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R Sekiguchi

Publications and source records attributed to R Sekiguchi.

31 records · Page 2Linked to original sources
PubMed1991

Analysis of the influence of vasopressin neuropeptides on social recognition of rats.

The facilitatory effect of vasopressin neuropeptides on social recognition of adult male rats was analyzed. The decrease of social investigation behaviors during a second encounter with the same juvenile rat served as index for social recognition. Treatment with desglycinamide-(Arg8)-vasopressin (6 mg.kg-1, s.c.) extended the time that adults recognize the same juvenile from 30 min to 24 h. Structure-activity studies revealed that the effect of vasopressin neuropeptides on social recognition resides in the 5-8 part of the AVP molecule. The peptide (pGlu4,Cyt6) AVP-(4-8) was more potent than DGAVP in this behavioral paradigm. These effects bear similarities with the memory enhancing effects of vasopressin neuropeptides as found in other test procedures.

Animals↗
PubMed1990

Kinetic and molecular orbital studies on the rate of oxidation of monosubstituted phenols and anilines by horseradish peroxidase compound II.

The second-order rate constant (k4) for the oxidation of a series of aromatic donor molecules (monosubstituted phenols and anilines) by horseradish peroxidase (HRP) compound II was examined with a stopped-flow apparatus. The electronic states of these substrates were calculated by an ab initio molecular orbital method. It was found that in both phenols and anilines log k4 values correlate well with the highest occupied molecular orbital (HOMO) energy level and the lowest unoccupied molecular orbital (LUMO) energy level, but not with the net charge or frontier electron density on atoms of these molecules. The HOMO and LUMO energy levels of phenols and anilines further showed linear relationships with Hammett's sigma values with negative slopes. Similar results were obtained in the oxidation of substrates by HRP compound I, except that the rate of reaction was much higher than in the case of HRP compound II. In addition, the rates of oxidation of phenols by compound I or II were found to be about 1000 times higher than those of anilines with similar HOMO energy levels. On the basis of these results, the mechanism of electron transfer from the substrate to the heme iron of HRP compound II is discussed.

Aniline Compounds↗
PubMed1990

New plastic-coated coaxial catheter system for superselective hepatic catheterization: technical note.

With the use of a new improved coaxial catheter system, superselective hepatic catheterization has become easier. The improvements consist of a decrease in the outer and an increase in the inner diameters of the coaxial catheters from 0.98 to 0.96 mm and from 0.55 to 0.65 mm, respectively, and thickening of core guidewire material from 0.014 inch (0.35 mm) to 0.018 inch (0.40 mm). With this new catheter system, it is possible to inject contrast medium (iopamidol 300) at a higher rate (3 ml/sec) and gelatin sponge particles instead of gelatin powder for arterial embolization. The success rates for superselective catheterization using conventional (n = 10 procedures) and the improved coaxial catheter systems (n = 7) were 30% and 86%, respectively.

Catheterization↗
PubMed1990

Aberrant right gastric vein directly communicating with left portal vein system. Incidence and implications.

In 3 patients with primary hepatic malignancies, a communication between the right gastric vein and the left portal vein system was recognized at angiography. The right gastric vein entered directly into the left lateral portal veins in 2 patients and into the left medial portal veins in one. Portal angio-CT performed in one patient demonstrated a specific defect only in the left lateral superior area of the liver, consistent with the segmental opacification of the portal vein branch recognized on the angiogram. This rare communication was seen in 3 (1.5%) of 200 consecutive patients who underwent celiac angiography and is most likely an anomaly in which the right gastric vein directly enters the left portal vein instead of the portal vein trunk. When interpreting a filling defect not associated with a mass lesion on portal angio-CT for hepatic neoplasms or the right gastric vein communicating with the left portal vein system on the angiogram, this particular anomaly should be considered.

Adult↗
PubMed1988

The use of dansyl lysine to assess heat damage and thermotolerance of normal tissues.

The fraction of cells excluding the fluorescent dye dansyl lysine has previously been shown to correlate well with heat-induced cell killing in a variety of mammalian cell lines and in murine tumors in vivo. Here we evaluate the usefulness of dansyl lysine as a probe for assessment of thermal damage and for measuring the kinetics of thermotolerance development and decay in murine normal tissues. Skin cells were heated in vivo with an initial treatment of 44 degrees C for 20 min by local radiofrequency. Bone marrow cells were heated at 42.5 degrees C for 20 min by whole body water bath immersion. Cell suspensions were prepared, heated in vitro for various lengths of time at 44 degrees C (skin) or 43 degrees C (bone marrow), and scored for the fraction of dansyl lysine-excluding cells. Skin and bone marrow cells expressed maximum thermotolerance by 8 and 6 hr, respectively and returned to normal heat sensitivity by 48 and 146 hr, respectively. The assay was not useful with skeletal muscle and liver, as we were not successful in obtaining viable, dansyl lysine-excluding cells from these tissues. Also, in our hands red blood cells, normal human leukocytes, mouse spleen and thymus cells all failed to stain dansyl lysine even after extreme heating. Dansyl lysine staining, particularly when combined with flow cytometry analysis, has been shown to be a useful method for assessing thermal damage and thermotolerance relatively rapidly in all tumor systems tested to date, and, as shown here, may possess utility in measuring similar endpoints for certain nonclonogenic normal tissues.

Adaptation, Physiological↗
PubMed1988

A new antifungal antibiotic, cystargin: fermentation, isolation, and characterization.

