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H Oka

Publications and source records attributed to H Oka.

At least 217 records · Page 12Linked to original sources
PubMed1993

The mode of cerebellar activation of pyramidal neurons in the cat parietal cortex (areas 5 and 7): an intracellular HRP study.

Response properties of 180 pyramidal neurons (11 layer II, 66 layer III, 7 layer IV, 76 layer V and 20 layer VI neurons) in the cat parietal cortex (areas 5 and 7) were examined intracellularly with stimulations of the cerebellar nucleus (CN), the thalamic ventroanterior nucleus (VA) and the lateral posterior nucleus (LP) under pentobarbital anesthesia. Pyramidal neurons were identified morphologically or electrophysiologically with antidromic responses by pontine nuclei (PN) stimulation. CN and VA stimulations evoked EPSPs in layer II, III, V and VI pyramidal neurons, but scarcely induced EPSPs in layer IV pyramidal ones. The mean latencies of CN-EPSPs were nearly the same through layers II to V, giving values of around 4.5 ms, but that of layer VI pyramidal neurons was much longer (5.5 +/- 0.8 ms: mean +/- SD). Those of VA-EPSPs were also nearly the same through all layers (around 2.2-2.8 ms). In case of LP stimulation, EPSPs were scarcely recorded in layer II and IV pyramidal neurons. The mean latency of LP-EPSPs was much shorter in layer III (2.6 +/- 1.0 ms) than those in layers V and VI (3.8-3.9 ms). It was noted that pyramidal neurons in layers II and III responded more frequently to CN and VA stimulations than those in deeper layers, and that the amplitudes of CN- and VA-EPSPs were large and conspicuous in layer III. In layer V, a statistical difference in the latency distributions of CN-, VA-, and LP-EPSPs between fast- and slow-type pyramidal neurons was not detected. The present results suggest that there exist the different modes of thalamocortical (T-C) innervations in the cat parietal cortex; the superficial T-C innervation of CN-VA inputs and the deep T-C innervation of LP inputs.

Animals↗
PubMed1993

Enflurane increases the adrenaline threshold for the development of slow responses in isolated canine trabeculae.

To determine if enflurane has different effects on myocardial sensitivity to adrenaline than those previously reported for halothane, we have studied the enflurane-adrenaline interaction in isolated canine trabeculae using doses of adrenaline necessary to produce slow responses (adrenaline threshold for the development of slow responses, ATSR) as an indicator. The preparations were depolarized in Tyrode's solution containing potassium chloride 26 mmol litre-1, then adrenaline concentrations in the solution were increased stepwise. Enflurane 1% had no significant effect, but 2% and 4% significantly increased the ATSR two-fold and seven-fold, respectively. To investigate the influence of enflurane on the adrenaline-adrenoceptor interaction, we studied the effects on the ATSR of 2% enflurane alone or in combination with either prazosin 8 ng ml-1 or metoprolol 17 ng ml-1. Compared with the ATSR obtained with 2% enflurane alone, alpha 1-block with prazosin did not alter, but beta 1-block with metoprolol significantly increased the ATSR (three-fold). These effects on enflurane are qualitatively as well as quantitatively similar to those reported previously for halothane. Thus, assuming that the MAC value for enflurane is about 2-2.5 times greater than that for halothane, the effects of enflurane on slow channel conductance (antiarrhythmic effects of enflurane) might be about two to three times greater than those of halothane at equivalent depth of anaesthesia. Such differences may explain in part the clinical observation that ventricular arrhythmias are less likely with enflurane than with halothane.

Animals↗
PubMed1993

Hepatic arterial and portal venous oxygen content and extraction in liver cirrhosis.

We examined the oxygen content in the hepatic arterial, hepatic venous and portal venous blood to evaluate the oxygen supply to the liver and hepatic oxygen extraction in cirrhosis. The arterial-portal venous difference of the oxygen content was within the normal range in cirrhosis patients, although the oxygen content of the hepatic artery and portal vein was lower than in the control patients. The hepatic venous oxygen content was normal in the cirrhosis patients. The oxygen tension and saturation were always higher in the splenic vein than in the other branches of the portal system. Oxygen was supplied chiefly by the hepatic artery, and arterial oxygen extraction was normal in cirrhosis. In addition, there was no change in arterial extraction during oxygen inhalation by cirrhosis patients. Portal venous oxygen extraction was decreased in cirrhosis and was increased by oxygen inhalation. These findings indicate the autoregulation of hepatic oxygen through a mutual relationship between the hepatic arterial and the portovenous oxygen supply.

