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Biomedical subjects

K Yamabe

Publications and source records attributed to K Yamabe.

At least 19 recordsLinked to original sources
PubMed2004

[Case of systolic anterior motion of mitral valve after mitral valve repair].

A 56-year-old woman was underwent mitral valve repair for prolapse of the posterior mitral leaflet. Intraoperative transesophageal echocardiography (TEE) showed systolic anterior motion (SAM) of the mitral valve at the weaning from cardiopulmonary bypass (CPB). Sliding technique was easily performed at the second pump run. Intraoperative TEE demonstrated no SAM or residual mitral regurgitation after the second pump run.

Cardiac Surgical Procedures↗
PubMed2002

Sequential variation of groundwater quality in an agricultural area with greenhouses near the coast.

The quality of coastal groundwater utilized for greenhouse-farming is liable to be affected by not only fertilization practices but also seawater intrusion into the aquifer. In this study, the sequential variations of groundwater quality and the mechanisms of its pollution processes were analyzed through successive field measurements from June 2000 to May 2001 in such a coastal agricultural area located in Kochi prefecture, Japan. The analysis revealed that the ions for NO3-, SO4(2-), Mg2+ and Ca2+ in the groundwater originated primarily from the ground surface due to the seasonal flooding activities. It was also estimated that denitrification occurred at three well points, and the rate constants were 0.010, 0.019 and 0.089 d-1, respectively. Na+, Mg2+ and Ca2+ concentrations in the groundwater governed by seawater intrusion phenomena showed strong correlations with the concentration of Cl- by excluding the influence of fertilizer. Cation exchange phenomena between Ca2+ and Na+ and as well as the mixing with seawater had a considerable effect on the groundwater quality.

Agriculture↗
PubMed2002

[Resection for pulmonary metastasis of gastrointestinal stromal tumor of the stomach at 10 years after gastrectomy; report of a case].

A 70-years-old male, who had received gastrectomy for leiomyosarcoma of the stomach 10 years ago, was found to have a left lung tumor on chest X-ray and computed tomography (CT). The tumor was diagnosed to be a pulmonary metastasis of gastric leiomyosarcoma. On admission, another tumor was detected at left occipital region by brain CT and was thought to be meningioma. Left lower lobectomy and brain tumor resection were performed serially. The histologic and immunohistochemical findings showed that both tumors were metastases of gastrointestinal stromal tumor (GIST) of the stomach after long disease-free interval. Compared with the primary tumor, cellular density, mitotic figures, bizarre nuclei, and necrotic foci were prominent in the metastatic tumors. This case suggest that GIST may recurrent as pulmonary metastasis after long disease-free interval and should be follow up longer after resection. Patient prognosis with pulmonary metastases is considered to be reflected more exactly in biological malignant potential of metastatic tumor rather than that of primary tumor.

Aged↗
PubMed2002

Quantitative assessment of harmonic power Doppler myocardial perfusion imaging with intravenous Levovist in patients with myocardial infarction: comparison with myocardial viability evaluated by thallium-201 single-photon emission computed tomography and coronary flow reserve.

BACKGROUND: Intravenous myocardial contrast echocardiography with harmonic power Doppler imaging is a novel technique for assessing myocardial perfusion. AIMS: The aim of this study was to quantitatively assess myocardial perfusion by harmonic power Doppler imaging in patients with a previous myocardial infarction and compare myocardial contrast echocardiography results with myocardial viability evaluated by thallium-201 single-photon emission computed tomography ((201)Tl-SPECT) and the results of Doppler flow measurement of coronary flow velocity reserve. METHODS: Twenty-three patients with anterior myocardial infarction who were scheduled for adenosine stress (201)Tl-SPECT underwent myocardial contrast echocardiography with harmonic power Doppler imaging. Harmonic power Doppler imaging was performed at rest and during adenosine infusion (0.15 mg/kg/min) using an intravenous infusion of Levovist. The peak colour pixel intensity ratios of the risk area to the control area were used for quantitative analysis of myocardial perfusion by harmonic power Doppler imaging. Coronary blood flow velocity was measured using Doppler-tipped guidewire in the distal portion of left anterior descending artery and coronary flow velocity reserve was calculated. RESULTS: In patients with myocardial viability assessed by (201)Tl-SPECT, pixel intensity ratios both at rest and during hyperaemia were significantly higher compared with those in patients without myocardial viability (at rest: 0.62 +/- 0.28 vs 0.37 +/- 0.17, P=0.038, during hyperaemia 0.72 +/- 0.19 vs 0.40 +/- 0.18, P=0.003). Coronary flow velocity reserve was significantly different between two groups (2.35 +/- 0.43 vs 1.49 +/- 0.53, P <0.01). CONCLUSIONS: Quantitative assessment of microvascular integrity by harmonic power Doppler imaging corresponds to the evaluation of the microcirculation by coronary flow velocity reserve.

