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C Kurihara

Publications and source records attributed to C Kurihara.

At least 19 recordsLinked to original sources
PubMed2001

Changes of DNA titer and sequence variance of TT virus in hepatic disorders.

TT virus (TTV) has been reported to occur in association with elevated alanine aminotransferase (ALT) levels in patients with posttransfusion hepatitis of unknown etiology. We examined whether the presence, change of DNA titer, or variation in sequence of this virus is associated with acute or chronic liver dysfunction in Japanese. We detected TTV by polymerase chain reaction (PCR) using primers generated from the conserved region of the TTV genome. Direct DNA sequencing of the original N22 region was used to characterize TTV isolates. We detected TTV DNA in 15 (25%) of 60 patients with liver dysfunction. Variants recovered from infected patients formed four genotypes/subtypes, corresponding to G1a, G1b, G2, and G4. Although TTV DNA titers in patients with G2 and G4 were lower than those with G1, TTV was consistently detected regardless of genotype/subtype. TTV infection continued for at least 1 year after normalization of ALT level in patients with acute liver dysfunction. Changes in DNA titer, substitutions of deduced amino acids, and variety of quasispecies of TTV were detected during the observation period, but no significant fluctuation in ALT level was found. We conclude that persistent infection, changes in DNA titer, and variation in sequence of this novel virus are not significantly related to hepatic disorders.

Journal Article↗
PubMed2001

Molecular characterization of hepatitis C virus genotype 2a from the entire sequences of four isolates.

Genotype 2a hepatitis C virus (HCV) has different characteristics from genotype 1b, such as responsiveness to interferon therapy. Such type-specific characteristics appear to be due to differences in the HCV genome sequence. The complete sequences of genotype 2a HCV genome isolated from four patients with chronic hepatitis C were determined, and nucleotide and deduced amino acid sequences were compared within genotype 2a, as well as between genotype 2a and 1b. Whereas the amino acid sequence similarity of the core region was highest within genotype 1b, the NS3 and NS4B regions of exhibited greater similarity than the core region in genotype 2a. The serine protease and helicase motifs in the NS3 region were well conserved in genotype 2a to the same degree as in genotype 1b. However, the putative secondary structure of 2a isolates was significantly different from that of the 1b isolates. Analysis of amino acid similarity between genotypes 2a and 1b revealed the lowest degree of similarity in the E1 region, followed by the NS2 and NS5A region. Sequences of genotype 2a in the interferon-sensitivity determining region (ISDR) located in the NS5A region had a deletion of four amino acids compared with that of genotype 1b. When the ISDR of the genotype 2a was aligned for maximal similarity, it exhibited similarity of only 52.5-55.0% when compared with that of HCV-J, which belongs to genotype 1b. These findings for the entire sequences of genotype 2a isolates will contribute to virological studies of HCV.

Amino Acid Sequence↗
PubMed1999

[The association of TTV genetic variant with liver disease].

TT virus (TTV), a novel DNA virus, has been reported in non-A to non-G posttransfusion hepatitis patients. Among 61 Japanese patients with liver diseases of non-B and non-C etiology, TTV DNA was detected in 15(25%) patients. The N22 region of TTV was sequenced and compared with the published sequence. Four genetic groups corresponding to G1a, G1b, G2 and G4 were formed. TTV was detected persistently regardless of its genotype/subtype. However, G2 and G4 contained 10 to 100 folds lower in titer than G1. Co-existing multiple mutants and subtypes were identified in one case. Since changes of TTV DNA titer and appearance of deduced amino acid substitution was not linked to ALT levels, the association of TTV to chronic liver diseases seemed low.

Amino Acid Sequence↗
PubMed1998

Full-length GBV-C/HGV genomes from nine Japanese isolates: characterization by comparative analyses.

