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Biomedical subjects

H Murakami

Publications and source records attributed to H Murakami.

At least 325 records · Page 18Linked to original sources
PubMed1996

Impaired endothelium-dependent vasorelaxation in peripheral vasculature of patients with thromboangiitis obliterans (Buerger's disease).

BACKGROUND: Thromboangiitis obliterans (TAO) is an occlusive arterial disease and a separate disease entity from atherosclerosis. It occurs mainly in the small and medium-sized vessels. Although the cause of TAO is unknown, systemic factors (immunological or humoral) may be involved in addition to abnormal peripheral microcirculation. Endothelium is now recognized as an important factor in the maintenance of microvascular circulation and the inhibition of platelet aggregation. This study examines the possible impairment of endothelium-dependent vasodilation in the peripheral vasculature of patients with TAO. METHODS AND RESULTS: Forearm blood flow (FBF) changes induced by the endothelium-dependent vasodilator acetylcholine, the endothelium-independent vasodilator sodium nitroprusside, and occlusion-induced reactive hyperemia were measured plethysmographically in eight patients with TAO and in eight healthy control subjects matched for age and smoking status. The increase in FBF response to intra-arterial acetylcholine infusion was lower in patients with TAO than in healthy control subjects (peak FBF, 22.9 +/- 2.9 versus 14.1 +/- 2.8 mL/min per dL of tissue volume; P < .01). In contrast, there was no significant difference in the increase in FBF response to sodium nitroprusside infusion between the two groups (peak FBF 13.1 +/- 4.0 versus 16.3 +/- 2.5 mL/min per dL of tissue volume; P = NS). In the case of reactive hyperemia, there were no significant differences between the two groups at any time points of hyperemia (peak FBF, 32.9 +/- 4.0 versus 31.4 +/- 3.3 mL/min per dL of tissue volume; P = NS). CONCLUSIONS: These results indicate that peripheral endothelium-dependent vasodilation is impaired in the nondiseased limb of patients with TAO. This type of vascular dysfunction may contribute to such characteristics as segmental proliferative lesion and thrombus formation in the peripheral vessels of patients with TAO.

Acetylcholine↗
PubMed1996

Neural BC1 RNA in mouse skeletal muscle is a denervation-induced RNA whose expression is developmentally regulated.

We detected neural BC1 RNA in mouse skeletal muscle. The level of BC1 RNA was high in the fetus, but it declined progressively to the adult level as development proceeded. These observations suggest that this RNA is involved in the prenatal development and differentiation of muscles. Although its developmental expression correlates with the fetal period of polyneuronal innervation, BC1 RNA does not seem to play a direct role(s) in synaptogenesis, since its expression was not restricted to the neuromuscular junction. We also demonstrated that the BC1 RNA level in adult muscle was elevated after denervation, suggesting that changes in the activity of muscles or neural factors caused by axotomy, or both may result in BC1 RNA upregulation.

Actins↗
PubMed1996

A RING finger motif regulates transforming activity of the rfp/ret fusion gene.

The rfp/ret transforming gene was generated by DNA rearrangement which occurred during transfection of NIH 3T3 cells. The amino-terminal half of Rfp with a RING finger motif was fused to the truncated Ret receptor tyrosine kinase, leading to a transforming sequence, Rfp/Ret. In the present study, to elucidate the importance of a RING finger motif for its transforming activity, we mutated cysteine or histidine residues present in the motif that are believed to be crucial for the tertiary structure of the protein. Substitution of Cys-16, Cys-31, or His-33 markedly decreased the transforming activity of Rfp/Ret. These mutations also resulted in a striking decrease of tyrosine phosphorylation of the mutant proteins in transfectants. In contrast, mutations of Cys-118 or His-124 in the second cysteine/histidine-rich motif (called B box) of Rfp/Ret did not affect its activity. These results thus indicated that the RING finger structure is critical for the full transforming activity of Rfp/Ret.

3T3 Cells↗
PubMed1996

A mutation at tyrosine 1062 in MEN2A-Ret and MEN2B-Ret impairs their transforming activity and association with shc adaptor proteins.

