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Biomedical subjects

D S Moran

Publications and source records attributed to D S Moran.

At least 19 recordsLinked to original sources
PubMed2005

Physical exercise increases the expression of TNFalpha and GLUT 1 in muscle tissue of diabetes prone Psammomys obesus.

INTRODUCTION: Tumor necrosis factor-alpha (TNFalpha) is a major mediator of insulin resistance. On the other hand, it has been suggested that TNFalpha may facilitate glucose uptake through GLUT 1 expression. We recently found that physical exercise prevented the progression to type 2 diabetes mellitus in diabetes prone Psammomys obesus (sand rat). AIM: The aim of the present study was to characterize the influence of physical exercise on the expression of TNFalpha, its receptor R1 and GLUT 1 in muscle tissue of this animal model. METHODS: Animals were assigned for 4 weeks to four groups: high-energy diet (HC), high-energy diet and exercise (HE), low-energy diet (LC), low-energy diet and exercise (LE). TNFalpha, R1 and GLUT 1 expression were analyzed using Western blot technique. RESULTS: None of the animals in the HE group became diabetic while all the animals in the HC group became diabetic. TNFalpha, its receptor (R1) and GLUT 1 expressions were significantly higher in the two exercising groups (LE and HE) and significantly lower in the HC group compared to the control LC group. CONCLUSIONS: Physical exercise augments the expression of TNFalpha, its receptor R1 and the glucose transporter GLUT 1 in muscle tissue. We suggest that this mechanism may improve glucose uptake through pathways parallel and unrelated to insulin signaling that may include MAPK and/or NO. These biochemical processes contribute to the beneficial effects of physical exercise on the prevention of type 2 diabetes mellitus.

Animals↗
PubMed2003

Evaluation and refinement of the environmental stress index for different climatic conditions.

The purpose of this study was to evaluate the recently constructed environmental stress index (ESI) for a large database comprising various climatic conditions. Data analysis of measurements from 19 locations revealed a high correlation between ESI and the wet bulb globe temperature (WBGT) index for each database. Validity from statistical analysis, including optimization procedures, slightly changed the ESI constants as follows: ESI = 0.62Ta - 0.007RH + 0.002SR + 0.0043(Ta x RH) - 0.078(0.1 + SR)(-1) where: Ta = ambient temperature (degrees C); RH = relative humidity (%); and SR = solar radiation (w x m(-2)). The refined ESI and the WBGT index were applied to databases of more than 125,000 measurements for each variable: Ta, RH, SR, black globe temperature (Tg), and wet bulb temperature (Tw). For each database, the ESI was then successfully correlated with the WBGT (P < 0.05, R2 > or = 0.899). We conclude that the refined ESI, which is constructed from fast response and commonly used weather sensors (Ta, RH, SR), is a potential index to serve as an alternative to the WBGT for heat category assessment.

Acclimatization↗
PubMed2003

[Core body temperature monitoring using the telemetric pill].

Exposure to extreme weather or physical work conditions can lead to dangerous core temperature changes, and to the clinical syndromes accompanying them. Core temperature measurement is the main tool for diagnosing these syndromes. Recent technological advances particularly NASA's telemetry and miniaturizing technologies, have led to the development of a CorTemp Ingestible Temperature Sensor, or "pill". The pill is a small electronic device, which senses the body's temperature and transmits it through a radio wave signal to an external receiver. The advantage of the pill over other temperature measurement devices is that it is a simple device that enables core temperature measurement for many hours without the need of any wire connections or other cumbersome instruments. For this reason, the pill is an ideal tool for core temperature measurements in field locales or for continuous long duration temperature monitoring of ambulatory patients. The following study reviews available literature concerning the use of the pill and the validity of its measurements. A high correlation has been revealed between pill temperature measurements and rectal or esophageal measurements. Pill temperature values usually fall between the high rectal and the low esophageal measurements, considered the gold standard for core temperature measurement. A number of studies emphasizing the advantage of the pill are presented in this review.

Administration, Oral↗
PubMed2001

Potential applications of heat and cold stress indices to sporting events.