Female↗
PubMed1993

Usefulness of thallium-201 re-injection method for the evaluation of myocardial viability.

Areas of the heart which are supposedly absent of myocardial viability due to persistent thallium defect in exercise thallium myocardial scintigraphy sometimes recover ventricular wall motion through coronary revascularization. To avoid such underestimation of myocardial viability, a "re-injection method" was developed. At the peak of supine ergometer exercise in 51 patients with coronary artery disease, 111 MBq thallium was injected. Conventional exercise and 3 h-delay images were then obtained using single photon emission computed tomography. Subsequently, 55 MBq thallium was injected and a re-injection image was obtained 1 h later. Each image was divided into 12 segments and compared by left ventriculography and coronary angiography. Redistribution was found in 36 patients (71%) on the delayed images and in 44 patients (86%) on either the delayed or the re-injection images (p < 0.05). There were 127 redistribution segments (38%) on the delayed images and 163 (49%) on the re-injection images out of 336 defects on the exercise images (p < 0.001). In normokinetic segments with significant coronary stenosis and in hypokinetic segments, redistribution was found in 42% and 45% of the defects, respectively, on the delayed images, and in 65% and 62% of the defects, respectively, on the re-injection images (p < 0.01). However, no significant differences were observed between the delayed and either the delayed or re-injection images in the akinetic segments. These results suggest that the re-injection method is useful for avoiding underestimation of myocardial viability.

Aged↗
PubMed1993

Invasive meningiomas in relation to high proliferating potential.

We conducted a study to investigate whether an association exists among histologic findings, labeling index determined by the labeling index (LI) of proliferating cell nuclear antigen (PCNA) and recurrence in a population of 30 meningioma patients. All of 6 patients (invasive meningioma) with brain invasion had a PCNA LI in excess of 5%. Recurrence was found in 4 of these patients. In 24 patients who did not have brain invasion, PCNA LI was 4% or less and only 1 case had recurrence. Recurrence occurred in 3 of 25 patients who underwent macroscopic total resection and all of these 3 cases had brain invasion and a PCNA LI in excess of 5%. The findings of this study indicated the existence of a close correlation between peripheral invasiveness of meningioma and its biological behavior.

Adolescent↗
PubMed1993

[E-cadherin expression and cancer invasion and metastasis].

E-cadherin (ECD) is a transmembrane glycoprotein that mediates the calcium dependent adhesion of cells and plays a major role in cell-cell adhesion of normal epithelium. In present study, we have established the positive ECD expressed clone (ECD(+)) and the negative ECD expressed clone (ECD(-)). Anti human ECD monoclonal antibody (HECD-1) disturbed the mutual adhesion of ECD(+) effectively but didn't disturb that of ECD(-). ECD(+) did not invade the collagen/fibroblast gel, but ECD(-) did. Furthermore, ECD(+) acquired invasiveness in the collagen gel when HECD-1 was used. Clinicopathologically, we have investigated the correlation between expression of ECD and metastasis in human esophageal and gastric cancers by immunohistochemical staining using HECD-1. ECD expression of these lymph node metastatic tumor in the primary sites was more reduced than that of non metastatic tumor significantly. These results indicated that reduction or dysfunction of ECD diminishes intercellular adhesion and acquires invasive and metastatic capacity in human cancer cells.

Cadherins↗
PubMed1993

Origin of craniopharyngioma: an electron microscopic study.

To investigate the possibility that the two subtypes of craniopharyngioma, adamantinous type and squamous papillary type, are tumors arising from different origins, the authors conducted an electron microscopic study in 10 cases of craniopharyngioma. Light microscopic study revealed distinct differences between the two subtypes, but their ultrastructure was fundamentally similar. In this report, the authors propose an explanation of the origin of these subtypes to account for the findings.

Adolescent↗
PubMed1993

[The effects of nicotine on a patient with spinocerebellar degeneration whose symptoms temporarily exacerbated by cigarette smoking].

