Effect of GRF and somatostatin on 7B2 secretion by rat GH1 cells

A novel pituitary protein "7B2" was secreted by GH1 cells. The secretion of 7B2 was increased in the presence of human GRF in a dose-responsive manner. In contrast, a somatostatin analog, SMS 201-995, revealed the inhibitory effects on the basal- and GRF-induced secretion of 7B2 at the concentration of 10(-7) M. These findings suggest that 7B2 is a secretory protein of rat GH1 cells under certain conditions.     

A toxic substance produced by Nocardia otitidiscaviarum isolated from cutaneous nocardiosis

During our studies on toxic substances from clinically isolated Nocarida, a new isolate identified as Nocardia otitidiscaviarum from cutaneous nocardiosis was found to produce a toxic substance called HS-6 that had strong in vitro as well as in vivo toxicity. The mouse intraperitoneal LD₅₀ value was 1.25 mg/kg and the ED₅₀ value for L1210 cultured cells was 0.3 ng/ml. The structure of HS-6 was determined and found to belong to the 16-membered macrocyclic group with a molecular formula of C₄₃H₆₈O₁₂. HS-6 also showed activity against pathogenic fungi such as Cryptococcus neoformans.     

Existence of a Common Glycoprotein Homologous to S-Glycoproteins in Two Self-incompatible Homozygotes of Brassica campestris

S-Glycoproteins (S-locus-specific glycoproteins) in Brassicaspecies are present only in stigmas and thought to play an importantrole in self-incompatibility system. The stigma extract containsalso several other glycoproteins reacting with the antiserumto S-glycoproteins, among which some glycoproteins from S₈S₈-and S₉S₉-homozygotes have the same pI value. Both of the glycoproteinswhich were tentatively termed NS₈- and NS₈S₉-glycoproteins,respectively, were isolated and analyzed. Those were revealedto be identical. Its amino acid sequence was homologous withthe S-glycoproteins in Brassica species. The NS-glycoproteinswere expressed at the same time and only in stigma as S-glycoproteins. (Received July 19, 1988; Accepted September 7, 1988)     

Evidence for secretion of 7B2 by A- and B-cells of hamster pancreatic islets.

7B2 is a neuroendocrine protein, and in the pancreatic islets the presence of 7B2 in A- and B-cells was immunohistochemically demonstrated. In order to examine 7B2 secretion by A- and B-cells of pancreatic islets, we prepared isolated hamster pancreatic islet cells as well as an A-cell-rich culture, and studied 7B2 secretion under certain stimulations. 7B2 was secreted by isolated hamster pancreatic islet cells. This secretion was stimulated by theophylline and arginine, but glucose had a weak effect on the 7B2 secretion. Such a response of 7B2 to the stimulations was different from that of insulin or glucagon. 7B2 secretion was also noted in the A-cell-rich culture. These results suggest that 7B2 is secreted by both A- and B-cells of the hamster pancreatic islets and its secretion is regulated under certain conditions.     

Estrogen participation in induction of cervicovaginal adenosis-like lesions in immature mice exposed prenatally to diethylstilbestrol

The structure of human zygapophyseal joint synovial folds as seen by high-power light microscopy and transmission electron microscopy is described. Small myelinated nerves are demonstrated in association with some capillaries in the synovial folds. This may have clinical significance in the field of spinal pain.     

Growth and Aspartate Kinase Activity in Wheat Cell Suspension Culture: Effects of Lysine Analogs and Aspartate-Derived Amino Acids

The effects of lysine analogs and aspartate-derived amino acidson the growth of wheat cell suspension culture were studied.S-(2-Aminoethyl)-L-cysteine (AEC), -hydroxylysine (DHL) andtrans-lysene caused complete growth inhibition at 1.0 mM. Thegrowth inhibition of lysine analogs were, in the order of decreasingeffectiveness; AECDHL, trans-lysene>oxalysine, homolysineand lysyne. cis-Lysene and methyllysine were not inhibitoryeven at concentrations of 10 mM. Lysine effectively relievedgrowth inhibition induced by the lysine analogs. Lysine plusthreonine showed concerted inhibition, which was relieved bythe addition of methionine. Activity of aspartate kinase extracted from wheat cell suspensionculture was strongly inhibited by L-lysine; 0.75 to 1 mM oflysine was required for half-maximal inhibition. Threonine andmethionine, individually or in combination with lysine, showedno inhibitory effect on the enzyme activity. S-Adenosylmethionine,when added with lysine in equimolar concentrations, enhancedthe feedback inhibition by lysine, lowering the concentrationof lysine for half-maximal inhibition to 0.13 mM. The aspartatekinase isolated from the cells cultured in the presence of 5mM lysine did not differ in regulatory properties from the enzymefrom the cells cultured without lysine. AEC at 5 mM inhibitedthe enzyme activity by 50%. Other lysine analogs were not inhibitoryto the enzyme activity even at 10 mM. Growth inhibition of wheat suspension culture by aspartate-derivedamino acids and lysine analogs were discussed in relation totheir inhibitory effects on aspartate kinase activity. (Received October 25, 1985; Accepted February 26, 1986)     

