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Biomedical subjects

S Tanabe

Publications and source records attributed to S Tanabe.

At least 127 records · Page 7Linked to original sources
PubMed1999

Effects of prolyl endopeptidase inhibitors and neuropeptides on delayed neuronal death in rats.

We investigated the effects of the prolyl endopeptidase inhibitors 1-[1-(Benzyloxycarbonyl)-L-prolyl]prolinal (Z-Pro-Prolinal) and N-benzyloxycarbonyl-thioprolyl-thioprolinal-dimethylaceta l (ZTTA) on delayed neuronal death induced by four-vessel-occlusion transient ischemia in rats. We also examined the effects of [pGlu4, Cyt6, ArgS]vasopressin (vasopressin-(4-9)) and thyrotropin-releasing hormone (TRH) on the delayed neuronal death. Furthermore, we investigated the role of vasopressin receptors in the effects of vasopressin and prolyl endopeptidase inhibitors. Z-Pro-Prolinal, vasopressin-(4-9) and TRH protected pyramidal cells in the CA1 subfield of the rat hippocampus from delayed neuronal death after 10-min ischemia. The effect of vasopressin-(4-9) was abolished by vasopressin receptor antagonists. The effect of Z-Pro-Prolinal was also abrogated by the antagonists. These results suggest that the neuroprotective effect of prolyl endopeptidase inhibitors is mediated by neuropeptides such as [Arg8]vasopressin and TRH, and indicate the involvement of vasopressin receptors in the neuroprotective effect of vasopressin-(4-9) and prolyl endopeptidase inhibitors.

Animals↗
PubMed1999

Synthesis and biological activity of KCB-328 and its analogues: novel class III antiarrhythmic agents with little reverse frequency dependence.

A series of 3,4-dimethoxyphenethylamine derivatives was prepared, and their prolongation effects on effective refractory period of contractile response (ERPc) and action potential duration (APD) in isolated guinea-pig papillary muscles at 1 Hz and 3 Hz were examined. SAR studies led to the identification of KCB-328 (51) which is a novel class III antiarrhythmic agent with little reverse frequency dependence.

Animals↗
PubMed1999

Distribution and specific bioaccumulation of butyltin compounds in a marine ecosystem

Butyltin compounds (BTs), including tributyltin (TBT) and its breakdown products, di- (DBT) and monobutyltin (MBT), were determined in sea water, sediment, and biota at various trophic levels in the food chain collected from Otsuchi Bay, Japan, for understanding distribution and bioaccumulation of BTs in natural marine ecosystems. BT residues were detected in all the compartments analyzed, although their concentrations appeared to be less than those in polluted areas. Concentrations of BTs in sea water were higher in locations near Otsuchi Port, indicating that maritime activities in the harbor has been a major source of BTs in this bay. A specific peak in BT residue levels was found in sediment cores at an estimated depth that dated to be from the 1980s. Lack of significant variation in the composition of BTs at different depths of cores suggests slow degradation rate of these compounds in sediments. BTs were accumulated in plankton and other organisms up to approximately 70,000 times higher than in sea water. However, no considerable biomagnification was observed for BTs through the food chain. Relatively high concentrations were found in caprellids and smaller fish, such as gunnels. These organisms accumulated TBT as the predominant compound among BT derivatives and showed higher bioconcentration factors for TBT than in other species reported so far. Our results suggest that certain organisms in the food chain may have a less capacity to degrade TBT, and therefore may accumulate BTs at elevated levels.http://link.springer-ny. com/link/service/journals/00244/bibs/37n1p50.html

Journal Article↗
PubMed1999

Contamination levels and specific accumulation of persistent organochlorines in Caspian seal (Phoca caspica) from the Caspian sea, Russia.

Persistent organochlorines, such as polychlorinated biphenyls (PCBs) including coplanar congeners, DDTs, HCHs, chlordanes (CHLs), and HCB, were determined in the blubber of Caspian seals (Phoca caspica) and their fish diet (Rutilus sp.) collected in 1993 from the northern Caspian Sea, Russia. Notable concentrations of DDTs and HCHs were found at mean values of 19 and 1.3 microg/g on wet-weight basis in adult male seals, respectively. PCB pollution in Caspian seals was not so considerable compared with those of seals that suffered mass mortality. Less gender difference of organochlorine residue levels in adult animals implies less excretion of organochlorines from the body of adult females through lactation and gestation, probably due to the higher rate of pregnancy failure. Immature seals had a wide range of organochlorine concentrations, which decreased as body length increased, suggesting dilution. Caspian seals can be considered to have higher degradation capacity for coplanar PCBs. Mean TEQs (2,3,7,8-TCDD toxic equivalents) for non-, mono- and di-ortho coplanar PCBs was 51 pg/g on wet-weight basis, which was lower than those in seals that have suffered mass mortality, but comparable to those found in Arctic seals.

