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Biomedical subjects

T Kamada

Publications and source records attributed to T Kamada.

At least 415 records · Page 23Linked to original sources
PubMed1992

Detection of the minus strand of hepatitis C virus RNA by reverse transcription and polymerase chain reaction: implications for hepatitis C virus replication in infected tissue.

The combination of reverse transcription and polymerase chain reaction is a very powerful tool for the detection of hepatitis C virus RNA in sera of patients with hepatitis C virus infection. However, when studying the presence of this virus in tissue using polymerase chain reaction, it may be difficult to distinguish between blood viral particles adhering to the tissue and viral RNA contained within the tissue. Because hepatitis C virus has a single-stranded RNA of positive polarity, a minus-strand RNA is expected to be found in hepatitis C virus-replicating tissues as a template for the synthesis of genomic RNA. To see whether the detection of the minus strand of hepatitis C virus RNA by polymerase chain reaction can be used for the determination of hepatitis C virus-replicating tissues, we examined the presence of the minus strand of hepatitis C virus RNA in the plasma, peripheral blood mononuclear cells and liver specimens of patients with hepatitis C virus infection. The plus-strand RNA was detected in the plasma, peripheral blood mononuclear cells and the liver specimens, but the minus-strand RNA was only detected in the liver. These results suggest that hepatitis C virus replicates in the liver but not in peripheral blood mononuclear cells. This detection method for the minus strand of hepatitis C virus RNA should be useful for determining hepatitis C virus replication in tissues other than liver tissue.

Adult↗
PubMed1992

Intracellular calcium as a second messenger for human hepatocyte growth factor in hepatocytes.

Human hepatocyte growth factor is a newly discovered substance that stimulates DNA synthesis in vitro. In this study, we examined intracellular Ca2+ movement as one of the second messengers for human hepatocyte growth factor in primary-cultured hepatocytes. The addition of hHGF induced Ca2+ oscillation, but the frequency of oscillations varied from cell to cell. We also saw marked intercellular heterogeneity in the initial latent period for the Ca2+ response; the mean latent period was rather longer than those seen with phenylephrine and vasopressin. This difference in the initial latent period may be due to the difference in the pathways of Ca2+ elevation. Duration of culture determined the number of human hepatocyte growth factor-responsive cells; their number peaked at 2 to 5 hours of confluent culture, whereas the peak was earlier in a low-density culture. These changes in responsiveness during culture can be explained by the cell cycle-dependent sensitivity to human hepatocyte growth factor of hepatocytes. The Ca2+ response to human hepatocyte growth factor was dose dependent; 10(-10) mol/L hHGF gave the highest Ca2+ response, similar to the dose-response curve of DNA synthesis. We even observed the Ca2+ response in the Ca(2+)-free buffer, so the increase in Ca2+ was considered due to release from intracellular Ca2+ stores. These results suggest that human hepatocyte growth factor causes the intracellular Ca2+ elevation in the early stage of the cell cycle and that it plays important roles in the signal transduction systems for human hepatocyte growth factor and the proliferation of hepatocytes.

Animals↗
PubMed1992

Immunohistochemical detection of hepatitis C virus-infected hepatocytes in chronic liver disease with monoclonal antibodies to core, envelope and NS3 regions of the hepatitis C virus genome.

The localization of hepatitis C virus-infected hepatocytes in the human liver remains unclear despite the development of a serological assay for the antibody to hepatitis C virus. We studied their localization immunohistochemically with monoclonal antibodies to core, envelope and NS3 antigens of hepatitis C virus. We examined 48 liver biopsy samples from C100-3 antibody-positive patients with chronic liver disease (chronic persistent hepatitis, 5 cases; chronic active hepatitis, 41 cases; cirrhosis, 2 cases) and 12 liver biopsy samples from C100-3 antibody-negative patients with chronic liver disease (type B chronic hepatitis, 8 cases; alcoholic liver disease, 4 cases). In the C100-3 antibody-positive group, positive immunostaining for core antigen, envelope antigen and NS3 antigen was found in 23% (11 of 48), 24% (11 of 45) and 24% (11 of 46), respectively. Negative results were obtained in the C100-3 antibody-negative group. Hepatocytes with positive staining were scattered in the lobules, and they were found in the same regions irrespective of whether the antibody to core antigen, to envelope antigen or to NS3 antigen was used. Each positive cell was strongly stained in the cytoplasm; these decorations disappeared after absorption of the primary antibody with purified antigen. mean ALT levels in the patients with positive immunostaining for core, envelope or NS3 antigen (174.8 +/- 105.7 U/L) tended to be higher than in those with negative immunostaining (142.0 +/- 93.8 U/L). On histological evaluation of liver specimens with a scoring system of the histological activity index, intralobular inflammation and fibrosis had higher scores for samples with positive rather than negative immunostaining (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

Epidermal growth factor induces dose-dependent calcium oscillations in single fura-2-loaded hepatocytes.

