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Biomedical subjects

T S Neuman

Publications and source records attributed to T S Neuman.

11 recordsLinked to original sources
PubMed1990

Effect of hyperbaric oxygen on murine neutrophil and T-lymphocyte functions.

We investigated the effect of repeated hyperbaric oxygen (HBO) exposure on PMN and T-lymphocyte functions in a murine model. Animals received eight 90-min exposures twice daily to 2.4 ata and 100% or 10% oxygen. Control animals were maintained in room air. On the ninth day spleens and peritoneal cell exudates were harvested. Phagocytosis was measured by flow-cytometric analysis of the ability of PMN to engulf formalin-killed, fluorescence-labeled Staphylococcus aureus. PMN-killing capacity was measured by the ability of PMN to undergo an oxidative burst after stimulation with N-formyl methionyl-leucyl-phenylalanine, phorbol myristate, or opsonized zymosan. T-lymphocyte subpopulations were identified using monoclonal antibodies and two-color flow cytometry after 48 h stimulation with phytohemagglutinin, and lymphocyte proliferation was measured by 3 H-thymidine incorporation. We found PMN phagocytosis and oxidative burst were unchanged after HBO treatment. Lymphocyte proliferation was decreased, and an activated population of CD8+ T cells appeared after mitogen stimulation. We conclude that, although PMN function is not affected by prior HBO, lymphocyte proliferation is decreased.

Animals↗
PubMed1990

Combined arterial gas embolism and decompression sickness following no-stop dives.

Decompression sickness (DCS) has been clinically classified as Type I (predominantly joint pain) or Type II (predominantly spinal cord lesions). We present 3 cases that are all characterized by severe (Type II) DCS with signs and symptoms of spinal cord injury occurring in conjunction with arterial gas embolism (AGE). We consider the AGE "minor" because only 2 of the 3 subjects initially lost consciousness, and in all cases the signs and symptoms of the AGE had essentially resolved within 1 h or by the time recompression therapy began. DCS was resistant to recompression therapy, even though treatment began promptly after the accident in 2 of the 3 cases. None of the cases had a good neurologic outcome and there has been one death. None of the divers exceeded the U.S. Navy "no-stop" limits for the depths at which they were diving. We have observed a previously unreported clinical syndrome characterized by severe Type II DCS subsequent to AGE following pressure-time exposures that would normally not be expected to produce DCS. We postulate that AGE may have precipitated or predisposed to this form of DCS.

Adult↗
PubMed1989

The impact of a regionalized trauma system on trauma care in San Diego County.

A review of autopsy reports on traumatic deaths in 1986 was conducted to determine the impact on trauma mortality of the regionalized trauma system instituted in San Diego County in 1984. Determination of preventable death was made by a panel of experts and compared with an identical review of traumatic deaths in 1979, five years before the institution of regionalized trauma care. Of 211 traumatic deaths reviewed from 1986, two (1%) were classified as preventable, compared with 20 of 177 (11.4%) deaths in 1979 (P less than .001). A breakdown of trauma deaths into central nervous system and noncentral nervous system categories revealed the overall decline was in large part a consequence of the decline in non-central nervous system deaths from 16 of 83 in 1979 to one of 62 in 1986 (P less than .005). The decrease in central nervous system-related preventable deaths from four of 94 in 1979 to one of 149 in 1986 (P less than .10) was not statistically significant. Although it is likely the trauma system introduced in 1984 contributed to the decline in preventable death, it is not possible to isolate this variable from other changes that occurred during the interval between studies. A review of trauma deaths over the same time interval in a community with similar demographics but without a trauma system might help determine the relative contribution of the trauma system.

Adult↗
PubMed1987

Diving medicine.

This article orients the practicing physician to the physical and physiologic basis for the more common medical problems encountered in diving, discusses the common presenting manifestations for these disorders, and provides a framework for their treatment. Medical fitness for diving is also briefly addressed.

Barotrauma↗
PubMed1979

Urinary excretion of water and electrolytes during open-sea saturation diving to 850 fsw.

The dive was carried out in the open sea to a depth of 850 fsw (26.7 ATA) for 6 days (DD 1--6) in the saturated mode, with personnel transfer capsule (PTC) excursions between 0 and 150 fsw and diver excursions between 0 and 50 fsw from the saturation base. Each diver had two excursion dives on alternate days. Although each PTC excursion lasted approximately 7 h, the actual time spent in the water averaged 10.5 min per diver. For 12 divers, daily excretion of water, electrolytes, aldosterone, and antidiuretic hormone (ADH) was studied, along with plasma composition (including prolactin), before, during, and after hyperbaric exposure. A significant increase in urine flow was observed on DD2--4 (1604 ml/day predive vs. 2300 ml/day on DD 4; P less than 0.05), after which the degree of diuresis decreased to about 1800 ml/day. Urine osmolality changed inversely with urine flow, with the lowest value of 532 mOsm/kg on DD 4. During the postdive period, both urine flow and urine osmolality returned to the predive level. The endogenous creatinine clearance was maintained at about 200 liters/day throughout the dive. The fractional excretion of Na+ remained unchanged while that of K+ increased significantly during hyperbaric exposure, thus decreasing the urinary Na+/K+ ratio. The fractional excretion of total osmotic substances showed a small hyperbaric exposure. Body weight decreased progressively during the initial 4 days of pressure exposure, equalling 2.6 kg on DD 4. These findings suggest that the observed diuresis may be accompanied by a net loss of body water. Neither the plasma prolactin level nor urinary excretion of aldosterone and ADHshowed any consistent change throughout the dive. It thus appears that, although there is a small osmotic component, the observed diuresis is primarily due to the ADH-independent inhibition of fre water reabsorption from the collecting duct by means of a mechanism yet to be identified.

