Developmental toxicity of N-methylaniline following prenatal oral administration in rats.

OBJECTIVES: The objective of the study was to assess prenatal toxicity of N-methylaniline (NMA) administered by gavage to pregnant female rats. MATERIAL AND METHODS: Pregnant female rats were administered N-methylaniline in corn oil by gavage at daily doses of 0.8 mg/kg of body weight (b.w.), 4 mg/kg b.w., 20 mg/kg b.w. and 100 mg/kg b.w. from implantation (the 5th day post mating) to the day prior to the scheduled caesarean section (the 20th day of pregnancy). General behavior, body weight, food and water consumption, hematological, biochemical analyses and pathomorphological changes of the dams were recorded. RESULTS: All the females survived until the end of the study. The test substance was toxic to pregnant females, even at the lowest of the used doses, i.e., 0.8 mg/kg b.w./day. Lower weight gain during pregnancy and significantly higher NMA-dose-dependent absolute weight of the organs were noted in the exposed females. The females from the groups exposed at doses of 20 mg/kg b.w./day and 100 mg/kg b.w./day developed anemia and showed higher concentrations of free thyroxine (FT3) and free triiodothyronine (FT4) thyroid hormones. Total protein concentration exhibited an increase in all the exposed groups of females. In the prenatal toxicity study, administration of N-methylaniline throughout the embryonic and fetal periods produced embryotoxic effects at doses ranging 4-100 mg/kg b.w./day. CONCLUSIONS: Considering the data obtained in this study, it is reasonable to assume that N-methylaniline administered orally to pregnant rats is toxic for mothers even at a low dose of 0.8 mg/kg b.w./day. However, this dose was not associated with any significant effects to their offspring. This prenatal exposure level may be considered as no-observed-adverse-effect level (NOAEL) for the progeny and a dose of 4 mg/kg b.w./day as the lowest-observed-adverse-effect level (LOAEL) for the progeny.

Anti-tumor potential of nitroxyl derivative Pirolin in the DMBA-induced rat mammary carcinoma model: A comparison with quercetin.

BACKGROUND: Considering the role of oxidative stress in carcinogenesis, we investigated the effect of synthetic antioxidant Pirolin (3-carbamoyl-2,2,5,5-tetramethylpyrroline-1-oxyl) on breast cancer progression. Since the anticancer drugs may cause cardiotoxicity due to oxidative stress in the heart muscle, we also evaluated Pirolin performance in heart tissue and compared its effect with that of the natural dietary flavonoid quercetin. METHODS: Sprague-Dawley rats were administered with 7,12-dimethylbenz(a)anthracene (DMBA) and then treated ip with an antioxidant (each at a dose of 10mg/kg b.w.) for 14 days. The histopathology of tumors, their size and multiplicity were assesed. The effect of antioxidants on heart tissue was evaluated by the oxidative stress markers and poly (ADP-ribose) polymerase 1 (PARP 1) cleavage. RESULTS: The median number of tumors and their volume, at the end of the study, were considerably smaller in both antioxidant-treated groups. We found a better antioxidative performance of quercetin in the heart, since a restoration of the GSH pool and decreased amount of hydroperoxides were observed. Antioxidants did not prevent cardiomyocytes from apoptosis. CONCLUSION: The attenuation of tumor progression by Pirolin was comparable with the action of quercetin. No negative changes were observed in the heart of animals after Pirolin treatment. Thus, its use in targeting deregulated redox pathways should be further studied.

Scintigraphic assessment of renal function in steel plant workers occupationally exposed to lead.

