Impact of folic acid supplementation on single- and double-stranded RNA degradation in human colostrum and mature milk.

Sufficient intake of folic acid is necessary for normal embryogenesis, fetal, and neonatal development. Folic acid facilitates nucleic acid internalization, and protects cellular DNA from nuclease degradation. Human milk contains enzymes, antimicrobial proteins, and antibodies, along with macrophages, that protect against infections and allergies. However, little to no information is available on the effects of folic acid supplementation on degradation of nucleic acids in human milk. In the present study, we aimed to determine the RNase activity (free and inhibitor-bound) in colostrum and mature milk, following folic acid supplementation. The study design included a total of 59 women, 27 of whom received 400 µg of folic acid daily periconceptionally and after. Folic acid supplementation increased the free RNase and polyadenylase activity following lactation. However, the increased RNase activity was not due to de novo enzyme synthesis, as the inhibitor-bound (latent) RNase activity was significantly lower and disappeared after one month. Folic acid reduced RNase activity by using double-stranded RNA as substrate. Data suggests that folic acid supplementation may improve viral RNAs degradation and mRNA degradation, but not dsRNA degradation, preserving in this way the antiviral defense.

Alkaline phosphatase activity in human colostrum as a valuable predictive biomarker for lactational mastitis in nursing mothers.

AIMS: Biochemical investigations have shown that an indigenous milk enzyme - alkaline phosphatase (ALP) - which is detectable in the lactocytes, plays a very important diagnostic role in clinical medicine, since its activity varies in different tissues and serves as a specific indicator of disease states. The purpose of this study was to evaluate ALP activity in human colostrum as a possible early predictive biomarker for lactational mastitis in nursing mothers. PATIENTS & METHODS: During a period from May to July 2010, a total of 60 healthy nursing mothers were recruited for this study. RESULTS: The mean level of colostrum ALP activity from the affected breasts was significantly higher when compared with ALP activity from the contralateral asymptomatic as well as 'healthy' breasts (p < 0.01). CONCLUSION: Determining ALP activity in colostrum could be a valuable biochemical marker for an early prediction of mastitis in nursing mothers.

Arginase activity in human milk during the first month of lactation.

Arginase (L-arginine amidinohydrolase, EC 3.5.3.1) is the key enzyme in urea synthesis, hydrolyzing L-arginine into L-ornithine and urea. Arginase modulates levels of nitric oxide, creatine, and creatinine, likely by regulating intracellular L-arginine availability. The objective of the present study was to determine the arginase activity and concentration of urea and creatinine in colostrum and mature human milk obtained from nursing mothers. Our longitudinal biochemical analyses show that arginase activities and urea concentrations were the highest at the first day of lactation (colostrum). The decreasing enzyme activity and urea start at the second day, remaining at this level until the end of the first month of lactation (30th day). The concentration of creatinine in human colostrum and mature milk did not significantly change. The alteration of arginase activity between colostrum and mature milk may be a consequence of the transfer of arginase from the blood of the breast mother mammary glands into the colostrum and mature milk. The concentration of nutrients in colostrum and mature milk undergo alterations, probably to satisfy the requirements of the nursing infant for arginine, essential amino acids for human body growth, and normal physiology.