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Biomedical subjects

K Kano

Publications and source records attributed to K Kano.

At least 73 records · Page 4Linked to original sources
PubMed1999

Role of 2-amino-3-carboxy-1,4-naphthoquinone, a strong growth stimulator for bifidobacteria, as an electron transfer mediator for NAD(P)(+) regeneration in Bifidobacterium longum.

2-Amino-3-carboxy-1,4-naphthoquinone (ACNQ) is a novel growth stimulator for bifidobacteria. The role of ACNQ as a mediator of the electron transfer from NAD(P)H to dioxygen (O(2)) and hydrogen peroxide (H(2)O(2)), proposed in our previous paper, was examined using the cell-free extract and whole cells of Bifidobacterium longum. Continuous monitoring of ACNQ, O(2) and H(2)O(2) by several amperometric techniques has revealed that ACNQ works as a good electron acceptor of NAD(P)H diaphorase and that the reduced form of ACNQ is easily autoxidized and also acts as a better electron donor of NAD(P)H peroxidase than NAD(P)H. The generation of H(2)O(2) by B. longum under aerobic conditions is effectively suppressed in the presence of ACNQ. These ACNQ-mediated reactions would play roles as NAD(P)(+)-regeneration processes. The accumulation of ACNQ in the cytosol has been also suggested. These characteristics of ACNQ seem to be responsible for the growth stimulation of bifidobacteria. Vitamin K(3), which has an extremely low growth-stimulating activity and was used as a reference compound, exhibits much lower activity as an electron transfer mediator. The difference in the activity is discussed in terms of the redox potential and partition property of the quinones.

Anaerobiosis↗
PubMed1999

Biochemical and electrochemical characterization of quinohemoprotein amine dehydrogenase from Paracoccus denitrificans.

A new quinohemoprotein amine dehydrogenase from Paracoccus denitrificans IFO 12442 was isolated and characterized in views of biochemistry and electrochemistry. This enzyme exists in periplasm and catalyzes the oxidative deamination of primary aliphatic and aromatic amines. n-Butylamine or benzylamine as a carbon and energy source strongly induces the expression of the enzyme. Carbonyl reagents inhibit the enzyme activity irreversibly. This enzyme is a heterodimer constituted of alpha and beta subunits with the molecular mass of 59.5 and 36.5 kDa, respectively. UV-vis and EPR spectroscopy, and the quinone-dependent redox cycling and heme-dependent peroxidative stains of SDS-PAGE bands revealed that the alpha subunit contains one quinonoid cofactor and one heme c per molecule, while the beta subunit has no prosthetic group. The redox potential of the heme c moiety was determined to be 0.192 V vs NHE at pH 7.0 by a mediator-assisted continuous-flow column electrolytic spectroelectrochemical technique. The analysis of the substrate titration curve allowed the evaluation of the redox potential of the quinone/semiquinone and semiquinone/quinol redox couples as 0.19 and 0.11 V, respectively.

Dithionite↗
PubMed1999

Electrochemical study of reversible hydrogenase reaction of Desulfovibrio vulgaris cells with methyl viologen as an electron carrier.

An electrode modified with immobilized whole cells of Desulfovibrio vulgaris (Hildenborough) produces an S-shaped voltammogram with both cathodic- and anodic-catalytic-limiting currents in a methyl viologen-containing buffer saturated with H2. Methyl viologen penetrates into the bacterial cells to serve as an electron carrier in the reversible reaction of hydrogenase in the cells and functions as an electron-transfer mediator between the bacterial cells and the electrode, thus producing the catalytic currents for the evolution and consumption of H2. An equation for the catalytic current that takes into account the reversible hydrogenase reaction explains well the shape of the voltammogram. The potential at null current on the voltammogram agrees with the potential determined by potentiometry with the same electrode, which is equal to the redox potential of the H+/H2 couple in the solution--the standard potential of a hydrogen electrode at the pH of the solution. When D. vulgaris cells are suspended in an argon-saturated buffer containing methyl viologen, the suspension produces a catalytic current at a bare glassy carbon electrode for the evolution of H2. Analysis of the current by a theory for a catalytic current for a unidirectional nonlinear enzyme catalysis allows us to determine the kinetic parameters of the reaction between methyl viologen and hydrogenase in intact D. vulgaris cells. Thus we obtain the apparent Michaelis constant for methyl viologen cation radical, K'MV.+ = 0.16 mM, and the apparent catalytic constant (that is, the turnover number per D. vulgaris cell), zkcat,H+ = 1.2 x 10(7) s-1, for the H2 evolution reaction at pH 5.5 and at 25 degrees C, z being the number of hydrogenases contained in a D. vulgaris cell. The bimolecular reaction rate constant, kcat,H+/K'MV.+, of the reaction between methyl viologen cation radical and oxidized hydrogenase in intact D. vulgaris cells is estimated as 4.2 x 10(7) M-1 s-1. Similarly, the bimolecular reaction rate constant, kcat,H2/K'MV2+, of the reaction between methyl viologen and reduced hydrogenase is estimated to be 1.2 x 10(7) M-1 s-1 at pH 9.5 and 25 degrees C. Both rate constants are large enough for the reactions to be diffusion-limited processes.

