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Biomedical subjects

Y Shiratori

Publications and source records attributed to Y Shiratori.

At least 217 records · Page 12Linked to original sources
PubMed1990

Protein modeling of human prorenin using the molecular dynamics method.

To study the activation-inactivation mechanism of the renin zymogen, prorenin, a tertiary structural model of human prorenin was constructed using computer graphics and molecular dynamics calculations, based on the pepsinogen structure. This prorenin model shows that the folded prosegment polypeptide can fit into the substrate binding cleft of the renin moiety. The three positively charged residues, Arg10, Arg15, and Arg20, in the prosegment make salt bridges with Asp225, Glu331, and Asp60, respectively, in renin. Arg43, which is in the processing site, forms salt bridges with the catalytic residues of Asp81 and Asp269. These ionic interactions between the prosegment and the renin may contribute to keeping the prorenin structure as an inactive form.

Amino Acid Sequence↗
PubMed1990

Percutaneous ethanol injection therapy for neoplasms located on the surface of the liver.

There has been a reluctance to perform percutaneous ethanol injection therapy on lesions located on the surface of the liver because of the possibility of complications. We treated 16 lesions located on the surface of the liver in 14 patients by percutaneous ethanol injection and evaluated the complications and efficacy. Bleeding and seeding of malignant cells did not occur in any case. However, transient pain after injection of ethanol was more intense in these patients than in those whose lesions were not on the surface of the liver. Histopathologic examinations, imaging findings, and decrease in the serum alpha-fetoprotein levels showed that percutaneous ethanol injection was effective for tumors located on the surface of the liver. Our experience suggests that percutaneous ethanol injection can be performed safely even when lesions are located on the surface of the liver.

Adult↗
PubMed1990

Percutaneous ethanol injection therapy of hepatocellular carcinoma: analysis of 77 patients.

Although sonographically guided percutaneous ethanol injection therapy has been attracting a great deal of attention in the treatment of liver neoplasms, few reports regarding long-term results of this therapy have been published. We report here our 4-year experience, in which ethanol injection was performed 419 times on 108 lesions in 77 patients with hepatocellular carcinoma. Histopathologic examination performed in 14 cases after the therapy revealed that the lesion was completely necrotic in 10 cases, 90% necrotic in three cases, and 70% necrotic in the remaining case. Angiography performed after the therapy showed complete disappearance of tumor stain in 37 of 42 cases treated with ethanol injection. CT after the therapy showed no enhancement of the treated lesion in 55 of 56 cases. Elevated serum levels of alpha-fetoprotein decreased in 21 of 24 cases. Ethanol injection improved the long-term prognosis of the patients. Among the 50 patients in whom there were three or fewer lesions and all lesions were treated by ethanol injection, the 1-, 2-, 3-, and 4-year survival rates were 89%, 74%, 68%, and 60%, respectively. Factors that significantly affected the prognosis were the goal of the treatment, liver function, and size of the largest lesion. Serious complications rarely occurred even in patients with severe liver dysfunction. Percutaneous ethanol injection therapy appears to be valuable for treatment of hepatocellular carcinoma.

Adult↗
PubMed1990

Deletion of D-helix in bovine pancreatic phospholipase A2.

D-Helix-deleted bovine pancreatic phospholipase A2 was designed using molecular mechanic calculations, and synthesized. Effects of the deletion on the enzymatic activity and on the structure were investigated. The enzymatic activity of the mutant protein was about 40% of that of the native one for a micellar substrate of 1,2-dioctanoyl-phosphatidylcholine. Although the Michaelis constant of the mutant enzyme was not changed, the catalytic constant was decreased. The dissociation constant of calcium ion was also changed. 1H NMR study revealed a slight conformation change around the active site of the mutant enzyme in addition to changes around the mutated region. The effect on the activity of the mutation seems to be due to the conformational changes around the active site.

Amino Acid Sequence↗
PubMed1990

Ultrasound-guided percutaneous injection of ethanolamine oleate for hypersplenism. An experimental study in dogs.

In order to evaluate a possible therapy for hypersplenism, an experiment with animals was done. In nine dogs, 0.6 ml/kg body weight of 5% ethanolamine oleate was injected percutaneously into the spleen under ultrasound guidance. The injection was repeated three times at intervals of 1 week. Three dogs each were killed at 1, 4, and 8 weeks after the final injection. All dogs tolerated the procedure well and lived until they were killed. The platelet count and leukocyte count increased after the injections, and remained higher than the pretreatment level until death. This effect probably is due to depressed splenic function. The autopsy showed 40% of the spleen to be infarcted with complete destruction of the normal structure. No serious complications occurred. In addition, injection of ethanolamine oleate in six fully heparinized dogs showed that there was little risk of hemorrhage. Ultrasound-guided percutaneous injection of ethanolamine oleate might be a simple and effective therapy for hypersplenism.

