Search PubMed⌕ Search

Biomedical subjects

N Ishihara

Publications and source records attributed to N Ishihara.

At least 91 records · Page 5Linked to original sources
PubMed1988

Reduction of delta-aminolevulinate dehydratase concentration by bromobenzene in rats.

The effects of bromobenzene on delta-aminolevulinate (ALA) dehydratase (EC 4.2.1.24) were examined in rats. The enzyme in the bone marrow was irreversibly inhibited after 12 hours of treatment with bromobenzene (intraperitoneally) without any change in the enzyme concentration. When bromobenzene treatment was prolonged to 72 hours, the concentrations of the enzyme in the bone marrow and in the liver were reduced proportionally to the decrease in the enzyme activity. Neither the activity nor the concentration of ALA dehydratase in the peripheral erythrocytes were reduced even after 72 hours treatment with bromobenzene. These findings indicate that bromobenzene decreases ALA dehydratase activity in a biphasic manner; firstly, through an irreversible inhibition probably due to the formation of mercaptide with the essential SH groups and, secondly, through a reduced synthesis of the enzyme.

Animals↗
PubMed1988

Are blood platelets involved in the pathogenesis of ischemic brain edema in gerbils?

Edema formation following severe permanent or temporary cerebral ischemia in gerbils with an artificially reduced platelet count was investigated. Acute focal cerebral ischemia was produced by extracranial carotid ligation, and the local cerebral blood flow was estimated using the hydrogen clearance method. Brain tissue water and sodium and potassium contents were taken as indexes of brain edema. The platelet count was reduced in some gerbils by intravenous injection of neuraminidase. After 60 minutes of ischemia, a marked increase in tissue water and sodium contents accompanied by a decrease in potassium content was observed in untreated gerbils. However, gerbils with a reduced platelet count revealed similar but significantly smaller changes in all the measured parameters. Restoration of blood flow after 60 minutes of ischemia resulted in further accumulation of water and sodium and in depletion of potassium in both groups. These changes were significantly smaller in the gerbils with a reduced platelet count. It is concluded that platelets, activated by cerebral ischemia, may be involved in the development of ischemic brain edema in gerbils.

Animals↗
PubMed1987

CSF beta-endorphin and leu-enkephalin levels in the acute and chronic stages of cerebral infarction.

To investigate the role of endogenous opioid peptides in the pathophysiology of cerebral ischaemia, the CSF levels of immunoreactive beta-endorphin and leu-enkephalin in 16 patients with cerebral infarction were measured. Both the CSF beta-endorphin and leu-enkephalin levels in the acute stage of cerebral infarction were significantly higher than the values in the chronic stage. The CSF concentrations of the two peptides revealed a positive correlation in the acute but not the chronic stage. The increased endogenous opioid peptides in the CSF in the acute stage may modify the evolution of cerebral infarction.

Acute Disease↗
PubMed1987

Neoplastic endocrine cells in carcinomas of the small intestine: histochemical and immunohistochemical studies of 24 tumors.

Endocrine cells in 24 primary carcinomas and in the nonneoplastic mucosa of the small intestine were investigated histochemically and immunohistochemically with antisera against serotonin and 10 kinds of peptide hormones. Argyrophil-positive endocrine cells were found in four of eight duodenal, all of eight jejunal, and six of eight ileal carcinomas. The density of the positive cells was higher in the ileal tumors than in the duodenal and jejunal ones. Immunoreactive endocrine cells were detected in three duodenal, six jejunal, and five ileal carcinomas. Immunoreactive serotonin cells were present most frequently and most densely without respect to the site of origin of the carcinomas. In general, the population of endocrine cells among the tumor cells was higher in the ileal carcinomas than in the duodenal and jejunal ones. The ileal carcinomas frequently and densely demonstrated somatostatin, peptide YY, neurotensin, glucagon, and glicentin cells in addition to serotonin cells. The kinds of endocrine cells and the relative frequency of each kind of endocrine cell in carcinomas of the small intestine were similar to those in the nonneoplastic mucosa from which the carcinomas originated. This is the first systematic immunohistochemical study on endocrine cells in carcinoma of the small intestine.

Adult↗
PubMed1987

Effect of clofibrate on lipid peroxidation in rats treated with aspirin and 4-pentenoic acid.