Bacterial Proteins↗
PubMed1999

Surface characterization and on-line activity measurements of microorganisms by capillary zone electrophoresis.

Capillary zone electrophoresis (CZE) was applied to the electrophoretic characterization for microorganisms. The electrophoretic peaks detected using light scattering phenomena were characteristic of the microorganisms used. The electrophoretic mobility (mu) evaluated by CZE was in good agreement with that obtained by classical electrophoresis of microorganisms. The migration time was reproducible and depended on the ionic strength (I). Analysis of the mu vs. I relationship provided information regarding the charge density and the hardness of the microbial cell surface. The redox enzymatic activity of microorganisms was also evaluated by CZE using a running buffer containing a corresponding substrate and an appropriate exogenous electron acceptor. A decrease in the concentration of the electron acceptor due to microbial activity can be simultaneously monitored during the electrophoretic process without significant modification of the CZE instrument. Effects of some chemical treatments of microbial cells were also studied using this technique.

Bacteria↗
PubMed1999

Influence of grip strength on metacarpal bone mineral density in postmenopausal Japanese women: a cross-sectional study.

Most published studies on the role of muscle strength in the maintenance of bone mineral density (BMD) focused on the relationship between specific muscle groups and adjacent bones, mostly in young and premenopausal women. This study examined the influence of grip strength on BMD of the metacarpal index in postmenopausal Japanese women. Subjects included 1168 postmenopausal women aged 40-70 years. BMD measurement was done with computed X-ray densitometry (CXD) by analyzing X-ray films of the right second metacarpal index. Grip strength was measured in both the dominant and nondominant hands using a squeeze dynamometer. Grip strength (r = 0.2474; P = 0.0001) and age (r = -0.5443; P = 0.0001) significantly correlated positively and negatively, respectively, with BMD. Physical activity (r = 0.1318; P = 0.0001) also correlated positively with BMD. Breastfeeding (r = -0.1658; P = 0.0001), however, correlated negatively with BMD. Subjects with a history of regular physical activity had higher grip strengths and BMD, than those with no physical activity. Adjustment for age, physical activity, calcium intake, BMI, breastfeeding, testing site, and menopausal type indicated a significant (P for trend = 0.0013) positive association of grip strength with BMD. Subjects with stronger grip strengths had a decreased risk for low BMD.

Absorptiometry, Photon↗
PubMed1999

Subtraction ICG angiography in Harada's disease.

BACKGROUND/AIM: The significance of indocyanine green (ICG) angiography (ICGA) in Harada's disease still awaits clarification in many respects. This study investigates the details of choroidal lesions observed in Harada's disease by the subtraction method. METHODS: Eight patients with Harada's disease were followed with ICGA. ICG angiograms were obtained with a Topcon high resolution digital fundus camera and processed with a Topcon IMAGEnet computer system. Image subtraction was conducted for analysing serial angiograms taken at about 2 second intervals during the dye transit phase and those taken in the early and middle phases of angiography. RESULTS: Standard ICG images of acute stage disease showed delayed choroidal filling in the early phase. Mid phase angiograms showed areas with bright fluorescence of variable intensity, indicating intrachoroidal ICG leakage. With image subtraction of angiograms with an interval of seconds the choroidal vessels could be imaged sequentially, with the choroidal arteries visualised first, followed by the definition of the choriocapillaris and then the choroidal veins. The choroidal veins with delayed filling were visualised as positive images in serial subtraction angiograms. Subtraction with an interval of minutes showed uneven background fluorescence and bright fluorescence corresponding to the areas of intrachoroidal ICG leakage. After the disease subsided with steroid therapy, angiography revealed an improvement in delayed choroidal filling. Image subtraction by the second allowed a clear visualisation of improved choroidal venous filling, while subtraction by the minute showed homogeneous background fluorescence, eliminating brighter areas. CONCLUSION: Subtraction ICGA demonstrated that delayed filling of the choroidal veins of varying severity occurs in association with hyperpermeability of the choroidal vessels in the course of Harada's disease.