The genomes of nine GBV-C/HGV isolates from Japanese chronic hepatitis patients were fully sequenced and characterized. They shared 85% nucleotide sequence homology with previously characterized isolates from the US and West Africa. Homology studies and phylogenetic analyses showed that the Japanese isolates formed a third group distinct from the established groups 1 and 2. The genetic distances between the three groups of GBV-C/HGV were very similar to the distances between the two classical swine fever virus (CSFV) serotypes, which suggested that they might belong to a separate GBV-C/HGV serotype. Plot similarity analysis comparing the three groups exposed relatively conserved terminal non-coding regions. Hairpin structures predicted in the Japanese isolates are probably involved in viral replication. The region coding E1-E2-NS-2 showed the least similarity (80%); in HCV the similarity here is only 50% due to its hypervariability. NS-3 and NS-5b that respectively encode the helicase/protease and RNA-dependent RNA polymerase, had a high degree of amino acid homology, suggesting a high degree of functional constraint in this region. The NS-5b nucleotide sequence was highly conserved perhaps because of constraints from RNA secondary structure and/or an open reading frame in the negative strand.

Base Sequence↗
PubMed1998

Multicyclic reverse transcription-polymerase chain reaction assay system for quantification of GB virus-C/hepatitis G virus RNA in serum.

A new quantitative reverse transcription-polymerase chain reaction (RT-PCR) method is described for analyzing the amount of GB virus-C (GBV-C)/hepatitis G virus (HGV) RNA in serum. This multicyclic RT-PCR (MRT-PCR) method used oligonucleotide primers deduced from the 3' noncoding region (3'NCR) that is highly conserved among GBV-C/HGV isolates. Quantitation of GBV-C/HGV RNA using MRT-PCR ranged between 10(2) and 10(10) copies/ml when PCR cycle number was regulated at exponential amplification of the products. Competitive RT-PCR (CRT-PCR) was carried out with mutant RNA and sample that had been measured by MRT-PCR. Quantitation of GBV-C/HGV RNA using both methods agreed. MRT-PCR detected viral RNA in a single step PCR, and demonstrated a high degree of sensitivity that was equal to that of the RT-PCR procedure, which used nested primers deduced from the non-structural (NS) 3 region. The MRT-PCR method for quantitation of GBV-C/HGV RNA in serum may prove useful for diagnosis.

DNA Primers↗
PubMed1997

New variant groups identified from HGV isolates.

We have determined the primary sequence of the 5' noncoding region (5' NCR) and putative helicase regions (NS-3) of hepatitis G virus (HGV) and GB virus C (GBV-C) that were isolated in Japan from suspected cases of nonA-nonB and/or nonA-nonB-nonC viral hepatitis by using RT-PCR, and we compared the newly isolated sequences with three established isolates. The addition of a "G" residue was found at the 5' terminus of all 8 Japanese isolates. These isolates were more clearly distinguished from the prototype viruses by comparison with the 5' NCR sequence than by comparison with the NS-3 region. Our results suggested that at least three distinct genomic variants of HGV exist. Genotyping of HGV by using RT-PCR based on the sequence of the 5' NCR seems highly feasible.

Base Sequence↗
PubMed1997

The sequence element of the internal ribosome entry site and a 25-kilodalton cellular protein contribute to efficient internal initiation of translation of hepatitis C virus RNA.

Translation of hepatitis C virus (HCV) RNA is initiated by internal entry of ribosomes into the 5' noncoding region (NCR). This process depends on genomic elements within the 5' NCR called the internal ribosome entry site (IRES) and may involve host factors. The alpha-branch structure (nucleotides 47 to 67) of the HCV IRES is considered a cis-acting element critical for translation initiation because it is indispensable for translation in vitro (S. Fukushi, K. Katayama, C. Kurihara, N. Ishiyama, F. B. Hoshino, T. Ando, and A. Oya, Biochem. Biophys. Res. Commun. 199:425-432, 1994). In order to further characterize the function of the alpha-branch, we determined whether sequence exchange within the alpha-branch had any effect on translation initiation. An in vitro translation study revealed that the stem sequences of this region played an important role in efficient IRES function. In addition to several HeLa cell proteins, which had a binding affinity for the 5' NCR, a novel 25-kDa protein that specifically interacted with the HCV IRES was discovered. The binding affinity of the 25-kDa protein for the 5' NCR was correlated with the efficiency of translation initiation of HCV RNA, indicating a critical role for the 25-kDa protein in HCV translation.

