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Jerrold Petrofsky, PhD
Professor, Physical Therapy
School of Allied Health Professions
Member, Physical Therapy, SAHP, Faculty of Graduate Studies
Publications    Scholarly Journals--Published
  • Petrofsky J S, Alshammari F, Lee H, Yim J E, Bains G, . . . Cavalcanti P. (2012). Electroencephalography to Assess Motor Control During Balance Tasks in People with Diabetes. Diabetes Technology & Therapeutics, 14(11), 1068-1076. ( 11/2012 ) Link...
    Background: Balance is sensed through peripheral and central receptors and mediated by central control through the brain and spinal cord. Although some evidence exists as to the areas of the brain involved and how processing of data occurs in young individuals, nothing has been published on people with diabetes. The purpose of this study was to examine the electroencephalogram (EEG) during common sensorimotor and balance training tasks and to relate these to task difficulty. Subjects and Methods: Postural sway and EEG change of alpha, beta, and sigma wave bands were measured in 17 young subjects, 10 older subjects, and 10 subjects with diabetes during eight progressively more difficult balance tasks with eyes open and closed, feet in tandem or apart, and on foam or a firm surface. Results: EEG power of beta and sigma wave bands showed significant increases on the cortical and parietal areas of the brain relative to the control tasks when eyes were open (P < 0.05). The cortical involvement decreased as the task became more difficult with vision and somatosensory information reduced, whereas that of the parietal area increased with task difficulty. The greatest increase was in subjects with diabetes, and the least was in younger people. Individuals with diabetes had increased sigma and beta EEG power in all regions of the brain examined with increased complexity of the balance task. Conclusions: This study demonstrated cortical and parietal involvement in static balance tasks commonly used in sensorimotor training. The results support the proposal that there was increased subcortical control with increase in task difficulty in the young subjects, but in subjects with diabetes, there was a major increase in activity across the brain.
  • Petrofsky J S, & Berk L. (2012). Response to "Thermography, Therapeutic Exercise, and Individuals with Diabetes". Diabetes Technology & Therapeutics, 14(10), 969-970. ( 10/2012 ) Link...
  • Yim J, Petrofsky J, Berk L, Daher N, Lohman E, Moss A, & Cavalcanti P. (2012). Protective effect of anti-oxidants on endothelial function in young Korean-Asians compared to Caucasians. Medical Science Monitor, 18(8), CR467-CR479. ( 8/2012 )
    Background: Previous studies show that Asians have an impaired blood flow response (BFR) to occlusion after a single high fat (HF) meal. The mechanism is believed to be the presence and susceptibility to high free radicals in their blood. The free radical concentration after a HF meal has not been examined in Asians. Further the BFR to heat after a single HF meal in Koreans has not been measured. Material/Methods: This study evaluated postprandial endothelial function by measuring the BFR to vascular occlusion and local heat before and after a HF meal and the interventional effects of anti-oxidant vitamins on improving endothelial function in young Korean-Asians (K) compared to Caucasians (C) with these assessments. Ten C and ten K participated in the study (mean age 25.3 +/- 3.6 years old). BFR to vascular occlusion and local heat and oxidative stress were assessed after a single low fat (LF) and HF meal at 2 hours compared to baseline. After administration of vitamins (1000 mg of vitamin C, 800 IU of vitamin E, and 300 mg of Coenzyme Q-10) for 14 days, the same measurements were made. Results: This study showed that the skin BFR to vascular occlusion and local heat following a HF meal significantly decreased and free radicals significantly increased at 2 hours compared to baseline in K (p<.001), but not in C. When vitamins were given, the BFR to vascular occlusion and local heat before and after HF meal were not significantly different in K and C. Conclusions: These findings suggest that even a single HF meal can reduce endothelial response to stress through an oxidative stress mechanism but can be blocked by antioxidants, probably through scavenging free radicals in K. Since endothelial function improved even before a HF meal in K, endothelial damage from an Americanized diet may be reduced in K by antioxidants.
  • Yim J, Petrofsky J, Berk L, Daher N, & Lohman E. (2012). Differences in endothelial function between Korean-Asians and Caucasians. Medical Science Monitor, 18(6), CR337-CR343. ( 6/2012 )
    Background: The vascular endothelium plays an integral role in maintaining vascular homeostasis, including the regulation of blood flow, vascular tone, and platelet aggregation. The aim of this study was to see if there were any differences in endothelial function between Koreans and Caucasians. Material/Methods: This was accomplished by 2 measures of endothelial function the response to local heat and the response to vascular occlusion. Ten Caucasian and 10 Korean male and female subjects participated (<35 years old). Endothelial function was assessed by the skin blood flow response to local heat using a thermode for 6 minutes at 3 temperatures (38 degrees C, 40 degrees C and 42 degrees C) and by vascular occlusion for 4 minutes followed by release and measurement of skin blood flow for 2 minutes. Results: When applying 6 minutes of local heat at 3 different temperatures (38 degrees C, 40 degrees C, and 42 degrees C), the skin blood flows were significantly higher for all temperatures in Caucasians as compared with Koreans, with peak blood flow of 223 +/- 48.1, 413.7 +/- 132.1, and 517.4 +/- 135.8 flux in Caucasians and 126.4 +/- 41.3, 251 +/- 77.9, and 398 +/- 97.2 flux in Koreans, respectively (p=0.001). Results of this study support the idea that the skin blood flow response to occlusion was significantly higher in Caucasians (peak 411.9 +/- 88.9 flux) than Koreans (peak 332.4 +/- 75.8 flux) (p=0.016). Conclusions: These findings suggest that Koreans may have lower endothelial function than Caucasians, which may be explained, in part, by genetic variations between the 2 ethnic groups.
  • Petrofsky J S. (2012). Resting blood flow in the skin: does it exist, and what is the influence of temperature, aging, and diabetes?. J Diabetes Sci Technol, 6(3), 674-85. ( 5/2012 )
    Measurement of resting blood flow to the skin and other organs is an important indicator of health and disease and a way to assess the reaction to various stimuli and pharmaceutical interventions. However, unlike plasma ions such as sodium or potassium, it is difficult to determine what the proper value for resting blood flow really is. Part of the problem is in the measurement of blood flow; various techniques yield very different measures of skin blood flow even in the same area. Even if there were common techniques, resting blood flow to tissue, such as the skin, is determined by the interaction of a plurality of factors, including the sympathetic nervous system, temperature, pressure, shear forces on blood vessels, tissue osmolality, and a variety of other stimuli. Compounding this variability, the blood flow response to any stressor is reduced by free radicals in the blood and diminished by aging and diabetes. Race also has an effect on resting blood flow to the skin. All these factors interact to make the exact resting blood flow difficult to determine in any one individual and at any one time. This review examines the main techniques to assess blood flow, the factors that alter blood flow in the skin, and how aging and diabetes affect blood flow. Recommendations for the measurement of resting blood flow are presented.
  • Petrofsky J S, Berk L, Alshammari F, Lee H, Hamdan A, . . . Al-Nakhli H. (2012). The interrelationship between air temperature and humidity as applied locally to the skin: the resultant response on skin temperature and blood flow with age differences. Med Sci Monit, 18(4), CR201-8. ( 4/2012 )
    BACKGROUND: Most studies of the skin and how it responds to local heat have been conducted with either water, thermodes, or dry heat packs. Very little has been accomplished to look at the interaction between air humidity and temperature on skin temperature and blood flow. With variable air temperatures and humidity's around the world, this, in many ways, is a more realistic assessment of environmental impact than previous water bath studies. MATERIAL/METHODS: Eight young and 8 older subjects were examined in an extensive series of experiments where on different days, air temperature was 38, 40, or 42 degrees C. and at each temperature, humidity was either 0%, 25%, 50%, 75%, or 100% humidity. Over a 20 minute period of exposure, the response of the skin in terms of its temperature and blood flow was assessed. RESULTS: For both younger and older subjects, for air temperatures of 38 and 40 degrees C., the humidity of the air had no effect on the blood flow response of the skin, while skin temperature at the highest humidity was elevated slightly. However, for air temperatures of 42 degrees C., at 100% humidity, there was a significant elevation in skin blood flow and skin temperature above the other four air humidity's (p<0.05). In older subjects, the blood flow response was less and the skin temperature was much higher than younger individuals for air at 42 degrees C. and 100% humidity (p<0.05). CONCLUSIONS: Thus, in older subjects, warm humid air caused a greater rise in skin temperature with less protective effect of blood flow to protect the skin from overheating than is found in younger subjects.
  • Petrofsky J S, Berk L, Alshammari F, Lee H, Hamdan A, . . . Al-Nakhli H. (2012). The interrelationship between air temperature and humidity as applied locally to the skin: The resultant response on skin temperature and blood flow with age differences. Medical Science Monitor, 18(4), CR201-CR208. ( 4/2012 )
    Background: Most studies of the skin and how it responds to local heat have been conducted with either water, thermodes, or dry heat packs. Very little has been accomplished to look at the interaction between air humidity and temperature on skin temperature and blood flow. With variable air temperatures and humidity's around the world, this, in many ways, is a more realistic assessment of environmental impact than previous water bath studies. Material/Methods: Eight young and 8 older subjects were examined in an extensive series of experiments where on different days, air temperature was 38, 40, or 42 degrees C. and at each temperature, humidity was either 0%, 25%, 50%, 75%, or 100% humidity. Over a 20 minute period of exposure, the response of the skin in terms of its temperature and blood flow was assessed. Results: For both younger and older subjects, for air temperatures of 38 and 40 degrees C., the humidity of the air had no effect on the blood flow response of the skin, while skin temperature at the highest humidity was elevated slightly. However, for air temperatures of 42 degrees C., at 100% humidity, there was a significant elevation in skin blood flow and skin temperature above the other four air humidity's (p<0.05). In older subjects, the blood flow response was less and the skin temperature was much higher than younger individuals for air at 42 degrees C. and 100% humidity (p<0.05). Conclusions: Thus, in older subjects, warm humid air caused a greater rise in skin temperature with less protective effect of blood flow to protect the skin from overheating than is found in younger subjects.
  • Petrofsky J S, Berk L, Alshammari F, Lee H, Hamdan A, . . . Al-Nakhli H. (2012). The interrelationship between air temperature and humidity as applied locally to the skin: The resultant response on skin temperature and blood flow with age differences. Medical Science Monitor, 18(4), CR201-CR208. ( 4/2012 )
    Background: Most studies of the skin and how it responds to local heat have been conducted with either water, thermodes, or dry heat packs. Very little has been accomplished to look at the interaction between air humidity and temperature on skin temperature and blood flow. With variable air temperatures and humidity's around the world, this, in many ways, is a more realistic assessment of environmental impact than previous water bath studies. Material/Methods: Eight young and 8 older subjects were examined in an extensive series of experiments where on different days, air temperature was 38, 40, or 42 degrees C. and at each temperature, humidity was either 0%, 25%, 50%, 75%, or 100% humidity. Over a 20 minute period of exposure, the response of the skin in terms of its temperature and blood flow was assessed. Results: For both younger and older subjects, for air temperatures of 38 and 40 degrees C., the humidity of the air had no effect on the blood flow response of the skin, while skin temperature at the highest humidity was elevated slightly. However, for air temperatures of 42 degrees C., at 100% humidity, there was a significant elevation in skin blood flow and skin temperature above the other four air humidity's (p<0.05). In older subjects, the blood flow response was less and the skin temperature was much higher than younger individuals for air at 42 degrees C. and 100% humidity (p<0.05). Conclusions: Thus, in older subjects, warm humid air caused a greater rise in skin temperature with less protective effect of blood flow to protect the skin from overheating than is found in younger subjects.
