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Biomedical subjects

K Murata

Publications and source records attributed to K Murata.

At least 73 records · Page 4Linked to original sources
PubMed2001

Predominant inner-half wall thickening of left ventricle is attenuated in dilated cardiomyopathy: an application of tissue Doppler tracking technique.

The importance of the inner half (IH) of the left ventricular (LV) wall has been reported in hearts that contract normally. However, it is difficult to verify this fact in an in vivo human heart with clinical echocardiography. By using a recently developed tissue Doppler tracking technique, we could assess the systolic wall thickening of the IH and outer half (OH) of the LV wall in 11 normal and 7 dilated cardiomyopathic hearts. Percent wall thickening and the fractional contribution of the IH and OH to the transmural wall thickening were calculated. In healthy subjects, percent wall thickening of the IH, OH, and transmural wall of the left ventricle were 75.8% +/- 24.1%, 39.4% +/- 14.4% (P <.001 versus IH), and 57.6% +/- 17.6%, respectively. In patients with dilated cardiomyopathy, those values were 31.3% +/- 17.1%, 31.2% +/- 20.1% (not significant versus IH), and 31.2% +/- 16.5%, respectively. On the other hand, the fractional contributions of the IH and OH were 66.2% +/- 7.7% and 33.8% +/- 7.7% (P &lt.01 versus IH) in healthy subjects and 50.5% +/- 11.8% and 49.5% +/- 11.8% (not significant versus IH) in patients with dilated cardiomyopathy. Specifically, the IH contributed to the transmural wall thickening nearly twice as much as the OH did in healthy subjects, however, the predominance of IH contribution was attenuated in dilated cardiomyopathy. The tissue Doppler tracking technique is useful in assessing the IH and OH LV wall thickening separately in the clinical situation.

Adult↗
PubMed2001

The importance of pulmonary venous flow measurement for evaluating left ventricular end-diastolic pressure in patients with coronary artery disease in the early stage of diastolic dysfunction.

Transmitral flow pattern assessed by pulsed Doppler echocardiography is widely used to evaluate left ventricular end-diastolic pressure (LVEDP). A restrictive mitral flow pattern is well recognized as a finding of severely elevated LVEDP. On the other hand, an abnormal relaxation pattern can be interpreted many ways. For example, some patients who display an abnormal relaxation pattern have a mild impairment of left ventricular (LV) relaxation as a result of aging, and others have severely impaired LV diastolic function. To evaluate LVEDP in patients with abnormal relaxation mitral filling patterns, we studied 55 patients who had coronary artery disease with abnormal relaxation pattern who underwent elective cardiac catheterization. We recorded the transmitral and pulmonary venous flow velocity curves and measured the duration of the mitral A wave (MAd) and pulmonary venous reversal wave during atrial contraction (PAd). Positive correlations were found between PAd and LVEDP (r = 0.65, P <.01) and between PAd-MAd and LVEDP (r = 0.7, P <.0001); however, MAd was not significantly correlated with LVEDP. In conclusion, PAd must be measured for an accurate evaluation of LV end-diastolic pressure in patients with an abnormal relaxation pattern in the transmitral flow velocity curve.

Aged↗
PubMed2001

New method of on-line quantification of regional wall motion with automated segmental motion analysis.

We have recently developed an automated segmental motion analysis (A-SMA) system, based on an automatic "blood-tissue interface" detection technique, to provide real-time and on-line objective echocardiographic segmental wall motion analysis. To assess the feasibility of A-SMA in detecting regional left ventricular (LV) wall motion abnormalities, we performed 2-dimensional echocardiography with A-SMA in 13 healthy subjects, 22 patients with prior myocardial infarction (MI), and 9 with dilated cardiomyopathy (DCM). Midpapillary parasternal short-axis and apical 2- and 4-chamber views were obtained to clearly trace the blood-tissue interface. The LV cavity was then divided into 6 wedge-shaped segments by A-SMA. The area of each segment was calculated automatically throughout a cardiac cycle, and the area changes of each segment were displayed as bar graphs or time-area curves. The systolic fractional area change (FAC), peak ejection rate (PER), and filling rate (PFR) were also calculated with the use of A-SMA. In the control group, a uniform FAC was observed in real time among 6 segments in the short-axis view (60% +/- 10% to 78% +/- 9%), or among 5 segments in either the 2-chamber (59% +/- 12% to 75% +/- 16%) or 4-chamber view (58% +/- 13% to 72% +/- 12%). The variations of FAC, PER, and PFR were obviously decreased in infarct-related regions in the MI group and were globally decreased in the DCM group. We conclude that A-SMA is an objective and time-saving method for assessing regional wall motion abnormalities in real time. This method is a reliable new tool that provides on-line quantification of regional wall motion.

