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Biomedical subjects

J Roth

Publications and source records attributed to J Roth.

At least 649 records · Page 36Linked to original sources

[Influence of 2-ethyl-3-(4-hydroxybenzoyl)-benzofuran (benzarone) on experimental atheromatosis (author's transl)].

Local transmural electrical stimulation by chronically implanted electrodes of a carotid artery in rabbits was daily repeated. The area in direct contact to the electrodes covered 0.5 x 5 mm of adventitia. The carotid walls received DC impulses (10 ms/imp, 10 Hz, 100 microA) 2 x 1/2 h daily. Within 4 weeks a proliferate of smooth muscle cells develops in the intima at the spot where the anode contacts the outside of the artery. If the animals were fed 2% cholesterol in normal food the proliferate developed to a typical atheroma. The other parts of the arterial system did not develop plaques within this time. At the luminal side of the plaques no significant adhesions of platelets could be seen. Addition of 300 mg 2-ethyl-3-[-4-hydroxybenzoyl]-benzofuran (benzarone, Fragivix) to 100 g of animal food (containing 2% cholesterol) caused a less pronounced increase of serum cholesterol than in the controls which received cholesterol-containing food without benzarone. The development of plaques could not be prevented by benzarone, however, the growth of the atheromatous plaque was inhibited and the incorporation of lipids into the plaques was less pronounced than in those animals which received a diet with cholesterol but without benzarone. In those animals which received benzarone more lipid-laden foam cells were seen moving through the endothelium out of the plaque into the lumen of the stimulated artery. These foam cells were of mononuclear origin.

Animals↗

[Application of the ultrasonic aerosol apparatus "TuR" USI50 for the test of the bronchial reactivity--comparative studies with "TuR" USI3 (author's transl)].

By comparative studies with the ultrasonic aerosol apparatus "TuR" USI3 and "TuR" USI50 was shown that their applicability for tests of the bronchial reactivity leads to corresponding test results. Based on long experiences with the ultrasonic aerosol method the USI50 apparatus may recommended also for use of the acetylcholine test (0.01% solution) in clinics and ambulances. Detailed references are given for use of the application technique to guarantee that uniform conditions of investigation are present.

Acetylcholine↗

Increased insulin binding to erythrocytes in anorexia nervosa: restoration to normal with refeeding.

We studied [125I] insulin binding to circulating cells in patients with anorexia nervosa (eight females), in the basal cachectic state (seven patients) and after weight gain (eight patients) and compared the values to those obtained in 17 normal volunteers (eight females and nine males). Untreated patients showed increased insulin binding to receptors on erythrocytes (mean +/- S.E.M., 12.2 +/- 0.99 per cent of total); after weight gain, these increased levels returned to normal (6.8 +/- 0.42 vs 6.7 +/- 0.63 per cent of total). Increased binding was due to an increased number of receptors per cell, with little or no change in receptor affinity. In five patients (one untreated, four treated), results of [125I] insulin binding to erythrocytes correlated closely (r = 0.982) with results obtained with monocytes. We conclude that in patients with anorexia nervosa, insulin binding to receptors is altered and that the abnormality is corrected by restoration of normal food intake and body weight.

Adolescent↗

Electrolyte effects on the activity of mutant enzymes in vivo and in vitro.

All temperature-sensitive histidine auxotrophs of Salmonella typhimurium tested are corrected by addition of neutral salts to their growth medium. The correctability seems to result from direct electrolyte effects on mutant protein stability since several of the mutant proteins are also salt correctable in vitro.

Alcohol Oxidoreductases↗

Radioimmunoassay of the insulin receptor: a new probe of receptor structure and function.

A sensitive and specific radioimmunoassay for the insulin receptor has been developed employing receptor autoantibodies from the serum of a patient with insulin-resistant diabetes. The assay detects insulin binding sites at concentrations as low as 0.1 nanomolar; distinguishes between receptors originating from human placental membranes, human lymphoblastoid cells, and mouse liver membranes; and measures the receptor independently of its binding function. Down-regulation, or loss of binding after exposure to insulin, is associated with loss of immunoreactive receptor.

