Biomedical subjects

Arie Laor

Publications and source records attributed to Arie Laor.

8 recordsLinked to original sources

PubMed2005

Large lungs in divers: natural selection or a training effect?

BACKGROUND: Normal spirometry is required for medical clearance of professional divers in many countries. Divers frequently have unusually large lung volumes associated with a low ratio of FEV(1) to FVC (FEV(1)%), suggestive of obstructive airways disease. We retrospectively analyzed the records of divers in the Israeli Navy with a low FEV(1)% who fulfilled the criteria for large lungs, to determine whether this might be the effect of training or natural selection. We also investigated changes in pulmonary function in relation to diving experience. METHODS: A total of 171 divers with FEV(1)% < 80% on simple spirometry were evaluated. We conducted a retrospective analysis of lung function data for those subjects who met the criteria for large lungs. RESULTS: One hundred nine of 171 divers with low FEV(1)% met the criteria for large lungs and were included in the study. Their average age was 25 years (range, 18 to 44 years), and their mean diving experience was 7 years (range, 0 to 26 years). No difference was found in FVC values between experienced and inexperienced divers. The mean forced expiratory flow at 50% of vital capacity was significantly reduced in the most experienced group compared with the novice or less experienced divers. No difference was found in the diffusing capacity of the lung for carbon monoxide between experienced and inexperienced divers. CONCLUSIONS: We suggest that large lungs may represent part of the natural selection for diving, rather than a training effect. Prolonged diving experience may result in the development of small airways disease.

Adolescent↗

PubMed2004

Assessment of heat tolerance for post exertional heat stroke individuals.

BACKGROUND: The aim of this study was to evaluate the heat tolerance test, which was performed by individuals with high risk for heat injuries, for exposure duration and climatic conditions. MATERIAL/METHODS: Nineteen young (19+/-1 yr) post heat stroke males performed 2 separate tolerance tests consisting of identical treadmill walking (5km.h-1, 2% grade) for 120 min during hot (40 degrees C, 40%RH) and comfort (20 degrees C, 50%RH) climate conditions. Physiological monitoring included rectal temperature (Tre), heart rate (HR), skin temperature and sweat rate (msw). Concomitantly, strain evaluation was assessed by the physiological strain index (PSI) and the cumulative heat strain index (CHSI). RESULTS: 14 subjects were categorized as heat tolerant (HT) and 5 subjects as heat intolerant (HI). The comfort tolerance test was found as irrelevant for heat intolerance assessment. PSI after 60 min (PSI60) was unable to predict PSI after 120 min (PSI120) whereas there was not a high enough correlation between CHSI60 and CHSI120. CONCLUSIONS: It was concluded that tolerance to heat must be tested during heat stress and the test duration cannot be shorter than 120 min.

Adult↗

PubMed2004

Human ACE I/D polymorphism is associated with individual differences in exercise heat tolerance.

We hypothesized that there is an association between the angiotensin I-converting enzyme (ACE) insertion (I)/deletion (D) polymorphism with the variability in exercise heat tolerance in humans. Fifty-eight Caucasian men were exposed to a 2-h exercise heat-tolerance test. We analyzed the association between their heat-tolerance levels with the ACE DD (n = 25) and I+ (n = 33) genotypes and with various anthropometrical parameters and aerobic fitness. It was found that the relative changes in body core temperature, heat storage, and heart rate during the 120-min exposure to exercise heat stress was consistently lower in the I+ genotype group compared with the DD genotype group (0.8 +/- 0.2 vs. 1 +/- 0.1 degrees C, P < 0.05; 17.7 +/- 1.8 vs. 19.8 +/- 1.3 W/M(2), P < 0.05; and 33 +/- 7 vs. 44 +/- 5 beats/min, respectively, P = 0.06). No significant association was found between heat strain response and the anthropometrical measurements or aerobic fitness in the various genotype groups. We suggest that the ACE I+ polymorphism may be considered as a possible candidate marker for increased heat tolerance.

Adult↗

PubMed2004

Relationship between changes in neck circumference and changes in blood pressure.

OBJECTIVE: Neck circumference (NC), as an upper body obesity index, is a simple screening measure for identifying overweight and obese patients. This study examines a relationship between changes in systolic blood pressure (BP), and diastolic BP and changes in NC, and other components of the metabolic syndrome. METHODS: In a longitudinal cohort study the study group was comprised of 364 subjects (155 men and 209 women) with no known major medical conditions who were not receiving any medication therapy. Main indicators studied included systolic BP, diastolic BP, NC, waist circumference (WC), waist-to-hip ratio (WHR), lipoprotein, glucose, and uric acid levels. RESULTS: Pearson's correlation coefficients indicated a significant association between changes in systolic BP and changes in NC (men, r = 0.54; women, r = 0.56; each, P <.0001), WC men, r = 0.51; women, r = 0.56; each, P <.0001), triglycerides (men, r = 0.41; women, r = 0.44; each, P <.0001), and glucose (men, r = 0.43, P <.001; women, r = 0.48, P <.0001); between changes in diastolic BP and changes in NC (men, r = 0.56; women, r = 0.68; each, P <.0001), WC (men, r = 0.62; women, r = 0.50; each, P <.0001), triglycerides (men, women; each, r = 0.39, P <.0001), and glucose (men, r = 0.45; women, r = 0.49; each, P <.0001). CONCLUSIONS: Changes in systolic BP and diastolic BP correlated positively with changes in NC and other components of the metabolic syndrome.

Adult↗

PubMed2004

Hydration status measurement by radio frequency absorptiometry in young athletes--a new method and preliminary results.

