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Biomedical subjects

L S Smith

Publications and source records attributed to L S Smith.

At least 91 records · Page 5Linked to original sources
PubMed1980

High-performance liquid chromatography of acid-stable and acid-labile phosphoamino acids.

A high-performance liquid chromatographic system has been developed which permits the separation of both acid-stable and acid-labile phosphoamino acids. An anion-exchange resin and two buffers of different ionic strength and near neutral pH are used. A low-ionic-strength buffer is used for the separation of N-omega-phosphoarginine and N-epsilon-phospholysine, while the higher-ionic-strength buffer permits the clear separation of tau-phosphohistidine, omicron-phosphoserine and omicron-phosphothreonine. An in-stream fluorometric detection system using omicron-phthalaldehyde permits the rapid analysis of samples containing as little as 25 pmoles of phosphoamino acid. This method has been applied to the detection of tau-phosphohistidine from alkaline digests of chemically phosphorylated calf thymus histone 4 and bovine myelin basic protein.

Amino Acids↗
PubMed1980

Hematologic response of fish to changes in gas or hydrostatic pressure.

Hematologic changes were studied in fingering salmon after rapid decompression from combined or independent exposure to gas and hydrostatic pressure. After decompression, fingerling salmon saturated with excess gas under pressure (10.1-40.6 m of seawater) suffered a decrease in thrombocyte counts and fibrinogen, prolonged prothrombin (PT) times, and increased fibrinolytic activity, plasma proteins, and erythrocyte counts in proportion to severity of the dive. After decompression, fingerling salmon exposed to increased pressure experienced an increase in thrombocyte counts and available fibrinogen, shortened PT times, increased erythrocyte counts, and decreased plasma protein levels. It appeared that pressure causes activation of the blood coagulation system of fish. This activation may predispose the fish to increased susceptibility to bubble-induced diffuse intravascular coagulation after rapid decompression. Furthermore, hemoconcentration after decompression may be a pressure-related phenomenon and not a response to bubble-induced anoxia.

Animals↗
PubMed1980

Separation of basic parameters of decompression using fingerling salmon.

The experimental limitations inherent in use of air-breathing vertebrates for studies of decompression are chiefly due to the difficulty in estimating supersaturation levels associated with both symptoms of decompression sickness and bubble formation. The difficulty is because gas elimination begins upon reduction of pressure and therefore complicates any estimates of the supersaturations that promoted the bubbles or symptoms, or both, in the first place. Use of physostomatous fish such as salmonid fingerlings easily available from hatcheries allows decompression of both fish and surrounding water, thereby minimizing gas tension gradients from the fish to the water and the water to the fish. Depending upon the experimental conditions imposed, the important physical properties such as diffusivity and solubility of different diving gases, H2, Ne, He, and N2, can be separated or combined parametrically. Results of these studies indicate that initial bubble formation in vivo is relatively independent of solubility, whereas the bubble growth phase is more dependent on gas concentration.

Animals↗
PubMed1977

WAIS functioning of cirrhotic and non-cirrhotic alcoholics.

This study was done to determine whether the cognitive dysfunction often found in chronic alcoholics would be greater for alcoholics with Laennec's cirrhosis than for alcoholics without cirrhosis. It was hypothesized that cirrhotic alcoholics would score lower than non-cirrhotic alcoholics, who in turn would score lower than non-alcoholic, non-cirrhotic controls on (1) WAIS Verbal, Performance, and Full Scale IQ; (2) scaled score configuration; and (3) the Wechsler Deterioration Quotient. The WAIS was administered in a Veterans Administration Center to 60 Caucasian male patients aged 35-64 who had been assigned to one of the three groups (N = 20 per group). No differences were found among groups on age, education, or the Information and Vocabulary subtests (p greater than .05). Significant differences (p less than .05) were found on Verbal, Performance, and Full Scale IQ, the remaining nine subtests, and the Deterioration Quotient. A stepwise discriminate function analysis substantiated these differences. It was concluded that Laennec's cirrhosis is a physical condition that negatively affects intellectual functioning in alcoholics.

Adult↗
PubMed1976

Comparison of machine and manual staining of direct smears for acid-fast bacilli by fluorescence microscopy.

Comparisons were made in Lusaka and in London between manual staining and staining in an automatic machine with auramine-phenol of direct smears of sputum and other types of specimen for acid-fast bacilli. No evidence was obtained of carry-over of acid-fast bacilli from positive to negative smears during machine staining. There was improved contrast between bacilli and the background in smears prepared with the machine.

Benzophenoneidum↗
PubMed1976

Decompression-induced bubble formation in salmonids: comparison to gas bubble disease.

