Biomedical subjects

A Hara

Publications and source records attributed to A Hara.

At least 307 records · Page 17Linked to original sources

PubMed1995

Positive inotropic effect of the novel forskolin derivative 6-(3-dimethylaminopropionyl)forskolin hydrochloride.

The effect of NKH477 (6-(3-dimethylaminopropionyl)forskolin hydrochloride, CAS 138605-00-2), a novel water-soluble forskolin derivative, on the energy metabolism of the heart was examined and compared with that of dobutamine. The isolated rat heart was perfused with Krebs-Henseleit bicarbonate buffer with a gas mixture containing 95% O2 + 5% CO2 according to the Langendorff's technique. NKH477 (1 or 10 mumol/l) increased maximum rate of rise of left ventricular pressure (LVdP/dtmax) (positive inotropic action), heart rate (positive chronotropic action), and coronary flow. On the other hand, dobutamine (50 or 500 nmol/l) exhibited the positive inotropic action only. Both NKH477 (10 mumol/l) and dobutamine (500 nmol/l) increased the tissue adenosine monophosphate level, and decreased the tissue creatine phosphate level (a decrease in energy store) in the heart. Nevertheless, neither NKH477 (1 or 10 mumol/l) nor dobutamine (50 or 500 nmol/l) modified the tissue adenosine triphosphate level and the value of energy charge potential, an index of myocardial energy state. These results suggest that NKH477 produces both positive inotropic and positive chronotropic actions, while it does not disturb myocardial energy state, although it decreases the energy store.

Adrenergic beta-1 Receptor Agonists↗

PubMed1995

Hypothermic prevention of nuclear DNA fragmentation in gerbil hippocampus following transient forebrain ischemia.

The protective effect of hypothermia on DNA fragmentation following transient forebrain ischemia in mongolian gerbils was investigated. The DNA fragmentation demonstrated in situ in gerbil hippocampal CA1 was compared between intra- and post-ischemic hypothermia. Intra-ischemic hypothermia prevented the DNA fragmentation in hippocampal CA1 completely, while severe DNA damage was observed in post-ischemic hypothermia group. the degree of DNA fragmentation of hippocampal CA1 in the post-ischemic hypothermia group was equal to that in the ischemic control group. The results suggest that hypothermia during a transient forebrain ischemia exerts a protective effect on the post-ischemic hippocampal damage by preventing the DNA fragmentation in CA1 neurons.

Animals↗

PubMed1994

Reduction of prostaglandin D2 to 9 alpha,11 beta-prostaglandin F2 by a human liver 3 alpha-hydroxysteroid/dihydrodiol dehydrogenase isozyme.

Prostaglandin (PG) specificity of two 3 alpha-hydroxysteroid/dihydrodiol dehydrogenase isozymes, DD2 and DD4, of human liver was examined. DD2 exhibited NADPH-linked reductase activity for 9-,11- and 15-ketoprostaglandins at a pH optimum of 6.0, whereas DD4 reduced only 15-ketoprostaglandin F2 alpha. DD2 showed the highest Vmax/Km value for PGD2 of the PG substrates, and the reduced product of PGD2 was identified to 9 alpha,11 beta-PGF2 by gas chromatography-mass spectrometry. In the reverse reaction with NADP+ as a cofactor, the two enzymes slowly oxidized several PGs with 9-, 11- and/or 15-hydroxy groups, except that DD2 showed high activity for 9 alpha,11 beta-PGF2 at a pH optimum of 10.0. The Km and Vmax values of DD2 for PGD2 were 57 microM and 250 nmol/min per mg, respectively, at pH 7.0 and 37 degrees C, and the respective values for 9 alpha,11 beta-PGF2 were 72 microM and 10 nmol/min per mg. PGD2 11-ketoreductase activity in human liver cytosol was recovered in 30-75% saturated ammonium sulfate fraction. More than 77% of the PGD2 11-ketoreductase activity in the ammonium sulfate fraction was immunoprecipitated by antibodies against DD2, and inhibited by known inhibitors of the enzyme. These results suggest that DD2 is a major soluble PGD2 11-ketoreductase species in human liver.

