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At least 991 records · Page 55Linked to original sources
PubMed1982

Role of locally generated prostaglandins in adaptive gastric cytoprotection.

This study was designed to determine the role of mucosal generation of prostaglandins (PGs) in the ability of mild irritants (20% ethanol or 5% NaCl) to protect against the formation of mucosal lesions caused by necrotizing agents (100% ethanol or 25% NaCl) or acidified aspirin (ASA). Mild irritants protected damage from necrotizing agents but not from ASA. This protection was accompanied by increased mucosal generation of PGE2 and PGI2-like substances. Exogenous PGE2 and PGI2 applied topically to the gastric mucosa in a nonantisecretory dose greatly inhibited the formation of lesions induced by either necrotizing agents or ASA. Pretreatment with indomethacin, which suppressed the generation of mucosal PGs augmented formation of lesions by necrotizing agents and partly counteracted the protective effect of mild irritants. We conclude that mild irritants, and exogenous PGs inhibit the formation of gastric lesions by necrotizing agents, at least in part, by mucosal generation of PGs.

Animals↗
PubMed1988

Somatostatin stimulates prostaglandin production by rat gastric epithelial cells in vitro, but is not cytoprotective.

Whether somatostatin stimulates prostaglandin synthesis by gastric cells is controversial. Also, it is unknown whether somatostatin protects gastric cells against exogenous injury in conditions independent of systemic factors and of inhibition of gastric acid secretion. The present study was undertaken (1) to evaluate the effect of somatostatin on prostaglandin production by rat gastric epithelial cells in monolayer culture and (2) to assess whether somatostatin protects gastric cells against taurocholate- and indomethacin-induced damage in vitro. Somatostatin at concentrations of 10(-5) M and 10(-4) M significantly stimulated PGE2 and 6-keto-PGF1 alpha production by rat gastric epithelial cells but was not able to prevent damage induced by sodium taurocholate and indomethacin to rat gastric cells in monolayer culture. These results suggest that: (1) somatostatin stimulates prostaglandin synthesis by cultured rat gastric epithelial cells, but (2) is not directly protective to rat gastric epithelial cell monolayers against drug-induced damage in vitro.

6-Ketoprostaglandin F1 alpha↗
PubMed1982

Cytoprotection - organoprotection by somatostatin: gastric and hepatic lesions.

In rats, the hemorrhagic gastric erosions produced by ethanol, and the fatal hemorrhagic hepatic necrosis induced by phalloidin, were significantly reduced by regular somatostatin, but not by derivatives devoid of -SH containing cysteines. These effects of the hormone were abolished in animals which received, in addition, the sulfhydryl blocker n-ethylmaleimide before the toxic chemicals. Thus, somatostatin exhibits organoprotection dependent on endogenous sulfhydryls.

Animals↗
PubMed1995

Topical nicotine protects rat gastric mucosa against ASA-induced damage. A role for mucosal fluid secretion in cytoprotection.

Acute intragastric nicotine administration has previously been shown to protect against ethanol-induced gastric mucosal damage. The aim of this study was to examine the effects of acute nicotine exposure on ASA-induced gastric mucosal damage and to determine if nicotine's protective effect is secondary to an increase in mucosal blood flow or in mucosal fluid secretion, as reflected by changes in the juxtamucosal pH gradient and volume of intragastric fluid. Mucosal blood flow, using a laser Doppler flowmeter, juxtamucosal pH gradient (depth, magnitude, and surface pH), using antimony microelectrodes, and changes in volume of luminal bathing solutions were measured in rat ex vivo gastric chamber preparations prior to and after a 10-min exposure to topical nicotine (1 mg in 8 ml of 0.2 M mannitol in 50 mM HCl), or to mannitol-HCl solution (vehicle). This was followed by application of acidified ASA (80 mM in 160 mM HCl) to the chambered mucosae for 10 min. Lesion area, expressed as the percentage of total glandular mucosa which was damaged, was significantly (P < 0.05) reduced by nicotine pretreatment. Blood flow decreased with nicotine exposure by 18.4%, compared to 13.6% in the control group (NS). Both gradient depth and gastric fluid volume increased significantly in the nicotine group (P < 0.05) compared to controls. Yohimbine pretreatment prevented both the increase in juxtamucosal pH gradient depth and the protective effect of nicotine. These results suggest that acute intragastric nicotine exposure protects against ASA-induced gastric damage in rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Topical↗
PubMed1992

The acrolein cytotoxicity and cytoprotective action of alpha-tocopherol in primary cultured rat hepatocytes.

The influence of acrolein on hepatocytes and the effect of alpha-tocopherol on acrolein cytotoxicity were investigated using primary cultured rat hepatocytes. Hepatocellular injury was dependent on both acrolein concentration in medium and on duration of exposure. Treatment of hepatocytes with 100 microM acrolein resulted in a marked loss of cellular glutathione (GSH) within 15 min, gradual accumulation of cellular lipid peroxide (LPO) and subsequent lactate dehydrogenase (LDH) leakage in the medium from 3 hr after exposure to acrolein. Cellular GSH peroxidase (GSH-Px) activity at 2 hr was significantly decreased. Electron microscopic examination on hepatocytes at 8 hr revealed a marked swelling of mitochondria and ruptures of the plasma membrane. Simultaneous treatment with 100 microM acrolein and 20 microM alpha-tocopherol did not prevent the loss of cellular GSH, though it prevented the LPO accumulation and the LDH leakage. The decrease of cellular GSH-Px activity with acrolein treatment was not mitigated by co-treatment with alpha-tocopherol. Ultrastructural alterations of hepatocytes induced by acrolein were minimized by co-treatment with alpha-tocopherol. In conclusion, acute loss of GSH and GSH-Px may increase cellular LPO and lead to hepatocellular injury, though suppression of cellular LPO accumulation by alpha-tocopherol can prevent the hepatocellular injury, even under condition of lack of GSH and GSH-Px.

