Biomedical subjects

K Miyahara

Publications and source records attributed to K Miyahara.

At least 55 records · Page 3Linked to original sources

PubMed2000

[Modified Konno procedure for a child with left ventricular outflow tract obstruction after repair of atrioventricular septal defect: a transaortic transpulmonary approach].

A one-year-old infant underwent repair of atrioventricular septal defect with common orifice. About 2 years later, echocardiography revealed a left ventricular outflow tract obstruction for the first time. Because of progression of the obstructive lesion, a modified Konno procedure through a transaortic transpulmonary approach was later performed at 8 years old, and the postoperative course was uneventful. This is a useful procedure for left ventricular outflow tract obstruction with normal aortic valve and aortic annulus, because it can both preserve a native aortic valve and dose not necessitate right ventriculotomy in resection of hypertrophied muscle and patch enlargement of interventricular septum.

Aorta↗

PubMed1999

Tissue factor pathway inhibitor-2 is a novel mitogen for vascular smooth muscle cells.

A mitogen for growth-arrested cultured bovine aortic smooth muscle cells was purified to homogeneity from the supernatant of cultured human umbilical vein endothelial cells by heparin affinity chromatography and reverse-phase high performance liquid chromatography. This mitogen was revealed to be tissue factor pathway inhibitor-2 (TFPI-2), which is a Kunitz-type serine protease inhibitor. TFPI-2 was expressed in baby hamster kidney cells using a mammalian expression vector. Recombinant TFPI-2 (rTFPI-2) stimulated DNA synthesis and cell proliferation in a dose-dependent manner (1-500 nM). rTFPI-2 activated mitogen-activated protein kinase (MAPK) activity and stimulated early proto-oncogene c-fos mRNA expression in smooth muscle cells. MAPK, c-fos expression and the mitogenic activity were inhibited by a specific inhibitor of MAPK kinase, PD098059. Thus, the mitogenic function of rTFPI-2 is considered to be mediated through MAPK pathway. TFPI has been reported to exhibit antiproliferative action after vascular smooth muscle injury in addition to the ability to inhibit activation of the extrinsic coagulation cascade. However, structurally similar TFPI-2 was found to have a mitogenic activity for the smooth muscle cell.

Animals↗

PubMed1999

Nitric oxide inhibits HIV tat-induced NF-kappaB activation.

To evaluate the roles of nitric oxide (NO) on human immunodeficiency virus (HIV) Tat-induced transactivation of HIV long terminal repeat (HIV-LTR), we examined the effect of NO in the regulation of nuclear factor (NF)-kappaB, a key transcription factor involved in HIV gene expression and viral replication. In the present study, we demonstrate that HIV Tat activates NF-kappaB and that this activation can be attenuated by endogenous or exogenous NO. Inhibition of endogenous NO production with the NO synthase (NOS) inhibitor L-NMMA causes a significant increase in Tat-induced NF-kappaB activity. In addition, NO attenuates signal-initiated degradation of IkappaBalpha, an intracellular inhibitor of NF-kappaB, and blocks the DNA binding activity of the NF-kappaB p50/p50 homodimer and p50/p65 heterodimer. To determine how NO is induced by HIV Tat, reverse transcription polymerase chain reaction was used to demonstrate the induction of NOS-2 and NOS-3 mRNA by Tat. Although a putative NF-kappaB binding site was identified in the -74 GGAGAGCCCCC -64 region of the NOS-3 gene promoter, gel mobility shift assays and site-directed mutation analyses suggest that the putative NF-kappaB site is not of primary importance. Rather, several Sp-1 sites adjoining the putative NF-kappaB binding site in the promoter region of NOS-3 gene are required for the induction of NOS-3 gene expression by Tat.

Animals↗

PubMed1999

Components of the ether-insoluble resin glycoside fraction from the seed of Cuscuta australis.

An ether-insoluble resin glycoside fraction was obtained from the seeds of Cuscuta australis. Identification and characterization of alkaline hydrolysis products by means of GC, FABMS, and 1H, 13C, and 2D NMR revealed the material to be composed of three new glycosidic acids, cuscutic acids A1-A3 (1-3); triglycosides with (11S)-jalapinolic or (11S)-convolvulinolic acid as the aglycon; and acetic, isobutyric, (2S)-2-methylbutyric, tiglic, and (2R,3R)-nilic acids. The resin glycoside is considered to be a complex mixture of glycosidic ester-type oligomers (up to heptamers) with a core consisting of a number of the above cuscutic acids each acylated with one or two carboxylic acid moieties.

Carbohydrate Sequence↗

PubMed1999

Experimental His-bundle pacing: histopathological and electrophysiological examination.

