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K Aisaka

Publications and source records attributed to K Aisaka.

At least 19 recordsLinked to original sources
PubMed2006

Purification, characterization, and potential applications of formate oxidase from Debaryomyces vanrijiae MH201.

Formate oxidase was found in cell-free extracts of Debaryomyces vanrijiae MH201, a soil isolate. After purification by column chromatography, the preparation showed a protein band corresponding to a molecular mass (MM) of 64 kDa on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The MM, estimated by a gel filtration, was 99 kDa. The preparation showed two and three bands on isoelectric focusing under denaturing and native conditions, respectively. These results suggest that the preparation contained three isoforms, each of which might be composed of alphaalpha, alphabeta, and betabeta subunits with apparently similar MM. The preparation acted on formate with K (m) and V (max) values of 11.7 mM and 262 micromol min(-1) mg(-1), respectively, at pH 4.5 and 25 degrees C, but showed no evidence of activity on the other compounds tested. The optimum pH and temperature were pH 4.0 and 35 degrees C, respectively. The preparation showed activities of 85% of the initial activity after storage at pH 6.0 and 4 degrees C for 8 weeks. When 10 mM formaldehyde was reacted with 2.0 U ml(-1) of the enzyme preparation at pH 5.5 and room temperature in the presence of 2.0 U ml(-1) of a microbial aldehyde oxidase and 100 U ml(-1) of catalase for 180 min, neither of formate nor formaldehyde was detected, suggesting that the reaction involved the quantitative conversion of formaldehyde to carbon dioxide.

Aldehyde Oxidase↗
PubMed2005

Characterization and potential application of purified aldehyde oxidase from Pseudomonas stutzeri IFO12695.

The molecular weight of purified aldehyde oxidase from Pseudomonas stutzeri IFO12695 was estimated to be 160 kDa by a gel filtration method. SDS-PAGE showed that the enzyme consisted of three non-identical subunits with molecular weights of 18, 38, and 83 kDa. The enzyme exhibited an absorption spectrum with maxima at 277, 325, 365, 415, 450, 480, and 550 nm and possessed molybdenum, CMP, iron, sulfur, and FAD as its cofactors, indicating that it belonged to the xanthine oxidase family. A variety of aliphatic and aromatic aldehydes were oxidized; and among them n-hexylaldehyde gave the most rapidly action. When 10 mM formaldehyde was treated with the aldehyde oxidase in the presence of catalase for 240 min, the formaldehyde concentration was reduced to 0.8 mM, suggesting this enzyme might be effective for the removal of formaldehyde contained in wastewater.

Aldehyde Oxidase↗
PubMed2001

Inhibitory effect of JTV-803, a new cyclic guanidine derivative, on factor Xa in vitro and in vivo.

JTV-803, 4-[(2-amidino-1,2,3,4-tetrahydroisoquinolin-7-yloxy)methyl]-1-(4-pyridinyl)piperidine-4-carboxylic acid monomethanesulfonate trihydrate showed a competitive inhibitory effect on human factor Xa, with a K(i) value of 0.019 microM. This compound was 100 times more selective in inhibiting human factor Xa as compared to its inhibitory activity against thrombin, plasmin, and trypsin. JTV-803 was also examined for its inhibitory effect on activated factor Xa obtained from plasma of various animal species. JTV-803 exerted a potent inhibitory effect on human factor Xa (IC(50): 0.081 microM). JTV-803 prolonged activated partial thromboplastin time and prothrombin time in a dose-dependent manner. Oral anticoagulant efficacy of JTV-803 was examined ex vivo for its inhibition of human factor Xa in cynomolgus monkeys. JTV-803 produced more than 20% inhibition of human factor Xa for 8 h. Taken together, the results indicate JTV-803 is a long-acting oral anticoagulant which exerts its effect via specific inhibition of human factor Xa.

Administration, Oral↗
PubMed2001

A retrotransposon-derived gene, PEG10, is a novel imprinted gene located on human chromosome 7q21.