Germ line mutations of the ret proto-oncogene are associated with the development of three dominantly inherited neoplastic disorders, multiple endocrine neoplasia (MEN) 2A, MEN 2B, and familial medullary thyroid carcinoma. It has been demonstrated that the mutations result in constitutive activation of the Ret protein, leading to transformation of NIH 3T3 cells. In the present study we investigated the role of tyrosine residues present in the carboxyl-terminal sequence for the transforming activity of Ret with the MEN 2A or MEN 2B mutation (MEN2A-Ret or MEN2B-Ret). Substitution of phenylalanine for tyrosine 1062 (designated Y1062F) markedly impaired the transforming activity of both MEN2A-Ret and MEN2B-Ret, whereas substitution or deletion for four other tyrosines (codons 981, 1015, 1090, and 1096) did not affect their activity. The Shc adaptor proteins bound to the MEN2A-Ret and MEN2B-Ret proteins and were phosphorylated on tyrosine in the transfectants. The binding of Shc to the Y1062F mutant proteins was reduced by approximately 80%, indicating that tyrosine 1062 is a major binding site for Shc. In addition, phosphopeptide analysis of MEN2A-Ret demonstrated that tyrosine 1062 represents an autophosphorylation site of the mutant Ret proteins.

Adaptor Proteins, Signal Transducing↗
PubMed1996

Swapping between Fas and granulocyte colony-stimulating factor receptor.

Fas belongs to the tumor necrosis factor/nerve growth factor receptor family. The Fas ligand binds to its receptor, Fas, and induces apoptosis in Fas-bearing cells. The granulocyte colony-stimulating factor receptor (G-CSFR) is a member of the hemopoietic growth factor receptor family. G-CSF induces its dimerization and regulates the proliferation and differentiation of neutrophilic granulocytes. We constructed hybrid receptors between Fas and G-CSFR and expressed them in the mouse T cell line WR19L or the mouse myeloid interleukin-3-dependent FDC-P1 cell line. The Fas ligand or an agonistic anti-Fas antibody stimulated proliferation of the FDC-P1 transformants expressing a chimera consisting of the Fas extracellular and G-CSFR cytoplasmic regions. On the other hand, G-CSF could not induce apoptosis in the transformants expressing the chimera consisting of the G-CSFR extracellular and Fas cytoplasmic regions, but these cells were killed by a polyclonal antibody against G-CSFR. These results indicated that receptors belonging to different receptor families can be functionally exchanged and confirm that a homodimer of G-CSFR can transduce the growth signal, whereas Fas must be oligomerized (probably trimerized) to transduce the apoptotic signal.

Animals↗
PubMed1996

Androgen insensitivity syndrome due to new mutations in the DNA-binding domain of the androgen receptor.

Androgen insensitivity syndrome (AIS) is associated with a wide range of quantitative or qualitative defects in the androgen receptor (AR). In some patients with AIS, however, no defects are detectable in the ligand-binding properties of the AR. We have analyzed the ARs of two unrelated patients with this category (termed 'receptor-positive type') of AIS. Sequence analysis of these patients' AR gene revealed single amino acid substitutions (579Cys(TGC)-->Phe(TTC) and 582Phe(TTC)-->Tyr(TAC)) in exon B encoding the first zinc finger of the DNA-binding domain of the AR. These mutations have not been previously reported. Moreover, cotransfection assays and mobility shift assays revealed that these patients' mutant ARs had defective transcriptional activity of the target gene because of impaired DNA-binding ability to the androgen-responsive element. These findings strongly indicate that these mutations are responsible for the pathogenesis of AIS in these patients.

Adult↗
PubMed1996

High-performance liquid chromatographic determination of pioglitazone and its metabolites in human serum and urine.

A high-performance liquid chromatographic (HPLC) method for the simultaneous determination of pioglitazone and its metabolites (M-I to M-V) in human serum and urine was developed. The method for serum involved the solid-phase and liquid-liquid extraction. Urine with and without enzymatic hydrolysis using beta-glucuronidase was treated with liquid-liquid extraction. The compounds in the extract were analyzed using HPLC with UV detection at 269 nm. The detection limits of pioglitazone, M-I, M-II, M-III, M-IV, and M-V in serum were 0.01-0.05 micrograms/ml, those in urine were 0.1-0.5 micrograms/ml, and those in urine after enzymatic hydrolysis were 0.3-0.5 micrograms/ml, respectively. The method was applied to the clinical trials of pioglitazone.

Calibration↗
PubMed1996

Identification of tyrosine residues that are essential for transforming activity of the ret proto-oncogene with MEN2A or MEN2B mutation.

