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Biomedical subjects

T Hata

Publications and source records attributed to T Hata.

At least 325 records · Page 18Linked to original sources
PubMed1993

Echocardiographic assessment of systolic time intervals in vaginal and cesarean delivered neonates.

Echocardiographic assessments of fetal and neonatal systolic time intervals were made to determine differences in circulatory changes in 40 neonates delivered vaginally and 30 delivered by elective cesarean section. Left preejection period (LPEP), left ventricular ejection time (LVET), LPEP/LVET, right preejection period (RPEP), right ventricular ejection time (RVET), RPEP/RVET, and heart rate were determined at various time points from antenatal to 120 hours after delivery. There were no significant changes in left systolic time intervals between the two groups at any various time points. However, RPEP and RPEP/RVET values were significantly higher in the cesarean section group than in those in normal vaginal delivery group within 12 hours after delivery. These results suggest that the transient pulmonary hypertension after delivery is prolonged in babies delivered by elective cesarean section.

Cesarean Section↗
PubMed1993

A combined anterolateral thigh flap, anteromedial thigh flap, and vascularized iliac bone graft for a full-thickness defect of the mental region.

A triple combined anterolateral thigh flap, anteromedial thigh flap, and vascularized iliac bone graft was used for reconstruction of a full-thickness defect of the mental region after wide resection of advanced tongue cancer. The distal end of the pedicle vessels of these double skin flaps, i.e., the lateral circumflex femoral system, was directly anastomosed in tandem to the pedicle of the iliac bone graft, which was enveloped by these flaps. The advantages of this iliac osteocutaneous flap are as follows: It can be transferred within a shorter surgical time because the flaps can be obtained in the supine position simultaneously with tumor resectioning; and its skin components can be separated from the bone because each component has its own pedicle vessels, has a longer vascular pedicle (> 10 cm), and has a thicker crest of the bone graft. This flap is believed to be suitable for reconstruction of large full-thickness defects in various sizes of the mandibular and maxillary regions of the face.

Aged↗
PubMed1993

Acute left main coronary artery obstruction with myocardial infarction--reperfusion strategies, and the clinical and angiographic outcome.

We studied the clinical and angiographic outcomes in 8 patients with acute left main coronary artery obstruction. Intracoronary thrombolysis with 1.2 x 10(5) units of urokinase was performed in 3 patients during preparation for percutaneous transluminal coronary angioplasty (PTCA), and failed in all 3 cases. In 2 patients, the left main coronary artery was recanalized by intracoronary thrombolysis with 3.6 and 4.8 x 10(5) units of urokinase, respectively. PTCA was attempted either before or after intracoronary thrombolysis in 5 patients and achieved reperfusion in all 5 cases. However, 2 of the 8 patients had persistent high-grade residual stenosis 69% and 89% luminal reduction, respectively. Emergency coronary artery bypass grafting was successfully performed in these 2 patients, and both are currently alive. Although intraaortic balloon counterpulsation was performed in all 8 patients, 2 died acutely from pump failure in the catheterization laboratory. One patient died later due to congestive heart failure. The factors favoring survival were right coronary artery dominance and a well-developed collateral circulation. Our findings suggest that PTCA is a useful strategy for reperfusion following acute left main coronary artery occlusion. When PTCA cannot achieve sufficient revascularization, emergency coronary artery bypass grafting should be performed. To control pump failure, intraaortic balloon counterpulsation is insufficient in some cases and more aggressive measures may be required.

Aged↗
PubMed1993

Changes of pial vessel diameter and CO2 reactivity during insulin-induced hypoglycemia and in the recovery period following glucose administration.

The present study examined the changes of cerebrovascular CO2 reactivity during insulin-induced hypoglycemia and in the recovery period following glucose administration in cats. The diameters of pial vessels were continuously measured using the vidicon camera system. Hypoglycemia was induced by intraperitoneal injection of Actrapid insulin (100 IU/kg). Cerebrovascular CO2 reactivity was estimated by the changes of pial vessel diameters during 3 min inhalation of 5% CO2 in air at each stage of glucose level. CO2 reactivity was impaired in the hypoglycemic stage and this impairment was further enhanced in the early recovery stage. In the late recovery stage, CO2 reactivity was restored particularly in the small arteries which were less innervated by autonomic nerves. These results suggest that the sympathetic activity plays an important role in the impairment of cerebrovascular CO2 reactivity during hypoglycemia.

Animals↗
PubMed1993

Role of endothelin in heart function in health and disease.