His-bundle pacing gives a more physiological ventricular contraction in comparison to right ventricular apical pacing. However the problems of lead fixation and stability of long-term His-bundle pacing are yet unsolved. We used six adult beagles, in which a screw-in lead was anchored in the His-bundle region for observation of the pacing conditions and histopathologic changes of the conduction system over the course of 2 months. In the results, a satisfactory fixation was obtained using a conventional screw-in lead and no histological influence on the conduction system was observed. The pacing threshold at the time of implantation was 1.15 +/- 0.69 V (3.23 +/- 3.08 mA) in the pulse width of 0.5 ms. R wave amplitude, the impedance and slew rate were 7.28 +/- 2.04 mV, 409 +/- 102 Ohm, and 0.65 +/- 0.41 V/s, respectively. Two months later, these parameters changed to 2.83 +/- 1.06 V (10.4 +/- 5.71 mA), 5.63 +/- 1.62 mV, 310 +/- 71.3 Ohm, and 0.49 +/- 0.22 V/s, respectively. These results suggest the feasibility of clinical application of permanent His-bundle pacing.

Animals↗

PubMed1999

Glycerophosphocholines of the earthworm, Pheretima asiatica.

The lipid composition of the earthworm, Pheretima asiatica (Annelida), was analyzed. Four glycerophospholipids, together with four known glycosphingolipids, were isolated in pure form. The former four were 1-alkyl 2-acyl glycerophosphocholines possessing a C17:0 and/or C18:1 fatty acid residue. Their structures, including the position and geometry of the double bond, were determined on the bases of chemical and spectral data.

Animals↗

PubMed1999

Radioprotective effects of sodium tungstate on hematopoietic injury by exposure to 60Co gamma-rays in Wistar rats.

Radioprotective effects of sodium tungstate (ST) on 60Co gamma-ray induced decrease in hematocrit value and in survival rate in Wistar strain male rats were examined. A long-term administration of ST (less than 150 mg/kg body weight/day) for 60-300 days had no significant effects on body and organs weights and survival days. The LD50/60 in 20 weeks old rats was 220 mg/kg body weight/day. Daily administration of 38, 75 or 150 mg from 7 days before and after irradiation to 60 days significantly mitigated the decrease in hematocrit values, especially at 23 days after irradiation (P < 0.05). The highest mitigation rate of the decrease in hematocrit value was observed in rats administered at a dose of 38 mg ST/day. Simultaneously, a dose of 38 mg ST/day inhibited lethal effect of 60Co gamma-rays significantly. The dose-reduction factor for survival of 38 mg ST administered rats was 1.14.

Animals↗

PubMed1999

A case of a dog with thickened calvaria with neurologic symptoms: magnetic resonance imaging (MRI) findings.

A 6-year-old female mongrel dog weighing 9.0 kg was presented ananastatic, with clouding of consciousness, bilateral loss of hearing and depressed reactivity of the eyes to light. Magnetic resonance imaging (MRI) examination showed that the calvaria was markedly thickened with compression to the cerebrum and cerebellum. The case of a dog with thickened calvaria with compression of the cerebrum and cerebellum which could not be diagnosed by conventional measures was amenable to diagnosis by MRI. With increased application of MRI examination, such canine cases might increase in number.

Anemia↗

PubMed1999

Development of atherosclerotic lesions in cholesterol-loaded rabbits.

To examine both of the target vessels and the optimal time of their endothelial denudation to study vascular restenosis after balloon injury in cholesterol-loaded rabbits, we made 36 atherosclerotic rabbits by feeding a hypercholesterol diet, and histologically examined the onset time and the development of atherosclerosis. Atheromatous changes were observed first after the 5th week in the thoracic aorta from the start of the diet, and then extended to the abdominal aorta, coronary artery with time. The atherosclerotic lesions in the thoracic aorta and the proximal portion of the coronary artery showed high-grade concentric intimal thickening with luminal stenosis. The abdominal aortic lesion mildly progressed. In the renal, carotid and femoral arteries, in contrast, slight atheroscleromatous changes developed during the diet period. These results suggest that the thoracic and abdominal aortas and the coronary artery would be suitable as target vessels to study vascular restenosis after balloon injury, and the endothelial denudation of these vessels should be performed between the 8th and 15th week in this diet protocol for an accurate analysis.

Animals↗

PubMed1999

Successful use of high frequency oscillatory ventilation for pneumomediastinum.

An infant with pneumomediastinum due to mechanical ventilation was successfully treated using high frequency oscillatory ventilation (HFOV). The 3-month-old male had undergone ligation of a patent ductus arteriosus and suffered from barotraumatic pneumomediastinum in the postoperative period. Computed tomography of the chest confirmed the diagnosis. While using conventional mechanical ventilation the respiratory failure worsened. HFOV was instituted and the patient improved. A lower airway pressure by this mode of ventilation provided significant advantages in the patient with an air leak. He was subsequently extubated and discharged home.

