PubMed Health⌕ Search

Biomedical subjects

H Takeuchi

Publications and source records attributed to H Takeuchi.

At least 649 records · Page 36Linked to original sources
PubMed1990

Pharmacological characteristics of two different types of inhibitory GABA receptors on Achatina fulica neurones.

GABA (gamma-aminobutyric acid) receptors of Achatina fulica neurones have been classified into two types associated with neuronal inhibition and one type with excitation. The pharmacological features of muscimol I and baclofen types associated with inhibition were investigated in this study. Activation of muscimol I type receptors on TAN (tonically autoactive neurone) by GABA, muscimol and trans-4-aminocrotonic acid (TACA) produced a transient outward current (Iout) with an increase in membrane conductance (g). Their relative potencies at GABA ED50 (approximately 10(-4) M) were: GABA: muscimol: TACA = 1:0.6:0.3. The relation between Iout and g increase (delta g) induced by various concentrations of these compounds was linear. The Hill coefficients for GABA were close to 1.0. The GABA effects were potentiated by pentobarbitone, antagonized competitively by pitrazepin and non-competitively by picrotoxin and diazepam, and unaffected by bicuculline. The reversal potentials of the effects of GABA, muscimol and TACA on TAN changed under various [Cl-]0 according to the Nernst equation for Ec1, but not under various [K+]0 and [Na+]0. Activation of baclofen type GABA receptors on RPeNLN (right pedal nerve large neurone) by GABA and (+/-)-baclofen produced a slow Iout with an increase in g. The two compounds were almost equipotent (ED50: approximately 3 x 10(-4) M). The relation between Iout and delta g produced by various concentrations was linear. The Hill coefficients for GABA were also close to 1.0. The reversal potentials of GABA and (+/-)-baclofen on RPeNLN changed under various [K+]0 according to the Nernst equation for EK, but not under various [Cl-]0 and [Na+]0. The two compounds hardly affected the voltage-gated and slowly inactivating calcium current. The Iout produced by GABA and (+/-)-baclofen was reduced by tetraethylammonium chloride, but was unaffected by 4-aminopyridine, bicuculline, pitrazepin and picrotoxin. In conclusion, the pharmacological features of muscimol I type GABA receptors are partly comparable to those of mammalian GABAA receptors, except for the influences of bicuculline and diazepam: the features of the baclofen type GABA receptor, which did not occur with muscimol I type receptors in the same neurone, were similar to those of GABAB.

Animals↗
PubMed1990

Comparative study of d-diltiazem and its analogues as calcium antagonists in snail neurones.

The blocking effects of d-diltiazem, its metabolites, deacetyl-d-diltiazem (d-M1), deacetyl-N-demethyl-d-diltiazem (d-M2), deacetyl-O-demethyl-d-diltiazem (d-M4) and deacetyl-N, O-demethyl-d-diltiazem (d-M6) and 1-diltiazem were investigated on the voltage-gated calcium current (ICa) of an Achatina neurone. Based on the IC50 values, the order of potency was: d-diltiazem (0.426 mM), d-M2 (0.456), d-M1 (0.491), 1-diltiazem (0.759) greater than d-M4 (1.212) greater than d-M6 (greater than 2.000). Assuming that the IC50 reflects the KD for resting Ca2+ channels (Kr), steady state activation studies gave KD values for the inactivated channels (Ki) and Kr/Ki ratios of 0.122 mM (Ki) and 3.52 (Kr/Ki) (d-diltiazem), 0.112 and 6.98 (1-diltiazem), 0.083 and 6.07 (d-M1) and 0.156 and 2.97 (d-M2). All drugs tested showed a certain degree of voltage-dependence. The further percentage reduction in the normalized ICa after high frequency stimulation demonstrated the use-dependence of: 1-diltiazem (27.5%), d-diltiazem (26.3) greater than d-M2 (19.2) greater than d-M1 (16.7) greater than d-M6 (9.8). The voltage- and use-dependence of these drugs are consistent with their Ca2+ antagonistic properties.

Animals↗
PubMed1990

Environments and conformations of tryptophan side chains of gramicidin A in phospholipid bilayers studied by Raman spectroscopy.

