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Biomedical subjects

T Takeuchi

Publications and source records attributed to T Takeuchi.

At least 451 records · Page 25Linked to original sources
PubMed1998

Relationship between inhibitory effect of endogenous opioid via mu-receptors and muscarinic autoinhibition in acetylcholine release from myenteric plexus of guinea pig ileum.

Relationship between activation of opioid receptors and muscarinic autoinhibition in acetylcholine (ACh) release from the myenteric plexus was studied in longitudinal muscle myenteric plexus (LMMP) preparations of guinea pig ileum. A mu-receptor agonist, [D-Ala2, N-Me-Phe4, Gly5-ol] enkephalin (DAMGO), at a concentration of 1 microM inhibited the ACh release evoked by electrical field stimulation (EFS) at 1 Hz but not at 10 Hz. After the muscarinic autoreceptors were blocked with atropine (1 microM), DAMGO inhibited EFS-evoked ACh release also at 10 Hz. After the autoreceptors were potently activated with muscarine (200 microM), the inhibitory effect of DAMGO at 1 Hz was abolished. A kappa-receptor agonist, U-50,488, at 1 microM inhibited the EFS-evoked ACh release both at 1 and 10 Hz. U-50,488 inhibited ACh release regardless of the presence of atropine or muscarine. A delta-agonist, enkephalin [D-PEN2.5] (PDPDE), did not show any significant effect. On the other hand, a selective mu-receptor antagonist, cyprodime, increased ACh release evoked by EFS at 1 Hz, but not at 10 Hz. After the autoreceptors were blocked, cyprodime increased EFS-evoked ACh release also at 10 Hz. The selective kappa-receptor antagonist, nor-binaltorphimine, did not affect ACh release in the absence or presence of atropine. The results suggest that endogenous opioid(s) inhibits ACh release by activating mu-, but not kappa- and delta-receptors in the LMMP of guinea pig ileum and that the inhibitory effect of endogenous opioid(s) in the ACh release is important when muscarinic autoinhibition mechanism does not fully work.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗
PubMed1998

Decrease in participation of nitric oxide in nonadrenergic, noncholinergic relaxation of rat intestine with age.

Participation of nitric oxide in the electrical field stimulation-induced nonadrenergic, noncholinergic (NANC) relaxation in various intestinal regions was studied in 2- to 50-week-old Wistar rats. In the jejunum of 2-week-old rats, the extent of the nitric oxide-mediated component of the relaxation of longitudinal muscle was approximately 60-70%, whereas the component was 40-50% in 4-week-old rats and was absent in 8- and 50-week-old rats. Thus, nitric oxide seems to be the most important mediator at young ages but its significance is lost with age. The same tendency as that in the jejunum was also shown in longitudinal muscle of the ileum, proximal and distal colon, and rectum. The tendency was also shown in the circular muscle of the rectum. Sensitivity of the longitudinal muscle of the jejunum and proximal colon to exogenously added nitric oxide was high in younger rats. Immunoreactive structures for nitric oxide synthase were observed in the circular muscle layer of the rectum. The population of the structures was denser in 4-week-old than that in 50-week-old. The results suggest that NANC relaxation in every region of the intestine at 2-week-old is almost solely mediated by nitric oxide, and its significance as an inhibitory mediator gradually or rapidly decreases with age.

Adrenergic Agents↗
PubMed1998

Inhibitory effect of endomorphin-1 and -2 on acetylcholine release from myenteric plexus of guinea pig ileum.

Endomorphin-1 and -2, putative endogenous ligands for the mu-opioid receptor, inhibited acetylcholine (ACh) release evoked by electrical field stimulation (EFS) at 1 Hz, which partially activates muscarinic autoreceptors, but not at 10 Hz, which fully activates muscarinic autoreceptors, in longitudinal muscle with the myenteric plexus (LMMP) preparations of guinea pig ileum. After blockade of autoinhibition by atropine, the peptides also inhibited EFS-evoked ACh release at 10 Hz. The inhibitory effects on ACh release were abolished by the mu-opioid antagonist cyprodime. These results suggest that endomorphin-1 and -2 inhibit ACh release from LMMP preparations of guinea pig ileum and that the mechanism of the inhibition must have a component in common with muscarinic autoinhibition.

Acetylcholine↗
PubMed1998

Age-related changes in the cochlea and cochlear nuclei of dogs.

