Alterations in the rabbit lymphoid tissue after bendiocarb administration

Various pesticides have immuno-suppressive effects, and thus the organisms become responsive to viral, bacterial and parasitic diseases and neoplasm. The aim of the study was to observe the structure of the small intestine (height of enterocytes and crypts), mucosal lymphoid tissue (Payer's patches, lymphocytes in lamina propria) and a lymph node after administration of bendiocarb (2,2-dimethyl-1,3-benzodioxol-4-yl-methylcarbamate) on days 3, 10, 20, 30 and 60 of the experiment. The height of the observed enterocytes showed an increasing tendency. On days 20, 30 and 60 we also observed an increase in diameter of crypts located in intestinal epithelium. The number of cells in lamina propria mucosae was significantly reduced on days 20 and 30 after administration of bendiocarb. Observations of the lymph node showed that on days 10 and 20 there was a significant increase in relative volume of medulla at the expense of the relative volume of the cortex and a decrease in the number of lymphocytes. However, we recorded an increase in diameter of lymphocytes. The intracellular parasite Toxoplasma gondii (T. gondii) belongs to the most common pathogenic parasites in the world and it can cause serious health complications in pregnant and immunodeficient individuals. DNA isolation, standard polymerase chain reaction (PCR) and visualization in a 2.5 % agarose gel, the presence of DNA T. gondii was detected in no examined rabbit brain samples. Using real time PCR T. gondii DNA was detected and quantified in the three rabbit brain samples (10 %).     

Developmental exposure to diuron causes splenotoxicity in male Sprague-Dawley rat pups

This study investigated whether perinatal exposure to diuron [3-(3,4-dichlorophenyl)-1-1-dimethylurea] might exert adverse effects on rat lymphoid organs. Pregnant Sprague-Dawley (SD) rats were exposed to diuron at 500, 750 or 1250 ppm in the diet from gestational days (GD) 12–21 and during lactation. At postnatal day (PND) 42, male pups were euthanized and thymus, spleen, mesenteric lymph node and femur were collected for histopathological analysis. Food consumption and body weight gain were significantly reduced in dams exposed to 1250 ppm during gestation period. Also, Diuron at 750 and 1250 ppm produced: (1) increased relative spleen weight associated histologically with severe congestion in red pulp, (2) enhanced extramedullary hematopoiesis and hemosiderosis as well as (3) depletion of lymphoid follicles in white pulp. Flow cytometric analysis revealed a significant reduction in B lymphocytes (CD45RA+) in male pups but T lymphocytes (CD4+, CD8+ and CD4+/CD8+) were not markedly affected. Thus, data suggest that Diuron-induced maternal toxicity in dams exposed to high dose and perinatal exposure to this herbicide produced spleen toxicity as evidenced by a reduction in B lymphocyte number in male SD pups.     

Developmental exposure to diuron causes splenotoxicity in male Sprague-Dawley rat pups

This study investigated whether perinatal exposure to diuron [3-(3,4-dichlorophenyl)-1-1-dimethylurea] might exert adverse effects on rat lymphoid organs. Pregnant Sprague-Dawley (SD) rats were exposed to diuron at 500, 750 or 1250 ppm in the diet from gestational days (GD) 12-21 and during lactation. At postnatal day (PND) 42, male pups were euthanized and thymus, spleen, mesenteric lymph node and femur were collected for histopathological analysis. Food consumption and body weight gain were significantly reduced in dams exposed to 1250 ppm during gestation period. Also, Diuron at 750 and 1250 ppm produced: (1) increased relative spleen weight associated histologically with severe congestion in red pulp, (2) enhanced extramedullary hematopoiesis and hemosiderosis as well as (3) depletion of lymphoid follicles in white pulp. Flow cytometric analysis revealed a significant reduction in B lymphocytes (CD45RA+) in male pups but T lymphocytes (CD4+, CD8+ and CD4+/CD8+) were not markedly affected. Thus, data suggest that Diuron-induced maternal toxicity in dams exposed to high dose and perinatal exposure to this herbicide produced spleen toxicity as evidenced by a reduction in B lymphocyte number in male SD pups.     

