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Biomedical subjects

K Shiraki

Publications and source records attributed to K Shiraki.

At least 37 records · Page 2Linked to original sources
PubMed2001

Hepatocyte growth factor promotes epithelial morphogenesis and occludin linkage to the cytoskeleton in cultured retinal pigment epithelial cells.

BACKGROUND: Although hepatocyte growth factor (HGF) is also known as scatter factor, it induces epithelial morphogenesis in cultured bovine retinal pigment epithelial (RPE) cells. To elucidate the mechanism of epithelial morphogenesis, we investigated the influence of HGF on occludin, a major component of tight junctions. METHODS: RPE cells were plated on collagen type 1-coated chamber slides or dishes, 20 ng/ml HGF was added and the cells were incubated for 1 week. Cells were harvested at several time-points, and occludin expression was examined by immunohistochemistry. Detergent extraction protocols to identify the intensity of occludin linkage to the cytoskeleton were also used. Occludin expression was determined semiquantitatively by Western blotting. RESULTS: Fluorescence microscopy revealed that HGF treatment increased the levels of insoluble occludin at the cell borders after detergent extraction. These level of insoluble occludin and the associated epithelial morphology were maintained for more than 3 weeks after withdrawal of HGF, whereas cells not treated with HGF had a fibroblastic appearance. Western blotting also showed that insoluble occludin was more abundant in HGF-treated cells. Furthermore, immunoreactive bands of insoluble occludin were somewhat larger than those of soluble occludin, suggesting that insoluble occludin may be modified in comparison to soluble occludin. CONCLUSION: Our results suggest that HGF promotes linkage of occludin to the cytoskeleton. HGF may become a therapeutic candidate in physiological recovery of RPE cells and in preparation of RPE monolayers for transplantation.

Animals↗
PubMed2001

Water drinking causes a biphasic change in blood composition in humans.

To investigate precisely the fluid shifts associated with water drinking in humans, we measured continuously blood density and plasma electrolyte concentrations using the mechanical oscillator technique and ion-selective electrodes, respectively, in healthy young volunteers before (10 min) and after (48 min) water drinking for a period of 2 min. Beat-by-beat blood pressure was also monitored throughout the experiment. Drinking 1 l tap water caused a transient increase in blood density immediately after the drinking episode (from 1051.1+/-0.5 g/l before drinking to 1051.8+/-0.5 g/l 4 min after the start of drinking, P<0.05), followed by a gradual reduction (1050.1+/-0.5 g/l at 31 min). This drinking-induced change paralleled those of haematocrit, plasma density and plasma volume. Plasma [Na+] and [Cl-] and osmolality decreased after drinking without transient increases and reached minima at about 30 min. A transient increase in mean arterial blood pressure was observed prior to the increase in blood density. These findings suggest that water drinking causes a biphasic change in plasma volume: initial haemoconcentration, probably due to sympathetic acceleration, followed by haemodilution due to the post-absorptive effect, and further suggest that the fluid shift associated with the initial haemoconcentration is isosmotic.

Adult↗
PubMed2001

Does ascorbic acid prevent retinopathy during interferon therapy in patients with chronic hepatitis C?