Many recreational and elite athletes participate in sporting events every year. However, when these events are conducted under hostile environmental conditions, whether in cold or hot climates, the risk for environmental illnesses increases. The higher the stress, the greater is the potential for performance decrements, injuries and illnesses. The most common expected heat illnesses are heat exhaustion and heatstroke, whereas hypothermia and frostbite are the most common cold injuries. However, heat and cold stress indices can minimise the risk for environmental illnesses and dehydration by following the recommendations and guidelines which accompany these indices. Stress indices should be used by athletes, coaches and officials to prevent injury and improve safety conditions for competitors and participants in recreational activities. All participants should be made aware of warning signs, susceptibility and predisposing conditions. Coaches should be aware of their responsibility with regard to the safety of their trainees, and officials should organise and plan events at times that are likely to be of low environmental stress. However, they must also be prepared and equipped with the means necessary to reduce injuries and treat cases of collapse and environmental illnesses. The lack of a friendly, small and simple device for environmental stress assessment is probably the main reason why stress indices are not commonly used. We believe that developing a new portable heat and cold stress monitor in wristwatch format for use by those exposed to environmental stress could help in the decision making process of expected hazards caused by exercising and working in hostile environments, and might help prevent heat and cold illnesses.

Cold Temperature↗
PubMed2001

[Methods for core temperature measurements].

The measurement of core temperature is important for many clinical situations including heat illnesses, hypothermia, infections, sepsis, shock, hemorrhage, and exposure to chemical and biological agents. Currently, oral and rectal temperatures are clinically utilized for such measurements. However, oral measurements are not always possible and accurate whereas rectal measurements are not convenient in the field, are labor intensive, use fragile glassware containing mercury--an environmental contaminant, require sterilization and are not suited for mass casualties. A simple, non-invasive, non-breakable, inexpensive device to measure core temperature, which is not labor intensive, would have great use in the field and in hospitals, as well as provide an important advance in instrumentation for experimental physiology. The purpose of this work is to evaluate the different methods for core temperature measurement. Since the middle of the 18th century, the mercury thermometer has been almost the only instrument for measuring core temperature. Today, more sophisticated methods and instruments are gaining popularity. In addition, new promising converted techniques, which are about to enter the market and increase the available variety of instruments, might improve the situation as far as reliability and convenience of use are concerned. Despite the importance and usage of this variable, the progress in this field has been slower than would have been expected.

Body Temperature↗
PubMed2000

Exertional heat stroke--the prevention of a medical emergency.

In most cases, exertional heat stroke (EHS) can be prevented in the military setting. The actions taken by the Israel Defense Forces (IDF) and their outcome prove this well. Unfortunately, despite the available information, there are still incidents of failure of command in conducting physical exercise, leading to EHS. In our experience, most incidences are a consequence of disregarding safety regulations. The application of simple and reasonable measures will not only prevent accidents from happening, but will also result in better trained soldiers.

Adult↗
PubMed2000

Stress evaluation by the physiological strain index (PSI).

A physiological strain index (PSI) based on rectal temperature (Tre) and heart rate was recently suggested to evaluate exercise/heat stress. This review summarizes the development of PSI which was evaluated from seven different databases during the last three years. PSI was developed from data obtained from man performing exercise in the heat and from a separate database of man wearing protective clothing and exercising in hot-dry and hot-wet environmental conditions. This index was also evaluated for heat strain associated with hypohydration and for exercise/heat stress and gender. In addition, PSI was adjusted for values in rats, and could be used to assess the individual roles played by heat acclimation and exercise training in rats. This simple to use index scales strain to a range of 0-10, can be used on-line or during data analysis, and includes the ability to depict rest and recovery periods. The PSI has the potential to be widely accepted and to serve universally.

Animals↗
PubMed1999

Exertional heat stroke: a case series.

UNLABELLED: Exertional heat stroke (EHS) is a state of extreme hyperthermia that occurs when excess heat that is generated by muscular exercise exceeds the body's ability to dissipate it at the same rate. EHS is thought to coincide with previously healthy, highly motivated, and relatively untrained individuals exerting in hot environments for long periods. PURPOSE: To establish this notion, the present study was aimed to follow the trends in the incidence of EHS in the period 1988-1996. METHODS: During these years, 150 cases of male soldiers (age = 20+/-3 yr) were reported to our institute as suffering from heat illnesses. According to the files, 82 cases were definitely diagnosed as EHS. RESULTS: More than 50% of the cases occurred during the first 6 months in service. Most of the cases occurred during the summer season (June-September), but 30% of the cases occurred during the spring. EHS was not related to time in the day. Many cases occurred during the night or early morning, even under mild heat load. Forty percent of the cases occurred during very short activities, and about 60% occurred already during the first 2 h of exercise. The results were discussed in view of the regulations which prevail in the Israeli army. CONCLUSIONS: It seems that almost all EHS cases occurred when regulations were not strictly followed.

Heat Stroke↗
PubMed1999

Can gender differences during exercise-heat stress be assessed by the physiological strain index?

