Biomedical subjects

W A Bateman

Publications and source records attributed to W A Bateman.

5 recordsLinked to original sources

PubMed2001

G-transition effects and their implications.

G-transition effects are defined as the spectrum of physiological and psychophysical effects induced by rapid changes in gravitoinertial forces, alternating between hypogravity (<1 Gz) and hypergravity (>1 Gz) and vice versa. They appear to involve the cardiovascular and spatial orientation systems. This note attempts to briefly review past and current research efforts on the consequences of G-transitions and to examine potential confounding Coriolis-induced bias in both ground-based and inflight research. A brief review of current evidence of vestibular influence on orthostatic compensation and their implications for G tolerance is presented. The effects of roll-induced hypogravity on subsequent G tolerance and possible misperception of attitude during roll rotation are discussed. An integrated approach is recommended for future research on acceleration and disorientation.

Aerospace Medicine↗

PubMed2001

Basic recruit training: health risks and opportunities.

The present review examines the impact of basic recruit training on health and lifestyle. Many of those recruited begin training with a less than optimal lifestyle with respect to fitness, smoking habits, alcohol consumption, drug abuse, and exposure to sexually transmitted diseases. Thus, there is scope to enhance training programs that address fitness and lifestyle, minimizing potential losses in health and efficiency from upper respiratory infections, musculoskeletal injuries, cardiac catastrophes, mental disturbances, and adverse responses to extreme environments.

Acute Disease↗

PubMed1994

Effect of modafinil on heat production and regulation of body temperatures in cold-exposed humans.

Military personnel often undergo sustained operations that affect vigilance and alertness. Pharmacological agents may be used to enhance vigilance. Most such agents also have thermogenic properties. Whether a new promising stimulant, modafinil (Lyons and French, Aviat. Space Environ. Med. 1991; 62:432-435), has a beneficial effect on cold tolerance in the military context, is not known. The goal of this study was, therefore, to evaluate the effect of this new drug on thermal balance and the regulation of body temperatures in neutral conditions and when challenged by a cold exposure. Nine subjects underwent three trials each: two in the cold (3 h at rest, 10 degrees C) 0.5 h after the ingestion of either placebo or modafinil (200 mg), and one in thermal neutrality with modafinil (same conditions except Tdb = 29.3 degrees C). As expected, cold produced a drop in Tre and Tsk and an increase in Vo2. Although non-significant, there was a tendency for a slightly greater drop in Tre with modafinil (0.65 degrees C vs. 0.57 degrees C with placebo). A similar tendency was found for the heat debt (S) which was greater with modafinil than with placebo (16.1 +/- 0.7 vs. 14.7 +/- 0.6 kJ.kg-1, respectively, +9.5%, p = 0.11). This tendency appears to be the combined result of a slightly lower mean heat production during the test and a slightly greater mean dry heat loss. When tested at thermal neutrality, the drug had no effect on any thermal or metabolic parameters. The results demonstrate that the ingestion of a single dose of modafinil has no significant acute effect on thermal balance in neutral conditions and on thermoregulation in normal subjects exposed to cold. However, a tendency for slightly greater cooling was noted with modafinil. It is not known whether the use of modafinil in conjunction with sleep deprivation (a likely scenario) could magnify this effect.

Adult↗

PubMed1994

Influence of ondansetron on thermoregulation during exercise in the heat wearing combat clothing.

Ondansetron is a selective serotonin antagonist which has been shown to be an effective antiemetic agent for patients undergoing radiation or chemotherapy treatment. The Canadian Forces together with other NATO Countries have an interest in selecting an antiemetic agent that not only is effective in the prevention of emesis induced by chemical agents or radiation exposure, but also has minimal, if any, side effects. The purpose of this study was to examine the influence of a single 8-mg oral dose of the drug on thermoregulation during exercise in a hot (40 degrees C, 30% relative humidity) environment. Ten unacclimatized males performed a drug and placebo trial in single-blind random order. The sessions involved walking on a treadmill at 4.8 km.h-1 with a 2% elevation for a maximum of 3 h. Subjects wore combat clothing during the trials. Total exposure time was similar for the placebo (177 +/- 6 min) and drug (172 +/- 11 min) trials. Also, the rate of sweat production (0.64 +/- 0.1 and 0.66 +/- 0.1 kg.h-1 for placebo and drug, respectively) and body heat gain (303 +/- 112 and 305 +/- 110 kj for the placebo and drug, respectively) were not different between trials. Rectal temperature increased 1.48 +/- 0.40 degrees C for the placebo and 1.47 +/- 0.37 degrees C for the ondansetron trial. Finally, there was no difference in the mean skin temperature response which increased in both conditions to 37.1 +/- 0.5 degrees C. Under the conditions of this experiment, there is no evidence to suggest that the ingestion of ondansetron influences thermoregulation in a hot environment.

Adult↗

PubMedDate not supplied

Blood flow measurement using digital angiography and parametric imaging.

A method of blood flow measurement is described that determines flow through a particular artery in absolute units or as a fraction of the cardiac output. For measuring flow as a percentage of cardiac output, no assumption about the vessel's cross-sectional shape is necessary. If one assumes that the vessel's cross section is circular, then absolute flow determination is possible. All methods would require only a single intravenous injection of contrast material. Details of the theory of these methods are presented and alternative data analysis options are developed and discussed.

Angiography↗