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Biomedical subjects

H Oka

Publications and source records attributed to H Oka.

At least 145 records · Page 8Linked to original sources
PubMed1997

Prolongation of QTc interval in patients with Parkinson's disease.

QTc intervals were measured in 30 patients with Parkinson's disease and 30 healthy control subjects. The mean value of QTc intervals in patients with Parkinson's disease significantly exceeded that of healthy controls (418 +/- 14 ms vs. 403 +/- 18 ms). Prolongation of the QTc interval was unrelated to the administration of levodopa. The mean QTc interval in patients whose Hoehn and Yahr score was III or more was significantly greater than that of patients whose score was II or less (424 +/- 12 ms vs. 410 +/- 12 ms). A significant correlation between the QTc interval and the Valsalva ratio, as well as the overshoot, was identified. The QTc interval is closely related to autonomic nervous system dysfunction, including abnormal baroreceptor reflex function, in patients with Parkinson's disease.

Antiparkinson Agents↗
PubMed1997

Timing of surgical treatment for active native value endocarditis.

The aim of the study was to assess the optimum timing of surgical treatment for the active phase of native valve endocarditis. A retrospective study was conducted of the records of patients who had undergone aortic and/or mitral valve replacement for active native valve endocarditis during 1979-94 at Kinki University Hospital. Thirty-three patients with active infective endocarditis of the native valves were treated surgically. Their mean age was 45.4 years (range 11-71). The infective organism was streptococcus in 9 cases, Staphylococcus aureus in 8, and enterococcus in 4 cases. Blood cultures were negative in 9 cases. Of the patients infected with Staphylococcus aureus, 3 died soon after the operation and 1 died later during hospitalization. These 4 patients had been treated medically more than 2 weeks before operation. Another patient who was also treated medically more than 2 weeks before surgery survived. In contrast, all 3 patients infected with Staphylococcus aureus who were operated on within 2 weeks after the onset survived. No early or in-hospital deaths were documented among patients infected with organisms other than Staphylococcus aureus. Among patients who had suffered preoperative embolic episodes, the time from the initial pyrexia to the embolic event was clearly shorter in those infected with Staphylococcus aureus than in those infected with other organisms. Among the former group, 5 out of 6 patients suffered an embolism within 2 weeks of the onset of pyrexia and the remaining 1 within 3 weeks. Thus, in patients presenting with active native valve endocarditis caused by Staphylococcus aureus, surgical treatment should be performed as soon as possible after the onset of pyrexia, preferably within 2 weeks or as soon as the infective organism is identified as Staphylococcus aureus.

Adolescent↗
PubMed1997

Diagnostic Brachial Coronary Arteriography Using a Power-Assisted Injector and 4 French Catheters with New Shapes.

BACKGROUND: Right brachial access in diagnostic coronary arteriography (CAG) has demonstrated advantages over femoral approaches, including earlier ambulation and more predictable hemostasis, particularly when small diameter catheters were used. Poor results from some earlier reports of brachial CAG have been due partially to the need to use large diameter catheters for positional control. Technical advances in catheters and contrast injection may increase the utility of brachial access CAG. PURPOSE AND STUDY DESIGN: We evaluated three 4 French (Fr) catheters with new shapes and with a large internal to external diameter ratio that were designed to overcome previous limitations to brachial CAG. Contrast agent was delivered with a novel power injector (CAG-20) intended for arteriography using small catheters. Routine right brachial access CAG and left ventriculography (LVG) were evaluated in 2663 (69%) of 3880 consecutive patients admitted for examination from 1991 to 1995. The study population included 128 patients (5%) with left main trunk disease, 819 (21%) with old myocardial infarctions and 1747 (66%) with more than one vessel disease. For this trial, 1217 patients with valvular disease, ischemia associated with aortic or peripheral vascular disease, congenital cardiac disease and post-surgical and emergency catheterization were excluded because femoral access or a larger catheter (> 4 Fr) were required in those cases. RESULTS: A total of 2573 (97%) diagnostic quality CAG (> grade 3/5) were obtained solely with 4 Fr catheters placed via the right brachial artery. Of the other 66 examinations, 50 were completed through the brachial route but with alternate size or shape catheters and 16 cases required the femoral JudkinÕs technique. Useful LVG (> grade 2/4) were obtained from 2604 patients (98%). Overall, 2536 (95%) of cases provided clinically valuable images for both CAG and LVG from brachial access. We experienced one semi-emergency bypass operation and one emergency stent implantation caused by coronary dissection. There were no deaths, acute myocardial infarctions, loss of pulse or nerve injuries. CONCLUSION: Power-injector assisted, brachial 4 Fr CAG and LVG proved to be safe and cost-effective. Brachial access has the potential to become a routine method for out-patient cardiac opacification.