Raman spectroscopy has been used to investigate the hydrophobic interaction of the indole ring with the environments, the water accessibility to the N1H site, and the conformation about the C beta-C3 bond for the four tryptophan side chains of gramicidin A incorporated into phospholipid bilayers. Most of the tryptophan side chains of the head-to-head helical dimer transmembrane channel are strongly interacting with the lipid hydrocarbon chains, and the hydrophobic interactions for the rest increase with increasing hydrocarbon chain length of the lipid. One tryptophan side chain (probably Trp-15) is accessible to water molecules, another (Trp-9) is deeply buried in the bilayer and inaccessible, and the accessibilities of the remaining two (Trp-11 and Trp-13) depend on the bilayer thickness. The torsional angle about the C beta-C3 bond is found to be +/- 90 degrees for all the tryptophans irrespective of the membrane thickness. Binding of the sodium cation to the channel does not change the torsional angles but decreases the water accessibilities of two tryptophans (Trp-11 and Trp-13) considerably. In conjunction with a slight spectral change in the amide III region, it is suggested that the sodium binding causes a partial change in the main-chain conformation around Trp-11 and Trp-13, which results in the movements of these side chains toward the bilayer center. Two models consistent with the present Raman data are proposed for the tryptophan orientation in the dominant channel structure.

Chemical Phenomena↗
PubMed1990

Comparison of oxygen supply methods for cultures of shear-stress sensitive organisms including animal cell culture.

In animal cell culture, oxygen supply sometimes limits cell growth. Therefore, four oxygen supply methods (free surface aeration, porous Teflon tubing, perfluorocarbon addition and external aerator) were compared in terms of oxygen transfer rate for suspension culture of animal cells. Oxygen transfer rate with the free surface aeration was dependent on the vertical position of the impeller and the stirred Reynolds number for h/HL greater than 0.35, but no effect of the impeller position was observed for h/HL less than 0.35. The relationship between the Reynolds and Sherwood numbers could be expressed by simple correlations. These correlations could also be applied to oxygen transfer using porous Teflon tubing. When oxygen was supplied with perfluorocarbon saturated with air, the overall mass transfer coefficient KL was estimated to be about 9.0 X 10(-3) cm s-1, which was five-fold greater than that of the surface aeration. Maximum cell densities which would be supported by four methods were calculated from values of KLa for different sizes of fermentor assuming that oxygen supply would be the rate-limiting factor in animal cell culture.

Animals↗
PubMed1990

Blood-brain barrier disruption caused by impairment of cerebral autoregulation during chronic cerebral vasospasm in primates.

Impairment of the cerebral autoregulation and its effects on the development of brain oedema during chronic cerebral vasospasm after subarachnoid haemorrhage (SAH) were studied in primates. The unilateral induction of SAH by clot placement around cerebral arteries produced a moderate degree of vasospasm (more than 40% reduction of vessel caliber on angiogram) seven days after SAH. Abolishment of autoregulation was observed in the territories of the cerebral hemisphere supplied by the vasospastic arteries. It was found that in this region an increase in cerebral perfusion pressure easily produced a marked elevation of the cerebral blood flow over the upper limit of autoregulation threshold resulting in disruption of the blood-brain barrier.

Animals↗
PubMed1990

The role of prostatic specific antigen in monitoring prostatic cancer and its prognostic importance.

Serum prostatic specific antigen (PA) and prostatic acid phosphatase (PAP) levels were measured in 113 untreated patients with prostatic cancer and in 137 patients with benign prostatic hypertrophy (BPH). Of the 113 cancer patients, 81% and 69%, respectively, were detectable by means of PA or PAP assay alone. PA was a more sensitive indicator, than PAP in all stages, especially localized disease (stages A, B and C). Using the BPH group as a negative control, specificities of PA and PAP were 81% and 94% respectively. In another group of 68 patients with BPH whose blood samples were taken immediately after prostatic manipulation, both PA and PAP levels were elevated significantly. In 87 of the 113 cancer patients the two markers were serially determined, and 22 patients presented disease progression. Concerning the sensitivity within 6 months before progression, PA appears to be more reliable than PAP in early detection of disease progression. According to Kaplan-Meier projections, the patients with normal pretreatment PA levels had significantly longer intervals to progression than did those with moderate to marked PA elevation (more than 100 ng/ml) (P less than 0.05). This study shows that PA is more reliable than PAP for detection and monitoring of prostatic cancer. Pretreatment PA levels appear to be of a high prognostic value for time to progression, irrespective of stage and treatment regimen.