Adult↗
PubMed2001

Compensatory responses of left atrial conduit flow to atrial fibrillation with acute myocardial infarction in a canine model.

The aim of this study was to examine the interaction of acute atrial fibrillation (Af) and acute myocardial infarction (AMI) on left atrial (LA) and left ventricular (LV) filling in atrioventricular (A-V) sequential paced, open chest, anesthetized dogs. Left atrial conduit function was determined from pulmonary venous flow (PVF) and detailed analysis of early diastolic flow with the use of micromanometers and transmitral Doppler echocardiography. We studied 8 dogs with regular ventricular rates to avoid the confounding effect of ventricular arrhythmia in Af. In the control stage, Af increased the diastolic PVF volume to the left atrium compared with that during regular A-V pacing (from 0.58 +/- 0.11 mL/beat to 0.70 +/- 0.13 mL/beat, P <.05), as a compensatory response to the impaired systolic PVF volume (from 0.56 +/- 0.12 mL/beat to 0.41 +/- 0.11 mL/beat, P <.05). As a result, cardiac output was maintained. However, in the AMI stage, Af decreased cardiac output (from 0.95 +/- 0.32 L/min to 0.80 +/- 0.23 L/min, P <.05 versus AMI with A-V pacing), and decreased diastolic PVF volume (from 0.46 +/- 0.13 mL/beat to 0.33 +/- 0.14 mL/beat, P <.05 versus AMI with A-V pacing). These changes were associated with a prolonged LV isovolumic pressure decay rate. Our study demonstrates that Af does not affect cardiac output in the setting of normal LV function at a controlled ventricular rate because enhanced LA conduit flow compensates for impaired LA reservoir function. In contrast, in the setting of AMI, the compensatory response to Af is attenuated because of abnormal LV relaxation, resulting in a decrease in cardiac output.

Animals↗
PubMed2001

Does pleural lavage cytology before thoracic closure predict both patient's prognosis and site of cancer recurrence after resection of esophageal cancer?

BACKGROUND: Operative manipulation occasionally exfoliates and spreads cancer cells in the surgical field, and it is a matter of concern whether the exfoliated cancer cells actually affect the patient's prognosis and sites of cancer recurrence. METHODS: In 240 patients with esophageal cancers, lavage cytology (LC) of the right pleural cavity was performed before and after esophageal resection combined with regional lymphadenectomy. The cytologic results were compared with the pathologic factors associated with cancer extension, postoperative survival, and cause of surgical failure. RESULTS: Only 3 patients (1.3%) were LC positive before resection. Of the 237 LC-negative patients, LC was also negative after resection in 215 patients (90.7%) (LC-/-), but LC became positive after resection in 22 patients (9.3%) (LC-/+). The 3-year survival rate was 0% in the LC-/+ group versus 65% in the LC-/- group, and the median survival rates were 10.9 months and 25.0 months, respectively (P <.0001). Multivariate analysis revealed that LC-/+ was an independent prognostic factor (P =.0331), along with nodal involvement and depth of cancer invasion. However, there were no significant differences in the sites of cancer recurrence between the 2 groups. Only 1 patient was found to develop the first recurrence in the pleural cavity. The LC-/+ group had a higher incidence of bulky lymph-node metastasis (P =.0009). CONCLUSIONS: Pleural LC after resection of esophageal cancer seems to be a prognostic indicator of overall recurrence, but not necessarily in the pleural cavity. Patients with a positive LC after resection may benefit most by effective systemic adjuvant chemotherapy.

Adult↗
PubMed2001

Histopathologic findings of cornea verticillata in a woman heterozygous for Fabry's disease.

PURPOSE: To report the histopathologic findings of the cornea verticillata observed in a woman who was heterozygous for Fabry's disease. METHOD: A 67-year-old woman was found to have a whorl-like corneal opacity on her visit to the Department of Ophthalmology. Aichi Saiseikai Hospital. Her visit was because of a sudden loss of vision in her right eye owing to a central retinal artery occlusion in association with an ophthalmic artery occlusion. The patient died suddenly of an acute heart failure; with family consent, an autopsy was performed and the right eye was removed for histopathologic examination by light and electron microscopy. RESULTS: Low levels of alpha-galactosidase in the leukocytes together with the corneal finding led to the diagnosis of heterozygous Fabry's disease. Light microscopy revealed a 0.3- to 0.5-microm thick layer between the epithelial and Bowman's layers. Oil red O positive deposits were accumulated in the subepithelial layer, and the density varied in different regions. Electron microscopy showed that subepithelial layer differed in thickness, and the basal lamina reduplicated regionally. We were not able to determine the structure that correlated with the "ridge" in the central part of the cornea. CONCLUSION: The oil red O positive deposits and their variation in density in the subepithelial area of the cornea may have caused the characteristic whorl-like corneal opacity in this woman who was heterozygous for Fabry's disease.

