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Biomedical subjects

M Smith

Publications and source records attributed to M Smith.

At least 1,369 records · Page 76Linked to original sources
PubMed1976

Pressure antagonism of barbiturate anesthesia.

The losses of righting reflex produced by various doses of phenobarbital in mice at 1 atm O2 versus 1 atm O2 plus 102 atm He were determined. The resulting dose-response curve at pressure gave an ED50 that was 64 per cent larger than the ED50 at 1 atm. This increment is essentially the same as that found for gaseous anesthetics under similar test conditions. The quantitative similarity of the results of pressure reversals of barbiturate and inhalational anesthetics suggests that the mechanisms or sites of action of these agents are similar. However, the dose-response curve at 103 atm was steeper than that at 1 atm. This raises an alternative possibility that anesthetics and pressure bear no mechanistic relationship to each other, but rather that pressure produces a generalized central nervous system stimulation that would antagonize any depressant effect.

Anesthesia, Inhalation↗
PubMed1976

Chromosomal assignment of the HL-A common antigenic determinants in man-mouse somatic cell hybrids.

In the study presented here, man-mouse somatic cell hybrid clones were examined by means of radioimmunoassays for the presence of both beta2-microglobulin (beta2m) and the HL-A xenoantigenic determinant. In addition, the clones were examined for their karyotype and the expression of enzymes with known chromosomal assignments. The results obtained indicate that the gene coding for the HL-A xenoantigenic determinant is carred on chromosome 6. The data obtained provides a direct demonstration that the gene coding for beta2m segregates independently of that coding for the alloantigenic polypeptide chain of the HL-A molecule, and that the gene coding for beta2m is carried on chromosome 15.

Animals↗
PubMed1976

Cell-mediated immunity to varicella-zoster virus demonstrated by viral inactivation with human leukocytes.

Cell-mediated immunity to varicella-zoster (V-Z) virus in persons immune to varicella has been demonstrated, using a tissue culture technique. Cell-mediated immunity was reflected by the ability of peripheral leukocytes (lymphocytes and monocytes) from human donors to inactivate V-Z virus. Leukocytes were stimulated by the addition of noninfectious V-Z antigen to cultures newly infected with V-Z virus. Several days leter, the V-Z virus in these cultures was titered. When leukocytes from donors immune to caricella were used, a significant decrease in V-Z titer, compared with controls, was noted. When leukocytes from donors susceptible to varicella were tested, no decrease in V-Z virus titer was found. A mixed population of lymphocytes and monocytes from immune donors was required to demonstrate inactivation of V-Z virus. The development of specific cell-mediated immunity to V-Z virus may play a role in termination of varicella and in prevention of second attacks of this disease.

Antigens, Viral↗
PubMed1976

Accidental laboratory infection with Treponema pallidum, Nichols strain.

This case report describes a laboratory-acquired infection with Treponema pallidum, Nichols strain. The specific details of the accidental exposure are presented, along with a description of the clinical observations. This infection indicates that the rabbit adapted Nichols strain of T pallidum retains its capability to infect humans. In addition, aerosols of concentrated preparations of these organisms, generated within the laboratory, represent a definite biohazard.

Aerosols↗
PubMed1976

Mineral and nitrogen metabolic studies on Skylab flights and comparison with effects of earth long-term recumbency.

A metabolic study of the effects of space flight on various chemical elements, particularly those with special relevance to the musculo-skeletal system, was carried out on the nine astronauts who participated in the three Skylab flights of 28, 59 and 84 days in 1973-1974. The study required of the cooperating crewmen constant dietary intake, continuous 24-hour urine collections and total fecal collections for 21-31 days before each flight, throughout each flight and for 17-18 days post-flight. Increases in urinary calcium and negative calcium balances during space flight were generally similar to those found in previous immobilization and bedrest studies. The persistence of these alterations in calcium metabolism throughout the flights suggested that calcium losses would continue in weightlessness for a very long time. Significant losses of nitrogen and phosphorus occurred, associated with observed reduction in muscle tissue. Both mineral and muscle losses occurred despite vigorous exercise regimens in flight. It was concluded that unless protective measures can be developed, capable musculo-skeletal function is likely to be impaired in space flights, ultimately to be conducted to Mars, of 11/2 to 3 years duration.

Bed Rest↗
PubMed1976

The coagulation and fibrinolytic response to splenectomy.

The responses of the coagulation and fibrinolytic systems in nine patients with Hodgkin's disease undergoing splenectomy and lymph node mapping have been compared with those in nine patients undergoing elective upper abdominal operation for benign conditions. Differences have been noted in base line levels of fibrinogen, prothrombin, partial thromboplastin time and euglobulin lysis time. Platelet count increases were exaggerated following splenectomy, but other parameters of coagulation activity behaved similarly in the two groups. There is no evidence from this study to support the suggestion that blood coagulability is increased more markedly following splenectomy than it is after other upper abdominal operations.

Abdomen↗
PubMed1976

Immune complex infusion in the rat. Renal functional and morphological changes.

Immune complexes were precipitated from pooled goat antisera to human Cohn Fraction II. After washing the complexes were solubilized in antigen excess. When complexes containing 10 mg of antibody were infused into saline-loaded rats an episode of oligoanuria lasting 4-6 hr resulted followed by transient proteinuria. By 24 hr after complex infusion protein excretion had returned to pre-infusion levels. With infusion of 5 mg of antibody similar functional alterations, though of lesser severity, occured. Control animals infused with Cohn fraction II alone in an amount and protein concentration equal to the experimental groups exhibited none of these features. Changes in blood pressure did not occur. Immune complex deposition was not detectable in the glomeruli by immunofluorescence microscopy. A mild microangiopathy affecting mainly interstitial vessels, with some glomerular endothelial cell swelling, was evident on light microscopy. It is suggested that circulating factors resulting from complex infusion rather than glomerular complex localization account for the changes observed.

Animals↗
PubMed1975

The influence of beta-adrenergic blockade upon baseline blood coagulation and fibrinolytic activity and upon the responses to venous occlusion.

Twenty volunteers were assessed for baseline coagulation (Thrombelastography, Factor VIII and platelet count) and fibrinolytic (Euglobulin Lysis Time and Fibrin(ogen) Degradation Products) activity two hours after ingestion of 60 mgm propranolol or an identical placebo administered on a double blind basis. The responses of these parameters to a fifteen minute period of venous occlusion was also assessed. Beta adrenergic blockade reduced baseline FDP titres but did not affect other parameters, nor the local response to venous occlusion. During occlusion no significant change in coagulation activity could be detected in the non-occluded arm, but a small but statistically significant shortening of ELT was observed. Since this effect was prevented by propranolol it is probably mediated through adrenergic mechanisms. Adrenergic stimuli appear to influence episodes of coagulation and fibrinolysis during everyday activity, but do not contribute to baseline levels of coagulation or fibrinolytic function.

Adult↗