Barotrauma↗

PubMed1999

A long-term follow-up study of cervical spondylotic myelopathy treated by "French window" laminoplasty.

We investigated 30 patients with multilevel cervical spondylotic myelopathy (22 males and 8 females) treated by "French window" laminoplasties from 1979 to 1988. Patients averaged 62.6 years of age, and were followed an average of 5 years and 2 months. The average preoperative and postoperative Japanese Orthopaedic Association (JOA) scores were assessed, rising from the original 8.8 +/- 3.4 to 11.9 +/- 3.3 (p < 0.001). Patients were divided into two groups, demonstrating poor alignment and no malalignment after surgery. There was no statistical difference regarding improvement in the neurological examinations between these two groups. The "French window" laminoplasty achieved good clinical results in the management of cervical spondylotic myelopathy irrespective of whether or not alignment deteriorated in the postoperative period.

Cervical Vertebrae↗

PubMed1999

Extended use of hemofiltration and high perfusion flow rate in cardiopulmonary bypass improves perioperative fluid balance in neonates and infants.

We evaluated the efficacy of the extended use of hemofiltration (EHF) and high perfusion flow rate in cardiopulmonary bypass (CPB) in pediatric open-heart surgery retrospectively. In the EHF method, hemofiltration was used for hemic prime before initiation of the bypass and ultrafiltration was used throughout the bypass. Thirty-four children, with transposition of great arteries who were undergoing arterial switch operation with the use of hemic prime, were subjects of this study. They were divided into 2 groups, a control group (n = 16) and a group (n = 18) that underwent EHF. There were no significant differences between groups in demographics, but the maximum perfusion index and lowest rectal temperature were higher in the EHF group. This study compared urination during bypass, arterial oxygen pressure at the end of bypass and operation, the duration of the ventilation, and postoperative soft tissue index (STI) expressing the severity of edema. In the EHF group, urination during bypass was significantly higher, and there was a tendency to higher arterial oxygen pressure. The patients in the EHF group were weaned from the ventilator significantly earlier. Postoperative STI was significantly higher, so edema was more severe in the control group. We consider that the use of EHF and a high perfusion flow rate in CPB are an ideal method to improve the perioperative fluid balance in pediatric open-heart surgery. We suspect that these good clinical effects result from maintaining the inflammatory mediators at a low level throughout the bypass, reducing the following release of the mediators and attenuating the interaction of the mediators.

Blood Flow Velocity↗

PubMed1999

[Experience with repair of muscular trabecular ventricular septal defects].

We reviewed the records of 9 pediatric patients with muscular trabecular ventricular septal defects undergoing repair between April 1994 and June 1998 (mean age 2.6 +/- 3.1 years, mean weight 9.0 +/- 5.2 kg). The prevalence rate for muscular trabecular defects in the patients undergoing open-heart surgery for congenital heart disease was 2.0%. Although only 6 of the 9 patients were diagnosed as having muscular trabecular defects preoperatively, 60 degrees left anterior oblique and 30 cranially tilted projections of left ventricular cineangiocardiogram were useful to detect these defects. The technique of filling the left heart with blood by stopping to vent the left heart and inflating the lungs during the last one or two ligatures in closure of the defects was also useful to detect these defects intraoperatively. In closure of muscular trabecular defects, division of some trabeculations including a moderator band enabled complete repair through a right atriotomy. The nearer the inferior border of the ventricular septal defects were to the heart apex, the more postoperative residual shunts were left. We consider that apical left ventriculotomy may be needed in apical defects, although the right atrial approach is satisfactory for most muscular trabecular defects.

Child↗

PubMed1998

Role of calcineurin and Mpk1 in regulating the onset of mitosis in budding yeast.

Signalling via calcium is probably involved in regulating eukaryotic cell proliferation, but details of its mechanism of action are unknown. In Schizosaccharomyces pombe, the onset of mitosis is determined by activation of a complex of the p34cdc2 protein kinase and a cyclin protein that is specific to the G2 phase of the cell cycle. This activation requires dephosphorylation of p34cdc2. Weel, a tyrosine kinase that inhibits p34cdc2 by phosphorylating it, is needed to determine the length of G2 phase. Here we show that calcium-activated pathways in Saccharomyces cerevisiae control the onset of mitosis by regulating Swel, a Weel homologue. Zds1 (also known as Oss1 and Hst1) is important in repressing the transcription of SWE1 in G2 phase. In the presence of high calcium levels, cells lacking Zds1 are delayed in entering mitosis. Calcineurin and Mpk1 regulate Swel activation at the transcriptional and posttranslational levels, respectively, and both are required for the calcium-induced delay in G2 phase. These cellular pathways also induce a G2-phase delay in response to hypotonic shock.

