Biomedical subjects

Y Sakai

Publications and source records attributed to Y Sakai.

At least 343 records · Page 19Linked to original sources

PubMed1997

Isolation and amino acid sequence of flavostatin, a novel disintegrin from the venom of Trimeresurus flavoviridis.

Flavostatin, a novel disintegrin purified from the venom of Trimeresurus flavoviridis, consists of 68 amino acids, including an Arg-Gly-Asp sequence and 12 Cys residues at positions highly conserved among disintegrins. The N-terminal sequence of flavostatin was identical to those of triflavin and flavoridin, previously reported disintegrins from the Trimeresurus flavoviridis venom. Differences among the C-terminal sequences of these disintegrins are considered to affect their biological potencies. Isolated flavostatin inhibited ADP collage, and thrombin receptor agonist peptide-induced platelet aggregation in human platelet-rich plasma with an IC50 range of 59 to 98 nM. Contrary to expectations, these values were similar to those for triflavin.

Adenosine Diphosphate↗

PubMed1997

Gene expression of matrix metalloproteinase-1 (interstitial collagenase) and matrix metalloproteinase-3 (stromelysin-1) in basal cell carcinoma by in situ hybridization using chondroitin ABC lyase.

The gene expression of matrix metalloproteinase-1 and -3 was examined in basal cell carcinomas by in situ hybridization using digoxigenin-labelled riboprobes. Nodulo-ulcerative basal cell carcinomas demonstrated the gene expression for both metalloproteinases but superficial basal cell carcinomas did not present any transcripts for them. Transcripts for matrix metalloproteinase-1 (interstitial collagenase) were demonstrated densely in stromal cells among tumour masses, and those for matrix metalloproteinase-3 (stromelysin-1) were detected only in more advanced cases. Neither were expressed in tumour cells. The two metalloproteinases were produced by stromal cells according to the tumour invasion process, in which various growth factors, cytokines and inflammatory factors, which could regulate gene expressions of matrix metalloproteinases, were involved. It was also found that hybridization signals were enhanced by treatment with chondroitin ABC lyase, which digested abundant glycosaminoglycans in basal cell carcinoma. The procedure for the digestion is simple, and appears to be of value for in situ hybridization studies on tissues containing large amounts of glycosaminoglycans.

Basal Cell Carcinoma↗

PubMed1997

Sendai virus-based expression of HIV-1 gp120: reinforcement by the V(-) version.

BACKGROUND: We have established a system for recovering Sendai virus (SeV), a nonsegmented negative strand RNA virus, entirely from cDNA at an extremely high rate, and have succeeded in creating a V(-) SeV whose gene expression was greatly enhanced by the deletion of the nonessential V gene. Because of its extreme medical importance, there has been a strong need for the establishment of a better system to express the gp120 envelope glycoprotein of the human immunodeficiency virus type 1 (HIV-1) in sufficient quantity and purity. It also remains to be established to produce gp120 in in vitro natural host cells for HIV-1 such as human primary blood mononuclear cells, macrophages or established T cell lines. RESULTS: Using the above system, we created recombinant Sendai viruses expressing the gp120 in CV1 cells, a monkey kidney line. The expression level from the standard V(+) version has already reached 2.2/microg per 10(6) infected cells, which was readily purified from the culture fluid with a recovery rate of about 60%, and has so far appeared to be functionally and serologically authentic. The inserted gp120 gene was stably maintained during numerous passages of the recombinant virus. The V(-) version-based expression was even more robust, consistently reaching over 6.0 microg per 10(6) cells, a level that is one of the highest currently attainable for gp120 production in mammalian cells. Furthermore, a broad host range of SeV allowed gp120 production in all the three natural host cells for HIV-1 described above. CONCLUSIONS: SeV-based expression serves as a novel choice for producing large quantities of HIV-1 gp120 and will greatly facilitate biochemical, biological and immunological studies of this important glycoprotein.

DNA, Recombinant↗

PubMed1997

Impaired left ventricular diastolic filling occurs in diabetic patients without atherosclerotic coronary artery disease.