The in vivo hepatic lipid peroxide content of rats was increased by aspirin or 4-pentenoic acid (4-PA) administration but was decreased by clofibrate (CPIB) administration. The increase by aspirin or 4-PA treatment was depressed by simultaneous administration of CPIB. However, the in vitro formation of lipid peroxide in liver mitochondria and microsomes of rats treated with CPIB as well as aspirin and 4-PA was also elevated compared to that of control rats. The formation of lipid peroxide in mitochondria and microsomes of control rats in vitro was depressed by the addition of cytosols obtained from untreated (control), aspirin-treated, 4-PA-treated, and CPIB-treated rats, but was not depressed by the addition of albumin or heated cytosols. The most effective depression was obtained by the addition of cytosol obtained from CPIB-treated rats. In addition, glutathione peroxidase activity and nonprotein sulfhydryl content in cytosol obtained from CPIB-treated rats were elevated compared to those from control, aspirin, and 4-PA-treated rats. The results suggest that the action of CPIB may be mainly related to the increase of cytosolic glutathione peroxidase activity and nonprotein sulfhydryl content. Hepatic triglyceride and phospholipid contents of rats treated with aspirin or 4-PA were increased compared to those of control rats. These increases were also reversed by simultaneous administration of CPIB.

Animals↗
PubMed1987

Bilateral thalamic infarction associated with selective downward gaze paralysis.

A 34-year-old man presented with transient downward gaze paralysis and impairment of convergence together with prominent psychic disturbances. Cranial CT and MRI clearly demonstrated a symmetric infarction extending from the bilateral thalamus to the rostral medial midbrain. The existence of downward gaze paralysis following ischemic stroke is contributory to the diagnosis of not only the location of but also the responsible artery for the infarction.

Adult↗
PubMed1986

Dual effect of naloxone on blood platelet aggregation and cerebral blood flow in gerbils.

The effect of naloxone on blood platelet aggregation and cerebral blood flow in gerbils was studied. Administration of naloxone in dose 1 mg/kg to intact gerbils resulted in a marked increase in platelet aggregability accompanied by 27% reduction in cerebral blood flow. Focal cerebral ischemic injury significantly enhanced platelet aggregatory response and treatment with naloxone was without any additional effect on platelet aggregation. Cerebral blood flow in ischemic hemisphere, however, increased following naloxone injection by 46%. In vitro naloxone in millimolar concentrations inhibited platelet aggregation in a dose-dependent way. Apparent decrease in fluorescence of platelet membranes tagged with fluorescence probe due to naloxone suggests conformational changes in platelet membrane as a primary mechanism for the antiaggregatory effect of naloxone in vitro.

Animals↗
PubMed1986

Comparison of the effects of urinary flow on adjusted and non-adjusted excretion of heavy metals and organic substances in 'healthy' men.

The effect of variation in urinary flow rate (ml urine min-1, UF) on adjusted and non-adjusted urinary excretion of metals and organic substances was examined in ten 'healthy' men. The effect of UF was found to be eliminated when urinary concentrations of lead (Pb), hippuric acid (HA), delta-aminolevulinic acid (ALA) and coproporphyrin (CP) were adjusted to urinary specific gravity and to UF. Similarly, the effect of UF on inorganic mercury (Hg) was eliminated when the concentration was adjusted to timed excretion and to UF. The effect on zinc (Zn) and copper (Cu) was eliminated when adjusted to urinary creatinine (Cn) and to UF. The difference in the effect of UF on the adjusted urinary excretion was explained by the effect of UF on timed excretion of substance, which was ranked in the following order: Pb, HA, total urinary solutes, ALA and CP; Zn; Cu; Cn; and Hg. It was concluded that 'UF-adjusted concentration' is applicable to measurement of all substances in urine as a method of minimizing UF effects, while the other three adjustment methods have only limited uses.

Adult↗
PubMed1986

Effect of clofibrate on cholesterol metabolism in rats treated with polychlorinated biphenyls.

