Lead and zinc concentrations in household dust and toenails of the residents (Estarreja, Portugal): a source-pathway-fate model.

This paper describes a methodology developed to assess and apportion probable indoor and outdoor sources of potentially toxic elements while identifying chemical signatures in the household dust collected from private homes in an industrial city (Estarreja, central Portugal). Oral bioaccessibility estimates and the chemical composition of toenail clippings were used to assess indoor dust ingestion as a potential exposure pathway and further investigate exposure-biomarker relationships. Indoor and paired outdoor dust samples were collected from each household. A total of 30 individuals, who provided toenail clippings and a self-reported questionnaire, were recruited for the study. Total concentrations of 34 elements, including lead and zinc, were determined in washed toenail samples and household dust via Inductively Coupled Plasma-Mass Spectrometry. The oral bioaccessibility was estimated using the Unified BARGE Method. The enrichment factor shows that lead was enriched (10 < EF < 100) while zinc (EF > 100) was anomalously enriched in the household dust, thus indicating potential exposure in the home environment. The results from principal component analysis coupled to cluster analysis and linear discriminant analysis suggested that mixed contamination derived from multiple sources with a predominance of biomass burning. Stepwise multiple linear regression analysis was performed to model toenail data using the indoor dust elemental composition. Whereas the model obtained for lead was not reliable, indoor dust zinc and antimony contents arose as good predictors of toenail zinc. The exposure-biomarker relationships seem to be influenced by the oral bioaccessibility of the elements.

Functional mapping of the circuits involved in the expression of contextual fear responses in socially defeated animals.

In this study, we have aimed at outlining the neural systems underlying the expression of contextual fear to social defeat. First, we have developed an experimental procedure, where defeated animals could express, without the presence of a dominant aggressive male, robust and reliable conditioned fear responses to the context associated with social defeat. Next, by examining the pattern of Fos expression, we have been able to outline a brain circuit comprising septal and amygdalar sites, as well as downstream hypothalamic paths, putatively involved in the expression of contextual fear to social threat. Of particular relevance, we have found that exposure to a defeat-associated context results in a striking Fos up-regulation in the dorsomedial part of the dorsal premammillary nucleus (PMDdm). To further understand the role of the PMDdm in the circuit organizing conditioned fear to social threats, we have been able to observe that pharmacological blockade of the PMDdm reduced fear responses to a social defeat-associated context. Next, we observed that pharmacological blockade of the dorsomedial part of the periaqueductal gray, one of the main targets of the PMDdm, produced an even higher reduction of conditioned fear in defeated intruders, and appears as an important node for the expression of contextual defensive responses to social threats. The present results help to elucidate the basic organization of the neural circuits underlying contextual conditioned responses to social defeat, and reveal that they share at least part of the same circuit involved in innate responses to social defeat to an aggressive conspecific.

Abortion associated with Chlamydia abortus in extensively reared Iberian sows.

Reproductive disease was investigated in Iberian pigs on an extensive farrow-to-finish farm in the southwest of Spain. Chlamydia abortus was isolated in cell culture and C. abortus-specific PCR products were detected in placental and fetal tissues. In one batch of 14 sows, the percentage of sera positive for C. abortus specific antibodies increased from 35.7% to 85.7% in the period of 2 weeks following abortion. C. abortus may play a role in abortion in extensively reared Iberian sows.

Transfer factors as immunotherapy and supplement of chemotherapy in experimental pulmonary tuberculosis.

Problems of logistics, compliance and drug resistance point to an urgent need for immunotherapeutic strategies capable of shortening the current six month antibiotic regimens used to treat tuberculosis. One potential immunotherapeutic agent is transfer factors. Transfer factors (TF) are low molecular weight dialysable products from immune cells which transmit the ability to express delayed-type hypersensitivity (DTH) and cell mediated immunity from sensitized donors to nonimmune recipients. In this study we determined the efficiency of TF as immunotherapy to treat experimental tuberculosis. When BALB/c mice are infected via the trachea with Mycobacterium tuberculosis H37Rv there is an initial phase of partial resistance dominated by Th-1 type cytokines plus tumour necrosis factor-alpha (TNFalpha) and the inducible isoform of nitric oxide synthase (iNOS), followed by a phase of progressive disease characterized by increasing expression of IL-4, diminished expression of TNFalpha and iNOS, and low DTH. Animals in this late progressive phase of the disease (day 60) were treated with different doses of TF (one injection per week) obtained from spleen cells when the peak of immune protection in this animal model is reached (day 21), or with different doses of TF from peripheral leucocytes of PPD + healthy subjects. We show here that the treatment with murine or human TF restored the expression of Th-1 cytokines, TNFalpha and iNOS provoking inhibition of bacterial proliferation and significant increase of DTH and survival. This beneficial effect was dose dependent. Interestingly, murine TF in combination with conventional chemotherapy had a synergistic effect producing significant faster elimination of lung bacteria loads than chemotherapy alone.