Animals↗
PubMed1996

Nucleotide sequence of the 5' noncoding region of hepatitis G virus isolated from Japanese patients: comparison with reported isolates.

The nucleotide sequences of the 5' noncoding region (NCR) of hepatitis G virus (HGV) from sera of Japanese patients were determined. Among these isolates, there was a high degree (> 96.9%) of sequence identity, whereas identity with previously reported GB virus-C or HGV strains was low (> 87.0%). Phylogenetic analyses showed that the HGV strains from Japanese patients clustered in groups distantly separated from previously reported strains. Among the Japanese HGV isolates, the genetic distances corresponded to subtype differences observed within hepatitis C virus (HCV) isolates, whereas the differences between the Japanese isolates and the prototypes corresponded to genetic distances observed between HCV genotypes. The Japanese HGV isolates found in this study should be placed in a new genotype distinct from previously described isolates.

Base Sequence↗
PubMed1995

Characterization of the hog cholera virus 5' terminus.

Hog cholera virus (HoCV) 5' terminus of the ALD and GPE(-) strains were analyzed by using rapid amplification of cDNA end method (5'RACE). An additional nine nucleotides were found at the 5' termini of genomic RNA in the ALD and GPE(-) strains of HoCV. These nine nucleotides were also conserved in BVDV and were suggested to form a hairpin structure at the 5' terminus by computer-assisted analysis. It seems possible that the secondary structure and/or the 5' terminus sequence has a significant role in the HoCV virus genome.

Animals↗
PubMed1994

Complete 5' noncoding region is necessary for the efficient internal initiation of hepatitis C virus RNA.

The mechanism of translational initiation by the 5' noncoding region (5'NCR) of hepatitis C virus (HCV) genome was analyzed. Using an in vitro translation system with artificial RNA containing a modified 5' NCR of HCV under the various KCl conditions, nucleotides (nt.) 62 to 341 of the HCV 5'NCR were not functional as an internal ribosome entry site (IRES). However, the full-length 5'NCR (nt. 1 to 341) produced an efficient internal initiation. To identify the essential region of the HCV-IRES, various mutants were produced in which stem-loops, predicted by secondary structure analysis of the HCV 5'NCR, were deleted. These constructs were analyzed by in vitro translation. Comparison of translation efficiency among these mutants suggested that the alpha- or both alpha- and beta-branches of domain II are essential for efficient translation. Moreover, the formation of correct secondary structure of IRES seems to be stabilized by the presence of domain I in 5'NCR. Furthermore, the uncapped 5'NCR of HCV promotes translation more efficiently than capped truncated 5'NCR constructs. Our results strongly suggested that complete 5'NCR containing all stem-loop structures is necessary for initiation by HCV-IRES.

Base Sequence↗
PubMed1994

[Factors determining the level of PaCO2 during laparoscopic cholecystectomy].

Factors responsible for the elevation of PaCO2 were investigated in 30 patients undergoing laparoscopic cholecystectomy using CO2 gas insufflation. Intraperitoneal insufflation of CO2 gas was performed to the level of 15 mmHg of intraperitoneal pressure in each patient and the following measurements were made: body height, body weight, body surface area (BSA), circumference of abdominal wall, obesity index, body mass index (BMI), operating time, total volume of insufflated CO2 gas, and change of peak inspiratory pressure. Rate of elevation of PaCO2 showed the highest correlation with BSA (correlation coefficient -0.691 [P < 0.01]) followed by body weight, body height, and circumference of abdominal wall. These results suggest that during laparoscopic cholecystectomy using CO2 gas insufflation, the degree of CO2 storage capacity has the highest effect on the elevation of PaCO2.

Adult↗
PubMed1990

[A rapid diagnosis for periodontitis based on enzymatic activity of periodontopathic bacteria. Correlation between enzymatic activity, clinical periodontal parameters, and subgingival level of microorganisms].