3-Hydroxysteroid Dehydrogenases↗

PubMed1994

Chemoprevention of 4-nitroquinoline 1-oxide-induced oral carcinogenesis by dietary curcumin and hesperidin: comparison with the protective effect of beta-carotene.

The modifying effects of two natural products, curcumin and hesperidin, given during the initiation and postinitiation phases of oral carcinogenesis initiated with 4-nitroquinoline 1-oxide (4-NQO) were investigated in male F344 rats and compared with that of beta-carotene. At 6 weeks of age, rats were divided into experimental and control groups and fed the diet containing beta-carotene, hesperidin, or curcumin at a dose of 0.5 g/kg diet (500 ppm). At 7 weeks of age, all animals except those treated with each test chemical alone and control groups were given 4-NQO (20 ppm) in the drinking water for 8 weeks to induce oral cancer. Seven days after the 4-NQO exposure, groups of animals fed the diets containing test chemicals were switched to the basal diet and continued on this diet until the end of the study. Starting 1 week after the stop of 4-NQO exposure, the groups given 4-NQO and a basal diet were switched to the diets containing beta-carotene, hesperidin, and curcumin and maintained on these diets for 22 weeks. The other groups consisted of rats given 500 ppm beta-carotene, hesperidin, or curcumin alone or untreated rats. All animals were necropsied at the termination of the experiment (week 32). The incidences of tongue neoplasms and preneoplastic lesions, polyamine levels in the tongue tissue, and cell proliferation activity estimated by bromodeoxyuridine-labeling index and by morphometric analysis of silver-stained nucleolar organizer region proteins were compared among the groups. Feeding of curcumin and beta-carotene during the initiation and postinitiation phases and hesperidin at the initiation stage caused a significant reduction in the frequency of tongue carcinoma (41-91% reduction, P < 0.05) and the order of chemopreventive efficacy was curcumin > beta-carotene > hesperidin. The incidences of oral preneoplasia in rats fed the diets mixed with these compounds were also decreased (P < 0.05). There were no such lesions in rats treated with test compounds alone or those in an untreated control group. Dietary administration of these compounds significantly decreased the labeling index of bromodeoxyuridine and the number and area of silver-stained nucleolar organizer region proteins per cell nucleus that are proliferation biomarkers, of the tongue squamous epithelium (P < 0.05). In addition, polyamine levels in the oral mucosa were lowered in rats treated with 4-NQO and three test compounds when compared to those give 4-NQO alone (P < 0.05).(ABSTRACT TRUNCATED AT 400 WORDS)

4-Hydroxyaminoquinoline-1-oxide↗

PubMed1994

Chemoprevention of 4-nitroquinoline 1-oxide-induced oral carcinogenesis by dietary protocatechuic acid during initiation and postinitiation phases.

The modifying effects of three doses of dietary protocatechuic acid (PCA) given the initiation and postinitiation phases of oral carcinogenesis initiated with 4-nitroquinoline 1-oxide (4-NQO) were investigated in male F344 rats. At 6 weeks of age, rats were divided into experimental and control groups and fed the diet containing PCA at various doses of 0 g/kg diet (basal diet alone), 0.5 g/kg diet (500 ppm), 1 g/kg diet (1000 ppm), and 2 g/kg diet (2000 ppm). At 7 weeks of age, all animals except PCA alone and control groups were given 4-NQO (20 ppm) in the drinking water for 8 weeks to induce oral cancer. Seven days after the 4-NQO exposure, groups of animals fed the PCA diets were switched to the basal diet and continued on this diet until the end of the study. Starting 1 week after the end of 4-NQO exposure, the groups given 4-NQO and a basal diet were switched to the diets containing PCA and maintained on these diets for 22 weeks. The other groups consisted of rats given 2000 ppm PCA alone or untreated rats. All animals were necropsied at the termination of the experiment (week 32). The incidences of tongue neoplasms and preneoplastic lesions, polyamine levels in the tongue tissue, and cell proliferation activity estimated by bromodeoxyuridine-labeling index and by morphometric analysis of silver-stained nucleolar organizer regions' protein were compared among the groups. Feeding of PCA at all doses during initiation or postinitiation phase significantly decreased the development of tongue neoplasms (squamous cell papilloma and carcinoma) and preneoplasia (hyperplasia and dysplasia) (P < 0.05). There were no such lesions in rats treated with 2000 ppm PCA alone or those in an untreated control group. Dietary administration of PCA also caused significant decreases in the labeling index of bromodeoxyuridine and the number and area of silver-stained nucleolar organizer regions per cell nucleus, known as cell proliferation indices, of the tongue squamous epithelium (P < 0.05). In addition, PCA exposure during either initiation or postinitiation phase decreased polyamine levels in the oral mucosa (P < 0.05). These results clearly indicated that PCA inhibited rat oral carcinogenesis in both initiation and postinitiation phases, when administered in these respective phases together with or following treatment with 4-NQO, and such inhibition might be related to suppression of cell proliferation by PCA.

