D-Lysine hydrochloride

The objective of this experiment was to test the hypothesis that the physiological state of lactation is accompanied by both an increase in total plasma lysine flux (rate of loss and replacement of lysine) and a net reduction in flux through the plasma lysine pool after accounting for lysine secreted in the milk. Eight lactating French Alpine does were primed and infused for three hours with solutions of alpha15N L-lysine HCl in 0.9% saline through indwelling jugular vein catheters. Enrichment of circulating plasma lysine by continuous intravenous infusion of alpha15N L-lysine was used to estimate whole body lysine flux. This procedure was repeated one month after cessation of milking. Total plasma lysine flux was similar for dry and lactating does (116.6 and 123.0 mmol/d, SEM 16.6 mmol), but 54.2 mmol/d lysine was secreted as milk protein during lactation. Direct measurement of lysine absorption from the lower tract and independent measurement of lysine degradation are needed to provide a more complete portrait of caprine lysine kinetics.

Apart from their pivotal roles in anabolic protein synthesis, cationic amino acids, particularly, L-lysine HCl and its oligomers, up to molecular weight 1000, showed a remarkable property of cellular growth stimulation both in vitro and in vivo. L- and D-Lysine HCl, at a maximal stimulatory concentration of 7 microg/mL of added load of the amino acid, supported a characteristic time-scaled cellular expansion in vitro, and L-lysine-mediated cell expansion in batch cultures always showed a stimulation index (S.I.) ranging up to approximately 35, compared with the matched control populations. Variable S.I. was possibly due to factors such as seeding density, type of media additives, number of passages the cells have undergone before being stimulated, etc. Beyond and before maximal stimulatory concentration of the amino acid, there is a sharp decline in the cellular growth-promoting activity of monomeric L-lysine HCl in vitro, thereby showing a clear concentration window for maximum cellular growth promotion.

Broiler chicks were provided choices of synthetic diets (a) adequate or low in lysine, and (b) adequate in or devoid of lysine. In each case, chicks consumed some of each diet offered, but preference was shown for the adequate lysine diet. Growth rates of chicks given choices ranged from 80% of that of chicks fed an adequate lysine diet with no choice for two weeks, then growth rates fell to about 60% of those fed adequate lysine. In another study, chicks were fed a diet devoid of lysine but were offered pure L-lysine HCl in a separate feeder. These chicks selected some of the supplementary lysine, but their body weights were only 68% of the body weight of chicks fed an adequate lysine diet after 21 days. Chicks given a choice of diets prepared with an adequate quantity of either L- or D-lysine preferred with L-lysine diet but did not select sufficient quantity to reach normal growth. These observations indicate that chicks can discern the presence of L-lysine in diets or separately, but will not select sufficient quantity for maximum growth potential.

In situ DNA hybridization is becoming rapidly an important technique for detection and typing of human papillomaviruses (HPV) in epithelial lesions, some of which (those due to HPV 16, 18 and 31) seem to possess an increased risk for progression into an invasive squamous cell carcinoma. An improved in situ DNA hybridization technique (Technique II) was described, and the results obtained in a series of cervical and penile HPV lesions were compared with those given by the in situ hybridization technique (Technique I) previously used in our laboratory. Special emphasis was made to increase the sensitivity with three basic alterations of the hybridization protocol; omission of the 0.2 N HCl wash, use of increased proteinase K concentration (from 50 micrograms/ml to 1 mg/ml), and elevated denaturation temperature (obtained by a heating block instead of an incubator). Poly-D-lysine as a slide-coating medium was replaced by Kodak Photo-Flo 200 to improve the attachment of the tissue sections on the slides.