The Effect of Curcumin on Oxaliplatin and Cisplatin Neurotoxicity in Rats: Some Behavioral, Biochemical, and Histopathological Studies

Cisplatin is commonly used against several solid tumors, and oxaliplatin is an effective cytotoxic drug used in colorectal cancer. A major clinical issue affecting 10–40 % of patients treated with cisplatin or oxaliplatin is severe peripheral neuropathy causing sensory, motor, and autonomic dysfunction, with symptoms including cold sensitivity and neuropathic pain. The biochemical basis of the neurotoxicity is uncertain, but is associated with oxidative stress. Curcumin (a natural phenolic yellow pigment) has strong antioxidant, anticancer, and anti-inflammatory actions. Here we report the possible protective effect of curcumin on some cisplatin- and oxaliplatin-induced behavioral, biochemical, and histopathological alterations in rats. Twenty-four hours after the end of treatments some motor and behavioral tests (motor activity, thermal and mechanical nociception, and neuromuscular coordination) were conducted, followed by measuring plasma neurotensin platinum concentration in the sciatic nerve, and studying the histopathology of the sciatic nerve. Oxaliplatin (4 mg/kg) and cisplatin (2 mg/kg) [each given twice weekly, in a total of nine intraperitoneal injections over 4.5 weeks] significantly increased plasma neurotensin concentration, caused specific damage in the histology of the sciatic nerve and produced variable effects in the motor and behavioral tests. Oral curcumin (10 mg/kg, 4 days before the platinum drug, and thereafter, concomitantly with it for 4.5 weeks) reversed the alterations in the plasma neurotensin and sciatic nerve platinum concentrations, and markedly improved sciatic nerve histology in the platinum-treated rats. Larger experiments using a wider dose range of oxaliplatin, cisplatin, and curcumin are required to fully elucidate the possible protective role of curcumin in platinum-induced neurotoxicity.     

Positional effect of mutations in 5＇UTR of hepatitis C virus 4a on patients＇ response to therapy

AIM： To investigate the effects of mutations in domain Ⅲ of the hepatitis C virus （HCV） internal ribosome entry sequences （IRES） on the response of chronic HCV genotype 4a patients to interferon therapy.
METHODS： HCV RNA was extracted from 19 chronic HCV 4a patients receiving interferon/ribavirin therapy who showed dramatic differences in their response to combination therapy after initial viral clearance. IRES domain Ⅲ was cloned and 15 clones for each patient were sequenced. The obtained sequences were aligned with genotype 4a prototype using the ClustaIW program and mutations scored. Prediction of stem-loop secondary structure and thermodynamic stability of the major quasispecies in each patient was performed using the MFOLD 3.2 program with Turner energies and selected constraints on base pairing.
RESULTS： Analysis of RNA secondary structure revealed that insertions in domain Ⅲ altered WatsonCrick base pairing of stems and reduced molecular stability of RNA, which may ultimately reduce binding affinity to ribosomal proteins. Insertion mutations in domain - were statistically more prevalent in sustained viral response patients （SVR, n = 14） as compared to breakthrough （BT, n = 5） patients.
CONCLUSION： The influence of mutations within domain Ⅲ on the response of HCV patients to combination therapy depends primarily on the position, but not the frequency, of these mutations within IRES domain Ⅲ.     

Influence of experimental type 1 diabetes on the pulmonary effects of diesel exhaust particles in mice

