Leche materna: características funcionales de los oligosacáridos de la leche materna (Parte 2) / Breast milk: functional characteristics of breast milk oligosaccharides (Part 2)

Durante los primeros meses de vida, los oligosacáridos de la leche materna (HMOs) aportados por la leche materna participan en procesos asociados con la maduración de tejidos y sistemas del tubo digestivo, modulan algunos de sus procesos metabólicos y ejercen efectos prebióticos y antimicrobianos. Otros efectos estudiados son su contribución a la instalación, desarrollo y estimulación de la microbiota residente con predomino de Bifidobacterium y Bacteroides, con efectos protectores frente a posibles colonizaciones o patologías por enteropatógenos (bacterianas, virus o parásitarias) que pueden actuar nivel local en el tubo digestivo, pero también pueden influir a nivel sistémico. Los HMOs modularían el desarrollo de la inmunidad innata y adaptativa, y probablemente previenen el desarrollo de fenómenos de atopia/alergia. Una patología propia de la etapa neonatal de los prematuros es la enterocolitis necrosante y algunos HMOs podrían disminuir el riesgo de su manifestación. Las actividades de los oligosacáridos de la leche materna contribuyen a la adaptación del lactante a los desafíos que plantea su entorno incluyendo la prevención de algunas patologías en edades posteriores, como es el caso de la diabetes tipo 1 y la obesidad.

During the first months of life, breast milk oligosaccharides (HMOs) stimulate development of the gastrointestinal tract in newborns and young infants; they modulate its metabolism and transport capabilities. Additionally, they exert prebiotic and antimicrobial activities and contribute to the development of the resident intestinal microbiota with a predominance of Bifidobacterium and Bacteroides and protect from colonization and infections by enteropathogens (bacteria, virus or parasites). It is highly probable that their activities extend beyond infancy and persist into adult life. HMOs stimulate the development of the innate and adaptive immune systems and decrease the risk of atopy/allergy. Their intake has been associated with a degree of protection against as necrotizing enterocolitis among premature infants. HMOs contribute to the long term adaptation and protection of newborn infants to unfavorable conditions of their environment and in this way may contribute to protect breastfed infants from type 1 diabetes and obesity.

Oligosacáridos de la leche humana. Papel en la salud y en el desarrollo del lactante / Human milk oligosaccharides. The rule in the health and development of the infants

Breast-feeding is the optimal mode of feeding for the normal full-term infant. Human milk composition knowledge has been basis for recommended dietary allowances for infants. Few studies about human milk carbohydrates have been done until the last decade. However, carbohydrates provide approximately 40-50 of the total energy content of breast milk. Quantitatively oligosaccharides are the third largest solute in human milk after lactose and fat. Each individual oligosaccharide is based on a variable combination of glucose, galactose, sialic acid, fucose and N-acetylglucosamine with many and varied linkages between them, thus accounting for the enormous number of different oligosaccharides in human milk. The oligosaccharides content in human milk varies with the duration of lactation, diurnally and with the genetic makeup of the mother. At present, a great interest in the roles of human milk oligosaccharides is raising. They act as a the soluble fibre in breast milk and their structure is available to act as competitive ligands protecting the breast-fed infant from pathogens and act as well as prebiotic. They may also act as source of sialic acid and galactose, essential for brain development. This is why today there is an increasing health and industrial interest in human milk oligosaccharides content, with the main purpose of incorporating them as new ingredients in infant nutrition.

Aspectos funcionais da glicosilacao de um receptor de laminina de melanoma murino / Functional aspects of the glycosylation in the receptor of laminin of murine melanoma

A interacao entre a laminina e gp120 140, uma proteina de celulas B16-F10, imunoquimicamente relacionada a alfa-6 beta-1 integrina, e dependente de oligossacaridios N-ligados presentes no receptor. Analise com lectinas de especificidades conhecidas permitiu concluir que gp120/140 e uma sialoglicoproteina, apresentando principalmente complexos antenarios, entre as estruturas N-ligadas. Ainda, foi possivel mostrar que gp120/140 apresenta residuos de alfa-galactose terminais. Por meio de tratamento com exoglicosidases, foi possivel mostrar que residuos alfa-gal presentes na cadeia alfa sao determinantes da interacao com laminina, em ensaios de ligand blotting. Estes residuos estao associados ao fenomeno de adesao celular. De outro lado, a cadeia beta-1, apresenta complexos tri- e tetra-antenarios, cuja sintese pode ser inibida indiretamente por swainsonina. Estes complexos parecem estar associados ao fenomeno de espalhamento celular. Mostrou-se ser possivel modular as funcoes de adesao e espalhamento mediadas por integrinas modificando-se o estado de glicolisacao de suas cadeias