Biomedical subjects

S Tanabe

Publications and source records attributed to S Tanabe.

At least 19 recordsLinked to original sources

PubMed1992

Sphingosine inhibits factor Xa-catalyzed prothrombin activation on the surface of cultured calf pulmonary artery endothelium perturbed by hydrogen peroxide.

The effects of hydrogen peroxide on factor Xa-catalyzed prothrombin activation on the surface of vascular endothelial cells, and the inhibitory effect of sphingosine on prothrombin activation were studied in cultured calf pulmonary artery endothelial cells (CPAEC). Hydrogen peroxide enhanced factor Xa-catalyzed prothrombin activation on the cell surface in a time and dose-dependent manner. Sphingosine, a potent inhibitor of protein kinase C and the extrinsic pathway of blood coagulation, showed a partial inhibition of prothrombin activation on the surface of CPAEC. When cells were perturbed by hydrogen peroxide, sphingosine inhibited prothrombin activation and displaced factor Xa bound to the cell surface.

Amino Acid Sequence↗

PubMed1992

Residue pattern and dietary intake of persistent organochlorine compounds in foodstuffs from Vietnam.

Concentrations of polychlorobiphenyls (PCBs), hexachlorocyclohexane isomers (HCHs), DDT compounds (DDTs), hexachlorobenzene (HCB), aldrin, dieldrin, heptachlor and heptachlor epoxide were determined in foodstuffs collected from different locations in Vietnam. Elevated levels of PCBs, DDTs, HCHs, and aldrin and dieldrin were found in animal fat, butter, meat, and seafood. Caviar and butter samples imported from the Soviet Union contained considerably higher amounts of PCBs, HCHs and DDTs. The average daily intake of some organochlorines by Vietnamese people were higher than those observed in most of the developed nations. The dietary intake of DDTs was the highest among various chemicals studied. Interestingly, the daily dietary intake of PCBs was comparable to those in developed countries. Fish, shellfish, prawn, and crab were the primary route of DDTs to humans, whereas cereals and vegetables were the predominant sources of PCBs and HCHs.

Food Analysis↗

PubMed1992

Characteristic trend of persistent organochlorine contamination in wildlife from a tropical agricultural watershed, south India.

The residue levels of persistent organochlorines, such as HCH (BHC: 1,2,3,4,5,6-hexachlorocyclohexane) isomers, DDT [1,1,1-trichloro-2,2-bis (p-chlorophenyl) ethane] compounds, PCBs (polychlorobiphenyls) and HCB (hexachlorobenzene), were measured in wildlife. The wildlife were sampled from terrestrial and aquatic habitats in and around the agricultural watershed of Parangipettai, South India. On the basis of overall concentrations sigma HCH ranked first followed by sigma DDT, sigma PCB and HCB, reflecting the increasing usage of HCH in recent years in India. The residue levels of organochlorines in birds varied according to their feeding habits and showed the following pattern: inland piscivores and scavengers greater than coastal piscivores greater than insectivores greater than omnivores greater than granivores. High levels of HCH and DDT residues were recorded in Pond heron and Cattle egret which feed in the agricultural fields. Comparison of HCH concentrations in fish and birds in the study area to other locations was made to further understand the dynamics of contaminant accumulation in tropical wildlife. Regarding birds, a wide variation in residue levels could be seen among various countries, with tropical regions registering high levels. In contrast, the variation is not prominent in the case of fish. The residue levels in fish measured in the present study were generally comparable to values reported from other locations. This suggests that the bioavailability of contaminants to the aquatic fauna is less due to the smaller flux and shorter residence time of these chemicals in the tropics.

Agrochemicals↗

PubMed1992

Isomer-specific analysis of PCBs including toxic coplanar isomers in canned cod livers commercially processed in Poland.

Concentrations of highly toxic coplanar non-ortho (IUPAC Nos. 77, 126 and 169), mono-ortho (IUPAC Nos. 60, 105, 118 and 157), di-ortho (IUPAC Nos. 128, 139 and 170) members and 73 other isomers and congeners of PCBs were determined in canned cod livers W 9tróbka rybna po Kaukasku produced by a company in Gdańsk, Poland in early 1990. Total PCB concentrations ranged over 1.2-2.6 micrograms/g wet mass. Concentrations of ten toxic coplanar PCBs (IUPAC Nos. 77, 126, 169, 60, 105, 118, 156, 128, 138, and 170) were found to be in the range of 360 to 690 ng/g wet mass and their TCDD TEQs were 370 to 530 pg/g for aryl hydrocarbon hydroxylase and from 290-430 pg/g for ethoxy-resorufin O-deethylase. Among these toxic congeners IUPAC No. 126, which showed 84% of total TEQ values, imparted most significant toxic threat. Considering these observations, canned cod livers are likely to pose concern to human health since they exceed the tolerance limit of total PCBs (2.0 micrograms/g for edible parts of fishery products) and contain significant residue levels of toxic coplanar PCBs.

