Search PubMed⌕ Search

Biomedical subjects

N Enomoto

Publications and source records attributed to N Enomoto.

At least 109 records · Page 6Linked to original sources
PubMed1995

Fraction-specific populations of the hypervariable region of the hepatitis C virus in a patient with cryoglobulinemia.

Nucleotide sequences of the hypervariable region (HVR) of the E2/NS1 gene of hepatitis C virus (HCV), which are now thought to contain epitopes for neutralizing antibodies, were compared between antibody-bound HCV and free HCV in a patient with type II cryoglobulinemia. Antibody-bound HCV was immunoprecipitated with anti-human immunoglobulins from serum of the patient. Total RNA was recovered from the pellet and the supernatant, respectively, and the envelope gene containing the HVR was amplified by the reverse transcription and nested polymerase chain reaction. The amplified cDNA was examined by the single strand conformation polymorphism (SSCP) analysis. Sequences of bands separated by SSCP analysis were determined by the dideoxy chain termination method. SSCP analyses revealed that the HCV populations were completely different between antibody-bound HCV and free HCV: antibody-bound HCV was composed of two bands and free HCV was composed of three bands. These five bands showed different mobility with each other on the SSCP gel. Sequencing of each band revealed distinct HVR sequences, differing in 1-34 nucleotides and 1-15 deduced amino acids. Three sequences of free HCV was similar with each other (1-5 nucleotide and 1-4 amino acid differences). On the other hand, two sequences of antibody-bound HCV had 5-34 nucleotide and 5-15 amino acid differences with free HCV. Thirteen amino acids in the 5' of HVR were completely identical in three sequences of free HCV, whereas there were three and seven amino acid differences in two sequences of antibody-bound HCV. These findings suggest that isolated specific epitopes for envelope antibodies exist within the HVR.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1995

Variations in the core region of hepatitis C virus genomes in patients with chronic hepatitis.

In each infected patient, the population of hepatitis C virus is composed of quasispecies that differ in their nucleotide sequences. Among regions in hepatitis C virus genomes, nucleotide sequences of the hypervariable region have been shown to change quickly during the course of infection. It is not known, however, whether these variations exist in the core region that has recently been suggested to contain human lymphocyte antigen class 1 restricted sites for cytotoxic T cell recognition. To clarify this, RNA was extracted from the plasma of four patients with chronic hepatitis C. After cDNA synthesis, DNA fragments that contain the core region were amplified by the polymerase chain reaction and the diversity of the core region was analyzed by the single strand conformation polymorphism analysis. Using this method, single or multiple DNA bands were observed in each patient, and representative bands showed different nucleotide sequences. Comparison of single strand conformation polymorphism patterns revealed that the population of quasispecies changed during the course of chronic infection. These changes were more remarkable in patients with high serum alanine aminotransferase levels than those with low serum alanine aminotransferase levels. Thus, sequential variations exist in the core region of hepatitis C virus in same individuals, and the population of quasispecies as determined by the sequence of the core region changes during the course of infection, which might be related to cytopathic effects of hepatitis C virus.

Alanine Transaminase↗
PubMed1995

Host dependent variation of hepatitis C virus: phylogenetic analyses.

Hepatitis C virus quasispecies in six patients from three families were separated by single strand conformation polymorphism analysis and by determination of nucleotide sequences of envelope regions containing the E1 gene segment and hypervariable region-1 of each quasispecies. Four of the six patients had multiple quasispecies. Phylogenetic analyses indicated that all quasispecies from one individual were highly homologous to each other. The homology was higher in the E1 gene segment than in hypervariable region-1. Furthermore, all quasispecies found in members of one family (husband and wife) were also highly homologous, suggesting direct intrafamilial transmission. The direction of hepatitis C virus variation in hypervariable region-1, however, seems to differ depending on the host in intrafamilial transmission.

Adolescent↗
PubMed1995

Detection and analysis of replicating hepatitis C virus RNA in hepatocellular carcinoma tissues.