OBJECTIVES: Occupational exposure to lead may produce kidney damage, but existing data on the dose range associated with nephrotoxicity are inconclusive. We here assessed renal function under conditions of low to moderate lead exposure using renal scintigraphy. METHODS: Fifty-three male foundrymen (exposed group) and fourty male office workers (control group) from a steel plant were included in the study. Glomerular and tubular renal function were assessed by means of (99m)Tc-DTPA and (99m)Tc-EC clearance, respectively. Urinary markers of glomerular dysfunction (albumin) and tubular damage (α1-microglobulin (α1M), ß2-microglobulin (ß2M), retinol-binding protein (RBP), N-acetyl-ß-glucosaminidase (NAG) activity) were determined using latex beads tests or colorimetry. The lead concentration in blood was measured with atomic absorption spectrometry. RESULTS: The blood lead concentrations were 145.8 (121.3-175.3) and 39.3 (35.1-44.1) µg/l (geometric mean, 95(th) CI, p<0.001) in the exposed and control groups, respectively. Subjects exposed to lead presented with increased (99m)Tc-DTPA clearance (158.3 (148.4-168.8) vs. 135.9 (127.9-144.4) ml/min; p<0.01) and urinary albumin excretion (7.61 (6.28-9.22) vs. 4.78 (4.05-5.65) mg/g creatinine; p<0.001). (99m)Tc-EC clearance and excretion of α1M, ß2M, RBP and NAG were not significantly different between the groups. Significant correlations between (99m)Tc-DTPA clearance and blood lead concentrations (r=0.45; p<0.01) and between urinary albumin excretion and blood lead concentrations (r=0.71; p<0.001) were noted. CONCLUSIONS: Use of renal scintigraphy in present study revealed measurable alterations of renal function under the conditions of low-level lead exposure and suggest that increased glomerular filtration may be an early indicator of kidney damage in subjects occupationally exposed to lead.

Toxic effect in the lungs of rats after inhalation exposure to benzalkonium chloride.

BACKGROUND: Benzalkonium chloride (BAC) is a quaternary ammonium compound (QAC) toxic to microorganisms. Inhalation is one of the major possible routes of human exposure to BAC. MATERIALS AND METHODS: Experiments were performed on female Wistar rats. The rats were exposed to aerosol of BAC water solution at the target concentration of 0 (control group) and 35 mg/m(3) for 5 days (6 h/day) and, after a 2-week interval, the animals were challenged (day 21) with BAC aerosol at the target concentration of 0 (control group) and 35 mg/m3 for 6 h. RESULTS: Compared to the controls, the animals exposed to BAC aerosol were characterized by lower food intake and their body weight was significantly smaller. As regards BAC-exposed group, a significant increase was noted in relative lung mass, total protein concentration, and MIP-2 in BALF both directly after the termination of the exposure and 18 h afterwards. Significantly higher IL-6 and IgE concentrations in BALF and a decrease in the CC16 concentration in BALF were found in the exposed group immediately after the exposure. The leukocyte count in BALF was significantly higher in the animals exposed to BAC aerosol compared to the controls. In the lungs of rats exposed to BAC the following effects were observed: minimal perivascular, interstitial edema, focal aggregates of alveolar macrophages, interstitial mononuclear cell infiltrations, thickened alveolar septa and marginal lipoproteinosis. CONCLUSION: Inhalation of BAC induced a strong inflammatory response and a damage to the blood-air barrier. Reduced concentrations of CC16, which is an immunosuppressive and anti-inflammatory protein, in combination with increased IgE concentrations in BALF may be indicative of the immuno-inflammatory response in the animals exposed to BAC aerosol by inhalation. Histopathological examinations of tissue samples from the BAC-exposed rats revealed a number of pathological changes found only in the lungs.

Comparison of neurobehavioral and biochemical effects in rats exposed to dusts from copper smelter plant at different locations.

