Biomedical subjects

T Hirabayashi

Publications and source records attributed to T Hirabayashi.

At least 37 records · Page 2Linked to original sources

PubMed2000

[Ruptured aneurysm of sinus of Valsalva into the right atrium with aortic valve perforation].

A 58-year-old female was admitted to our hospital because of sudden dyspnea and general malaise. A continuous murmur was heard along the left sternal border. A chest X-ray showed cardiomegaly and pulmonary vascular marking. Doppler echocardiography confirmed the presence of an aneurysmatic mass, originating from the non-coronary sinus of Valsalva and extending to the right atrium, with a turbulent flow into the right atrium, aortic regurgitation (II/IV) and tricuspid regurgitation (III/IV). Ascending aortography demonstrated a communication between the aortic sinus and the right atrium. The pulmonary-to-systemic flow ratio was calculated to be 2.04. Oblique aortotomy and right atriotomy were performed. The aneurysm was resected and its origin was directly closed with horizontal mattress sutures through the aortic side and right atrial side. Perforation of a non-coronary cusp that caused aortic regurgitation was found following aortotomy and it was closed with an autologous pericardial patch. Tricuspid annuloplasty was performed using DeVega's technique. The postoperative course was uneventful, and she was discharged on the 10th postoperative day.

Aortic Rupture↗

PubMed1999

Critical duration of intracellular Ca2+ response required for continuous translocation and activation of cytosolic phospholipase A2.

When cells are exposed to certain external stimuli, arachidonic acid (AA) is released from the membrane and serves as a precursor of various types of eicosanoids. A Ca2+-regulated cytosolic phospholipase A2 (cPLA2) plays a dominant role in the release of AA. To closely examine the relation between Ca2+ response and AA release by stimulation of G protein-coupled receptors, we established several lines of Chinese hamster ovary cells expressing platelet-activating factor receptor or leukotriene B4 receptor. Measurement of intracellular Ca2+ concentration ([Ca2+]i) demonstrated that cell lines capable of releasing AA elicited a sustained [Ca2+]i increase when stimulated by agonists. The prolonged [Ca2+]i elevation is the result of Ca2+ entry, because this elevation was blocked by EGTA treatment or in the presence of Ca2+ channel blockers (SKF 96365 and methoxyverapamil). cPLA2 fused with a green fluorescent protein (cPLA2-GFP) translocated from the cytosol to the perinuclear region in response to increases in [Ca2+]i. When EGTA was added shortly after [Ca2+]i increase, the cPLA2-GFP returned to the cytosol, without liberating AA. After a prolonged [Ca2+]i increase, even by EGTA treatment, the enzyme was not readily redistributed to the cytosol. Thus, we propose that a critical time length of [Ca2+]i elevation is required for continuous membrane localization and full activation of cPLA2.

Animals↗

PubMed1999

Tissue-specific distribution of breast-muscle-type and leg-muscle-type troponin T isoforms in birds.

In order to show the tissue-specific distribution of troponin T (TnT) isoforms in avian skeletal muscles, their expression was examined by electrophoresis of the breast and leg muscles of seven avian species and immunoblotting with the antiserum against fast skeletal muscle TnT. It has been reported in the chicken that breast-muscle-type (B-type) and leg-muscle-type (L-type) TnT isoforms are expressed specifically in the adult breast and leg muscles, respectively. Their differential expression patterns were confirmed in all birds examined in this study. The expression of a segment encoded by the exon x series of TnT was also examined by immunoblotting with the antiserum against a synthetic peptide derived from the exon x3 sequence, because the segment has been shown to be included exclusively in the B-type, but not in the L-type TnT. The expression of the segment was found only in the breast muscle, but not in the leg muscle of all birds examined. TnT cDNA sequences from the duck breast and leg muscles were determined and showed that only B-type TnT had an exon x-related sequence, suggesting that the expression of B-type TnT containing the exon x-derived segment is conserved consistently in the birds.