The purpose of the present study was to elucidate the influences of nicotine on a patient with spinocerebellar degeneration whose symptoms temporarily exacerbated by cigarette smoking. We have examined the influences of nicotine gum on cerebellar ataxia. Limb ataxia, dysarthria and truncal titubation were maximally aggravated 15 min after nicotine gum chewing, which paralleled blood nicotine level. Specific increased accumulation of 123I-IMP was observed in the cerebellum 15 min after nicotine gum load by 123I-IMP-SPECT. On the other hand, in a control with spinocerebellar degeneration whose symptoms not changed by nicotine gum load, the specific finding on 123I-IMP-SPECT was not detected. These findings suggested a direct effect of nicotine on the cerebellum.

Amphetamines↗
PubMed1993

[A study of epidemiology and fetal effects of human parvovirus B19 infection].

The risk of human parvovirus B19(B19) infection in pregnant women, the relationship between B19 and early spontaneous abortion, and the pathogenesis of non-immune hydrops fetalis (NIHF) due to B19 infection were studied. 1) After the period of prevalence of erythema infectiosum(EI) between 1986 and 1987, the positive rate of anti B19 IgG antibody by sandwich ELISA in the sera from subjects aged 15-34 years old was 17-26%. This indicates that about 80% of pregnant women could be at the risk of B19 infection in future EI prevalence within ten years. 2) IgM antibody assayed by capture ELISA was positive in 1.4% of the sera from pregnant women during the period of EI prevalence. 3) B19 DNA could not be detected by in situ hybridization (ISH) in any chorionic tissues from 105 early spontaneous abortuses during the period. B19 infection could not be proven as one of the causes of early spontaneous abortion. 4) B19 DNA was localized by ISH in erythroblasts but not in myocardial cells of two fetuses out of 11 NIHF. Therefore, NIHF following B19 infection could take place due to anemia following B19 infection of erythroblasts and their destruction.

Abortion, Spontaneous↗
PubMed1993

[Acute aneurysm surgery and the Glasgow Coma Scale: relationship with 6-month outcome].

A series of 610 patients who had aneurysm surgery within 7 days of the hemorrhage were analyzed as to the relationship between the preoperative Glasgow Coma Scale (GCS) score and the outcome assessed by using the Glasgow Outcome Scale (GOS) at 6 months after surgery. The patient distribution in accordance with the GCS scores in descending order from 15 to 3 was as follows: 265, 109, 44, 24, 17, 20, 25, 15, 18, 12, 16, 23, and 22 cases, respectively. In general, the larger the GCS score, the better the outcome. Thus, the overall results proved to be significantly correlated with the GCS score prior to surgery (r = 0.608, P < 0.01). As for demarcation levels along the GCS axis in terms of the GOS, a significant difference in the outcome was observed at the level of GCS scores between 15 and 14 (P < 0.0001, Wilcoxon test). However, no borderlines were evident at any GCS levels other than 15/14. The problems of applying the GCS to the grading system of aneurysmal subarachnoid hemorrhage are discussed.

Adult↗
PubMed1993

[Vasospasm and its outcome after early surgery for ruptured cerebral aneurysms: changing pattern of its incidence and outcome during this 9-year period].

The occurrence and outcome of vasospasm (VS) were analyzed in 240 patients who had aneurysm surgery within 7 days of a hemorrhage during 9-year period (1981-89). Occurrence of VS was evaluated by the appearance of ischemic symptoms, (A) with or (B) without CT evidence of infarcts. The surgical outcome was assessed by the Glasgow Outcome Scale 6 months postoperatively. The results in the first and the latter halves of the period were compared. The overall incidence of VS (A+B) was 34.8% (A: 23.5%, B: 11.3%) and 33.6% (A: 15.2%, B: 18.4%) in the first and the latter halves, respectively. Thus, VS leading to infarction showed a tendency to decrease in the latter half of the period, though the overall incidence of VS itself was almost identical in both the first and second halves of the period. The results were also analyzed according to preoperative grading based on the Glasgow Coma Scale (GCS). The tendency toward decreased severity of VS in the latter term was most remarkable in patients with GCS total scores between 14 and 13. The decreased incidence of severe VS proved to be reflected in decreased mortality and in increased rate of good outcome in the latter half of the period. In order to confirm whether the results obtained in our clinic are universal, we applied the same analysis for control groups in four cooperative double-blind clinical trials performed during this period in Japan. The study again showed that the rate of infarction has decreased significantly over the decade, resulting in the improved surgical outcome.(ABSTRACT TRUNCATED AT 250 WORDS)

Cerebral Infarction↗
PubMed1992

The medial dorsal nucleus is one of the thalamic relays of the cerebellocerebral responses to the frontal association cortex in the monkey: horseradish peroxidase and fluorescent dye double staining study.

