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Biomedical subjects

Y Masuda

Publications and source records attributed to Y Masuda.

At least 127 records · Page 7Linked to original sources
PubMed2000

Digging behavior of ddY mouse.

In the present studies, the behavior of ddY mice digging wood chips was carefully observed. When mice were individually placed on new 5 cm-thick wood chips, their behavior was found to be the same irrespective of their age or sex. The behavior was not prevented by non-noxious 5 black steel rods which were used to measure digging ability, and was not related to habituation or learning. But moist or dirty chips remarkably weakened digging ability. These findings strongly suggest that the digging behavior is a natural and instinctive one, but not an expression of anxiety as previously reported.

Adaptation, Psychological↗
PubMed2000

The effect of globopentaosylceramide on a depression model, mouse forced swimming.

We investigated the late effects of serotonergic drugs on mouse forced swimming and found that serotonin 1A antagonist NAN-190 hydrobromide (NAN-190) and serotonin 2 agonist R(-)-DO1 hydrochloride (DO1) increase the typical anti-depressive behavior climbing 6 hours after the intraperitoneal injection. With the use of ion exchanger, ultra filtration and chemical extraction methods, a substance having remarkable anti-depressive activity on mouse forced swimming was extracted from the serums of the mice treated with the drugs. The substance was strongly suggested to be a glycolipid having a specific sugar chain structure GalNAcalpha1-3GalNAc in its terminal. In fact, globopentaosylceramide, another glycolipid having the structure in the terminal also showed marked anti-depressive activity on mouse forced swimming, but globotetraosylceramide lacking the sugar chain structure did not. The GalNAcalpha1-3GalNAc-lipid reactivity in the serum and typical anti-depressive behavior climbing increased corresponding to the doses of NAN-190 and DO1. These findings clearly indicate that the terminal structure GalNAcalpha1-3GalNAc has the essential role in the anti-depressive activity of globopentaosylceramide, and that serotonin 1A antagonism and serotonin 2 agonism increase the production of an anti-depressive glycolipid having the terminal structure in mouse serum.

Amphetamines↗
PubMed2000

Repeated electroconvulsive shock treatment induces two humoral anti-depressive factors in mouse.

Forced swimming is considered a depression model. Repeated electroconvulsive shock treatment shows an anti-depressive effect in mice forced swimming. In serum of the mice treated with repeated electroconvulsive shock, the humoral anti-depressive factors were detected. The factors were the glycolipid having GalNAc alpha1-3GalNAc and mouse fibrinopeptide A having amino acid sequence TDTEKDGEFLSGGGV. The behavioral anti-depressive activity of the glycolipid was decreased by the low doses (100 to approximately 10 microg/kg) of dopamine 2 receptor antagonist sulpiride. Behavioral activity of the peptide was also decreased by the low doses (100 to approximately 1 microg/kg) of dopamine 1 receptor antagonist SCH-23390. The present findings clearly indicate that repeated electroconvulsive shock treatment induces the humoral anti-depressive factors affecting the dopaminergic neuronal system in mice.

Amino Acid Sequence↗
PubMed2000

The perineuronal proteoglycan surface coat in the adult rat brain, with special reference to its reactions to Gömöri's ammoniacal silver.

The present study showed that many neurons in the adult rat brain possessed a perineuronal sulfated proteoglycan surface coat which reacted to cationic iron colloid and aldehyde fuchsin. This surface coat was stained supravitally with Ehrlich's methylene blue and doubly stained with Ehrlich's methylene blue and aldehyde fuchsin. The surface coat was also stained with Gömöri's ammoniacal silver and doubly stained with Gömöri's ammoniacal silver and cationic iron colloid. The surface coat was usually expressed together with a nerve cell surface glycoprotein net detectable with lectin Wisteria floribunda agglutinin. These findings indicate that the perineuronal proteoglycan surface coat is identical to Cajal's superficial reticulum and contains some collagenous elements. It was further demonstrated that collagenase digestion erased Gömöri's ammoniacal silver impregnation within the perineuronal proteoglycan surface coat.

Animals↗
PubMed2000

[The quality of life after radical prostatectomy measured by general health questionnaire and visual analogue scales].