A new method for non-invasive measurement of the human state of hydration is presented. This method is based on frequency-dependent absorptiometry of radio-waves passing through tissues. A device utilizing this method was constructed and applied to 12 young (24 +/- 1) male volunteers, who were dehydrated for 1-2.5% of their weight by performance of a physical effort (two 30 min bouts of treadmill walking/running at 2, 3, 4, 5, 6 and 7 mph, 5 min at each speed, separated by 10 min rest), under moderate heat stress (40 degrees C, 40% RH). Hypohydration level was determined by body weight measurements taken before each session, after 30 min and at the end of each session. Concomitantly, measurements of radio frequency (RF) absorption were taken. Each volunteer underwent the heat stress exercise twice: one in which no drinking was permitted, and another with free drinking. A correlation (R2 = 0.734) between weight loss and a change in the radio-waves absorption pattern was observed in most of the volunteers, in both hypo and euhydration sessions. Further work to establish the reproducibility and validity of the RF methodology in larger and different populations, i.e., females, other age groups and different health conditions, is already being researched.

Adult↗

PubMed2003

Relationship of neck circumference to cardiovascular risk factors.

OBJECTIVE: To determine a relationship between neck circumference (NC) and risk factors for coronary heart disease by evaluating the components of the metabolic syndrome. RESEARCH METHODS AND PROCEDURES: The study group included 561 subjects (231 men and 330 women) who had no known major medical conditions and were not receiving any medication therapy. The subjects were those who attended a family health clinic for any reason between 1998 and December 2001. Main indicators studied included NC, waist circumference, waist-to-hip ratio, body mass index, blood pressure, and lipoprotein, glucose, and uric acid levels. RESULTS: Pearson's correlation coefficients indicated a significant association between NC and body mass index (men, r = 0.71; women, r = 0.81; each, p < 0.0001), waist circumference (men, r = 0.75; women, r = 0.79; each, p < 0.0001), waist-to-hip ratio (men, r = 0.56; women, r = 0.63; each, p < 0.0001), total cholesterol (men, r = 0.50; women, r = 0.66; each, p < 0.0001), low-density lipoprotein-cholesterol (men, r = 0.42; women, r = 0.60; each, p < 0.0001), triglycerides (men, r = 0.48; women, r = 0.49; each, p < 0.0001), glucose (men, r = 0.21, p < 0.001; women, r = 0.44; p < 0.0001), uric acid (men, r = 0.50, p < 0.0001; women, r = 0.60, p < 0.001), and systolic (men, r = 0.53; women, r = 0.69; each, p < 0.0001), and diastolic (men, r = 0.55; women, r = 0.65; each, p < 0.0001) blood pressure. DISCUSSION: Higher NC is correlated positively with the factors of the metabolic syndrome; therefore, it is likely to increase the risk of coronary heart disease.

Adolescent↗

PubMed2003

A prospective randomized controlled study of phototherapy using blue and blue-green light-emitting devices, and conventional halogen-quartz phototherapy.

OBJECTIVE: To determine the efficacy of blue versus blue-green phototherapy using new light sources with narrow luminous spectra. The devices made of high-intensity gallium nitride light-emitting diodes (LEDs) were also compared to conventional halogen-quartz bulbs phototherapy. DESIGN: Prospective open randomized study. PARTICIPANTS: A total of 114 jaundiced, but otherwise healthy term infants who met the entry criteria for phototherapy set by the American Academy of Pediatrics' Practice Parameter. MAIN OUTCOME MEASURES: The duration of phototherapy and the rate of decrease in total serum bilirubin (TSB). RESULTS: The mean TSB concentrations at initiation and termination of treatment, as well as the duration of phototherapy and the rate of decrease in TSB, were not statistically different in newborns receiving blue LED, blue-green LED or conventional phototherapy. The average rate of decrease in TSB (slope), after adjustment by a linear regression analysis for confounding factors, was -3.61 micromol/hour (95% confidence limits -5.47, -1.75) in the 25 newborns receiving blue LED phototherapy compared with -2.57 micromol/hour (-4.32, -0.82) in the 22 newborns treated with blue-green LED phototherapy and -3.42 micromol/hour (-5.02, -1.81) in the 57 newborns who received conventional phototherapy. CONCLUSIONS: When using low light irradiance, there was no statistically significant difference in the effectiveness of phototherapy using blue-green LEDs, blue LEDs or conventional halogen-quartz bulbs.

Bilirubin↗

PubMedDate not supplied

Cumulative pregnancy rate following IVF and intracytoplasmatic sperm injection with ejaculated and testicular spermatozoa.

The purpose of this study was to calculate the cumulative pregnancy rates of IVF cycles with ICSI using ejaculated or testicular spermatozoa. A computerized database for the IVF cycles with ICSI performed between January 1996 and December 1998 was utilized. Cycles with spermatozoa obtained after electro-ejaculation were excluded. A multifactorial analysis was performed to define the impact of different factors on the success rate of IVF and ICSI. During a 36-month period, 229 pregnancies were achieved by 643 couples using ejaculated spermatozoa, and 83 pregnancies by 167 couples who required testicular spermatozoa. The pregnancy rates (PR) per cycle, including all treatment cycles with ejaculated spermatozoa, remained similar during the first five consecutive cycles achieving a cumulative PR of 80.44%. The cumulative pregnancy rates for cycles with testicular spermatozoa showed a consistent rise during four consecutive treatments and reached 61.84%. The regression analysis of pregnancy rate showed that it was significantly positively correlated with oocyte fertilization rate (P = 0.02), and negatively correlated with maternal age (P = 0.03). Thus, according to the present results, couples with infertility who require IVF with ICSI should be offered at least five consecutive attempts if ejaculated spermatozoa are used, and at least four cycles whenever testicular spermatozoa are used.

Ejaculation↗