A novel paternally expressed imprinted gene, PEG10 (Paternally Expressed 10), was identified on human chromosome 7q21. PEG10 is located near the SGCE (Sarcoglycan epsilon) gene, whose mouse homologue was recently shown to be imprinted. Therefore, it is highly possible that a new imprinted gene cluster exists on human chromosome 7q21. Analysis of two predicted open reading frames (ORF1 and ORF2) revealed that ORF1 and ORF2 have homology to the gag and pol proteins of some vertebrate retrotransposons, respectively. These data suggest that PEG10 is derived from a retrotransposon that was previously integrated into the mammalian genome. PEG10 is likely to be essential for understanding how exogenous genes become imprinted.

Amino Acid Sequence↗
PubMed2001

Antithrombotic effects of a synthetic inhibitor of activated factor X, JTV-803, in animals.

JTV-803, 4-[(2-amidino-1,2,3,4-tetrahydroisoquinolin-7-yloxy)methyl]-1-(4-pyridinyl)piperidine-4-carboxylic acid monomethanesulfonate trihydrate, at > or = 0.1 mg/kg/h inhibited the increase in plasma thrombin-antithrombin III complex in response to continuous infusion of thromboplastin in rats. JTV-803 inhibited thrombus formation in an arteriovenous shunt model by intravenous infusion at > or = 0.3 mg/kg/h and prolonged the occlusion time of photochemically induced arterial thrombus in the middle cerebral artery at >1.5 mg/kg/0.5 h. Activated partial thromboplastin time was prolonged at 10 mg/kg/h. Intravenous administration of JTV-803 prolonged bleeding time at 30 mg/kg/h, a dose 10-100 times higher than the dose that inhibited thrombus formation. Compared with thrombin inhibitor, JTV-803 had less of an effect on the bleeding time. In the arteriovenous shunt model in cynomolgus monkey, JTV-803 prolonged the occlusion time when administered by continuous infusion at 0.3 mg/kg/h or orally at 10 mg/kg. These results suggest that the human factor Xa inhibitor JTV-803 is an orally active anticoagulant that does not affect bleeding time and is useful for the prevention of thrombus.

Animals↗
PubMed2001

Tumour suppressor activity of human imprinted gene PEG3 in a glioma cell line.

BACKGROUND: Mouse imprinted gene Peg3 encodes a large C2H2 type zinc finger protein with unique characteristics. Peg3 knockout mice were found to show an impairment in maternal behaviour of the adult female. Mouse Peg3 is located on the proximal region of chromosome 7 which is syntenic to the long arm of human chromosome 19. It has been reported that a loss of heterozygosity (LOH) of chromosome 19q occurs frequently in several glioma types. RESULTS: We isolated human PEG3 cDNA. Both human and mouse PEG3 were strongly expressed in the adult brain and the Peg3 protein was localized in the nuclei of both neurones and glial cells. A significant decrease in PEG3 expression was more commonly observed in glioma cell lines as compared with that in primary cultures of astrocytes. Transfection of PEG3 cDNA in a glioma cell line resulted in a loss of tumorigenicity in nude mice. CONCLUSIONS: The human PEG3 gene is a paternally expressed imprinted gene. Introduction of PEG3 cDNA into the glioma cells suggests that human PEG3 protein functions as a tumour suppressor. Human PEG3 is located on 19q13.4 and is one of the candidates for tumour suppressor genes that are predicted to be sited in gliomas.

5' Untranslated Regions↗
PubMed2001

Determination of 1,5-anhydro-D-glucitol on the basis of its inhibitory effect on trehalase activity.

1,5-Anhydro-D-glucitol (1,5-AG) was found to inhibit trehalase and trehalose phosphorylase activities competitively, because of its structural similarity with D-glucose. Trehalase from Nocardia sp., one of the most 1,5-AG-sensitive enzymes, was used in the determination of 1,5-AG concentration, which is a useful marker for the diagnosis of diabetes. A good linear relationship was observed between 1,5-AG concentration in the range of 0.02 to 1.0 mM and the extent of trehalase inhibition by 1,5-AG. The 1,5-AG concentration range could be determined by estimating enzymatically the amount of the reaction product, D-glucose, produced by the trehalase.

