Interaction of L-glutamic acid with human T-lymphocytes

A specific interaction of [3H]Glu with T lymphocytes from the blood of healthy donors (Kd = 0.236 microM) was revealed and described. It was found that unlabeled quisqualate, a structural analogue of L-glutamic acid, and unlabeled dipeptides Ala-Glu, Glu-Ala, and Glu-Glu competitively inhibit the specific binding of [3H]Glu to T lymphocytes (with Ki 0.19, 2.4, 3.4, and 1.2 microM, respectively). Binding experiments with conjugates of labeled and unlabeled glutamic acid with dextran showed that the receptors of [3H]Glu are localized on the outer surface of the plasma membrane of T lymphocytes.     

Sequence analysis of small cryptic plasmids isolated from Selenomonas ruminantium S20

The degradation kinetics of five glutamine dipeptides in aqueous solution, i.e. glycyl-L-glutamine (Gly-Gln), L-alanyl-L-glutamine (Ala-Gln), L-valyl-L-glutamine (Val-Gln), L-leucyl-L-glutamine (Leu-Gln) and L-isoleucyl-L-glutamine (Ile-Gln), were studied. Stability tests were performed using a stability-indicating high-performance liquid chromatographic assay. Two different Ala-Gln degradation routes, i.e. the cleavage of a peptide bond and the deamination of an amide group, were observed. The degradation was adequately described by pseudo-first-order kinetics. The maximum stability of Ala-Gln was obtained at an approximate pH of 6.0. The pH-rate profile described by specific acid-base catalysis and hydrolysis by water molecules agreed with the experimental results. The activation energy of Ala-Gln at pH 6.0 was determined to be 27. 1kcal mol-1, and the shelf-life (90% remaining) at 25 and 40 degrees C was predicted to be 5.3 years and 7.1 months, respectively. The rate constants of the glutamine dipeptides were influenced by the N-terminal amino acid residue and decreased in the order: Gly-Gln, Ala-Gln, Leu-Gln, Val-Gln and Ile-Gln.     

Comparison of methods to enumerate bacteria in dental unit water lines

Millipore HPC samplers are simple, self-contained test devices that can be used by personnel in dental offices who do not have microbiologic training to easily and economically monitor dental unit water quality without laboratory support. This study evaluated the correlation of HPC samplers to R2A agar for enumerating planktonic bacteria in dental unit treatment water. Eight different dental units were sampled. Five replicates were performed for each media at each dilution. The Pearson correlation coefficient between the R2A agar and HPC sampler is 0.89. These data suggest HPC samplers correlate with conventional laboratory-based R2A culture techniques for determining dental unit water line contamination.