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Biomedical subjects

K Murata

Publications and source records attributed to K Murata.

At least 55 records · Page 3Linked to original sources
PubMed2001

Asymmetric arrangement of auxiliary subunits of skeletal muscle voltage-gated l-type Ca(2+) channel.

Highly purified L-type Ca(2+) channel complexes containing all five subunits (alpha(1), alpha(2), beta, gamma, and delta) and complexes of alpha(1)-beta subunits were obtained from skeletal muscle triad membranes by three-step purification and by 1% Triton X-100 treatment, respectively. Their structures and the subunit arrangements were analyzed by electron microscopy. Projection images of negatively stained Ca(2+) channels and alpha(1)-beta complexes were aligned, classified and averaged. The alpha(1)-beta complex showed a hollow trapezoid shape of 12 nm height. In top view, four asymmetric domains surrounded a central depression predicted to form the channel pore. The complete Ca(2+) channel complex exhibited the cylindrical shape of 20 nm in height binding a spherical domain on one edge. Further image analysis of higher complexes of the Ca(2+) channel using a monoclonal antibody against the beta subunit showed that the alpha(1)-beta complex forms the non-decorated side of the cylinder, which can traverse the membrane from outside the cell to the cytoplasm. Based on these results, we propose that the Ca(2+) channel exhibits an asymmetric arrangement of auxiliary subunits.

Animals↗
PubMed2001

Crystal structure of alginate lyase A1-III complexed with trisaccharide product at 2.0 A resolution.

The structure of A1-III from a Sphingomonas species A1 complexed with a trisaccharide product (4-deoxy-l-erythro-hex-4-enepyranosyluronate-mannuronate-mannuronic acid) was determined by X-ray crystallography at 2.0 A with an R-factor of 0.16. The final model of the complex form comprising 351 amino acid residues, 245 water molecules, one sulfate ion and one trisaccharide product exhibited a C(alpha) r.m.s.d. value of 0.154 A with the reported apo form of the enzyme. The trisaccharide was bound in the active cleft at subsites -3 approximately -1 from the non-reducing end by forming several hydrogen bonds and van der Waals interactions with protein atoms. The catalytic residue was estimated to be Tyr246, which existed between subsites -1 and +1 based on a mannuronic acid model oriented at subsite +1.

Binding Sites↗
PubMed2001

Molecular cloning and characterization of a zinc finger protein involved in Id-1-stimulated mammary epithelial cell growth.

Id proteins are dominant negative regulators of basic helix-loop-helix transcription factors. Previous work in our laboratory has shown that constitutive expression of Id-1 in SCp2 mouse mammary epithelial cells inhibits their differentiation and induces proliferation, invasion, and migration. Id-1 expression also correlates with the invasive and aggressive potential of human breast cancer cells. However, little is known about Id-1 target genes that are important for regulating normal and transformed breast epithelial cell phenotypes. Now we report the cloning of a novel zinc finger protein, Zfp289, using degenerate primers to specifically amplify cDNAs from Id-1-transfected SCp2 cells. Zfp289 has homology with a yeast zinc finger protein, the GTPase-activating protein Gcs-1, which was initially identified as a gene required for the re-entry of cells into the cell cycle after stationary phase growth. Zfp289 mRNA expression pattern correlates with Id-1 expression in SCp2 mammary epithelial cells under various experimental conditions as well as in the mouse mammary gland at different stages of development. It is predominantly present in the cytoplasm of the cells as evident from green fluorescent protein fusion protein localization. SCp2 mammary epithelial cells with constitutive expression of Zfp289 have a higher S-phase index, compared with control cells, when cultured in a serum-free medium. We conclude that the novel zinc finger protein Zfp289, which may represent the mammalian homologue of Gcs-1, is potentially an important mediator of the Id-1-induced proliferation pathway in mammary epithelial cells.

Amino Acid Sequence↗
PubMed2001

Intervention for prevention of low back pain in Japanese forklift workers.