Aged↗
PubMed2001

Expression of gp34 (OX40 ligand) and OX40 on human T cell clones.

gp34, which we previously cloned, is a ligand of OX40 (CD134), a costimulatory molecule involved in T cell activation. To elucidate the role of human OX40 / OX40L interaction, we examined the expression of gp34 (OX40L) and OX40 in normal human hematopoietic cells by using flow cytometry. OX40 expression is observed on activated T cells, while OX40L is expressed in antigen-presenting cells. However, cytotoxic T lymphocyte (CTL) clones specific for Epstein-Barr virus (EBV)-transformed autologous lymphoblastic cell lines (LCLs) induced both OX40 and OX40L expression after antigen or T cell receptor (TCR) stimulation. This study suggests a possible function of OX40L / OX40, through T cell-T cell interaction, in the reactivation of memory T cells in an autocrine manner, with implications for the pathogenesis of viral infections and neoplasms.

Antibodies, Monoclonal↗
PubMed2001

Polysaccharide lyase: molecular cloning, sequencing, and overexpression of the xanthan lyase gene of Bacillus sp. strain GL1.

When grown on xanthan as a carbon source, the bacterium Bacillus sp. strain GL1 produces extracellular xanthan lyase (75 kDa), catalyzing the first step of xanthan depolymerization (H. Nankai, W. Hashimoto, H. Miki, S. Kawai, and K. Murata, Appl. Environ. Microbiol. 65:2520-2526, 1999). A gene for the lyase was cloned, and its nucleotide sequence was determined. The gene contained an open reading frame consisting of 2,793 bp coding for a polypeptide with a molecular weight of 99,308. The polypeptide had a signal peptide (2 kDa) consisting of 25 amino acid residues preceding the N-terminal amino acid sequence of the enzyme and exhibited significant homology with hyaluronidase of Streptomyces griseus (identity score, 37.7%). Escherichia coli transformed with the gene without the signal peptide sequence showed a xanthan lyase activity and produced intracellularly a large amount of the enzyme (400 mg/liter of culture) with a molecular mass of 97 kDa. During storage at 4 degrees C, the purified enzyme (97 kDa) from E. coli was converted to a low-molecular-mass (75-kDa) enzyme with properties closely similar to those of the enzyme (75 kDa) from Bacillus sp. strain GL1, specifically in optimum pH and temperature for activity, substrate specificity, and mode of action. Logarithmically growing cells of Bacillus sp. strain GL1 on the medium with xanthan were also found to secrete not only xanthan lyase (75 kDa) but also a 97-kDa protein with the same N-terminal amino acid sequence as that of xanthan lyase (75 kDa). These results suggest that, in Bacillus sp. strain GL1, xanthan lyase is first synthesized as a preproform (99 kDa), secreted as a precursor (97 kDa) by a signal peptide-dependent mechanism, and then processed into a mature form (75 kDa) through excision of a C-terminal protein fragment with a molecular mass of 22 kDa.

Amino Acid Sequence↗
PubMed2001

Genetic immunization of wild-type and hepatitis C virus transgenic mice reveals a hierarchy of cellular immune response and tolerance induction against hepatitis C virus structural proteins.

To study the effect of genetic immunization on transgenic expression of hepatitis C virus (HCV) proteins, we evaluated the immunological response of HCV transgenic mice to HCV expression plasmids. FVB/n transgenic mice expressing HCV structural proteins (core, E1, and E2) and wild-type (WT) FVB/n mice were immunized intramuscularly with plasmids expressing core (pHCVcore) or core/E1/E2 (pHCVSt). After immunization, HCV-specific humoral and cellular immune response was studied. Both WT and transgenic mice immunized with either HCV construct produced antibodies and exhibited T-cell proliferative responses against core or envelope. In WT mice immunized with pHCVSt, cytotoxic T-lymphocyte (CTL) activities were detected against E2 but not against core or E1, whereas strong CTL activities against core could be detected in WT mice immunized with pHCVcore. In pHCVSt-immunized, transgenic mice, CTL activities against the core or envelope were completely absent, but core-specific CTL activities could be detected in pHCVcore-immunized transgenic mice. A similar pattern of immune responses was also observed in other mouse strains, including a transgenic line expressing human HLA-A2.1 molecules (AAD mice). Despite the presence of a peripheral cellular immunity against HCV, no liver pathology or lymphocytic infiltrate was observed in these transgenic mice. Our study suggests a hierarchy of CTL response against the HCV structural proteins (E2 > core > E1) in vivo when the proteins are expressed as a polyprotein. The HCV transgenic mice can be induced by DNA immunization to generate anti-HCV antibodies and anticore CTLs. However, they are tolerant at the CTL level against the E2 protein despite DNA immunization.