Mixed exposure to metals (including arsenic and lead) associated with the neurological and respiratory effects constitute one of the major health problems of copper smelting. Chemical composition of the dust, and the expected health effect of inhalation can be very diverse at different parts of the smelter plant. The aims of this study were to compare lung responses and behavioral effects in female Wistar rats after instillation of dust collected from different production processes at the same smelter department. Dusts collected at two different locations of furnace hall were sifted through 25-µm-mesh sieve. Obtained dust fractions, P-25(I) collected near stove, rich in heavy metals and arsenic, and P-25(II) collected near anode residue storage site, rich in aluminium, were instilled to rats. At 1, 7 and 30 days after dusts instillation, lung injury and inflammation were measured by analyzing sings of lung permeability in the bronchoalveolar lavage fluid (BALF), cell differentiation in BALF sediment and lung morphology. The behavioral studies were done 30 days after exposure. Results of biochemical tests showed a strong pro-inflammatory effect of P-25(I) fractions. Mostly characteristic effects after instillation of P-25(I) samples were 10× increased protein leakages in BALF. Both P-25(I) and P-25(II) fractions caused a reduction of Clara-cell 16 protein concentration (CC16) in BALF and activation of serum butyrylcholinesterase (BChE) at all time points. The morphological studies after exposure to P-25(I) fractions showed multi-focal infiltrations in the alveoli. The behavioral results, especially P-25(II) group rats (in open filed, passive avoidance and hot plate tests), indicated adverse effects in the nervous system, which may be related to changes in the dopaminergic and cholinergic pathway. The symptoms were noted in the form of persistent neurobehavioral changes which might be associated with the content of neurotoxic metals. e.g. Al, Mn and/or As. Decrease of CC16 concentration that occurred immediately after instillation of both dust samples, point out impaired anti-inflammatory potential, resulted in early harmful effect not only to the respiratory tract but also to the whole body, including the nervous system.

Fertility and developmental toxicity studies of diethylene glycol monobutyl ether (DGBE) in rats.

OBJECTIVES: The solvent, dimethylene glycol monobutyl ether (DGBE), is a component of latex paints, inks; it is used as a degreasing agent, industrial detergent. The aim of the study was evaluating the effects of DGBE administered by gavage on the estrous cycle and given with drinking water on fertility in rats and early development of their progeny. MATERIALS AND METHODS: Female rats were exposed to DGBE by gavage during 8 weeks at 250, 500 or 1000 mg/kg/day. Vaginal smears were collected during the exposure and 4 weeks after its cessation. Fertility studies were performed in male and female animals exposed to in drinking water. Males were exposed for 10 weeks and then mated with females exposed before mating, during pregnancy and lactation. Young animals were observed during 3 weeks after birth. RESULTS: DGBE does not cause disturbances of the menstrual cycle in females. Parameters used to assess the general toxicity indicate that males receiving DGBE in drinking water are more sensitive to this compound than females: significantly greater, dose-dependent relative spleen weight, significant decrease in hematological parameters from 8% to 15% depending on the dose, were observed. Clinical chemistry parameters (HDL-cholesterol, BUN) and some markers of oxidative stress differ between the exposed groups and the control one, but without adverse health effect. The microscopic examination of internal organs did not reveal morphological changes in male and female rats. CONCLUSION: The results of our study on the impact of exposure to DGBE on fertility in rats indicate that the substance administered for 9-10 weeks to females and males at a limit dose of 1000 mg/kg did not impair fertility or viability of their offspring during the first three weeks of life.

Tissue reaction to the nickel implants in the guinea pigs.

OBJECTIVES: The aim of the study was the assessment of local tolerance to nickel implants during 9 months observation in guinea pigs sensitized to nickel before implantation and non-sensitized ones. MATERIALS AND METHODS: Three groups of guinea pigs were included in the study: 10 sensitized to nickel by the guinea pig maximization test; 10 previously non-sensitized and 10 in control group. In 20 animals (except control group) the nickel implants were inserted in the muscle of the back. After 9 months of observation, the animals were patch-tested with 5% nickel sulfate. Also percentage of eosinophils in peripheral blood was examined. Next, the tissue surrounding the implant and skin from the area of patch tests were collected for the histological examination. RESULTS: In 70% of previously sensitized animals, the patch test confirmed the sensitivity to nickel. In 60% of previously non-sensitized animals, a positive reaction to nickel occurred. The results of patch tests in control group were negative. Percentage of eosinophils in peripheral blood was fourfold higher in animals sensitized to nickel than in control group. In histological examination, in the tissue surrounding the implant a dissimilarity concerning the intensity of cellular infiltration was observed between animals previously allergic and non-allergic to nickel. In the 2 of 10 previously sensitized guinea pigs quite severe inflammatory reactions in the inside of connective tissue capsule were noted which may indicate a local allergic reaction. The histological images of skin collected from the positive patch test site corresponded with the typical allergic contact dermatitis. CONCLUSIONS: Nickel implants may cause primary sensitization to nickel. The nature of the histological changes in the tissues around the implants in guinea pigs sensitized to nickel may correspond to an allergic reaction. The examination of percentage of eosinophils in blood of guinea pigs may be useful in assessing the allergenic activity of metal alloys containing nickel.