To study the underlying morphological changes of presbycusis, cochlea and cochlear nuclei from twenty three dogs, ranging in age from 3 days to 17 years, were examined histologically. Dogs used in this study were house dogs kept in an environment similar to that of humans. Four types of histological changes reported in human presbycusis, that is, loss of spiral ganglion cells, atrophy of the organ of Corti, atrophy of the stria vascularis, and thickening of the basilar membrane were observed in dogs. The changes were prominent at the base of the cochlea. Less intense changes were also observed in the apex of the cochlea. The degree of these changes appeared to progress as a function of age. All four types of changes with varied intensity were found in all dogs over 12 years old. In addition to the changes in the cochlea, cochlear nuclei changes including nerve cell loss, astrogliosis and ubiquitin deposition were found in dogs over 10 years old. Hearing dysfunction was accompanied by the morphological changes, though the degree of the hearing dysfunction did not always parallel to that of morphological changes. The morphological changes seen in the cochlea and cochlear nuclei of dogs were qualitatively and quantitatively similar to those reported in aged humans, indicating that otopathologic changes in the inner ear may be due to aging plus exposure to certain environmental ototoxic factors.

Aging↗
PubMed1998

Near-infrared spectrometry analysis of fat, neutral sterols, bile acids, and short-chain fatty acids in the feces of patients with pancreatic maldigestion and malabsorption.

CONCLUSION: Near-infrared spectrometry is a new, rapid, and accurate method for measuring fecal fat that does not require a great deal of chemical knowledge and that can be used by anyone. This method is considered indispensable for the diagnosis of pancreatic steatorrhea and treatment follow-up. METHODS: Fecal fats (GLC method, van de Kamer method), neutral sterols (GLC method), bile acids (GLC method) and short-chain fatty acids (HPLC method) were assayed by the respective conventional methods in 120 subjects, including patients with pancreatic dysfunction, and the results were compared with the those obtained by near-infrared spectrometry. The correlations between fecal fat excretion measured by the GLC method (x) and van de Kamer method (x) and by near-infrared spectrometry (y) were expressed by y = 1.10x - 0.16 (r = 0.949, P < 0.01) and y = 0.750x + 1.654 (r = 0.930, p < 0.01), respectively. RESULTS: The sensitivity and specificity of near-infrared spectrometry for fecal fats were 94.9 and 98.2%, respectively, when compared with the GLC method, and 87.5 and 90.0%, respectively, when compared with the van de Kamer method. In contrast, near-infrared spectrometry was not nearly as accurate as the conventional methods for determining neutral sterols, bile acids, and short-chain fatty acids.

Bile Acids and Salts↗
PubMed1998

Pseudotumor cerebri in a patient with acute promyelocytic leukemia during treatment with all-trans retinoic acid.

We report a rare case of pseudotumor cerebri associated with all-trans retinoic acid (ATRA) treatment of acute promyelocytic leukemia (APL). An 18-year-old male was admitted to our hospital complaining of palpitations and shortness of breath; he was found to have APL. The administration of ATRA and chemotherapy was started. After 23 days, he complained of nausea, headache and double vision. Computed tomography and magnetic resonance imaging of the head showed no intracranial abnormalities. Bilateral papilledema, a symptom of increased intracranial pressure, was noted. A diagnosis of pseudotumor cerebri was made. Symptoms were improved by administration of glycerin and the discontinuation of ATRA. After 29 days, a complete remission was achieved.

Adolescent↗
PubMed1998

Tyrosine phosphorylated proteins in synovial cells of rheumatoid arthritis.

Two of the key events in the pathogenesis of rheumatoid arthritis are the synovial cell proliferation and lymphocyte infiltration into the synovium. The resulting synovitis is longlasting and leads to destructive arthritis, which is a hallmark of rheumatoid arthritis. Accumulating evidence suggests that one of the key biochemical events in the altered cell function of RA is phosphorylation of the tyrosine residues of proteins. In this paper we review the cellular components participating in the chronic inflammation of RA joints. We present the results of analyzing tyrosine phosphorylated proteins of synovial cells from RA patients and discuss a possible pathogenic role of non-receptor tyrosine kinase in RA.

Animals↗
PubMed1998

[Changes in blood polyamine levels following chemotherapy in patients with invasive urinary bladder carcinoma].