The c-ret proto-oncogene with multiple endocrine neoplasia (MEN) 2A or 2B mutation can transform NIH3T3 cells with high efficiencies as a consequence of its constitutive activation. The MEN2A mutation induces ligand-independent homodimerization of the Ret protein on the cell surface while the MEN2B mutation appears to alter the catalytic activity without dimerization. In the present study, we investigated the role of tyrosine residues present in the kinase domain for the transforming activity of the mutant Ret proteins. Substitution of phenylalanine for tyrosine 905 (Y905F) that corresponds to tyrosine 416 of the Src protein abolished the transforming activity of Ret with the MEN2A mutation (MEN2A-Ret) but not with the MEN2B mutation (MEN2B-Ret). On the other hand, the transforming activity of MEN2B-Ret but not MEN2A-Ret significantly decreased by changing tyrosine 864 or 952 to phenylalanine. In addition, double mutations of these tyrosines (Y864/952F) completely abolished the activity of MEN2B-Ret. The Y905F and Y864/952F mutations resulted in severe impairment of the kinase activity of MEN2A-Ret and MEN2B-Ret, respectively. These results thus indicated that tyrosine residues essential for the transforming activity are different between MEN2A-Ret and MEN2B-Ret.

3T3 Cells↗
PubMed1996

Stress signal, mediated by a Hog1-like MAP kinase, controls sexual development in fission yeast.

We identified the phh1+ gene that encodes a MAP kinase as the effector of Wis1 MAP kinase kinase in fission yeast, which is highly homologous with HOG1 of S. cerevisiae. Heterothalic phh1 dsiruptant is phenotypically indistinguishable from wis1 deletion mutant, both displaying the same extent of partial sterility and enhanced sensitivity to a variety of stress. In phh1 disruptant, nitrogen starvation-induced expression of ste11+, a key controller of sexual differentiation, is markedly diminished. Ectopic expression of ste11+ effectively restores fertility, but not stress resistance, to the phh1 disruptant. These data show that stress signal, mediated by a MAP kinase, is required for efficient start of sexual differentiation.

Amino Acid Sequence↗
PubMed1996

Successful implantation of in vitro cultured rabbit embryos after uterine transfer: a role for mucin.

The functional role of the mucin layer for development of rabbit embryos was examined by uterine transfer of embryos with different thicknesses of mucin. Embryos collected at various intervals after human chorionic gonadotropin (hCG) injection were cultured until 90 hr post-coitum (p.c.) and transferred to the uterus of synchronized recipients. When embryos collected at 20 or 25 hr p.c. were used for transfer, no implantation occurred. By contrast, embryos collected at 35 or 40 hr p.c. developed to term at high rates (53 and 80%, respectively). The thickness of the mucin layer on the embryos was different between these two groups. Embryos collected before 25 hr p.c. have less than 11.2 +/- 0.2 microns of thickness of mucin and embryos collected after 35 hr p.c. have more than 34.3 +/- 5.5 microns. To examine whether mucin deposition is required for in vitro cultured rabbit blastocysts to continue development after uterine transfer, embryos were collected at 20 hr p.c., cultured for 60 or 70 hr in vitro, and then temporarily transferred to the oviducts of recipient does to add mucin. These embryos were recovered from the oviducts at 24 hr after transfer, classified according to the thickness of mucin deposition, and transferred again to the uterus of synchronized recipients. Twenty live young were obtained from 67 embryos with a 20-40 microns thick mucin layer. No live young were obtained from 57 embryos with less than a 20 microns thick mucin. The thickness of the mucin layer appears to be an important factor for successful implantation of rabbit embryos.

Animals↗
PubMed1996

Interaction of tobramycin and pH in cultured chick tibiae.

The toxicity of tobramycin at concentrations released from antibiotic-impregnated polymethylmethacrylate beads was determined using cultured embryonic chick tibiae. Because previous results from this laboratory have shown that osteoblast metabolism is inhibited at low pH and because of the potential for a low local pH in infected bone, the antibiotic was tested in medium with pH values from 6.8 to 7.4. Bone metabolism was evaluated by measuring the rates of glycolysis (lactate production), protein synthesis ([3H]proline uptake), and collagen synthesis ([3H]proline hydroxylation). Tobramycin at the concentrations released from the beads (1.0-1.5 mg/ml) contributed to lowering the pH of the medium. At pH 7.4, the antibiotic produced as much as a 30, 39, and 48% decrease in glycolysis, protein synthesis, and collagen synthesis, respectively. Tibiae exposed to tobramycin for 3 days, followed by 2 days without the antibiotic, showed only a partial recovery from its toxic effects. Although tobramycin was relatively less toxic in an acidic environment, the overall metabolic activity of the bones was poorest when the tobramycin concentration was high (2.0 mg/ml) and pH was low (6.8). The results of this study support the following conclusions: (a) tobramycin at high concentrations is toxic to bone, (b) a combination of high tobramycin concentration and low pH in the bone microenvironment may greatly inhibit bone metabolism, and (c) treatment and prevention of osteomyelitis by means of tobramycin-impregnated beads may be augmented by preventing the pH from decreasing in traumatized areas.