Evaluation of reproductive disorders in female rats exposed to N-methyl-2-pyrrolidone.

BACKGROUND: N-methyl-2-pyrrolidone (NMP) is a solvent used in the petrochemical, and electronic industries, in pesticides production, veterinary drugs, and paint removers. The aim of study was to evaluate the relationship between the dose of NMP given orally and its effect on fertility in female rats and early development of their progeny. METHODS: Females were exposed by gavage 5 days/week to NMP at 150, 450, or 1000 mg/kg/day 2 weeks before mating, during mating, gestation, and lactation. On the first postnatal day (PND 1), the live and dead pups were counted, weighed, and gender was determined. On PND 4, the litters were culled to eight animals each and balanced for gender. Young animals were observed during 3 weeks after birth. RESULTS AND CONCLUSION: Fertility index did not significantly differ in the control and the group exposed at 150 mg/kg/day but it was significantly lower in the groups exposed at 450 or 1000 mg/kg/day. The number of live pups in the group exposed to the highest dose was significantly lower and the number of stillbirths in litters was significantly greater. Survival of the pups from all exposed groups during the 3 weeks after birth was significantly lower than the control animals. The results of our study indicate that intragastric exposure of female rats to NMP before pregnancy during gestation causes significant impairment in female fertility and intrauterine mortality rates. At lower doses, toxic or slightly toxic to the mothers, this substance causes decrease in viability and physical development of progeny.

The inflammatory response in lungs of rats exposed on the airborne particles collected during different seasons in four European cities.

Epidemiological studies have reported associations of ambient particulate air pollution, especially particulate matter (PM) less than 10 µm with exacerbations of asthma and chronic obstructive pulmonary disease. In an in vivo model, we have tested the toxicity of urban airborne particles collected during spring, summer, and winter seasons in four cities (Amsterdam, Lodz, Oslo, and Rome) spread across Europe. The seasonal differences in inflammatory responses were striking, and almost all the study parameters were affected by PM. Coarse fractions of the urban particle samples were less potent per unit mass than the fine fractions in increasing cytokine [macrophage inflammatory protein (MIP)-2 and tumor necrosis factor (TNF)-α] levels and in reducing Clara-cell secretory protein (CC16) levels. This study shows that PM collected at 4 contrasting sites across Europe and during different seasons have differences in toxic potency. These differences were even more prominent between the fine and coarse fractions of the PM.

4-Week inhalation toxicity of 2-methylnaphthalene in experimental animals.

OBJECTIVES: This paper presents toxic effects of 2-MN in laboratory animals under conditions of 4-week inhalation exposure to 2-methylnaphthalene (2-MN) vapors. MATERIALS AND METHODS: Male Wistar rats were exposed to 2-MN vapors at a nominal concentration of 0, 2, 10 or 50 mg/m(3) in dynamic inhalation chambers for 4 weeks (6 h/day, 5 days/week). After 4 weeks of inhalation exposure the animals were necropsied. Blood samples were collected and selected organs were weighted and prepared for histological examinations. RESULTS: The effects of the increased levels of exposure to 2-MN experienced by the experimental rats were as follows: a) increasing γ-glutamylotransferase activity, b) stimulation of the hematopoietic system, c) lower cholesterol concentrations, d) higher number of goblet cells in lobar bronchi, e) hyperplasia of hepatic bile ducts. CONCLUSION: Four-week exposure of the animals to 2-MN at 2 mg/m(3) proved to be the no-observed-adverse-effect-level (NOAEL), while 10 mg/m(3) appeared to represent the lowest-observed-adverse-effect-level (LOAEL).

