PubMed Health⌕ Search

Biomedical subjects

K Asada

Publications and source records attributed to K Asada.

At least 55 records · Page 3Linked to original sources
PubMed1998

Purification and molecular properties of ascorbate peroxidase from bovine eye.

Ascorbate peroxidase (APX) is a hydrogen peroxide-scavenging peroxidase which uses ascorbate (AsA) as the specific electron donor. APX has not been isolated in mammals. Ocular tissue contains AsA at high concentrations, and we detected APX activity in bovine retinal pigment epithelium (RPE) and choroid. We purified APX from bovine RPE and choroid by four chromatographic steps. The purified APX was a monomeric hemoprotein with a molecular mass of 43 kDa. The amino acid sequence of the amino-terminal region of the purified APX showed a high degree of homology to that of plants. The primary product of the APX reaction was identified as the monodehydroascorbate radical. The APX showed high specificity for AsA as an electron donor. This is the first isolation and characterization of APX from mammals, and its role in the protection against active species of oxygen in ocular tissue is discussed.

Amino Acid Sequence↗
PubMed1998

[Removal of the endocardial pacemaker leads--experience with 16 leads in 10 patients].

Recent advances in pacemaker leads have contributed to the improvement of their stability at the anchored sites. However, we sometimes have difficulty in removing them. We have experienced the removal of 16 leads in 10 patients (male: 7, female: 3) in the last 5 years. The age of patients ranged from 48 to 87 years, and the average was 60. The reasons for the removal were as follows; pocket infection in 6 cases, sepsis in 1 case, ischemic skin erosion in 1 case, retained fractured ventricular lead in 1 case, fracture of Accufix atrial lead in 1 case. The methods of removal consisted of using the removal kit, the snare or the basket snare transvenously, direct surgical approach or a combination of them. We used the removal kit alone in 12 electrodes (6 atrial, 6 ventricular), and removal of 5 atrial and 3 ventricular leads were successfully by this method only. The removal of 4 leads by kits alone failed, so that 2 ventricular leads were removed transvenously, one atrial and one ventricular lead were removed surgically, and 1 ventricular lead was left untreated. Finally, we were able to remove 15 of 16 leads (93.3%) successfully. This experience indicates that these interventions should be performed as less invasively as possible, yet we should give an explanation to the patients as to the options we may employ when we have failed in the intended procedure.

Aged↗
PubMed1998

[A case report of infective endocarditis caused by MRSA and characterized by pedicled vegetation on the posterior wall of left atrium].

We report here a case of active infective endocarditis caused by Methicilin-Resistant Staphylococcus aureus (MRSA). A 24-year-old woman was admitted to the Osaka Medical Collage Hospital with continuous fever. After admission, MRSA was detected by blood culture and chemotherapy with Vancomycin was started. However, after 1 week, her condition had not improved. Moreover, a pedicled vegetation on the posterior wall of the left atrium and mitral regurgitation due to prolapse of the anterior leaflet were revealed by transesophageal echocardiography. The vegetation grew to about 2 cm in diameter and prolapsed into the left ventricle during diastole. We performed an early operation although the infection was still active due to its rapid growth and the risk of embolism. There was a large pedicled vegetation on the posterior wall of the left atrium as shown by preoperative echocardiography, but the mitral valve appeared to be intact. Therefore, the vegetation was completely removed and the mitral annulus was plicated by Kay's method to treat the associated mitral regurgitation. Postoperatively, we administered VCM 2 g/day for 24 days. The course was uneventful. The patient was discharged from the hospital on the 31st postoperative day.

Adult↗
PubMed1998

Enhancement of retroviral gene transduction on a dish coated with a cocktail of two different polypeptides: one exhibiting binding activity toward target cells, and the other toward retroviral vectors.

CH-296, a recombinant fragment of human fibronectin (FN) composed of the cell-binding domain (C-domain), heparin-binding domain II (H-domain), and CS1 site, enhances the retrovirus-mediated gene transduction (GT) of hematopoietic stem cells. The RGD sequence in the C-domain is recognized by a variety of cell types through integrin VLA-5, and the LDV sequence in the CS1-site is recognized by integrin VLA-4. Retrovirus particles were also found to bind to the H-domain. Consequently, the CH-296 fragment can enhance GT through binding to both retrovirus particles and target cells that express integrins VLA-5 and/or VLA-4. In this study, we found that the GT efficiency can be maintained at levels comparable to that of CH-271, a FN fragment similar to CH-296 but lacking the CS1 site, when a cocktail of separated functional domains of CH-271 is used. When a dish was coated with a mixture of the C-domain and H-domain (molar ratio, 1:10), the GT efficiency of NIH3T3 cells reached the same level as that of the mother fragment, CH-271. The H-domain in the cocktail can be replaced with other virus-binding components, polylysine, FGF, and the insulin-binding domain of ColV, without the loss of GT efficiency. With other than FN fragments, a cocktail of erythropoietin and polylysine caused higher GT efficiency of Epo-receptor expressing TF-1 cells than in the case of each component alone.