BACKGROUND: The effectiveness of two different approaches for the prevention of low back pain (LBP) was compared in forklift workers. The first approach (personal) consisted of providing lumbar support, arctic jacket and physical exercise, and the second (facility approach) included the improvement of forklift seats and tires. METHODS: The self-reported prevalence of LBP was surveyed three times before and after the two forms of interventions, in 260 male blue-collar workers including 27 forklift workers, and 55 male white-collar workers of a copper smelter. RESULTS: The initial prevalence of LBP was 63% in the forklift workers, which was significantly higher than that found in the other blue-collar workers (32%) and in the white-collar workers (22%). One year after the first intervention (personal approach) to the forklift workers, the prevalence of LBP fell to 56%. The second intervention (facility approach), which was mainly comprised of a reduction in whole body vibration, was subsequently added, and 9 months later the prevalence of LBP in the forklift workers further decreased to 33%. The reduction of the prevalence from the initial survey was significant (P = 0.008), and that from the second survey was nearly significant (P = 0.070). CONCLUSIONS: These findings suggest that the facility approach is more effective for a reduction of LBP than the personal approach.

Adolescent↗
PubMed2001

Endoscopic transanal decompression with a drainage tube for acute colonic obstruction: clinical aspects of preoperative treatment.

PURPOSE: The study was undertaken to evaluate the clinical usefulness of endoscopic transanal decompression with a newly developed drainage tube for the treatment of acute colonic obstruction. METHODS: Thirty-six patients ranging in age from 46 to 87 years (average age = 69 years) with acute colorectal obstruction secondary to carcinoma were treated by means of intubation with a flexible drainage tube using combined endoscopic and fluoroscopic guidance. After tube placement, the obstructed colon was aspirated, decompressed, and cleaned with a 50 ml syringe and saline solution. The drainage tube was kept inserted and the colon was irrigated two or three times per day using 500 to 1,000 ml of saline until there were no contents in the colon. The colon was almost empty at the time of operation. The success rate, benefits, and complications of this technique were evaluated. RESULTS: Placement of the drainage tube was successful in 34 (94.4 percent) of 36 patients. Immediately after aspiration and decompression, symptoms related to obstruction were relieved in 21 patients (61.8 percent), within one hour in 9 patients (26.5 percent) and within four hours in 4 patients (11.8 percent). All 34 patients had elective single-stage surgery without severe complications at the anastomotic site such as anastomotic leakage and postanastomotic stenosis that needed treatment a few days after placement of the drainage tube. In the two cases of unsuccessful placement of the drainage tube, emergent colostomy was performed. CONCLUSION: Decompression with a transanal drainage tube is an easy and safe technique to relieve colonic obstruction effectively without any excess burden to patients. Because the procedure permits single-stage surgery in most cases, it is also cost effective.

Acute Disease↗
PubMed2001

Focal eosinophilic myositis.

Idiopathic hypereosinophilic syndrome (HES) is a heterogeneous group of disorders with the common features of prolonged eosinophilia of underdetermined cause and multiple organ system dysfunction. Focal eosinophilic myositis is an uncommon manifestation of HES. We report a case of focal eosinophilic myositis with tender muscle swelling followed by proximal weakness, but without non-systemic symptoms and muscle trophism in the lower limbs. Muscle biopsy specimen showed acute myositis with eosinophil infiltration. Electromyographic features were typical of myositis. The clinical and biochemical response to corticosteroids was excellent, and a relapse that occurred because the steroid dose was not lowered, responded well.

Adult↗
PubMed2001

Auditory threshold reduction on alcohol ingestion.

RATIONALE: Auditory threshold (AT) measurement method has become the standard behavioral procedure for describing auditory sensitivity. Therefore, the AT measurement method is applicable to evaluation of auditory function. However, only a few studies have been performed to clarify the alteration of audibility under the influence of alcohol on normal humans by measurement of AT. OBJECTIVE: The fact that blood alcohol concentration (BAC) is influenced by the dose of alcohol and the time of measurement suggests that the effects of alcohol may also be altered by the same factors. The present study was conducted to elucidate how alcohol ingestion method affects the AT at a wider range from lower to higher frequency in the time course. METHODS: Fifteen paid Japanese (seven men and eight women, 20-33 years of age) were employed in AT measurements at an octave frequency ranging from 250 to 8,000 Hz before and 5, 30, 60, 120, 240 and 480 min after drinking various amounts (125, 250, 500 and 1,500 ml) of normal beer (5% alcohol) or alcohol-free beer. RESULTS: The AT was significantly reduced within 30 min after the ingestion of 250 and 500 ml of beer, occurring on and after peak BAC. The reducing effect disappeared 480 min after ingestion. CONCLUSIONS: Drinking extra small amounts of alcohol induces the reduction of AT. The effect of alcohol on AT is altered by the alcoholic dose used in testing.

