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Biomedical subjects

Y Matumoto

Publications and source records attributed to Y Matumoto.

At least 19 recordsLinked to original sources
PubMed1998

Structure-function studies of human leptin.

To elucidate the structural requirement of human leptin for its functions, the wild-type, mutant-type, C-terminal deletion, and N-terminal deletion were expressed in Escherichia coli and purified in soluble forms. These leptin analogs were intracerebroventrically injected into C57BL/6J ob/ob mice, and their in vivo biological activities were evaluated. The mutant-type leptin lacking a C-terminal disulfide bond reduced food intake at doses of more than 15 pmol/mouse, which was as effective as the wild-type leptin. C-terminal deletion without the loop structure, also significantly, but to a lesser extent, reduced food intake at doses of more than 90 pmol/mouse. However, N-terminal deletions showed no effect on food intake. We also evaluated the effects of the leptin analogs on radiolabeled leptin binding to its receptor in the choroid plexus using autoradiography. An excess of unlabeled mutant-type leptin as well as wild-type leptin led to complete inhibition of binding. C-terminal deletions led to weak inhibitory activity, whereas N-terminal deletions caused no inhibitory activity. These results clearly demonstrate that the N-terminal region of leptin is essential for both its biological and receptor binding activities. The amino acid sequence of the C-terminal loop structure is also important for enhancing these actions, whereas the C-terminal disulfide bond is not needed.

Animals↗
PubMed1998

Selective tumoricidal effect of soluble proteoglucan extracted from the basidiomycete, Agaricus blazei Murill, mediated via natural killer cell activation and apoptosis.

We have isolated a novel type of natural tumoricidal product from the basidiomycete strain, Agaricus blazei Murill. Using the double-grafted tumor system in Balb/c mice, treatment of the primary tumor with an acid-treated fraction (ATF) obtained from the fruit bodies resulted in infiltration of the distant tumor by natural killer (NK) cells with marked tumoricidal activity. As shown by electrophoresis and DNA fragmentation assay, the ATF also directly inhibited tumor cell growth in vitro by inducing apoptotic processing; this apoptotic effect was also demonstrated by increased expression of the Apo2.7 antigen on the mitochondrial membranes of tumor cells, as shown by flow-cytometric analysis. The ATF had no effect on normal mouse splenic or interleukin-2-treated splenic mononuclear cells, indicating that it is selectively cytotoxic for the tumor cells. Cell-cycle analysis demonstrated that ATF induced the loss of S phase in MethA tumor cells, but did not affect normal splenic mononuclear cells, which were mainly in the G0G1 phase. Various chromatofocussing purification steps and NMR analysis showed the tumoricidal activity to be chiefly present in fractions containing (1-->4)-alpha-D-glucan and (1-->6)-beta-D-glucan, present in a ratio of approximately 1:2 in the ATF (molecular mass 170 kDa), while the final purified fraction, HM3-G (molecular mass 380 kDa), with the highest tumoricidal activity, consisted of more than 90% glucose, the main component being (1-->4)-alpha-D-glucan with (1-->6)-beta branching, in the ratio of approximately 4:1.

Agaricus↗
PubMed1998

Down-regulation of focal adhesion kinase, pp125FAK, in endothelial cell retraction during tumor cell invasion.

Although endothelial cell retraction is required before tumor cell invasion, its molecular mechanism still remains obscure. We previously demonstrated that conditioned medium (CM) derived from a human pancreatic cancer cell line, PSN-1, induced endothelial cell retraction and facilitated tumor cell invasion. To investigate the molecular change of events in the transduction of extracellular signals during endothelial cell retraction, we examined the effect of the CM derived from PSN-1 cells on the tyrosine phosphorylation in endothelial cells. Immunoblot analyses revealed that the PSN-1 CM decreased tyrosine phosphorylation of a 120-130 kD protein, and induced the concomitant down-regulation of focal adhesion kinase, pp125FAK, during endothelial cell retraction in time- and dose-dependent fashions. These changes preceded endothelial cell retraction and were reversible after removal of the CM. Further quantitative densitometric analyses demonstrated that the extent of decrease in tyrosine phosphorylated 120-130 kD protein during the endothelial cell retraction was likely to be proportional to that of the down-regulation of pp125FAK. A tyrosine phosphorylated 120-130 kD protein immunoprecipitated by anti-phosphotyrosine antibody immunoreacted with anti-pp125FAK antibody. These results suggested that decreased amount of a tyrosine phosphorylated 120-130 kD protein probably due to the down-regulation of pp125FAK might be associated with the signal transduction pathway in the endothelial cells during their retraction. Furthermore, these findings were also observed in the CM from another four human cancer cell lines, suggesting the down-regulation of pp125FAK in endothelial cells during tumor cell invasion.

