Phenobarbital: a locus of action on spike broadening and potassium inactivation

1. The effect of phenobarbital on frequency-dependent spike broadening and potassium inactivation was studied in snail neurons. 2. The amount of spike broadening was significantly depressed by the application of 10(-3) M phenobarbital but the time course of broadening was unaffected. 3. In voltage clamped neurons, this concentration of phenobarbital significantly depressed the amount of potassium current inactivation without altering its time constant. 4. A possible locus of phenobarbital's anticonvulsant action is through a decrease in synaptic efficacy resulting from a depression of presynaptic spike broadening.     

Rescue of developmental lens abnormalities in chimaeras of noncataractous and congenital cataractous mice

In the study of the lens of a congenital cataractous mouse mutant (CAT), it has been shown that a loss of growth regulation at the cellular level causes gross lens abnormalities. The phenotypic characteristics of the cataractous mouse lens are similar to those seen in human congenital cataract and thus serves as a model system for medical research. In this present investigation, we have demonstrated that the abnormalities of the congenital cataractous lens can be rescued by forming chimaeras between DBA/2 (a noncataractous strain of mouse) and the CAT mutant. This report describes the histological, cellular and biochemical analysis of the resultant chimaeric eyes, and discusses possible mechanisms by which these results were achieved.     

Electrophoretic and enzymatic analysis of glycosaminoglycans in the blood serum of patients with hyperthyroidism

An effect of hyperthyroidism on the composition and levels of glycosaminoglycans in the blood serum was studied. Glycosaminoglycans isolated from 1-ml blood samples were assayed with the following techniques: carbazole, electrophoretic and enzymatic. Separation and assay of particular GAG were made with bidirectional electrophoresis. Isomers of the remaining chondroitin sulphates were assayed enzymatically. Electrophoretograms of GAG in blood serum of healthy women have shown two fractions: low sulphate chondroitin sulphate and chondroitin-4-sulphate. The same fractions of GAG were found in blood serum of the female patients with hyperthyroidism. Mean concentration of GAG in the blood serum of hyperthyroid patients increased by 51%: low sulphate chondroitin sulphate and chondroitin-4-sulphate concentrations increased by 22% and 190% respectively. Chondroitin sulphates in the blood serum of both groups were degraded to unsaturated disaccharides not containing sulphur and unsaturated 4-sulphate disaccharides. Concentrations of unsaturated 4-sulphate and unsaturated sulphur-free disaccharides increased by 71% and 17% in hyperthyroidism. Observed changes in the blood serum GAG concentrations reflect changes in the connective tissue metabolism in hyperthyroidism.     

Results of combined therapy in patients with nonseminomatous testicular tumors

The results of multidrug therapy of 44 male patients with non-seminomatous testicular tumours are discussed. The diagnosed tumours were of all stages of the clinical advances and were treated with combined chemotherapy (surgery and PVP regimen). Thirty two patients (73%) are followed up between 7 and 103 months and survived, complete remission is noted in 29 patients (66%) including 6 patients who survived over 5 years. Symptoms of the tumour are found in 3 patients. Twelve patients (27%) died. The treatment did not produce life-threatening complications. The obtained results have been compared with those reported by other authors.     

Immunohistochemical techniques for detection of dermatan sulfate proteoglycan in tissue sections

Dermatan sulfate proteoglycan chains were detected in tissue sections treated with chondroitin B-lyase (0.01 units/ml) in 20 mM Tris-HCl (pH 8.0) for 1 hr, followed by staining with antibody 9A2 specific for unsaturated uronic acid coupled to N-acetylgalactosamine-4 sulfate. In contrast, after treatment with chondroitin B-lyase, no positive staining was observed with antibodies 3B3 and 1B5 which react to the unsaturated uronic acid coupled to N-acetylgalactosamine 6-sulfate and unsaturated uronic acid coupled to N-acetylgalactosamine, respectively. The distribution of dermatan sulfate thus revealed was confirmed by comparison with that found by monoclonal antibody 6B6 which reacts with small proteoglycans carrying dermatan sulfate side chains. The localization of positive staining in fibrous connective tissues was almost identical with these two procedures.     