Adult↗
PubMed1978

Diving experience and emotional factors related to the psychomotor effects of nitrogen narcosis.

Simple and complex psychomotor performance were tested among 21 Navy divers under normal conditions and during nitrogen narcosis in simulated dives to 170 ft of sea water. Complex psychomotor performance was impaired significantly during narcosis, while simple psychomotor performance remained essentially normal. Differences between baseline scores for complex psychomotor performance (pre- and post-dive combined) and scores obtained from the two combined testing sessions administered during narcosis were correlated with official Navy records of diving experience and self-reported moods. None of the diving experience measures was associated significantly with these difference scores. The moods of Fatigue and Happiness were, however, correlated significantly with impairment. These results indicate that, although previous experience with nitrogen narcosis and diving tasks do not mediate the performance effects of nitrogen narcosis, the complex psychomotor effects nitrogen narcosis are related to emotional traits.

Adult↗
PubMed1977

Venous gas bubbles: production by transient, deep isobaric counterdiffusion of helium against nitrogen.

When awake goats were subjected to isobaric gas switching from saturation (17 hours) on 4.7 atmospheres of nitrogen (0.3 atmosphere of oxygen) to 4.7 atmospheres of helium (0.3 atmosphere of oxygen), bubbles detected by 5-megahertz Doppler ultrasound in the posterior vena cava 20 to 60 minutes after the switch continued for 4 hours. Similar experiments carried out at 6.7 atmospheres of inert gas and 0.3 atmosphere of oxygen produced more bubbles for as long as 12 hours after the gas switch. This is believed to be the first objective demonstration of the phenomenon of deep isobaric supersaturation under transient operational diving conditions at relatively shallow diving depths. Detection of bubbles by Doppler ultrasound confirms the potential importance of the phenomenon to shallow saturation diving and holds promise for better quantitification of its effects as well as those of its counterpart, isobaric undersaturation, which can confer a decompression advantage.

Animals↗
PubMed1976

Blood viscosity in man following decompression: correlations wiht hematocrit and venous gas emboli.

Whole blood viscosities were measured in U.S. Navy personnel before and after chamber compressions to 5 ATA (132FSW) and 7.4 ATA (210 FSW) by a new method described here. Bubble scores as a quantitative measure of venous gas emboli were determined during decompression and for 30 min thereafter. Hematocrit was measured both before and after each dive. There were five cases of decompression sickness in the two groups. No significant changes in whole blood viscosity, or hematocrit, were noted either in the group that was affected by decompression sickness or in all of the subjects taken as a group. No correlations between total bubble score and changes in viscosity or hematocrit could be made. These results imply that no major changes in viscosity occur in the usual forms of decompression sickness encountered in human beings.

Blood Viscosity↗
PubMed1976

Hematologic changes in man during decompression: relations to overt decompression sickness and bubble scores.

In order to determine whether asymtomatic gas phase separation causes hematologic abnormalities, studies were carried out following two dive series, one to 210 feet of sea water (FSW) for 50 min and the other to 132 FSW for 30 min. Studies included white and red cell count, red cell indices, platelet count, ESR, fibrinogen, fibrin split products, prothrombin time, partial thromboplastin time, coagulation factors II, V, VII, VIII, and X, clot retraction, platelet aggregation and adhesion, euglobulin lysis time, and platelet factor III. Changes were seen in platelet and white cell count, prothrombin time and partial thrombo-plastin time. White cell count was the only variable which correlated with total bubble score. The results are presented and implications of the findings discussed.

Adult↗
PubMed1976

Gas phase separation during decompression in man: ultrasound monitoring.

During two dive series, one to 132 fsw and one to 210 fsw, Doppler ultrasonic bubble detectors were used to monitor venous gas bubbles in divers during decompression and for 30 min thereafter. Various decompression schedules were used. Bubble scores were evaluated by independent listerners to tape recordings in a blind manner. A significant increase in bubble scores throughout the stages of decompression and postdecompression was demonstrated as well as a statistically significant relationship between bubble score and decompression sickness. A reduction in mean bubble score was found in divers who made an additional deep decompression stop that was unrelated to the extension of the decompression time. The implications of these findings are discussed.

Adult↗