Diffusion-weighted MR imaging is highly accurate for diagnosing stroke within 6 hours of symptom onset and is superior to CT and conventional MR imaging.

The rapid growth of infant brains places an exceptionally high demand on the supply of nutrients from the diet, particularly for preterm infants. Sialic acid (Sia) is an essential component of brain gangliosides and the polysialic acid (polySia) chains that modify neural cell adhesion molecules (NCAM). Sia levels are high in human breast milk, predominately as N-acetylneuraminic acid (Neu5Ac). In contrast, infant formulas contain a low level of Sia consisting of both Neu5Ac and N-glycolylneuraminic acid (Neu5Gc). Neu5Gc is implicated in some human inflammatory diseases. Brain gangliosides and polysialylated NCAM play crucial roles in cell-to-cell interactions, neuronal outgrowth, modifying synaptic connectivity, and memory formation. In piglets, a diet rich in Sia increases the level of brain Sia and the expression of two learning-related genes and enhances learning and memory. The purpose of this review is to summarize the evidence showing the importance of dietary Sia as an essential nutrient for brain development and cognition.

Human milk, including milk from mothers of preterm infants, is a rich source of oligosaccharide-bound sialic acid, which contrasts with the relatively small amounts found in infant formulas. The nutritional significance of sialic acid is presently unknown, but it is plausible that it is a conditional nutrient that contributes to sialic acid accretion in the brain.

The gastrointestinal tract of mammals contains a complex microbial community that influences numerous aspects of health and development. It is postulated that establishment of this community during early life has long-term consequences on the health status of adults. Potential influences on colonization are expected to include environmental microbes, diet and the developmental changes of the host. Denaturing gradient gel electrophoresis was used to follow the individual community dynamics of 24 piglets over the period of 3-36 days after birth. The community of piglets older than 31 days was inferred to show high stability relative to the first 28 days post birth. The stable day 36 community showed significant correlation between cohabiting piglets, but not between siblings. This cohabitation effect was not observable in 1-or 2-week-old piglets but was strongest at either 3 or 4 weeks post birth. The onset of this change after 2 weeks is predicted to be after the development of key induction elements of the immune system and before significant levels of piglet sIgA were observable (4 weeks). The outcome is altered community dynamics that result in significant similarity between the stable communities that develop in cohabiting pigs. We conclude that for a finite period in their development, the outcome of gut colonization in piglets is greatly influenced by the immediate environment. The implication is that mammals have a developmental window, in which the developing host-gut microbiota interaction will be simultaneously more amenable to engineering and more susceptible to disturbance.

The structure of cationic lipids is a major factor for their transfection activity. A cationic lipid generally contains four functional domains: a hydrophilic headgroup, a linker, a backbone domain, and a hydrophobic domain. The structure of the hydrophobic domain determines the phase transition temperature and the fluidity of the bilayer and influences the stability of liposomes, the DNA protection from nucleases, the endosomal escape, the DNA release from complex, and the nuclear penetration. Also, toxicity of the lipids is influenced by the hydrophobic domain. The compounds used for gene delivery are classified according to the structure of the hydrophobic domain as follows: aliphatic chains, steroid domain, and fluorinated domain. In this review, we summarized recent research results concerning the structures of the hydrophobic domain, in order to find the effect of the hydrophobic domain on transfection efficiency. Understanding these would be very important for scientists to prepare novel cationic lipids and design novel formulations with high transfection efficiency.

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The early stages of neurodevelopment in infants are crucial for establishing neural structures and synaptic connections that influence brain biochemistry well into adulthood. This postnatal period of rapid neural growth is of critical importance for cell migration, neurite outgrowth, synaptic plasticity, and axon fasciculation. These processes thus place an unusually high demand on the intracellular pool of nutrients and biochemical precursors. Sialic acid (Sia), a family of 9-carbon sugar acids, occurs in large amounts in human milk oligosaccharides and is an essential component of brain gangliosides and sialylated glycoproteins, particularly as precursors for the synthesis of the polysialic acid (polySia) glycan that post-translationally modify the cell membrane-associated neural cell adhesion molecules (NCAM). Human milk is noteworthy in containing exceptionally high levels of Sia-glycoconjugates. The predominate form of Sia in human milk is N-acetylneuraminic acid (Neu5Ac). Infant formula, however, contains low levels of Sia consisting of both Neu5Ac and N-glycolyneuraminic acid (Neu5Gc). Current studies implicate Neu5Gc in several human inflammatory diseases. Polysialylated NCAM and neural gangliosides both play critical roles in mediating cell-to-cell interactions important for neuronal outgrowth, synaptic connectivity, and memory formation. A diet rich in Sia also increases the level of Sia in the brains of postnatal piglets, the expression level of 2 learning-related genes, and enhances learning and memory.

Background and Purpose-We sought to characterize the evolution of acute ischemic stroke by MRI and its relationship to patients' neurological outcome. Methods-Fourteen patients with acute ischemic stroke underwent MRI within 13 hours of symptom onset (mean, 7.4Ϯ3 hours) and underwent repeated imaging and concurrent neurological examination at 8, 24, 36, and 48 hours and 7 days and Ͼ42 days after first imaging. Results-Diffusion-weighted imaging (DWI) lesion volumes increased between the first and second scans in 10 of 14 patients; scans with maximum DWI lesion volume occurred at a mean of 70.