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Biomedical subjects

Y Chiba

Publications and source records attributed to Y Chiba.

At least 19 recordsLinked to original sources
PubMed2006

Changes in HRCT findings in patients with respiratory bronchiolitis-associated interstitial lung disease after smoking cessation.

High-resolution computed tomography (HRCT) findings in patients with respiratory bronchiolitis-associated interstitial lung disease (RB-ILD) are varied and nonspecific. There is no known report of changes in HRCT findings and respiratory function test results for RB-ILD patients following the cessation of smoking. Five patients with RB-ILD, confirmed by surgical lung biopsy, were retrospectively studied. Each stopped cigarette smoking and did not receive corticosteroid therapy after diagnosis. The clinical symptoms, respiratory function test results and HRCT findings obtained at the final observation were compared with those from the time of diagnosis. Ground-glass opacity and centrilobular nodules corresponding to pathological respiratory bronchiolitis, as well as intralobular fine linear-reticular opacity corresponding to fibrosis involving the subpleural alveolar septa, showed computed tomography-pathological correlations. Both clinical symptoms and the diffusing capacity of the lungs for carbon monoxide improved significantly following smoking cessation, as did ground-glass opacity and centrilobular nodules seen during the initial HRCT examination. Centrilobular nodules and ground-glass opacity, which are the main features of high-resolution computed tomography of respiratory bronchiolitis-associated interstitial lung disease patients and represent pathological respiratory bronchiolitis, can be improved by smoking cessation. The diffusing capacity of the lung for carbon monoxide in respiratory function tests can be also improved.

Adult↗
PubMed2006

Sensory system-predominant distribution of leukotriene A4 hydrolase and its colocalization with calretinin in the mouse nervous system.

Leukotriene B4 is a potent lipid mediator, which has been identified as a potent proinflammatory and immunomodulatory compound. Although there has been robust evidence indicating that leukotriene B4 is synthesized in the normal brain, detailed distribution and its functions in the nervous system have been unclear. To obtain insight into the possible neural function of leukotriene B4, we examined the immunohistochemical distribution of leukotriene A4 hydrolase, an enzyme catalyzing the final and committed step in leukotriene B4 biosynthesis, in the mouse nervous system. Immunoreactivity for leukotriene A4 hydrolase showed widespread distribution with preference to the sensory-associated structures; i.e. neurons in the olfactory epithelium and vomeronasal organ, olfactory glomeruli, possibly amacrine cells, neurons in the ganglion cell layer and three bands in the inner plexiform layer of the retina, axons in the optic nerve and tract up to the superior colliculus, inner and outer hair cells and the spiral ganglion cells in the cochlea, vestibulocochlear nerve bundle, spinal trigeminal tract, and lamina II of the spinal cord. Double immunofluorescence staining demonstrated that most of the leukotriene A4-hydrolase-immunopositive neurons coexpressed calretinin, a calcium-binding protein in neurons. The ubiquitous distribution of leukotriene A4 hydrolase was in sharp contrast with the distribution of leukotriene C4 synthase [Shimada A, Satoh M, Chiba Y, Saitoh Y, Kawamura N, Keino H, Hosokawa M, Shimizu T (2005) Highly selective localization of leukotriene C4 synthase in hypothalamic and extrahypothalamic vasopressin systems of mouse brain. Neuroscience 131:683-689] which was confined to the hypothalamic and extrahypothalamic vasopressinergic neurons. These results suggest that leukotriene B4 may exert some neuromodulatory function mainly in the sensory nervous system, in concert with calretinin.

Animals↗
PubMed2006

Is intrapartum temporary pacing required for women with complete atrioventricular block? An analysis of seven cases.

Women with complete atrioventricular heart block without a permanent pacemaker normally receive temporary pacing for labour and birth. Here, we report seven women who were managed without pacing. All women had a temporary pacing lead inserted prior to induction of labour, but none of the women required pacing during labour or birth. Our experience suggests that women with complete atrioventricular block and without permanent pacing do not routinely require temporary pacing for labour and birth.

Adult↗
PubMed2006

Apical vulnerability to dendritic retraction in prefrontal neurones of ageing SAMP10 mouse: a model of cerebral degeneration.