Adult↗
PubMed2001

Impairment of chest wall mechanics and increased chest wall work of breathing cause postoperative respiratory failure in patients who have undergone radical esophagectomy.

PURPOSE: We verified the hypothesis that impairment of chest wall mechanics would be related to the cause of postoperative respiratory failure in patients undergoing radical esophagectomy. METHODS: A total of 21 patients were studied. After management with mechanical ventilation to prevent respiratory failure for several days, trial weaning from the ventilator was performed. The patients were divided into a successful weaning group (S group) and an unsuccessful weaning group (US group), depending on the results of the weaning trial. We compared respiratory mechanics and the respiratory work of breathing during weaning from the ventilator between the two groups. RESULTS: In the US group, lung and chest wall compliance was significantly lower and the development of intrinsic positive end-expiratory pressure (PEEPi) was observed. The work of breathing and the oxygen cost of breathing were significantly higher in the US group. The increased respiratory energy work was due to a moderate increase in lung work and a significant increase in chest wall work. CONCLUSION: Our results suggested that postoperative respiratory failure was related to increased respiratory energy expenditure, significantly deteriorated chest wall mechanics, and increased chest wall work, all of which are involved in the development of postoperative respiratory failure after radical esophagectomy.

Journal Article↗
PubMed2001

Morphological and functional differentiation of human thyroid cells in collagen gel culture.

OBJECTIVE: Cultured human thyroid cells in collagen gel culture were examined on cell morphology and the production of thyroglobulin (Tg), triiodothyronine (T3) and thyroxine (T4) which are components of functional differentiation. METHODS: Thyroid cells obtained from normal human thyroid tissues (four cases), follicular adenoma tissues (three cases), papillary carcinoma tissues (three cases), and follicular carcinoma tissue (one case), were cultured in collagen gel. Then these cultured cells were observed on cellular morphology and production of Tg, T3 and T4. Moreover, changes in morphological characteristics and production of Tg, T3 and T4 induced by addition of thyroid stimulating hormone (TSH) and epidermal growth factor (EGF) to medium in collagen gel culture were determined. RESULTS: Normal and tumor cells in collagen gel culture formed colonies and follicles with Tg production, similar to in vivo-like three-dimensional cellular structures and functions. Normal thyroid cells stimulated TSH induced more Tg and produced morphological changes, i.e. enlarged follicular lumens and increased the height of follicular cells, but did not promote cell proliferation. Reversely, normal thyroid cells stimulated with EGF promoted cell proliferation, but did not change morphological findings and did not increase production of Tg, T3 and T4. CONCLUSIONS: These findings suggest that collagen gel culture is useful for observing the effects of stimulation by cell growth factor on the morphological and functional differentiation of human thyroid cells.

Cell Differentiation↗
PubMed2001

Detection of early venous filling in gliomas on MRI: preliminary study by 2D time-resolved dynamic contrast-enhanced MR angiography with echo-sharing technique.

We evaluated the detection of early venous filling of gliomas by 2D time resolved dynamic contrast enhanced MR digital subtraction angiography (MR-DSA) with echo-sharing technique and compared the results with those of conventional contrast digital subtraction angiography (C-DSA). C-DSA and MR-DSA examinations were performed in eight patients with malignant gliomas and compared with regard to the visualization of early filling veins; time intensity curves of arteries, early filling veins and normal veins were made, and rise time and time to peak were evaluated. MR-DSA visualized 12 out of 17 early filling veins depicted on C-DSA. The failure of five veins to be depicted may be due to the overlapping of other structures, such as other vessels and tumor stain. On time intensity curves, the mean difference in rise time was 0.9 sec between the artery and early filling vein, and the mean difference of time to peak was 1.6 sec. C-DSA has been the modality of choice in demonstrating early venous filling, a useful finding in the differential diagnosis of gliomas. However the high temporal resolution of MR-DSA with echo-sharing technique provides sufficient visualization of early venous filling of gliomas. Additional information for precise differential diagnosis may be obtained by adding MR-DSA to the imaging protocol for gliomas.

