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Biomedical subjects

H Kanai

Publications and source records attributed to H Kanai.

At least 73 records · Page 4Linked to original sources
PubMed1998

[Histological and morphometrical studies on small arteries in normal brainstems with special reference to the pathogenesis of the hypertensive brainstem hemorrhage].

Plasmatic arterial necrosis and microaneurysm of small arteries are preceded by smooth muscle cell loss and the rupture of these arterial lesions is a direct cause of hypertensive intracerebral hemorrhage. The hypertensive brainstem hemorrhage occur exclusively in the pons. To elucidate whether there are differences of underlying arterial lesions between each part of the brainstem or not, small arteries in normal 34 autopsied brainstems were investigated histologically and morphometrically. Histological study revealed the predilection of the occurrence of plasmatic arterial necrosis, microaneurysms and fibronodular arterial lesions in the hypertensive pons. These lesions occurred predominantly in the small arteries 100-300 microns in diameter in the basal part of hypertensive pons, and were rare in the other parts of hypertensive brainstems and in normotensive brainstems. A negative correlation between the ratio of number of smooth muscle cell nuclei to the area of tunica media and age was demonstrated morphometrically. The ratio in the hypertensive group was significantly lower than that of the normotensive group. In addition the mean ratio in the pons was significantly lower than that in the midbrain and the medulla oblongata in the hypertensive group. These results are consistent with the fact that the hypertensive brainstem hemorrhage predominantly occur in the pons and primary bleedings in the other parts of the brainstem are rare.

Aged↗
PubMed1997

Changes of immunoreactive neuropeptide Y, somatostatin and corticotropin-releasing factor (CRF) in the brain of a novel epileptic mutant rat, Ihara's genetically epileptic rat (IGER).

Ihara's genetically epileptic rat (IGER) is a rat mutant with genetically scheduled spontaneous convulsions mimicking human limbic seizures. In the present study, the possible changes of three neuropeptides, neuropeptide Y (NPY), somatostatin (SRIF) and corticotropin-releasing factor (CRF), in the brains of IGER were investigated. Increased contents of immunoreactive (IR) NPY were found only in the hippocampus of 2-month IGERs before developing convulsive seizures, while similar increases of IR-NPY were discovered in the striatum and pyriform and entorhinal cortex as well as hippocampus in 8-month IGERs with repetitive seizures. There were no significant differences in the brain contents of IR-SRIF and IR-CRF between IGERs and the controls at both ages. These findings indicate an enhanced rate of NPY synthesis in this experimental model of epilepsy which may play a critical role in the development of epileptogenesis.

Animals↗
PubMed1997

Immature teratoma producing alpha-fetoprotein without components of yolk sac tumor in the pineal region.

A case of pineal region tumor in a 9-year-old boy with a high serum alpha fetoprotein (AFP) level is reported. The serum levels of beta-human chorionic gonadotropin (HCG) and placental alkaline phosphatase (PLAP) were not elevated. The tumor was composed of radiologically different components and was removed surgically. Postoperative radiation therapy was performed and the serum level of AFP gradually declined to the normal range. The pathological diagnosis was immature teratoma, and no elements of yolk sac tumor or embryonal carcinoma were found. In the immunohistochemical study, AFP was detected in the cytoplasm of gastrointestinal-type epithelium and primitive neuroepithelial element. This is considered a rare case of intracranial immature teratoma in which AFP was detected immunohistochemically in the columnar epithelium and immature neural tissue.

Biomarkers, Tumor↗
PubMed1997

Role of serotonin in nephrotoxic serum nephritis in WKY rats.

Our objective was to determine whether serotonin is involved in inducing nephrotoxic serum nephritis in WKY rats. After injection of antiglomerular basement membrane antiserum, urinary protein excretion was significantly decreased in rats treated with the serotonin receptor antagonist, MCI-9042, and in rats treated with p-chlorophenylalanine. Similarly, severe necrotizing lesions and crescent formation were inhibited in a dose-dependent manner by treatment with MCI-9042 and p-chlorophenylalanine. The number of intraglomerular ED-1-positive cells was increased on day 3 and thereafter in the placebo group. A significant increase in the number of crescent lesions was observed in the placebo group on day 7 and thereafter. Neither adenosine diphosphate- nor collagen-induced platelet aggregations were inhibited in platelet-rich plasma from rats treated with MCI-9042. No significant differences were observed in the production of circulating antibody and antibody deposition in rat glomeruli among the study groups. These results indicate that pathologic changes and urinary protein excretion are closely related to the presence of serotonin in nephrotoxic serum nephritis of WKY rats. Thus serotonin may play a key role in the glomerular injury in this model. Studies on the mode of action of MCI-9042 on platelet aggregation in vivo indicate that the antiplatelet effect of this drug did not contribute to the inhibition of renal injury in this experimental model. This study suggests that serotonin participates in macrophage-mediated immune injury in nephrotoxic serum nephritis of WKY rats.