4-Nitroquinoline-1-oxide↗

PubMed1994

Molecular cloning of two human liver 3 alpha-hydroxysteroid/dihydrodiol dehydrogenase isoenzymes that are identical with chlordecone reductase and bile-acid binder.

Human liver contains two dihydrodiol dehydrogenases, DD2 and DD4, associated with 3 alpha-hydroxysteroid dehydrogenase activity. We have raised polyclonal antibodies that cross-reacted with the two enzymes and isolated two 1.2 kb cDNA clones (C9 and C11) for the two enzymes from a human liver cDNA library using the antibodies. The clones of C9 and C11 contained coding sequences corresponding to 306 and 321 amino acid residues respectively, but lacked 5'-coding regions around the initiation codon. Sequence analyses of several peptides obtained by enzymic and chemical cleavages of the two purified enzymes verified that the C9 and C11 clones encoded DD2 and DD4 respectively, and further indicated that the sequence of DD2 had at least additional 16 residues upward from the N-terminal sequence deduced from the cDNA. There was 82% amino acid sequence identity between the two enzymes, indicating that the enzymes are genetic isoenzymes. A computer-based comparison of the cDNAs of the isoenzymes with the DNA sequence database revealed that the nucleotide and amino acid sequences of DD2 and DD4 are virtually identical with those of human bile-acid binder and human chlordecone reductase cDNAs respectively.

3-Hydroxysteroid Dehydrogenases↗

PubMed1994

Purification and characterization of a novel dimeric 20 alpha-hydroxysteroid dehydrogenase from Tetrahymena pyriformis.

Tetrahymena pyriformis was found to exhibit high NADPH-dependent 20-oxosteroid reductase activity that converted 17 alpha-hydroxyprogesterone into 17 alpha,20 alpha-dihydroxypregn-4-en-3-one. The enzyme was purified 400-fold from the cytosolic fraction. The purified enzyme with a specific activity of 6.4 mumol/min per mg of protein had an isoelectric point of 4.9 and M(r) of 68,000, and was composed of two subunits of equal size. The N-terminal sequence was determined to be LAKTVPLNDGTNFPIFGG. The enzyme reduced pregnanes and pregnanes possessing a 17 alpha-hydroxy group to a greater extent than those without the hydroxy group, and oxidized 20 alpha-hydroxy groups of the steroids in the presence of NADP+. The Km values for 17 alpha-hydroxyprogesterone and 17 alpha-hydroxypregnenolone were 2.9 and 3.4 microM respectively. Although the enzyme was inactive towards androgens and oestrogens with 3- or 17-oxo groups, it reduced several nonsteroidal carbonyl compounds and oxidized trans-benzene dihydrodiol. The enzyme activity was inhibited by synthetic oestrogens, barbiturates, aldose reductase inhibitors and quercitrin. Thus, this enzyme is a novel form of 20 alpha-hydroxysteroid dehydrogenase (EC 1.1.1.149) which structurally and functionally differs from the mammalian and bacterial enzymes.

17-alpha-Hydroxypregnenolone↗

PubMed1994

Ultrastructural localization of carbonyl reductase in mouse lung.

