Biomedical subjects

H Hagihara

Publications and source records attributed to H Hagihara.

At least 19 recordsLinked to original sources

PubMed2001

Effect of FR194738, a potent inhibitor of squalene epoxidase, on cholesterol metabolism in HepG2 cells.

(E)-N-ethyl-N-(6,6-dimethyl-2-hepten-4-ynyl)-3-[2-methyl-2-(3-thienylmethoxy)propyloxy]benzylamine hydrochloride (FR194738) inhibited squalene epoxidase activity in HepG2 cell homogenates with an IC50 value of 9.8 nM. In the study using intact HepG2 cells, FR194738 inhibited cholesterol synthesis from [14C]acetate with an IC50 value of 4.9 nM, and induced intracellular [14C]squalene accumulation. On the other hand, the 3-hydroxy-3-methylglutaryl (HMG)-CoA reductase inhibitor simvastatin reduced both cholesterol and squalene synthesis from [14C]acetate. Incubation with simvastatin for 18 h produced increases in HMG-CoA reductase activity in HepG2 cells, which was related to the degree of reduction in cholesterol synthesis. The HMG-CoA reductase activity increased by 13- and 19-fold at the concentrations of simvastatin that inhibited cholesterol synthesis by 65% and 82%, respectively. In contrast, FR194738 did not increase HMG-CoA reductase activity at the concentrations that inhibited cholesterol synthesis by 24% and 69%, and moderate increase (4.6-fold) was observed at the concentration that inhibited cholesterol synthesis by 90%. These results suggest that non-sterol metabolite(s) derived from mevalonate prior to the squalene epoxidation step in the cholesterol synthetic cascade have a regulatory role in the suppression of HMG-CoA reductase activity. We speculate that FR194738 inhibits cholesterol synthesis with a minimal change of the regulator(s) and would be highly effective in the treatment of hypercholesterolemia.

Benzylamines↗

PubMed2001

Purification and properties of a high-molecular-weight, alkaline exopolygalacturonase from a strain of Bacillus.

1An exopolygalacturonase [exo-PG; poly (1,4-alpha-D-galacturonide) digalacturonohydrolase, EC 3.2.1.82] was found in a culture of Bacillus sp. strain KSM-P576. The purified exo-PG had a molecular weight of approximately 115,000 and an isoelectric point of pH 4.6. The N-terminal amino acid sequence was Thr-Glu-Val-Ser-Pro-Lys-Ser-Pro-Ala-Ser-Pro-Val. Maximum activity toward polygalacturonic acid (PGA) was observed at 55 degrees C and pH 8.0 in 100 mM Tris-HCl buffer. The exo-PG was quite stable in various pH buffers between pH 6 and 12 when incubated at 30 degrees C for 1 h. Mg(2+,) Mn(2+,) Pd(2+) and Ca(2+) ions stimulated the enzyme activity. The exo-PG released digalacturonic acid from PGA, tri-, tetra-, and penta-galacturonic acids. The apparent K(m) values for oligogalacturonic acids were almost identical, and k(cat) values increased with the chain length of the substrates.

Journal Article↗

PubMed2001

Nucleotide and deduced amino acid sequences of an alkaline pullulanase from the alkaliphilic bacterium Bacillus sp. KSM-1876.

The nucleotide sequence of an alkaline pullulanase-encoding gene from alkaliphilic Bacillus sp. strain KSM-1876 was determined. The open reading frame of the gene encoded 1142 amino acids with a calculated molecular mass of 128739 Da. The alkaline pullulanase showed very limited homology (<32% identity) to previously reported debranching enzymes from prokaryotes and eukaryotes. It contained unique tandem repeats in both the N-terminal and the C-terminal regions.

Amino Acid Sequence↗

PubMed2001

Deduced amino-acid sequence of a calcium-free alpha-amylase from a strain of Bacillus: implications from molecular modeling of high oxidation stability and chelator resistance of the enzyme.

