Search PubMed⌕ Search

Biomedical subjects

A Ohno

Publications and source records attributed to A Ohno.

At least 19 recordsLinked to original sources
PubMed2003

Functional characterization of three human cytochrome p450 2E1 variants with amino acid substitutions.

1. Cytochrome p450 (p450) 2E1 is a hepatic enzyme of importance for the metabolism of xenobiotics such as drugs and environmental toxicants. Genetic polymorphisms of CYP2E1 in 5'-flanking and coding regions have been found previously in Caucasian and Chinese populations. 2. In order to investigate the effects of amino acid substitutions on the function of CYP2E1, the enzymes of all known CYP2E1 variants in the coding region (CYP2E1.2, CYP2E1.3 and CYP2E1.4) with Arg76His, Val389Ile and Val179Ile substitutions, respectively, as well as the wild-type CYP2E1 (CYP2E1.1) were expressed in COS-1 cells, and their chlorzoxazone 6-hydroxylation and 4-nitrophenol 2-hydroxylation activities were determined. 3. The protein level of CYP2E1.2 was reduced to 29% compared with that of CYP2E1.1. The profiles of the level of activity relative to CYP2E1.1 for chlorzoxazone 6-hydroxylation (300 microM substrate) and 4-nitrophenol 2-hydroxylation (150 microM substrate) were very similar. 4. Although the K(m) values were not significantly different among wild-type and variant CYP2E1s in any oxidation metabolism, the V(max) and V(max)/K(m) of CYP2E1.2 on the basis of the CYP2E1 protein level were 2.7-3.0-fold higher than those of CYP2E1.1. In contrast, the levels of CYP2E1 protein and catalytic activity of CYP2E1.3 and CYP2E1.4 were not affected by the corresponding amino acid substitutions. 5. The findings suggest that Arg76 is closely associated with the function of CYP2E1, and that the genetic polymorphism of CYP2E1 is one cause of interindividual differences in the toxicity of xenobiotics.

Amino Acid Substitution↗
PubMed2001

NAD/NADH models with axial/central chiralities: superiority of the quinoline ring system.

Precursors of NAD model compounds 1c and 3a,b were successfully resolved into their atropisomers with respect to carbamoyl rotation. Atropisomers of quinoline derivatives are much more stable than pyridine derivatives as determined by cyclic voltammetry and X-ray crystallography. The 1,4-reduction of NAD model compound 4 was successfully achieved, affording novel NADH model compound 5. The rotational properties of the side chain of 5 were investigated by means of dynamic NMR. The rotational rate and syn/anti ratio, which indicate the orientation between carbonyl oxygen and hydrogen at the 4-position, are significantly affected by addition of magnesium ion. In the rotational transition state, the double-bond character of the C(carbonyl)-N(amide) bond is disrupted judging from the activation parameters. The oxidation of chiral 5 with p-benzoquinone in the presence of magnesium ion catalyst gave predominantly one enantiomer of 4. On the other hand, oxidation of 5 with p-chloranil (tetrachloro-p-benzoquinone) in the absence of magnesium ions affords the opposite enantiomer of 4 as the major product. The product enantiomer ratio is parallel to the syn/anti ratio in the starting material, indicating the importance of ground state conformation to stereochemistry of the reaction.

Crystallography, X-Ray↗
PubMed2001

The in vivo activity of olamufloxacin (HSR-903) in systemic and urinary tract infections in mice.

The in vivo activity of olamufloxacin (HSR-903), a new fluoroquinolone, was evaluated and compared with ciprofloxacin, sparfloxacin and levofloxacin. Olamufloxacin was active against systemic infection in mice inoculated with both Gram-positive and -negative bacteria. Olamufloxacin had equal efficacy for experimental urinary tract infections in mice caused by Pseudomonas aeruginosa.

Animals↗
PubMed2001

In vitro and in vivo antibacterial activities of L-084, a novel oral carbapenem, against causative organisms of respiratory tract infections.