There have been various laboratory methods for the microbiological diagnosis of periodontal disease. However, there have been some disadvantages in these methods. In this study of the application of a chair-side test for microbiological diagnosis, the activity of peptidases in periodontal pockets of patients was examined by using the assay system SK-013. SK-013 consists of synthetic substrates and is capable of rapidly (in 15 min) evaluating the activity of specific peptidase from Treponema denticola and Bacteroides species. Using SK-013, we evaluate the correlation between the enzymatic activity, clinical periodontal parameters and subgingival level of microorganisms, including phase contrast microscopy. We calculated the sensitivity and efficacy of SK-013 as a diagnostic indicator in the presence of Spirochetes and in periodontitis. A positive correlation were demonstrated between enzymatic activity, clinical periodontal parameters, the numbers of total cell count, Spirochetes, and M & S ratio. SK-013 was highly sensitive and efficacious (sensitivity: 92%, efficacy: 96%). We concluded that the assay system SK-013 is a useful chair-side method for diagnosing periodontal disease.

Bacteroides↗
PubMed1990

[A rapid diagnosis for periodontitis based on the enzymatic activity of periodontopathic bacteria. The application of the SK-013 to the judgement on the effect of initial preparation].

The purpose of the present study was to examine the diagnostic value of the SK-013 (Sunstar, Osaka) in evaluating the effect of initial preparation. The SK-013 is a highly sensitive reagent to measure peptidase activity specifically produced by Bacteroides gingivalis. Bacteroides forsythus, and Treponema denticola. Thirty-six sites in 16 periodontitis patients were monitored in this study. The clinical status of each site was assessed using the clinical indices such as gingival index (GI), plaque index (PII), probing depth (PD), and bleeding on probing (BOP). The composition of subgingival microflora in samples was determined using phase contrast microscopy. Clinical, microbiological, and enzymatic examinations were made at five separate appointments, as follows: (1) at baseline prior to plaque control instruction; (2) 4 weeks following plaque control instruction; and (3) 2, 4, 8 weeks following scaling and root planing of periodontal sites. The results of these examinations were compared statistically. The correlation was positive between the total counts of bacteria including spirochetes and motile rods and the enzymatic activity identified using the SK-013. Also the enzymatic profile was highly correlated with microbiological findings other than clinical indices. These results show that the SK-013 is a clinically useful diagnostic method for assessing the effect of initial periodontal therapy.

Bacteroides↗
PubMed1989

[Research into actual conditions and preventive care in periodontal disease. Relationship between questionnaire results and periodontal disease in youth].

The purpose of this study was to determine the prevalence of periodontal disease and the relationship between the results of questionnaire concerning periodontal disease and the actual periodontal condition in youth. The examination was carried out in three parts. In the first part, a questionnaire was conducted on 3,886 junior and senior high school students (12 to 18 years of age) living in Kawagoe, Japan. The questionnaire was composed by of items concerning habits of oral hygiene, periodontal symptoms, understanding of periodontal disease and history of diagnosis by dentist of periodontal disease. Secondary, mass intraoral examination was carried out on all objects. The examination covered gingival inflammation, periodontal probing depth, calculus, dental plaque, dental caries and malalignment. Lastly, we examined the relationship between the results of periodontal examination and questionnaire with the original periodontal classification. The following results were obtained: 1. As an example of items in questionnaire, 83.1% brushed their teeth more than two times daily. The understanding of oral hygiene concerning dental caries was improved, but concerning periodontal disease was still poor. 2. The symptom most frequently reported was gingival bleeding during tooth brushing (18.4%). 3. The percentage of persons with periodontal disease (moderate gingival inflammation and periodontal pocket 4 mm or deeper) was of the highest frequency at 13 years old. The proportion of males increased with the advanced state of periodontal disease. 4. A significant correlation was found (chi 2-test: alpha less than 0.001) between advanced state of periodontal disease and a decrease in tooth brushing time per day. 5. A significant correlation was found between the advance of periodontal disease and gingival bleeding on tooth brushing (chi 2-test: alpha less than 0.001). Similarly, a correlation was found between the advance of periodontal disease and gingival swelling (chi 2-test: alpha less than 0.001). 6. A significant correlation was found (chi 2-test: alpha less than 0.001) between the advance of periodontal disease and aggravation of condition of dental plaque, calculus, dental caries and malalignment.

Adolescent↗