S. Teodorova

A comparative analysis of the heavy metal loading of small mammals in different regions of Bulgaria II: chromosomal aberrations and blood pathology.

Heavy metal content was monitored in small mammals inhabiting mountain ecosystems and two industrial polluted regions in Bulgaria. Rodents (Microtus arvalis, M. rossiaemeridionalis, Clethrionomys glareolus, Pitymys subterraneus, Chionomys nivalis, Apodemus flavicollis, A. sylvaticus, and Mus macedonicus) were used as zoomonitors. Pathological changes in chromosome status, hematological indices, and blood cell morphology were analyzed in the context of heavy metal bioaccumulation. Significant correlations were obtained between the heavy metal load of zoomonitors and the frequency of chromosomal aberrations and pathological changes in erythrocytes (mainly micronuclei and basophilic granulations). It is suggested that mercury is a strong damaging factor for chromosomes and red blood cell apparatus.

Bioaccumulation and damaging action of polymetal industrial dust on laboratory mice Mus musculus alba: I. Analysis of Zn, Cu, Pb, and Cd disposition and mathematical model for Zn and Cd bioaccumulations☆

The concentrations of Zn, Cu, Pb, and Cd in the liver, kidneys, spleen, bones, and carcass of laboratory mice BALB/cy were observed in toxicological experiments. Polymetal industrial dust containing these metals was given to experimental animals at 1% concentration mixed with conventional animal food. Samples for analyses were taken on Days 15, 40, 60, 90, and 120 posttreatment. The experimental data clearly support the established antagonistic interactions among cadmium, zinc, copper, and lead. A mathematical model was proposed to study the main tendencies of heavy metal bioaccumulation under conditions of metal interaction and excessive exposure. The experimental results were assessed on the basis of the model. A rate constant of renal excretion greater than that of hepatic excretion was obtained, which agrees with the observed inversion of cadmium kidney/liver ratio in the conditions of very high exposure.

Bioaccumulation and damaging action of polymetal industrial dust on laboratory mice Mus musculus alba II. Genetic, cell, and metabolic disturbances☆

An ecologo-toxicological experiment was carried out with laboratory mice Mus musculus alba of the inbred line BALB/c. The experimental animals (male and female) were exposed for 120 days to polymetal industrial dust containing zinc, copper, lead, and cadmium, which was mixed with conventional animal food. Chromosome aberration frequency and pathological changes in hematological indices, oxygen consumption, body temperature, and body weight were studied in the context of heavy metal bioaccumulation and interactions. Samples for analyses were taken on days 15, 40, 60, and 90. An increased frequency of chromosome aberrations (up to 22%), lead-induced anemia, and significant decreases in body temperature were observed. A strong correlation between hemoglobin content and oxygen consumption (O2/g h) was established. An increase in hematocrit, accompanied by a loss of body weight after day 60, suggests dehydration resulting from lead and cadmium poisoning.

Modified Natural Clinoptilolite Detoxifies Small Mammal’s Organism Loaded with Lead I. Lead Disposition and Kinetic Model for Lead Bioaccumulation

Zeolites, especially clinoptilolites, have wide application in removing heavy metals from different solutions and wastewater. The detoxification capacity of the clinoptilolite sorbent KLS–10-MA, a modified natural Bulgarian zeolite, applied as a food supplement in conditions of an ecotoxicological experiment with conventional food and lead was demonstrated for the first time. Laboratory mice, inbred imprinting control region strain, were used in a 90-day ecotoxicological experiment. Animals were divided into four experimental groups. Lead bioaccumulations in exposed and non-supplemented/supplemented with KLS–10-MA animals were compared. As additional control, healthy animals non-exposed to Pb were fed with conventional forage mixed with 12.5% KLS–10-MA. The dietary inclusion of the sorbent reduced Pb concentrations in exposed and supplemented mice by 84%, 89%, 91%, 77%, and 88% in carcass, liver, kidneys, bones, and feces, respectively. A mathematical model was proposed to outline the common trends of bone Pb bioaccumulation in exposed and non-supplemented/supplemented animals. Characteristic parameters of the kinetics of Pb concentrations were determined. Based on the model, the coefficient of absorption of Pb by gastrointestinal mucosa in the supplemented mice was found—η = 3.53% (versus η = 15% in non-supplemented ones). The present study clearly indicates that there is a realistic perspective to create a new drug based on modified natural clinoptilolites in cases of chronic heavy metal intoxication, without negatively affecting the environment.

A comparative analysis of the heavy metal loading of small mammals in different regions of Bulgaria: I: monitoring points and bioaccumulation features

Data on liver and body copper, zinc, lead, and cadmium content of small mammals (rodents and insectivorous) were collected and analyzed. Data comparisons were performed in two aspects: (1) points and years of monitoring; (2) monitor species bioaccumulations. Specific bioaccumulation features were observed in some of the monitor species. A method for comparative evaluation of heavy metal loads in the different species is proposed using data for liver and body contamination. The loads of Clethrionomys glareolus and Apodemus flavicollis were compared, and the data are in agreement with data from other authors in Central Europe. A correlation between heavy metal content in the food and liver of snow vole was established. The data demonstrate that two of the regions investigated in Rila Mountain National Park could be assumed to be background locations. Some possible reasons for the heavy metal contamination of the low-altitude region in Rila are discussed. Not very significant pollution was observed around industrial facilities. Correlations between heavy metal levels in zoomonitors and meteorological factors were established.