The SAMP10 mouse is a model of accelerated ageing in which senescence is characterized by age-related atrophy of the cerebral cortex and limbic structures, poor learning and memory task performance with depressive behaviour and cholinergic and dopaminergic alterations. Here we studied age-related changes in the dendritic arbors and spine density of pyramidal cells in the medial prefrontal cortex of SAMP10 mice using a quantitative Golgi method. Dendrites of prefrontal neurones gradually retracted with ageing towards the soma with the relative preservation of overall complexity. Apical dendrites were much more severely affected than basal dendrites. The combined length of the apical dendrites and spine density were decreased by 45% and 55%, respectively, in mice at 12 months, compared with mice at 3 months of age. Immunohistochemical and immunoblot analyses indicated that expression of microtubule-associated protein (MAP) 2, a marker of dendrites, decreased in an age-related manner not only in the anterior cortex but also in the posterior cortex and olfactory structures in SAMP10 mice. Decreased expression of MAP2 mRNA caused the decrease in MAP2 protein expression. These results suggest that retraction of apical, but not of basal dendrites, with a loss of spines in prefrontal neurones, appears to be responsible for poor learning and memory performance in aged SAMP10 mice. It is also suggested that age-related dendritic retraction occurs in a wide area including the entire cerebral cortex and olfactory structures.

Aging↗
PubMed2005

Highly selective localization of leukotriene C4 synthase in hypothalamic and extrahypothalamic vasopressin systems of mouse brain.

While leukotriene C4 (LTC4) was originally identified as a potent bronchoconstrictor, the compound has versatile biological activities besides inflammatory reactions. Although the high content of LTC4 has been reported in the hypothalamus and median eminence, the precise localization of the compound remained obscure. To elucidate its possible functions in the neuroendocrine systems, we determined immunohistochemical localization of LTC4 synthase, a key enzyme to produce LTC4 using mouse brains. Light microscopy and confocal laser scanning microscopy showed that LTC4 synthase was selectively localized in the vasopressinergic magnocellular neurons of the hypothalamic paraventricular, supraoptic and suprachiasmatic nuclei and in the retrochiasmatic area, as well as in axons that emanated from these neurons to the pars nervosa of the pituitary gland. At subcellular level, however, LTC4 synthase and arginine vasopressin appeared to localize differently within individual neurons. LTC4 synthase immunoreactivity was also observed in the axons of the extrahypothalamic system including the bed nucleus of the stria terminalis, lateral habenular nucleus, midbrain central gray, medial amygdaloid nucleus and ventral septal area, although this immunoreactivity was relatively minor. The other brain regions did not contain LTC4 synthase immunoreactivity. The distribution of LTC4 synthase did not overlap with that of either oxytocin or luteinizing hormone releasing hormone. Therefore, LTC4 is considered to be involved in neural functions of the brain magnocellular vasopressinergic system such as water retention. LTC4 may also be involved in extrahypothalamic vasopressinergic neural functions including the regulation of learning and memory, social recognition memory, sexual and aggressive behavior, etc.

Animals↗
PubMed2005

Incidence of insulin resistance in obese subjects in a rural Japanese population: the Tanno and Sobetsu study.

OBJECTIVES: Although it is well known that obesity is closely related to insulin resistance, the incidence of the development of insulin resistance in people with obesity is not known. In this study, we investigated the incidence of insulin resistance in citizens of two rural communities in Japan. SUBJECTS AND METHODS: The subjects were 102 men and 126 women over the age of 30 years selected from 1035 citizens who had undergone medical examinations in the towns of Tanno and Sobetsu, Hokkaido, in 1991 and 1998. Those who were on medication for hypertension, diabetes, hyperlipidaemia, coronary heart disease and cerebral vessel disease were excluded. The simple index to determine insulin resistance [i.e. homeostasis model assessment (HOMA-R) > or = 1.73] was used, and subjects who were determined to be positive for insulin resistance according to this index in 1991 were also excluded in order to determine the incidence of insulin resistance in subjects who had no abnormalities other than obesity. The systolic blood pressure (SBP), diastolic blood pressure, body mass index (BMI), triglyceride level, high-density lipoprotein level, blood sugar level, serum insulin value and HOMA-R were measured in all subjects in 1991 and in 1998. Moreover, the subjects were divided into two groups according to BMI, a normal group consisting of subjects with BMI < 25 and an obesity group consisting of subjects with BMI > or = 25. We also compared the incidences of insulin resistance in normal and obesity groups of subjects who were newly determined to be positive for insulin resistance on the basis of data obtained from medical examinations conducted in 1998. RESULTS: The incidence of insulin resistance was significantly higher in the obesity group than in the normal group (25.0 vs. 4.5%). The results of logistic regression analysis showed that obesity was closely related to insulin resistance and that the relative risk of development of insulin resistance adjusted for age, sex, SBP, FPG and HDL was 3.193 (95% CI 1.085-9.401). CONCLUSIONS: The incidence of insulin resistance was significantly higher in the obesity group than in the normal group in this study, suggesting that improvement in obesity is important for prevention of the occurrence of type 2 diabetes or atherosclerotic disease based on insulin resistance.

