Search PubMed⌕ Search

Biomedical subjects

G Takada

Publications and source records attributed to G Takada.

At least 19 recordsLinked to original sources
PubMed1996

Effect of anoxia on striatal monoamine metabolism in immature rat brain compared with that of hypoxia: an in vivo microdialysis study.

We examined in 5-day-old rats the effects of either anoxia or 8% hypoxia on extracellular monoamines such as dopamine (DA), 3,4-dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), norepinephrine (NE), 5-hydroxytryptamine (5-HT), and 5-hydroxyindole-3-acetic acid (5-HIAA) using in vivo microdialysis and subsequent HPLC. After stabilization 64 animals were exposed to 100% nitrogen for 16 min and 40 animals to 8% oxygen for 128 min. Both anoxia and hypoxia produced acute increase in the striatal extracellular DA (anoxia: P < 0.001, hypoxia: P < 0.01). Especially in anoxia, DA levels increased transiently to 2000-times the basal levels and 6-times higher than those in hypoxia. NE also increased in both anoxia and hypoxia. DOPAC and HVA decreased during hypoxia (P < 0.01 and P < 0.001, respectively), while those in anoxia were unchanged. In anoxia, decrease tendency of their levels were in short duration and that of 5-HIAA was followed by gradual increase (P < 0.001). These data demonstrated that brief exposure to anoxia or hypoxia had significant influence on striatal monoamine metabolism in immature brain and the pattern of change of monoamine in anoxia was different from that in hypoxia.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1996

Effects of cardiac output on Doppler transmitral and transtricuspid flow velocity patterns in very low birth weight infants.

We studied effects of cardiac output on Doppler transmitral and transtricuspid flow velocities in 24 appropriate for gestational age premature infants. We measured peak flow velocity of early diastole (peak E) and atrial contraction (peak A), ratio of peak flow velocity of early diastole to atrial contraction (peak E/A), total flow velocity-time integral, the first third filling fraction, peak filling rate normalized to stroke volume, and deceleration time (DT). Cardiac output was calculated as the product of the aortic flow velocity-time integral, aortic valve area, and heart rate. The cardiac output increased significantly with advancing gestational age and body weight (r = 0.78 and 0.86, P < 0.01, respectively). With increasing cardiac output, the transmitral as well as transtricuspid peak E, peak E/A, and total flow velocity-time integral increased significantly without any change in the peak filling rate normalized to stroke volume, peak A, and deceleration time. The transmitral as well as transtricuspid peak E did not correlate with the heart rate. Although these results do not establish whether changes in ventricular relaxation process or in cardiac output is responsible for the progressive increase in the peak E and peak E/A. Unchanged peak filling rate normalized to stroke volume of the left and right ventricles suggest that changes in cardiac output with maturity is, in fact, one of the important contributory factors. This evidence should be borne in mind in interpreting ventricular diastolic filling as an index of ventricular diastolic function in premature infants.

Blood Flow Velocity↗
PubMed1996

Identification and characterization of cellulose-binding domains in xylanase A of Clostridium stercorarium.

The xynA gene encoding a major xylanase of Clostridium stercorarium F-9 was sequenced. The structural gene consists of an open reading frame of 1533 bp encoding a protein of 511 amino acids with an M(r) of 56,519. XynA consists of a catalytic domain belonging to family G at the NH2-terminus and two direct repeats of about 90 amino acids with a short spacing at the COOH-terminus. The repeated sequences, CBDI and CBDII, were not homologous with amino acid sequences of the CBDs classified into families I to V. Nevertheless, XynA showed an affinity for insoluble cellulose such as Avicel. Binding of XynA to Avicel was strongly dependent on the concentration of the incubation buffer and was inhibited by Triton X-100. XynA bound to Avicel (2.4 nmol/g-cellulose) and acid-swollen cellulose (180 nmol/g-cellulose), suggesting that this enzyme has higher affinity for amorphous cellulose than for crystalline cellulose. Functions of CBDI and CBDII were investigated by constructing the mutant enzymes and evaluating the cellulose-binding ability of each of them. XynA4 lacking CBDI and XynA5 lacking CBDII bound to Avicel to a lesser extent than the parental enzyme XynA; but XynA6, devoid of both CBDs, did not bind at all, indicating that CBDI and CBDII each functioned independently as CBD in XynA and their binding capacity was additive. Although the Ruminococcus albus endoglucanase EgIV that was joined to CBDs of XynA acquired cellulose-binding ability, the substrate specificity of EgIV was not altered in the presence or absence of CBDs.

Amino Acid Sequence↗
PubMed1996

Changes in left ventricular volume and systolic function before and after the closure of ductus arteriosus in full-term infants.

