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H Takata

Publications and source records attributed to H Takata.

At least 19 recordsLinked to original sources
PubMed1997

Hepatocyte growth factor activator inhibitor, a novel Kunitz-type serine protease inhibitor.

Hepatocyte growth factor (HGF) activator is a serine protease that is produced and secreted by the liver and circulates in the blood as an inactive zymogen. In response to tissue injury, the HGF activator zymogen is converted to the active form by limited proteolysis. The activated HGF activator converts an inactive single chain precursor of HGF to a biologically active heterodimer in injured tissue. The activated HGF may be involved in the regeneration of the injured tissue. In this study, we purified an inhibitor of HGF activator from the conditioned medium of a human MKN45 stomach carcinoma cell line and molecularly cloned its cDNA. The sequence of the cDNA revealed that the inhibitor has two well defined Kunitz domains, suggesting that the inhibitor is a member of the Kunitz family of serine protease inhibitors. The sequence also showed that the primary translation product of the inhibitor has a hydrophobic sequence at the COOH-terminal region. Inhibitory activity toward HGF activator was detected in the membrane fraction as well as in the conditioned medium of MKN45 cells. These results suggest that the inhibitor may be produced as a membrane-associated form and secreted by the producing cells as a proteolytically truncated form.

Amino Acid Sequence↗
PubMed1997

Histomorphometric analysis of the response of rat tibiae to shape memory alloy (nitinol).

The bone reaction to nitinol (Ni-Ti), a metal with shape memory, and other materials inserted transcortically and extending into the medullary canal of rat tibiae was quantitatively assessed using an image processing system. The materials examined were implants, all of the same shape and size, composed of nitinol, pure titanium (Ti), anodic oxidized Ti (AO-Ti), a titanium alloy (Ti-6Al-4V) and pure nickel (Ni). While the other four implant materials were progressively encapsulated with bone tissues, Ni was encapsulated with connective tissues through the 168-day experimental period, and the Ni implants showed no bone contact at any time during the experimental period. Histometric analysis revealed no significant difference among the tissue reactions to Ti, AO-Ti and Ti-6Al-4V, but Ni-Ti implants showed significantly (P < 0.01) lower percentage bone contact and bone contact area than any of the other titanium or titanium alloy materials.

Alloys↗
PubMed1996

Structure of the cyclic glucan produced from amylopectin by Bacillus stearothermophilus branching enzyme.

The thermostable branching enzyme (BE, EC 2.4.1.18) from Bacillus stearothermophilus TRBE14 produces large cyclic glucans from waxy rice amylopectin similar to those obtained from amylose as described elsewhere [H. Takata, T. Takaha, S. Okada. M. Takagi, and T. Imanaka, J. Bacteriol., 178 (1996) 1600-1606]. The structure of the product (P-1) from the late-stage reaction was analyzed in detail. The weight-average degree of polymerization (dpw) of P-1 was 900. Its chain-length distribution was not significantly changed compared with that of amylopectin, although the amount of long chains (dp > 38) was slightly decreased. The cyclic component of P-1, which was isolated by the extensive action of glucoamylase, had dpw of 49. Three point five alpha-1,6 linkages were directly involved in the formation of the ring structure with several non-cyclic side chains linked to the ring. Based on these results, the action and new roles of BE are discussed.

1,4-alpha-Glucan Branching Enzyme↗
PubMed1996

Controlling substrate preference and transglycosylation activity of neopullulanase by manipulating steric constraint and hydrophobicity in active center.

The substrate specificity and the transglycosylation activity of neopullulanase was altered by site-directed mutagenesis on the basis of information from a three-dimensional structure predicted by computer-aided molecular modeling. According to the predicted three-dimensional structure of the enzyme-substrate complex, it was most likely that Ile-358 affected the substrate preference of the enzyme. Replacing Ile-358 with Trp, which has a bulky side chain, reduced the acceptability of alpha-(1-->6)-branched oligo- and polysaccharides as substrates. The characteristics of the I358W-mutated enzyme were quite different from those of wild-type neopullulanase and rather similar to those of typical starch-saccharifying alpha-amylase. In contrast, replacing Ile-358 with Val, which has a smaller side chain, increased the preference for alpha-(1-->6)-branched oligosaccharides and pullulan as substrates. The transglycosylation activity of neopullulanase appeared to be controlled by manipulating the hydrophobicity around the attacking water molecule, which is most likely used to cleave the glucosidic linkage in the hydrolysis reaction. We predicted three residues, Tyr-377, Met-375, and Ser-422, which were located on the entrance path of the water molecule might be involved. The transglycosylation activity of neopullulanase was increased by replacing one of the three residues with more hydrophobic amino acid residues; Y377F, M375L, and S422V. In contrast, the transglycosylation activity of the enzyme was decreased by replacing Tyr-377 with hydrophilic amino acid residues, Asp or Ser.