Assessment of neurobehavioral and biochemical effects in rats exposed to copper smelter dusts.

Female Wistar rats were instilled per os by gavage with different copper dust samples: P-25 obtained by passing the test material through a 25 µmsieve, and P-0.1 containing soluble matter and ultra-fine, non-soluble<100 nm particulate matter (PM) fraction. The control group received sterile saline. The effects were studied at day 1, 7, and 30 post-exposure, focusing on bronchoalveolar lavage fluid (BALF) analysis (including biochemistry, cell morphology, cell viability, and Clara cell 16 protein concentration) and pathomorphology of lung. Results of biochemical tests showed a strong pro-inflammatory effect of both particulate fractions. The morphological studies after exposure to P-25 and P-0.1 fractions showed multi-focal infiltrations in the alveoli. Changes in behavioral (radial maze and passive avoidance tests) have shown that memory in groups exposed to dust was impaired. Our findings indicate that both samples of dust from Copper Smelter cause greater and lesser intensity (P-25 > P-0.1) of the symptoms of acute inflammatory reaction immediately 24 h after instillation to rats. Exposure results in dropping CC16 protein level in serum of rats. After one month, previous acute inflammation was resolved and transformed in persistent low-grade inflammation. The low-grade inflammation resulted in induction of neurobehavioral effects probably by changes in "cholinergic anti-inflammatory pathway" in which acetylcholine modulates neurotransmission.

Carcinogenic effect of arsenate in C57BL/6J/Han mice and its modulation by different dietary selenium status.

In this study, carcinogenic effects of arsenate in female C57BL/6J/Han mice exposed in drinking water to 50, 200 or 500microgAs/L for 24 months were investigated. All animals were fed low-selenium diet, however half of them were supplemented with sodium selenite in drinking water (200microgSe/L) to ensure the normal dietary level of selenium. Glutathione peroxidase activity in erythrocytes and plasma as well as selenium concentration in plasma after 3, 6, 12 and 18 months in satellite groups showed considerable decrease in animals from non-selenium supplemented groups in comparison to supplemented groups. A clear arsenic concentration-dependent increase in the number of malignant lymphoma associated with increase in the risk of death was observed (hazard ratio=0.91, 1.46, and 2.24, for 50, 200 and 500microgAs/L, respectively). No significant influence of selenium dietary status on arsenic carcinogenicity was shown. A significant association between selenium supplementation status and increased risk of death of the animals from causes other than malignant tumors was found (HR=1.79, p=0.04).

DNA damage induced by nitrous oxide: study in medical personnel of operating rooms.

Occupational exposure to anaesthetics such as nitrous oxide (N(2)O) and halogenated hydrocarbons has been suggested to increase risk of genetic damage. However, the dose-dependency of genotoxic effects has not been unequivocally established and their relation to occupational exposure limit (OEL) remain obscure. In this study, the genotoxicity associated with occupational exposure to anaesthetics has been investigated in a group of 55 female nurses and 29 male anaesthesiologists active for at least 5 years in a working environment containing variable concentrations of N(2)O and halogenated hydrocarbons. 83 unexposed health care workers (52 female nurses and 31 male doctors) matched for age, gender, smoking habit and employment duration were included in the control group. Genotoxicity has been assessed using comet test. Concentrations of nitrous oxide, sevoflurane and isoflurane monitored by gas chromatography and mass spectrometry made possible to relate the extent of DNA damage to the level of exposure. Our results for the first time document a positive correlation between the DNA damage and the N(2)O levels in the ambient air. By contrast, no correlation has been observed between genotoxic effects and concentrations of sevoflurane and isoflurane. The extent of genetic injury was especially aggravated among nurses and anaesthesiologists exposed to N(2)O in concentrations exceeding OEL (180 mg/m(3)). We conclude that occupational exposure to N(2)O is associated with increased DNA damage and that the level of exposure plays a critical role in this regard.

