Search PubMed⌕ Search

Biomedical subjects

M Miyata

Publications and source records attributed to M Miyata.

At least 163 records · Page 9Linked to original sources
PubMed1997

Expression, purification, and characterization of enzyme IIA(glc) of the phosphoenolpyruvate:sugar phosphotransferase system of Mycoplasma capricolum.

The gene encoding enzyme IIA(glc) (EIIA) of the phosphoenolpyruvate:sugar phosphotransferase system of Mycoplasma capricolum was cloned into a regulated expression vector. The purified protein product of the overexpressed gene was characterized as an active phosphoacceptor from HPr with a higher pI than previously described EIIAs. M. capricolum EIIA was unreactive with antibodies directed against the corresponding proteins from either Gram-positive or Gram-negative bacteria. Enzyme IIA(glc) behaved as a homogeneous, monomeric species of 16,700 Mr in analytical ultracentrifugation. The circular dichroism far-UV spectrum of EIIA reflects a low alpha-helical content and predominantly beta-sheet structural content: temperature-induced changes in ellipticity at 205 nm showed that the protein undergoes reversible, two-state thermal unfolding with Tm = 70.0 +/- 0.3 degrees C and a van't Hoff deltaH of 90 kcal/mol. Enzyme I (64,600 Mr) from M. capricolum exhibited a monomer-dimer-tetramer association at 4 and 20 degrees C with dimerization constants of log K(A) = 5.6 and 5.1 [M(-1)], respectively, in sedimentation equilibrium experiments. A new vector, capable of introducing an N-terminal His tag on a protein, was developed in order to generate highly purified heat-stable protein (HPr). No significant interaction of EIIA with HPr was detected by gel-filtration chromatography, intrinsic tryptophanyl residue fluorescence changes, titration calorimetry, biomolecular interaction, or sedimentation equilibrium studies. While Escherichia coli EIIA inhibits Gram-negative glycerol kinase activity, the M. capricolum EIIA has no effect on the homologous glycerol kinase. The probable regulator of sugar transport systems, HPr(Ser) kinase, was demonstrated in extracts of M. capricolum and Mycoplasma genitalium. Gene mapping studies demonstrated that, in contrast to the clustered arrangement of genes encoding HPr and enzyme I in E. coli, these genes are located diametrically opposite in the M. capricolum chromosome.

Chromosome Mapping↗
PubMed1997

Characterization of dnaA gene expression in Mycoplasma capricolum.

Expression of the dnaA gene in Mycoplasma capricolum was studied. The transcriptional start site was located 10 bp upstream from the putative translational initiation codon. Immunoblotting analysis revealed that DnaA protein was expressed at the levels significantly larger than those in Escherichia coli, and was localized mainly in the membrane. The transcriptional level of dnaA gene was reduced by inhibition of DNA synthesis with methyl methanesulfonate or mitomycin C, while the level of DnaA protein did not change. Reduction of protein synthesis did not significantly affect the total amount of DnaA protein, suggesting that the rates of synthesis and degradation of the protein are slow. These observations showed that the expression pattern of dnaA gene in M. capricolum is different from those of walled bacteria in some aspects.

Amino Acid Sequence↗
PubMed1997

Simultaneous observation of endocrine and exocrine functions of the pancreas responding to somatostatin in man.

Six patients who underwent segmental autotransplantation of the caudal pancreas (SAT) following total pancreatectomy for pancreatic cancer were investigated. The graft was transplanted to the left groin, and pancreatic juice was diverted outside through a polyethylene tube indwelled into the main pancreatic duct. In these SAT patients, the responses of insulin (IRIS) in terms of plasma levels and pancreatic secretion to subcutaneous injections of somatostatin octreotide (Sandostatin: SMS201-995) were simultaneously observed. Four doses (0.039, 0.156, 0.625 and 2.5 micrograms/kg) of SMS201-995 were given on separate days. As a control, saline was injected subcutaneously. Standard liquid test meal was given 1 h after the subcutaneous injection. The basal plasma IRI were significantly decreased with doses greater than 0.156 microgram/kg. The postprandial responses of IRI was also significantly suppressed with the same doses. On the other hand, the basal pancreatic exocrine secretion was significantly suppressed with doses greater than 0.625 microgram/kg. The postprandial pancreatic exocrine secretion was also significantly suppressed with doses greater than 0.625 microgram/kg. Those suppressions were dose-dependent. The postprandial CCK secretion was also significantly suppressed in dose-dependent manner with SMS201-995. The CCK suppression was significantly correlated with the suppression of pancreatic exocrine secretion. This clinical study under the setting of SAT demonstrated not only the direct inhibitory effect of somatostatin on both the islet and acinar cells but also, probably, the indirect inhibitory effect on the acinal cells via suppression of CCK release in humans.

