Ketoconazole inhibits the conductance K+ induced by thyreoliberin (TRH) in GH3 cells

Ketoconazole an imidazole derivative used in clinical practice as an antifungal medicine interferes with the phospholipid dependent "second messenger" pathway. In this work we show that in the GH3 clonal cell line, ketoconazole (10 microM) inhibits part of the complex pattern of electrical activity induced by Thyrotropin-Releasing Hormone (TRH, 10 nM). The phase blocked by ketoconazole represents the Ca2+ -activated K+ conductance.     

Activation by bacterial lipopolysaccharide causes changes in the cytosolic free calcium concentration in single peritoneal macrophages

Variations in the cytosolic free Ca2+ concentration [( Ca2+]i) upon LPS exposure were studied in single rat peritoneal macrophages loaded with fura-2 under carefully controlled conditions. Of a total of 60 cells examined, 47% responded to LPS (1 microgram/ml) with an increase in [Ca2+]i. Macrophages were heterogeneous with regard to the LPS response, with individual cells exhibiting single rapid and transient increases in [Ca2+]i, multiple transients, or slower and more sustained variations. In 62% of the responding cells, a second exposure to LPS elicited a [Ca2+]i rise, although usually to a slightly lower peak value. Thus, rapid desensitization to LPS does not occur in the majority of these macrophages. EGTA did not abolish the response of those cells that exhibited a single rapid transient in [Ca2+]i, indicating that the source of the initial [Ca2+]i rise was the intracellular stores. There was no obvious correlation between the type of response to LPS and the initial morphologic features (rounded vs polarized) of the cells. Our present work shows unequivocally that LPS induces increases in macrophage [Ca2+]i and, thereby, lends substantial support to the hypothesis that [Ca2+]i is a second messenger in LPS-mediated activation of the macrophage.     

Effect of neurotensin on pancreatic function in man

The effect of neurotensin on submaximally-stimulated hepatobiliary and pancreatic secretion was studied in 6 healthy subjects. An intravenous infusion of neurotensin 1.4 ± 0.3 pmol/kg/min, designed to reproduce plasma neurotensin immunoreactivity levels within the physiological range, produced a significant increase in pancreatic bicarbonate output. Plasma concentrations of pancreatic polypeptide rose by 83 ± 16 pmol/l and were associated with a small reduction in trypsin, but no significant change in bilirubin outputs.     

Structural studies of the apoprotein of the Folch-Pi bovine brain myelin proteolipid : characterization of the CNBr-fragments and of a long C-terminal sequence.

The action of cyanogen bromide on the quite insoluble bovine proteolipid apoprotein allowed the determination of four peptide fragments: two of them constituted a 19 amino acid long C-terminal sequence of the apoprotein. Our results were in favour of the existence of only one subunit presenting a molecular weight closely related to 25,000 for which a schematic representation is given.     

Effect of Metalaxyl on the incidence and severity of Pearl millet downy mildew disease in Northern Nigeria

Pearl millet downy mildew (DM) incidence, severity and yield losses of two pearl millet varieties (local and improved) due to the disease were determined in the field. Significant differences in the disease incidence and severity were recorded in the plots sown with metalaxyl-treated seeds and those sown with non-treated seeds, indicating the efficacy of the fungicide on the fungus. Yield losses due to non-treatment of seeds with metalaxyl was 40.88 and 45.39% in a local variety and 43.00 and 18.60% in an improved variety in the 2000 and 2001 cropping seasons respectively. Significant differences between plots sown with metalaxyl-treated and those sown with non-treated seeds were obtained for other yield components such as 1000-grains weight, panicle length and weight.     

Voltage-dependent ionic conductances in the human malignant astrocytoma cell line U87-MG

Although the human malignant astrocytoma cell line U87-MG has been used in numerous studies, few findings are available on the properties of its membrane ion conductances. Characterization of the ion channels expressed in these cells will make it possible to study membrane ion conductance changes when a receptor is activated by its ligand. This will help to elucidate the functional properties of these receptors and their signal-transduction pathways in pathophysiological events. This work studied the voltage-dependent ionic conductances of U87-MG cells using the Whole-Cell Recording patch-clamp technique. Six types of voltage-dependent ionic currents were identified: (i) a TEA-, 4-AP- and CTX-sensitive Ca²⁺-dependent K⁺ current, (ii) a transient K⁺ current inhibited by 4-AP, (iii) an inwardly rectifying K⁺ current blocked by Ba²⁺ and 4-AP, (iv) a DIDS- and SITS-sensitive Cl^? current, (v) a TTX-sensitive Na⁺ conductance and (vi) a L-type Ca²⁺ conductance activated by BayK-8644 and inhibited by Ni and the L-type Ca²⁺ channel inhibitor, nifedipine. In addition, electrical depolarizations elicited inward currents due to voltage-independent, Ca²⁺-dependent K⁺ influx against the electrochemical gradient, probably via an ouabain-sensitive Na⁺-K⁺ pump.