Serum and hepatic cholesterol content in rats treated with polychlorinated biphenyls (PCBs, KC-400) were increased compared to those of control rats. This increase of cholesterol content was reduced to control level by simultaneous administration of ethyl p-chlorophenoxyisobutyrate (CPIB). Also, when lecithin-cholesterol acyltransferase (LCAT) (EC. 2.3.1.43) activity was expressed as the net cholesterol esterification, the acyltransferase activity in rats treated with PCBs was elevated, while the elevated acyltransferase activity was brought to control level by simultaneous administration of CPIB. On the other hand, the amount of bile of rats treated with CPIB, PCBs and PCBs-CPIB was increased, but free and total cholesterol content in bile of these treated rats was decreased to 40-60% of those of control rats. Moreover, cytochrome P-450 content in liver microsomes of rats treated with CPIB, PCBs and PCBs-CPIB was increased. At the same time, cholesterol-metabolizing activity in liver microsomes of rats treated with CPIB, PCBs and PCBs-CPIB also was elevated. Similar results were obtained for drug metabolizing (aniline hydroxylation and aminopyrine N-demethylation) activity. In addition, the amount of bile acids excreted from rats treated with CPIB, PCBs and PCBs-CPIB was increased compared to that of control rats. These results suggest that hypercholesterolemia induced by oral ingestion of PCBs is recovered by CPIB treatment and that this hypocholesterolemic effect of CPIB may be related partly to the elevation of hepatic mixed function oxidase activity for cholesterol catabolism.

Animals↗
PubMed1986

Peptide YY immunoreactive cells in gastrointestinal carcinoids: immunohistochemical and ultrastructural studies of 60 tumors.

The distribution and frequency of peptide YY (PYY) cells in 60 gastrointestinal carcinoids and in the nonneoplastic mucosa around the carcinoids were studied by an indirect immunoperoxidase method with anti-PYY serum. Additionally, the endocrine cell type of the PYY cells in appendiceal and rectal carcinoids was assessed by transmission electron microscopy. A few PYY cells were present in specimens of nonneoplastic mucosa from stomach, duodenum, jejunum, ileum, and appendix, with an abundance of these cells in rectal mucosa. Peptide YY cells were found in one of 13 gastric, one of 13 duodenal, one of one jejunal, zero of two ileal, three of 11 appendiceal, and 16 of 20 rectal carcinoids. All but one of the PYY-positive carcinoids were argyrophil carcinoids. Peptide YY cells in the gastric, duodenal, and jujunal carcinoids were present in small numbers. The three PYY-positive carcinoids of the appendix were composed almost totally of PYY cells, whereas those of the rectum generally contained only sporadic PYY cells. The peptide YY cells observed ultrastructurally contained almost round secretory granules (about 160 nm in average diameter), which were most consistent with D1(H) cell type granules with respect to shape and average diameter. This is the first systematic immunohistochemical and ultrastructural study of PYY cells in gastrointestinal carcinoids.

Carcinoid Tumor↗
PubMed1986

A neuroendocrine (Merkel) cell carcinoma with coexisting intraepidermal squamous cell carcinoma of the skin. Its growth accelerated by an extrinsic factor.

A case of neuroendocrine (Merkel) cell carcinoma with coexisting intraepidermal squamous cell carcinoma of the skin was studied histologically, immunohistochemically and ultrastructurally as well as with tissue-culture and transplantation into nude mice. The primary tumor found in the lower leg of a 68-year-old Japanese man had remained thumb-sized for five years and, after contusion, had begun to enlarge rapidly up to 5 cm in size during one month. The patient died of metastatic neuroendocrine cell carcinoma nine months after excision of the primary tumor. Histologically the primary tumor was composed of neuroendocrine cell carcinoma extending down to subcutaneous adipose tissue and a small amount of intraepidermal squamous cell carcinoma, not associated with a wide range of necrosis, hemorrhage, granulation tissue or fibrosis. The tumor cells of the former were diffusely positive for neuron-specific enolase. They contained a few secretory granules, 100 nm in diameter. The tumor cells both cultured in media and transplanted into nude mice died two months later. The present case is the first report of Merkel cell carcinoma in which the growth accelerated by an extrinsic factor was proved. Histogenesis of neuroendocrine cell carcinoma with coexisting squamous cell carcinoma is also discussed.

Adenocarcinoma↗
PubMed1986

A case report on human type B botulism.

A case of type B human botulism was found in Tochigi Prefecture in November, 1984. Botulinum type B toxin was detected in the serum and feces of the patient. The serum toxin was activated by trypsinization. Type B toxin was demonstrated in cooked meat medium cultures of the fecal specimens. The patient recovered after administration of type A, B, E and F quadrivalent antitoxin.

Botulinum Toxins↗