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Biomedical subjects

Y Hayashida

Publications and source records attributed to Y Hayashida.

At least 19 recordsLinked to original sources
PubMed2006

Usefulness of measurement of the temporal stem on magnetic resonance imaging in the diagnosis of frontotemporal dementia.

PURPOSE: To investigate whether measurements of brain structures on routine magnetic resonance (MR) images can be used to distinguish between normal subjects and patients with frontotemporal dementia (FTD) or Alzheimer's disease (AD). MATERIAL AND METHODS: MRI studies were performed on 30 patients with dementia (FTD, n = 15; AD, n = 15) and 15 age-matched controls. Width measurements, obtained at the corpus callosum, the cingulate gyri, the hippocampi, and the temporal stem of the anterior temporal lobes, were compared among FTD and AD patients and control subjects on oblique-coronal T2-weighted images. RESULTS: The width of the temporal stem was significantly narrower in FTD than in AD patients and control subjects (6.3 +/- 1.3 mm, 7.8 +/- 1.1 mm, and 8.2 +/- 0.9 mm, respectively) (P < 0.05), although there was some overlapping between AD and FTD patients. All patients whose temporal stem width was < 6 mm had FTD. While the width of the corpus callosum, cingulate gyri, and hippocampi was significantly narrower in patients with AD and FTD than in the controls, there was no significant difference between the AD and FTD patients. CONCLUSION: The width of the temporal stem was significantly narrower in patients with FTD than in those with AD and controls. The described measurements can easily be obtained and may be useful for the diagnosis of FTD.

Aged↗
PubMed2006

Chronic hypoxia alters calbindin D-28k immunoreactivity in lingual and laryngeal taste buds in the rat.

The distribution and abundance of the calcium binding protein, calbindin D-28k (CB) immunoreactivity in the taste buds of the circumvallate papillae and larynx were compared between normoxic and chronically hypoxic rats (10% O2 for 8 weeks). In the normoxic rats, CB immunoreactivity was observed in some cells and fibers of the intragemmal region of the taste buds in the circumvallate papillae. In contrast, in the subgemmal region of the laryngeal taste buds, fibers but not cells were immunoreactive for CB. In chronically hypoxic rats, CB immunoreactive cells and fibers in the taste buds were decreased in the circumvallate papillae. In the laryngeal taste buds, the density of the subgemmal CB immunoreactive fibers in chronically hypoxic rats was greater than in normoxic rats. It is considered that function of the laryngeal taste buds is different from that of the lingual taste buds, so that laryngeal taste buds may be involved in chemosensation other than taste. The altered density of CB immunoreactive cells and fibers in the lingual and laryngeal taste buds is a predominant feature of hypoxic adaptation, and chronic hypoxic exposure might change the chemical sensitivity of the circumvallate papillae and larynx through the regulation of intracellular Ca2+.

Adaptation, Physiological↗
PubMed2006

Diffusion-weighted imaging of metastatic brain tumors: comparison with histologic type and tumor cellularity.

BACKGROUND AND PURPOSE: On diffusion-weighted imaging (DWI), metastatic tumors of the brain may exhibit different signal intensities (SI) depending on their histology and cellularity. The purpose of our study was to verify the hypotheses (1) that SI on DWI predict the histology of metastases and (2) that apparent diffusion coefficient (ADC) values reflect tumor cellularity. MATERIALS AND METHODS: We assessed conventional MR images, DWI, and ADC maps of 26 metastatic brain lesions from 26 patients, 13 of whom underwent surgery after the MR examination. Two radiologists performed qualitative assessment by consensus of the SI on DWI in areas corresponding to their enhancing portions. We measured the contrast-to-noise ratio (CNR) on T2-weighted images and normalized ADC (nADC) values, and compared them with tumor cellularity. RESULTS: The mean SI on DWI and the CNR on T2-weighted images were significantly lower in well differentiated than in poorly differentiated adenocarcinomas and lesions other than adenocarcinoma. The mean nADC value was significantly higher in well differentiated than poorly differentiated adenocarcinomas and lesions other than adenocarcinoma. All 3 small-cell carcinomas and 1 large-cell neuroendocrine carcinoma exhibited high SI on DWI. The nADC value showed a significant inverse correlation with tumor cellularity. There was no significant correlation between the CNR and tumor cellularity. CONCLUSION: The SI on DWI may predict the histology of metastases; well differentiated adenocarcinomas tended to be hypointense, and small- and large-cell neuroendocrine carcinomas showed hyperintensity. Their ADC values reflect tumor cellularity.

Adenocarcinoma↗
PubMed2006

[Posterior ventricular septal perforation successfully repaired through right ventricular approach].

