Search PubMed⌕ Search

Biomedical subjects

Y Masuda

Publications and source records attributed to Y Masuda.

At least 523 records · Page 29Linked to original sources
PubMed1993

[Quantitation of regional myocardial blood flow using continuous inhalation of C15O2 and positron emission tomography].

A C15O2 continuous inhalation and a steady-state theory using positron emission tomography (PET) have been used to quantitate regional cerebral blood flow. We extended this method for quantitative regional myocardial blood flow (RMBF) measurement. Forty-three patients, involving 4 normal volunteers, 16 patients with coronary heart disease (CHD), 20 patients with hypertrophic cardiomyopathy (HCM), and 3 patients with dilated cardiomyopathy (DCM), were studied. 6 min-scan was recorded in the steady-state condition during C15O2 continuous inhalation. A C15O inhalation scan was required to obtain the blood pool image. The subtracted image showed myocardial perfusion image. These images demonstrated homogeneous accumulation in normal volunteers. Reduced accumulation were detected in patients with myocardial infarction. Hypertrophied myocardium was demonstrated in patients with HCM. Diffuse heterogeneous accumulation was demonstrated in patients with DCM. Fourteen patients with HCM, whose left ventricular myocardial thicknesses were more than 20 mm, were selected for the RMBF measurement to minimize errors due to the partial volume effect. The arterial blood activity was measured by assigning a region of interest to the left atrial cavity on PET images. RMBF was calculated using the steady-state theory. Calculated flow values ranged from 21.2 to 152.6 ml/min/100 g. The good correlation was obtained between RMBF using 13NH3 first pass method and RMBF using gas inhalation method in six patients. These results indicate that C15O2 PET has the potential capability for the noninvasive quantitation of RMBF.

Adult↗
PubMed1993

[Cardioprotective effect of cromakalim, a K+ channel opener, on isolated globally ischemic and reperfused rat hearts].

Examination was made of cardioprotective effect related to the ATP-sensitive K+ (KATP) channel on isolated globally ischemic reperfused rat hearts using cromakalim, a putative ATP-sensitive K+ channel opener. The hearts were subjected to 20 min Langendorff perfusion with Krebs Henseleit Bicarbonate Buffer (KHBB) (70 cmH2O, 37 degrees C), followed by 30 min ischemia at 36 degrees C, and 30 min reperfusion with KHBB, with (cromakalim group) or without (control group) pretreatment by 10 microM cromakalim added to KHBB for 5 min prior to ischemia. Before ischemia, no significant change in heart rate (HR), left ventricular developed pressure (LVDP) or coronary flow (CF) by 10 microM cromakalim could be detected. The two groups were the same in CF during reperfusion, but recovery of HR and LVDP significantly improved in the cromakalim group. Creatine kinase (CK) leakage in the cromakalim group was significantly less than in the control group during reperfusion. Cromakalim is thus shown to reduce the myocardial injury during ischemia and reperfusion. Intracellular Ca2+ content of the cromakalim group appeared lower than that of the control group at 30 min of reperfusion. At 5-30 min of reperfusion, in the cromakalim group, intracellular Ca2+ storage was prevented, leading to a good recovery of cardiac function, while in the control group, intracellular Ca2+ increased and recovery of cardiac function was poor. After pretreatment with 10 microM cromakalim, intracellular K+ content of the cromakalim group was significantly lower than in the control group before ischemia. At 5 min of reperfusion, intracellular K+ content of the cromakalim group was slightly less than that of the control group.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Inhibitory effect of zonisamide on human carbonic anhydrase in vitro.

We examined the relative potencies of zonisamide (CAS 68291-97-4) to acetazolamide in inhibiting carbonic anhydrases in human erythrocytes and purified human carbonic anhydrase I and II in vitro and found them to be about 1/150, 1/8 and 1/188, respectively. The IC50 values of zonisamide and acetazolamide for the inhibition of erythrocyte enzymes were close to those of purified carbonic anhydrase II. This result indicates that zonisamide actually differs from acetazolamide in their actions on the physiological events which are coupled with CO2 hydration in vivo.

Acetazolamide↗
PubMed1993

[Studies on screening for hard-of-hearing children by questionnaire. 2. Comparison of response rates to individual questions in 1-year-6-month-old children with normal hearing and hearing loss using a health screening questionnaire].

