Biomedical subjects
Publications and source records attributed to C Sato.
Hepatitis C virus populations in infected individuals consist of quasispecies with diverse mutations. These quasispecies have different biological properties, and the analysis of these variants has led to new interpretations of viral persistence, carcinogenesis and resistance to interferon therapy.
Hepatocyte growth factor/scatter factor (HGF/SF) and keratinocyte growth factor (KGF, also designated FGF-7) are paracrine growth factors secreted by mesenchymal cells and active on a variety of epithelial cell types. In this study, the biologic responses of keratinocytes to these paracrine growth factors were compared. Stimulation of mitogenesis, migration, plasminogen activator (PA) activity, and fibronectin production were examined using human foreskin keratinocytes cultured in serum-free MCDB 153 medium. Although the two factors stimulated a similar level of proliferation when cells were maintained for 5 d in 1.8 mM Ca++, the peak effect of KGF, observed at 10 ng/ml, was approximately threefold higher than that of HGF/SF when cells were in medium containing 0.15 mM Ca++. Both agents promoted the migration of cells in low-calcium medium (0.08 mM Ca++). However, the magnitude of the response was approximately twofold greater for HGF/SF at 10 ng/ml than KGF at the same concentration. None of the matrix proteins such as type I collagen, type IV collagen, laminin, or fibronectin either stimulated or suppressed HGF/SF- or KGF-stimulated keratinocyte migration. Both factors stimulated PA activity of the cell extracts, especially urokinase-type, with similar potencies. Promoted PA activity was maximal with the addition of 10 ng/ml of either factor. Neither factor increased the production of fibronectin under conditions in which transforming growth factor-beta 1 was active. These results indicate that HGF/SF and KGF, both recognized as paracrine growth factors, elicit distinctive patterns of response by keratinocytes, implying that they have different roles in epidermal physiology.
The stimulatory effect of recombinant human insulin-like growth factor-I (rhIGF-I) and recombinant human insulin-like growth-factor-binding protein-1 (rhIGFBP-1) on wound healing was assessed using diabetic db/db mice and normal rabbits. Full-thickness wounds of 6 mm diameter were prepared on the backs of diabetic C57BL/KsJ db/db mice and on the inner sides of normal rabbit ears. Various concentrations of rhIGF-I and/or rhIGFBP-1 were applied locally to the open wounds of db/db mice once daily for 5 d and to the covered wounds of normal rabbits once after wounding. Sections of the wounds were evaluated histologically on the seventh or eighth day by measuring re-epithelialization (%), area of granulation tissue (mm2), and capillary numbers. Wound repair was accelerated by each of the treatments in descending order of rhIGF-I plus rhIGFBP-1, rhIGF-I, rhIGFBP-1, and vehicle alone. In db/db mice, the combination of 50 micrograms rhIGF-I and 165 micrograms rhIGFBP-1 (equimolar ratio) significantly stimulated granulation tissue formation (p < 0.01) and capillary numbers (p < 0.05). Doses of rhIGFBP-1 greater than 16.5 micrograms were required for significant acceleration of the healing stimulated by 50 micrograms of rhIGF-I. In normal rabbits, co-administration of 10 micrograms rhIGF-I and 33 micrograms rhIGFBP-1 (equimolar ratio) significantly stimulated all three wound-healing parameters (p < 0.01), with such stimulation being much greater than that induced by rhIGF-I alone. Interestingly, rhIGFBP-1 alone showed a mild stimulatory activity on wound healing in both models despite its lack of mitogenic activity in vitro. These results demonstrate that rhIGFBP-1 enhances the stimulatory activity of rhIGF-I on wound healing and suggest the clinical utility of the co-administration of rhIGF-I and rhIGFBP-1 for wound repair.
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.
A rare case of gastric carcinoma associated with increased serum variant alkaline phosphatase activities is presented. A 54 year old man had extremely high serum alkaline phosphatase activity (18,607 U/l) with normal calcium and phosphate concentrations. His bone scintigram showed abnormal findings, 'super bone scan'. He was diagnosed as having Borrmann type 4 gastric carcinoma with diffuse bone metastases by examinations of the upper gastrointestinal tract and iliac bone biopsy. The alkaline phosphatase isozyme of this patient was of the bone type as measured by cellulose acetate membrane electrophoresis and the placenta/bone type by agarose gel electrophoresis, respectively. Immunoelectrophoresis and the immunoprecipitation method using monoclonal antibodies against various alkaline phosphatase isozymes, however, showed that his serum alkaline phosphatase had the liver type antigenicity. Furthermore, it had a larger molecular size and different sugar chains compared with the common liver type alkaline phosphatase. These findings suggest that a unique variant alkaline phosphatase was produced by gastric cancer cells, which is possibly an explanation for the high serum alkaline phosphatase activities in this patient.
