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Biomedical subjects

T Nakazato

Publications and source records attributed to T Nakazato.

At least 37 records · Page 2Linked to original sources
PubMed1995

[Clinical evaluation of endoscopic ultrasonography (EUS) in the diagnosis of superficial esophageal carcinoma].

Pre-operative diagnosis of the depth of invasion is important to decide the treatment of superficial esophageal carcinoma. The ability of EUS to diagnose the depth of invasion was examined in 40 lesions with superficial esophageal carcinoma between January 1993 and April 1994. The depth of invasion was classified as m1 or m2, m3 or sm1, and sm2 or more. Mucosal carcinoma could be detected clearly by using the 20MHz miniature probe. The diagnostic accuracy was 82.5% in all 40 lesions, and 77.8% in mucosal carcinoma (included with sm1). The reasons for incorrect diagnosis were broadness of the lesion, microinvasion, and artifact of endoscopic biopsy. EUS is considered to be useful even for superficial esophageal carcinoma as one of the preoperative diagnostic imagings.

Esophageal Neoplasms↗
PubMed1994

Human cardiovascular and vestibular responses in long minutes and low +Gz loading by short arm centrifuge.

1.4 G, 1.7 G, and 2.0 G of +Gz and 60 minutes centrifugation was adopted to 20 healthy male subjects using 1.8 m radius centrifuge equipped to Nihon University School of Medicine. G was applied from lower G, considering G training effect for the subjects. Effects on performance decline and side effects of such a short-arm centrifugation were especially observed in the experiments, because this size of centrifuge could be used in space station in future for a strong countermeasure of cardiovascular deconditioning, demineralization from bone, etc. G training effect was observed same as higher and rapid G acceleration in fighter pilot. Subjects suffered from many types of discomfort; such as sensation of heaviness of diaphragm, cold sweat, nausea, irritable feeling, arrhythmia, tachycardia, rapid decrease of blood pressure, which sometimes caused interruption of G load. As 2.0 G and 60 minutes centrifugation seemed very tough load to the subjects, there should be necessary some G suit or other countermeasure, if we apply a higher G and/or longer G duration. Performance decline due to the load commonly continued for 1 hour or so. Side effects were observed in relation to neuro-vestibular, cardio-vascular, and autonomic nervous system.

Adult↗
PubMed1994

Artificial G-load and chemical changes of saliva.

Effectiveness of artificial G load is expected when it is used as a countermeasure against various bio-medical mishaps which are taking place in the micro-gravity environment, and probably more importantly, to prepare re-entry to the earth 1-G environment. Regarding the salivary chemical analysis, it has been known that, in case of (experimental) motion sickness, symptomatic outputs are delivered through the autonomic nervous system, and changes in salivary chemical components occur. In this study, accordingly, quantitative analyses of salivary potassium, sodium, chloride and total protein were performed before and after various levels of G loads which were produced by our short-radius human centrifuge. When the results were compared, the subjects who failed 60 minutes ride exhibited significantly higher post-load levels of potassium and sodium than those of successful 60 minutes riders. However, the differences between two groups were less clear in chloride and total protein. The result of present study indicates that salivary potassium and sodium are good indicators to represent autonomic nervous system function under the stressful condition produced by an artificial G load.

Adult↗
PubMed1994

[Results of annual health examination for the aged provided by the law that are predictive of increased mortality risk].

