A Pentanucleotide ATTTC Repeat Insertion in the Non-coding Region of DAB1, Mapping to SCA37, Causes Spinocerebellar Ataxia.

Advances in human genetics in recent years have largely been driven by next-generation sequencing (NGS); however, the discovery of disease-related gene mutations has been biased toward the exome because the large and very repetitive regions that characterize the non-coding genome remain difficult to reach by that technology. For autosomal-dominant spinocerebellar ataxias (SCAs), 28 genes have been identified, but only five SCAs originate from non-coding mutations. Over half of SCA-affected families, however, remain without a genetic diagnosis. We used genome-wide linkage analysis, NGS, and repeat analysis to identify an (ATTTC)n insertion in a polymorphic ATTTT repeat in DAB1 in chromosomal region 1p32.2 as the cause of autosomal-dominant SCA; this region has been previously linked to SCA37. The non-pathogenic and pathogenic alleles have the configurations [(ATTTT)7-400] and [(ATTTT)60-79(ATTTC)31-75(ATTTT)58-90], respectively. (ATTTC)n insertions are present on a distinct haplotype and show an inverse correlation between size and age of onset. In the DAB1-oriented strand, (ATTTC)n is located in 5' UTR introns of cerebellar-specific transcripts arising mostly during human fetal brain development from the usage of alternative promoters, but it is maintained in the adult cerebellum. Overexpression of the transfected (ATTTC)58 insertion, but not (ATTTT)n, leads to abnormal nuclear RNA accumulation. Zebrafish embryos injected with RNA of the (AUUUC)58 insertion, but not (AUUUU)n, showed lethal developmental malformations. Together, these results establish an unstable repeat insertion in DAB1 as a cause of cerebellar degeneration; on the basis of the genetic and phenotypic evidence, we propose this mutation as the molecular basis for SCA37.

Mutational mechanism for DAB1 (ATTTC)n insertion in SCA37: ATTTT repeat lengthening and nucleotide substitution.

Dynamic mutations by microsatellite instability are the molecular basis of a growing number of neuromuscular and neurodegenerative diseases. Repetitive stretches in the human genome may drive pathogenicity, either by expansion above a given threshold, or by insertion of abnormal tracts in nonpathogenic polymorphic repetitive regions, as is the case in spinocerebellar ataxia type 37 (SCA37). We have recently established that this neurodegenerative disease is caused by an (ATTTC)n insertion within an (ATTTT)n in a noncoding region of DAB1. We now investigated the mutational mechanism that originated the (ATTTC)n insertion within an ancestral (ATTTT)n . Approximately 3% of nonpathogenic (ATTTT)n alleles are interspersed by AT-rich motifs, contrarily to mutant alleles that are composed of pure (ATTTT)n and (ATTTC)n stretches. Haplotype studies in unaffected chromosomes suggested that the primary mutational mechanism, leading to the (ATTTC)n insertion, was likely one or more T>C substitutions in an (ATTTT)n pure allele of approximately 200 repeats. Then, the (ATTTC)n expanded in size, originating a deleterious allele in DAB1 that leads to SCA37. This is likely the mutational mechanism in three similar (TTTCA)n insertions responsible for familial myoclonic epilepsy. Because (ATTTT)n tracts are frequent in the human genome, many loci could be at risk for this mutational process.

Characterization of polymeric nanoparticles for intravenous delivery: Focus on stability.

The nano-bio interaction has been of increased focus in the past years but very limited results have been obtained for polymeric nanoparticles (NP). Not only is needed to broaden the results obtained with model NP towards other nano-materials used for clinical application but the colloidal stability of NP as a variable consequence of the formation of the protein corona has been significantly understated. The lack and heterogeneity of assays to study NP stability and represent the biological environment call for the standardization of assays to improve the representativeness and comparability of results. In this paper, uncoated and PAH-coated PLGA NP have been prepared and characterized in regard to their potential for intravenous administration. The comparative study of the stability of NP in three media used to represent the biological environment-bovine serum albumin (BSA) solution, mouse and human plasma - revealed that both formulations were unstable in human plasma as opposed to the results obtained for other media. This unexpected behavior in plasmas of different origins could be correlated with a significant variation of the amount of proteins adsorbed to NP and, ultimately, with an approximately 6-fold difference in total protein concentration between the plasma samples. These results suggest that inter-species variation could impact on the colloidal stability of NP and enhance the need to understand the correlation between biological media and identify protocol-related interferences which, altogether, may evidence a relevant factor compromising in vitro- in vivo correlation and the translation of delivery systems aimed at intravenous administration.