A comprehensive review of the literature has revealed that endothelins belong to a family of vasoactive peptides which are formed and released from the endothelium. By producing constriction of the coronary arteries and peripheral blood vessels, endothelins are known both to reduce coronary bloodflow and increase blood pressure and thus can be seen to affect heart function adversely. On the other hand, endothelins are capable of producing positive inotropic and chronotropic effects by directly affecting both the myocardium and nodal tissues. Prolonged actions of high concentrations of endothelins can be seen to induce relative hypoxia in the myocardium which will eventually result in heart dysfunction. The mechanisms of actions of endothelin on smooth muscle cells and cardiomyocytes include interaction with endothelin receptors on the cell surface, activation of phospholipase C through G-proteins, and increase in the intracellular concentration of Ca2+ through the increase in phosphoinositol turnover. Endothelins were found to exert no effects on sarcolemmal Na+,K(+)-ATPase, Na(+)-Ca2+ exchange and Ca2+ pump systems nor on the sarcoplasmic reticular Ca2+ pump system and myofibrillar ATPase activities in the rat heart. Marked elevation in the levels of plasma endothelins and down-regulation of endothelin receptors in ischemia-reperfusion injury, hypertension and chronic diabetes indicate a significant role of endothelins in the genesis of heart dysfunction under different pathological conditions.

Animals↗
PubMed1993

[Superior sagittal sinus thrombosis in paroxysmal nocturnal hemoglobinuria--an autopsied case].

A 43-year-old Japanese man was admitted to our hospital because of acute occipital headache and drowsiness. He had been diagnosed as paroxysmal nocturnal hemoglobinuria (PNH) with acute renal failure for 2 months prior to the admission. He had abdominal pain and fever of unknown origin for 2 weeks. On admission neurological examination revealed mild disturbance of consciousness, right papilledema and minimal nuchal rigidity. The urinalysis was normal and blood hemoglobin was 8.3 g/dl. Mild hemolysis was suspected because of decreased level of the serum haptoglobin. The magnetic resonance imaging (MRI) of the brain demonstrated the complete occlusion of the superior sagittal sinus by fresh thrombus and the cerebral hemorrhage in the right parieto-occipital subcortex. No other cause for cerebral sinus thrombosis was detected. The patient was treated medically using anti-edema agents, but on the twentieth hospital day he died because of brain herniation. The postmortem examination disclosed thrombosis in the superior sagittal sinus and transverse sinus on both side. There was a massive hematoma in the right parieto-occipital subcortex. The spleen and kidney also contained multiple venous thromboses. Twelve cases of cerebral sinus thrombosis with PNH have been reported in the literatures. Although cerebral sinus thrombosis is a common complication with PNH in Caucasian, but is rare in Asian including Japanese. This may probably depend upon a racial difference. To our knowledge, this is the first report of a patient with cerebral sinus thrombosis with PNH in Japan.

Adult↗
PubMed1993

[A surgical case report of severe valvular aortic stenosis with atrial septal defect in a 78-year-old female].

We have experienced open heart surgery of severe valvular aortic stenosis associated with atrial septal defect in a 78-year-old female patient. This is the oldest case in Japanese literature. Because balloon valvuloplasty can not produce improvement in hemodynamic and clinical status, open heart surgery was performed as the final decision. The operative procedure consisted of aortic valve replacement with a 19 mm St. Jude Medical valve and direct closure of atrial septal defect. Postoperative course was excellent. The patient is doing well at the two years and three months of follow-up period.

Aged↗
PubMed1992

Identification of inducible calmodulin-dependent nitric oxide synthase in the liver of rats.

A calmodulin-dependent nitric oxide synthase was significantly induced in the liver of rats treated intravenously with heat-killed Propionibacterium acnes and 5 days later with Escherichia coli lipopolysaccharide. The apparent calmodulin-dependent and -independent isozymes were separated by Mono Q column chromatography after their partial purification by 2',5'-ADP-agarose affinity chromatography. Both enzymes had a molecular weight of 125,000 as determined by SDS-polyacrylamide gel electrophoresis and required NADPH, tetrahydrobiopterin, and dithiothreitol as cofactors. Their activities were completely inhibited by the specific nitric oxide synthase inhibitors NG-monomethyl-L-arginine and N omega-nitro-L-arginine at 80 and 800 microM, respectively. The peptide maps of these two isozymes with lysylendopeptidase and their reverse-phase column chromatographic profiles were indistinguishable. In the presence of bovine calmodulin, the purified calmodulin-dependent isozyme behaved as a calmodulin-independent isozyme on Mono Q column chromatography. The purified calmodulin-independent isozyme was converted to a calmodulin-dependent isozyme by EDTA and EGTA. Calmodulin blot analysis using 125I-calmodulin showed that the two isozymes bound calmodulin equally efficiently.

Amino Acid Oxidoreductases↗
PubMed1992

Molecular design of a eukaryotic messenger RNA and its chemical synthesis.

A designed mRNA consisting of 42 ribonucleotides having the cap structure was synthesized. The capped leader sequence of the brome mosaic virus (BMV) mRNA 4, m7G5'pppGUAUUAAUA (F-1), was synthesized by the phosphotriester method and followed by the capping reaction. A 32-mer consisting of an initiation codon (AUG), the coding region corresponding to a bacterial pheromone cAD1 and two stop codons, was constructed by the 18-mer (F-2) and 14-mer (F-3), which were synthesized by the phosphoramidite method. 2'-,3'-O-Methoxymethylene-guanosine 5'-phosphate was condensed with F-3 using P1-2',3'-O-methoxymethyleneguanosine-5'-yl P2-adenosine-5'-yl pyrophosphate (9) with T4 RNA ligase. The chemically synthesized RNA fragments were ligated successively with T4 RNa ligase to afford the whole RNA molecule.

