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Biomedical subjects

T Takeuchi

Publications and source records attributed to T Takeuchi.

At least 1,315 records · Page 73Linked to original sources
PubMed1989

Herbimycin A suppresses the reduction of gap-junctional intercellular communication induced by tumor-promoting phorbol ester in 3T3-L1 cells.

We have examined the suppressive effect of herbimycin A on the reduction of gap-junctional intercellular communication that is induced by a tumor-promoting phorbol ester in 3T3-L1 cells. Most cells in growth arrest participated in dye-coupling, as evaluated by the transfer between cells of a fluorescent dye (Lucifer Yellow CH). Treatment of cells with 0.25 microgram/ml herbimycin A slightly enhanced the dye-coupling. This enhancement required treatment for periods as long as 24 h. Addition of 100 ng/ml 12-O-tetradecanoylphorbol-13-acetate (TPA) caused a rapid reduction of dye-coupling. However, addition of TPA did not suppress dye-coupling in cells pretreated for more than 24 h with herbimycin A. Pretreatment of cells for less than 6 h with herbimycin A did not suppress the TPA-induced reduction of dye-coupling. These results suggest that herbimycin A suppresses the reduction of gap-junctional intercellular communication that is induced by TPA through enhancement of the ability of the cells to participate in gap-junctional intercellular communication.

Animals↗
PubMed1989

Modification of cellular membrane functions by pendolmycin.

Pendolmycin is a new indole alkaloid isolated from Nocardiopsis as an inhibitor of phosphatidylinositol turnover. Structurally, pendolmycin is similar to teleocidin B and lyngbyatoxin A. Pendolmycin, teleocidin B and 12-O-tetradecanoylphorbol-13-acetate all inhibited phosphatidylinositol turnover in A431 cells. Pendolmycin inhibited binding of epidermal growth factor, activated arachidonic acid release and hexose transport, and inhibited binding of phorbol-12,13-dibutylate in C3H10T1/2 cells. Thus, pendolmycin was as potent as teleocidin B and phorbol ester tumor promoters in modification of cell membrane functions, while having the simplest structure among them.

Alkaloids↗
PubMed1989

Nucleolar organizer regions in hepatocarcinogenesis induced by N-2-fluorenylacetamide in rats: comparison with bromodeoxyuridine immunohistochemistry.

The number of silver-stained nucleolar proteins (AgNOR) was counted in preneoplastic and neoplastic rat liver lesions induced by N-2-fluorenylacetamide (FAA) and was compared with that of bromodeoxyuridine (BrdU)-incorporating cells detected immunohistochemically using monoclonal antibody against BrdU. Male ACI/N rats were given diet containing 200 ppm FAA for 12, 16 or 20 weeks to induce hepatocellular foci and tumors. The mean numbers of AgNOR stained by a one-step silver colloid method and BrdU-labeling indices in various liver cell lesions were as follows: nontreated liver (n = 20), 1.20 and 0.08; nonlesional areas (n = 20), 1.33 and 0.13; altered liver cell foci (n = 80), 2.04 and 4.05 [eosinophilic cell type (n = 20), 1.78 and 1.82; clear cell type (n = 20), 1.45 and 1.77; basophilic cell type (n = 20), 1.99 and 4.58; hyperbasophilic cell type (n = 20), 2.94 and 8.02]; neoplastic nodules (n = 10), 3.11 and 2.99; hepatocellular carcinomas (n = 10), 7.22 and 8.29. Thus, the mean number of AgNOR and the value of BrdU-labeling index were well correlated and both values showed a stepwise increase from normal liver cells to liver cell carcinoma, although some scatter was present. These data suggest that mean number of AgNOR may reflect the cellular kinetics in rat hepatocarcinogenesis, and the one-step silver colloid method for demonstration of AgNOR may therefore be a simple and useful staining to examine the proliferative nature of cells.

2-Acetylaminofluorene↗
PubMed1989

Opioid receptor modulation of neural transmission in the rabbit coeliac ganglion and ganglionic opioid receptor activation by bunitrolol.

