Master of Science / Department of Agronomy / Michel D. Ransom / Many soils in southeastern Kansas are characterized by high clay contents and high shrink-swell potentials. Their vertic properties and claypan characteristics cause soil management to be difficult and pose problems for agricultural, environmental, and engineering uses. Thus, collecting more information and improving our understanding of these soils is an important step towards bettering our soil management techniques. The objectives of this study were to examine the morphology, processes of soil genesis, clay mineralogy, micromorphology, and potassium fixation potential of the soils of interest and how these characteristics varied between and within individual pedons. Ten pedons expected to represent varying degrees of vertic expression were selected. Methods included the use of field descriptions, routine soil laboratory characterization, micromorphological investigations, the determination of clay mineralogy by X-ray diffraction, and the measurement of potassium fixation potential. Field morphology reflected the geologic parent materials available in the region. The fine sediments that compose these clayey soils are primarily provided by the Pennsylvanian and Permian shales and limestones underlying this region and the Flint Hills to the west. Dominant pedogenic processes currently at work are clay illuviation and shrink-swell processes. Silty, non-expansive surface soils at all but sites 6 and 7 are thought to buffer the rapid wetting and drying cycles needed for maximum vertic expression. Four of the soils were dominated by smectitic minerals in the clay fraction while the rest exhibited a more mixed mineralogy. Disruption of illuvial clay features by shrink-swell movement was evident in thin section. Striated b-fabrics dominated the micromorphology except in non-expansive surface soils. K fixation of the soil surface was found to be negative in all soils, thus K fixation potential is considered very low. In subsurface horizons, K fixation generally increased with increasing vermiculite content. In addition to limited quantities of K-fixing clay minerals, naturally high K levels limited the amount of K fixation in this study. The information presented can be used to improve our understanding and management of high clay, vertic and claypan soils in southeastern Kansas.

Made available in DSpace on 2014-07-29T15:26:22Z (GMT). No. of bitstreams: 1 Tese Keila Correia de Alcantara.pdf: 2967378 bytes, checksum: abcf75d777805ea6de3323b7586a4654 (MD5) Previous issue date: 2010-10-31 / Introduction: The spread of the aids epidemic among young women and HIV-1 mother-tochild transmission (MTCT) represent important public health issues. In this context, prenatal care represents a unique opportunity for the early diagnosis of young women and for the implementation of full preventive strategies to HIV-1MTCT. Objectives: To study immunological, virological, clinical and epidemiological characteristics and to identify factors associated with HIV-1MTCT among HIV-1 pregnant women/infants recruited in Goias State. Material and methods: Cohort 1: 41 pregnant HIV/AIDS: infant pairs (April/2000-August/2001) were recruited and prospectively followed up at two regional reference centers-Mother-Infant Hospital (HMI/SUS) and Hospital Dr. Anuar Auad (HAA/HDT/SUS). Cohort 2: 172 HIV/AIDS pregnant women and 149 exposed children were recruited at the Institute of diagnosis and prevention (IDP/APAE) and prospectively followed up at HAA/HDT/SUS. The following tests were performed: maternal viral load, CD4+ T cell counts, HIV-1env/gag subtypes by heteroduplex mobility assay/HMA (cohort 1) and pol (protease and reverse transcriptase-PR/RT) sequencing for resistance profile, subtypes identification and phylogeography analysis for subtype C (cohort 2). Infants born to HIV-1/aids mothers were evaluated by plasma viral RNA and CD4+ T cell counts. Seroreversion of exposed- uninfected children was followed by sequential ELISA tests for IgG anti HIV-1. Results: Patients from cohorts 1 and 2 presented similar social-demographic and clinical profiles. The median age was 26 years; 15-41 years), lower educational level predominated and most were diagnosed during pregnancy (90%). Over 80% received ARV prophylaxis. One case of MTCT was observed in cohort 1 which was associated with short prophylaxis and long labor period. Exposed-uninfected infants born to symptomatic mothers seroreverted earlier. Cohort 2 included 80% of all HIV-1 infected pregnant women from Goias state in that period. The early prophylaxis and undetectable viral load predominated among previously diagnosed patients (p<0.05). One ARV naive patient presented transmitted drug resistance; 10 ARV experienced patients presented secondary drug resistance: 6 under MTCT prophylaxis, 4 under HAART. MTCT was observed in 3/149 (2.01%) cases and late diagnosis, vaginal delivery, brastfeeding and lack of oral ZDV were observed. Among MTCT cases resistance mutations were not detected. HMA env/gag (cohort 1) and pol sequencing (cohort 2) results showed mostly subtype B followed by