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ABSTRACT: Background The purpose of this study was to investigate the changes in the Power Spectrum Density (PSD) of the electroencephalography (EEG) in common sensorimotor balance training tasks of varying difficulty. Sensorimotor balance exercises including alteration of vision, base of support or surface compliance are used to improve postural control. These exercises are presumed to induce supraspinal adaptation, however, there were no studies that investigated the power changes of the cortical activity in these static balance tasks. Our objective was to provide evidence in the cortical involvement with the static balance tasks frequently used in sensorimotor training. Material and Methods Postural sway and EEG changes of alpha, beta and sigma wave bands were measured in seventeen participants during eight balance tasks of varying difficulty with eyes open and closed, feet in tandem or apart and on foam or a firm surface. Results The power of beta and sigma bands increased significantly at the parietal and central area of the brain in tasks with eyes open together with one sensory factor (base of support or surface compliance) or two sensory factors (base of support and surface compliance) altered, and in task with three sensory factors (vision, base of support and surface compliance) altered from the control task. Conclusions This study demonstrated the cortical involvement in the sensorimotor balance tasks, suggesting that these exercises may induce cortical adaptation for postural control. The results support subcortical control with increased task difficulty and the increase in cortical processing when task became extremely challenging.
Medical science monitor: international medical journal of experimental and clinical research 01/2013; 19:175-86. · 1.70 Impact Factor
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Jerrold Scott Petrofsky,
Faris Alshammari,
Gurinder Singh Bains,
Iman Akef Khowailed,
Haneul Lee,
Yashvanth Nagarajamurthy Kuderu,
Riya D Lodha,
Sophia Rodrigues,
Diamond Nguyen,
Pooja Ashok Potnis,
Pooja P Deshpande,
Jong Eun Yim, Lee Berk
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ABSTRACT: Background It is well established that there is a reduction in the skin blood flow (SBF) in response to heat with age and diabetes. While it is known that high BMI creates a stress on the cardiovascular system and increases the risk of all cause of morbidity and mortality, little is known of the effect of high BMI on SBF response to heat. Since diabetes is associated with age and a higher BMI, the interrelationship between age, BMI and SBF needs to be investigated to better understand the contribution diabetes alone has to endothelial impairment. Material and Methods This study examined the SBF to heat in young and old people with low and high BMI and people with diabetes with high BMI to determine the contribution these variables have on SBF. Subjects were ten young and older people with BMI <20 and ten young and older people with BMI >20 and ten subjects with diabetes with BMI >20. The SBF response, above the quadriceps, was determined during a 6 minutes exposure to heat at 44°C. Results Even in young people, SBF after the stress of heat exposure was reduced in subjects with a high BMI. The effect of BMI was greatest in young people and lowest in older people and people with diabetes; in people with diabetes, BMI was a more significant variable than diabetes in causing impairment of blood flow to heat. BMI, for example, was responsible for 49% of the reduction in blood flow after stress heat exposure (R=-0.7) while ageing only accounted for 16% of the blood flow reduction (R=-0.397). Conclusions These results would suggest the importance of keeping BMI low not only in people with diabetes to minimize further circulatory vascular damage, but also in young people to diminish long term circulatory vascular compromise.
Medical science monitor: international medical journal of experimental and clinical research 01/2013; 19:257-63. · 1.70 Impact Factor
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Diabetes Technology & Therapeutics 10/2012; 14(10):969-70. · 1.93 Impact Factor
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ABSTRACT: 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.
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.
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.
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.
Medical science monitor: international medical journal of experimental and clinical research 08/2012; 18(8):CR467-479. · 1.70 Impact Factor
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ABSTRACT: 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.
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°C, 40°C and 42°C) and by vascular occlusion for 4 minutes followed by release and measurement of skin blood flow for 2 minutes.
When applying 6 minutes of local heat at 3 different temperatures (38°C, 40°C, and 42°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).
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.
Medical science monitor: international medical journal of experimental and clinical research 06/2012; 18(6):CR337-43. · 1.70 Impact Factor
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Jerrold S Petrofsky, Lee Berk,
Faris Alshammari,
Haneul Lee,
Adel Hamdan,
Jong Eun Yim,
Yusufi Kodawala,
Dennis Patel,
Bhakti Nevgi,
Gauri Shetye, [......],
Mastour Alshaharani,
Kunal Pathak,
Sushma Neupane,
Karunakar Somanaboina,
Samruddha Shenoy,
Sungwan Cho,
Bargav Dave,
Rajavi Desai,
Swapnil Malthane,
Hani Al-Nakhli
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ABSTRACT: 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.
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°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.
For both younger and older subjects, for air temperatures of 38 and 40°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°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°C. and 100% humidity (p<0.05).
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.
Medical science monitor: international medical journal of experimental and clinical research 04/2012; 18(4):CR201-8. · 1.70 Impact Factor
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Jerrold Petrofsky, Lee Berk,
Faris Alshammari,
Haneul Lee,
Adel Hamdan,
Jong Eun Yim,
Denis Patel,
Yusufi Kodawala,
Gauri Shetye,
Wei-Ti Chen, [......],
Karunakar Somanaboina,
Rajavi Desai,
Bhargav Dave,
Swapnil Malthane,
Mastour Alshaharani,
Sushma Neupane,
Samruddha Shenoy,
Bhakti Nevgi,
Sungkwan Cho,
Hani Al-Nakhli
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ABSTRACT: 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.
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°C, 40°C, or 42°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.
For the control subjects, the moisture in the air had no different effect on skin blood flow at air temperatures of 38°C and 40°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°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.
These data show that individuals with diabetes do not tolerate moist, warm air above 50% humidity as well as controls without diabetes.
Diabetes Technology & Therapeutics 02/2012; 14(2):105-16. · 1.93 Impact Factor
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ABSTRACT: 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.
Experimental Diabetes Research 01/2012; 2012:657103. · 1.20 Impact Factor
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ABSTRACT: 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.
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.
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.
Autonomic damage in the subjects with diabetes masked much of the stress of the inability to optimize balance in this population.
Diabetes Technology & Therapeutics 06/2010; 12(6):475-81. · 1.93 Impact Factor
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ABSTRACT: Research has shown that ingestion of a single high-fat (HF) meal causes postprandial lipemia and produces a reduced brachial artery blood flow response to vascular occlusion in Caucasians. However, the forearm BF response to occlusion in Caucasian and Asian populations after a single HF meal has not been compared. Eleven healthy male Asians, mean age 26.4 (+/- 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 (LF) (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 FBFO 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.
The Southeast Asian journal of tropical medicine and public health 03/2010; 41(2):490-500. · 0.60 Impact Factor
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ABSTRACT: 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.
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°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 μs, current approximately 20 mA).
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).
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.
Journal of Diabetes 03/2010; 2(1):41-6.
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ABSTRACT: 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.
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.
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.
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.
Diabetes Technology & Therapeutics 02/2010; 12(2):153-60. · 1.93 Impact Factor
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ABSTRACT: 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 40 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 40 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.
Archives for Dermatological Research 05/2009; 301(8):581-5. · 2.28 Impact Factor