Amino Acid Sequence↗
PubMed1996

Potato D-enzyme catalyzes the cyclization of amylose to produce cycloamylose, a novel cyclic glucan.

Potato D-enzyme was purified from recombinant Escherichia coli, and its action on synthetic amylose (average Mr of 320,000) was analyzed. D-enzyme treatment resulted in a decrease in the ability of the amylose to form a blue complex with iodine. Analysis of the products indicated that the enzyme catalyzes an intramolecular transglycosylation reaction on amylose to produce cyclic alpha-1,4-glucan (cycloamylose). Confirmation of the cyclic structure was achieved by demonstrating the absence of reducing and nonreducing ends, resistance to hydrolysis by glucoamylase (an exoamylase), and by "time of flight" mass spectrometry. The degree of polymerization of cycloamylose products was determined by time of flight mass spectrometry analysis and by high-performance anion-exchange chromatography following partial acid hydrolysis of purified cycloamylose molecules and was found to range from 17 to several hundred. The yield of cycloamylose increased with time and reached >95%. D-enzyme did not act upon purified cycloamylose, but if glucose was added as an acceptor molecule, smaller cyclic and linear molecules were produced. The mechanism of the cyclization reaction, the possible role of the enzyme in starch metabolism, and the potential applications for cycloamylose are discussed.

Chromatography, Gel↗
PubMed1996

Cyclization reaction catalyzed by branching enzyme.

The action of branching enzyme (EC 2.4.l.l8) from Bacillus stearothermophilus on amylose was analyzed. The enzyme reduced the molecular size of amylose without increasing the reducing power. This result could not be explained by the normal branching reaction model. When the product was treated with glucoamylase (an exo++-type amylase), a resistant component remained. The glucoamylase-resistant component was easily digested by an endo-type alpha-amylase or by isoamylase plus glucoamylase. These results suggested that the glucoamylase-resistant component was a cyclic glucan composed of alpha-1,4- and alpha-l,6-glucosidic linkages. In other words, it was suggested that branching enzyme catalyzed cyclization of the alpha-l,4-glucan chain of the amylose molecule to form an alpha-l,6-glucosidic linkage, thereby forming two smaller molecules. Mass spectrometry also supported the cyclic nature of the product.

1,4-alpha-Glucan Branching Enzyme↗
PubMed1995

[The relationship between blood sugar control and vascular complications in elderly diabetic patients--investigative study in 17 hospitals of Kochi Prefecture. Kochi Working Group on Diabetes Mellitus].

The aim of this study was to clarify whether the control state of fasting blood sugar can influence the occurrence of diabetic microangiopathy and macroangiopathy even in elderly patients with diabetes mellitus. In Kochi Prefecture 18 internal physicians participated in evaluating clinical courses of 898 patients, consisting of 466 males and 432 females, for an average of 69 months. Elderly cases aged 65 years or more old (group 1) consisted of patients who were aged 71.8 +/- 5.2 years old (M +/- SD). The average age of 481 adult cases under 65 years of age (group II) was 54.4 +/- 8.4 years old. Between the good and poor control groups, there was no difference in terms of blood pressure, body mass index (BMI) and serum lipids. Arteriosclerotic diseases such as myocardial infarction, cerebral infarction and arteriosclerosis obliterans appeared about as frequently in both the good and the poor control groups, while microangiopathies such as retinopathy, nephropathy and neuropathy were significantly more frequent in the poor control group compared to the good control group. The same tendency concerning these complications was seen in group II. Concerning treatment, diet treatment without drug treatment was significantly more frequent in the good control group compared to the poor control group, while hypoglycemic agents and subcutaneous insulin injection were used more often in the poor control group, the more severe state of diabetes mellitus in the latter group. Concerning the main reasons for good control, successful diet treatment was cited most often, followed by regular intake of medications. On the other hand disturbed diet treatment was the most frequent reason for poor control, indicating the strategic importance of diet treatment. Arteriosclerotic diseases were found more often in group I than group II, while the frequency of microangiopathies was similar. Concerning sexes, male patients tended to suffer more often from arteriosclerotic diseases than female patients, but the frequency of microangiopathy was similar. From the above findings it was concluded that poor control of fasting blood sugar level was related to microangiopathies in both non-elderly adult and elderly patients.

