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Biomedical subjects

M Shibata

Publications and source records attributed to M Shibata.

At least 19 recordsLinked to original sources
PubMed1992

Positive regulation of mu-calpain action by polyphosphoinositides.

Whether calcium is the only major intracellular activator of calpain has not yet been established. Here we demonstrate that polyphosphoinositides may play critical roles in the activation process of mu-calpain. Experiments with purified enzyme, substrate (fodrin), and phospholipids show that only polyphosphoinositides but not other lipids significantly promote calpain action in the physiological intracellular calcium range of 10(-7) to 10(-6) M. The effect of polyphosphoinositide is exerted through both a reduction in the calcium concentration required for calpain autolysis and an increase in the Vmax of the proteolytic reaction. Neomycin, a polyphosphoinositide-binding antibiotic, inhibits both polyphosphoinositide-assisted proteolysis in test tubes and calcium-induced calpain activation coupled with substrate proteolysis in intact cells. This implies that the presence of polyphosphoinositides may actually be a prerequisite for calpain activation inside cells.

Amino Acid Sequence↗
PubMed1992

Hepatitis C virus infection in hepatocellular carcinoma. Detection of plus-strand and minus-strand viral RNA.

BACKGROUND: Although serum antibody to hepatitis C virus (anti-HCV) is found in many patients with hepatocellular carcinoma, the actual roles of HCV in carcinogenesis are unknown. METHODS: With reverse transcription followed by the polymerase chain reaction (RT-PCR), HCV RNA was examined in the sera and liver tissues of 16 patients with hepatocellular carcinoma who did not have hepatitis B virus markers, 13 of whom had anti-HCV. RESULTS: In the 13 patients with anti-HCV, the HCV genomic plus-strand RNA was detected more frequently in noncancerous tissues (8 patients, 61.5%) and in sera (6 patients, 46.2%) than in cancerous tissues (3 patients, 23.1%). No viral RNA was found in either sera or tissues in the three patients without anti-HCV. By using a sense primer for the RT in the RT-PCR assay, amplification was attempted of a putative complementary minus-strand RNA that is believed to reflect viral replication in the eight patients with the plus-strand RNA. The minus-strand RNA was found in the noncancerous tissues of six patients; it was not detected in the cancerous tissues. CONCLUSIONS: These results suggest that HCV can infect and replicate predominantly in noncancerous cells but rarely in tumor cells.

Aged↗
PubMed1992

Cloning of ASH, a ubiquitous protein composed of one Src homology region (SH) 2 and two SH3 domains, from human and rat cDNA libraries.

The protein ASH (for abundant Src homology), composed of one Src homology region (SH) 2 and two SH3 domains, was cloned by screening human and rat cDNA libraries with an oligonucleotide probe directed to a consensus sequence of the SH2 domains. The rat-derived ASH peptide was comprised of 217 amino acids with a molecular mass of 25-28 kDa and was found to be ubiquitous in rat tissues. A human cDNA clone was also found to code for part of the same protein, suggesting that ASH is common to human and rat. The amino acid sequence of ASH was strikingly similar to Sem-5, the product of a nematode cell-signaling gene, and ASH is most probably a mammalian homologue of Sem-5. ASH bound in vitro to phosphotyrosine-containing proteins, including activated epidermal growth factor receptor, the ASH SH2 domain being responsible for the binding. Induced expression of an antisense ASH cDNA led to a reduction in cell growth. Considering these observations and the structural homology to Sem-5, ASH is likely to function as a ubiquitous signal transducer, possibly resembling Sem-5, which communicates between a receptor protein tyrosine kinase and a Ras protein.

Adaptor Proteins, Signal Transducing↗
PubMed1992

Inhibition of the light-induced H+ release from uncoupled thylakoid membranes by N-ethylmaleimide.

The light-induced H+ release from thylakoids, which can be observed under completely uncoupled conditions, was inhibited by the SH reagent N-ethylmaleimide (NEM) and its analogs, while the conventional H+ uptake and electron transfer were not affected. The half-inhibiting concentration of NEM for the H+ release was 10 mM and 4 mM in thylakoids in the presence of nigericin and in CF1-depleted thylakoids, respectively. The inhibitory effect increased with the increase in hydrophobicity of the NEM analogs: N-methylmaleimide less than N-ethylmaleimide less than N-phenylmaleimide. It is suggested that SH groups in hydrophobic interior within the membrane are essential to the release of protons.

