Phase angle and bioelectrical impedance vectors in adolescent and adult male athletes.

The aim of the current study was to assess phase angle (PA) and bioelectrical impedance vectors (BIVA) in adolescent (n = 105, 12-19 y) and adult (n = 90, 20-50 y) male athletes practicing varied sports modalities. Bioelectrical impedance analysis (BIA) was performed with a single-frequency tetrapolar impedance analyzer after the athletes had fasted overnight for 8 h. PA and BIVA were determined from BIA data. PA presented correlations (P < .01) with body-mass index (r = .58) in all athletes and also with age in adolescent (r = .63) and adult (r = -.27) athletes. Compared with adults, adolescent athletes presented lower PA and higher frequency of PA below the 5th percentile of a reference population (P < .001). The adolescents with low PA were mostly football and basketball players. The BIVA confidence ellipses of adult and adolescent athletes were different (P < .001) between them and from their respective reference populations and were closer than those of adult and adolescent nonathletes. About 80% of the athletes were in the 95th percentile of BIVA tolerance ellipses and in quadrants consistent with adequate body cell mass and total body water. The adolescent athletes outside the 95th percentile ellipse were all football and basketball players who showed indications of decreased water retention and body cell mass and of increased water retention, respectively. PA and BIVA ellipses showed that the intense training routine of the athletes changed functional and hydration parameters and that the magnitude of these changes in adolescents may depend on the sport modality practiced.

n-6 and n-3 Long-chain polyunsaturated fatty acids in the erythrocyte membrane of Brazilian preterm and term neonates and their mothers at delivery.

Placental transfer of the long-chain polyunsaturated fatty acids (LCPUFA) arachidonic (AA) and docosahexaenoic (DHA) acids is selectively high to maintain accretion to fetal tissues, especially the brain. The objectives of the present study were to investigate the essential fatty acid (EFA) and LCPUFA status at birth of preterm and term Brazilian infants and their mothers, from a population of characteristically low intake of n-3 LCPUFA, and to evaluate the association between fetal and maternal status, by the determination of the fatty acid composition of the erythrocyte membrane. Blood samples from umbilical cord of preterm (26-36 weeks of gestation; n = 30) and term (37-42 weeks of gestation; n = 30) infants and the corresponding maternal venous blood were collected at delivery. The LCPUFA composition of the erythrocyte membrane and DHA status were similar for mothers of preterm and term infants. Neonatal AA was higher (P < 0.01) whereas its precursor 18:2n-6 was lower (P < 0.01) than maternal levels, as expected. There was no difference in LCPUFA erythrocyte composition between preterm and term infants, except for DHA. Term infants presented a worse DHA status than preterm infants (P < 0.01) and than their mothers (P < 0.01) at delivery. There was a negative correlation of neonatal DHA with maternal AA and a positive correlation between neonatal AA and maternal AA and 18:2n-6 only at term. These results suggest that the persistent low DHA maternal status, together with the comparatively better AA and 18:2n-6 status, might have affected maternal-fetal transfer of DHA when gestation was completed up to term, and possibly contributed to the worse DHA status of term neonates compared with the preterm neonates.

Longitudinal change in plasma total homocysteine during pregnancy and postpartum in Brazilian women and its relation with folate status and other factors.

Fasting plasma total homocysteine (tHcy) concentration was determined in a cohort of pregnant Brazilian women (n = 46) supplemented with folic acid from the second trimester of pregnancy. Blood samples were obtained in the first and third trimesters from all women, and 30-40 days postpartum from seventeen women. Plasma tHcy decreased during pregnancy from 10.3 to 8.7 micromol/L, and was 11.6 micromol/L in the postpartum. Plasma and erythrocyte folate increased, consistent with use of the folate supplement, but decreased slightly in the postpartum, whereas the opposite occurred for plasma vitamin B12. tHcy was inversely correlated with plasma and erythrocyte folate in the third trimester (r = -0.585 and -0.460, respectively). This relationship occurred despite the fact that all women had attained what could be considered adequate levels of folate indices. Furthermore, the change (third trimester minus first trimester levels) of tHcy was inversely correlated (p < 0.01) with the changes in plasma (r = -0.573) and erythrocyte folate (r = -0.525). tHcy had no correlation in any of the periods tested with plasma vitamin B12, plasma albumin, hematocrit, hemoglobin, iron indices, dietary intakes of folate, vitamins B12 and B6, and levels of folate supplement.

