Biomedical subjects

M Ohta

Publications and source records attributed to M Ohta.

At least 721 records · Page 40Linked to original sources

PubMed1991

Relationships between energy level and insulin secretion in isolated rat islets of Langerhans. A study at various pH values.

To define better the role of [ATP]/[ADP] in insulin release from pancreatic islets, changes in the adenine nucleotide ratios elicited by alterations in external pH were correlated with the secretion profiles produced by administration of two metabolic secretagogues, 16 mM glucose and 10 mM alpha-ketoisocaproic acid. Experiments were carried out in buffers with and without bicarbonate, in the pH range 6.5-7.7. Insulin release was dependent on pHe irrespective of the secretagogue used. Secretion profiles for alpha-ketoisocaproic acid were the same both with and without bicarbonate; the release was decreased below pH 7.1 but maintained at 7.4-7.7. The same pattern was seen with glucose in media buffered with Hepes. With bicarbonate present, secretion caused by high glucose showed a bell-shaped dependence on [H+], with reductions at the acid and alkaline sides of pH 7.1-7.4. [ATP] and [ADP] were higher when Hepes was the buffer, at all pH values studied. The [ATP]/[ADP] declined with increasing pH under both basal and stimulated conditions; the values were always larger after stimulation although at pH 7.7 with bicarbonate present and glucose as the stimulant the difference was very small. It is concluded that: (i) the [ATP]/[ADP] in pancreatic islets is markedly dependent on pHe; (ii) there is no straight-forward correlation between either [ATP] or the absolute value for [ATP]/[ADP] and insulin secretion; and (iii) a rise in [ATP]/[ADP] is necessary for glucose-stimulated insulin release although it is not always the rate-determining event.

Adenosine Diphosphate↗

PubMed1991

Localization, isolation and properties of three NADPH-dependent aldehyde reducing enzymes from dog kidney.

Three kinds of NADPH-dependent aldehyde reducing enzymes were present in the dog kidney. Aldose reductase was located in the inner medulla region and aldehyde reductase in all regions of the renal cortex, outer medulla and inner medulla. In addition, a new reductase designated tentatively as high-Km aldose reductase, which was converted into an aldose reductase-like enzyme, was present in the inner medulla region of the kidney. Aldose reductase, aldehyde reductase and high-Km aldose reductase were purified to homogeneity from each region of the dog kidney. The molecular weight of aldose reductase was estimated to be 38,500 by SDS-polyacrylamide gel electrophoresis and the isoelectric point was found to be 5.7 by chromatofocusing. Aldose reductase had activity for aldo-sugars such as D-xylose, D-glucose and D-galactose as substrates and utilized both NADPH and NADH as coenzymes. Sulfate ions resulted in over 2-fold activation of aldose reductase. All aldehyde reductases from the three regions had the same properties. The molecular weights and isoelectric points of aldehyde reductases were 40,000 and 6.1, respectively. The aldehyde reductases were inactive for D-hexose, utilized only NADPH as coenzyme and were not affected by sulfate ions. High-Km aldose reductase had a molecular weight of 38,500 and an isoelectric point of 5.4. It had activity for aldo-sugars, but showed much higher Km and lower kcat/Km values than aldose reductase. Sulfate ions inhibited high-Km aldose reductase. It was converted into an aldose reductase-like enzyme by incubation in phosphate buffer at pH 7.0. The three kinds of enzymes were strongly inhibited by the known aldose reductase inhibitors. However, aldehyde reductase and high-Km aldose reductase were, in general, less susceptible than aldose reductase.

Alcohol Dehydrogenase↗

PubMed1991

Expression of a novel immediate early gene during 12-O-tetradecanoylphorbol-13-acetate-induced macrophagic differentiation of HL-60 cells.