L-084 (a prodrug of LJC 11,036 [L-036]) is a new oral carbapenem. Here we compared the in vitro and in vivo antibacterial activities of L-036 with those of imipenem, faropenem, ceditoren-pivoxil, cefdinir, amoxicillin, and levofloxacin. The MICs at which 90% of the isolates were inhibited of L-036 against methicillin-susceptible staphylococci, Streptococcus pneumoniae including penicillin-resistant organisms, Escherichia coli, Klebsiella pneumoniae, Haemophilus influenzae including ampicillin-resistant organisms, Legionella pneumophila, and Moraxella catarrhalis were equal to or less than 1 microg/ml. In pharmacokinetics studies of L-084 in lungs of mice, the maximum concentration in serum, half-life, and area under the concentration-time curve of this drug were 9.09 microg/g of tissue, 6.18 h, and 31.0 microg. h/ml, respectively. In murine respiratory infection models of penicillin-susceptible and -resistant S. pneumoniae and H. influenzae, the efficacies of L-084 were better than those of reference drugs. Our results indicate that the in vitro high potency and good distribution in the lungs might be the underlying mechanisms of its efficacy in the murine model of pneumonia.

Animals↗
PubMed2001

(10Z)- and (10E)-19-fluoro-1alpha,25-dihydroxyvitamin D3: an improved synthesis via 19-nor-10-oxo-vitamin D.

An efficient synthetic route to (10Z)- and (10E)-19-fluoro-1alpha,25-dihydroxyvitamin D3 was developed. The key feature of this pathway is the introduction of a 19-fluoromethylene group to a (5E)-19-nor-10-oxo-vitamin D derivative. The 10-oxo-compound was obtained via a 1,3-dipolar cycloaddition reaction of (5E)-1alpha,25-dihydroxyvitamin D with in situ generated nitrile oxide followed by ring cleavage of the formed isoxazoline moiety with molybdenum hexacarbonyl. Conversion of the keto group of (5E)-19-nor-10-oxo-vitamin D to the E and Z fluoromethylene group was achieved through a two-step sequence involving a reaction of lithiofluoromethyl phenyl sulfone followed by the reductive desulfonylation of the alpha-fluoro-beta-hydroxy sulfone. The dye-sensitized photoisomerization of the (5E)-19-fluorovitamin D afforded the desired (5Z)-19-fluorovitamin D derivatives, (10Z)- and (10E)-19-fluoro-1alpha,25-dihydroxyvitamin D3.

Calcifediol↗
PubMed2001

[Effects of bofu-tsusho-san, a traditional Chinese medicine, on body fat accumulation in fructose-loaded rats].

The effects of Bofu-tsusho-san (BOF), a traditional Chinese medicine, on fructose-induced hypertriglyceridemia and body fat accumulation were investigated in female SD rats. Rats were allowed to drink ad libitum 25% (w/w) fructose solution for 6 weeks. BOF was administered to the rats as an experimental diet containing 1.5% or 4.5% (w/w) of BOF during the fructose-loading period. BOF suppressed body weight gain and prevented the elevation of serum triglyceride levels and body fat accumulation in fructose-loaded rats without affecting food and fructose intake. Furthermore, BOF prevented the increase of triglyceride content in the liver and the reduction of mitochondrial cytochome c oxidase activity in the brown adipose tissue induced by fructose. From these results, it has been suggested that BOF has a preventive effect against the body fat accumulation caused by excess intake of sugar or other fructose-containing foods. The inhibition of triglyceride synthesis in the liver, and the enhancement of lipolysis in adipocytes and of thermogenesis in brown adipose tissue have been presumed as the mechanisms of action of BOF.

Adipose Tissue↗
PubMed2001

[Changes of infections due to drug resistant bacteria and its control].