Zinc uptake by human placental microvillous membrane vesicles: effects of gestational age and maternal serum zinc levels.

Zinc uptake by syncytiotrophoblast microvillous membrane vesicles (SMMV) from human placentas was characterized and the effects of maternal serum zinc levels at term and of gestational age on kinetic parameters were evaluated. Zinc uptake at pH 7.2 was rapid for the first 2 min, followed by a slower increase, approaching equilibrium after 30 min. Uptake was saturable at a zinc concentration of 30 micromol/L, higher than the upper range of the physiological serum zinc level. Kinetic analysis of uptake at 1 min in SMMV from term placenta showed similar Km values (mean: 6.9+/-0.6 micromol/L) for different levels of maternal serum zinc. However, Vmax was higher (p < 0.05) in SMMV from mothers with serum zinc lower than 7.6 micromol/L compared to those with higher serum zinc levels (35.8+/-1.6 and 26.6+/-1.6 nmol 65Zn/mg protein/min, respectively). Km values were similar in term (>37 wk of gestation) and preterm (20-25 wk of gestation) placentas, whereas Vmax was higher (p < 0.05) in the preterm (34.3+/-1.6 nmol Zn/mg protein/min) compared to term placentas from mothers with serum zinc levels above 7.6 micromol/L. These results suggest that whereas afffinity for zinc was not altered with gestational age or maternal serum zinc levels, zinc-uptake capacity in human placenta is influenced both by gestational age and by low levels of maternal serum zinc in order to ensure an adequate maternal-fetal zinc transfer.

Effect of heat treatment on nutritional quality of germinated legume seeds.

The effect of heat treatment of germinated soybean, lupin, and black bean on chemical composition and protein utilization in rats was evaluated. Heat treatment caused complete inactivation of trypsin inhibitors whereas it did not affect phytic acid levels. Proximate components, minerals, and amino acids did not change, but low molecular weight sugars were affected by heat treatment differently for each germinated legume. The sugar digestibility ratio (total digestible sugars/total nondigestible sugars) in germinated black beans doubled after heat treatment. True protein digestibility (TD) increased with heat treatment only in germinated soybean. Net protein utilization was markedly improved (20%) with heat treatment in germinated soybean and lupin. Utilizable protein of heat-treated germinated legumes was 289, 236, and 132 g/kg of legume dry weight for soybean, lupin, and black bean, respectively. Supplementation with methionine did not alter TD but improved all other indices of protein utilization in the germinated legumes, particularly in black bean. All three germinated legumes become equivalent in protein quality when heating and supplementation with methionine are combined with germination. The use of germinated heat-treated soybean, lupin, and black bean on their own and/or as food ingredients is nutritionally advantageous due to the low content of nondigestible oligosaccharides and the high protein utilization.

Micronutrient regulation in pregnant and lactating women from Rio de Janeiro.

Studies with low-income pregnant and lactating women from the city of Rio de Janeiro, concerned mainly with the changes in micronutrient homeostasis during pregnancy and lactation in the absence of overt clinical deficiencies, are reported. These studies focused on folate, cobalamin, iron, zinc and vitamin A. Factors that may affect the maternal micronutrient state, such as dietary intakes, use of supplements and interrelationships of micronutrients have been considered, as well as the implications of these changes for maternal-fetal transfer and milk composition. Although these studies were not designed to evaluate the prevalence of sub-clinical micronutrient deficiencies in pregnant and lactating women, they indicate that high frequencies of sub-clinical deficiencies of folate, iron, zinc and vitamin A, especially in pregnant women, are expected to be found in Rio de Janeiro.