Aged↗
PubMed1997

Clinical investigation of colorectal cancer detected by follow-up colonoscopy after endoscopic polypectomy.

PURPOSE: We analyzed the results of a long-term follow-up surveillance of patients with colorectal polyps after endoscopic polypectomy in terms of the cumulative incidence of subsequent colorectal cancer and the clinicopathologic characteristics of carcinomas detected by colonoscopy. METHOD: The study cohort consisted of 6,715 patients who had received endoscopic resection of single or multiple colorectal polyps and then underwent periodic colonoscopy (or a combination of sigmoidoscopy and barium x-ray examination in some cases) during an average follow-up of six years (40,622 person-years in total). RESULTS: During the follow-up, 31 cases of colorectal cancer containing 15 submucosal invasive carcinomas (T1,N0,M0) and 16 advanced carcinomas were detected. The cumulative incidence of colorectal cancer was analyzed for four subgroups of the 6,715 patients classified according to the diameter, grade of dysplasia, and histologic features of polyps. Furthermore, the depth of invasion, macroscopic configuration of submucosal invasive cancer, and site of colorectal cancer observed in the 31 cases were compared with those of a reference group of 1,497 patients with colorectal cancer treated at Takano Hospital during the same period. Submucosal invasive cancer was the most common type among the colorectal carcinomas detected during follow-up. In terms of macroscopic configuration of submucosal cancer, the superficial type was significantly more common than the protruded type. The superficial submucosal cancer showed a significantly longer interval to detection than the protruded submucosal cancer. By site of lesion, proximal colon cancer was significantly more common. CONCLUSION: Follow-up colonoscopy appears to be useful in patients with larger polyps (>5 mm). Patients with severe dysplasia and those with malignant polyps should be followed-up carefully. Because submucosal cancer detected by follow-up examination after polypectomy showed higher rates of superficial-type cancer and proximal colon cancer, careful endoscopic examination of the entire colon is important.

Adenomatous Polyps↗
PubMed1997

A case of Sjögren's syndrome associated with Sweet's syndrome.

We report a case of Sjögren's syndrome whose clinical course had been indolent until the patient presented with Sweet's syndrome (acute febrile neutrophilic dermatosis). This patient showed renal failure and renal tubular acidosis. Sweet's syndrome resolved within 3 weeks without corticosteroid therapy. Renal biopsy findings were consistent with interstitial nephritis. His renal manifestations responded to corticosteroid therapy and the renal function remained stable during 6 years follow-up without recurrence of Sweet's syndrome. Although close association of both syndromes is already known, in our case Sjögren's syndrome may have been exacerbated by occurrence of Sweet's syndrome.

Acute Kidney Injury↗
PubMed1997

Histometric analysis of the distal pancreas in pancreatic head cancer.

To clarify the histological status of the pancreas tail after pancreatoduodenectomy (PD), fibrosis, islets of Langerhans, and A, B, and D cells were examined histometrically in surgical cases of pancreatic cancer. The same investigations were also performed during an autopsy examination of the pancreas tail of survivors of surgery who had received either PD or total pancreatectomy with segmental autotransplantation (SAT). In the surgical cases, fibrosis and the islet percentage compared with nonpancreatic cancer cases were significantly higher while the B cell ratio was significantly lower. In addition, in pancreatic cancer patients, the fibrosis and islet ratio in the group with a blocked pancreatic duct were higher while the B cell ratio was lower than in the group with an open pancreatic duct. A direct relationship between the islet ratio and the degree of fibrosis, and an inverse relationship between the B cell ratio and the degree of fibrosis, were thus found. From the autopsy cases, the fibrosis progressed and the islet ratio increased following PD, but after SAT only the islet ratio increased compared to the time of surgery. The progression of fibrosis after PD thus suggests the presence of some problems in both the surgical method and postoperative management.