Journal Article↗
PubMed2001

Effect of high-dose progestogen on hemostatic properties of blood in patients with endometrial cancer.

Fifteen cases of endometrial cancer were administered daily doses of 600 mg of MPA after surgery to prevent the recurrence of cancer. The initiation times of coagulation (time necessary for fibrin network formation) were measured with a highly sensitive damped oscillation rheometer and compared with those of 15 control patients who were not administered MPA. Biochemical studies of blood coagulation and fibrinolysis were also done. The initiation times of coagulation were 19.0+/-1.8 minutes (min mean +/- standard deviation) after 3-6 months and 16.0+/-2.0 min after 9-12 months of MPA administration, both times being significantly shorter compared with the controls (24.0+/-2.5 min). Hematocrit values, platelet counts and fibrinogen levels were similar between the two groups. Activated partial thromboplastin time (APTT) was significantly decreased and antithrombin III activity (AT III), thrombin-antithrombin complex (TAT), plasminogen level, plasmin-alpha(2) plasmin inhibitor complex level (PIC) and the fibrin degradation product level (FDP) were significantly increased in the MPA group compared with the control group. Accelerated coagulation of blood was definitely induced by high-dose MPA but antithrombin and fibrinolytic activities were also induced, and, thus, thromboembolic complications were prevented.

Adult↗
PubMed2000

Effect of JTH-601, a novel alpha(1)-adrenoceptor antagonist, on prostate function in dogs.

We examined the effect of JTH-601 (3-¿N-[2-(4-hydroxy-2-isopropyl-5-methylphenoxy)ethyl]-N-methylaminom ethyl¿-4-methoxy-2,5,6-trimethylphenol hemifumarate), a new alpha(1L)-adrenoceptor antagonist, on prostatic function in isolated canine prostate and in anesthetized dogs. In the contraction study, phenylephrine and noradrenaline produced concentration-dependent contractions in canine prostate and carotid artery, respectively. In these tissues, JTH-601, prazosin (a non-selective alpha(1)-adrenoceptor antagonist), and tamsulosin (an alpha(1A)-adrenoceptor antagonist) competitively antagonized contraction in a concentration-dependent manner. The pA(2) (pK(B)) values with prostate were 8.49+/-0.07 for JTH-601, 7.94+/-0.04 for prazosin and 9.42+/-0.22 for tamsulosin. The ratio of pA(2) (carotid artery/prostate), i.e. prostatic selectivity, was 10.471 for JTH-601, 0.008 for prazosin and 0.371 for tamsulosin, respectively. In anesthetized dogs, JTH-601 (1 mg/kg, i.d.) significantly decreased urethral pressure by 15% without affecting blood pressure or heart rate. Tamsulosin (0.1 mg/kg, i.d.) decreased urethral pressure to the same extent as did JTH-601, but with a significant effect on blood pressure and heart rate. JTH-601 showed higher selectivity for canine prostate both in vitro and in vivo. In prostate, an important role of the alpha(1L)-adrenoceptor is suggested in the smooth muscle contraction mediated by alpha(1)-adrenoceptors. JTH-601 is expected to be an effective alpha(1)-adrenoceptor antagonist for the treatment of urinary outlet obstruction by benign prostatic hypertrophy with a minimum effect on the cardiovascular system.

Adrenergic alpha-1 Receptor Antagonists↗
PubMed2000

Enzymatic synthesis of novel disaccharides using disaccharide phosphorylases.