Animals↗
PubMed1998

Properties of the respiratory NAD(P)H dehydrogenase isolated from the cyanobacterium Synechocystis PCC6803.

Activity staining with NADPH-nitroblue tetrazolium after native-PAGE of membrane proteins of Synechocystis PCC6803, solubilized with 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS), revealed four NAD(P)H dehydrogenase (NDH) activities; an NDH complex of the respiratory chain, a ferredoxin NADP+ reductase (FNR), a drgA product which oxidized both NADH and NADPH, and an uncharacterized NADH-specific enzyme. The NDH complex was purified with anion exchange and gel filtration chromatographies. The purified complex had a molecular mass of 376 kDa and was composed of 9 subunits. Western analysis showed that the complex contained the NDH-H subunit, but not NDH-A or B. The enzyme reduced ferricyanide much faster than plastoquinone and used NADPH as its preferred electron donor rather than NADH. The enzymatic activity was inhibited by diphenyleneiodonium chloride and salicylhydroxamic acid, but not by rotenone, p-chloromercuribenzoate, N-ethylmaleimide, flavon, dicumarol, or antimycin A. These results suggest that the purified complex is a hydrophilic subcomplex which contains an NADPH binding site and flavin, and is dissociated from a hydrophobic subcomplex, which contains quinone binding site.

Amino Acid Sequence↗
PubMed1998

Isolation of a novel NAD(P)H-quinone oxidoreductase from the cyanobacterium Synechocystis PCC6803.

A novel NAD(P)H-quinone oxidoreductase (NQR) was isolated from the cyanobacterium Synechocystis PCC6803 by ion-exchange, affinity and gel-filtration chromatographies. Isolated NQR was found to be a drgA gene product that was a homodimer composed of 23-kDa subunits. It showed NAD(P)H-plastoquinone oxidoreductase activity with Km values for NADPH and NADH of 12 and 48 microM, respectively. The activity was inhibited by thiolmodifying reagents, but not by rotenone, amobarbital, salicylhydroxamic acid, dicumarol, flavone, or diphenyleneiodonium chloride. Therefore, the Cys-147 residue is probably involved in the catalytic reaction. The amino acid sequence of the purified NQR had some homology with those of NADH oxidase, NAD(P)H-flavin oxidoreductase, and nitroreductase but did not contain either an adenine-binding motif or a phosphate-binding motif, thus, it is a new type of NQR.

Amino Acid Sequence↗
PubMed1998

Surgical treatment of discrete subaortic stenosis in an adult.

We report on an adult patient with discrete-type subaortic stenosis. A 48-year-old man who had progressed asymptomatically since childhood despite heart murmur was transferred to our hospital. The patient was diagnosed as having severe aortic stenosis with a pressure gradient of 100 mmHg across the aortic valve, associated with a grade II aortic regurgitation. A conventional aortic valve replacement was scheduled. During surgery, the aortic valve was found to be tricuspid but incompetent as a result of shrinking and thickening of the left coronary cusp. A circumferential fibromuscular ridge was observed under the cusps, which corresponded to Kelly's type II discrete subaortic stenosis. Because of the small subaortic area and deformity of the cusp, we performed aortic valve replacement after excision of all cusps and the fibromuscular ridge. Early corrective surgery is recommended for discrete subaortic stenosis to prevention regurgitation progression.

Aortic Valve Stenosis↗
PubMed1997

Right ventricular myxoma: report of a case.

We herein report a 36-year-old man who underwent surgical resection for myxoma. Preoperative two-dimensional echocardiography demonstrated a mass in the right ventricle. Intraoperatively, the tumor was found to derive from an anterior papillary muscle of the tricuspid valve. The tumor was successfully excised and the tricuspid valve was repaired with chordoplasty and annuloplasty. A histopathological examination revealed myxoma and a 2-year follow-up has shown no evidence of recurrence or tricuspid valve regurgitation.

Adult↗
PubMed1997

Chiral analysis of 3-methoxy-4-hydroxyphenylglycol in human urine.