Using left ventriculography, left ventricular diastolic function was studied in 24 diabetic patients who had angina pectoris without atherosclerotic large-vessel coronary artery diseases (group A, 14 patients with exercise-induced ischemic ST-T changes as seen during electrocardiogram; group B, 10 patients without such changes). In groups A and B, the global peak filling rate was significantly less than that in control patients without diabetes or cardiac diseases. The ratio of the global time to the peak filling rate to the diastolic time was higher in both groups A and B than in the control groups. However, the total of time differences, defined as the sum of the time differences between global time to the peak filling rate and each of the three regional time to the peak filling rate, was greater in group A than in either group B or the control patients. Total time difference was similar in group B and the controls. Left ventricular diastolic filling was impaired in diabetic patients without large-vessel coronary artery disease. Impaired diastolic filling was present regionally in patients with ischemic ST-T change but globally in those without such change.

Adult↗

PubMed1997

Correction of pectus excavatum and pectus carinatum assisted by the endoscope.

Six patients with pectus excavatum and two patients with pectus carinatum had their conditions corrected by a partial costal cartilage resection with a sternal osteotomy through a 2.5-cm to 4-cm skin incision located just above the xyphoid process assisted by an endoscope. In addition to the incision, stab wounds of less than 3 mm in diameter were also made, in some cases, for insertion of the surgical instruments to facilitate the operation. The ribs and rib cartilages were exposed beyond the affected area through a prexyphoid incision under endoscopic control. The mobility of the skin incision site was thus enhanced, and it was possible to perform most of the subperichondrial partial costal cartilage resection under direct visualization. The pleura was freed from the sternum under endoscopic visualization. The advantages of this technique include minimal operative scars and the ability to free the pleura from the sternum under endoscopically magnified visualization, which prevents rupturing of the pleura in the retrosternal area.

Adolescent↗

PubMed1997

Creation of an infectious recombinant Sendai virus expressing the firefly luciferase gene from the 3' proximal first locus.

A genetic engineering approach was made to generate a recombinant non-segmented negative-strand RNA virus, Sendai virus (SeV) of the family Paramyxoviridae, that expresses firefly luciferase. The DNA construct containing the entire open reading frame (ORF) of the luciferase gene followed by the SeV transcription stop and restart signals connected with the conserved intergenic three nucleotides was inserted immediately before the ORF of the viral 3'-proximal nucleocapsid (N) protein gene in a full-length SeV cDNA copy. After intracellular expression of full-length antigenomic transcripts from the engineered cDNA and of the viral n ucleocapsid protein and RNA polymerase from the respective plasmids, a recombinant SeV expressing luciferase activity at a high level was recovered, although the tendency of this particular reporter gene product to aggregate in cells made it difficult to estimate the maximum level of expression. The increase in genome length brought about by inserting 1728 nucleotides into the 15,384 nucleotide parental SeV was associated with reduced plaque size, slightly slower replication kinetics and a severalfold decrease in yield of the virus. The inserted luciferase gene was stably maintained after numerous rounds of replication by serial passages in chick embryos. These results indicate the potential utility of SeV as a novel expression vector.

Animals↗

PubMed1997

Gastric stump carcinosarcoma with rhabdomyosarcomatous differentiation.

Gastric carcinosarcoma is an unusual tumor and its occurrence in the gastric stump is extremely rare. A report is presented here of a unique case of gastric stump carcinosarcoma with rhabdomyosarcomatous differentiation in a 74-year-old man. The patient had undergone partial gastrectomy with gastrojejunostomy (Billroth II method) 30 years previously. The tumor had both adenocarcinoma and sarcoma components, and an immunohistochemical study suggested a focal transition between these components. The main sarcomatous components showed fibrosarcomatous features with a scattered distribution of rounded tumor cells, whose rhabdomyosarcomatous differentiation was immunohistochemically determined. Ultrastructural examination supported the rhabdomyosarcomatous natures. Experience with the present tumor indicates that carcinosarcoma with rhabdomyosarcomatous differentiation can occur in the gastric stump and that this disease is capable of aggressive behavior.

Aged↗

PubMed1997

Clinicopathological characteristics of the focal and segmental form of idiopathic membranous nephropathy: comparison with the typical form of this disease.