Human promyelocytic leukemia cell line, HL-60, undergoes macrophagic differentiation when it is stimulated with TPA (12-O-tetradecanoylphorbol-13-acetate). We have cloned ETR101 cDNA whose mRNA was induced immediate early (30 min) and transiently by TPA. The mRNA is superinduced by addition of the protein synthesis inhibitor cycloheximide. The sequence of ETR101 cDNA (1826 base pairs) reveals that (i) it will encode a protein of 223 amino acids with a formula molecular weight of 24,200, (ii) the amino acid sequence is highly homologous to mouse chx1 protein whose mRNA was found recently to be enhanced in activated T lymphocytes in response to cycloheximide, (iii) the amino acid sequence is also weakly homologous to jun family gene products, and (iv) in the mRNA 3'-flanking region, there is a unique GUUUG sequence which is complementary to a part of B1 repetitive sequence and may be involved in mRNA degradation. ETR101 mRNA is induced by TPA in a wide variety of leukemia cells including myeloid, T-lymphoid, and B-lymphoid lineages. We have found that this mRNA is also induced by okadaic acid, a protein phosphatase inhibitor, and that TPA or cycloheximide act synergistically with okadaic acid. In addition, the induction is inhibited by protein kinase C inhibitors. Therefore, ETR101 mRNA level is controlled, either directly or indirectly, by protein phosphorylation.

Amino Acid Sequence↗

PubMed1991

The secretin precursor gene. Structure of the coding region and expression in the brain.

Secretin is a 27-amino acid gastrointestinal hormone that stimulates the secretion of bicarbonate-rich pancreatic fluid. We isolated and analyzed the coding region of the gene for the rat secretin precursor. The entire coding region spans 692 base pairs and is divided into four regions corresponding to the signal peptide and NH2-terminal peptide, the secretin peptide and processing signal sequences, a part of the COOH-terminal peptide, and the remainder of the COOH-terminal peptide, which are interrupted by three short introns (81, 105, and 104 base pairs). The organization is similar to those of the genes for other members of the secretin family, glucagon and VIP/PHI-27 precursors, supporting the assumption that the genes for the secretin family peptide precursors originated from a common ancestral gene. We also demonstrated that the secretin precursor gene is widely expressed in the brain and in the hypophysis. The regional expression pattern of the secretin precursor gene in the brain is quite different from those of the glucagon and VIP/PHI-27 precursor genes. The secretin precursor gene is highly expressed in the medulla oblongata and pons of the brain and the hypophysis, the expression levels of which are comparable to those in the duodenum. The secretin precursor mRNA in the brain and the hypophysis has the same coding sequence as that in the duodenum, indicating that secretin in the brain and the hypophysis is produced from the same secretin precursor protein as that in the duodenum. This is the first evidence to be reported that the secretin precursor gene is definitely expressed in the brain.

Amino Acid Sequence↗

PubMed1991

Clinicopathological study of pulmonary giant cell carcinomas with reference to prognosis of patients.

Giant cell carcinomas of the lung have been notorious in fulminant clinical courses. Thus, this report describes two exceptionally favorable cases among six cases of giant cell carcinoma of the lung. Their histopathological features are a sharply-demarcated tumor of Stage I, absence of vascular permeation of the cancer cells, prominent lymphoid and plasma cell infiltration in the tumor tissue, and lymph follicle formation in the surrounding tissues. Another case with a Stage II tumor showed the same histopathological findings as the above two cases with the exception of lymphatic permeation of the cancer cells. This patient expired about one year after undergoing an operation. As conventional controls, the remaining three cases with Stage III tumors showed an alveolar extension of tumor cells and vascular permeation. There was a fulminant course after the operation. Notwithstanding similar intervals from their clinical onset to operation in the 4 cases other than Cases 4 and 6, their stages showed considerable variations. Hence, each histopathological feature might have substantiated the different clinical courses following the operation. Electron microscopy of three of the cases indicated double-membrane-bound blisters with intermediate junctions in the bizarre giant cells, and cancer cell differentiation toward both glandular and squamous directions.

