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Biomedical subjects

O Hashimoto

Publications and source records attributed to O Hashimoto.

At least 55 records · Page 3Linked to original sources
PubMed1997

Follistatin and its role as an activin-binding protein.

Follistatin (FS), a specific binding protein for activin, neutralizes the diverse actions of activin by forming an inactive complex with activin. FS is a monomer derived from two polypeptide core sequences of 288 (FS-288) and 315 (FS-315) amino acids originated from alternatively spliced mRNA. We purified six molecular forms of FS from porcine ovaries. Their structural differences were caused by truncation of the COOH-terminal region and/or the presence of carbohydrate chains, resulting in the formation of FS-288, FS-315 and FS composed of 303 amino acids (FS-303) in various forms of glycosylation on the two potential Asn-linked glycosylation sites. All six molecular species have almost the same activin binding activity (Kd = 540-680 pM). By contrast, the COOH-terminal truncated form, FS-288, showed much higher affinity for heparan sulfate proteoglycans of the cell surface than FS-303, whereas the intact form of FS, FS-315, had no affinity. Furthermore, FS-288 more effectively blocked the suppression of follicle-stimulating hormone (FSH) secretion from rat pituitary cells by activin. This implies that activin binds to the cell surface through FS-288 which adheres to the cell surface. To clarify the physiological role of cell-associated FS, we then investigated the binding of activin to cell-associated FS and the fate of cell surface-bound activin and FS using primary cultured rat pituitary and ovarian granuloma cells. When the cells were incubated with 125I-activin A in the presence of FS-288 or 315, the binding of activin A to the cell surface was promoted much more markedly by FS-288 than by FS-315. The amounts of radioactivity recovered in trichloroacetic acid-soluble fractions (degraded activin) from the incubation medium were greatly increased by the addition of FS-288. This increase was abolished by heparan sulfate, monensin (an endocytosis inhibitor), chloroquine (a lysosome function inhibitor) and several lysosomal enzyme inhibitors. These results suggest that cell-associated FS-288 accelerates the internalization of activin into the cells, leading to its degradation by lysosomal enzymes, and that cell surface-associated FS therefore plays a role in the clearance system of activin.

Activins↗
PubMed1996

cDNA cloning and expression of the Xenopus laevis vitellogenin receptor.

A Xenopus laevis oocyte cDNA library was screened with a PCR-generated X. laevis vitellogenin (VTG) receptor probe and a 3.6 kb cDNA clone containing the entire open reading frame, and 5' and 3' noncoding regions were isolated. The deduced amino acid sequence was 72% homologous to the chicken VLDL/VTG receptor, and the characteristic domains were highly conserved. Ligand binding analysis confirmed that the cloned receptor was Xenopus VTG-specific. Although Northern blotting analysis revealed that this gene was expressed as a major transcript of 3.6 kb in Xenopus ovary, weak but significant expression was observed in other tissues by RT-PCR analysis. The fact that major expression of the gene occurs in the ovary suggests that it has an important function in this organ.

Amino Acid Sequence↗
PubMed1996

The incidence of viremia and the heterogeneity of hepatitis C virus genotypes among blood donors, hemophiliacs and patients with chronic liver disease.

