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PubMedDate not supplied

[Anticholinergics and cytoprotectants in gastroduodenal ulcer].

The authors evaluate the present curative indications of anticholinergic and cytoprotector drugs in the treatment of ulcer disease. They conclude that the therapeutic relevance of mucosal protective agents is limited in comparison with the major gastroactive medications especially in the treatment of peptic ulcer disease.

Anti-Ulcer Agents↗
PubMed1993

[Evaluation of the clinical efficacy of misoprostol for gastric cytoprotection in patients under treatment with NSAID after proctologic intervention].

To perform ambulatorial surgery with local anaesthetics, it is important to carry out a correct postsurgical NSAID therapy avoiding the risks induced by these drugs. Two groups of patients submitted to ambulatorial hemorrhoidectomy were enrolled in a randomized study to evaluate the safety of NSAID therapy with or without the coadministration of misoprostol, a PGE1 analogue with gastroprotective action. Aim of this study was to evaluate if misoprostol in coadministration with NSAID could permit a correct domiciliary postsurgical NSAID therapy without gastric symptoms related to the NSAID therapy. From January 1990 to December 1991, 95 patients underwent hemorrhoidectomy and were discharged with analgesic therapy: the first group (n = 45) without gastroprotective therapy, the second group (n = 50) with the coadministration of misoprostol 200 mcg bid. After 7 and 14 days of treatment patients showed the following symptoms: in the first group 13.3% of the cases showed mild epigastric pain, 8.8% moderate epigastric pain and 4.4% severe epigastric pain with heartburn; in the second group (NSAID + misoprostol) only 4% of the cases showed moderate epigastric pain. The incidence of epigastric pain was statistically higher (p < 0.05) in patients treated with NSAID alone in comparison with the group treated with NSAID + misoprostol. The results, according to international literature, show that correct gastro-protective therapy with synthetic prostaglandins (misoprostol) is necessary for patients in treatment with NSAIDs.

Adult↗
PubMed1994

The influence of high and low doses of diltiazem on isolated alveolar type II cells during normothermic and hypothermic ischemia: cytoprotection or cytotoxicity?

The alteration of calcium homeostasis is of outstanding importance for the cytotoxic reactions that place after ischemia, for this reason calcium channel blockers have been used with the purpose to protect the lung during transplantation. This work analyses the effect of Diltiazem at two different doses (10 mg/l and 50 mg/l) on Wistar rat alveolar type II cells, incubated for 8 hours at 37 degrees C and at 4 degrees in an electrolytic solution. Total protein content and the rate of protein synthesis derived from 35S Methionine uptake were used to evaluate cells viability. The data showed that Diltiazem did not improve cellular viability after warm and cold metabolic ischemia either using 10 mg/l or 50 mg/l, while at 4 degrees C a significantly cytotoxic effect (p < 0.05) was observed. At this temperature toxicity was independent on the dose used.

Animals↗
PubMed1996

Adsorption of mixtures of bile salt taurine conjugates to lecithin-cholesterol membranes: implications for bile salt toxicity and cytoprotection.

Tauroursodeoxycholate (TUDC), a relatively hydrophilic bile salt, reduces disruption of cholesterol-rich membranes by more hydrophobic bile salts such as taurocholate (TC), taurochenodeoxycholate (TCDC), or taurodeoxycholate (TDC). We examined the interactions of these bile salts in adsorption to large unilamellar vesicles to determine whether TUDC may stabilize membranes by preventing adsorption of more toxic bile salts. Fractional adsorption was quantified by rapid ultrafiltration. Adsorption coefficient Ai was defined for each bile salt i as ([bound i]/[free i])/[lecithin]. Affinity of different bile salts for lecithin vesicles varied with their relative hydrophobicity, increasing in the order TUDC < TC << TCDC < or = TDC. Ai of each bile salt fell with its accumulation on membranes, reaching a minimum at bound bile salt/lecithin mole ratio (B:L) between 0.05 and 0.1, then increasing with formation of higher-affinity mixed micelles. Inclusion of cholesterol in vesicles reduced Ai of all bile salts. In heterologous binding studies at submicellar concentrations, Ai of each bile salt varied with total B:L but was independent of the specific bile salts present on the membrane. Addition of TUDC to TDC reduced binding of TDC to membranes only slightly and lowered the threshold TDC concentration associated with transition to mixed micelles. However, above this threshold, TUDC markedly altered the adsorption of TDC to lecithin-containing phases. We conclude that TUDC does not directly stabilize membranes; rather, reduced permeabilization and dissolution of cholesterol-rich membranes after addition of TUDC to TDC may result from effects on the formation and structure of simple and mixed micelles.

Adsorption↗
PubMed1996

Isolated rat gastric mucosal cells: optimal conditions for cell harvesting, measures of viability and direct cytoprotection.