  • Al-Nakhli H H, Petrofsky J S, Laymon M S, Arai D, Holland K, & Berk L S. (2012). The Use of Thermal Infrared Imaging to Assess the Efficacy of a Therapeutic Exercise Program in Individuals with Diabetes. Diabetes Technology & Therapeutics, 14(2), 159-167. ( 2/2012 ) Link...
    Background: Exercise is of great value for individuals with diabetes in helping to control their hemoglobin A1c levels and in increasing their insulin sensitivity. Delayed-onset muscle soreness (DOMS) is a common problem in healthy individuals and in people who have diabetes. People with diabetes are also faced with metabolic and endothelial impairments, which could make DOMS even worse. But because they usually have neuropathies, they may not feel this soreness appropriately, leading to premature return to exercise and causing further injuries. Research Design: One hundred eighteen subjects participated in this study and were divided into four groups. Two groups (healthy and diabetes) performed a series of abdominal exercises, and the other two groups (healthy and diabetes) performed a series of arm exercises to induce DOMS. Skin temperature above the muscle was assessed using a thermal infrared camera, and perceived soreness of the exercised muscle was assessed using a 100-mm visual analog scale. Serum myoglobin concentrations were also measured. Results: There was a significant increase in skin temperature 24 h post-exercise for all four exercise groups (P < 0.05), where the combined average increase in skin temperature for all four groups was approximately 0.65 degrees C from baseline. Also, 24 h post-exercise, all four groups were significantly sorer than they were at baseline (P < 0.05). Serum myoglobin levels were also significantly higher on day 3 compared with day 1 (P < 0.05). Conclusion: Infrared thermal imaging may be a valuable technique of seeing which muscles are sore hours or even days after the exercise is over. Thus, thermal imaging would be an efficient and painless way of looking at DOMS in both healthy individuals and individuals who have diabetes, even if they are facing neurological problems.
  • Petrofsky J, Berk L, Alshammari F, Lee H, Hamdan A, . . . Al-Nakhli H. (2012). The Effect of Moist Air on Skin Blood Flow and Temperature in Subjects With and Without Diabetes. Diabetes Technology & Therapeutics, 14(2), 105-116. ( 2/2012 ) Link...
    Background: Endothelial function is known to be impaired in response to heat in people with diabetes, but little has been done to see how air humidity alters the skin blood flow response to heat. Methods: Seventeen male and female subjects were divided in two groups, one with type 2 diabetes and the other the control subjects without diabetes, age-matched to the diabetes group. All subjects participated in a series of experiments to determine the effect of the warming of the skin by air on skin temperature and skin blood flow. On different days, skin temperature was warmed with air that was 38 degrees C, 40 degrees C, or 42 degrees C for 20 min. Also, on different days, at each temperature, the air humidity was adjusted to 0%, 25%, 50%, 75%, or 100% humidity. Skin blood flow and temperature were measured throughout the exposure period. This allowed the interactions between air humidity and temperature to be assessed. Results: For the control subjects, the moisture in the air had no different effect on skin blood flow at air temperatures of 38 degrees C and 40 degrees C (analysis of variance, P > 0.05), although skin blood flow progressively increased at each air temperature that was applied. But for the warmest air temperature, 42 degrees C, although the four lower humidities had the same effect on skin blood flow, air at 100% humidity caused the largest increase in skin blood flow. In contrast, in the subjects with diabetes, blood flow was always significantly less at any air temperature applied to the skin than was observed in the control subjects (P < 0.05), and skin blood flow was significantly higher for the two higher humidities for the two higher air temperatures. Skin temperature paralleled these findings. Conclusion: These data show that individuals with diabetes do not tolerate moist, warm air above 50% humidity as well as controls without diabetes.
  • Petrofsky J S, Alshahmmari F, Lee H, Hamdan A, Yim J E, . . . Desai R. (2012). Reduced endothelial function in the skin in Southeast Asians compared to Caucasians. Med Sci Monit, 18(1), CR1-8. ( 1/2012 )
    BACKGROUND: The reaction of vascular endothelial cells to occlusion and heat in Southeast Asian Indians (SAI) compared to Caucasians (C) has not been studied, although genetic differences are found in endothelial cells between the races. MATERIAL/METHODS: Ten C and Ten SAI (<35 years old) male and female subjects participated. There was no difference in the demographics of the subjects except that the SAI group had been in the United States for 6 months; C was natives to the US. Endothelial function was assessed by the response of the circulation (BF) to local heating and the response to vascular occlusion. The effects of local heat on circulation in the skin on the forearm was assessed by applying heat for 6 minutes at temperatures, 38, 40 and 42 degrees C on 3 separate days. On different days, vascular occlusion was applied for 4 minutes to the same arm and skin blood flow was measured for 2 minutes after occlusion; skin temperature was either 31 degrees C or 42 degrees C. RESULTS: When occlusion was applied at a skin temperature of 31 degrees C, the BF response to occlusion was significantly lower in the SAI cohort compared to C (peak BF C = 617 +/- 88.2 flux, SAE = 284 +/- 73 flux). The same effect was seen at skin temperatures of 42 degrees C. The circulatory response to heat was also significantly less in SAI compared to C at each temperature examined (p<0.05)(for temperatures of 38, 40 and 42 degrees C, peak blood flow for C was 374.7 +/- 81.2, 551.9 +/- 91.3 and 725.9 +/- 107 flux respectively and 248.5 +/- 86.2, 361.4 +/- 104.3 and 455.3 +/- 109.7 flux respectively for SAI. (p<0.05). CONCLUSIONS: Thus there seems to be big differences in these 2 populations in endothelial response to these stressors. The difference may be due to genetic variations between the 2 groups of subjects.
  • Petrofsky J S, Alshammari F, Lee H, Hamdan A, Yim J E, . . . Desai R. (2012). Reduced endothelial function in the skin in Southeast Asians compared to Caucasians. Medical Science Monitor, 18(1), CR1-CR8. ( 1/2012 )
    Background: The reaction of vascular endothelial cells to occlusion and heat in Southeast Asian Indians (SAI) compared to Caucasians (C) has not been studied, although genetic differences are found in endothelial cells between the races. Material/Methods: Ten C and Ten SAI (<35 years old) male and female subjects participated. There was no difference in the demographics of the subjects except that the SAT group had been in the United States for 6 months; C was natives to the US. Endothelial function was assessed by the response of the circulation (BF) to local heating and the response to vascular occlusion. The effects of local heat on circulation in the skin on the forearm was assessed by applying heat for 6 minutes at temperatures, 38, 40 and 42 degrees C on 3 separate days. On different days, vascular occlusion was applied for 4 minutes to the same arm and skin blood flow was measured for 2 minutes after occlusion; skin temperature was either 31 degrees C or 42 degrees C. Results: When occlusion was applied at a skin temperature of 31 degrees C, the BF response to occlusion was significantly lower in the SAT cohort compared to C (peak BF C=617+/-88.2 flux, SAE=284+/-73 flux). The same effect was seen at skin temperatures of 42 degrees C. The circulatory response to heat was also significantly less in SAI compared to C at each temperature examined (p<0.05) (for temperatures of 38,40 and 42 degrees C, peak blood flow for C was 374.7+/-81.2, 551.9+/-91.3 and 725.9+/-107 flux respectively and 248.5+/-86.2, 361.4+/-104.3 and 455.3+/-109.7 flux respectively for SAI. (p<0.05). Conclusions: Thus there seems to be big differences in these 2 populations in endothelial response to these stressors. The difference may be due to genetic variations between the 2 groups of subjects.
  • Al-Nakhli H H, Petrofsky J S, Laymon M S, & Berk L S. (2012). The use of thermal infra-red imaging to detect delayed onset muscle soreness. J Vis Exp, (59), . ( 0/2012 ) Link...
    Delayed onset muscle soreness (DOMS), also known as exercise induced muscle damage (EIMD), is commonly experienced in individuals who have been physically inactive for prolonged periods of time, and begin with an unexpected bout of exercise, but can also occur in athletes who exercise beyond their normal limits of training. The symptoms associated with this painful phenomenon can range from slight muscle tenderness, to severe debilitating pain. The intensity of these symptoms and the related discomfort increases within the first 24 hours following the termination of the exercise, and peaks between 24 to 72 hours post exercise. For this reason, DOMS is one of the most common recurrent forms of sports injury that can affect an individual's performance, and become intimidating for many. For the last 3 decades, the DOMS phenomenon has gained a considerable amount of interest amongst researchers and specialists in exercise physiology, sports, and rehabilitation fields. There has been a variety of published studies investigating this painful occurrence in regards to its underlying mechanisms, treatment interventions, and preventive strategies. However, it is evident from the literature that DOMS is not an easy pathology to quantify, as there is a wide amount of variability between the measurement tools and methods used to quantify this condition. It is obvious that no agreement has been made on one best evaluation measure for DOMS, which makes it difficult to verify whether a specific intervention really helps in decreasing the symptoms associated with this type of soreness or not. Thus, DOMS can be seen as somewhat ambiguous, because many studies depend on measuring soreness using a visual analog scale (VAS), which is a subjective rather than an objective measure. Even though needle biopsies of the muscle, and blood levels of myofibre proteins might be considered a gold standard to some, large variations in some of these blood proteins have been documented, in addition to the high risks sometimes associated with invasive techniques. Therefore, in the current investigation, we tested a thermal infra-red (IR) imaging technique of the skin above the exercised muscle to detect the associated muscle soreness. Infra-red thermography has been used, and found to be successful in detecting different types of diseases and infections since the 1950's. But surprisingly, near to nothing has been done on DOMS and changes in skin temperature. The main purpose of this investigation was to examine changes in DOMS using this safe and non-invasive technique.
  • Petrofsky J, Berk L, & Al-Nakhli H. (2012). The Influence of Autonomic Dysfunction Associated with Aging and Type 2 Diabetes on Daily Life Activities. Experimental Diabetes Research, , . ( 0/2012 ) Link...
    Type 2 diabetes (T2D) and ageing have well documented effects on every organ in the body. In T2D the autonomic nervous system is impaired due to damage to neurons, sensory receptors, synapses and the blood vessels. This paper will concentrate on how autonomic impairment alters normal daily activities. Impairments include the response of the blood vessels to heat, sweating, heat transfer, whole body heating, orthostatic intolerance, balance, and gait. Because diabetes is more prevalent in older individuals, the effects of ageing will be examined. Beginning with endothelial dysfunction, blood vessels have impairment in their ability to vasodilate. With this and synaptic damage, the autonomic nervous system cannot compensate for effectors such as pressure on and heating of the skin. This and reduced ability of the heart to respond to stress, reduces autonomic orthostatic compensation. Diminished sweating causes the skin and core temperature to be high during whole body heating. Impaired orthostatic tolerance, impaired vision and vestibular sensing, causes poor balance and impaired gait. Overall, people with T2D must be made aware and counseled relative to the potential consequence of these impairments.
  • Lohman E B, Bains G S, Lohman T, DeLeon M, & Petrofsky J S. (2011). A comparison of the effect of a variety of thermal and vibratory modalities on skin temperature and blood flow in healthy volunteers. Medical Science Monitor, 17(9), MT72-MT81. ( 9/2011 )
