The effect of exposure to chlorfenvinphos on lipid metabolism and apoptotic and necrotic cells death in the brain of rats.

This study investigated the influence of chlorfenvinphos (0.3 mg/kg bw/24 h corresponding to 0.02 LD50; orally by gastric gavage for 14 and 28 days) on lipid metabolism, and apoptotic and necrotic cells death in the brain of rats as the possible mechanism of neurotoxic action of organophosphate (OP) pesticides at low exposure. Total cholesterol (TCh), triglycerides (TG), phospholipids (PL), and free fatty acids (FFA) were determined and apoptotic, necrotic, and living cells were quantified in the brain. Moreover, the serum and brain acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) were assayed as biomarkers of neurotoxicity. The treatment with chlorfenvinphos increased (duration dependently) the concentrations of TCh and TG and the ratio of TCh/PL, and decreased PL concentration. The prevalence of apoptotic and necrotic cells increased and that of the living brain cells depressed (by 10%) already after 14 days of the exposure. The brain activities of AChE and BChE decreased by 12% and 15%, and by 18% and 25% after 14 and 28 days, respectively, whereas the serum activities of these enzymes were inhibited (by 24% and 18%, respectively) only after the longer treatment. The changes in lipid metabolism and distribution of the living, apoptotic, and necrotic brain cells correlated with AChE and BChE activities in the serum and brain. The results show that chlorfenvinphos may disturb lipid metabolism and induce apoptosis and necrosis in the brain even at the exposure not affecting the serum activities of cholinesterases, and causing only moderate inhibition of their brain activities. Based on the findings it can be concluded that low repeated exposure to OP pesticides may influence the nervous system through disrupting the lipid profile of the nervous tissue and decreasing the number of the nervous cells.

Oxidative damage to proteins and DNA in rats exposed to cadmium and/or ethanol.

The study was aimed to estimate whether rat's exposure to cadmium (Cd; 50mg/l in drinking water for 12 weeks) and/or ethanol (EtOH; 5g/kg b.wt./24h p.o. for 12 weeks), noted by us to induce oxidative stress and stimulate lipid peroxidation, can cause oxidative damage to proteins and DNA, and whether and to what extent the effects of co-exposure differ from those observed under the treatment with each substance alone. Protein carbonyl groups (PC) and protein thiol groups (PSH) in the serum, liver and kidney, as markers of oxidative protein damage, and 8-hydroxy-2'-deoxyguanosine (8-OHdG) in the serum, as a marker of DNA oxidation, were determined. The exposure to Cd or/and EtOH led to oxidative protein damage (increased PC and decreased PSH concentrations in the serum and/or liver), and to DNA oxidation (increased 8-OHdG concentration in the serum). The effects were more advanced at the co-exposure than at the treatment with each substance alone. The more serious damage to proteins and DNA at the co-exposure to Cd and EtOH seems to be the effect of independent action of both xenobiotics. The results of the present paper together with our recent findings in the same rats seem to indicate that at co-exposure to Cd and EtOH proteins and DNA may be more vulnerable to oxidation than lipids. The paper is the first report suggesting that excessive EtOH consumption during exposure to Cd may increase the risk of health damage via enhancing protein and DNA oxidation.

Enhanced zinc consumption prevents cadmium-induced alterations in lipid metabolism in male rats.