We report the results of studies on responses to questions on hearing impairment, comparing 165 school children whose hearing was diagnosed as normal at the time of admission to primary school and 37 children with hearing loss attending facilities for children with this disability. These children had been covered by similar surveys as part of the health screening for 1-year-6-month-old infants conducted by municipal authorities. Significant differences between the two groups were noted in the response rates to all questions on hearing. Similar differences were noted in the responses to questions on family history of hearing impairment. There were no significant differences in the incidences of asphyxia and jaundice at birth. The most striking differences were noted in the response rates to questions 6, 7, 8, 10, 11, 16, and 18. Most useful and universally valid in this survey were questions 8, 10 and 18 in addition to the question on whether or not parents suspected infantile hearing loss.

Child, Preschool↗
PubMed1992

Deconjugating activity for sulfoconjugated dopamine in homogenates of organs from dogs.

To clarify the possibility that sulfoconjugated dopamine (DA) may play a physiological role by being converted to active free DA, we examined the deconjugating activity in homogenates of organs from dogs. Each tissue homogenate was incubated with sulfoconjugated DA, and the deconjugating activity of the organs was compared. The kidney and liver exhibited the highest deconjugating activities. In contrast, the intestine and heart showed lower arylsulfatase activities, and almost no activity was found in the brain or skeletal muscle. Moreover, in the heart, the deconjugating activity for sulfoconjugated DA was higher in the atrium than the ventricle. These results indicate that sulfoconjugated DA is converted to active free DA in homogenates of organs from dogs and that the deconjugating activity varies between different parts of an organ. Sulfoconjugated DA must be looked upon as a possible precursor or reservoir for the production of active free DA.

Animals↗
PubMed1992

Binding sites for pituitary adenylate cyclase activating polypeptide (PACAP): comparison with vasoactive intestinal polypeptide (VIP) binding site localization in rat brain sections.

Pituitary adenylate cyclase activating polypeptide (PACAP) is structurally similar to vasoactive intestinal polypeptide (VIP). We investigated the characteristics and topographical distribution of [125I]PACAP binding sites compared with those of [125I]VIP binding sites in the rat brain. Radiolabeled PACAP and VIP showed highly specific binding to sections at the level of the dorsal hippocampus. The specific binding of [125I]PACAP was 10 times higher than that of [125I]VIP in hippocampal sections. [125I]PACAP binding was scarcely displaced by unlabeled VIP, while [125I]VIP binding was effectively displaced by unlabeled PACAP. Therefore, PACAP binding sites may reflect both PACAP specific binding sites and VIP/PACAP binding sites. However, the amount of VIP/PACAP binding sites was negligibly low. Autoradiography revealed that [125I]PACAP binding sites were dense in the piriform cortex, diagonal band, accumbens nucleus, anterior part of the striatum, hippocampal formation, habenular nucleus, lateral hypothalamic area, superior colliculus and dorsal raphe nucleus. Moderate to high labeling was observed in the medial septal nucleus, olfactory tubercle, caudal part of the striatum, most parts of the thalamus, supraoptic and periventricular hypothalamic nuclei, central gray, substantia nigra pars compacta, locus coeruleus, pontine reticular nucleus and cerebellum. Distribution pattern was remarkably different from that of [125I]VIP binding sites in the hippocampal formation, lateral hypothalamic area, substantia nigra pars compacta, pontine reticular nucleus and cerebellum. The present results suggest that PACAP may have a physiological role in the regulation of the central nervous system.

Animals↗
PubMed1992

Pituitary adenylate cyclase activating polypeptide provokes cultured rat chromaffin cells to secrete adrenaline.

Pituitary adenylate cyclase activating polypeptide (PACAP) provoked the rat chromaffin cells to secrete adrenaline. Within 20 min, the amount of adrenaline secreted by PACAP (10(-8) M) was as much as that caused by acetylcholine (10(-4) M). PACAP, but not acetylcholine, induced a long-term (over 120 min) increase in secretion of adrenaline. PACAP also activated adenylate cyclase and elevated cytosolic Ca2+ concentration. Furthermore, we found immunoreactive PACAP and PACAP binding sites in the rat adrenal medulla. These results suggest that PACAP has an important role in stimulating secretion of adrenaline in the adrenal medulla.

Adrenal Cortex↗
PubMed1992

Human T-cell leukemia virus type I associated lymphadenitis.

Histopathologic changes in lymph nodes were examined from ten patients with mild lymphadenopathy, a few atypical lymphocytes in their peripheral blood, skin lesions, and proviral DNA of human T-cell leukemia virus type I (HTLV-I) in their nodes. The proviral DNA of HTLV-I was detected by southern blot analysis, in situ hybridization, and/or polymerase chain reaction techniques. The lymph nodes showed preserved nodal architecture with diffuse infiltration of small to intermediate-sized lymphocytes in association with scattered transformed lymphocytes and a few immunoblast-like cells in the enlarged paracortex. The infiltrating lymphocytes were positive for CD4, but neither rearrangement nor deletion of T-cell receptors and immunoglobulin heavy chain genes was detected. Eight of ten patients received no therapy, and all patients were alive and healthy more than 5 months after the biopsies. The histologic findings resembled those of a viral infection and could be distinguished from HTLV-I associated lymphomas.

