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Biomedical subjects

J Uchiyama

Publications and source records attributed to J Uchiyama.

At least 19 recordsLinked to original sources
PubMed1999

Absence of R1066X mutation in six Japanese patients with Dubin-Johnson syndrome.

The Dubin-Johnson syndrome (DJS) is a rare autosomal recessive liver disease characterized by chronic conjugated hyperbilirubinemia. The phenotype of this syndrome is thought to be caused by the impaired expression of the canalicular multispecific organic anion transporter (cMOAT), which transports non-bile salt organic anions into the bile. Recently, a mutation from arginine (Arg) to stop-codon at codon 1066 in the cMOAT gene has been reported in one Caucasian patient with DJS. In this study, we investigated whether this mutation is found in Japanese patients with DJS. Genomic DNAs were extracted from the leukocytes of six Japanese patients and the fragments spanning codon 1066 were amplified by polymerase-chain reaction. The digest of the amplified fragments with a restriction enzyme, Taql, demonstrated that all of six patients did not exhibit an R1066X mutation. No mutation at Arg1066 was also confirmed by direct sequencing of the amplified products. These findings suggested that this R1066X mutation was not a major mutation in Japanese patients with DJS. Further investigation will be required in an attempt to search other mutations in cMOAT gene in Japanese patients with DJS.

Adult↗
PubMed1998

Differential expression of multidrug resistance (mdr) and canalicular multispecific organic anion transporter (cMOAT) genes following extrahepatic biliary obstruction in rats.

The hepatic canalicular membrane has transporters that play an important role as efflux pumps in the excretion of endogenous bile constituents or xenobiotics into bile canaliculi. To elucidate functional significance of canalicular transporters in the mechanism of cholestasis, mRNA expression levels of multidrug resistance (mdr) 1b, mdr2 and canalicular multispecific organic anion transporter (cMOAT) genes were analyzed by Southern blotting of reverse-transcribed PCR products of liver mRNA obtained from cholestatic rats that had been subjected to bile duct ligation. Both mdr1b and mdr2 mRNA expression increased after ligation. Immunohistochemical study revealed that the products of both mdr1b and mdr2 were present on the canaliculi, and that their levels increased after ligation. In contrast, cMOAT mRNA expression was not increased, but rather attenuated by ligation. The expression of canalicular transporters was differentially regulated in extrahepatic biliary obstruction, indicating the different roles are played by mdr and cMOAT in the pathogenesis of cholestasis.

ATP Binding Cassette Transporter, Subfamily B↗
PubMed1998

Comparison of two interferon alfa treatment regimens characterized by an early virological response in patients with chronic hepatitis C.

OBJECTIVE: We investigated the efficacy of an interferon regimen characterized by an early virological response in patients with chronic hepatitis C and evaluated whether the patient's virological status during therapy would be useful for predicting a complete response. METHODS: We treated 62 patients with chronic hepatitis C with 6 million units (MU) of human lymphoblastoid interferon daily for 4 wk. The serum HCV RNA was assayed at week 2 by the reverse transcription-polymerase chain reaction. HCV RNA-negative patients (group A) received 6 MU of interferon three times weekly for an additional 22 wk (total dose, 564 MU). HCV RNA-positive patients were randomly assigned to group B-1, which received the same regimen as group A, or to group B-2, which received 6 MU of interferon daily for 4 wk followed by 6 MU three times weekly for 18 wk (total dose, 660 MU). RESULTS: Complete responses were achieved by 19 (63.3%) of 30 group A patients, compared with one (6.3%) of 16 group B-1 patients and none of 16 group B-2 patients. The virological response at week 2 and the pretreatment serum HCV RNA level were independent significant predictors of a complete response. CONCLUSION: Patients who were still HCV RNA-positive at week 2 were unlikely to achieve a complete response after interferon therapy. An increase in the total dose of interferon failed to yield further benefit in these patients.

Adult↗
PubMed1997

Fas ligand-mediated depletion of CD4 and CD8 lymphocytes by monomeric HIV-1-gp120.

In order to determine in what condition and by what mechanism gp 120 can deplete not only CD4 but also CD8 T cells, an in vitro system was established in which peripheral blood lymphocytes from healthy donors were treated with recombinant gp 120. We found that gp 120 can deplete both CD4 and CD8 T cells when they have recently been activated and are exposed to IL-2-deficient conditions. Bioassay of the Fas ligand (FasL) demonstrated augmented expression and release of soluble FasL by CD4 T cells in the supernatant of this culture. The administration of anti-FasL mAb and anti-Fas mAb, both of which exhibit neutralizing activity, completely abolished the depletion of these two T cell populations in culture. Based on these findings, we concluded that FasL depletes Fas antigen expressing CD4 and CD8 T cells by programmed cell death.

