Search PubMed⌕ Search

Biomedical subjects

M Kojima

Publications and source records attributed to M Kojima.

At least 631 records · Page 35Linked to original sources
PubMed1989

Detection and characterization of p-coumaric acid hydroxylase in mung bean, Vigna mungo, seedlings.

A new p-coumaric acid (4-hydroxycinnamic acid) hydroxylase was detected in mung bean seedlings treated with tentoxin, a fungal toxin, in which polyphenol oxidase that hydroxylates a wide variety of monophenols in vitro was completely eliminated. The enzyme required molecular oxygen and showed a pH optimum of 5.0. The enzyme acted only on p-coumaric acid (Km, 3.0 X 10(-5) M), while its specificity for the electron donor was rather broad. The Km value for NADPH (1.5 X 10(-4) M) was much lower than that for L-ascorbic acid (1.0 X 10(-2) M), although the Vmax value was almost the same with both electron donors. The enzyme was potently inhibited by beta-mercaptoethanol (Ki, 3.5 X 10(-6) M) and diethyldithiocarbamate (Ki, 2.3 X 10(-4) M), but was insensitive to p-chloromercuribenzoate. The enzyme was localized in the cell organelles which sedimented between mitochondria and endplasmic reticulum on sucrose density gradient centrifugation. The enzyme activity in the seedling was changed in response to induction by light in a manner suggesting its involvement in biosynthesis of phenolic compounds in mung bean seedlings.

Aryl Hydrocarbon Hydroxylases↗
PubMed1989

Purification and characterization of a peptide C-terminal alpha-amidating enzyme from porcine atrium.

In many peptide hormones and neuropeptides, the carboxy-terminal alpha-amide structure is essential in eliciting biological activity. Here we report the purification and characterization of an alpha-amidating enzyme from porcine atrium, in which a high concentration of alpha-amidating activity was detected. The enzyme was purified to homogeneity from the membrane fraction of porcine atria by five steps of chromatography, including an affinity chromatography using a Sepharose column coupled with a substrate, Tyr-Phe-Gly. The purified enzyme was found to be composed of a single polypeptide chain with an apparent molecular weight of 92,000. This enzyme converted several synthetic peptides with C-terminal glycine to the corresponding des-glycine peptide alpha-amides.

Amino Acid Sequence↗
PubMed1989

Decrease in alpha 1-adrenoceptor reserve in mesenteric arteries isolated from spontaneously hypertensive rats.

The characterization of alpha-adrenoceptor-mediated contractile responses and the effects of the calcium channel blocker nifedipine on these responses were investigated in mesenteric arterial strips from 13-week-old male spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto rats (WKY). Contractile responses to the alpha-adrenoceptor agonists phenylephrine and clonidine were mediated through the activation of alpha 1-adrenoceptors. The dose producing a half-maximum response (ED50) for the agonists was higher in SHR than in WKY. Affinities of alpha 1-adrenoceptors were similar between the two strains. When arterial strips from both strains were treated with the same concentration of phenoxybenzamine, the maximum response to each agonist was weaker in SHR. The alpha 1-adrenoceptor occupancy-response relationship for phenylephrine was hyperbolic and less steep in SHR, while the relationship for clonidine was linear in SHR but not in WKY. Alpha 1-adrenoceptor occupancy at a half-maximum response to each agonist was greater in SHR. Nifedipine inhibited the maximum responses to the agonists more profoundly in SHR than in WKY. This inhibition was greater in the response to clonidine than in the response to phenylephrine in both strains. When the maximum response to phenylephrine was reduced to the same extent in both strains by treatment with different concentrations of phenoxybenzamine, the responses to phenylephrine were more susceptible to inhibition by nifedipine. Under these conditions, the effects of nifedipine were similar between SHR and WKY. These results suggest that alpha 1-adrenoceptor reserve is reduced in SHR mesenteric artery compared with WKY, which may be responsible for the greater inhibition by nifedipine of the alpha 1-adrenoceptor-mediated contractions in SHR.

Adrenergic alpha-Agonists↗
PubMed1989

Effects of AFD-21, a new class I antiarrhythmic agent, and AFD-19, its active metabolite, on the maximal rate of rise of action potentials in guinea pig papillary muscles: dependence on time, voltage, and action potential duration.