Digital imaging fluorescence microscopy has been used to investigate epidermal growth factor-induced calcium responses of fura-2-loaded hepatocytes in primary culture at the single-cell level. Epidermal growth factor induced oscillations in cytosolic free calcium ([Ca2+]i) consisting of a periodic train of spikes unlike the monophasic elevation in cell suspensions reported previously. In this study, 79% of the cells in the microscopic field responded to 0.1 nmol/L epidermal growth factor, and 78% of the responsive cells displayed oscillations. However, the frequency of oscillations differed considerably from cell to cell. [Ca2+]i measurement in a cell population was simulated using these data, but only a slightly biphasic pattern was obtained, indicating the significance of single-cell measurement of [Ca2+]i. Because considerable heterogeneity existed in the sensitivity to epidermal growth factor between the cells, single hepatocytes were stimulated sequentially with increasing concentrations of epidermal growth factor to investigate the dose dependence of the oscillations. The frequency of the oscillations increased with increasing epidermal growth factor concentration, but the amplitude was similar for all concentrations, suggesting the existence of frequency-encoded information even in the pathway through tyrosine kinase for epidermal growth factor signaling. The pattern of the oscillations with epidermal growth factor, especially the latency, was considerably different from that with phenylephrine, which is known to use the phosphatidylinositol pathway, possibly because of the difference in the pathway toward phosphatidylinositol turnover between these agonists.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Tumor necrosis factor and endotoxin in the pathogenesis of liver and pulmonary injuries after orthotopic liver transplantation in the rat.

This study examines whether tumor necrosis factor and endotoxin are involved in the pathogenesis of primary nonfunction of graft and pulmonary complication after orthotopic liver transplantation. Livers from Lewis rats were stored for either 1 or 4 hr in ice-cold Euro-Collins solution (1-hr storage and 4-hr storage group, respectively). Subsequently, donor livers were implanted orthotopically. In some experiments, anti-tumor necrosis factor antibody was administered intravenously before and immediately after the surgery into animals that received livers stored for 4 hr. Blood samples for the measurement of tumor necrosis factor and endotoxin were collected by way of an indwelling catheter placed in the suprahepatic vena cava. Serum tumor necrosis factor was elevated at all time points studied postoperatively in rats of the 4-hr storage group; however, tumor necrosis factor was not detected in the serum in the 1-hr storage group. Endotoxin was also elevated significantly in the serum of the former group compared with levels in the serum of the latter group. The peak value of endotoxin occurred 1 hr earlier than that of tumor necrosis factor, suggesting that the rise in endotoxin stimulated release of tumor necrosis factor. The histological study of livers stored for 4 hr showed substantial hepatocellular degeneration 24 hr after surgery, whereas hepatocellular damage was minimal in the 1-hr storage group. Serum ALT levels 24 hr after the operation in the 1-hr and 4-hr storage groups were 169 +/- 46 IU/L and 374 +/- 41 IU/L (mean +/- S.E.M., p less than 0.05), respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Alanine Transaminase↗
PubMed1992

Improved serodiagnosis of chronic hepatitis C in Japan by a second-generation enzyme-linked immunosorbent assay.

To clarify the role of hepatitis C virus (HCV) infection in chronic liver disease, sera from Japanese patients which were negative by the original anti-HCV assay (Ortho) were subjected to a second-generation anti-HCV assay based on a combination of structural (C22) and nonstructural (C200) recombinant HCV proteins. Of 29 patients with chronic non-A, non-B hepatitis, 20 (69%) were anti-HCV-positive by the second-generation enzyme-linked immunosorbent assay (ELISA) and also positive by the reverse transcription-polymerase chain reaction (RT-PCR) which detects the HCV genome. Of 41 chronic hepatitis B virus carriers, 3 (7%) were positive by the second-generation ELISA; 1 of 3 was positive by RT-PCR. The HCV genome was detected in all cases positive for anti-HCV with high titers. Of 59 healthy subjects negative by the second-generation ELISA, none were positive by RT-PCR. These findings indicate that HCV is a major causative agent of chronic non-A, non-B hepatitis in Japan and that second-generation ELISA is specific and a more sensitive diagnostic assay for chronic hepatitis C.

Base Sequence↗
PubMed1992

Antibodies to a putative hepatitis C virus polyprotein in Japanese patients with chronic liver disease.

