Immunofluorescence of somatostatin-producing sites in the hypothalamus of the tadpole,Alytes obstetricans Laur.

Summary Three sites of somatostatin-synthesizing perikarya, or a related antigen, were determined by immunofluorescence in the hypothalamus of the tadpole, Alytes obstetricans (Amphibia, Anura). Two sites of neurosecretory perikarya were localized in the preoptic nuclei of the anterior hypothalamus; the axons extended either to the anterior diencephalon or to the median eminence and the pituitary. The third site was found in the posterior hypothalamus. These neurosecretory cells showed a strong immunofluorescent reaction; their axons all terminated at the level of the median eminence. Somatostatin cells were only found in intact or hypophysectomized tadpoles given somatotropin (STH). The strong reaction observed in hypophysectomized tadpoles was possibly due to the loss of the terminal portion of the neurosecretory pathway (median eminence and pituitary) by which the agent is transported to the site of discharge.     

Calcium and sulphur in neurosecretory granules and calcium in mitochondria as determined by electron microscope X-ray microanalysis

Summary Sections of neurosecretory cells fixed in glutaraldehyde and osmium tetroxide were studied by means of an EMMA-4 analytical microscope. Secretory granules in neurosecretory cells of the corpus cardiacum and of the brain, both in the desert locust Schistocerca and in the blowfly Calliphora, as well as neurosecretory granules in posterior pituitaries of the frog Rana and of the albino rat all contain a high concentration of calcium. A distinct sulphur peak was also a constant feature.In neurosecretory cells of the corpus cardiacum of Schistocerca the chromatin contained a high concentration of calcium. The mitochondria also contained much calcium, but part of this disappeared during preparation except when fixative and wash contained calcium chloride. By block staining with uranyl acetate most calcium is displaced from the mitochondria, whereas most of the calcium remains in the neurosecretory granules. Since the calcium peaks in spectra from neurosecretory granules appear of similar size, regardless of variations in the preparative procedure, this calcium must be firmly bound. The possible role of the calcium bound to the neurosecretory substance is discussed.The presence of sulphur in insect neurosecretory granules indicates the presence of a protein besides the hormone, i.e., an insect neurophysin.We wish to thank Dennis Greer for the operation of the analytical microscope. This work was supported by a Wellcome-Carlsberg Travelling Research Fellowship awarded to T.N. The EMMA-4 facility is supported by a grant from the British Science Research Council     

Prostaglandin D2, another renal prostaglandin?

Prostaglandin (PG) D₂ was biosynthesized by rabbit renal papillae incubates in vitro. Quantification of the renal prostaglandins by gas chromatography-mass spectroscopy demonstrated that the concentration of PGD₂ generated by renal papillae was to the amount of PGE₂ or about 1 μg/g tissue/30 min. Infusion of the sodium salt of PGD₂ into the renal artery of the dog produced a dose related increase in renal blood flow and urine flow, free water clearance, sodium excretion and potassium excretion without changes in systemic hemodynamics. At low doses PGD₂ increased renal blood flow to all cortical zones. Higher concentrations of PGD₂ produced a shift in the intrarenal distribution of blood flow toward the juxtamedullary nephrons.     

Membrane fluidity in normal and cystic fibrosis fibroblasts

We have observed distinct differences in the polarization of fluorescence and temperature dependent emission intensity of the highly fluorescent phospholipid derivative (1-acyl-2-(N-4-nitrobenzo-2-oxa-1,3-diazole)--aminocaproyl phosphatidylcholine (NBD-PC), when incorporated in the plasma membranes of normal and cystic fibrosis fibroblasts. Fluorescence polarization measurements indicate that the fluorochrome has a much higher degree of rotational mobility in cystic fibrosis fibroblasts as compared with normal cells. Temperature dependent transitions in the emission intensity of NBD-PC incorporated in normal fibroblasts are indicated at 17.7 and 21.2° C while the abnormal cell membranes apparently undergo transitions at 8.7 and 13.5° C. These differences might be due to changes in plasma membrane composition and/or organization, in the case of the cystic fibrosis cells.     

Regulation of adenosine 5′-phosphosulfate sulfotransferase activity by H2S and cyst(e)ine in primary leaves of Phaseolus vulgaris L.