Adoptive Transfer↗
PubMed2001

Loss of hippocampal CA3 pyramidal neurons in mice lacking STAM1.

STAM1, a member of the STAM (signal transducing adapter molecule) family, has a unique structure containing a Src homology 3 domain and ITAM (immunoreceptor tyrosine-based activation motif). STAM1 was previously shown to be associated with the Jak2 and Jak3 tyrosine kinases and to be involved in the regulation of intracellular signal transduction mediated by interleukin-2 (IL-2) and granulocyte-macrophage colony-stimulating factor (GM-CSF) in vitro. Here we generated mice lacking STAM1 by using homologous recombination with embryonic stem cells. STAM1(-/-) mice were morphologically indistinguishable from their littermates at birth. However, growth retardation in the third week after birth was observed for the STAM1(-/-) mice. Unexpectedly, despite the absence of STAM1, hematopoietic cells, including T- and B-lymphocyte and other hematopoietic cell populations, developed normally and responded well to several cytokines, including IL-2 and GM-CSF. However, histological analyses revealed the disappearance of hippocampal CA3 pyramidal neurons in STAM1(-/-) mice. Furthermore, we observed that primary hippocampal neurons derived from STAM1(-/-) mice are vulnerable to cell death induced by excitotoxic amino acids or an NO donor. These data suggest that STAM1 is dispensable for cytokine-mediated signaling in lymphocytes but may be involved in the survival of hippocampal CA3 pyramidal neurons.

Adaptor Proteins, Signal Transducing↗
PubMed2001

Loss of neurons in the hippocampus and cerebral cortex of AMSH-deficient mice.

AMSH, a molecule that associates with STAM1, is involved in the in vitro cell growth signaling mediated by interleukin 2 and granulocyte-macrophage colony-stimulating factor. To investigate the in vivo functional role of AMSH, we have generated AMSH-deficient mice by gene targeting. The AMSH-deficient mice were morphologically indistinguishable from their littermates at birth, and histopathological examinations revealed normal morphogenesis in all tissues tested. However, all the AMSH-deficient mice exhibited postnatal growth retardation and died between postnatal day 19 (P19) and P23. Examination of brain sections at P6 demonstrated significant loss of neurons and apoptotic cells in the CA1 subfield of the hippocampus. Brain atrophy developed by P16 and was accompanied by complete loss of the CA1 neurons in the hippocampus and marked atrophy of the cerebral cortex. Furthermore, AMSH-deficient hippocampal neuronal cells were unable to survive in vitro, even in the presence of several stimulatory cytokines, while AMSH-deficient cerebellar neurons, thymocytes, and embryonic fibroblasts survived normally. Taken together, these observations indicate that AMSH is an essential molecule for the survival of neuronal cells in early postnatal mice.

Adaptor Proteins, Signal Transducing↗
PubMed2001

Transient increase in the levels of T-helper 1 cytokines in postmenopausal women and the effects of hormone replacement therapy.

The aim of this study was to determine, at least in part, T-cell function in postmenopausal women and the effects of hormone replacement therapy (HRT). Levels of T-helper 1 (Th1) cytokines (IL-2 and IFN-gamma) and T-helper 2 (Th2) cytokines (IL-4 and IL-10) produced by phytohemagglutinin-stimulated whole blood cells from 72 untreated and 44 HRT-treated women were measured by ELISA. Thirteen of the 44 HRT-treated women were examined before and during HRT. The production of IL-2 increased gradually with advance of the postmenopausal period. The levels of IL-2 in women in the early (< or =10 years) and mid (>10 and <30 years) postmenopausal stages were significantly higher than those in women in their second, third and fourth decades. The level in women in the late (> or =30 years) postmenopausal stage, however, was significantly lower than those in women in the early and mid postmenopausal stages. The level of IFN-gamma was highest in women in the mid postmenopausal stage. On the other hand, the levels of Th2 cytokines did not change with age or after menopause until the mid postmenopausal period but were significantly lower in women in the late postmenopausal stage. IFN-gamma levels in women on HRT were significantly lower than those in untreated postmenopausal women at all postmenopausal stages. HRT induced a significant decrease in the production of IL-2 and IL-4. In conclusion, production of Th1 cytokines is augmented in women after menopause. HRT prevents this increase, thereby improving the aberration of Th1/Th2 balance that is implicated in an inadequate immune response and pathological conditions.