Acrolein↗
PubMed1999

Cytoprotective effect of trimetazidine on 60 minutes of intestinal ischemia-reperfusion injury in rats.

Trimetazidine (TMZ), a potent antioxidant agent, has been used to protect the myocardium, liver and kidney from ischemia reperfusion (IR) injury. We investigated the effect of TMZ, a cellular anti-ischemic agent and a free radical scavenger, on 60 min of warm intestinal IR injury in rats. Sprague-Dawley rats were divided into three groups: a sham-operated group (no IR injury, n = 8), an ischemic control group (control, n = 8), and a TMZ-treated group (3 mg/kg, n = 8). Malondialdehyde (MDA) levels, myeloperoxidase (MPO) activity, and mucosal damage were investigated after 120 min of reperfusion. MDA levels and MPO activity were more elevated and histopathological damage more severe in the control group than in the sham group (P < 0.05). MDA levels and MPO activity were lower and there was less histopathological damage in the TMZ group than in the control group (P < 0.05). Accumulation of lipid peroxidation products and neutrophils in mucosal tissues were significantly inhibited by TMZ treatment. We conclude that pretreatment of rats with TMZ before intestinal ischemia attenuates but does not prevent, histological damage.

Animals↗
PubMed2007

Cytoprotective agent in Lactobacillus bulgaricus extracts.

Adenosine 5'-diphosphoribose (ADP-ribose) has been identified as a significant contributor to the anti-cytotoxic activity of Lactobacillus bulgaricus extracts. Although the biological activities associated with the administration of probiotic bacteria and components thereof are sometimes attributed to the peptidoglycans that comprise a substantial portion of the Gram-positive bacterial cell wall, we found that the beta-nicotine adenine dinucleotide (NAD) hydrolysis product ADP-ribose was a significant contributor to the observed anti-cytotoxicity in our L. bulgaricus extracts. The ADP-ribose was isolated, identified, and quantitated by high performance liquid chromatography (HPLC) and by nuclear magnetic resonance (NMR) spectroscopy. ADP-ribose levels as low as 5 mg/L exhibited a measurable inhibition of tumor necrosis factor alpha (TNF-alpha) mediated cytotoxicity in an in vitro cell assay, whereas the ADP-ribose content of the L. bulgaricus extracts often exceeded 5 mg/g dry weight.

Adenosine Diphosphate Ribose↗
PubMed2005

Use of antisense oligonucleotides targeting the cytoprotective gene, clusterin, to enhance androgen- and chemo-sensitivity in prostate cancer.

The discovery and targeting of genes mediating androgen-independence may lead to the development of novel therapies that delay progression of hormone refractory prostate cancer (HRPC). Clusterin is a stress-associated cell survival gene that increases after androgen ablation. Here, we review clusterin's functional role in apoptosis and the use of antisense oligonucleotides (ASOs) against clusterin to enhance apoptosis in prostate cancer models. Immunostaining of tissue microarrays constructed from untreated and post-hormone treated radical prostatectomy specimens confirm that clusterin is highly expressed in virtually all HRPC cells, 80% of prostate cancer cells after neoadjuvant hormone therapy, but is low or absent (<20%) in untreated specimens. Overexpression of clusterin in LNCaP cells confers resistance to both androgen ablation and chemotherapy. Clusterin ASOs reduced clusterin levels in a dose-dependent and sequence-specific manner. Adjuvant treatment with murine clusterin ASOs after castration of mice bearing Shionogi tumors decreased clusterin levels, accelerated apoptotic tumor regression, and significantly delayed the recurrence of androgen-independent tumors. A human clusterin ASO targeting the translation initiation site and incorporating MOE-gapmer backbone (OGX-011) synergistically enhanced the cytotoxic effects of paclitaxel in human xenografts of prostate, renal cell, bladder, and lung cancer. Clusterin, is an anti-apoptosis protein upregulated in an adaptive cell survival manner by androgen ablation and chemotherapy that confers resistance to various cell death triggers. Suppression of clusterin levels using ASOs enhances cell death following treatment with androgen ablation, radiation, and chemotherapy.

Androgens↗
PubMed1998

Radiochemotherapy with amifostine cytoprotection for head and neck cancer.

A randomized study was conducted to evaluate the protective activity of amifostine (A) against the dose-limiting toxicities of radiochemotherapy (RCT). Patients with head and neck cancer received radiotherapy (2 Gy/day 5 days a week up to 60 Gy) with carboplatin 70 mg/m2 on days 1-5 and 21-25 inclusive. Patients either received RCT alone (n = 14) or RCT + A at a dose of 500 mg prior to treatment with carboplatin (n = 25). There was a significant reduction in the incidence of grade 3/4 mucositis (P < 0.0001), acute grade 2 xerostomia (P < 0.0001) and grade 3/4 thrombocytopenia (P = 0.012) in these patients who received A. The incidence of grade 2 late xerostomia at 12 months is 16.7% and the incidence of loss of taste is 0% in patients treated with A, as opposed to 54.5% and 63.6% in patients who received RCT alone. There were 18 (72%) complete responses (CR) and 6 (24%) partial responses (PR) in patients who received A, compared with 6 (43%) CR and 6 PR (43%) in patients treated with RCT alone. The disease-free survival at 12 months is 85.7% in the RCT + A arm and 78.6% in the RCT alone arm. The use of amifostine reduces the incidence and severity of acute and late toxicities associated with RCT whilst preserving antitumour activity.

Adult↗