Amino Acid Sequence↗

PubMed1999

Effects of invaginating anastomosis in Kasai hepatic portoenterostomy on resolution of jaundice, and long-term outcome for patients with biliary atresia.

BACKGROUND/PURPOSE: This report describes a technique of hepatic portoenterostomy (HPE) to keep sustained bile drainage in biliary atresia patients. In conventional HPE, the medial posterior row of the anastomosis is placed behind the main portal vein. But around both lateral corners where the portal branches enter the liver parenchyma, the anastomosis is placed across and outside of the portal veins. Resultantly, the proximal part of the portal veins become included in anastomosis attaching directly to the dissected area where bile ducts are copious. In a devised procedure designated as invaginating anastomosis (IA), an anastomotic line was placed to invaginate the medial branch of the right portal vein and also placed behind the veins even at their roots. This technique puts all portal branches outside of the anastomosis, preventing cicatricial adhesion at the dissected area with the posterior wall of the veins. METHODS: The effect of IA was evaluated in terms of resolution of jaundice and long-term outcome compared with conventional anastomosis (CA). Group IA consisted of 20 patients and group CA of 18 patients. RESULTS: Patients in whom jaundice resolved included 19 (95%) in group IA and 11 (61%) in group CA (P < .05). Reoperation was needed in only one infant in group IA, and in six in CA (P < .05). In patients with reoperation in group CA, the portahepatis was found to be contracted with dense cicatricial tissues. The survival rates for patients with a native liver, calculated excluding those in whom the cause of death was not liver deterioration, was 87% for IA compared with 41% for CA (P < .05). Averaged biliary atresia prognostic index at the last follow-up evaluation was 20.2+/-24.5 for group IA and 62.6+/-29.8 for group CA (P < .001). CONCLUSION: The invaginating anastomosis in portoenterostomy promised a sustained bile drainage and improved long-term outcome by preventing cicatricial contraction of the portahepatis.

Anastomosis, Surgical↗

PubMed1999

Evidence that far-infrared radiation promotes growth of Xenopus laevis.

In most ectotherms, environmental temperature has differential effects on growth and differentiation. For example, amphibian size at maturity decreases with increasing temperature. To address how radiant heat in the form of far-infrared radiation (FIR) may affect development of the aquatic ectotherm Xenopus laevis, we continuously irradiated swimming larvae as they developed into young adults. Here we report evidence that FIR promotes growth of these organisms in an aqueous environment.

Animal Husbandry↗

PubMed1999

The structure of the avian fast skeletal muscle troponin T gene: seven novel tandem-arranged exons in the exon x region.

To elucidate the mechanism that produces enormous molecular diversity in troponin T (TnT) of fast skeletal muscle, we determined the 5'-half genomic sequence of the chicken fast muscle TnT gene. The sequence of ca. 16 kb included seven exons (exons 1, 2, 3, 4, w, 5, and 6), which have been reported previously and presumed by sequencing TnT cDNAs. Additionally we found six 15 nt and one 18 nt sequences in the region between exons 5 and 6 (i.e. the exon x region). They were encompassed by consensus splice donor and acceptor sites and preceded by putative branch sites, and designated herein as exons xa to xg. Our result shows that the sequence derived from exons x1, x2, and x3, the exons presumed previously by cDNA sequencing, is actually encoded by the seven exons xa to xg, establishing the precise gene structure in the exon x region. Based on our data, together with that on the 3'-half genomic sequence of the quail fast muscle TnT gene, we conclude that the avian fast skeletal muscle TnT gene includes 27 exons, 16 of which are alternatively spliced.

Animals↗

PubMed1998

Conditional expression of the dual-specificity phosphatase PYST1/MKP-3 inhibits phosphorylation of cytosolic phospholipase A2 in Chinese hamster ovary cells.