Effects of haloperidol and sulpiride on dopamine-induced inhibition of nucleus accumbens neurons

Microiontophoretic study was performed to elucidate dopaminergic mechanism in the nucleus accumbens (Acc) of rats anesthetized with chloral hydrate. Iontophoretically applied dopamine produced an inhibition of glutamate-induced firing in 28 (62%) out of 45 Acc neurons tested. The dopamine-induced inhibition of 14 Acc neurons was clearly antagonized by simultaneous application of haloperidol, and a partial antagonism by sulpiride was observed in 3 out of 10 Acc neurons. These results indicate that dopamine produces an inhibition of the Acc neuron and that, compared to haloperidol, sulpiride is a less potent blocker of the postsynaptic dopamine receptor involved in the dopamine-induced inhibition.     

Metabolism of Choline Chloride and Its Analogs in Wheat Seedlings

The incorporation rate of choline chloride and allylcholinebromide into wheat protoplasts were rapid compared with theincorporation rate of benzylcholine bromide. Choline chloridewas metabolized via two pathways: choline betaine and choline phosphorylcholine phos-phatidylcholine. Allylcholine bromidewas metabolized via only one pathway: allylcholine phosphorylallylcholine phosphatidylallylcholine, and benzylcholine bromide was notmetabolized at all. These results suggest that the stimulationof photosynthesis (Hyeon et al. 1988) by these compounds iscaused directly by these choline analogs and not by their metabolites. (Received June 29, 1989; Accepted October 20, 1989)     

Is helodermin-like immunoreactivity in human thyroid C cells due to a salmon calcitonin-like substance?

Helodermin-like and salmon calcitonin (sCT)-like immunoreactivities co-existed in a subset of human calcitonin (hCT)-containing cells in normal human thyroid tissue and medullary thyroid carcinomas. Helodermin/sCT-immunoreactive cells were mostly different from calcitonin gene-related peptide (CGRP)-positive cells. Helodermin and sCT immunoreactivities were not identified in pulmonary and pancreatic hCT-positive neuroendocrine tumors, except for a few lung tumor cells showing positive staining with one of two sCT antisera used. Helodermin immunoreactivity demonstrated by rabbit antiserum R0086 was completely abolished in the presence of synthetic sCT, while sCT immunoreactivity was not absorbed by synthetic helodermin. The carboxyl terminal Arg30-Thr31 sequence (and Pro35 amide structure) of helodermin would be the epitopic site recognized by this antiserum, since a similar amino acid sequence is present in sCT molecules but absent from hCT and CGRP.     

Inhibition of Endothelial Cell Differentiation on a Glycosylated Reconstituted Basement Membrane Complex

The vascular basement membrane is involved in the regulation of endothelial cell differentiation. The accumulation of advanced glycosylation endproducts (AGEs) has been demonstrated on these basement membranes in patients with diabetes. We examined the effect of AGEs on endothelial cell behavior on reconstituted basement membrane, Matrigel. Human umbilical vein-derived endothelial cells (HUVECs) stopped proliferating and differentiated into capillary-like tube-shaped structures on Matrigel. Laminin antibody partially blocked this process. HUVECs cultured on glycosylated Matrigel, however, proliferated and formed a monolayer without tube formation. The inclusion of aminoguanidine, an inhibitor of AGE formation, during the glycosylation of Matrigel restored HUVEC differentiation. Although the laminin adsorbed onto the plastic culture wells promoted HUVEC attachment and spreading, glycosylated laminin reduced HUVEC attachment by 50% and abolished cellular spreading. These effects were restored by aminoguanidine. HUVEC attachment to glycosylated laminin was further reduced by AGE-modified albumin, poly I, acetylated low-density lipoprotein, or maleylated albumin, ligands for a scavenger receptor. Coating the culture dishes with the laminin peptides RGD, YIGSR, and SIKVAV supported the attachment of HUVECs that was unaffected by glycosylation. Results suggest that AGE accumulation on the basement membranes inhibits endothelial cell differentiation by impairing the normal interactions of endothelial cell receptors with their specific matrix ligands. This process may be involved in diabetic angiopathy.