It has been investigated, based on a rat model of human exposure to cadmium (Cd), whether zinc (Zn) supplementation may prevent Cd-induced alterations in lipid metabolism. For this purpose, the concentrations of free fatty acids (FFA), phospholipids (PL), triglycerides (TG), total cholesterol (TCh), and high and low density lipoprotein cholesterol (HDL and LDL, respectively) as well as the concentrations of chosen indices of lipid peroxidation such as lipid peroxides (LPO), F2-isoprostane (F2-IsoP) and oxidized LDL (oxLDL) were estimated in the serum of male Wistar rats administered Cd (5 or 50mg/l) or/and Zn (30 or 60mg/l) in drinking water for 6 months. The exposure to 5 and 50mg Cd/l resulted in marked alterations in the lipid status reflected in increased concentrations of FFA, TCh, LDL, LPO, F2-IsoP and oxLDL, and decreased concentrations of PL and HDL in the serum. The concentrations of LDL, LPO, F2-IsoP and oxLDL were more markedly enhanced at the higher Cd dosage. The supplementation with Zn during the exposure to 5 and 50mg Cd/l entirely prevented all the Cd-induced changes in the serum concentrations of the estimated lipid compounds and indices of lipid peroxidation, except for the F2-IsoP for which Zn provided only partial protection. Based on the results it can be concluded that Zn supplementation during exposure to Cd may have a protective effect on lipid metabolism consisting in its ability to prevent hyperlipidemia, including especially hypercholesterolemia, and to protect from lipid peroxidation. The findings seem to suggest that enhanced dietary Zn intake during Cd exposure, via preventing alterations in the body status of lipids may, at least partly, protect against some effects of Cd toxicity, including oxidative damage to the cellular membranes and atherogenic action. The paper is the first report suggesting protective impact of Zn against proatherogenic Cd action on experimental model of chronic moderate and relatively high human exposure to this toxic metal.

Beneficial effect of zinc supplementation on biomechanical properties of femoral distal end and femoral diaphysis of male rats chronically exposed to cadmium.

The present study was aimed at estimate, based on the rat model of human moderate and relatively high chronic exposure to cadmium (Cd), whether zinc (Zn) supplementation may prevent Cd-induced weakening in the bone biomechanical properties. For this purpose, male Wistar rats were administered Cd (5 or 50 mg/l) or/and Zn (30 or 60 mg/l) in drinking water for 6 and 12 months. Bone mineral density (BMD) and biomechanical properties (yield load, ultimate load, post-yield load, displacement at yield and at ultimate, stiffness, work to fracture, yield stress, ultimate stress and Young modulus of elasticity) of the femoral distal end and femoral diaphysis were examined. Biomechanical properties of the distal femur were estimated in a compression test, whereas those of the femoral diaphysis -- in a three-point bending test. Exposure to Cd, in a dose and duration dependent manner, decreased the BMD and weakened the biomechanical properties of the femur at its distal end and diaphysis. Zn supplementation during Cd exposure partly, but importantly, prevented the weakening in the bone biomechanical properties. The favorable Zn influence seemed to result from an independent action of this bioelement and its interaction with Cd. However, Zn supply at the exposure to Cd had no statistically significant influence on the BMD at the distal end and diaphysis of the femur. The results of the present paper suggest that Zn supplementation during exposure to Cd may have a protective influence on the bone tissue biomechanical properties, and in this way it can, at least partly, decrease the risk of bone fractures. The findings seem to indicate that enhanced dietary Zn intake may be beneficial for the skeleton in subjects chronically exposed to Cd.

Estimation of Polish cigarettes contamination with cadmium and lead, and exposure to these metals via smoking.

To estimate exposure to cadmium (Cd) and lead (Pb) through cigarette smoking, the concentrations of both metals in the blood or/and urine of smokers (20 cigarettes or more per day for 10 years or longer) and their non-smoking counterparts inhabiting an environmentally unpolluted area (Bialystok, Poland) were evaluated, as well as Cd and Pb contents in the cigarette brands (produced in Poland) smoked by the participants, including intact cigarettes, pre-smoking (tobacco, paper and filter) and post-smoking (butt, ash and smoke) cigarette components. Blood and urinary Cd concentrations in the smokers have been already reported by us to be 2-4 times higher than in the non-smokers (Galazyn-Sidorczuk et al. Polish Journal of Environmental Studies, 13 (Suppl.1):91-95, 2004). All the other measurements are the subject of the present paper. Pb concentration in the blood of the cigarette smokers (52.12 +/- 15.51 microg l(-1)) was higher by 29% than in the non-smokers (40.42 +/- 11.19 microg l(-1)). The mean Cd and Pb contents in the cigarettes were 0.6801 +/- 0.1765 and 0.6853 +/- 0.0746 microg per cigarette, respectively. Under cigarette burning, performed using a machine for self-acting burning, on average 33% of Cd and 11% of Pb present in the whole cigarette was released into the smoke. For Cd, unlike Pb, there was a high positive correlation between the metal content in cigarettes and tobacco and its release into the smoke. Moreover, the subjects smoking cigarettes containing the highest Cd amount had higher blood Cd concentration than smokers of other cigarette brands. The results give clear evidence that in the case of inhabitants of areas unpolluted with Cd and Pb habitual cigarette smoking, due to tobacco contamination, creates a serious source of chronic exposure to these metals, especially to Cd.