Adult↗
PubMed1999

Cloning and studies of the mouse cDNA encoding Smad3.

Following stimulation by the transforming growth factor-beta (TGF-beta) family in the cytoplasm, the Smad family is phosphorylated and translocated to the nucleus and activates several gene transcriptions. In this study, the mouse Smad3 cDNA including the open reading frame (ORF) was cloned from the mouse brain using a RACE (rapid amplification of cDNA ends) technique, and its expression pattern was analyzed in mouse tissue using northern blot. The predicted amino acid (aa) sequences of mouse Smad3 showed a high homology with human Smad3 (99.3%) and mouse Smad2 (85.4%). It revealed that this protein may be highly conserved in different species of mammals. Northern blot analyses revealed that Smad3 was highly expressed in the brain and ovary, and that the size of major transcript was about 5.7 kb. In situ hybridization analyses revealed the high expression of Smad3 was detected in the pyramidal cells of the hippocampus, the granule cells of the dentate gyrus, the granular cells of the cerebral cortex and the granulosa cells of the ovary. Smad3 may be essential transducer of signals from TGF-beta and activin in these cells.

Amino Acid Sequence↗
PubMed1999

[The critical appraisal of QOL questionnaire for prostate cancer patients].

BACKGROUND: Prostate cancer is a common malignancy that affects Japanese elderly men. Its incidence is increasing, recently, and its treatments are various. The measurement of quality of life (QOL) has become important for the evaluation of and selection of treatments. In Japan, however, there is no standard way of measuring QOL for prostate cancer patients, except the Japanese version of the EORTC QOL questionnaire for prostate cancer patients. We examined the validity and feasibility of this translated EORTC QOL questionnaire for prostate cancer patients. METHODS: Sixty-nine prostate cancer patients who were under treatment in 4 hospitals were selected for this study. We applied the content validity, the factorial validity which was analyzed by the oblique principal component cluster analysis, the internal consistency analyzed by the alpha coefficient of Cronbach, the convergent validity which was used GHQ, IPSS and PS as external measures, and the feasibility. RESULTS: This questionnaire showed good internal consistency, as the alpha coefficient was 0.61 to 0.90 in all domains, except for sex life, which was the lowest. This questionnaire was classified into 7 clusters by the oblique principal component cluster analysis. Consequently, the factorial validity was good, except for items regarding sex life. As domains correlate well with external measures except in sex life, the convergent validity was good. It was suggested that only two items were not acceptable in regard to the content validity and the feasibility, and that the translation into Japanese of 2 items was inadequate. CONCLUSIONS: Our study suggests that the Japanese version of the EORTC QOL questionnaire for prostate cancer patients demands improvement for the practical employment in clinical trials, as there is a problem of translation and feasibility.

Aged↗
PubMed1999

[Observation of physiological change in the human ciliary body using an ultrasound biomicroscope during accommodation].

PURPOSE: To evaluate changes in the ciliary body during accommodation using an ultrasound biomicroscope (UBM). SUBJECTS AND METHODS: Eleven healthy persons, aged from 24 to 33 years, served as subjects. They were asked to lie in the supine position and to fixate a target placed on the ceiling 2 m above with the left eye. A concave lens with the power of -6 to -8 diopters was then placed before the fixating left eye. The thickness of the ciliary body in the right eye was measured by UBM in the nonaccommodative and accommodative states. FINDINGS: The anterior chamber in the right eye became significantly shallow during accommodation. The thickness of the ciliary body significantly increased during accommodation at 0.5 mm and 1.0 mm posterior to the scleral spur. It significantly decreased at 2.0 mm, 2.5 mm and 3.0 mm posterior to the scleral spur. CONCLUSION: During induced accommodation in the left eye, the anterior portion of the ciliary body in the right eye increased and the posterior portion decreased in thickness. The findings imply that the circular ciliary muscles are mainly involved in accommodation and not the longitudinal muscles.

Accommodation, Ocular↗
PubMed1999

Comparison between pre- and posttreatment clinical and renal biopsies in children receiving low dose ciclosporine-A for 2 years for steroid-dependent nephrotic syndrome.

