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Biomedical subjects

R Rueda

Publications and source records attributed to R Rueda.

At least 19 recordsLinked to original sources
PubMed2006

Ribonucleotides: conditionally essential nutrients shown to enhance immune function and reduce diarrheal disease in infants.

It remains a goal of pediatric nutrition to provide optimal nourishment for infants who are not fed human milk. Investigators have attempted to emulate the composition and functionality of human milk, the gold standard for infant nutrition. These efforts began with the analysis of milk components and continued with assessments of biological effects that culminated in clinical studies in infants. This chapter summarizes the path that researchers followed to study ribonucleotides and their role in infant nutrition. Based on analytical methods for the quantification of ribonucleotides in human milk, investigators assessed their potential impact on the immune systems of infants and looked for concomitant mechanistic explanations. These inquiries evolved into clinical trials in which ribonucleotide-supplemented formula performance was compared with that of non-supplemented formulas and with human milk. This chapter intends to summarize an area of pediatric nutrition that has yielded both enlightening evidence and seemingly contradictory data.

Diarrhea, Infantile↗
PubMed2001

Dietary gangliosides positively modulate the percentages of Th1 and Th2 lymphocyte subsets in small intestine of mice at weaning.

We studied the influence of dietary gangliosides on the number of spontaneous cytokine-secreting cells from two intestinal lymphocyte populations: lamina propria lymphocytes and Peyer's patches lymphocytes in Balb/c mice for 28 days after weaning. Weanling mice were separated into two groups, designated as Control and BG. The Control group was fed with a semipurified diet without gangliosides and the BG group was fed with the semipurified diet supplemented with 47 mg/kg of a mixture of bovine brain gangliosides. Intestinal lymphocytes were isolated from mice killed at 3, 7, 14 and 28 days after weaning, and the percentages of spontaneous Th1 as well as Th2 cytokine-secreting lymphocytes were determined using the ELISPOT assay. The BG group animals showed an earlier development in the number of cytokine-secreting cells, which appeared one week later in Control animals. In addition, mice fed with the ganglioside-supplemented diet showed a significantly higher number of Th1 and Th2 cytokine-secreting lymphocytes than Control mice in lamina propria and Peyer's patches lymphocytes at the end of the experimental period (28 days). Our results suggest that dietary gangliosides influence the maturation process of the intestinal immune system that take place during weaning.

Animals↗
PubMed2000

Weaning induces an increase in the number of specific cytokine-secreting intestinal lymphocytes in mice.

Intestinal immunity differs from systemic immunity in several aspects and is frequently studied separately. In this work we have analysed the frequency of mononuclear cells spontaneously secreting the cytokines IL-2, IL-4, IL-5, IL-6, IL-10, interferon gamma (IFN-gamma) and tumour necrosis factor (TNF-alpha), in Peyer's patches and lamina propria of small intestine in mice by enzyme linked immunosorbent spot (ELISPOT) during 1 month after weaning. We have found a high percentage of spontaneous Th(1)as well as Th(2)cytokine-secreting lymphocytes in both populations, Peyer's patches and lamina propria. An increase in the number of the lymphocytes secreting most of the studied cytokines, at 1 and 2 weeks after weaning, was also observed. These results suggest that the increase in the number of cytokine secreting lymphocytes may be one of the potential mechanisms involved in the development of the intestinal immune system at weaning.

Animals↗
PubMed2000

The development and construct validation of a Spanish version of an Academic Self-Concept scale for middle school Hispanic students from families of low socioeconomic levels.

For a sample of 305 6th, 7th and 8th grade students, of whom 95% was from economically disadvantaged Hispanic families and for whom English was their second language, evidence was sought regarding the reliability and construct validity of scores on a Spanish version of an academic self-concept measure entitled Dimensions of Self-Concept (DOSC), comprising five subscales bearing the same names as those of the five hypothesized constructs that they were intended to operationalize: Level of Aspiration, Anxiety, Academic Interest and Satisfaction, Leadership and Initiative, and Identification versus Alienation. Reliability estimates varying between .72 and .80 were judged to be reasonably satisfactory. Results from oblique factor analysis lent empirical support for the hypothesized constructs of Anxiety, Leadership and Initiative, and Identification versus Alienation. Scores associated with the subscales of Level of Aspiration and Academic Interest and Satisfaction generated a factor interpreted as a fusion of the two constructs of Level of Aspiration and Academic Interest and Satisfaction.

Achievement↗
PubMed1998

Addition of gangliosides to an adapted milk formula modifies levels of fecal Escherichia coli in preterm newborn infants.

Because some gangliosides bind bacteria, we tested the influence of supplementating an adapted milk formula with gangliosides, at a total concentration of 1.43 mg/100 kcal, on the fecal microflora of preterm infants. At all sampling times, feces from infants fed with ganglioside-supplemented formula had significantly lower relative content of Escherichia coli than feces from infants fed with control milk formula: the difference was especially significant at age 7 days postnatal < .001). At age 30 days postnatal, fecal bifidobacterial counts were higher in infants fed with ganglioside-supplemented formula (P < .05). We conclude that gangliosides at concentrations present in human milk significantly modify the fecal flora.

