Lead enhances fluoride influence on apoptotic processes in the HepG2 liver cell line.

Chronic long-term exposure to high levels of fluoride leads to fluorosis, manifested by skeletal fluorosis and damage to internal organs, including kidneys, liver, parathyroid glands, and brain. Excess fluoride can also cause DNA damage, trigger apoptosis, and change cell cycle. The effect of fluoride may be exacerbated by lead (Pb), a potent inhibitor of many enzymes and a factor causing apoptosis, still present in the environment in excessive amounts. Therefore, in this study, we investigated the effects of sodium fluoride (NaF) and/or lead acetate (PbAc) on development of apoptosis, cell vitality, and proliferation in the liver cell line HepG2. We examined hepatocytes from the liver cell line HepG2, incubated for 48 h with NaF, PbAc, and their mixture (NaF + PbAc), and used for measuring apoptosis, index of proliferation, and vitality of cells. Incubation of the hepatocytes with NaF or PbAc increased apoptosis, more when fluoride and Pb were used simultaneously. Vitality of the cells depended on the compound used and its concentration. Proliferation slightly increased and then decreased in a high fluoride environment; it decreased significantly after addition of Pb in a dose-dependent manner. When used together, fluoride inhibited the decreasing effect of Pb on cell proliferation.

The effect of perinatal lead exposure on dopamine receptor D2 expression in morphine dependent rats.

The aim of this study was to investigate the behavioral and molecular effects of pre- and postnatal lead (Pb) exposure on the expression of morphine withdrawal and tolerance in adult rats. Rats were orally treated with 0.1% (1000ppm) lead acetate from conception, through gestation, up to postnatal day (PND) 28. Subsequently, behavioral experiments were conducted on adult (PND 60) male rats. To assess behavioral effects of morphine dependence in Pb-exposed rats two experimental models were used: naloxone-precipitated withdrawal signs and the assessment of morphine tolerance to antinociceptive effect in the tail-immersion test. Morphine withdrawal and tolerance were more expressed in Pb-exposed morphine administered rats than in morphine administered rats. In the case of morphine withdrawal signs the analysis of protein (Western blotting) and mRNA (RT PCR) expression revealed significantly higher dopamine D2 receptor (D2R) expression in prefrontal cortex, but not in striatum and hippocampus, in Pb-exposed morphine administered rats than in morphine administered rats. Differently, in the case of morphine tolerance the significant upregulation of D2R protein and mRNA expression in hippocampus, but not in prefrontal cortex or striatum, was demonstrated in Pb-exposed and morphine administered rats in comparison with morphine administered. These findings suggest that in morphine withdrawal and tolerant rats the perinatal Pb-exposure can affect D2R expression in brain region-specific manner. Immunohistochemical assessment of D2R expression in hippocampus showed translocation of D2R from membrane-cytoplasm in control rats to nucleus in morphine administered rats. Perinatal Pb-exposure did not induce the changes in the localization of D2R irrespective of morphine effect.

Disrupted pro- and antioxidative balance as a mechanism of neurotoxicity induced by perinatal exposure to lead.

The aim of this paper was to examine if pre- and neonatal exposure that results in lead (Pb) concentration below 'safe level' (10 µg/dL) in offspring blood may cause disruption of the pro/antioxidant balance in the developing rat brain. We studied oxidative stress intensity (malondialdehyde (MDA) concentration) as well as mRNA, protein expression and the activity of copper/zinc superoxide dismutase (SOD1), manganese superoxide dismutase (SOD2), glutathione peroxidase (GPx), phospholipid hydroperoxide glutathione peroxidase (GPx4), catalase (CAT), glutathione reductase (GSR). We also measured glutathione (GSH) concentrations in selected structures of the rat brain (forebrain cortex, FC, cerebellum, C, and hippocampus, H) and showed cellular localization of GPx4, SOD1 and SOD2 expressions in the hippocampus by immunohistochemical examinations. Despite low Pb level in blood we observed decrease of the activity of some antioxidant enzymes as well as mRNA and protein expression downregulation associated with an increase of MDA level and CAT expression upregulation, especially in the hippocampus region. At the subcellular level, downregulation of SOD2 expression and decreased enzyme activity as well as mitochondrial pool of GSH suggest also that mitochondrial mechanisms might account for Pb neurotoxicity mechanism. For some enzymes, we found differences in the effects of Pb on the level of expression and activity. The activity of CAT decreased despite an increase in mRNA and protein expression; and likewise the activities SOD1, GPx1 GPx4 decreased, despite substantially unchanged level of expression. These effects may be the result of impairment of catalytic function of the enzyme protein caused by Pb interaction or of reduction in the availability of cofactors. We conclude that antioxidant system of the hippocampus of immature rat brain is highly vulnerable to perinatal Pb exposure. Therefore, oxidative stress may be one of the possible mechanisms disturbing cellular metabolism in this structure. Disruption of pro- and antioxidant balance should be considered as a potential mechanism of the observed Pb adverse effects, leading to the impaired learning ability caused by Pb exposure in children.