A new sulfur-containing peptide antifungal antibiotic, cystargin, was isolated from the fermentation broth of a new species of genus Kitasatosporia, designated as Kitasatosporia cystarginea. On acid hydrolysis, cystargin (C60H77N19O17S6) gave equimolar glycine, proline, aspartic acid and arginine. By performic acid oxidation, cysteic acid was detected after hydrolysis. It showed a growth inhibitory activity against various phytopathogenic fungi and inhibition of beta-1,3-glucan synthetase from Saccharomyces cerevisiae.

Actinomycetales↗
PubMed1986

A comparative study on characterization and distribution of cholecystokinin binding sites among the rat, mouse and guinea pig brain.

Using the in vitro quantitative receptor autoradiographical technique, [propionyl-3H]propionylated cholecystokinin octapeptide ([3H]pCCK-8) binding sites were investigated in tissue sections of rat, mouse and guinea pig brains. In all the tested animals, [3H]pCCK-8 bound very slowly to the tissue sections. Dissociation was also slow, and had a biphasic profile suggesting CCK-8 binding sites are heterogeneous. Dissociation rate constants were, however, unequal among these species. In the saturation binding studies, both Bmax and (Kd)app values varied among the animal species. The autoradiograms revealed marked species differences in [3H]pCCK-8 binding sites in the brain among 3 closely related species of rodents. [3H]pCCK-8 binding sites were undetectable in the nucleus accumbens/caudate-putamen and the amygdaloid complex of the mouse brain, and scarcely found in the ventromedialis of the hypothalamus of the mouse and guinea pig brain. Furthermore, moderate-to-high densities of [3H]pCCK-8 binding sites were observed in the cerebella of the mouse and guinea pig, whereas in the rat cerebellum the binding sites were undetected. The above-mentioned observations suggest the existence of species differences in the binding pattern of CCK-like peptides among closely related animal species. Furthermore, it would appear that CCK-like peptides in the brain may play different physiological roles among animal species.

Animals↗
PubMed1986

Neurochemical and behavioral studies on the mode of action of oxypertine.

The mode of action of 1-[2-(5,6-dimethoxy-2-methyl-3-indole) ethyl]-4-phenylpiperidine (oxypertine) was re-examined neurochemically and behaviorally. The results obtained in the present study differed from those reported to date in the following respects. Oxypertine caused an obvious dose-related depletion in the levels of norepinephrine (NE), dopamine (DA) and 5-hydroxytryptamine (5-HT) in various discrete regions of the rat brain. The depletion in NE and DA levels were more remarkable than that in 5-HT levels. A uniform, but not statistically significant decrease in the NE level occurred throughout the rat brain at a dose level of 10 mg/kg i.p. However, the same dose of oxypertine caused significant reduction of the DA levels in the cortex and striatum. The level of homovanillic acid in three discrete regions, i.e., the cortex, striatum and mid-brain, increased in a dose-dependent manner following oxypertine administration. However, there was no difference in the level of 3,4-dihydroxyphenylacetic acid (DOPAC) at the two different dosages examined, i.e., 10 and 35 mg/kg i.p., although DOPAC levels increased significantly. Pretreatment with oxypertine at relatively smaller dosages than mentioned above inhibited apomorphine-induced stereotypy in a dose-dependent manner. Thus, it seems reasonable to conclude that at dose levels within the therapeutic range oxypertine affects mainly the dopaminergic mechanism, but it also affects the noradrenergic mechanism and thereby achieves its favorable antipsychotic action on schizophrenia.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1985

Liquid-chromatographic assay of diazepam and its major metabolites in serum, and application to pharmacokinetic study of high doses of diazepam in schizophrenics.

In this rapid, sensitive method for simultaneously determining diazepam and its biologically active metabolites--nordiazepam, oxazepam, and temazepam--in serum, 250 to 1000 microL of serum is extracted with ether and the extracted compounds are quantified by "high-performance" liquid chromatography on a Shimpack FLC-C8 microparticulate column. Absorbance of the effluent is monitored at 254 nm. The limit of detection in serum is about 10 micrograms/L for each drug. Analytical recovery of each drug added to the serum varied from 91 to 102% for oxazepam and temazepam, from 82 to 99% for nordiazepam and diazepam. Within-day and between-day CVs ranged from 2 to 5% for oxazepam and temazepam, and from 2 to 7% for nordiazepam and diazepam. We also report results on using this assay in a pharmacokinetic study of high doses of diazepam used to treat chronic schizophrenic patients.

Administration, Oral↗
PubMedDate not supplied

Intraoperative and conformal external-beam radiation therapy in patients with locally advanced pancreatic carcinoma; results from a feasibility phase II study.

BACKGROUND/AIMS: Chemoradiation therapy is widely indicated to patients with locally advanced pancreatic carcinoma, though the capability of radiotherapy alone is not assessed enough. The purpose of this study is to clarify the efficacy and safety of a more intensive radiotherapy for those patients. METHODOLOGY: Fifteen patients were enrolled in a feasible phase II study of treatment with intraoperative radiation therapy (25 Gy), followed by conformal external-beam radiation therapy (40 Gy in 20 fractions, 5 times/week). The antitumor effect was evaluated on the early phase of dynamic computed tomography image. RESULTS: The full irradiation dose was feasible in 12 of 15 patients. The overall response rate was 40% (1 complete and 5 partial responses). Grade 3 toxicity was observed in 2 patients (13%) with nausea/vomiting or anorexia. One patient developed gastric ulcer and died of gastrointestinal bleeding 12 months after intraoperative radiation therapy. The median survival time was 11.1 months, and the 2-year survival rates were 13%. Survival for more than 2 years was observed in 2 of the 6 responders. CONCLUSIONS: The above radiotherapy is considered to be active for the locally advanced pancreatic cancer with acceptable toxicity, when the gastrointestinal tract is excluded from the radiation field. This should be further assessed in late phase II studies involving a large number of patients.

Adenocarcinoma↗