Escherichia coli↗
PubMed1998

Neonatal dietary gangliosides.

Gangliosides are glycosphingolipids that are widely distributed in vertebrate tissues and body fluids and which are specially abundant in neural tissues. Milk from different species has a particular ganglioside content and profile. Human milk has a higher content of gangliosides than bovine milk. GD3 and GM3 are the predominant individual gangliosides in bovine milk. In human colostrum GD3 is also the main ganglioside whereas in human mature milk GM3 predominates over the other gangliosides. Human milk also contains GM1 and a number of highly polar gangliosides, which may play an important role in infant physiology. GM1 has been shown to inhibit Escherichia coli and Vibrio cholerae enterotoxins. We have found that a ganglioside-supplemented infant formula modifies the intestinal ecology of preterm newborns, increasing the Bifidobacteria content and lowering that of Escherichia coli. Although the exact mechanism by which dietary gangliosides reduce the fecal content of Escherichia coli is unknown, in vitro experiments suggest that they may act as false intestinal receptors for some strains of this bacteria. Since GD3 and other gangliosides have been involved in mechanisms of lymphocyte activation and differentiation, dietary gangliosides might have a function in intestinal immunity development.

Animals↗
PubMed1998

Gestational age and origin of human milk influence total lipid and fatty acid contents.

The human milk composition may be influenced by several factors, such as gestational age or genetic characteristics and dietary habits of different populations. To analyze the total lipid and fatty acid contents of human milk, we have conducted two studies, one on mothers who had delivered preterm and term newborns and another on mothers from two different sociocultural backgrounds (Spain and Panama). The total lipid content (g/100 g wet weight) was significantly higher in term (2.76 +/- 0.66; mean +/- SD) than in preterm mature milk (1.06 +/- 0.4). The relative amount of 18:1n-9 was significantly higher in preterm than in term milk for transitional and mature milk, whereas that for the colostrum followed the opposite trend. Concerning the comparison between milk from mothers born in different countries, the relative contents of each of the fatty acids 16:0, 16:1n-7, 18:2n-6, 18:3n-3, and 22:5n-3 were higher in Panamanian than in Spanish milk, whereas the mean percentages of saturated fatty acids < 14:0, of 16:1n-9, and of 18:1n-9 were higher in Spanish than in Panamanian milk. Statistically significant differences were found during the three periods of lactation considered for almost all the fatty acids mentioned above, especially for 18:1n-9 and 18:3n-3. Although the potential biological significance of the changes in oleic acid content between preterm and term milk remains unclear, differences in fatty acid content between Spanish and Panamanian milk reflect the different composition of the diet among women from these countries.

Cohort Studies↗
PubMed1997

Developmental changes in UDP-N-acetylglucosamine 2-epimerase activity of rat and guinea-pig liver.

The activity of UDP-N-acetylglucosamine 2-epimerase was determined in the liver of rats and guinea-pigs of different ages. The activity of this enzyme in rats was low at birth, increased to a maximum value on day 15, and fell gradually until day 30. Thereafter, it increased up to the 60th day. The activity profile of the enzyme from guinea-pig liver was very similar. However, guinea-pig activity was 2-5 times lower than in rats. Both rats and guinea-pigs displayed similar liver sialic acid contents which increased from birth to 2 months of age. Rats also showed a N-glycolylneuraminic acid content that decreased from birth to 2 months. From these results we can inferred that postnatal UDP-N-acetylglucosamine 2-epimerase activity seems to be correlated with age and the developmental states of rats and guinea-pigs.

Animals↗
PubMed1996

Comparison of content and distribution of human milk gangliosides from Spanish and Panamanian mothers.

The lactational changes in content and distribution of gangliosides in human milk from Spanish and Panamanian mothers delivering term newborns were studied. There were no statistically significant differences in the concentration of gangliosides between Spanish and Panamanian milk. The ganglioside content expressed as a function of total milk lipids tended to decrease as lactation progressed in both types of milk. There was a significant correlation (r = 0.5896; p = 0.0062) between ganglioside and total lipid contents in Panamanian milk. However, in Spanish milk, the correlation was not significant (r = 0.1516; p = 0.3439). We did not detect important differences in the relative concentrations of individual gangliosides during lactation among milk samples from Spanish and Panamanian mothers. For both of them, GD3 was the most abundant ganglioside in colostrum, whilst in mature milk it was GM3.

Adult↗
PubMed1996

Changes during lactation in ganglioside distribution in human milk from mothers delivering preterm and term infants.