    Background: Circulation plays an essential role in tissue healing. Moist heat and warm water immersion have been shown to increase skin circulation; however, these heating modalities can cause burns. Recent research has shown that passive vibration can also increase circulation but without the risk of burns. Material/Methods: The aim of this study is to compare the effects of short-duration vibration, moist heat, and a combination of the two on skin blood flow (SBF) and skin temperature (ST). Ten (10) subjects, 5 female and 5 male, aged 20-30 years of age, received two interventions a day for 3 consecutive days: Intervention 1 - Active vibration only (vibration exercise), Intervention 2 - passive vibration only, Intervention 3 - moist heat only, Intervention 4 - passive vibration combined with moist heat, Intervention 5 - a commercial massaging heating pad, and Intervention 6 - no intervention, resting in supine only (control). SBF and ST were measured using a laser Doppler imager during the 10 minute intervention and then throughout the nine minute recovery period. Results: The mean skin blood flow following a ten-minute intervention of the combination of passive vibration and moist heat was significantly different from the control, active vibration, and the commercial massaging heating pad. Skin temperature following the ten-minute interventions of moist heat alone and passive vibration alone were both significantly different from the commercial massaging heating pad and active vibration interventions. Conclusions: The combination of passive vibration and moist heat produced the greatest increase in skin blood flow and the second highest increase in skin blood flow nine minutes post application.
  • Petrofsky J. (2011). A method of measuring the interaction between skin temperature and humidity on skin vascular endothelial function in people with diabetes. J Med Eng Technol, 35(6-7), 330-7. ( 8/2011 ) Link...
    BACKGROUND: A core defect in people with Type 2 Diabetes is endothelial dysfunction. This defect permeates all organ systems in the body including the ability of the skin to protect itself from thermal injuries by an appropriate increase in skin circulation. Most studies on the local response to heating have been done with dry heat sources. Recent data show that endothelial function is improved in people with diabetes with moist heat. Little is known about 'how' moist heat must be or the mechanisms on why moist heat triggers a better blood flow response than dry heat. METHODS: In the present investigation, a device was developed to provide variable temperature air and variable humidity as an aid to study the dynamics of the skin circulatory response to heat in people with diabetes. The device consisted of a water bath used to heat air and an air dryer and air bubbler to generate dry and moist air, respectively, at a fixed temperature. The air could then be mixed and the temperature stabilized to produce a variable temperature and humidity air source to expose the skin to in people with diabetes. RESULTS: The device was validated at different air temperatures and humidities and tested on four subjects to assess operation. The air flows, temperatures and humilities were stable with less than a 5% coefficient of variation. CONCLUSIONS: Testing on humans showed that there appeared to be a linear relationship between air humidity and blood flow at a given air temperature exposed to the skin.
  • Song C H, Petrofsky J S, Lee S W, Lee K J, & Yim J E. (2011). Effects of an Exercise Program on Balance and Trunk Proprioception in Older Adults with Diabetic Neuropathies. Diabetes Technology & Therapeutics, 13(8), 803-811. ( 8/2011 ) Link...
    Background: Diabetes is the most common cause of peripheral neuropathies. No definitive treatment for diabetic neuropathies has been reported, and very few studies have been published on the role of exercise in reducing either the symptoms or incidence of diabetic neuropathies. Methods: This study assessed the effects of an exercise program on balance and trunk proprioception in older adults with diabetic neuropathies. Thirty-eight patients with diabetes having peripheral neuropathies were enrolled, randomized, and subdivided in two groups: an experimental group of 19 participants with diabetes (72.9 +/- 5.6 years old) and a control group of 19 participants with diabetes (73.2 +/- 5.4 years old). Both groups received health education on diabetes for 50 min/week for 8 weeks. The experimental group practiced an additional balance exercise program for 60 min, two times a week. The exercise training was performed two times per week for 8 weeks. Results were evaluated by both static and dynamic balance and trunk proprioception. Results: Postural sway significantly decreased (P < 0.05), the one-leg stance test significantly increased (P < 0.05), and dynamic balance from the Berg Balance Scale, Functional Reach Test, Timed Up and Go test, and 10-m walking time improved significantly after balance exercise (P < 0.05). Trunk repositioning errors also decreased with training (P < 0.05). Conclusion: The balance exercise program improved balance and trunk proprioception. These results suggested that a balance exercise is suitable for individuals with diabetic neuropathy.
  • Petrofsky J, Alshahmmari F, Yim J E, Hamdan A, Lee H, . . . Desai R. (2011). The interrealtionship between locally applied heat, ageing and skin blood flow on heat transfer into and from the skin. J Med Eng Technol, 35(5), 262-74. ( 7/2011 ) Link...
    In response to a thermal stress, skin blood flow (BF) increases to protect the skin from damage. When a very warm, noxious, heat source (44 degrees C) is applied to the skin, the BF increases disproportionately faster than the heat stress that was applied, creating a safety mechanism for protecting the skin. In the present investigation, the rate of rise of BF in response to applied heat at temperatures between 32 degrees C and 40 degrees C was examined as well as the thermal transfer to and from the skin with and without BF in younger and older subjects to see how the skin responds to a non-noxious heat source. Twenty male and female subjects (10 - 20-35 years, 10 - 40-70 years) were examined. The arms of the subjects were passively heated for 6 min with and without vascular occlusion by a thermode at temperatures of 32, 36, 38 or 40 degrees C. When occlusion was not used during the 6 min exposure to heat, there was an exponential rise in skin temperature and BF in both groups of subjects over the 6-min period. However, the older subjects achieved similar skin temperatures but with the expenditure of fewer calories from the thermode than was seen for the younger subjects (p<0.05). BF was significantly less in the older group than the younger group at rest and after exposure to each of the three warmest thermode temperatures (p<0.05). As was seen for noxious temperatures, after a delay, the rate of rise of BF at the three warmest thermode temperatures was faster than the rise in skin temperature in the younger group but less in the older group of subjects. Thus, a consequence of ageing is reduced excess BF in response to thermal stress increasing susceptibility to thermal damage. This must be considered in modelling of BF.
  • Petrofsky J, Batt J, Bollinger J N, Jensen M C, Maru E H, & Al-Nakhli H H. (2011). Comparison of Different Heat Modalities for Treating Delayed-Onset Muscle Soreness in People with Diabetes. Diabetes Technology & Therapeutics, 13(6), 645-655. ( 6/2011 ) Link...
    Background: Delayed-onset muscle soreness (DOMS) is a serious problem for people who do not exercise on a regular basis. Although the best preventive measure for diabetes and for maintaining a low hemoglobin A1c is exercise, muscle soreness is common in people with diabetes. For people with diabetes, DOMS is rarely reported in exercise studies. Research Design: One hundred twenty subjects participated in three groups (young, older, and type 2 diabetes) and were examined to evaluate the soreness in the abdominal muscles after a matched exercise bout using a p90x exercise video (Beachbody LLC, Los Angeles, CA) for core fitness. Next, three heating modalities were assessed on how well they could reduce muscle soreness: ThermaCare (R) (Pfizer Consumer Healthcare, Richmond, VA) heat wraps, hydrocollator heat wraps, and a chemical moist heat wrap. Results: The results showed that people with diabetes were significantly sorer than age-matched controls (P < 0.05). On a 100-mm VAS (100 mm = sorest), the average soreness for the people with diabetes was 73.3 +/- 16.2 mm, for the older group was 56.1 +/- 15.1 mm, and for the younger group was 41.5 +/- 9.3 mm; these differences were significant (analysis of variance, P < 0.05). The greatest reduction in soreness after applying the modalities was using moist heat, both immediately after the modality and up to 2 days after the exercise. Right after the modality, moist heat reduced pain by 52.3% in the older subjects compared with 30.5% in the subjects with diabetes and 33.3% in the younger subjects. Skin blood flow in the abdominal area before exercise was greatest in the younger subjects and lower in the subjects with diabetes after heat application. Skin temperature at rest and after exercise was greatest in the diabetes group. Conclusions: Muscle soreness following exercise was greatest in people with diabetes, and the best modality of the three studied to reduce this type of soreness was chemical moist heat.
  • Petrofsky J S. (2011). The effect of type-2-diabetes-related vascular endothelial dysfunction on skin physiology and activities of daily living. J Diabetes Sci Technol, 5(3), 657-67. ( 5/2011 )
    A common factor contributing to organ damage in type 2 diabetes mellitus (T2DM) is impaired tissue blood flow caused by damage to vascular endothelial cells (VECs). Damage can occur even before the clinical diagnosis of diabetes. It can be caused by both a high average blood glucose concentration and/or large daily spikes in blood glucose. While much of the present literature focuses on the damage to VECs and organs from these large glucose excursions, this review will focus on the consequence of this damage, that is, how endothelial cell damage in diabetes affects normal daily activities (e.g., exercise, reaction to typical stimuli) and various treatment modalities (e.g.. contrast baths and electrical stimulation therapy). It is important to understand the effects of VEC damage such as poor skin blood flow, compromised thermoregulation, and altered response to skin pressure in designing diabetes technologies as simple as heating pads and as complex as continuous glucose monitors. At the simplest level, people with diabetes have poor circulation to the skin and other organs. In the skin, even the blood flow response to locally applied pressure, such as during standing, is different than for people who do not have T2DM. Simple weight bearing on the foot can occlude the skin circulation. This makes the skin more susceptible to damage. In addition, endothelial damage has far-reaching effects on the whole body during normal activities of daily living, including an impaired response to local heat, such as hot packs and contrast baths, and higher body temperatures during whole body heating due to impaired blood flow and a reduced ability to sweat. Finally, because of multiple organ damage, people with T2DM have poor balance and gait and impaired exercise performance.
  • Petrofsky J, Paluso D, Anderson D, Swan K, Yim J E, . . . Katrak V. (2011). The contribution of skin blood flow in warming the skin after the application of local heat; the duality of the Pennes heat equation. Medical Engineering & Physics, 33(3), 325-329. ( 4/2011 ) Link...
    As predicted by the Pennes equation, skin blood flow is a major contributor to the removal of heat from an external heat source. This protects the skin from erythema and burns. But, for a person in a thermally neutral room, the skin is normally much cooler than arterial blood. Therefore, if skin blood flow (BF) increases, it should initially warm the skin paradoxically. To examine this phenomenon, 10 young male and female subjects participated in a series of experiments to examine the contribution of skin blood flow in the initial warming the skin after the application of local heat. Heat flow was measured by the use of a thermode above the brachioradialis muscle. The thermode was warmed by constant temperature water at 44 degrees C entering the thermode at a water flow rate of 100 cm(3)/min. Skin temperature was measured by a thermistor and blood flow in the underlying skin was measured by a laser Doppler imager in single point mode. The results of the experiments showed that, when skin temperature is cool (31-32 degrees C), the number of calories being transferred to the skin from the thermode cannot account for the rise in skin temperature alone. A significant portion of the rise in skin temperature is due to the warm arterialized blood traversing the skin from the core areas of the body. However, as skin temperature approaches central core temperature, it becomes less of a heat source and more of a heat sync such that when skin temperature is at or above core temperature, the blood flow to the skin, as predicted by Pennes, becomes a heat sync pulling heat from the thermode. (C) 2010 IPEM. Published by Elsevier Ltd. All rights reserved.