Animals↗
PubMed1997

Prenatal diagnosis of congenital unilateral hydrocephalus.

A case is presented in which fetal unilateral hydrocephalus that had not been definitively diagnosed by ultrasonography was confirmed by means of magnetic resonance imaging. Computed tomography performed in the neonatal period after intraventricular injection of contrast medium showed stenosis of the foramen of Monro.

Adult↗
PubMed1997

The molecular mechanisms of 5-fluoro-2'-deoxyuridine induced cell death.

The molecular mechanism of cell death induced by 5-Fluoro-2'-deoxyuridine (FUdR) was investigated. FUdR caused cell death to induce dNTP pool imbalance and following DNA double strand breaks in mouse mammary tumor FM3A cells. We isolated a new endonuclease from FUdR-treated cells, named endonuclease S, that played an important role in FUdR-induced cell death. Cells treated with FUdR showed intracellular acidification before cell death formation. We observed that the endonuclease S in acidic cells may lead the DNA fragmentation. On the other hand, we observed that protease inhibitors (such as TLCK, TPCK, PMSF, p-APMSF, Pefabloc SC and Z-Asp-CH2-DCB) blocked intracellular acidification, DNA fragmentation and FUdR-induced cell death. But the inhibitors did not affect dNTP pool imbalance in the cells. These results suggest that proteases act at the point of downstream of dNTP pool imbalance and upstream of the intracellular acidification.

Animals↗
PubMed1995

The complete nucleotide sequence of odontoglossum ringspot virus (Cy-1 strain) genomic RNA.

The complete nucleotide sequence of the genomic RNA of odontoglossum ringspot virus Cy-1 strain (ORSV Cy-1) was determined using cloned cDNA. This sequence is 6611 nucleotides long containing four open reading frames, which correspond to 126 K, 183 K, 31 K, and 18 K proteins. Its genomic organization is similar to other tobamoviruses, TMV-V(vulgare), TMV-L (tomato strain), tobacco mild green mosaic virus (TMGMV) and cucumber green mottle mosaic virus (CGMMV). The 5' non-coding regions of ORSV Cy-1 is 62 nucleotides. The ORFs encoded a 126 K polypeptide and a 183 K read-through product in which helicase-sequence and polymerase-sequence motifs are found. The ORFs encoding the 126 K and 183 K proteins have 61% and 63% identities with those of TMV-V. The third ORF encoded a 31 K protein homologous to TMV cell-to-cell movement protein. It has 63% identities with that of TMV-V. The fourth ORF encoded an 18 K coat protein. The 5' non-coding region, which extends from base 1 to 62 has 2 G residues and a ribosome binding site (AUU). The 3' non-coding region, 414 nucleotides in length, is entirely different from that of other tobamoviruses.

Amino Acid Sequence↗
PubMed1994

Surgical treatment of ventricular tachycardia after surgical repair of tetralogy of Fallot. Relation between intraoperative mapping and histological findings.

BACKGROUND: The mechanism of ventricular tachycardia (VT) after correction of tetralogy of Fallot (TF) is poorly understood. The purpose of this study was to examine the histopathology of the arrhythmogenic area detected by intraoperative mapping. METHODS AND RESULTS: The patients were three men who underwent radical surgery for TF at age 3, 3, or 5 years, respectively. VT developed at 8, 9, or 11 years, respectively, after surgery, and shock developed during VT in every case. The ECG revealed monomorphic VT in two cases and polymorphic VT in one case. Induction of VT resulted in a wide left-axis deviation-pattern QRS with cycle lengths varying between 260 and 330 milliseconds. The VT origin was identified at the right ventricular outflow tract (RVOT). A radical operation was performed with the patient under cardiopulmonary bypass. On epicardial mapping, delayed activation of the RVOT was recorded during sinus rhythm, and clockwise circus movement of the macroreentry current during VT on the right ventricular free wall was documented in each case. The VTs were treated successfully by surgical resection and cryoablation of the myocardium. In every patient, histology of the myocardial specimens showed degeneration, adiposis, fibrosis, inflammatory cell infiltration, and scattered myocyte islets. These lesions corresponded anatomically to the area of myocardium in which delayed activation was evident during epicardial mapping. CONCLUSIONS: The results of this study indicate that patients with VT after radical correction of the TF have abnormal histopathological findings at the site of the prior right ventriculotomy scar. These lesions were noted within the region of delayed activation found during epicardial mapping and were found to be a part of the reentrant circuit.