Possible risk factors associated with mortality were studied in a community using data derived from annual mass health examinations for the aged mandated by law. A total of 1,804 adults (685 men and 1,119 women) aged 40 or older in A-town, located on Tsushima Island, Nagasaki Prefecture, Japan who had participated in annual health examinations at least once between 1984 and 1990, were followed for a mean period of 4.9 years. After adjustment for age using Cox proportional hazards models, in men liver dysfunction (aspartate aminotransferase > 40 U/l or alanine aminotransferase > 35 U/l), fasting blood glucose > or = 110 mg/dl and glucosuria, and in women serum creatinine > or = 1.2 mg/dl, fasting blood glucose > or = 110 mg/dl and proteinuria were found to be associated with a significantly increased risk of total mortality. In multivariate analysis using all independent variables that were significantly associated with mortality in age-adjusted bivariate analysis, in men liver dysfunction and hyperglycemia, and in women hypercreatininemia and hyperglycemia, were significant predictors of mortality. These independent variables remained significant or marginally significant predictors of total mortality even after excluding the effects of 3 pancreatic cancer cases with liver dysfunction or hyperglycemia or 12 deaths within the first year of follow-up, being associated with at least two-fold increased hazard rate ratios. From these results, it is recommended that persons with these risk factors be followed intensively and counseled by public health personnel to modify risk factors.

Adult↗
PubMed1993

A triangular conditioning voltage wave does not influence spontaneous neuronal activity in the rat striatum.

A triangular potential wave applied shortly before each measuring triple pulse has been used in in vivo voltammetric experiments to ensure the maintenance of a high level of stability and sensitivity in the carbon fiber electrode. To investigate whether a triangular wave (0- +/- 1500 mV, 10 V/s slope) and a consecutive triple pulse affect spontaneous neuronal firing, extracellular recordings were made in the rat striatum at a distance of about 200-300 microns from the carbon fiber electrode while these potentials were being delivered. No significant change in the rate of spontaneous firing was found. A triangular pulse has proven to be very effective in lengthening the measurement lifetime of the carbon fiber electrode without interfering with the spontaneous activity of striatal neurons.

Animals↗
PubMed1992

Decarboxylation of exogenous L-3,4-dihydroxyphenylalanine in rat striatum as studied by in vivo voltammetry.

An in vivo voltammetric technique was used to determine whether striatal nondopaminergic neurons take up and decarboxylate exogenous L-3,4-dihydroxyphenylalanine (L-DOPA) and release it as dopamine. After the striatal serotonergic neurons of the rat had been destroyed by intraventricular injection of 5,7-dihydroxytryptamine, L-DOPA was administered intraperitoneally. It was found that changes in the dopamine concentration in the striatal extracellular fluid of the rat were the same as those in the nonlesioned rat. L-DOPA was also administered to the rat after the striatal perikarya had been destroyed by the intrastriatal injection of kainate. The striatal dopamine concentrations of the lesioned rat changed in parallel with 5,7-dihydroxytryptamine-lesioned rats, as well as the nonlesioned rats. Moreover, when normal rats were administered L-DOPA, the dopamine concentration was not increased in the cerebellum, where dopamine neurons do not exist. From these observations, it is concluded that exogenous L-DOPA is taken up, decarboxylated to dopamine, and released only in the striatal dopamine neurons.

5,7-Dihydroxytryptamine↗
PubMed1992

[A case report of true palmar aneurysm].

True palmar aneurysm is a rare disease of the hand. Only 12 cases of true palmar aneurysm have been reported in Japan. This occurs commonly in the hypothenar region. We experienced a 12-year-old boy who had a aneurysm of the left palmar hand successfully treated by surgery. The clinical diagnosis was established by ultra sound. Vascular reconstruction by end to end anastomosis was performed after excision of aneurysm. Pathology revealed this was true aneurysm.

Anastomosis, Surgical↗
PubMed1991

High-performance liquid chromatographic determination of pyrophosphate in the presence of a 20,000-fold excess of orthophosphate.