During chloroplast development in the primary leaves of Phaseolus vulgaris, the extractable activity of adenosine 5-phosphosulfate sulfotransferase increased ten-fold. When chloroplast development took place in air enriched with 3.5 l H₂S·l^-1 there was a decrease in adenosine 5-phosphosulfate sulfotransferase activity. Cyst(e)ine in concentrations up to 1 mM (in the external medium) did not affect the increase in adenosine 5-phosphosulfate sulfotransferase activity in intact plants. In plants with excised roots, 0.75 mM cyst(e)ine inhibited this increase. In green primary leaves, H₂S or cyst(e)ine treatment resulted in a decrease of extractable adenosine 5-phosphosulfate sulfotransferase activity. In intact plants, this effect of cyst(e)ine was observed at a concentration of 1 mM, and in plants with excised roots, 0.25 mM had a comparable effect.In developing plants, the extractable activities of O-acetyl-L-serine sulfhydrylase (EC 4.2.99.9) and ribulosebisphosphate carboxylase (EC 4.1.1.39.) were not affected by H₂S or cyst(e)ine.Abbreviations APS adenosine 5-phosphosulfate - APSSTase adenosine 5phosphosulfate sulfotransferase - BSA bovine serum albumin - DTE dithioerythritol - EDTA ethylenediaminetetra-acetic acid - OASSase O-acetyl-L-serine sulfhydrylase - PAPS adenosine 3-phosphate 5-phosphosulfate - POPOP 1,4 Di 2-(5-phenyloxazolyl)-benzene - PPO 2,5-diphenyloxazol - RubP ribulose-bisphosphate - RubPCase ribulosebiphosphate carboxylase This is no. 8 in the series Regulation of Sulfate Assimilation in Plants. The term cysteine is used when it is clear that cystine is not involved; cyst(e)ine is used for an undefined mixture of cysteine and cystine. The concentrations are expressed in all cases relative to cysteine     

Studies on immobilized α-glucosidase from brewers yeastSaccharomyces carlsbergensis

Summary -Glucosidase isolated from brewer's yeast (Saccharomyces carlsbergensis) was immobilized using hydroxymethacrylate activated by cyanogen bromide as a carrier. Up to a hundred-fold increase in the stability of the enzyme was observed after immobilization. The yield in activity (bound/applied) was up to 30%. Before developing the process of enzymatic cleavage of maltose further we evaluated the kinetic properties of the enzyme catalyst, as we had observed earlier that the soluble enzyme is strongly inhibited by the product glucose. This is even more pronounced with the immobilized -glucosidase leading in this case to a linear relation between initial rate and substrate concentration, so K_M (approx.) values can no longer be defined due to the dominating influence of the product inhibition.     

Estrous cycle regulation in the whitefooted mouse (Peromyscus leucopus) with special reference to vaginal cast formation

The estrous cycle of the whitefooted mouse (Peromyscus leucopus) was consistent with those described for most small rodents and closely resembled that of the house mouse and the rat in timing. The presence of the male did not accelerate puberty nor induce cycle synchrony, but was critical in establishing cycle regularity. Females isolated from influences of males never attained a pattern of concistent cycle length. Development of the vaginal epithelium during estrus was excessive in both isolated and non-isolated females, resulting in a "cast" of cornified epithelium which could be removed intact during metestrus. Casts removed during the making of vaginal smears measured up to 20 mm in length and still left a sufficient residue of cells which could be detected in all stages of the estrous cycle.     

Bacteriological quality of fabrics washed at lower-than-standard temperatures in a hospital laundry facility

We determined whether the bacteriological quality of fabrics cleaned in a hospital laundry could be maintained at wash temperatures lower than 75 degrees C by the use of economically reasonable formulas and wash conditions. Three groups of bacteria were examined to determine bacteriological quality: aerobic, nonexacting chemoorganotrophs, staphylococci, and total coliforms. The distribution of bacteria on soiled fabric was patchy, with staphylococci and total coliforms ranging from less than 0.1 to greater than 4 X 10(3) CFU/cm2 and chemoorganotrophs ranging from less than 0.1 to greater than 5 X 10(5) CFU/cm2. The washing process routinely produced fabric containing less than 1 CFU/cm2. Low-temperature (47.8 to 60.0 degrees C) wash procedures eliminated all bacterial groups at least as effectively as did high-temperature procedures. The effectiveness of bacterial density reduction at low temperature was augmented by increased concentrations of bleach. Successful low-temperature washing such as that shown here may save both energy and money for hospitals.     

Potent and specific blockade by AH 22216 of histamine-H2-receptor-mediated acid secretion in isolated rabbit gastric cells

AH 22216 is a new histamine-H₂-receptor antagonist which possesses a triazole ring. When compared to cimetidine, AH 22216 is about 100 times more potent (Ki = 0.21×10^–8 M) in inhibiting histamine-stimulated acid secretion in isolated rabbit gastric cells. These two antihistamines have no effect on carbachol-stimulated acid secretion in the system. The data indicate that AH 22216 interacts directly and specifically on the gastric H₂-receptor of the parietal cell and are consistent with the reported pharmacological potencies of AH 22216 and cimetidine on histamine-induced gastric-acid secretion in vivo. AH 22216 could thus be a useful therapeutic agent in patients with peptic ulcers.