Stimulation of platelet-activating factor (PAF) receptor induces activation of extracellular signal-regulated kinase (ERK) and cytosolic phospholipase A2 (cPLA2) and release of arachidonic acid in Chinese hamster ovary cells. To determine whether the dual-specificity protein phosphatase PYST1/MKP-3 inhibits phosphorylation of cPLA2, we have generated a cell line that conditionally expresses PYST1 under the control of a tetracycline-regulated inducible system. We found that induction of PYST1 suppressed phosphorylation and activation of cPLA2 as well as ERK. Arachidonic acid release was also reduced by about 30%. Pretreatment of cells with an MEK inhibitor, PD98059, had similar effects on PAF-induced cPLA2 phosphorylation and arachidonic acid release. These experiments demonstrate that expression of PYST1 prevents phosphorylation of a cytoplasmic substrate for ERK. Thus, this inducible system may offer a valuable means of investigating physiological roles of ERK in vivo.

Animals↗

PubMed1998

Skeletal muscle regeneration induced by chorio-allantoic grafting.

To examine whether the expression pattern of fast-muscle type troponin-T (TnT) isoforms was fixed in cell lineage, breast muscle pieces (pectoralis major) from chick embryos and young and adult chickens were grafted on to chorio-allantoic membrane of 9-day-old chick embryos and cultured until the host embryos hatched out. Muscle fibre formation of the grafts was investigated by histological and immunohistochemical methods with anti-fast-muscle type and anti-slow-muscle type TnT sera, and the expression of fast-muscle type TnT in the grafts from chick embryos and young chickens was studied by SDS-polyacrylamide gel electrophoresis (SDS-PAGE), two-dimensional SDS-PAGE, and immunoblotting. In the chorio-allantoic grafting, the breast muscle initially degenerated forming pyknotic nuclei and hyaline cytoplasm. The surviving cells, which were supposed to be satellite cells, regenerated new muscle fibres of the same type as those of the grafted muscle in respect of TnT isoform expression. Therefore, we considered that the ability to express specific isoforms of TnT was fixed in the satellite cells, and that chorio-allantoic grafting was a useful technique for studying muscle differentiation.

Allantois↗

PubMed1998

Cooperative roles of colon and anorectum during spontaneous defecation in conscious dogs.

Colorectal motility during spontaneous defecation was investigated using force strain gauge transducers implanted in the proximal colon, distal colon, rectum, and anus in six dogs. One 24-hr recording and several defecation recordings were made in each dog. During 24-hr recordings, 29 giant contractions were observed in the distal colon. The giant contractions, which propagated to the rectum, accompanied evacuation more frequently than those that stopped at the distal colon (P < 0.05). Of 66 episodes of defecation, 63 (95%) were accompanied by a giant contraction of the distal colon. Of these, 57 (90%) propagated to the rectum. In three events, giant contraction originated at the rectum. The rectum relaxed prior to the contraction. The internal anal sphincter also relaxed. Migration of giant contraction to the rectum, rectal relaxation-contraction sequence and sphincter relaxation played important roles during defecation. Defecation is a consequence of successive phenomena occurring in both the colon and anorectum.

Anal Canal↗

PubMed1998

Evidence that far infrared radiation promotes growth of Xenopus laevis.

Animals↗

PubMed1997

Neuronal nicotinic acetylcholine receptor in the hypothalamus: morphological diversity and neuroendocrine regulations.

The subcellular localization and functional significance of neuronal nicotinic acetylcholine receptor alpha4-subunits were investigated in the rat hypothalamic supraoptic nucleus. A high level of alpha4 mRNA expression was found in the magnocellular neurons in the supraoptic nucleus. Strong immunoreactitivy for alpha4 in neurons of the supraoptic nucleus was detected in the rough endoplasmic reticulum and cytoplasmic matrix, although it was very weak in the Golgi apparatus, except for the transport vesicles. Immunoreactivity for alpha4 was detected in both the pre-synaptic axon terminals and post-synaptic axon terminals. A high level of signals for vasopressin mRNA was detected in the supraoptic nucleus after the animals were injected s.c. with nicotine. These findings suggest that alpha4-containing subtypes are synthesized in the rough endoplasmic reticulum and transported to the plasma membrane and serve as pre- and post-synaptic nicotinic acetylcholine receptors. Nicotine may up-regulate vasopressin gene expression in the supraoptic nucleus, acting through nicotinic acetylcholine receptors.