A 65-year-old man underwent a successful repair of a posterior ventricular septal perforation (VSP) 9 days after suffering an acute inferior myocardial infarction. After hospitalization, his hemodynamic condition gradually worsened, in spite of administering intensive medical therapy. Emergent operation was performed on the 4th day after onset. An equine pericardial patch was sutured around the VSP through the right ventricular side of the septum using the double-patch repair method and the right ventricular wall was closed as using the standard extracorporeal perfusion technique. The dimensions of the VSP measured 5 mm in diameter. Transesophageal echocardiography was performed on the 14th postoperative day. Cardiac catheter examination was done on the 18th postoperative day. No residual shunt was recognized and cardiac function was good. He was discharged on the 20th postoperative day. The occurrence of a posterior VSP is comparatively rare, and repair of VSP is difficult to perform during an acute period. Therefore, the operative results of VSP cases remain poor.

Aged↗
PubMed2005

Hypoxic adaptation of the rat carotid body.

Three types of hypoxia with different levels of carbon dioxide (hypocapnic, isocapnic, and hypercapnic hypoxia) have been called systemic hypoxia. The systemic hypoxic carotid bodies were enlarged several fold, but the degree of enlargement was different for each. The mean short and long axes of hypocapnic and isocapnic hypoxic carotid bodies were 1.6 (short axis) and 1.8-1.9 (long axis) times larger than normoxic control carotid bodies, respectively. Those of hypercapnic hypoxic carotid bodies were 1.2 (short axis) and 1.5 (long axis) times larger than controls, respectively. The rate of enlargement in hypercapnic hypoxic carotid bodies was lower than in hypocapnic and isocapnic hypoxic carotid bodies. The rate of vascular enlargement in hypercapnic hypoxic carotid bodies was also smaller than in hypocapnic and isocapnic hypoxic carotid bodies. Thus, the enlargement of hypoxic carotid bodies is mainly due to vascular dilation. Different levels of arterial CO2 tension change the peptidergic innervation during chronically hypoxic exposure. The characteristic vascular arrangement was under the control of altered peptidergic innervation. During the course of hypoxic adaptation, the enlargement of the carotid bodies with vascular expansion began soon after the start of hypoxic exposure. During the course of recovery, the shrinking of the carotid bodies with vascular contraction also started at a relatively early period after the termination of chronic hypoxia. These processes during the course of hypoxic adaptation and during the course of recovery were under the control of peptidergic innervation. These findings may provide a standard for further studies of hypoxic carotid bodies.

Adaptation, Physiological↗
PubMed2004

Morphological changes in the rat carotid body 1, 2, 4, and 8 weeks after the termination of chronically hypocapnic hypoxia.

Morphological changes in the rat carotid bodies 1, 2, 4, and 8 weeks after the termination of chronically hypocapnic hypoxia (10% O2 for 8 weeks) were examined by means of morphometry and immunohistochemistry. The rat carotid bodies after 8 weeks of hypoxic exposure were enlarged several fold with vascular expansion. The carotid bodies 1 and 2 weeks after the termination of 8 weeks of hypoxic exposure were diminished in size, although their diameter remained larger than the normoxic controls. The expanded vasculature in chronically hypoxic carotid bodies returned to the normoxic control state. In the carotid bodies 1 week after the termination of chronic hypoxia, the density of NPY fibers was remarkably increased and that of VIP fibers was dramatically decreased in comparison with the density in chronically hypoxic carotid bodies. In the carotid bodies 2 and 4 weeks after the termination of hypoxia, the density of SP and CGRP fibers was gradually increased. In the carotid bodies 8 weeks after the termination of hypoxia, the appearance of the carotid body returned to a nearly normoxic state, and the density of SP, CGRP, VIP, and NPY fibers also recovered to that of normoxic controls. These results suggest that the morphological changes in the recovering carotid bodies start at a relatively early period after the termination of chronic hypoxia, and a part of these processes may be under the control of peptidergic innervation.

Animals↗
PubMed2003

Peptidergic innervation in the rat carotid body after 2, 4, and 8 weeks of hypocapnic hypoxic exposure.

The distribution and abundance of neuropeptide-containing nerve fibers were examined in the carotid bodies of rats exposed to hypocapnic hypoxia (10% O2 in N2) for 2, 4, and 8 weeks. The carotid bodies after 2, 4, and 8 weeks of hypoxic exposure were enlarged by 1.2-1.5 times in the short axis, and 1.3-1.7 times in the long axis in comparison with the normoxic control ones. The enlarged carotid bodies contained a number of expanded blood vessels. Mean density per unit area (10(4) microm2) of substance P (SP) and calcitonin gene-related peptide (CGRP) immunoreactive fibers was transiently high in the carotid bodies after 4 weeks of hypoxic exposure, and decreased significantly to nearly or under 50% after 8 weeks of hypoxic exposure. Density of vasoactive intestinal polypeptide (VIP) immunoreactive fibers increased significantly in all periods of hypoxic exposure observed, and was especially high in the carotid bodies after 4 weeks of hypoxic exposure. Density of neuropeptide Y immunoreactive fibers was unchanged in the carotid bodies during hypoxic exposure. These characteristic changes in the density of SP, CGRP, and VIP fibers in the carotid bodies after 4 weeks of hypoxic exposure suggest that the role of these neuropeptide-containing fibers may be different in the carotid bodies after each of three periods of hypoxic exposure, and that the peptidergic innervation after 8 weeks of hypoxic exposure may show an acclimatizing state.