Controversial data have been obtained with direct cellular protection by prostaglandins and sulfhydryls. In the present studies, we compared the merits and liabilities of currently available cell viability assays, some of which have not been previously employed in studies of the gastric mucosa. We also tested the hypothesis that length of incubation of isolated cells with protective agents might influence the degree of cellular damage. Gastric mucosal cells were isolated from nonfasted rats and digested with various concentrations of pronase and/or EGTA. Cell viability was assessed by trypan blue and fast green exclusion, fluorescein diacetate hydrolysis, chromium release, LDH release, mitochondrial succinate dehydrogenase activity and nuclear fluorescence induced by ethidium bromide. The experiments revealed that both pronase and EGTA are needed to obtain mucosal cells with optimal yield and initial viability and that sequential additions of pronase (30 min) and EGTA (30 min), rather than their combination (60 min), increased viability without decreasing yield. Cell viability and yield were better when pronase was used in the first incubation. For LD50 determinations, a cell suspension was incubated with ethanol (0%-15%) for 5 min. For studying the effects of protective agents, the cells were pretreated with 16,16-dmPGE2 or cysteamine HCl at 37 degrees C for 30 min before a 5-min exposure to 7.5% or 15% ethanol. The LD50 value for ethanol injury was approximately 15% for all assays except LDH, where the LD50 value was 8.5%. Preincubating gastric mucosal cells for 30 min with 16,16-dmPGE2 or cysteamine resulted in no preservation of cell viability. However, when cells were preincubated with one of the protective agents for 60 min and then exposed to 8% or 10% ethanol for 5 min, partial protection was observed when assessed by succinate dehydrogenase activity and, in certain cases, by LDH release. We conclude that all seven cell viability assays yield a measurable LD50 value for ethanol-induced cell injury, but the results may vary by as much as 82%. Low concentrations of both pronase and EGTA are needed to obtain isolated mucosal cells with both high yield and initial viability. Biochemical measures of mitochondrial activity and nuclear damage provide reliable evidence of cell viability and should be used to complement membrane permeability assays. Long preincubation of cells (60 min) with protective agents resulted in only slight protection of mitochondrial function, in contrast to the rapid induction of gastroprotection seen with these compounds in vivo. We therefore surmise that processes that contribute to organ protection occur faster and more efficiently than those that control direct cell injury and protection.

Animals↗
PubMed1996

The mechanism of cytoprotective action of lazaroids I: Inhibition of reactive oxygen species formation and lethal cell injury during periods of energy depletion.

Tirilazad mesylate and related compounds, known as lazaroids, are recognized as inhibitors of membrane lipid peroxidation that also act as free radical scavengers. These compounds have demonstrated protective activity in animal models of traumatic head injury and cerebral ischemia. In this study we used an in vitro cell model to investigate the mechanism by which tirilazed mesylate and related antioxidants delay or prevent the lethal cell injury provoked by chemically induced energy depletion. When the cultured human astrocytoma cell line UC-11MG was treated with the metabolic inhibitor sodium iodoacetate for 4 hr, the cells exhibited signs of irreversible cell injury, including alterations in plasma membrane morphology, the breakdown of membrane phospholipids (release of arachidonic acid into the extracellular medium) and the loss of viability as indicated by the leakage of cytoplasmic components. A large quantity of reactive oxygen species (ROS) was detected in the injured cells by a dichlorofluorescin assay. Increases in early lipid peroxidation products were detected as elevated hydroxyeicosatetraenoic acids in the membrane phospholipds, which indicated that the membrane lipids were oxidatively damaged. The addition of tirilazad mesylate, a troloxamine derivative or the common phenolic antioxidant nordihydroguaiaretic acid effectively prevented the increases in ROS, attenuated the elevation of hydroxyeicosatetraenoic acids, and delayed irreversible cell injury. We propose that the destruction of crucial cell constituents in the lipophilic compartments by ROS is one of the major causes of lethal cell injury. The cyytoprotective action of the lazaroids in related, as least in part, to their ability to block the formation of ROS and to arrest the secondary cell injury.

Arachidonic Acids↗
PubMed1996

[Amifostine: current and future applications in cytoprotection].

Originally developed against the effects of ionizing radiations, amifostine is an organic thiophosphate compound shown able to selectively protect normal tissues against cytotoxic agents in cellular and animal models, without protecting tumor tissues. Amifostine is a prodrug which is dephosphorylated into its active metabolite, a free thiol derivative, by membrane alkaline phosphatase of the target issue. This unique metabolism supports its cellular selectivity and its preferential uptake by normal tissues. In phase II clinical trials, a decreased toxicity has been demonstrated in patients given alkylating agents; however, reduction of the response has not been observed. On the basis of these results, a prospective, randomized, phase III study has been conducted in patients with ovarian carcinoma receiving a combination of cisplatinum and cyclophosphamide. A significant decrease in hematologic, renal and neurologic toxicity was observed in the amifostine-treated patients compared with the control group, and response rates did not significantly differ between the two groups. Insufficient or emerging data are only available for other applications, including either in vitro manipulation of hematopoietic grafts or in vivo treatment of non-Hodgkin's lymphoma, head and neck carcinoma, non-small cell lung cancer and radioprotection. No data are yet available in regard to the potential protective effects of amifostine against mutagenicity and cancerogenicity of both chemo- and radiotherapy.

