Metal mixture inhalation (Cd-Pb) and its effects on the bronchiolar epithelium. An ultrastructural approach

The current study explores the effects of the inhalation of lead (Pb), Cd and its mixture (Pb-Cd) in a mice model, analysing metal concentrations in the lung, and the morphological modifications in the bronchiolar epithelium identified by scanning electron microscopy after eight weeks of inhalation. Our results indicate that metal concentrations in lung were higher compared to controls; however, Pb concentrations drastically decrease in the mixture. This reduction was also observed in the inhalation chamber. The main changes observed in the bronchiole were mostly in the mixture. The modifications were mainly given by Cd alone and in the mixture, with a decreased number of nonciliated bronchiolar cells and an increased number of bundles of dividing cells. The additive effect of Pb-Cd is suggested, as the extensive damage observed was more evident when mice were exposed to the mixture, and the results endured more research in the area of inhaled mixtures.

MORPHOLOGICAL RECOVERY OF THE GRANULE CELLS FROM THE OLFACTORY BULB AFTER THE CESSATION OF ACUTE OZONE EXPOSURE

The purpose of this study was to analyze the possible morphological recovery of the granule cells in the olfactory bulb as a consequence of oxidative stress after an acute ozone exposure. Rats were divided in two groups: Control (air exposed) and experimental group, exposed 4 h, to 1 ppm ozone and divided into 4 subgroups, which were sacrificed at 2 and 24 h, 10 and 15 days, respectively. Olfactory bulbs were processed with the rapid Golgi method and for transmission electron microscopy. The granule cells of the olfactory bulb disclosed less dendritic spine density at 2, 24 h, and 10 days after the exposure compared with controls. At 15 days, the number of spines increased to values similar to those found in controls. The granule cells ultrastructure demonstrated an increment in lipofucsin granules, as well as swollen organelles, changes that decreased overtime. This change decline might be related to a partial recovery of the associative granule cells function.

Ultrastructural findings in murine seminiferous tubules as a consequence of subchronic vanadium pentoxide inhalation

Vanadium (V) is a transition metal emitted to the atmosphere during the combustion of fossil fuels. Its current status as an atmospheric pollutant increases the need for information about the effects that this element might have on the reproductive health of exposed populations. The present study investigated changes in testicular ultrastructure following inhalation exposure of male mice to V (as vanadium pentoxide). Tissue V level was constant during the 12-week time period. We observed necrosis of spermatogonium, spermatocytes and Sertoli cells, as well as pseudo-nuclear inclusion and disruption of cellular junctions. Our findings stressed the importance of the hemato-testicular barrier in supporting the function of Sertoli cells and suggest as a possible target of V, tight junction proteins. Further analysis is needed in order to identify the role that reactive oxidative species (ROS) might have on these cellular junctions, and if a specific protein is the target of its toxic effects. The relevance of this report concerns the impact that metal air pollution could have on male fertility in dense cities with vehicular traffic problems.

DNA damage as an early biomarker of effect in human health

In the last few decades the need for new approaches to assess DNA damage has been increasing due to the implications that different insults on genetic material may have on human health. In this context, the identification of how chemical agents with different mechanisms of action (i.e., antineoplastic drugs) damage DNA provides a good model to investigate some cellular and molecular mechanisms underlying the basis of genetic toxicology. The nasal epithelium is the first barrier with which environmental pollutants interact, and for this reason this epithelium can be useful as a sentinel in order to assess the interactions between the environment and the living organisms. Taking these phenomena into account and using a simple, sensitive and rapid method such as the single cell gel electrophoresis, we could obtain information and an initial approach on the DNA status. This assay in combination with other techniques that provide more information about other molecular parameters could give us a better view of the biological status of the living cell.