PURPOSE: Ascorbic acid was administered to patients with chronic hepatitis C to elucidate the mechanism of onset of retinopathy during interferon (IFN) therapy, and its prevention. METHODS: The subjects were 62 patients with chronic hepatitis C who had been admitted to our hospital. For the IFN therapy, 6 MIU of natural IFN-alpha, or 10 MIU of recombinant human IFN-alpha 2b was administered every day for the first 2 weeks, followed by administration three times a week for 22 weeks. The patients were randomly assigned to a group receiving 600 mg/day of ascorbic acid or a group not receiving ascorbic acid (control group). The optic fundi were examined by ophthalmologists before the IFN therapy began and subsequently at weeks 2 and 4 and then every 4 weeks during the IFN therapy. RESULTS: Retinopathy was found in 9 of the 31 patients (29%) in the ascorbic acid-treated group and in 11 of the 31 patients (35%) in the control group. The cumulative incidence of hemorrhage in the ascorbic acid-treated group was lower than that in the control group during the IFN therapy, but the difference between the two groups was not significant (P = 0.186). The cumulative incidence of cotton-wool spots in the ascorbic acid-treated group was almost same as that in the control group during the IFN therapy. The median platelet counts before the therapy was begun were 11.8 x 10(4)/mm2 in the group with hemorrhage and 16.6 x 10(4)/mm2 in the group without, and the lowest platelet counts during IFN therapy were 7.3 x 10(4)/mm3 in the group with hemorrhage and 9.5 x 10(4)/mm3 in the group without, indicating significantly lower values in the group with hemorrhage (P = 0.018 and P = 0.020, respectively). The lowest platelet counts during IFN therapy were 7.4 x 10(4)/mm3 in the group with cotton-wool spots and 9.7 x 10(4)/mm3 in the group without, indicating a significantly lower value in the group with cotton-wool spots (P = 0.036). CONCLUSIONS: Ascorbic acid was not considered to be useful for the prevention of the retinopathy associated with IFN therapy in patients with chronic hepatitis C.

Adult↗
PubMed2001

p21WAF1/CTP1 expression and hepatitis virus type.

Since p21WAF1/CIP1 (p21) is a universal inhibitor of cyclin-dependent kinases and is regulated transcriptionally by p53, which is activated by DNA stress, its expression reflects DNA stress in chronic hepatitis. Recently an association with both hepatitis B and C virus and the expression of p53 or p21 was reported. We analyzed p21 expression in 18 cases of HBV-associated chronic liver diseases and 32 cases of HCV-associated chronic liver diseases by immunohistochemical analysis, and investigated the possible association between hepatocyte p21 expression and hepatic inflammation, fibrosis, and especially hepatitis virus type. The p21-positive hepatocytes were more numerous in areas of intense inflammation and spotty necrosis and areas close to fibrosis, and they increased according to the degrees of grading and staging. The p21 labeling index (LI) in patients with liver cirrhosis was significantly higher than that in patients with chronic hepatitis of both hepatitis viral types (5.84 +/- 0.61 vs 12.0 +/- 0.83, P < 0.0001 in hepatitis B, 10.28 +/- 0.80 vs 15.6 +/- 1.09, P = 0.0004 in hepatitis C), Furthermore, the p21 LI was significantly higher in HCV-associated liver disease than in HBV-associated liver disease in every group (4.02 +/- 0.48 vs 7.74 +/- 0.96, P = 0.021 in low grade group, 7.35 +/- 0.46 vs 12.8 +/- 0.57, P < 0.0001 in high grade, 12.0 +/- 0.83 vs 15.6 +/- 1.09, P = 0.034 in liver cirrhosis). In, conclusion, p21 expression was up-regulated by the stress of inflammation and fibrosis and might be influenced by viral proteins in human chronic liver disease.

Adult↗
PubMed2001

Fundus autofluorescence in patients with pseudoxanthoma elasticum.

PURPOSE: To characterize changes in fundus autofluorescence in patients with pseudoxanthoma elasticum (PXE). Fundus autofluorescence intrinsically derives from lipofuscin, and the degree of autofluorescence is thought to indicate the degree of retinal pigment epithelium (RPE) metabolic activity. METHODS: Twelve eyes of 6 patients (2 men, 4 women) with PXE were studied with a confocal scanning laser ophthalmoscope. Patient age ranged from 42 to 62 years. The autofluorescence of abnormal retinal areas was compared digitally with that of neighboring, presumed healthy control areas. When the average gray level of a fundus region was 2 SDs above or below the average gray level of a control area, autofluorescence of the fundus region was considered abnormal. RESULTS: In all 12 eyes, some segments of the angioid streaks showed decreased fundus autofluorescence, and other segments of the streaks showed normal autofluorescence. Areas of peripapillary chorioretinal atrophy seen in 2 eyes and of disciform scarring seen in 3 eyes showed decreased autofluorescence. Solitary or multiple drusen-like spots showed increased autofluorescence in all 12 eyes. CONCLUSION: Atrophic and degenerative RPE regions showed decreased fundus autofluorescence in areas of chorioretinal atrophy and in some segments of the angioid streaks. Some drusen-like spots showed increased autofluorescence. The characteristic changes in autofluorescence that we observed in PXE patients suggest that the content of the drusen-like substance differs from that of senile drusen and that the drusen-like lesions are similar to the sub-RPE deposits seen in macular dystrophy.