  • Petrofsky J, Paluso D, Anderson D, Swan K, Alshammari F, . . . Yim J E. (2011). The Ability of Different Areas of the Skin to Absorb Heat from a Locally Applied Heat Source: The Impact of Diabetes. Diabetes Technology & Therapeutics, 13(3), 365-372. ( 3/2011 ) Link...
    Background: When heat is applied to the skin, heat is conducted away because of the latent heat transfer properties of the skin and an increase in skin circulation, but little attention has been paid to the heat transfer properties of skin in different areas of the body and in people with diabetes. Research Design: Thirty subjects in the age range of 20-75 years had a thermode (44 degrees C) applied to the skin of their arm, leg, foot, and back for 6 min to assess the heat transfer characteristics of skin in these four areas of the body. Skin blood flow and skin temperature were monitored over the 6-min period. Results: For the younger subjects, blood flow was not statistically different in response to heat in three areas of the body, starting at less than 200 flux measured by a laser Doppler imager and ending at approximately 1,200 flux after heat exposure. The foot had higher resting blood flow and higher blood flow in response to heat. Temperature and the rate of rise of temperature were also not different in any of the areas. The heat added to raise temperature, however, varied by body region. The arm required the least, whereas the leg and foot required the most. For the older group and subjects with diabetes, the heat required for any region of the body was much less to achieve the same increase in skin temperature, and blood flows were also much less; the subjects with diabetes showed the least blood flow and required the fewest calories to heat the skin. Whereas the foot required the greatest number of calories to heat the tissue in younger and older subjects, in subjects with diabetes, the foot took proportionally fewer calories. Conclusion: Thus, specific areas of the body are damaged more by diabetes than other areas.
  • Petrofsky J, Goraksh N, Alshammari F, Mohanan M, Soni J, . . . Katrak V. (2011). The ability of the skin to absorb heat; the effect of repeated exposure and age. Med Sci Monit, 17(1), CR1-8. ( 1/2011 )
    BACKGROUND: When heat is applied to the skin, it is dissipated due to conductive heat flow in the tissue and the blood. While heat flow has been studied after applying a single heat exposure, the physiology of repeated exposures to local heat has not been well investigated. MATERIAL/METHODS: Twenty male and female subjects in the age range of 20-65 years old participated in a series of experiments during which a thermode was placed on their leg above the quadriceps muscle for 20 minutes, and on 3 sequential days, to see the effect of repeated local heat on skin blood flow, skin temperature, and on caloric transfer from a thermode used to raise skin temperature. RESULTS: The results of the experiment showed that, for young subjects, to raise skin temperature to 40 degrees C required more than double the calories required in older subjects. Further, in the younger subjects, the blood flow response in the first 20 minutes of heat exposure was over 30% higher than that seen in the older subjects. However, on the 2nd and 3rd day, the blood flow response of the younger subjects, was not significantly different between day 2 and 3, but was significantly less than day 1. There was no statistical difference in the blood flow response between day 1, 2 and 3 in the older subjects. In the younger subjects, in the 2 and 3rd day, the number of calories needed to warm the skin was also significantly less than that seen in the first day. CONCLUSIONS: In younger subjects but not older subjects, there appears to be some degree of acclimatization with an enhanced blood flow response in the first day that was protective to the skin which was not seen in repeated heat exposure.
  • Petrofsky J, Goraksh N, Alshammari F, Mohanan M, Soni J, . . . Katrak V. (2011). The ability of the skin to absorb heat; The effect of repeated exposure and age. Medical Science Monitor, 17(1), CR1-CR8. ( 1/2011 )
    Background: When heat is applied to the skin, it is dissipated due to conductive heat flow in the tissue and the blood. While heat flow has been studied after applying a single heat exposure, the physiology of repeated exposures to local heat has not been well investigated. Material/Methods: Twenty male and female subjects in the age range of 20-65 years old participated in a series of experiments during which a thermode was placed on their leg above the quadriceps muscle for 20 minutes, and on 3 sequential days, to see the effect of repeated local heat on skin blood flow, skin temperature, and on caloric transfer from a thermode used to raise skin temperature. Results:The results of the experiment showed that, for young subjects, to raise skin temperature to 40 degrees C required more than double the calories required in older subjects. Further, in the younger subjects, the blood flow response in the first 20 minutes of heat exposure was over 30% higher than that seen in the older subjects. However, on the 2nd and 3rd day, the blood flow response of the younger subjects, was not significantly different between day 2 and 3, but was significantly less than day 1. There was no statistical difference in the blood flow response between day 1, 2 and 3 in the older subjects. In the younger subjects, in the 2 and 3(rd) day, the number of calories needed to warm the skin was also significantly less than that seen in the first day. Conclusions: In younger subjects but not older subjects, there appears to be some degree of acclimatization with an enhanced blood flow response in the first day that was protective to the skin which was not seen in repeated heat exposure.
  • Petrofsky J, Lee H, Trivedi M, Hudlikar A N, Yang C H, . . . Katrak V. (2010). The Influence of Aging and Diabetes on Heat Transfer Characteristics of the Skin to a Rapidly Applied Heat Source. Diabetes Technology & Therapeutics, 12(12), 1003-1010. ( 12/2010 ) Link...
    Background: Numerous studies have examined the blood flow of the skin at rest and in response to sustained heat and shown that, in older people and people with diabetes, the skin blood flow response to heat is diminished compared to younger people. It is not sustained heat, however, that usually causes burns; it is a more rapid application of heat. Subjects and Methods: Ten younger subjects, 10 older subjects, and 10 subjects with diabetes were examined before and after applying a water-filled thermode to the skin above the quadriceps muscle to observe the changes in skin temperature and skin blood flow and the ability of the skin to absorb heat after a 2-min heat exposure with water at 44 degrees C. Results: Skin temperature rose from 31.2 degrees C at rest to 38.3 degrees C after 2 min of heat application in all subjects (P>0.05 between groups). The calories required in the younger group of subjects was 2.26 times the calories required in the older group of subjects for the same change in skin temperature and 13.8 times the calories needed to increase skin temperature in the subjects with diabetes. Furthermore, the blood flow at rest was lower in people with diabetes than older subjects and both groups less than that seen in younger subjects. The blood flow response to heat was slower in the subjects with diabetes compared to the older subjects and much slower than that seen in the younger subjects. Conclusions: Reduced skin blood flow of older and subjects with diabetes, decreased thickness of the dermal layer, and increased subcutaneous fat, as well as damage to transient receptor potential vanilloid 1 receptors, may account for some of the differences between the groups.
  • Mousavi S A, Hashemipour M, Sadeghi M, Petrofsky J S, & Prowse M A. (2010). A FUZZY LOGIC CONTROL SYSTEM FOR THE ROTARY DENTAL INSTRUMENTS. Iranian Journal of Science and Technology Transaction B-Engineering, 34(B5), 539-551. ( 10/2010 )
    Nickel-titanium alloy (Ni-Ti) rotary dental instrument files are devices which are commonly used in the field of endodontics for root canal preparation. However, Ni-Ti file breakage is common and is often caused by excessive hand pressure by the endodontist during a root canal preparation. The present solution is to automate the control of file failure (caused by pressure) through the development of a fuzzy logic controller to maintain the file breakage. Both in vitro and in vivo experiments were conducted to gather enough data to observe the system behavior and to modify the control system. In vivo results showed that a fuzzy logic control system was able to improve the file life up to 22% compared to existing rotary instrument control systems. Thus the fuzzy logic system presented in this paper not only improves the filing process performance, but reduced the time and costs spent by the endodontist as well through maximizing the use of file life and preventing file failures with the use of an applied intelligent control system.
  • Petrofsky J S. (2010). A Device to Measure Heat Flow Through the Skin in People with Diabetes. Diabetes Technology & Therapeutics, 12(9), 737-743. ( 9/2010 ) Link...
    Introduction: As people age, and especially for older people with diabetes, there is increased susceptibility to burns. However, this is not true for all older people or all people with diabetes. The factors that predict burn susceptibility in specific members of the population with diabetes have not been elucidated. To understand the heat transfer properties of the skin in different parts of the body and how it is altered by skin blood flow, age, and glycemic control, a new device was developed. Methods: The device was a Plexiglas (R) (Arkema, Colombes, France) capsule (thermode) that has a footprint on the skin of 20 cm 2, with the side contacting the skin made of thin brass. The thermode was machined to allow the free flow of water through the interior with the exception of a small hole for a laser Doppler flow meter to assess blood flow under the capsule. Flow directors kept the water flow even on the under surface of the capsule and minimized turbulent flow until high water flow rates are forced through the capsule. Results: When tested, the device provided even heat on the brass surface and could show the movement of heat into the skin and the corresponding changes in skin blood flow and temperature. In limited testing, clear differences were seen in heat flux in people with diabetes versus controls. Conclusion: This device might be very useful in determining the early onset of diabetes-related skin damage. Future studies should include examining different regions of the body and variables such as hemoglobin A1c.
  • Petrofsky J S, Focil N, Prowse M, Kim Y, Berk L, Bains G, & Lee S. (2010). Autonomic Stress and Balance-the Impact of Age and Diabetes. Diabetes Technology & Therapeutics, 12(6), 475-481. ( 6/2010 ) Link...
    Introduction: Balance is impaired in the elderly and people with diabetes. However, the effect of attempted balance on the autonomic nervous system has not been investigated. Methods: Ten control subjects, 10 subjects with type 2 diabetes (age range, 21-75 years), and 10 older subjects age-matched to the subjects with diabetes were examined to determine the effect of diabetes and age on balance and the associated autonomic stress. Subjects were asked to stand on a balance platform for 1-min periods under four conditions: (1) quiet standing, (2) quiet standing with eyes closed, (3) quiet standing eyes closed with the platform allowed to move side to side over a central pivot that allows the edge of the platform to rotate 4 inches up and down, and (4) the same platform with eyes closed. Blood pressure, electrocardiogram, and sway were recorded. Results: Balance was worst in the subjects with diabetes, while the cardiovascular stress, as assessed by both heart rate and blood pressure, was greatest in the older group of subjects. But subjects with diabetes, while having a greater blood pressure response to the stress induced by balance, showed a poor heart rate response, probably due to diabetes-induced autonomic damage. Conclusion: Autonomic damage in the subjects with diabetes masked much of the stress of the inability to optimize balance in this population.
  • Petrofsky J S, Lawson D, Berk L, & Suh H. (2010). Enhanced healing of diabetic foot ulcers using local heat and electrical stimulation for 30 min three times per week. Journal of Diabetes, 2(1), 41-46. ( 3/2010 ) Link...