Administration, Cutaneous↗
PubMed1989

Production of leukotriene B4 in parenchymal and sinusoidal cells of the liver in rats treated simultaneously with D-galactosamine and endotoxin.

A study was conducted to investigate production rate of leukotriene B4 (LTB4) in parenchymal and sinusoidal liver cells of rats with acute hepatic failure (AHF). AHF was induced by simultaneous administration of D-galactosamine (GalN) and endotoxin (LPS), and parenchymal as well as sinusoidal liver cells were isolated by collagenase perfusion method. Following preincubation for 15 min, isolated cellular fractions were incubated with Ca-ionophore (2 microM) for 5 min, and levels of LTB4 in culture media before and 5 min after addition of Ca-ionophore were analyzed by HPLC. Following results were obtained: The production rate of LTB4 was found to be the highest in Kupffer cells (7.2ng/10(6) cells/5 min), followed by endothelial cells (1.1), stellate cells (0.2) and parenchymal cells (not detectable). The production rate of LTB4 in both Kupffer cells and endothelial cells was found to reach a maximum in the fraction isolated 60 min after administration of GalN and LPS. Treatment with AA861, one of the selective inhibitors of 5-lipoxygenase, was shown to reduce the production of LTB4 in Kupffer cells to 53% at 10(-7)M and above 99% at higher than 10(-5)M. In conclusion, the majority of LTB4 generated in the liver of rats with AHF was found to be synthesized in Kupffer cells and, to a lesser extent, in endothelial cells, and the enhanced production of LTB4 was found to be greatly inhibited by treatment with AA861.

Acute Disease↗
PubMed1989

Kupffer cell function in chronic ethanol-fed rats.

In an attempt to clarify the Kupffer cell function in alcoholism, chronic ethanol-fed rats were investigated. The clearance of latex particles in the rat was analysed to estimate the function of the reticuloendothelial system in the liver, and the phagocytic function of Kupffer cells was measured by counting particles in the cell after isolation of non-parenchymal cells by collagenase digestion of the liver following an injection of latex particles and subsequently by staining of endogenous peroxidase activities. In addition, the number of Kupffer cells and their phagocytic function were examined histologically in fresh frozen sections of liver after an injection of particles. Serum ethanol concentration in the ethanol-fed rats was 10-60 mumol/l. The clearance of latex particles was markedly reduced in the ethanol-fed rats as compared with the paired controls (P less than 0.01). Markedly decreased-phagocytic function was found in 20% of Kupffer cells in the chronic ethanol-fed rats. The number of Kupffer cells in the ethanol-fed rats was increased as compared with the paired control rats. Chemotaxis analysis revealed that hepatocytes when incubated with ethanol, produced chemotactic factor for Kupffer cells and polymorphonuclear cells. These abnormal Kupffer cell functions may contribute to the pathogenesis of alcoholic liver disease.

Animals↗
PubMed1989

Phagocytic properties of hepatic endothelial cells and splenic macrophages compensating for a decreased phagocytic function of Kupffer cells in the chronically ethanol-fed rats.

The balance of phagocytic function among Kupffer cells, hepatic endothelial cells and splenic macrophages in the chronically ethanol-fed rats has been investigated. Clearance of latex particles in the blood was measured to estimate the function of the reticuloendothelial system. Phagocytosis of latex particles by Kupffer cells, hepatic endothelial cells or splenic macrophages in vivo was measured by counting the number of ingested particles in a cell after isolation of hepatic nonparenchymal cells or spleen cells following injection of different amounts of latex particles. Latex particle clearance was suppressed in the ethanol-fed rats, demonstrating a decreased phagocytic capacity of the reticuloendothelial system. Markedly decreased phagocytic function was found in 40% of Kupffer cells of the chronically ethanol-fed rats. In contrast, the number of latex particles in hepatic endothelial cells and in splenic macrophages was increased after injection of a triggering dose of latex particles. From these results it may be concluded that an increased phagocytosis of hepatic endothelial cells and splenic macrophages could compensate for the decreased phagocytic function of Kupffer cells.

Animals↗
PubMed1988

Characterization of N-linked oligosaccharides attached to human renin expressed in COS cells.

