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Biomedical subjects

M Kaito

Publications and source records attributed to M Kaito.

At least 19 recordsLinked to original sources
PubMed2001

Recovery of infectious human parainfluenza type 2 virus from cDNA clones and properties of the defective virus without V-specific cysteine-rich domain.

A full-length cDNA clone was constructed from the genome of the human parainfluenza type 2 virus (hPIV2). First, Vero cells were infected with recombinant vaccinia virus expressing T7 RNA polymerase, and then the plasmid encoding the antigenome sequence was transfected into Vero cells together with polymerase unit plasmids, NP, P, and L, which were under control of the T7 polymerase promoter. Subsequently, the transfected cells were cocultured with fresh Vero cells. Rescue of recombinant hPIV2 (rPIV2) from cDNA clone was demonstrated by finding the introduced genetic tag. As an application of reverse genetics, we introduced one nucleotide change (UCU to ACU) to immediate downstream of the RNA-editing site of the V gene in the full-length hPIV2 cDNA and were able to obtain infectious viruses [rPIV2V(-)] from the cDNA. The rPIV2V(-) possessed a defective V protein that did not have the unique cysteine-rich domain in its carboxyl terminus (the V-protein-specific domain). The rPIV2V(-) showed no growth in CV-1 and FL cells. Replication of the rPIV2V(-) in these cells, however, was partially recovered by adding anti-interferon (IFN)-beta antibody into the culture medium, showing that the rPIV2V(-) is highly sensitive against IFN and that no growth of rPIV2V(-) in CV-1 and FL cells is mainly due to its hypersensitivity to endogenously produced IFN. These findings indicate that the V-protein-specific domain of hPIV2 is related to IFN resistance. On the other hand, the rPIV2V(-) efficiently replicated in Vero cells, which are known as a IFN-non-producers. However, the virus yields of rPIV2V(-) in Vero cells were 10- to100-fold lower than those of control rPIV2, although syntheses of the viral-specific proteins and their mRNAs in rPIV2V(-)-infected Vero cells were augmented up to 48 p.i. in comparison with those of rPIV2. Furthermore, the rPIV2V(-) virions showed anomalous in size as compared with rPIV2 virions. These results suggest that the V protein plays an important role in the hPIV2 assembly, maturation, and morphogenesis.

Animals↗
PubMed2001

Induction of virus-specific cytotoxic T lymphocytes by in vivo electric administration of peptides.

Generally, major histocompatibility complex (MHC) class I presentation of peptide antigens only occur for proteins' which are actively synthesized and processed intracellularly, so that immunization with a cytotoxic T lymphocyte (CTL) target peptide does not usually elicit effective CTL responses. In the present study, we explored the use of epitope peptides by in vivo electroporation to introduce directly into the cytoplasm for the vaccine elicitation of virus-specific CTLs in a mouse system. BALB/c mice were immunized with human immunodeficiency virus (HIV) env (P18, residues 311-320) or hepatitis C virus (HCV) NS5 (P17, residues 2423-2434) with or without electric pulses. Effector cells against peptide-labeled target cells were elicited in mice immunized with peptides with electric administration but not without electric administration. Moreover, cytolytic activities of CTL against peptide-labeled target cells were enhanced by the addition of plasmid having the immunostimulatory sequence (ISS) or cDNA of the B7-1 molecule in electric administration of peptides. The results of the present study suggest that a peptide vaccine against a virus using electric administration is effective in eliciting virus specific CTLs.

Amino Acid Sequence↗
PubMed2001

Hepatitis C virus core particle detected by immunoelectron microscopy and optical rotation technique.