Antibodies, Monoclonal↗
PubMed1996

Induction of apoptosis by calmodulin-dependent intracellular Ca2+ elevation in CD4+ cells expressing gp 160 of HIV.

Human CD4+ cell clones expressing either gp160 or gp120 of HIV-1 under the transcriptional control of an inducible promoter were used to examine the role of Ca2+ signalling in the induction of apoptosis by envelope glycoproteins. Singlecell killing with apoptosis was induced in the cells expressing gp 160 while no such apoptosis was found in the cells expressing gp 120. An increase of intracellular Ca2+ was found in the gp 160-expressing cells but not in the gp 120-expressing cells as determined by Intracellular Ca2+ imaging analysis before the appearance of DNA fragmentation. W7, a calmodulin antagonist, blocked the elevation of Ca2+ as well as the resultant DNA fragmentation, which thus implies that the calmodulin-dependent intracellular Ca2+ release system is first activated by gp 160 and thereafter apoptosis takes place. The above results thus indicate that Ca2+ signalling plays a crucial role in the apoptosis accompanying the single-cell death induced by gp 160 in CD4+ cells.

Apoptosis↗
PubMed1995

Identification of the site of interaction of the 14-3-3 protein with phosphorylated tryptophan hydroxylase.

The 14-3-3 protein family plays a role in a wide variety of cell signaling processes including monoamine synthesis, exocytosis, and cell cycle regulation, but the structural requirements for the activity of this protein family are not known. We have previously shown that the 14-3-3 protein binds with and activates phosphorylated tryptophan hydroxylase (TPH, the rate-limiting enzyme in the biosynthesis of neurotransmitter serotonin) and proposed that this activity might be mediated through the COOH-terminal acidic region of the 14-3-3 molecules. In this report we demonstrate, using a series of truncation mutants of the 14-3-3 eta isoform expressed in Escherichia coli, that the COOH-terminal region, especially restricted in amino acids 171-213, binds indeed with the phosphorylated TPH. This restricted region, which we termed 14-3-3 box I, is one of the structural regions whose sequence is highly conserved beyond species, allowing that the plant 14-3-3 isoform (GF14) could also activate rat brain TPH. The 14-3-3 box I is the first functional region whose activity has directly been defined in the 14-3-3 sequence and may represent a common structural element whereby 14-3-3 interacts with other target proteins such as Raf-1 kinase. The result is consistent with the recently published crystal structure of this protein family, which suggests the importance of the negatively charged groove-like structure in the ligand binding.

14-3-3 Proteins↗
PubMed1994

Differential effects of methylmercury on the phosphorylation of protein species in the brain of acutely intoxicated rats.

The in vivo effect of methylmercury (MeHg) on the phosphorylation in vitro of the brain cytosol fraction was examined in acutely poisoned rats (10 mg/kg/day, for 7 days). The total phosphorylation activity, determined in the presence or absence of protein kinase effectors (Ca2+ and cAMP) and substrates (casein, histone and protein kinase C substrate), did not markedly change with the progress of intoxication. Two-dimensional electrophoretic analysis of the phosphorylated cytosol fractions from control and MeHg-treated rats revealed that (1) the extents of phosphorylation of the 24 major protein species in the control rats differed greatly from each other, (2) the effect of MeHg on the phosphorylation was not uniform regarding the individual 24 proteins or the period of intoxication, and (3) in the symptomatic period, many protein species including tubulin subunits showed elevated phosphorylation, while a few protein species showed decreased phosphorylation. These results suggest that the neurotoxic action of MeHg could be mediated through, at least in part, the modification of functional protein species due to excess phosphorylation that leads to impairment of the normal cellular processes.

Amino Acid Sequence↗
PubMed1992

Accumulation of vanadium during embryogenesis in the vanadium-rich ascidian, Ascidia gemmata.