Using echocardiographic techniques, the change in left ventricular (LV) volume and its effect on systolic function were studied before and after the closure of ductus arteriosus in 18 full-term infants. Examinations were performed twice in each infant, within 6 h after birth and on day 5, and the patency of the ductus with left-to-right shunt was confirmed at the first examination by Doppler echocardiography. A biplane Simpson's rule method was used for volume measurements. The LV end-diastolic volume, stroke volume, and cardiac output were more than 1.3-fold before the ductal closure, and the ejection fraction showed the similar change. However, the mean normalized systolic ejection rate, an index of contractility, and heart rate showed no significant difference. The Frank-Starling curve was obtained from the relationship between the LV end-diastolic and stroke volumes, and the LV performance was operated at a higher level on that curve when the ductus was open. Our data indicated that LV cardiac output was significantly higher during the patency of the ductus arteriosus and that this high cardiac performance might depend more on the Frank-Starling response to the volume load through the ductus arteriosus than on the increase of LV contractility and heart rate.

Cardiac Output↗
PubMed1996

Cytotoxic activity against tumour cells mediated by intermediate TCR cells in the liver and spleen.

Morphological and phenotypic characterization in previous studies has indicated that intermediate (int) T-cell receptor (TCR) cells or T natural killer (TNK) cells may stand at an intermediate position between NK cells and high TCR cells of thymic origin in phylogenetic development. In this study, a functional study on cytotoxic activity against various tumour targets was performed in each purified subset. When a negative selection method entailing in vivo injection of anti-asialo GM, antibody or anti-interleukin (IL)-2R beta monoclonal antibody (mAb) was applied, IL-2R beta 1 CD3 NK cells were found to have the highest NK activity while IL-2R beta 1 int CD3 (or TCR) cells had a lower level of the NK activity. High CD3 cells (freshly isolated) did not have any such activity. Sorting experiments further revealed that the NK function mediated by int CD3 cells was augmented when they were exposed to anti-CD3 mAb. anti-TCR alpha beta, or anti-TCR-delta mAb. This phenomenon was not observed in NK cells and high CD3 cells. More importantly, when anti-CD3 mAb (or anti-TCR mAb) was added to the assay culture, int CD3 cells became cytotoxic against even NK-resistant tumour (Fc gamma R-. Fas+) targets. Liver mononuclear cells or int CD3 cells exposed to anti-CD3 mAb for 6 hr showed an elevated level of perforin in their cytoplasms. The present results suggest that int CD3 cells are usually non-cytotoxic against various tumours but become functional after being stimulated via the TCR CD3 complex.

Animals↗
PubMed1996

Doppler echocardiographic findings of indomethacin-induced occlusion of the fetal ductus arteriosus.

We present an unusual case of indomethacin-induced occlusion of the fetal ductus arteriosus, which occurred in one of twins. In fetal echocardiography, the characteristic findings, a to and fro regurgitation pattern at pulmonary valve and postvalvular dilation of the main pulmonary artery, were obtained in addition to right ventricular dilation and hypertrophy, tricuspid regurgitation, right atrium dilation, and pericardial effusion. This fetus developed fetal distress and was delivered by an emergency cesarean section at 35 weeks' gestation. We suggest that these fetal echocardiographic findings may be the end-stage signs of the fetal ductal occlusion as well as the signs for emergent delivery.

Adult↗
PubMed1996

Relationships between clinical and histological profiles of non-familial idiopathic neonatal hepatitis.

Idiopathic neonatal hepatitis (INH) is a syndrome characterized clinically and histologically but there is little information concerning the relationship between the clinical features and histological findings. In the present study, sixty-two patients clinically diagnosed as non-familial INH were histologically classified into four groups according to a provisional definition based on predominant lesions and examination of their clinical features. Patients of cholestasis (n = 23) and giant cell hepatitis (GCH, n = 21) were most frequent (37% and 33%, respectively), and patients of fatty liver (n = 10) and hepatitis (n = 8) were less common (16% and 13%). The GCH group showed a dominance of male, low birthweight, older and breast-fed babies. The cholestasis group demonstrated a dominance of male, low birthweight, younger and bottle-fed babies. The hepatitis group had the highest frequencies of high-grade hepatomegaly and splenomegaly. Fifty six cases completely recovered. Two died of hepatic failure in early infancy and four had chronic liver diseases at the age of 12 months. The fatty liver group had the worst outcome. Histological features in non-familial INH were variable and typical giant cell hepatitis was seen in only one-third of patients. Characteristic clinical features in each histologically classified group may suggest heterogenous etiologies underlying non-familial INH.

Diagnosis, Differential↗
PubMed1996

Relationship of feeding modality to clinical features in Japanese infants with idiopathic neonatal hepatitis of the non-familial form.