An HPLC method was based on anion-exchange separation of pyrophosphate (diphosphate) and orthophosphate and postcolumn spectrophotometric detection at 140 degrees C with a molybdenum(V)-molybdenum(VI) reagent. The reagent was easy to prepare, stable for at least 6 months at room temperature, and ready for the determination of pyrophosphate and orthophosphate by the so-called heteropoly blue method without use of any reducing agent. A photodiode-array detector for HPLC indicated the spectral characteristics of the heteropoply blue complex that was detectable at 330-800 nm. The HPLC method had a wide dynamic range from 3 x 10(-7) to 5 x 10(-4) M for both pyrophosphate and orthophosphate with a relative standard deviation of measurement of 10 approximately 2%. Pyrophosphate of 5 x 10(-7) and 5 x 10(-6) M, respectively, could be determined in the presence of a 20,000-fold excess of orthophosphate; 0.01 and 0.1 M.

Chromatography, High Pressure Liquid↗
PubMed1989

Effect of exogenous L-dopa on behavior in the rat: an in vivo voltammetric study.

L-DOPA was administered intraperitoneally (i.p.) or intraventricularly (i.v.t.) to freely moving rats to investigate the effects of exogenous L-DOPA itself on behavior. Striatal dopamine (DA) in the extracellular fluid was examined with microcomputer-controlled in vivo voltammetry, and behavioral change was observed. When L-DOPA was administered (i.p.) after pretreatment with benserazide, a peripheral DOPA decarboxylase inhibitor, behavioral change was elicited before the elevation in DA and suppressed before its reduction. After pretreatment with NSD-1015, a central DOPA decarboxylase inhibitor, behavioral change was also elicited, although DA was still not increased. When L-DOPA was injected (i.v.t.), the behavioral effect was manifested at once; DA was still unchanged at this time, but it increased after behavioral activity reached the maximum level. L-DOPA was also injected (i.v.t.) into rats with striatal lesions induced by 6-hydroxydopamine (i.v.t.). Behavioral change was manifested promptly after the injection. When the dose-response curves to different dosages of L-DOPA were examined in normal rats without striatal lesions, it was found to exhibit a steeper rise than that of DA. Finally, when rats were injected (i.p. or i.v.t.) with 3-O-methyl-DOPA (3-methoxytyrosine), a major metabolite of L-DOPA, no behavioral change was elicited, and no increase in DA was recognized. These experimental results indicated that L-DOPA is related directly to the manifestation of behavioral change.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1989

Adrenoleukodystrophy presenting as spinocerebellar degeneration.

The clinical features of 3 patients from a kindred with adrenoleukodystrophy and the analysis of their plasma sphingomyelin are described. Onset of symptoms was between the ages of 33 and 54 years. Ataxic gait and spasticity were the only symptoms noted during the early stage of the disorder. Dementia and optic atrophy were present in two of the cases. Baseline plasma cortisol was normal, but adrenocorticotropic hormone was elevated. Analysis of plasma sphingomyelin demonstrated an increase in very-long-chain (C24-C26) fatty acid. This study demonstrates that adrenoleukodystrophy may present with spinocerebellar symptoms.

Adrenocorticotropic Hormone↗
PubMed1988

In vivo voltammetric study of 6-hydroxydopamine-induced neuronal degradation.

Freely moving rats were injected intraventricularly with 200 micrograms of 6-hydroxydopamine (6-OHDA) and examined for transport of this substance to the striatum, degradation of dopamine (DA) neurons, and functional recovery through microcomputer-controlled in vivo voltammetry. Approximately 6 min after the injection, 6-OHDA began to appear in the extracellular fluid of the contralateral striatum. It increased linearly and began to decrease exponentially with the termination of the injection. Two hours after the injection with 6-OHDA, a peak began to appear at the same potential as the peak of DA in the differential pulse voltammogram. It persisted for approximately 3 days. When the rats were injected intraperitoneally with L-3,4-dihydroxyphenylalanine (L-Dopa), the conversion of L-Dopa to DA was not found 1 week after the 6-OHDA injection, but was clearly recognized 5 months after the injection. When the rats were examined for behavioral changes arising from the L-Dopa injection, they were found to be clearly less hyperactive 5 months after the 6-OHDA injection than 1 week after.

Animals↗