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Biomedical subjects

J Ogata

Publications and source records attributed to J Ogata.

At least 109 records · Page 6Linked to original sources
PubMed1988

Mortality and histological findings of the brain during and after cerebral ischemia in male and female spontaneously hypertensive rats.

Mortality and pathological changes of the brain during and after cerebral ischemia induced by bilateral carotid artery occlusion (BCO) were studied in male and female spontaneously hypertensive rats (SHR). Systolic arterial blood pressure at rest was significantly higher in male SHR (228 +/- 13 mm Hg, mean +/- S.E.M.) than female (192 +/- 12) (P less than 0.05). The average survival time during permanent occlusion was 11 +/- 6 h (mean +/- S.D.) in male SHR and 17 +/- 7 in female (P less than 0.005), though the cumulative mortality during 24-h ischemia was not different between male (88%) and female SHR (84%). Severe ischemic changes of nerve cells in the brain, especially in the cortex and hippocampus, were observed in 50% of male SHR at 3-h ischemia, while only 15% was observed in female SHR even after 7-h ischemia. After the temporary ischemia followed by reperfusion for 24 h, the mortality was varied between male and female SHR; 0, 31 and 100% after 1-, 3- and 5-h ischemia, respectively, in male SHR and 0% after 1- to 3-h ischemia and 33% after 5- to 7-h ischemia, respectively, in female. Ischemic changes of the brain tissue, such as acidophilic cytoplasm, nuclear degeneration and intercellular edema, were more frequent and severe in male SHR than female after recirculation following 3- or 5-h ischemia. It is concluded that the mortality and post-ischemic viability seem to be determined by the duration of ischemia and also by the degree of the neuronal damage, and female SHR is more tolerated for ischemic insult in comparison to male SHR.

Animals↗
PubMed1988

Regulation of prostaglandin synthesis by reduced glutathione in urinary bladder epithelium.

A possible mechanism is presented by which reduced glutathione (GSH) regulates prostaglandin (PG) synthesis in microsomes of the porcine bladder epithelium. At a concentration of GSH less than 10(-5) M, microsomes produced more PGI2 and PGF2 alpha than PGE2. At a greater GSH concentration, PGE2 synthesis was remarkably enhanced. On the other hand, PGI2 and PGF2 alpha synthesis was inhibited. In the presence of 10(-3) M GSH, ten times more PGE2 was produced than the other PGs. The concentration of GSH in porcine bladder epithelium was about 0.6 mM. This reciprocal effect of GSH was also observed in rabbit and bovine bladder epithelium. These findings suggest that GSH is involved in the regulation of PG synthesis in urinary bladder epithelium. GSH may influence the physiological and pathophysiological changes elicited by PGs in the lower urinary tract.

Animals↗
PubMed1988

Effect of continuous intravesical infusion of low-concentrated mitomycin-C on bladder carcinogenesis in rats treated with N-butyl-N-4-hydroxybutyl-nitrosamine.

In the first experiment, histological changes of urinary bladder after long-term transvesical catheterization were evaluated in normal rats. No malignant changes of the bladder epithelium were detected in the two and four-week catheterization groups. However incidences of papilloma and papillary carcinoma developed in three of the five rats (60%) in the eight-week group. In a second experiment the therapeutic effect of continuous or intermittent administration of MMC on bladder carcinogenesis in rats treated with N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) was examined. MMC at a total dose of four mg. was administered for two weeks in both therapeutic groups. Continuous infusion was performed transvesically using an osmotic pump and a silicone catheter, on the basis that preliminary examination revealed the urinary delivery rate of MMC was constant for two weeks. In the intermittent group, MMC solution was instilled transurethrally with a venural catheter twice a week. The continuous infusion of low concentrated MMC reduced significantly (p less than 0.02) the incidence of tumor development in spite of extended catheterization (for eight weeks) into the bladder. However, the intermittent instillation of high concentrated MMC hardly inhibited the development of bladder tumors. We should consider the optimal concentration and time of a drug in intravesical chemotherapy based on the above findings.

Administration, Intravesical↗
PubMed1988

Clinical choroidal thrombosis, hypertension, and diabetes mellitus: an electron microscopic study.

Changes in the choroidal artery were examined at autopsy in 16 Japanese patients with hypertension and insulin-dependent diabetes mellitus. These changes could be divided into 1) arteriosclerotic ones consisting of intimal thickening due to migration of smooth muscle cells, 2) hyaline deposits in the subendothelium, 3) extensive degeneration (moth-eaten atrophy and necrosis) of medial smooth muscle cells, and 4) changes resulting from fibrinoplatelet thrombi and their organization (recanalization and obstruction). The intimal thickening and medial damage correlated with aging, were accelerated by hypertension, and were remarkable in arterioles less than 60 micron in diameter. Diabetes mellitus apparently did not enhance these vascular changes. Thrombotic occlusion or narrowing of the choroidal artery was frequently observed in the arterioles of patients with hypertension and diabetes mellitus who had chronic azotemia or renal insufficiency. Subendothelial hyaline deposits were increased in patients with diabetes. The narrowing or obstructive changes in the choroidal artery were extensive in the intraocular blood vessels. These changes may be secondary and induce damage to other intraocular blood vessels and tissues, including the retina.