Hepatitis C Virus (HCV) is the major cause of parentally transmitted non-A, non-B hepatitis. We studied the incidence of HCV Viremia in blood donors, hemophiliacs and patients with chronic liver disease who are positive for antibodies to HCV, and then correlated the HCV genotypes among the three groups. 23 blood donors, 10 hemophiliacs and 97 patients with chronic liver disease were found to be positive for anti-HCV during this study period from June 1993 to December 1993. Only 3 (13%) blood donors, 6 (60%) hemophiliacs and 71 (73%) patients with chronic liver disease were found to be viremic when tested for HCV RNA by reverse transcriptase-polymerase chain reaction (RT-PCR). The low incidence of viremia among blood donors may be due to any one of the following three reasons. 1, the level of viremia was below the level of detection. 2, the viremia was intermittent with persistent infection. 3, the majority of cases represented resolved infection. The HCV genotypes were heterogeneous among the three groups. All the blood donors with viremia and 35 (50%) of patients with chronic liver disease, belonged to type II (1b). However only one (17%) of the hemophiliacs belonged to type II (1b). Studies have shown that the genotype I(1a) is the predominant type in the USA and Europe, whereas type II(1b) is more frequent in the Far East. It is also suggested that type II (1b) is associated with non-responsiveness to interferon therapy. Our hemophiliacs were treated with imported coagulation factors, thus they were probably exposed to the genotypes in the west. There was significant difference in the incidence of HCV type II (1b) among local blood donors and hemophiliacs (P = 0.005). However the difference between the hemophiliacs and the patients with chronic liver disease was not statistically significant. The number of patients in this study was too small to draw any firm conclusions. However the findings highlight the importance of studying the genotypes of patients with Hepatitis C infection due to their relevance in the management of these cases with interferon therapy.

Adolescent↗
PubMed1995

Manipulation of a single cell with microcapillary tubing based on its electrophoretic mobility.

Manipulation of a single cell of spherical shape, approximately 5-10 microns in diameter, was performed with capillary tubing and an electrostatic field. A single cell migrates with its electrophoretic mobility into capillary tubing against the flow of electroosmosis coming out of the capillary. After trapping the cell in the capillary, it is pulled out into the other microreservoir with the application of a reverse electric voltage. When we apply a negative voltage to the microreservoir itself, the cell in it can keep floating for a relatively long period due to electrostatic repulsion. The electrophoretic mobility of a single cell is also estimated.

Animals↗
PubMed1995

Glycine-to-arginine substitution at codon 145 of HBsAg in two infants born to hepatitis B e antigen-positive carrier.

Two daughters born to an HBeAg-positive carrier became hepatitis B virus carriers despite immunoprophylaxis with hepatitis B immune globulin or hepatitis B vaccine. The elder daughter received hepatitis B immune globulin alone and the younger daughter received both hepatitis B immune globulin and hepatitis B vaccine. They acquired anti-HBs passively immediately after birth, and the younger daughter did not respond to active immunization. The nucleotide sequence of the S gene of hepatitis B virus DNA from the four carriers in the family was determined. A 531-bp fragment within the S gene, which includes a region encoding both the common a and type-specific d/y or r/w determinants, was amplified by polymerase chain reaction and sequenced. Antigenic subtypes of HBV were identified as adr in the father and adw in both the mother and two daughters. Amino acid residues 122-160 of HBsAg were identical between the daughters and their mother except for a glycine-to-arginine substitution at codon 145. A possibility that this escape mutant had selective advantage over wild-type hepatitis B virus under immune pressure is discussed.

Amino Acid Sequence↗
PubMed1995

Functional liver imaging with asialoglycoprotein receptors and serum hyaluronate in a patient with amyloidosis.

A 47-year-old man with primary amyloidosis was admitted with abdominal pain. A new radionuclide liver imaging technique using Technetium-99m diethylenetriamine-pentaacetic acid-galactosyl human serum albumin, was performed and the serum hyaluronate concentration was measured. Although ordinary laboratory tests revealed only slight abnormalities, the uptake of the radiolabelled ligand for hepatocyte asialo-glycoprotein receptors was decreased, and marked hepatomegaly was revealed. Furthermore, the serum hyaluronate level was elevated. Histological examination of a hepatic needle biopsy specimen revealed a marked deposition of amyloid in the hepatic perisinusoidal spaces. These results indicate that this new radionuclide liver imaging technique (using Technetium-99m diethylenetriamine-pentaacetic acid-galactosyl human serum albumin) and the measurement of serum hyaluronate may be useful supplementary tools for identifying amyloid deposition in the hepatic perisinusoidal spaces in patients with amyloidosis.