Adolescent↗
PubMed2001

Rat small intestine muscle relaxation alkaloids from Orixa japonica leaves.

Two quinoline alkaloids, japonine (1) and eduline (2) were isolated from the methanol extract of the leaves of Orixa japonica as relaxants against rat small intestine muscle. The activity of these alkaloids was comparable to that of the typical muscle relaxant papaverine (4). This is also the first report of the isolation of eduline (2) from O. japonica.

Alkaloids↗
PubMed2001

Syncope induced by tobacco smoking in the head-up position.

A 26-year-old man had a loss consciousness for a few minutes while smoking in the standing position, and was referred to hospital. No abnormalities were found in a computed tomography examination of his head, in a 24-h electrocardiogram or in an exercise tolerance test. The head-up tilt test (HUT) while tobacco smoking elicited a positive response in the tilted position, but the HUT without tobacco smoking was negative. The most noteworthy effect of tobacco smoking during the HUT was the high level of plasma epinephrine compared to the levels seen during supine smoking or the HUT alone. Syncope induced by tobacco smoking in the standing position is rare and the mechanism may be the same as that underlying neurally mediated syncope.

Adult↗
PubMed2001

Atheromatous plaque in the distal aortic arch creating the potential for cerebral embolism during cardiopulmonary bypass.

The present study evaluated the risk in cardiac patients of rupture of a plaque by a jet stream from the arch cannula. The entire thoracic aorta and cardiac function were routinely monitored by transesophageal echocardiography (TEE) in 88 adult patients who underwent coronary artery bypass surgery. The changes in the atheromatous plaque in the distal aortic arch were observed before and after cardiopulmonary bypass. Of the 88 patients, 13 were found to have preoperative atheromatous plaque at the distal aortic arch and 8 (61.5%) of them suffered plaque rupture caused by jet stream from the arch cannula. Only 1 patient experienced apparent embolic episodes manifesting as cerebral and left leg embolisms; the remaining 7 had no clinical embolic symptoms. In order to prevent atheroembolic events, attention should be paid not only to the ascending aorta, but also to the distal arch and in this regard TEE is useful for detecting atheromatous changes of the aorta.

Aged↗
PubMed2001

Establishment of a mass-production system for NADP using bacterial inorganic polyphosphate/ATP-NAD kinase.

The inorganic polyphosphate/ATP-dependent NAD kinase (Ppnk) of Mycobacterium tuberculosis was applied to the mass-production of NADP from NAD and inorganic polyphosphate (metaphosphate). When Ppnk purified from recombinant Escherichia coli cells overexpressing the M. tuberculosis Ppnk was used, 30 mM (27 g/l) NADP was produced from 50 mM NAD and 100 mg/ml metaphosphate at 37 degrees C and pH 7.0. The recombinant E. coli cells were immobilized in polyacrylamide gel, and treated with acetone to render the cells permeable to substrates and products. When acetone-treated immobilized cells were used, 16 mM (14 g/l) NADP was produced from 50 mM NAD and 100 mg/ml metaphosphate at 37 degrees C and pH 7.0. The isolation of NADP formed in the reaction mixture was easy because of the absence of by-products (ATP degradation compounds), and this NADP production system using purified Ppnk or immobilized recombinant E. coli cells expressing Ppnk is thought to be feasible in the production of NADP on an industrial scale.

Journal Article↗
PubMed2001

Super-channel in bacteria: function and structure of a macromolecule import system mediated by a pit-dependent ABC transporter.

In a soil isolate, Sphingomonas sp. A1, the transport of a macromolecule (alginate: 27 kDa) is mediated by a pit-dependent ATP-binding cassette (ABC) transporter. The transporter is different from other ABC transporters so far analyzed in that its function is dependent on the pit, a mouth-like organ formed on the cell surface only when the cells are compelled to assimilate macromolecules, and in that it allows direct import of macromolecules into cells. The ABC transporter coupled with the pit, which functions as a funnel and/or concentrator of macromolecules to be imported, was designated as the "Super-channel", and in this review, we discuss the three-dimensional structure and specific function of the "Super-channel" for macromolecule import found for the first time in a bacterium.

ATP-Binding Cassette Transporters↗