Animals↗
PubMed1996

Appendical fistulae formation as a complication of primary Crohn's disease prior to surgical management: report of a case.

We report herein the unusual case of a 55-year-old man who presented with primary Crohn's disease of the appendix with fistulae. In this patient there was no history of previous appendectomy. Although fistula formation around the orifice of the appendix after appendectomy for primary Crohn's disease of the appendix has been observed in a number of long-term follow-up studies, preoperative fistula formation is extremely rare.

Appendix↗
PubMed1996

The effectiveness of medroxyprogesterone in the treatment of multiple metastasizing leiomyosarcomas: report of a case.

A 51-year-old woman was admitted to our hospital for further investigation of chest X-ray films which showed multiple shadows that had been growing slowly over 2 years. Her only symptom was hemosputa. The lesions were suspected of being metastasizing leiomyoma due to her past history of uterine leiomyoma. Just 1 week before undergoing scheduled open lung biopsy, the lung lesions increased remarkably in size and number. A thoracotomy was performed and six of the numerous nodules were removed. The resected specimens were pathologically diagnosed as metastasizing leimyosarcoma which was positive for the progesterone and estrogen receptors. Thus, 1 month postoperatively, a course of medroxyprogesterone (MPA), 600 mg daily, was commenced. The residual lesions in her chest started to diminish, shortly afterward. She has remained well on this MPA regimen for 45 months. The prognosis of patients with metastasizing leiomyosarcoma is poor because of its low sensitivity to chemotherapy; however, some types of leiomyosarcoma are hormone-sensitive. It is therefore important to examine the hormone receptors of excised tumors from patients suspected of having metastasizing leiomyoma or leimyosarcoma.

Antineoplastic Agents, Hormonal↗
PubMed1996

Modified antigen-binding of human antibodies with glycosylation variations of the light chains produced in sugar-limited human hybridoma cultures.

We have characterized the effects of serum and N-acetylglucosamine in a glucose-deprived condition on the glycosylation of antibody light chains, as well as the resulting biological properties of those antibodies. We have chosen for our investigation the human hybridoma lines producing monoclonal antibodies reactive to lung adenocarcinoma. Each antibody possess a N-glycosylated carbohydrate chain in the hypervariable region of the light chains. When the cell lines were grown in the absence of glucose, variant light chains with varying molecular masses were found to be secreted. Analysis of these light chains produced in a glucose-deprived condition revealed that the changed molecular-mass of the variant light chains is due to different glycosylation. Addition of N-acetylglucosamine or fetal calf serum to the glucose-free medium led to the creation of other light chains that exhibit increased antigen binding activity.

Acetylglucosamine↗
PubMed1996

Prediction of prognosis by electron microscopic analysis of myeloma cells.

Myeloma cells were ultrastructurally analyzed in relation to survival in 54 patients with myeloma who were treated with melphalan-prednisolone or cyclophosphamide-prednisolone. Since previous studies by electron microscope had demonstrated that the degree of nuclear-cytoplasmic asynchrony of myeloma cells was associated with poor prognosis, this study focused on three kinds of nuclear abnormalities and eight kinds of cytoplasmic abnormalities. The patients were classified into three groups according to the presence of these abnormalities. The median survival times of the first group with five or fewer of 11 different kinds of abnormalities, the second group with 6-8 abnormalities and the third group with nine or more abnormalities were 2353, 531, and 115 days, respectively. Further more, this classification by ultrastructural abnormalities corresponded to those by the initial hemoglobin concentrations, platelet counts, and percentages of myeloma cells and plasmablasts in the bone marrow. These findings suggest that ultrastructural analysis of nuclear and cytoplasmic abnormalities, in addition to nuclear maturity, of myeloma cells may provide important information for predicting the prognosis in myeloma patients.

Bone Marrow↗