Although persistent hepatitis C virus infection is closely associated with the development of hepatocellular carcinoma, the nature of hepatitis C virus replication in the hepatocellular carcinoma tissue has not been fully characterized. To study this, carcinoma and non-carcinoma tissues were obtained from five patients with hepatocellular carcinoma. Total RNA was recovered from each tissue, and a portion of the envelope gene of replicating hepatitis C virus was amplified by minus-strand-specific reverse transcription and nested polymerase chain reaction. The amplified cDNA was examined by single strand conformation polymorphism analysis and sequencing. Hepatitis C virus replication was detected in both carcinoma and non-carcinoma tissues in four patients who were positive for serum hepatitis C virus markers. In one patient, a single species with identical envelope 2 genome was obtained from both carcinoma and non-carcinoma tissues. In the other three patients, the replicating hepatitis C virus existed as a mixture of 2-5 species with different but highly homologous (82-99%) envelope 2 genomes (quasispecies populations). The constitution of viral populations was different between carcinoma and non-carcinoma tissues. A total of ten sequences were recovered; four sequences were found in both tissues, two were found in carcinoma tissues, and four were found in non-carcinoma tissues. The difference in the constitution of quasispecies populations between carcinoma and non-carcinoma tissues confirms the unequivocal replication of hepatitis C virus in both tissues, and may imply the presence of different biological properties among hepatitis C virus with different sequences.

Amino Acid Sequence↗
PubMed1995

Clinical relevance of hepatitis C virus quasispecies.

It has been shown that hepatitis C virus (HCV) populations in infected individuals are composed of quasispecies with diverse mutations. The analysis of these variants may reveal mechanisms of the persistence of HCV infection, carcinogenesis and resistance to antiviral therapy. Recently, genetic features of interferon-resistant HCV have been elucidated through the analysis of interferon-resistant quasispecies, making it possible to predict interferon efficacy by detecting interferon-resistant strains.

Amino Acid Sequence↗
PubMed1995

Comparison of full-length sequences of interferon-sensitive and resistant hepatitis C virus 1b. Sensitivity to interferon is conferred by amino acid substitutions in the NS5A region.

We have previously demonstrated that sensitivity to interferon is different among hepatitis C virus (HCV) quasispecies simultaneously detected in same individuals and that interferon-resistant HCV quasispecies are selected during the treatment. To determine the genetic basis of their resistance to interferon, HCV genotype-1b was obtained from serum of three patients before and during interferon therapy, and their full-length nucleotide and deduced amino acid sequences were determined. Comparison of the pairs of interferon-resistant and interferon-sensitive HCV isolates in respective individuals demonstrated clusters of amino acid differences in the COOH-terminal half of the NS5A region (codon 2154-2383), which contained a common unique amino acid difference at codon 2218. Additional sequence data of the COOH-terminal half of the NS5A region obtained from six interferon-resistant and nine interferon-sensitive HCV confirmed the exclusive existence of missense mutations in a 40 amino acid stretch of the NS5A region around codon 2218 (from codon 2209 to 2248) in interferon-sensitive HCV. On the other hand, this region of interferon-resistant HCV was identical to that of prototype HCV genotype-1b (HCV-J, HCV-JTa, or HC-J4). We designated this region as the interferon sensitivity determining region. Thus, HCV genotype-1b with the prototype interferon sensitivity determining region appears to be interferon-resistant strains. The specific nature of these mutations might make it possible to predict prognostic effects of interferon treatment.

Adult↗
PubMed1995

Increased gene expression of water channel in cirrhotic rat kidneys.