Hepatitis C Virus (HCV) are 55-65 nm spherical particles, but the internal structure of the virion remains to be clarified. To clarify the morphology of HCV core particles, we performed an immune electron microscopy (IEM) using plasma samples from two blood donors with high HCV RNA titers and a detergent-treated anti-HCV core antibody-free plasma sample with high HCV RNA titer (1.5x10(8) copies/ml). Spherical particles, with 33-40 nm in diameter (an average diameter of 37 nm) were found in 1.22-1.25 g/ml fractions after sucrose density gradient centrifugation by conventional electron microscopy (EM). IEM using rabbit polyclonal antibody (RR8) specific to the putative HCV core protein and goat anti-rabbit IgG colloidal gold particles revealed that these spherical particles specifically reacted with RR8. This finding indicates that the spherical particles are naked HCV core particles. Some of the HCV core particles had an icosahedron-like structure. Optical rotation technique showed that the HCV core particle exhibits six-fold symmetry and that the length of regular hexagon side is approximately 20 nm. These findings showed that HCV core particles are spherical particles of 33-40 nm in diameter and that HCV core particles may possess an icosahedron-like structure and a buoyant density of 1.22-1.25 g/ml.

Journal Article↗
PubMed2001

Role of UGT1A1 mutation in fasting hyperbilirubinemia.

BACKGROUND AND AIM: Low-grade fasting hyperbilirubinemia is a common observation in healthy subjects (HS), whereas high-grade fasting hyperbilirubinemia is believed to be a characteristic finding of Gilbert's syndrome. This study was undertaken to assess the role of mutation in bilirubin UDP- glycosyltransferase gene (UGT1A1) on fasting hyperbilirubinemia. METHODS: Analysis of UGT1A1 and a caloric restriction test (400 kcal for 24 h) were performed in 56 healthy subjects (25 males, 31 females), and 28 patients with Gilbert's syndrome (18 males, 10 females). There were 29 healthy subjects with no mutation in UGT1A1, and 27 healthy subjects and 26 Gilbert's syndrome patients with mutations in the coding and/or promoter (TATA box) regions of UGT1A1. RESULTS: The mean increment of serum bilirubin (DeltaSB) was 7.6 micromol/L [corrected] (males) and 4.1 micromol/L (females) in subjects with no UGT1A1 mutation. Subjects with mutation in UGT1A1 showed higher levels of DeltaSB than individuals without mutation. Among healthy subjects, gender difference in DeltaSB values was observed only in individuals with the wild type of UGT1A1, but not in those with mutations in this gene. CONCLUSION: The results of the present study suggest that UGT1A1 mutation has a role in the development of high-grade fasting hyperbilirubinemia after caloric restriction.

Adult↗
PubMed2001

Paraformaldehyde protects of hepatitis C virus particles during ultracentrifugation.

Divergent buoyant densities of hepatitis C virus (HCV) have been reported. If the destruction of HCV particles occurs during the ultracentrifugation process to separate fractions with different densities, an accurate evaluation of the HCV buoyant density is difficult. To examine this concern, changes were examined in HCV RNA titer of each density fraction after paraformaldehyde fixation of virus particles in the sera of 9 patients with chronic HCV infection. Serum was treated with 4% paraformaldehyde, and the density fractions were then separated by ultracentrifugation. The HCV RNA titer of each fraction was determined by reverse transcription-polymerase chain reaction (RT-PCR) assay, and the results were compared with those obtained from the serum without paraformaldehyde fixation. After fixation, the HCV RNA titer was significantly increased in the 1.11-1.14 g/mL fraction (P=0.0018), and decreased in the 1.14-1.17 and 1.17-1.20 g/mL fractions (P=0.0457 and 0.0003, respectively). Using immunogold electron microscopy, it was found that morphologically destroyed HCV particles are present mainly in the 1.17 g/mL fraction of paraformaldehyde-untreated samples, whereas the intact HCV virion particles are present in the 1.12 and 1.14 g/mL fractions of the paraformaldehyde-treated samples. These results suggest that the destruction of HCV virions occurs during the ultracentrifugation process and that paraformaldehyde treatment protects from destruction. It was also considered that the accurate buoyant density of the HCV virion is 1.11-1.14 g/mL. This study describes a useful method for the purification of HCV virions, and provides new insights for elucidating the physicochemical properties of HCV particles.

Adult↗
PubMed2000

Induction of hepatitis C virus-specific cytotoxic T lymphocytes in mice by an intrahepatic inoculation with an expression plasmid.

