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Biomedical subjects

K Simon

Publications and source records attributed to K Simon.

At least 127 records · Page 7Linked to original sources
PubMed1986

Dual regulation of PTH-stimulated adenylate cyclase activity by GTP.

Guanyl nucleotide regulation of parathyroid hormone (PTH)-activated adenylate cyclase was studied in membrane preparations of cultured opossum kidney cells. Guanosine triphosphate (GTP) (100 microM) decreased PTH-stimulated activity by 70%. Pertussis toxin enhanced PTH stimulation in intact cells and membranes, completely blocked the inhibitory effect of GTP, and catalyzed the [32P]ADP-ribosylation of a 38,000-dalton protein migrating in the position of the alpha-subunit of the inhibitory GTP-regulatory protein Ni. Cholera toxin was used to identify the alpha-subunit of the stimulatory GTP-binding protein Ns, a 42,000-dalton protein. We tested the idea that Ni may be involved in mediating the reduced response of opossum kidney cells to PTH after pretreatment with the hormone (desensitization). GTP inhibited PTH-stimulated activity to approximately the same degree in membranes from PTH-pretreated cells and control cells whether or not the cells had also received pertussis toxin. We conclude that GTP inhibits PTH action in opossum kidney cells through Ni but that PTH-induced desensitization is not mediated by Ni.

Adenylate Cyclase Toxin↗
PubMed1986

Mast cell degranulation after a single dose of gliadin in the jejunum of patients with coeliac disease.

The exact pathomechanism of jejunal damage caused by gliadin in coeliac disease has not been clarified. 0.3 g of gluten per kg bodyweight was administered to 14 children affected by coeliac disease, being on gluten-free diet, five hours before jejunal biopsy. There was no change in the number of intraepithelial lymphocytes and eosinophils while cellular infiltration of the lamina propria exhibited a marked increase and the number of mast-cells per tissue unit significantly decreased as compared with controls. It is concluded that mast-cells may play an important role in the mechanism of gluten induced jejunal damage.

Adolescent↗
PubMed1986

[Early operation of acute appendicitis--risk in unnecessary appendectomies].

The authors have analysed their own surgical patients, with the view to establishing the rate of unnecessary appendectomy. Any operation is accompanied by a certain risk, including appendectomy. Hence, unnecessary interventions should be avoided. Complications usually concomitant with appendicitis may occur, as well, in the wake of unnecessary appendectomy. Yet, they are much more common, when an operation had been delayed.

Acute Disease↗
PubMed1984

Carcinogenesis studies on guppies.

Guppies (Lebistes reticulatus) were used as models for the screening of potentially carcinogenic substances. These fish, a simple, readily accessible type, are sensitive toward carcinogens. Using this model, we performed studies on the morphological effects of a few water-soluble chemicals. Guppies treated with diethylnitrosamine were used as positive controls. Changes were noted in the livers, and a few specific lesions occurred in their gastrointestinal tracts. Studies were also conducted with 10 other similar chemicals found in the human environment that have potential use in chemotherapy. Of these, the carcinogenic effect of N,N'-dinitrosopiperazine on fish was demonstrated. Some researchers think this compound is a derivative of the pesticide Triforine. Furthermore, 2 of the 10 chemicals intended for use in therapy proved to be potential carcinogens. Because these experiments with water-soluble substances are inexpensive and the test periods are short, the use of fish is considered more advantageous than is the use of rodents.

Animals↗
PubMed1983

The effect of E-N-trimethyl lysine (TML) treatment on the regeneration of bone marrow and intestinal mucosa in mice.

E-N-Trimethyl-lysine (TML) prevents the anemia caused by 5 Gy whole body irradiation of mice when applied simultaneously with irradiation in a dose of 100 mg/kg i.p. The number of splenic colonies increases significantly after TML treatment of the irradiated recipients. TML increased the proliferative activity of Lieberkühn's crypts in mice, especially after lethal whole body irradiation. The possibility of clinical use of TML is discussed.

Animals↗
PubMed1983

Library-media production interface.

This article presents a detailed discussion of the roles of the health sciences library and the media production service personnel in providing a standardized system for accessing audiovisual and video in-house produced software. A worksheet and guidelines for collecting complete bibliographic information for these programs are also included.

Audiovisual Aids↗
PubMed1982

Renal tubular acidosis: its types and role in renal calculosis.

In the light of published observations attention is called to the various forms of renal tubular acidosis (RTA), its etiology, pathologic significance, excretion of an "alkaline-persistent" urine in the presence of hyperchloremic acidosis, and to the possible consequences: nephrocalcinosis and renal calculosis. The frequency of incomplete RTA of various causes in calculosis is pointed out. The patient material of the authors and the results of phosphate therapy are presented, stressing the importance of alkalizing therapy and its prophylactic value.

Acidosis, Renal Tubular↗