Effect of selenium and Ascaridia galli infection on antioxidant biomarkers in broiler chickens: a mathematical model for parasite reduction and host growth

The activity of selenium-dependent glutathione peroxidase (GPX), liver concentration of vitamin E, and plasma and liver selenium levels were used for estimation of the antioxidant status of broiler chickens infected with Ascaridia galli. These biomarkers were recorded in an experiment covering 70 days p.i. At the same time the establishment rate of A. galli in chicken intestines, gain in the host body weight and chicken survival were studied. Broiler chickens (Cobb hybrids) were infected with 1450 embryonated A. galli eggs and treated with Sel-plex. A mathematical model was applied to determine the rate of nematode reduction and the relative rate of gain of host body weight, which are essential kinetic parameters of parasite-host interaction. The activity of GPX increased with both elevated selenium and reduced infection levels. The concentrations of selenium and vitamin E, and the GPX activity in the infected chickens demonstrated a similar pattern of change with time after day 30 p.i. The supplementation of the broilers with dietary selenium in the form of Sel-plex improved their antioxidant status. Increases by 29% in vitamin E concentration, 15% in GPX activity, and 22% in liver selenium concentration, respectively, were recorded in the infected and treated, compared to infected and untreated broilers.

Administration of Zn-Co-Mn basic salt to chickens with ascaridiosis. II. Sex ratio and microelement levels in Ascaridia galli and in treated and untreated chickens.

Hisex chickens were infected with 1,450 embryonated Ascaridia galli eggs and treated with a new synthesized basic mixed salt (ZnxCoyMn1-x-y).(OH)6SO4.2H2O). The worm burden was determined and sex ratios for A. galli of M:F=1.4 and M:F=2 in untreated and treated chickens, respectively, were found. A decrease in the mean establishment rate of A. galli in treated chickens was observed. The levels of zinc, cobalt and manganese were determined in liver and muscle of the host and in male and female A. galli. The survival of the chickens and gain in body weight were improved, and the restoration of microelement content was observed by treatment with the salt. A positive effect of the basic Zn-Co-Mn salt was also observed in the nematode microelement levels. Significant differences were found between the levels of zinc, cobalt and manganese in male and female A. galli.

The effect of cobalt compounds on uninfected and Ascaridia galli-infected chickens: a kinetic model for Ascaridia galli populations and chicken growth.

The effect of dietary cobalt from three different sources on uninfected and Ascaridia galli-infected Hisex chickens, has been studied. The chicken diet was supplemented with 0.06 Co2+ kg-1 food either in the form of two glycine-cobalt compounds or mixed zinc-cobalt basic salt. An excess of dietary cobalt in small doses increases the gain of body weight and decreases host mortality. A greater bioefficiency of cobalt was established in infected chickens. A mathematical model has been used to provide a quantitative interpretation of the observed results. The model solutions of the kinetics of worm numbers and body weight are in a good agreement with experimental data. The model is valid for different degrees of A. galli infections and for treatment with different trace elements. The value of the kinetic parameter, regarded as a phenomenological constant of the host immune response, depends on the degree of infection.

Effects of glycine-metal compounds on Ascaridia galli-infected chickens expressed by a kinetic model

The biogenic elements zinc, manganese and cobalt are essential for metabolic processes in animals. Compounds of nGly.Me2+A. mH2O (Me2+=Zn2+, Mn2+, Co2+; A=Cl(-), SO4(2-), n=1, 2; m=2, 5), as supplements in the diet, were used separately on different experimental groups of male Hisex chickens to correct the mineral deficiency caused by Ascaridia galli infections. An amelioration of body weight gain, reduction of mortality and restoration of trace element levels were estimated in infected chickens. A mathematical model has been proposed for A. galli population kinetics in chickens, taking into account the stimulating effect of these elements on the nematodes. The model parameters are considered as phenomenological constants of the host-parasite system. An agreement with experimental data is observed using, for the parameters psi, alpha, micro and micros, values equal to those calculated in previously investigated A. galli-chicken systems. For parameter nu (immunological constant) the same value was obtained as in a previous experiment with high infection. This model is likely to be suitable for a range of host-nematode systems, including varying degrees of infection and treatment with different trace elements.

Content of some microelements in chickens with ascaridiasis under combined drug treatment

The content of zinc, cobalt, and selenium in the intenstinal wall of Leghorn chickens infected withAscaridia galli was determined by nondestructive neutron-activation analysis. A comparison was made between the infected animals that were treated with Piperathrine and those that were given microelements or those that did not receive microelements. Age-dependent changes were found in the content of the microelements in the control groups. It is concluded that zinc, cobalt, and selenium are unevenly distributed in the intestinal tissues, with a dominating density of selenium occurring in the epithelial layer of the intestinal mucosa.