Adult↗
PubMed1997

Prevention of graft rejection and graft-versus-host reaction by a novel immunosuppressant, FTY720, in rat small bowel transplantation.

In the present study, we examined the immunosuppressive effect of a new drug, FTY720, on small bowel transplantation (SBT) in rats. Grafts from (LEW x BN) F1-to-LEW rats treated with FTY720 at 0.5 mg/kg from day 0 to 14 post-SBT survived significantly longer than untreated grafts. In addition, the administration of FTY720 combined with cyclosporin (CyA; 5 mg/kg per day) had a synergistic effect on allograft survival. The graft-versus-host reaction (GVHR) that occurred in the LEW-to-F1 rats was markedly reduced after the administration of FTY720. FTY720 combined with a low dose of CyA completely abrogated GVHR without any adverse reaction. FTY720 treatment resulted in a significant decrease in the number of lymphocytes in the peripheral blood and the spleen, but the number of peripheral neutrophils was unchanged. Thus, FTY720 would appear to be an ideal drug to combine with CyA in order to control the immune reaction after SBT.

Animals↗
PubMed1997

Hormone-cytokine response. Pneumoperitoneum vs abdominal wall-lifting in laparoscopic cholecystectomy.

BACKGROUND: Changes in blood hormone and cytokine were investigated in patients who underwent laparoscopic cholecystectomy via insufflation (CO2 group) vs those who had abdominal wall-lifting (Air group). METHODS: Seventeen female patients with cholecystolithiasis were randomly divided into two groups. Peripheral blood samples were obtained during perioperative period, and plasma hormone levels (ACTH, cortisol) and serum cytokine levels (TNFalpha, IL-1beta, IL-6, IL-10) were measured. RESULTS: The number of circulating lymphocytes significantly decreased at 1 h after surgery in both groups, but the decrease in the CO2 group was significantly smaller than that in the Air group. There was no significant difference in hormone elevation between groups. Serum concentrations of IL-6 and IL-10 in the Air group were significantly higher than in the CO2 group. CONCLUSIONS: CO2 insufflation may reduce cytokine production in laparoscopic cholecystectomy.

Abdominal Muscles↗
PubMed1997

Sexual co-flocculation by heterothallic cells of the fission yeast Schizosaccharomyces pombe modulated by medium constituents.

Novel simple synthetic media for inducing sexual co-flocculation in a short time after mixing heterothallic fission-yeast (Schizosaccharomyces pombe) cells of h- and h+ were devised; The most effective of these, mannose synthetic medium (MSM), contains 0.4% mannose as a carbon source in addition to galactose, KH2PO4 (pH4.0) and 4 vitamins. The addition of galactose to the medium suppressed the asexual self-flocculation but rather promoted the sexual co-flocculation. By transferring and mixing h- and h+ cells grown in malt-extract broth plus galactose into MSM, these heterothallic strains were revealed to be sexually ready through a long period of the log to stationary phases. Furthermore, a variety of C sources and NH4Cl at various concentrations in various media were examined for their effects upon sexual co-flocculation, conjugation and sporulation; it was found that the sugar concentration strictly affected the progress of the sequence of sexual reproduction at 26 degrees C but not 30 degrees C and that sexual co-flocculation of the heterothallic strains was induced only under lower concentrations of C and N source than that for the homothallic one.

Ammonium Chloride↗
PubMed1997

Down-regulation of 5-hydroxytryptamine7 receptors by dexamethasone in rat frontocortical astrocytes.

Astrocytes derived from rat frontal cortex contain 5-hydroxytryptamine7 (5-HT)7 receptors positively coupled to adenylyl cyclase. In the present study, we investigated the effects of glucocorticoids on adenylyl cyclase activity and 5-HT7 receptor gene expression in astrocytes. Addition of dexamethasone (0.01-100 nM, 12-72 h) to the culture medium decreased cyclic AMP formation induced by 5-HT in a time- and concentration-dependent manner. Dexamethasone treatment (10 nM, 48 h) reduced maximum responses of cyclic AMP formation induced by 5-HT and 5-carboxamidotryptamine without alterations in the EC50 value. In contrast, treatment with the mineralocorticoid aldosterone (48 h) had no significant effects on 5-HT-induced cyclic AMP formation with concentrations up to 10 nM. It was observed that dexamethasone treatment (1-100 nM, 3-72 h) also decreased the expression of 5-HT7 receptor mRNA, using reverse transcription and polymerase chain reaction analysis. A significant reduction in expression of 5-HT7 mRNA appeared at 3 h of dexamethasone treatment and reached a maximum at 6 h of treatment. On the other hand, dexamethasone treatment (10 nM, 48 h) did not affect basal levels of cyclic AMP and cyclic AMP synthesis stimulated by isoproterenol, N-ethylcarboxamidoadenosine, cholera toxin, and forskolin. These results suggest that dexamethasone decreases the expression of the 5-HT7 receptor gene and, consequently, 5-HT7 receptor-mediated signal transduction in frontocortical astrocytes.