To clarify the relationship between idiopathic neonatal hepatitis and feeding type, that is, formula-milk feeding and breast-milk feeding, the medical records of 100 patients (68 male and 32 female babies) with idiopathic neonatal hepatitis of non-familial form referred to the medical centers of Akita University and Tohoku University during the past 18 years were reviewed. The patients were divided into two 9 year periods (1975-83 and 1984-92), and their clinical features were analyzed in terms of feeding type and sex. The number of patients enrolled decreased from 69 in the first half to 31 in the second half. The number of male patients dropped from 53 to 15, although the number of female patients (n = 16) remained the same in both 9 year periods. The frequency of formula-milk feeding significantly decreased in the second half (42/69 to 6/31, P < 0.01). Compared with the expected numbers of patients in the second half, calculated on the changes in the live birth population and feeding modality between the two halves, the actually enrolled numbers of patients in the second half were less in both the male and the formula-milk fed groups (x0.35 and x0.22), whereas the numbers of female and breast-milk feeding groups were close to the expected values (x1.26 and x1.08). When sex and feeding modality were combined, the formula-milk fed male group showed the lowest value (x0.10), and the breast-milk fed female group showed the highest value (x2.85). In conclusion, feeding type, especially in combination with gender, might be one causative factor in the occurrence of idiopathic neonatal hepatitis.

Breast Feeding↗
PubMed1996

An infant case of Ebstein's anomaly of the tricuspid valve with abnormal diastolic filling pattern of the left ventricle.

We report herein an infant case of Ebstein's anomaly with abnormal diastolic filling pattern of the left ventricle. We also compare the case with a comparable case without such abnormal filling pattern. The patient, who had pulmonary valve stenosis, patent ductus arteriosus and mild mitral regurgitation, underwent transventricular valvotomy at 30 days of age. Postoperative course was uneventful. Serial Doppler echocardiographic studies were performed at 2 hr, 40 days, and 52 days of age. Peak velocity and flow velocity-time integral of early diastole, and ratios of the peak velocities and velocity time integrals of the early diastole and atrial contraction were below the 95% confidence limits of the normal controls. Our case suggests that left ventricular diastolic dysfunction may exist in the Ebstein's anomaly when it is associated with mitral valve abnormality such as mitral regurgitation.

Diastole↗
PubMed1995

Role of age on transmitral flow velocity patterns in assessing left ventricular diastolic function in normal infants and children.

This study demonstrated that both peak E and flow velocity integral of early diastole increased to reach the older children's values by 36 months of age and leveled off thereafter, whereas both peak A and flow velocity integral of atrial contraction had little change. These results suggest that age-related changes in E wave reflect the maturational or developmental alterations in LV diastolic properties, especially in the relaxation process.

Adolescent↗
PubMed1995

Changes in transmitral and pulmonary venous flow patterns in the first day of life.

The purpose of this study was to see the relationship between changes in pulmonary venous flow velocities and those in transmitral flow velocities during the first day of life. A serial Doppler echocardiography was performed in 24 normal neonates at 2, 12, and 24 hours of age. The size of the ductus arteriosus was 4.3 +/- 0.5 mm at 2 hours and 2.1 +/- 0.7 mm at 12 hours, and closed in 21 of 24 neonates at 24 hours. The peak systolic pulmonary venous flow (peak S), peak diastolic pulmonary venous flow (peak D), peak D/S, peak velocity at early diastolic filling (peak E), and peak E/A, which were high at 2 hours, decreased significantly at 12 hours but remained constant thereafter. The size of the ductus arteriosus was found to be correlated with peak S, peak D, and peak D/S. There was a direct correlation between peaks E and D (r: 0.64, p < 0.01) as well as a direct correlation between peaks E/A and D/S (r: 0.36, p < 0.05). These results indicate that the diastolic pulmonary venous flow is determined by the same factors that influence the transmitral flow. These waveforms may reflect the increase in pulmonary circulatory volume by left-to-right shunting through the ductus arteriosus.

Blood Flow Velocity↗
PubMed1995

Congenital hypomyelination neuropathy: decreased expression of the P2 protein in peripheral nerve with normal DNA sequence of the coding region.

Congenital hypomyelination neuropathy (Lyon type) is characterized by a non-progressive clinical course and a histopathological formation of atypical onion-bulb. We have studied the immunohistochemical expression of the major peripheral myelin proteins including P0 protein, myelin basic protein (MBP) and P2 protein in three such patients. No significant difference was observed between the patients and the controls, as to the P0 and MBP staining. In contrast, P2 protein antiserum scarcely stained the patients' nerve fibers except for a few scattered adequately myelinated fibers. Assuming the pathogenetic contribution of the extremely decreased P2 protein to the disease, we investigated P2 protein gene by sequencing all coding regions but failed to detect any change in the nucleotide sequence. Further investigation including the analysis of promoter region of P2 protein gene is needed to elucidate the mechanism of congenital hypomyelination neuropathy.

Base Sequence↗