To reveal the thalamic relay nucleus of the cerebellocerebral responses in the frontal association cortex, simultaneous labeling of the cerebellothalamic (C-T) terminals and the thalamocortical (T-Cx) neurons was performed in three monkeys. Horseradish peroxidase (HRP) was injected into the deep cerebellar nuclei and small doses of HRP or fluorescent dye were injected into the prefrontal cortex. The distribution of anterogradely labeled C-T terminals and retrogradely labeled T-Cx neurons was examined in the same sections. In addition to being distributed in the ventral thalamic nuclei and nucleus X, as previously reported, anterogradely labeled terminals were distributed in the ventrolateral part of the medial dorsal (MD) nucleus where retrogradely labeled thalamo-frontal projection neurons were localized. This study revealed that the ventrolateral parts of the MD together (MDmf, MDpc and MDdc) form one of the thalamic relays of the cerebelloprefrontal responses.

Animals↗
PubMed1992

Serial assessment of denervated but viable myocardium following acute myocardial infarction in dogs using iodine-123 metaiodobenzylguanidine and thallium-201 chloride myocardial single photon emission tomography.

Iodine-123 metaiodobenzylguanidine (mIBG) is taken up by sympathetic nerve endings, allowing scintigraphic imaging of myocardial sympathetic innervation. We investigated the denervated but viable canine myocardium after acute myocardial infarction by serial mIBG and thallium-201 chloride (201TlCl) single photon emission tomography (SPET). In 12 dogs, acute myocardial infarction was produced by ligation of the left circumflex coronary artery. Images of mIBG and thallium SPET were obtained 6 h, 1, 4 and 6 weeks later. The defect size was calculated in percentage points from short axial views, and the 123I-mIBG/201TlCl ratio was determined. The uptake ratio was high at 1 week but gradually decreased. Three dogs were killed at each time point, and tissue samples were obtained from infarcted (both 201TlCl and 123I-mIBG defects), peri-infarcted (123I-mIBG defect and 201TlCl normal) and normal myocardium (both mIBG and 201TlCl normal). The changes in tissue content of noradrenaline in these lesions were measured. Noradrenaline tissue content gradually recovered in the peri-infarcted area. However, no recovery was noted in the infarcted area at 6 weeks. We conclude that sympathetic denervation and re-innervation occur following acute myocardial infarction, and the denervated but viable myocardium could be detected non-invasively by combined mIBG and thallium SPET.

3-Iodobenzylguanidine↗
PubMed1992

Effect of hepatic collateral hemodynamics on gastric mucosal blood flow in patients with liver cirrhosis.

The dependence of the gastric mucosal change in liver cirrhosis on the extrahepatic collaterals is still unknown. Therefore we studied the influence of these collateral hemodynamics on gastric mucosal blood flow and gastric mucosal lesions. The subjects were 23 cirrhotic patients and were divided into two groups by the findings of percutaneous transhepatic portography. The first group consisted of 14 cases whose extrahepatic collaterals were via esophageal varices (group I). The second group included 9 cases having collaterals other than esophageal varices (group II). Multiple red spots were observed in 13 of 14 cases in group I, and two of nine cases in group II. Gastric mucosal blood flow was 2.0 +/- 0.9 volts (mean +/- SD) in group I, 4.0 +/- 1.2 in group II. A statistically significant difference was observed between groups I and II. Gastric mucosal blood flow was not significantly correlated with portal venous pressure in group I. It is concluded that, in liver cirrhosis, gastric mucosal blood flow is changeable according to the types of the extrahepatic collaterals.

Aged↗
PubMed1992

Immunohistochemical evaluation of E-cadherin adhesion molecule expression in human gastric cancer.