    Background: Electrical stimulation (ES) with heating is effective in healing chronic wounds. However, it this effect due to ES alone or both heating and ES? The aim of the present study was to deduce the individual roles of heat and ES in the healing of chronic wounds. Methods: The study was performed on 20 patients (mean age 48.4 +/- 14.6 years) with non-healing diabetic foot ulcers (mean duration 38.9 +/- 23.7 months) who received local dry heat (37 degrees C; n = 10) or local dry heat + ES (n = 10) three times a week for 4 weeks. Patients were given ES using biphasic sine wave stimulation (30 Hz, pulse width 250 mu s, current approximately 20 mA). Results: Skin blood flow in and around the wound was measured with a laser Doppler flow imager. In the ES + heat group, the average wound area and volume decreased significantly by 68.4 +/- 28.6% and 69.3 +/- 27.1%, respectively (both P < 0.05), over the 1-month period. During the average session, blood flow increased to 102.3 +/- 25.3% with local heat and to 152.3 +/- 23.4% with ES + heat. In the group receiving treatment with local heat only, wounds that had not healed for at least 2 months showed 30.1 +/- 22.6% healing (i.e. a decrease in wound area) after 1 month. Although this level of healing was significant, it was less than that observed in the ES + heat group (P < 0.05). Conclusions: Local dry heat and ES work well together to heal chronic diabetic foot wounds; however, local heat would appear to be a relevant part of this therapy because ES alone has produced little healing in previous studies.
  • Bui C, Petrofsky J, Berk L, Shavlik D, Remigio W, & Montgomery S. (2010). ACUTE EFFECT OF A SINGLE HIGH-FAT MEAL ON FOREARM BLOOD FLOW, BLOOD PRESSURE AND HEART RATE IN HEALTHY MALE ASIANS AND CAUCASIANS: A PILOT STUDY. Southeast Asian Journal of Tropical Medicine and Public Health, 41(2), 490-500. ( 3/2010 )
    Research has shown that ingestion of a single high-fat (HP) meal causes postprandial lipemia and produces a reduced brachial artery blood flow response to vascular occlusion in Caucasians. However, the forearm BE response to occlusion in Caucasian and Asian populations after a single I IF meal has not been compared. Eleven healthy male Asians, mean age 264 (+/- 4.2) years, height 174 2 (+/- 7.4) cm, and weight 73.8 (+/- 5.7) kg and eight Caucasians, mean age 26.8 (+/- 4 6) years, height 182.9 (+/- 5.9) cm, and weight 82.8 (+/- 4 8) kg were studied. A randomized cross-over study design was used with a HF (50.1 g total fat) or low-fat (L.F) (5.1 g total fat) test meal 1 week apart. Forearm blood flow was measured over a 2-minute period following a 4-minute occlusion (FBFO) at 2 and 4 hours following ingestion of a test meal. This study found that FBFO was significantly attenuated in Asians (19.3%, p=0.09) compared to Caucasians after the ingestion of a HF meal When comparing LF vs HF meals in Asians, the FRFO were 336.9 ml/100 ml tissue/minute and 240.8 ml/100 ml tissue/minute, respectively (p=0 02), whereas in Caucasians, the FBFO were 344.8 ml/100 ml tissue/minute and 287 4 ml/100 ml tissue/minute, respectively. It appears Asians have a more sensitive response to a single HF meal which may be explained, in part, by genotypic variation. These findings suggest that a single HF meal may contribute to the detrimental effects on vascular health in Asian males and raises speculation regarding the cumulative impact of a chronic HF diet in this population.
  • Petrofsky J S, McLellan K, Prowse M, Bains G, Berk L, & Lee S. (2010). The Effect of Body Fat, Aging, and Diabetes on Vertical and Shear Pressure in and Under a Waist Belt and Its Effect on Skin Blood Flow. Diabetes Technology & Therapeutics, 12(2), 153-160. ( 2/2010 ) Link...
    Background: Much attention has been given to the effect of pressure on skin blood flow in the feet of older people and people with diabetes. However, little attention has been paid to other areas of the body, especially under the belt at the waist where pressure might be high during body movements associated with exercise. This may be very important when devices such as heat packs are worn during the day under the belt because their safety relies on appropriate skin blood flow to dissipate the heat; in diabetes populations burns have been seen. Methods: Forty male and female subjects, with and without diabetes, were examined in two series of experiments to assess the vertical and shear pressure under a belt worn during different common exercises. Vertical and shear pressure under the belt, belt tension, and shear pressure were measured with a Tactilus (Sensor Products, Madison, NJ) pressure mapping system. Eleven different body movements were examined. Then, from the recorded pressures, a second series of experiments examined skin blood flow at these same pressures. Results: The results of the experiments showed that there was little shear and vertical pressure in thin subjects during 10 different exercises. However, for overweight subjects, pressure under the belt was as high as 150 kPa. At these high levels of pressure, skin circulation was occluded. Conclusions: In subjects with diabetes who are generally overweight and have impaired circulation, hot packs should be used with caution because of the low blood flows at rest and occlusion of the circulation under the belt with body movement.
  • Petrofsky J, Gunda S, Raju C, Bains G S, Bogseth M C, . . . Lohman E. (2010). Impact of hydrotherapy on skin blood flow: How much is due to moisture and how much is due to heat?. Physiother Theory Pract, 26(2), 107-12. ( 2/2010 ) Link...
    Hydrotherapy and whirlpool are used to increase skin blood flow and warm tissue. However, recent evidence seems to show that part of the increase in skin blood flow is not due to the warmth itself but due to the moisture content of the heat. Therefore, two series of experiments were accomplished on 10 subjects with an average age of 24.2 +/- 9.7 years and free of diabetes and cardiovascular disease. Subjects sat in a 37 degrees C hydrotherapy pool under two conditions: one in which a thin membrane protecting their skin from moisture while their arm was submerged in water and the second where their arm was allowed to be exposed to the water for 15 minutes. During this period of time, skin and body temperature were measured as well as skin blood flow by a Laser Doppler Imager. The results of the experiments showed that the vapor barrier blocked any change in skin moisture content during submersion in water, and while skin temperature was the same as during exposure to the water, the blood flow with the arm exposed to water increased from 101.1 +/- 10.4 flux to 224.9 +/- 18.2 flux, whereas blood flow increased to only 118.7 +/- 11.4 flux if the moisture of the water was blocked. Thus, a substantial portion of the increase in skin blood flow associated with warm water therapy is probably associated with moisturizing of the skin rather than the heat itself.
  • McLellan K, Petrofsky J S, Zimmerman G, Lohman E, Prowse M, Schwab E, & Lee S. (2009). The Influence of Environmental Temperature on the Response of the Skin to Local Pressure: The Impact of Aging and Diabetes. Diabetes Technology & Therapeutics, 11(12), 791-798. ( 12/2009 ) Link...
    Background: To protect against ischemia, pressure-induced vasodilation (PIV) causes an increase in skin blood flow. Endothelial dysfunction, which is commonly found in older patients and those with diabetes, and global temperatures can affect the resting blood flow in skin, which may reduce the blood flow during and after the application of local pressure. The present study investigated the PIV of the skin with exposure to three global temperatures in younger and older populations and those with diabetes. Materials and Methods: Older subjects (n = 15, mean age 64.2 +/- 14.0 years), subjects with diabetes (n = 15, mean age 62 +/- 5.9 years, mean duration 13.2 +/- 9.1 years), or younger subjects (n = 15, mean age 25.7 +/- 2.9 years) participated. An infared laser Dopler flow meter was used to measure skin blood flow on the bottom of the foot, lower back, and hand during and after applications of pressure at 7.5, 15, 30, 45, and 60 kPa at 16 degrees C, 24 degrees C, and 32 degrees C global temperatures. Results: The resting blood flow for all subjects was significantly lower in the 16 degrees C environment (P < 0.05). Blood flow in the group with diabetes was significantly lower at rest, during the application of all pressure, and after the release of pressure in all global temperatures (P < 0.05). The younger group showed a significant increase in blood flow after every pressure application, except 7.5 kPa, in all global conditions (P < 0.001). Older subjects and patients with diabetes did not have a significant reactive hyperemia, especially in the 16 degrees C environment. Conclusion: The protective mechanism of PIV is severely reduced in older populations and those with diabetes, especially in colder environments where skin blood flow is already diminished.
  • Suh H, Petrofsky J S, Lo T, Lawson D, Yu T, Pfeifer T M, & Morawski T. (2009). The Combined Effect of a Three-Channel Electrode Delivery System with Local Heat on the Healing of Chronic Wounds. Diabetes Technology & Therapeutics, 11(10), 681-688. ( 10/2009 ) Link...
    Background: Historically, electrical stimulation (ES) has been used as a treatment for wound care. However, some studies show wounds healing with ES, whereas others do not. Part of the difficulty can be resolved by using heat to help dilate blood vessels, but an inherent problem with ES is uneven currents across the wound due to the use of only two electrodes. Therefore, we designed and tested a multi-electrode ES device in combination with local warming of the wound in non-healing chronic ulcers. Study Design: Eighteen subjects (mean +/- SD age, 35.7 +/- 21.3 years) with chronic ulcers (no healing for 26.1 +/- 24.6 months) received ES treatment three times a week for 4 weeks. A heat lamp was used before and during ES to keep the wound and area surrounding the wound warm (37 degrees C). ES was applied for 30 min with biphasic sine wave stimulation at a frequency of 30 Hz, pulse width of 250 mu s, and current of about 20 mA. Skin blood flow (BF) in and around the wound was measured with a laser Doppler imager. Wound size was measured prior to each treatment. Results: Over the 1-month period, the mean wound area significantly decreased by 43.4 +/- 44.5% (P < 0.05), and wound volume decreased by 57.0 +/- 27.9% (P < 0.05). Skin BF significantly increased after application of ES and local heat (P < 0.05). The skin BF response decreased as time progressed and the wound healed. Conclusions: Thus, in this pilot study, application of a three-channel ES system in combination with local heat is effective in the healing of non-healing chronic wounds. Future studies should examine a larger population with variables such as treatment duration, number of days, or length of treatment to optimize the effect of ES on healing of non-healing chronic wounds.
  • Petrofsky J S, Bains G, Raju C, Lohman E, Berk L, . . . Batt J. (2009). The effect of the moisture content of a local heat source on the blood flow response of the skin. Archives of Dermatological Research, 301(8), 581-585. ( 9/2009 ) Link...
    Numerous studies have examined the effect of local and global heating of the body on skin blood flow. However, the effect of the moisture content of the heat source on the skin blood flow response has not been examined. Thirty-three subjects, without diabetes or cardiovascular disease, between the ages of 22 and 32 were examined to determine the relationship between the effects of dry vs. moist heat applied for the same length of time and with the skin clamped at the same skin temperature on the blood flow response of the skin. The skin, heated with an infrared heat lamp (skin temperature monitored with a thermocouple) to 40A degrees C for 15 min, was either kept moist with wet towels or, in a separate experiment, kept dry with Drierite (a desiccant) between the towels to remove any moisture. Before and after heat exposure of the forearm, blood pressure, heart rate, skin moisture content, skin temperature, and skin blood flow were recorded. The results of the experiment showed that there was no change in skin moisture after 15 min exposure to dry heat at 40A degrees C. However, with moist heat, skin moisture increased by 43.7%, a significant increase (P < 0.05). With dry heat, blood flow increased from the resting value by 282.3% whereas with moist heat, blood flow increased by 386% over rest, a significant increase over dry heat (P < 0.05). Thus, with a set increase in skin temperature, moist heat was a better heating modality than dry heat. The reason may be linked to moisture sensitivity in calcium channels in the vascular endothelial cell.
  • Petrofsky J S, Lohman E, & Lohman T. (2009). A device to evaluate motor and autonomic impairment. Medical Engineering & Physics, 31(6), 705-712. ( 7/2009 ) Link...