Animals↗
PubMed2002

Electrical properties of chemoreceptor elements in the carotid body.

The electrical properties of chemoreceptor afferent nerve fibers and glomus cells and the behavior of cytosolic Ca(2+) in glomus cells are reviewed. While this has not been confirmed, spontaneously depolarizing potentials (SDPs) recorded in a chemoreceptor afferent terminal may be the postsynaptic expression of presynaptic events. Glomus cells, which are presynaptic elements, either depolarized or hyperpolarized in response to natural and chemical stimulation. After-hyperpolarization following an initial depolarization and after-depolarization following an initial hyperpolarization were often seen. When a glomus cell depolarizes, voltage noise increases despite a decrease in input resistance in both intact and denervated carotid bodies. The voltage noise may be "receptor noise" generated in the glomus cell itself. The electrical properties of glomus cells change in the denervated carotid body, which suggests that the chemoreceptor afferent nerve exerts some trophic effect(s) on glomus cells. Hypoxia either increases or decreases cytosolic Ca(2+), while ACh or NaCN induces either an increase or no change in cytosolic Ca(2+) in glomus cells. There are at least two possible explanations for voltage changes in glomus cells: a chemical stimulus first depolarizes the glomus cell and induces Ca(2+) influx to release chemical substances, or a chemical stimulus induces an increase in [Ca(2+)](i) and then hyperpolarizes the glomus cell via potassium influx.

Carotid Body↗
PubMed2002

Changes in the peptidergic innervation in the carotid body of rats chronically exposed to hypercapnic hypoxia: an effect of arterial CO2 tension.

The abundance of neuropeptide Y (NPY)-, vasoactive intestinal polypeptide (VIP)-, substance P (SP)-, and calcitonin gene-related peptide (CGRP)-immunoreactive nerve fibers in the carotid body was examined in chronically hypercapnic hypoxic rats (10% O2 and 6-7% CO2 for 3 months), and the distribution and abundance of these four peptidergic fibers were compared with those of previously reported hypocapnic- and isocapnic hypoxic carotid bodies to evaluate the effect of arterial CO2 tension. The vasculature in the carotid body of chronically hypercapnic hypoxic rats was found to be enlarged in comparison with that of normoxic control rats, but the rate of vascular enlargement was smaller than that in the previously reported hypocapnic- and isocapnic hypoxic carotid bodies. In the chronically hypercapnic hypoxic carotid body, the density per unit area of parenchymal NPY fibers was significantly increased, and that of VIP fibers was unchanged, although the density of NPY and VIP fibers in the previously reportetd chronically hypocapnic and isocapnic hypoxic carotid bodies was opposite to that in hypercapnic hypoxia as observed in this study. The density of SP and CGRP fibers was decreased. These results along with previous reports suggest that different levels of arterial CO2 tension change the peptidergic innervation in the carotid body during chronically hypoxic exposure, and altered peptidergic innervation of the chronically hypercapnic hypoxic carotid body is one feature of hypoxic adaptation.

Animals↗
PubMed2001

Testis-specific and developmentally induced expression of a ghrelin gene-derived transcript that encodes a novel polypeptide in the mouse.

Ghrelin is a novel growth hormone-releasing peptide isolated from rat stomach. In the present study, we report expression of a ghrelin gene-derived transcript (GGDT) in the mouse testis. Analysis of GGDT cDNA revealed that the 68 bp sequence at the 5'-end was unique and the remaining 252 bp sequence was identical with the sequence encoded by exons 4 and 5 of mouse ghrelin gene. The 5'-unique sequence encoded 12 amino acid residues being in-frame with the C-terminal 42 amino acid sequence of mouse ghrelin. The 54-amino-acid polypeptide encoded by GGDT contained no apparent signal peptide sequence but possessed a nuclear localization signal-like sequence. Ghrelin mRNA was extensively expressed in the stomach, while GGDT was expressed only in the testis. The 5'-unique sequence of GGDT was identified between exons 3 and 4 of the ghrelin gene, indicating that GGDT was generated by alternative usage of the 68 bp exon as the testis-specific first exon. The GGDT expression in the testis was initiated and increased after 2 weeks of postnatal period. These results indicate that the expression of GGDT is regulated in testis-specific and developmental stage-specific manners.

