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Biomedical subjects

J Hirsch

Publications and source records attributed to J Hirsch.

At least 253 records · Page 14Linked to original sources
PubMed1981

Effects of altered adipose tissue morphology on plasma insulin levels in the rat.

The usual covariates of adiposity--adipocyte size, total body fat, and food intake--were experimentally dissociated using three new models of altered adipose tissue morphology in the rat. It was thereby possible to test the hypothesis that plasma immunoreactive insulin level (IRI) is a function of mean adipocyte size. In two of the models, experimental and control rats differ substantially in total body fat but show no difference in mean adipocyte size. In these models, no difference in plasma IRI was found between experimental and control animals. In a third model, experimental and control rats differ in mean adipocyte size but not in total body fat or daily food intake. In this model, plasma IRI was found to differ between experimental and control rats. These observations demonstrate a close link between adipocyte size and plasma IRI and suggest that the hyperinsulinemia and peripheral insulin resistance of obesity are more likely due to adipocyte hypertrophy than to increases in total body fat or daily food intake.

Adipose Tissue↗
PubMed1981

Single motor unit activity in the diaphragm of cat during pressure breathing.

In this study we analyzed the breath-by-breath activity of single motor units in the diaphragm slip of allobarbital-anesthetized cats during quiet breathing and during continuous positive- and negative-pressure breathing. Our objective was to determine whether single motor units, on the basis of their activities, can be separated into discrete subpopulations or whether they fall on a continuum analogous to that of motor units of hindlimb muscles. The firing profiles of each unit were characterized for each pressure level by the onset and peak firing frequencies, onset latency, duration of firing, number of impulses per breath, and minimal frequency, when appropriate. Units with shorter onset latencies had higher peak frequencies, longer firing durations, and increased firing frequencies than did units with longer onset latencies. These comparative relationships persisted even though the activity of every motor unit was altered during pressure breathing. During positive-pressure breathing onset latencies were lengthened, and durations of firing were shortened with little change in onset or peak frequencies. Late units might be silenced. During negative-pressure breathing onset latencies were shortened, and durations of firing were lengthened, sufficiently in some cases to fill the expiratory pause. In addition, previously inactive units were recruited late in inspiration for short, relatively high frequency bursts during inspiration. The results support the concept that the phrenic motoneuron pool is comprised of three discrete subpopulations.

Airway Resistance↗
PubMed1981

Enhanced platelet accumulation onto injured carotid arteries in rabbits after aspirin treatment.

Prostacyclin (PGI2) is a powerful inhibitor of platelet aggregation, but its role in the pathogenesis of arterial thrombosis is uncertain. We have studied the thrombogenic effect of inhibiting PGI2 production by aspirin (ASA) in carotid arteries of rabbits given 0, 3, 10, or 100 mg ASA/kg either 1, 3, 6, or 20 h beforehand. Platelet accumulation onto injured carotid arteries was enhanced with ASA in a dose of 10 mg/kg. A higher dose of ASA (100 mg/kg) had no further effect. The enhanced thrombogenic effect of ASA persisted for at least 20 h and was associated with a decrease in vessel wall PGI2 production. There was a strong inverse correlation (r = 0.55, P less than 0.01) between PGI2 production and platelet accumulation. The findings suggest that the margin of safety in obtaining an antithrombotic effect of ASA and producing a potential thrombotic effect in arteries may not be as large as predicted by studies using cultured endothelial cells or experimentally induced thrombosis in veins.

Animals↗
PubMed1980

[Demonstration of Epstein-Barr virus genome in european Burkitt lymphoma (author's transl)].

A 6-year-old European boy with a tumour in the head and neck region died 86 days after the first occurrence of symptoms despite chemo- and radiotherapy. An epipharyngeal biopsy at the beginning of the disease and a cytological investigation of biopsy and autopsy material showed non-Hodgkin lymphoma with a high degree of malignancy of the Burkitt type. High antibody titres against Epstein-Barr virus (EBV)-specific virus capsid antigen, nuclear antigen and the R component of the EBV-early-antigen-complex as well as the approximately 27 EBV genome equivalents per tumour cell, demonstrated by DNA-DNA hybridisation, characterised the tumour as true Burkitt lymphoma which is observed extremely seldom outside Africa.

Antigens, Viral↗
PubMed1980

Effect of glycerol on weight loss and hunger in obese patients.

The effectiveness of oral glycerol as a dietary component or as a supplement to a 1000-kcal/day diet was examined in two studies involving obese patients. Glycerol did not differ from an equicaloric dose of glucose in its effect on hunger ratings, diet compliance or overall weight loss. We conclude that oral glycerol is not a useful adjunct to weight reduction programs.