Amyloidosis↗
PubMed1995

Ultrastructure of cardiac myocyte in the Asian elephant (Elephas maximus).

Cardiac myocytes of an Asian elephant (Elephas maximus) were observed by transmission electron microscopy. Typical ultrastructural features of cardiac myocytes are exhibited in the musculature of both the left and right atria, and left ventricle of the heart. Myofibrils, mitochondria, T-system and sarcoplasmic reticulum are well-developed within the cytoplasm. Many mitochondria are characteristically concentrated is some myocytes. Cardiac musculature is also distributed in the root of the caudal vena cava. Many atrial granules are detected not only in atrial myocytes, but also in the myocytes of the caudal vena cava. Atrial natriuretic polypeptide may be secreted from the caval venous wall in the elephant.

Animals↗
PubMed1995

Effect of extracellular matrix on two cell lines established from Mongolian Gerbil's (Meriones unguiculatus) malignant melanoma.

We investigated the effect of extracellular matrix (ECM) on the adhesion, morphology and proliferation of two Mongolian gerbil's melanoma cell lines (MGM-S, MGM-A) which differed in malignancy. Fibronectin matrix was detected on the cell surface of MGM-S by immunofluorescence techniques. MGM-A cells, showing a multipolar shape, were widely spread over the dishes coated with fibronectin, laminin or type IV collagen. The adhesion rate of MGM-A cells to ECM components was higher compared to that in controls. Attachment to laminin was conspicuously promoted. The effect of laminin on MGM-A cell growth was also the highest among the substrates examined. On the other hand, these ECM components did not affect MGM-S cells. These results suggest that laminin and fibronectin may participate in the malignancy of MGM cell lines.

Animals↗
PubMed1994

Acute and chronic effects of thromboxane A2 inhibition on the renal hemodynamics in streptozotocin-induced diabetic rats.

We examined acute and chronic effects of thromboxane (TX) A2 inhibition on the renal hemodynamics at early and late stage of untreated streptozotocin (STZ)-induced diabetic rats. Two weeks and 28 weeks after the induction of diabetes, renal blood flow (RBF) under anesthesia was measured with an electromagnetic flowmeter before and after TXA2 inhibition. In two-week-old diabetic rats, a specific TXA2 synthetase inhibitor, OKY-046, or a specific TXA2 receptor antagonist, Sulotroban, increased renal vascular resistance (RVR) and ameliorated the hyperperfusion. The renal vasoconstrictive effect of OKY-046 was blunted by an angiotensin converting enzyme (ACE) inhibitor, MK422, or an angiotensin II receptor antagonist, Saralasin. On the contrary, OKY-046 ameliorated the renal hypoperfusion by decreasing RVR in 28-week-old diabetic rats. Chronic oral administration of OKY-046 ameliorated not only the renal hyperperfusion but increased urinary albumin excretion (UAE) at two weeks, but also the renal hypoperfusion, filtration fraction and UAE at 24 weeks. It is suggested that TXA2 might, at least in part, play important roles in the hyperperfusion by modulating activity of the renin-angiotensin system at an early stage of untreated diabetic rats and in the hypoperfusion at the late stage of untreated diabetic rats, and that TXA2 is also involved in the increase of UAE. These results support roles for TXA2 in the progression of renal injury in STZ-induced diabetic rats.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1993

Compensatory function of central dopaminergic system for suppressing psychic seizures--repeated plasma homovanillic acid measurement in refractory temporal lobe epilepsy.

Repeatedly measured plasma homovanillic acid concentration, as a clinically available index of central dopaminergic activity in a patient with temporal lobe epilepsy during a drug-free period, was significantly correlated with seizure frequency in the week immediately following, but not preceding, blood sampling days. This result suggests a compensatory function of the dopaminergic system in suppressing refractory psychic seizures.

Adult↗