Assessment of reproductive toxicity and gonadotoxic potential of N-methyl-2-pyrrolidone in male rats.

OBJECTIVES: N-methyl-2-pyrrolidone (NMP) is a solvent used in petrochemical, electric and electronic industries, and in the production of paint removers, pesticides and veterinary drugs. The substance exhibits slight acute toxicity, and moderate irritant, embryotoxic and teratogenic effects. The aim of the study was to assess NMP reproductive toxicity and gonadotoxicity in male rats. MATERIAL AND METHODS: The animals were exposed per os to NMP at daily doses of 0, 100, 300 and 1000 mg/kg. After 10 weeks of exposure, each male was mated with nonexposed female, then all the males were autopsied, and epididymis and testis were fixed for pathomorphological examination. Viability and development of offspring was observed to 28 days postbirth. RESULTS: NMP at 1000 mg/kg was found to produce male infertility and extensive damage to the seminiferous epithelium in the seminal tubules of the testis. When administered at 100 mg/kg or 300 mg/kg, it did not significantly affect fertility or spermatogenesis. NMP exposure at 100 mg/kg did not influence either the viability or the development of their offspring in the first month of life, while exposure at 300 mg/kg resulted in a significantly lower viability of the offspring in the first four days of life. CONCLUSION: This study has demonstrated that sub-chronic exposure of male rats to NMP at 1000 mg/kg/day produces gonadotoxic effect and brings about infertility. Administration at lower doses of 100 and 300 mg/kg did not impair male fertility, but only the lowest dose of 100 mg/kg was found to have no influence on the prenatal development of the progeny.

Occupational exposure to nitrous oxide - the role of scavenging and ventilation systems in reducing the exposure level in operating rooms.

OBJECTIVES: The aim of this study was to assess the level of occupational exposure to nitrous oxide (N(2)O) in operating rooms (ORs), as related to different ventilation and scavenging systems used to remove waste anaesthetic gases from the work environment. METHODS: The monitoring of N(2)O in the air covered 35 ORs in 10 hospitals equipped with different systems for ventilation and anaesthetic scavenging. The examined systems included: natural ventilation with supplementary fresh air provided by a pressure ventilation system (up to 6 air changes/h); pressure and exhaust ventilation systems equipped with ventilation units supplying fresh air to and discharging contaminated air outside the working area (more than 10 air changes/h); complete air-conditioning system with laminar air flow (more than 15 air changes/h). The measurements were carried out during surgical procedures (general anaesthesia induced intravenously and maintained with inhaled N(2)O and sevofluran delivered through cuffed endotracheal tubes) with connected or disconnected air scavenging. Air was collected from the breathing zone of operating personnel continuously through the whole time of anaesthesia to Tedlar((R)) bags, and N(2)O concentrations in air samples were analyzed by adsorption gas chromatography/mass spectrometry. RESULTS: N(2)O levels in excess of the occupational exposure limit (OEL) value of 180mg/m(3) were registered in all ORs equipped with ventilation systems alone. The OEL value was exceeded several times in rooms with natural ventilation plus supplementary pressure ventilations and twice or less in those with pressure/exhaust ventilation systems or air conditioning. N(2)O levels below or within the OEL value were observed in rooms where the system of air conditioning or pressure/exhaust ventilation was combined with scavenging systems. Systems combining natural/pressure ventilation with scavenging were inadequate to maintain N(2)O concentration below the OEL value. CONCLUSION: Air conditioning and an efficient pressure/exhaust ventilation (above 12 air exchanges/h) together with efficient active scavenging systems are sufficient to sustain N(2)O exposure in ORs at levels below or within the OEL value of 180mg/m(3).