Animals↗

Inhibition of insulin receptor binding by dimethyl sulfoxide.

Little is known of the effects of the solvent on hormone-receptor interactions. In the present study the effect of the polar solvent dimethyl sulfoxide on the binding of insulin to its surface receptors on cultured human lymphocytes of the IM-9 line was investigated. At concentrations exceeding 0.1% (v/v), dimethyl sulfoxide produced a dose-related inhibition of 125-I-labeled insulin binding. Insulin binding was totally abolished in 20% dimethyl sulfoxide. This inhibition was immediately present and was totally reversible. Analysis of the data of binding at steady state indicated that the decrease in binding of 125I-labeled insulin was due to a reduced affinity of the insulin receptor without noticeable change in the concentration of receptor sites. Kinetic studies showed that the decreased affinity could largely be accounted for by a decreased association rate constant; effects on dissociation and negative cooperativity of the insulin receptor was affected to a much lesser extent.

Depression, Chemical↗

A contribution to the formation mechanism of calcium oxalate urinary calculi. IV. Experimental investigations of the intrarenal crystallisation of calcium oxalate in rabbit.

Rabbits were given glyoxylic acid to induce intrarenal calcium oxalate crystal formation. The point of crystallisation in the renal tubule, the structure and the composition of the intrarenal crystals were studied. The initial crystallisation takes place in the proximal tubule. Calcium phosphate formation was excluded by microprobe examination. The comparison of the structures of the intrarenally formed crystals with those of Whewellite stones by scanning electron microscopy and the examination of isolated crystals by x-ray diffraction showed the intratubular crystals to consist of Whewellite.

Animals↗

Inhomogeneity of surface labelling of B-cells at prospective sites of exocytosis.

Using ferritin-labelled Ricinus communis agglutinin to detect lectin-binding sites of the pancreatic B-cell surface, we show that limited regions of the plasma membrane are deprived of lectin-binding sites over marginated secretory granules. Such deprived regions increased during glucose stimulation of B-cells in monolayer culture: 56 +/- 8 of them were found in high (300 mg/100 ml) glucose as compared to only 27 +/- 5 in low (50 mg/100 ml) glucose (p less than 0.005). In addition, non-membrane, intracytoplasmic bridges were detected between the plasma membrane and the membrane of the marginated granule suggesting the involvement of cell web components in promoting the change in surface labelling.

Animals↗

Concentrations of insulin and insulin receptors in the brain are independent of peripheral insulin levels. Studies of obese and streptozotocin-treated rodents.

In view of the potent influences of the central nervous system on glucose metabolism and on its hormonal regulators, and our recent finding of insulin and insulin receptors throughout the central nervous systsem, we have examined extreme conditions of hyperinsulinemia (obese mice) and hypoinsulinemia (streptozotocin-treated rats) with respect to changes in brain insulin and receptor content. Sprague-Dawley rats given streptozotocin (100 mg/kg body wt) developed severe diabetes and by 48 h showed no change in brain insulin. Rats given 65 mg/kg streptozotocin also had severe diabetes, but survived longer. Both at 7 d and at 30 d after streptozotocin treatment there was no significant change in brain insulin or in brain content of insulin receptors, despite the fact that peripheral hepatic receptors were elevated and pancreatic insulin was markedly depleted. The obese mice were studied at 8-10 wk when peripheral plasma insulin concentrations were 50-fold elevated and receptors on peripheral target cells were reduced to congruent with40-50% of normal; brain insulin concentrations and receptor content were indistinguishable from those of thin littermates. Thus, brain insulin, which is typically 10 times higher than plasma insulin concentrations, and brain receptor content, which is equivalent to receptor content on peripheral tissues, appears to be regulated entirely independently of hormone and receptor in the periphery. These findings are consistent with the hypothesis that insulin in the central nervous system is synthesized by the neural elements, and plays a role in the central nervous system which is unrelated to peripheral glucose metabolism.

Animals↗