Association of Mycobacterium tuberculosis PE PGRS33 polymorphism with clinical and epidemiological characteristics.
ABSTRACT There is evidence that some members of the Mycobacterium tuberculosis PE PGRS gene subfamily, including PE PGRS33, may have a specific function in M. tuberculosis persistence. The impact of naturally-occurring PE PGRS33 genetic variations on the virulence and transmissibility of clinical M. tuberculosis isolates is not known. We used PCR and DNA sequencing to identify genetic variations in the PE PGRS33 gene in comparison with the sequenced laboratory strain, H37Rv, among 649 isolates from a population-based sample. The PE PGRS33 alleles were placed into two groups, based on the effect of the sequence variations on the PE PGRS33 protein, and their associations with clinical and epidemiological characteristics were assessed using multivariate logistic regression to control for potential confounding of host-related factors. Of the 639 isolates for which sequence data were obtained, 139 (21.8%) had PE PGRS33 alleles that would result in a significant change to the PE PGRS33 protein due to large insertions/deletions or frameshift mutations. These isolates were significantly associated with clustering based on genotype and absence of cavitations in the lungs, compared to isolates having PE PGRS33 alleles that would result in no or minimal change to the PE PGRS33 protein. The association of significant changes to PE PGRS33 with clinical and epidemiological characteristics suggests that PE PGRS33 may have an important role in M. tuberculosis persistence.
Article: Long-term adequacy of exclusive breast-feeding: how scientific research has led to revised opinions.[show abstract] [hide abstract]
ABSTRACT: The present paper reviews the research of the authors and their colleagues over the past 20 years to provide improved nutritional and anthropometric guidelines for the assessment of lactational adequacy and for when the weaning process might be initiated. The nutritional guidelines are based on revised dietary energy requirements. The basic assumption is that since breast milk is a well-balanced food, if energy needs are satisfied so will those for essential nutrients. Energy requirements for young babies have been derived from the application of the doubly-labelled-water technique. This approach indicated that 460 kJ (110 kcal)/kg per d at 1 month and 397 and 355 kJ (95 and 85 kcal)/kg per d at 3 and 6 months respectively would be satisfactory for a nutrient content of high bioavailability. Translated into a breast-milk intake of 850 ml/d the latter would cover the dietary energy needs of the average child growing along the 50th centile until at least 4 months, but the typical child from many developing countries following the 25th centile until 6 months. The importance of revised growth reference values for infancy, equally crucial for assessing lactational adequacy, is also reviewed. In contrast with the shapes of earlier reference patterns, growth trajectories are different when babies are fed in accordance with modern paediatric advice. Mothers and health professionals using the older growth charts to assess the progress of a baby can be misled into assuming that the weaning process needs to be introduced sooner than necessary. Examples of this situation within the context of a developing country are provided.Proceedings of The Nutrition Society 03/2000; 59(1):17-23. · 2.77 Impact Factor