It is a remarkable and previously unrecognized fact that ascidians, which are known to contain high levels of vanadium in their blood cells, begin to accumulate vanadium during embryogenesis. This study revealed that the accumulation starts quite dramatically 2 wk after fertilization, and 2 mo later, the amount of vanadium in larvae is 600,000 times higher than that in the unfertilized egg. These results were obtained by neutron activation analysis, a highly sensitive method for determining levels of vanadium, in the Ascidia gemmata, the ascidian that contains the highest known levels of vanadium and accumulates vanadium at 150 mM in its blood cells, a concentration that corresponds to 4,000,000 times the concentration in seawater.

Animals↗
PubMed1991

Evaluation of a new calcium containing cardioplegic solution in the isolated rabbit heart in comparison to a calcium-free, low sodium solution.

Isolated perfused rabbit hearts were studied to compare the effects of 3 hour ischemic arrest following either calcium-free or calcium-containing cardioplegia, on the recovery of isovolumic function of the left ventricle, coronary flow, release of creatine phosphokinase and myocardial water content. The hearts perfused with the calcium-containing solution (Ca 0.5 mmol/L) showed better recovery of the developed pressure in the left ventricle, and its first derivative and compliance. Coronary flow at a constant perfusion pressure was better restored during reperfusion in the hearts with calcium-containing solution. The release of less CPK and a lower water content were also observed in the hearts reperfused with calcium-containing solution. We concluded that calcium-containing cardioplegic solution with a high concentration of magnesium (10 mmol/L) was superior to calcium-free solution for myocardial protection.

Animals↗
PubMed1991

Analysis of K. pneumoniae by monoclonal antibody: immunohistochemical detection of K. pneumoniae surface antigen injected into mice and rats.

The monoclonal antibody Kp62 recognized surface antigenic determinants of some strains of Klebsiella pneumoniae. The antigen recognized by Kp62 was demonstrated on the bacterial surface using immunoelectron microscopy. Kp62 reacted with K. pneumoniae No. 1 or K. pneumoniae B 5055 and lipopolysaccharide (LPS) from the same bacteria. However, Kp62 was not inhibited by the LPS from Escherichia coli (E. coli) O111:B4 and E. coli O55:B5. Thus, Kp62 might be a useful monoclonal antibody to detect K. pneumoniae and LPS from K. pneumoniae. The possibility to visualize the localization of K. pneumoniae LPS injected into animals using immunohistochemical methods with this monoclonal antibody was examined. It was possible to detect the injected LPS in the spleen of mouse and rat with the monoclonal antibody to K. pneumoniae. In order to detect the early events taking place in the spleen after intravenous injection of LPS, time course of LPS distribution in mice and rats was studied. After 30 min, 2, 4, 8 and 24 h LPS localized in the marginal zone (MZ) in mice and rats, although the degree of LPS positive cells varied. The cells responsible for trapping the injected LPS appeared to be marginal zone macrophages. The early trapping of LPS by marginal zone macrophages was thought to be important for the following immune responses to the injected LPS. Interestingly the antigenic determinant on the injected LPS appeared to last long on or within the cells in the spleen from the injected animals. Such a remaining antigen might be important for the continuous stimulation of B cells by the LPS. With respect to the distribution of red pulp (RP) and white pulp (WP), we found the varied distribution of LPS between mouse and rat, and SPF and conventionally fed (Conv) animals. For example, LPS-positive cells in RP of rat were scarce, while significant degree of LPS-positive cells were observed in mice. And in WP, LPS-positive cells were observed in Conv DA rats, but not in mice or SPF-fed Wistar rats. These results may suggest that the mode of antigen processing may be different in the spleen of rat and mouse or even among the different strain of rats and previous sensitization to the LPS (or the similar antigenic determinants) may lead to the different distribution of LPS in the spleen. The monoclonal antibody specifically raised against K. pneumoniae was shown to be very useful to follow the fate of LPS derived from K. pneumoniae using immunohistochemical method.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1988

Production of monoclonal antibodies against surface antigenic determinants of Klebsiella pneumoniae.

The production of four murine monoclonal antibodies (Kp26, Kp53, Kp62 and Kp71) to Klebsiella pneumoniae surface antigen(s) is described. The binding of all four monoclonal antibodies to K. pneumoniae was inhibited by F(ab')2 fragments of normal human serum IgG, suggesting that the antigenic determinants of K. pneumoniae detected by the four monoclonal antibodies may be similar to those recognized by human serum IgG. The antigen identified by Kp62 was purified from a deoxycholate-solubilized bacterial fraction using immunoaffinity chromatography. The molecular weight of the antigen was determined by sodium dodecyl sulphate polyacrylamide gel electrophoresis to be 50,000-70,000.

Animals↗