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T Karashima

Publications and source records attributed to T Karashima.

61 records · Page 4Linked to original sources
PubMed1980

Actions of nitroglycerine on smooth muscles of the guinea-pig and rat portal veins.

1 Effects of nitroglycerine (NG) on the electrical and mechanical activities of smooth muscle cells of the rat and guinea-pig portal veins were studied by a microelectrode technique and an isometric tension recording method.2 The membrane potentials of smooth muscle cells in the rat and guinea-pig were -44.4 mV and -47.6 mV, respectively. In both species the smooth muscle cells generated spikes as burst discharges.3 In the guinea-pig portal vein, NG (2.8 x 10(-8) M) produced biphasic potential changes, an initial transient hyperpolarization followed by depolarization. The hyperpolarization suppressed and depolarization enhanced spike activities.4 From the changes in the membrane potential produced by NG in various concentrations of [K](o), [Na](o) or [Ca](o), it is postulated that the hyperpolarization is due to an increase in the K-permeability and the depolarization is due to an increase in the Na-permeability of the membrane.5 NG (2.8 x 10(-5) M) had no effect on the membrane activity of the rat portal vein.6 NG consistently suppressed mechanical activities generated in both tissues. The minimum concentration required to suppress the mechanical activity was lower in the guinea-pig than in the rat portal vein.7 NG suppressed the contraction due to noradrenaline more than that evoked by excess [K](o) in both species.8 From these experiments, it is concluded that NG relaxes the muscular bed of portal veins of both species. In the rat portal vein, suppression of mechanical activity had no causal relation to the membrane activity. In contrast, in the guinea-pig portal vein, suppression of mechanical activity was slightly modified by changes in the membrane activity, i.e. hyperpolarization additively contributes to the relaxation and depolarization slightly suppresses the relaxation.

Animals↗
PubMedDate not supplied

Superactive somatostatin analog decreases plasma glucose and glucagon levels in diabetic rats.

The action of the new analog of somatostatin, D-Phe-Cys-Tyr-D-Trp-Lys-Val-Cys-Trp-NH2 (RC-160), on plasma glucagon and glucose levels was evaluated in streptozotocin-diabetic rats. The effect of this analog on the insulin-induced hypoglycemia in diabetic rats was also investigated in order to evaluate the risk of exacerbating hypoglycemia. Administration of analog RC-160, in a dose of 25 micrograms/kg b. wt. SC, inhibited plasma glucagon secretion and decreased plasma glucose levels. This effect also occurred when plasma glucagon and glucose levels were first elevated by arginine infusion, 1000 mg/kg/hr for 30 min. Subcutaneous injection of regular insulin, 15 U/kg b. wt., produced hypoglycemia with a progressive increase in glucagon levels. Analog RC-160 completely suppressed the hypoglycemia-induced glucagon release for up to 150 min after injection of the analog or insulin. A greater decrease in the plasma glucose level was observed in the group treated with insulin and the analog than in the group injected only with insulin. These results indicate that somatostatin analog RC-160 can produce a marked and prolonged inhibition of glucagon release and a decrease in the plasma glucose level in diabetic rats. This analog may be useful as an adjunct to insulin in the treatment of diabetic patients, although caution should be exercised, to prevent hypoglycemia when using somatostatin analogs together with insulin.

Animals↗
PubMedDate not supplied

Expression of interleukin-8 correlates with angiogenesis, tumorigenicity, and metastasis of human prostate cancer cells implanted orthotopically in nude mice.