Aged↗
PubMed2001

Improvement of afterload mismatch of left atrial booster pump function with positive inotropic agent.

OBJECTIVES: The objective of this study was to examine the hypothesis that a positive inotropic agent improves left ventricular (LV) filling during left atrial (LA) contraction in the presence of markedly elevated LV filling pressure. BACKGROUND: In patients with old myocardial infarction (MI), an increase in the operational LV chamber stiffness reduces LV filling during the LA contraction, resulting from an "afterload mismatch" of the LA booster pump function. METHODS: We investigated the effect of dobutamine infusion (3 microg/kg/min) on the LA pump function in the presence of elevated LV filling pressure induced by aortic constriction (Aoc) during acute MI in 10 dogs. Transmitral flow velocity was determined by transesophageal echocardiography, LV pressure by a micromanometer and LV volume by a conductance catheter. We measured the early (E) and late (A) diastolic peak transmitral flow velocities (cm/s) and LV chamber stiffness (deltaP/deltaV: mm Hg/ml; where deltaP is developed pressure and deltaV is the absolute filling volume during LA contraction). RESULTS: When the deltaP/deltaV was increased by Aoc during MI (from 1.1 +/- 0.8 to 3.1 +/- 2.6 mm Hg/ml, p < 0.01), A decreased significantly (from 30 +/- 5 to 22 +/- 8 cm/s, p < 0.01), and the ratio of E to A increased (from 1.0 +/- 0.3 to 1.4 +/- 0.8, p < 0.05) compared with MI without Aoc, showing the pseudonormal transmitral flow pattern, the so called "LA afterload mismatch." Dobutamine under this condition significantly reduced the deltaP/deltaV (to 1.7 +/- 1.2 mm Hg/ml, p < 0.05), resulting in an increase in A (to 31 +/- 8 cm/s, p < 0.01) and a decrease in E/A (to 1.0 +/- 0.3, p < 0.05), and the transmitral flow became a prolonged relaxation pattern as in MI without Aoc in all dogs. There was an inverse correlation between the deltaP/deltaV and the time-velocity integral of A (r = -0.70, p < 0.01). CONCLUSIONS: Dobutamine improved the afterload mismatch of the LA booster pump function. This effect may have been due to the reduction in LV operational chamber stiffness, resulting in an increase in the LA forward ejection into the LV.

Animals↗
PubMed2001

Molecular characterization of Escherichia coli NAD kinase.

NAD kinase was purified to homogeneity from Escherichia coli MG1655. The enzyme was a hexamer consisting of 30 kDa subunits and utilized ATP or other nucleoside triphosphates as phosphoryl donors for the phosphorylation of NAD, most efficiently at pH 7.5 and 60 degrees C. The enzyme could not use inorganic polyphosphates as phosphoryl donors and was designated as ATP-NAD kinase. The N-terminal amino-acid sequence of the purified enzyme was encoded by yfjB, which had been deposited as a gene of unknown function in the E. coli whole genomic DNA sequence database. yfjB was cloned and expressed in E. coli BL21(DE3)pLysS. The purified product (YfjB) showed NAD kinase activity, and was identical to ATP-NAD kinase purified from E. coli MG1655 in molecular structure and other enzymatic properties. The deduced amino-acid sequence of YfjB exhibited homology with that of Mycobacterium tuberculosis inorganic polyphosphate/ATP-NAD kinase [Kawai, S., Mori, S., Mukai, T., Suzuki, S., Hashimoto, W., Takeshi, Y. & Murata, K. (2000) Biochem. Biophys. Res. Commun. 276, 57-63], and those of many hypothetical proteins for which functions have not yet been revealed. The YfjB homologues were considered to be NAD kinases and alignment of their sequences revealed highly conserved regions, XXX-XGGDG-XL and DGXXX-TPTGSTAY, where X represents a hydrophobic amino-acid residue.