    Various devices have been developed to assess impairment of the autonomic nervous system, while other devices have been developed to evaluate the motor system. However, no devices have been developed to examine the interaction between the autonomic and somatic nervous systems. Therefore, the device described here, a square platform which was 0.7 x 0.7 m in length and 0.1 m thick, was developed to examine somatic-autonomic interaction. The device can be used by placing it directly on the floor or on 1 of 2 pivots; one that allowed the platform to move 0.2 m (+/- 44.1 degrees) in the front to back or side to side direction and one that allowed both movements together. Strain gauge load cells in the platform measured sway and tremor during the subjects attempt to balance and a continuous blood pressure monitor and the ECG were used to assess the response of the autonomic nervous system (heart rate variability). The device was tested on 5 normal subjects and the following was evaluated: (1) sway during standing, (2) weight shift during standing, (3) frequency of sway and extent of sway during standing, (4) sympathetic and parasympathetic alterations in the ANS during attempted balance, and (5) phase delays between motor and autonomic responses. The results showed that, with increasing balance challenge, sway increased, tremor increased, the sway angle increased and sway was positively correlated with heart rate and negatively correlated with blood pressure. A balance challenge significantly increased sympathetic activity but not parasympathetic activity. This device should have useful applications in assessing motor impairments and sensory and autonomic impairments in a variety of conditions. (C) 2009 IPEM. Published by Elsevier Ltd. All rights reserved.
  • Petrofsky J S, & McLellan K. (2009). Galvanic Skin Resistance-A Marker for Endothelial Damage in Diabetes. Diabetes Technology & Therapeutics, 11(7), 461-467. ( 7/2009 ) Link...
    Background: Aging and diabetes are both associated with impaired vascular endothelial function. This causes a reduction in the resting blood flow and the blood flow response to autonomic stressors. Further, skin moisture and the ability to sweat are also reduced with aging and diabetes. The present investigation was undertaken to determine if the extent of damage from aging and diabetes could be accurately assessed by simply examining the electrodermal skin response (galvanic skin resistance) to a thermal stress. Study Design: Forty-five subjects whose average age was 31.2 +/- 8.3 years (younger group), 62.4 +/- 9.6 years (older group), and 61.8 +/- 11.3 years (diabetes group) were divided into three groups of 15 subjects. Subjects were exposed to environmental temperatures of 15 degrees C, 23 degrees C, or 32 degrees C for 30 min. During this period of time, sweat rate, skin blood flow, the electrodermal skin response, and skin moisture were measured. Results: There were significant impairments in skin moisture, sweat, skin blood flow, and the galvanic skin response at any of the three environmental temperatures in subjects with diabetes compared to older subjects compared to younger subjects (analysis of variance, P < 0.01). Both a reduction in skin blood flow and impaired sweating contributed to the higher galvanic skin resistance seen in subjects with diabetes. The greatest contributor was impaired sweating. Conclusions: The results show that galvanic skin resistance, at any environmental temperature, may be a good means of assessing vascular damage and impaired sweat response in people with diabetes.
  • Petrofsky J S, Bains G S, Prowse M, Lellan K M, Ethiraju G, . . . Schwab E. (2009). The influence of age and diabetes on the skin blood flow response to local pressure. Medical Science Monitor, 15(7), CR325-CR331. ( 7/2009 )
    Background: Previous data has shown that when pressure is applied to the skin of the ankle and oil the foot, there is a reactive increase ill circulation. In the present investigation, these studies were expanded to look at the response of the hand, back, and foot to applied pressure. Material/Methods: Ten young subjects whose average age was 26.5 +/- 3.3 yrs, 10 older subjects whose average age was 73.3 +/- 19.7 yrs and 10 people wiht diabetes whose average age was 60.1 +/- 5.7 yrs participated in the study. There was no statistical difference in the height or weight of the subjects. Hemoglobin Alc of the group with Diabetes averaged 6.98 +/- 1.15% with the mean duration of diabetes 13.6 +/- 9.5 yrs. An infrared laser Doppler flow meter was used to measure circulation on the hand, lower back, and on the bottom of the foot during application of pressure at 15, 30, 45, and 60 kPa. Results: For all three areas of the body, circulation was significantly less ill the group with diabetes than the other two groups (p<0.05). When pressure was applied at. 15 kPa, the blood flow to the skin initially decreased, but then increased in the younger subjects and in the older subjects but did not increase in subjects with diabetes for any area of the body. Further, after pressure was released, for any of the four pressure examined here, while the younger subjects showed a pronounced reactive hyperemia, subjects with diabetes showed a diminished hyperemia not proportional to the pressure that was applied. Conclusions: It appears that the normal protective mechanism of a pressure induced hyperemia is absent or diminished in patients with diabetes with more effect on the periphery than on the core area of the body. More importantly, after pressure was applied and released, subjects with diabetes lacked a proportional hyperemia to recovery form the transient ischemia of the pressure.
  • Petrofsky J S, Bains G S, Prowse M, Mc Lellan K, Ethiraju G, . . . Schwab E. (2009). The influence of age and diabetes on the skin blood flow response to local pressure. Med Sci Monit, 15(7), CR325-31. ( 7/2009 )
    BACKGROUND: Previous data has shown that when pressure is applied to the skin of the ankle and on the foot, there is a reactive increase in circulation. In the present investigation, these studies were expanded to look at the response of the hand, back, and foot to applied pressure. MATERIAL/METHODS: Ten young subjects whose average age was 26.5+/-3.3 yrs, 10 older subjects whose average age was 73.3+/-19.7 yrs and 10 people with diabetes whose average age was 60.1+/-5.7 yrs participated in the study. There was no statistical difference in the height or weight of the subjects. Hemoglobin A1c of the group with Diabetes averaged 6.98+/-1.15% with the mean duration of diabetes 13.6+/-9.5 yrs. An infrared laser Doppler flow meter was used to measure circulation on the hand, lower back, and on the bottom of the foot during applications of pressure at 15, 30, 45, and 60 kPa. RESULTS: For all three areas of the body, circulation was significantly less in the group with diabetes than the other two groups (p<0.05). When pressure was applied at 15 kPa, the blood flow to the skin initially decreased, but then increased in the younger subjects and in the older subjects but did not increase in subjects with diabetes for any area of the body. Further, after pressure was released, for any of the four pressures examined here, while the younger subjects showed a pronounced reactive hyperemia, subjects with diabetes showed a diminished hyperemia not proportional to the pressure that was applied. CONCLUSIONS: It appears that the normal protective mechanism of a pressure induced hyperemia is absent or diminished in patients with diabetes with more effect on the periphery than on the core area of the body. More importantly, after pressure was applied and released, subjects with diabetes lacked a proportional hyperemia to recovery form the transient ischemia of the pressure.
  • Petrofsky J, Prowse M, Remigio W, Raju C, Salcedo S, . . . Gadagoju A. (2009). The Use of an Isometric Handgrip Test to Show Autonomic Damage in People with Diabetes. Diabetes Technology & Therapeutics, 11(6), 361-368. ( 6/2009 ) Link...
    Background: Vascular endothelial and autonomic damage are hallmarks of type 1 and type 2 diabetes. However, while much has been published on impairment of the autonomic nervous system, much less has been published on the interrelationship between autonomic damage and exercise. Study Design: The present investigation examined the change in heart rate, blood pressure, skin and limb blood flow, and sweat during non-fatiguing (10% and 25% maximum strength [maximal voluntary contraction (MVC)]) and a fatiguing isometric contraction (40% MVC) in people with type 2 diabetes compared to younger and older controls to see if a simple handgrip test could show the extent of autonomic damage in people with diabetes. Fifteen younger subjects (30.6+/-8.6 years), 15 older subjects (65.8+/-8.8 years), and 15 subjects with diabetes (63.4+/-14.4 years) whose average percentage body fat was 40.1+/-12.9%, 36.1+/-9.3%, and 39.6+/-15.5%, respectively, participated in these studies. Whole forearm blood flow, skin blood flow, and sweat on the forearm, chest, and forehead were measured at rest and during and after a contraction at 10% MVC, 25% MVC, and 40% MVC. Results: Blood flows and sweat rates were greatest in younger subjects, significantly less in older subjects, and even significantly less in subjects with diabetes (P < 0.05). The heart rate response was unaltered during contractions at 10% and 25% MVC and less in diabetes than in the other two groups with 40% MVC. Strength was about half in the diabetes group than with the other two groups, but endurance was similar. Conclusions: Diabetes is associated with a reduction in handgrip strength and significantly impaired autonomic function during and after isometric exercise.
  • Petrofsky J S, McLellan K, Bains G S, Prowse M, Ethiraju G, . . . Schwab E. (2009). The influence of ageing on the ability of the skin to dissipate heat. Medical Science Monitor, 15(6), CR261-CR268. ( 6/2009 )
    Background: Ageing reduces the resting blood flow to the skin as well as the blood flow response to thermal Stimuli. However, the interrelationships between skin thickness, subcutaneous fat, and skill blood flow in determining the heat dissipation characteristics of the skin have not been investigated. Material/Methods: In the present investigation, 60 male and female subjects were examined with either a continuous 0.15 watt heat source or a 40 degrees C instantaneous heat source applied to the skill. Data was correlated to skin and subcutaneous fat thickness measured by ultrasound and to skin blood flow measured by a laser Doppler flow meter. Results: The results of the experiments showed a significant. negative correlation between age and skill thickness (p<0.0001) and between age and subcutaneous fat thickness (p<0.001). Blood Flows in the skill, with the subject in a 24 degrees C, room were 61.8% less in the older subjects compared to the younger subjects. This was due to both a reduction in red cell concentration and red cell velocity. The lower concentration of red cells matches the reduction in skill thickness, implying a loss in the dermal layer of the skill associated with ageing. The skill blood flow response to continuous heat and to a single heat exposure were both reduced in the older subjects (p<0.01). Ageing also caused a slower response of the skill to heat stress. Conclusions: The results support a reduction in both the resting and post local heat skin blood flows associated with ageing. Some of this may be due to a reduction in dermal layer thickness due to ageing. Conclusions:
  • Suh H, Petrofsky J, Fish A, Hernandez V, Mendoza E, . . . Lawson D. (2009). A New Electrode Design to Improve Outcomes in the Treatment of Chronic Non-Healing Wounds in Diabetes. Diabetes Technology & Therapeutics, 11(5), 315-322. ( 5/2009 ) Link...
    Background: Chronic wounds are life-threatening in people with diabetes. Some studies show that electrical stimulation (ES) can help wounds heal, while others do not. But, ES is usually applied using a two-electrode system, where current distribution is greatest in the center line between the electrodes. In the present study, a three-electrode system (three-channel ES) was developed. Current dispersion on the skin and in the quadriceps muscle was compared between the conventional two-electrode and three-electrode systems in controls and tested for its ability to heal chronic wounds in people with diabetes. Methods: In controls, current was delivered via a biphasic sine wave at a frequency of 30 Hz and pulse width of 100 mu seconds. Stimulation electrodes 5 cm x 5 cm and 5 cm x 10 cm were placed at 10 cm and 15 cm separation distances above the quadriceps muscle. Skin currents were measured using five pairs of surface electrodes positioned in five separate locations on the skin. Muscle currents were measured using three pairs of needle electrodes positioned in three different locations in the muscle belly. In chronic wounds in eight subjects with diabetes, stimulation was applied for 1 month, and healing and blood flow were measured. Results: Current during three-channel ES was dispersed more evenly and more deeply than with conventional two-channel ES (P < 0.05). In wounds, there was almost complete healing in 1 month, and current was uniform in the wound. Conclusions: Three-channel ES is more effective than two-channel ES in terms of better current dispersion across the skin and penetration into tissue and will probably be better for wound healing.
  • McLellan K, Petrofsky J S, Bains G, Zimmerman G, Prowse M, & Lee S. (2009). The effects of skin moisture and subcutaneous fat thickness on the ability of the skin to dissipate heat in young and old subjects, with and without diabetes, at three environmental room temperatures. Medical Engineering & Physics, 31(2), 165-172. ( 3/2009 ) Link...