OBJECTIVES: The impact of radical prostatectomy on the quality of life (QOL) of patients were evaluated. MATERIALS AND METHODS: A total of 22 patients who underwent radical prostatectomy for clinically localized prostate cancer entered this study. Patients were asked to complete a questionnaire containing the general health questionnaire (GHQ) and a series of questions evaluating voiding function, incontinence and sexual dysfunction before and after the operation. In addition, the visual analogue scaled (VAS) questionnaire containing incontinence and sexual dysfunction was applied. RESULTS: No significant differences in GHQ were found between pre- and post operative status, but disease-targeted QOL such as sexual function was affected after the radical prostatectomy. In the points of incontinence and sexual dysfunction, VAS questionnaire significantly correlated with those of categorical questionnaires. CONCLUSIONS: There results suggest that GHQ is not affected, but disease-targeted QOL in some categories of sexual function is affected by radical prostatectomy, and that VAS questionnaires are not only useful for assessing the disease-targeted QOL but also easy to quantify QOL of the patients.

Aged↗
PubMed2000

Uptakes and images of 38K in rabbit heart, kidney, and brain.

UNLABELLED: The purpose of this study was to evaluate the kinetics and image quality of positron-emitting 38K (half-life, 7.6 min) and high-resolution small-animal PET in the heart, kidney, and brain of rabbits. METHODS: Studies were performed with 18 closed-chest anesthetized rabbits at baseline and during infusions of adenosine (0.2 mg/kg/min) and propranolol (0.5-1.0 mg/kg intravenously) using high-resolution small-animal PET. 38K was injected intravenously and dynamic PET imaging of the heart, kidney, or brain was performed for 3 min. Colored microspheres were injected into the left ventricle to measure organ blood flow. Arterial blood was withdrawn directly from the femoral artery, and, after the animals were killed, 38K activities in each organ were measured directly with a well counter. Uptake of 38K was calculated by dividing the 38K activities in each organ by the integral of the input function. The extraction fraction of 38K was estimated by dividing the uptake of 38K in each organ by the organ blood flow, measured by microspheres. RESULTS: The left ventricular myocardium and kidney were clearly visualized, but there was no visual 38K uptake in the brain. For the heart, kidney, and brain, respectively, average blood flow was 2.91 +/- 1.29, 5.49 +/- 0.71, and 0.57 +/- 0.11 mL/min/g, and the extraction fraction of 38K at baseline was 0.55 +/- 0.13, 0.48 +/- 0.13, and 0.022 +/- 0004. The Renkin-Crone model fit the relation between myocardial extraction and flow under a wide range of myocardial blood flow (r = 0.89). CONCLUSION: 38K is a suitable tracer for noninvasively showing the potassium kinetics of the heart, kidney, and brain by PET imaging.

Animals↗
PubMed2000

[Anesthetic management in pediatric interventional cardiology].

Interventional cardiology (n = 108) and cardiac angiography (n = 481) procedures in pediatrics performed between January 1996 and December 1998 were reviewed. Means (SD) of duration of anesthesia for interventional cardiology and cardiac angiography were 245 (130) and 152 (48) minutes, respectively (P < 0.001). Incidences of long operations requiring over 6 hours of anesthesia were 12 and 0%, respectively (P < 0.001). Incidences of hemodynamic derangements were 17 and 2.9%, and catheter-related complications were 7.4 and 0.83%, respectively (P < 0.001). Incidences of ICU admission were 7.4 and 0.62% those of emergency surgery were 4.6 and 0%, and those of blood transfusion were 4.6 and 0%, respectively (P < 0.001). Incidences of cardiopulmonary resuscitation, and cardioversion were also higher in interventional cardiology (P < 0.05), and all these emergency cases were rescued successfully. The risk of cardiac angiography is higher compared with general surgery, and the risk of interventional cardiology is higher than cardiac angiography in pediatrics. This study reconfirms that anesthesiologists should play an active role in care of pediatric patients undergoing high-risk procedures outside the operating room.

Anesthesia, General↗
PubMed2000

[Differential diagnosis of idiopathic cardiomyopathy from ischemic cardiomyopathy and hypertensive heart disease using non-invasive methods].