1. We examined the preganglionic splanchnic nerve activity and postganglionic renal nerve activity before and after a local injection of naloxone (20 micrograms/kg) into the coeliac ganglion of anaesthetized rabbits. This was done during graded hypertension, induced by the administration of phenylephrine (0.5-10 micrograms/kg, i.v.) and with selective intraganglionic injection of methionine-enkephalin (ME) and bunitrolol, which is a beta-blocker. 2. During hypertension both pre- and postganglionic discharge decreased, but only postganglionic discharge was inhibited by naloxone treatment into the ganglion. 3. Local injection of ME (0.1-10 micrograms/kg) into the coeliac ganglion decreased postganglionic activity by 9.0 +/- 1.0 to 41.2 +/- 4.7% from control, and this decrease was inhibited by naloxone. 4. Administration of bunitrolol (1-300 micrograms/kg) decreased postganglionic discharge by 3.9 +/- 1.4 to 39.7 +/- 2.4% of the control and this decrease was also inhibited by naloxone. 5. These results suggest that opioid receptors in the coeliac ganglion play an inhibitory role in neural ganglionic transmission and that this inhibitory action reduces postganglionic sympathetic discharge.

Adrenergic beta-Antagonists↗
PubMed1989

[The clinical effectiveness of OFLX in the treatment of chlamydial pneumonia].

We treated three patients of chlamydial pneumonia with OFLX, two patients were diagnosed as psittacosis and one as pneumonia associated with TWAR strain by serologic test. Three hundred mg of OFLX was orally administered three times per day and the duration of treatment was from seven to fourteen days, and we compared the clinical effectiveness of OFLX in three cases (mild: 1, moderate: 2) with that of MINO in eleven cases (mild: 3, moderate: 8), who were administered two hundred mg of MINO two times per day orally or intravenously. We isolated C. psittaci from three pet birds including case 2 and the in vitro activity of OFLX and MINO against three strains of C. psittaci was determined. Clinical effectiveness were observed and obtained results were as follows. 1) In OFLX group, three patients judged as "Good", and in MINO, one patient as "Excellent", ten as "Good". 2) The duration of pneumonic shadow was 9.33 +/- 3.21 in OFLX group, 10.3 +/- 3.50 in MINO group, and there was no significant difference between both groups. 3) The in vitro activity of OFLX and MINO against 3 strains was 0.78-1.56 micrograms/ml and 0.025 microgram/ml, respectively. From these results, it was concluded that OFLX was considered to be a useful antichlamydial agent in the treatment of mild or moderate cases of chlamydial pneumonia.

Adolescent↗
PubMed1989

Chorioamnionitis and serum IgM in Wilson-Mikity syndrome.

A total of 753 infants weighing less than 1800 g at birth were studied prospectively and their serum IgM concentrations measured within 72 hours of age. Placentas from 584 of these infants were examined histologically for chorioamnionitis. The results were correlated with chronic respiratory insufficiency. Altogether 101 infants developed chronic respiratory insufficiency of which 22 had bronchopulmonary dysplasia and 35 Wilson-Mikity syndrome. The remaining 44 infants were classified as 'unexplained chronic lung disease'. Mean serum IgM concentration for Wilson-Mikity syndrome was 1.02 g/l whereas it was 0.14 g/l for bronchopulmonary dysplasia and 0.32 g/l for unexplained chronic lung disease. The incidence of chorioamnionitis was significantly higher in Wilson-Mikity syndrome (30/35) compared with bronchopulmonary dysplasia (4/16) and with infants without chronic respiratory insufficiency (145/490). Wilson-Mikity syndrome was shown to be significantly correlated with the evidences of intrauterine inflammation.

Chorioamnionitis↗
PubMed1989

Effect of traditional herbal medicine, shakuyaku-kanzo-to on total and free serum testosterone levels.

The effect of the traditional herbal medicine, Shakuyaku-Kanzo-To (SK), which contains Shakuyaku (S) and Kanzo (K) in equal amounts, on serum testosterone levels was investigated in androgen-sterilized rats. They were given orally SK [0, 22.5, 45, 90 and 180 mg/kg body weight (b.w.)] and S or K (0, 11.25, 22.5, 40 and 90 mg/kg b.w.) in 2 ml of water daily for 2 weeks. Dose-dependent decreases in free serum testosterone (T) levels were found in the administration of SK. Total serum T levels in the administration of SK and S decreased in a dose-dependent manner. K decreased total serum T levels slightly in 11.5 and 22.5 mg/kg doses but showed the dose-dependent increase in much higher doses, the extent of which was much less than that of the decrease in S. Serum estradiol/T (E2/T) ratios were significantly elevated in 45 to 180 mg/kg doses of SK, 90 mg/kg dose of S and 11.25 to 90 mg/kg doses of K. Serum LH and FSH levels were not changed by SK, S and K. Oophorectomized rats were similarly given SK (0, 90 and 180 mg/kg b.w.) and S or K (the half doses of SK). There were no changes in serum T, LH and FSH levels in all given doses. Thus, one of the mechanisms for SK to lower serum T levels is the direct action on the ovary to stimulate the aromatase activity, resulting in decreasing the T secretion and this is the additive effects of S and K.