Neurotoxicity of lead. Hypothetical molecular mechanisms of synaptic function disorders.

Lead (Pb) toxicity is still a major health problem associated with both environmental and occupational exposure. Special attention is given to the neurotoxic effect of lead. Along with the newly emerging data, the Pb concentration in the body that can be considered safe is declining. Numerous studies on the neurotoxicity of Pb have shown multiple cellular 'molecular targets' of this metal at the biochemical and molecular levels, and differences in sensitivity to its toxic action among various neural cells. One possible target of the neurotoxic effect of Pb (at the synapse level) is N-methyl-D-aspartic acid (NMDA) receptors. This review presents the hypothetical molecular mechanism by which Pb disrupts synapse formation and plasticity in developing hippocampal neurons and the role of the NMDA receptor-dependent signaling pathway and brain-derived neurotrophic factor (BDNF) as a mechanism of Pb neurotoxicity at the synapse level.

The character of haemostatic disorders and level of protein S-100 in acute ischaemic stroke can affect survival in the first week of follow-up: a pilot study.

Disorders of haemostasis which result in ischaemic stroke usually appear as thromboembolism in peripheral veins and the pulmonary circulation, and to a lesser extent as coagulopathy. The S-100 protein, a marker of stroke, correlates positively with the neurological deficit National Institutes of Health Stroke Scale (NIHSS). We adopted the hypothesis that early death of patients with acute ischaemic stroke can be explained by changes in blood coagulation and fibrinolysis. The study included 84 patients hospitalized with acute ischaemic stroke. Three groups were created: I (death between 1 and 2 days), II (death between 5 and 7 days) and III (with no deaths in hospital). We measured levels of fibrinogen, antithrombin, D-dimers, plasmin-antiplasmin complexes, plasminogen and clotting times (prothrombin time and activated partial thromboplastin time), platelet number, euglobulin clot lysis time (ECLTindex) and S-100 protein, C-reactive protein and white blood cells (WBCs). Group I had lower concentrations of fibrinogen compared to groups II (3.13 vs. 4.18, P<0.01) and III (3.13 vs. 3.77, P<0.02) and higher levels of D-dimers (3643 vs. 2278, P<0.05), higher concentrations of plasmin-antiplasmin complexes (1410 vs. 882, P=0.03) and a lower ECLTindex (152 vs. 219, P<0.02) when compared with group III. Group I also had higher concentrations of protein S-100 (2.09 vs. 0.61, P<0.001), higher NIHSS (18.0 vs. 13.2, P=0.073) and number of WBC (14.1 vs. 11.1, P<0.02) than in group III. The observed abnormalities in haemostasis, either found systemically or locally as cerebral microvascular thrombosis, may be factors potentially associated with death of patients with the shortest survival time.

Comparative effects of conjugated linoleic acid (CLA) and linoleic acid (LA) on the oxidoreduction status in THP-1 macrophages.