Unstable repeat expansions in neurodegenerative diseases: nucleocytoplasmic transport emerges on the scene.

An astonishing number of neurological diseases result from expansion of unstable repetitive sequences causing alterations in key neuronal processes. Some are progressive late-onset conditions related to aging, such as the spinocerebellar ataxias. In several of these pathologies, the expanded repeat is transcribed, producing an expanded RNA repeat that causes neurodegeneration by a complex mechanism, comprising 3 main pathways. These include (1) accumulation in the nucleus of RNA foci, resulting from sequestration of RNA-binding proteins functioning in important neuronal cascades; (2) decrease in availability of RNA-binding proteins, such as splicing factors, causing alternative splicing misregulation with imbalance in the expression ratio of neuronal isoforms; and (3) generation of neurotoxic peptides, produced from repeat-associated non-ATG-initiated translation across the RNA repeat, in all reading frames. Recently, 2 pathologies characterized by impaired motor function, cognitive decline, or/and degeneration of motor neurons have been found that have broaden our understanding of these diseases. Moreover, the finding of compromised nucleocytoplasmic transport opens new avenues for research. This review will cover the amazing progress regarding these conditions.

HIV genotypes and primary drug resistance among HIV-seropositive blood donors in Brazil: role of infected blood donors as sentinel populations for molecular surveillance of HIV.

BACKGROUND: There are few surveillance studies analyzing genotypes or primary (transmitted) drug resistance in HIV-infected blood donors in Brazil. The aim of this study was to characterize patterns of HIV genotypes and primary resistance among HIV-seropositive donors identified at 4 geographically dispersed blood centers in Brazil. METHODS: All HIV-infected donors who returned for counseling at the 4 REDS-II Hemocenters in Brazil from January 2007 to March 2011 were invited to participate in a case-control study involving a questionnaire on risk factors. Viral sequencing was also offered to positive cases to assign genotypes and to detect and characterize primary resistance to reverse transcriptase and protease inhibitors according to World Health Organization guidelines. RESULTS: Of the 341 HIV-seropositive donors who consented to participate in the risk factor and genetics study, pol sequences were obtained for 331 (97%). Clade B was predominant (76%) followed by F (15%) and C (5%). Primary resistance was present in 36 [12.2%, 95% confidence interval (CI) 8.2 to 15.5] of the 303 individuals not exposed to antiretroviral therapy, varying from 8.2% (95% CI: 2.7 to 13.6) in Recife to 19.4% in São Paulo (95% CI: 9.5 to 29.2); there were no significant correlations with other demographics or risk factors. CONCLUSIONS: Although subtype B remains the most prevalent genotype in all 4 areas, increasing rates of subtype C in Sao Paulo and F in Recife were documented relative to earlier reports. Transmitted drug resistance was relatively frequent, particularly in the city of Sao Paulo which showed an increase compared with previous HIV-seropositive donor data from 10 years ago.

Spatial analysis of migrating Apis mellifera colonies in Salvador, Bahia, Brazil.

Beekeeping in Brazil is growing but also associated with an increase in the number of human and animal accidents involved. In particular, bees of the Apis mellifera species (Africanized bees) are known for their aggressive behaviour and frequent swarming activity due to their poor adaptation to the human environment. This study analyzed the spatial distribution of occurrences of migratory swarms of A. mellifera and recorded apicultural accidents in the city of Salvador, Bahia, Brazil. The association of demographic and climatic variations on places where the swarms occurred was also evaluated. The study is based on data collected within the frame of the "SOS Bees", a project initiated for the protection of the environment and enforced by a special unit of the military police in Bahia. In the 3-year period from 2000 to 2003, 590 swarms were registered in 75 of the 98 zones of information of Salvador. Three cluster areas, representing 25.4% of all events, were identified. In that period, 316 apicultural accidents were registered involving humans and one involving dogs. The seasonal rise of the monthly average temperature showed an association with the increase of the number of swarming events.