A method for the synthesis of novel disaccharides was developed. It involved the following two steps. The first step consisted of two continuous reactions: the conversion of maltose to beta-D-glucose-1-phosphate and D-glucose by the phosphorolytic activity of maltose phosphorylase and the specific consumption of only D-glucose by incubation with glucose-consuming yeast cells. The second step involved the addition of an appropriate carbohydrate and its condensation with the remaining beta-D-glucose-1-phosphate by the synthetic activity of maltose phosphorylase or trehalose phosphorylase. Several factors affecting the yields of disaccharides were optimized. Using this method, five maltose-like derivatives and two trehalose-like derivatives were synthesized from maltose and the corresponding carbohydrates. Among these, 4-O-alpha-D-glucopyranosyl-L-fucopyranose (Glc(alpha1-4)Fuc) and alpha-d-glucopyranosyl alpha-D-fucopyranoside (Glc(alpha1-1alpha)Fuc) were purified, and identified by 1H NMR and 13C NMR.

Journal Article↗
PubMed2000

Identification of an imprinted gene, Meg3/Gtl2 and its human homologue MEG3, first mapped on mouse distal chromosome 12 and human chromosome 14q.

BACKGROUND: The paternal duplication of mouse distal chromosome 12 leads to late embryonal/neonatal lethality and growth promotion, whereas maternal duplication leads to late embryonal lethality and growth retardation. Human paternal or maternal uniparental disomies of chromosome 14q that are syntenic to mouse distal chromosome 12 have also been reported to show some imprinting effects on growth, mental activity and musculoskeletal morphology. For the isolation of imprinted genes in this region, a systematic screen of maternally expressed genes (Megs) was carried out by our subtraction-hybridization method using androgenetic and normally fertilized embryos. RESULTS: We have isolated seven candidate clones of the mouse Meg gene. Among them, we identified a novel maternally expressed imprinted gene, Meg3, on mouse distal chromosome 12 and showed that it was identical to the Gtl2 gene. We also found that the human homologue MEG3 on chromosome 14q was also monoallelically expressed. CONCLUSIONS: This is the first identification of the imprinting gene, both on mouse distal chromosome 12 and on human chromosome 14q, respectively. Because there are no obvious open reading frames in either the mouse Meg3/Gtl2 or human MEG3, the function of these genes remains unclear. However, this result will provide a good basis for the further investigation of several important imprinted genes in this chromosomal region.

Animals↗
PubMed2000

Mouse Peg9/Dlk1 and human PEG9/DLK1 are paternally expressed imprinted genes closely located to the maternally expressed imprinted genes: mouse Meg3/Gtl2 and human MEG3.

BACKGROUND: Genomic imprinting significantly influences development, growth and behaviour in mammals. Systematic screening of imprinted genes has been extensively carried out to identify the genes responsible for imprinted phenotypes and to elucidate the biological significance of this phenomenon. In this study, we applied DNA chip technology for isolating paternally expressed imprinted genes (Pegs). We compared the resulting expression profiles of parthenogenetic and fertilized control embryos to identify novel imprinted genes. RESULTS: A novel paternally expressed mouse imprinted gene, Peg9/Dlk1, was identified. Consistent with this finding, the paternal expression of its human homologue, PEG9/DLK1, was also confirmed. These two genes form imprinted gene clusters with the reciprocally imprinted mouse Meg3/Gtl2 and human MEG3 genes that we first identified on distal chromosome 12 and chromosome 14q32, respectively. CONCLUSIONS: As DNA chip technology allows us to quickly screen a large number of genes, using this technology to search for imprinted genes could accelerate the identification of genes responsible for human and mouse genetic diseases. Dlk1 and DLK1, which encode transmembrane proteins, have six EGF-like repeats and show homology to the Delta gene in Drosophila melanogaster. Because of its homology to mammalian Delta homologues, PEG9/DLK1 may contribute to the scoliosis phenotype observed in maternal uniparental disomy 14 (mUPD14) patients.

Animals↗
PubMed2000

Contractile properties of urethral smooth muscles of young and aged female dogs: morphological and pharmacological aspects.