Adenosine↗
PubMed2001

Spinal cord lesions of myelitis with hyperIgEemia and mite antigen specific IgE (atopic myelitis) manifest eosinophilic inflammation.

We report the neuropathological findings of spinal cord specimens obtained from two patients who had localized myelitis with hyperIgEemia and mite antigen specific IgE (atopic myelitis). Both cases showed mild spinal cord dysfunction, and the gadolinium-enhanced area of the isolated spinal cord lesion observed on MRI was biopsied, respectively. Neuropathologically, both cases showed many perivascular lymphocyte cuffings associated with disrupted vessels, and the infiltration of eosinophils in the spinal cord lesions. Both myelin and axons were lost in the lesions, which were associated with astrogliosis. These findings suggest that an allergic mechanism may play a role in this condition.

Adult↗
PubMed2001

Identification of amino acid residues essential for the substrate specificity of Flavobacterium sp. endo-beta-N-acetylglucosaminidase.

The gene encoding the endo-beta-N-acetylglucosaminidase from Flavobacterium sp. (Endo-Fsp) was sequenced. The Endo-Fsp gene was overexpressed in Escherichia coli cells, and was purified from inclusion bodies after denaturation by 8 M urea. The renatured Endo-Fsp had the same optimum pH and substrate specificity as the native enzyme. Endo-Fsp had 60% sequence identity with the endo-beta-N-acetylglucosaminidase from Streptomyces plicatus (Endo-H), and the putative catalytic residues were conserved. Site-directed mutagenesis was done at conserved residues based on the three-dimensional structure and mutagenesis of Endo-H. The mutant of Glu-128, corresponding to Glu-132 in Endo-H and identified as an active site residue, was inactivated. Mutagenesis around the predicted active site of Endo-Fsp reduced the enzymatic activity. Moreover, the hydrolytic activity toward hybrid-type oligosaccharides was decreased compared to that toward high-mannose type oligosaccharides by mutagenesis of Asp-126 and Asp-127. Therefore, site-directed mutagenesis of some of these conserved residues indicates that the predicted active sites are essential to the enzymatic activity of Endo-Fsp, and may have similar roles in catalysis as their counterparts in Endo-H.

Amino Acid Sequence↗
PubMed2001

[Incidence of systolic pulmonary venous flow reversal in patients with mitral valve prolapse: influence of the prolapse site].

OBJECTIVES: Systolic pulmonary venous flow reversal identified by pulsed Doppler echocardiography is useful for the diagnosis of severe mitral regurgitation. The direction of the mitral regurgitant jet in severe mitral regurgitation significantly influences the systolic pulmonary venous flow reversal in an experimental model. This study investigated the influence of the site of mitral valve prolapse on the incidence of systolic pulmonary venous flow reversal in patients with severe mitral regurgitation using transthoracic color Doppler echocardiography. METHODS: This study included 59 consecutive patients with severe mitral regurgitation (regurgitant fraction > 50%) due to mitral valve prolapse. Exclusion criteria were left ventricular ejection fraction < 45%, non sinus rhythms, associated aortic valve disease, bileaflet prolapse, and inadequate Doppler recordings. Right upper pulmonary venous flow was recorded and regurgitant fraction of mitral regurgitation measured by transthoracic color Doppler echocardiography. The sites of mitral valve prolapse were confirmed at operation in all patients. RESULTS: The incidence of systolic pulmonary venous flow reversal was 78% (14/18) in the patients with anterior leaflet prolapse, 82% (9/11) in the patients with medial commissure prolapse, 75% (12/16) in the patients with posterior middle scallop prolapse, 20% (2/10) in the patients with posterior medial scallop prolapse, and 25% (1/4) in the patients with posterior lateral scallop prolapse. There were no significant differences in regurgitant fraction between the five groups. The incidence of systolic pulmonary venous flow reversal was significantly lower in the patients with posterior medial scallop prolapse compared to the other sites of mitral valve prolapse (p < 0.01). CONCLUSIONS: Assessment of the severity of mitral regurgitation by systolic pulmonary venous flow reversal using transthoracic color Doppler echocardiography may be underestimated in patients with prolapse of the posterior medial scallop.