Evidence for oxidative stress at elevated plasma thiol levels in chronic exposure to carbon disulfide (CS2) and coronary heart disease.

OBJECTIVES: Oxidative stress in plasma may be promoted by plasma thiols such as homocysteine. However, other thiols such as glutathione may also exert antioxidant effects in vitro and in vivo. To further investigate whether plasma thiols act as prooxidants or antioxidants, we compared plasma oxidative status in patients with coronary heart disease (CHD) and in subjects occupationally exposed to carbon disulfide (CS(2)). METHODS: Fifty-five subjects chronically exposed to CS(2), 53 CHD patients, and 52 healthy controls were examined. To assess plasma oxidative status, concentrations of thiobarbituric reactive substances (TBARS) and total antioxidative capacity (TAC), as well as ferritin and ceruloplasmin were determined. Antioxidative reserve was assessed by the determination of vitamine E, uric acid, superoxide dismutase, catalase, and glutathion peroxidase. In addition, protein and non-protein plasma thiol levels were measured. RESULTS: Patients in both groups had increased levels of plasma thiols as compared to controls: CS(2)-exposed subjects presented with increased levels of thiols associated with plasma proteins, whereas CHD patients presented with elevated total homocysteine and cysteine levels. TBARS were significantly increased and TAC was significantly decreased both in CS(2)-exposed subjects and in CHD patients. In addition decreased activity of glutathione peroxidase, an antioxidative enzyme inhibited by thiol-containing compounds, was noted in both groups. CONCLUSION: These results demonstrate that regardless of their metabolic origin increased thiols are associated with increased oxidative stress in plasma.

Pneumotoxicity of dust from aluminum foundry and pure alumina: a comparative study of morphology and biomarkers in rats.

OBJECTIVES: The overall objective was to assess the role of aluminum dust and fumes in the aluminum foundry (Al-F) in generating local inflammation in the respiratory tract, which may lead to induction and elicitation of occupational asthma and fibrosis. To understand the underlying mechanisms of involving particles from foundry, a long-term study was performed on rats. MATERIALS AND METHODS: Pure alpha-alumina (Al-P) or (Al-F) was intratracheally instillated to rats in doses of 20 mg suspended in 0.5 ml of saline. After 3, 6 and 9 months since instillation, the following biomarkers were assessed in lung tissues: Clara cell protein (CC16), hyaluronic acid (HA), total protein, metaloproteinases (MMP) in bronchoalveolar lavage fluid (BALF), and GSH-S-transferase (GST). Morphological study of lungs and cells in BALF sediment was also performed. RESULTS: In the long-term study, Al-F dust induced marked changes in both epithelial cells and lung tissues, leading to important remodeling in collagen deposit and elastase fibres after 6 and 9 months. By contrast, the same dose of Al-P caused an increase in the number of polymorphonuclear leukocytes in the lung and fibrosis, but the latter was manifested by only slight signs. The lung BALF showed a decreasing level of Clara cell protein and a markedly increased expression of MMP-2 and MMP-9. These findings suggest that there is an upregulation of MMP and an increase in epithelial cell death and Clara cells proliferation, which may contribute to the respiratory symptoms through remodeling of airways and alveolar structures. CONCLUSIONS: In conclusion, it must be said that CC16 is the most sensitive biomarker. Decreasing levels of this biomarker in BALF was observed in an early phase (3 months PE) of our study with serum aluminum (Al-S) concentration not exceeding 30 microg/L(-1). Foundry dust causes marked irritation and inflammation in the rat lung. In occupational exposure it may therefore be active in the human lung, and thus contribute to the chronic obturative pulmonary disease (COPD).

High mobility group box 1 protein as a late-acting mediator of acute lung inflammation.