We determined whether the expression of interleukin-8 (IL-8) by human prostate cancer cells correlates with induction of angiogenesis, tumorigenicity, and production of metastasis. Low and high IL-8-producing clones were isolated from the heterogeneous PC-3 human prostate cancer cell line. The secretion of IL-8 protein correlated with transcriptional activity and levels of IL-8 mRNA. All PC-3 cells expressed both IL-8 receptors, CXCR1 and CXCR2. The low and high IL-8-producing clones were injected into the prostate of nude mice. Titration studies indicated that PC-3 cells expressing high levels of IL-8 were highly tumorigenic, producing rapidly growing, highly vascularized prostate tumors with and a 100% incidence of lymph node metastasis. Low IL-8-expressing PC-3 cells were less tumorigenic, producing slower growing and less vascularized primary tumors and a significantly lower incidence of metastasis. In situ hybridization (ISH) analysis of the tumors for expression of genes that regulate angiogenesis and metastasis showed that the expression level of IL-8, matrix metalloproteinases, vascular endothelial growth factor (VEGF), and E-cadherin corresponded with microvascular density and biological behavior of the prostate cancers in nude mice. Collectively, the data show that the expression level of IL-8 in human prostate cancer cells is associated with angiogenesis, tumorigenicity, and metastasis.

Animals↗
PubMedDate not supplied

Differential expression of progression-related genes in the evolution of superficial to invasive transitional cell carcinoma of the bladder.

It is generally accepted that there are dichotomous biologic pathways that lead to the development of either: i) superficial papillary (Ta) transitional cell carcinoma (TCC) or ii) precursor lesions to muscle-invasive (CIS, T1) TCC and muscle-invasive (> or =T2) TCC. We investigated the expression of several progression-related genes to characterize the phenotype of these tumors within these divergent developmental pathways. Using a colorimetric in situ hybridization technique, we examined the expression of mRNAs of several progression-related genes in archival, pathologic specimens from 77 patients with bladder TCC. These genes included basic fibroblast growth factor (bFGF), vascular endothelial growth factor (VEGF), interleukin (IL)-8, matrix metalloproteinase (MMP)-9, and epidermal growth factor receptor (EGFR). Relative gene expression was quantified using image analysis. Gene expression was normalized using poly (dT) and the expression of each factor in a panel of specimens of normal urothelium. Patients were stratified according to disease stage, and the level of gene expression among the stratified groups was compared. VEGF, bFGF, IL-8, and MMP-9 expression was increased in muscle-invasive compared with superficial papillary tumors, (p<0.05) and VEGF expression was increased in muscle-invasive tumors compared with CIS specimens (p<0. 05). bFGF, IL-8, and EGFR expression was increased in CIS specimens compared with superficial papillary tumors (p<0.05). The pattern of expression of bFGF, VEGF, IL-8, MMP-9, and EGFR represent the divergent developmental pathways in the pathogenesis of bladder TCC, which characterizes superficial or invasive bladder cancer. bFGF, IL-8, and EGFR appear to be upregulated in early precursor lesions (CIS), whereas VEGF appears to be upregulated at later stages in the development of muscle-invasive TCC.

Carcinoma in Situ↗
PubMedDate not supplied

Adenoviral-mediated gene therapy of human bladder cancer with antisense interleukin-8.

We previously demonstrated the importance of interleukin-8 (IL-8) as a mediator of angiogenesis, tumorigenicity, and metastasis of transitional cell carcinoma (TCC) of the bladder. In the present study, we evaluated the feasibility of adenoviral mediated antisense IL-8 gene transfer (Ad IL-8-AS) as therapy for established TCC. In vitro, Ad IL-8-AS inhibited endothelial cell proliferation and enhanced endothelial cell apoptosis. The highly metastatic human TCC cell line 253J B-V(R) was implanted into the subcutis of athymic nude mice, and intralesional therapy with Ad IL-8-AS commenced when the tumors reached a diameter between 5 and 7 mm. Tumor growth was significantly inhibited compared with therapy in controls (saline and beta-galactosidase adenovirus). Ad IL-8-AS therapy decreased the in vivo expression of IL-8 and matrix metalloproteinase type 9 (MMP-9), reduced microvessel density, and enhanced endothelial cell apoptosis. These results indicate that Ad IL-8-AS therapy targets both tumor cells and host endothelial cells resulting in endothelial cell apoptosis and significant inhibition of tumor growth.

Adenoviridae↗