Adult↗
PubMed2001

SADS: A new component of Fas-DISC is the accelerator for cell death signaling and is downregulated in patients with colon carcinoma.

Fas is the death receptor, transducing cell death signaling upon stimulation by Fas ligand. During Fas-initiated cell death signaling, the formation of Fas-death inducing signaling complex (Fas-DISC) is the first step. Here we have identified a new component of Fas-DISC which we call 'small-accelerator for death signaling' (SADS). SADS cDNA encodes a 150 amino acid polypeptide (Mr = 16,700). During Fas-mediated cell death, SADS enhances the interaction of Fas-death domain-interactive factors (FADD) and procaspase-8, and deletion mutant analysis has identified FADD- and caspase-8-interactive domains in SADS. Inhibition or removal of SADS delays Fas-mediated cell death. In addition, we demonstrate the deletion or mutation of SADS in patients with colon carcinoma and that exogenous SADS expression in human colon carcinoma SW480 cells that lack SADS leads to re-acquisition of Fas-mediated cell death. Here, we propose that SADS is one of the cell death-associated factors and enhances Fas-DISC formation, especially FADD and procaspase-8 recruitment.

Apoptosis↗
PubMed2001

Effect of immunity on gene delivery into anterior horn motor neurons by live attenuated herpes simplex virus vector.

Efficient and prolonged foreign gene expression has been demonstrated in the bilateral anterior horn motor neurons of the spinal cord by intramuscular inoculation with attenuated herpes simplex virus (HSV) expressing latency associated transcript promoter-driven beta-galactosidase (betaH1). To examine the effect of immunity on the gene delivery, betaH1 was applied in rats immunized subcutaneously or intramuscularly with the parent HF strain. Rats were immunized subcutaneously with HF strain and 28 days later when the high antibody titer was maintained, betaH1 was inoculated into the right gastrocnemius muscle. Second, 35 days after inoculation with HF strain into the right gastrocnemius muscle, betaH1 was inoculated at the same site. In both ways of immunization, immunity did not abolish or prevent the transgene expression in the anterior horn motor neurons, but attenuated the range and the number of the beta-galactosidase-positive neurons from about 85% to 50-65% on 28 days after inoculation with betaH1. However, beta-galactosidase activity was observed in a wide range of the bilateral anterior horn motor neurons without significant pathological changes. These findings support the feasibility of the attenuated HSV vector in gene delivery into the central nervous system, even in the presence of immunity.

Animals↗
PubMed2001

Comparative analyses of the conformational stability of a hyperthermophilic protein and its mesophilic counterpart.

Comparison of the conformational stability of an O(6)-methylguanine-DNA methyltransferase (MGMT) from the hyperthermophilic archaeon Thermococcus kodakaraensis strain KOD1 (Tk-MGMT), and its mesophilic counterpart C-terminal Ada protein from Escherichia coli (Ec-AdaC) was performed in order to obtain information about the relationship between thermal stability and other factors, such as thermodynamic parameters, thermodynamic stability and other unfolding conditions. Tk-MGMT unfolded at Tm = 98.6 degrees C, which was 54.8 degrees C higher than the unfolding temperature of Ec-AdaC. The maximum free energy (DeltaG(max)) of the proteins were different; the value of Tk-MGMT (42.9 kJ.mol-1 at 29.5 degrees C) was 2.6 times higher than that of Ec-AdaC (16.6 kJ.mol-1 at 7.4 degrees C). The high conformational stability of Tk-MGMT was attributed to a 1.6-fold higher enthalpy value than that of Ec-AdaC. In addition, the DeltaG(max) temperature of Tk-MGMT was considerably higher (by 22.1 degrees C). The apparent heat capacity of denaturation (DeltaC(p)) of Tk-MGMT was 0.7-fold lower than that of Ec-AdaC. These three synergistic effects, increasing DeltaGmax, shifted DeltaG vs. temperature curve, and low DeltaC(p), give Tk-MGMT its thermal stability. Unfolding profiles of the two proteins, tested with four alcohols and three denaturants, showed that Tk-MGMT possessed higher stability than Ec-AdaC in all conditions studied. These results indicate that the high stability of Tk-MGMT gives resistance to chemical unfolding, in addition to thermal unfolding.