Aged↗
PubMed1994

Properties and active center of the thermostable branching enzyme from Bacillus stearothermophilus.

Although the branching enzyme (EC 2.4.1.18) is a member of the alpha-amylase family, the characteristics are not understood. The thermostable branching enzyme gene from Bacillus stearothermophilus TRBE14 was cloned and expressed in Escherichia coli. The branching enzyme was purified to homogeneity, and various enzymatic properties were analyzed by our improved assay method. About 80% of activity was retained when the enzyme was heated at 60 degrees C for 30 min, and the optimum temperature for activity was around 50 degrees C. The enzyme was stable in the range of pH 7.5 to 9.5, and the optimum pH was 7.5. The nucleotide sequence of the gene was determined, and the active center of the enzyme was analyzed by means of site-directed mutagenesis. The catalytic residues were tentatively identified as two Asp residues and a Glu residue by comparison of the amino acid sequences of various branching enzymes from different sources and enzymes of the alpha-amylase family. When the Asp residues and Glu were replaced by Asn and Gln, respectively, the branching enzyme activities disappeared. The results suggested that these three residues are the catalytic residues and that the catalytic mechanism of the branching enzyme is basically identical to that of alpha-amylase. On the basis of these results, four conserved regions including catalytic residues and most of the substrate-binding residues of various branching enzymes are proposed.

1,4-alpha-Glucan Branching Enzyme↗
PubMed1993

Toxicokinetic approach for evaluating respiratory depression effect of aminoglycoside antibiotics: species differences in drug susceptibility.

The respiratory depression effect of aminoglycoside antibiotics was studied by a toxicokinetic approach, and species differences in drug susceptibility were elucidated based on plasma concentrations. An allometric relationship was obtained between total body clearance of arbekacin, a novel aminoglycoside antibiotic, and animal body weight. The power was 0.714, less than unity, which means smaller animals have higher ability to eliminate the drug from the body and need higher doses to attain a certain steady-state plasma concentration. When the infusion rate of arbekacin was altered, the total dose required to cause the toxicologic endpoint for respiratory depression (60 per cent loss of respiratory rates) changed greatly, but the plasma concentration of arbekacin at the toxicologic endpoint remained at almost a constant level. The concentration at the toxicologic endpoint was similar for all of the animal species examined and was 650-950 micrograms ml-1, even though the total dose required to cause the toxicologic endpoint varied greatly among the animal species. These findings suggest that the toxicologic effect compartment for respiratory depression is indistinguishable from the plasma compartment, and that species differences in the total dose are due to differences in pharmacokinetics of the drug, mainly in the total body clearance, but not to differences in intrinsic susceptibility to the drug.

Aminoglycosides↗
PubMed1993

Identification of alloantisera reacting with HLA-C blank (Cx52) using a mouse L-cell transfected with the HLA-Cw*1201 allele.

The HLA-C locus frequently has a serologically undefined "blank" (CwBL) specificity. A cDNA clone derived from the HLA-C gene with a blank specificity (Cx52) strongly associated with the most common haplotype in a Japanese population, A24-CwBL-B52-DR2-DQ6-DP9, has been recently cloned and sequenced in our laboratory and officially designated Cw*1201 as an allelic name, indicating that the inability to define the HLA-C antigen serologically in this haplotype is not due to an HLA-C antigen gene deletion or mutation, but to the absence of typing sera. In this paper, a mouse L-cell transfectant expressing this Cw*1201 gene product was constructed and employed for screening of alloantisera recognizing the HLA-C antigen with the Cw*1201 specificity. Two alloantisera against Cw*1201 were thus identified and characterized using HLA homozygous B-cell lines and local panel PBL cells, indicating that a transfectant expressing a single HLA provides an efficient screening system for collection of HLA-typing sera, especially reacting with serologically unclassifiable "blank" antigens.

Alleles↗
PubMed1993

[Effect of AS-35 aerosol on bronchoconstriction induced by specific antigens in macacus rhesus monkeys].