The Effect of N-nitrosodimethylamine on TRAIL and DR5 expression in human neutrophils--preliminary study.

The intracellular mechanisms of NDMA-induced apoptosis of neutrophils have not yet been fully understood. The aim of this study was to explain whether the TRAIL/DR5 system is implicated in NDMA-induced apoptosis of human neutrophils. The expression of TRAIL and DR5 was examined, as well as the secretion of sTRAIL and sDR5 by human neutrophils treated with NDMA confronted with intensity apoptosis of these cells. For comparative purposes similar examinations in autologous peripheral blood mononuclear cells (PBMC) were performed. Decreased expression and secretion of TRAIL and increased expression and secretion of DR5 associated with increased intensity of apoptosis of polymorphonuclear leukocytes (PMNs) suggest that NDMA-induced apoptosis in these cells may be depend on TRAIL/DR5 system. Autologous PBMCs no exerted that changes in the expression and secretion of TRAIL as well as in the intensity of apoptosis. However, the expression and secretion of DR5 by PBMCs were similar to those by PMNs. Differences above suggest that PMNs are more sensitive to unfavorable action of NDMA than PBMCs.

Effect of zinc supplementation on bone metabolism in male rats chronically exposed to cadmium.

The aim of the present study is to investigate, based on the rat model of moderate and relatively high human exposure to cadmium (Cd), whether zinc (Zn) supplementation may prevent Cd-induced disorders in bone metabolism. For this purpose, male Wistar rats received Cd (5 and 50mg/l) or/and Zn (30 and 60mg/l) in drinking water for 6 and 12 months. Bone densitometry and biochemical markers of bone turnover were used to assess the effects of Cd or/and Zn. Bone mineral content (BMC) and density (BMD) were measured in the femur. Serum osteocalcin (OC) and alkaline phosphatase in trabecular (bT-ALP) and cortical (bC-ALP) bone were determined as bone formation markers, and carboxy-terminal cross-linking telopeptides of type I collagen (CTX) in serum were measured as bone resorption marker. Serum concentration of calcium (Ca) and its renal handling, as well as Zn and Cd concentrations in the serum/blood, urine and femur were evaluated as well. The exposure to 5 and 50mg Cd/l (0.340+/-0.026 and 2.498+/-0.093mg Cd/kg body wt/24h, respectively), in a dose and duration dependent manner, affected bone turnover (inhibited bone formation and stimulated its resorption) and disturbed bone mineralization (decreased BMC, BMD and Zn concentration). Zn supply at the concentration of 30 and 60mg/l (1.904+/-0.123 and 3.699+/-0.213mg/kg body wt/24h, respectively) during Cd exposure influenced the Cd-induced disorders in bone metabolism. Zn administration to the Cd-exposed rats enhanced the bone ALP activity and prevented Cd-induced bone resorption, but had no statistically significant effect on BMC and BMD; however, mean values of the densitometric parameters in the rats receiving both Cd and Zn were higher than in those treated with Cd alone. Moreover, Zn supplementation at both levels of Cd exposure was found to prevent Cd accumulation in the femur and the Cd-induced decrease in bone Zn concentration. The results of the present study allow the conclusion that Zn supplementation during Cd exposure may partly protect from disorders in bone metabolism. The influence of Zn may be accompanied by its ability to prevent Cd-induced Zn deficiency and to decrease Cd accumulation in bone tissue. The findings seem to indicate that enhanced dietary intake of Zn in subjects chronically exposed to moderate and relatively high Cd levels may have a protective influence on the skeleton.

The influence of human neutrophils on N-nitrosodimethylamine (NDMA) synthesis.