E-cadherin (ECD) is one of subclasses of the cadherin family which plays a major role in the maintenance of intercellular adhesion in epithelial tissues. An immunohistochemical study of ECD expression was performed on gastric adenocarcinoma from 103 patients using our monoclonal antibody for human ECD (HECD-1). ECD was strongly expressed in normal gastric epithelium without exception; however, various staining patterns were observed in cancer tissues. The frequency of tumours with preserved ECD expression (Pre-type) and reduced ECD expression (Rd-type) was 42% and 58% respectively. Tumours with a high frequency of Rd-type expression particularly included: undifferentiated tumours (85%, 46/54), Borrmann's type 4 (90%, 9/10), tumours larger than 2.6 cm in diameter (65%, 53/81), tumours invading beyond the subserosa layer (78%, 46/59), and tumours with infiltrative growth (87%, 41/47). Furthermore, the frequency of Rd-type expression in cases with peritoneal dissemination (82%, 9/11) or lymph node metastasis (73%, 43/59) was significantly higher than that in cases without dissemination or metastasis. These results suggest that ECD might play a key role in the genesis of histological differentiation, and that the reduction of ECD expression may affect the mode of invasion and metastasis of human gastric cancer cells.

Adenocarcinoma↗
PubMed1992

Randomized, controlled study on adjuvant immunochemotherapy with PSK in curatively resected colorectal cancer. The Cooperative Study Group of Surgical Adjuvant Immunochemotherapy for Cancer of Colon and Rectum (Kanagawa).

A randomized, controlled trial of adjuvant immunochemotherapy with PSK (Kureha Chemical Industry Co., Tokyo, Japan) in curatively resected colorectal cancer was studied in 35 institutions in the Kanagawa prefecture. From March 1985 to February 1987, 462 patients were registered. Four hundred forty-eight of those patients (97.0 percent) satisfied the eligibility criteria. The control group received mitomycin C intravenously on the day of and the day after surgery, followed by oral 5-fluorouracil (5-FU) administration for over six months. The PSK group received PSK orally for over three years, in addition to mitomycin C and 5-FU as in the control group. At the end of February 1990, the median follow-up time for this study was four years (range, three to five years). The disease-free survival curve and the survival curve of the PSK group were better than those of the control group, and differences between the two groups were statistically significant (disease-free survival, P = 0.013; survival, P = 0.013). These results indicate that adjuvant immunochemotherapy with PSK was beneficial for curatively resected colorectal cancer.

Adjuvants, Immunologic↗
PubMed1992

Effects of interferon-alpha on human B cell responsiveness: biphasic effects in cultures stimulated with Staphylococcus aureus.

Although interferon-alpha (IFN-alpha) has been found to be involved in the immune regulation in vivo, the effects of IFN-alpha on human B cells have not yet been clarified because of conflicting results in the literature. The present study therefore examined the effects of several subtypes of IFN-alpha (natural, alpha 1, alpha 2a, alpha 2b) on B cell responsiveness in detail by comparing different experimental conditions. Highly purified B cells from normal human individuals were cultured with Staphylococcus aureus (SA) + IL-2 or with immobilized anti-CD3-activated T4 cells in the presence or absence of IFN-alpha. IFN-alpha enhanced the immunoglobulin (Ig) production induced by immobilized anti-CD3-activated T4 cells. By contrast, IFN-alpha (5-50,000 IU/ml) suppressed the Ig production induced by SA + IL-2. The suppression by IFN-alpha was dependent on the concentration of SA. The inhibitory effects of IFN-alpha in SA-stimulated cultures were exerted in the first 72 hr of cultures and required the presence of IL-2, whereas IFN-alpha enhanced the maturation of B cells when it was added after 72 hr of cultures. The suppressive effects of IFN-alpha were overcome by addition of immobilized anti-CD3-preactivated T cells that had been treated with mitomycin C, but not by the addition of fresh T cells or soluble factors produced by activated T cells. Of interest, IFN-alpha did not inhibit the expression of IL-2R, but inhibited that of intercellular adhesion molecule-1 (ICAM-1) on B cells after stimulation with SA + IL-2, suggesting that the suppressive effects of IFN-alpha might be related to the regulation of B cell-B cell contacts through ICAM-1. There was no significant difference in effects on B cells among various subtypes of IFN-alpha. These results suggest that the effects of IFN-alpha on human B cell responsiveness may be different depending on the nature of stimulation. Moreover, the data indicate that IFN-alpha enhances the differentiation of activated B cells irrespective of the activation signals.

Antibodies, Monoclonal↗