Neurotoxic effect of dermally-applied chlorpyrifos and cypermethrin in Wistar rats.

The aim of the study was to evaluate the neurotoxic effect of a dermally-applied mixture of chlorpyrifos and cypermethrin in rats based on cognitive function, activity of the blood cholinesterase and brain acetylcholinesterase, as well as histologic brain examination. Nurelle D 550 EC (500 g of chlorpyrifos and 50 g of cypermethrin) was used in the study. The application liquid was in the form of a water solution. The investigation covered eight groups of animals: six experimental groups and two control groups, of 15 rats each. Experimental groups received 5.6 mg/cm2 chlorpyrifos and 0.5 mg/cm2 cypermethrin, or 27.8 mg/cm2 chlorpyrifos and 2.7 mg/cm2 cypermethrin dermally, for one day, one week and four weeks, except for Saturdays and Sundays. The preparations examined were applied to the tail skin of rats. The animals were anaesthetized at the end of exposure period. Plasma cholinesterase and brain acetylcholinesterase activities were determined. The brain for histological examination was perfused with a solution of methanol, formalin and glacial acetic acid, and the sections stained by the Nissel method. The behaviour of the animals was evaluated in the open field test four times: before exposure, and after one, two and four weeks of the experiment. The results of the study showed that chlorpyrifos and cypermethrin applied in a mixture caused an inhibition of cholinesterase and acetylcholinesterase activity and elicited the pycnosis of brain neurocytes.

Studies of toxicity of dermally-absorbed nurelle D 550 EC preparations.

The aim of the study was the evaluation of the toxic effect of a two-component, preparation Nurelle D 550 EC (500 g of chlorpyrifos and 50 g cypermethrin per 1 l), administrated dermally. Toxicity was evaluated from histological and ultrastructural studies of the internal organs and immunotoxic effects (evaluation of phagocytical and bactericidal activity of neutrophils). The preparation for dermal application was applied in 2 concentrations (200 mg/kg/day of chlorpyrifos plus 20 mg/kg/day of cypermethrin or 1000 mg/kg/day of chlorpyrifos, plus 100 mg/kg/day of cypermethrin). The preparation was administrated on the tail skin of female Wistar rats for 4 hours daily for a period of 4 weeks. After 28 days of the experiment, the animals were anaesthetised and blood was taken from the heart to evaluate the granulocyte system. The following organs were taken for histological studies: liver, kidney, lung, heart, spleen, thymus and lymph nodes. Ultrastructural studies were carried out on the lung, liver, kidney and heart. The results of the study showed that dermal application of the pesticide Nurelle D 550 EC resulted in slight morphological and ultrastructural changes in the liver, kidney, lung and heart. The preparation examined slightly elevated the bactericidal activity of neutrophils. The differences, however, were not statistically significant. The phagocytic reaction in animals of both experimental groups did not differ from that observed in control group

Toxicity of dermally applied alpha-cypermethrin in rats.

The aim of the study was to assess the immunotoxic effect of dermally applied alpha-cypermethrin in rats based on phagocytic and bactericidal activity of neutrophils of peripheral blood, and the general toxic effect based on histological and ultrastructural examination of internal organs. The preparation was dermally applied in doses of 50 mg/kg and 250 mg/kg. It was administered to the tail skin of female Wistar rats, 4 hours daily for 28 days. After the experiment, the animals were anaesthetized and heart blood was taken in order to evaluate the activity of granulocyte system. The following organs were taken for histological examinations: brain, lung, heart, liver, spleen, kidneys, thymus and lymphatic nodes. Lung, liver, kidney and heart were used for ultrastructural studies. The results of the study showed that bactericidal and phagocytic activity of neutrophils was stimulated after administration of 50 mg/kg alpha-cypermethrin. Dermal application of the preparation resulted in slight histological changes in liver, kidney, lung and brain. Pathological changes in heart were observed only on the level of ultrastructure.

Toxicity of dermally absorbed dichlorvos in rats.

Toxicity of dermally absorbed dichlorvos was studied in rats, based on its effects on internal organs, and on phagocytic and bactericidal activity of the neutrophile system. The studies were conducted on 30 female rats of Wistar strain. The animals were divided into three groups, two of which were experimentally exposed to dermal absorption of dichlorvos (37.5 mg/kg - 1/2 LD50; or 7.5 mg/kg - 1/10 LD50;), and one control group which was exposed to dermal absorption of the solvent. The animals were exposed to dermal absorption for 4 hours daily for a period of 4 weeks. After 28 days, the rats were anaesthetized, blood was drawn from the heart to evaluate the activity of the neutrophilic system, and the internal organs excised for histological and ultrastructural studies. Dermally absorbed dichlorvos caused histopathological changes in lungs, lymphatic glands and thymus, as well as histopathological and ultrastructural changes in liver, kidneys and heart muscle. Dichlorvos stimulated the bactericidal and phagocytic activity of neutrophils.

Influence of some immune factors on the IL-6 and soluble IL-2 receptors in haemodialysed patients.

In respect to the immune deficiency state of long-term haemodialysed patients, both cytokines and their receptor disturbances have been taken into consideration. The purpose of our study was to evaluate the effect of uraemic and haemodialysis factors on the interleukin-6 and interleukin-2 soluble receptor levels and the reactivity after influenza vaccination. We have found that IL-6 and IL-2 receptor levels were statistically significantly elevated (98.8 +/- 39 pg/ml and 1557 +/- 544 U/ml, respectively) in serum of haemodialysed patients. The fact that increased immune complexes statistically correlated with soluble IL-2 receptor levels (p < 0.01) was very interesting for us. In order to study the immunological response after vaccination, 10 patients have been investigated after influenza vaccination. Plasma samples were collected before, as well as 1 and 4 weeks after vaccine administration. Antibody titres measured by haemagglutinin inhibition showed decreased antibody levels in haemodialysed patients. We conclude that the interleukin disturbance and the elevated interleukin-2 receptor levels together with the presence of circulating immune complexes can influence in some way the immune response of haemodialysed patients.