In patients with liver cirrhosis, impaired water and sodium excretion has been incriminated in the pathogenesis of ascites formation. Increased reabsorption of water in the distal nephron has been shown to play an important role in water retention in cirrhotic rat kidneys. Recently, a complementary DNA (cDNA) for the vasopressin-regulated water channel (the aquaporin of the apical membrane of the kidney collecting duct [AQP-CD]) has been cloned. It is suggested that AQP-CD plays an important role in renal water handling. Therefore, in the present study, to investigate the pathogenic role of the water channel in water retention in liver cirrhosis, gene expression of AQP-CD in the kidney was evaluated in cirrhotic rats. Liver cirrhosis was induced by an intraperitoneal administration of carbon tetrachloride twice a week for 12 weeks in 14 rats. Messenger RNA expression of AQP-CD in whole kidney homogenates determined by Northern blot hybridization was significantly increased in cirrhotic rats (147%; P < .01) and dehydrated rats (206%; P < .0001) compared with control rats. Protein expression of AQP-CD in the homogenates of kidney medulla determined by Western blot analysis was significantly increased in cirrhotic rats (203%; P < .03) compared with control rats. Furthermore, mRNA expression of AQP-CD in the kidney showed a significant correlation with the volume of ascites in cirrhotic rats (r = .62, P < .02). No significant difference was observed in water intake, urinary volume, serum osmolality, serum sodium, and creatinine clearance between control and cirrhotic rats, suggesting that dehydration was unlikely in cirrhotic rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Diversity of quasispecies in various disease stages of chronic hepatitis C virus infection and its significance in interferon treatment.

Hepatitis C virus (HCV) populations in vivo exist as a mixture of heterogeneous viruses called quasispecies, which have variations in the hypervariable region (HRV). However, the relationship between the diversity of HVR quasispecies, the disease stage, or the interferon (IFN) responsiveness remains to be elucidated. To study these, serum samples were obtained from 42 patients with chronic hepatitis C virus infection; 24 with chronic active hepatitis (CAH) treated with IFN, 9 with cirrhosis, 9 with hepatocellular carcinoma (HCC). HCV quasispecies populations were separated by the single-strand conformation polymorphism (SSCP) method targeted to the HVR. The patients were classified into two groups; a single-band group (n = 12) in which HVR quasispecies was homogeneous and a multiple-band group (n = 30) in which HVR quasispecies was heterogeneous. Patients with multiple bands had significantly more advanced liver disease than those with a single-band group (P = .0082). The percentage of patients with single band were 41% in CAH, 22% in cirrhosis, and 0% in HCC. Multivariate analyses showed that viral diversity was independently related to the progression of liver disease and was not correlated with the duration of infection. We also found that in CAH, the patients who had multiple bands (n = 14) were more resistant to IFN therapy than those who had a single band (n = 10) (P = .002). These results indicate that the diversity of HCV quasispecies becomes more complex as the disease stage progresses and that CAH with more complex diversity shows less IFN effectiveness.

Aged↗
PubMed1995

Limited usage of T-cell receptor beta chains and sequences of the complementarity determining region 3 of lymphocytes infiltrating in the liver of autoimmune hepatitis.

To study the role of antigen-specific T lymphocytes in the pathogenesis of autoimmune hepatitis, messenger RNA of T-cell receptors (TCR) was analyzed in liver biopsy specimens from four patients with autoimmune hepatitis. Using the TCR beta-chain variable region family specific oligonucleotides, a remarkable bias for the usage of beta-chain variable region 3 was detected in all four patients. Therefore, nucleotide and amino acid sequences of the complementarity-determining region 3 rearranged to the beta-chain variable region 3, which is a putative contact site for peptide fragments from antigens bound in the groove of the human leukocyte antigen molecule, was further analyzed in randomly selected 10 clones from each patient. An Asp-Arg-Pro motif in the complementarity-determining region 3 was identified in three of four patients with human leukocyte antigen DR4, and this motif was always rearranged to the beta-chain junctional region 1.2. From these results, beta-chain variable region 3+, Asp-Arg-Pro+, beta-chain junctional region 1.2+ T-cell clones may be among the responsible lymphocytes involved in the liver damage in autoimmune hepatitis, especially in patients with human leukocyte antigen DR4. Thus, an analysis of the complementarity-determining region 3 may give us an important clue to clarify characteristics of target antigens included in autoimmune hepatitis.

Adult↗
PubMed1995

[Reconstructive surgery for acquired mitral regurgitation].