Although, the diagnosis of idiopathic cardiomyopathy is determined by cardiac catheterization including myocardial biopsy, non-invasive diagnosis is important. The most useful method is nuclear cardiology to differentiate dilated cardiomyopathy from ischemic cardiomyopathy. Cardiac images in ischemic cardiomyopathy have wider perfusion and metabolic defects than in dilated cardiomyopathy using Tl-201, Tc-99m perfusion tracers, I-123 BMIPP, N-13 NH3 and F-18 FDG. The degree of heterogenecity of the myocardium is higher in ischemic cardiomyopathy than in dilated cardiomyopathy by these tracers. Left ventricular hypertrophy is common finding in hypertension and hypertrophic cardiomyopathy. However, in hypertensive heart disease the left ventricular wall thickness rarely exceed than 20 mm, and the septal wall thickness/posterior wall thickness is not more than 1.5, which are frequently shown in hypertrophic cardiomyopathy. Right ventricular hypertrophy near the ventricular septum is also one of the characteristic findings in hypertrophic cardiomyopathy.

Cardiomyopathy, Dilated↗
PubMed2000

[A case of anaphylaxic shock due to latex glove used on internal examination and on the probe of intrauterine echogram].

A 15 year old female with uterus bicornis bicollis was admitted for operation. She had a history of atopic dermatitis and allergy to buckwheat, raw egg and latex. Two months previously she had developed whole body flushing during dental treatment, and latex glove used by the dentist had been suspected as the cause. Prior to the operation she underwent internal examination and intrauterine echogram in which a latex glove was carelessly used by another gynecologist who had not confirmed her past history. After 30 minutes, dyspnea and urticaria without itching, appeared suddenly. Blood pressure decreased to 80/50 mmHg and heart rate increased to 120 beats.min-1. She was then transferred to our ICU. Methylprednisolone was administered intravenously for dyspnea and circulatory collapse. After 3 hours, the patient made an uneventful recovery. The increased plasma latex protein-specific IgE levels confirmed anaphylaxis to latex. The increasing incidence of potentially life-threatening allergic reactions to latex has caused mounting concern over recent years. We may suspect latex allergy when an anaphylaxic reaction or shock of unknown origin occurs. In hospitals, latex free products must be prepared for use with latex allergic patients and for protection of medical staff with this allergy.

Adolescent↗
PubMed1999

Prognostic utility of myocardial blood flow assessed by N-13 ammonia positron emission tomography in patients with idiopathic dilated cardiomyopathy.

Previous studies in patients with idiopathic dilated cardiomyopathy (IDC) have suggested that myocardial perfusion is impaired and spatially heterogeneous in such cases. Our objective was to identify any association between an abnormality in myocardial perfusion and the prognosis of patients with IDC. We collected data on N-13 ammonia positron emission tomography (PET) studies performed in 26 patients with IDC (9 nonsurvivors, 17 survivors) and in 8 normal control subjects. Regional myocardial blood flow (rMBF) was quantified using N-13 ammonia positron emission tomography and the Simple flow model. The spatial heterogeneity of myocardial perfusion was assessed by calculating the coefficient of variance of rMBF. Mean rMBF of the survivors was significantly lower (0.54 +/- 0.13 ml/min/g) than that of control subjects (0.66 +/- 0.06 ml/min/g) (p = 0.03 vs control), but did not differ significantly between nonsurvivors (0.58 +/- 0.15 ml/min/g) and control subjects. The coefficient of variance of rMBF was significantly higher in nonsurvivors than in either survivors or control subjects (0.24 +/- 0.08 vs 0.15 +/- 0.08, p = 0.007, and 0.16 +/- 0.05, p = 0.03, respectively). The probability of 3-year survival (Kaplan-Meier method) was 33.0% in subjects whose coefficient of variance of rMBF was above the median compared with 90.0% in subjects whose coefficient of variance of rMBF was below the median (p = 0.01). The probability of 3-year survival did not differ among subjects whose mean rMBF was above versus below the median (61.5% vs 62.9%, respectively). The results suggest that the prognosis of patients with IDC is associated with the spatial heterogeneity of myocardial perfusion, not with initial absolute rMBF.

Adult↗
PubMed1999

Characteristics of the muscle spindle endings of the masticatory muscles in the rabbit under halothane anesthesia.