Ultrastructural changes in the rabbit liver induced by carbamate insecticide bendiocarb

Carbamates (CB) are used as insecticides and some of them have been registered as human drugs. The mechanism of CB poisoning involves reversible inhibition of acetylcholine esterase. In the present study, we investigated changes in liver ultrastructure in rabbits (Oryctolagus cuniculus) which were administered bendiocarb for 3, 10, 20, and 30 days. Rabbits in all experimental groups received capsules of bendiocarb (96% Bendiocarb, Bayer, Germany) per os daily at a dose of 5 mg/kg of body weight, and after day 11 received the same dose every 48 h. The observed changes were only moderate, focal, and the effect on the liver was not uniform. On the third day of the experiment, injured hepatocytes had dilated bile capillaries with reduced microvilli. There were no visible alterations in the intercellular contacts. Nuclei of these cells were irregular in shape. Many hepatocytes showed considerable increase in the number of peroxisomes. On day 10 of the experiment, the number of peroxisomes was reduced. Other changes, such as dilated rough endoplasmic reticulum and proliferation of smooth endoplasmic reticulum were observed on day 20. The number of lipid droplets in hepatocytes gradually increased. Usually they were present in low numbers, but on day 30 of the experiment their number increased significantly. They coalesced and formed a single lipid droplet which changed the shape of the nuclei. The results presented in this study indicate that both short and long-term administration of bendiocarb affects the liver ultrastructure. At the same time we also observed rapid onset of regeneration of the damaged tissue through activation of hepatocytes and oval cells.     

Bendiocarbamate induced structural alterations in rabbit thymus after experimental peroral administration

In this study histological structure of rabbit thymus after bendiocarbamate (2,3-isopropyledene-dioxyphenyl methylcarbamate) administration was studied. Bendiocarbamate was perorally administered for 90 days. At Day 3, 10, 20, 30, 60, 90 morphometric analysis was realized. Quantitative evaluation showed that in the control group thymus cortex forms 57.94 +/- 7.10% and medulla 35.94+/- 7.38%. In almost all experimental groups significantly higher relative volume of cortex and lower relative volume of medulla was detected. Detail morphometric analysis found that the number of thymocytes per constant area and the diameter of tymocytes was decresed after bendiocarbamate administration. The number and diameter of reticular cells was not affected. Results of this study suggest negative effect of bendiocarbamate on the formation of thymus structures.     

Bendiocarbamate induced structural alterations in rabbit thymus after experimental peroral administration

In this study histological structure of rabbit thymus after bendiocarbamate (2,3–isopropyledene–dioxyphenyl methylcarbamate) administration was studied. Bendiocarbamate was perorally administered for 90 days. At Day 3, 10, 20, 30, 60, 90 morphometric analysis was realized. Quantitative evaluation showed that in the control group thymus cortex forms 57.94 ± 7.10% and medulla 35.94± 7.38%. In almost all experimental groups significantly higher relative volume of cortex and lower relative volume of medulla was detected. Detail morphometric analysis found that the number of thymocytes per constant area and the diameter of tymocytes was decresed after bendiocarbamate administration. The number and diameter of reticular cells was not affected. Results of this study suggest negative effect of bendiocarbamate on the formation of thymus structures.     

Bendiocarb effect on liver and central nervous system in the chick embryo

The aim of the study was to investigate toxicity of bendiocarb (2, 3-isopropyledene-dioxyphenyl methylcarbamate) to organs of chicken embryo. The toxic action of bendiocarb was observed on liver and central nervous system (CNS). Bendiocarb was administered to chicken embryos at embryonic day (ED) 3 in a dose 500 μ g/egg and 10 ED (800 μ g/egg). The observations showed no macroscopic or microscopic changes in the liver and CNS with either dose or day of incubation when the bendiocarb was administered. The liver and CNS were also investigated for caspase activity in relation to application of bendiocarb and no differences in the number of cells with caspase immunopositivity were observed in comparison with the control. The results obtained indicate that bendiocarb administered in the respective doses showed no toxicity to investigated organs. Furthermore, both at the early (3 ED) and the later (10 ED) stages of development no increase in numbers of apoptotic cells in chicken embryos was observed.     