We investigated the influence of lactosucrose on the intestinal flora of healthy volunteers. Eight healthy volunteers (male:female = 4:4, age 34 +/- 4 years) received 6 g of lactosucrose daily for 8 weeks. Fecal microflora, bacterial metabolites, pH, and moisture were analyzed before and after the administration of lactosucrose. The results showed that the number and percentage of Bifidobacterium sp. in relation to the total bacteria significantly increased during the period of lactosucrose administration. Although fecal putrefactive products, fatty acids, pH, moisture content, and stool volume did not show significant changes during the test period, the amount of fecal phenol showed a negative correlation with the number of Bifidobacterium sp. Fecal ammonia significantly decreased after 4 and 8 weeks of lactosucrose administration, and 1 week after the end of lactosucrose administration, compared with results after a 1-week administration of lactosucrose. When the administration was stopped, the percentage of Bifidobacterium sp. in relation to the total count gradually decreased to the same level as before the administration of lactosucrose. These results suggest that under physiological conditions, lactosucrose acts on the intestinal microflora as a growth factor of Bifidobacterium sp.
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.
To investigate the recent prevalence of human alveolar echinococcosis in Hokkaido, we took advantage of Western blotting analysis capable of classifying persons infected with Echinococcus multilocularis into two groups: the complete and incomplete types. From the geographic distribution, the residents with the complete type appeared for the first time in 1992 in the Oshima district (western Hokkaido). The age distribution indicated that persons with the complete type increased, since 1990, in the age groups younger than 30 years old.
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)
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.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
To investigate the role of nitric oxide in renal function and hemodynamics in cirrhotic patients with ascites, L-arginine (30 g in 300 mL of distilled water), a substrate for nitric oxide synthase, was infused into six cirrhotic patients with ascites, and the effects were compared with those of saline infusion. Healthy controls (n = 5) were also studied under the same conditions. In the patients, L-arginine infusion significantly decreased systolic and diastolic blood pressures while markedly increasing urinary flow and urinary sodium excretion; no significant changes were seen with saline infusion. In controls, only diastolic blood pressure was decreased by L-arginine infusion, whereas urinary flow and urinary sodium excretion were increased by both L-arginine and saline infusion. In both groups, a similar increase of plasma atrial natriuretic factor (ANF) was seen with L-arginine and saline infusions; endothelin and catecholamines were not affected by either infusion. In both groups, plasma levels of vasopressin were increased by L-arginine infusion. In the cirrhotic patients, urinary excretions of cyclic guanosine monophosphate (cGMP) and nitrates/nitrites (NOx) were significantly increased by L-arginine infusion, whereas no significant changes were seen with saline infusion. In controls, only the excretion of cGMP was increased by L-arginine infusion. In summary, L-arginine infusion induces diuresis and natriuresis accompanied by increased excretions of cGMP and NOx in cirrhotic patients with ascites. This differs from the response in controls, where the increase in urinary sodium excretion is not accompanied by an increase in markers of increased nitric oxide synthesis.
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.
Two patients with acute liver dysfunction who were negative for serum IgM-HA antibody on presentation became positive a week later. At early stages of hepatitis A, serum IgM-HA antibody may be negative. Another assay approximately 2 wk apart is recommended.
Effects of verapamil, an calcium channel blocker, on hepatic glutathione were studied in vivo in the rat and in the perfused rat liver. An injection of verapamil at a dose of 15 mg/kg body weight but not at 5 mg/kg significantly decreased hepatic glutathione contents in both fed and fasted animals 6 h after the injection. The administration of verapamil at a dose of 10 mg/kg twice a day for a week brought a significant decrease in hepatic glutathione contents and a significant increase in plasma glutathione levels. In the perfused rat liver, sinusoidal glutathione efflux was significantly increased when verapamil was added to the perfusion medium in a concentration of 20 microM. These data indicate that verapamil increases glutathione efflux from the liver and that calcium mobilization may be concerned in glutathione efflux in vivo.