Acute inflammatory lung injury is often a delayed complication of critical illness and is associated with increased mortality. High mobility group box 1 (HMGB1) protein, in addition to its role as a transcriptional regulator factor, has been identified as a late mediator of endotoxin lethality and might be also involved in the development and progression of acute lung injury. HMGB1 protein itself can cause an acute inflammatory response manifested by increased production of proinflammatory cytokines and neutrophil accumulation. The delayed kinetics of HMGB1 protein release indicate that this protein is a distal mediator of acute inflamatory lung injury. Anti-HMGB1 protein antibodies attenuated endotoxin-induced lung injury, but not the early release of TNF-alpha and IL-1beta, indicating that HMGB1 protein is a late mediator of endotoxin-induced acute lung injury. HMGB1 protein is not released by apoptotic cells but is passively released by necrotic or damaged somatic and immune cells and it functions as a major stimulus of necrosis-induced inflammation. HMGB1 protein is also released by activated monocytes/macrophages and induces delayed and biphasic release of proinflammatory mediators from these cells. HMGB1 protein failed to stimulate cytokines release in lymphocytes, indicating that cellular stimulation is specific. We would like to suggest that HMGB1 protein may be also a primary mediator of the inflammatory responses to lung cells injury caused by toxic environmental chemicals.

[Good laboratory practice in occupational hygiene]. / Dobra Praktyka Laboratoryjna w higienie pracy.

Good laboratory practice (GLP) is the system that ensures quality assessment, defines the organization rules of institutions performing non-clinical studies in the area of human and environmental safety in general, and of chemicals and chemical preparations in particular as well as sets the conditions of planning, performing and monitoring of studies, the outcome of which is recorded, stored and reported. Occupational hygiene is an area of activities that involves anticipation, assessment and surveillance of health hazards in the work environment aimed at protecting health of workers and the population at large (IOHA). Assessment and control of harmful agents, which occur in the work environment, technological processes or methods of work should be carried out by research units (laboratories) with well documented competencies in the environment and/or biological monitoring, and those granted accreditation according to EN/ISO 17025. Anticipated risks should be based on analyses of physical, chemical and toxic properties of harmful agents, performed in line with the rules of good laboratory practice. Accredited laboratories and the quality of their tests are monitored by governmental agencies. The application of the GLP system provides: the opportunity to investigate analytical procedures and data (the documentation concerning each stage of a given analysis should ensure a complete reconstruction of the whole analytical process); the confirmed reliability of the results; the recognition of the results in European Union member states and by the Organization for Economic Cooperation and Development (OECD); the opportunity to avoid repetition of analyses and studies; a better care of the human health and environment.

Combined exposure to m-xylene and ethanol: oxidative stress in the rat liver.

OBJECTIVES: Ethanol may be a significant combined factor in human solvent toxicity. Lipid peroxidation has been suggested to be an important contributing mechanism involved in experimental alcohol-induced liver injury. The aim of the study was to investigate whether a short-term ethanol ingestion in rats chronically exposed to m-xylene vapor may influence the lipid peroxidation rate in the intracellular hepatic membranes, the level of glutathione and the activity of glutathione-related enzymes in the liver. MATERIALS AND METHODS: Experiments were performed on male Wistar rats (outbred IMP:WIST) exposed to m-xylene (5 months, 5 h/day), at a low concentration (400 mg/m3), and/or acute ethanol administration (6 oral doses of 0.25 g/100 g b.w. at 12 h intervals, for the last 3 days of xylene exposure). To estimate the oxidative stress in the liver, lipid peroxidation rate in microsomal and lysosomal membranes, glutathione sulfhydryls levels, and glutathione-S-transferase activity were determined. RESULTS: The studies indicated that combined exposure to ethanol and m-xylene, as distinct from the chronic exposure to m-xylene alone, led to the increased lipid peroxidation rate in microsomal and lysosomal membranes with a simultaneous decrease in the levels of glutathione sulfhydryls and glutathione-S-transferase activity. CONCLUSIONS: We conclude that the enhanced lipid peroxidation rate in the intracellular hepatic membranes may be an important agent in combined ethanol/xylene-induced hepatotoxicity.