Chloroplasts↗
PubMed1992

Pial arteriolar constriction following cortical spreading depression is mediated by prostanoids.

The mechanism of pial arteriolar constriction during post-cortical spreading depression (CSD) was examined in anesthetized adult rabbits. Using a closed cranial window and intravital microscopy, the diameter of a pial arteriole was determined. A single CSD was induced by KCl micro-injection and its propagation was monitored by recording slow potential changes accompanying CSD. Prostanoid levels in cortical cerebrospinal fluid (CSF) were determined by radioimmunoassay. Pial arteriolar diameter increased significantly from 76 +/- 6 to a maximum of 119 +/- 5 microns (57%, n = 8) for 1.6 +/- 0.1 min when CSD (velocity, 2.8 +/- 0.1 mm/min) reached the cortex just beneath the vessel irrespective of its location. Shortly after CSD expiration from the cortex, pial arteriolar diameter decreased from the pre-CSD level to a minimum of 67 +/- 5 microns (12%, n = 8) for 19.5 +/- 2.1 min. CSD was elicited again in the same animal while the cortical surface under the window was continuously superfused with artificial CSF at a flow rate of 3.2-4.5 ml/min. Pial arteriolar dilation (from 75 +/- 6 to 115 +/- 3 microns, 53 +/- 9%, for 1.6 +/- 0.1 min, n = 8) was observed again during CSD (velocity, 2.7 +/- 0.2 mm/min), however, no constriction of the vessel was seen after CSD expiration. Indomethacin pretreatment (n = 11) to inhibit prostanoid production enhanced the magnitude of CSD-induced vasodilation from the pretreatment levels of 59 +/- 9% (from 82 +/- 5 to 130 +/- 8 microns for 1.7 min) to the post-treatment levels of 82 +/- 13% (from 78 +/- 5 to 142 +/- 12 microns for 1.8 min).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Detection and quantification of anti-Ki antibodies by enzyme-linked immunosorbent assay using recombinant Ki antigen.

OBJECTIVE: To establish an enzyme-linked immunosorbent assay (ELISA) for detecting anti-Ki antibody, using a bovine recombinant Ki antigen, and studying its specificity. METHODS: Sera from 220 patients with various connective tissue diseases were screened, and a prospective study of fluctuations in anti-Ki antibody and clinical course of a woman with systemic lupus erythematosus (SLE) was analyzed, by ELISA: RESULTS: Anti-Ki antibodies were present in 18.9% of patients with SLE. The titer of anti-Ki antibody in the woman with SLE rose before the onset of pericarditis and pleuritis in this longitudinal study. CONCLUSION: ELISA using a recombinant Ki antigen is useful for the diagnosis of SLE, and it might be useful in estimating disease activity in patients with SLE.

Animals↗
PubMed1992

Detection of hepatitis C virus by polymerase chain reaction and response to interferon-alpha therapy: relationship to genotypes of hepatitis C virus.

To investigate the relationship between genotypes of hepatitis C virus and response to interferon-alpha therapy, hepatitis C virus RNA was assayed by polymerase chain reaction with three sets of primers and probes in 70 patients with non-A, non-B chronic hepatitis who received interferon-alpha. Twenty-four patients sustained long-term remissions (complete responders). Polymerase chain reaction for 5'-terminal noncoding region detected hepatitis C virus RNA in 94.3% (66 of 70) of the patients. Polymerase chain reaction for nonstructural region 3, in which primers and a probe were synthesized to be identical to hepatitis C virus-J, detected hepatitis C virus RNA in 40 patients. Polymerase chain reaction for nonstructural region 5-in which sequences of primers and a probe were derived from hepatitis C virus-K2, a genotype different from hepatitis C virus-J--detected hepatitis C virus RNA in 17 patients. Only one patient was positive on both nonstructural region 3 and nonstructural region 5 polymerase chain reaction. Nucleotide sequence of clones obtained from 5' terminal noncoding region polymerase chain reaction products of two patients positive on polymerase chain reaction for nonstructural region 3 and negative on polymerase chain reaction for nonstructural region 5 (group 1) corresponded to that of the hepatitis C virus-J group, and those of clones from two patients negative on polymerase chain reaction for nonstructural region 3 and positive on polymerase chain reaction for nonstructural region 5 (group 2) corresponded to that of hepatitis C virus-K2.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Two different protein kinases act on a different time schedule as glial filament kinases during mitosis.