Journal Article↗
PubMed1997

[Clinicophysiological study of tremor in Parkinson's disease: quantitative tremor-based assessment of motor count using actigraphy].

In Parkinson's disease, resting tremor is often the initial symptom. This report focuses on the mechanism underlying tremor in Parkinson's disease and quantitative assessment of tremor. Central factors including Vim (nucleus ventralis intermedius) in the thalamus, and peripheral factors, such as acceleration of input pathways from muscle spindles via muscle tonus, are important aspects of the tremor mechanism in Parkinson's disease. It has also been suggested that tremor in Parkinson's disease is associated with parasympathetic and sympathetic dysfunctions. Objective assessments of tremor, such as the application of surface electromyography, are useful in the diagnosis and treatment of Parkinson's disease. Actigraph, as introduced herein, is a three dimensional motor sensing apparatus. Therefore, motor counts over 0.01 G can be detected by actigraphy. To date, this device has been used for evaluating akinesia in Parkinson's disease and insomnia. In this study, actigraphy was used in Parkinson patients with tremor, and it reflected motor activity in the wrist and was associated with the severity of hand tremor. Activities of daily living (ADL) are disturbed by hyperkinesia of the hand for Parkinson patients with hand tremor. We demonstrated that actigraphy is a simple and quantitative method of assessing motor activity in Parkinson patients with tremor.

Aged↗
PubMed1997

[Central motor conduction time using magnetic and vibratory stimulation in Parkinson's disease, especially in patients with rigidity].

Rigidity, tremor, akinesia and disorder of postural reflex are the main clinical features of Parkinson's disease. We presented the mechanism underlying rigidity and assessed central motor conduction time (CMCT) using magnetic, with or without vibratory, stimulations. Basal ganglia, especially, the internal pallidum, and the thalamus play major roles in the mechanism of rigidity in Parkinson's disease. Hyperexcitability of the spinal motor nucleus due to low threshold has been recognized. Magnetic stimulation is painless and is simpler than electric stimulation. Therefore, this method is used clinically for evaluating conduction disturbance of the upper motor neurons in multiple sclerosis, cerebrovascular disease and so on. CMCT measured by magnetic and/or electric stimulation may be abbreviated or normal in Parkinson's disease, according to the literature, though controversy persists in this regard. In our study, CMCT was normal in Parkinson patients. However, CMCT was reduced in patients with rigidity and tremor. Furthermore, in a portion of the patients, CMCT was further abbreviated by also applying vibratory stimulation. These observations support the hypothesis that cells in the thalamus, cortex and spinal cord and/or pathways in these portions of the central nervous system are excitable or activated in Parkinson patients with rigidity and tremor. However, elucidation of the mechanisms underlying rigidity and tremor awaits further investigation.

Humans↗
PubMed1997

[Total intravenous anesthesia with propofol and fentanyl for laparoscopic cholecystectomy].