Histopathological lesions in the body organs of cat-fish (Heteropneustes fossilis) following mercury intoxication

Light microscopic study of different body organs of cat-fish following exposure to HgCl2 0.2 mg/L in water for 30 days revealed that focal degeneration of liver cells and disorganization of hepatic cords occurred at places. Furthermore, centrilobular atrophy and compensatory hypertrophy of some hepatic cells were also observed. In the kidneys disintegration of renal epithelium along with displacement of nuclei, shrinkage of glomeruli, breakdown of Bowman's capsule and heavy infiltration by inflammatory cells were observed. The histopathological changes noted in the intestine included degeneration of lining epithelium, and diminution of goblet cells. Microscopic section of ovaries exhibited reduction of ooplasm leading to formation of atypical oocytes. An increase in the occurrence of atretic oocytes and interfolicular spaces was also discernible. No histopathological lesions could be detected in testes of male fish probably because of the difference in the maturity of the control and experimental groups. The pathomorphological alterations in relation to mercury toxicity in spleen were associated with the disorganization of the splenic cords resulting in the displacement of lymphatic tissue cells within the substance of splenic pulp. Marked depletion of the red pulp was noticeable.     

Chromosomal aberrations in ovine lymphocytes exposed in vitro to tolylfluanid

Chromosomal aberrations have been used as important cytogenetic biomarkers to study the mutagenic effects of different chemicals in vivo and in vitro. Chromosomal aberrations were evaluated in cultures of sheep lymphocytes in vitro exposed to the fungicide tolylfluanid. Lymphocyte cultures from three donors were exposed to four different concentrations of fungicide (1.10(-4) M(.)L; 1.10(-5) M(.)L; 1.10(-6) M(.)L; 1 × 10(-7) M(.)L). Chromosomal analysis showed a significant (P = 0.018 and 0.038 respectively, Anova test, P < 0.05, Tukey test) increase in the frequency of aberrant cells (ABC) in cultures treated with the highest negative experimental concentrations of tolylfluanid (1.10(-4) M(.)L; 1.10(-5) M(.)L) compared to control. Significantly increased numbers of chromatid breaks (7.67 ± 0.58% against 1.67 ± 2.08%, P = 0.009, Anova test, P < 0.05, Tukey test) and chromatid gaps (7.67 ± 1.15% against 2.67 ± 0.58%, P?= 0.003, Anova test, P < 0.05, Tukey test) were observed in ovine cultures treated with the highest experimental concentration of tolylfluanid (1.10(-4) M(.)L). Tolylfluanid induced also chromosomal exchanges (P = 0.038, and 0.016 respectively, Anova test, P < 0.05, Tukey test) in ovine cultures treated with the highest experimental concentrations of tolylfluanid (1.10(-4) M(.)L; 1.10(-5) M(.)L). The mitotic index has not shown any statistical differences between the various treatments and control groups. Our results suggest a significant genotoxic effect of tolylfluanid only at the highest concentration in sheep peripheral lymphocytes in vitro.     

Toxic effects of the herbicide 2,4-dichlorophenoxyacetic acid on lymphoid organs of the rat

We investigated the toxicity of the widely used herbicide dimethylammonium salt of 2,4-dichlorophenoxyacetic acid (DMA-2,4-D) on the lymphoid system of rats after a single dose oral administration using histological, cytochemical and molecular methods. DMA-2,4-D destroyed in a dose- and time-dependent manner the vascular integrity of the thymus and caused cell depletion in the white pulp of the spleen and in the cortex of the thymus, which was at least partly due to programmed cell death. DMA-2,4-D appeared to have hemolytic activity and caused intravascular hemolysis of erythrocytes. An increased hemosiderin content in macrophages of the spleen indicated phagocytosis of lysed erythrocytes. We conclude that acute DMA-2,4-D herbicide poisoning results in severe damage of the lymphatic organs thymus and spleen.     