Alkaline alpha-amylase (AmyK38) from the alkaliphilic Bacillus sp. strain KSM-K38 is a unique enzyme in that it is highly chelator-resistant and oxidatively stable [Hagihara, H., Igarashi, K., Hayashi, Y., Endo, K., Ikawa-Kitayama, K., Ozaki, K., Kawai, S. & Ito, S. (2001) Appl. Environ. Microbiol. 67, 1744-1750]. This enzyme was found to contain no Ca and require Na (or monovalent cations) for manifestation of activity. The nucleotide sequence of the gene for the novel enzyme was determined, and it harbored an ORF of 1503 bp encoding the enzyme of 501 amino acids, including a 21-amino-acid signal peptide. The deduced amino-acid sequence of the mature enzyme (55 097 Da) showed moderate homology to those of alpha-amylases from Bacillus licheniformis, Bacillus stearothermophilus and Bacillus amyloliquefaciens, with approximately 63% identity. A methionine residue, which is conserved and susceptible to chemical oxidation, was replaced with leucine in AmyK38. Moreover, many conserved residues that are crucial ligands for Ca were replaced with other amino acids, thereby leading to loss of the Ca coordination geometries. By building a molecular model, we showed the calcium-independent, oxidatively stable active-site topology and structural integrity of AmyK38.

Alkalies↗

PubMed2001

Novel alpha-amylase that is highly resistant to chelating reagents and chemical oxidants from the alkaliphilic Bacillus isolate KSM-K38.

A novel alpha-amylase (AmyK38) was found in cultures of an alkaliphilic Bacillus isolate designated KSM-K38. Based on the morphological and physiological characteristics and phylogenetic position as determined by 16S ribosomal DNA gene sequencing and DNA-DNA reassociation analysis, it was suggested that the isolate was a new species of the genus Bacillus. The enzyme had an optimal pH of 8.0 to 9.5 and displayed maximum catalytic activity at 55 to 60 degrees C. The apparent molecular mass was approximately 55 kDa, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and the isoelectric point was around pH 4.2. This enzyme efficiently hydrolyzed various carbohydrates to yield maltotriose, maltohexaose, maltoheptaose, and, in addition, maltose as major end products after completion of the reaction. The activity was not prevented at all by EDTA and EGTA at concentrations as high as 100 mM. Moreover, AmyK38 was highly resistant to chemical oxidation and maintained more than 80% of its original activity even after incubation for 1 h in the presence of excess H2O2 (1.8 M).

Bacillus↗

PubMed2001

Purification and properties of a galacturonic acid-releasing exopolygalacturonase from a strain of Bacillus.

An exopolygalacturonase [exo-PGase; poly (1,4-alpha-D-galacturonide) galacturonohydrolase, EC 3.2.1.67] was found to be extracellularly produced by Bacillus sp. strain KSM-P443. The exo-PGase was purified to homogeneity, as judged by polyacrylamide gel electrophoresis, through sequential column chromatographies. The enzyme had a molecular weight of approximately 45,000 and an isoelectric point of pH 5.8. The N-terminal sequence was Ser-Met-Gln-Lys-Ile-Lys-Asp-Glu-Ile-Leu-Lys-Thr-Leu-Lys-Val-Pro-Val-Phe and had no sequence similarity to those of other pectinolytic enzymes reported to date. Maximum activity toward polygalacturonic acid (PGA) was observed at 60 degrees C and at pH 7.0 in 100 mM Tris-HCl buffer without requiring any metal ions. When the chain length of oligogalacturonic acids increased, the apparent Km for them decreased, but the kcat values increased. This is the first bacterial exo-PGase that releases exclusively mono-galacturonic acid from PGA, di-, tri-, tetra-, and penta-galacturonic acids.

Bacillus↗

PubMed2000

Aortic wall damage in mice unable to synthesize ascorbic acid.

By inactivating the gene for L-gulono-gamma-lactone oxidase, a key enzyme in ascorbic acid synthesis, we have generated mice that, like humans, depend on dietary vitamin C. Regular chow, containing about 110 mg/kg of vitamin C, is unable to support the growth of the mutant mice, which require L-ascorbic acid supplemented in their drinking water (330 mg/liter). Upon withdrawal of supplementation, plasma and tissue ascorbic acid levels decreased to 10-15% of normal within 2 weeks, and after 5 weeks the mutants became anemic, began to lose weight, and die. Plasma total antioxidative capacities were approximately 37% normal in homozygotes after feeding the unsupplemented diet for 3-5 weeks. As plasma ascorbic acid decreased, small, but significant, increases in total cholesterol and decreases in high density lipoprotein cholesterol were observed. The most striking effects of the marginal dietary vitamin C were alterations in the wall of aorta, evidenced by the disruption of elastic laminae, smooth muscle cell proliferation, and focal endothelial desquamation of the luminal surface. Thus, marginal vitamin C deficiency affects the vascular integrity of mice unable to synthesize ascorbic acid, with potentially profound effects on the pathogenesis of vascular diseases. Breeding the vitamin C-dependent mice with mice carrying defined genetic mutations will provide numerous opportunities for systematic studies of the role of antioxidants in health and disease.