To explore the response characteristics of muscle spindle units in the masticatory muscles in the rabbit, the responses of muscle spindle units were recorded from the mesencephalic trigeminal nucleus (MesV) under halothane anesthesia during ramp-and-hold stretches. Three firing patterns, initial burst (IB) at the onset of the dynamic phase, negative adaptation (NA) at the end of the dynamic phase and firing during the release (FDR) phase, were observed during muscle stretch. IB was present at higher stretch velocities, FDR at lower stretch velocities. The velocity at which an IB or FDR was present was different from unit to unit. Because, within the range of the velocities of stretch tested, units with NA always showed NA and units without NA never did, all recorded units were divided into two groups on the basis of the existence of NA (NA(+) or NA(-) units). Response characteristics of the two groups were then compared. NA(+) units showed an IB more frequently and FDR less frequently than NA(-) units. NA(+) units had significantly higher dynamic responsiveness and discharge variability than NA(-) units. The conduction velocity of the afferents of NA(+) units was higher than that of NA(-) units. However, distributions of these measurements were not bimodal. These results suggest that NA is the useful criteria to classify the muscle spindle endings in the masticatory muscles in the rabbit under halothane anesthesia.

Anesthesia↗
PubMed1999

Effects of aspirin and trapidil on cardiovascular events after acute myocardial infarction. Japanese Antiplatelets Myocardial Infarction Study (JAMIS) Investigators.

Aspirin therapy confers conclusive net benefits in the acute phase of evolving myocardial infarction, but no clear evidence of benefit from the long-term use of aspirin after acute myocardial infarction (AMI) has been shown in any single study. This multicenter study, the Japanese Antiplatelets Myocardial Infarction Study, was performed to find out whether aspirin or trapidil would improve clinical outcome compared with no antiplatelets in postinfarction patients. The study was a multicenter, open-label, randomized controlled trial of aspirin 81 mg/day, trapidil 300 mg/day, and no antiplatelets in patients with AMI admitted within 1 month from the onset of symptoms. Seven hundred twenty-three patients were enrolled at 70 hospitals in 18 prefectures of Japan; 250 were randomly assigned to treatment with 81 mg aspirin (aspirin group), 243 to that with trapidil (trapidil group), and 230 were not given antiplatelet agents. The mean follow-up period was 475 days. This study demonstrated that long-term use of aspirin at the dose of 81 mg/day reduced the incidence of recurrent AMI compared with the group receiving no antiplatelets after AMI (p = 0.0045) and that trapidil also reduced the occurrence of reinfarction compared with the group receiving no antiplatelets, but the difference was not significant (p = 0.0810). The incidence of cardiovascular events including cardiovascular death, reinfarction, uncontrolled unstable angina requiring admission to hospital, and nonfatal ischemic stroke was reduced in the group receiving 300 mg trapidil daily compared with the group receiving no antiplatelets (p = 0.0039). The use of aspirin 81 mg/day provided almost no benefit over no antiplatelets therapy in the incidence of cardiovascular events. In conclusion, low-dose aspirin (81 mg) effectively prevented recurrent AMI in postinfarction patients after thrombolysis or coronary angioplasty when used over a long term. Furthermore, the long-term use of trapidil resulted in a significant reduction in the incidence of cardiovascular events.

Aged↗
PubMed1999

Induction of food intake by a noradrenergic system using clonidine and fusaric acid in the neonatal chick.

To clarify noradrenergic systems on food intake of the neonatal chicks, we examined the effects of i.c.v injection of clonidine (CLON), an alpha2-receptor agonist, and fusaric (5-butylpicolinic) acid (FA), a dopamine (DA)-beta-hydroxylase (DBH) inhibitor. Although a high dose (250 ng) of CLON induced a narcoleptic response and reduced food intake, food intake at 30 min post-injection was enhanced by lower doses (25 and 50 ng) of CLON. Central administration of FA (25, 50 and 100 microg) increased food intake in a dose-dependent fashion. It is suggested that feeding behavior is stimulated by low levels of CLON and decreased by further production of norepinephrine (NE), and FA may play the disturbance of sleeping and then enhance food intake.

Adrenergic alpha-Agonists↗
PubMed1999

Single-turnover analysis of mutant human apurinic/apyrimidinic endonuclease.