Glial fibrillary acidic protein (GFAP) is a component of glial filaments specific to astroglia. We now report the spatial and temporal distributions of four phosphorylated sites in the GFAP molecule during mitosis of astroglial cells, determined by antibodies which can distinguish phosphorylated epitopes from non-phosphorylated-epitopes. Immunofluorescence microscopy showed that the Ser8 residues in the entire cytoplasmic glial filament system are initially phosphorylated when the cells enter mitosis. In cytokinesis, the phosphoSer8 residues become dephosphorylated, whereas Thr7, Ser13 and Ser34 in glial filaments at the cleavage furrow become the preferred sites of phosphorylation. The cdc2 kinase purified from mitotic cells can phosphorylate GFAP at Ser8 but not at Thr7, Ser13 or Ser34, in vitro. These results suggest that cdc2 kinase acts as a glial filament kinase only at the G2-M phase transition while other glial filament kinases are probably activated at the cleavage furrow before final separation of the daughter cells.

Amino Acid Sequence↗
PubMed1992

Chloroplast DNA of black pine retains a residual inverted repeat lacking rRNA genes: nucleotide sequences of trnQ, trnK, psbA, trnI and trnH and the absence of rps16.

A physical map of black pine (Pinus thunbergii) chloroplast DNA (120 kb) was constructed and two separate portions of its nucleotide sequence were determined. One portion contains trnQ-UUG, ORF510, ORF83, trnK-UUU (ORF515 in the trnK intron), ORF22, psbA, trnI-CAU (on the opposing strand) and trnH-GUG, in that order. Sequence analysis of another portion revealed the presence of a 495 bp inverted repeat containing trnI-CAU and the 3' end of psbA but lacking rRNA genes. The position of trnI-CAU is unique because most chloroplast DNAs have no gene between psbA and trnH (trnI-CAU is usually located further downstream). Black pine chloroplast DNA lacks rps16, which has been found between trnQ and trnK in angiosperm chloroplast DNAs, but possesses ORF510 instead. This ORF is highly homologous to ORF513 found in the corresponding region of liverwort chloroplast DNA and ORF563 located downstream from trnT in Chlamydomonas moewusii chloroplast DNA. A possible pathway for the evolution of black pine chloroplast DNA is discussed.

Amino Acid Sequence↗
PubMed1992

Oxygen availability and motor unit activity in humans.

Six men were studied to determine the interrelationships among blood supply, motor unit (MU) activity and lactate concentrations during intermittent isometric contractions of the hand grip muscles. The subjects performed repeated contractions at 20% of maximal voluntary contraction (MVC) for 2 s followed by 2-s rest for 4 min with either unhindered blood circulation or arterial occlusion given between the 1st and 2nd min. The simultaneously recorded intramuscular MU spikes and surface electromyogram (EMG) data indicated that mean MU spike amplitude, firing frequency and the parameters of surface EMG power spectra (mean power frequency and root mean square amplitude) remained constant during the experiment with unhindered circulation, providing no electrophysiological signs of muscle fatigue. Significant increases in mean MU spike amplitude and frequency were, however, evident during the contractions with arterial occlusion. Similar patterns of significant changes in the surface EMG spectra parameters and venous lactate concentration were also observed, while the integrated force-time curves remained constant. These data would suggest that the metabolic state of the active muscles may have played an important role in the regulation of MU recruitment and rate coding patterns during exercise.

Adult↗
PubMed1992

Correlation between detection of anti-viral antibody and histopathological disease activity in an epidemic of hepatitis C.

There was an epidemic of non-A non-B hepatitis in a small area of a town in the central part of Japan, which began with an outbreak of several patients in 1981 and then spread extensively with the result that about one third of the inhabitants showed abnormality in serum liver function tests at the health check performed in 1985. We determined histological diagnoses on that occasion for 167 individuals of the abnormal population and recently assayed antibodies against hepatitis C virus (HCV) for most of their sera left available. Histologically, chronic active hepatitis (CAH) was the major pattern, accounting for 59.3% (99 cases) of the total. Others were chronic persistent hepatitis (CPH) (13.2%), chronic lobular hepatitis (CLH) (16.2%), liver cirrhosis (LC) (6.6%) and fatty liver (4.8%). In the serological studies, the newly developed system to detect antibodies against the viral core protein p 22 was found to be much more sensitive than the conventional system to detect anti C 100-3 antibodies. By using these two methods in combination, we found that 82% were antibody-positive, indicating strong implication of HCV in this epidemic. This was further supported by direct detection of the viral genome in patients' sera by polymerase chain reaction following reverse transcription. We further found a strong correlation between the histological inflammatory activity and the antibody prevalence, since nearly all (97.6%) of the CAH cases were antibody-positive by at least either of the antibody assays, while only about 50% were positive in the less active cases such as CPH and CLH.