To investigate the frequency of exposure to hepatitis C virus (HCV) in chronic liver disease, sera from Japanese patients were tested with the original anti-HCV assay (Ortho) and an anti-HCV assay based on synthetic peptides corresponding to a variety of regions in the HCV genome. Thirty-one (67%) of 46 patients with chronic non-A,non-B hepatitis were anti-HCV-positive by the Ortho ELISA, 20 of whom were also positive by ELISA based on synthetic HCV peptides. Eight (53%) of the 15 patients negative by the Ortho ELISA tested positive for anti-HCV by ELISA based on HCV peptides. Serum HCV RNA was detected in all cases positive for antibody to the HCV peptide and in 14 (78%) of 18 cases without antibody. Thirty-seven hepatitis B virus carriers were without anti-HCV by the Ortho ELISA and were negative for serum HCV RNA, six (16%) of whom were positive by ELISA based on HCV peptides. Antibody responses were directed against each synthetic HCV peptide used, with a considerable difference in incidence, indicating possible expression of the corresponding region in the course of HCV propagation. These findings indicate that exposure to HCV may be more common than expected based on the results of the Ortho ELISA.

Amino Acid Sequence↗
PubMed1992

Assessment of portosystemic shunting from superior mesenteric vein by duodenal administration of iodoamphetamine I123.

Portosystemic shunting (PSS) from the superior mesenteric vein (SMV) was evaluated with the duodenal administration of iodoamphetamine I123 (IMP) in patients with chronic hepatitis and liver cirrhosis. After duodenal intubation, IMP was administered through a tube, and then scintigraphy including the pulmonary and hepatic regions was performed. In all patients, images of the liver and/or lungs were observed within 10 min and became clear with time, due to a good absorption of IMP from the intestine. On the other hand, IMP appears not to be absorbed from the stomach. The portosystemic shunt index was calculated by dividing counts of lungs by counts of liver and lungs. The shunt index (mean +/- SE) was 1.5% +/- 0.8%, 12.6% +/- 3.7% and 28.3% +/- 4.5% in chronic hepatitis, compensated cirrhosis and decompensated cirrhosis, respectively. This index was significantly higher in cirrhosis, especially in decompensated cirrhosis. Therefore, transintestinal portal scintigraphy with IMP could be a useful method for the non-invasive and quantitative evaluation of PSS from the SMV in portal hypertension.

Amphetamines↗
PubMed1992

The characteristics of blood-brain barrier in three different conditions--infarction, selective neuronal death and selective loss of presynaptic terminals--following cerebral ischemia.

We investigated the extravasation of serum albumin using immunohistochemistry in three different conditions, i.e., infarction, selective neuronal death and selective loss of presynaptic terminals following cerebral ischemia in gerbils. In selective neuronal death, which is typically found in the CA1 neurons of the hippocampus after 5-min bilateral cerebral ischemia, selective damage of postsynaptic components with intact presynaptic sites was demonstrated by immunohistochemical examination for microtubule-associated protein 2 and synapsin I, and albumin extravasation did not become apparent before postsynaptic structures were destroyed. In cerebral infarction, which was consistently observed in the thalamus after 15-min forebrain ischemia, massive albumin extravasation was visible early after ischemia due probably to the ischemic endothelial necrosis. In selective loss of presynaptic terminals, which was detected at the molecular layer of the dentate gyrus in the contralateral, nonischemic hippocampus after unilateral cerebral ischemia, immunoreaction for albumin was not visualized. Since endothelium and glial cells were intact in morphological aspects in selective damage of both pre- and postsynaptic sites, it was thought that extravasation was facilitated by the stimulation of endothelial cells and glial cells with unknown factors that were induced by the destruction of post- but not presynaptic elements.

Albumins↗
PubMed1992

Effects of alpha-interferon on gamma-interferon production of peripheral blood mononuclear cells in hepatitis B virus carriers.

We studied gamma-interferon production of phytohemagglutinin-stimulated peripheral blood mononuclear cells in response to alpha-interferon in hepatitis B virus carriers and healthy individuals. The magnitude of gamma-interferon production was significantly higher in patients with anti-HBe antibody than in patients with HBe antigen and healthy individuals. Furthermore, alpha-interferon augmented the production of gamma-interferon of peripheral blood mononuclear cells from patients with active liver injury [serum alanine aminotransferase (ALT), greater than 40 U/L], but not that from patients with inactive liver injury (serum ALT, less than 40 U/L) or healthy individuals. These results suggested that alpha-interferon could enhance the cellular immune response against hepatitis B virus by augmenting the endogenous production of gamma-interferon in patients with active liver injury, implying that the responsiveness to alpha-interferon might be responsible for liver cell injury.