Animals↗
PubMed1989

Insulin extraction and glucose output by the perfused liver of starved rats.

Using the isolated and perfused liver of rats, we investigated the effect of starvation on hepatic glucose output and hepatic insulin extraction. The rats were starved for 72 h. The intestines of fed and starved rats were isolated and perfused, and portal venous effluent (PVE) was collected. The liver of fed and starved rats was perfused with synthetic medium or PVE containing 100 mg/dl glucose and 100 muU/ml insulin. Fractional uptake of insulin and reduction in glucose output by the perfused liver were almost the same in all groups. These results suggest that the removal and action of insulin in the liver were not altered by short-term starvation in rats.

Animals↗
PubMed1989

Plaunotol stimulates endogenous secretin release and exocrine pancreatic secretion in rats.

The effect of the new antiulcer agent plaunotol on the release of endogenous secretin and the pancreatic exocrine secretion was investigated in anesthetized rats. In 48 rats with pancreatic and biliary diversion, continuous intraduodenal infusion of plaunotol in 3 graded doses (5, 20 and 80 mg/h/rat) resulted in significant increases in both circulating plasma secretin concentration and pancreatic exocrine secretion, including volume and bicarbonate output, in a dose-dependent manner (r = 0.655, p less than 0.001; r = 0.598, p less than 0.001; r = 0.436, p less than 0.01, respectively). The pancreatic bicarbonate output was closely correlated to plasma secretin concentrations (r = 0.631, p less than 0.001). Amylase output also increased after plaunotol administration, but not in a dose-dependent manner (r = 0.092, n.s.). These findings suggest strongly that the increase in pancreatic secretion of fluid and bicarbonate output was mainly due to increased endogenous secretin release resulting from plaunotol administration.

Amylases↗
PubMed1989

Studies on prolactin and growth hormone gene expression in the pituitary gland of spontaneous dwarf rats.

The spontaneous dwarf rat (SDR) is a newly established experimental model for pituitary dwarfism with an autosomal recessive mode of inheritance. GH and PRL gene expressions were studied in the pituitary gland of this animal. Immunocytochemistry failed to detect any immunoreactive GH cells in SDR pituitary gland, whereas numerous PRL cells were encountered throughout the anterior lobe. Similarly, GH was not detectable in the pituitary cytosol from SDR of 7, 20, and 80 days of age. PRL of the same mol wt as the authentic rat PRL was found in the pituitary glands in all SDRs examined. Since these results were thought to be due to the absence of GH mRNA in the SDR's pituitary gland, we attempted to detect GH mRNA by dot hybridization. Very small amounts of GH mRNA were found in the pituitary glands of both male (2.6% of normal) and female (6.0% of normal) SDRs. Reduced levels of PRL mRNA were also found in the pituitary glands of male (50%) and female (30%) SDRs. Northern blot analyses of total RNA extracts revealed that the GH mRNA of the SDR was similar in size to the mature GH mRNA found in the pituitary glands of control rats. PRL mRNA from the SDR also migrated to the same position as normal PRL mRNA. Nuclear DNA preparations were prepared from normal and SDR livers, and the genomic organizations of the GH and PRL genes were examined using restriction mapping. The DNA fragment length patterns obtained with the cDNA probes for GH or PRL using several restriction enzyme digestions were identical. The results suggest that the GH deficiency in SDR is not due to a gross deletion or rearrangement of the GH gene. It is proposed that SDR may be an excellent experimental model for the study of isolated GH deficiency in the human.

Animals↗
PubMed1989

Cellular sialic acid level and phenotypic expression in B16 melanoma cells: comparison of spontaneous variations and bromodeoxyuridine- and theophylline-induced changes.

The relation of the total cellular content of sialic acid to phenotypic expression of B16 mouse melanoma cells was examined by using phenotype-modifying reagents and more than 10 cloned cell lines with spontaneous phenotypic variations. The sialic acid content changed in a growth phase-dependent manner with a peak in the early log phase of growth. This peak completely disappeared when cells were treated with 5-bromodeoxyuridine (BrdU), suggesting its relation to quasi-normal phenotypes of the treated cells. BrdU treatment also reduced the cellular sialic acid content itself and resulted in the suppression of the activity of tyrosinase, the key enzyme for melanogenesis, and a considerable increase in cell-to-substratum adhesiveness. Treatment with theophylline, in contrast, markedly elevated the sialic acid content, which was accompanied by dramatic increments in tyrosinase activity and pigmentation as well as a slight increase in adhesiveness. The results show a correlation of sialic acid level with tyrosinase expression but not with cell adhesion. From comparison of spontaneous phenotypic variations, the correlation of sialic acid level with tyrosinase activity was confirmed, while there was only a slight correlation with adhesiveness. It is thus suggested that sialylation/desialylation, being reflected as variations in cellular sialic acid content, is implicated in melanoma cell differentiation in terms of tyrosinase expression.