Base Sequence↗
PubMed1992

Complement-dependent lysis of tumor cells by a baboon IgM antibody to a tumor-associated antigen.

We developed a high-titer polyclonal antiserum to a glycoprotein tumor-associated antigen (TAA) by immunization of a baboon with the purified glycoprotein antigen. The baboon serum was fractionated into IgG and IgM components by DEAE Affi-Gel blue chromatography. The ability of the baboon IgM anti-TAA antibody to effect tumor cell lysis in the presence of complement was tested using a chromium-release assay. The baboon antibody was able to lyse melanoma target cells (20.8%-71.4% cytolysis), breast carcinoma cells (36.5%-38.9% cytolysis), and a neuroblastoma cell line (35.5% cytolysis) in the presence of complement but did not effect significant lysis of autologous lymphoblastoid cell lines (4.9% cytolysis) or peripheral blood lymphocytes from healthy volunteers (12.6% cytolysis). Cytolysis of melanoma target cells was completely inhibited by preabsorption of the IgM anti-TAA antibody with UCLA-SO-M14 (M14) cells and partially inhibited by preabsorption with several other melanoma cell lines. There was no significant inhibition of tumor cell lysis after preabsorption of the antibody with lymphoblastoid cell lines. Complement-dependent lysis of M14 targets could be blocked by addition of the purified antigen to the antibody prior to incubation with the tumor cells. Our results suggest that the glycoprotein TAA resides on the tumor cell surface and that the baboon IgM anti-TAA antibody recognizes the antigen on the cell surface and is able to fix complement and effect the lysis of the tumor cells.

Animals↗
PubMed1992

Pharmacokinetics of temocapril hydrochloride, a novel angiotensin converting enzyme inhibitor, in renal insufficiency.

The pharmacokinetics of temocapril hydrochloride, a novel prodrug-type angiotensin-I converting enzyme (ACE) inhibitor, has been studied in patients with mild (Group II) to severe (Group III) renal insufficiency in comparison with subjects with normal renal function (Group I). The pharmacokinetic parameters of the active diacid metabolite, including Cmax, AUC and half-life (t1/2), showed only slight changes between the three groups: AUC (0-inaffinity) was significantly larger in Group III than Group I, and t1/2 tended to be prolonged in Group III, but the change was not significant. The urinary recovery of the diacid was significantly decreased in Group III. (Group I, 28.1%, Group II, 21.6%, Group III, 12.8%). Compared with other ACE inhibitors, which are mainly excreted through the kidney, the plasma concentration of the active diacid metabolite was hardly influenced by renal function. It was speculated that lowering of the dose of temocapril might be recommended only in patients with severe renal insufficiency.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1992

The divergent actions of volatile anaesthetics on background neuronal activity and reactive capability in the central nervous system in cats.

The effects of halothane, isoflurane, and enflurane on background neuronal activity and reactive capability in the central nervous system were studied in cats. The background neuronal activity was assessed by midbrain reticular cell firing, which was measured by the method of multi-unit activity, and the EEG in the cortex, amygdala, and hippocampus. The reactive capability was assessed by evoked responses in the visual neuronal pathway. All anaesthetics studied suppressed reticular cell firing in a dose-dependent manner, and the suppression by halothane (43.8 +/- 10.3% of control, mean +/- SD) was less than isoflurane (66.5 +/- 5.8%, P < 0.01) and enflurane (73.1 +/- 8.8%, P < 0.05) at 1 MAC. Spontaneous EEG spikes developed at 4.8% isoflurane and 3.6% enflurane anaesthesia. Phasic activation of reticular cell firing was associated with EEG spikes during isoflurane and enflurane anaesthesia, and the activation during enflurane anaesthesia was greater than during isoflurane anaesthesia (P < 0.01). Photic stimulation provoked EEG spikes and repetitive stimulation induced seizure activity only at 3.6% enflurane anaesthesia. Halothane and isoflurane suppressed stimulation induced responses in the visual neuronal pathway. The amplitudes of N1 in visual cortical evoked responses induced by photic stimulation were suppressed to 70.1 +/- 24.5% of control at 2.4% halothane and 39.3 +/- 27.3% at 4.8% isoflurane. Enflurane, at 3.6%, augmented the evoked response induced by photic stimulation (398.4 +/- 83.0% of control in the amplitude of N1). These results indicate that all the agents studied had suppressive actions on background neuronal activity in the order halothane < isoflurane = enflurane. The effects on reactive capability were divergent among agents, e.g., enflurane enhanced, halothane suppressed, and the actions of isoflurane were intermediate. We conclude that the anaesthetic effects on background activity and on reactive capability are divergent and that suppression of reactive capability is a factor in determining the ease of clinical application of the anaesthetics.

