ABSTRACT
Abstract: Objective: The feasibility of the use of WHO impregnated paper and biochemical assays to determine lethal concentrations (LC50 and LC99) and insecticide metabolic enzyme levels of Triatoma dimidiata. Materials and methods: LC50 and LC99 were calculated with WHO papers impregnated at different concentrations of malathion, propoxur and deltamethrin; the percentage of insensitive acetylcholinesterase (iAChE); and the levels of esterases, glutathione S-transferases, and monooxygenases in laboratory nymphs of the first stage (5 to 7 days), were undertaken using the WHO biochemical assays. Results: Respectively the LC50 and LC99 µg/cm2 obtained for malathion were 43.83 and 114.38, propoxur 4.71 and 19.29, and deltamethrin 5.80 and 40.46. A 30% of the population had an iAChE, and only a few individuals had high P450 and β-eterase levels. Conclusion: Impregnated papers and biochemical tests developed by WHO for other insects, proved to be feasible methods in monitoring insecticide resistance and metabolic enzymes involved in T. dimidiata.
Resumen: Objetivo: La factibilidad de usar los papeles impregnados y ensayos bioquímicos según la OMS para determinar concentraciones letales (CL50 y CL99) y niveles enzimáticos en la resistencia a insecticidas en Triatoma dimidiata. Material y métodos: Se calcularon la CL50 y CL99 con papeles impregnados según la OMS a diferentes concentraciones de malatión, propoxur y deltametrina; el porcentaje de acetilcolinesterasa insensible (iAChE); y los niveles de esterasas, glutatión S-transferasas, y monooxigenasas en ninfas de laboratorio del estadio I (5-7 días) se determinaron usando los ensayos bioquímicos según la OMS. Resultados: Se obtuvieron las CL50 y CL99 µg / cm2 respectivamente para malatión 43.83 y 114.38, propoxur 4.71 y 19.29, y deltametrina 5.80 y 40.46. Un 30% de las chinches tuvo iAChE, y sólo pocos individuos tuvieron niveles superiores de P450 y β-eterasas. Conclusión: Los papeles impregnados y ensayos bioquímicos que describe la OMS para otros insectos demostraron ser métodos factibles para monitorear la resistencia a insecticidas y las enzimas metabólicas involucradas en T. dimidiata.
Subject(s)
Animals , Propoxur/toxicity , Pyrethrins/toxicity , Triatoma/drug effects , Insecticide Resistance , Insecticides/toxicity , Malathion/toxicity , Nitriles/toxicity , Acetylcholinesterase/analysis , Triatoma/enzymology , World Health Organization , Feasibility Studies , Cytochrome P-450 Enzyme System/analysis , Esterases/analysis , Glutathione Transferase/analysis , Mixed Function Oxygenases/analysis , Lethal Dose 50 , Nymph/drug effects , Nymph/enzymologyABSTRACT
Aim: The aim of this study was to evaluate the synergistic effect of low radiation dose with the chemotherapeutic drug in order to find possible way to lessen the harmful effects during chemo-radiotherapy. Study Design: Randomized controlled experiment. Place and Duration of Study: Experimental Animal Unit, Drug Radiation Research Department, National Center for Radiation Research and Technology, Cairo Egypt. Methodology: Estimation of antioxidant activity of low radiation dose on oxidative stress induced by cisplatin administration at a dose of 10 mg/kg b. wt. in male albino rat. Results: Results of experiment revealed that cisplatin administration caused a significant increase in serum alanine transaminase (GPT) activity (38.58±2.060) and FSH level (8.162±1.424) accompanied with a decrease in serum albumin (3.492±0.253), and Butyry Cholein Esterase (BChE) (65.35 12.61). In Liver and testis, GSH content (68.00±2.391 & 24.93±4.778) as well as cytochromes P450 levels (0.3875±0.0727 & 0.2167±0.0459) showed a significant decrease as compared to the normal control level respectively. In addition the level of Fe, Cu and Zn showed no significant changes in liver and appeared to be significantly decrease as in case of corresponding trace elements in testis organs. On the other hand, exposing to low dose of radiation (0.5 Gy) post-cisplatin treatment effectively prevented these alterations and maintained the antioxidant status. Conclusion: Data from present results revealed that low radiation dose have the existence as an antioxidant and antitumor agents which may be useful to use as a synergistic agents with the chemotherapeutic drug.