Inhalation of cadmium, lead or its mixture Effects on the bronchiolar structure and its relation with metal tissue concentrations

The human population in the industrialized world is constantly exposed to chemical mixtures of pollutants such as metals; information about the consequences of the interactions of these compounds on health is scarce. The current study examines the effects of the inhalation of lead (Pb), cadmium (Cd) and Pb-Cd mixture in mice models analyzing the metal concentrations in lung, and the morphological modifications in the bronchiolar epithelium identified by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) after 4 weeks of inhalation. Our results showed that metal concentrations in lung were higher compared to controls; however, Pb concentrations drastically decrease with the mixture. This reduction was also observed in the inhalation chamber. These data correlate with the morphological alterations observed, which consisted of flattened and decreased number of nonciliated bronchiolar cells (NCBC), bald ciliated cells and bundles of NCBC. These modifications were mainly given by Cd, alone or in combination with Pb. The clusters formed by NCBC cells suggest cell proliferation which probably means that after metal inhalation, the cells enhance their proliferative capacity in order to repopulate the bronchiolar wall.

Pulmonary lymphoid lesions in an experimental model of collapsing glomerulopathy in rats

The characterization of lung damage in an experimental model of collapsing glomerulopathy (CG) in rats is described.

METHODS

12 rats were divided into two groups and injected intravenously (iv) with 1 mg/saline in a final volume of 1 ml/ day in the tail vein for 5 days, with fractionated serum from control and CG subjects. Proteinuria was quantified, and the Glomerular filtration rate was calculated based on creatinine clearance (CC). Rats were sacrificed by perfusion fixation at day 5.

RESULTS

Rats injected with serum from CG patients developed proteinuria (p<0.001). A decrease in CC (0.68+/-0.19) in these rats was also observed. Glomerular tuft retraction and mesangial proliferation was observed in all rats receiving serum from the CG patients. Peribronchiolar infiltrate integrated mainly by lymphocytes, was identified in all CG rats. In some areas this infiltration disrupted the basement membrane and damaged the epithelium. No histopathological abnormalities in the kidney or lungs were found in rats receiving control serum.

CONCLUSION

Patchy pulmonary lymphoid infiltrates were found in the CG model. Up to now there was no information about pulmonary lymphoid infiltration in CG patients. Besides fluid overload due to renal insufficiency or a nephrotic syndrome, other causes of pulmonary involvement in CG patients should be explored.

Nigrostriatal modifications after vanadium inhalation: an immunocytochemical and cytological approach

Vanadium (V) has increased in the air as a component of suspended particles originated from fuel combustion. In this report, a model of inhaled V in mice was implemented to identify the effect that V has in the corpus striatum and substantia nigra, structures with high concentrations of dopamine and scarce antioxidants burden. Mice inhaled 0.02 M V2O5 1 h twice a week and were sacrificed at points from 1 to 8 weeks after inhalation, perfused, and processed for Golgi method and for tyroxine hidroxylase (TH) inmunocytochemistry. Cytological analysis consisted in counting the number of dendritic spines in 20 medium-size spiny neurons and the number of TH immunoreactive neurons in the substatia nigra pars compacta. Dendritic spine density decreased drastically after V exposure; the same was observed with the TH-positive neurons, which decreased in a time-dependent mode. No previous morphological studies about V and nervous system have been reported. The decrease in spine density and in TH-positive neurons might have functional repercussions that should be studied because the trend of this element in the atmosphere is to increase.

Genotoxic differences by sex in nasal epithelium and blood leukocytes in subjects residing in a highly polluted area

We describe differences by sex in genotoxic damage found in a population of medical students exposed to a highly oxidative atmosphere, compared with a control group, measured by the single-cell gel electrophoresis assay and histological changes in nasal epithelium smears. Cells were obtained from the nasal epithelium and blood leukocytes. Higher DNA damage in nasal cells and leukocytes was found in males compared to females and control subjects. The percentage of squamous metaplastic changes in the nasal epithelium was also higher in males compared with females and controls. The co-mutation of normal nasal epithelium by squamous cells might modify its protective function in the nose, increasing the risk of damage to the lower respiratory tract. Although, as medical students, males and females were exposed to the same environment and activity patterns, male genotoxicity damage was higher in control and exposed subjects. More research should be done in order to identify direct or indirect sexual hormone intervention.

