Search PubMed⌕ Search

Biomedical subjects

J Roth

Publications and source records attributed to J Roth.

At least 793 records · Page 44Linked to original sources
PubMed1975

On the selectivity of aryl hydrocarbon hydroxylase induction after 3-methylcholanthrene pretreatment.

The development of aryl hydrocarbon (benzo(a)pyren)hydroxylase (AHH), succinate dehydrogenase and glucose-b-phosphatase activities in the liver and the kidney and of liver weight and glycogen were investigated in 7-day-old rats treated i.p. with 1, 10, and 100 mg 3-methylcholanthrene (MC)/kg body weight. 3-MC highly specifically influenced the AHH activity, which was increased dose dependent. The higher the dose, the higher and the longer was the induction effect. The other biochemical parameters investigated were not influenced. At the maximum of the induction effect after pretreatment with the highest dose of 3MC no morphological alterations in the liver could be observed by light and electron microscopy. Therefore the 3-MC mediated AHH induction seems to be a suitable model for the examination of dose dependent inducer-inhibitor interactions in the intact animal.

Animals↗
PubMed1975

The use of flurorescein investigations with concanavalin A, Lens culinaris lectin and Ricinus communis lectin.

Investigations on methods for the utilization of fluorescein-isothiocyanate-labelled Concanavalin A, Lens culinaris lectin and Ricinus communis lectin for immunohistological demonstration as simple sugar moieties are reported. The stainings were carried out on rabbit erythrocytes. Ehrlich ascitee tumor cells and various mammalian tissues. Optimum results were obtained in living cells and native cryostate tissue sections. The influence of different fixing agents and conditions of fixation on the degree of tissue flurorescence were studied. Generally the fluorescense decreased by aldehyde fixation. Similar effect was observed following fixation by heat. Furthermore, changes in the pattern of fluorescence depending on the type of tissue and utilized lectin were observed after aldehyde fixation. The degree of tissue fluorescence was fairly independent of the pH value. The specificity of the particular reactions for saccharide demonstration was shown; glycerol is capable of a differently strong "hapten-like" action.

Animals↗
PubMed1975

[Dosage measurement of fast electrons using modified Fricke's solution].

A combination of two different modifications indicated in the literature about the ferrosulfate dosimetry has been given. This permits a dose measurement which shows compared to the usual dosimetry of Fricke above all following advantages: dose specification related to water; displacement of the absorption maximum in the perceptible spectral sphere; increase of the sensibility and lower influence of pollutions. The molar coefficient of extinction of the modified solution has been determined from Co-60-gamma irradiation and is epsilonm = 1,46 - 10(4) L - Mol(-1) - cm(-1). The increase of extinction which has been measured with this method after the irradiation with 18 MeV electrons occurs linearly within the studied region to 1200 rd at least, the G-value is 15,5. The indicated method renders possible a relative simple calibration of the ionisation chambers which have been used in the practice.

Cobalt Radioisotopes↗
PubMed1974

Distribution of concanavalin a receptors on normal rat liver cells and zajdela ascites hepatoma cells.

The distribution of Concanavalin A receptors in cultures of normal rat liver cells and of Zajdela ascites hepatoma cells of the rat was investigated by the Con A-po technique (Bernhard and Avrameas, 1971). Con A-po labelling of the cell surface showed a patchy distribution of Concanavalin A receptors in ascites hepatoma cells, whereas continuous Con A-po labelling was seen at the surface of normal rat liver cells. The different distribution of Concanavalin A receptors was caused by rapid internalization of Con A-po labelled material and not by a simple rearrangement of the receptors. The significance of this process is discussed with respect to Concanavalin A receptor mobility and membrane stability after cell transformation.

Animals↗
PubMed1974

Insulin-dependent regulation of insulin receptor concentrations: a direct demonstration in cell culture.

Chronic (5-16 hr) exposure of cultured human lymphocytes to 10(-8) M insulin at 37 degrees in vitro produced a decrease in insulin receptor concentrations unaccounted for by simple occupancy of sites; acute exposure (0-2 hr) was without effect. These results reproduced observations in vivo where chronic hyperinsulinemia (e.g., 10(-8) M insulin in the circulation of obese insulinresistant hyperglycemic mice) is associated with a substantial reduction in the concentration of insulin receptors per cell, while acute hyperinsulinemia in vivo has no effect on receptor concentration. These data suggest a reciprocal relationship between insulin in the extracellular fluid and the concentration of insulin receptors per cell, which is mediated at the target cell itself by intracellular insulin-sensitive regulatory processes and directly affects target-cell sensitivity to hormone.

Binding Sites↗
PubMed1974

Specialized transducing phages derived from salmonella phage P22.

Salmonella phage P22 has been used in the construction of three sorts of specialized transducing phage: P22 proAB, P22 proABlac and P22 argF. The bacterial genes carried are derived from E. coli K12. Since E. coli and Salmonella chromosomes recombine very poorly, E. coli genes cannot be transduced into Salmonella recipients by P22's generalized transduction mechanism. Therefore, stable inheritance of E. coli material provides a means of detecting specialized transduction. Formation of these phages was possible because the P22 prophage recognizes an attachment site in the E. coli F' prolac episome. Salmonella strains carrying the F' prolac episome can be lysogenized by P22 so as to leave the prophage inserted into the E. coli material of the F' factor. Improper prophage excision can then lead to formation of P22 specialized phages carrying E. coli genetic material.

Alleles↗