Adult↗
PubMed1980

Systemic distribution of N2 paste containing 14C paraformaldehyde following root canal therapy in dogs.

Using rubber-dam isolation and an aseptic and standardized endodontic technique, root canal therapy was performed on the right and left fourth mandibular premolars in four dogs. Each tooth was obturated with N2 paste containing 6.5 percent 14C paraformaldehyde. In each dog at 1 hour, 1, 7, 14, and 28 days, blood was drawn and biopsy specimens were taken of the adjacent lymph nodes, liver, and kidney. At 28 days, the animals were killed, and the experimental and adjacent tissues were processes for light microscopy. Histologic examination demonstrated that particles of the paste placed in the root canal were present in pulp, periapical, and periodontal tissues remote from the original site in the root canal. In addition, 14C-labeled paraformaldehyde which was contained in the N2 paste was found in blood, regional lymph nodes, kidney, and liver. The amount of radioactivity in all the body organs decreased with time.

Animals↗
PubMed1980

Long-term effects of early nutritional experience on the development of obesity in the rat.

Adjustment of litter size was used to provide two levels of early nutrition to rat pups and thereby to produce adult rats of markedly different body weights. Effects of the two levels of early nutrition on adipose tissue were compared after the rats had been fed ad libitum for nearly 1 year. Mean fat cell size did not differ between rats raised in large and small litters regardless of whether they had been maintained continuously on a stock diet (upon which rats usually have normal size fat cells) or had been switched to a high-fat diet (upon which rats usually have greatly enlarged fat cells). However, rats raised in large litters had less body fat and fewer fat cells than rats reared in small litters, both in absolute terms and relative to body weight. Litter size also affected the absolute, but not relative, increase in body fat and fat cell number induced by high fat feeding. Early nutrition thus has a sustained effect on fat mass and fat cell number, but not on fat cell size, which is apparent even when adipose tissue has been induced to major alteration by the feeding of a high fat diet.

Adipose Tissue↗
PubMed1980

Comparison of two direct assays for platelet-associated IgG (PAIgG) in assessement of immune and nonimmune thrombocytopenia.

A number of methods have been developed to measure platelet-associated IgG (PAIgG). The antiglobulin consumption assay directly quantitates IgG on the platelet and is sensitive and specific. A fluorescent anti-IgG assay has recently been described and has the advantage of simplicity. We compared the results of these two PAIgG assays in immune and nonimmune thrombocytopenia and nonthrombocytopenic controls. The antiglobulin consumption assay was negative in 61 of 62 and the fluorescent negative in 54 of 62 assays in nonthrombocytopenic controls, and they were negative in 11 of 13 and 8 of 13 assays, respectively, in nonimmune thrombocytopenic patients. The antiglobulin consumption assay was positive in 54 of 58 and the fluorescent positive in 24 of 58 assays of patients with immune thrombocytopenia (ITP and SLE). The overall sensitivity and specificity of the antiglobulin consumption assay was 94% and 95% and of the fluorescent assay was 44% and 82%.

Blood Platelets↗
PubMed1979

Effect of guanidine on release of noradrenaline from the perfused spleen of the cat.

1 Guanidine increased noradrenaline (NA) output at 5 Hz by 3 to 6 fold, and doubled it at 30 Hz. Onset of maximum activity was slow, and reversal was also slow. Output of NA induced by potassium, sodium deprivation, or tyramine was not affected. 2 NA output was doubled at low concentrations (1 to 2 mM) of guanidine, but maximal effect was obtained at 4 mM. At 10 mM, spontaneous release was occasionally observed. 3 The effect of guanidine on NA release was related to the external calcium concentration. Outputs which previously have been shown to be insignificant at 5 Hz in 0.25 and 0.75 mM calcium-Krebs solution were markedly enhanced by guanidine. Guanidine enhanced release at all calcium concentrations up to 7.5 mM, but maximum output was obtained at 2.5 mM. 4 Guanidine had no effect on the recovery of intra-arterially infused NA. 5 The effects of guanidine and tetraethyl-ammonium (TEA) on NA release at 5 Hz were additive. 6 Guanidine reversed the inhibition of NA release by guanethidine during nerve stimulation at 5 and 10 Hz, and the NA output increased nearly 2.5 fold after repeated stimulation of the nerves. Guanidine was less effective in reversing the inhibitory effects of guanethidine on NA release at 30 Hz. 7 Guanidine did not affect release of catecholamines (CA) from the perfused cat adrenal gland by splanchnic nerve stimulation. 8 It is suggested that guanidine enhances NA release partly by increasing the influx of calcium into the neurone during an action potential, and also by interfering with intracellular binding of calcium.

Adrenal Medulla↗