ABSTRACT
Pharmacogenomics (or pharmacogenetics), the study of the effects of genetic differences on a person’s response to drugs, can help in optimizing drug efficacy and minimizing adverse drug reactions. Interperson difference in drug metabolism is one of the important consequences of such genetic variation. This variation is determined in part by mutations in cytochrome P450 enzymes (CYPs). IMU is part of a major collaborative research project in the area of phamacogenetics and drug metabolism. Working together with USM and UiTM, our group has, since 2000, generated useful population database on genetic polymorphism of various CYP isoforms. We have successfully genotyped three major ethnic groups, Malay, Indian and Chinese for their allelic frequency of important isoforms. These include CYP2D6, CYP2C9, CYP2C8 and CYP2A6. Data generated so far collectively have contributed to our effort in mapping and constructing genomic database for Malaysian population. Since early 2002, our research has been focusing on developing in vitro methods in studying the functional consequences of genetic polymorphism of CYP enzymes. Using site-directed mutagenesis, CYP mutants, carrying nucleotide changes as reported in known alleles in human populations, were generated and expressed in E. coli system, and the expressed recombinant proteins were characterized using enzyme assays to determine the functional consequences of mutations. We have established a series of HPLC (high performance liquid chromatography)-based and fluorescence-based assays to investigate CYP activities. Assays that have been developed include tolbutamide methylhydroxylase, paclitaxel 6a-hydroxylase, dextromethorphan O-demethylation, testosterone 6b-hydroxylation and coumarin 7-hydroxylase assays. These assays serve as activity markers allowing comparison of catalytic activities of mutant proteins generated. Another focus of our work is to use the developed assays as a screening tool to investigate drug-herb interactions. This was achieved by co-incubation of herbal extracts and active constituents with the probe substrates in the assays followed by characterization of the kinetic behaviors of the enzymes involved using various pharmacokinetic parameters such as Km, Vmax, IC50 and Ki. This work is currently carried out with collaboration from the Institute for Medical Research (IMR) and is supported by MOSTI’s eScienceFund under RM9. It is envisaged that this screening work will give us insights on the potential of the commonly used herbs to cause pharmacokinetic interactions with other drug substrates, and allow us to elucidate the mechanisms involved in the interactions.
ABSTRACT
AIM: To study the methodology of hepatic cytochromes P450 in Wistar rats. METHODS: After the Wistar rats were administered with gatifloxacin and ciprofloxacin once daily for 7 days,and liver microsome was distilled by different velocity centrifugation. The Lowry method was used to measure the concentration of protein in liver microsome,and the activities of gatifloxacin in hepatic microsomal enzymes (CYP450) of rats were studied by spectrophotometer. RESULTS: The linearity range of ox blood serum albumin standard curve was 25-250 mg?L -1 with the detection limits 25 mg?L -1 and correlation coefficient 0.9988 . The contents of cytochromes P450 and cytochromes b5 and the activity of NADPH-cytochrome C reductase indicated that ultraviolet spectrophotometer method was sensitive. The linearity range of formaldehyde standard curve,which was used to measure the activities of aminopyrine-N-demethylase and erytheomycin-N-demethylase was 0.05 - 0.5 mmol?L -1 with the detection limits 0.05 mmol?L -1 and correlation coefficient 0.9998 . The linearity range of resorufin standard curve,which was used to measure the activity of Coumarin 7-hydroxylation was 1-8 ?mol?L -1 with the detection limits 1 ?mol?L -1 and correlation coefficient 0.9998 . CONCLUSION: The methods of measuring the contents and activities of the six hepatic microsomal enzymes are sensitive and credible in Wistar rats by ultraviolet and fluorescence spectrophotometer.