Partial characterization of folate uptake in microvillous membrane vesicles isolated from human placenta.

The purpose of the present study was to determine biochemical parameters of folate uptake, and the putative contribution of the membrane-anchored folate receptor in microvillous membrane vesicles obtained from the syncytiotrophoblast of human term placenta. Uptake of [3H]-pteroylglutamic acid (PGA) by microvillous membrane vesicles was pH dependent with a maximum at pH 6.0, and attained equilibrium at 60 min of incubation. Uptake was higher in the presence on an inward pH gradient (pHout = 6.0; pHin = 7.5) than in the absence of the gradient (pHout = pHin = 6.0). The effect of changes in medium osmolality showed that both binding to the vesicular membrane and internalization contributed to the measured [3H]-PGA uptake. Equilibrium uptake experiments using [3H]-PGA concentrations within the physiological range of folate in blood serum showed that saturation was achieved at 30 nM and revealed a single class of binding sites with a Kd of 1.8 nM for [3H]-PGA. Cleavage of the glycosyl-phosphatidylinositol moiety of the folate receptor, which anchors the receptor to the membrane, with phosphatidylinositol-specific phospholipase C resulted in a reduction of about 80% in [3H]-PGA uptake. In conclusion, our results showed that the folate uptake in the maternally facing membrane of the human placenta presents a saturable component and is mediated by the folate receptor to ensure an adequate maternal-fetal folate transfer.

Partial characterization of folate uptake in microvillous membrane vesicles isolated from human placenta

The purpose of the present study was to determine biochemical parameters of folate uptake, and the putative contribution of the membrane-anchored folate receptor in microvillous membrane vesicles obtained from the syncytiotrophoblast of human term placenta. Uptake of [3H]-pteroylglutamic acid (PGA) by microvillous membrane vesicles was pH dependent with a maximum at pH 6.0, and attained equilibrium at 60 min of incubation. Uptake was higher in the presence of an inward pH gradient (pHout = 6.0; pHin = 7.5) than in the absence of the gradient (pHout = pHin = 6.0). The effect of changes in medium osmolality showed that both binding to the vesicular membrane and internalization contributed to the measured [3H]-PGA uptake. Equilibrium uptake experiments using [3H]-PGA concentrations within the physiological range of folate in blood serum showed that saturation was achieved at 30 nM and revealed a single class of binding sites with a Kd of 1.8 nM for [3H]-PGA. Cleavage of the glycosyl-phosphatidylinositol moiety of the folate receptor, which anchors the receptor to the membrane, with phosphatidylinositolspecific phospholipase C resulted in a reduction of about 80 per cent in [3H]-PGA uptake. In conclusion, our results showed that the folate uptake in the maternally facing membrane of the human placenta presents a saturable component and is mediated by the folate receptor to ensure an adequate maternal-fetal folate transfer.

Effect of subadequate maternal vitamin-A status on placental transfer of retinol and beta-carotene to the human fetus.

The placental transfer of retinol and beta-carotene was assessed based on maternal serum, cord serum and placental levels at term parturition in women with adequate (n = 15; serum retinol > 20 micrograms/dl) and subadequate (n = 16; serum retinol < or = 20 micrograms/dl) vitamin-A status. There was no difference in retinol and beta-carotene levels in placenta and cord serum between these groups. However, differences in the relation of maternal, placental and cord blood components were observed between women with adequate and subadequate vitamin-A status. In women with subadequate status, circulating fetal retinol levels correlated with placental retinol levels, and maternal serum beta-carotene correlated with placental retinol. Within this group, maternal serum beta-carotene and cord serum retinol correlated significantly in women with serum retinol levels lower than 15 micrograms/dl. These results suggest that beta-carotene may be a precursor of retinol in placenta and that this conversion may depend on the nutritional status of the mother, being particularly effective in a more depleted state.