Although idiopathic membranous nephropathy (IMN) is thought to represent a diffuse glomerulopathy, it was found that three of 31 children histologically diagnosed as IMN showed focal and segmental deposition of immunoglobulin G (IgG) and C3 on the glomerular capillary walls. The present study attempted to comparatively investigate clinical and pathological features of the diffuse group and the focal segmental group in 31 IMN children. Immunofluorescence study revealed that 28 of 31 IMN exhibited diffuse granular deposition of IgG along glomerular capillary walls. In contrast, focal and segmental deposition of IgG and C3 was noted in three children with IMN. In addition, focal and segmental electron-dense deposits were identified in these cases. In two children of the focal segmental group, immunofluorescent patterns of IgG deposition were unchanged even at the second biopsy. The focal segmental form of IMN tended to occur in younger children than diffuse IMN. However, other clinical parameters such as the range of proteinuria, hematuria, serum albumin and prognosis did not show any significant differences between both groups. Electrophoretic profiles of urinary proteins on sodium dodecylsulfate-polyacrylamide gel electrophoresis were not different between both groups. It is proposed that the focal segmental form of IMN may have a distinctive glomerulopathy from the typical form of IMN.

Child, Preschool↗

PubMed1997

Blood cardioplegia infusion using a recirculation type circuit generates bradykinin in significant amounts during open heart surgery.

The single pass type (SP) of blood cardioplegia is commonly used in North America during open heart surgery. However the recirculation type (RC) of blood cardioplegia is still widely used in other areas including Japan. Infusion blood cardioplegia using the latter technique often decreases the perfusion pressure. To determine the cause for this, blood levels of bradykinin (BK) were measured in cardiopulmonary bypass (CPB) and the 2 types of blood cardioplegic circuits. As the BK levels in the RC cardioplegia (>3,000 pg/ml) rose, the perfusion pressure decreased abruptly with the increase of the BK levels in the CPB circuit. With SP cardioplegia, the BK level was not increased either during cardioplegia (p < 0.009) or CPB (p < 0.009), and the perfusion pressure was not decreased (p < 0.02). We concluded that the SP circuit is superior to the RC one because of the lesser production of BK and thus lesser fluctuation of perfusion pressure.

Aged↗

PubMed1997

The physiological property and function of the electrolyzed-ionized calcium Aquamax on water molecular clusters fractionization.

Aquamax, the ionized mineral (Ca, 21 mg/ml; MG, 0.068 mg/ml; Na 0.13 mg/ml; K, 0.006 mg/ml) is a fermented organic mineral extract. The fundamental physiological property and function of this mineral is to promote the molecular level mineral supply to the cell inside. The contained minerals exist at a molecular level to fractionize the molecular clusters of water and to make water's penetration ratio into objects higher only at 0.1-0.2% concentration. Existing minerals, especially the calcium, were barely dissolved in water, and its low penetration was caused by its low electrolyzed behavior plus the effects from an anion mineral, such as phosphorous, sulfur, nitrogen, or any oxalic acid combining with a colloidal calcium to construct and crystallize as the calcium phosphate and the calcium sulfate. Aquamax minerals penetrate into objects to fractionize water molecular clusters and to make water functional, neutralize in the anion mineral and oxalic acid elements, raise the object's electric conductivity, and preserve perishables.

Calcium↗

PubMed1997

Electron microscopic studies of the early cellular events occurring in oral mucosa of rats affected by graft-versus-host disease (GVHD).

Previous histologic studies of tongue lesions in graft-versus-host disease (GVHD) in non-irradiated (Brown Norway x Lewis) F1 rats given parental spleen cells have demonstrated an increase in the number of MHC class II+ cells with dendritic shape in the lamina propria to be the earliest event in the development of the lesion. We studied this histologic finding by electron microscopy to increase understanding of the early cellular events occurring in the lesion. Electron microscopically, the most prominent cell type observed in the lamina propria was the cell with a dendritic shape. These dendritic cells possessed large nuclei that often showed irregular indentations and ample cytoplasm containing numerous filaments and mitochondria. A few lysosomal or phagocytic structures were also seen in the cytoplasm. No Birbeck granules were identified. These findings were very similar to those of indeterminate cells in the epidermis and dermis. Our data strongly support the hypothesis that MHC class II+ cells with dendritic shape present antigen during the induction of local immunological responses in the tongue of GVHD rats.

Animals↗

PubMed1997

Purification and properties of methyl formate synthase, a mitochondrial alcohol dehydrogenase, participating in formaldehyde oxidation in methylotrophic yeasts.