Adenosine↗
PubMed1997

Role of endogenous somatostatin in postprandial hypersecretion of neurotensin in patients after gastrectomy.

OBJECTIVE: The purpose of this report is to elucidate the mechanism of the hypersecretion of neurotensin (NT) after gastrectomy. SUMMARY BACKGROUND DATA: NT secretion induced by fat ingestion is increased after pancreatoduodenectomy or distal gastrectomy. The hypersecretion of NT in the patients undergoing resection of the upper gastrointestinal tract is suppressed by an exogenous somatostatin (SST) analog. METHODS: We observed simultaneously the secretion of NT and SST in the same patients before and after gastrectomy (n = 7). We also observed the secretion of these hormones induced by intraduodenal (ID) fat infusion in the normal volunteers (n = 6). RESULTS: The response of plasma NT to fat ingestion was significantly increased after gastrectomy compared with that before gastrectomy. The response of plasma SST after gastrectomy was significantly suppressed. The response of plasma NT and SST after ID fat infusion in the normal volunteers was similar to the gastrectomized state. CONCLUSION: Diminution of SST secretion, probably caused by the lack of SST cells in the distal part of the stomach, may play a role in augmenting NT secretion after gastrectomy.

Aged↗
PubMed1997

Characteristics of IgA anti-HIV antibodies in plasma from patients with HIV infection.

The concentration of total IgA and the specificity and molecular size of IgA anti-human immunodeficiency virus (HIV) type-1 antibodies in plasma obtained from individuals at different stages of HIV infection were analyzed. The concentration of total IgA in the plasma was not decreased even in the late stage of HIV infection, in contrast with those of total IgG and IgM. The IgA anti-HIV antibodies differed to the IgG anti-HIV antibodies in their specificity as determined by Western blotting. The IgA antibodies mainly bind to Env glycoproteins. The IgA anti-HIV antibodies in plasma were detected between IgG and IgM by gel filtration, suggesting the presence of polymeric IgA anti-HIV antibodies. These results indicate that the production of non-specific IgA in plasma is enhanced by unknown mechanisms in every stages of HIV infection, and suggest that IgA anti-HIV antibodies in plasma which are possibly polymeric and have unique specificity may play an important role in HIV infection.

Antibody Specificity↗
PubMed1997

Ultrastructural study of antral G cells in patients with duodenal ulcer: effect of Helicobacter pylori eradication.

BACKGROUND: It is established now that Helicobacter pylori infection is associated with exaggerated gastrin release to meals and other stimuli and that the abnormal secretion of gastrin is reversed after successful treatment of the infection. By comparing morphology of G cells from the same patients before and after treatment, we were able to investigate the ultrastructural effect of cure of H. pylori on G cells. METHODS: Gastric mucosal biopsy specimens were obtained from 10 patients with duodenal ulcer before and 3, 6, and 9 months after cure of H. pylori infection. Negative controls consisted of four healthy volunteers without H. pylori infection. G cells were evaluated by immunohistochemical and electron microscopy. Treatment with H2-antagonists was continued for 6 months after cure of the H. pylori infection. RESULTS: Ultrastructural studies of secretory granules of antral G cells in controls displayed a broad range of electron density ranging from dark with a full appearance to totally electron-lucent with a "vacuolating" appearance. In duodenal ulcer patients before treatment, electron-lucent vacuolating granules predominated. After elimination of H. pylori, G-cell granules showed a marked increase in electron density close to that of controls. CONCLUSIONS: Our study showed that the density of granules of G cells is decreased in H. pylori-infected duodenal ulcer patients compared to that in H. pylori-negative controls and is consistent with enhanced gastrin release. Cure of H. pylori infection was associated with return to normal density of G-cell granules.