The aim of this study was to investigate the effect of conjugated linoleic acids (CLAs) on macrophage reactive oxygen species synthesis and the activity and expression of antioxidant enzymes, catalase (Cat), glutathione peroxidase (GPx), and superoxide dismutase (SOD). The macrophages were obtained from the THP-1 monocytic cell line. Cells were incubated with the addition of cis-9,trans-11 CLA or trans-10,cis-12 CLA or linoleic acid. Reactive oxygen species (ROS) formation was estimated by flow cytometry. Enzymes activity was measured spectrophotometrically. The antioxidant enzyme mRNA expression was estimated by real-time reverse transcriptase polymerase chain reaction (RT-PCR). Statistical analysis was based on nonparametric statistical tests [Friedman analysis of variation (ANOVA) and Wilcoxon signed-rank test]. cis-9,trans-11 CLA significantly increased the activity of Cat, while trans-10,cis-12 CLA notably influenced GPx activity. Both isomers significantly decreased mRNA expression for Cat. Only trans-10,cis-12 significantly influenced mRNA for SOD-2 expression. The CLAs activate processes of the ROS formation in macrophages. Adverse metabolic effects of each isomer action were observed.

Changes in the concentration of microelements in the teeth of rats in the final stage of type 1 diabetes, with an absolute lack of insulin.

The mineral content of tooth hard tissue may influence the rate of decay change. Considering this fact, we aimed at examining if type 1 diabetes might be a contributing factor to the appearance of tooth decay. The experiment was conducted on female Wistar rats. To induce diabetes, rats were intravenously injected with 1 mL streptozocine 0.01 M citrate buffer. The control group of rats was injected with 1 mL 0.01 M citrate buffer only. After 10 days, teeth and blood serum samples were obtained. Fluoride concentration was determined by potentiometer method, and calcium and magnesium, by AAS. Serum concentrations of glucose and estradiol in the diabetic rats were significantly higher compared to the control group. In the experimental group, a statistically significant decrease of fluorine concentration in both teeth and serum were observed. Calcium and magnesium concentrations in blood serum and dental magnesium concentration were significantly higher in rats with type 1 diabetes compared with the control. A downward trend in the content of dental calcium in streptozotocin-induced diabetic rats was observed. The results obtained indicate that caries initiation and progression could be promoted by metabolic changes associated with diabetes affecting the mineral composition of tooth hard tissue.

Enhanced matrix-degrading proteolytic activity within the thin thrombus-covered wall of human abdominal aortic aneurysms.

OBJECTIVE: The maintenance of an arterial elastin's integrity is essential in the prevention of abdominal aortic aneurysm (AAA) development. So far, the effect of intraluminal thrombus (ILT) thickness on the elastolytic activity within the AAA wall has not been studied. In the present study the hypothesis that thin thrombus is associated with enhanced proteolytic activity within human AAA wall was investigated. METHODS: The specimens for analysis, from both thin (< or = 10 mm) thrombus-covered and thick (> or = 25 mm) thrombus-covered wall, had been taken from 40 patients undergoing elective repair of AAA. We evaluated neutrophil elastase activity with the enzymatic assay. Concentrations of active matrix metalloproteinase-9 (MMP-9), total matrix metalloproteinase-8 (MMP-8), and tissue inhibitor of matrix metalloproteinases-1 (TIMP-1) were measured by ELISA. Biochemical parameters were compared with the Wilcoxon signed-rank test. RESULTS: Statistical analysis showed that the activity of elastase (P<0.0001) as well as concentrations of active MMP-9 (P=0.001), total MMP-8 (P<0.0001) and active MMP-9/total TIMP-1 ratio (P=0.002) were significantly higher in the thin thrombus-covered wall. Furthermore the TIMP-1 was found to have a lower concentration in the thin thrombus-covered in comparison with the thick thrombus-covered wall (P=0.003). There was a significant positive correlation between measurements in AAA wall sites with thin and thick thrombus for elastase, TIMP-1, MMP-9/TIMP-1 ratio, and a borderline correlation was observed for MMP-8. Active MMP-9 concentration did not correlate between sites. CONCLUSION: The current study demonstrates the differentiation of protease activity within the same AAA wall and its enhancement within the thin thrombus-covered aneurysm wall.