The postoperative antiemetic effect of total intravenous anesthesia with propofol and fentanyl was evaluated in 40 patients for laparoscopic cholecystectomy. Patients were divided into 2 groups. In group P, anesthesia was induced with intravenous fentanyl 0.1 mg and propofol 2 mg.kg-1 and maintained with continuous infusion of propofol. In group I, anesthesia was induced with intravenous thiopental 5 mg.kg-1 and maintained with nitrous oxide 60% in oxygen and isoflurane. Post-operative nausea and vomiting were recorded for 8 h after surgery. Nausea scores (range 1-4) were significantly lower in group P as compared with group I at 0 h after surgery, but no difference between the groups at 2 h, 4 h, 8 h after surgery. No significant differences were found in the incidence of vomiting between the groups. These results suggest that total intravenous anesthesia with propofol and fentanyl is superior to inhalational anesthesia with nitrous oxide and isoflurane in postoperative nausea. This antiemetic effect is, however, limited in the early period after anesthesia.

Aged↗
PubMed1997

Mechanical impedance of layered tissue.

The human body is a medium which consists of various tissues such as skin, fat, muscle and bone. Each of the tissues has their own biomechanical properties. We have measured biomechanical impedances by applying a random vibration (30-1000 Hz) to the layered model of human tissues to study the occurring mechanism of impedances measured at the skin surface. The data showed that the top tissue layer and the underlying layer both contribute to the impedance depending on the thickness of the top layer. The contribution of the underlying layer was clearer over the frequency range from 30 to 400 Hz. Quantitatively we found the following: The impedance measured at the surface was roughly expressed as the model which is connected in series by the impedances of the top and underlying tissues. The contribution of the underlying tissue decreased according to the increase of the thickness of the top tissue, and disappeared over a certain thickness (18 mm in this paper).

Adipose Tissue↗
PubMed1996

Detection of a new interstellar molecular ion, H2COH+ (protonated formaldehyde).

A new interstellar molecular ion, H2COH+ (protonated formaldehyde), has been detected toward Sgr B2, Orion KL, W51, and possibly in NGC 7538 and DR21(OH). Six transitions were detected in Sgr B2(M). The 1(1,0)-1(0,1) transition was detected in all sources listed above. Searches were also made toward the cold, dark clouds TMC-1 and L134N, Orion (3N, 1E), and a red giant, IRC + 10216, without success. The excitation temperatures of H2COH+ are calculated to be 60-110 K, and the column densities are on the order of 10(12)-10(14) cm-2 in Sgr B2, Orion KL, and W51. The fractional abundance of H2COH+ is on the order of 10(-11) to 10-(9), and the ratio of H2COH+ to H2CO is in the range 0.001-0.5 in these objects. The values in Orion KL seem to be consistent with the "early time" values of recent model calculations by Lee, Bettens, & Herbst, but they appear to be higher than the model values in Sgr B2 and W51 even if we take the large uncertainties of column densities of H2CO into account. We suggest production routes starting from CH3OH may play an important role in the formation of H2COH+.

Astronomical Phenomena↗
PubMed1996

E-cadherin mediated adhesion system in cancer cells.

BACKGROUND: Cadherins are the family of functionally related transmembrane glycoproteins responsible for the Ca(2+)-dependent cell-cell adhesion mechanism that is crucial for the mutual association of vertebrate cells. Because cell dissociation and acquisition of cell motility occur in cancer invasion and metastasis, it is important to study the possible involvement of mutual cell adhesion of cancer cells. METHODS: The results and observations reported in the literature on the involvement of cadherin-mediated adhesion in the behavior of cancer cells are reviewed and compared with the authors' experimental and clinical studies. RESULTS: In the initial studies, E-cadherin and alpha-catenin or beta-catenin expression have been investigated immunohistochemically. Although these molecules showed strong expression in noncancerous epithelial tissues without exception, the reduction of the immunoreactivities of cancer cells has been observed. These observations suggest that the impaired E-cadherin mediated adhesion system is a characteristic of cells with malignant transformation. The impaired expression of E-cadherin is frequently observed in tumors with aggressive histopathologic characteristics that are defined by morphologic degree of invasiveness and metastasis. Three mechanisms of the inactivation of cadherin action could be proposed in human cancers by in vivo and in vitro studies. The first is downregulation of E-cadherin expression and its gene mutation. The second is abnormality of deletion of catenins, including the absence of alpha-catenin. The third abnormality of this adhesion system is biochemical modification of catenins such as the phosphorylation of beta-catenin. CONCLUSIONS: Numerous studies have suggested that the E-cadherin adhesion system is disturbed in cancer cells through various mechanisms and these impaired functions of E-cadherin contribute to the release of cancer cells from the primary lesion and to cell dedifferentiation.