N-nitrozodimethyloamine (NDMA) is a carcinogenic compound that can be formed in vivo. NDMA is synthesized from precursors-amines and nitrosating agents. Nitrosating agents are formed through the reaction of oxide, reactive oxygen species and nitric oxide (NO). Human neutrophils (PMN) are an important source of the most reactive oxygen species as well as of the nitric oxide. The increase in oxygen metabolism of PMN can lead to the increase nitrosating agent and nitroso-forms. Inflammatory process is associated with locally decreased pH that may favor nitrosation reaction. In the present study, we estimated the NDMA synthesis by LPS-stimulated PMN in the presence of the iNOS inhibitor--N-nitro-L-arginine methyl ester (L-NAME). In the nitrosation reaction dimethylamine (DMA) was used as substrat. The viability of the cells was measured by cytometric method. NDMA concentrations the culture media was measured by GCMS method. NO production was estimated by Griess's method. Expression of iNOS was determined by western blotting. Results obtained showed that DMA nitrosation is most effective in pH between 3-4.5. Nonstimulated PMN produced lower concentrations of NO than LPS-stimulated cells (1.27 microg/cm3 and 1.57 microg/cm3, respectively). In the culture of nonstimulated PMN supplemented with DMA, there was NDMA (mean--0.99 ng/cm3). In the culture of LPS-stimulated PMN in the presence of DMA, the concentration of NDMA was higher than in the culture of nonstimulated PMN (median--1.45 ng/cm3). In the supernatants of cells incubated without DMA and with DMA, LPS and L-NAME, no NDMA was detected. These results indicate that PMN can be one of sources of nitrosating agents and can play a role in endogenous NDMA synthesis. Stimulation of PMN can lead to the increase of NDMA concentration following the increase of NO production. Different pathological conditions associated with PMN activation as well as the decreased pH may favor endogenous NDMA synthesis.

Involvement of some low-molecular thiols in the peroxidative mechanisms of lead and ethanol action on rat liver and kidney.

The involvement of low-molecular thiols, such as reduced glutathione (GSH) and metallothionein (Mt), in the mechanisms of the peroxidative action of lead (Pb) and ethanol (EtOH) in liver and kidney was investigated on rats treated with 500 mg Pb/l (in drinking water) and 5 g EtOH/kg body wt./24h (p.o.), alone and in conjunction with each other for 12 weeks. Beside of GSH and Mt, concentration of total and non-protein SH groups (TSH and NPSH, respectively) in these organs as well as the blood activity of dehydratase of delta-aminolevulinic acid (delta-ALAD) and the urinary concentration of delta-aminolevulinic acid (delta-ALA) were determined. The exposure to Pb and EtOH alone and in conjunction with each other led to a decrease in the blood delta-ALAD activity and an increase in the urinary delta-ALA concentration, and these effects were more markedly advanced at co-exposure. In the liver and kidney of rats treated with Pb and/or EtOH, a decrease in concentrations of GSH and NPSH was noted, compared to control. However, in the Pb+EtOH group, only the liver concentrations of NPSH and GSH were lower also compared to the Pb and EtOH groups. The liver concentration of TSH decreased in the rats exposed to EtOH alone and in conjunction with Pb, whereas the kidney concentration of TSH decreased only at co-exposure to Pb and EtOH. Mt concentration was unchanged except for an increase in the liver in the Pb and Pb+EtOH groups. Two-way analysis of variance (ANOVA/MANOVA) revealed that the changes noted at the co-exposure to Pb and EtOH resulted from an independent action of the two xenobiotics as well as from their interactive action. Negative correlations noted between the liver and kidney concentrations of GSH and/or NPSH and recently reported malondialdehyde (MDA, an indicator of lipid peroxidation) concentration in both organs of those rats indicate the relationship between the content of SH groups and the intensity of the Pb and/or EtOH-induced lipid peroxidation. The results allow for the conclusion that the decrease in the liver and kidney concentrations of GSH and NPSH are involved in the mechanisms of the peroxidative action of Pb and EtOH alone and at co-exposure in these organs.

The effect of ethanol and nitric oxide on the N-nitrosodimethylamine formation in HepG2 cells overexpressing CYP2E1.