Since 3-methoxy-4-hydroxyphenylglycol (MHPG) is a neutral metabolite from norepinephrine, it will be a diagnostic marker for mental diseases such as depression. For the development of an immunoassay, the natural enantiomer of MHPG would be required to prepare its antigen and to examine the specificity of the antibody. A natural enantiomer synthesized, however, has not been obtained so far. In this paper, we attempted to enantioseparate synthetic DL-MHPG and to assign D-enantiomer from the optical rotation of MHPG purified from human urine, because endogenous norepinephrine occurs as D-enantiomer which should metabolically generate D-MHPG. Enantioseparation conditions were tested using a Ceramospher Chiral RU-1 column (4.6 x 250 mm) at a flow rate of 0.5 ml/min. The resolution was adequate for the analysis and purification of synthetic DL- and the urinary MHPGs using methanol as a mobile phase and the column temperature at 0 degrees C, where DL-MHPG was detected as two peaks. The earlier peak (peak 1) showed (-) optical rotation, while the latter gave (+) optical rotation. After being treated with beta-glucuronidase, the normal human urine was extracted with ethyl acetate and then evaporated to dryness. The residue was suspended in water and the supernatant was analyzed and purified by a reversed phase column with a multi channel detector. A peak corresponding to MHPG was collected and concentrated to dryness. The pooled residues were dissolved in methanol and enantioseparated on the chiral HPLC. The urinary MHPG appeared as a single peak which was corresponded to the earlier peak of DL-MHPG and showing (-) optical rotation. Thus, the urinary MHPG was found to be D-(-)-MHPG. Then the absolute configuration of enantioseparated MHPGs were assigned to each optical rotation, judging from the chemical data and the metabolic pathway of the urinary D-MHPG. These enantiomers will be useful for studying on biochemistry and immunoassay.

Chromatography, High Pressure Liquid↗
PubMed1997

Generation of superoxide anion and localization of CuZn-superoxide dismutase in the vascular tissue of spinach hypocotyls: their association with lignification.

The sites of generations of superoxide anions and hydrogen peroxide in cross sections of hypocotyls from spinach seedlings were located by staining with nitroblue tetrazolium (NBT) and with starch-iodide, respectively. Formazan, produced upon the reduction of NBT by superoxide, was observed mainly in the vascular tissue only in the presence of inhibitors of CuZn-superoxide dismutase (CuZn-SOD), and its formation was suppressed under anaerobic conditions. Thus, NBT was reduced to formazan specifically by the superoxide anions generated in vascular tissue. The reduction of NBT was suppressed by inhibitors of NAD(P)H oxidase, but neither by cyanide nor azide, indicating the involvement of NAD(P)H oxidase in the generation of superoxide anions in the vascular tissue. Starch-I2 complex also was formed in the vascular tissue, but not in the presence of either the CuZn-SOD inhibitor or the NAD(P)H oxidase inhibitor, indicating that the hydrogen peroxide is produced via the catalytic disproportionation with CuZn-SOD of the superoxide generated by NAD(P)H oxidase. Generations of superoxide anions and hydrogen peroxide in the vascular tissue were particularly apparent in the xylem and associated with the sites of distribution of CuZn-SOD as determined by an immunohistochemical method, and also with the location of lignin as determined by the phloroglucin-HCl reaction.

Enzyme Inhibitors↗
PubMed1997

Arthritis and meningitis--the first manifestations of bacterial endocarditis in 2 patients.

We have encountered 2 patients in whom the first manifestations of bacterial endocarditis were arthritis (in 1 case septic arthritis and in the other nonseptic arthritis) and bacterial meningitis. These presentations were followed by acute heart failure due to aortic valve destruction, although the patients showed no significant cardiovascular manifestations on admission. Aortic valve replacement was performed in each case and the patients' postoperative course was comfortable. We would like to emphasize the following points. (1) Arthritis and meningitis are uncommon in patients with bacterial endocarditis. However, it is necessary to consider the possibility of bacterial endocarditis when these clinical manifestations present together. Such a combination can cause rapid valve destruction. When more than 2 rare complications of bacterial endocarditis coexist, surgery should be considered as soon as the definite diagnosis of bacterial endocarditis is established, even if congestive heart failure has not yet developed. (2) Arthritis associated with bacterial endocarditis might be truly septic rather than mediated by circulating immune complexes as is commonly believed.

Aged↗
PubMed1997

[Effect of aprotinin on bleeding during and graft patency after coronary artery bypass grafting].