Amygdala↗
PubMed1992

Intraventricular infusion of leupeptin decreases Bmax of the D2 receptor in the striatum of young rats.

Intraventricular infusion of a thiol protease inhibitor, leupeptin, was previously shown to induce several morphological and immunochemical manifestations of normal and pathological aging in rat brain. The present study attempted to elucidate whether this treatment also perturbs another brain function which declines in aging, dopamine D2 receptor binding in striatum. Intraventricular infusion of leupeptin (0.6 mg per day) for two weeks caused a significant (about 20%) reduction in the binding maximum (Bmax) of dopamine D2 receptors (as examined by [3H] spiperone binding) in the striatum of young male Fischer-344 rats in comparison to (saline-infused) control rats. The apparent Kd values did not differ significantly between the control and leupeptin-treated rat groups. The results suggest that decreased protein turnover may be a factor in the decline in Bmax of D2 receptors during aging.

Animals↗
PubMed1992

Quantitation of cytomegalovirus DNA in lung tissue of bone marrow transplant recipients.

Five bone marrow transplant recipients who died of respiratory failure were retrospectively analyzed with polymerase chain reaction (PCR) assay for pulmonary cytomegalovirus (CMV) infection. Two patients had CMV interstitial pneumonitis according to the virus isolation and the histologic and immunofluorescent examinations of the lungs, while the other three patients had non-CMV diseases (ie, idiopathic interstitial pneumonitis, pulmonary aspergillosis, or Streptococcus mitis septicemia). Cytomegalovirus DNA was amplified from the postmortem lung tissue with PCR. The PCR assay showed apparent PCR signals specific to CMV DNA in the two patients with CMV pneumonitis. In contrast, CMV DNA was hardly detectable or undetectable in the three patients without CMV disease. With quantitative PCR assay the initial CMV copy number in the lung tissue of the two patients with CMV pneumonitis was more than 10(4) copies/micrograms DNA and was over 1,000-fold more than that of the three patients without CMV pneumonitis. These results show that quantitative PCR assay could be useful as a diagnostic measure for pulmonary CMV infection.

Adolescent↗
PubMed1992

Identification of a 64-kDa protein phosphorylated with glucose in human polymorphonuclear leukocytes in a cell-free system.

We previously reported that a 64-kDa protein (p64) in human polymorphonuclear leukocytes (PMN) was phosphorylated with [gamma-32P]ATP under a micromolar concentration of glucose in a cell-free system. The present paper presents the results of analysis of phosphorylation reaction and the identification of phosphoprotein. The findings that p64 was also phosphorylated with glucose-6-[32P]phosphate and that phosphorylation was inhibited with mannoheptulose suggested that the reaction was mediated by hexokinase. In fact, it was found that [32P]phosphate in glucose-6-[32P]phosphate was incorporated into either p64 or rabbit muscle phosphoglucomutase and that glucose-6-phosphate formation from glucose and ATP was detected in over 100-kDa fraction of PMN cytosol. These results showed that p64 was phosphoglucomutase in PMN and that phosphate incorporation into p64 was a conversion of a phosphate group in glucose-6-phosphate produced by hexokinase. It was further demonstrated by analysis of two-dimensional electrophoresis that p64 phosphorylated with glucose induction was different from another 64-kDa protein phosphorylated by stimulation with formyl-methionyl-leucyl-phenylalanine in vivo.

Cell-Free System↗