The development and use of antibiotics for the chemotherapy of bacterial infections was one of the most remarkable accomplishments in medicine of the 20th. However, antibiotic-resistant bacteria were found in clinical isolates soon after the introduction of the earliest antimicrobial agents into the market. Significant increases in prevalence of resistance to antimicrobial agents have been observed in common pathogens of humans in the worldwide and problems of resistance are still presently serious among the immunocompromised host. The most important of these organisms are methicillin-resistant Staphylococcus aureus penicillin-resistant Streptococcus pneumoniae, vancomycin-resistant Enterococcus, and certain gram-negative bacilli due to extended-spectrum beta-lactamase production. These antibiotic resistances have made antimicrobial therapy of many infections extremely difficult or virtually impossible in some instances. In this article, we reviewed the history of antibiotic-resistance and discussed on the future.

Bacterial Infections↗
PubMed2001

[Vancomycin-resistant enterococci(VRE)].

The incidence of Enterococcal nosocomial infection has increased since 1980s. Most Enterococci are intrinsically resistant to many kinds of antibiotics, therefore, therapeutic drugs for enterococal infectious disease are limited to a few antibiotics such as ampicillin, gentamicin and vancomycin. However, since the first report of penicillinase producing E. faecalis in 1983, ampicillin-resistant strains have been increasing, furthermore, these strains often associated with high-level resistance to aminoglycosides. The yearly usage of vancomycin increased because vancomycin was only effective drug against such resistant strains and worldwide spread of multidrug-resistant MRSA which vancomycin is only effective. However, High-level vancomycin-resistance strains of E. faecium were first isolated in England in 1986. In 1990s, VRE have been spreading all over the world, especially, the emergency of multidrug-resistant strains, which are resistant to high concentrations of ampicillin or gentamicin or to vancomycin in USA, brought serious therapeutic dilemmas. This review focuses on the background in emergence of VRE, the relation with use of avoparcin, is used for growth promotion in farm animals, the mechanism of resistance, and the prevention of the spread of vancomycin resistance.

Cross Infection↗
PubMed2000

NAD(P)+-NAD(P)H models. 90. Stereoselection controlled by electronic effect of a carbonyl group in oxidation of NAD(P)H analog.

4-Monodeuterated NAD(P)H model compounds (1,4,6,7-tetrahydro-1,6,11-trimethyl-5-oxo-5H-benzo[c]pyrido[2,3-e]az epin; 11Me-MMPAH) have been oxidized with a series of p-benzoquinone and its derivatives in the presence of Mg2+. The models have an axial chirality with respect to the orientation of carbonyl dipole, the dihedral angle of which is larger than 55 degrees out of the plane of dihydropyridine ring. Without Mg2+, the anti- (with respect to the carbonyl dipole) hydrogen is 3 to 32 times more reactive than the corresponding syn-hydrogen, whereas, when Mg2+ is present in the system, the selectivity is shifted toward the syn-preferency. Mg2+ plays the role of a Lewis acid catalyst to control the stereochemistry at the same time as it catalyzes the reaction.

Catalysis↗
PubMed2000

Quenching of a photosensitized dye through single-electron transfer from trivalent phosphorus compounds

Various types of trivalent phosphorus compounds 1 undergo single-electron transfer (SET) to the photoexcited state of rhodamine 6G (Rho+*) in aqueous acetonitrile to quench the fluorescence from Rho+*. The rate constants kp for the overall SET process were determined by the Stern-Volmer method. The rate is nearly constant at a diffusion-controlled limit in the region of E1/2(1) < 1.3 V (vs Ag/Ag+), whereas log kp depends linearly on E1/2(1) in the region of E1/2(1) > 1.3 V, the slope of the correlation line being -alphaF/RT with alpha = 0.2. The potential at which the change in dependence of log kp on E1/2(1) occurs (1.3 V) is in accordance with the value of E1/2(Rho+*) (1.22 V) that has been obtained experimentally. Thus, the SET step is exothermic when E1/2(1) < 1.3 V and endothermic when E1/2(1) > 1.3 V. The alpha-value (0.2) obtained in the endothermic region shows that the SET step from 1 to Rho+* is irreversible in this region. Trivalent phosphorus radical cation 1*+ generated in the SET step undergoes an ionic reaction with water in the solvent rapidly enough to make the SET step irreversible. In contrast, the SET from amines 2 and alkoxybenzenes 3 to Rho+* is reversible when the SET step is endothermic, meaning that the radical cations 2*+ and 3*+ generated in the SET step undergo rapid "back SET" in the ground state to regenerate 2 and 3.