Aged↗
PubMed1988

Primary brainstem death: a clinico-pathological study.

A case of primary brainstem death in a man with surgically treated cerebellar haemorrhage is reported. Necropsy revealed extensive necrosis confined to the brainstem and cerebellum. The absence of diabetes insipidus and the persistence of electroencephalographic activity were the characteristic clinical features of the case. This differentiates the condition from so-called "whole brain death". Analysis of three further cases with acute vascular lesions of the brainstem or cerebellum, shown at necropsy, revealed that primary brainstem death with prolonged somatic survival can occur in specific circumstances after surgical intervension.

Brain Death↗
PubMed1987

Carbon dioxide reactivity of cerebral cortical and pial arteries in spontaneously hypertensive and normotensive rats--a morphometric study.

The responsiveness of cerebral arteries to the changes in arterial carbon dioxide tension (paCO2) was studied in spontaneously hypertensive rats (SHRs) and normotensive rats (NTRs). A freeze substitution method was applied for the preparation of pial and cortical arteries for morphometrical study. Hypercapnia was induced by giving 8% CO2, and hypocapnia was provided by hyperventilation. The ratios of internal (d) to external diameter (D) (d/D ratio) of both pial and cortical arteries in SHR were not different from those in NTRs during normocapnia. In hypercapnia, the ratios of pial and larger cortical arteries (D greater than or equal to 20 micron) in SHRs were 80.9 +/- 0.8% and 78.6 +/- 0.6%, respectively, being significantly smaller than 86.2 +/- 0.7% and 82.2 +/- 0.5% in NTR. In contrast, the d/D ratio of pial arteries in hypocapnia was 72.5 +/- 1.4% in SHRs, which was significantly larger than 67.5 +/- 1.4% in NTRs. The responsiveness of smaller cortical arteries (D less than 20 micron) to paCO2 was not different between SHRs and NTRs. The present results suggest that in SHRs cerebrovascular CO2 reactivity is decreased as compared to NTRs, especially in pial and larger cortical arteries.

Animals↗
PubMed1987

Lipid composition of the plasma membrane isolated from normal and precancerous rat bladder epithelium.

Four-week-old Wistar strain rats were given 0.05% N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) solution for 12 weeks and used as a precancerous model. Sixteen-week-old rats of the same strain were used as controls. Plasma membranes (PMs) were prepared from normal and precancerous bladder epithelium. The lipid content and the fatty acid compositions of total lipids, phospholipids, and their subclasses were analysed. The following observations were made: 1) Precancerous PMs had longer chains composed of more unsaturated fatty acids than the normal ones. 2) There were high amounts of arachidonic acid in rat bladder epithelium, and it accounted for more than fifty percent of phosphatidylethanolamine. PMs of precancerous epithelium had more arachidonic acid than those of the normal epithelium. These findings may be useful for the early detection of precancerous epithelium.

Animals↗
PubMed1987

Role of the kallikrein-kinin system in two-kidneyed and one-clipped hypertensive rats.

The influence of aprotinin as a kallidinogenase inactivator on the antihypertensive effect of angiotensin I converting enzyme inhibitor (CEI) was studied in two-kidneyed and one-clipped hypertensive rats. Sixteen two-kidneyed and one-clipped hypertensive rats and sham-operated normotensive rats were prepared for this experiment. They were divided into two groups: those with the aprotinin infusion and those without. The effects of the oral administration of CEI were compared as regards mean arterial pressure (MAP) and urinary kallikrein activity (UKA). In 8 hypertensive rats under glucose infusion, MAP fell from 184.4 +/- 4.5 to 106.3 +/- 5.2 mm Hg, and UKA changed from 1.37 +/- 0.18 nkat/12 h to 0.61 +/- 0.11 nkat/12 h after the administration of CEI. In the remaining hypertensive rats under aprotinin infusion, MAP decreased from 175.0 +/- 3.0 to 140.6 +/- 5.1 mm Hg, and UKA slightly changed from 0.72 +/- 0.25 nkat/12 h to 0.59 +/- 0.12 nkat/12 h. Thus, the decrease of MAP after the administration of CEI was suppressed by the aprotinin infusion, and this significant difference was supported by the decrease of UKA. As for 16 normotensive rats, CEI did not alter MAP, nor did aprotinin have any effect on it. However, UKA tended to decrease after the administration of CEI. These results suggest that both the kallikrein-kinin system and the renin-angiotensin system play an important role in the maintenance of high blood pressure in two-kidneyed and one-clipped chronically hypertensive rats.

Animals↗
PubMed1987

[A case of virilizing adrenocortical carcinoma in an adult female with increased urinary excretion of catecholamines].