subtypes F1, C and recombinants, mainly BF1. HIV-1 subtype C was identified only among pregnant women from cohort 2 which together with recombinants BC represented around 20% of the isolates. Subtype C and BC recombinants were isolated in interior municipalities of Goias state located close to the main highways that connect south/southern to north (BR153), northeast (BR020) and South/west (BR369/BR070). Phylogenetic/ phylogeographic analysis showed a subtype C clado, clusters (aLTR &#8805; 0.85) with sequences from Southern states and from Sao Paulo and evidences of multiple introductions. Conclusion: Our results indicate the importance of prenatal care for the early diagnosis/prevention of HIV-1 vertical transmission. However late diagnosis and missed opportunities to fully prevent transmission were associated with vertical transmission. Multiple introductions and the dissemination of HIV-1 subtype C by heterosexual contact in interior cities highlight the importance of monitoring the genetic diversity and the impact of subtype C dissemination in the interior of Brazil. Note: superscript + is where it appears and the program does not copy. / Introdução: O avanço da epidemia de aids em mulheres jovens e a transmissão materno-infantil do HIV-1 (TMI) representam importantes temas de saúde pública. Neste contexto, a assistência pré-natal representa uma oportunidade única para o diagnóstico da infecção pelo HIV-1 e implementação precoce de medidas profiláticas para TMI. Objetivos: Estudar as características imunológicas, virais, clínicas, epidemiológicas e identificar fatores associados à transmissão materno-infantil do HIV-1 entre gestantes infectadas pelo HIV-1/filhos recrutados no estado de Goiás. Material e métodos: Coorte 1: 41 pares mães HIV/aids-filhos (abril/2000-agosto/2001) recrutados e acompanhados prospectivamente em dois centros de referência regionais (Hospital Materno Infantil/HMI/SUS; Hospital Dr. Auar Auad/HAA/HDT/SUS). Coorte 2: 172 mães HIV/aids-149 filhos recrutados no Instituto de Diagnóstico e Prevenção/IDP/APAE e acompanhados prospectivamente no HAA/HDT/SUS. Foram avaliados viremia plasmática materna, contagem de células T CD4+, subtipos de HIV-1 nas regiões env/gag pelo ensaio da mobilidade de heteroduplex (HMA) para coorte 1 e sequenciamento gene pol (protease e transcriptase reversa-PR/RT) para identificar mutações de resistência aos antirretrovirais e subtipos do HIV-1 e análise filogeográfica das seqüências do subtipo C da coorte 2. As crianças filhas de mães HIV/aids foram submetidas a testes para quantificação do RNA HIV-1 plasmático e das células T CD4+. Nas crianças não infectadas a sororreversão foi acompanhada sequencialmente por ELISA para IgG anti HIV-1/2. Resultados: As pacientes da coorte 1 e 2 apresentaram características sócio-demográficas e clínicas semelhantes. A mediana de idade foi 26 anos (variação 15-41 anos), a maioria tinha baixa escolaridade e foi diagnosticada durante a gestação (90%). Mais de 80% recebeu profilaxia ARV para TMI. Na coorte 1 foi observado um caso de TMI associado a curta exposição à profilaxia e longo trabalho parto. Entre crianças expostas/nãoinfectadas a sororreversão foi mais rápida entre os nascidos de mães sintomáticas. A coorte 2 representou 80% do total de gestantes HIV-1+ do Estado de Goiás no período. A introdução precoce da profilaxia e viremia indetectável predominaram nas pacientes com diagnóstico anterior à gestação (p<0.05). Uma paciente virgem de tratamento apresentou resistência transmitida; 10 pacientes apresentaram resistência secundária: 6 sob profilaxia, 4 sob HAART. Entre os casos de TMI (3/149; 2.01%) observamos diagnóstico tardio, parto vaginal, amamentação e ausência do AZT oral e mutações de resistência não foram detectadas. Resultados do HMA (coorte 1) e do sequenciamento automatizado (coorte 2) em gestantes de Goiás mostraram a circulação dos subtipos B, F1 e recombinantes, principalmente BF1 nas regiões env/gag e pol do HIV-1. O subtipo C só foi detectado na coorte 2 e juntamente com os recombinantes BC representaram em torno de 20% dos isolados. HIV-1 subtipo C, originado do sul do país, foi detectado em gestantes de municípios do interior de Goiás por onde passam importantes vias de ligação sul-norte (BR153), sul-nordeste (BR020) e sulcentro-oeste/Mato Grosso (BR070/BR364). Análises filogenética/filogeográfica do subtipo C mostraram um clado monofilético formado por sequencias de Goias e da região Sul e de São Paulo e evidências de múltiplas introduções em Goiás. Conclusão: Nossos resultados indicam que o programa pré-natal de alta cobertura em Goiás representa uma importante oportunidade para diagnósttico e prevenção precoce de transmissão vertical do HIV-1. Entretanto os 3 casos de TMI observamos diagnóstico tardio e perda de oportunidade para a profilaxia completa da transmissão vertical do HIV-1. Múltiplas introduções e a disseminação do subtipo C por contato heterossexual no interior indicam a necessidade de monitoramento da diversidade genética e do impacto da disseminação do subtipo C no interior do Brasil. OBS: + está sobrescrita onde aparece e o programa não copia.