We assessed the possibility of intrahepatic inoculation with a plasmid encoding hepatitis C virus (HCV) proteins to elicit HCV-specific cytotoxic T lymphocytes (CTL) in mice as a conventional animal model of HCV infection. BALB/c mice were intrahepatically or intramuscularly inoculated with an expression plasmid DNA encoding HCV structural proteins under the control of the elongation factor 1-alpha promoter. Expressions of HCV-core protein and envelope proteins (E1 and E2) in hepatocytes were detected immunohistochemically 6 days after inoculation. CTL responses were examined using target cells either pulsed with a specific peptide or infected with a recombinant vaccinia virus expressing HCV structural protein. Both intrahepatically and intramuscularly DNA-inoculated mice developed CD8(+), MHC class I-restricted CTL responses that recognized the peptide pulsed as well as HCV proteins expressing target cells. These studies demonstrated the usefulness of a murine model of HCV infection induced by direct intrahepatic DNA inoculation for understanding the immunopathogenic mechanisms in HCV infection.

Animals↗
PubMed2000

Biliary excretion of TT virus (TTV).

A novel DNA virus (TT virus; TTV) was isolated from a patient with post-transfusion hepatitis of unknown etiology. If TTV replicates in the liver, TTV may appear in the bile. In the present study, to clarify whether fecal-oral infection occur via biliary excretion, the presence of TTV DNA was assessed in paired serum and bile samples collected from 28 patients with obstructive jaundice without parenchymal liver disease. TTV DNA was detected by polymerase chain reaction (PCR) using semi-nested primers, and quantified by Real Time Detection PCR (RTD-PCR). The nucleotide sequence of isolates TTV DNAs was also determined and the sequences were compared between serum and bile samples. Among 28 patients, 7 were positive for TTV DNA in both samples, and 3 and 2 were positive in serum and bile respectively. Of 7 patients positive for TTV DNA in both samples, the TTV DNA titer was higher in serum of 4 patients and in bile of 1 patient. Among 7 patients positive for TTV DNA in serum and bile, 6 had the same sequence in both samples. Multiple distinct types of TTV DNA clones were isolated from serum in 2 patients and from bile in 4 patients. In conclusion, TTV DNA is detected frequently in bile from patients with obstructive jaundice, suggesting a fecal-oral route of infection and high prevalence of asymptomatic TTV carriers. TTV DNA was detected only in serum from some patients, suggesting that replication of TTV may occur in other organs as well as in the liver.

Aged↗
PubMed2000

Ineffective interferon treatment of chronic hepatitis C-associated porphyria cutanea tarda, but with a transient decrease in HCV RNA levels.

Many patients with porphyria cutanea tarda (PCT) have been reported to be hepatitis C virus (HCV) carriers, suggesting that HCV infection plays a role in the pathogenesis of this type of porphyria. In this study, we report a patient with chronic hepatitis C-associated PCT. Therapy with interferon (IFN) transiently decreased HCV RNA levels, but levels of urinary porphyrins and serum transaminases and ferritin remained unchanged. Serum ferritin and urinary porphyrin levels improved after phlebotomy, but this therapy was not effective in improving serum transaminase levels. Although a physiopathological association between HCV infection and PCT has been suggested previously, IFN was not effective in this patient. The transient decrease in HCV RNA levels was a factor independent of porphyrin metabolism.

Aged↗
PubMed2000

Decrease of regional cerebral blood flow in liver cirrhosis.

OBJECTIVE: Alterations of regional cerebral blood flow (rCBF) in subjects with liver cirrhosis have not been fully evaluated. We evaluated quantitative changes in rCBF using single photon emission computed tomography (SPECT). METHODS: Twenty-eight Japanese patients with liver cirrhosis were enrolled in this study. None of them exhibited advanced hepatic encephalopathy at the time of examination. The cause of liver cirrhosis was viral infection in 26 patients; the cause was unknown in two patients. Child-Pugh classification of the patients was as follows: Group A, 12 patients; Group B, 12 patients; and Group C, four patients. The control group consisted of 25 age-matched healthy subjects. Radionuclide angiography was performed by rapid injection of Tc-99m ethyl cysteinate dimer (ECD) (740 MBq) via the right cubital vein, and then SPECT brain images were taken. Using the Patlak graphical method, rCBF values (ml/100 g per min) were calculated in the frontal, parietal, temporal and occipital lobes and cerebellum on SPECT images. RESULTS: The rCBF values were lower in cirrhotic patients than in controls, i.e. by 15% in the frontal lobe, by 12% in the parietal lobe, by 10% in the temporal and occipital lobes, and by 7% in the cerebellum. They decreased concomitantly with the severity of liver disease. A significant negative correlation was noted between rCBF values and Child-Pugh score in the frontal (P<0.01), parietal (P<0.05) and occipital lobes (P<0.01). rCBF values of each region were not correlated with age or with results of neuropsychological test. The degree of association between rCBF values and results of laboratory examination was generally poor. CONCLUSION: Patients with liver cirrhosis without advanced encephalopathy showed widespread reduction in rCBF; this reduction was particularly evident in the frontal lobe. Tc-99m ECD SPECT may be useful for evaluating cerebral functional changes in patients with liver cirrhosis.

