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Biomedical subjects

M Honma

Publications and source records attributed to M Honma.

At least 127 records · Page 7Linked to original sources
PubMed1992

Poly(ADP ribose) polymerase-defective mutant cell clone of mouse L1210 cells.

By a sequential mutation and selection utilizing N-methyl-N'-nitro-N-nitrosoguanidine as a mutagen, we succeeded in separating a poly(ADP ribose) polymerase-defective mutant clone (Cl-3527) from a mouse L1210 cell clone (Cl-3). The enzyme activity per cell in Cl-3527 cells was only 8% of that in wild type L1210 (CCL 219) cells. Immunoblot analysis of the enzyme protein in crude extracts of the mutant and wild type cells revealed that the enzyme defect was manifested as the loss of a 113-kDa wild type enzyme band in Cl-3527. Further analysis of partially purified enzyme from Cl-3527 by immunoblotting revealed that the molecular size of the enzyme in Cl-3527 was 108 kDa and that the amount of the mutant enzyme protein was markedly decreased in Cl-3527. The mutant enzyme was much more heat-labile than the wild type enzyme but the Km for NAD+, requirements for Mg2+ and nicked DNA, and the inhibition by 3-aminobenzamide, a potent inhibitor of the enzyme, however, were not so different from those of wild type enzyme. The mutant cells showed prolonged doubling time, increased temperature-sensitivity, increased percentage of active enzyme on a treatment of cells at high temperature, and increased expression of plasma membrane NADase, compared to wild type cells. Introduction of wild type ADPR pol gene into Cl-3527 cells partially restored the ADPR pol activity and the heat-resistance.

Animals↗
PubMed1992

Evidence for a single catalytic site of honeybee alpha-glucosidase I by chemical modification with diethylpyrocarbonate.

Honeybee alpha-glucosidase I was inactivated with diethylpyrocarbonate (DEPC). The inactivation followed pseudo-first-order kinetics. The rate of the loss of activity was decreased by the addition of a substrate, maltose. Since there was no spectral change in the tyrosine absorption region, it was recognized that DEPC did not react with this residue. The alpha-glucosidase had one free sulfhydryl group, which was not involved in the catalytic reaction, and was not modified by DEPC. On the other hand, the specific reaction of DEPC with a histidyl residue was spectrophotometrically confirmed by an increase in absorption near 240 nm, and the activity of the inactivated enzyme was restored by hydroxylamine. The modification rate of one histidyl residue by DEPC was almost equal to the rate of the activity loss. These results indicate that there is one histidyl residue at or near the catalytic site, and that honeybee alpha-glucosidase I has a single active site.

Animals↗
PubMed1992

The effect of cyanide on isolated perfused rat heart.

Using Langendorff isolated perfused rat hearts, we demonstrated direct effects of cyanide on the heart. A heart from a sacrificed male rat was placed on a Langendorff apparatus and perfused with Tyrode solution containing 2.0 mM NaCN (CN-TS), following with normal Tyrode solution (TS) at 37 degrees C. During perfusion we monitored the heart beat, and the state of inorganic phosphate (Pi), creatine phosphate (CrP) and adenosine triphosphate (ATP) by 31P-NMR spectrometer equipped with a surface coil probe. After the beginning of the CN-TS perfusion, the heart was initially excited, and ceased beating completely seventy seconds later. During CN-TS perfusion, the CrP immediately disappeared, but the ATP level was maintained considerably. The peak of Pi shifted to the right, indicating acidosis in the heart. These results suggest that the ATP level in a heart during exposure of cyanide is maintained by activation of anaerobic glycolysis in compensation for cellular oxygen utilization.

Adenosine Triphosphate↗
PubMed1991

Isolation, sequence, and expression in Escherichia coli of the Pseudomonas sp. strain ACP gene encoding 1-aminocyclopropane-1-carboxylate deaminase.