The influence of lipopolysaccharide (LPS) and the nitric oxide synthase (iNOS) inhibitor--N-nitro-L-arginine methyl ester (L-NAME)--on the formation of N-nitrosodimethylamine (NDMA) by HepG2 cells, engineered to overexpress CYP2E1, was assessed and compared with data from empty vector-transfected cells. HepG2 cells produced significant amounts of NDMA but its levels in the culture media of cells overexpressing CYP2E1 was significantly lower than in empty-vector transfected cells. LPS increased the formation of NDMA, the expression of the iNOS and the production of the nitric oxide (NO). On the other hand, L-NAME significantly decreased NDMA levels. The results above indicate that the synthesis of NDMA by HepG2 cells depends on NO production. Furthermore, ethanol did not affect iNOS expression but decreased NDMA levels in CYP2E1-transfected cells below the detection limit. It is probably caused by the increased N-nitrosodimethylamine metabolism. In conclusion, HepG2 cells' ability to synthesize NO with simultaneous CYP2E1 activation may lead to an increase of carcinogenic products of the NDMA metabolism.

Bone metabolism of male rats chronically exposed to cadmium.

Recently, based on a female rat model of human exposure, we have reported that low-level chronic exposure to cadmium (Cd) has an injurious effect on the skeleton. The purpose of the current study was to investigate whether the exposure may also affect bone metabolism in a male rat model and to estimate the gender-related differences in the bone effect of Cd. Young male Wistar rats received drinking water containing 0, 1, 5, or 50 mg Cd/l for 12 months. The bone effect of Cd was evaluated using bone densitometry and biochemical markers of bone turnover. Renal handling of calcium (Ca) and phosphate, and serum concentrations of vitamin D metabolites, calcitonin, and parathormone were estimated as well. At treatment with 1 mg Cd/l, corresponding to the low environmental exposure in non-Cd-polluted areas, the bone mineral content (BMC) and density (BMD) at the femur and lumbar spine (L1-L5) and the total skeleton BMD did not differ compared to control. However, from the 6th month of the exposure, the Z score BMD indicated osteopenia in some animals and after 12 months the bone resorption very clearly tended to an increase. The rats' exposure corresponding to human moderate (5 mg Cd/l) and especially relatively high (50 mg Cd/l) exposure dose- and duration-dependently disturbed the processes of bone turnover and bone mass accumulation leading to formation of less dense than normal bone tissue. The effects were accompanied by changes in the serum concentration of calciotropic hormones and disorders in Ca and phosphate metabolism. It can be concluded that low environmental exposure to Cd may be only a subtle risk factor for skeletal demineralization in men. The results together with our previous findings based on an analogous model using female rats give clear evidence that males are less vulnerable to the bone effects of Cd compared to females.

Weakness in the mechanical properties of the femurs of growing female rats exposed to cadmium.

The study assessed the effect of cadmium (Cd) intoxication on the risk of deformities and fractures of the growing bones of female rats, in order to model human exposure to this metal. For this purpose, bone mineral density and mechanical properties of the proximal and distal ends and diaphysis of the femur were investigated in female Wistar rats exposed to 1, 5 and 50 mg Cd/l in drinking water for 3, 6, 9 and 12 months after the onset of weaning. Daily Cd doses received from drinking water during the treatment period were in the following ranges: 0.059-0.219, 0.236-1.005 and 2.247-9.649 mg/kg body weight at 1, 5 and 50 mg Cd/l, respectively. Biomechanical properties of the femoral proximal and distal ends were evaluated in a compression test, and those of the femoral diaphysis in a cutting test, with loading perpendicular to the longitudinal axis of the bone in all tests. The mineralization and mechanical properties of the bone tissue at various locations on the femur were affected by exposure to Cd in a dose- and duration-dependent manner. Exposure to 1 mg Cd/l (corresponding to low human exposure) during skeletal development weakened the fracture strength of the femoral neck and the trabecular bone at the level of the distal end of the femur and affected the elastic properties of the cortical bone at the femoral diaphysis. At higher levels of Cd exposure, adverse effects were generally observed after a shorter exposure period than for 1 mg Cd/l, and were more advanced. The cadmium-induced weakening of the biomechanical properties of bone at particular sites on the femur correlated with the decreased bone mineralization. The results indicate that even a low exposure to Cd may affect the mineralization and biomechanical properties of growing bone, thus enhancing the risk of fracture.