Epidemiologically, exposure to particulate air pollution is associated with increases in morbidity and mortality, and diabetics are especially vulnerable to effects of particles. This study was carried out to determine the respiratory effect of diesel exhaust particles (DEP; 0.4 mg/kg) on mice rendered diabetic by the injection of streptozotocin or vehicle (control). Four weeks following induction of diabetes, the animals were intratracheally instilled (i.t.) with DEP (0.4 mg/kg) or saline. 24 h later, the measurement of airway reactivity to methacholine in vivo by a forced oscillation technique showed a significant and dose-dependent increase in airway resistance in non-diabetic mice exposed to DEP versus non-diabetic mice exposed to saline. Similarly, the airway resistance was significantly increased in diabetic mice exposed to DEP versus diabetic mice exposed to saline. Nevertheless, there was no difference in the airway resistance between diabetic and non-diabetic mice after i.t. administration of DEP. Following DEP administration there were neutrophil polymorphs infiltration of pulmonary interalveolar septae and the alveolar spaces with many macrophages containing DEP in both diabetic and non-diabetic mice. Interestingly, apoptotic cells were only found in the examined lung sections from diabetic mice exposed to DEP. Total proteins and albumin concentrations in bronchoalveolar lavage (BAL) fluid, markers for increase of epithelial permeability, were significantly increased in diabetic mice exposed to DEP compared to saline-treated diabetic and DEP-treated non diabetic mice. Superoxide dismutase activity and reduced glutathione concentration in BAL were significantly decreased in diabetic mice exposed to DEP compared to saline-treated diabetic and DEP-treated non diabetic mice. Moreover, tumor necrosis factor α (TNFα) concentrations were significantly increased in diabetic mice exposed to DEP compared to saline-treated diabetic and DEP-treated non diabetic mice. We conclude that, at the dose and time point investigated, DEP equally increased airway resistance and caused infiltration of inflammatory cells in the lung of both diabetic and non-diabetic mice. However, the occurrence of oxidative stress, the presence lung apoptotic cells and the increase of total proteins, albumin and TNFα in BAL fluid were only seen in DEP-exposed diabetic mice suggesting an increased respiratory susceptibility to particulate air pollution.     

Experimental gentamicin nephrotoxicity and agents that modify it: a mini-review of recent research

The aminoglycoside antibiotic gentamicin (GM) is still widely used against infections by Gram-positive and Gram-negative aerobic bacteria. Its therapeutic efficacy, however, is limited by renal impairment that occurs in up to 30% of treated patients. The drug may accumulate in epithelial tubular cells causing a range of effects starting with loss of the brush border in epithelial cells and ending in overt tubular necrosis, activation of apoptosis and massive proteolysis. GM also causes cell death by generation of free radicals, phospholipidosis, extracellular calcium-sensing receptor stimulation and energetic catastrophe, reduced renal blood flow and inflammation. Many drugs have been shown to either ameliorate or potentiate GM nephrotoxicity. This article aims at updating the literature that has been published in the past decade on the effects of agents that either ameliorate or augment the nephrotoxicity of this aminoglycoside. Notable among the new ameliorating procedures are gene therapy, such as intravenous cell therapy with serum amyloid A protein-programmed cells, and the use of some novel antioxidant agents and oils of natural origin. These include, for example, green tea, garlic saffron, grape seed extracts as well as sesame and oleanolic oils. Agents that may augment GM nephrotoxicity include indomethacin, cyclosporin, uric acid and the Ca(++) -channel blocker verapamil. Most of the nephroprotective agents mentioned here have not been tested in large controlled clinical trials. Because of their relative safety and effectiveness, antioxidant agents seem to be good candidates for testing in humans.     

Interaction of nimesulide,a cyclooxygenase-2 inhibitor,with cisplatin in normotensive and spontaneously hypertensive rats

We investigated the effect of administration of nimesulide, a selective cyclooxygenase-2 (COX-2) inhibitor, on cisplatin (CP)-induced nephrotoxicity in rats. WKY rats and SHRs were divided into four groups, each. The first and second groups received saline and oral nimesulide (20 mg/kg/day for 6 days), respectively, whereas the third and fourth groups received a single intraperitoneal (i.p.) injection of CP (5 mg/kg) and CP (5 mg/kg) and nimesulide (20 mg/kg/day for 5 days), respectively. At the end of the experiment, rats were anesthetized and blood pressure and renal blood flow (RBF) were monitored, followed by intravenous (i.v.) injection of norepinephrine (NE). Nephrotoxicity was evaluated histopathologically and biochemically. CP caused a reduction in baseline RBF in both WKY and SHRs. It increased the concentrations of urea and creatinine and kidney relative weight, and decreased body weight in both WKY and SHRs. Histopathologically, CP caused remarkable renal damage in both WKY rats and SHRs. Treatment with nimesulide alone did not produce any significant change in any of the above measurements. However, nimesulide aggravated CP-induced renal tissue damage in SHRs, but not in WKY rats. The results show that administration nimesulide augmented the histopathological indices of nephrotoxicity in SHRs, but not in WKY rats.