Pseudomonas sp. strain ACP is capable of growth on 1-aminocyclopropane-1-carboxylate (ACC) as a nitrogen source owing to induction of the enzyme ACC deaminase and the subsequent conversion of ACC to alpha-ketobutyrate and ammonia (M. Honma, Agric. Biol. Chem. 49:567-571, 1985). The complete amino acid sequence of purified ACC deaminase was determined, and the sequence information was used to clone the ACC deaminase gene from a 6-kb EcoRI fragment of Pseudomonas sp. strain ACP DNA. DNA sequence analysis of an EcoRI-PstI subclone demonstrated an open reading frame (ORF) encoding a polypeptide with a deduced amino acid sequence identical to the protein sequence determined chemically and a predicted molecular mass of 36,674 Da. The ORF also contained an additional 72 bp of upstream sequence not predicted by the amino acid sequence. Escherichia coli minicells containing the 6-kb clone expressed a major polypeptide of the size expected for ACC deaminase which was reactive with ACC deaminase antiserum. Furthermore, a lacZ fusion with the ACC deaminase ORF resulted in the expression of active enzyme in E. coli. ACC is a key intermediate in the biosynthesis of ethylene in plants, and the use of the ACC deaminase gene to manipulate this pathway is discussed.

Amino Acid Sequence↗
PubMed1991

[The effect of an oral gold compound, auranofin, on bronchial responsiveness to inhaled methacholine in well-controlled bronchial asthma].

Recently, in Japan, auranofin (6 mg/day) has been demonstrated to be a useful treatment for patients with moderate to severe asthma in a double-blind clinical trial. Therefore, to investigate the mechanism of auranofin on bronchial asthma, we examined pulmonary functions and bronchial responsiveness to inhaled methacholine in well-controlled asthmatics after 12 wks of treatment with auranofin, in a double-blind, placebo-controlled fashion. Twenty-five adult patients with asthma received orally 3 mg of auranofin or inactive placebo twice daily for 12 weeks. Bronchial responsiveness, pulmonary function tests and concentrations of gold in the blood were measured before and 6 and 12 wks after the therapy. Bronchial responsiveness (PD35-Grs) was significantly decreased after 12 wks of treatment with auranofin, compared with that 12 wks after treatment with inactive placebo. We suggest that inhibition of bronchial hyperresponsiveness by auranofin is one of the mechanisms by which auranofin is effective against bronchial asthma.

Adult↗
PubMed1991

[Histopathological examination of a case of Behçet's disease with aortic regurgitation].

Cardiac involvement in Behçet's disease is quite uncommon. We report a case of Behçet's disease with aortic regurgitation of which histology was examined. A 56-year-old male came to our hospital with a complaint of right cervical pain. Diagnosis of aortic regurgitation was made by echocardiography, cardiac catheterization and aortography. As the cardiac lesion worsened, the operation of the aortic valve replacement was performed. On pathological examination, there was marked fibrous thickening on the aortic valve and the rupture of elastic tissue in the media of aortic wall. There was no history of rheumatic fever nor syphilis, and dilation of orifice of the aorta was not observed. Thus these changes were probably due to Behçet's disease itself.

Aortic Valve Insufficiency↗
PubMed1991

[Relationship between differentiation of U937 cells and free-radicals-associated proteins on the membrane].

U937, the human monocytic cell line does not have the ability to generate free radicals. However, this cell can be differentiate into a monocyte by stimulation with phorbol esters. In this study, whether differentiated U937 could generate free radicals upon stimulation with chemotactic peptide was examined. The amount of surface protein which was related to the generation of free radicals was quantitated using a monoclonal antibody, termed TM2, which reacted with free radical-associated proteins. There was great augmentation of TM2-associated protein in differentiated U937 cells compared with undifferentiated U937 cells. There were slight differences in the molecular weight of the TM2-associated protein among undifferentiated U937 cells, differentiated U937 cells and granulocytes. It seems necessary to increase some specific protein on the surface of U937 cells in order to generate free radicals.