The immunocytochemical localization of tetrameric carbonyl reductase in the mouse lung was determined by an electron-microscopical immunogold procedure using monospecific antibodies against the enzyme. The labelling of carbonyl reductase was observed within the mitochondria of the ciliated and non-ciliated cells of the bronchioles and the type II alveolar pneumocytes, and the density of labelling in the non-ciliated cells was higher than those in the other cells. No significant labelling was detected over other compartments of the epithelial cells. The labelling was undetectable in the type I alveolar cells, alveolar macrophages and connective tissue cells of the lung. These results clearly indicate the localization of carbonyl reductase to the mitochondrial matrix of these epithelial cells, of which the non-ciliated bronchiolar cells contained particularly high amounts of the enzyme.

Alcohol Oxidoreductases↗

PubMed1994

Decreased inner retinal activity in branch retinal vein occlusion.

The electroretinogram, electro-oculogram and electroretinogram oscillatory potential all reflect the mass activity of the retina. The electroretinogram usually remains normal after branch retinal vein occlusion, whereas the electro-oculogram and oscillatory potential often show abnormalities. These tests thus have a differential sensitivity to branch retinal vein occlusion. However, whether the inner layer of the retina is affected in branch retinal vein occlusion has not been determined. In this study, conventional electroretinographic and oscillatory potential data were compared in 34 patients with branch retinal vein occlusion, while electroretinographic and electro-oculographic data were compared in 30 patients with branch retinal vein occlusion, in an attempt to determine whether the inner retina was affected in this disorder. None of the conventional electroretinographic variables showed any significant difference between the eyes with branch retinal vein occlusion and the fellow eyes. In the oscillatory potential test, however, the sum of the amplitudes of O1, O2, O3 and O4 showed a significant difference (p < 0.02). In addition, the light peak-dark trough ratio and the light peak showed a significant difference in the electro-oculogram (p < 0.05 and p < 0.05, respectively). Since the oscillatory potential and the electro-oculogram light rise potential reflect the activity of the inner retina, our data suggest that the inner retina was affected by branch retinal vein occlusion and that these variables are more sensitive indicators than the electroretinogram.

Acute Disease↗

PubMed1994

A single cell gel electrophoresis technique for the detection of DNA damage induced by ACNU, an alkylating agent or irradiation in murine glioma cell lines.

A simple and convenient technique for in situ quantification of DNA damage induced by 1-(4-amino-2-methyl-5-pyrimidinyl) methyl-3-(2-chloro-ethyl)-3-nitrosourea hydrochloride (ACNU) an alkylating agent, or irradiation was demonstrated in C6 glioma cells using a single cell gel electrophoresis. Treatment with ACNU or irradiation caused a dose dependent DNA damage which was detected by measuring the length of migration of fragmentary DNA in individual cells. Wild type C6 cells treated with ACNU (0, 10, 30, 60 micrograms ml-1) for one hour showed longer distance of migration of DNA than the ACNU-resistant subtype cells (C6R), indicating that ACNU-sensitive C6 cells were more vulnerable to ACNU than C6R cells. The results of DNA migration in C6 and C6R cells treated with ACNU were consistent with that from MTT assay which had been regarded as a standard method for chemosensitivity test. Furthermore, a time course study for DNA repair activity of C6 and C6R cells was also performed by measuring the length of DNA migration after incubation (0, 15, 30, 60, 120 min) of cells treated with 60 micrograms ml-1 ACNU. C6R cells repaired DNA damage more rapidly than C6 cells. In addition, the technique was also used to measure the DNA damage in C6 cells exposed to 0, 2, 6, 8, 10 Gy of x-ray irradiation, and a dose-dependent DNA migration after radiation injury was observed. This technique appears to be simple and useful for assessing chemosensitivity or radiosensitivity in individual glioma cells.

Alkylating Agents↗

PubMed1994

Stereospecificity of trans-dihydrodiol oxidation by dimeric and monomeric dihydrodiol dehydrogenases from mammalian tissues.

