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Biomedical subjects

J Roth

Publications and source records attributed to J Roth.

At least 721 records · Page 40Linked to original sources
PubMed1977

[Are repeated controls of the forced expiratory volume (FEV1) necessary in examinations of bronchial reactivity? (author's transl)].

In 432 patients examinations of bronchial reactivity with the acetylcholin test (3 min. inhalation of a 0.1% acetylcholine solution) were carried out with testing FEV1 immediately, 5 min. and 10 min. after stopping inhalation. It could be shown that the extent of bronchial hyperreactivity can be found by a single determination after acetylcholine provocation. It is proposed to use this one-step method for routine examinations and to measure FEV1 five min. after stopping inhalation. For clinical evaluation the intensity of bronchial reaction has also to be considered and estimated.

Acetylcholine↗
PubMed1977

[Reproducibility and accuracy of an optical ssd pointer (author's transl)].

The reproducibility and accuracy of an optical source-surface distance measuring device was systematically examined. The standard deviation of twenty equal distance settings was +/-0,5%. The error in dose-rate caused by one single adjustment did not exceed +/-2%. The position of the effective source-center is defined by a special inverse square plot. A periodical check is recommended.

Mathematics↗
PubMed1977

[Long-term control of reproducibility of automatic developers (author's transl)].

Variability of blackening of X ray films may be due to inconstant concentration or temperature of the developer. Reproducibility was examined with stepwise blackening, exposed under standard conditions and densitometrically evaluated after development. The resulting differences of blackening are without significance for the subjective assessment of X ray films, since they lie within +/- 10%.

Film Dosimetry↗
PubMed1976

Insulin-induced dissociation of its receptor into subunits: possible molecular concomitant of negative cooperativity.

The detergent-solubilized avian insulin receptor retains negative cooperativity and other binding properties of the membrane bound form. On gel filtration the receptor elutes as a single peak with a Stokes radius of 72 A. Preincubation of the receptor with low levels of insulin leads to the formation of a second, smaller form with a Stokes radius of 40 A. The percent of receptor in this second peak is proportional to the insulin concentration and correlates well with the insulin-induced increase in dissociation rate (negative cooperativity). Both the isolated high molecular weight and the isolated low-molecular-weight forms of the receptor re-equilibrate in the presence of insulin and, upon refiltration of either isolated peak, both forms of the receptor are obtained. These results are compatible with a model of the insulin receptor in which a tetrameric form can dissociate to a monomeric form as a concomitant of negative cooperativity.

Allosteric Regulation↗
PubMed1976

[Comparability of jet and ultrasonic aerosols in bronchial reactivity tests].

The use of tests of bronchial reactivity for expert's opinions as well as ability examinations and check-ups in the field of occupational medicine makes great demands on their reproducibility. In the case of different application techniques the comparability of the test results is to be proved. For two aerosol producers used in the GDR test variants reliable for many years were comparatively investigated. Hereby the possibility could be proved on principle to achieve comparable results by variation of the concentration of the acetylcholine solution given. The choice of the test concentration in question is decisively influenced by the aim of the examination and the kind of test persons.

Acetylcholine↗
PubMed1976

Cell surface receptors for insulin and human growth hormone. Effect of microtubule and microfilament modifiers.

The receptors for the polypeptide hormones, insulin and growth hormone, are located on the cell surface. Since the cytoplasmic microtubules and microfilaments are involved in the mobility and distribution of surface receptors for immunoglobulins and lectins, we investigated the role of these structures in the binding of insulin and human growth hormone to their receptors on cultured human lymphocytes (IM-9). Cells preincubated with microfilament modifiers, cytochalasin A, B, and D (10 mug/ml), had decreased binding of insulin (30%) and human growth hormone (60%) under steady state conditions, which was not reversed by removing the cytochalasins from the medium and was due entirely to a reduced number of receptor sites on the cell surfact. The lost receptors were not detected in the medium, suggesting a redistribution within the cell. The cytochalasins failed to alter the affinity of the hormones for their receptors or the negative cooperativity of the insulin receptor. The anti-microtubule agents (vincristine, vinblastine, colchicine) had no effect on the binding of insulin and growth hormone to their receptors. Deuterium oxide, a stabilizer of microtubules and other proteins, decreased the affinity (40%) of insulin for its receptors under steady state conditions and accelerated moderately the spontaneous dissociation of 125I-insulin from its receptors. Since cytochalasin decreases the number of available insulin and human growth hormone receptor sites, cytochalasin-sensitive microfilamentous structures appear to modulate the exposure of cell surface hormone receptors, while microtubules do not seem to be involved.