A physiological strain index (PSI) based on rectal temperature (Tre) and heart rate (HR) was recently suggested to evaluate exercise-heat stress. The purpose of this study was to evaluate PSI for gender differences under various combinations of exercise intensity and climate. Two groups of eight men each were formed according to maximal rate of O2 consumption (VO2 max). The first group of men (M) was matched to a group of nine women (W) with similar (P > 0.001) VO2 max (46.1 +/- 2.0 and 43.6 +/- 2.9 ml. kg-1. min-1, respectively). The second group of men (MF) was significantly (P < 0. 001) more fit than M or W with VO2 max of 59.1 +/- 1.8 ml. kg-1. min-1. Subjects completed a matrix of nine experimental combinations consisting of three different exercise intensities for 60 min [low, moderate, and high (300, 500, and 650 W, respectively)] each at three climates (comfortable, hot wet, and hot dry [20 degrees C 50% relative humidity (RH), 35 degrees C 70% RH, and 40 degrees C 35% RH, respectively]). No significant differences (P > 0.05) were found between matched genders (M and W) at the same exposure for sweat rate, relative VO2 max (%VO2 max), and PSI. However, MF had significantly (P < 0.05) lower strain than M and W as reflected by %VO2 max and PSI. In summary, PSI applicability was extended for exercise-heat stress and gender. This index continues to show potential for wide acceptance and application.

Adult↗
PubMed1999

Evaluating physiological strain during cold exposure using a new cold strain index.

A cold strain index (CSI) based on core (T(core)) and mean skin temperatures (T(sk)) and capable of indicating cold strain in real time and analyzing existing databases has been developed. This index rates cold strain on a universal scale of 0-10 and is as follows: CSI = 6.67(T(core t) - T(core 0)). (35 - T(core 0))(-1) + 3.33(T(sk (t)) - T(sk 0)). (20 - T(sk 0))(-1), where T(core 0) and T(sk 0) are initial measurements and T(core t) and T(sk t) are simultaneous measurements taken at any time t; when T(core t) > T(core 0), then T(core t) - T(core 0) = 0. CSI was applied to three databases. The first database was obtained from nine men exposed to cold air (7 degrees C, 40% relative humidity) for 120 min during euhydration and two hypohydration conditions achieved by exercise-heat stress-induced sweating or by ingestion of furosemide 12 h before cold exposure. The second database was from eight men exposed to cold air (10 degrees C) immediately on completion of 61 days of strenuous outdoor military training, 48 h later, and after 109 days. The third database was from eight men repeatedly immersed in 20 degrees C water three times in 1 day and during control immersions. CSI significantly differentiated (P < 0.01) between the trials and individually categorized the strain of the subject for two of these three databases. This index has the potential to be widely accepted and used universally.

Adult↗
PubMed1999

The physiological strain index applied to heat-stressed rats.

A physiological strain index (PSI) based on heart rate (HR) and rectal temperature (Tre) was recently suggested to evaluate exercise-heat stress in humans. The purpose of this study was to adjust PSI for rats and to evaluate this index at different levels of heat acclimation and training. The corrections of HR and Tre to modify the index for rats are as follows: PSI = 5 (Tre t - Tre 0). (41.5 - Tre 0)-1 + 5 (HRt - HR0). (550 - HR0)-1, where HRt and Tre t are simultaneous measurements taken at any time during the exposure and HR0 and Tre 0 are the initial measurements. The adjusted PSI was applied to five groups (n = 11-14 per group) of acclimated rats (control and 2, 5, 10, and 30 days) exposed for 70 min to a hot climate [40 degrees C, 20% relative humidity (RH)]. A separate database representing two groups of acclimated or trained rats was also used and involved 20 min of low-intensity exercise (O2 consumption approximately 50 ml. min-1. kg-1) at three different climates: normothermic (24 degrees C, 40% RH), hot-wet (35 degrees C, 70% RH), and hot-dry (40 degrees C, 20% RH). In normothermia, rats also performed moderate exercise (O2 consumption approximately 60 ml. min-1. kg-1). The adjusted PSI differentiated among acclimation levels and significantly discriminated among all exposures during low-intensity exercise (P < 0.05). Furthermore, this index was able to assess the individual roles played by heat acclimation and exercise training.

Acclimatization↗
PubMed1999

Wet bulb globe temperature (WBGT)--to what extent is GT essential?