Animals↗

PubMed1999

[Comparison between intermittent antegrade warm blood cardioplegia and cold crystalloid cardioplegia in patients performed reoperation for valvular heart disease].

The purpose of this study was to compare the postoperative cardiac function and systemic effects between intermittent antegrade warm blood cardioplegia and cold crystalloid cardioplegia in patients performed reoperation for chronic acquired valvular heart disease. Group I consisted of 4 patients who underwent intermittent antegrade warm blood cardioplegia (MVR in 1, MVR + TAP in 2, DVR + TAP in 1), and Group II consisted of 5 patients who underwent intermittent antegrade cold crystalloid cardioplegia (MVR + TAP in 3, TVR in 2). There were no significant differences found between the two groups in operation time, perfusion time, aortic cross clamp time, spontaneous beating rate after declamping and reperfusion time. Also doses of inotropes required during weaning was almost the same for the both groups. But 24 hours after surgery, smaller doses of inotropes (4.4 +/- 2.1 gamma/kg/min) were required for Group 1, while larger doses (7.8 +/- 2.8 gamma/kg/min) were required for Group 2 (p < 0.05). As for the postoperative complications, none was noted in Group 1, while multiple organ failure in 2, hyperbilirubinemia in 2 and complete atrioventricular block in 1 patient was noted in Group 2. The above results suggest that, for reoperations of valvular heart disease, intermittent antegrade warm blood cardioplegia is a useful and reliable method with optimum myocardial protection as well as favorable systemic effects.

Adult↗

PubMed1999

[Echo-guided extirpation of huge left atrial myxoma].

A 41-year-old male undergoing outpatient therapy for hypertension was to have a mass in the left atrium by echocardiography for screening. Transesophageal echocardiography did not identify the attachment of the tumor. The optimal approach to the tumor was determined depending on the findings of intraoperative echocardiography which well visualized the attachment of the tumor. The tumor, a large myxoma filling the most inner space of the left atrium, was extirpated via incisions in the right atrium and interatrial septum. Intraoperative echocardiography is an extremely useful method to determine the optimal approach for tumor resection. It is especially useful in cases of left atrial myxoma which has an unclear attachment on preoperative examination.

Adult↗

PubMed1999

Thermostabilization by proline substitution in an alkaline, liquefying alpha-amylase from Bacillus sp. strain KSM-1378.

alpha-Amylase (LAMY) from alkaliphilic Bacillus sp. strain KSM-1378 is a novel semi-alkaline enzyme which has 5-fold higher specific activity than that of a Bacillus licheniformis enzyme. The Arg124 in LAMY was replaced with proline by site-directed mutagenesis to increase thermostability of the enzyme. The wild-type and engineered LAMYs were very similar with respect to specific activity, kinetic values, pH-activity curve, and degree of inhibition by chelating reagents. Thermostability and structure stiffness of LAMYs as measured by fluorescence were increased by the proline substitution. The change of Arg124 to proline is assumed to stabilize the loop region involving amino acid residues from 122 to 134. This is the first report that thermostability of an alpha-amylase is improved by proline substitution.

Amino Acid Sequence↗

PubMed1998

Inhibitors of acyl-CoA:cholesterol O-acyltransferase. 3. Discovery of a novel series of N-alkyl-N-[(fluorophenoxy)benzyl]-N'-arylureas with weak toxicological effects on adrenal glands.

A series of N-alkyl-N-[(fluorophenoxy)benzyl]-N'-arylureas were prepared and evaluated for their ability to inhibit intestinal acyl-CoA:cholesterol O-acyltransferase and to inhibit accumulation of cholesteryl esters in macrophages in vitro. In vivo hypocholesterolemic activity was assessed in cholesterol-fed rats by oral administration as a dietary admixture and/or by gavage in a PEG400 vehicle. Modification of the alkyl substituent on the N'-aryl moiety and on the urea nitrogen significantly influenced macrophage assay in vitro. Toxicological study revealed a distinct relationship between macrophage assay and the toxicity observed in adrenal glands of rabbits treated with representatives of this series of compounds. Investigations utilizing the macrophage assay as an indicator for adrenal toxicity led to the identification of compounds 1g (FR190809) and 1k (FR186485, or FR195249 as its hydrochloride salt) as potent, nonadrenotoxic, orally efficacious ACAT inhibitors irrespective of the administration method.