Animals↗

PubMed1997

Natural occurrence of fast- and fast/slow-muscle chimeric fibers in the expression of troponin T isoforms.

Rhomboideus, one of the back muscle tissues, and its single fibers were studied in chickens by immunostaining with antisera against fast- and slow-muscle-type troponin T isoforms. Nonuniform distribution of slow-muscle-type isoforms was for the first time detected in single fibers isolated from the muscle, although fast-muscle-type troponin T isoforms were distributed over the whole length of the fiber. Based on these observations, we conclude that fast- and fast/slow-muscle chimeric fibers exist in normal skeletal muscle tissue and that the existence of chimeric fibers is direct evidence showing that myonuclei subjected to different determination in troponin T isoform expression can together form a single muscle fiber.

Aging↗

PubMed1997

More than 10 years' follow-up to total colonic aganglionosis--severe iron deficiency anemia and growth retardation.

Seven cases of total colonic aganglionosis were reviewed with a follow-up period of 10 to 26 years, focusing on the relationship between the length of aganglionic ileum and postoperative metabolic disorders. Pulled-through ileum ranged from 0 to 65 cm from the ileocecal valve, and suprapelvic side-to-side anastomosis was performed between the pulled-through ileum and 17 to 40 cm of aganglionic colon (left side and transverse colon, four; right side colon, one; no colonic patch, two). Hemoglobin level in three out of four patients with ileal involvement of more than 25 cm was below 11 g/dL (10.9, 7.7, 6.6 g/dL, respectively). Serum iron level was less than 30 micrograms/dL (27, 21, 20, 18 micrograms/dL, respectively) in four out of five patients with ileal involvement of more than 10 cm. Serum vitamin B12 level was below 100 (100, 46 pg/dL, respectively) in two patients whose pulled-through ileum was 45 cm and 65 cm, respectively from the ileocecal valve. One patient needs periodical parenteral iron therapy and one was treated as megaloblastic anemia. In the patients with ileal involvement of more than 25 cm, both weight and height for age are very low at less than the fifth percentile, except for one patient whose side patch was at the right colon. One patient still needs parenteral nutritional support. Severe iron deficiency anemia, low level of B12, and growth retardation are apparent in the patients with total colonic aganglionosis with ileal involvement. Colonic side-to-side anastomosis does not substitute for the loss of terminal ileum.

Anastomosis, Surgical↗

PubMed1997

Stability of chicken troponin T expression in cultured muscle cells.

Cells prepared from chicken skeletal muscles of early developmental stages were cultured to study their troponin T isoform expression, using antisera specific to fast- and slow-muscle-type isoforms, and compared with the cells from later stages described in the previous study (Mashima at al., 1996). We found that cultured myogenic cells from chickens and chick embryos could be classified, as in the previous study, into two types, fast type and fast/slow type in which fast- and slow-muscle-type isoforms were coexpressed. Ratios of these two types of muscle cells varied depending on their origins and developmental stages, and fast/slow type cells were in the majority at early stages. Since two distinct populations of cells committed to myogenic cell lineages were supposed to give rise to the two types of myotubes, we investigated the intrinsic stability of troponin T expression of the cultured myogenic cells using the serial subcloning method. The results of clonal analysis suggested that the expression pattern of troponin T isoform in cultured muscle cells is stable and that myogenic cell lineages play an important role in giving rise to different muscle types.

Animals↗

PubMed1997

Regulation of troponin T gene expression in chicken fast skeletal muscle: involvement of an M-CAT-like element distinct from the standard M-CAT.