Effect of low-level lifetime exposure to cadmium on calciotropic hormones in aged female rats.

The effect of low-level lifetime exposure to cadmium (Cd) on calciotropic hormones and the possible association between the Cd-induced disorders in bone metabolism and these hormones were investigated on a female rat model of human environmental exposure in areas unpolluted by this metal. For this purpose, the concentrations of 25-hydroxyvitamin D (25OHD), 1,25-dihydroxyvitamin D (1,25(OH)(2)D), calcitonin (CT) and parathormone (PTH) were measured in the serum of control and Cd-exposed (1 mg Cd/l in drinking water for 24 months) female rats. Calcium (Ca) and inorganic phosphorus (P(i)) serum concentrations, renal tubular reabsorption of Ca (TRCa) and phosphate (TRP) and the glomerular filtration rate (GFR) were estimated as well. Moreover, 1,25(OH)(2)D, metallothionein (MT) and Cd were determined in the kidney. The exposure to Cd led to a decrease in the serum concentrations of 25OHD and 1,25(OH)(2)D (by 50 and 31%, respectively) and the concentration of 1,25(OH)(2)D in the kidney mitochondrial fraction (by 55%). The serum concentrations of CT and PTH increased (5.2-fold and by 29%, respectively) and those of Ca and P(i) were unchanged, whereas the TRCa, TRP and GFR decreased due to the exposure to Cd. The results give evidence that the low lifetime exposure to Cd disturbs the metabolism of calciotropic hormones and damages the reabsorptive and filtrative function of the kidney in aged female rats. Numerous correlations noted between calciotropic hormones and the indices of kidney function, and indices of bone turnover and bone mineral status (bone mineral content and density) of these females indicate a relationship between these hormones and the kidney functional status and bone metabolism. The results of the present study together with our previous findings on the bone status in the experimental model allow for the conclusion that the low lifetime exposure to Cd by affecting the metabolism and proper function of calciotropic hormones may contribute to the advancement of bone damage at the elderly.

Weakness in the mechanical properties of the femur of growing female rats exposed to cadmium.

This study was aimed at assessing the effect of cadmium (Cd) intoxication on the risk of deformities and fractures of the growing bone on a female rat model of human exposure to this metal. For this purpose, bone mineral density (BMD) and mechanical properties of the proximal and distal ends and diaphysis of the femur were investigated in female Wistar rats exposed to 1, 5, and 50 mg Cd L(-1) in drinking water for 3, 6, 9, and 12 months since weaning. Daily Cd doses received from the drinking water during the treatment period were in the ranges 0.059-0.219, 0.236-1.005, and 2.247-9.649 mg kg(-1) body weight at 1, 5, and 50 mg Cd L(-1), respectively. Biomechanical properties of the femoral proximal and distal ends were evaluated in a compression test and those of the femoral diaphysis in a cutting test with loading perpendicular to the bone longitudinal axis in all tests. Cd dose- and exposure duration-dependently affected the mineralization and mechanical properties of the bone tissue at various locations of the femur. Exposure to 1 mg Cd L(-1) (corresponding to low human exposure) during skeletal development weakened the fracture strength of the femoral neck and of the trabecular bone at the level of the distal end of the femur and affected the elastic properties of the cortical bone at the femoral diaphysis. At the higher levels of Cd treatment, the adverse action generally occurred after shorter exposure than at 1 mg Cd L(-1) and was more seriously advanced. The Cd-induced weakening in the bone biomechanical properties at particular sites of the femur correlated with the decreased bone mineralization. The results indicate that even low exposure to Cd may affect the mineralization and biomechanical properties of growing bone, thus increasing the risk of fractures.

Effect of chronic exposure to cadmium on the mineral status and mechanical properties of lumbar spine of male rats.