Age Factors↗
PubMed1999

Neonatal hyperbilirubinemia and a common mutation of the bilirubin uridine diphosphate-glucuronosyltransferase gene in Japanese.

Neonatal hyperbilirubinemia, which is prevalent among Asian peoples, has been considered as a physiological phenomenon, and its metabolic basis has not been clearly explained. Gilbert syndrome is a common inherited disease of unconjugated hyperbilirubinemia due to decreased bilirubin uridine diphosphate-glucuronosyltransferase (B-UGT), and its role in neonatal jaundice has recently been considered. We have previously reported that the Gly71Arg mutation of the B-UGT gene associated with Gilbert syndrome is prevalent in Japanese, Korean, and Chinese populations and was more frequently detected in neonates with severe hyperbilirubinemia than in control subjects. We have studied 159 Japanese full-term neonates, evaluating the relationship between the B-UGT genotype and the severity of jaundice, as assessed with a transcutaneous bilirubinometer. The gene frequency of the Gly71Arg mutation in these neonates was 0.19, and neonates carrying the Gly71Arg mutation had significantly increased bilirubin levels on days 2-4, manifested in a gene dose-dependent manner. The frequency of the Gly71Arg mutation was 0.47 in the neonates who required phototherapy (i.e., those with more severe hyperbilirubinemia), significantly higher than 0.16 in the neonates who did not require the therapy. The gene frequency of the TA repeat promoter polymorphism, the (TA)7 mutation, was 0.07, and neonates carrying this mutation did not have an increase in bilirubin. These results suggested that the Gly71Arg mutation contributes to the high incidence of neonatal hyperbilirubinemia in Japanese.

Base Sequence↗
PubMed1999

Usefulness of endoscopic aspiration mucosectomy as compared with strip biopsy for the treatment of gastric mucosal cancer.

BACKGROUND: Several techniques are available for the endoscopic treatment of gastric intramucosal cancers, but their advantages and disadvantages have not been adequately evaluated. We compared the therapeutic usefulness of endoscopic aspiration mucosectomy with that of strip biopsy. METHODS: Between May 1995 and May 1997, we performed strip biopsy (May 1995 through February 1996) or endoscopic aspiration mucosectomy (March 1996 through May 1997) in a consecutive series of patients with intestinal-type intramucosal cancer. Parameters of assessment included the following: size of removed specimens, en bloc resection rate, time required for resection, duration of hospitalization, and complications. RESULTS: Forty-nine patients with gastric intramucosal cancers underwent endoscopic aspiration mucosectomy and 44 underwent strip biopsy. The two groups were similar with respect to age, gender, and lesion macroscopic appearance, size, and site. The mean longest diameter of the resected specimens was significantly greater with endoscopic aspiration mucosectomy (20.3 +/- 3.4 mm) than with strip biopsy (15. 8 +/- 4.4 mm) (p < 0.001). The rate of en bloc resection (resection of an entire lesion in one procedure) was significantly higher with endoscopic aspiration mucosectomy (61.2%, 30 of 49) than with strip biopsy (36.4%, 16 of 44) (p < 0.05). The number of specimens obtained by piecemeal resection was slightly, but not significantly, higher with strip biopsy (2.4 +/- 1.7) than with endoscopic aspiration mucosectomy (2.0 +/- 1.7). The time required for treatment was similar for each procedure. The duration of hospitalization was significantly shorter with endoscopic aspiration mucosectomy (12.8 +/- 5.3 days) than with strip biopsy (15.9 +/- 74 days) (p < 0.05). As for complications, the rate of bleeding was 20. 5% (9 of 44) with strip biopsy and 10.2% (5 of 49) with endoscopic aspiration mucosectomy; bleeding was controlled in all cases by treatment with a heater probe. CONCLUSIONS: Endoscopic resection of large gastric intramucosal tumors is easier with endoscopic aspiration mucosectomy compared with strip biopsy. Endoscopic aspiration mucosectomy is a useful procedure for en bloc resection.

Adenocarcinoma↗
PubMed1999

Effects of arginine-vasopressin fragment 4-9 on rodent cholinergic systems.