Aged↗
PubMed2000

[A case of symptomatic cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL)].

We here report a 42-year-old woman diagnosed cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) by age, family history, neurological findings, and neuro imagings. Magnetic resonance imaging well demonstrated the multiple lesions in the cerebrum including the brain stem, which was characteristic findings in CADASIL.

Adult↗
PubMed1999

Cancer gene therapy using a pro-apoptotic gene, caspase-3.

Caspase-3 is a member of the cysteine protease family, which plays a crucial role in apoptosis. We applied the human caspase-3 gene as a novel form of anticancer gene therapy. Overexpression of human caspase-3 alone could not induce apoptosis of tumor cell lines, but apoptosis was markedly enhanced by the addition of etoposide. In an AH130 liver tumor model, transduction of human caspase- 3, but not the empty vector, induced extensive apoptosis and reduced tumor volume when combined with etoposide administration. However, this effect was not observed with a Bcl-2 overexpressing tumor. In conclusion, caspase-3 gene transduction accompanied by an additional death stimulus may be a useful method of anticancer gene therapy, except for Bcl-2 overexpressing tumors.

Adenoviridae↗
PubMed1998

Prevention of hypoxic liver cell necrosis by in vivo human bcl-2 gene transfection.

Prevention of hypoxic cell death is a key to successful liver transplantation. We developed a new method for preventing liver hypoxic cell death by introducing an anti-cell death gene directly into rat livers. When the human bcl-2 gene (hbcl-2) was directly transfected into rat livers together with non-histone chromosomal protein high mobility group 1 (HMG1) by the hemagglutinating virus of Japan (Sendai virus; HVJ)-liposome method, human Bcl-2 protein (hBcl-2) was efficiently expressed. Electron microscopy and fluorescence microscopy revealed that hepatocytes expressing exogenous hBcl-2 were almost completely protected the hypoxic cell necrosis. The expression of the hBcl-2 also inhibited activation of caspase-3 (-like) proteases and liver dysfunction. Thus, we conclude that transfection of the hbcl-2 gene through HVJ-liposome method is useful to prevent liver cell necrosis induced by hypoxia. This finding could lead to new strategies to avoid the hypoxic cell death, the major problem in liver transplantation.

Animals↗
PubMed1997

Cloning, sequencing, and expression of Arthrobacter protophormiae endo-beta-N-acetylglucosaminidase in Escherichia coli.

The gene encoding endo-beta-N-acetylglucosaminidase from Arthrobacter protophormiae (Endo-A) was cloned, and its nucleotide sequence was determined. A single open reading frame consisting of 1935 base pairs and encoding a polypeptide composed of signal peptides of 24 amino acids and a mature protein of 621 amino acids was found. The primary structure of Endo-A exhibited significant homology with FO1F.10 gene product from Caenorhabditis elegans and weak homology with peptide-N4-(N-acetyl-beta-D-glucosaminyl)asparagine amidase from Flavobacterium meningosepticum and chitinase from Streptomyces olivaceoviridis. However, the enzyme had no significant homology with any previously reported endo-beta-N-acetylglucosaminidases. Transformed Escherichia coli cells carrying the 4.5-kb fragment expressed Endo-A activity. This enzyme activity was detected in the medium as well as in the periplasmic space of cells under the control of the Endo-A gene promoter. The recombinant Endo-A was efficiently isolated from the periplasmic space of the cells. N-terminal sequence analysis revealed that native and recombinant Endo-A have the same N-terminus. Recombinant and native Endo-A also showed very similar optimum pH profiles and transglycosylation activity.

Amino Acid Sequence↗
PubMed1996

Induction of apoptosis as well as necrosis by hypoxia and predominant prevention of apoptosis by Bcl-2 and Bcl-XL.