The effect of cadmium (Cd) on the risk of vertebral damage was investigated on a male rat model of human exposure. Young Wistar rats were treated with Cd in drinking water at the concentration of 1, 5 or 50 mgCd/l for 12 months. Bone mineral density (BMD) of the lumbar spine (L1-L5), the rate of deformities and fractures, biomechanical properties (compression test) and the chemical composition of the fourth lumbar vertebral body (L4) were estimated. The exposure to 1 mgCd/l (corresponding to low environmental exposure in non-Cd-polluted areas) had no effect on the L4 composition, density and mechanical strength; in one animal only (10%) it was deformed. In the 5 mgCd/l group, the content of minerals (including calcium, zinc and phosphate) in the L4 and the displacement at ultimate decreased, whereas its ultimate strength and the L1-L5 BMD tended to decline. In most of the rats, the L4 was intact and there were no vertebral fractures. At 50 mgCd/l, the BMD of the L1-L5 and the content of minerals in the L4 (including calcium, magnesium, zinc, copper, iron and phosphate) were lower compared to control, and these changes were accompanied by a weakness in the L4 mechanical strength. The L4 was intact only in 30% of these rats; in other animals it was deformed (40%) or fractured (30%). The results allow for the conclusion that moderate environmental exposure to Cd (5 mgCd/l in the model applied) may enhance the risk of vertebral damage in men. These, together with our previous findings on an analogous female rat model, seem to indicate that males may be less vulnerable to the vertebral fractures due to exposure to Cd compared to females.

Disorders in bone metabolism of female rats chronically exposed to cadmium.

The effect of cadmium (Cd) on bone metabolism during skeletal development and maturity was investigated on a rat model of human exposure. Young female Wistar rats were exposed to 1, 5, or 50 mg Cd/l in drinking water for 3, 6, 9, and 12 months. Total bone mineral density (T-BMD), bone mineral content (BMC), density (BMD), and bone area at the femur and lumbar spine (L1-L5) were measured densitometrically. Alkaline phosphatase (ALP) and osteocalcin (OC) as bone formation markers, and carboxy-terminal cross-linking telopeptides of type I collagen (CTX) in bone (trabecular and cortical) or serum as bone resorption markers were measured. Renal calcium (Ca) handling and Cd body burden were evaluated as well. At the stage of intensive skeletal development (the first 6 months of the experiment), at all exposure levels, Cd inhibited the processes of bone formation and as a result disturbed the accumulation of bone mass leading to osteopenia (- 1 > Z score/T score BMD > -2.5) and at 5 and 50 mg Cd/l even to more advanced disorders in the BMD. Continuation of the exposure up to skeletal maturity led to high bone turnover with increased resorption enhancing the prevalence of osteopenia or the BMD values having the Z score/T score < -2.5. The results allow for the conclusion that chronic, even low-level exposure to Cd disturbs bone metabolism during skeletal development and maturity by affecting bone turnover most probably through a direct influence on bone formation and resorption, and indirectly via disorders in Ca metabolism. Our findings confirm the hypothesis that environmental exposure to Cd may be a risk factor for low BMD.

[Select parameters of renal function in smokers in correlation with the exposure to cadmium]. / Badania nad wplywem palenia na wybrane parametry biochemiczne funkcji nerek w powiazaniu z narazeniem na kadm.

Cigarette smoke contains about 4000 chemical substances, including toxic metals such as cadmium. Smoking of 20 cigarettes a day results in inhalation an average 3.6-6.0 microg of cadmium. Due to nephrotoxic action of some components of tobacco smoke, and especially cadmium, the present study was aimed to evaluate of chosen parameters of kidney status in cigarette smokers in connection with estimation of cadmium concentration. The study was conducted in eighty-nine health and unexposed occupationally to cadmium inhabitants of Bialystok, smoking and non-smoking men and women at age 35-50. The smokers consumed 20 and more cigarettes per day for longer period than 10 years. Blood and morning urine were collected for analysis. In the urine samples, cadmium concentration (by atomic absorption spectrometry) and cotinine concentration (by gas chromatography with mass spectrometry), as an indicator of exposure to cigarette smoke, were determined. The kidney status was evaluated based on the urinary activities of lysosomal enzyme N-acetyl-beta-D-glucosaminidase (NAG) and its isoenzyme B (by colourimetrical method modified by Zwierz et al.) and concentrations of creatinine and urea in the serum (using diagnostic laboratory tests by POCh). The percentage reabsorption of phosphates was evaluated as well (TRP). Cadmium concentration in the urine of smoking women and men was higher compared to non-smokers, but there was no correlation between cadmium and cotinine concentrations in urine. In the smoking women, the urinary activity of NAG and TRP were higher than in non-smoking ones. In smokers, the activities of NAG and NAG-B in men and the activity of NAG-B in women were in the range of values noted in non-smokers, however the frequency of appearance of NAG and NAG-B activities above the limit of detection was higher compared to non-smokers. Cigarette smoking had no influence on the serum concentrations of creatinine and urea in both men and women and TRP in men. The results of the analysis of the urinary NAG and NAG-B activities in conjunction with the frequency of their appearance allow concluding that cigarette smoke might lead to an occurrence of early changes in proximal tubules of men and women.