Anti-Bacterial Agents↗
PubMed1997

Enhanced interleukin-8 production by cultured Chang liver cells subjected to ethanol exposure and subsequent stimulation with tumor necrosis factor-alpha.

We investigated the production of interleukin-8 (IL-8) and chemotactic activity released from Chang liver cells subjected to long-term treatment with ethanol (Et) and subsequent stimulation with tumor necrosis factor-alpha (TNF-alpha). Chang liver cells were cultured in the presence of 5, 50 or 100 mmol/l Et for 4 weeks and then treated with recombinant TNF-alpha (1, 10, 100 U/ml). The culture supernatants were assayed for IL-8 using a sandwich ELISA and chemotactic activity was measured using a chemotactic chamber. Total RNA was also extracted from these cells and IL-8 mRNA was assayed by RT-PCR. In addition, TNF-receptor expression on the Et-treated cells was analyzed by flow cytometry. IL-8 levels in supernatants of cells stimulated with 100 U/ml of TNF-alpha for 48 h rose significantly with increasing concentrations of Et and values obtained were as follows: 4,918 +/- 244.4 pg/ml at 0 mmol/l Et, 5,335 +/- 266.2 pg/ml at 5 mmol/l Et, 8,726 +/- 873.4 pg/ml at 50 mmol/l Et and 9,134 +/- 866.0 pg/ml at 100 mmol/l Et. The chemotactic activity also increased with increasing concentrations of Et and was almost completely suppressed by anti-IL-8 antibody. Using semiquantitative analysis of radioactivity of IL-8 mRNA using a 32P gamma ATP-labeled primer for IL-8 mRNA, Et-treated cells were shown to have markedly higher levels of radioactivity than untreated cells. In addition, TNF-receptor expression was significantly higher in cells treated with 100 mmol/l Et. These data suggest that long-term Et treatment of Chang liver cells stimulated with TNF-alpha may enhance transcription of the IL-8 gene with up-regulation of the TNF receptor.

Antibodies↗
PubMed1997

Severe hypertriglyceridemia caused by tamoxifen-treatment after breast cancer surgery.

Tamoxifen, a nonsteroidal estrogen antagonist, has been widely used in a hormonal treatment for breast cancer. The side effects of tamoxifen are generally recognized to be mild. However, we experienced three cases of severe hypertriglyceridemia and/or hyperglycemia induced by tamoxifen. For normalization of their hypertriglyceridemia we need to stop giving tamoxifen. In one of three cases we analyzed her lipoprotein profile in detail with lipoprotein lipase activities and apolipoprotein E phenotype. The case was a 49 year-old woman. After 15 months of tamoxifen administration, she was diagnosed as severe hypertriglyceridemia. Consecutively, severe hyperglycemia was occurred to need insulin therapy. After tamoxifen withdrawal, her triglyceride and glucose levels improved. Her lipolytic enzyme was reduced during tamoxifen treatment. Apolipoprotein E phenotype was uncommon E4/2. Although hypertriglyceridemia was not considered to be a risk factor for coronary heart disease, a marked hypertriglyceridemia might occasionally produce severe lethal pancreatitis. We recommend that a periodic plasma lipid analysis is needed for patients treated with tamoxifen, especially for diabetic and hypertriglyceridemic patients, to avoid such complications.

Antineoplastic Agents, Hormonal↗
PubMed1997

[A case of multiple endocrine neoplasia type I with primary hyperparathyroidism, prolactin secreting pituitary microadenoma and gastrin secreting duodenal carcinoid].

A case of MEN type I in a 64-year-old man is reported. He had undergone partial duodenectomy because of gastric ulcer and multiple duodenal polyps (gastrin secreting carcinoid). Blood examination revealed hypercalcemia, hyperPTHemia, and hyperprolactinemia. Neck US and CT showed enlargement of 4 parathyroid glands. Brain MRI revealed the microadenoma in left pituitary gland. Total parathyroidectomy with auto-transplantation in the left forearm were performed. Histological examination showed the hyperplasia of the parathyroid. Three and a half year after parathyroidectomy, there was no evidence of recurrence of gastrin secreting tumor and hyperparathyroidism, and enlargement of pituitary microadenoma. This is the first MEN type I case in Japan which have detected 3 endocrine tumors clinically with gastrin secreting duodenal carcinoid.

Adenoma↗