Animals↗

PubMed1992

Results of reoperation for failed microvascular decompression.

Among 64 patients with hemifacial spasm (HFS) and 60 with trigeminal neuralgia (TN) treated by microvascular decompression (MVD), repeated MVD performed on 3 cases with HFS resulted in the absence of spasm in all cases. In 7 cases with TN, this technique resulted in complete remission in 2, recurrence in 3, and no pain relief in 2 cases. MVD was more effective on HFS than on TN in repeated procedures as well as for initial treatment. The cause of recurrence of HFS was attributed to the inadequate cushion effect of muscle as a prosthesis, while that for TN was suspected to be related more to post-operative fibrotic adhesions formed around the fifth nerve.

Adult↗

PubMed1992

Decreased hypothalamic and medullary GABA turnover in spontaneously hypertensive rats.

OBJECTIVE: The aim was to assess whether Gamma-aminobutyric acid (GABA) neurone activities in the central nervous system, especially in the hypothalamus and medulla oblangata, are altered in hypertension. METHODS: Central GABA content and turnover rate were measured in spontaneously hypertensive rats (SHR) and their normotensive Wistar Kyoto controls (WKY). GABA content was determined with high performance liquid chromatography, and in vivo GABA turnover rates were estimated by GABA accumulation after injection of amino-oxyacetic acid, a selective inhibitor of GABA degrading system. Two groups of nine week old male rats (32 SHR and 32 WKY) were used. RESULTS: GABA concentrations in cerebrospinal fluid were lower in SHR than in WKY. Since hypothalamus and medulla oblongata are the possible active sites of this system, basal GABA contents and in vivo GABA turnover rates were measured in hypothalamus and medulla oblongata. Basal GABA content in the medulla oblongata and hypothalamus was almost equal in SHR and WKY. On the other hand, GABA turnover rates were significantly lower in SHR than in WKY in both the hypothalamus and the medulla. CONCLUSIONS: Since it is known that GABA is an inhibitory neurotransmitter in the central nervous system and that it controls autonomic and cardiovascular activities, the findings suggest that the decreased hypothalamic and medullary GABAergic activities may permit sympathetic hyperactivity to contribute to the increase in blood pressure in SHR.

Aminooxyacetic Acid↗

PubMed1992

Biochemical studies on oral toxicity of ricin. IV. A fate of orally administered ricin in rats.

After oral administration of ricin in rats, its distribution in the gastrointestinal tract, body fluids and principal organs was determined by an enzyme immunoassay, and the immunoreactive ricin detected was identified by gel filtration followed by sodium dodecyl sulfate polyacrylamide gel electrophoresis, protein blotting and the immunobinding method. When ricin D (10 mg/kg rat) was given orally to a rat, which dose is equivalent to 1/3 LD50, about 75% of the ricin was found in the stomach and small intestine within 2 h, and most of it was transferred to the large intestine after 24 h. It was also demonstrated by an in vitro toxicity test of immunoreactive ricin in the blood and lymph obtained from the intoxicated rats that a part of the ricin was absorbed from the small intestine into the tissues and organs via the circulatory systems (lymphatic and blood vessels) as the active ricin. The participation of the blood vessels was greater in the absorption of ricin from the gastrointestinal tract than that of the lymphatic system. Ricin, after absorption, was detected in liver and spleen and ricin found in the liver was predominantly in the form of intact ricin, although an undetectable amount of ricin in other organs cannot be eliminated. These results infer that a small fraction of orally-given ricin was transferred to the circulating system and was responsible for rat's death as in the case of i.p. administration.

Administration, Oral↗

PubMed1992

Biochemical studies on oral toxicity of ricin. V. The role of lectin activity in the intestinal absorption of ricin.