Animals↗
PubMed1997

Trimethyltin syndrome as a hippocampal degeneration model: temporal changes and neurochemical features of seizure susceptibility and learning impairment.

The effects of trimethyltin on the hippocampus were investigated in terms of changes in histology, depth electroencephalography, learning acquisition and memory retention, choline acetyltransferase and neuropeptides, and seizure-induced c-fos messenger RNA expression. The results were as follows. (1) Morphologically, trimethyltin produced a progressive loss of hippocampal CA3 and CA4 pyramidal cells, starting from four days after peroral treatment with trimethyltin hydroxide (9 mg/kg), as described previously. (2) Neurophysiologically, the increased seizure susceptibility to pentylenetetrazol treatment reached a maximum at four days post-trimethyltin and then declined after five days post-trimethyltin. The maximal seizure susceptibility at four days post-trimethyltin was confirmed by the immediate and long-lasting appearance of spike discharge in the hippocampus. However, this was not verified by the expression of c-fos messenger RNA in the hippocampus, which was comparable between trimethyltin-treated and control rats. (3) Behaviorally, the time-courses of aggression and learning impairment were similar to that of the seizure susceptibility. (4) Neurochemically, trimethyltin treatment caused changes of neurochemical markers, which were manifested by the elevation of neuropeptide Y content in the entorhinal cortex, and of choline acetyltransferase in the hippocampal CA3 subfield. Trimethyltin may offer potential as a tool for investigations on the relationship between neuronal death in the hippocampus and the development of seizure susceptibility and learning impairment. Alterations in glucocorticoids, glutamate and neuropeptides may all contribute to the manifestation of the trimethyltin syndrome.

Animals↗
PubMed1997

Nucleolar organizing regions in primary intracranial malignant lymphomas.

Twenty-two non-immunocompromised patients with primary intracranial malignant lymphomas were examined on surgical material by using an argyrophilic method for the demonstration of nucleolar organizer regions as Ag-NORs. The histopathological classifications of 22 patients included 3 small lymphocytic, 7 small cleaved, 9 large cell. 1 mixed large and small, and 2 small non-cleaved type. The numbers of Ag-NOR of malignant lymphoma patients varied from 1.36 to 5.02 (mean 3.46 +/- 0.25). The mean Ag-NOR numbers in the histopathological subtypes were small lymphocytic 1.63, small cleaved 3.18, large 4.21, mixed large and small 3.47, and small non-cleaved 3.78. The number of Ag-NORs in small lymphocytic type was significantly less than small cleaved or large cell type (p < 0.05). The small cleaved type also had a smaller Ag-NOR number than the large cell type (p < 0.05). Except for two patients who had postoperative deterioration, 20 patients received postoperative irradiation ranging from 36 to 54 Gy (median, 46 Gy). Sixteen patients had complete response to radiotherapy, and 4 had good partial response. Ten patients had tumor recurrence within the remission period of 3 months to 7 years and 10 months (median 4.8 months). Three patients with intracranial relapse at a remote site had a significantly longer remission period (mean 57.3 months) than 7 with local relapse (mean 6.29 months), p < 0.05. The mean Ag-NOR number of the short and long remission period were 3.13 +/- 0.34 and 3.8 +/- 0.80, respectively. No significant difference was found between these two groups. The survival period was 3.2 months to 12 years (median 20 months). The Ag-NOR numbers of survival period less than or more than 20 months were 3.62 +/- 0.40 and 3.27 +/- 0.37, respectively. The Ag-NOR numbers did not correlate with either the remission or the survival period. These results indicate that Ag-NOR numbers may correlate with the histopathologic types, but not with the prognosis of primary intracranial malignant lymphomas.

Adult↗
PubMed1997

[A case of infant testicular tumor diagnosed ultrasonographically in the prenatal period].