Journal Article↗
PubMed2000

Association of essential hypertension in elderly Japanese with I/D polymorphism of the angiotensin-converting enzyme (ACE) gene.

Recent evidence suggests that an insertion/deletion (I/D) polymorphism of the gene encoding angiotensin-converting enzyme (ACE) is associated with myocardial infarction and related cardiovascular diseases. We investigated a possible association of the ACE polymorphism with essential hypertension in a total of 263 cases/controls from among the elderly (age, over 70 years) and middle-aged (age between 30 and 60 years) Japanese population. The frequency of the I/I homozygote was significantly higher in hypertensive subjects than in controls in the elderly age group (33/57 vs 16/46; P = 0.02), but no association was observed in the middle-aged group (25/75 vs 26/85; P = 0.71). Similarly, having at least one insertion allele was associated with essential hypertension in the elderly age group (83/114 vs 46/92 in controls; P = 0.001), but not in the middle-aged group (78/150 vs 94/170; P = 0.524). These data suggest that genetic variation at the ACE locus may be associated with some determinants for blood pressure in elderly persons, and imply the involvement of the ACE insertion/deletion polymorphism in the etiology of age-related essential hypertension in the Japanese population.

Adult↗
PubMed2000

Differential effects of amino acid and ketoacid on protein metabolism in humans.

We examined the effects of insulin, amino acid (AA), and branched-chain ketoacid (KA) availability on leucine kinetics in eight healthy volunteers (age = 22 +/- 2 y, body mass index = 24 +/- 1 kg) by using the euglycemic insulin clamp and [1-14C] leucine turnover techniques. Four experimental conditions were studied: study I, hyperinsulinemia; study II, hyperinsulinemia with maintenance of basal plasma AA and branched-chain KA concentrations; study III, hyperinsulinemia with hyperaminoacidemia and basal plasma branched-chain KA concentrations; and study IV, hyperinsulinemia plus basal plasma AA concentrations and elevated branched-chain KA levels. Basal endogenous leucine flux (ELF) averaged 1.20 +/- 0.05 (mumol.kg-1.min-1, mean +/- SE); basal leucine oxidation (LOX) was 0.25 +/- 0.01; and basal non-oxidative leucine disposal (NOLD) was 0.95 +/- 0.04. ELF significantly decreased in study I (0.77 +/- 0.06 mumol.kg-1.min-1, P < 0.01 versus basal). When plasma AA and branched-chain KA were either maintained at their basal levels (study II) or increased above baseline values (studies III and IV), ELF declined further (0.64 +/- 0.05, 0.66 +/- 0.02, and 0.66 +/- 0.03 mumol.kg-1.min-1, respectively; all Ps < 0.01 versus basal and P < 0.01 versus study I). LOX declined in study I (0.12 +/- 0.02 mumol.kg-1.min-1, P < 0.01 versus basal) but increased significantly in studies II, III, and IV (0.31 +/- 0.04, 0.37 +/- 0.03, and 0.40 +/- 0.03 mumol.kg-1.min-1, respectively, all Ps < 0.01 versus basal, P < 0.05 study IV versus study II, and P < 0.05 study III versus study II). NOLD declined in study I (0.65 +/- 0.05 mumol/kg.min, P < 0.01 versus basal), whereas neither the maintenance of basal plasma AA/branched-chain KA levels (study II; 0.89 +/- 0.2 mumol.kg-1.min-1) nor the elevation of plasma branched-chain KA concentration (study IV; 0.96 +/- 0.1 mumol.kg-1.min-1) increased NOLD above baseline level. A stimulation of NOLD was observed only when plasma AA levels were increased (study III; 1.23 +/- 0.03 mumol/kg.min, P < 0.01 versus basal). In conclusion, the present data do not support the concept of a direct anabolic action of ketoanalogs but do provide additional evidence for the pivotal role of AA availability in the stimulation of whole-body protein synthesis.