BACKGROUND: Industrial and military safety personnel often require an easy, quick and accurate assessment of heat stress as a potential risk. The widely used WBGT index to evaluate heat stress is cumbersome and suited for a fixed site station rather than a mobile situation. Recently, a modified discomfort index (MDI) compiled from ambient temperature (Ta) and wet bulb temperature (Tw) was suggested to evaluate heat stress. HYPOTHESIS: Validation of the simple and easy-to-operate MDI on an independent database can determine whether this index is able to serve as a reliable and valid alternative to WBGT. METHODS: Four separate database sets obtained from the Marine Corps Training Site on Parris Island, SC, served to validate this index. Hourly weather measurements were collected daily during 4 yr, representing a wide range of environmental conditions. RESULTS: The MDI validity was tested vs. the WBGT index. A highly significant correlation coefficient (r) greater than 0.95 (p < 0.001) was found in each of the four database sets. CONCLUSIONS: The simply constructed and user friendly MDI is easier to calculate and use than WBGT, and it has the potential to serve as an attractive alternative to the WBGT index in assessing heat stress.

Heat Stress Disorders↗
PubMed1998

A physiological strain index to evaluate heat stress.

A physiological strain index (PSI), based on rectal temperature (Tre) and heart rate (HR), capable of indicating heat strain online and analyzing existing databases, has been developed. The index rates the physiological strain on a universal scale of 0-10. It was assumed that the maximal Tre and HR rise during exposure to exercise heat stress from normothermia to hyperthermia was 3 degrees C (36.5-39.5 degrees C) and 120 beats/min (60-180 beats/min), respectively. Tre and HR were assigned the same weight functions as follows: PSI = 5(Tret - Tre0) . (39.5 - Tre0)-1 + 5(HRt - HR0) . (180 - HR0)-1, where Tret and HRt are simultaneous measurements taken at any time during the exposure and Tre0 and HR0 are the initial measurements. PSI was applied to data obtained from 100 men performing exercise in the heat (40 degrees C, 40% relative humidity; 1.34 m/s at a 2% grade) for 120 min. A separate database representing seven men wearing protective clothing and exercising in hot-dry and hot-wet environmental conditions was applied to test the validity of the present index. PSI differentiated significantly (P < 0.05) between the two climates. This index has the potential to be widely accepted and to serve universally after extending its validity to women and other age groups.

Acclimatization↗
PubMed1998

Evaluation of different levels of hydration using a new physiological strain index.

A physiological strain index (PSI), based on rectal temperature (Tre) and heart rate (HR), was recently suggested for evaluating heat stress. The purpose of this study was to evaluate the PSI for different combinations of hydration level and exercise intensity. This index was applied to two databases. The first database was obtained from eight endurance-trained men dehydrated to four different levels (1.1, 2.3, 3.4, and 4.2% of body wt) during 120 min of cycling at a power output of 62-67% maximum O2 consumption (VO2 max) in the heat [33 degrees C and 50% relative humidity (RH)]. The second database was obtained from nine men performing exercise in the heat (30 degrees C and 50% RH) for 50 min. These subjects completed a matrix of nine trials of exercise on a treadmill at three exercise intensities (25, 45, and 65% VO2 max) and three hydration levels (euhydration and hypohydration at 3 and 5% of body wt). Tre, HR, esophageal temperature (Tes), and local sweating rate were measured. PSI (obtained from either Tre or Tes) significantly (P < 0.05) differentiated among all exposures in both databases categorized by exercise intensity and hydration level, and we assessed the strain on a scale ranging from 0 to 10. Therefore, PSI applicability was extended for heat strain associated with hypohydration and continues to provide the potential to be universally accepted.

Adult↗
PubMed1997

Heat intolerance induced by antidepressants.

A case in which prescription medications induced heat intolerance which led to heat stroke is presented. A subject who suffered from depression and was treated with fluoxetine HCL (prozac) and lithium carbonate was engaged in mild intermittent work for 4 hours under hot/dry climatic conditions (Ta = 37 degrees C, rh = 15%). The subject lost consciousness, was hyperthermic and suffered from disseminated intravascular coagulation. A year later residual cerebellar symptoms were still evident and severe atrophy of the cerebellar tissue was demonstrated in a CT scan. It is suggested that drug-induced heat intolerance was the predisposing factor that reduced the patient ability to sustain exercise-heat stress, and under the favorable environmental circumstances led to excessive heat accumulation which ultimately caused heat stroke. This is the first description, to our knowledge, of heat intolerance of a patient treated by a combination of fluoxetine and lithium carbonate.

Antidepressive Agents↗
PubMed1997

Heat-stroke-induced cerebellar atrophy: clinical course, CT and MRI findings.

We report the clinical course and CT and MRI findings in a case of heat-stroke-induced cerebellar atrophy. Although the cerebellar syndrome was severe concomitant with the onset of heat stroke, no abnormality was observed on brain CT in the first 2 weeks following the event. Cerebellar atrophy was first noted after 10 weeks on MRI; it was progressive during a 1-year follow-up.

Atrophy↗