    The Pennes model predicts the ability of the skin to dissipate heat as a function of conductive heat transfer and blood flow. Conductive heat exchange may be affected by skin moisture and subcutaneous fat thickness, factors not considered by Pennes. In the present investigation, we sought to expand the Pennes model by examining subcutaneous fat and skin moisture as factors of heat dissipation and their effects on heat exchange and blood flow. Subjects who were older (0) (mean age 64.2 +/- 5.9 years, n=15), had diabetes (D) (mean age 62 +/- 5.9 years, mean duration 13.2 +/- 9.1 years, n=15), and were younger (Y) (mean age 25.7 +/- 2.9 years, n=15) participated. Thermisters were placed in an iron heat probe and on the skin to measure the change in skin temperature to create a thermal change index to demonstrate the ability of the skin to dissipate heat. The lower back had the thickest subcutaneous fat layer for all subjects, which contributed to higher skin temperatures than the foot and hand in response to local and global heat. There was a significant inverse correlation between skin moisture and skin temperature after 5 s of heat application (r=-0.73, p<0.001) with O and D having significantly less skin moisture than Y (p<0.05). O and D had significantly increased skin temperatures in response to local heat, as compared to Y, in all global temperatures (p<0.05). Thus, the Pennes model may need to be adjusted to take into consideration aging, diabetes, skin moisture, and subcutaneous fat thickness. (C) 2008 IPEM. Published by Elsevier Ltd. All rights reserved.
  • McLellan K, Petrofsky J S, Zimmerman G, Prowse M, Bains G, & Lee S. (2009). Multiple Stressors and the Response of Vascular Endothelial Cells: The Effect of Aging and Diabetes. Diabetes Technology & Therapeutics, 11(2), 73-79. ( 2/2009 ) Link...
    Background: The present study examined the effects of local heat, global heat, and the interaction between these two endothelial stressors on the blood flow of the skin of the foot in people who are older and who have diabetes. Methods: Subjects who were older (mean age 64.2 +/- 5.9 years) and were younger (mean age 25.7 +/- 2.9 years) and subjects who had diabetes (mean age 62 +/- 5.9 years, mean duration 13.2 +/- 9.1 years) participated. Subjects were exposed to three global temperatures (16 degrees C, 24 degrees C, and 32 degrees C), and the blood flow response was recorded on the foot with a laser Doppler flow meter for 30 s following applications of local heat (30 degrees C, 33.5 degrees C, and 37 degrees C) using a Peltier junction to clamp the skin for 2 min. Results: All three groups significantly increased blood flow from the 16-24 degrees C environments for the 37 degrees C application of local heat (P(Younger) = 0.02, P(Older) = 0.02, P(Diabetes) = 0.01). Those with diabetes and those who were older only increased blood flow 5% and 6% from the 24-32 degrees C environment, which was not statistically significant (P(Older) = 0.12, P(Diabetes) = 0.14). Conclusions: There appears to be considerable blood flow reserve in younger subjects to tolerate heat stress. In contrast, older subjects and those with diabetes reach a critical level after which additional heat does not cause in increase in blood flow.
  • Maloney-Hinds C, Petrofsky J S, Zimmerman G, & Hessinger D A. (2009). The Role of Nitric Oxide in Skin Blood Flow Increases Due to Vibration in Healthy Adults and Adults with Type 2 Diabetes. Diabetes Technology & Therapeutics, 11(1), 39-43. ( 1/2009 ) Link...
    Background: We recently demonstrated concomitant increases in skin blood flow and nitric oxide (NO) production in young healthy adults in response to externally applied vibration of the forearm. Research has shown that adults with type 2 diabetes exhibit depressed NO production and vascular responses to NO. We hypothesized that subjects with type 2 diabetes would display lower than normal increases in skin blood flow to externally applied vibration. Research Design and Methods: Therefore, the purpose of this study was to compare 20 male and female, age- and body mass index-matched normal adults and adults with type 2 diabetes in terms of the effects of external vibration of the forearm on skin blood flow and the rate of NO production. Skin blood flow and NO production were measured before vibration, immediately after 5 min of vibration, and 5 min after vibration ceased. Results: Although externally applied vibration significantly increased skin blood flow for both groups P 0.0001), those with diabetes had significantly lower (223%; P = 0.003) skin blood flows compared to the healthy older adults (461%). The rate of NO production, expressed as mu M NO . flux, also increased significantly in both groups after vibration (healthy group, 374%; diabetes group, 236%) and remained significantly elevated (healthy group, 258%; diabetes group, 177%) for at least 5 min; however, the difference between groups was not significant (P = 0.1.2). Conclusions: These findings suggest that subjects with diabetes exhibit a lower skin blood flow and lower NO response to externally applied vibration than matched normal subjects.
  • Petrofsky J S, & Laymon M. (2009). Heat transfer to deep tissue: the effect of body fat and heating modality. J Med Eng Technol, 33(5), 337-48. ( 0/2009 ) Link...
    The purpose of this study was to quantify the thermal transfer characteristics of the skin in relation to body composition as assessed by the ability of water immersion and hot and cold packs with different thicknesses of towels layers to heat or cool deep tissue. Two sets of experiments were conducted to determine the interrelationships between body fat content and muscle temperature after immersion of the limb in water or the application of hot and cold packs. In the first series of experiments, subjects immersed their lower body in water at 42, 37, 34, 27, 24 and 0 degrees C for 20 minutes. Muscle temperature was measured in the skin above and in the belly of the quadriceps and medial gastrocnemius muscles by a thermistor on the skin and one implanted with a 20-gauge needle 25 mm below and perpendicular to the skin. To see the effect of circulation, a series was conducted with the circulation occluded. In the second series, hot or cold packs were used with different thicknesses of towel layers. The muscle temperature after immersion in water approached that of the packs within approximately 20 minutes. In contrast, when hot and cold packs were used with various thickness of towels ranging from 2 to 10 mm in thickness, the change in muscle temperature was much less and it was still changing at the end of a 20 minute period. Subjects with high body fat changed their deep tissue temperatures much more slowly with a time constant nearly double that of the thin subjects with all modalities. Even after water immersion, if the body fat exceeded 25% of the subject's weight, 20 min of immersion was not enough to either warm the muscle or cool it down substantially. Cold packs and hot packs were very ineffective in changing muscle temperature under these same conditions. Body fat plays a major role, as did limb blood flow in controlling the movement of heat across the limb.
  • Petrofsky J, Bains G, Prowse M, Gunda S, Berk L, . . . Madani P. (2009). Does skin moisture influence the blood flow response to local heat? A re-evaluation of the Pennes model. J Med Eng Technol, 33(7), 532-7. ( 0/2009 ) Link...
    Pennes first described a model of heat transfer through the limb based only on calories delivered from a heat source, calories produced by metabolism and skin blood flow. The purpose of this study was to determine the effect of a moist versus a dry heat source on the skin in eliciting a blood flow response to add data to this model. Ten subjects were examined, both male and female, with a mean age of 32.5 +/- 11.6 years, mean height of 172.8 +/- 12.3 cm, and mean weight of 77.6 +/- 19.5 kg. Skin temperature was measured by a thermocouple placed on the skin and skin blood flow measured by a laser Doppler flow meter. The results of the experiments using a dry heat pack (commercially available chemical 42 degrees C cell dry heat source), moist hydrocollator pack (72.8 degrees C) separated from the skin by eight layers of towels, and whirlpool at 40 degrees C, showed that moist heat caused a significantly higher skin blood flow (about 500% greater) than dry heat (p < 0.01). Most of the greater increase in skin blood flow with moist heat was due to the greater rate of rise of skin temperature with moist versus dry heat while some of the increase in blood flow was due to the moisture itself. This could either be related to the greater heat flux across the skin with moist air or due to changing the ionic environment around skin thermo receptors by keeping the skin moist during heating. Skin thermo receptors are believed to be temperature sensitive calcium gated channels in endothelial cells which couple calcium influx to a release of nitric oxide. If true, reducing moisture in the skin might have the effect of altering ionic flux through these receptors. A correct model of skin heat flux should therefore take heat moisture content into consideration.
  • Petrofsky J, Bains G, Prowse M, Gunda S, Berk L, . . . Madani P. (2009). Dry heat, moist heat and body fat: are heating modalities really effective in people who are overweight?. J Med Eng Technol, 33(5), 361-9. ( 0/2009 ) Link...
    Surface heating modalities are commonly used in physical therapy and physical medicine for increasing circulation, especially in deep tissues, to promote healing. However, recent evidence seems to indicate that in people who are overweight, heat transfer is impaired by the subcutaneous fat layer. The present investigation was conducted on 10 subjects aged 22-54 years, whose body mass index averaged 25.8+/-4.6. Subcutaneous fat above the quadriceps muscle varied from 0.51 to 0.86 cm of thickness. Three heating modalities were examined: the application of dry heat with a commercial chemical heat pack, hydrocollator heat packs (providing a type of moist heat), and a whirlpool, where conductive heat loss through water contact would be very high. The temperature of the skin and the temperature in the muscle (25 mm below the skin surface) were assessed by thermocouples. The results of the experiments showed that for heating modalities that are maintained in skin contact for long periods of time, such as dry heat packs (in place for 6 hours), subcutaneous fat did not impair the change in deep muscle temperature. In contrast, when rapid heat modalities were used, such as the hydrocollator and the whirlpool (15 minutes of sustained skin contact), the transfer of heat from the skin to deep muscle was significantly impaired in people with thicker subcutaneous fat layers. We observed that the greater the impairment in heat transfer to muscle from skin covered by body fat, the warmer the skin temperature increase during the modality.
  • Petrofsky J, Laymon M, Prowse M, Gunda S, & Batt J. (2009). The transfer of current through skin and muscle during electrical stimulation with sine, square, Russian and interferential waveforms. J Med Eng Technol, 33(2), 170-81. ( 0/2009 ) Link...
    Electrical stimulation is a commonly used modality for both athletic training and physical therapy. However, there are limited objective data available to determine the waveform which provides the maximum muscle strength as well as minimizing pain. In the present investigation, two groups of subjects were examined. Group 1 was composed of six males and four females and group 2 was composed of three male and three female subjects. The first series of experiments investigated muscle strength with stimulation at currents of 20, 40 and 60 milliamps using sine, square, Russian and interferential waveforms evaluating strength production and pain as outcomes. The second phase of experiments compared the effect of the different waveforms on current dispersion in surface versus deep muscle electrodes with these same waveforms. The results of the experiments showed that sine wave stimulation produced significantly greater muscle strength and significantly less pain than square wave, Russian or interferential stimulation at that same current. The most painful stimulation was square wave. Strength production was greatest with sine wave and least with Russian and interferential. An explanation of these findings may be the filtering effect of the fat layer separating skin from muscle. The highly conductive muscle and skin dermal layers would form the plates of a capacitor separated by the subcutaneous fat layer providing an RC filter. This filtering effect, while allowing sine wave stimulation to pass to the muscle, reduced power transfer in square wave, Russian and interferential stimulation is observed.
  • petrofsky lee. "Rsg and endothelial function." med sci monitor 12;cr21. (2005): -. ( 1/2005 )
  • Carrole, C., Petrofsky, J.S., & Phillips, C.A. (1981). Multi-dimensional modeling of movement. Proc Aerospace Med Assoc,81:15-16.

