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El-Khatib, A. S., "Possible modulatory role of nitric oxide in lung toxicity induced in rats by chronic administration of bleomycin.", Chemotherapy, vol. 48, issue 5, pp. 244-51, 2002 Dec. Abstract

BACKGROUND: The present study was undertaken to evaluate whether stimulation or inhibition of nitric oxide (NO) synthesis could affect lung toxicity induced by chronic administration of bleomycin (BLM). L-arginine (ARG) and N(G)-nitro-L-arginine methyl ester (L-NAME) were employed as NO precursor and NO synthesis inhibitor, respectively.

METHODS: BLM was administered intraperitoneally to male Wistar rats at a dose of 15 mg/kg, 3 times a week, for a total period of 4 weeks. ARG (500 mg/kg/day) and L-NAME (100 mg/kg/day) were given in drinking water, the treatments commenced with BLM and continued up to the end of the experiment. Appropriate controls were performed.

RESULTS: BLM treatment resulted in a pronounced fall in the average body weight of animals, together with a rise in the lung weight/body weight ratio. In the lung tissue, elevated levels of hydroxyproline (HP) and lipid peroxides (LP) as well as decreased activity of angiotensin converting enzyme (ACE) further evidenced the toxicity. Pulmonary level of NO end products, nitrite and nitrate, tended to rise but did not reach a significant level. Glutathione (GSH) content and GSH-peroxidase activity measured in the lung remained unaltered. In animals given concurrent treatment of BLM and ARG, a remarkable rise in the pulmonary level of nitrite and nitrate was observed. Average body weight was still decreased when compared with the untreated control group, but the decrease was significantly less than that observed in the BLM group. In addition, ARG decreased the extent of BLM-induced elevations of lung HP and LP levels. Meanwhile, ARG failed to significantly affect the BLM-evoked decrease in pulmonary ACE activity and increase in lung weight/body weight ratio. In animals given simultaneous treatment of BLM and L-NAME, noticeable reductions in the pulmonary levels of nitrite/nitrate and GSH were detected. BLM-induced decrease in body weight and increase in lung weight/body weight ratio were accentuated by L-NAME co-treatment. Furthermore, administration of L-NAME led to more profound elevations in lung HP and LP levels, without affecting the decrease in pulmonary ACE activity elicited by BLM.

CONCLUSION: In principle, the present findings indicate that the lung toxicity exerted by chronic administration of BLM is alleviated by ARG, but exacerbated by L-NAME supplementation. This could indicate a possible protective role of NO.

el-Khatib, A. S., and M. A. Mansour, "Prior treatment with captopril attenuates carbon tetrachloride-induced liver injury in mice.", Research communications in molecular pathology and pharmacology, vol. 110, issue 1-2, pp. 3-16, 2001 Jul-Aug. Abstract

The present investigation focused on the possible hepatoprotective potential of captopril on carbon tetrachloride (CCl4)-induced acute liver injury in mice. Twenty-four hours after a single intraperitoneal injection of CCl4 (20 microl/Kg), hepatotoxicity was evidenced in the serum by elevated levels of aspartate transaminase (AST; EC: 2.6.1.1), alanine transaminase (ALT; EC: 2.6.1.2) and lactate dehydrogenase (LDH; EC: 1.1.1.27) and in the liver by depleted level of reduced glutathione (GSH), enhanced activity of glutathione peroxidase (GSH-Px; EC: 1I.11.1.9) and elevated level of lipid peroxides (LP). Captopril was given orally at three dose levels viz., 10, 25 and 50 mg/Kg/day for three consecutive days before subjecting the animals to the hepatotoxin. With the exception of the lowest dose namely, 10 mg/Kg/day, captopril afforded protection against CCl4-induced hepatotoxicity to different extents. Thus, the elevated activities of the enzymes AST, ALT, LDH and GSH-Px as well as the enhanced lipid peroxidation were markedly reduced below those elicited by the hepatotoxin, reaching values closer to the control, though still statistically higher. Captopril, however, did not ameliorate the depletion of GSH produced by CCl4. The data reported herein reveal a protective potential of captopril against the acute hepatotoxicity induced by CCl4 in mice. This hepatoprotection could be attributed, at least in part, to the free radical scavenging properties of the drug.

El-Khatib, A. S., A. M. Agha, L. G. Mahran, and M. T. Khayyal, "Prophylactic effect of aqueous propolis extract against acute experimental hepatotoxicity in vivo.", Zeitschrift für Naturforschung. C, Journal of biosciences, vol. 57, issue 3-4, pp. 379-85, 2002 Mar-Apr. Abstract

Propolis has been extensively used in folk medicine for the management of a wide spectrum of disorders. In a previous study, we demonstrated the protective effect of the aqueous propolis extract (APE) against the injurious effects of carbon tetrachloride (CCl4) on hepatocytes in vitro. The present investigation was carried out to show whether the hepatoprotective effect of the extract could also be manifested in vivo. Rats were given APE orally for 14 consecutive days, before being subjected to a single intraperitoneal injection of CCl4. One day after the CCl4 injection, the animals were sacrificed, hepatocytes were isolated and liver homogenates were prepared for the assessment of liver injury. In isolated hepatocytes, APE afforded protection against CCl4-induced injury as manifested by a decrease in the leakage of the cytosolic enzyme lactate dehydrogenase (LDH), decreased generation of lipid peroxide and maintenance of cellular reduced glutathione (GSH) content. In principle, similar findings were observed in liver homogenates. The present findings show that APE has in vivo hepatoprotective potential which could be attributed at least in part to the maintenance of cellular GSH content. The latter effect seems to play an important role in conserving the integrity of biomembranes as it was associated with a decrease in lipid peroxidation and reduced leakage of cytosolic LDH.

Mahran, L. G., A. S. el-Khatib, A. M. Agha, and M. T. Khayyal, "The protective effect of aqueous propolis extract on isolated rat hepatocytes against carbon tetrachloride toxicity.", Drugs under experimental and clinical research, vol. 22, issue 6, pp. 309-16, 1996. Abstract

The protective effect of honeybee aqueous propolis extract (APE) against the hepatotoxicity of carbon tetrachloride was investigated using isolated liver-cell suspensions as the experimental model. Various concentrations of the extract were preincubated with the hepatocyte suspensions for 30 min before being subjected to the hepatotoxin for a further 30 min. The hepatocyte toxicity was assessed using three parameters, namely, the release of lactate dehydrogenase, the formation of lipid peroxides and the depletion of intracellular reduced glutathione. It was found that a dose-related protection against the induced cell injury was conferred by APE as evidenced by its inhibitory influence on the changes induced by CCl4 on the measured parameters. The hepatocyte protective effect of APE is probably a result of its antioxidant and free-radical-scavenging properties which in turn help to maintain the intracellular level of reduced glutathione.