In order to investigate a possible role of lectin activity of ricin in its absorption from the small intestine, we prepared two ricin derivatives. BMH-ricin, prepared by crosslinking A and B chains of ricin with 1,6-bismaleimidohexane, was nearly non-toxic but the lectin activity was unaltered. And, NBS-ricin, prepared by the oxidation of tryptophanyl residues of ricin with N-bromosuccinimide, was not only non-toxic but also non-lectinic. After the oral administration of ricin derivatives to rats, their interaction with the digestive tract and absorption into the circulatory systems have been compared with those of ricin, immunochemically and histologically. It was shown by immunostaining that ricin and BMH-ricin could bind to the intestinal mucosa, whereas NBS-ricin could not. No appreciable damage in the small intestine from rats treated with either BMH-ricin or NBS-ricin has been observed, in contrast to ricin treatment where severe impairment of the small intestinal tissues resulted after 5 h. Immunoreactive ricin in the liver has been determined with the ricin enzyme immunoassay (EIA). When compared at 48 h after oral administration, NBS-ricin was not detected, whereas BMH-ricin was found to be 38 micrograms/liver and ricin 100 micrograms/liver. From these results, it was inferred that the lectin activity of ricin plays an important role in the absorption of ricin from the small intestine and that the absorption of ricin protein was enhanced by its high toxicity.

Administration, Oral↗

PubMed1992

Effects of calphobindin II (annexin VI) on procoagulant and anticoagulant activities of cultured endothelial cells.

Effects of human placental calphobindin II (CPB-II) on the protein C activation and prothrombin activation on the cell surface of cultured calf pulmonary arterial endothelial cells have been investigated. CPB-II inhibited thrombin generation by factor Xa bound to the surface of the cultured endothelial cells in a dose-dependent manner. The amount (IC50) of CPB-II causing the inhibition at 50% was estimated to be approximately 10 nM. CPB-II was found to be ineffective, however, in the protein C activation by thrombin-thrombomodulin (TM) complex on the cell surface. Assay using purified TM revealed that CPB-II was able to exhibit the inhibitory potency for the protein C activation exclusively in the reconstituted system with negatively charged phospholipids. These results suggest that the neutral phospholipids participate in the protein C activation through the thrombin-TM system on the endothelial cell surface. The ability of CPB-II to inhibit procoagulant activity without affecting anticoagulant activity on the cultured endothelial cells is probably related to its potential physiological function, while it is able to exert various degrees of influence upon these activities in blood coagulation by interacting with negatively charged phospholipids in vitro.

Amino Acid Sequence↗

PubMed1992

High performance liquid chromatographic determination of bound sulfide and sulfite and thiosulfate at their low levels in human serum by pre-column fluorescence derivatization with monobromobimane.

A sensitive and specific high performance liquid chromatographic method for the determination of sulfide, sulfite, and thiosulfate was established. Inorganic sulfur anions were converted into fluorescent derivatives with monobromobimane. The derivatives were separated on a coupled column chromatography with a reversed-phase octadecyl silica column connected with a weakly basic anion exchanger column by isocratic elution with acetic acid solution (pH 3)-acetonitrile (13:3, v/v) containing 25 mM NaClO4. The method was applied to the determination of bound sulfide and sulfite and thiosulfate in normal human serum. Thiosulfate could be determined directly by use of an ultrafiltered sample. For the determination of bound sulfide and sulfite, the pretreatment step with continuous flow gas dialysis was effective for the sample after releasing sulfide and sulfite by reduction with dithiothreitol. The limits of quantification by the present method were 0.05 microM for thiosulfate, 0.5 microM for bound sulfide, and 0.2 microM for bound sulfite.

Bridged Bicyclo Compounds↗

PubMed1992

Interaction of toxic lectin ricin with epithelial cells of rat small intestine in vitro.

To clarify the mechanism of oral toxicity of ricin, the interaction of ricin with the epithelial cells isolated from rat small intestine was compared in vitro with those of other plant lectins by two different determinations, i.e., viability and cytotoxicity. After incubation of the cells for 1 h at 37 degrees C with ricin, B-chain, castor bean hemagglutinin (CBH), soybean agglutinin (SBA), wheat germ agglutinin (WGA), concanavalin A (Con A), and peanut agglutinin (PNA), respectively, followed by staining with trypan blue, ricin and ricin B-chain as well as CBH and SBA were found to have effectively reduced the number of viable cells. On the contrary, only ricin inhibited protein synthesis in the cells and the effect was blocked by D-galactose. Additional experiments employing [125I]-labeled ricin strongly suggested that ricin was first bound via its B-chain to the galactosyl residues on the cell surface followed by internalization into cells as the whole 62 kDa molecule. These results infer first that ricin, as well as other lectins mentioned above, was able to reduce viability of the epithelial cells of rat small intestine by direct binding to the cell surface. The second effect, specific to ricin, was the inhibition of cellular protein synthesis.