Acute effects of 3,4-dichloroaniline on biomarkers and spleen histology of the common goby Pomatoschistus microps

The aromatic amine 3,4-dichloroaniline (DCA) is a model environmental contaminant, precursor for synthesis and degradation product of several herbicides, which is commonly found in European estuarine ecosystems. In this work, the possibility of using biochemical and histological markers to assess sub-lethal effects of DCA in natural populations of Pomatoschistus microps juveniles was investigated. Alterations on the activities of the enzymes acetylcholinesterase (AChE), lactate dehydrogenase (LDH) and glutathione S-transferase (GST) and histological alterations on spleen were investigated after 96 h of exposure to sublethal concentrations of DCA (0.50-1.49 mg/l). At the concentrations tested, DCA had no effect on AChE activity. LDH and GST activities were significant altered in treated animals when compared to control groups. As already described for mammals, DCA induced splenic histological alterations in P. microps, including expansion of red pulp and deposition of hemosiderin granules in a concentration-dependent manner. This suggests that DCA is a xenobiotic of concern in estuaries receiving agricultural effluents.     

Photomirex: a teratogenicity and tissue distribution study in the rabbit.

Adult New Zealand white does were intubated orally with single daily doses of 0, 5, or 10 mg of photomirex (8-monohydromirex) per kg body weight from the 6th through to the 18th day of gestation. Pregnancies were interrupted at term by cesarian section and fetuses removed and evaluated by following routine teratologic methods. Both maternal and fetal tissues were analyzed for residues of photomirex. None of the treated does showed any sign of toxicity. Except for a significant reduction in the mean fetal weight of the 10 mg/kg group all other parameters which evaluated fetal survival and fetal development were within the control range. Photomirex was found in all tissues examined. In the doe, the highest levels were found in fat followed by liver, kidney, spleen, heart, brain and blood. Photomirex was readily transferred across the placenta and accumulated in the fetus. However, in the fetus the highest levels were found in the heart, followed by liver, brain and blood. There were no teratogenic effects at the doses used in this study.     

Photomirex: A teratogenicity and tissue distribution study in the rabbit

Abstract

Adult New Zealand white does were intubated orally with single daily doses of 0, 5, or 10 mg of photomirex (8‐monohydromirex) per kg body weight from the 6th through to the 18th day of gestation. Pregnancies were interrupted at term by cesarian section and fetuses removed and evaluated by following routine teratologic methods. Both maternal and fetal tissues were analyzed for residues of photomirex. None of the treated does showed any sign of toxicity. Except for a significant reduction in the mean fetal weight of the 10 mg/kg group all other parameters which evaluated fetal survival and fetal development were within the control range. Photomirex was found in all tissues examined. In the doe, the highest levels were found in fat followed by liver, kidney, spleen, heart, brain and blood. Photomirex was readily transferred across the placenta and accumulated in the fetus. However, in the fetus the highest levels were found in the heart, followed by liver, brain and blood. There were no teratogenic effects at the doses used in this study.     

Evaluation of bendiocarb cytotoxicity in mammalian and insect cell cultures

There is an increasing need for rapid and easily interpreted in vitro assays to screen for possible cytotoxicity of pesticides. The objective of this study was to investigate the effect of the carbamate insecticide bendiocarb on mammalian and insect cell cultures. The cytotoxicity of this insecticide was evaluated by cell proliferation and cellular damage was assessed by evaluation of the cytopathic effect and lactate dehydrogenase (LDH) leakage. Cells of insect origin (Sf21) were the most sensitive to bendiocarb with significant (P < 0.01) suppression of their proliferative activity ranging from 10(-1)-10(-5) M. However, significant suppression of proliferative activity was also recorded in rat liver cells (WBF344; 10(-1)-10(-3) M; P < 0.01-0.05) and rabbit kidney cells (RK13; 10(-1) M; P < 0.01). In contrast with the proliferation activity of cells, a cytopathic effect based on cellular damage and LDH leakage into the medium was observed only at the highest concentration (10(-1) M) in RK 13 and WBF344 cells, but not in the Sf21 insect cell line. Our results indicate that bendiocarb exposure caused a cell-type dependent decrease in cell proliferation; however, cell damage and LDH leakage into the medium were not present or were strongly limited, dependent on the cell phenotype. Cell proliferation was shown as a sensitive indicator for evaluation of the cytotoxic effect of bendiocarb in vitro; on the other hand, microscopic signs of cellular damage and LDH leakage were insufficient in vitro markers.     