BACKGROUND: Alpha1-adrenoceptors are highly concentrated in the urethral smooth muscles and may play an important role in the contraction of this area. However, detailed examinations of age-related changes of the properties of urethral smooth muscle have rarely been undertaken. METHODS: The contractile properties of urethras from young non-parous and old parous female beagles were determined with a urethral function study, macroscopic autoradiography for urethras using [3H]-labeled tamsulosin and morphometry of the urethral muscles. RESULTS: The antagonistic effect (pA2) of prazosin for norepinephrine was 7.76+/-0.13 in young dogs and 7.62+/-0.06 in aged dogs. The specific binding of [3H]-tamsulosin (a relatively selective alpha1A-adrenoceptor antagonist) was recognized diffusely in proximal urethras with in vitro autoradiography. The density of binding in smooth muscles was approximately 60 and 40% in circular longitudinal layers, respectively, for both dogs. CONCLUSIONS: The female canine urethra had alpha1A, and alpha1L-adrenoceptors. No age-related changes were seen in the function of the proximal urethra, distribution of alpha1-adrenoceptor binding sites and smooth muscle densities.

Adrenergic alpha-Agonists↗
PubMed2000

Prostate selectivity of JTH-601-G1, an active metabolite of JTH-601, in dogs.

OBJECTIVE: To evaluate the effect of JTH-601-G1, an active metabolite and glucuronide conjugate of JTH-601 (an alpha1-adrenoceptor antagonist), on smooth muscle contraction in canine prostate and artery, and to examine the effect of JTH-601-G1 on prostatic urethral pressure and blood pressure in anaesthetized dogs. Materials and methods Male beagle dogs were used in both an in vitro and an in vivo study. In the former, the prostate and right common carotid artery were isolated, and smooth muscle strips from the prostate and open-ring strips from the carotid artery prepared. The effects of JTH-601-G1 on phenylephrine- and noradrenaline-induced contraction were assessed in these tissues. In the in vivo study, four dogs were anaesthetized and the change in urethral pressure, blood pressure and heart rate measured continuously. Vehicle (saline) and JTH-601-G1 were then infused intravenously in increasing doses (0.33-3.3 microg/kg/min for 30 min). In three other dogs, the effect of JTH-601-G1 infusion at a higher rate (25 microg/kg/min for 3 h) on blood pressure was evaluated, and the plasma concentration of JTH-601-G1 measured using high-performance liquid chromatography-mass spectrometry. RESULTS: Of the distinct metabolites of JTH-601, JTH-601-G1 had the most potent alpha1-adrenoceptor antagonistic effect in isolated canine prostate. JTH-601-G1 also antagonized alpha1-adrenoceptor agonist-induced contraction in common carotid artery, but the pA2 value in the artery was approximately 25 times higher than that in the prostate. In anaesthetized dogs, JTH-601-G1 decreased urethral pressure in a dose-dependent manner; at the highest dose, urethral pressure decreased by 24.5% and blood pressure by 7.0%. However, there was no significant change in heart rate at any dose. The plasma concentration of JTH-601-G1 increased with the dose of JTH-601-G1, but the concentration of both JTH-601 and other metabolites was below the detection limit. The higher JTH-601-G1 infusion rate caused blood pressure to decrease by only 6-10% even at JTH-601-G1 plasma concentrations of approximately 1500 ng/mL during the infusion. Although there was a negative correlation between mean blood pressure and plasma JTH-601-G1 concentration, the decrease in blood pressure was small compared with the reduction in urethral pressure. CONCLUSION: JTH-601-G1 appears to be a major active metabolite of JTH-601 but with a higher selectivity for canine prostate than artery. The results also indicate that in addition to the alpha1A-adrenoceptor, the alpha1L-adrenoceptor plays an important prostatic selective role in smooth muscle contraction via the alpha1-adrenoceptor.

Adrenergic alpha-Antagonists↗
PubMed2000

Cardiovascular pharmacological studies on JTV-506, a new potassium channel opener. 1st communication: effects on myocardium and vasculature.