In a previous in vitro study, 9-[(4-acetyl-3-hydroxy-2-n-propylphenoxy) methyl]-3-(1H-tetrazol-5-yl)-4H- pyrido[1,2-a]pyrimidin-4-one (AS-35) was shown to have an inhibitory effect on antigen-induced mediator release and an antagonistic effect on leukotriene C4 and D4 receptors. In the present study, therefore, we investigated the effect of AS-35 aerosol on allergen-induced bronchoconstriction, using 6 female Macacus rhesus monkeys sensitized with DNP-Ascaris extracts (DNP-As). After treatment with an inactive placebo, inhalation challenge with DNP-As increased total lung resistance and decreased dynamic lung compliance dose-dependently 1 week after sensitization with DNP-As. Treatment with AS-35 aerosol, however, significantly inhibited allergen-induced bronchoconstriction dose-dependently 2 weeks after the sensitization. The inhibitory effect was about ten times more potent than that of DSCG. Because we confirmed that DNP-As evoked almost the same bronchoconstriction 1 and 2 weeks after sensitization and also that AS-35 did not inhibit histamine-induced bronchoconstriction at all, we inferred that AS-35 diminished allergen-induced bronchoconstriction by inhibiting allergen-induced mediator release from the cells in the airway.

Aerosols↗
PubMed1992

Action of neopullulanase. Neopullulanase catalyzes both hydrolysis and transglycosylation at alpha-(1----4)- and alpha-(1----6)-glucosidic linkages.

The transglycosylation reaction catalyzed by neopullulanase was analyzed. Radioactive oligosaccharides were produced when the enzyme acted on maltotriose in the presence of [U-14C]glucose. Some of the radioactive oligosaccharides had only alpha-(1----4)-glucosidic linkages, but others were suggested to have alpha-(1----6)-glucosidic linkages. The existence of alpha-(1----6)-glucosidic linkages in the products from maltotriose with neopullulanase was proven by proton NMR spectroscopy and methylation analysis. We previously reported that the one active center of neopullulanase catalyzes the hydrolysis of alpha-(1----4)- and alpha-(1----6)-glucosidic linkages (Kuriki, T., Takata, H., Okada, S., and Imanaka, T. (1991) J. Bacteriol. 173,6147-6152). These facts proved that neopullulanase catalyzed all four types of reactions: hydrolysis of alpha-(1----4)-glucosidic linkage, hydrolysis of alpha-(1----6)-glucosidic linkage, transglycosylation to form alpha-(1----4)-glucosidic linkage, and transglycosylation to form alpha-(1----6)-glucosidic linkage. The four reactions are typically catalyzed by alpha-amylase, pullulanase, cyclomaltodextrin glucanotransferase, and 1,4-alpha-D-glucan branching enzyme, respectively. These four enzymes have some structural similarities to one other, but reactions catalyzed by the enzymes are considered to be distinctive: the four reactions are individually catalyzed by each of the enzymes. The experimental results obtained from the analysis of the reaction of the neopullulanase exhibited that the four reactions can be catalyzed in the same mechanism.

1,4-alpha-Glucan Branching Enzyme↗
PubMed1992

Establishment and characterization of a cell line, KaMi, from human lung large cell carcinoma.

A cell line of human lung large cell carcinoma (LCC) was established directly from the metastatic skin tumor tissue. The clinical course of the patient who carried this carcinoma was peculiar; generalized lymphadenopathy, histologically resembling Hodgkin's disease, was found as the first clinical symptom. The lung tumor was not discovered until the time of autopsy. This cell line (KaMi) grew adherent to culture vessels with the population doubling time of 20.6h, formed colonies in soft agars with efficiency of 22.6%, and formed tumors in athymic nude mice. The authenticity of KaMi was confirmed by chromosomal analysis and isoenzyme patterns. KaMi cells bore a strong resemblance to the original tumor cells which were composed of small spindle cells, large polygonal cells, and multinucleated giant cells. Immunohistochemically, KaMi cells showed a weak tendency to differentiate to squamous cells, and these immunohistochemical reactivities were almost compatible to those of the original tumor cells, but ultrastructurally, KaMi cells were more immature than the original ones. Treatment with several reagents could not augment a differentiation of KaMi cells. Cytokeratin profiles showed a tendency of squamous cell differentiation. KaMi cells may aid in elucidating the pathogenesis and biology of LCC and its relationship to other lung tumors.

Animals↗
PubMed1992

[Influence of systolic left ventricular blood flow direction on genesis of senile calcification of the aortic valve].