Adult↗
PubMed2000

Problems related to determination of MICs of oximino-type expanded-spectrum cephems for Proteus vulgaris.

During in vitro susceptibility testing of clinical isolates of Proteus vulgaris, we noted that the MICs of several expanded-spectrum cephems were much higher in the broth microdilution method than in the agar dilution method (termed the MIC gap phenomenon). Here we investigated the mechanism of the MIC gap phenomenon. Cephems with the MIC gap phenomenon were of the oximino type, such as cefotaxime, cefteram, and cefpodoxime, which serve as good substrates for inducible class A beta-lactamase (CumA) enzymes produced by P. vulgaris; this finding suggests a relationship between the MIC gap phenomenon and CumA. Since peptidoglycan recycling shares a system common to that inducing CumA, we analyzed the mechanism of the MIC gap phenomenon using P. vulgaris B317 and isogenic mutants with mutations in the peptidoglycan recycling and beta-lactamase induction systems. The MIC gap phenomenon was observed in the parent strain B317 but not in B317G (cumG-defective mutant; defective peptidoglycan recycling) and B317R (cumR-defective mutant; defective CumA transcriptional regulator). No beta-lactamase activity was detected in B317G and B317R. beta-Lactamase activity and the MIC gap phenomenon were restored in B317G/pMD301 (strain transcomplemented by a cloned cumG gene) and B317R/pMD501 (strain transcomplemented by a cloned cumR gene). MICs determined by the agar dilution method increased when lower agar concentrations were used. Our results indicated that the mechanism of the MIC gap phenomenon is related to peptidoglycan recycling and CumA induction systems. However, it remains unclear how beta-lactamase induction of P. vulgaris is suppressed on agar plates.

Cephalosporins↗
PubMed2000

Synthesis of (10Z)- and (10E)-19-fluoro-1alpha,25-dihydroxyvitamin D3: compounds to probe vitamin D conformation in receptor complex by 19F-NMR.

To study the interaction of vitamin D with its receptor by 19F-NMR, (5Z,10Z)- and (5Z,10E)-19-fluoro-1alpha,25-dihydroxyvitamin D3 were synthesized starting from vitamin D2 via electrophilic fluorination of vitamin D-SO2 adducts as the key step. Regio- and stereoselective electrophilic fluorination at C(19) of vitamin D-SO2 adducts was achieved under the conditions using (PhSO2)2NF and bulky bases. The stereochemistry of the addition and elimination of SO2 of various vitamin D derivatives was studied in detail. SO2 causes Z-E isomerization of the 5,6-double bond of vitamin D and adds to the resulting (5E)-isomer from the sterically less hindered side opposite to the substituent at C(1). Elimination of SO2 from 19-substituted vitamin D-SO2 adducts proceeded exclusively in a suprafacial manner with respect to the diene part under either thermal or reductive conditions. Dye-sensitized photochemical isomerization of 19-fluorovitamin D derivatives was studied in detail. The rapid isomerization at the 5,6-double bond was followed by the slow isomerization at the 10,19-double bond to yield the (5E,10Z)-isomer (by nomenclature of the 1-OH derivatives) as the major product. (10Z)- and (10E)-19-Fluorovitamin Ds were also interconverted thermally probably via the corresponding previtamin D by 1,7-sigmatropic isomerization.

Fluorine↗