The effects of JTV-506 ((-)-(3S,4R)-2,2-bis(methoxymethyl)-4-[(1,6-dihydro-1-methyl-6-oxo-3- pyridazinyl)amino]-3-hydroxychroman-6-carbonitrile hemihydrate, CAS 170148-29-5), a novel coronary vasodilator, on hemodynamics, cardiac function and cardiac oxygen consumption were evaluated in anesthetized dogs. In anesthetized, open-chest dogs, JTV-506 (0.3-10 micrograms/kg i.v.) induced a marked increase in coronary blood flow in a dose dependent manner, while at these doses it had smaller effects on vertebral and mesenteric blood flow and almost no effect on renal blood flow. JTV-506 (1-10 micrograms/kg i.v.) showed a tendency to decrease oxygen consumption of the heart and elevate myocardial oxygen pressure without cardiac suppression. Effects of JTV-506 on hemodynamics and the respiratory system following i.v. administration (0.3-300 micrograms/kg) were investigated in spontaneously breathing anesthetized dogs. The effective dose to induce hemodynamic changes was more than 3 micrograms/kg. JTV-506 did not have a crucial influence on electrocardiogram. JTV-506 caused marked increase in coronary blood flow and myocardial oxygen pressure with slight change in blood pressure. It is concluded that JTV-506 is a potent vasodilator, with particularly pronounced effect on vasculature of the heart. These results suggest that JTV-506 may be useful in the treatment of angina pectoris.

Anesthesia↗
PubMed2000

Cardiovascular pharmacological studies on JTV-506, a new potassium channel opener. 2nd communication: effects on blood pressure in conscious animals.

The effects of JTV-506 ((-)-(3S,4R)-2,2-bis(methoxymethyl)-4-[(1,6-dihydro-1-methyl-6-oxo-3- pyridazinyl)amino]-3-hydroxychroman-6-carbonitrile hemihydrate, CAS 170148-29-5), a novel coronary vasodilator, on blood pressure were evaluated in conscious dogs and rats. In conscious dogs, JTV-506 (0.01-1 mg/kg p.o.), levcromakalim (0.01-1 mg/kg p.o.) and nifedipine (3-30 mg/kg p.o.) elicited an increase in double product, whereas nicorandil (1-10 mg/kg p.o.) did not affect the double product. The JTV-506-induced increase in double product was abolished by a beta-blocker, propranolol, suggesting that this increase in double product may be due to augumentation of heart rate by sympathetic nerves which mediate the baroreflex. The doses at which JTV-506 increased coronary blood flow in a previous study were lower than the doses required to increase the double product. JTV-506 did not have a crucial influence on electrocardiogram. In conscious rats, orally administered JTV-506, levcromakalim, nicorandil and nifedipine reduced blood pressure and increased heart rate dose dependently. These effects were more remarkable in hypertensive rats than in normotensive rats. JTV-506, a new potassium channel opener, seems to be relatively free of any hemodynamic effects.

Animals↗
PubMed2000

Expression and imprinting status of human PEG8/IGF2AS, a paternally expressed antisense transcript from the IGF2 locus, in Wilms' tumors.

A large imprinted gene cluster in human chromosome 11p15.5 has been implicated in Beckwith-Wiedemann syndrome and Wilms' tumor. We have identified a paternally expressed imprinted gene, PEG8/IGF2AS, in this locus. It is transcribed in the opposite direction to the IGF2 transcripts and some genomic regions are shared with the IGF2 gene, as in the case of the mouse imprinted Igf2as gene reported previously by T. Moore et al. As to the relationship between these genomic regions, the human and mouse genes are very similar but there is no homology in their middle parts. Interestingly, PEG8/IGF2AS and IGF2 were found to be overexpressed in Wilms' tumor samples, at levels over ten and a hundred times higher than that in normal kidney tissues neighboring the tumors, respectively. These findings indicate that PEG8/IGF2AS is a good marker of Wilms' tumor and also suggest the possibility of PEG8/IGF2AS being one of the candidate Wilms' tumor genes.

Amino Acid Sequence↗