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Biomedical subjects

M Hoffman

Publications and source records attributed to M Hoffman.

At least 361 records · Page 20Linked to original sources
PubMed1980

Adaptation to hyperoxia in the neonatal rat: kinetic parameters of the oxygen-mediated induction of lung superoxide dismutases, catalase and glutathione peroxidase.

The activities of the enzymes superoxide dismutase, catalase and glutathione peroxidase increase in the lungs of neonatal rats exposed to normobaric hyperoxia. The oxygen-mediated increase in activity of these enzymes, known from previous studies to be an inductive response, was studied in 10- and 25-day-old rats as a function of both oxygen concentration and length of time of exposure to greater than 95% oxygen. In the lungs of 10-day-old rats the increase in superoxide dismutase, catalase, and glutathione peroxidase occurs only at 80% ambient oxygen or greater. In 25-day-old rats a similar pattern of response occurs with pulmonary catalase and glutathione peroxidase. However, unlike the response in 10-day-old rats, pulmonary superoxide dismutase does not increase in oxygen-exposed 25-day-old rats. The time course of enzyme induction was different for 10-day-old rats compared with 25-day-old rats. Exposure of 10-day-old rats to 95+% oxygen resulted in a significant increase in activity of superoxide dismutase after only 4 h when compared with air-exposed control animals. Catalasee and glutathione peroxidase in the same age group increased significantly after 6 h and 12 h of exposure to oxygen, respectively. Maximal levels of superoxide dismutase, catalase and glutathione peroxidase were reached after 6, 12 and 24 h of exposure to hyperoxia, respectively. This level of activity was then maintained throughout the subsequent exposure time up to 96 h. The activity of pulmonary catalase and glutathione peroxidase in 25-day-old rats did not increase significantly after 6 h of exposure to hyperoxia. An apparent plateau of increased activity was reached after 24 h of exposure. As observed with the 3 enzymes in 10-day-old rats, maximal enzyme activities were maintained throughout the subsequent period of oxygen exposure up to 96 h.

Adaptation, Physiological↗
PubMed1980

Regulatory mechanisms of cell-mediated immunity in allogeneic pregnancy.

The transfer of cells from allopregnant animals to syngeneic receivers allografted with paternal strain tumor leads to mild but significant enhancement. The effect can be defined as T cell mediated. Cells from allopregnant animals can suppress a mixed lymphocyte reaction (MLR) of maternal responders against paternal stimulators. The effect relies upon a THY 1+, Ly 2+, Ia+ cell. Cell-mediated lympholysis (CML) assay could also be suppressed by cells from allopregnant animals. Placental products are capable of interfering with allograft rejection in vivo. They can block MLR in vitro, and seem to act in part via the induction of suppressor cells. The respective roles of these depressive components, together with enhancing antibodies, is discussed.

Animals↗
PubMed1979

Long-term effect of ovariectomy on dopamine-stimulated adenylate cyclase in rat striatum and nucleus accumbens.

The long-term effects on dopamine-sensitive adenylate cyclase of deprivation of gonadal steroids resulting from ovariectomy were studied in extrahypothalamic areas of the brain, i.e. corpus striatum and nucleus accumbens. The results obtained show that in both central nervous system areas dopamine- and apomorphine-stimulated adenylate cyclase were significantly reduced, suggesting that the function of dopamine receptors in these areas was depressed.

Adenylyl Cyclases↗
PubMed1979

Incidence of bronchoconstriction due to aspirin, azo dyes, non-azo dyes, and preservatives in a population of perennial asthmatics.

Forty-five patients with moderately severe perennial bronchial asthma were challenged by ingestion of: acetylsalicyclic acid (ASA); 4 azo dyes (tartrazine, sunset yellow, amaranth, and ponceau); 3 non-azo dyes (erythrosine, brilliant blue, and indigotin); sodium benzoate (NaB); parahydroxybenzoic acid (OHBA); butylated hydroxyanisole (BHA); and butylated hydroxytoluene (BHT). A fall in forced expiratory volume is one second (FEV1) greater than 25% from baseline was considered positive. Seven patients who gave an unequivocal history of aspirin intolerance were not challenged with ASA; an additional 13 had positive open challenges to ASA, giving an apparent incidence of aspirin sensitivity of 20/45. The presence of nasal polyps, simusitis, or the regular use of corticosteroids, either singly or in combination, was not associated with an increased incidence of reactions to ASA. Significant bronchoconstriction to open challenges with agents other than ASA was less frequent. Positive open challenges to all substances except aspirin were followed by double-blind challenges which were positive in only 3 instances: 1 each with erythrosine, ponceau, and NaB/OHBA. Our findings confirm that ASA intolerance is relatively common but suggest on the other hand that reactions to dyes and preservatives are uncommon cause of clinically significant bronchoconstriction in moderately severe perennial asthmatics.

Adolescent↗
PubMed1979

Arteriovenous fistula and portal hypertension secondary to islet-cell tumor of the pancreas.

A case of portal hypertension secondary to an arteriovenous fistula in a pancreatic tumor is presented. Recurrent gastrointestinal hemorrhage prompted endoscopy which revealed esophageal varices and an abnormal papilla of Vater. Ultrasonography and arteriography were instrumental in demonstrating the nature of the pathological process. In this situation portal hypertension resulted from increased portal venous flow rather than portal obstruction. Correction must include obliteration of systemic arterial to portal venous communication.

Adenoma, Islet Cell↗