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Biomedical subjects

T Takeuchi

Publications and source records attributed to T Takeuchi.

At least 1,063 records · Page 59Linked to original sources
PubMed1992

AB3217-A, a novel anti-mite substance produced by a strain of Streptomyces platensis.

AB3217-A, a novel anti-mite substance, was isolated from the fermentation broth of a streptomycete strain. The strain was isolated from a soil collected at Kita-azumi, Nagano Prefecture, Japan, and identified as Streptomyces platensis AB3217. AB3217-A was purified by Amberlite IR120B, Diaion HP-20 and CM-Sephadex C-25 column chromatographies. The molecular formula was determined as C17H23NO7 by elemental analysis, MS and 13C NMR spectroscopy. The structure of AB3217-A was determined to be (1R,3S,4S,7R,8R,11R,12S,13R)-4,12,13-trihydroxy-8-(4-methoxy phenyl)-6-aza-2,9,14-trioxatricyclo-[9.2.1.0(3,7)]tetradecane by spectroscopic analysis and X-ray crystallographic analysis. The molecule of AB3217-A has unique structure that deacetylanisomycin and beta-D-xylofuranose linked through glycosidic bond and ether bond resulting in the formation of nine-membered ring. AB3217-A showed marked activity against the two spotted spider mite, Tetranychus urticae.

Animals↗
PubMed1992

Syntheses and activities of some bactobolin derivatives.

Some derivatives of bactobolin were prepared from bactobolin by dehydration or substitution reactions through tris(dimethylamino)alkoxyphosphonium salt formation. A derivative with low toxicity, 6-deoxybactobolin, showed moderate activity against Gram-positive and Gram-negative bacteria including methicillin-resistant Staphylococcus aureus.

Animals↗
PubMed1992

Totally synthetic analogues of siastatin B. II. Optically active piperidine derivatives having trifluoroacetamide and hydroxyacetamide groups at C-2.

Siastatin B analogues, optically active 2-(trifluoroacetamide)- 3,4,5-trihydroxypiperidines having nitromethyl, aminomethyl and carboxyl branched groups at C-5, and (+)-(2R,3R,4R,5R)-5-(aminomethyl)-3,4,5-trihydroxy-2- (hydroxyacetamido)piperidine have been obtained total synthetically from D-ribono-1,4-lactone. Some analogues have inhibitory activity against some glycosidases, and (+)-(2R,3R,4R,5R)-2-(trifluoroacetamido)-3,4,5-trihydroxypiperi dine-5-carboxylic acid showed a marked inhibitory activity against beta-glucuronidase.

Anti-Bacterial Agents↗
PubMed1992

[Imported parasitic diseases--recent epidemiology and progress in the chemotherapy].

Imported parasitic diseases have been increasingly important in basic and clinical medicine in developed countries, as the number of travellers in developing countries, where numerous kinds of parasitic diseases are highly endemic, have been increasing. Recent epidemiologic investigation demonstrated that malaria, amebiasis, trypanosomiasis, leishmaniasis and cysticercosis seemed important as judged from the number of infected individuals, primarily Japanese travellers. Although these parasitic diseases pose some serious medical problems, establishment of the effective chemotherapeutic strategy is of urgent significance. In this respect, activities of the Research Group of Development of Chemotherapeutic Agents against Tropical Parasitic Diseases supported by the Japanese Ministry of Health and Welfare appear to be important to keep appropriate drugs in Japan.

Amebiasis↗
PubMed1992

[Cancer of the kidney mimicking renal multilocular cyst].

Two cases of multilocular cystic adenocarcinoma of the kidney are presented. Although ultrasonography (US) and x-ray computed tomography (CT) are generally considered to be excellent diagnostic methods for renal cystic lesions, in the 2 cases reported here they failed to give the correct diagnosis. These unusual cases altered us to the possibility that the capabilities of modern diagnostic imaging techniques can lead to a false sense of security regarding the prognosis. To our knowledge, there are no reliable clinical features which distinguish multilocular cystic adenocarcinoma from multilocular cystic nephroma.