Iron uptake from lactoferrin by intestinal brush-border membrane vesicles of human neonates.

It is uncertain to what extent the binding of human lactoferrin (LF) to its receptor in the intestinal brush-border membrane affects iron uptake in infants. The purpose of this study was to investigate iron uptake from human LF by brush-border membrane vesicles (BBMV) obtained from the small intestine of human neonates. LF was purified from pooled human colostrum. Uptake experiments were performed by incubation of 55Fe-citrate or 55Fe-LF with BBMV, followed by rapid filtration through microporous filters. 55Fe uptake from LF by BBMV was dependent on pH, with a maximum at 7.5, and increased with incubation time, reaching a maximum at 1 min. When 55Fe was bound to citrate, uptake was slower (maximum at 5 min) and not dependent on pH. In both experiments, the maximum uptake of iron bound to LF was about twice that of iron bound to citrate (230 pmol and 105 pmol/mg microvillus protein, respectively). Partial degradation of LF in two fragments resulted in the loss of its capacity to increase iron uptake by BBMV. From these preliminary results we conclude that LF may increase iron absorption during the neonatal period, contributing to the high bioavailability of this mineral in human milk.

Iron uptake from lactoferrin by intestinal brush-border membrane vesicles of human neonates

It is uncertain to what extent the binding of human lactoferrin (LF) to its receptor in the intestinal brush-border membrane affects iron uptake in infants. The purpose of this study was to investigate iron uptake from human LF by brush-border membrane vesicles (BBMV) obtained from the small intestine of human neonates. LF was purified from pooled human colostrum. Uptake experiments were performed by incubation of 55Fe-citrate or 55Fe-LF with BBMV, followed by rapid filtration through microporous filters. 55Fe uptake from LF by BBMV was dependent on pH, with a maximum at 7.5, and increased with incubation time, reaching a maximum at 1 min. When 55Fe was bound to citrate, uptake was slower (maximum at 5 min) and not dependent on pH. In both experiments, the maximum uptake of iron bound to LF was about twice that of iron bound to citrate (230 pmol and 105 pmol/mg microvillus protein, respectively). Partial degradation of LF in two fragments resulted in the loss of its capacity to increase iron uptake by BBMV. From these preliminary results we conclude that LF may increase iron absorption during the neonatal period, contributing to the high bioavailability of this mineral in human milk.

Liver reserves of iron, copper, and vitamin B12 in Brazilian fetuses and infants of different socioeconomic status.

The purpose of this study was to investigate the influence of the stage of fetal development and of maternal socioeconomic status on liver concentrations and total liver reserves of iron, copper, and vitamin B12 in Brazilian fetuses and infants. Eighty fetuses and infants ranging from 19 to 42 wk of gestational age were studied. Liver concentrations of nutrients did not vary significantly with the stage of fetal development. Therefore, increases in total liver reserves during development were caused mainly by increases in liver weight. There were significant correlations between total liver reserves of vitamin B12 and iron (r = 0.742, p < 0.001), vitamin B12 and copper (r = 0.444, p < 0.001), and iron and copper (r = 0.431, p < 0.001). Maternal socioeconomic status did not affect liver nutrient concentrations or total hepatic levels at any stage of fetal development.

Lactoferrin levels and unsaturated iron-binding capacity in colostrum of Brazilian women of two socioecomic levels

The objetive of this study was to compare lactoferrin (LF) levels and unsaturated iron-binding capacity (UIBC) of colostrum from Brazilian women aged 20-38 years of low (N = 28) and high (N = 15) socioeconomic level. Both groups received a similar amount of supplental iron (25-65 mg/day) during pregnancy. We also determined the relationship between LF levels and UIBC, and between these components and maternal iron status. Both groups (low and high socieconomic level) showed adequate and similar mean hematocrit (35.0 ñ 13% and 35.9 ñ 1.3%, respectively) and serum ferritin (64 ñ 12 µg/1 and 57 ñ 12 µg/1, respectively) levels. Furthermore, LF levels (5.7 ñ 0.9 mg/ml and 5.5 ñ 0.6 mg/ml) and UIBC (3.8 ñ 0.3 µg/ml and 3/1 ñ 0.3 µg/ml) were not significantly different in the two groups of women, nor were they related to maternal hematocrit or serum ferritin. UIBC was significantly (P = 0.009), although weakly positively correlated (r= 0.45) with LF levels, suggesting that other colostrum ligands may contribute substantially to the capacity of colostrum to bind exogenous iron