Methyl formate synthase, which catalyzes methyl formate formation during the growth of methylotrophic yeasts, was purified to homogeneity from methanol-grown Candida boidinii and Pichia methanolica cells. Both purified enzymes were tetrameric, with identical subunits with molecular masses of 42 to 45 kDa, containing two atoms of zinc per subunit. The enzymes catalyze NAD(+)-linked dehydrogenation of the hydroxyl group of the hemiacetal adduct [CH2(OH)OCH3] of methanol and formaldehyde, leading to the formation of a stoichiometric amount of methyl formate. Although neither methanol nor formaldehyde alone acted as a substrate for the enzymes, they showed simple NAD(+)-linked alcohol dehydrogenase activity toward aliphatic long-chain alcohols such as octanol, showing that they belong to the class III alcohol dehydrogenase family. The methyl formate synthase activity of C. boidinii was found in the mitochondrial fraction in subcellular fractionation experiments, suggesting that methyl formate synthase is a homolog of Saccharomyces cerevisiae Adh3p. These results indicate that formaldehyde could be oxidized in a glutathione-independent manner by methyl formate synthase in methylotrophic yeasts. The significance of methyl formate synthase in both formaldehyde resistance and energy metabolism is also discussed.

Alcohol Oxidoreductases↗

PubMed1997

Regulation of the formate dehydrogenase gene, FDH1, in the methylotrophic yeast Candida boidinii and growth characteristics of an FDH1-disrupted strain on methanol, methylamine, and choline.

The structural gene (FDH1) coding for NAD(+)-dependent formate dehydrogenase (FDH) was cloned from a genomic library of Candida boidinii, and the FDH1 gene was disrupted in the C. boidinii genome (fdh1 delta) by one-step gene disruption. In a batch culture experiment, although the fdh1 delta strain was still able to grow on methanol, its growth was greatly inhibited and a toxic level of formate was detected in the medium. In a methanol-limited chemostat culture at a low dilution rate (0.03 to 0.05 h[-1]), formate was not detected in the culture medium of the fdh1 delta strain; however, the fdh1 delta strain showed only one-fourth of the growth yield of the wild-type strain. Expression of FDH1 was found to be induced by choline or methylamine (used as a nitrogen source), as well as by methanol (used as a carbon source). Induction of FDH1 was not repressed in the presence of glucose when cells were grown on methylamine, choline, or formate, and expression of FDH1 was shown to be regulated at the mRNA level. Growth on methylamine or choline as a nitrogen source in a batch culture was compared between the wild type and the fdh1 delta mutant. Although the growth of the fdh1 delta mutant was impaired and the level of formate was higher in the fdh1 delta mutant than in the wild-type strain, the growth defect caused by FDH1 gene disruption was small and less severe than that caused by growth on methanol. As judged from these results, the main physiological role of FDH with all of the FDH1-inducing growth substrates seems to be detoxification of formate, and during growth on methanol, FDH seems to contribute significantly to the energy yield.

Amino Acid Sequence↗

PubMed1997

Importance of the cysteine-rich carboxyl-terminal half of V protein for Sendai virus pathogenesis.

The Sendai virus V protein is a nonstructural trans-frame protein whose cysteine-rich C-terminal half is fused to the acidic N-terminal half of the P protein via mRNA editing. We recently created a mutant by disrupting the editing motif, which is devoid of mRNA editing and hence unable to produce the V protein, and demonstrated that this V(-) virus replicated normally or even faster with augmented gene expression and cytopathogenicity in cells in vitro, but was strongly attenuated in pathogenicity for mice (A. Kato, K. Kiyotani, Y. Sakai, T. Yoshida, and Y. Nagai, EMBO J. 16:578-587, 1997). Thus, although categorized as a nonessential protein, the V protein appeared to encode a luxury function required for the viral in vivo pathogenesis. Here, we created another version of a V-deficient mutant, VdeltaC, encoding only the N-terminal half but not the V-specific C-terminal half, by introducing a stop codon in the trans-V frame, and then we compared its in vitro and in vivo phenotypes with those of the V(-) and wild-type viruses. The VdeltaC virus was found to be similar to the wild-type virus in vitro with no augmented gene expression and cytopathogenicity, but in vivo, it resembled the V(-) virus, displaying a similarly attenuated phenotype. Thus, the pathogenicity determinant in the V protein was mapped to the C-terminal half. The N-terminal half was likely sufficient to confer normal (wild-type) in vitro phenotypes.