Aged↗

PubMed1991

Gene expression of fibroblast growth factor receptors in the tissues of human gliomas and meningiomas.

Northern blot analysis showed transcripts of two types of the fibroblast growth factor (FGF) receptor genes, flg and bek, in almost all the tissues samples of 18 human gliomas and 22 human meningiomas, which produced abundant basic and/or acidic FGF. From immunohistochemistry, FGF receptors were expressed in the tumor cells of a glioma and a meningioma. RNA expression of these FGF receptors was also detectable in normal human brains and normal bovine meninges. The expression level of either FGF receptor gene was not significantly different between tumor tissues and normal tissues.

Blotting, Northern↗

PubMed1991

Effects of novel aldose reductase inhibitors, M16209 and M16287, on streptozotocin-induced diabetic neuropathy in rats.

We investigated the effects of novel aldose reductase inhibitors, M16209 (1-(3-bromobenzo[b]furan-2-ylsulfonyl)hydantoin) and M16287 (1-(3-chlorobenzo[b]furan-2-ylsulfonyl)hydantoin), on neuropathy in streptozotocin-induced (STZ) diabetic rats. Both compounds (3-100 mg/kg per day, p.o.) dose dependently improved the decreased motor nerve conduction velocity in the sciatic nerve during a 14-day treatment period. These compounds also partially ameliorated the diabetes-induced histological changes in the sciatic nerve. A distinct increase in sorbitol content and a slight decrease in myo-inositol content was observed in the sciatic nerve of STZ diabetic rats, and the sorbitol accumulation was dose dependently suppressed by treatment with M16209 and M16287. Treatment started at an earlier period was more effective in the suppression of sorbitol accumulation. There was a significant correlation between motor nerve conduction velocity and nerve sorbitol content, whereas there was none between motor nerve conduction velocity and myo-inositol content. The present study indicates that M16209 and M16287 are potent aldose reductase inhibitors expected to be useful for the treatment of diabetic complications.

Aldehyde Reductase↗

PubMed1991

The expression of two isoforms of the human fibroblast growth factor receptor (flg) is directed by alternative splicing.

Structural analysis of the cDNA for the human fibroblast growth factor receptor (flg) revealed the existence of a larger and a shorter isoform of the receptor. The larger form has three extracellular immunoglobulin-like domains. On the other hand, the shorter form deletes the first (the most external) immunoglobulin-like domain region. Two consecutive amino acids (Arg Met) between the first and second immunoglobulin-like domains are sometimes deleted from the shorter form. In this paper, we isolated and analyzed the gene for the human fibroblast growth factor receptor. Organization of the gene revealed that the isoforms are produced by two different types of alternative splicing (the cassette and internal donor types) from the common gene. In human placenta, the shorter form is expressed as the major isoform.

Base Sequence↗

PubMed1991

Prognostic factors in yolk sac tumors of the ovary. A clinicopathologic analysis of 29 cases.

Twenty-nine ovarian cancer patients with yolk sac tumors and germ cell tumors with yolk sac tissue as a component of their disease (16 endodermal sinus tumor, 11 mixed germ cell tumors, one embryonal carcinoma, and one polyembryoma) were treated with cytoreductive surgery and combination chemotherapy. Prognostic factors were investigated in this group. Patients with Stage I disease had a more favorable prognosis (P less than 0.003) than those with Stages II and IV disease. The difference in prognosis was significant in cases where residual tumor was absent (P less than 0.003) and in cases where ascites was either absent or less than 100 ml in volume (P less than 0.05). Endodermal sinus tumor with either an intestinal (P less than 0.05) or microcystic pattern (P less than 0.01) was more common in survivors than in those who died. The age, preoperative serum alpha-fetoprotein level, maximum tumor size, and tumor weight had no significant correlation with prognosis. In advanced cases, chemotherapy regimens including cisplatin gave better results than those containing vincristine, dactinomycin, and cyclophosphamide (P less than 0.05). The optimal treatment of yolk sac tumors or tumors with yolk sac tissue as a component of the ovary is discussed in light of these results.

