RESUMO
Bacillus thuringiensis Cry toxins have been widely used in the control of insect pests either as spray products or expressed in transgenic crops. These proteins are pore-forming toxins with a complex mechanism of action that involves the sequential interaction with several toxin-receptors. Cry toxins are specific against susceptible larvae and although they are often highly effective, some insect pests are not affected by them or show low susceptibility. In addition, the development of resistance threatens their effectiveness, so strategies to cope with all these problems are necessary. In this review we will discuss and compare the different strategies that have been used to improve insecticidal activity of Cry toxins. The activity of Cry toxins can be enhanced by using additional proteins in the bioassay like serine protease inhibitors, chitinases, Cyt toxins, or a fragment of cadherin receptor containing a toxin-binding site. On the other hand, different modifications performed in the toxin gene such as site-directed mutagenesis, introduction of cleavage sites in specific regions of the protein, and deletion of small fragments from the amino-terminal region lead to improved toxicity or overcome resistance, representing interesting alternatives for insect pest control.
Assuntos
Endotoxinas/farmacologia , Animais , Bacillus thuringiensis/química , Quitinases/farmacologia , Sinergismo Farmacológico , Insetos/efeitos dos fármacos , Inseticidas/farmacologia , Controle Biológico de Vetores , Proteínas Recombinantes de Fusão/farmacologia , Inibidores de Serina Proteinase/farmacologiaRESUMO
The mass media are recognized by many social scientists as important sources of medical information for lay people and as a positive influence on those working in the health care professions. However, there is a lack of study about print and mass media reporting on major health problems in developing countries such as Mexico. This article presents the findings of a study conducted to identify specific messages that the Mexican print media convey to the general reader about chronic diseases, especially one of the most important and pervasive, diabetes. We undertook a comprehensive review and content analysis of secondary source media reporting in the Boletin (Bulletin)--published by the Department of Education and Health, Universidad Autónoma Metropolitana, Xochimilco. The Boletin summarizes all articles related to health matters published in 12 national daily newspapers and 3 magazines. Our study covered all issues of the Boletin from 1992 through 1996. Our findings indicate that at times the press and popular print media disseminate an incomplete and often biased picture of chronic diseases prevalent in Mexico. Specifically, the press gives equal or more important coverage of acute diseases, or to AIDS, than to other major chronic conditions. The press also reproduces the biomedical model of disease and does not address topics important to certain segments of the population, including the patient. Moreover, the media may present an overly idealized impression of the capability of health services. Consequently, this failure to address the issues of certain widespread, chronic illnesses is severe enough to ask about the role of the press in medical health care reform. We conclude by suggesting areas for further research.
Assuntos
Bibliometria , Doença Crônica/epidemiologia , Jornalismo Médico/normas , Humanos , Serviços de Informação , Meios de Comunicação de Massa , México/epidemiologia , Controle de Qualidade , Estudos RetrospectivosRESUMO
The effect of Fasciola hepatica parasite burden on the detection of excretory/secretory (E/S) antigens in sera and feces of experimentally infected sheep was evaluated using a double antibody-based capture enzyme-linked immunosorbent assay (ELISA). Four groups of five sheep each were used. The first three groups were infected with 50, 100 and 200 metacercariae of F. hepatica, and the fourth group remained as non-infected control. On the day of infection and weekly thereafter, serum and fecal samples were taken. ELISA detected F. hepatica E/S antigen levels in serum from the first week post-infection (wpi) and in fecal supernatant from the fourth wpi, which were significantly (p<0.05) higher than controls. F. hepatica eggs were not detected until after the eighth wpi. The correlation between absorbance of E/S antigens in serum with the fluke burden was 0.77 (p<0.0001) and in feces 0.76 (p<0.0001) at 12th wpi. The sensitivity of the assay to detect E/S antigens in serum was 86.6% and in feces 93.3%. It is concluded that the ELISA technique used in this study offers a diagnostic alternative for detecting early infections of F. hepatica in sheep.
Assuntos
Antígenos de Helmintos/análise , Fasciola hepatica/imunologia , Fezes/parasitologia , Doenças dos Ovinos/parasitologia , Animais , Antígenos de Helmintos/sangue , Ensaio de Imunoadsorção Enzimática/veterinária , Fígado/parasitologia , Contagem de Ovos de Parasitas/veterinária , Sensibilidade e Especificidade , OvinosAssuntos
Síndrome de Beckwith-Wiedemann/genética , Doenças em Gêmeos , Criança , Feminino , Humanos , LactenteRESUMO
Se presentan los casos clinicos de tres hermanas, dos de ellas gemelas, fallecidas a corta edad y una tercera hermana de doce anos de edad procedentes de embarazos de la misma madre con diferentes padres. Los tres casos presentan rasgos sugerentes del Sindrome de Beckwith-Wiedeman. Se discutem algunos hechos de la transmision genetica de este cuadro