To assess the factors which may initiate and accelerate degenerative senile calcification of the aortic valve, two-dimensional echocardiograms and the clinical characteristics of 259 consecutive cases with senile calcification of the aortic valve were studied. The results were compared with those of similar studies among 186 consecutive cases with the normal aortic valves. An aortic cusp with an area of increased echo greater than 3 mm in width and with decreased pliability was regarded as calcified. Among patients with calcification of one aortic cusp, 114 exhibited calcification of a noncoronary cusp, 17 calcification of the left coronary cusp and 3 calcification of the right coronary cusp (p < 0.001). Among patients with calcification of 2 aortic cusps, 39 had calcification of a noncoronary and left coronary cusps, 3 calcification of the left and right coronary cusps and 16 calcification of the right and noncoronary cusps (p < 0.001). In patients with calcification of their aortic valves, the end-diastolic angle between the interventricular septum and the ascending aorta was 102 +/- 10 degrees; whereas, it was 89 +/- 10 degrees in the control group (p < 0.001). There were no differences in frequency of aortic root calcification, mitral annular calcification, hypertension, ischemic heart disease, hyperlipidemia, hyperuricemia, or hyperglycemia, between patients with and without calcification of their aortic valves. Of the female patients ranging in age from 65 to 74 years, 88% in those with calcification of 3 cusps and 30% in those with calcification of one cusp (p < 0.05) had mitral annular calcification.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1991

HLA class II antigens are associated with Japanese pemphigus patients.

We investigated the HLA class II antigens in 30 Japanese cases of pemphigus, 17 cases of pemphigus vulgaris (PV) and 13 cases of pemphigus foliaceus (PF), by both serologic and restriction fragment length polymorphism (RFLP) analyses. We detected two major haplotypes susceptible to PV, i.e., DRw12-DQw7 and DRw6-DQw5. In contrast, DR2 was absent in PV. RFLP analyses showed that DRw6 PV patients had a disease-associated restriction fragment representing DQw5, the same association as that found in DRw6 Jewish PV patients. However, DRw12 Japanese PV patients had DQw7, whereas DR4 Jewish PV patients had DQw8. On the other hand, all 13 PF patients were serologically typed for DQw1, which could not be further subdivided into DQw5 by RFLP analyses. These results suggest that Japanese and Jewish PV patients may be immunogenetically closely related to each other, but Japanese PV patients appear to be immunogenetically different from Japanese PF patients.

Autoantibodies↗
PubMed1991

Analysis of the active center of Bacillus stearothermophilus neopullulanase.

The active center of the neopullulanase from Bacillus stearothermophilus was analyzed by means of site-directed mutagenesis. The amino acid residues located in the active center of the neopullulanase were tentatively identified according to a molecular model of Taka-amylase A and homology analysis of the amino acid sequences of neopullulanse, Taka-amylase A, and other amylolytic enzymes. When amino acid residues Glu and Asp, corresponding to the putative catalytic sites, were replaced by the oppositely charged (His) or noncharged (Gln or Asn) amino acid residue, neopullulanase activities toward alpha-(1----4)- and alpha-(1----6)-glucosidic linkages disappeared. When the amino acids corresponding to the putative substrate-binding sites were replaced, the specificities of the mutated neopullulanases toward alpha-(1----4)- and alpha-(1----6)-glucosidic linkages were obviously different from that of the wild-type enzyme. This finding proves that one active center of neopullulanase participated in the dual activity toward alpha-(1----4)- and alpha-(1----6)-glucosidic linkages. Pullulan is a linear glucan of maltotriosyl units linked through alpha-(1----6)-glucosidic linkages. The production ratio of panose from pullulan was significantly increased by using the mutated neopullulanase which exhibited higher specificity toward the alpha-(1----4)-glucosidic linkage. In contrast, the production ratio of panose was obviously decreased by using the mutated neopullulanse which exhibited higher specificity toward the alpha-(1----6)-glucosidic linkage.

Amino Acid Sequence↗
PubMed1990

Binding site of omeprazole in hog gastric H+,K(+)-ATPase.

Omeprazole transforms into an active compound in an acidic environment, which is able to modify a sulfhydryl group of gastric H+,K(+)-ATPase. Omeprazole was transformed into a strongly fluorescent molecule by UV-light irradiation (excitation wavelength = 290 nm, emission wavelength = 335 nm). The omeprazole-modified residue of hog H+,K(+)-ATPase was estimated by the fluorescence of the omeprazole moiety and limited tryptic digestion of the enzyme. Among the four main tryptic digested subfragments, omeprazole was bound to the 67, 42 and 32-kDa subfragments, but not to the 52-kDa subfragment. Taking the amino acid sequence of this ATPase into consideration, we propose that omeprazole specifically binds with Cys322 in hog H+,K(+)-ATPase (Cys321 in rat).

Adenosine Triphosphatases↗