Adult↗
PubMed1992

Reversal by 3,3',5-triido-L-thyronine of the working memory deficit, and the decrease in acetylcholine, glutamate and gamma-aminobutyric acid induced by ethylcholine aziridinium ion in mice.

The effect of 3,3',5-triiodo-L-thyronine (T3) on working memory in ethylcholine aziridinium ion (AF64A)-treated mice was studied in a delayed non-matching to sample task using a T-maze. After behavioural testing was completed, mice were killed by microwave irradiation and regional brain levels of acetylcholine, aspartate, glutamate, glutamine, glycine, taurine, and gamma-aminobutyric acid (GABA) were measured by high-performance liquid chromatography with electrochemical detection. Treatment with AF64A (7 nmol, i.c.v.) produced a deficit in working memory performance in the non-matching to sample task at 30 s delay, and decreased acetylcholine, glutamate, and GABA levels in the hippocampus, but not in the septum and cerebral cortex. Administration of T3 (0.3 mg/kg, p.o., once daily for 6 days) to AF64A-treated animals improved the deficit in working memory performance and reversed the decrease in acetylcholine, glutamate, and GABA levels in the hippocampus. These results indicate that the deficit in performance induced by AF64A can be improved by T3 administration.

Acetylcholine↗
PubMed1992

Two-color flow cytometric analysis of splenic lymphocyte subpopulations in patients with gastric cancer.

Lymphocyte subpopulations of the spleen were assayed in 26 patients with gastric cancer and 5 patients with benign disease using two-color flow cytometric analysis. The ratio of Leu 2a+.Leu 15+ cells, or suppressor T cells, in the gastric cancer patients was about 6 per cent, being higher than that in the patients with benign disease (p less than 0.05). There were fewer Leu 7+.Leu 11- cells, or natural killer-NK-cells, in the gastric cancer patients in stage III or IV than in those with stages I or II (p less than 0.05). The ratio of Leu 3a+.Leu 8- cells, or helper T cells, in the stage IV patients accounted for about 15 per cent of the splenic lymphocytes, which was less than that seen in the patients in stages I or II (p less than 0.05). The ratio of Leu 2a+.Leu 15- cells, or cytotoxic T cells, was approximately twice that of suppressor T cells. The pre-operative administration of lentinan plus OK-432 increased the ratio of Leu 4+.HLA-DR+ cells, or activated T cells, and cytotoxic T cells (p less than 0.05 and p less than 0.01, respectively). The above results suggest that lymphocyte subpopulations in the spleen may have more immunosuppressive potential in proportion with the stage of gastric cancer, but that this reduced immune state may be altered when lentinan and OK-432 are given to these patients.

Adult↗
PubMed1992

A rapid assay for neurotransmitter amino acids, aspartate, glutamate, glycine, taurine and gamma-aminobutyric acid in the brain by high-performance liquid chromatography with electrochemical detection.

For simultaneous assay of the five neurotransmitter amino acids, Asp, Glu, Gly, Tau, and GABA in brain tissues, a very rapid and simple chromatographic method using high-performance liquid chromatography with electrochemical detection in combination with o-phthalaldehyde derivatization is described. Because the present method permits the determination of these five amino acids within less than five minutes in one chromatographic run, up to 100 samples a working day can be analyzed using an autosampler. Within-run coefficients of variation for these five amino acids were less than 2% (n = 20). The quantitative detection limit was 2.5 pmol for the 5 amino acids. The present method has been applied to the measurement of the five amino acid neurotransmitter levels in several discrete brain regions of mice treated with and without electroconvulsive shock.

Amino Acids↗
PubMed1992

Effects of nefiracetam, a novel pyrrolidone derivative, on brain monoamine metabolisms in mice.