Adenosine Triphosphate↗
PubMed2001

A neutrophil elastase inhibitor (ONO-5046) reduces neurologic damage after spinal cord injury in rats.

In view of a cytoprotective effect of elastase inhibitor on chemokine-mediated tissue injury, we examined the neuroprotective effect of ONO-5046, a specific inhibitor of neutrophil elastase, in rats with spinal cord injury. Standardized spinal cord compression markedly increased cytokine-induced neutrophil chemo-attractant (CINC)-1 mRNA and protein. Their increases correlated with neurologic severity of injured rats. Immunohistochemically, CINC-1 protein was detected sequentially in vascular endothelial cells at 4 h, in perivascular neutrophils at 8 h, and in neutrophils infiltrating into cord substance at 12 h. Pretreatment with ONO-5046 (50 mg/kg) markedly ameliorated motor disturbance in injured rats, and reduced CINC-1 protein and mRNA expression. ONO-5046 also significantly reduced the increase of neutrophil accumulation or infiltration estimated by myeloperoxidase activity, and the extent of vascular permeability by Evans blue extravasation in the injured cord segment in comparison to control animals receiving vehicle. These results suggest that CINC-1 contributed to inflammation in rat spinal cord injury and ONO-5046 attenuated neurologic damage partly by blocking CINC-1 production of the chemoattractant, preventing neutrophil activation and vascular endothelial cell injury.

Animals↗
PubMed2001

Hepatitis C virus-like particles induce virus-specific humoral and cellular immune responses in mice.

We have recently described the production of hepatitis C virus-like particles (HCV-LPs) in insect cells that resemble the putative virions. Here we evaluate the humoral and cellular immunogenicity of the virus-like particles with or without viral p7 protein, a small viral polypeptide that resides between the structural and nonstructural regions of the HCV polyprotein and whose function has not been defined. Immunized BALB/c mice developed high titers of anti-E2 antibodies and virus-specific cellular immune responses including cytotoxic T lymphocytes and T helper responses with gamma interferon production. The virus-like particles without p7 generated a higher cellular immune response with a more T(H)1 profile than the particles with p7. Immunization of heat-denatured particles resulted in substantially lower humoral and cellular responses, suggesting that the immunogenicity is strongly dependent on particle formation. Administration of CpG oligonucleotide or cationic lipid 3beta-[N-(N',N'-dimethylaminoethane)carbamoyl]cholesterol (DC-Chol), two potent adjuvants, did not significantly enhance the immunogenicity of HCV-LPs. Our results indicate that HCV-LPs can induce humoral and cellular immune responses and offer a promising approach to vaccine development.

Adjuvants, Immunologic↗
PubMed2001

Clinical application of the reversed pedicled venous flap containing perivenous areolar tissue and/or nerve in the hand.

A reversed pedicled venous flap containing perivenous areolar tissue and/or nerve was used to cover traumatic skin defects of seven fingers in six patients. The series consisted of six men, ranging in age from 20 to 57 years (average: 39 years). The reconstructed sites were four dorsal skin defects and three volar skin defects of the finger. The flap was designed on the dorsum of the hand, in such a way as to place a vein at the centre of the flap and not to involve the dorsal metacarpal artery. The flap contained a dorsal vein, perivenous areolar tissue and fascia of the interosseous muscle. Cutaneous nerves were present in three of the seven flaps. The pedicle of the flap was dissected distally to the finger web space and the flap was transferred to the skin defect. The size of the flap ranged from 1.4x4.5 cm to 6.0x7.0 cm. The average length of the pedicle was 1.6 cm. Skin grafting was needed at the donor site in one case (flap size: 6.0x7.0 cm), but primary closure was possible in the remaining cases. Postoperatively, the largest flap showed superficial necrosis, although it survived. The remaining flaps survived completely. This suggests that in a large flap the skin should be attached to the pedicle to prevent congestion. The flap can be elevated without reference to the dorsal metacarpal artery at the ulnar side of the dorsum of the hand. The flap is an effective option to reconstruct skin defects of the finger, especially the little finger.

Adult↗