The aim of the present study was to examine the effects of calcitonin gene-related peptide (CGRP) on the K+ channels of vascular smooth muscle cells. Cultured smooth muscle cells from a porcine coronary artery were studied using the patch-clamp technique. Extracellular application of 100 nM CGRP activated two types of K+ channels, the Ca(2+)-activated K+ channel (KCa channel) and the ATP-sensitive K+ channel (KATP channel) in cell-attached patch configurations. In cells pretreated with Rp-cAMPS, a membrane-permeable inhibitor of cAMP-dependent protein kinase (PKA), extracellular application of 100 nM CGRP could not activate the KCa or KATP channel, indicating that the activation of the K+ channels by CGRP occurs in connection with PKA. In the cell-attached patch configurations, extracellular application of 1 mM dibutyryl cAMP, a membrane permeable cAMP, activated KCa and KATP channels. In inside-out patch configurations, application of PKA to the cytosolic side activated both the KCa and KATP channels. These results indicate that CGRP modulates the K+ channels of vascular smooth muscle cells via adenylate cyclase, i.e., cAMP-PKA pathway, and contributes to control of vascular tone.

Adenylyl Cyclases↗

PubMedDate not supplied

Proton magnetic resonance spectroscopy on childhood-onset dentatorubral-pallidoluysian atrophy (DRPLA).

To evaluate brain dysfunction of childhood-onset dentatorubral-pallidoluysian atrophy (DRPLA), three children with progressive myoclonus epilepsy, who were diagnosed as having DRPLA by DNA analysis, for the first time, underwent a study of proton magnetic resonance spectroscopy (1H-MRS). 1H-MRS obtained from both the parietal and basal ganglia regions disclosed markedly reduced ratios of N-acetylaspartate to both choline and creatine. Especially regarding the basal ganglia region, the latter (ratio of N-acetylaspartate to creatine) closely correlated to severity of genetic abnormality, i.e. number of expanded CAG repeats, suggesting that the degree of neuronal loss in the region strongly depends on genetic factors. 1H-MRS must be a valuable tool to clarify the pathophysiology of DRPLA.

Adolescent↗

PubMedDate not supplied

Endoscopic evaluation of the therapeutic effect of sclerotherapy for esophageal varices.

The rebleeding rate after endoscopic injection sclerotherapy was studied in 237 patients with esophageal varices, and the optimal outcome of treatment was determined. Two new categories, RC(2-) and F0, were added to the classification scheme of endoscopic findings of varices in Japan. RC(2-) represents a state in which no veins, not even small vessels, are observed by endoscopy after endoscopic injection sclerotherapy, and F0 represents a state in which no localized venous dilations in the esophagus exist. The criteria for defining the other categories were not altered, and the R-C sign was expressed as RC(2-), RC(-), or RC(+); the degree of dilation was classified as F0 to F3. By combining the R-C sign and the F number, endoscopic findings were classified 1 to 4 weeks after endoscopic injection sclerotherapy into groups designated RC(2-)F0, RC(-)F0, RC(-)F1, and RC(+)F1-RC(+)F2. The four groups were observed to determine the incidence of esophageal stricture and rebleeding. In the RC(2-)F0 group, the incidence of stricture was high, but the rebleeding rate was low. In the RC(-)F0 group, both the incidence of stricture and rebleeding rate were low. We conclude that the optimal outcome of endoscopic injection sclerotherapy is RC(-)F0.

Esophageal and Gastric Varices↗

PubMedDate not supplied

Suppressive effect of ursodeoxycholic acid on regenerating cells.

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Animals↗

PubMedDate not supplied

Pathophysiological role of nitric oxide in rat experimental colitis.