Brain↗
PubMed2000

Novel assay for measuring serum conjugated bilirubin and its clinical relevance.

We have developed a new enzymatic assay for the determination of conjugated bilirubin (Bc) using stable liquid reagents. In this assay, only Bc is selectively oxidized by bilirubin oxidase at pH 5. 0 in the presence of nitrilotris (methylenephosphonic acid) trisodium salt, ethylenediaminetetraacetic acid disodium manganese (II) salt, and 4-hydroxy-2,2,6,6,-tetramethylpiperidine 1-oxyl. Bc is quantitatively determined from a decrease in the absorbance at 450 nm caused by Bc oxidization. The reagent solutions of the assay were developed so that they could be stably stored for one year together with bilirubin oxidase, in order to eliminate the need to prepare working solutions every time they are required. The assay has good reactivity, differentiability, measurability, and precision. Neither ascorbic acid nor hemoglobin interfered with the measurement. Bc values determined by the assay reflected more clearly the pathophysiological condition of hepatobiliary disease patients with jaundice than the values of total bilirubin or direct bilirubin determined by conventional methods. From these observations, we concluded that this Bc assay is valuable for the evaluation of jaundice.

Bilirubin↗
PubMed1999

High prevalence of transfusion-transmitted virus among patients with non-B, non-C hepatocellular carcinoma.

BACKGROUND: Many patients with hepatocellular carcinoma are positive for hepatitis B surface antigen (HBsAg) or antibodies to hepatitis C virus (anti-HCV). Recently, transfusion-transmitted virus (TTV) DNA was identified in the serum of patients with non-B, non-C posttransfusion hepatitis. In this study, the prevalence of TTV DNA in the serum of patients with non-B, non-C hepatitis-associated hepatocellular carcinoma was evaluated. METHODS: Fifteen patients with hepatocellular carcinoma negative for HBsAg, antibodies to hepatitis B core antigen (anti-HBc), and anti-HCV antibodies were enrolled in this study (non-B, non-C group). Fifteen patients positive for HBsAg and negative for anti-HCV antibody (HBV group) and another group of patients negative for HBsAg but positive for anti-HCV antibody (HCV group) were also enrolled in this study. Data obtained from 27 healthy subjects negative for both HBsAg and anti-HCV antibody and normal levels of serum alanine aminotransferase represented controls. The healthy control group, the non-B, non-C group, and the HCV group were age-matched. TTV DNA was detected by heminested polymerase chain reaction in which specific primers were used. RESULTS: TTV DNA was detected in 10 of 15 patients (67%) in the non-B, non-C group. This prevalence rate in the non-B, non-C group was significantly higher than that in the HBV group (3 of 15 patients, 20%) and the control group (9 of 27 patients, 33%), but it was not significantly different from that in the HCV group (7 of 15 patients, 47%). The noncancerous hepatic tissue samples of 10 TTV-DNA positive patients in the non-B, non-C group included 2 with chronic hepatitis and 8 with cirrhosis. CONCLUSIONS: This study showed that TTV DNA is frequently detected in the serum of patients with non-B, non-C hepatocellular carcinoma. This result suggests a potential pathogenetic association between hepatocellular carcinoma and TTV infection.

Aged↗
PubMed1999

Induction of apoptotic cell death in human hepatocellular carcinoma SK-HEP-1 cells by a polyamine synthesis inhibitor, methylglyoxal bis(cyclopentylamidinohydrazone).