Prevalência de adultos infectados por Leishmania leishmania chagasi entre doadores de sangue do Hemocentro Regional de Montes Claros, Minas Gerais, Brasil / Prevalence of adults infected with Leishmania (Leishmania) chagasi among blood donors of the Hemominas Foundation in Montes Claros, Minas Gerais, Brazil

O objetivo deste trabalho foi estudar a prevalência de adultos infectados por L. L. chagasi entre doadores de sangue do Hemocentro Regional de Montes Claros/MG .Realizou-se estudo epidemiológico, transversal e quantitativo, no período de 16/09/08 a 13/11/08. Participaram da pesquisa 421 doadores aptos na triagem clínica, sendo realizada imunofluorescência indireta para L.L.chagasi. Aqueles que apresentaram resultados positivos foram submetidos ao teste rápido antígeno-específico para Leishmania donovani. A análise das variáveis gênero, faixa etária, procedência, número de doações, resultados sorológicos para leishmaniose e chagas, foi realizada pelos testes estatísticos qui-quadrado (x2), x2 com tendência linear e teste Fisher. Foi considerado o nível de significância de 5 por cento (p<0,05). O perfil da amostra foi semelhante ao perfil geral dos doadores. Os participantes, em sua maioria procedentes da zona urbana (92,7 por cento), residentes em Montes Claros (67,9 por cento), homens (61,3 por cento), com faixa etária de 18 a 29 anos. Em relação aos resultados sorológicos, 23 (5,5 por cento) apresentaram positividade para imunofluorescência indireta e nenhum destes foi positivo no teste rápido. Ao comparar os resultados da imunofluorescência para leishmaniose e a sorologia Elisa chagas, dois foram positivos para ambos os testes, sendo demonstrada correlação estatística significante (p=0,003). Porém, 21 foram positivos para leishmaniose e negativos para chagas. Os resultados permitiram conhecer a prevalência da infecção por L. l. chagasi em indivíduos assintomáticos, adultos, doadores de sangue do Hemocentro Regional de Montes Claros/MG e apontam para a necessidade de maiores estudos quanto ao possível risco de transmissão transfusional da doença.

The objective of this work was to study the prevalence of adults infected by Leishmania (Leishmania) chagasi among blood donors of the Hemominas Foundation in Montes Claros, Brazil. A cross-sectional, quantitative epidemiological study was performed of 421 blood donors from September 16 2008 to November 13 2008. The L. l. chagasi indirect immunofluorescence test (RIFI) was utilized. Donors that presented with positive results in RIFI were retested using the fast immunochromatographic test (Trald). The gender, age, place of origin, number of donations, leishmania and chagas disease serum results were studied with statistical correlations being analyzed utilizing the chi-square test (x2), x2 with linear tendency and the Fisher test; a level of significance of 5 percent (p <0.05) was considered acceptable. The profile of the study sample was similar to the overall donor profile. The participants were mostly donors from urban areas (92.7 percent), living in Montes Claros (67.9 percent), men (61.3 percent) and with ages between 18 and 29 years old. In relation to the serum results, 23 (5.5 percent) were positive according to the RIFI however none of them were positive by the Trald. On comparing the results of RIFI and the chagas disease serum test (Elisa), two individuals were positive for both tests, thereby giving a statistically significant correlation (p=0.003). However the other 21 were positive only by RIFI and negative for chagas disease. The results show the prevalence of infection by L. l. chagasi in asymptomatic, adult blood donors in the Hemominas Foundation in Montes Claros, and highlight the need for further studies on the possible risk of disease transmission via blood transfusion.