The effects of acute and chronic administration of nefiracetam, a pyrrolidone derivative, on monoaminergic neurotransmitter systems in the mouse hippocampus, frontal cortex, hypothalamus, and striatum were studied. The levels of monoamines and of their metabolites were measured by high performance liquid chromatography with electrochemical detection on the first, 7th, and 14th days after nefiracetam was given. The neurochemical effects of nefiracetam were compared with those of oxiracetam and indeloxazine. Acute administration of nefiracetam (10 mg/kg, po) and oxiracetam (10 mg/kg, po) had no effect on the levels of noradrenaline (NA), dopamine (DA), or 5-hydroxytryptamine (5-HT), or on the levels of their metabolites, 3-methoxy-4-hydroxyphenylglycol (MHPG), 3,4-dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), and 5-hydroxyindoleacetic acid (5-HIAA), in any of the regions examined. In contrast, a single dose of indeloxazine (10 mg/kg, po) decreased the levels of MHPG, DOPAC, and 5-HIAA in all regions examined. After chronic administration of nefiracetam (10 mg/kg, po, once daily), the levels of MHPG, DOPAC, and 5-HIAA were higher than control in all regions on the 14th day only. Oxiracetam (10 mg/kg, po, once daily) similarly increased the levels of MHPG, DOPAC, and 5-HIAA in the hippocampus, frontal cortex, and striatum, but not in the hypothalamus. Conversely, indeloxazine (10 mg/kg, po, once daily) decreased the levels of MHPG and 5-HIAA in all regions and the levels of DOPAC and HVA in the hippocampus and striatum as measured on the 7th and 14th days. These results show that nefiracetam has a delayed effect on brain monoaminergic metabolism, and that its effects are similar to those of oxiracetam, but clearly different from those of indeloxazine.

Animals↗
PubMed1992

A case of histiocytic necrotizing lymphadenitis with bone marrow and skin involvement.

We report a case of histiocytic necrotizing lymphadenitis (HNL) with bone marrow extension in a 29-year-old male in which many large mononuclear cells infiltrated the bone marrow and mimicked malignant lymphoma. A lymph node biopsy confirmed the diagnosis of HNL. Immunohistologically, the infiltrating cells in the bone marrow were positive for lysozyme, LeuM1, Kp-1 and T-cell markers. The cells did not show haemophagocytosis. A skin biopsy from an accompanying facial skin rash revealed a proliferation of large cells similar to those observed in affected foci of the lymph node in subcutaneous tissue. The infiltrating cells were mainly lysozyme and Kp-1-positive histiocytes, some with phagocytosis of nuclear debris but none characteristic of haemophagocytosis. Transformed T-cells were also infiltrating.

Adult↗
PubMed1992

Evaluation of morphological changes of the atherosclerotic aorta by enhanced computed tomography.

Enhanced and non-enhanced computed tomography (CT) were performed in 405 subjects (222 men; 183 women; mean age 57 years). Intimal atherosclerotic changes of the aorta were quantified by enhanced CT, revealing the atheromatous intima to be projecting and thick-walled, while non-enhanced CT demonstrated aortic calcification. We measured the degree of aortic intimal changes at various segments of the aorta. In 224 cases, CT was performed from the aortic root to the bifurcation of the abdominal aorta. Intimal changes were found predominantly at the aortic arch, the middle descending thoracic and the infrarenal abdominal aorta. As for the intimal changes, aortic calcification and aortic pulse wave velocity were significant atherosclerotic characteristics. The aortic diameter did not show a significant association with intimal change. Among the various atherosclerotic risk factors, intimal change was significantly associated with age, systolic blood pressure, serum total cholesterol and diabetes mellitus, whereas gender, diastolic blood pressure, relative weight and cigarette use were not significantly related. For coronary artery disease and arteriosclerosis obliterans, aortic intimal changes constituted a significant atherosclerotic feature. In cerebrovascular disease, however, aortic intimal change did not play a significant role.

Adolescent↗
PubMed1992

Pharmacological properties of ceruletide in the vertical and horizontal locomotor activities of mice.

To clarify the pharmacological properties of ceruletide (CER) and cholecystokinin-octapeptide (CCK-8) with respect to vertical (VLA) and horizontal (HLA) locomotor activities of mice, effects of pretreatment with CER (0.5, 5, and 50 micrograms/kg, IP) and CCK-8 (5, 50, and 500 micrograms/kg, IP) on apomorphine (0.1 mg/kg, SC)- and clonidine (0.1 mg/kg, SC)-induced hypo-VLA and -HLA and on apomorphine (1 mg/kg, SC)-induced hyper-VLA and -HLA were examined. CER and CCK-8 had a dose-dependent inhibitory effect on VLA and HLA in intact mice. Pretreatment with CER had a biphasic effect (increase and decrease) on apomorphine- and clonidine-induced hypo-VLA, as well as an effect on apomorphine-induced hypo-HLA, a decreased effect on clonidine-induced hypo-HLA, and a decreased effect on apomorphine-induced hyper-VLA and -HLA. On the other hand, pretreatment with CCK-8 had no effect on apomorphine- and clonidine-induced hypo-VLA and -HLA and a decreased effect on apomorphine-induced hyper-HLA but not on hyper-VLA. These results suggest that for apomorphine- and clonidine-induced locomotion in mice CER has pharmacological properties different from those of CCK-8.

Animals↗