Adolescent↗

PubMed1991

Postoperative adjuvant chemotherapy in non-small cell lung cancer: prognostic value of DNA ploidy and post-recurrent survival.

Eighty-six patients with non-small cell lung cancer who underwent curative operations were postoperatively randomized to control and adjuvant chemotherapy groups. In the adjuvant chemotherapy group, patients received cisplatin-based combination chemotherapy 3 or 4 weeks after operation and the average cycle of chemotherapy was 2.3 (from 1 to 6 cycles). In this trial, no evidence of improved survival or delayed recurrence was seen in the treated patients. In multivariate analysis of prognostic variables, the most important factor was the pathological stage of the disease and, second, DNA ploidy of the primary tumor. Although histology (squamous vs. non-squamous cell carcinoma) had a trend to influence the survival, it was not a significant factor. A total of 33 patients had recurrences: 17 and 16 patients were in control and adjuvant chemotherapy groups, respectively. Postrecurrent survival in the adjuvant chemotherapy group was significantly shorter than that in the control group, as determined by the generalized Wilcoxon and log rank tests. Median survival time after recurrence in the control and adjuvant therapy groups was 18.5 and 7.5 months, respectively. These results suggest that DNA ploidy of primary tumors should be considered as a prognostic factor in future trials of adjuvant therapy. Furthermore, analysis of postrecurrent survival in the adjuvant chemotherapy trial, as well as that of overall and disease-free survivals should be done.

Aged↗

PubMed1991

Influence of surgical resection before and after chemotherapy on survival in small cell lung cancer.

We attempted to define the role of surgery in the treatment of small cell lung cancer (SCLC). Of 81 patients with clinically localized SCLC, 36 underwent surgical resection: 19 underwent initial resection with postoperative chemotherapy, while the remaining 17 were treated initially with chemotherapy, then resection. The remaining 45 patients were treated with a combination of chemotherapy and radiotherapy. The 5-year survival for the 36 surgical patients was 38%; median survival time (MST) was 33 months. Nineteen patients treated with postoperative chemotherapy showed a 42% 5-year survival, while 17 patients treated with preoperative chemotherapy showed a 33% 5-year survival. This difference was not significant. However, stage III survival tended to be better in patients with preoperative chemotherapy (MST, 29 months) than in those who had had postoperative chemotherapy only (MST, 17 months). Although survival of the 45 nonsurgical patients was poor, stage I and II patients, or those with complete remission showed a 25% 5-year survival with an MST of 33 months, and a 21% 5-year survival with an MST of 25 months, respectively. We thus concluded that initial resection combined with postoperative chemotherapy is beneficial for patients with stage I, and probably stage II disease. For resectable stage III, particularly in patients with N2 disease, adjuvant resection after chemotherapy may be a favorable choice in the management of SCLC. For advanced stage III, complete remission by chemotherapy should be attempted in combination with radiotherapy.

Aged↗

PubMed1991

Structures of asparagine-linked oligosaccharides from hen egg-yolk antibody (IgY). Occurrence of unusual glucosylated oligo-mannose type oligosaccharides in a mature glycoprotein.