Apurinic/apyrimidinic endonuclease (AP endo) is a key enzyme in the repair of oxidatively damaged DNA. Using single-turnover conditions, we recently described substrate binding parameters for wild type human AP endo. In this study, we utilized four enzyme mutants, D283A, D308A, D283A/D308A, and H309N, and assayed them under steady state and single-turnover conditions. The turnover number of the single aspartate mutants was decreased 10-30-fold in comparison to that of the wild type. The decrease in the turnover number was accompanied by a 17- and 50-fold decrease in the forward rate constant (kon) for substrate binding by D308A and D283A, respectively. The dissociation rate constant for substrate (koff) was unchanged for the D308A mutant but was 10 times faster for the D283A mutant than for the wild type. The apparent Km values for both of the single aspartate mutants were about equal to their respective KD values. To account for the kinetic behavior of the D308A mutant, it was necessary to insert a conformational change into the kinetic scheme. In contrast to the single aspartate mutants, the turnover number for the double mutant was 500-fold lower than that of the wild type, its apparent Km was 2.5-fold higher, and binding to substrate was weak. Mutation of His309 caused the greatest decrease in activity, resulting in a turnover number that was more than 30000-fold lower than that of the wild type and an apparent Km that was 13-fold higher, supporting the notion that His309 is intimately involved in catalysis. Molecular dynamics simulation techniques suggested that conversion of either aspartate to alanine resulted in major shifts in the spatial localization of key amino acids. Despite the fact that the two aspartates flank His309, the movement they engendered was distinct, consistent with the differences in catalytic behavior. We suggest that the conformation of the active site is largely maintained by the two aspartates, which enable efficient binding and cleavage of abasic site-containing DNA.

Alanine↗
PubMed1999

Tiam1 is involved in the regulation of bufalin-induced apoptosis in human leukemia cells.

Bufalin, a component of the Chinese medicine chan'su, induces apoptosis in various lines of human tumor cells, such as leukemia HL60 and U937 cells, by altering the expression of apoptosis-related genes, for example, bcl-2 and c-myc. In this study, we characterized a gene that is involved in bufalin-induced apoptosis by the differential display (DD) technique. The partial nucleotide sequence of one of the differentially expressed clones obtained after treatment with bufalin was identical to that of the human gene for Tiam1. When U937 cells were treated with 10(-7) M bufalin, expression of both Tiam1 mRNA and the protein was induced 1 h after the start of the treatment. The increase of Tiam1 mRNA was transient but the level of Tiam1 protein continued to increase at least for 6 h. In addition, the activities of Rac1 and p21-activated kinase (PAK) were also stimulated by bufalin treatment. To evaluate the role of Tiam1 in the apoptotic process, we examined the effects of the expression of sense and antisense RNA for Tiam1 in U937 cells. Apoptosis was strongly induced by bufalin in cells that expressed sense RNA for Tiam1 as compared to apoptosis in control cells treated with bufalin only. Cells expressing antisense RNA for Tiaml were significantly more resistant than the control bufalin-treated cells to induction of DNA fragmentation in response to bufalin. Moreover, sense transformants had elevated activities of PAK and c-Jun NH2-terminal kinase (JNK). These results suggest that Tiaml might play a critical role in bufalin-induced apoptosis through the activation of Rac1, PAK, and JNK pathway.

Antineoplastic Agents↗
PubMed1999

Intracerebroventricular administration of mouse leptin does not reduce food intake in the chicken.

Recently, it has been suggested that leptin plays an important role in regulation of food intake and metabolism in rats and mice, however, the effect of central administration of leptin on food intake in chicks has not been reported. We have investigated the anorexigenic effect of leptin administered by intracerebroventricular (i.c.v.) injection in chicks using mouse leptin, which shows 97% homology to chicken leptin. Three experiments were conducted. After being deprived of food for 3 h, male broiler chicks were administered leptin by i.c.v. injection at dose levels of 0, 0.2, 1.0 and 5.0 microg (Experiment 1) or 0, 2.5 and 5.0 microg (Experiment 2). The birds were allowed free access to the diet for 2 h (Experiment 1) and 24 h (Experiment 2) after treatment. Male Single Comb White Leghorn chicks were used in Experiment 3 and were treated in the same manner as in Experiment 1. In all experiments, central administration of mouse leptin did not influence food intake in the time periods examined. It appears that either mouse leptin does not bind to the chicken leptin receptor or in the chicken brain the leptin receptor may be absent.

Analysis of Variance↗