A new approach to chromosome doubling for haploid rice plants

Summary Rice nodal segments from three flowering haploids were excised and treated for different lengths of time with 0.3% or 0.4% colchicine (dissolved in 2% DMSO) in an attempt to induce fertile seeds. A combination of higher colchicine concentration and longer hours of treatment reduced the survival rate of treated segments, but more fertile plants were transformed. Pooled data showed that of the 842 segments used, 42.2% survived the treatment and sprouted, but only 31.9% were successfully established and grown to maturity. Among the 269 mature plants, 29,4% produced fertile seeds (panicles) with an average of 146.2 seeds per diploidized plant.     

Effects of phorbol esters on endothelial cell microfilaments: Laser scanning confocal microscopy and quantitative morphometry of dose dependent changes

Phorbol esters are known to alter microfilaments but it is not clear if the changes correspond to modulation of the phosphoinositide turnover/protein kinase C system. The novel technique of laser scanning confocal epifluorescence was used to study fiber orientation in phorbol ester treated cells. We treated endothelial cells with control agents and agents known to stimulate protein kinase C: 4 alpha-phorbol, phorbol 12-myristate 13-acetate (PMA), phorbol dibutyrate (PDB), or lipopolysaccharide. After incubation with the test agents, the endothelial cell microfilaments were stained with rhodamine pholloidin and viewed by conventional epifluorescence and by laser scanning confocal epifluorescence microscopy. The images obtained by the confocal microscopy corresponded to a thin optical section through the cells, 300 nm or more in thickness. The microfilaments extended predominantly in the plane of focus. After exposure of the cells to phorbol esters, the stress fibers became more nearly parallel in arrangement or were shortened, but remained in the plane of focus. The modification of microfilaments in response to phorbol esters was quantitated by a single blind analysis. In order to compare the morphological changes with a biochemical action of the phorbol esters, we measured phosphoinositide turnover. The dose-dependence of morphological changes was compared and contrasted to the dose-dependent effect of phorbol esters on bradykinin-stimulated phosphoinositide turnover. PMA had about the same EC50 (1-5 nM) for both biochemical and morphological processes. PDB was less potent in inducing the disruption of microfilament structure than in inhibiting phosphoinositide turnover. Lipopolysaccharide was ineffective in inducing a morphological change under these conditions. A simple activation of protein kinase C is insufficient to explain the dose-dependent effects of phorbol esters. Thus a morphometric analysis can help distinguish the potency of cytoskeleton modulators.     

Pharmacokinetic disposition of pethidine under tolerance

Under tolerance, evoked by multiple doses of pethidine (PD), the serum and brain tissue content of PD was related to diminished analgesic activity. Even though in tolerant rats no enhancement of PD biotransformation in the liver could be recognized (as followed by the measurement of hepatic esterase and N-demethylase activity), the amounts of both PD and nor-PD excreted in urine were increased under tolerance. The authors conclude that the faster disposition of PD may contribute to the development of tolerance.     

Interleukin-6 triggers the association of its receptor with a possible signal transducer, gp130

Interleukin-6 mediates pleiotropic functions in various types of cells through its specific receptor (IL-6-R), the cDNA of which has already been cloned. We report here that an 80 kd single polypeptide chain (IL-6-R) is involved in IL-6 binding and that IL-6 triggers the association of this receptor with a non-ligand-binding membrane glycoprotein, gp130. The association takes place at 37 degrees C within 5 min and is stable for at least 40 min in the presence of IL-6, but does not occur at 0 degree C. Human IL-6-R can associate with a murine gp130 homolog and is functional in murine cells. Mutant IL-6-R lacking the intracytoplasmic portion is functional, suggesting that the two polypeptide chains interact to involve their extracellular portion. In fact, a soluble IL-6-R lacking the transmembrane and intracytoplasmic domains can associate with gp130 in the presence of IL-6 and mediate its function. These findings indicate that the complex of IL-6 and IL-6-R can interact with a non-ligand-binding membrane glycoprotein, gp130, extracellularly and can provide the IL-6 signal.