Adult↗
PubMed2004

Hyperresponsiveness of bronchial but not tracheal smooth muscle in a murine model of allergic bronchial asthma.

OBJECTIVE: To determine a change in airway smooth muscle contractility in a murine model of allergic asthma, the responsiveness of airway smooth muscles isolated from ovalbumin (OA)-sensitized and -challenged mice was compared with that from control animals. METHODS: Actively sensitized mice were repeatedly challenged by ovalbumin (OA) antigen inhalation. Twenty-four h after the last antigen challenge, tracheal and bronchial smooth muscle responsiveness to acetylcholine (ACh) and endothelin-1 (ET-1) were measured. Airway microvascular leakage and histochemistry were also determined as indices of airway inflammation. RESULTS: Both the ACh and ET-1 responsiveness of bronchial, but not tracheal, smooth muscles were significantly augmented in OA-challenged mice, whereas no significant change in the expression levels of M2, M3 and ETB receptors was observed. The Evans blue dye extravasation in the main bronchial, but not tracheal, tissue of OA-challenged mice was significantly increased as compared with that of sensitized control animals. A marked inflammatory cells infiltration was also observed in bronchial but not tracheal tissues of OA-challenged mice. CONCLUSION: Repeated antigen challenge to sensitized mice caused a hyperresponsiveness of bronchial, but not tracheal, smooth muscle accompanied with bronchial tissue inflammation.

Acetylcholine↗
PubMed2004

Development of cholinergic chronotropic control in chick (Gallus gallus domesticus) embryos.

In chick (Gallus gallus domesticus) embryos, instantaneous heart rate begins to fluctuate with the appearance of rapid, transient decelerations at around the end of the second week of incubation. Previously, it was shown that instantaneous heart rate decelerations were eliminated by administration of atropine and concurrently heart rate baseline was elevated in late embryos. Because the previous study lacked statistical treatment and there has been recent controversy over the development of tonic vagal control of the heart, we reexamine the hypothesis that transient decelerations of instantaneous heart rate are mediated by vagus nerve and the vagal tone begins to appear at around the end of the second week of incubation. Atropine administration tests were conducted for sixty-seven 11- to 14-day-old and 18-day-old embryos in total. Heart rate decelerations appeared sporadically in three out of ten 12-day-old embryos, but the difference of mode heart rate before and after administration of atropine was not significant. Seven out of nine 13-day-old embryos and all nine 14-day-old embryos showed heart rate decelerations and the difference of mode heart rate before and after atropine administration was significant. In late (18-day-old) embryos, magnitude and frequency of instantaneous heart rate decelerations further increased with additional appearance of transient, irregular accelerations. Administration of varying doses of atropine completely eliminated the heart rate decelerations and elevated the heart rate baseline more markedly than in young embryos, indicating the maturation of vagal tone late in incubation.

Animals↗
PubMed2004

Association of the hCLCA1 gene with childhood and adult asthma.

Asthma is caused by bronchial inflammation. This inflammation involves mucus overproduction and hypersecretion. Recently, a mouse model of asthma showed that gob-5 is involved in the pathogenesis of asthma. The gob-5 gene is involved in mucus secretion and its expression is upregulated upon antigen attack in sensitized mice. The observation suggests that human homologue of gob-5, hCLCA1 (human calcium-dependent chloride channel-1), may be involved in human disease. We screened for single-nucleotide polymorphisms (SNPs) in hCLCA1 in the Japanese population. We identified eight SNPs, and performed association studies using 384 child patients with asthma, 480 adult patients with asthma, and 672 controls. In haplotype analysis, we found a different haplotype distribution pattern between controls and childhood asthma (P<0.0001) and between controls and adult asthma (P=0.0031). We identified a high-risk haplotype (CATCAAGT haplotype; P=0.0014) and a low-risk haplotype (TGCCAAGT haplotype; P=0.00010) in cases of childhood asthma. In diplotype analysis, patients who had the CATCAAGT haplotype showed a higher risk for childhood asthma than those who did not (P=0.0011). Individuals who had the TGCCAAGT haplotype showed a lower risk for childhood asthma than those who did not (P<0.0001). Our data suggested that variation of the hCLCA1 gene affects patients' susceptibility for asthma.

Adolescent↗
PubMed2004

Autoregulation of the gene for cystathionine gamma-synthase in Arabidopsis: post-transcriptional regulation induced by S-adenosylmethionine.