We report a case of testicular tumor detected by ultrasonography during the prenatal period. Ultrasonography performed at 32 weeks of gestation showed that one testis was larger than the other. The right testis was markedly enlarged at 38 weeks of gestation. The heterogeneous echo pattern of the right testis suggested a testicular tumor. Right high orchiectomy was performed 3 months after birth. Pathological findings of the tumor were teratoma with mature and immature components according to the histological classification of testicular tumor. In Japan, this is the second case diagnosed in the prenatal period using ultrasonography.

Female↗
PubMed1996

Nitric oxide synthase-containing neurons in the hippocampus are preserved in trimethyltin intoxication.

We studied the effects of trimethyltin (TMT) (9 mg/kg, p.o.) on the nitric oxide synthase (NOS)-containing neurons in the rat hippocampus by NADPH-diaphorase histochemistry and a biochemical assay of NOS activity. TMT exposure caused the typical behavioral changes and a loss of the CA3/4 pyramidal cells, which were NADPH diaphorase-negative. The scattered interneurons and the CA1 pyramidal cells, which were NADPH diaphorase-positive, were spared. Hippocampal NOS activity showed no reduction in the TMT-treated rats compared with the controls. These results provide evidence of the preservation of the NOS-containing neurons in TMT intoxication.

Animals↗
PubMed1996

Potent and long-lasting anticonvulsant effects of 1-naphthylacetyl spermine, an analogue of Joro spider toxin, against amygdaloid kindled seizures in rats.

The anticonvulsant effect of 1-naphthylacetyl spermine (1-NA-Spm), an analogue of Joro spider toxin, against amygdaloid kindled seizures was studied in rats. 1-NA-Spm (10, 20 and 40 micrograms/rat) dose-dependently improved kindled seizures and shortened the afterdischarge duration 30 min after the administration. The anticonvulsant effect was observed even one day after the drug, and then gradually disappeared within 4 days. The present findings demonstrate that 1-NA-Spm acts as a potent and long-acting anticonvulsant against amygdaloid kindled seizures, and also suggest, together with the previous findings, that the calcium-permeable AMPA receptors, which are selectively antagonized by 1-NA-Spm, play a critical role in the seizure generation mechanism of amygdaloid kindling.

Amygdala↗
PubMed1996

Expression of c-fos mRNA after audiogenic seizure in adult rats with neonatal hypothyroidism.

In situ hybridization histochemistry was used to evaluate the expression of the immediate-early gene c-fos following the induction of audiogenic seizures in adult rats with transient neonatal hypothyroidism. The rats treated with 0.02% propylthiouracil (PTU) through mother's milk during days 0-19 after delivery showed a high incidence of seizures to auditory stimulation at the age of 4 months. The significant induction of c-fos mRNA by audiogenic seizures is prominent in several brain areas including central gray, peripeduncular nucleus, inferior colliculus, septal nucleus, bed nucleus of stria terminalis, and dorsomedial hypothalamus. However, the expression of c-fos mRNA was comparable in neocortex, dorsal hippocampus and medial geniculate body between control rats and PTU-treated, seizure-induced rats. These results confirm the previous report on the c-fos expression following audiogenic seizure sensitized during development by a loud noise [20]. The present results indicate that the neonatal PTU treatment may provide a useful tool for studying the mechanism underlying the seizure susceptibility and development after maturation.

Acoustic Stimulation↗
PubMed1996

Evaluation of blood coagulation-fibrinolysis system in patients receiving chronic hemodialysis.

We determined plasma levels of thrombomodulin, thrombin-antithrombin III complex (TAT), protein C, protein S, and plasmin-alpha 2 plasmin inhibitor complex (PIC) before and after hemodialysis in 54 patients receiving chronic hemodialysis, to evaluate the blood-coagulation system and to evaluate the antithrombogenicity of various dialyzer membranes. Predialysis levels of thrombomodulin and TAT were both significantly increased compared with normal control values, but levels of protein C, protein S, and PIC were not changed. In patients dialyzed with ethylene vinyl alcohol (EVAL) and polysulfone membranes, postdialysis levels of thrombomodulin, TAT, protein C, protein S, and PIC were not significantly different from the predialysis levels. However, in patients dialyzed with regenerated cellulose and polymethyl-methacrylate (PMMA) membranes, postdialysis levels of thrombomodulin, TAT, and PIC were significantly higher than predialysis levels. We conclude that patients on maintenance hemodialysis were considered to be in a state of hypercoagulability before hemodialysis, and a single hemodialysis session using regenerated cellulose and PMMA membrane may have caused injury to vascular endothelial cells, hypercoagulability, and enhancement of fibrinolytic activity.