Cell Differentiation↗
PubMed1990

Application of DNA fingerprinting to parentage and extended family relationship testing.

For the purpose of applying DNA fingerprinting to parentage or other extended blood relationship testing, we have developed a general system for estimating blood relationship between a set of individuals. This system can be used for any blood relationship testing, even if critical family members are unavailable. A general formula for calculating the probability of such relationships based on Bayes' theorem has been devised and the ability of DNA fingerprinting produced by Jeffrey's polycore probe to determine the relationships has been evaluated.

Bayes Theorem↗
PubMed1990

Protective effect of sodium molybdate against the acute toxicity of mercuric chloride in rat. VI. The mechanism of stimulative action of sodium molybdate on urinary excretion of mercury.

In order to gain further insight into the protective action of Na2MoO4 pretreatment (1.24 mmol/kg, once a day, i.p.) against the acute toxicity of HgCl2 (30 mummol/mmol/kg, once, s.c.), changes of renal function, tissue accumulation of mercury, and urinary excretions of mercury and phenolsulfonphthalein after exposure to HgCl2 were investigated. Lactate content in the kidney and serum calcium were also measured. Na2MoO4 pretreatment enhanced urinary excretion of mercury. Renal function of Na2MoO4-pretreated rats was better maintained as compared to that of the rats given HgCl2 alone at either dose (30 or 15 mumol/kg) although the metal content in the kidney of this group was almost the same as that of the latter HgCl2-alone rats. This pretreatment prevented the rise in lactate content in the kidney and the reduction of urinary excretion of phenolsulfonphthalein caused by HgCl2, Na2MoO4 reduced serum calcium. These results suggest that Na2MoO4 prevented mercury-induced acute renal failure by decreasing tissue accumulation of the metal through urinary excretion of mercury. Better renal hemodynamics attributable to hypocalcemia may be a causative factor in the enhancement of urinary excretion of mercury.

Animals↗
PubMed1990

[Infarctions in fibroadenomas of the breast during pregnancy--a case report and a review of the literature].

Described is a case of infarctions in fibroadenomas of the breast that occurred during pregnancy, with a review of the pertinent literature and a brief discussion on the difficulty of achieving a cytologic diagnosis. A 24-year-old female presented tender lumps that increased in size in her breast during the 7 months of her pregnancy. A subsequent cytologic examination revealed many typical cells with clustered nude nuclei. The cytologic diagnosis indicated a Group V, poorly differentiated adenocarcinoma. Following delivery of her infant, the lumps were excised. Microscopic examination revealed extensive infarcted fibroadenomas with lactational changes.

Adenocarcinoma↗
PubMed1989

Endocardium of the left ventricle in volume-loaded canine heart. A histological and ultrastructural study.

To investigate the effects of volume loading of the heart, the endocardium was studied histologically and ultrastructurally. Thirteen adult female beagle dogs were used. An arterio-venous shunt was constructed between the right common carotid artery and the right external jugular vein in nine animals to induce a volume load. Four animals were used as controls. All were kept for 6-12 months. Heart weight, relative heart weight (heart weight/body weight), cardiac output index, stroke volume index and volumes of both ventricles in the experimental animals were significantly larger than in the controls. Shunted blood volume was significantly correlated with heart weight. The endocardium of the left ventricle in the experimental animals showed elastofibrosis and was significantly thicker than in the controls. In 5 hearts, it was more than 20 microns thick and its endothelial cells showed many long microvilli with a very thick basement membrane (1.5-2.0 microns). The thickness of the endocardium was significantly correlated with the heart weight, relative heart weight and cardiac output index, within 1%, 5% and 5% risk, respectively. These endocardial changes were thought to be induced by hemodynamic changes in the left ventricle of the volume-loaded heart, probably being correlated with changes in cardiac function and morphology.

Animals↗