The stereochemical course in the enzymatic oxidation of trans-dihydrodiols of benzene and naphthalene by dimeric dihydrodiol dehydrogenase of monkey kidney was compared with that by monomeric dihydrodiol dehydrogenase of rat liver. The monkey kidney and rat liver enzymes each oxidized about half of the racemic dihydrodiol of benzene added to the reaction mixture, but almost all the substrate was disappeared in the reaction mixture containing both enzymes. The CD spectra of the unreacted dihydrodiols of benzene and naphthalene in reaction mixtures containing the rat liver enzyme showed the negative sign of Cotton effect, while those in reaction mixtures containing the monkey kidney enzyme gave the positive sign of Cotton effect. Thus, the monkey kidney dimeric enzyme selectively oxidized (-)-[1R,2R]-dihydrodiols of aromatic hydrocarbons, in contrast to the stereo-specificity of the rat liver enzyme for the (+)-[1S,2S]-isomers. The (+)-[1S,2S]- and (-)-[1R,2R]-dihydrodiols of benzene were separately prepared from the racemic form by using the two enzymes, and were used as substrates to determine the stereospecificity of dihydrodiol dehydrogenases from other mammalian tissues. The dimeric enzymes from pig liver and rabbit lens also exhibited specificity for the (-)-isomer, which was opposite to that of the monomeric enzymes from human and mouse liver, although aldehyde reductase and aldose reductase oxidized both (+)- and (-)-isomers.

Alcohol Oxidoreductases↗

PubMed1994

Purification and characterization of dimeric dihydrodiol dehydrogenase from dog liver.

High NADP(+)-linked dihydrodiol dehydrogenase activity was detected in dog liver cytosol, from which a dimeric enzyme composed of M(r) 39,000 subunits was purified to homogeneity. The enzyme oxidized trans-cyclohexanediol, and trans-dihydrodiols of benzene and naphthalene, the [1R,2R]-isomers of which were selectively oxidized. In the reverse reaction in the presence of NADPH as a coenzyme, the enzyme reduced alpha-dicarbonyl compounds, such as methylglyoxal, 3-deoxyglucosone, and diacetyl, and some compounds with a carbonyl group, such as glyceraldehyde, lactaldehyde, and acetoin. 4-Hydroxyphenylketones and ascorbates inhibited the enzyme. The results of steady-state kinetic analyses indicated that the reaction proceeds through an ordered bi bi mechanism with the coenzyme binding to the free enzyme, and suggested that the inhibitors bind to the enzyme-NADP+ binary complex. The dimeric enzyme was detected in liver and kidney of dog, and was immunochemically similar to the dimeric enzymes from monkey kidney, rabbit lens, and pig liver. The sequences (total 127 amino acid residues) of eight peptides derived on enzymatic digestion of the dog liver enzyme did not show significant similarity with the primary structures of members of the aldo-keto reductase and short chain dehydrogenase superfamilies, which include monomeric dihydrodiol dehydrogenases and carbonyl reductase, respectively.

Animals↗

PubMed1994

The gene encoding a new mitogenic factor in a Streptococcus pyogenes strain is distributed only in group A streptococci.

We recently cloned a gene encoding a new mitogenic factor (MF) from Streptococcus pyogenes NY-5. In the present study, we determined the distribution of this MF gene (mf) by PCR based upon its sequence. Of 371 streptococcal group A strains isolated from clinical specimens, 370 (99.7%) were positive for mf. The strain that was negative for the MF gene was also negative for the streptolysin O gene (slo). Some streptococcal strains belonging to groups C and G were negative for mf but positive for slo. Group B strains were negative for both. Furthermore, we examined the presence of mf in 54 strains belonging to 28 families and found mf only in group A streptococci. These results indicate that mf is distributed specifically in group A streptococci and the presence of mf in clinical samples strongly suggests infection with group A streptococci.

Bacterial Proteins↗

PubMed1994

Comparison of DNA methylation patterns among mouse cell lines by restriction landmark genomic scanning.