Animals↗

PubMed1992

Role of sympathetic nerve inhibition in the vasodepressor effect of bromocriptine in normotensive and hypertensive rats.

This study aimed to elucidate the mechanism of the hypotensive effect of bromocriptine (BRC), and to investigate whether or not the effects of BRC on the sympathetic nervous system are altered in hypertension. BRC was administered intravenously to normotensive and spontaneously hypertensive rats (SHR). It elicited hypotensive effects dose-dependently in urethane-anaesthetized normotensive rats, an effect which was antagonized with metoclopramide. Pretreatment with intravenous hexamethonium attenuated the hypotensive effect of BRC. BRC decreased plasma norepinephrine (NE) without inhibiting the sympathetic nerve spikes recorded from the postganglionic sympathetic nerve bundle. The hypotensive effect of BRC was significantly greater in SHR than in Wistar Kyoto Rats (WKY). Decrease in NE by BRC was also significantly greater in SHR than in WKY. These results suggest that the hypotensive effect of BRC is induced by suppression of NE release, not by inhibition of sympathetic nerve spikes, and that the dopaminergic presynaptic inhibition is attenuated in SHR.

Animals↗

PubMed1992

[The limits of recovery in hydronephrosis. An experimental pathological study].

The object of this experimental study is to elucidate the limits of recovery in hydronephrosis. Hydronephrosis in the rabbit kidney was made by left ureteric ligation for 1, 2, 3 and 4 weeks, followed by relief of obstruction with uretero-ureteric anastomosis. Two and 4 weeks after relief, histopathological examination was performed. In proportion to the obstructive period, both proximal tubule and thin portion of Henle's loop showed atrophy of epithelial cells, multi-laminar thickening of basement membranes, and splitting between epithelium and basement membranes. The interstitium showed edema and subsequent fibrosis. These damages were thought to be due to severe ischemia, which such tubules did not recover and even showed more advanced damages after relief. On the other hand, thick portion of Henle's loop, distal tubule and collecting duct showed advanced compression atrophy and dilated lumen, while no severe ischemic damage was demonstrated. Therefore, after relief, they showed recovery, and, even in the case of no recovery, they showed no advanced damages. In hydronephrosis, severe ischemic damages brought about a loss of the ability of recovery.

Animals↗

PubMed1992

Cytoprotective effect of dilazep on hydrogen peroxide-perturbed vascular endothelial cells.

The effect of dilazep and dimethyl thiourea (DMTU) on the hydrogen peroxide-derived injury of culture pulmonary artery epithelial cells (CPAEC) was assessed by colorimetric assay of MTT formazan (MTT formazan assay). When CPAEC were treated with hydrogen peroxide, neither cell lysis nor detachment of the cells from surface of the well was observed. However, the MTT formazan formation was decreased in a time and dose dependent manner. The decrease in the formation was significantly suppressed in the presence of dilazep (0.1 to 10 microM) or DMTU (0.01 to 0.3 microM). CPAEC treated with hydrogen peroxide in the same way enhanced an activation of prothrombin, and this enhancement was significantly inhibited in the presence of dilazep (1 to 3 microM). These data indicate that dilazep exerts a cytoprotective effect against challenges of intracellular oxidant produced by hydrogen peroxide and suppresses augmented procoagulant activity of injured cells.

Animals↗

PubMed1992

Effect of manidipine on cardiac hypertrophy and coronary circulation in DOCA/salt hypertensive rats.

The effect of manidipine on cardiac hypertrophy, coronary circulation, left ventricular weight and maximal coronary flow in hypertension was measured in DOCA/salt treated systolic hypertensive rats with and without manidipine treatment. Normotensive rats were used as controls. After feeding with 0.05% manidipine-containing food, blood pressure was reduced only in DOCA/salt hypertensive rats, but not in control rats. After 3 weeks of treatment, sodium excretion was significantly increased in DOCA/salt-treated rats with or without manidipine treatment. Hearts were removed and perfused with modified Krebs-Henseleit solution with adenosine (5 x 10(-5) M) in a Langendorff apparatus. Maximal coronary flow (MCF) was significantly decreased only in DOCA/salt hypertensive rats without treatment, while manidipine treatment restored MCF. Left ventricular weight/body weight was also markedly greater in DOCA/salt-treated rats not given manidipine. Left ventricular weight in DOCA/salt-treated rats given manidipine was significantly reduced compared with DOCA/salt hypertensive rats without treatment, although it was heavier than in the control animals. Morphological examination showed that the increased wall/lumen ratio in DOCA/salt hypertensive rats was reduced by manidipine treatment. These findings suggest that treatment with manidipine in DOCA/salt hypertensive rats lowered high blood pressure and improved impaired coronary circulation with a reduction in left ventricular and vascular hypertrophy.