Amifostine↗
PubMedDate not supplied

Formulation of aspirin-magaldrate double-layer tablets: in vitro evaluation and cytoprotective activity in rats.

Double layer 325 mg oral aspirin tablets buffered with magaldrate antacid, 100, 150, 175 and 200 mg (F1, F2, F3 and F4, respectively) were prepared by direct compression. The new formulae were of remarkable hardness and friability. The tablets complied with the requirements of the acid neutralizing capacity, uniformity of dosage units, disintegration and dissolution tests (USP XXIII) for buffered aspirin tablets. The in vitro release pattern of F1 and F1 followed first order kinetics (r = 0.999), while F3 and F4 were released according to a zero order model (r = 0.993). Formulations F2, F3 and F4 as well as the marketed preparations, pure Aspro tablets (Acetylsalicylic acid 320 mg per tablet), or Ascriptin tablets (aspirin 325 mg plus 150 mg Maalox per tablet) were administered to fasted rats by gavage at doses that provided 400 mg aspirin kg-1 and the extent of the induced gastric damage was quantified 6 h later. Ascriptin, F3 and F4 preparations produced significantly less gastric damage (p < 0.05, n = 6) when compared with pure Aspro tablets. There was a clear dose-dependent decrease in the gastric damage following treatment with F2, F3 and F4 preparations, but there was no significant difference between the effects of F3 and F4 which were equipotent with Ascriptin.

Aluminum Hydroxide↗
PubMed1996

Myocardial ischemia, reperfusion and cytoprotection.

The hypothesis proposed is that ischemic cell death is a metabolic event as evidenced by ischemic contracture. There is a protective role for glycolytic ATP and for some drugs. There must be enough coronary flow to deliver the glucose. It appears that provision of glucose and restoration of blood flow have complementary benefits. Such combinations need exploration in patients.

Adenosine Triphosphate↗
PubMed1997

Role of cytoprotective mechanisms in the photochemical purging of autologous bone marrow grafts.

The molecular basis of the differential sensitivity of normal hematopoietic stem cells and of leukemia, lymphoma, and neuroblastoma cells to merocyanine 540 (MC540)-mediated photodynamic therapy (PDT) is not yet completely understood. While the capacity to bind dye molecules appears to be the major determinant of a cell's susceptibility of MC540-mediated PDT, we here present evidence that under certain experimental conditions a cell's capacity to repair MC540-mediated photodynamic damage is also an important factor. Two parameters, temperature and intracellular glutathione (GSH) content, were varied to investigate the role of cellular defense mechanisms in the dye-sensitized photoinactivation of normal murine granulocyte/macrophage progenitors (CFU-GM) and K562, L1210, and melphalan-resistant L1210/L-PAM1 leukemia cells. When exposed to MC540 and light at room temperature, the three leukemia cell lines bound similar amounts of dye and accumulated similar amounts of lipid hydroperoxide (LOOH) but differed markedly in their sensitivity to MC540-mediated PDT. Performing MC540-mediated PDT at 4 degrees C instead of at room temperature reduced dye binding and LOOH generation and enhanced cytotoxicity in some but not all cell lines. A brief (< or = 120 minutes) incubation at 37 degrees C immediately following MC540-mediated PDT accelerated the decay of LOOH in all leukemic cell lines and reduced cell kill by about 2 log in both CFU-GM and leukemia cells. The effect of post-PDT incubation at 37 degrees C on LOOH decay was most pronounced in K562 and least pronounced in L1210/L-PAM1 cells, whereas its effect on cell survival was less pronounced in L1210 cells than in the remaining cell types. L1210/L-PAM1 cells whose GSH content had been reduced from 8.2 to 1.6 micrograms/mg protein by incubation with buthionine sulfoximine recovered from potentially lethal photodynamic damage as rapidly as untreated L1210/L-PAM1 cells and more rapidly than wild-type L1210 cells with a GSH content of 4.5 micrograms/mg protein. Thus, with regard to capacity of L1210/L-PAM1 cells to recover from photodynamic damage, the cells' enhanced capacity to synthesize GSH appeared more decisive than intracellular GSH levels per se. Taken together, these data suggest that temperature-dependent cellular defense mechanisms are significant determinants of a cell's susceptibility to MC540-mediated PDT. The data emphasize the need for temperature control during and immediately after the photochemical purging of autologous bone marrow or peripheral blood stem cells.

Animals↗