Adenocarcinoma↗
PubMed1992

[Effect of proton pump inhibitor, in combination with epidermal growth factor, on the healing of chronic gastric ulcer in submandibular gland removed rats].

The effect of a proton pump inhibitor, omeprazole (OPZ), in combination with mouse epidermal growth factor (EGF), on the healing of chronic gastric ulcers induced by acetic acid in submandibular glands removed rats (SMR rat) was investigated. Four separate groups of SMR rats were orally administered 1 ml of distilled water (control), 100 mg/kg of OPZ alone (OPZ), 5 micrograms/kg of mouse EGF alone (EGF), or combination with (EGF + OPZ) twice daily. Two weeks later, ulcer areas of four groups were measured and expressed as the ulcer index (UI). The UI of the OPZ and EGF + OPZ group was significantly reduced as compared with that of the control. Furthermore, the UI of the EGF + OPZ group was significantly smaller than that of the EGF group. The present study indicates that the proton pump inhibitor promotes healing of chronic gastric ulcers in SMR rats and the effect of the proton pump inhibitor is enhanced by administration of mouse EGF.

Acetates↗
PubMed1992

Heart allografts in murine systems. The differential activation of Th2-like effector cells in peripheral tolerance.

Activated CD4+ Th2 cells release cytokines (IL-4,-10) that block activation & cytokine (IL-2/IFN-gamma) release by proinflammatory T (CD4+,CD8+) effector cells. To test the hypothesis that peripheral tolerance to alloantigen is linked to differential activation of CD4+ Th2 cells we measured cytokine transcripts in heart grafts (C57BL/10----C3H/HeJ) and spleens of mice rendered "tolerant" by donor-specific blood transfusion, anti-CD4 mAb pretreatment, and cyclosporine administration. The expression of IL-2/IFN-gamma transcripts was reduced greater than 90% in grafts from tolerant recipients. IL-4/IL-10 transcripts were generally enhanced and persisted in graft and recipient spleen. Accordingly adoptive transfer studies were performed to determine whether Th2-like effectors, which express Fc receptors (FcR), mediate suppression in this model. Unfractionated mononuclear cells (MC) (5 x 10(6), isolated from spleens of heart graft recipients made tolerant by DST, prolonged the survival of test grafts greater than 90 days in irradiated (680 rads) recipients reconstituted with a sufficient number of MC from spleens of naive C3H to precipitate rejection of the test graft in 18.2 days (MST, n = 5). Conversely adoptive transfer of inocula depleted of FcR+ cells on immune complex columns or with anti-FcR mAb 24G2 caused test grafts to be rejected in 8-11 days. These results suggest that peripheral tolerance to alloantigen may be linked to differential activation of Th2 cells that induce anergy by suppression. The possibility that Th2-like effectors mediate peripheral tolerance to self is discussed.

Animals↗
PubMed1992

Elevated interleukin-6 and gamma-globulin during interferon therapy of hepatitis B.

A 49-yr-old man with chronic hepatitis B manifested hypergammaglobulinemia, lymphadenopathy, and a high serum interleukin-6 level following treatment with recombinant human alpha-interferon. One month later, when the patient was treated with natural beta-interferon, serum levels of interleukin-6 and gamma-globulin increased again. The serum gamma-globulin decreased to the pretreatment level after discontinuation of interferon therapy. The serum alanine aminotransferase level remained normal for 6 months. In this case, hypergammaglobulinemia and lymphadenopathy, as well as the elevated serum interleukin-6 level, were considered to be signs of highly enhanced humoral immunity related to alpha- and beta-interferon therapy.

Alanine Transaminase↗
PubMed1992

Holding power and reinforcement of cancellous screws in human bone.

