Pastagens melhoradas e suplementação alimentar no comportamento reprodutivo de vacas de corte primíparas.

O desempenho reprodutivo de 122 vacas Devon primíparas foi avaliado nos seguintes tratamentos: T1: 33 vacas mantidas em campo natural (Axonopus sp; P. notatum Flugge); T2: 30 vacas em campo natural, suplementadas, em média, por 82 e 31 dias, respectivamente, no pré e pós-parto com 1 kg de feno (L. multiflorum L.; T. repens; T. subterraneum e campo natural) e 1,74 kg de farelo de arroz e 0,24 kg de farelo de soja vaca/dia; T3: 29 vacas mantidas em pastagem natural melhorada com as mesmas espécies forrageiras do feno do T2, por, em média, 73 dias e 40 dias no pré e pós-parto, respectivamente; T4: 30 vacas na mesma pastagem natural melhorada do T3 utilizada em média por 89 dias pré e 52 dias pós-parto. Durante o experimento manteve-se a lotação de uma vaca/ha para T1 e T2 e 1,5 vaca/ha para T3 e T4. Após os tratamentos, foi constituído um só grupo em campo natural com lotação de uma vaca com cria/ha. O campo natural não possibilitou ganhos diários de peso (GDM) satisfatórios (0,065 kg/dia; P<0,05) no final da gestação e início da lactação. A suplementação favoreceu os GDM das vacas (0,576 kg/dia). Vacas do T3 e T4 tiveram GDM maiores no pré (0,801 e 1,031) e pós-parto (0,506 e 0,520) e o melhor desempenho reprodutivo. Vacas com ganhos de peso na época de monta tenderam à melhor taxa de concepção. Não houve diferença entre tratamentos na taxa de prenhez, mas a comparação de T1 e T2 com o T3 e T4 indicou superioridade das pastagens melhoradas sobre o campo natural, com ou sem suplementação. Os índices de prenhez foram: T1= 81,3%; T2= 77,8%; T3 = 100,0%; e T4= 93,1%

Frequencies of CCR5-D32, CCR2-64I and SDF1-3’A mutations in Human Immunodeficiency Virus (HIV) seropositive subjects and seronegative individuals from the state of Pará in Brazilian Amazonia

The distribution of genetic polymorphisms of chemokine receptors CCR5-delta32, CCR2-64I and chemokine (SDF1-3’A) mutations were studied in 110 Human Immunodeficiency Virus type 1 (HIV-1) seropositive individuals (seropositive group) and 139 seronegative individuals (seronegative group) from the population of the northern Brazilian city of Belém which is the capital of the state of Pará in the Brazilian Amazon. The CCR5-delta32 mutation was found in the two groups at similar frequencies, i.e. 2.2% for the seronegative group and 2.7% for the seropositive group. The frequencies of the SDF1-3’A mutation were 21.0% for the seronegative group and 15.4% for the seropositive group, and the CCR2-64I allele was found at frequencies of 12.5% for the seronegative group and 5.4% for the seropositive group. Genotype distributions were consistent with Hardy-Weinberg expectations in both groups, suggesting that none of the three mutations has a detectable selective effect. Difference in the allelic and genotypic frequencies was statistically significant for the CCR2 locus, the frequency in the seronegative group being twice that found in the seropositive group. This finding may indicate a protective effect of the CCR2-64I mutation in relation to HIV transmission. However, considering that the CCR2-64I mutation has been more strongly associated with a decreased risk for progression for AIDS than to the resistance to the HIV infection, this could reflect an aspect of population structure or a Type I error

Frequency of the CCRdelta32 allele in Brazilians: a study in colorectal cancer and in HTLV-I infection