Animals↗
PubMed1989

Contribution of external Ca2+ to the modulation by prostaglandin E2 of the release of acetylcholine from the myenteric plexus of guinea pig ileum.

The effects of external concentration of Ca2+ [( Ca2+]o) on the modulation by indomethacin (IND) or prostaglandin E2 (PGE2) of the evoked release of acetylcholine (ACh) were investigated in the myenteric plexus of guinea pig ileum. An increase in the [Ca2+]o from 0.45 to 3.6 mM depressed both the spontaneous and the nicotine-induced release of ACh, while the releases of ACh induced by electrical-field stimulation (EFS) or by high K+ were augmented. IND and PGE2 did not modify the release of ACh induced by EFS and high K+, at any given [Ca2+]o tested. The nicotine-induced release of ACh was significantly inhibited by IND with no relation to [Ca2+]o, and these inhibitory effects of IND were prevented by PGE2. At 0.45 mM [Ca2+]o, the extent of the recovery by PGE2 was less potent than those at other [Ca2+]o. IND inhibited the spontaneous release of ACh at lower [Ca2+]o, and such inhibition was not observed in the presence of PGE2. Thus, the modulatory actions of PGE2 on the spontaneous and the nicotine-induced release of ACh may depend partially on [Ca2+]o.

Acetylcholine↗
PubMed1989

Melanin production in cultured albino melanocytes transfected with mouse tyrosinase cDNA.

An attempt was made in the present study to express mouse tyrosinase cDNAs fused with the authentic genomic 5' non-coding flanking sequence in cultured albino melanocytes. One of the cDNA sequences, which expressed successfully and produced melanin pigments, was analyzed with respect to deduced amino acid sequence. Sequencing of the tyrosinase genomic gene revealed the existence of several sets of a characteristic structure which consists of a chain of two successive stem structures, CCAAT-homology and TATA box at its 5' non-coding region. It seems possible that this region represents the regulatory element of the tyrosinase gene. Unusually long GA cluster at 5' upstream region was also found.

Amino Acid Sequence↗
PubMed1989

A sensitive enzyme immunoassay system of rat epidermal growth factor in biological fluids and tissue extracts.

Rat epidermal growth factor was purified from rat submandibular glands to obtain specific antiserum for the establishment of an immunoassay system. Purified rat epidermal growth factor showed a single peak on reverse phase HPLC and a single band on sodium dodecyl sulphate polyacrylamide gel electrophoresis at mol wt 5100 in the presence of 2-mercaptoethanol and at mol wt 41,000 in the absence of 2-mercaptoethanol. Antibody against rat epidermal growth factor showed cross-reactivities with mouse and human epidermal growth factors on soft agar-double immunodiffusion test. The established sandwich enzyme immunoassay for rat epidermal growth factor had a high sensitivity (500 fg/tube), which made it possible to measure minute amounts of endogenous rat epidermal growth factor without pretreatment. Physiological concentrations of rat epidermal growth factor in rat biological fluids and tissues were determined. Species differences in physiological distributions of epidermal growth factor are discussed.

Animals↗
PubMed1989

Occipital lobe ependymal cyst--case report.

A 51-year-old female with an ependymal cyst in the left occipital lobe presented with headache, vomiting, dizziness, and right incomplete homonymous hemianopsia. Following a cyst-ventricular communication and cyst-peritoneal shunting procedure, the visual field loss improved markedly. On the basis of the visual field symptoms, computed tomographic findings, and intraoperative observations, the cyst was considered to have developed in the vicinity of the body and posterior horn of the left lateral ventricle, extending to the left occipital lobe.

Brain Diseases↗
PubMed1989

Role of PAF in ischemia-reperfusion injury in the rat stomach.

Ischemia-reperfusion induced extensive gastric mucosal injury and an increase in chemiluminescence activity of neutrophils obtained from the portal vein in hemorrhagic shock rats. CV-3988, a selective antagonist of platelet activating factor (PAF), significantly reduced the gross and histologic gastric damage, and the increase in chemiluminescence activity of neutrophils. These results suggest that PAF generated on hypoxia might stimulate oxygen radical production by neutrophils, resulting in the occurrence of gastric injury in hemorrhagic shock rats.

Animals↗