Binding, Competitive↗
PubMed1976

[The reproducibility of the acetylcholine test and the effect of the respiratory flow rate].

The reproducibility of the acetylcholine-test results was controled by means of comparative investigations on 50 patients. The method of investigation render it possible with a high reliability to exclude a bronchial hyperreactivity. However, a single positive diagnose needs an additional control examination with reference to the interpretation of evidence. The different test results are caused by the biological variability of the bronchial hyperreactivity; on the other hand, an influence of variability of the minute output of breathing could be excluded.

Acetylcholine↗
PubMed1976

Purification and characterization of two lectins from Caragana arborescens seeds.

A glycoprotein fraction with hemagglutinating activity was purified by affinity chromatography from seeds of the pea tree, Caragana arborescens. Subsequent fractionation resolved two components, which could be separated on a preparative scale using different affinity matrices. The major component binds to N-acetylgalactosamine coupled to Sepharose 4B. It is a glycoprotein with high hemagglutinating activity. It is composed of two types of polypeptides, present in nonstoichiometric amounts, with apparent molecular weights near 30,000. In the native molecule, the subunits are cross-linked by disulfide bonds to form dimers, which in turn appear to be in rapid equilibrium with tetramers. The minor component binds to underivatized Sepharose 4B. It too, is a glycoprotein but has low hemagglutinating activity. It is composed of three types of polypeptides which, although they have apparent molecular weights near 30,000 are distinguished from the subunits of the major hemagglutinin by a number of physical and chemical properties. The native molecule is dimeric, with a mass of 60,000 daltons. The major component has high affinity (K = 0.1 mM) for the haptenic sugar, N-acetylgalactosamine, but will also bind D-galactose. Neither lectin has ABO blood group specificity, nor are they transformed mouse fibroblasts to the same extent.

Acetylgalactosamine↗
PubMed1976

Histochemical lectin affinity technique by means of FITC-labeled serum protein fractions.

A two-step affinity technique is described for light microscopic demonstration of the Concanavalin A, Agaricus bisporus lectin and Ricinus communis lectin binding sites by means of various FITC-labeled human and rabbit serum protein fractions. Experiments for the visualization of the Lens culinaris lectin and the Pisum sativum lectin binding sites gaves negative results. The technique consist of two reaction steps which involve the incubation of tissue sections in the lectins followed by the visualization of receptor-bound lectins with FITC-labeled serum protein fractions basing on their carbohydrate content. The specificity of the technique could be demonstrated by the addition of the hapten or by incubation in the FITC-labeled serum protein fractions only. In contrast to the direct or indirect staining methods only very small amounts of purified lectins are necessary.

Animals↗
PubMed1976

The insulin receptor of the turkey erythrocyte. Characterization of the membrane-bound receptor.

The insulin receptor of the turkey erythrocyte has previously been shown to be very similar to that of the mammalian insulin receptors. As a first step in the isolation of this receptor a highly purified plasma membrane fraction has been prepared. The binding characteristics of the purified membrane-bound receptor were identical to those found with intact erythrocytes, but the membrane preparation had very little insulin-degrading activity. Isolation of the membrane by the methods described gave a 100-fold purification of the insulin receptor with 67% yield.

Animals↗
PubMed1976

Regulation of receptor concentration by homologous hormone. Effect of human growth hormone on its receptor in IM-9 lymphocytes.