Arginine-vasopressin fragment 4-9 (AVP4-9) has been demonstrated in animal studies to facilitate learning and memory. To clarify the mechanisms of this facilitation, we focused on the effects of AVP4-9 on rodent cholinergic systems. AVP4-9 (0.1 microM) enhanced the basal and the high-potassium-evoked acetylcholine (ACh) release from rat hippocampal slices (122.4 and 120.0% of control, respectively) in the presence of 1.3 mM calcium (physiological level) at 60 min after the incubation at 37 degrees C. The AVP4-9-stimulated basal ACh release was inhibited by a V1-selective antagonist ([(beta-mercapto-beta,beta-cyclopentamethylene propionic acid)1, O-methyl-Tyr2, Arg8] vasopressin), but not by a V2-selective antagonist ([adamantaneacetyl1, O-ethyl-D-Tyr2, Val4, aminobutyryl6, Arg8,9]-vasopressin). In addition, AVP4-9 did not affect the basal ACh release under the calcium-free condition at 37 degrees C or in the presence of 1.3 mM calcium at 4 degrees C. However, AVP4-9 facilitated the passive-avoidance response of scopolamine (a cholinergic blocker)-induced memory-deficient mice. These findings demonstrate that AVP4-9 stimulates ACh release via mediation by V1-like vasopressin receptors, and shows dependence on calcium ion and temperature. The results also suggest that the mechanism of the facilitative effects of AVP4-9 on learning and memory consist of the observed stimulation of cholinergic systems and other parallel pathways that would not be inhibited by cholinergic blocking.

Acetylcholine↗
PubMed1999

Butyltin residues in livers of humans and wild terrestrial mammals and in plastic products.

Butyltin compounds (BTs) including mono-(MBT), di-(DBT) and tributyltin (TBT) were determined in livers of humans and wild terrestrial mammals, such as raccoon dogs (Nyctereutes procyonoids) and monkeys (Macaca fuscata) from Japan. In addition, 22 samples of plastic products were analyzed. BT residues were detected in all the liver samples of humans and raccoon dogs, with concentrations of <360 ng/g wet wt, whereas concentrations in the liver of monkeys were either less than the detection limit or were only in trace levels. Elevated concentrations of BTs, particularly DBT (<140,000 ng/g) and MBT (<130,000 ng/g), were found in some plastic products, such as baking parchments made from siliconized paper and gloves made up from polyurethane. The results of a cooking test using the above baking parchment indicated the transfer of BTs to foodstuffs. These observations suggest expansion of BT contamination among terrestrial mammals. BT pollution from industrial appliances, such as plastic stabilizers and catalysts other than those of marine origin as antifouling agents, are suggested as alternative sources of exposure.

Journal Article↗
PubMed1999

Response of coupled noisy excitable systems to weak stimulation.

It is known that coupling can enhance the response of noisy bistable devices to weak periodic modulation. This work examines whether a similar phenomenon occurs in the active rotator model for excitable systems. We study the dynamics of assemblies of weakly periodically modulated active rotators. The addition of noise to these brings about a number of behaviors that have no counterpart in networks of bistable systems. The analysis of the dynamics of the solution of the Fokker-Planck equation of active rotator networks shows that these new behaviors are similar to generic responses of periodically forced autonomous oscillators. This is because noise alone, in the absence of other inputs, can regularize the dynamics of single active rotators through coherence resonance, and lead to regular synchronous activity at the level of networks. We argue that similar phenomena take place in a broad class of excitable systems.

Acoustic Stimulation↗
PubMed1999

Response of an ensemble of noisy neuron models to a single input.

Spike timing precision in response to a subthreshold stimulation can be enhanced by noise in ensembles of neurons [X. Pei, L. Wilkens, and F. Moss, Phys. Rev. Lett. 77, 4679 (1996)]. We elucidate the mechanism underlying this phenomenon by computing the membrane potential distributions of ensembles of Hodgkin-Huxley neuron models. For small noise amplitudes, the membrane potential distribution takes on a Gaussian form centered on the resting potential, while for large fluctuations, there is a significant spread to lower potentials. These two regimes are separated by a relatively narrow band where the distributions transit rapidly from the Gaussian-like shapes to the spread ones. We argue that the optimal noise that maximizes the spike timing precision is situated close to this boundary.

Action Potentials↗
PubMed1999

Effects of estrogen on action potential and membrane currents in guinea pig ventricular myocytes.

To explore a possible ionic basis for the prolonged Q-T interval in women compared with that in men, we investigated the electrophysiological effects of estrogen in isolated guinea pig ventricular myocytes. Action potentials and membrane currents were recorded using the whole cell configuration of the patch-clamp technique. Application of 17beta-estradiol (10-30 microM) significantly prolonged the action potential duration (APD) at 20% (APD(20)) and 90% repolarization (APD(90)) at stimulation rates of 0. 1-2.0 Hz. In the presence of 30 microM 17beta-estradiol, APD(20) and APD(90) at 0.1 Hz were prolonged by 46.2 +/- 17.1 and 63.4 +/- 11.7% of the control (n = 5), respectively. In the presence of 30 microM 17beta-estradiol the peak inward Ca(2+) current (I(CaL)) was decreased to 80.1 +/- 2.5% of the control (n = 4) without a shift in its voltage dependence. Application of 30 microM 17beta-estradiol decreased the rapidly activating component of the delayed outward K(+) current (I(Kr)) to 63.4 +/- 8% and the slowly activating component (I(Ks)) to 65.8 +/- 8.7% with respect to the control; the inward rectifier K(+) current was barely affected. The results suggest that 17beta-estradiol prolonged APD mainly by inhibiting the I(K) components I(Kr) and I(Ks).