Troponin T (TnT), like other myofibrillar proteins, is expressed as various isoforms in different muscle fibers and/or at different development stages. A recent study suggested the expression pattern of chicken fast TnT isoforms is fixed in a given cell lineage. In the present study, we isolated genomic clones of the chicken fast TnT gene to carry out molecular analysis of its expression mechanism. One of the clones, pWETNTa, contained the 5' upstream region and approximately 20 kb downstream from exon 1. We constructed promoter/upstream segments of the chicken fast TnT gene linked to the bacterial chloramphenicol acetyltransferase (CAT) gene and tested the regulatory function of the 5' upstream region by transient transfection of the gene constructs into muscle cells. We showed that a DNA segment between -264 and -44 bp from the most 5' transcriptional initiation site, which has an MEF2, and M-CAT-like element, a CArG box and two E boxes, was essential for the expression of the fast TnT gene. Furthermore, mutation of the M-CAT-like element in the segment resulted in the most serious reduction in the fast TnT promoter activity. The results suggested that the M-CAT-like element plays an important role in transcriptional regulation of the fast TnT gene. The M-CAT-like element is very similar to the M-CAT element, but in electrophoretic mobility shift assay, the factor(s) that bound to this motif was found to be different from the M-CAT binding factor (MCBF).

Animals↗

PubMed1996

Cloning of chicken slow muscle troponin T and its sequence comparison with that of human.

A full-length cDNA coding for chicken slow muscle troponin T (TnT) was for the first time isolated from a cDNA library of 10-day-old embryos, using an RT-PCR product of chicken slow muscle TnT. It showed about 60% homology for chicken fast and slow muscle TnTs and 75.2% for human slow muscle TnT. The 16 amino acid sequence found in the carboxyl terminus of human slow muscle TnT was absent in the chicken slow muscle TnT. The 5E-5A-7E sequence found in the amino terminal region of chicken slow muscle TnT was partly similar to the counterpart of human slow muscle TnT, but not to those of chicken fast and cardiac muscle TnTs. With this report of chicken slow muscle TnT, cDNA information on chicken TnTs of all three striated muscles was completed following those of human TnTs.

Amino Acid Sequence↗

PubMed1996

Targeted disruption of gp130, a common signal transducer for the interleukin 6 family of cytokines, leads to myocardial and hematological disorders.

gp130 is a ubiquitously expressed signal-transducing receptor component shared by interleukin 6, interleukin 11, leukemia inhibitory factor, oncostatin M, ciliary neurotrophic factor, and cardiotrophin 1. To investigate physiological roles of gp130 and to examine pathological consequences of a lack of gp130, mice deficient for gp130 have been prepared. Embryos homozygous for the gp130 mutation progressively die between 12.5 days postcoitum and term. On 16.5 days postcoitum and later, they show hypoplastic ventricular myocardium without septal and trabecular defect. The subcellular ultrastructures in gp130-/- cardiomyocytes appear normal. The mutant embryos have greatly reduced numbers of pluripotential and committed hematopoietic progenitors in the liver and differentiated lineages such as T cells in the thymus. Some gp130-/- embryos show anemia due to impaired development of erythroid lineage cells. These results indicate that gp130 plays a crucial role in myocardial development and hematopoiesis during embryogenesis.

Animals↗

PubMed1996

Chronic rejection in lung allografts: immunohistological analysis of fibrogenesis.

In ongoing chronic rejection after lung transplantation, alveolar interstitial fibrosis develops. However, little is known about the mechanisms involved. In order to investigate these mechanisms, expression of extracellular matrix molecules (ECM) (undulin, decorin, tenascin, laminin, and fibronectin) and cytokines [transforming growth factor (TGF)-beta 1, TGF-beta 3, platelet-derived growth factor (PDGF), and PDGF receptor] were semiquantitatively evaluated in chronically rejected lung allografts, using standard immunohistochemical techniques. Additionally, the presence of macrophages was analysed. The present study demonstrates an increased infiltration of macrophages with a concomitant upregulation of cytokines (TGF-beta 1, TGF-beta 3, and PDGF) and an increased deposition of ECM in chronic lung rejection. These cytokines have an important role in the stimulation of fibroblasts which are a major source of ECM. Upregulated expression of ECM in the alveolar interstitial space leads to alveolar malfunction by thickening of the wall and, thus, is one of the causative factors of respiratory dysfunction in chronic lung graft rejection.

Adult↗