The authors report an in vitro biomechanical evaluation of a biodegradable material that might be used for the reinforcement of surgical screws in fractures involving severely osteoporotic bone. The material is a particulate composite with a matrix phase consisting of a hydrolyzable prepolymer, polypropylene fumarate (PPF), crosslinked with methacrylate monomer, and a particulate phase consisting of tricalcium phosphate and calcium carbonate. Pullout force and stripping load of cancellous screws were determined along with screw pullout force before and after reinforcement with either polymethylmethacrylate (PMMA) or PPF composite. Pullout force was moderately correlated (R2 = 0.59) with apparent density by a power law relationship of the form 0.065p1.37-1.77. Stripping load was strongly correlated (R2 = 0.91) with apparent density by a power law of the form 0.13p1.35-93.8. Mean pullout force before and after reinforcement with PMMA was 382 +/- 100 N (mean +/- standard deviation) and 879 +/- 315 N, respectively. Mean pullout force before and after reinforcement with PPF composite was 571 +/- 294 N and 829 +/- 354 N, respectively. Although the increase in pullout force with cement reinforcement was highly significant in both cases, the magnitude of the increase did not depend on the type of cement. Thus PPF seems to provide reinforcement that is equivalent to that provided by PMMA.

Aged↗
PubMed1992

Selective inhibitory effects of calcium channel antagonists on the two components of the neurogenic response of guinea pig vas deferens.

The effects of L-type calcium channel antagonists and omega-conotoxin on the contractile responses of guinea pig vas deferens were examined in vitro. Electrical stimulation of the postganglionic hypogastric nerve induced biphasic contraction consisting of rapid phasic and delayed tonic components. L-type calcium channel antagonists, such as diltiazem, verapamil and nicardipine, mainly inhibited the delayed tonic component, whereas omega-conotoxin mainly inhibited the rapid phasic component. Stimulations in the presence of prazosin and alpha, beta-methylene ATP induced rapid transient and delayed contraction, respectively, which were inhibited by omega-conotoxin and L-type calcium channel antagonists, respectively. Short-term stimulation with five pulses induced a small fast phasic contraction. This contraction, which could be desensitized by alpha, beta-methylene ATP, was inhibited by omega-conotoxin, but not by L-type calcium channel antagonists. At the concentrations used in the present study, none of the calcium channel antagonists inhibited the contractions induced by exogenously added ATP or norepinephrine. These findings suggest that L-type calcium channel antagonists and omega-conotoxin inhibit the neurotransmissions mediated by norepinephrine and ATP, respectively, from the postganglionic nerve to the vas deferens of the guinea pig. Inhibition of the voltage-dependent calcium channel is discussed in relation to the mechanism of cotransmission in this preparation.

Adenosine Triphosphate↗
PubMed1992

Analysis of a unique molecule responsible for regeneration and stabilization of differentiated state of tissue cells.

In Wolffian regeneration in the newt, a functional lens can be regenerated through cellular transdifferentiation of the pigmented epithelium of the mid-dorsal marginal iris. A novel monoclonal antibody, 2NI-36 mAb, generated in our laboratory has been utilized as a highly useful probe to study newt lens regeneration. The antigen molecule against this 2NI-36 mAb (2NI-36) became temporarily undetectable only at the site of lens regeneration. Moreover, the ventral iris pieces expressed the ability to differentiate a lens when pretreated with this monoclonal antibody and implanted in lentectomized eyes (Eguchi, Cell Differ. Dev. 25, Suppl., 1988). We have investigated the distribution of 2NI-36 in newt tissues. 2NI-36 was not specific to iris pigmented epithelium and distributed in many different kinds of mesodermal tissues, including dermis, blood vessel, mesonephros and so forth. 2NI-36 was also detected in either cell surface or intercellular spaces of cultured pigmented epithelial cells when they organized an epithelial cell sheet. Western blot analysis showed that 2NI-36 had the molecular weight of 50-200kD and was completely digested by trypsin, suggesting that 2NI-36 was a glycoprotein with many carbohydrate chains. It was also revealed by Western blot analysis that all the tissues in which 2NI-36 could be detected expressed this molecule similar to that in the iris epithelium. We expect that 2NI-36 is a glycoprotein expressed by various newt tissues and is functional to stabilize the differentiated state of each tissue cell in the same way as observed in the iris pigmented epithelial cells.

Animals↗