Animals↗
PubMed1996

Pituitary choristoma composed of corticotrophs and adrenocortical cells in the sella turcica.

A pituitary tumour composed of well-differentiated corticotrophs and adrenocortical cells is reported. Sections of the tumour revealed a mixture of small round cells with amphophilic or basophilic periodic acid-Schiff (PAS)-positive cytoplasm and large spherical and oval cells with abundant, granular, partly vacuolated PAS-negative cytoplasm. The small cells contained type 1 cytokeratin-positive microfilaments, numerous 250-500 nm endocrine-type secretory granules immunoreactive for adenocorticotropic hormone (ACTH) and beta-lipotropin. The large cells possessed ample cytoplasm filled with abundant vesicular smooth endoplasmic reticulum, numerous mitochondria possessing tubulovesicular cristae and frequent dense bodies. They lacked the features of pituitary endocrine cells or folliculostellate cells and were found to contain a panel of steroidogenic dehydrogenases and hydroxylases. The tumour was classified as a choristoma, in which two distinct cells types, corticotrophs and adrenocortical cells, were mixed. We suggest that, under continued ACTH stimulation, umcommitted stem cells may differentiate into adrenocortical cells. Alternatively, the presence of adrenocortical cells may be the result of heterotopia.

Adolescent↗
PubMed1996

Measurement of 5-fluorouracil in scalp hair: a possible index of patient compliance with oral adjuvant chemotherapy.

OBJECTIVE: Little is known about patient compliance with oral adjuvant chemotherapy. It is estimated to be poor especially in Japan, where it is still unusual for patients to be directly informed of their diagnosis of malignancy. 5-Fluorouracil (5-FU) was measured in hair samples to assess patient exposure to 5-FU, and its potential usefulness is discussed as an index of compliance with postoperative adjuvant chemotherapy. METHODS: Hair samples obtained from 55 patients, who had received oral 5-FU (total dose 27-41 g) as postoperative adjuvant chemotherapy over a 6-month period, were used for the analysis of 5-FU. The drug was extracted from the hair using ethyl acetate, and its fluorescence derivatization was employed for measurement with HPLC. The detection limit of 5-FU in hair was 0.01 ppm. RESULTS: In 22 out of 55 samples 5-FU content was under the detection limit, whereas in the remaining 33 samples the drug was detected in a range of 0.006-2.125 ng per hair strand; in addition, drug content showed a lognormal distribution. 5-FU was detected in the hair collected from those patients who were possibly compliant with the postoperative oral adjuvant chemotherapy. CONCLUSION: As many as 40% of the patients analysed were supposed to be much less compliant. Even in the possibly compliant patients, the degree of compliance with the therapy varied according to a log-normal distribution.

Animals↗
PubMed1996

Expression of BCL-2 gene product in embryonal tumors of the central nervous system.

BACKGROUND: The expression of bcl-2 is associated with suppression of programmed cell death and prolonged cell survival. Recently, immunoreactivity to the bcl-2 gene product has been reported not only in a variety of embryonal and adult nonhematopoietic tissues, but also in neuroblastoma. However, the study of bcl-2 expression has not been performed in brain tumors. METHODS: In this study, we examined the incidence and significance of bcl-2 expression in 25 cases of embryonal tumors of the central nervous system, including medulloblastoma, neuroblastoma, ependymoblastoma, and PNET (primitive neuroectodermal tumor), which has the possibility of neuronal differentiation. RESULTS: The results demonstrated that 13 tumors (52%) positive for bcl-2 belonged to early differentiated and neuronal types, and 7 negative tumors (28.0%) mostly belonged to undifferentiated type. CONCLUSIONS: These results have led us to speculate on the possibility that tumor cells begin expressing bcl-2 along with their neuronal differentiation from primitive cells.