BACKGROUND: The dose of ciclosporine-A (CSA) for long-term treatment of nephrotic syndrome remains unclear due to the chronic nephrotoxicity of CSA. PATIENTS AND METHODS: We examined 14 children with steroid-dependent nephrotic syndrome (SDNS) who showed signs of steroid toxicity and did not respond to cyclophosphamide. CSA was started at a dose between 2.0 and 3.3 mg/kg/day and the CSA dosage was decreased to between 1.6 and 3.1 mg/kg/day 4 months after the initiation of CSA therapy to maintain 40 to 70 ng/ml in the whole blood trough level. RESULTS: Renal histology before CSA therapy showed minimal changes in all patients. It was possible to discontinue corticosteroid therapy within 3 to 4 months in all patients. The SD score for height significantly improved during CSA therapy. The incidence of CSA side-effects in our patients was lower than previously reported. Post-therapy biopsies after 24 months of CSA treatment showed mild tubular atrophy accompanying stripped interstitial fibrosis in only 1 patient (7%), and positive findings of global sclerosed glomeruli in 2 patients. CONCLUSION: Long-term CSA therapy in low doses was effective for patients with SDNS and demonstrated a low incidence of CSA side-effects including nephrotoxicity.

Child↗
PubMed1999

[Rapid pulse injection of indocyanine green angiography for evaluation of choroidal venous circulation].

PURPOSE: To investigate the influence of the injection duration on the early phase of indocyanine green fundus angiography, we performed indocyanine green fundus angiography using a rapid pulse injection method, and compared early-phase findings with those obtained using a previous injection method. METHODS: Rabbit eyes were used. Normal eyes (10), eyes with chorioretinal atrophy (5), and eyes with occlusion of vortex veins (5) were examined. RESULTS: In normal eyes, rapid pulse injection resulted in visualization of some small bright fluorescent boluses from 6 to 12 seconds after injection, whereas with the previous method they were unclear. In eyes with occlusion of vortex veins, rapid pulse injection resulted in visualization of delayed hyperfluorescence of choroidal veins against the background, and the region of delayed venous filling could easily be determined. In eyes with chorioretinal atrophy, only the rapid pulse injection clearly revealed delayed filling of choroidal veins. CONCLUSIONS: The rapid pulse injection method enabled detection of lesions which were not clearly visible using the previous injection method, and is useful for study of choroidal circulation.

Animals↗
PubMed1999

[Clinical results of selective laser trabeculoplasty].

PURPOSE: Selective laser trabeculoplasty (SLT) is a new laser procedure using a frequency-doubled Q-switched Nd: YAG laser (wavelength: 532 mm). The laser parameters are set to selectively target pigmented trabecular meshwork (TM) cells without coagulative damage to the TM structure or non-pigmented cells. We investigated the safety and efficacy of SLT in lowering intraocular pressure (IOP). SUBJECTS AND METHOD: Sixty-seven eyes of 67 patients with uncontrolled open angle glaucoma were treated with the Coherent Selecta 7000 (Coherent Inc., Palo Alto, CA). Nineteen of 67 patients had previously received argon laser trabeculoplasty (ALT). A total of approximately 60 non-overlapping spots were placed over 180 degrees of the TM ranging from 0.5 to 1.0 mJ per pulse. The maximum energy level at which no bubble formation was observed determined choice. RESULTS: The average preoperative IOP was 22.4 mmHg. Six months after the operation, mean IOP reduction was 4.4 mmHg, and mean outflow pressure (OP) reduction was 38.1%. One month after the operation 68.7% of patients responded to treatment with an OP reduction of at least 20% ("responders"). Transient IOP elevation of 5 mmHg or greater was seen in 25.4% of patients. The success rate at 6 months after operation was 64.6% for all patients (67 eyes) and 78.2% for the responders (46 eyes). An analysis using a Cox proportional hazard model showed that a low preoperative IOP was the significant determinant for success, and the hazard ratio for the IOP increase of 5 mmHg was 2.12. Other factors such as age, gender, past history of ALT, and goniopigment were not significantly related to success. CONCLUSION: SLT appears to be a safe and effective way to lower IOP.

Adult↗
PubMed1999

[Clinical experiences and problems with home medical treatment in an orthopedic clinic].

Twenty-five patients who received home medical treatment were reviewed. There were 11 males and 14 females, with a mean age of 77 years. In an orthopedic clinic, it is difficult to secure the time for to visit a patient's home. Another problem for doctor is that the medical fee for home treatment is very low. To promote home treatment by orthopedists, it is important to secure the time to visit a patient's home, to improve the fees for home treatment, and to establish a connection with a visiting nurse care station and visiting rehabilitation workers.