Restriction landmark genomic scanning (RLGS) is a novel method which enables us to simultaneously visualize a large number of loci as two-dimensional gel spots. By this method, the status of DNA methylation can efficiently be determined by monitoring the appearance or disappearance of spots by using a methylation-sensitive restriction enzyme. In the present study, using RLGS with NotI, we examined, in comparison with a brain RLGS profile, the status of DNA methylation of more than 900 loci among three types of mouse cell lines: the embryonal carcinoma cell line P19, the stable mesenchymal cell line 10T1/2, and our established neuroepithelial (EM) cell lines. We found that the relative numbers of RLGS spots which appeared were less than 3.3% of those surveyed in all cell lines examined. However, 5 to 14% of spots disappeared, the numbers increasing with an increase in the length of the culture period, and many spots were commonly lost in 10T1/2 and in three EM cell lines. Thus, for these cell lines, many more spots disappeared than appeared. However, the numbers of spots disappearing and appearing were well balanced, and the ratio in P19 cells was almost equal to that in liver cells in vivo. These RLGS experimental observations suggested that permanent cell lines such as 10T1/2 are hypermethylated and that our newly established EM cell lines are also becoming heavily methylated at common loci. On the other hand, methylation and demethylation seem to be balanced in P19 cells in a manner similar to that in in vivo liver tissue.

Aneuploidy↗

PubMed1994

Evaluation of post-ischemic myocardial metabolism by 1H-magnetic resonance spectroscopy in the rabbit heart.

To assess myocardial metabolism during ischemia and reperfusion, 36 rabbits were divided into 4 groups; a control group (Control), an ischemia group in which the circumflex branch was ligated for 30 min (Ischemia), a 5 min reperfusion group (5-RP) and a 30 min reperfusion group (30-RP). The concentrations of metabolites (lactate, alanine and free-carnitine) in the myocardium determined by 1H-magnetic resonance spectroscopy (MRS). The concentration of free carnitine was lower in Ischemia than in Control (2.0 +/- 0.4 vs 5.2 +/- 1.4 mumol/wet.g, p < 0.01), and remained reduced in 30-RP (3.0 +/- 0.6 mumol/wet.g, p < 0.01). On the other hand, the concentration of lactate and alanine were higher in Ischemia than in those of Control (54.9 +/- 8.5 vs 8.8 +/- 0.8, 6.5 +/- 1.0 vs 2.5 +/- 0.5 mumol/wet.g, respectively; p < 0.01), and remained elevated in 30-RP. These findings indicate that recovery from an ischemia-induced disturbance in myocardial metabolism to the pre-ischemic level apparently requires a prolonged period after reperfusion, and that 1H-MRS is a useful new method for evaluating myocardial ischemia.

Alanine↗

PubMed1994

[A case of syphilitic keratitis and retinopathy].

This case study focuses on keratopathy and chorioretinopathy resulting congenital syphilis. The patient is a 51-year-old man who had diabetes mellitus for eleven years. Furthermore he had interstitial keratitis due to syphilis. Both fundi showed chorioretinal atrophy. The fundus findings were similar to those of retinitis pigmentosa. We examined the visual field, ERG and dark adaptation. The serological test for syphilis was positive. A diagnosis of congenital syphilis with keratopathy and chorioretinopathy was made.

Choroiditis↗

PubMed1994

Remission of recurrent primary intracranial malignant lymphoma after high-dose intra-arterial corticosteroid administration and intra-arterial chemotherapy--case report.

A 39-year-old male presented with rapidly growing recurrent primary intracranial malignant lymphoma, manifesting as intractable headache, recent memory disturbance, and left hemiparesis during the previous month. He had received irradiation and chemotherapy for primary intracranial malignant lymphoma 15 months before admission. Signs of uncal herniation developed soon after admission. High-dose intra-arterial corticosteroid infusion followed by intra-arterial chemotherapy (etoposide and cisplatin) successfully relieved the symptoms of uncal herniation. Magnetic resonance imaging demonstrated a dramatic remission in the size of the tumor and associated mass effect. Sequential administration of corticosteroid and chemotherapy agents is a possible treatment for recurrent malignant lymphoma.

Adrenal Cortex Hormones↗

PubMed1994

Cloning and sequencing the streptolysin O genes of group C and group G streptococci.

On the basis of the known streptolysin O (SLO) genomic sequence of Streptococcus pyogenes group A, we identified the SLO genes in some strains of group C and group G streptococci by the polymerase chain reaction procedure (PCR). The entire open reading frame region of these genes was cloned and analyzed. Their nucleotide sequence data showed that the defined SLO genes in group C and group G are almost identical to that of group A.

Amino Acid Sequence↗