Acetylation↗

PubMed1998

Inhibitors of acyl-CoA:cholesterol O-acyltransferase. 2. Identification and structure-activity relationships of a novel series of N-alkyl-N-(heteroaryl-substituted benzyl)-N'-arylureas.

A series of N-alkyl-N-(heteroaryl-substituted benzyl)-N'-arylurea and related derivatives represented by 2 and 3 have been prepared and evaluated for their ability to inhibit acyl-CoA:cholesterol O-acyltransferase in vitro and to lower plasma cholesterol levels in cholesterol-fed rats in vivo. Among these novel compounds, the type 3 series was superior. A pyrazol-3-yl group on the N-benzyl group of this trisubstituted urea (i.e. 3, Ar1 = pyrazol-3-yl) was identified as a heteroaromatic ring providing a good profile of biological activity. As a result of optimization of the combination with the N-alkyl group (R) and N-aryl group (Ar3), compound 3aq (FR186054) was identified as a new, orally efficacious ACAT inhibitor, which exhibited potent in vitro ACAT inhibitory activity (rabbit intestinal microsomes IC50 = 99 nM) and excellent hypocholesterolemic effects in cholesterol-fed rats, irrespective of administration mode (ED50 = 0.046 mg/kg dosed via the diet, ED50 = 0. 44 mg/kg administered by gavage in PEG400 vehicle). Moreover, a toxicological study revealed compound 3aq to be nontoxic to the adrenal glands of dogs when tested at a single dose of 10 mg/kg po.

Administration, Oral↗

PubMed1998

Synthesis, X-ray crystal structure, and biological activity of FR186054, a novel, potent, orally active inhibitor of acyl-CoA:cholesterol O-acyltransferase (ACAT) bearing a pyrazole ring.

The synthesis, single crystal X-ray structural analysis, and biological activity of FR186054 (2c), a new, potent, orally efficacious inhibitor of acyl-CoA:cholesterol O-acyltransferase (ACAT), containing a pyrazole ring are described. This compound displayed excellent in vitro efficacy, irrespective of dosing method, indicating superior characteristics compared to other ACAT inhibitors.

Administration, Oral↗

PubMed1998

Inhibitors of acyl-CoA:cholesterol O-acyltransferase (ACAT). Part 1: identification and structure-activity relationships of a novel series of substituted N-alkyl-N-biphenylylmethyl-N'-arylureas.

A series of N-alkyl-N-biphenylylmethyl-N'-arylurea and related derivatives represented by 1 have been prepared and evaluated for their ability to inhibit acyl-CoA:cholesterol O-acyltransferase in vitro and to lower plasma cholesterol levels in cholesterol-fed rats in vivo. Linking of two phenyl groups via oxygen and introduction of fluorine at appropriate positions on the biphenyl moiety improved in vitro and in vivo activity. From this series of analogs, compound 40 (FR179254), which had potent in vitro potency (rabbit intestinal microsomes IC50 = 25 nM), showed excellent plasma cholesterol-lowering activity when administered via the diet (ED50 = 0.045 mg/kg). However, the hypocholesterolemic effect of this compound was moderate when dosed by oral gavage in PEG400 as a vehicle (ED50 = 5.3 mg/kg). Modification of the N'-aryl moiety led to the identification of compound 50 (FR182980) which was efficacious in both dosing models (ED50 = 0.034 mg/kg and 0.11 mg/kg, respectively).

Anilides↗

PubMed1998

Enzymatic properties of a novel liquefying alpha-amylase from an alkaliphilic Bacillus isolate and entire nucleotide and amino acid sequences.

