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Biomedical subjects

Y Iguchi

Publications and source records attributed to Y Iguchi.

At least 91 records · Page 5Linked to original sources
PubMed1985

Participation of the nucleus reticularis gigantocellularis in the morphine-induced elevation of plasma corticosterone in rats.

The effects of morphine, adrenocorticotropic hormone (ACTH) and formalin on plasma corticosterone levels were investigated in the nucleus reticularis gigantocellularis (NRGC)-lesioned rats. ACTH (1.0 U/kg) or formalin (6.4%, 0.2 ml/rat) elevated plasma corticosterone in both sham-lesioned and NRGC-lesioned rats at the same degree, while morphine (10 mg/kg) also elevated plasma corticosterone in sham-lesioned rats, the elevation of which was significantly reduced by NRGC-lesioning. These findings suggest that the NRGC is involved in the corticosterone-increasing effect of morphine, but not involved in the effect of ACTH or formalin.

Adrenocorticotropic Hormone↗
PubMed1984

Intercellular junctions in odontoblasts of the rat incisor studied with freeze-fracture.

The morphology and distribution of various types of intercellular junctions were investigated in young odontoblasts. Gap junctions were found between odontoblasts as well as between odontoblasts and fibroblasts in the dental pulp. The junctions between odontoblasts were larger and more numerous than those between odontoblast and fibroblast, suggesting that the former may play an important role in regulating cellular activity and the latter may provide a pathway of low electrical resistance between odontoblast and nerve fibres. Irregularly-shaped gap junctions appeared as small aggregations of particles associated with a particle-free area and may indicate that the junction might not yet have been completely assembled. Tight junctions were observed at the distal ends of the young odontoblasts, arranged to form small maculae or faciae occludentes rather than belt-like zonulae. It is therefore not likely that the junction contributes to barrier function in the young odontoblasts. Although structures resembling typical desmosome were recognizable, this type of junction in odontoblasts is properly termed a desmosome-like junction from its morphological peculiarities.

Animals↗
PubMed1984

[A specific and quantitative determination of rat beta-endorphin. Combination of HPLC and RIA].

A specific and quantitative method for the determination of rat beta-endorphin by the combination of HPLC and RIA was developed. Rabbit antiserum against camel beta-endorphin (c beta-E) was raised and used for RIA at the final concentration of 1:10000. The quantitative range estimated from the displacement curve was 0.1-2.0 ng. Cross-reactivities with Met-Enk, Leu-Enk, alpha-MSH, alpha-endorphin, ACTH and human beta-E were less than 0.1, less than 0.1, less than 0.1, less than 0.1, 2 and 100%, respectively. These peptides were separated from each other by reversed phase HPLC with UV254 nm detection, and the minimum detectable dose of c beta-E was found to be 1 microgram. beta-E-like immunoreactivity (beta-ELIR) in the HPLC effluent was determined by RIA. The HPLC-RIA chromatogram of authentic c beta-E exhibited a single peak which coincided with the peak of c beta-E detected by UV, and 80% of the injected c beta-E (1-100 ng) was detected in the c beta-E fraction. The HPLC-RIA chromatogram of rat pituitary, hypothalamus, cerebrospinal fluid and plasma revealed the presence of 1-3 peaks, one of which was observed at the position of c beta-E. The HPLC elution of rat pituitary resolved the material into two peaks of biological activity, one of which coincided with the peak of beta-ELIR at the position of c beta-E. The HPLC-RIA chromatogram of the c beta-E fraction from pituitary obtained by gel-chromatography exhibited three peaks, one of which coincided with c beta-E. These results suggest that beta-ELIR in the c beta-E fraction of the HPLC elution may reflect rat beta-E accurately.

Animals↗
PubMed1984

[Morphine tolerance and dependence liability in NRGC-destructed rats].

The nucleus reticularis gigantocellularis (NRGC), including the nucleus reticularis paragigantocellularis (NRPG), of male Sprague Dawley rats was destructed bilaterally by DC 0.5 mA for 40 sec (D-rats). Morphine analgesia estimated by the tail pinch method in 4 and 10 days morphine treated sham operated rats (S-rats), of which the test doses were 40 and 80 mg/kg, respectively, was equal to or smaller than the analgesia by 5 mg/kg in non-treated S-rats. Morphine analgesia at 5 mg/kg in non-treated D-rats was weaker than that in S-rats. Morphine analgesia in 4 and 10 days morphine treated D-rats, of which the test doses were 40 and 80 mg/kg, respectively, was stronger than the analgesia by 5 mg/kg but weaker than that by 20 mg/kg in non-treated D-rats. These results indicate development of morphine tolerance in S- and D-rats. Reverse of diurnal variation in body weight and disappearance of diurnal variation in body temperature and in plasma corticosterone concentration (Pcs) were observed similarly in S- and D-rats during morphine treatment. Body weight loss, increase in Pcs and plasma ACTH concentration, and increase in adrenal weight were elicited by morphine withdrawal in both morphine treated S- and D-rats. These signs during morphine treatment and after morphine abstinence indicate the development of morphine dependence in D-rats. These results suggest that the NRGC participates in development of morphine analgesia, but does not participate in development of morphine tolerance and dependence.

Adrenal Glands↗
PubMed1983

[Effect of destruction of nucleus reticularis gigantocellularis of rat medulla oblongata on morphine analgesia].