To study the role of N-linked oligosaccharides attached to human renin, we generated three kinds of glycosylation-deficient renins in which one or both of two putative N-glycosylation sites was eliminated by amino acid replacement using site-directed mutagenesis. Examination of the three mutant renins (Asn-5 to Ala, Asn-75 to Ala, and both Asn-5 and -75 to Ala) expressed in COS cells demonstrated that both putative sites were certainly glycosylated with heterologous N-linked oligosaccharides. Moreover, the oligosaccharide chain attached at Asn-5 was different from that attached at Asn-75 in its molecular size. In addition, the secreted amount of the three mutant renins were different from one another, although the mutant and wild-type renins had practically the same specific activity. Our results suggest that the N-linked oligosaccharides have no effect on the enzymatic activity, but play an important role in stable secretion of human renin.

Cell Line↗
PubMed1987

Immunohistochemical detection of the placental form of glutathione S-transferase in dysplastic and neoplastic human uterine cervix lesions.

Expression of the human placental form of glutathione S-transferase (GST-pi) in dysplasia (53 cases), carcinoma in situ (10 cases), and invasive carcinoma (46 cases) of human uterine cervix was investigated immunohistochemically with specific anti-GST-pi rabbit antibody. While normal squamous epithelium was largely negative, the binding of antibody was appreciable in mild and moderate dysplasias, especially in the cytoplasm of cells demonstrating koilocytotic atypia. In severe dysplasia, the nuclei as well as the cytoplasm were strongly stained in all cell layers except for the superficial layer, and in carcinoma in situ both of them were also strongly stained in all cell layers. In invasive carcinoma, over 90% of cases exhibited strong cytoplasmic staining and in over 70% the nuclei were positive. GST activity towards 1-chloro-2,4-dinitrobenzene and GST-pi protein content were significantly increased in all of 4 squamous cell carcinomas examined as compared to values for normal cervical epithelia. Two-dimensional gel electrophoresis followed by immunoblotting using the GST-pi antibody demonstrated that, of many cytoplasmic proteins, only the GST-pi subunit was specifically bound. These results indicate that GST-pi is a potentially useful immunohistochemical marker for (pre)neoplasia of human uterine cervix. In addition, it was demonstrated that the cells in severe dysplasia, carcinoma in situ, and invasive carcinoma expressing GST-pi were often characterized by staining with a monoclonal antibody to the v-H-ras gene product.

Female↗
PubMed1987

[Trials for simplified hypertonic saline test].

Hypertonic saline test is indispensable for the evaluation of posterior pituitary function. However the test is not simple, including water loading, urine sampling and at least 45 min of hypertonic saline infusion, mostly because the test relies on urinary osmolality as an index of ADH secretion. The object of this study is try to simplify the test by directly measuring plasma ADH concentration before and after 10 min of hypertonic saline infusion. Intravenous infusion of hypertonic saline (5% NaCl, 0.24 ml/kg/min, for 10 min) was performed on normal subjects, patients with diabetes insipidus and patients with renal failure under chronic hemodialysis. Venous blood samples were obtained seriously including just before and after 10 min of the infusion. ADH was extracted from plasma using Sep-Pak C18 column and assayed by specific RIA. Minimum sensitivity of the assay was 0.25 pg/ml. The hypertonic saline infusion resulted in an increase of plasma osmolality by about 8 mOsm/kg H2O and plasma sodium concentration by 4 mEq/l. Plasma ADH increased from 0.77 +/- 0.09 to 3.42 +/- 0.73 pg/ml (m +/- SE, n = 8, p less than 0.01) in normal subjects of ad lib. water drinking and from 0.55 +/- 0.33 to 2.34 +/- 0.33 (m +/- SE, n = 4, p less than 0.05) in water loaded normal subjects (20 ml/kg of water, 60 min before hypertonic saline infusion).(ABSTRACT TRUNCATED AT 250 WORDS)

Diagnosis, Differential↗
PubMed1987

[13C]methacetin breath test for evaluation of liver damage.

Methacetin undergoes rapid O-dealkylation by hepatic microsomal enzyme systems, and the resultant CO2 is present in the expired air. The rate of O-dealkylation of methacetin was assessed by the [13C]methacetin breath test in seven healthy volunteers and 30 patients with histologically proven chronic liver diseases. The 30-min recovery of orally administered [13C]methacetin as 13CO2 in the exhaled air was significantly reduced in patients with chronic aggressive hepatitis and in those with liver cirrhosis but not in patients with chronic persistent hepatitis or healthy controls. Patients with either advanced cirrhosis or hepatocellular carcinoma showed significantly lower values than those with well-compensated cirrhosis. The levels in two patients with late primary biliary cirrhosis were reduced. These results show that the severity of liver damage can be effectively evaluated by [13C]methacetin breath test. In addition, this test is simple, safe, and time efficient.