Amino Acid Sequence↗

PubMed1997

Effect of enalapril maleate on cerebral blood flow in patients with chronic heart failure.

The effect of enalapril on cerebral blood flow (CBF) was studied in 11 patients with chronic heart failure (NYHA II or III, dilated cardiomyopathy in 6 and old myocardial infarction in 5). CBF was evaluated by analyzing the Patlak-Plot curve obtained from radionuclide angiography with technetium-99m hexamethylpropylene amine oxime (99mTC-HM-PAO). Cardiac index (CI) and stroke volume (SV) were simultaneously measured by impedance cardiography. These measurements were performed before and at four weeks after daily administration of 5 mg enalapril. The stroke volume, cardiac index, and heart rate were not significantly changed after four weeks of enalapril administration. However, CBF was increased by 6.5% from 36.72 +/- 4.66 to 39.13 +/- 5.65 mL/100g/min (P < 0.05). These results suggest that enalapril increased cerebral blood flow, which was not related to increased cardiac output in congestive heart failure. Patlak-Plot analysis of radionuclide angiography using 99mTC-HM-PAO may be available for quantitative assessment of brain perfusion.

Aged↗

PubMed1997

Treatment for advanced hepatocellular carcinoma by transarterial chemotherapy using reservoirs or one-shot arterial chemotherapy.

A prospective trial was performed in patients with advanced hepatocellular carcinoma to assess the therapeutic efficacy of transcatheter arterial chemotherapy using implanted reservoirs (12 patients) or conventional transcatheter arterial chemotherapy (8 patients). Epirubicin at a dose of 40 mg/m2 was given every month in the former, while epirubicin at a dose of 60 mg/m2 was administered every 3 months in the latter. During the 6 months from the introduction of these therapies, hospitalized periods were shorter and total hospital costs were less in the reservoir group than in the conventional chemotherapy group (p < 0.05 and p < 0.01, respectively). Transcatheter arterial chemotherapy using implanted reservoirs can be carried out on a day-care basis and may be beneficial for the treatment of patients with advanced hepatocellular carcinoma.

Aged↗

PubMed1997

Corticotropin-releasing factor up-regulates its own receptor gene expression in corticotropic adenoma cells in vitro.

To investigate the expression of CRF receptor (CRF-R) in human corticotropic adenoma (hCA) cells, we analyzed messenger RNA (mRNA) levels of type-1 CRF-R (CRF-R1). Adenomas were obtained from 10 patients with Cushing's disease. Northern blot analysis using a rat CRF-R1 complementary RNA probe revealed a main hybridization band of 2.7 kilobases in all the hCAs. The CRF-R1 mRNA level significantly increased after 1 h, reached 15-fold the basal level at 8 h, and remained elevated 24 h after the addition of 10 nmol/L CRF in vitro. Dose dependency of the stimulatory effect of CRF was also demonstrated in hCA cells, whereas CRF down-regulated CRF-R1 mRNA levels in rat anterior pituitary (AP) cells. Treatment with dexamethasone or vasopressin decreased the CRF-R1 mRNA level in hCA cells, as observed in rat AP cells. In conclusion, we detected CRF-R1 mRNA in all hCAs tested. The CRF-R1 mRNA level was up-regulated by CRF itself in cultured hCA cells, in contrast to the down-regulation in rat AP cells.

Adenoma↗

PubMed1997

Pyrrole butyric acid derivatives as inhibitors of steroid 5 alpha-reductase.

A series of pyrrole butyric acid derivatives was synthesized and evaluated for inhibitory activity on human and rat steroid 5 alpha-reductase in vitro and ex vivo. 3-Benzoyl-4-alkylpyrrole-1-butyric acids and 1-methyl-2-alkyl-3-benzoylpyrrole-5-butyric acid derivatives were effective inhibitors. Structure activity relationships were evaluated among the 37 compounds synthesized. Compound 37 (HQL-1069) shows potent inhibitory activities against both rat and human 5 alpha-reductase.

5-alpha Reductase Inhibitors↗