Asparagine-linked oligosaccharides present on hen egg-yolk immunoglobulin, termed IgY, were liberated from the protein by hydrazinolysis. After N-acetylation, the oligosaccharides were labelled with a UV-absorbing compound, p-aminobenzoic acid ethyl ester (ABEE). The ABEE-derivatized oligosaccharides were fractionated by anion exchange, normal phase and reversed phase HPLC, and their structures were determined by a combination of sugar composition analysis, methylation analysis, negative ion FAB-MS, 500 MHz 1H-NMR and sequential exoglycosidase digestions. IgY contained monoglucosylated oligomannose type oligosaccharides with structures of Glc alpha 1-3Man7-9-GlcNAc-GlcNAc, oligomannose type oligosaccharides with the size range of Man5-9GlcNAc-GlcNAc, and biantennary complex type oligosaccharides with core region structure of Man alpha 1-6(+/- GlcNAc beta 1-4)(Man alpha 1-3)Man beta 1-4GlcNAc beta 1-4(+/- Fuc alpha 1-6)GlcNAc. The glucosylated oligosaccharides, Glc1Man8GlcNAc2 and Glc1Man7GlcNAc2, have not previously been reported in mature glycoproteins from any source.

4-Aminobenzoic Acid↗

PubMed1991

Giant extrathoracic hematoma after thoracoplasty--a case report.

A rare case of an extrathoracic giant hematoma developing after a thoracoplasty in a 67 year old man is presented herein. The patient underwent a right thoracoplasty without removal of plombage and a left thoracoplasty with removal of plombage for tuberculosis of the bilateral upper lobes 27 and 24 years prior to presentation, respectively. He presented to us in May, 1987, with a subscapular tumor which had been growing over the last 5 years. A giant tumor, measuring 23 x 17 x 12 cm and weighing 2585 g was successfully removed and the patient has since been well without any evidence of recurrence.

Aged↗

PubMed1991

DNA ploidy patterns of tumors diagnosed as metachronous or recurrent lung cancers.

The relationship between the first tumor and the second tumor resected in 8 patients with non-small cell lung cancer was analyzed using deoxyribonucleic acid (DNA) flow cytometry. Of the 8 patients, 6 were clinically diagnosed as having metachronous lung cancers and 2, local recurrent tumors. The mean interval between operations in patients with metachronous lung cancers was 62 months (range, 15 to 128 months). Both tumors showed the same histology in 4 patients and a different histology in 2. In the 2 patients with local recurrent tumors, the interval between operations was 9 months and 39 months. In the analysis of DNA flow cytometry of the first and second tumors in the same patient, the tumors were defined as independent of each other when one tumor showed diploidy and the other, aneuploidy, or when each DNA index of abnormal clones between two aneuploid tumors was different. When both tumors showed diploidy or when at least one DNA index of abnormal clones between two aneuploid tumors was identical, the tumors were defined to be related to each other. According to these criteria, in 5 (83%) of the 6 patients clinically diagnosed as having metachronous lung cancers, the second tumor was classified as independent of the first tumor. On the other hand, in the 2 patients clinically diagnosed as having recurrent tumors, the second tumor was judged to be related to the first tumor. These data suggest that DNA flow cytometric analysis of tumors may be of value in the diagnosis of metachronous lung cancers.

Adenocarcinoma↗

PubMed1991

Purification and characterization of human testis aldose and aldehyde reductase.

1. Aldose reductase and aldehyde reductase were purified to homogeneity from human testis. 2. The molecular weight of aldose reductase and aldehyde reductase were estimated to be 36,000 and 38,000 by SDS-PAGE, and the pI values of these enzymes were found to be 5.9 and 5.1 by chromatofocusing, respectively. 3. Aldose reductase had activity for aldo-sugars, whereas aldehyde reductase was virtually inactive for aldo-sugars. The Km values of aldose reductase for D-glucose, D-galactose and D-xylose were 57, 49 and 6.2 mM, respectively. Aldose reductase utilized both NADPH and NADH as coenzymes, whereas aldehyde reductase only NADPH. 4. Sulfate ion caused 3-fold activation of aldose reductase, but little for that of aldehyde reductase. 5. Sodium valproate inhibited significantly aldehyde reductase, but not aldose reductase. Aldose reductase was inhibited strongly by aldose reductase inhibitors being in clinical trials at concentrations of the order of 10(-7)-10(-9) M. Aldehyde reductase was also inhibited by these inhibitors, but its susceptibility was less than aldose reductase. 6. Reaction of aldose reductase with pyridoxal 5'-phosphate (PLP) resulted ca 2.5-fold activation, but aldehyde reductase did not cause the activation. PLP-treated aldose reductase has lost the susceptibility to aldose reductase inhibitor.