The relationship of gas bubble disease (GBD) in fish to decompression-induced bubble formation was investigated with salmonids. Acute bioassays were used to determine equilibration times for critical effects in fish decompressed from depths to 200 fsw. It was found that equilibration of critical tissues was complete in 60-90 min. Salmonids and air-breathers are sensitive to decompressions at similar levels of supersaturation if elimination of excess gas following decompression is unrestricted. However, if elimination is restricted, bubble formation and growth increase accordingly. Tests with mixtures of He-O2, Ar-O2, N2-O2 (80% inert gas: 20% O2) and pure oxygen demonstrated that gas solubility as well as supersaturation (delta P), pressure ratio (initial pressure: final pressure), and absolute pressure must be considered in setting tolerance limits for any decompression. Gases with higher solubility are more likely to produce bubbles upon decompression. Oxygen, however, does not follow this relationship until higher pressures are reached, probably owing to its function in metabolism and in binding with hemoglobin. Tissue responses observed in both GBD and decompressed fish involved similar pathological effects at acute exposures. The circulatory system was consistently affected by bubbles that occluded vessels and blocked flow through the heart.

Animals↗
PubMed1976

The response of fish blood cells, particularly thrombocytes, to decompression.

The effects of decompression on various blood-cell types in chinook salmon (Oncorhynchus tshawytscha) were investigated using a 4-liter hyperbaric chamber. Thrombocytes (platelets) were found to decrease significantly in numbers following lethal and nonlethal decompressions. The response was highly dependent on depth, gas solubility, and rate of decompression, whereby increasing depth or gas solubility caused greater and faster declines of thrombocyte levels. Return of thrombocyte numbers to normal values usually occurred within 48 hours, except after the more severe decompressions where recovery was never fully attained during the sampling period. Erythrocyte levels increased significantly 1 day after a severe decompression, suggesting hemoconcentration. Leucocytes appeared not to respond to decompression; they were not decreased compared to normal levels, although they were significantly decreased compared to levels of the chamber controls in the nonpressurized chamber. The results are discussed in relation to possible involvement of the fish's blood-coagulation system after decompression.

Animals↗
PubMed1975

Changes in hemostatic parameters in fish following rapid decompression.

The effect of rapid decompression on the stress-accelerated blood coagulation system of male and fingerling coho salmon (Oncorhynchus kisutch) was examined after simulated 100- and 200-fsw dives. Blood samples taken either through a dorsal aorta cannula or from a severed caudal peduncle were analyzed for total plasma protein and fibrinogen concentrations, prothrombin times (PT), and partial thromboplastin times (PTT). The effect of mild decompression (100-fsw) on the hemostatic mechanism of both adult and fingerling coho salmon indicated an alternating fibrinogen concentration, declining from normal levels 1 min after decompression, followed by an increase 10 to 15 min later with an eventual loss of fibrinogen to one half the original level an hour after decompression. Partial thromboplastin times were found to increase 10 to 15 min after decompression occurred. Prothrombin times showed an increase 1 hour after decompression in adult salmon, whereas in fingerlings, prothrombin times increased almost immediately from normal levels. The effect of severe decompression (200-fsw) showed similar trends, but at an accelerated rate. It was concluded that both mild and severe decompression activates the hemostatic mechanism of fish which may eventually result in consumption coagulopathy at a greater rate than reported for experimental mammals.

Age Factors↗
PubMed1974

Bends in fish.

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Air↗
PubMed1973

Microbiological profiles of four Apollo spacecraft.

Selected surfaces from the Command Module, Lunar Module (ascent and descent stages), Instrument Unit, Saturn S-4B engine, and Spacecraft Lunar Module Adapter comprised the various components of four Apollo spacecraft which were assayed quantitatively and qualitatively for microorganisms. In addition, the first Lunar Roving Vehicle was assayed. Average levels of microbial contamination (10(4) per square foot of surface) on the Command Module, Instrument Unit, and Saturn S-4B engine were relatively consistent among spacecraft. The first postflight sampling of interior surfaces of the Command Module was possible due to elimination of the 21-day back-contamination quarantine period. Results of the pre- and postflight samples revealed increases in the postflight samples of 3 logs/inch(2). A total of 5,862 microbial isolates was identified; 183 and 327 were obtained from the Command Module at preflight and postflight sampling periods, respectively. Although the results showed that the majority of microorganisms isolated were those considered to be indigenous to humans, an increase in organisms associated with soil and dust was noted with each successive Apollo spacecraft.

Actinomycetales↗
PubMed1968

Death certificates.

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Death Certificates↗