The molecular mechanism of cell death due to hypoxia has not been elucidated. Our recent observations that overexpression of the anti-apoptotic proto-oncogene bcl-2 and a bcl-2-related gene, bcl-x, prevents hypoxic cell death suggest that hypoxia induces apoptosis. Using electron microscopy and confocal and nonconfocal fluorescence microscopy, we show here that hypoxia does, in fact, induce both necrosis and apoptosis, and that the proportion of these two modes is highly dependent on the cell type. Overexpression of Bcl-2 or Bcl-Xl blocks hypoxia-induced apoptosis in a dose-dependent manner.

Animals↗
PubMed1996

Purification of a phenobarbital-inducible UDP-glucuronosyltransferase isoform from dog liver which catalyzes morphine and testosterone glucuronidation.

A morphine UDP-glucuronosyltransferase (UGT) which could belong to the UGT2B subfamily was isolated from liver microsomes of a male beagle dog treated with phenobarbital. Glucuronidation toward morphine in the dog liver microsomes was increased threefold by the treatment. The microsomes were solubilized with Emulgen 911 and applied on a column of hemisuccinate derivative of Sepharose 4B column which has been developed in our laboratory. An isoform of UGT in the eluate was purified further by chromatofocusing and UDP-hexanolamine-affinity chromatography. A purified enzyme, UGTDOG-PB, was homogeneous on sodium dodecyl sulfate polyacrylamide gel electrophoresis and two-dimensional electrophoresis and exhibited a subunit molecular weight of 50 kDa. This isoform showed activities toward the 3-hydroxyl group of morphine, 4-hydroxybiphenyl, 4-nitrophenol, 4-methylumbelliferone, and testosterone, but not toward chloramphenicol and the 6-hydroxyl group of morphine. The substrate specificity of UGTDOG-PB is similar to that of stably expressed UGT2B1 which is considered a phenobarbital-inducible morphine UGT in the rat except that UGTDOG-PB is capable of glucuronidating 4-nitrophenol but not chloramphenicol. The NH2-terminus until the 30th residue of UGTDOG-PB is highly homologous to UGT2B subfamily, and the NH2-terminal 15 residues of UGTDOG-PB are completely identical to those of UGT2B1, UGT2B8, and UGT2B15. This is the first report describing the UGT isoform of dog and the purification of morphine UGT which may belong to UGT2B subfamily.

Amino Acid Sequence↗
PubMed1996

Immunocytochemical localization of heme oxygenase-2 in the rat cerebellum.

Carbon monoxide (CO) is a gas that can permeate biological membranes and it has been suggested that the gas plays a signaling role in the brain by activating soluble guanylyl cyclase (sGC). CO is generated by heme oxygenase during the conversion of heme to biliverdin. In this study, we raised an antiserum against the chemically synthesized amino-terminal fragment of heme oxygenase-2 (HO-2) and studied the distribution of this enzyme in the rat cerebellum by an immunocytochemical method. Immunoreactivity specific for HO-2 was observed only in neurons. In the Purkinje cells and the basket cells of the cerebellum, immunoreactivity was detected in the dendrites and the somata but not in the axon terminals, suggesting that CO might be liberated primarily from the dendrites and somata rather than from the axons in this region of the rat brain.

Amino Acid Sequence↗
PubMed1996

[Improved method of staining RNA in platelets for the evaluation of platelet production in thrombocytopenic patients].

Measurement of RNA stained platelets was proven to be an easy and useful laboratory test to evaluate the state of platelet production in the bone marrow. As the normal value of RNA stained platelet with thiazole orange(TO) in the original method was low, the values of TO-stained platelets in the cases with platelet hypoproduction were within the normal range, but ideally, they should be below the normal range. We modified the original method 1) by using sodium citrate as the anticoagulant instead of EDTA, and 2) by keeping the TO-stained preparation at 4 degrees C until the fluorescence was measured. The normal value of TO-stained platelets was elevated to 22.5 +/- 3.3% (n = 40, M +/- 1SD) or 54 +/- 10 x 10(9)/1. Twenty-seven out of 40 thrombocytopenic case with ITP showed an elevated percentage of TO-stained platelets, 11 cases showed a normal and only 2 cases showed a percentage lower than normal. By contrast, 9 out of 12 cases with platelet hypoproduction showed a lower percentage of TO-stained platelets and no cases showed a value higher than normal. The sensitivity and specificity of this modified RNA staining method for distinguishing thrombocytopenic cases with platelet hyperdestruction from that with hypoproduction were 96% and 75%, respectively.

Adult↗