Aldosterone↗

PubMed1992

3,5-Dihydroxyphenyl-glycine: a potent agonist of metabotropic glutamate receptors.

An amino acid, 3,5-dihydroxyphenylglycine (DHPG) induced current responses in Xenopus oocytes expressing a metabotropic glutamate receptor clone mGluR1. Apparent EC50 of DHPG for mGluR1 was slightly lower than that of (+-)-1-aminocyclopentane-trans-1,3-dicarboxylic acid (ACPD). DHPG responses were partially inhibited by 2-amino-3-phosphonopropionic acid (AP-3). DHPG had no effect on ionotropic glutamate receptors whose expression was induced in the oocytes following injection of poly(A)+ mRNA of rat brains. In hippocampal slices, DHPG produced slow excitation of pyramidal cells, resulting from a depression of Ca(2+)-dependent K+ current and a voltage-dependent K+ current. These results indicate that DHPG is a specific and potent agonist of mGluRs.

2-Amino-5-phosphonovalerate↗

PubMed1992

Geographical aspects of bcl-2 gene involvement in Japanese patients with non-Hodgkin's B-cell lymphomas.

Using three separate bcl-2 probes, we examined involvement of the bcl-2 gene in Japanese patients with non-Hodgkin's B-cell lymphomas. Of 52 patients with follicular lymphoma (FL), 24 had rearrangements. In a group of 50 patients with diffuse lymphoma, three of 32 patients with diffuse large cell lymphoma had rearrangements. The frequency of rearrangements in each of these groups, as detected by both major and minor breakpoint cluster region probes, was compatible with that found in other Far Eastern studies. However, the difference in frequency between the groups studied in the Far East and the West was significant, and these two geographically distinct populations also displayed a difference in the breakpoint distribution. In the immunophenotype study of 33 patients with FL, the expression of CD10 antigen correlated with bcl-2 involvement, whereas none of the other B markers emerged as parameters to distinguish between the two lymphoma groups; those with, and without, the rearrangements.

Humans↗

PubMed1992

[Assessment of left ventricular function with ESS-ESVI relationship in patients undergoing aortic valve replacement for aortic regurgitation].

Aortic valve replacement (AVR) for aortic regurgitation (AR) results in the reduction of left ventricular dimensions. But postoperative death or congestive heart failure may occur in patients with left ventricular dysfunction. Pre- and postoperative stress (ESS)-volume (ESVI) relationship by M-mode echocardiography was examined in 30 patients undergoing AVR. Postoperatively, 23 patients (Group A) achieved a normal left ventricular dimension (LVDd less than 55 mm, LVDs less than 45 mm) and 7 patients (Group B) had persistent left ventricular dilation (LVDd greater than or equal to 55 mm, LVDs greater than or equal to 45 mm). Correlation between preoperative ESS and ESVI was significant (r = 0.92, p less than 0.001), and the ESS/ESVI was greater in Group A of 1.62 +/- 0.29 kdy/cm2/ml/m2 than in Group B of 1.18 +/- 0.19 kdy/cm2/ml/m2 (p less than 0.001). Three patients with ESVI greater than 180 ml/m2 and ESS/ESVI less than 1.2 kdyn/cm2/ml/m2 died after operation. Echocardiographic variables correlated with ESS/ESVI were ESVI (r = -0.57), FS (r = -0.53) and CSA (r = -0.47). The changes in LVDs (delta Ds) after AVR correlated with ESS/ESVI in 12 patients with severe left ventricular dilatation. Postoperative left ventricular function could be predicted by ESS-ESVI relationship by preoperative DBcAMP infusion test. ESS/ESVI is sensitive to changes in the left ventricular contractility. The patients with ESVI greater than 180 ml/m2 and ESS/ESVI less than 1.2 kdyn/cm2/ml/m2 may result in poor prognostic outcome.

Adolescent↗