RESUMO
OBJECTIVES: The goals of these studies were to characterize the interaction of the P22 phage particle with the Salmonella cell surface and to determine the phage elements involved in this interaction by mutational analysis. BACKGROUND: The phage P22 has been characterized extensively. The gene and protein for the phage P22 tailspike, which is the phage adsorption organelle, have been intensively studied. The kinetics of the interaction of the tailspike protein with the cell surface has been studied in detail, surprisingly no mutational analysis has ever been reported that has defined these components and their interaction between themselves and the cell surface. The main and perhaps only component needed for this cell surface interaction is the tailspike protein. METHODS: Adsorption to the cell surface has been measured in the wild type phage and in mutant derivatives, isolated in this study. Phage mutants have been isolated after hydroxylamine mutagenesis. RESULTS: The adsorption of P22 to the cell surface is a temperature-independent event. Forty putative phage adsorption mutants have been isolated. A sample of them have been further analyzed. These divide the adsorption process into at least two stages. One stage contains mutants that absorb with essential wild type phage kinetics to the cell surface while the other stage with delayed adsorption kinetics. CONCLUSIONS: The interaction of the phage P22 with the Salmonella cell surface has been shown to be a complicated one which is temperature-independent and multi-stage. Mutants isolated in this study may help dissect this process even further
Assuntos
Humanos , Adsorção , /metabolismo , Salmonella typhimurium/virologia , /ultraestrutura , Lipopolissacarídeos/metabolismo , Proteínas da Cauda Viral/metabolismo , Salmonella typhimurium/metabolismo , Salmonella typhimurium/ultraestrutura , TemperaturaRESUMO
We evaluated the results of transfer of the tibialis anterior in the management of calcaneus deformity in young patients who had myelodysplasia; fifteen patients (twenty-two feet) were operated on between 1978 and 1985. The neural deficit was at the fourth and fifth lumbar levels. The average age at the time of the operation was seven years and two months (range, two to nineteen years). The average age at the latest follow-up was thirteen years (range, five to twenty-four years). The average duration of follow-up was five years and ten months (range, two to eleven years). Seventeen feet (twelve patients) had a good result (no ulceration of the heel or osteomyelitis and correction of the calcaneus deformity), and five feet (three patients) had a poor result (persistent ulceration, signs of osteomyelitis, recurrent or persistent calcaneus deformity, or the need for additional operative intervention). Children who were less than five years old had a better outcome, as determined by the Fisher exact test (p less than 0.5).
Assuntos
Calcâneo/anormalidades , Calcâneo/cirurgia , Defeitos do Tubo Neural/complicações , Transferência Tendinosa/métodos , Adolescente , Criança , Pré-Escolar , Seguimentos , Humanos , Satisfação do Paciente , Resultado do TratamentoRESUMO
Recent literature reports an apparent decline in the incidence of neural tube defects throughout the world. A revision of stillbirth certificates and surgical reports of closure procedures for open neural tube defects was done in order to establish the incidence and its trend during a nine year period in Puerto Rico. The current prevalence of the syndrome was estimated using the death certificates in addition to the fore-mentioned surgical reports. Our results indicate that Puerto Rico carries probably the highest incidence of the US territories and that the trend is not declining one.