Adult↗
PubMed1993

Inhibition of varicella-zoster virus (VZV) glycoprotein expression by a human monoclonal antibody against VZV glycoprotein III.

Effects of human monoclonal antibodies (MAbs) against varicella-zoster virus (VZV) glycoproteins (gp) on VZV glycoprotein expression were analyzed by flow cytometry. Human embryonic fibroblast (HEF) cells were inoculated with cell-free VZV and cultured in the presence of human MAbs. While human MAbs directed against gpI (V2) and -II (V1) did not affect VZV expression, a human MAb against gpIII (V3) inhibited expression of VZV gpI, -II, -III, and -IV. V3 also inhibited spread of VZV from infected to uninfected cells. Interferon-alpha, -beta, and -gamma and tumor necrosis factor-alpha were able to synergize with V3 and inhibit VZV gp expression. These results suggest that human MAb V3 may be useful for passive prophylaxis against VZV infection and for treatment of severe VZV infection.

Antibodies, Monoclonal↗
PubMed1991

Molecular cloning, sequencing and expression in Escherichia coli of the odontoglossum ringspot virus coat protein gene.

The sequence of the 3'-terminal 1865 nucleotides of the genome of the tobamovirus odontoglossum ringspot virus (ORSV) was determined. This sequence contained two open reading frames (ORFs), 912 and 477 nucleotides long. The 912 nucleotide ORF has been identified as the cell-to-cell transport protein gene. The 477 nucleotide ORF was expressed in Escherichia coli, and the product was detected by antibodies specific for the coat protein of ORSV. The amino acid sequence of protein encoded by this ORF shares 84% similarity with the tobacco mosaic virus (TMV) (vulgare) coat protein. The 3'-terminal untranslated region of ORSV comprises 414 nucleotides, 210 nucleotides more than that of TMV (vulgare) RNA.

Amino Acid Sequence↗
PubMed1990

[A case of complex cardiac anomalies with high pulmonary blood flow treated successfully by PDA banding].

A patient with complex cardiac anomalies who developed severe respiratory insufficiency due to high pulmonary blood flow from a giant PDA was treated successfully by PDA banding. PDA-dependent heart disease causes a reduction in pulmonary blood flow in many patients and is often treated by palliative shunt operation. Although the present patient had PDA-dependent heart disease, heart failure occurred due to increased pulmonary blood flow through PDA and required surgical treatment. We performed PDA banding, because it is technically simple and allows adjustment of the postoperative pulmonary blood flow according to the degree of constriction. The degree of constriction was determined according to the PaO2 value. SO2 levels of 60-70% have been used as an index of the extent of banding, but PaO2 is considered to be equally appropriate.

Constriction↗
PubMed1989

[Movement of regenerated lens epithelial cells in 50% galactose cataract and an aldose reductase inhibitor].

In experimental galactose cataract of rats, lens fiber cells were gradually destroyed by swelling and liquefaction occurring due to the accumulation of galactitol. In addition to the destruction of lens fiber cells, marked regeneration of lens epithelial cells was universally observed. In this study, we used the technique of 3H-thymidine autoradiography and examined the movement of regenerated (DNA synthesis) lens epithelial cells. On the fourth day from the starting of 50% galactose chow, 3H-thymidine was injected into the anterior chamber. After one week, 3H-thymidine-labelled epithelial cells was observed at the bow region of the equatorial area. After 2 to 4 weeks, labelled cells were found in the regenerated lens fibers of the cortex. After 3 weeks, labelled cells about to be destroyed by swelling and liquefaction were recognized. However, a few labelled cells were still observed in the epithelial cell layer. The same experiments were performed in two groups of normal chow-fed one and 50% galactose + an aldose reductase inhibitor (Statil)-fed one. The movements of 3H-thymidine labelled epithelial cells in the above two groups were almost identical. In addition, the movement of labelled cells was normalized by an aldose reductase inhibitor.

Aldehyde Reductase↗
PubMed1980

Carcinoma arising in a choledochocele.

A case of carcinoma arising in a choledochocele (type III of biliary cyst in Alonso-Lej classification) in a 61-year-old woman is presented. This is the first case reported of a malignant change developing in a choledochocele.

Adenocarcinoma, Papillary↗