Controlo químico de infestantes

Uma planta é considerada infestante quando nasce espontaneamente num local e momento indesejados, podendo interferir negativamente com a cultura instalada. As infestantes competem com as culturas para o espaço, a luz, água e nutrientes, podendo atrasar e prejudicar as operações de colheita, depreciar o produto final e assegurarem a reinfestação nas culturas seguintes. Dado o modo de propagação diferenciado das diversas espécies de infestantes, com as anuais a propagarem-se por semente e as perenes ou vivazes a assegurarem a sua propagação através de órgãos vegetativos (rizomas, bolbos, tubérculos, etc.), assim, também o seu controlo quer químico, quer mecânico terá que ser diferenciado, ou seja, para controlar infestantes anuais será suficiente destruir a sua parte aérea, enquanto para controlar infestantes perenes teremos que destruir os seus órgãos reprodutivos. O controlo de infestantes poderá ser químico, através da utilização de herbicidas, ou mecânico pela utilização de alfaias agrícolas, tais como a charrua de aivecas, a charrua de discos, a grade de discos, o escarificador e a fresa. Quando a técnica utilizada na instalação das culturas é a sementeira directa, o controlo das infestantes terá que ser obrigatoriamente químico, enquanto se o recurso à mobilização do solo for a técnica mais utilizada (sistema de mobilização tradicional ou sistema de mobilização reduzida), o controlo das infestantes tanto poderá ser químico como mecânico. Neste trabalho iremos abordar apenas, o controlo químico de infestantes

BCG vaccination in patients with severe combined immunodeficiency: Complications, risks, and vaccination policies

BACKGROUND: Severe combined immunodeficiency (SCID) is a syndrome characterized by profound T-cell deficiency. BCG vaccine is contraindicated in patients with SCID. Because most countries encourage BCG vaccination at birth, a high percentage of patients with SCID are vaccinated before their immune defect is detected. OBJECTIVES: We sought to describe the complications and risks associated with BCG vaccination in patients with SCID. METHODS: An extensive standardized questionnaire evaluating complications, therapeutics, and outcomes regarding BCG vaccination in patients given a diagnosis of SCID was widely distributed. Summary statistics and association analysis was performed. RESULTS: Data on 349 BCG-vaccinated patients with SCID from 28 centers in 17 countries were analyzed. Fifty-one percent of the patients had BCG-associated complications, 34% disseminated and 17% localized (a 33,000- and 400-fold increase, respectively, over the general population). Patients receiving early vaccination (≤1 month) showed an increased prevalence of complications (P = .006) and death caused by BCG-associated complications (P < .0001). The odds of experiencing complications among patients with T-cell numbers of 250/μL or less at diagnosis was 2.1 times higher (95% CI, 1.4-3.4 times higher; P = .001) than among those with T-cell numbers of greater than 250/μL. BCG-associated complications were reported in 2 of 78 patients who received antimycobacterial therapy while asymptomatic, and no deaths caused by BCG-associated complications occurred in this group. In contrast, 46 BCG-associated deaths were reported among 160 patients treated with antimycobacterial therapy for a symptomatic BCG infection (P < .0001). CONCLUSIONS: BCG vaccine has a very high rate of complications in patients with SCID, which increase morbidity and mortality rates. Until safer and more efficient antituberculosis vaccines become available, delay in BCG vaccination should be considered to protect highly vulnerable populations from preventable complications.Fil: Gómez Raccio, Andrea C.. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños ; ArgentinaFil: Orellana, Julio Cesar. Provincia de Córdoba. Hospital de Niños de la Santísima Trinidad. División de Alergia e Inmunología Clínica; ArgentinaFil: Liberatore, Diana. Hospital Italiano; ArgentinaFil: Bezrodnik, Liliana. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños ; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Marciano, Beatriz E.. National Institutes of Health; Estados UnidosFil: Huang, Chiung Yu. National Institutes of Health; Estados UnidosFil: Joshi, Gyan. National Institutes of Health; Estados UnidosFil: Rezaei, Nima. Teheran University of Medical Sciences. Children's Medical Center Hospital. Pediatric Center of Excellence; IránFil: Costa Carvalho, Beatriz. Federal University of São Paulo; BrasilFil: Cunha, Luciana. Federal University of Minas Gerais; BrasilFil: Pinto, Jorge A.. Federal University of Minas Gerais; BrasilFil: Espinosa Padilla, Sara E.. Secretaría de Salud. Instituto Nacional de Pediatría; MéxicoFil: Hernandez Nieto, Leticia. Secretaría de Salud. Instituto Nacional de Pediatría; MéxicoFil: Elfeky, Reem A.. Ain Shams University; EgiptoFil: Ariga, Tadashi. Hokkaido University Graduate School of Medicine; JapónFil: Toshio, Heike. Kyoto University Hospital; JapónFil: Dogu, Figen. Ankara University Medical School; TurquíaFil: Cipe, Funda. Ankara University Medical School; TurquíaFil: Formankova, Renata. Charles University; República Checa. University Hospital Motol; República ChecaFil: Nuñez Nuñez, M. Enriqueta. Western National Medical Center; MéxicoFil: Gonçalo Marques, Jose. Santa María Hospital. Lisbon Academic Center; PortugalFil: Pereira, María I.. Provincia de Córdoba. Hospital de Niños de la Santísima Trinidad. División de Alergia e Inmunología Clínica; ArgentinaFil: Listello, Viviana. Provincia de Córdoba. Hospital de Niños de la Santísima Trinidad. División de Alergia e Inmunología Clínica; ArgentinaFil: Slatter, Mary A.. Great North Children's Hospital; Reino UnidoFil: Nademi, Zohreh. Great North Children's Hospital; Reino UnidoFil: Kowalczyk, Danuta. Children's University Hospital. Department of Clinical Immunology and Transplantology; PoloniaFil: Fleisher, Thomas A.. National Institutes of Health; Estados UnidosFil: Davies, Graham. Great Ormond Street Hospital for Children; Reino UnidoFil: Neven, Bénédicte. Necker Hospital. Immunology-Hematology and Rheumatology Service; FranciaFil: Rosenzweig, Sergio D.. National Institute of Health. National Institute of Allergy and Infectious. Laboratory of Host Defenses. Primary Immunodeficiency Clinic and Infectious Diseases Susceptibility Unit; Estados Unido