UDS-test with freon 11 (R-11)

Trichlorofluoromethane, in concentrations of 80, 400, 2 000, 10 000 and 50 000 ppm, was administered to rats of both sexes (Sprague Dawley) by inhalation exposure. 2 000 ppm in air (= 11 200 mg/m³) amount to twice the MAK value of 1 000 ppm. At exposure times of 4 hours this corresponds to the MAK value defined for an 8 hour workday. Unscheduled DNA synthesis (UDS) was measured in single-cell suspensions of hepatocytes, pulmonary epithelial cells and lymphocytes of the spleen, respectively. In the pulmonary cells concentrations of 2 000, 10 000 and 50 000 ppm of freon 11 lead to a significantly increased mean silver grain count compared to a negative control group. In spleen and liver cells increasing concentrations of R 11 tend to increase the incorporation of thymidine into the DNA of the cells. These changes of the extent of unscheduled DNA synthesis can, however, not be statistically verified.     

Role of vitamin A in the haematotoxicity of hexachlorocyclohexane (HCH) in the rat.

The haematotoxicity of technical hexachlorocyclohexane (HCH) (1000 ppm) was investigated in male albino rats fed with diet free of vitamin A or containing vitamin A at 2000 or 10(5) I.U./kg. Assessment of HCH-induced haematotoxicity at the end of the 7 weeks feeding period was done on the basis of haemoglobin content, total count of red blood cells and white blood cells and the differential counts of the white blood cells as well as by parameters such as packed cell volume, mean corpuscular volume, mean corpuscular haemoglobin, mean corpuscular haemoglobin content, prothrombin time and clotting time. In the rats fed with vitamin A-free diet containing HCH, significant reductions were noticed in the total white blood cells count, clotting time and prothrombin time indicating severe haematotoxicity. Differential count of the white blood cells of these rats revealed a non-significant reduction in the lymphocyte count. The only indication of haematotoxicity caused by hexachlorocyclohexane in the vitamin A supplemented rats was a slight but statistically significant reduction of the total count of white blood cells. These results demonstrate that the haematotoxicity of hexachlorocyclohexane in the rats is enhanced by vitamin A-deficiency and its supplementation particularly in excess but not at hypervitaminotic level is protective against the toxicity.     

Cytogenetic changes in subjects occupationally exposed to benzene

Humans are exposed to benzene from various occupational and environmental sources. The genotoxic effects of benzene were assessed in peripheral blood lymphocytes of 36 workers employed in the shoe industry for a period extending from seven months to over 30 years. Chromosomal aberrations and sister chromatide exchanges were used as indicators of genotoxic effects. The incidence of dicentric chromosomes in the exposed group was significantly higher than in the control group (P < 0.05). No significant increase was detected between the working period in the exposed group and chromosomal aberrations. Sister chromatide exchange (SCE) frequency was not significantly increased in the exposed group.     