Aged↗
PubMed1998

Timing of menopause, reproductive years, and bone mineral density: a cross-sectional study of postmenopausal Japanese women.

Age at menopause has been found to be associated positively with bone mineral density, and age at menarche has been found to be associated negatively with bone mineral density. However, there have been few studies on the relations of timing of menopause and length of the reproductive period with bone mineral density. The purpose of this study was to examine the relations of timing of menopause and reproductive years (calculated as age at menopause minus age at menarche) with mineral density of the second metacarpal bone in postmenopausal Japanese women. The study population consisted of 1,035 naturally menopausal women aged 40-70 years who were screened in 1996-1997. Using computed x-ray densitometry, the authors measured bone mineral density by analyzing radiographic films of the right second metacarpal bone. Using the women with early menopause (age < 49 years) as the reference group and adjusting for age, subjects with late menopause were at decreased risk for low bone mineral density (odds ratio (OR) = 0.69, 95% confidence interval (CI) 0.49-0.97). After adjustment for additional covariates (grip strength, physical activity, body mass index, smoking, and calcium intake), the association was unchanged (OR = 0.70, 95% CI 0.50-0.99). Postmenopausal women with more reproductive years (> or = 40 years) were at decreased risk for low bone mineral density compared with those with fewer reproductive years, after adjustment for age (OR = 0.73, 95% CI 0.40-1.30) and potentially confounding factors (OR = 0.76, 95% CI 0.41-1.37); the p-value for trend was not statistically significant. In multiple linear regression analysis, early menopause and fewer reproductive years were independent predictors of low bone mineral density. In this study, postmenopausal Japanese women who had a late menopause and more reproductive years were at decreased risk for low bone mineral density, and may therefore be less prone to osteoporosis.

Adult↗
PubMed1998

Mechanistic study on the roles of a bifidogenetic growth stimulator based on physicochemical characterization.

2-Amino-3-carboxy-1,4-naphthoquinone, discovered as a novel bifidogenetic growth stimulator (BGS), has been characterized by determination of redox and acid-base equilibria, partition properties, and UV-vis and electron spin resonance spectral properties. BGS is proposed to function as an electron transfer mediator from NADH to O2. BGS is reduced by NADH-reduced diaphorase (or related enzymes) and the reduced BGS is reoxidized by autoxidation and a peroxidase-catalyzed reaction. The proposed reaction would spare pyruvate as an important metabolic intermediate, and minimize the cytotoxic effects of H2O2 generated by the autoxidation. Kinetic studies were performed in model enzymatic systems using 2-methyl-1,4-naphthoquinone (VK3) as a reference compound with a very weak growth-stimulating effect. The results support our proposal and reveal the superiority of BGS to VK3 as an electron transfer mediator in the proposed reactions.

Bifidobacterium↗
PubMed1998

Role of the isoprenyl tail of ubiquinone in reaction with respiratory enzymes: studies with bovine heart mitochondrial complex I and Escherichia coli bo-type ubiquinol oxidase.

The hydrophobic isoprene tail of ubiquinone-2 (Q2) exihibits binding specificity in redox reactions with bovine heart mitochondrial complex I (Ohshima, M., Miyoshi, H., Sakamoto, K., Takegami, K., Iwata, J., Kuwabara, K., Iwamura, H., and Yagi, T. (1998) Biochemistry 37, 6436-6445) and the Escherichia coli bo-type ubiquinol oxidase (Sakamoto, K., Miyoshi, H., Takegami, K., Mogi, T., Anraku, Y., and Iwamura, H. (1996) J. Biol. Chem. 271, 29897-29902). To identify the structural factor(s) of the diprenyl tail of Q2 governing the specific interaction with these enzymes, we synthesized a series of novel Q2 analogues in which only one of the structural factors of the diprenyl tail was systematically modified. In bovine complex I, the presence of the methyl branch and the pi-electron system in the first isoprene unit are responsible for high-affinity binding of Q2 to the ubiquinone reduction site, which results in a low Km and kcat values of Q2 reduction. The position of the methyl group in the tail is strictly recognized by the enzyme. In contrast to complex I, in bo-type ubiquinol oxidase, either of the two pi-electron systems in the tail is required for high-affinity binding of Q2H2 to the enzyme, while the presence of the methyl branch and the location of the pi-electron systems are not strictly recognized by the enzyme. We concluded that the role of the ubiquinone tail is not simply the enhancement of the hydrophobicity of the molecule and that molecular recognition of the tail by the quinone redox site differs among the respiratory enzymes.

Animals↗