We report a rare case of virilizing adrenocortical carcinoma with increased urinary excretion of catecholamines. A 53-year-old woman was admitted because of a huge abdominal mass. A child's-head-size mass was palpable in the right upper quadrant. IVP, CT scan and angiography revealed a characteristic picture of an adrenal tumor. Urinary catecholamines and vanilmandelic acid were increased slightly. The urinary 17 ketosteroid level was very high (59.0 mg per day) and was not suppressed by a dexamethasone test. Exploratory laparotomy revealed that the tumor was fixed and had infiltrated to the vena cava, aorta and liver. Therefore, chemotherapy was performed. The dosage of op'-DDD was increased gradually to 9 g daily. During this treatment, a 5-days' course of treatment with cis-platinum (50 mg/day) was repeated 2 times. This patient achieved partial response according to Koyama-Saito's criteria. However, she died 18 months after the first admission. On autopsy, determined histopathologically that she died of adrenocortical carcinoma arising from the adrenal gland. However systemic lymph node, bone and lung metastases were also revealed. There is a possibility that this tumor secreted both sex steroids and catecholamines.

Adrenal Cortex Neoplasms↗
PubMed1986

Autolysis of the granular layer of the cerebellar cortex in brain death.

In a study of duration of brain death, granular layer autolysis (GLA) of the cerebellar cortex was analyzed in 45 patients who died of acute cerebrovascular diseases (CVDs). Twelve patients who died of causes other than intracranial disease served as controls. Tonsillar herniation occurred in all who died of acute CVDs. More advanced GLA was seen in the central folia adjacent to the central white medullary body of the cerebellum as compared with the peripheral folia. Widespread GLA involving the most of the peripheral folia was found solely in patients in whom brain death had been present over 18 h. Of the 12 control patients, 4 showed GLA only in the central folia. Although GLA of the central folia might develop during immersion fixation of the brain, the alteration of the peripheral folia is assumed to develop in the period of brain death. Widespread GLA extending to the peripheral folia could be a pathological finding characteristic of brain death, where intracranial blood flow could be absent or significantly reduced. Brain death for little less than 1 day would be necessary for GLA to develop.

Adult↗
PubMed1986

A case of hypertension due to unilateral hydronephrosis in a child.

A case of hypertension secondary to unilateral hydronephrosis due to congenital obstruction of ureteropelvic junction in a 6-year-old boy is reported. Preoperatively, the plasma renin activity (PRA) in the peripheral vein and in the affected kidney was elevated. Blood pressure decreased significantly following administration of converting enzyme inhibitor. After nephrectomy, peripheral vein PRA and blood pressure returned to normal, despite withdrawal of antihypertensive medication and sodium restriction. Histological examination of the resected kidney revealed prominent hyperplasia of juxtaglomerular cells. These results strongly suggest that, in this case, hypertension was renin-dependent.

Child↗
PubMed1986

Reversal of multidrug resistance by synthetic isoprenoids in the KB human cancer cell line.

A colchicine resistant clone, Chr-24, derived from the human carcinoma KB cell line is extensively resistant to multiple drugs including vinblastine, vincristine, Adriamycin, actinomycin D, and daunomycin. In comparison with KB cells, very low accumulation of daunomycin or vincristine is observed in multidrug-resistant cells. Two isoprenoids with 9 to 10 isoprene chains (polyprenoids), N-(p-methylbenzyl)decaprenylamine and N-solanesyl-N,N'-bis(3,4-dimethoxybenzyl)ethylenediamine overcame the multidrug resistance almost completely in cultured Chr-24, whereas they only slightly sensitized the parental KB cells to anticancer agents. Both isoprenoids enhance the accumulation of vincristine or daunomycin in Chr-24, possibly by inhibiting efflux and also by enhancing influx of anticancer agents. A verapamil-like structure of N-solanesyl-N,N'-bis(3,4-dimethoxybenzyl)ethylenediamine is discussed in relation to its ability to overcome drug resistance.

Antineoplastic Agents↗
PubMed1985

Nucleotide sequences of two mRNAs for rat brain myelin proteolipid protein.

The 3200 and 1600 nucleotide mRNAs encoding rat brain proteolipid protein (PLP), the major protein component of central nervous system myelin, are heterogeneous at their 5' ends, differ in their 3' polyadenylation sites, and are transcribed from a single gene. The mRNAs, which first appear postnatally, encode identical 277 amino acid proteins that are 99% identical to the bovine protein sequence. Thus, PLP has been highly conserved during mammalian evolution. A single amino-terminal methionine is removed post-translationally, indicating that PLP does not require a signal peptide sequence for insertion into the myelin membrane. Mouse and monkey utilize the 3200 but not the 1600 nucleotide mRNA, suggesting that there is no functional necessity for two sizes of rat PLP mRNAs.

Amino Acid Sequence↗
PubMed1985

A case of hemangiomyoma of the ureter in a child.

Herein a rare case of hemangiomyoma of the ureter in a child is reported. Benign mesodermal tumors of the ureter are not common, particularly in a child. Two cases of leiomyoma of the ureter in childhood have been reported to date. This is the first case of ureteral hemangiomyoma in a child. Nephroureterectomy was performed and the subsequent clinical course reveals no evidence of recurrence.

Child↗