A novel liquefying alpha-amylase (LAMY) was found in cultures of an alkaliphilic Bacillus isolate, KSM-1378. The specific activity of purified LAMY was approximately 5,000 U mg of protein-1, a value two- to fivefold greater between pH 5 and 10 than that of an industrial, thermostable Bacillus licheniformis enzyme. The enzyme had a pH optimum of 8.0 to 8.5 and displayed maximum activity at 55 degreesC. The molecular mass deduced from sodium dodecyl sulfate-polyacrylamide gel electrophoresis was approximately 53 kDa, and the apparent isoelectric point was around pH 9. This enzyme efficiently hydrolyzed various carbohydrates to yield maltotriose, maltopentaose, maltohexaose, and maltose as major end products after completion of the reaction. Maltooligosaccharides in the maltose-to-maltopentaose range were unhydrolyzable by the enzyme. The structural gene for LAMY contained a single open reading frame 1, 548 bp in length, corresponding to 516 amino acids that included a signal peptide of 31 amino acids. The calculated molecular mass of the extracellular mature enzyme was 55,391 Da. LAMY exhibited relatively low amino acid identity to other liquefying amylases, such as the enzymes from B. licheniformis (68.9%), Bacillus amyloliquefaciens (66.7%), and Bacillus stearothermophilus (68.6%). The four conserved regions, designated I, II, III, and IV, and the putative catalytic triad were found in the deduced amino acid sequence of LAMY. Essentially, the sequence of LAMY was consistent with the tertiary structures of reported amylolytic enzymes, which are composed of domains A, B, and C and which include the well-known (alpha/beta)8 barrel motif in domain A.

Amino Acid Sequence↗

PubMed1998

Hyperexpression of the gene for a Bacillus alpha-amylase in Bacillus subtilis cells: enzymatic properties and crystallization of the recombinant enzyme.

We have constructed a new excretion vector, pHSP64, to develop a hyperexcretion system for Bacillus subtilis [Sumitomo et al., Biosci. Biotech. Biochem., 59, 2172-2175 (1995)]. The structural gene for a novel liquefying semi-alkaline alpha-amylase from the alkaliphilic Bacillus sp. KSM-1378 was amplified by PCR. It was cloned into a SalI-SmaI site of pHSP64 and the recombinant plasmid obtained was introduced into B. subtilis. The transformed B. subtilis hyperproduced the alpha-amylase activity extracellularly, corresponding to approximately 1.0 g (5 x 10(6) units) per liter of an optimized liquid culture. The recombinant enzyme was purified to homogeneity by a simple purification procedure with very high yield. No significant differences in physiochemical and catalytic properties were observed between the recombinant enzyme and the native enzyme produced by Bacillus sp. KSM-1378. The enzymatic properties of the recombinant enzyme were further examined with respect to the responses to various metal ions. The recombinant enzyme could easily be crystallized at room temperature within one day in a buffered solution of 10% (w/v) ammonium sulfate (pH 6.5).

Amino Acid Sequence↗

PubMed1997

Effects of FR145237, an acyl-CoA:cholesterol acyltransferase inhibitor, on diet-induced hypercholesterolemia in diabetic rats.

Recent studies have shown that acyl-CoA:cholesterol acyltransferase (ACAT) plays an important role in the initiation of diabetes-associated hypercholesterolemia. To confirm this hypothesis, effects of a potent ACAT inhibitor, FR145237, on diet-induced hypercholesterolemia were examined in streptozotocin (STZ)-induced diabetic rats. One-week feeding of 1% cholesterol and 0.5% cholic acid to normal rats and STZ-induced diabetic rats increased plasma cholesterol levels in both groups, and the response was more remarkable in the STZ rats than in the normal ones (1266 +/- 476 mg/dl and 146 +/- 7 mg/dl, respectively). FR145237 dose-dependently reduced the rise in plasma cholesterol levels in the STZ rats and the levels were almost normalized by treatment with 1 mg/kg/day of the compound. These results suggest that hyperresponse to dietary cholesterol was induced in the STZ rats and that ACAT is involved in the hyperresponse. The effects of FR145237 on other plasma lipids such as high density lipoprotein (HDL) cholesterol and triglyceride (TG) levels were also examined.

Animals↗

PubMed1997

[Emergency coronary artery bypass grafting using the internal thoracic artery graft after percutaneous transluminal coronary angioplasty in a patient with left main coronary artery disease associated with acute myocardial infarction].

A 66-year-old woman suffering acute myocardial infarction developed cardiogenic shock during urgent coronary angiography, which demonstrated a subtotal occlusion of the left main coronary artery and the triple-vessel coronary artery disease. The patient survived, after prompt percutaneous transluminal coronary angioplasty for the left main coronary artery disease, followed by emergency triple-vessel coronary artery bypass grafting using the internal thoracic artery graft for the left anterior descending artery. Postoperative angiography demonstrated well patent bypass grafts with good preservation of left ventricular function.

Aged↗