Amino Acid Sequence↗
PubMed1992

Platelet hypoaggregability in rats exposed to SART stress (repeated cold stress).

A prolongation of bleeding time accompanied by thrombocytopenia and abnormalities in coagulation-fibrinolysis systems has been observed in laboratory animals exposed to a chronic form of environmental stress induced by severe fluctuations of air temperature, known as SART (specific alternation of rhythm in temperature) stress. In order to clarify the hemostatic profile under SART stress in more detail, the present study examined platelet aggregability in vitro as well as in vivo in stressed rats. During exposure to stress, thrombocytopenia developed from day 5, and remained up to at least day 14. In vitro aggregation of platelets stimulated by ADP or collagen was markedly decreased in stressed rats, compared with unstressed rats. Furthermore, stressed rats exhibited in vivo hypoaggregability of platelets, as estimated by the magnitude of the drop in circulating platelet counts following intravenous injection of ADP and collagen. Protein and cholesterol content in platelets remained constant after stress exposure. These results indicate that SART-stressed rats exhibit platelet dysfunctions in addition to thrombocytopenia. Considering the previous findings, the hemostatic system under SART stress appears to show a general tendency toward hemorrhage.

Adenosine Diphosphate↗
PubMed1992

Conformational rigidity of specific pyrimidine residues in tRNA arises from posttranscriptional modifications that enhance steric interaction between the base and the 2'-hydroxyl group.

In order to elucidate roles of the 2'-O-methylation of pyrimidine nucleotide residues of tRNAs, conformations of 2'-O-methyluridylyl(3'----5')uridine (UmpU), 2'-O-methyluridine 3'-monophosphate (Ump), and 2'-O-methyluridine (Um) in 2H2O solution were analyzed by one- and two-dimensional proton NMR spectroscopy and compared with those of related nucleotides and nucleoside. As for UpU and UmpU, the 2'-O-methylation was found to stabilize the C3'-endo form of the 3'-nucleotidyl unit (Up-/Ump-moiety). This stabilization of the C3'-endo form is primarily due to an intraresidue effect, since the conformation of the 5'-nucleotidyl unit (-pU moiety) was only slightly affected by the 2'-O-methylation of the 3'-nucleotide unit. In fact even for Up and Ump, the 2'-O-methylation significantly stabilizes the C3'-endo form by 0.8 kcal/.mol-1. By contrast, for nucleosides (U and Um), the C3'-endo form is slightly stabilized by 0.1 kcal/.mol-1. Accordingly, the stabilization of the C3'-endo form by the 2'-O-methylation is primarily due to the steric repulsion among the 2-carbonyl group, the 2'-O-methyl group and the 3'-phosphate group in the C2'-endo form. For some tRNA species, 2-thiolation of pyrimidine residues is found in positions where the 2'-O-methylation is found for other tRNA species.(ABSTRACT TRUNCATED AT 250 WORDS)

Dinucleoside Phosphates↗
PubMed1992

Hepatocyte growth factor is a paracrine factor for renal epithelial cells: stimulation of DNA synthesis and NA,K-ATPase activity.

The expressions of mRNAs of hepatocyte growth factor (HGF) and its receptor (c-met) and its effects were examined in cultured renal epithelial cell lines (OK, LLCPK1, and MDCK cells) and rat mesangial cells in primary culture. Northern blot analysis revealed the presence of HGF mRNA in mesangial cells, but not in epithelial cells. c-met mRNA was detected in epithelial cells, but not in mesangial cells. HGF stimulated [3H]-thymidine incorporation (DNA synthesis) dose-dependently in OK and LLCPK1 cells, but not in MDCK and mesangial cells. Ouabaine sensitive rubidium uptake (Na,K-ATPase activity) was stimulated by 63% with HGF (10 ng/ml) treatment for 16hr in MDCK cells. The results suggest that HGF is produced in the kidney, at least in mesangial cells and works on epithelial cells to stimulate the proliferation and/or to modify cell functions in a paracrine manner.

Animals↗
PubMed1992

Mathematical modeling of fetal splenic growth: use of the Rossavik growth model.

Growth of the fetal spleen has been monitored by measurements of the maximal length (SL), profile circumference (SC), and profile area (SA) of the spleen, from 20 weeks to 41 weeks, menstrual age. Growth curves for these parameters have been determined using a specially developed growth curve model [P = c(t)k + s (t)]. R2 values of 94.3%, 94.9%, and 96.3% were obtained for SL, SC, and SA, respectively. Variability analysis indicated some progressive increase in variability with menstrual age for these three parameters. Variability data were used with the growth curve models to determine standard curves for SL, SC, and SA. These standard curves provide a superior means for evaluating the normal splenic growth in the fetus and for identifying splenic abnormalities in utero.

Embryonic and Fetal Development↗