When cultured human lymphocytes of the IM-9 line were exposed to human growth hormone (hGH) at 37 degrees, washed for 2 hours, and incubated with 125I-hGH, the binding of 125I-hGH was reduced. The magnitude of the reduction in binding was dependent on the concentration of growth hormone present as well as the duration of the exposure. As little as 2 X 10(-11) M (0.5 ng/ml) growth hormone had a discernible effect. Growth hormone at 2 X 10(-10) M (5.0 ng/ml), which is a low resting concentration of hormone in vivo and occupies about 20% of the receptors at steady state at 30 degrees, produced a 50% reduction in binding while 20 mg/ml, which occupies about 50% of the receptors under steady state conditions, produced an 80% loss of receptors. Further increases in growth hormone concentration produced little further effect on receptor loss. Thus, the loss of receptors at a given concentration of growth hormone (up to 20 ng/ml) in the preincubation at 37 degrees was greater than the occupancy produced by that concentration of growth hormone receptors under steady state conditions at 30 degrees. Analysis of the data indicated that the decrease in binding of 125I-hGH was due to a loss of receptors per cell without any change in affinity of receptor for hormone or in cell number. The concentration of insulin receptors on these cells was affected by the insulin concentration in the medium, and the concentration of growth hormone receptors was affected by growth hormone, but neither hormone had any effect on the heterologous receptors. Exposure of the cells to cycloheximide (0.1 mM) produced a progressive but smaller loss of growth hormone receptors, and the effect of cycloheximide was additive to the receptor loss induced by growth hormone, suggesting that cycloheximide inhibited synthesis of receptors while growth hormone accelerated loss of receptors. When growth hormone was removed from the medium, receptor concentrations were restored rapidly; half of the loss was restored by 6 to 8 hours and the full complement of receptors was restored by 24 hours following removal of the hormone. If the growth hormone was removed and replaced with cycloheximide, the return of the receptors was delayed until the cycloheximide was removed. Thus restoration of the receptors appeared to require the synthesis of new proteins. These data indicate that in the IM-9 lymphocytes the concentration of growth hormone receptors is very sensitive to regulation by growth hormone and also add further support to the suggestion that hormones in general actively regulate the concentration of their own receptors.

Animals↗
PubMed1976

Binding and degradation of insulin by human peripheral granulocytes. Demonstration of specific receptors with high affinity.

The interaction of insulin with human circulating granulocytes was studied with the use of 125I-insulin. Human granulocytes, isolated from blood by the Böyum technique, showed high insulin-degrading activity in vitro which almost obscured the presence of specific, high affinity binding sites. Degradation, measured by trichloroacetic acid precipitation and by binding to well characterized insulin receptors on cultured human lymphocytes (IM-9 line), was due to extracellular as well as cell-bound enzymes. Degradation was enhanced by Ca2+ and thiols and inhibited by various protease inhibitors and sulfhydryl-blocking reagents. Phenylmethylsulfonyl fluoride (5 X 10(-4) M), a serine protease inhibitor, was the most potent and inhibited 125I-insulin degradation by 80 to 90%. Tert-butyl hydroperoxide (2 X 10(-3) M), a glutathione-oxidizing reagent, inhibited degradation by 35 to 50%, possibly due to an effect on a glutathione-insulin transhydrogenase. Neither of the inhibitors affected cell viability. In the presence of inhibitors of degradation, binding sites for insulin with high affinity were detected, which by multiple criteria were true insulin receptors. Binding to these sites was rapid, saturable, and reversible with about 1000 sites/cell. The Hill coefficient for binding was 0.7, and the Scatchard plot of B/F versus B was curvilinear, due to site-site interactions of the negative cooperative type; the latter were demonstrated directly by kinetic studies. As shown previously for all other insulin receptors, binding was highly pH-dependent, and insulin analogues had affinities for these sites that closely correlated with their biological potencies.

Binding Sites↗