Overproduction of nitric oxide (NO) by inducible nitric oxide synthase (iNOS) may contribute to the pathophysiology of ulcerative colitis. A 2,4,6-trinitrobenzenesulfonic acid sodium salt (TNBS) colitis model was established to examine the effect of selective iNOS inhibition, by S-(2-aminoethyl) isothiouronium bromide (ITU), on colonic mucosal cell damage and inflammation. Rats, killed 7 days after TNBS, had increased colonic mucosal levels of iNOS and interleukin-8 (IL-8), in addition to severe colonic inflammation which was characterized by significantly increased colon weight, damage score and colonic myeloperoxidase activity (MPO) (a marker of neutrophil influx). TNBS-treated rats had markedly decreased body weight and thymus weight. Administration of colitic rats with ITU significantly inhibited iNOS activity/expression and tended to reduce mucosal levels of IL-8, but no effect on MPO activity was observed. Following ITU therapy, colitic rats had reduced colonic damage and losses in body weight and thymus weight were reversed. Improvement of TNBS colitis by ITU suggested that excess NO, produced by iNOS, may have contributed to the initiation/amplification of colonic disease, by mechanisms including enhancement of IL-8 release. NO-mediated enhancement of pro-inflammatory cytokine release was further investigated in vitro. Lipopolysaccharide (LPS) and interferon-gamma (IFN-gamma) stimulated release of nitrite, lactate dehydrogenase (LDH), TNF alpha, IL-1 beta and IL-8 from rat peritoneal macrophages, all of which were significantly reduced by ITU. This suggests that NO-mediated cell damage enhances pro-inflammatory mediator release from macrophages. In addition, enhancement of IL-8 and TNF alpha release was also partially NO-dependent in activated peritoneal neutrophils. Therefore, the amelioration of TNBS colitis by ITU could include inhibition of NO-mediated pro-inflammatory cytokine release.

Animals↗

PubMedDate not supplied

Preparation of stereoregulated antisense oligodeoxyribonucleoside phosphorothioate and interaction with its complementary DNA and RNA.

Diastereoisomeric specificity of oligodeoxyribonucleoside phosphorothioate (OPT) in DNA/OPT and RNA/OPT hybrid formation was investigated. The difference in the configuration between RRRR and SSSS was reflected in the conformation and the stability of the DNA/OPT and RNA/OPT hybrids. Therefore, findings of this report rationalize the antisense effect by non-stereoregulated OPT and the difference of diastereoisomerism in susceptibility to RNase H.

Circular Dichroism↗

PubMedDate not supplied

Improvement of metabolic performance of hepatocytes cultured in vitro in a packed-bed reactor for use as a bioartificial liver.

A packed-bed reactor using reticulated polyvinyl formal (PVF) resin as a support material is a useful configuration to achieve high density culture of hepatocytes for use as a bioartificial liver. The authors investigated the effects of oxygen concentrations of the culture medium on the metabolic performance of hepatocytes cultured in the reactor. A packed-bed reactor loaded with 250 PVF resin cubes (2 x 2 x 2 mm) was used. Hepatocytes obtained from male Wistar rats were inoculated into the reactor. Culture medium was perfused from the reservoir into the reactor through an oxygenator using a roller pump. Concentration of the dissolved oxygen in the medium was controlled by changing the gas mixture ratio supplied to the oxygenator. Hepatocytes cultured in the packed-bed reactor (cell density: 8.6 x 10(6) cells/cm3 PVF) under conditions of high dissolved oxygen concentrations ranging from 260 to 460 micromol/L showed 30% higher ammonium metabolic activity and 85% higher albumin secretion activity compared with those from the monolayer culture in the earlier culture stage (up to 2 days). However, low oxygen concentrations in the medium (<100 micromol/L) impaired activities of cultured hepatocytes.

Animals↗

PubMedDate not supplied

Effects of shear stress on metabolic function of the co-culture system of hepatocyte/nonparenchymal cells for a bioartificial liver.

To improve the culture conditions of hepatocytes for use as a bioartificial liver, the effects of shear flow on the co-culture system of hepatocytes/nonparenchymal cells (NPC) were investigated. A flow chamber with a collagen coated rectangular glass plate, where hepatocytes (5 x 10(4) cell/cm2) and NPC (2 x 10(5) cell/cm2) were seeded, was used to attain a shear stress of 4.7 dyne/cm2. Concentrations of ammonia and urea in the medium were measured daily during the 2 week experiment. The metabolic activity of hepatocytes in the homotypic culture were lower than those of the co-culture, especially when the cultivation time exceeded 1 week. In addition, the applied shear flow promoted activity of the co-culture system. An enhancement in the rates of ammonium removal and urea synthesis was obtained in the perfusion systems. Morphologic observation revealed that aggregates of hepatocytes formed abundantly in the perfusion system and hepatocytes developed a cuboid shape. This suggested that perfusion affected the function and morphology of hepatocytes in the co-culture system. Shear flow could induce cell-cell interactions and secretion of extracellular matrix through the activation of NPC.

Animals↗