The identification of a 32-bp deletion in the cc-chemokine receptor-5 gene (CCR5delta32 allele) that renders homozygous individuals highly resistant to HIV infection has prompted worldwide investigations of the frequency of the CCR5delta32 allele in regional populations. It is important to ascertain if CCR5delta32 is a factor to be considered in the overall epidemiology of HIV in individual populations. With this in mind we determined the CCR5delta32 allele frequency in a large sample (907 individuals) of the southeastern Brazilian urban population, stratified as follows: 322 healthy unrelated individuals, 354 unselected colorectal cancer patients, and 229 blood donors. The three groups displayed essentially identical allelic frequencies of CCR5delta32 and pairwise comparisons did not show significant differences. Thus, our results can be pooled to provide a reliable estimate of the CCR5delta32 allele frequency in the southeastern Brazil of 0.053 ± 0.005. The blood donors comprised 50 HTLV-I serologically negative individuals, 115 non-symptomatic individuals HTLV-I positive by ELISA but with indeterminate Western blot results, 49 healthy blood donors HTLV-I positive both at ELISA and Western blot and 15 patients with clinical spinal cord disease (HAM). A suggestive trend was observed, with the CCR5delta32 frequencies decreasing progressively in these four categories. However, when we applied Fischer's exact test no significant differences emerged. We believe that further studies in larger cohorts should be performed to ascertain whether the CCR5delta32 allele influences the chance of becoming infected or developing clinical symptoms of HTLV-I infection.<br>A observação de que indivíduos homozigotos para uma deleção de 32 pares de base no gene que codifica para o receptor 5 de cc-quimiocinas apresentam um menor risco de contrair a infecção por HIV-1 levou à investigação da freqüência deste polimorfismo em várias populações mundiais. É importante investigar se o CCR5delta32 é um fator a ser considerado na epidemiologia do HIV em populações individuais. Com estes pressupostos em mente nós estabelecemos a freqüência do CCR5delta32 em uma grande amostra (907 indivíduos não-relacionados) da população urbana do sudeste brasileiro, estratificada da seguinte maneira: 322 indivíduos sadios, 354 pacientes com câncer colorretal e 229 doadores de sangue. Os três grupos apresentaram essencialmente a mesma freqüência alélica de CCR5delta32 e a comparação par-a-par não revelou diferenças significativas. Assim, os nossos resultados podem ser agrupados para fornecer uma estimativa confiável de 0,053 ± 0,005 da freqüência alélica de CCR5delta32. Os doadores de sangue compreendiam 50 indivíduos soronegativos para HTLV-I, 115 indivíduos assintomáticos por ELISA mas com resultados indeterminados em Western blot, 49 indivíduos soropositivos para HTLV-I mas assintomáticos e 15 indivíduos soropositivos para HTLV-I sintomáticos com mielopatia. Foi observado um sugestivo gradiente decrescente da freqüência alélica de CCR5delta32 nestas categorias. Entretanto, quando aplicamos o teste exato de Fisher, não emergiram diferenças significativas. Para uma melhor avaliação da influência do alelo CCR5delta32 na probabilidade de infectar-se com HTLV-I ou de desenvolver doença clínica serão necessários estudos com um maior número de doadores de sangue

Effect of combined polymorphims in chemokines and chemokine receptors on the clinical course of HIV-1 infection in a brazilian population

Polymorphisms in genes that encode chemokines or their receptors can modulate susceptibility to human immunodeficiency virus (HIV) infection and disease progression. The objective of this study was to assess the frequency of polymorphisms CCR5-Δ32, CCR2-64I, CCR5-59029A and SDF1-3’A and their role in the course of HIV infection in a southern Brazilian population. Clinical data were obtained from 249 patients for an average period of 6.4 years and genotypes were determined by standard polymerase chain reaction (PCR) and PCR-restriction fragment length polymorphism. Survival analyses were conducted for three outcomes: CD4+ T-cell counts below 200 cells/ μl, acquired immune deficiency syndrome (AIDS) or death. The frequency of the polymorphisms CCR5-Δ32, CCR2- 64I, CCR5-59029A and SDF1-3’A were 0.024, 0.113, 0.487 and 0.207, respectively. CCR5-Δ32 was associated with a reduction in the risk for CD4+ T-cell depletion and with an increased risk for death after AIDS diagnosis. CCR2-64I was associated with a reduction in the risk for developing AIDS. SDF1-3’A was also associated with decreased risk for AIDS, but its effect was only evident when CCR2-64I was present as well. These results highlight the possibility of using these markers as indicators for the prognosis of disease progression and provide evidence for the importance of analysing the effects of gene polymorphisms in a combined fashion