Acid Phosphatase↗
PubMed1990

Lectin-binding glycoconjugates and immunoreactive proteoglycans in resorption pits freshly excavated by isolated rabbit osteoclasts.

Staining with FITC-conjugated concanavalin A, wheatgerm agglutinin and peanut agglutinin demonstrated that abundant sugar residues are present in resorption pits produced in vitro and over the cell surface of rabbit osteoclasts resorbing bovine femoral bone slices. After chondroitinase ABC digestion the stubs of chondroitin 4-sulphate and dermatan sulphate could be detected in the resorption pits by monoclonal antibodies.

Animals↗
PubMed1990

A band of F-actin containing podosomes is involved in bone resorption by osteoclasts.

Isolated rabbit osteoclasts cultured on devitalized thin bone slices excavate resorption lacunae that can be visualized with brightfield or phase-contrast microscopy. Superimposition of the brightfield images of such resorption lacunae and the fluorescence images of the corresponding osteoclasts after fixation and staining with rhodamine-conjugated phalloidin revealed that a bright fluorescent band of F-actin-containing podosomes precisely outlined the resorption lacunae in stationary osteoclasts. When the resorption lacunae were being extended laterally, the clearly delineated band of podosomes corresponded to the advancing edge of the resorbing osteoclast and the most recently excavated part of the lacunae. Reshaping and reorganization of the bright bands preceded development of the lateral boundary of the lacunae. Podosomes forming these bands were highly dynamic, changed in size and location, and appeared and disappeared continuously. Their lifespan varied between 2 and 12 min. Similar bands were also seen in vivo in bone-resorbing osteoclasts on the endocranial surface of growing calvariae. Podosomes disappeared in osteoclasts treated with calcitonin, resulting in the disruption of the fluorescent bands. Our results suggest that podosomes are an essential part of the resorption apparatus of osteoclasts.

Actins↗
PubMed1990

Molecular cloning and partial DNA sequencing of the collagenase gene of Vibrio alginolyticus.

DNA fragments Vibrio alginolyticus chemovar iophagus, at least 7 kb in length, were ligated to Escherichia coli expression vectors. Three clones of Escherichia coli HB101 (pLCO-1, pLCO-2, pLCO-3) were obtained by the colony immunoblotting method using anti-collagenase antibody. In Escherichia coli, all these genes produced collagenase antigens which were detected with Western blotting. The amino acid sequence of chemically purified collagenase fragments was also analyzed. An approximately 2.5 kb DNA fragment of the pLCO-1 clone was sequenced, and we found that portions of the deduced amino acid sequence of the chemically analyzed fragments. Therefore, it is highly probable that the gene studied in the present experiment is truly a collagenase structural gene.

Amino Acid Sequence↗
PubMed1990

Complete nucleotide sequence of the structural gene for alkaline proteinase from Pseudomonas aeruginosa IFO 3455.

The DNA-encoding alkaline proteinase (AP) of Pseudomonas aeruginosa IFO 3455 was cloned, and its complete nucleotide sequence was determined. When the cloned gene was ligated to pUC18, the Escherichia coli expression vector, the gene-incorporated bacteria expressed high levels of both AP activity and AP antigens. The amino acid sequence deduced from the nucleotide sequence revealed that the mature AP consists of 467 amino acids with a relative molecular weight of 49,507. The amino acid composition predicted from the DNA sequence was similar to the chemically determined composition of purified AP reported previously. The amino acid sequence analysis revealed that both the N-terminal side sequence of the purified AP and several internal lysyl peptide fragments were identical to the deduced amino acid sequences. The percent homology of amino acid sequences between AP and Serratia protease was about 55%. The zinc ligands and an active site of the AP were predicted by comparing the structure of the enzyme with of Serratia protease, thermolysin, Bacillus subtilis neutral protease, and Pseudomonas elastase.