Activity of lysosomal exoglycosidases in submandibular glands of rats intoxicated by cadmium at doses related to human chronic environmental and occupational exposures.

Work in cadmium (Cd) smelter and smoking cigarettes damages teeth and oral mucosa which are protected by tissue and salivary glycoconjugates: glycoproteins, glycolipids, and proteoglycans. We worked out a rat model imitating human "environmental" and "occupational" exposure to cadmium using 5 mg Cd and 50 mg Cd/l in drinking water, respectively. In submandibulary glands of exposed to Cd rats, we found the time and dose dependent accumulation of Cd and simultanous decrease in activity of beta-N-acetylhexosaminidase (HEX). In homogenates of submandibulary glands of control rats, beta-N-acetylhexosaminidase showed the highest activity. The activities of alpha-mannosidase and beta-galactosidase were very low. None of these exoglycosidases were inhibited by Cd even at 44 mM concentration.

Low-level exposure to cadmium during the lifetime increases the risk of osteoporosis and fractures of the lumbar spine in the elderly: studies on a rat model of human environmental exposure.

In this study, based on a rat model of human environmental exposure to cadmium (Cd), it has been examined whether low-level lifetime Cd exposure increases the risk of vertebral osteoporosis and vertebrae fractures in the elderly. For this purpose, the lumbar vertebral bodies (L4 or L3) of control and Cd-exposed (1 mg Cd/l in drinking water for 24 months) female Wistar rats were assigned to densitometric, radiographic, biomechanical (compression test), and biochemical studies, as well as to assess their dimensions and chemical composition. The exposure to Cd affected the mineral status of the L4. The decreased mineral content, density (BMD) and bone mineral area of the vertebral body together with the unchanged ratio of non-organic and organic components indicate osteoporotic nature of the Cd-induced changes. The activity of alkaline phosphatase in the L3 decreased. Cd also influenced the mechanical properties of the L4. The yield load and ultimate load decreased indicating a weakness in the vertebral body compression strength. Stiffness of the L4 decreased and the displacement at ultimate increased suggesting its enhanced susceptibility to deformities. Indeed, in the Cd group vertebral deformities (in 30% of females) or even fractures (in 40% of females), including those with disruption of bone continuity were evident. Z-score values for the L4 BMD revealed vertebral osteopenia in 30% and osteoporosis in 70% of the Cd-exposed females. The results allow for the conclusion that low lifetime exposure to Cd may become an important factor increasing the risk of lumbar spine osteoporosis with vertebral deformities and fractures in the elderly.

Effect of acute exposure to cadmium on the expression of calcitonin gene-related peptide (CGRP), calcitonin (CT), somatostatin (SST) and synaptophysin (SYN) in the C cells of the rat thyroid--a preliminary study.

The aim of the present study was to determine to what degree acute exposure to cadmium affects the expression of CGRP, CT, SST and SYN in the C cells of the rat thyroid. Animals from 7 experimental groups received CdCl2 iv. in doses of 3.5, 3, 2.5, 2, 1.5, 1 and 0.5 mg/kg b.w. respectively, while the control animals were given 0.9% NaCl iv. 24 hours after the iv. administration of CdCl2, a correlation was found between a single dose of cadmium and the intensity of the immunocytochemical reactions for CGRP, CT, SST and SYN in C cells of the rat thyroid when compared to the control. The weakest immunocytochemical reactions were noted in C cells of the thyroid of rats from Groups I and II, their intensity gradually increasing in Groups III, IV and V in comparison to the control. The reaction intensity in animals of Groups VI and VII resembled those of the control.