BACKGROUND: Polyamines are recognized as cell growth factors. We attempted to determine whether blood polyamines are useful biochemical makers for monitoring the efficacy of the chemotherapy on bladder tumors. METHODS: The blood concentrations of three polyamines, diamine, spermidine and spermine, were determined in 31 patients with invasive urinary bladder carcinoma, following chemotherapy with cisplatin, methotrexate and pirarubicin. Clinical response was evaluated by CT after 3 weeks. In 26 patients who underwent subsequent surgical therapy, the effectiveness of the chemotherapy were histopathologically evaluated by a pathologist according to the response criteria for bladder cancer treatment. RESULTS: Mean regression rate in the size of the tumor after the chemotherapy was 40.8%. Of 31 patients, clinical CR was observed in 2, PR in 11, and NC in 18. Of 26 patients who were histopathologically evaluated, grade 3 was observed in 5, grade 2 in 4, grade 1b in 4, grade 1a in 12, and grade 0 in 1. One week after chemotherapy, the levels of spermine and total polyamine in the patients with CR and PR were significantly lower than those in the patients with NC. Similarly one week after chemotherapy, the levels of spermine and total polyamine in the patients with grade 3 and grade 2 were significantly lower than those in the patients with grade 1b, grade 1a and grade 0. CONCLUSION: The study suggested that the levels of blood polyamines could be used as biochemical markers for monitoring the efficacy of the chemotherapy on bladder tumors.

Adenocarcinoma↗
PubMed1998

Diperamycin, a new antimicrobial antibiotic produced by Streptomyces griseoaurantiacus MK393-AF2. I. Taxonomy, fermentation, isolation, physico-chemical properties and biological activities.

Antibacterial antibiotics, diperamycin (1) was produced in the culture broth of Streptomyces griseoaurantiacus MK393-AF2. Various spectroscopic analyses of 1 suggested that 1 belonged to a member of cyclic hexadepsipeptide antibiotic. Antibiotic 1 had potent inhibitory activity against various Gram-positive bacteria including Enterococcus seriolicida and methicillin-resistant Staphylococcus aureus.

Animals↗
PubMed1998

Cremimycin, a novel 19-membered macrocyclic lactam antibiotic, from Streptomyces sp.

A novel 19-membered macrocyclic lactam antibiotic, cremimycin, was isolated from the culture broth of an actinomycete strain. The producing organism, designated MJ635-86F5, was identified as a member of Streptomyces. Cremimycin was isolated from the mycelial cake by extraction with CHCl3-MeOH and precipitation with hexane-MeOH. The structure of cremimycin was determined by spectroscopic study. Cremimycin showed broad antimicrobial activities against Gram-positive bacteria including MRSA.

Animals↗
PubMed1998

Nothramicin, a new anthracycline antibiotic from Nocardia sp. MJ896-43F17.

A new antibiotic designated nothramicin was isolated from the culture broth of Nocardia sp. MJ896-43F17 which was closely related to Nocardia brasiliensis. It was isolated by the Diaion HP-20 column chromatography, butyl acetate extraction and purified by HPLC. It inhibited the growth of mycobacteria at the concentration of 1.56 approximately 25 microg/ml. Nothramicin was revealed to be a new member of anthracycline antibiotics by the various spectroscopies.

Animals↗
PubMed1998

Synthesis and activity of 3-epi-actinobolin.

3-epi-Actinobolin was synthesized by the chemical transformation of actinobolin involving a key step of the reconstruction of fused delta-lacton skeleton via intramolecular acylation reaction. The analogue with low toxicity weakly inhibits Gram-positive and Gram-negative bacteria.

Anti-Bacterial Agents↗
PubMed1998

Polyketomycin, a new antibiotic from Streptomyces sp. MK277-AF1. I. Taxonomy, production, isolation, physico-chemical properties and biological activities.

A new antibiotic designated polyketomycin was isolated from the culture broth of Streptomyces sp. MK277-AF1. It was purified by ethyl acetate extraction, Sephadex LH-20 column chromatography and centrifugal partition chromatography (CPC). It inhibited growth of Gram-positive bacteria including methicillin-resistant Staphylococcus aureus (MRSA). Its MICs were less than 0.2 microgram/ml. Polyketomycin exhibited cytotoxic activity against nine tumor cell lines at concentrations of 0.9-5.2 micrograms/ml.

Anti-Bacterial Agents↗
PubMed1998

Epostatin, new inhibitor of dipeptidyl peptidase II, produced by Streptomyces sp. MJ995-OF5. I. Taxonomy of producing strain, fermentation, isolation, physico-chemical properties and biological properties.

A new inhibitor of dipeptidyl peptidase II (DPP-II, EC 3.4.14.2), designated as epostatin, was discovered in the fermentation broth of a strain isolated in our institute. The strain has been identified as Streptomyces sp. MJ995-OF5 on the basis of taxonomic studies. Epostatin was obtained as a yellow powder after seqential purification by chromatography on Diaion HP-20, n-butanol extraction, Sephadex LH-20 column chromatography and centrifugal partition chromatography (CPC). Epostatin inhibited DPP-II competitively in a dose dependent manner. The compound was slightly inhibitory against other dipeptidyl peptidases.

Alanine↗