Amino Acid Sequence↗
PubMed1990

Polycystic kidney of autosomal dominant inheritance, polycystic liver and congenital hepatic fibrosis in a single kindred.

A family with clear evidence of concomitant congenital hepatic fibrosis, polycystic liver and adult-type polycystic kidney is reported. The autosomal dominant inheritance of polycystic kidney in association with either liver cyst or hepatic fibrosis in this family suggests that various combinations of hepatic and renal fibrocystic lesions are possible to occur. Additionally, in the proband a very rare association of congenital hepatic fibrosis and cerebral aneurysm was present.

Adult↗
PubMed1990

Particle design of tolbutamide by the spherical crystallization technique. III. Micromeritic properties and dissolution rate of tolbutamide spherical agglomerates prepared by the quasi-emulsion solvent diffusion method and the solvent change method.

With the objective of modifying the micromeritic properties of tolbutamide (i.e., to manufacture a highly functional powder form), particle design was attempted using a quasi-emulsion solvent diffusion (QESD) method, and the micromeritic properties and dissolution rate of the obtained spherical agglomerates were evaluated by comparison with agglomerates prepared by the solvent change (SC) method. For the production of tolbutamide agglomerates by the QESD method, a necessary condition was the addition of a sucrose fatty acid ester to the system as an emulsifying agent. The particle diameter of the agglomerates obtained by the QESD method depended on the size of the initially formed quasi-emulsion droplets, which in turn depended on the viscosity of the solution. In addition, the agglomerates were nearly perfectly spherical in shape. In the QESD method, the quasi-emulsion droplets crystallized instantaneously from the droplet surface inward. The resultant agglomerates were dense, had great mechanical strength and showed excellent flowability due to their perfect spherical shape. On the other hand, the agglomerates produced by the SC method were conglomerates of primary crystals, and fine, needle-like crystals formed on their surface. As a result, these agglomerates had a large specific surface area, and they therefore showed greater solubility than the agglomerates prepared by the QESD method.

Chemistry, Pharmaceutical↗
PubMed1990

Flow cytometry to evaluate acrosome-reacted sperm.

Flow cytometry was used in the scoring of acrosome-reacted human sperm. Propidium iodide was used for detection of the nonviability of the sperm. Fluoresceinated pea lectin was used to detect acrosome-reacted sperm. The results obtained by flow cytometry and those obtained by fluorescence microscopy were compared to determine if flow cytometry can serve as a more accurate, faster, and simpler method. It was possible to detect human sperm by flow cytometry. The percentage of propidium iodide labeled sperm determined by flow cytometry was close to that obtained by fluorescence microscopy. Comparison of the percentage of acrosome-reacted sperm determined by flow cytometry and fluorescence microscopy showed that these methods gave very similar results (r = 0.98, p less than 0.001). Objective scoring of more sperm was possible by flow cytometry than by fluorescence microscopy, and flow cytometry was useful as a simple method for evaluation of acrosome-reacted human sperm.

Acrosome↗
PubMed1990

[Effects of novel immunosuppressant FK 506 in acute experimental allergic encephalomyelitis].

Experimental allergic encephalomyelitis (EAE) is a T cell-mediated autoimmune disease. It is widely used as an animal model of multiple sclerosis (MS). We studied the prophylactic effects of FK 506 electrophysiologically and immunohistochemically in acute EAE. Female Lewis rats were sensitized with guinea pig spinal cord in complete Freund's adjuvant. FK 506 suspended in distilled water was orally administered at 1.0, 3.2, 5.0 or 10.0 mg/kg per day for 12 successive days starting from the day of sensitization. A placebo was used as the control. Administration of FK 506 at doses of 3.2 mg/kg per day and over significantly delayed the onset of clinical signs. However, the FK 506 group showed a relapse or a chronic state following the onset of EAE. We made a time course recording of cortical somatosensory evoked potential (cortical SEP: P 15). P 15 latency in the placebo group was significantly delayed in accordance with the clinical signs and showed immediate improvement upon recovery. Prolongation of P 15 latency in the FK 506 group also occurred concomitantly with the clinical signs, but the delay continued after the loss of symptoms as well. After the onset of EAE, the infiltrating lymphocyte subset was examined by the avidin-biotin peroxidase complex (ABC) method in the lumbar spinal cord. In the placebo group, the number of OX3+ (Ia) cells and the W 3 25+: OX8+ (helper/inducer T: suppressor/cytotoxic T) ratio clearly reflected the development and remission of EAE. In the FK 506 group, however, increases in OX8+ lymphocytes were observed irrespective of clinical sign fluctuation, and there were corresponding decreases in the W 3/25+: OX8+ ratio.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1990

[Diagnosis of the upper urothelial tumor using a rigid ureteroscope].