The antitumor effects of a polyamine biosynthetic pathway inhibitor methylglyoxal bis(cyclopentylamidinohydrazone) (MGBCP) on the human hepatocellular carcinoma SK-HEP-1 cell line have been investigated. The growth of these cultured hepatocellular carcinoma cells was inhibited by MGBCP in a dose-dependent manner. Spermidine and spermine levels were dose-dependently depressed, and morphological changes due to programmed cell death (apoptosis) were observed in these MGBCP-treated hepatocellular carcinoma cells. These results suggest that in addition to reducing the growth rates, MGBCP can induce apoptotic cell death in this human hepatocellular carcinoma cell line.

Antineoplastic Agents↗
PubMed1999

Helper T cell determinant peptide contributes to induction of cellular immune responses by peptide vaccines against hepatitis C virus.

The capacity of novel subunit vaccines to generate cytotoxic T lymphocytes (CTLs) against hepatitis C virus (HCV) was assessed. BALB/c mice were immunized with peptides based on the CTL and helper T cell (Th) epitopes of the HCV core, with a mixture of CTL and Th peptides (CTL+Th) or with a conjugated Th-CTL peptide. Mice immunized with CTL, CTL+Th and Th-CTL peptides, but not those immunized with Th peptide, developed HCV core CTL epitope-specific effector cells. Cytotoxic activity induced by immunization with Th-CTL was much higher than that induced by immunization with CTL+Th or CTL alone. However, rapid and high cytotoxic activities against HCV core were not only detected after immunization with peptides containing the CTL epitope but also as a result of infection with recombinant vaccinia virus carrying the HCV core gene after immunization with the Th epitope alone. Immunization with peptides containing the Th epitope also elicited spleen cell proliferation. This study demonstrates the capacity of both Th and CTL activated peptide vaccines to elicit CD8+, MHC class I-restricted CTLs. The capacity of such CTLs to contribute towards a protective and/or pathogenic immune response against HCV can now be assessed in mouse models.

Amino Acid Sequence↗
PubMed1999

Evaluating response to nutritional therapy using the branched-chain amino acid/tyrosine ratio in patients with chronic liver disease.

The branched-chain amino acid (BCAA)/tyrosine (Tyr) ratio (BTR) recently has been reported to be a good indicator of the severity of hepatic parenchymal injury in patients with chronic liver disease. In the present study, sequential changes of BTR after BCAA administration were determined in patients with chronic liver disease to evaluate the value of BTR as a marker of the clinical response to nutritional therapy in these patients. This study comprised 75 patients with chronic hepatitis and 96 with liver cirrhosis. BTR was significantly decreased in patients with cirrhosis and hepatitis compared with healthy subjects. BTR was significantly correlated with the Child-Pugh score and with other liver function tests. BCAA increased significantly 2 hr after BCAA administration and decreased gradually thereafter. Tyr significantly decreased 4 hr after BCAA administration. BTR significantly increased 2 and 4 hr after BCAA therapy. The increase in BTR 3 hr after BCAA administration was low in patients with decreased basal BTR. The results of this study showed that BTR is a good index of the hepatic parenchymal damage and that it may be a useful marker for monitoring response to nutritional therapy in patients with chronic liver disease.

Amino Acids, Branched-Chain↗
PubMed1998

Case report: Alanine aminotransferase deficiency detected in a patient with chronic hepatitis C.

We report a case of alanine aminotransferase (ALT) deficiency in a 68-year-old Japanese female with chronic hepatitis C. The serum was positive for antibody to hepatitis C virus (HCV) and HCV-RNA. Liver biopsy showed histological evidence of chronic active hepatitis. The level of serum aspartate aminotransferase (sAST) was elevated, but sALT was extremely low. The patient was followed up for her serum aminotransferase levels for 1.5 years under the treatment with ursodeoxycholic acid. The low sALT level persisted during all the follow-up period. The ALT activity in liver tissue was also decreased. Based on these findings, ALT deficiency was suspected. sALT activity was also found to be low in her two sons. This latter finding suggests the hereditary character of this abnormality.

Adult↗