The purpose of this study was to evaluate the effect of aprotinin on intraoperative bleeding and graft patency in 200 patients undergoing elective CABG. Patients were classified into three groups; patients receiving 1500000 KIU of aprotinin (group A), 300000 KIU of aprotinin (group B) and no aprotinin as the control (group C). The groups were almost the same as to age, sex, number of grafts and use of ITA. Intraoperative bleeding and reexploration were significantly decreased in group A compared with group B and C. All patients underwent coronary angiography between the 4th and 8th post-operative weeks. Graft patency was significantly decreased in group A (SVG: 90.4%, ITA: 91.1%) compared with group B (SVG: 95.3%, ITA: 100%) and C (SVG: 95.5%, ITA: 99.2%). Perioperative myocardial infarction increased in group A (3.7%). Aprotinin was effective in reducing intraoperative bleeding in CABG, but decreased early graft patency after CABG. It is suggested that aprotinin should not be used routinely in CABG unless a patient has bleeding tendency which is likely to be seen in emergency and redo surgery.

Aged↗
PubMed1997

[A case of mobile left atrial thrombus without mitral valve disease].

A 70-year-old woman who had a left atrial thrombus without mitral valve disease was reported. On admission her electrocardiogram showed atrial fibrillation, but there was no cardiac murmur. Transthoracic echocardiogram revealed a dilated left atrium and an intact mitral valve, but did not detect any thrombus. Transesophageal echocardiogram, however, demonstrated the thrombus attaching to the left atrial appendage. Removal of the thrombus and maze procedure were performed at the same time. Although a pacemaker (DDDR mode) was required postoperatively, she spends uneventful daily life at two years after the surgery.

Aged↗
PubMed1997

[A case report of emergency mitral valve replacement for infective endocarditis in pregnancy].

Infective endocarditis is extremely rare in early pregnancy. We report an emergency mitral valve replacement performed successfully on a 16 week pregnant woman for infective endocarditis without preexisting heart disease. On admission, the patient was in acute heart failure, and the fetus had been already dead. Induced abortion was performed uneventfully 6 days after the cardiac operation.

Adult↗
PubMed1997

[A case of Jehovah's Witness underwent double valves replacement in reoperation].

The patient was a sixty five-year-old woman and Jehovah's Witness who refused either homologous or autologous blood transfusion on the ground of her faith. At the age of 47, she had closed commissurotomy for mitral valve stenosis. This time, because mitral valve restenosis and tricuspid valve regurgitation were found, double valve replacement, mitral and tricuspid, was performed on her, with an excellent result. It is expected that, in the near future, the indication for open heart surgery without blood transfusion will be increased by means of the following considerations as to blood loss preservation; 1. to shorten the time necessitating for an operation and reduce preoperative blood loss, 2. to improve cardio-pulmonary bypass system (Heparin coating etc), and 3. to augment the erythropoiesis (administration of EPO at the patient's own expense, etc.) and so on.

Aged↗
PubMed1997

[A case of dyskeratosis congenita with acute interstitial pneumonia].

This is a rare case of Dyskeratosis Congenita (DC) with acute interstitial pneumonia. A 51-year-old man with DC was admitted to our hospital because of cough, sputum and fever. Chest X-ray film showed ground glass opacities in all lung fields for a while steroid's therapy proved effective, but about seven months later the patient's condition became serious. Methylprednisolone, cyclophosphamide and mechanical ventilation therapy were not effective. He died and an autopsy was performed. The lung specimen showed Organizing Diffuse Alveolar Damage, and some parts pointed to bacterial infection. But Pneumocystic carinii pneumonia and Fungal infections were not found. It is therefore necessary to conduct intensive examinations of lung involvement of patients with Dyskeratosis Congenita.

Acute Disease↗
PubMed1997

[Open heart surgery in a Jehovah's Witness boy--a case report of successful management of aortic regurgatation and aneurysm of sinus Valsalva due to infective endocarditis].

Jehovah's Witness who require operation represent a challenge to the physician because of the patients' refusal to accept blood transfusion. We report an 8-year-old male of Jehovah's Witness who underwent a surgical treatment of infective endocarditis. He was transferred to our hospital because of high fever and heart murmur. Echocardiogram revealed a developing vegetation of aortic cusps and an aneurysmal change of the non-coronary sinus Valsalva. On admission he was complicated by anemia, purulent meningitis and suppurative arthritis of left knee. There were no signs of cardiac failure. Erythropoietin (6000 U thrice weekly) and iron (60 mg daily) were given for 11 weeks prior to surgery, raising the hemoglobin level from 9.2 g/dl to 18.4 g/dl. Aortic valve replacement and plasty of the sinus Valsalva were then performed. Intraoperatively hemoglobin concentration dropped to 10.3 g/dl and it raised to 15 g/dl postoperatively. We also used Cell-Saver to reduce blood loss. The patient made an uncomplicated recovery. Erythropoietin therapy contributed substantially to the successful outcome of this case.

Aortic Aneurysm↗