Between December, 1967, and July, 1994, 96 patients underwent repair of the mitral valve for acquired mitral valve regurgitation. According to Carpentier's classification, mitral valve pathology resulting in valve regurgitation was classified into three types; 4 patients assigned to type I, 63 type II, and 29 type III. The operative mortality rate was 1.0%. Follow-up data were available in 95 patients from 0.5 year to 25.3 years (mean average 8.8 years). The late mortality rate were not different between patients with valve pathology of type I, II and those with valve pathology of type III. Thromboembolism occurred on three patients for an embolic rate of 0.4% per patient-years. Twenty-eight patients required reoperation for residual MR and dehiscence of suture lines (type II; 10 cases, reoperation-free rate at 20 years, 83.2%) or recurrent MR due to progression of valve deformity (type III, 18 cases, reoperation-free rate at 20 years, 14.8%). These results demonstrate that patients with type I and II valve are good candidates for MVP, and that high incidence of reoperation for recurrent MR may limit the application of MVP to selected patients with type III valve.

Adolescent↗
PubMed1995

[Use of inferior epigastric artery for coronary artery bypass grafting].

The usefulness of the free inferior epigastric artery (IEA) as a coronary bypass graft was studied. Among 149 patients for coronary bypass grafting (CABG) between October 1992 and December 1994, the free IEA was used in 12 patients. The mean number of distal anastomosis was 3.7 per patient. The mean distal size of the IEA was 1.3 mm in diameter and the mean length was 9.4 cm. The IEA graft was anastomosed to the obtuse marginal branch in 5, to the diagonal branch in 4, and the right ventricular branch in 3. The proximal anastomosis of the IEA was constructed to the ascending aorta in three and to the saphenous vein (SVG) or to the internal thoracic artery (ITA) in 4 or 5, respectively. Postoperative angiogram demonstrated patent graft in ten and occluded graft in two in whom the size of IEA was less than 1.0 mm in distal diameter and the IEA was anastomosed to the aorta or to the SVG. The IEA was considered to be useful alternative arterial graft when it was used as "interposed graft" of which proximal anastomosis was made to the ITA and size-matching of the graft to the coronary artery was appropriate. The long-term patency of the graft can determine the true efficacy of the IEA for CABG.

Aged↗
PubMed1994

Evolution and selection of hepatitis C virus variants in patients with chronic hepatitis C.

It has been shown that hepatitis C virus (HCV) populations in vivo are composed of different but highly homologous HCV genomes (quasispecies) as shown in the hypervariable region (HVR) that exists in the N-terminal of the envelope 2 gene of HCV, and that the predominant sequence of the HVR of HCV genomes changes rapidly over time. To further investigate genetic backgrounds of the change in the HVR of HCV genomes, 45 plasma samples serially obtained from nine patients with chronic hepatitis C were studied using population-based analyses. Total RNA was recovered and the envelope gene containing the HVR was amplified by the reverse transcription and nested polymerase chain reaction. The amplified cDNA was examined by the single strand conformation polymorphism (SSCP) analysis. Furthermore, 43 HCV sequences, separated by the SSCP analysis from three patients were determined by the dideoxy chain termination method, and the phylogenetic analysis was performed using the neighbor joining method. The SSCP analysis demonstrated that HCV population within each individual were composed of 1 to 6 quasispecies. These quasispecies populations in vivo changed sequentially in eight of nine patients. Gradual selections of coexisting quasispecies were observed over 6- to 18-month periods in three patients, whereas complete replacements of previous quasispecies by new quasispecies were repeatedly observed over few-month intervals in five patients. The phylogenetic analysis on these quasispecies revealed the continuous accumulation of mutations in two patients and discontinuous appearance of evolutionarily distant quasispecies in one patient. These results indicate that HCV genomes in vivo form quasispecies populations, and that these quasispecies populations change during the natural course of chronic infection. Genetic mechanisms underlining the change of the HVR of HCV genome appear to be either continuous accumulation of mutations or selective overgrowth of preexisting minor variants from the large spectrum of quasispecies populations.

Aged↗