Adolescent↗
PubMed1996

Prolongation of QTc interval and autonomic nervous dysfunction in diabetic patients.

We have attempted to clarify the relationships of the QTc interval to alpha and beta sympathetic, as well as parasympathetic function tests including spectral analyses of the R-R interval and systolic blood pressure. The QTc intervals were estimated in 76 diabetic patients and 76 age-matched healthy controls whose R-R intervals were comparable to those of the diabetic patients. We also investigated the relationships of the QTc interval to various clinical features of diabetes mellitus and to autonomic function tests. The QTc interval in diabetic patients was significantly greater than that in healthy controls. The QTc intervals were unrelated to diabetic control, retinopathy and nephropathy, but were prolonged in patients with a long duration of diabetes as compared to those with a short disease duration. There were significant correlations between the QTc interval and orthostatic hypotension, R-R variation and the Valsalva maneuver. Significant correlations were observed between the QTc interval and both the low and the high frequency component of spectral analysis of the R-R interval, whereas no correlations were found with spectral analysis of systolic blood pressure. An abnormal QTc interval is an indicator of cardiac sympathetic and parasympathetic nervous dysfunction, but not vasomotor dysfunction.

Blood Glucose↗
PubMed1996

Equivalent parental distribution of frequently lost alleles and biallelic expression of the H19 gene in human testicular germ cell tumors.

Epigenetic alterations such as genomic imprinting might play an important role in human tumorigenesis, in addition to specific genetic alterations. To clarify the role of genetic and/or epigenetic alterations in the tumorigenesis of testicular germ cell tumors (GCTs), we analyzed 40 primary and 3 metastatic testicular GCTs with regard to specific chromosomal losses and their parental origin. A high incidence of loss of heterozygosity (LOH) was demonstrated on chromosomes 1p, 3p, 11p, and 17p: 9/19 (47%), 18/39 (46%), 13/40 (33%) and 20/36 (56%), respectively. However, there was no correlation between the frequency of LOH on any chromosome and clinicopathological features. Regarding the parental origin of the lost allele at these chromosomes, preferential loss was not demonstrated in this study. To clarify the imprinting status in GCTs, we analyzed the allele-specific expression of the H19 gene, which is paternally imprinted on chromosome 11p. All of 11 tumors without LOH at this locus showed biallelic expression of H19. Based on previous work demonstrating the biallelic expression of H19 in primordial germ cells and spermatogonia in the mouse germ line, these results suggest that the biallelic expression of H19 in testicular GCTs reflects the characteristics of the original germ cells in which the imprinting marking has been erased and not established, rather than loss of imprinting during tumorigenesis. It is also possible that a failure to re-establish the imprinting might be an initial event which leads to testicular GCTs.

Alleles↗
PubMed1996

Beta-catenin expression in human cancers.

Cell-cell adhesion in tissue is mainly regulated by homotypic interaction of cadherin molecules, which are anchored to the cytoskeleton via cytoplasmic proteins, including alpha- and beta-catenin. Although we previously demonstrated that alpha-catenin is crucial for cadherin function in vivo, little is known about the role of beta-catenin. We examined the expression of beta-catenin in human carcinoma samples along with normal tissue (esophagus, stomach, and colon) by immunostaining using our antibody for beta-catenin. Normal epithelium strongly expressed beta-catenin. However, beta-catenin expression was frequently reduced in primary tumors of the esophagus (10 of 15, 67%), stomach (9 of 19, 47%), and colon (11 of 22, 50%). From an immunoprecipitation study, we found that beta-catenin forms a complex with E-cadherin not only in the normal epithelium but also in cancerous tissues. In coexpression patterns of E-cadherin and beta-catenin, 43 (77%) of the 56 tumors showed a similar expression of both molecules, whereas the other 13 tumors (23%) showed positive staining for E-cadherin and reduced expression of beta-catenin. These findings suggest that beta-catenin forms a complex with E-cadherin in vivo and down-regulation of beta-catenin expression is associated with malignant transformation.

Adenocarcinoma↗