We studied changes during lactation in the relative concentration of individual gangliosides in human milk from mothers delivering preterm and term infants. The relative content of G(D3) was higher in colostrum than in mature milk, and tended to be higher in preterm colostrum than in term colostrum, whereas the relative content of G(M3) was higher in mature milk than in colostrum, and was also higher in term than in preterm milk. As G(D3) is usually detected in developing tissues whereas G(M3) is more abundant in mature tissues, these results suggest a relationship between the presence of individual gangliosides in human milk and immaturity of the mammary gland in mothers of preterm infants.

Adult↗
PubMed1995

Bilingual special education teachers' shifting paradigms: complex responses to educational reform.

This study examined the nature and process of change among five bilingual special education teachers as they attempted to modify existing instructional practices. Three factors affected the change process: (a) The more special education training in the teachers' background, the stronger their reductionist orientation; (b) change involves shifts in instructional practices and shifts in beliefs, and they do not automatically go hand in hand; and (c) change is most facilitated at the beginning stages of collaboration by including practicing members of the teachers' occupational community as agents of change.

Attitude↗
PubMed1995

New data on content and distribution of gangliosides in human milk.

The content and distribution of gangliosides, and total lipid content, were studied in human milk samples from different periods of lactation. We found a significant correlation (r = 0.5564; p = 0.0165) between ganglioside and total lipid contents. There was a selective change in the relative concentrations of GD3 and GM3 during lactation. The most abundant ganglioside in samples from the first three weeks of lactation was GD3, whereas after the first month, GM3 was the major ganglioside. In addition to GD3 and GM3, previously known to be present in human milk, we detected several previously unreported highly polar gangliosides.

Chromatography, Thin Layer↗
PubMed1994

Changes in ganglioside and sialic acid contents of goat milk during lactation.

The ganglioside content of goat milk has been determined from d 1 after parturition to d 60 of lactation. Marked changes occurred in milk over the course of lactation; the highest ganglioside content occurred in d-1 colostrum and then decreased to the end of the period studied. At least seven different ganglioside species were detected; three gangliosides containing sialyllactosylceramide accounted for 66 to 92% of the total lipid-bound sialic acid; this result reflected a very simple core structure of goat milk gangliosides. The most abundant ganglioside, II3(N-acetylneuraminic acid)2-lactosylceramide, was about 35 to 56%. The sialic acid content exhibited a trend similar to that of gangliosides; during early lactation sialic acid content was higher than in mature milk. Fat, protein, and total solids were high at initiation of lactation and decreased thereafter. However, lactose content remained almost unchanged during the period studied.

Animals↗
PubMed1993

Detection of complex gangliosides in human amniotic fluid.

Gangliosides are possibly very potent immunosuppressive molecules. Here we show that human amniotic fluid contains high concentrations of a number of previously unnoted, structurally complex and highly polar gangliosides. These unusual molecules are present early in pregnancy (first trimester), increase in concentration with gestational age, and reach maximum levels (0.8 microM) at term. Since similar gangliosides have been detected in human placenta, trophoblast, and amnion, we suggest that these molecules are shed into the amniotic fluid bathing these tissues.

Amnion↗
PubMed1990

Detection of immunoregulatory lipid-like factors in human amniotic fluid.

The immunosuppressive activity of amniotic fluid (AF) is extensively documented in the mouse. Although this property is due in part to the presence of alpha-fetoprotein (alpha-FP), other immunosuppressive factors are suspected. In this article, we demonstrate that human amniotic fluid lipid extract (AFLE) is inhibitory of, although not cytotoxic to, PHA-activated human lymphocytes, of mouse bone marrow cells, and of different established cell lines of human and mouse source. This effect is shown to be reversible. Under preparative thin layer chromatography (TLC) using chloroform:methanol:water (60:38:8) as solvents, the activity of AFLE migrates to two peaks of inhibition with Rf values of 0.46-0.62 and 0.84-1, respectively. These lipid-like factors may play a role as a nonspecific immunoregulatory mechanism which prevents maternally mediated immune rejection of the conceptus.

Amniotic Fluid↗
PubMed1989

Decreased levels of circulating CD4+ T lymphocytes during normal human pregnancy.

Peripheral blood mononuclear cell (PBMC) populations during human pregnancy have been investigated by many authors, although the different results obtained, principally in relation to T cells, are very discrepant. In this study we aimed to exclude all the possible causes of these discrepancies: small sample size; diurnal rhythm of CD4+ T cells; smoking habits; haemodilution which occurs during pregnancy and inappropriate statistical analysis; in order to determine whether gestation has a definite effect on PBMC populations. We found that the percentage of CD4+ T lymphocytes decreases in the first and second trimesters, returns to the non-pregnant level in the third trimester and remains there in the postpartum period. The percentages of CD3+ T lymphocytes run parallel to those of CD4+ while CD8+ T lymphocytes do not vary. The proportion of CD16+ cells, which include mature NK cells, diminishes in the second trimester and this reduction is maintained in the third trimester and the puerperium. No variation was found in the other PBMC studied (CD20+ lymphocytes, CD14+ monocytes and D/DR+ cells). When parity was considered no difference was seen between primiparous and multiparous women in any of the cell populations tested.

Adult↗