Differential distribution of 5-hydroxytryptamine3 receptor in the colon between human and guinea pig

Localization of 5-hydroxytryptamine3 (5-HT3) receptor in the human colon was examined by in vitro receptor autoradiography using [125I](S)iodozacopride, and compared with that in the guinea pig colon. [125I](S)iodozacopride binding sites were found with high densities around the myenteric plexus, but with low ones in the muscle layer and mucosa of the human colon, and the binding was abolished by granisetron, a specific 5-HT3 receptor antagonist. While in the guinea pig colon, specific [125I](S) iodozacopride binding was not detected in either the myenteric plexus or the muscle layers. Thus, the 5-HT3 receptors are present in the human colon, especially densely located in the myenteric plexus, but not in the guinea pig colon, and those may participate in the colonic motility. The results of functional studies of 5-HT3 receptor obtained from experiments using guinea pig are not always applying to the human.     

Involvement of G protein betagamma-subunits in diverse signaling induced by G(i/o)-coupled receptors: study using the Xenopus oocyte expression system

We studied the functions of -subunits of G_i/o protein using the Xenopus oocyte expression system. Isoproterenol (ISO) elicited cAMP production and slowly activating Cl^– currents in oocytes expressing ₂-adrenoceptor and the protein kinase A-dependent Cl^– channel encoded by the cystic fibrosis transmembrane conductance regulator (CFTR) gene. 5-Hydroxytryptamine (5-HT), [D-Ala², D-Leu⁵]-enkephalin (DADLE), and baclofen enhanced ISO-induced cAMP levels and CFTR currents in oocytes expressing ₂-adrenoceptor-CFTR and 5-HT_1A receptor (5-HT_1AR), -opioid receptor, or GABA_B receptor, respectively. 5-HT also enhanced pituitary adenylate cyclase activating peptide (PACAP) 38-induced cAMP levels and CFTR currents in oocytes expressing PACAP receptor, CFTR and 5-HT_1AR. The 5-HT-induced enhancement of G_s-coupled receptor-mediated currents was abrogated by pretreatment with pertussis toxin (PTX) and coexpression of G transducin (G_t). The 5-HT-induced enhancement was further augmented by coexpression of the G-activated form of adenylate cyclase (AC) type II but not AC type III. Thus -subunits of G_i/o protein contribute to the enhancement of G_s-coupled receptor-mediated responses. 5-HT and DADLE did not elicit any currents in oocytes expressing 5-HT_1AR or -opioid receptor alone. They elicited Ca²⁺-activated Cl^– currents in oocytes coexpressing these receptors with the G-activated form of phospholipase C (PLC)-2 but not with PLC-1. These currents were inhibited by pretreatment with PTX and coexpression of G_t, suggesting that -subunits of G_i/o protein activate PLC-2 and then cause intracellular Ca²⁺ mobilization. Our results indicate that -subunits of G_i/o protein participate in diverse intracellular signals, enhancement of G_s-coupled receptor-mediated responses, and intracellular Ca²⁺ mobilization. G protein-coupled receptor; cystic fibrosis transmembrane conductance regulator gene; cross talk; electrophysiology     

Hurler-Scheie phenotype: A report of two pairs of inbred sibs

Summary Four cases from two families with dermatan sulfate mucopolysacchariduria who lack -L-iduronidase in peripheral leukocytes are described. The clinical and roentgenographic features of these cases represent an intermediate phenotype between Hurler's syndrome and Scheie's syndrome, and both parents in each family are first cousins. In the presence of parental consanguinity, a phenotypic variation or a third mutant allele at the iduronidase locus seems to be a more reasonable explanation for these cases than a genetic compound.     

Involvement of Protein Kinase C in γ-Aminobutyric Acid Release from Xenopus Oocytes Injected with Rat Brain mRNA

Abstract: Involvement of protein kinase C (PKC) in the release of γ-aminobutyric acid (GABA) was examined in Xenopus laevis oocytes injected with mRNA from rat cerebellum, as compared with findings in slices of rat cerebellum. The mRNA-injected oocytes preloaded with [³H]GABA showed spontaneous release of [³H]GABA, ∼0.5% of GABA content per 1 min. Stimulation with either Ca²⁺ ionophore (A23187) or a high K⁺ concentration increased the release of [³H]GABA from slices of rat deep cerebellar nucleus and mRNA-injected oocytes but not from noninjected and water-injected oocytes. 12- O -Tetradecanoylphorbol 13-acetate (10–300 n M ) but not 4α-phorbol 12,13-didecanoate (300 n M ) potentiated the A23187-stimulated release of [³H]GABA from slices and from mRNA-injected oocytes, in a concentration-dependent manner. Thus, machinery associated with release processes of GABA can be expressed in oocytes by injecting rat cerebellar mRNA, and PKC participates in GABA release from the functionally expressed GABAergic nerve terminals.     

Rheological measurement of blood coagulation in vascular vessel model tube consisting of endothelial cells monolayer

An in vitro experimental system was developed to study the interaction between endothelial cells and blood as an early event in coagulation. A designed vascular vessel model tube is composed of a monolayer of bovine aorta endothelial cells (BAECs) cultured on an inner surface of a glass tube by means of a rotatory cultivation method. The change of fluidity during coagulation of blood in the tube was measured by a rheological technique. The rate of coagulation of blood in contact with endothelial cells was affected by cell culture conditions such as cell age, passage number of BAECs and substrate beneath endothelial cells. Fibrinolytic activity of the cells was examined by the rheological method. The present experimental system would be useful in examining the mechanism of blood coagulation based on the interaction between blood and endothelial cells as well as in evaluating endothelial cell functions.     

Purification, identification, and characterization of elastase on erythrocyte membrane as factor IX-activating enzyme

In our previous papers, we reported that factor IX (F-IX), when activated by erythrocyte membranes, causes coagulation. We report on purification, identification, and characterization of F-IX-activating enzyme extracted from human erythrocyte membranes. The enzyme whose amino acid sequence is almost in accord with neutrophil elastase was found in normal erythrocyte membrane. The molecular mass was slightly smaller than that of neutrophil elastase. The content of the enzyme in erythrocyte membranes was estimated to be 3.0-3.7 ng per 10(6)erythrocytes. The F-IX sites cleaved by the enzyme were slightly different from those by the ordinary coagulation reaction. The ability of F-IX cleaved by the enzyme to cause coagulation was estimated to be approximately 1/10 as high as that of the F-IX cleaved by activated F-XI. These findings provide evidence that F-IX is activated by erythrocyte membrane, which may serve as a triggering mechanism for blood coagulation.     

Consumption of pork-liver protein hydrolysate reduces body fat in Otsuka Long-Evans Tokushima Fatty rats by suppressing hepatic lipogenesis

This study was performed to examine the effect of consumption of pork-liver protein hydrolysate (PLH) on body fat accumulation in Otsuka Long-Evans Tokushima Fatty (OLETF) rats as a non-insulin-dependent diabetes mellitus model and in Long-Evans Tokushima Otsuka (LETO) rats as a control. Male 20-week-old OLETF and LETO rats were pair-fed either PLH or casein containing diet for 14 weeks. In the OLETF rats, dietary PLH significantly reduced the growth and weight of fat pad including perirenal and epididymal adipose tissues. Consumption of PLH markedly suppressed hepatic activities of lipogenesis enzymes such as glucose-6-phosphate dehydrogenase and fatty acid synthase and slightly elevated fecal excretion of total fat. In the LETO rats, growth and adipose tissue weight were unaffected by dietary treatment. The results suggest that PLH is a novel ingredient suppressing body fat in genetically obese rats by reducing lipogenesis.