     

     

    Fiore, P., Petrofsky, J.S., & Glaser, R.M. (1981). Cardiovascular responses to mixed static and dynamic exercise. IEEE Naecon Record, 81,1066-71.

     

     

    Glaser, R., & Petrofsky, J.S. (1981). Digitizing the Parkinson-Cowan CD-4 dry gas meter. IEEE Naecon Record, 81, 589-593.

     

     

    Lind, A.R., Dahms, T., Williams, C., & Petrofsky, J.S. (1981). The blood flow through the "resting" arm during handgrip contractions. Circ Res, 48, I104-I109.

     

     

    Petrofsky, J.S. (1981). Digital controlled handgrip dynamometer for isometric performance studies. IEEE Naecon Record, 81, 570-574.

     

     

    ( 0/1981 )
  • Petrofsky, J.S. (1981). Quantification through the surface EMG of muscle fatigue and recovery during successive isometric contractions. Aviat Space Environ Med, 52:545-550.

     


    Petrofsky, J.S. (1981). The influence of recruitment order and temperature on muscle contraction with special reference to motor unit fatigue. Europ J Appl Physiol, 47,17-25.

     


    Petrofsky, J.S., Burse, R., & Lind, A.R. (1981). The effect of deep muscle temperature on the cardiovascular responses of man to static effort. Europ J Appl Physiol, 47,7-16.

     


    Petrofsky, J.S., Le Donne, D., Reinhart, J.S., & Lind, A.R. (1981). The influence of the menstrual cycle on blood flow through muscle during isometric contractions. Ohio J Sci, 81, 236-238.

     

    ( 0/1981 )
  • Petrofsky, J.S., & Phillips, C.A. (1980). Interrelationship between muscle fatigue, muscle temperature, blood flow and the surface EMG. IEEE Naecon Record, 80,52-527.

     

    Petrofsky, J.S., & Phillips, C.A. (1980). The effect of elbow angle on isometric strength and endurance of flexors in men and women. J Hum Ergology, 9, 125-131.

     

    Petrofsky, J.S., & Phillips, C.A. (1980). The influence of recruitment order and fiber composition on the force-velocity relationship and fatigability of skeletal muscle in the cat. Med Biol Eng Comp, 18, 381-390.

     

    Petrofsky, J.S., Phillips, C.A., Sawka, M., Hanpeter, D., & Weber, C. (1980). Mechanical, electrical and biochemical correlates of isometric fatigue in the cat. Advances Physiol Sci, 18, 229-236.

    ( 0/1980 )
  Abstract
  • Jerrold Petrofsky, Faris Alshammari, Iman Akef Khowailed, Riya Lodha, Pooja Deshpande, Praveen Rajaram, Mahendra Gaikwad, Vidhi Vadera  The use of laser Doppler blood flow to assess the effect of acute administration of vitamin D on micro vascular endothelial function in people with diabetes  Phys Ther Rehabil ScipISSN 2287-7576 2013, 2 (2), 63-69

    ( 4/2014 )
  • Petrofsky J, Berk L, Bains G, Hau B, Doyle G, . . . Stark J. (2012). A viable methodology for assessing the onset of treatment for low back pain. British Journal of Clinical Pharmacology, 73(6), 1007-1007. ( 6/2012 )
  • Petrofsky J, Berk L, Bains G, Doyle G, Chen S, . . . Stark J. (2012). A viable methodology for assessing the onset of treatment for low back pain. International Journal of Clinical Pharmacy, 34(1), 164-164. ( 2/2012 )
  • Sirichotiratana M, Petrofsky J, & Berk L. (2009). DEVELOPMENT OF A METHOD FOR ASSESSING STRENGTH IN THE EXTENSOR DIGITORUM BREVIS MUSCLE. Journal of Investigative Medicine, 57(1), 167-167. ( 1/2009 )
  • Sirichotiratana M, Petrofsky J, & Prowse M. (2009). ASSESSMENT OF AUTONOMIC DAMAGE IN DIABETICS USING AN ISOMETRIC HANDGRIP TEST. Journal of Investigative Medicine, 57(1), 101-101. ( 1/2009 )
  • Sirichotiratana M, Petrofsky J, & Prowse M. (2009). ASSESSMENT OF AUTONOMIC DAMAGE IN DIABETICS USING AN ISOMETRIC HANDGRIP TEST. Journal of Investigative Medicine, 57(1), 154-154. ( 1/2009 )