Adult↗
PubMed1992

HCV RNA and antibody to HCV core protein in Japanese patients with chronic liver disease.

We evaluated the prevalence of hepatitis C virus (HCV) RNA and antibody (anti-HCVcore) to the putative HCV core protein in Japanese patients with chronic liver disease. Sera were screened by solid-phase enzyme immunoassay with a recombinant HCV core protein and by the reverse transcription-polymerase chain reaction (RT-PCR) test which directly detects the HCV genome. Anti-HCV core was detected with high titers in 95% (69/73) of chronic non-A, non-B hepatitis, and 94% (65/69) of anti-HCVcore-positive patients had the genome. Anti-HCVcore was also found with lower titers in 24% (10/41) of chronic hepatitis B virus carriers, and three of them had the genome. Only one (3%) of the 35 patients negative for anti-HCVcore tested positive to RT-PCR. These findings indicate the overwhelming prevalence of HCV infection in Japanese patients with chronic non-A, non-B hepatitis and a close relationship between the presence of anti-HCVcore and chronic hepatitis C in this population.

Adult↗
PubMed1992

Three cases of posttransfusion hepatitis C treated with interferon-alpha. Confirmation of a carrier state by detection of hepatitis C virus RNA after interferon therapy.

Interferon therapy is useful for decreasing the serum ALT level and improving liver histology in patients with chronic non-A, non-B hepatitis. This study examined the effect of interferon therapy in acute cases of posttransfusion hepatitis C. We report on three cases in which interferon alpha was administered at 100-220.5 million units. HCV RNA became undetectable during interferon administration and the ALT level declined to the normal range. However, after the cessation of the therapy, the ALT level began to fluctuate and HCV RNA reappeared in two patients. We concluded that interferon therapy for the acute phase of posttransfusion hepatitis is useful for suppressing viral replication and quickly improving the ALT level, but it can not always prevent the development of chronic hepatitis. Furthermore, there was a close correlation between the profile of HCV RNA and that of the ALT level, indicating that the replication of HCV plays an important role in liver injury.

Adult↗
PubMed1992

Hepatitis B virus markers and antibodies to hepatitis C virus in Japanese patients with hepatocellular carcinoma.

Sera from Japanese patients with chronic liver disease were tested for hepatitis B virus (HBV) markers and antibodies to hepatitis C virus (anti-HCV), and the results were correlated to the presence of hepatocellular carcinoma. In chronic non-A, non-B liver disease, anti-HCV prevalence was high both in patients with hepatocellular carcinoma (78/89, 88%) and without it (66/84, 79%), while previous HBV infection was more common in patients with hepatocellular carcinoma (65/89, 73%) than in those without it (46/84, 55%) (P less than 0.05). Coexistence of anti-HCV and antibodies to HBV was observed frequently in patients with hepatocellular carcinoma (56/89, 63%) compared with patients without it (39/84, 46%) (P less than 0.05). In chronic HBV carriers, anti-HCV was more common in patients with hepatocellular carcinoma (12/38, 32%) than in those without it (3/62, 5%) (P less than 0.01). These results suggest that infection with the two viruses may be a risk factor for more serious liver disease.

Aged↗
PubMed1992

Predominant beta-adrenoceptor blocking effect of xamoterol averaged over the day in patients with mild to moderate heart failure: insight into the mechanism of its long-term clinical efficacy.

Xamoterol acts as a beta 1-adrenoceptor agonist at low sympathetic activity and as an antagonist at high activity. Although its long-term efficacy has been proven in patients with mild to moderate heart failure, it remains unclear which effect, agonism or antagonism, accounts for its long-term activity. To clarify the effect of xamoterol on cardiac sympathetic activity in daily life, 24-h R-R interval histograms were obtained during administration of xamoterol 100 mg b.d. for 1 week to 10 patients with mild to moderate heart failure. Eight normal subjects were also studied as controls. To examine the relation between the effect of xamoterol and sympathetic activity, plasma noradrenaline (NA) levels were measured under 5 graded conditions simulating daily living. Xamoterol administration significantly decreased the standard deviation of the R-R interval, both in patients with heart failure and in normal subjects. The mean R-R interval, however, was increased in patients with heart failure, relative to normal subjects. In both groups, the R-R interval histograms had two peaks, i.e. a short daytime peak and a long night-time peak. Xamoterol decreased the median of the night-time peak without changing the daytime peak in normal subjects. In contrast, it increased the median of the daytime peak without producing a significant change in the night-time peak in patients with heart failure. Levels of plasma NA were significantly higher in patients than in normal subjects under all conditions.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic beta-Antagonists↗
PubMed1992

Changes in erythrocyte membrane fluidity by endotoxin in rats.