Motor impairments in an oxidative stress model and its correlation with cytological changes on rat striatum and prefrontal cortex

Exposure to ozone results in an increased production of free radicals which causes oxidative stress. The purpose of this study was to determine the effects of ozone exposure on motor behavior and its correlation with the cytology of the striatum and prefrontal cortex. Twenty-four male Wistar rats were exposed to 1 p.p.m. (parts per million) ozone for 4 hrs in a closed chamber. Control group was exposed to flowing air. Twenty-four hours after ozone exposure, the motor behavior was measured. After that, the animals were perfused and the brains were placed in Golgi stain. The analysis consisted in counting the dendritic spines in 5 secondary and 5 tertiary dendrites of each of the 20 medium size spiny neurons of striatum and 20 pyramidal neurons of prefrontal cortex analyzed. Our results showed alterations in motor behavior and a significant reduction of dendritic spines, and provided evidence that the deterioration in motor behavior is probably due to the reduction in spine density in the neurons of striatum and prefrontal cortex.

Effects of taurine on ozone-induced memory deficits and lipid peroxidation levels in brains of young, mature, and old rats

To determine the antioxidant effects of taurine on changes in memory and lipid peroxidation levels in brain caused by exposure to ozone, we carried out two experiments. In the first experiment, 150 rats were separated into three experimental blocks (young, mature, and old) with five groups each and received one of the following treatments: control, taurine, ozone, taurine before ozone, and taurine after ozone. Ozone exposure was 0.7-0.8 ppm for 4 h and taurine was administered ip at 43 mg/kg, after or before ozone exposure. Subsequently, rats were tested in passive avoidance conditioning. In the second experiment, samples from frontal cortex, hippocampus, striatum, and cerebellum were obtained from 60 rats (young and old), using the same treatments with 1 ppm ozone. Results show both an impairment in short-term and long-term memory with ozone and an improvement with taurine after ozone exposure, depending on age. In contrast to young rats, old rats showed peroxidation in all control groups and an improvement in memory with taurine. When taurine was applied before ozone, we found high peroxidation levels in the frontal cortex of old rats and the hippocampus of young rats; in the striatum, peroxidation caused by ozone was blocked when taurine was applied either before or after ozone exposure.

Morphologic alteration of the olfactory bulb after acute ozone exposure in rats

The interaction of ozone with some molecules results in an increased production of free radicals. The objective of this study was to identify whether acute ozone exposure to 1-1.5 ppm for 4 h, produced cytological and ultrastructural modifications in the olfactory bulb cells. The results showed that in rats exposed to ozone there was a significant loss of dendritic spines on primary and secondary dendrites of granule cells, whereas the control rats did not present such changes. Besides these exposed cells showed vacuolation of neuronal cytoplasm, swelling of Golgi apparatus and mitochondrion, dilation cisterns of the rough endoplasmic reticulum. These findings suggest that oxidative stress produced by ozone induces alterations in the granule layer of the olfactory bulb, which may be related to functional modifications.

Memory deterioration in an oxidative stress model and its correlation with cytological changes on rat hippocampus CA1

Exposure to ozone results in an increased production of free radicals which causes oxidative stress. The purpose of this study was to determine the effects of ozone exposure on memory and its correlation with the cytology of the hippocampus. Twenty-four male Wistar rats were exposed to 1 ppm (parts per million) ozone for 4 h in a closed chamber. Control group was exposed to flowing air. After ozone exposure, the rats were given long-term (24 h) memory training which consists of a passive avoidance conditioning. After that the animals were perfused and the brains were placed in the Golgi stain. The analysis consisted in counting the dendritic spines in five secondary and five tertiary dendrites of each of the 20 pyramidal neurons of hippocampus CA1 analyzed. Our results showed alterations on long-term memory and a significant reduction of dendritic spines, and provided evidence that this deterioration in memory is probably due to the reduction in spine density in the pyramidal neurons of hippocampus.