Cystathionine gamma-synthase (CGS) catalyses the first committed step of methionine biosynthesis in higher plants. CGS is encoded by the CGS1 gene in Arabidopsis. Stability of CGS1 mRNA is down-regulated in response to methionine application and the exon 1-coding region of CGS1 itself is necessary and sufficient for this regulation. mto1 (for methionine overaccumulation) mutants of Arabidopsis, which carry single-amino-acid sequence alterations within CGS1 exon 1, are deficient in this regulation and overaccumulate methionine. Since CGS1 exon 1 acts in cis during this regulation, we have proposed a model that the regulation occurs during translation of CGS1 mRNA when the nascent polypeptide of CGS and its mRNA are in close proximity. In fact, application of the translation inhibitor cycloheximide abolished this regulation in vivo. This model predicts that the regulation can be reproduced in an in vitro translation system. Studies using the in vitro translation system of wheatgerm extract have indicated that S-adenosylmethionine, a direct metabolite of methionine, is the effector of this regulation. A 5'-truncated RNA species, which is a probable degradation intermediate of CGS1 mRNA in vivo, was also detected in vitro, suggesting that the wheatgerm in vitro translation system reflects the in vivo regulation.

Amino Acid Sequence↗
PubMed2003

Classifying cases of fetal Wolff-Parkinson-White syndrome by estimating the accessory pathway from fetal magnetocardiograms.

The paper presents an evaluation of the possibility of using fetal magnetocardiogram (FMCG) signals to estimate and classify the accessory pathway in fetal Wolff-Parkinson-White (WPW) syndrome. The FMCG signals of two fetuses with WPW syndrome (type A) were detected using a 64-channel superconducting quantum-interference device system. An average across the cycles of these signals was taken to obtain clear WPW signals. To determine the direction and position of the accessory pathway in a fetal heart accurately, the accessory pathway and activated pathway at the peak of the QRS complex thus obtained were estimated for each fetus, using a single-dipole model. The phase angle (about 90 degrees) between the equivalent current dipoles (ECDs) was the same for both fetuses. This angle suggested that the accessory pathway is in the left side of the heart, i.e. that the pathway exists in the left ventricle, which indicates type A WPW syndrome. Identification of the position of the accessory pathway in a fetus with WPW syndrome from the angle between the ECD of the accessory pathway and the ECD of the peak in the QRS complex was thus demonstrated.

Electrocardiography↗
PubMed2003

Heart rate responses to cooling in emu hatchlings.

Among fluctuations of instantaneous heart rate (IHR) in newly hatched chicks, heart rate (HR) oscillation with a mean frequency of 0.7 Hz has been designated as Type II HR variability characterized by low frequency (LF) oscillation [Comp. Biochem. Physiol. Part A 124 (1999) 461]. In response to exposure to lowered ambient temperature (Ta), chick hatchlings raised their HR baseline accompanied with the production or augmentation of Type II HR oscillation, indicating that LF oscillation is a phenomenon relating to thermoregulation [J. Therm. Biol. 26 (2001) 281]. In emu hatchlings that are precocial like chickens, Type II HR oscillation also occurred, but less frequently in comparison with chick hatchlings [Comp. Biochem. Physiol. Part A 131 (2002) 787]. This present experiment was conducted to elucidate how IHR of emu hatchlings responds to changes in Ta. Six hatchlings were measured for IHR and skin temperature (Ts) during a 3-h period when they were exposed to controlled Ta (ca. 35 degrees C), lowered Ta (ca. 15-30 degrees C) and again the controlled Ta for individual 1-h periods. In response to all the cooling and re-warming procedures, HR baseline changed depending upon the intensity of the Ta differences; i.e. large differences of Ta produced large changes in HR. HR fluctuations tended to augment during cooling with a few exceptions, but LF oscillation was not produced. Thus, LF oscillation, which was scarce even at the controlled Ta, could not be used as a thermoregulatory indicator in emus.

Animals↗
PubMed2003

Simultaneous measurements of instantaneous heart rate and breathing activity in newly hatched chicks.

1. Among three types of fluctuations of instantaneous heart rate (IHR) found previously in newly hatched chicks, a high frequency oscillation with a mean frequency of about 0.7 Hz (Type I) appeared to be concurrent with breathing (Moriya et al., Comparative Biochemistry and Physiology, 124A: 461-468, 1999). 2. In order to confirm that Type I HR fluctuation is respiratory sinus arrhythmia (RSA), breathing activity was measured by a condenser microphone, simultaneously with IHR. 3. The microphone detected pressure changes caused by breathing (acoustorespirogram, ARG) and also unexpectedly movement, probably twitch, of hatchlings. 4. Simultaneous measurements of IHR and ARG demonstrated that oscillatory frequency of Type I HR fluctuation coincided with breathing frequency and IHR increased with inspiration, confirming that Type I HR oscillation is RSA. 5. In addition, large transient HR accelerations (Type III HR fluctuation) simultaneously occurred with movement or twitch of the hatchlings, suggesting that Type III HR fluctuation and movement of hatchlings have the same origin, probably sympathetic nerve function.