Effects of AFD-21 and AFD-19 (a new class I antiarrhythmic agent and its active metabolite, respectively) on the maximal rate of rise (Vmax) of action potentials (APs) were studied in guinea pig papillary muscles with special reference to their time, voltage, and action potential duration (APD) dependence. Both AFD-21 and AFD-19 (2-10 microM) reduced Vmax in a concentration-dependent manner without affecting the resting potential, APD, and effective refractory period. Both agents (5 microM) shifted the normalized Vmax resting potential curve (examined at 1 Hz) in the hyperpolarizing direction by 4-7 mV (voltage dependence). In addition, both agents (5 microM): a) caused a frequency-dependent reduction of Vmax at 0.25-3 Hz; b) developed a use-dependent (1 Hz) reduction of Vmax with an onset time constant of 1-3 s; and c) slowed the recovery process of Vmax, whose resultant recovery time constant was 2-3 s (time dependence). Nicorandil (1 mM), which shortens APD to about 25% of control, antagonized the AFD-21-induced time-dependent reductions of Vmax but not the AFD-19-induced reductions (APD dependence). These results suggest that the effects of AFD-21 on Vmax are APD dependent but those of AFD-19 are not, and thereby that AFD-21 and AFD-19 preferentially block inactivated and open sodium channels, respectively. The present findings are discussed from the viewpoint of the modulated or the guarded receptor hypothesis.

Action Potentials↗
PubMed1989

Toxicity of Microcystis aeruginosa K-139 strain.

Toxicity of the cells of a newly established axenic Microcystis aeruginosa K-139 strain to mice was studied. LD50 of the cells harvested in the mid-log phase was 7.3 mg/kg. The organs of acute dead mice were examined histopathologically. The blood congestion and necrosis of the parenchymal cells around the central veins in the liver were observed, but other organs seemed to be normal. The liver damage was confirmed by the tests of glutamic oxaloacetic transaminase (GOT) and glutamic pyruvic transaminase (GPT) activities in the sera of the mice after the injection with the K-139 cells. Furthermore, the K-139 cells were capable of inducing interleukin 1 (IL-1) production by peritoneal macrophages in vitro.

Animals↗
PubMed1989

[Preparation of cerebral ischemia-induced amnesic model in mice and ameliorative effect of several compounds on the model].

A simple and reliable method for the preparation of an ischemia-induced amnesic model was developed in mice and the model animals were employed for screening of the anti-amnesic effect of drugs. Under light thiopental anesthesia the bilateral carotid arteries were exfoliated from the surrounding tissues. Each artery was threaded through a small polyethylene tube, and the incision was sutured, leaving the tip of the tube and both ends of the thread out of the skin. To prevent the tube from falling off, both ends of the thread was ligated at the tip of the tube. Cerebral ischemia was attained by pulling the artery into the tube, and the occlusion was rapidly released by cutting the ligation in the thread and taking off the tube. Twenty-four hours after the surgery, the animals were used for the one trial passive avoidance learning test. In ddY strain mice, the amnesic state was obtained by 5 to 30 min cerebral ischemia, which was applied immediately after the acquisition trial. Mice of the ICR strain were more sensitive to the ischemic treatment and 2 min occlusion of the carotid arteries resulted in a high degree of amnesia. A potent prolyl endopeptidase inhibitor, Z-thiopro-thiazolidine, and 2 novel pyrrolidone derivatives, p-chlorobenzyl-2-pyrrolidone-5-carboxylate and N-(2-pyridylmethyl)-2-pyrrolidone-5-carboxamide, improved the acquisition of the passive avoidance response in the ischemia-induced amnesic models.

Amnesia↗
PubMed1989

Absorption of egg antigens by the gut observed by oral Prausnitz-Küstner (Walzer) reaction in atopic dermatitis.

Sera from 50 children (27 boys and 23 girls, under the age of 3 years) with atopic dermatitis allergic or not to hen's egg shown by skin test or radioallergosorbent test (RAST) were passively transferred to recipients which were then challenged with injection of egg antigen (Prausnitz-Küstner (P-K) test) or with ingestion of a raw egg (oral P-K test). Thirty-one patients showed positive P-K reaction with serum titers from 2 to 8,192. Fifteen of the P-K positive cases were also positive in the oral P-K test with titers from 2 to 256. The ratio of the oral P-K titer and the P-K titer in each positive case was from 1:2 to 1:32. The results indicate that a high percentage of atopic dermatitis patients with egg allergy have IgE antibody in the serum capable of reacting with an ingested egg.