Mixture effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin and polychlorinated biphenyl congeners in rats

Concern of the toxic effects and bioaccumulation of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and polychlorinated biphenyls in the environment continues to be a focus of research in persistent organochlorine contaminants. Groups of five adult female S.D. rats were administered by gavage 0, 2.5, 25, 250 or 1000 ng TCDD/kg body weight/day or TCDD in combination with a mixture of PCB congeners (PCBs) at 2 or 20 microg/kg b.w./day for a period of 28 days. Growth suppression, increased absolute and relative liver weights, and decreased thymic weight were observed in either the 1000 ng TCDD group alone, or the groups receiving a mixture of 1000 ng TCDD + 2 microg PCBs. The TCDD induced increases in liver and thymic weights were not altered by co-administration with PCBs, however, growth suppression appeared to be more pronounced in the group receiving 1000 ng TCDD + 2 microg PCBs than with TCDD alone. Treatment with TCDD at 250 ng and 1000 ng/kg resulted in a significant increase in hepatic microsomal methoxy resorufin-O-demethylase and ethoxy resorufin-O-deethylase activities which were antagonized by co-administration with PCBs. Similarly, effects of 250 ng TCDD on serum cholesterol and liver UDP glucuronosyl transferase activity and ascorbic acid were significantly reduced by co-administration with 20 microg PCBs. Other biochemical effects elicited by treatment with 1000 ng TCDD, but not affected by co-administration with PCBs include the following: increased serum albumin, decreased liver vitamin A, and increased kidney vitamin A and liver microsomal glutathione-S-transferase activity. While decreased hemoglobin, platelet, packed cell volume and red cell indices were observed in TCDD treated rats, no interactive effects were seen. The above results indicate that the mixture effects of PCBs and TCDD may be additive or antagonistic depending on the dose level and endpoints measured. For the purpose of predicting mixture effects, knowledge of mechanisms of action and toxicokinetics is required.     

Ozone differentially affects physiological and biochemical responses of two clover species; Trifolium repens and Trifolium pratense

The effect of acute ozone exposure (150 ppb for 3 h) on two clover species, white clover (Trifolium repens L.) and red clover (Trifolium pratense L.) was investigated through the analysis of 10 different physiological and biochemical parameters. Twenty-four hours after fumigation, visible symptoms of injury on leaves were observed only in red clover, but from the biochemical point of view, both species revealed significant ozone-induced modifications. A decrease in the photosynthetic efficiency as well as an increase in the de-epoxidation index and a decrease in the redox state of ascorbate were detected only in T. pratense leaves; no significant change in pigment content was found in either of the two species. On the other hand, both white and red clover showed, although to different extents, significant decreases in the activities of the antioxidant enzymes peroxidase and ascorbate peroxidase. Multivariate statistical analysis revealed not only that ozone affects both species, but also that they differentially respond to the pollutant, confirming the higher sensitivity of Trifolium pratense to ozone exposure.     

Toxicological assessment of chlorinated diphenyl ethers in the rat, Part II

Chlorinated diphenyl ethers (CDE's) are environmental contaminants that have been found in Great Lakes fish. Because of the paucity of toxicity data and potential for human exposure, the present short-term study was conducted to assess their potential toxic effects. Groups of 10 male and 10 female rats were administered the three CDE congeners (2,2',4,4',5-pentachlorodiphenyl ether (PCDE), 2,2',4,4',5,5'-hexachlorodiphenyl ether (HCDE), 2,2',3,4,4',6,6'-heptachlorodiphenyl ether (HPCDE] in diets at levels of 0.5, 5.0, 50 or 500 ppm for a period of 4 weeks. Decreased food consumption was observed with male and female rats fed the diet containing 500 ppm HPCDE. Treatment with the three isomers at the highest dose level produced an increase in liver weight in both sexes. While administration of PCDE produced an increase in hepatic aminopyrine demethylase activity, HCDE caused a significant increase in aminopyrine demethylase, aniline hydroxylase and ethoxyresorufin de-ethylase activities. HPCDE caused a significant increase in ethoxyresorufin de-ethylase activity. HPCDE at the highest dose level also caused a significant reduction in circulating lymphocytes in male rats. The 3 CDE's produced mild and adaptative histological changes in the liver and thyroid, but only HPCDE elicited mild changes in the thymus, bone marrow, and spleen. The above data indicate that HPCDE is immunosuppressive and that all three CDE isomers are considered to be moderately toxic in rats. The no-observable effects levels appear to be between 5-50 ppm in diet (0.36-3.0 mg/kg b.w.) for the three CDE's.