Adaptor Proteins, Signal Transducing↗

PubMed1998

[Coronary artery bypass grafting in cases with poor left ventricular function].

From January 1987 through June 1992, 18 patients with poor left ventricular function (left ventricular ejection fraction [LVEF] less than 0.3) underwent elective isolated primary coronary artery bypass surgery. The mean age was 56.4 years (range, 46 to 72 years), and 15 were males and 3 were females. Mean pre-operative LVEF measured by ventriculography was 0.26 +/- 0.03 (range, 0.19 to 0.30). Sixteen patients (88.9%) had a prior myocardial infarction and 9 (50%) had a history of congestive heart failure. Complete revascularization was the goal for all patients, and the mean number of bypass grafts was 3.0 +/- 0.8 per patient. The left anterior descending coronary artery (LAD) was revascularized in all patients. There were no operative deaths. Post-operative LVEF improved significantly from 0.26 +/- 0.03 to 0.42 +/- 0.11 (p = 0.0002), and the regional left ventricular wall motion improved in the diaphragmatic and posterobasal regions (p < 0.01). The patency of the grafts was 93.9% in all, and 100% for LAD. The mean follow-up period was 77 months, and the overall actuarial survival rate was 88.9% at 10 years. During follow-up periods, two patients died of congestive heart failure (CHF), and two required three rehospitalizations because of CHF. The overall cardiac event free rate was 75.8% at 10 years. In patients with poor left ventricular function, surgical revascularization can be performed safely, but congestive heart failure sometimes occurs during follow-up periods and may be the cause of death. Therefore alternate forms of therapy such as cardiac transplantation and/or TMLR should be considered in selected patients.

Aged↗

PubMed1998

[Two staged Starnes operation for Ebstein's anomaly with pulmonary atresia in early infancy--a report of a successful case].

Severe tricuspid valve regurgitation and decreased pulmonary blood flow in neonatal Ebstein's anomaly with pulmonary atresia, may result in cardiac respiratory failure and hypoxemia. The poor natural course and lack of standard surgical treatment make treatment for neonatal Ebstein's anomaly very difficult. The Blalock-Taussig operation was performed for hypoxemia in Ebstein's anomaly associated with pulmonary atresia and severe tricuspid regurgitation on 36th day after birth. On the 63rd day after birth, tricuspid valve orifice closure and right atrium plication (Starnes procedure) were accomplished under cardiopulmonary bypass. Heart failure became controllable and the patient condition was satisfactory at one year after surgery.

Anastomosis, Surgical↗

PubMed1998

Idiopathic peripheral neuropathy in the horse with knuckling: muscle and nerve lesions in additional cases.

We have previously reported a pathological investigation of peripheral neuropathy in a horse with knuckling. This report describes details of the muscle and peripheral nerve lesions in two additional cases of light horse yearlings with knuckling. The skeletal muscles showed neurogenic atrophy characterized by scattered single angular fibers, fiber grouping, and fiber-type grouping. The severity of muscle lesions increased distally; that is, both fore- and hindleg muscles were affected more severely than cervical and dorsal muscles. In the peripheral nervous system, a number of Renaut bodies appeared to be common in the nerve fascicles. Pathological alterations indicating demyelination, remyelination and regeneration of nerve fibers were occasionally observed. The most common abnormality was myelin ovoids or myelin debris infiltrated by macrophages. Occasionally, myelinated axons were seen containing accumulations of organelles, often associated with buckling of the myelin. The myelin sheath occasionally formed axonal outpouching containing accumulations of mitochondria and dense lamellar bodies. Histochemically, intramuscular nerve fibers presented multiple arborization and collateral ramification, indicating relapsing denervation and reinnervation. Also seen were the fibers with myelin balloons or swollen segments considered as being degenerative processes. The distribution patterns of muscular lesions in the affected animals were indicative of systemic distal denervation atrophy. In addition, peripheral nervous lesions that selectively involve the distal parts of axons and an absence of abnormalities in neuronal cell bodies in the spinal cord suggest a dying-back neuropathy. It was concluded that this disease should be classified as a distal axonopathy.

Animals↗

PubMed1998

Stoloniferins VIII-XII, resin glycosides, from Ipomoea stolonifera.

Five new ether-soluble resin glycosides were isolated from whole plants of Ipomoea stolonifera. Their structures have been determined on the basis of chemical and spectral data. Similar to the resin glycosides previously isolated, all of them are monomers of a jalapinolic acid tetra- or penta-glycoside in which the sugar moiety is partially acylated by organic acids and also combined with the carboxy group of the aglycone to form a macrocyclic ester structure.

Carbohydrate Conformation↗