Etiology of low back pain in elite boardsailors.

Seven elite boardsailors reporting nonradiating low back pain without leg pain during sailing volunteered for detailed examination. In these subjects, the onset of pain was limited to those occasions when sailing positions were held for a significant period of time, e.g., close hauled sailing or in light winds. No pain was described at any other time. The determination of possible antecedent factors was based on the results of clinical assessment, radiological evaluation, and computer tomography (CT) scanning. Apart from limited flexibility in some subjects, the clinical examination of these athletes was normal; CT changes in this group were limited to disc protrusions and bulges, and pars interarticularis defects. Despite the small number of subjects in the present report, it appears that the frequency of these problems exceeds that in the normal population. It may be possible to suggest that risk factors such as body position during prolonged sailing, particularly under light wind conditions without a harness, and limited flexibility may be associated with the radiological findings and may be implicated in the presence of low back pain, although further investigations appears warranted.     

Sentinel surveillance of human immunodeficiency virus infection in women seeking reproductive health services in the United States, 1988-1989. The Field Services Branch.

Cases of AIDS among women of reproductive age have increased dramatically since 1981; nearly a third of all cases among females were reported in 1990 alone. Surveillance of human immunodeficiency virus (HIV) infection among women is essential for monitoring the spread of HIV over time and identifying specific populations and geographic areas in need of HIV counseling, testing, and prevention services. Blinded (unlinked) serologic surveys were conducted in the United States and Puerto Rico in sentinel clinics providing reproductive health services to women, including family planning, prenatal care, and abortion services. Seventy-eight of 94 clinics (83%) in 30 cities conducting surveys during 1988 and 1989 detected at least one HIV-positive woman. Clinic-specific prevalence ranged from 0-2.28% (median 0.22%), with rates over 1% occurring in clinics predominantly on the East Coast and in Puerto Rico. Seroprevalence varied by primary type of service, race-ethnicity, and age group. Median rates were higher in clinics offering prenatal services and lower in abortion and family planning clinics in the same cities. In general, women 25-29 years of age showed the highest median rate of infection (0.32%), and rates were higher among black women (median 0.34%) than among Hispanic (median 0.11%) and white women (median 0%). Our data indicate the need to educate women about recognizing and reducing their risk of HIV infection. Reproductive health clinics with high seroprevalence should implement voluntary HIV counseling and testing with appropriate follow-up clinical evaluation and referral for infected women. Clinics with low prevalence should seize the opportunity to enhance HIV education and prevention efforts.     

Effects of alterations in left ventricular filling, contractility, and systemic vascular resistance on the ascending aortic blood velocity waveform of normal subjects.

OBJECTIVES: To confirm the consistent effects on Doppler-measured aortic blood flow velocity waveform variables of alterations in left ventricular preload, afterload, and inotropy using pharmacologic and physiologic maneuvers. SETTING: Medical school laboratory. SUBJECTS: Healthy volunteers. INTERVENTIONS: Increasing infusion rates of dobutamine (1.25 to 5 micrograms/kg.min), esmolol (1.25 to 5 mg/min), phentolamine (1.25 to 5 mg/min), methoxamine (1.25 to 5 mg/min), metaraminol (1.25 to 5 mg/min), and placebo (1.25 to 5 mL of 0.9% saline/min) and increasing plasma removal (0.5 to 1 L) in awake, rested, supine subjects. MEASUREMENTS AND MAIN RESULTS: Ascending aortic blood flow was measured by the suprasternal Doppler approach allowing calculation of waveform variables of stroke distance and minute distance (linear measures of stroke volume and cardiac output), peak velocity, mean acceleration and flow time corrected for heart rate. An index of systemic vascular resistance was obtained by dividing mean systemic BP by the minute distance. Inotropic changes predominantly affected peak velocity and mean acceleration. Changes in preload mainly affected the flow time corrected for heart rate, whereas afterload changes had an intermediate effect. Unsuspected but subsequently confirmed hemodynamic effects were seen with esmolol and metaraminol. CONCLUSIONS: Aortic blood flow velocity waveform variables measured by Doppler ultrasound can be used to noninvasively follow changes in left ventricular preload, afterload, and inotropy.     

Sexual behavior and 2-deoxyglucose uptake in male red-sided garter snakes (Thamnophis sirtalis parietalis).

The [14C]2-deoxyglucose (2-DG) technique was used to study patterns of neural activity associated with the species-typical courtship behavior of male red-sided garter snakes (Thamnophis sirtalis parietalis). Males in this species court females intensely during the first month following spring emergence from their prolonged winter hibernation. Autoradiographic methods were used to measure the accumulation of radioactive label in various regions through the brains of male garter snakes that courted females, males that failed to court females, and males not exposed to females. Male garter snakes that actively courted females showed a pronounced increase in 2-DG accumulation, and therefore presumably neural activity, in the region of the anterior hypothalamus/preoptic area, relative to males that did not actively court females. Males exposed to females (regardless of whether they courted or not) showed widespread, non-specific increases in 2-DG uptake relative to males not exposed to females. The results indicate the utility of the 2-DG technique for studying complex, species-typical behaviors in vertebrates.     

Brain metabolism and blood flow in acute cerebral hypoxia studied by NMR spectroscopy and hydrogen clearance.

We have developed a reliable, reproducible model of hypoxia in the gerbil. 1H and 31P NMR spectroscopy demonstrates that cerebral energy metabolism is very resistant to hypoxia. Cerebral blood flow (measured by hydrogen clearance) began to increase when the arterial oxygen tension (paO2) was reduced to 40-50 mm Hg, and there was no change in phosphorus metabolites or lactate until paO2 was below 40 mm Hg. In 50% of the animals lactate increased prior to any change in the phosphorus metabolites or intracellular pH, suggesting that 1H NMR may be more sensitive than 31P NMR at detecting hypoxic or ischaemic changes. The calculated rate of oxygen delivery at a time when phosphorus energy metabolism becomes impaired is similar in both hypoxia and ischaemia (ca 4mL/100 g/min). We suggest that the critical factor in ischaemia is the reduction in oxygen supply, rather than the accumulation of toxic metabolites, such as lactate.