Alcohol Dehydrogenase↗

PubMed1991

Leupeptin causes an accumulation of lipofuscin-like substances in liver cells of young rats.

Leupeptin, a thiol protease inhibitor, has previously been shown to cause a dense accumulation of substances resembling age pigment and called ceroid-lipofuscin, in brain cells of young rats. Thus far, however, attempts to produce age pigments in hepatocytes of normal young rats with protease inhibitor(s) have not been successful. The present study provides the first demonstration that leupeptin induces lipofuscin-like substances in normal young rat hepatocytes. Male Fischer-344 rats (age 4-6 weeks) were continuously infused with leupeptin or saline i.p. for 2 weeks by an osmotic minipump (dosage, 1-50 mg/100 g per day). Liver tissues were then examined by light, fluorescence and electron microscopy. Both hepatocytes and non-parenchymal cells of livers treated with leupeptin, but not saline, showed a dense accumulation of pigments which stained deeply with toluidine blue, were PAS-positive and were brightly autofluorescent. After UV excitation the pigments had an emission spectrum with a broad peak at 480-540 nm extending to 650 nm resembling the spectrum of age pigment from livers of normal aged rats. Electron microscopic examination revealed numerous lipofuscin-like deposits with heterogeneous morphology in the cytoplasm of both hepatocytes and non-parenchymal cells; lipid and myelin-like bodies were also present in hepatocytes. The results indicate that the perturbation of proteolytic activity in liver by leupeptin causes an accumulation of substances which by several criteria resemble lipofuscin. These results thus provide further support for the 'Protease Inhibitor Model of Lipofuscin Formation' as well as a potential experimental model for studying hepatocellular aging processes.

Aging↗

PubMed1991

Immature teratoma of the ovary.

The purpose of this study was to establish the optimal management of immature teratoma of the ovary. Pursuant to this, 20 previously untreated patients with immature teratoma were evaluated. Nine patients were at stage I of the disease, 2 had progressed to stage II, and 9 to stage III. Eight patients had grade 1 tumors, 11 had grade 2 tumors, and 1 had a grade 3 tumor. Postoperative chemotherapy was performed in 19 cases. Vincristine, actinomycin D, and cyclophosphamide (VAC) were administered in 9 cases, chemotherapy including cisplatin (P) was administered in 8 cases, and other regimens were followed in the 2 remaining cases. The median follow-up period was 62 months (range 19-108 months), and no patient was lost to follow-up. After completion of the follow-up period, 18 patients were alive and disease free, 1 was alive with liver metastasis, and 1 had died. The patient who died had suffered from a grade 3 tumor, and the recurrent tumor was a rhabdomyosarcoma. As a result of this study, it was found that immature teratoma of grades 1 and 2 can be managed successfully with VAC or P therapy. Thus, a hysterectomy should not be automatically performed in patients who still hope to give birth, yet suffer from a grade 1 or 2 immature teratoma at the time of a second operation.

Abdominal Neoplasms↗

PubMed1991

Interleukin 1 production by monocytic leukemia cells and its possible role in coagulation abnormalities.

Interleukin 1 (IL-1) production by leukemic cells was studied in 16 patients with myelocytic or monocytic leukemia. Leukemic cells from the patients with monocytic leukemia showed higher IL-1 production than those with myelocytic leukemia. Subclinical coagulation abnormalities were observed more frequently in patients with higher IL-1 producing monocytic leukemia. It is suggested that IL-1 from leukemic cells might play important roles in the establishment of these clinical features. Such observations might be of value in the understanding of the pathophysiology of leukemia-associated paraneoplastic phenomena.

Adult↗