Antigens↗
PubMed1989

[A noninvasive study on characteristics of the left ventricular function in elderly hypertensive patients].

To characterize the left ventricular (LV) systolic and diastolic function in elderly hypertensives, mechano-and echocardiography was performed in 27 elderly patients more than 65 years of age (20 hypertensives and 7 normotensives) and 46 middle-aged patients (34 hypertensives and 12 normotensives). In normotensives, a positive correlation was found to exist between age and blood pressure, LV wall thickness, II-RF interval and the A/E ratio, whereas the correlation of age to systolic parameters such as ET/PEP and EF was absent. This suggests that the LV diastolic function was impaired progressively by aging with preservation of the LV systolic function. In elderly hypertensives, LV systolic function was deteriorated and the A/E ratio increased as diastolic blood pressure became elevated. The A/E ratio also increased in this group as compared with that in middle-aged hypertensives, although the differences was not statistically significant. Unlike those in middle-aged hypertensives, the indices of LV function except the elevated blood pressure and the increased cardio-thoracic ratio were not significantly different between hypertensive and normotensive elderly patients. This might be because of the wide range of normal values in elderly persons due to the various degrees of atherosclerotic changes and other pathophysiologic factors, which might have masked obvious characteristics of hypertension in elderly hypertensives.

Adult↗
PubMed1989

[Interaction of platelets and cultured cells with polymers containing phospholipid polar groups].

To apply a polymer as biomaterials in a variety of medical field, the evaluations of its adaptability to various kinds of cells are necessary. Therefore, the present paper describes not only the interaction between new polymer materials having phospholipid moiety (MPC) and human epithelial cell (Ca. 9.22) but also the change of platelet function in contact with the material for a prolonged period. In many examples few cells are able to adhere or grow on the surface of high water content gels, similar phenomena are observed in the case of high MPC content copolymers. This result indicates that MPC copolymer tends to offer insufficient liquid structure on which cells are able to adhere and grow. Since the suspended cells which did not adhere on these MPC copolymers survive for prolonged incubation period, it is evident that the MPC copolymer has good compatibility to the cells, and is inadequate for the cell attachment. As the polymers containing polar head group of phospholipids suppress attachment or adhesion of platelets and Ca. 9.22 cells, the polymers are potentially useful for the nonthrombogenic materials and the coating of biosensor which is inserted and retained in the human body.

Cell Adhesion↗
PubMed1989

[Adhesion of 4-META/MMA-TBB resin to enamel treated with EDTA metal ammonium solutions. Effect of Fe.NH4, Co.NH4 and Cu.NH4 salts].

EDTA 3-2 (Fe.NH4), EDTA 3-2 (Co.NH4) and EDTA 3-2 (Cu.NH4) at pH 7.4 were investigated to determine effective pretreatment to promote strong adhesion of 4-META/MMA-TBB resin to enamel with minimum demineralization. EDTA 5-0 (NH4) solution which does not contain a metal salt was also investigated as a control. The amount of Ca2+ demineralized during the pretreatment and the tensile bond strength to enamel were measured. The pretreated enamel surface and the resin surface of the adhesion junction were observed with SEM. When the enamel surface was pretreated with EDTA 3-2 (Fe.NH4) for 60 seconds, the tensile bond strength of the resin to enamel was 7.1 MPa after the thermal cycling test. No direct correlation was observed between the amount of Ca2+ demineralized and the tensile bond strength. The stable and strong bonding to enamel was taken place without strong mechanical retention.

Acrylic Resins↗
PubMed1989

[Adhesion of 4-META/MMA-TBB resin to dentin treated with EDTA metal ammonium solutions. Effect of Fe.NH4, Co.NH4 or Cu.NH4 salts].

EDTA metal ammonium salt solution containing Fe3+, Co3+ or Cu2+ was studied to determine the pretreatment reagent that causes no denaturation of dentin collagen and promotes good adhesion to dentin. After application of EDTA 3-2 (Fe.NH4), EDTA 3-2 (Co.NH4) or EDTA 3-2 (Cu.NH4) at pH 7.4 on the dentin surface, the amount of Ca2+ demineralized and the tensile bond strength were measured. The pretreated dentin surfaces were also observed with SEM. No correlation was obtained between the amount of Ca2+ demineralized and the tensile bond strength. On the EDTA 3-2 (Fe.NH4) treated dentin a small amount of smear remained partially, but the tensile bond strength of 4-META/MMA-TBB resin to the dentin was higher than 13 MPa. This indicates that complete removal of the smear on dentin is not always necessary for better bonding.