It was confirmed that the nucleus reticularis gigantocellularis (NRGC), including the nucleus reticularis paragigantocellularis (NRPG), was a highly sensitive site in the production of morphine analgesia by the micro-injection technique (ED50 = 8.5 ng/rat). The NRGC of SD male rats (280-350 g) was bilaterally lesioned by direct current (0.5 mA for 40 sec). The body weight was decreased by NRGC destruction, while no abnormality in motor activity was observed in NRGC-destructed rats. The size of lesion was decreased in relation to the days after operation. The size of the destructed area immediately after operation was about 30% of the NRGC area. Morphine analgesia was estimated by tail pinch and hind paw pressure tests. No change in control pain threshold was produced by NRGC lesioning. Morphine analgesia due to 5, 10 and 15 mg/kg s.c. were depressed almost equally be NRGC lesioning, and depression % was 60-70%. Time course of the morphine effect in NRGC-destructed rats was similar to that in sham operated rats. The degree of depression of morphine analgesia by NRGC lesioning was dependent on the extent of NRGC lesioning, i.e., the more the destructed area of NRGC was extended, the more the morphine analgesia was depressed. Reduction of morphine analgesia in rats in which the position of destruction had deviated from the NRGC was smaller than that in rats in which the destruction was exactly at the NRGC. These results suggest that the NRGC, including the NRPG, plays an important role in morphine analgesia.

Analgesia↗
PubMed1981

Highly selective inhibitors of thromboxane synthetase. 1. Imidazole derivatives.

The structure--activity relationships of imidazole derivatives as inhibitors of thromboxane (TX) synthetase were investigated. Introduction of various substituents (e.g., one or two methyl groups, a halogen atom, a methylidene group, unsaturated bonds, or a phenylene group) into the alpha position or other positions in the carboxy-bearing side chain of 1-(7-carboxyheptyl)imidazole (15) was found to increase the inhibitory potency. The length of the side chains with the phenylene group was optimum for the inhibitory potency on TX synthetase in the region of 8.5-9.0 A. Among the tested imidazole derivatives, 1-(7-carboxy-7-methyl-2-octynyl)imidazole (47), 4-[3-(1-imidazolyl)-propyl]benzoic acid (50), and (E)-4-(1-imidazolylmethyl)cinnamic acid (54) and its alpha-methyl analogue (57) showed the highest potency with an IC50 in the range of 10(-8) to 10(-9) M. Inhibition by these derivatives was highly selective for the TX synthetase, since other enzymes such as fatty acid cyclo-oxygenase and prostacyclin synthetase were not affected.

Animals↗
PubMed1981

Highly selective inhibitors of thromboxane synthetase. 2. Pyridine derivatives.

The enzyme thromboxane (TX) synthetase is inhibited by pyridine. The beta-substituted pyridine derivatives showed higher inhibitory potency than the gamma-substituted ones having the same side chain. Among the beta-substituted derivatives containing the omega-carboxyalkyl group, the compounds with 6-8 carbon atoms in the side chain were especially effective. The derivatives holding the phenylene group in the side chain exhibited much higher inhibitory activity than those of the alkylene type. Among them, (E)-3-[4-(3-pyridylmethyl)phenyl]-2-methylacrylic acid hydrochloride (5a) had the highest potency (IC50 = 3 x 10(-9) M). The beta-substituted pyridine derivatives and 1-substituted imidazole derivatives which had the same side chain showed almost the same potency. The beta-substituted pyridine derivatives do not inhibit arachidonic acid cyclooxygenase or prostaglandin I2 synthetase, two other enzymes of the arachidonic cascade.

Animals↗
PubMed1980

Change of polyamine content in mouse skin by leupeptin, a protease inhibitor, during early stage of tumorigenesis.

The effect of a microbial protease inhibitor, leupeptin, on the content of polyamine in the mouse skin was examined during the early stage of tumorigenesis induced by a single application of 7,12-dimethylbenz[a]anthracene (DMBA) and repeated application of croton oil thereafter. Polyamine content in the skin was measured at 3, 5, 7, and 9 weeks during tumorigenesis. The mice with no visible tumor were selected for measurement of polyamine content at 9 weeks. Mice were left untreated for at least 1 week before measurement of polyamine. Polyamine in the skin was extracted with ice-cold 0.4N HClO4 and separated into putrescine, spermidine, and spermine fractions through CM-cellulose column. Polyamine concentration was determined by fluorometry with fluorescamine. Group A mice painted with croton oil 3 times a week did not develop tumors. Group B mice painted with a single DMBA developed skin tumors, and group C mice painted with a single DMBA and croton oil 3 times a week showed higher development of skin tumors than group B. Group D mice treated as group C and then painted with leupeptin about 2 hr after croton oil treatment. Animals in groups B, C, and D had higher spermidine content as group A at 3 and 5 weeks. Content of spermidine in group B decreased at 7 and 9 weeks compared with group C which had a high content throughout the time tested. Leupeptin treatment in group D inhibited spermidine content in the skin after 7 weeks without affecting until 5 weeks.

Animals↗
PubMedDate not supplied

Prevalence of urinary tract infection during outpatient follow-up after renal transplantation.

Seven hundred and twenty-seven renal transplant patients are reviewed with respect to the occurrence of urinary tract infection (UTI) after renal transplantation. UTI was defined as the detection of both bacteriuria (10(5) CFU/ml) and pyuria (10 leukocytes/hpf). UTI developed in 11 of the inpatients (20.8%) and in 30 (4.2%) of the outpatients during a one-year period. Among outpatients, 12 had symptomatic infections, comprising seven with acute pyelonephritis and five with acute cystitis. Asymptomatic UTI was detected in 18 patients. In addition, asymptomatic bacteriuria without pyuria was observed in ten (1.4%) patients. UTI was more common in patients with diabetes, and underlying urinary tract complications were present in some patients. Administration of trimethoprim-sulfamethoxazole for about 4 months is suggested to reduce the frequency of UTI in the early period after renal transplantation.

Anti-Bacterial Agents↗