The effect of endotoxin on fluidity and lipid composition of the erythrocyte membrane was studied in rats following the intraperitoneal administration of endotoxin (30 mg.kg(-1) body weight). Erythrocyte membrane fluidity measured with 16-stearic acid spin label (16-SAL) was significantly decreased in the endotoxin-treated rats as compared with control. A decrease of lysophosphatidylcholine in the membrane lipid was evident in the endotoxin-treated rats. The cholesterol to phospholipid molar ratios and other phospholipid fractions did not differ significantly in the two groups. The levels of plasma Beta-glucuronidase activity and lipoperoxide were significantly increased in the endotoxin-treated rats when compared to controls. There were significant correlations between the parameter of 16-SAL in erythrocytes and plasma Beta-glucuronidase activities or lipoperoxide from both endotoxin-treated and control groups, P < 0.005 or P < 0.02 respectively. In conclusion endotoxin decreased rat erythrocyte membrane fluidity in vivo. Since membrane fluidity is closely related to the vital functions of the membranes, the change described could be related to the abnormality of cell membrane functions in endotoxin shock state.

Journal Article↗
PubMed1992

Temporal increase in resting coronary blood flow causes an impairment of coronary flow reserve after coronary angioplasty.

Impaired coronary flow reserve immediately after coronary angioplasty may be attributed to an increase in resting coronary blood flow. To test this hypothesis we measured great cardiac venous flow (GCVF) at rest and during rapid atrial pacing before and immediately after angioplasty in 22 patients with significant narrowing of the left anterior descending artery and 12 patients (control group) with minimal narrowing. A follow-up (6 months) study was also done in seven patients. Immediately after angioplasty the coronary flow reserve (peak GCVF during pacing/resting GCVF) was not fully restored (1.5 +/- 0.36 before angioplasty, 1.76 +/- 0.42 after angioplasty, and 2.13 +/- 0.33 in the control group). Resting coronary vascular resistance (2.4 +/- 0.9 mm Hg/ml/min) was significantly decreased after angioplasty (2.0 +/- 0.8 mm Hg/ml/min), whereas coronary vascular resistance during rapid pacing was fully restored to normal. Resting hyperemia was restored 6 months later, whereas coronary vascular resistance during pacing was unaltered. In five patients, however, slight ischemic ST-T changes were observed during rapid pacing, even after successful angioplasty associated with a decrease in the lactate extraction ratio. These results indicate that the impaired coronary flow reserve immediately after angioplasty may be attributed mainly to the temporal but significant increase in resting coronary flow, although impaired coronary vascular response to augmented myocardial oxygen demand may also be partially involved.

Aged↗
PubMed1992

Analysis of pulmonary venous flow velocity patterns in hypertensive hearts: its complementary value in the interpretation of mitral flow velocity patterns.

Although the Doppler mitral flow velocity pattern changes in accordance with the degree of left ventricular diastolic dysfunction, it is "normalized" in the presence of heart failure. In this study the pulmonary venous flow velocity pattern was characterized in 43 hypertensive patients with and without heart failure to clarify whether analysis of the pulmonary venous flow velocity pattern provides complementary information in the interpretation of the mitral flow velocity pattern. The mitral flow velocity pattern in 32 hypertensive patients without heart failure was characterized by decreases in the peak early diastolic filling velocity (E) and the ratio of E to peak filling velocity at atrial contraction. The mitral flow velocity pattern was "normalized" in 11 patients with heart failure, with no differences in any mitral flow velocity pattern indexes as compared with 24 normal subjects. The pulmonary venous flow velocity pattern in hypertensive patients without heart failure was characterized by a decreased peak diastolic forward flow velocity (D) and an increased ratio of peak systolic forward flow velocity (S) to D (S/D ratio). In patients with heart failure, D was higher and the S/D ratio was lower compared with hypertensive patients without heart failure (p less than 0.01, p less than 0.01) and normal subjects (p less than 0.01, p less than 0.01). Thus the pulmonary venous flow velocity pattern appeared to be more reliable than the mitral flow velocity pattern in differentiating subgroups of patients with hypertension. Analysis of the pulmonary venous flow velocity pattern in conjunction with the mitral flow velocity pattern provides important and complementary information in the interpretation of the mitral flow velocity pattern in hypertensive patients with and without heart failure.

Blood Flow Velocity↗