Acetamides↗
PubMed1987

Modulation of collagen synthesis by fat-storing cells, isolated from CCl4- or vitamin A-treated rats.

In an attempt to elucidate the role of fat-storing cells (FSCs) in liver fibrosis, we investigated the collagen synthesis by FSCs freshly isolated from rats treated with CCl4, with vitamin A, and from untreated rats. FSCs from CCl4-treated rats contained a small number of lipid droplets and an abundant rough endoplasmic reticulum (RER), while those from vitamin A-treated rats showed numerous large lipid droplets and scanty RER. The population doubling times of FSCs isolated from normal, CCl4-treated, and vitamin A-treated rats were 38 +/- 4.3, 24 +/- 2.5, and 48 +/- 6.3 hr, respectively. The rate of collagen synthesis by FSCs from CCl4-treated rats was four- to sixfold enhanced, while collagen synthesis by FSCs from vitamin A-treated rats was suppressed. The ratio of collagen type I to type III produced by FSCs from CCl4 rats was enhanced as compared with control rats (94.7:5.3 vs 87.6:12.4). Therefore, FSCs can be considered to play an important role in the pathogenesis of liver fibrosis.

Animals↗
PubMed1987

[Immunohistochemical and biochemical investigations on glutathione S-transferases in the human placenta].

GST-pi can be purified as a major molecular form of glutathione S-transferase (GST) in human placenta. In this paper, the localization of GST-pi as well as of neutral and basic GSTs in the first, second and third trimester placental tissues (10, 3 and 14 samples, respectively) was investigated immunohistochemically using antibodies to acidic GST-pi from the placenta, neutral GST-mu and basic GST-I from the liver. Total GST activity was assayed using 1-chloro-2,4-dinitrobenzene as a substrate, and the relative activity and content of GST-pi were determined by activity inhibition test and single radial immunodiffusion, respectively, on 4 first and 5 third trimester placental tissues. The results obtained were as follows. In early placenta, cytotrophoblasts were strongly stained by anti-GST-pi antibody, while in third placenta mainly syncytiotrophoblasts were stained. GST-mu was stained only in syncytiotrophoblast in early placenta, while basic GST-I was weakly stained in the various cells in early to term placenta. Total GST activity in early and term placentas was 5.8 +/- 2.0 units/g of tissue (mean +/- S.D.) and 14.8 +/- 3.4 units/g, respectively. GST-pi relative activities were 90 +/- 4% and 85 +/- 6%, and GST-pi content was 41 +/- 31 micrograms/g and 106 +/- 29 micrograms/g, respectively. These results indicate that GST-pi is a major form of GST and localized mainly in trophoblasts at any developmental stage of the placenta, and it increases with development.

Cell Cycle↗
PubMed1986

Superoxide anion generating capacity and lysosomal enzyme activities of Kupffer cells in galactosamine induced hepatitis.

To elucidate the function of the reticuloendothelial system of liver in hepatic injury, we investigated the effect of endotoxins on superoxide anion (O-2) generating capacity and lysosomal enzyme activities of Kupffer cells isolated from rats treated with galactosamine (Gal N), with Gal N supplemented with polymyxin B (Polymyxin B-Gal N), with lipopolysaccharide (LPS) and from control rats. After collagenase digestion of the liver and centrifugation over metrizamide gradient, Kupffer cells were prepared by the dish adherence procedure. O-2 production by the cells was examined as chemiluminescence during phagocytosis of latex particles and beta-glucuronidase activities were analyzed. High titers of endotoxemia were detected in LPS and Gal N rats by limulus test, while a low endotoxemia titer was found in Polymyxin B-Gal N rats. Hepatocyte damage was found in Gal N rats, but little was recognized in LPS and Polymyxin B-Gal N rats. In the latter groups, Kupffer cells, activated by endotoxins, showed the enhancement of chemiluminescence and a release of lysosomal enzyme. Though lysosomal enzyme was released from Kupffer cells in Gal N rats, chemiluminescence was slightly suppressed in spite of the high titer of endotoxemia. These results appear to be related to the consumption of O-2 during liver injury. The functional state of Kupffer cells was thus changed by the grade of endotoxemia and hepatic injury.

Animals↗