Action Potentials↗
PubMed1999

Screening for aetiology of thrombophilia: a high prevalence of protein S abnormality.

We systematically screened for the aetiology of thrombophilia in 115 patients with venous, arterial and small vessel thromboses. Forty-one patients (36% of those we examined) suffering from a variety of thromboses, including deep vein thrombosis, pulmonary embolism, arterial occlusion, cerebral infarction, Moyamoya disease and ulcerative colitis, were characterized either with positive lupus anticoagulants or with decreased activities of protein S, protein C, antithrombin III and/or plasminogen. Eight mutation sites were confirmed in 11 thrombotic patients using gene analysis. Decreased protein S activity was found with a high incidence (23 out of 115) in Japanese patients who suffered from not only venous thrombosis but also arterial and small vessel thrombosis. We emphasize here the important role of protein S in the pathogenesis of thrombosis in the Japanese population.

Adolescent↗
PubMed1999

Antioxidant effects of albumin-bound sulfur in lipid peroxidation of rat liver microsomes.

The antioxidant potential of albumin-bound sulfur (SBA) was investigated in rat liver microsomes using lipid peroxidation systems in vitro. Sulfur bound to protein is a reduced metabolite which is produced from cystine by gamma-cystathionase. Lipid peroxidation was induced either chemically by ferrous ions and ascorbate or enzymatically by carbon tetrachloride or tert-butyl hydroperoxide as indicated by the increase in thiobarbituric acid reactive substances (TBA-RS) and oxygen consumption. Although the antioxidant effect of SBA was weak on the non-enzymatic lipid peroxidation system, the addition of SBA significantly inhibited TBS-RS formation and oxygen consumption compared with non-treated bovine serum alubumin (BSA) in a microsomal lipid peroxidation system induced enzymatically. The sulfur bound to albumin disappeared during incubation with liver microsomes. However, slight differences in the disappearance were observed depending on whether or not lipid peroxidation was induced in the enzymatic systems. In the CCl4-induced lipid peroxidation system, the cytochrome P-450 level was significantly decreased by the addition of SBA. Therefore, in cytochrome P-450 dependent lipid peroxidation system, the potential effects of sulfur bound to albumin are due to an inhibition of cytochrome P-450 rather than by the oxidation itself caused by radical trapping.

Albumins↗
PubMed1999

Chemical control of Haematobia irritans with 0.5% topical ivermectin solution in cattle.

A field trial was conducted to evaluate the efficacy of a topical formulation of ivermectin administered at the dose of 500 micrograms/kg against horn flies (Haematobia irritans) in cattle. Eighty-eight cattle in four herds naturally exposed to horn flies were used in the trial. Replicates were formed of two herds. Within replicates, one herd was randomly allocated to the untreated control and the other to the ivermectin treatment group. Horn fly counts were taken on the treatment day (Day 0) and on Days 7, 14, 21, 28, and 35 post-treatment. There were no horn flies on any cattle in the treatment group, whereas all the control cattle were continuously infested by horn flies on each examination day.

Administration, Topical↗
PubMed1999

[Effects of Helicobacter pylori eradication therapy on the healing process of peptic ulcers].

The advent of H2-receptor antagonists (H2RA) and proton pump inhibitors (PPI) has particularly revolutionized the treatment of peptic ulcer disease. Most cases can now be successfully controlled by medical treatment with H2RA and PPI, but a high rate of ulcer recurrence remains an important problem. The quality of ulcer healing (QOUH) has therefore received increasing attention, and various investigators have attempted to define the conditions required for nonrecurrence. Ulcer scars with a good QOUH are considered to have a very low risk of recurrence. Recent studies have confirmed that recurrence of peptic ulcer can be suppressed markedly by eradication of Helicobacter pylori (H. p). Moreover, various types of endoscopic examinations (conventional observation, dye-contrast endoscopy, magnifying endoscopy, endoscopic ultrasonography, pharmacoendoscopy) have confirmed that the QOUH after eradication of H. p is better than that after conventional anti-ulcer therapy. H. p eradication therapy may become treatment of first choice for peptic ulcers.

Anti-Bacterial Agents↗