Age Factors↗
PubMed2001

Effects of ketamine and propofol on autonomic cardiovascular function in chronically instrumented rats.

In this study C. we systematically examined the effects of ketamine and propofol at various doses (5-20 mg/kg) on blood pressure, heart rate and renal sympathetic nerve activity in chronically instrumented Wistar rats. We also assessed the effects of these anesthetics on the baroreflex control of heart rate and renal sympathetic nerve activity. Ketamine (10 mg/kg) increased blood pressure by 30.0+/-4.5%, heart rate by 17.7-3.3% and renal sympathetic nerve activity by 38.8+/-14.6%, while propofol (10 mg/kg) decreased blood pressure by 18.9+/-3.5%, heart rate by 5.5+/-2.5% and renal sympathetic nerve activity by 7.5+/-2.1%. These variables showed dose-dependent responses to both agents. Both ketamine and propofol decreased the range and maximum gain of the logistic function curve obtained by relating mean blood pressure to heart rate and blood pressure to renal sympathetic nerve activity. In conclusion, ketamine and propofol had different effects on autonomic cardiovascular function, but attenuated the baroreflex sensitivity of heart rate and renal sympathetic nerve activity in a dose-dependent manner. These results suggest the possibility that baroreflex sensitivity may reflect the depth of anethesia.

Anesthetics, Dissociative↗
PubMed2001

Post-pubertal mucinous cystadenoma of the pancreas.

A 14-year-old patient with a mucinous cystadenoma of the pancreas (MCAP) is presented. She presented with a palpable left-sided abdominal mass and underwent a left hemipancreatectomy. MCAP occurs mostly in middle-aged women, and no post-pubertal cases have been reported to date in the English literature.

Adolescent↗
PubMed2001

Biotransformation of thujopsene by Caragana chamlagu.

Biotransformation of thujopsene (1) using a cell suspension culture of Caragana chamlagu for 14 days gave mayurone (2, 52%) and two new compounds, 3beta-hydroxy-4-thujopsene (4, 16%) and 3beta-epoxythujopsa-5beta-ol (3, 22%).

Biotransformation↗
PubMed2001

Natural history of sigmoid colon cancer: report of a patient observed for 4 years.

We report a case of sigmoid colon cancer that was left untreated for a period of 4 years, because the patient declined treatment. A 59-year-old man was found to have an early carcinoma of the sigmoid colon measuring approximately 12 mm in diameter. The lesion, initially a flat cancer, increased in height and became sessile 4 months later. Subsequently, the central portion of the lesion became ulcerated, leaving an elevated ring along its periphery. The lesion eventually evolved into an ulcerated, invasive cancer. This sequence has not been observed with colonoscopy before.

Adenocarcinoma↗
PubMed2001

Organization of the mouse ghrelin gene and promoter: occurrence of a short noncoding first exon.

Ghrelin is a growth hormone-releasing peptide recently discovered in the stomach of rat and human as an endogenous ligand for growth hormone-secretagogue receptor. In the present study, a full-length cDNA for mouse ghrelin has been cloned from the stomach using the oligo-capping and rapid amplification methods, and the organization of its gene and promoter has been analyzed. The mouse ghrelin cDNA was 521 bp long, consisting of 44 bp 5'-noncoding region, 354 bp coding region encoding a pre-proghrelin composed of 117 amino acid residues and 123 bp 3'-noncoding region. The genomic sequence analysis has revealed that the mouse ghrelin gene consists of 5 exons and 4 introns. The first exon was revealed to be only 19 bp long presented at the noncoding region of cDNA. The identical 19 bp sequence was also found as the first exon at the 5'-end of full-length rat ghrelin cDNA obtained from the stomach. A TATA box-like sequence, TATATAA was localized 24 bp upstream of the transcription start site of the mouse ghrelin gene. The sequence of the 5'-promoter region of mouse ghrelin gene including the TATA-like sequence and short exon 1 was highly homologous to that of reported human ghrelin gene. These findings suggest that the structure of the promoter region including the short noncoding first exon and its transcriptional regulation are conserved among the mammalian ghrelin genes.

Animals↗
PubMed2001

4-Hydroxy-2,5-dimethyl-3(2H)-furanone (HDMF) production in simple media by lactic acid bacterium, Lactococcus lactis subsp. cremoris IFO 3427.

4-Hydroxy-2,5-dimethyl-3(2H)-furanone (HDMF) was detected in simple media prepared with heated sugar and amino acid solution as a result of the Maillard reaction. However, an increase in the amount of HDMF was observed in the media fermented by Lactococcus lactis subsp. cremoris IFO 3427. 4-Hydroxy-2(or 5)-ethyl-5(or 2)-methyl-3(2H)-furanone (HEMF) was not detected in all the simple media examined in this study.

Journal Article↗