Bacterial Proteins↗
PubMed2001

High expression of CD34-positive sinusoidal endothelial cells is a risk factor for hepatocellular carcinoma in patients with HCV-associated chronic liver diseases.

CD34 has been widely used for the assessment of sinusoid-like neoangiogenesis in hepatocellular carcinoma (HCC). Recently, it was demonstrated that CD34-positive cells isolated from human peripheral blood differentiate into endothelial cells and contribute to neoangiogenesis in adults. We investigated the localization and the substantial role of CD34-positive endothelial cells in the liver with hepatitis C virus (HCV)--associated chronic liver diseases. Liver tissue sections obtained by biopsy from 56 patients with HCV-associated chronic liver diseases by were examined immunohistochemically using anti-CD34, anti-von Willebrand factor (vWF), and anti-vascular endothelial growth factor (VEGF) antibodies. CD34 was stained in the sinusoid, showing dotty, linear, semicircular, or circular patterns. However, sinusoidal expression of vWF was not substantially identified in the same specimens, indicating the existence of sinusoidal CD34-positive but vWF-negative endothelial cells. We classified these cells as CD34 LI and found that CD34 LI was correlated with the expression of VEGF. Among 34 patients with advanced-stage disease, the cumulative incidence of HCC was significantly higher in patients with CD34 LI >or= 12 (n = 16) than in those with CD34 LI < 12 (n = 18; P = .009). Moreover, among several clinicopathologic risk factors, CD34 LI could be recognized as an independently significant factor for development of HCC (relative risk, 7.36; P = .019). We conclude that CD34-positive endothelial cells are regulated by several factors, such as VEGF, and might play a substantial role in hepatocarcinogenesis. Furthermore, high expression of CD34-positive sinusoidal endothelial cells is a risk factor for HCC in patients with HCV-associated chronic liver diseases.

Adult↗
PubMed2001

Problems during and after pregnancy of former biliary atresia patients treated successfully by the Kasai procedure.

BACKGROUND/PURPOSE: The aim of this study was to investigate the problems and the quality of life during and after pregnancy of the patients who had undergone Kasai operation and to find out a strategy for follow-up during the period of their pregnancy. METHODS: A questionnaire was sent to 134 institutions of the Japanese Biliary Atresia Society with the following questions: (1) Do you have any pregnancy cases in patients who had undergone Kasai operation? (2) Did she have any menstrual problem? (3) Did she have any problem during pregnancy and delivery? (4) Did she have any change in liver function tests after delivery? (5) Did she have any early and long-term problem after delivery? (6) Did the baby have any problem? (7) Was there any special care or comment about the pregnancy of the biliary atresia patients? The responses were analyzed. RESULTS: Fourteen institutions reported 16 cases of pregnancy, 23 cases of delivery, and 2 cases of abortion. The causes of abortion in the 2 cases were attributed to hemorrhagic shock after massive bleeding from esophageal varices and serious atopic dermatitis, respectively. Other problems during pregnancy were abruption of placenta, fetal distress leading to caesarian section, and development of liver dysfunction leading liver transplantation. Problems after delivery included deterioration of liver function in 6 patients (37.5%), attacks of ascending cholangitis in 4 patients (25.0%), and severe fatigue with liver dysfunction from nursing the baby leading to liver transplantation. Only 3 of 16 (18.8%) patients were free of any problems. No abnormality was seen in the babies. CONCLUSIONS: Even if the patients with biliary atresia lead a good postoperative course, unexpected complications can occur when they become pregnant. Close long-term follow-up is required for proper management of pregnancy in biliary atresia patients.

Adolescent↗