PubMed Health⌕ Search

Biomedical subjects

B E James

Publications and source records attributed to B E James.

14 recordsLinked to original sources
PubMed1990

Gene replacement and expression of foreign DNA in mycobacteria.

A system that permits molecular genetic manipulation of mycobacteria was developed on the basis of the yeast paradigm of gene replacement by homologous recombination. A shuttle vector that can replicate autonomously at a high copy number in Escherichia coli but must integrate into homologous DNA for survival in Mycobacterium smegmatis was constructed. The vector contains a ColE1 origin of replication, antibiotic resistance markers for ampicillin and kanamycin, a nutritional marker (pyrF) that allows both positive and negative selection in E. coli and M. smegmatis, and unique restriction sites that permit insertion of foreign DNA. Transformation of mycobacteria with this vector results in integration of its DNA into the genomic pyrF locus by either a single or a double homologous recombination event. With this system, the 65-kilodalton Mycobacterium leprae stress protein antigen was inserted into the M. smegmatis genome and expressed. This gene replacement technology, together with a uniquely useful pyrF marker, should be valuable for investigating mycobacterial pathobiology, for the development of candidate mycobacterial vaccine vehicles, and as a model for the development of molecular genetic systems in other pathogenic microorganisms.

Blotting, Southern↗
PubMed1979

Muscle protein degradation in premature human infants.

1. Myofibrillar protein degradation has been measured by the rate of 3-methylhistidine excretion in premature infants weighing between 635 g and 1295 g. Analyses were made in conjunction with 1--3 day nitrogen balance studies. 2. In 56 balance studies in 36 infants, total muscle protein breakdown varied between 0.70 and 2.58 (mean 1.05) g day-1 kg-1 body weight while the percentage of total muscle protein degraded each day was between 3.3 and 8.3 (mean 4.8). 3. Both total and fractional rates of protein breakdown showed highly significant negative correlations with nitrogen retention but no relationship to total energy input. 4. Protein degradation was higher than average in infants who were losing weight at the time of the balance study, lower in infants who were gaining weight and higher in those who died within 2 weeks of the analysis. 5. Myofibrillar protein breakdown was not different between infants fed orally and those receiving total parenteral nutrition. 6. Generally the effects of nitrogen and evergy status on muscle protein degradation in the premature infants are different from changes reported in adult human beings or adult rats. We suggest that this difference may be a consequence of the very limited energy reserves of the premature infant.

Aging↗