Boron Compounds↗
PubMed1989

Thyroid antigen-mediated glomerulonephritis in Graves' disease.

We describe a patient with Graves' disease in whom marked proteinuria, microhematuria and hypoalbuminemia were associated. Renal biopsy demonstrated electrondense deposits in the capillary basement membrane, a finding consistent with immune complex glomerulonephritis. Indirect immunofluorescent examination with rabbit antihuman thyroglobulin indicated that these electron-dense deposits were thyroid antigen-mediated immune complexes.

Antigen-Antibody Complex↗
PubMed1989

Effects of lidocaine alone and in combination with tetraethylammonium on the maximum upstroke velocity in guinea-pig papillary muscles.

Effects of 18.5 mumol/l lidocaine on the Vmax in the absence and presence of 10 mmol/l tetraethylammonium chloride (TEA), which specifically prolongs the action potential duration with little effects on Vmax, were studied in guinea-pig papillary muscles in a 10 mmol/l K+ Tyrode solution. The frequency-dependent reduction of Vmax was significantly increased at high frequencies (3 and 4 Hz) in the presence of lidocaine plus TEA. A simulation study was performed under the assumption that lidocaine interacts with open, inactivated and resting sodium channels and that TEA specifically prolongs the inactivated state, and a reasonable fit to the experimental Vmax changes was obtained. There were no significant differences between the effects of lidocaine alone and lidocaine plus TEA on the tonic blocks, time constants and zero-time intercepts of reactivation process of Vmax. The F-test shows that these reactivation processes in all preparations examined are described sufficiently well by monoexponential functions, that is, under the assumption of the linear relationship between available sodium conductance and Vmax. The finding that a nonlinear model does not significantly improve the fit indicates the possibility that the nonlinearity may not be prominent under the present experimental conditions.

Action Potentials↗
PubMed1989

[Relapse of acute monocytic leukemia present with skin and tracheal involvement].

A 34 year-old female was admitted because of anemia and leukopenia. Her bone marrow contained abundant blastic cells, which were histochemically positive for peroxidase and alpha-naphthyl butyrate esterase, but negative for ASD chloroacetate esterase. She was diagnosed as acute monocytic leukemia (FAB, M5a). Complete remission was achieved after the administration of BHAC, daunorubicin, 6MP and prednisolone, and she was discharged after consolidation therapies. But shortly later, she noticed hoarseness and erythematous nodules on her breast and abdomen. Though the examinations of peripheral blood and bone marrow did not show any abnormality, hoarseness rapidly worsened and she complained of dyspnea. X-ray and CT scan demonstrated narrowing of the trachea under the cricoid cartilage, and trans-tracheal biopsy revealed leukemic involvement. In addition, erythematous skin lesion showed the infiltration of leukemic cells by biopsy. Although radiation and chemotherapy was initiated, she died of pneumonia. We tried to discuss the laryngo-tracheal and skin involvement of acute monocytic leukemia as early symptoms of relapse.

Adult↗
PubMed1989

Childhood Ki-1 lymphoma. A report of two cases.

Two cases of childhood Ki-1 lymphoma occurred with the expression of Ki-1+/HLA-DR+/IL-2R+/EMA+/Leu-M1-/pan-T antigens-/pan-B antigens- in neoplastic cells. Patient 1 with nodular skin lesions expressed Leu-2a+ in the neoplastic cells and died 14 months later. Patient 2 with lymph node swelling and hepatosplenomegaly exhibited Leu-3a+ in the neoplastic cells and remains free of disease. The Leu-2a+ (case 1) or Leu-3a+ (case 2) findings suggest that the neoplastic cells in both cases were derived from T-lymphocyte lineage. However, Southern's blot analysis did not reveal any clonal rearrangements of T-cell receptor genes in the autopsy material from case 1. The Leu-3a+/Mcs-2+ finding in case 2 may indicate that the neoplastic cells were derived from monocyte/macrophage lineage.

Child, Preschool↗