We preoperatively diagnosed four cases suspected as malignant urothelial tumor of upper urinary tract using a rigid ureteroscope. In three cases of ureter tumor, biopsy was successful and showed low grade malignancy. Nephroureterectomy was performed in two cases with upper ureteral tumor. The tumor was fulgurated ureteroscopically in a case of lower ureteral tumor. In one case of renal pelvic tumor, biopsy was unsuccessful though the tumor was observed as a papillary configuration. Successively, biopsy using a flexible ureteroscope was performed and the tumor was treated by fulguration. Ureteroscopy is very useful for preoperative diagnosis of ureteral tumor and selection of treatment.

Carcinoma, Transitional Cell↗
PubMed1990

[Comparison of antagonistic effects of several drugs on calcium current in a giant neuron of an African snail (Achatina fulica Férussac)].

Antagonistic effects of several drugs on the calcium current (ICa) of a giant neurone, PON (periodically oscillating neurone), of an African snail (Achatina fulica Ferussac) were compared under the voltage clamp. According to their IC50 values and the confidence limit at 95%, the order of effectiveness of the drugs was: brovincamine, verapamil greater than or equal to isoperisone, eperisone, d-diltiazem greater than or equal to vincamine, l-diltiazem, tolperisone. Their IC50 values were assumed to be the dissociation constants of Ca2+ channels in the resting state (Kr). Voltage dependence of these drugs was examined by measuring the steady-state inactivation curves. From the results obtained, the dissociation constants of the channels in the inactivated state (Ki) and the Kr/Ki ratio were calculated for each drug. The order of Ki values of these drugs was: isoperisone, brovincamine, verapamil less than or equal to eperisone, l-diltiazem, d-diltiazem, tolperisone. The use dependence of the drugs was also examined by measuring the further decrease of ICa amplitude caused by high frequent stimulations. We observed that verapamil, brovincamine, d-diltiazem and l-diltiazem were use dependent, whereas eperisone, tolperisone and isoperisone were not.

Animals↗
PubMed1990

[Eaton-Lambert syndrome manifested by respiratory failure associated with small cell carcinoma of the lung].

A 63-year-old man with Eaton-Lambert syndrome manifested by marked respiratory failure was reported. He began to notice blepharoptosis and diplopia in September, 1987, followed by weakness and easy fatigability in bulbar, neck and limb muscles in association with impotence by February, 1988. On admission in August, 1988, Gowers' sign, decreased tendon reflexes and muscle weakness improved by the injection of edrophonium were found. Anti-acetylcholine receptor antibody was negative. Single muscle action potential evoked in the thenar muscle was abnormally low in amplitude with the stimulation of the median nerve: repetitive nerve stimulation study revealed the waning at the low rates, but the waxing at the high rate (30 Hz), suggesting the diagnosis of Eaton-Lambert syndrome. Early gastric cancer (adenocarcinoma) was diagnosed from needle biopsy specimens in August, 1988, but no other neoplasm including thymoma or lung cancer was found. After subtotal gastric resection in September, 1988, he failed into respiratory failure, requiring artificial ventilation for seven months. Plasmapheresis and drugs such as anticholinesterase, guanidine hydrochloride, and corticosteroid were ineffective for the recovery from weakness in respiratory muscle. Lung cancer was suspected, based on a chest X-ray in March, 1989, and one month later he died of pneumonia. At autopsy, small cell carcinoma of the lung was observed, but there was neither recurrence nor metastasis of the gastric cancer. Emphasis was placed on the respiratory failure in Eaton-Lambert syndrome which has rarely been reported.

Adenocarcinoma↗