Loud Noise Exposure Produces DNA, Neurotransmitter and Morphological Damage within Specific Brain Areas.

Exposure to loud noise is a major environmental threat to public health. Loud noise exposure, apart from affecting the inner ear, is deleterious for cardiovascular, endocrine and nervous systems and it is associated with neuropsychiatric disorders. In this study we investigated DNA, neurotransmitters and immune-histochemical alterations induced by exposure to loud noise in three major brain areas (cerebellum, hippocampus, striatum) of Wistar rats. Rats were exposed to loud noise (100 dBA) for 12 h. The effects of noise on DNA integrity in all three brain areas were evaluated by using Comet assay. In parallel studies, brain monoamine levels and morphology of nigrostriatal pathways, hippocampus and cerebellum were analyzed at different time intervals (24 h and 7 days) after noise exposure. Loud noise produced a sudden increase in DNA damage in all the brain areas under investigation. Monoamine levels detected at 7 days following exposure were differently affected depending on the specific brain area. Namely, striatal but not hippocampal dopamine (DA) significantly decreased, whereas hippocampal and cerebellar noradrenaline (NA) was significantly reduced. This is in line with pathological findings within striatum and hippocampus consisting of a decrease in striatal tyrosine hydroxylase (TH) combined with increased Bax and glial fibrillary acidic protein (GFAP). Loud noise exposure lasting 12 h causes immediate DNA, and long-lasting neurotransmitter and immune-histochemical alterations within specific brain areas of the rat. These alterations may suggest an anatomical and functional link to explain the neurobiology of diseases which prevail in human subjects exposed to environmental noise.

Association of donor-specific microchimerism with graft dysfunction in kidney transplant patients.

The biological significance of donor-specific microchimerism (DSM) in solid organ transplantation is unresolved. It has been reported both as a favourable feature, which may facilitate induction and maintenance of tolerance, and as a sign of graft-vs-host disease. Here, we applied a quantitative real-time PCR assay (qRT-PCR) to a selected series of kidney transplant recipients to measure the level of microchimerism in relation to allograft function and survival. DSM level was assessed by scoring the HLA-DRB1 locus in 54 patients (42 males, 12 females) with more than 2 years of follow-up after transplantation; 38 patients were considered to have stable renal function (SRF) and 16 had allograft dysfunction (AD). Among patients with AD, 12 (75%) showed detectable level of microchimerism, compared to 11 (29%) SRF patients (Odds Ratio 7.36, 95% CI 1.7-35.2; p<0.01). In addition, AD patients showed a higher mean donor genome equivalents (6.5×10(-5) vs. 2.4×10(-5); p<0.001). SRF patients were re-evaluated two years later; 2 out of 27 DSM negative vs. 2 out of 11 DSM positive had lost their transplanted organ. In conclusion, qRT-PCR applied to peripheral blood shows significant association between DSM and allograft dysfunction in kidney transplant patients.

Haplotype analysis of the H63D, IVS2+4t/c, and C282Y polymorphisms of the HFE gene reveals rare events of intragenic recombination.

OBJECTIVE: Two missense mutations of the HFE gene, one (C282Y) being a major gene for hereditary hemochromatosis and the other (H63D) playing a minor role in this disease, are carried by different haplotypes. Among other sequence variants of HFE, IVS2+4t/c polymorphism has been reported as a possible splicing mutation or risk modifier. Our aims were to identify sequence variants possibly associated with iron overload in our population, to study the intragenic haplotypes of the HFE gene, and to evaluate the role of IVS2+4t/c in hyperferritinemia. METHODS: We screened by direct sequencing the coding sequence and intron-exon boundaries of HFE in 265 patients with hyperferritinemia and 185 subjects from the general population. RESULTS: Linkage disequilibrium between the three pairs of polymorphic sites was complete between H63D and C282Y, whereas all four gametic types were present for both the H63D-IVS2+4t/c and the IVS2+4t/c-C282Y site pairs. The data supported a model in which the IVS2+4t/c polymorphism was ancestral, the D(63) mutation occurred on the t chromosome, and the Y(282) mutation occurred on the c chromosome; after the population spread of both mutations, intragenic recombination occurred on both sides of the t/c polymorphism, generating the rare haplotypes D(63)-c(IVS2+4)-C(282) and H(63)-t(IVS2+4)-Y(282). CONCLUSIONS: The IVS2+4c/t is a neutral polymorphism with regard to risk of iron overload. The presence of recombinant haplotypes on both its sides suggests a considerable evolutionary age of the two main risk alleles.