Adult↗
PubMed1996

Decrease in intra-abdominal visceral fat may reduce blood pressure in obese hypertensive women.

We investigated the relationship between changes in blood pressure and fat distribution after a 12-week low-calorie diet in 26 obese hypertensive women whose average age was 50 +/- 13 years, mean body mass index was 33.7 +/- 3.1 kg/m2, and mean blood pressure was 112 +/- 9 mm Hg. As an index of intra-abdominal fat accumulation, we used the ratio of the intra-abdominal visceral fat area to subcutaneous fat area, determined by a computed tomographic section at the level of the umbilicus. Subjects lost a mean of 9.4 +/- 4.1 kg on a 1200-kcal (5040-kJ) diet for 12 weeks. Their mean blood pressure fell from 112 +/- 9 to 101 +/- 12 mm Hg (P < .001). The ratio of the visceral to subcutaneous fat area was significantly reduced after weight reduction from 0.56 +/- 0.33 to 0.45 +/- 0.27 (P < .02). Fasting plasma glucose and plasma glucose area after a 75-g oral glucose tolerance test also were significantly reduced by weight reduction. The change in mean blood pressure after weight reduction was not correlated with the change in body weight or body mass index but was correlated with the reduction in visceral fat area or ratio of visceral fat to subcutaneous fat area. Changes in mean blood pressure also were correlated with changes in fasting plasma glucose levels and the plasma glucose area determined by 75-g oral glucose tolerance test. Results indicate that a decrease in intra-abdominal visceral fat, rather than simply of body weight, may reduce blood pressure in obese hypertensive subjects. The mechanism may involve an improvement in glucose tolerance caused by weight reduction.

Abdomen↗
PubMed1996

Effect of rapeseed and dietary oils on the mean survival time of stroke-prone spontaneously hypertensive rats.

Low-fat conventional diets supplemented with 5 or 10% vegetable oils were fed to stroke-prone spontaneously hypertensive rats (SHR-SP) from weaning and the mean survival times were determined. A 1% aqueous sodium chloride solution was used as drinking water throughout the experiments. In four separate experiments, the rapeseed oil group showed a significantly shorter mean survival time. The relative mean survival times were 50-59% (rapeseed oil group), 78-100% (soybean oil group) and 86% (microbial oil group) as compared with the group fed perilla oil (100%). The group which received 4-fold diluted rapeseed oil exhibited a significantly shorter survival time as compared with the group receiving soybean oil. Although the feeding experiments were performed under very simple and restricted conditions, these results suggest that the rapeseed oil prepared for human use contains a factor (s) which is toxic to SHR-SP rats.

Animals↗
PubMed1996

Serotonin metabolism in patients undergoing hemodialysis.

To determine the pathogenic role of serotonin (5-HT), we investigated 5-HT metabolism in undergoing hemodialysis (HD). Mean value of platelet 5-HT in patients undergoing HD was significantly lower than that of normal controls (0.22 + or - 0.16 pmol/10(5) platelets versus 0.35 + or - 0.13 pmol/10(5) platelets, p <0.02). While platelet uptake of 5-HT in normal controls reached a plateau in each experiment after incubation with authentic 5-HT for 60 min, platelet uptake of 5-HT in patients undergoing HD reached various levels. We found significantly lower platelet 5-HT levels in patients with diabetes mellitus (DM) after HD compared with those in patients with chronic glomerulonephritis (p <0.05). The pathogenic role of serotonergic amplifying mechanism especially in patients with DM should be investigated. Second, we investigated plasma 11-dehydro-thromboxane B2 (11-DTXB2) levels in patients undergoing HD. Mean level of plasma 11-DTXB2 concentration in patients after HD was significantly higher than in patients before HD (32.8 + or - 17.0 pg/ml versus 23.7 + or - 7.2 pg/ml, p <0.02). Increased plasma levels of 11-DTXB2 after HD were regarded as an indication of hypercoagulation. Our results provide evidence that several factors such as hypercoagulation, heparin, 5-HT uptake of platelet, or causal diseases of renal failure could be responsible for the lower platelet 5-HT levels in patients undergoing HD.

Adult↗