Aging↗
PubMed2002

Visualisation method of spatial interictal discharges in temporal epilepsy patients using magneto-encephalogram.

The aim of the study was to develop a method for investigating how interictal epileptic discharges in temporal epilepsy patients are activated spatially. The activity was measured using magneto-encephalography (MEG). The MEG data were used to produce a current-arrow map that reflected the topographic distribution of the electrical current for each peak epileptic waveform. A large current distribution was obtained that appeared to be contained in the limbic structure, in each temporal lobe. The large current orientation indicated two opposite directions. Furthermore, the decrease in the maximum strength of the current-arrow, depending on the medication (e.g. the decrease from 11 to 6 pT m-1 in the left temporal lobe (contralateral stimuli)), suggested that the discharge distributions could be used to verify the efficacy of medication. Thus the topographical visualisation method could be a new strategy for diagnosis in temporal epilepsy patients.

Aged↗
PubMed2002

Detection of atrial-flutter and atrial-fibrillation waveforms by fetal magnetocardiogram.

Two cases of fetal tachycardia are reported: atrial flutter and fibrillation. The waveforms from each case were detected by fetal magnetocardiograms (FMCGs) using a 64-channel superconducting quantum interference device (SQUID) system. Because the magnitude of supraventricular arrhythmia signals is very weak, two subtraction methods were used to detect the fetal MCG waveforms: subtraction of the maternal MCG signal, and subtraction of the fetal ORS complex signal. It was found that atrial-flutter waveforms showed a cyclic pattern and that atrial-fibrillation waveforms showed f-waves with a random atrial rhythm. Fast Fourier transform analysis determined the main frequency of the atrial flutter to be about 7Hz, and the frequency distribution of atrial fibrillation consisted of small, broad peaks. To visualise the current pattern, current-arrow maps, which simplify the observation of pseudo-current patterns in fetal hearts, of the averaged atrial flutter and fibrillation waveforms were produced. The map of the atrial flutter had a circular pattern, indicating a re-entry circuit, and the map of the atrial fibrillation indicated one wavelet, which was produced by a micro-re-entry circuit. It is thus concluded that an FMCG can detect supraventricular arrhythmia, which can be characterised by re-entry circuits, in fetuses.

Atrial Fibrillation↗
PubMed2002

Development of respiratory rhythms in perinatal chick embryos.

In chick embryos, gas exchange takes place via the chorioallantoic membrane (CAM) and the lungs at approximately 1 day prior to hatching. The present study was designed to elucidate the development of respiratory rhythms in the chick embryo during the whole pipping (perinatal) period with a condenser-microphone measuring system. The microphone was hermetically attached on the eggshell over the air cell on day 18 of incubation. It first detected a cardiogenic signal (i.e. acoustocardiogram), and then beak clapping and breathing signals (acoustorespirogram, ARG). The first signals of lung ventilation appeared intermittently and irregularly approximately once per 5 s among the clapping signals after the embryo penetrated its beak into the air cell (internal pipping, IP). The respiratory rhythm then developed irregularly, with a subsequent more regular rate. The envelope pattern of breathing from the onset of IP through external pipping (EP) to hatching was constructed by a specially devised procedure, which eliminated external and internal noises. The envelope patterns indicated that the IP, EP and whole perinatal periods of 10 embryos were 14.1+/-6.4 (S.D.), 13.6+/-4.0 and 27.6+/-5.4 h, respectively. In addition, they also indicated the period of embryonic hatching activity (i.e. climax) which was 48+/-19 min. The development of respiratory rhythm was also shown by the instantaneous respiratory rate (IRR) which was designated as an inverse value of two adjacent ARG waves.

Animals↗
PubMed2002

Initial experiences of tissue harmonic imaging in the diagnosis of fetal cardiac tumors.

The usefulness of tissue harmonic imaging in prenatal diagnosis is illustrated in two fetuses with a cardiac tumor. Tissue harmonic imaging provided more informative images than conventional B-mode imaging, enabling the detection of the site of attachment of the cardiac tumor and estimation of intracardiac blood flow. The advantages of tissue harmonic imaging over conventional B-mode imaging in prenatal diagnosis are discussed.

Blood Flow Velocity↗