Lactoferrin levels and unsaturated iron-binding capacity in colostrum of Brazilian women of two socioeconomic levels.

The objective of this study was to compare lactoferrin (LF) levels and unsaturated iron-binding capacity (UIBC) of colostrum from Brazilian women aged 20-38 years of low (N = 28) and high (N = 15) socioeconomic level. Both groups received a similar amount of supplemental iron (25-65 mg/day) during pregnancy. We also determined the relationship between LF levels and UIBC, and between these components and maternal iron status. Both groups (low and high socioeconomic level) showed adequate and similar mean hematocrit (35.0 +/- 1.3% and 35.9 +/- 1.3%, respectively) and serum ferritin (64 +/- 12 micrograms/l and 57 +/- 12 micrograms/l, respectively) levels. Furthermore, LF levels (5.7 +/- 0.9 mg/ml and 5.5 +/- 0.6 mg/ml) and UIBC (3.8 +/- 0.3 micrograms/ml and 3.1 +/- 0.3 micrograms/ml) were not significantly different in the two groups of women, nor were they related to maternal hematocrit or serum ferritin. UIBC was significantly (P = 0.009), although weakly positively correlated (r = 0.45) with LF levels, suggesting that other colostrum ligands may contribute substantially to the capacity of colostrum to bind exogenous iron.

Estado Nutricional y composición de la leche materna en Hierro, Zinc, Folato y Vitamina B12 de madres de bajo nivel socioeconómico de Río de Janeiro / Nutritional status and iron, zinc, folate and vitamin B12 milk composition in mothers of low socioeconomic level in Río de Janeiro

El objetivo del estudio fue verificar si el uso durante el embarazo de suplemento de hierro, folato y vitamina B12 por mujeres brasileñas de bajo nivel socioeconómico es suficiente para lograr un estado nutricional satisfactorio en estos nutrientes durante la amamantación y una composición adecuada de la leche. Como complemento del estudio fue analizado el estado nutricional de las madres y la composición de la leche en relación al zinc. Considerando los valores promedio, el estado nutricional de las madres en relación a los nutrientes estudiados fue adecuado. Sin embargo algunas madres tuvieron índices menores que los normales para mujeres no embarazadas. Estos bajos índices especialmente 30 días después del parto, sugieren que estas madres presentan un estado nutricional inadecuado. La composición de la leche en relación a los nutrientes estudiados fue comparable a la de mujeres bien nutridas de países desarrollados. Las madres que recibieron suplemento de folato durante el embarazo tuvieron niveles más altos en el suero inmediatamente después del parto, que las que no recibieron suplemento. Sin embargo, la composición de la leche no fue afectada. Se concluye que el suplemento recibido fue insuficiente para cubrir las demandas de este período y mantener reservas adecuadas

Iron, zinc, folate and vitamin B12 nutritional status and milk composition of low-income Brazilian mothers.

The purpose of this study was to assess the nutritional status of low-income Brazilian mothers, who were supplemented with iron and vitamin B12 during pregnancy, in terms of iron, zinc, folate and vitamin B12, in different stages of lactation and to determine the influence of the maternal nutritional status on milk composition. The effect of folate supplementation during pregnancy on folate status of the nursing mothers and milk composition was investigated. The effect of partial weaning on maternal status and milk composition was also studied. In general, the nutritional status of iron, zinc, folate and vitamin B12 of the mothers appears adequate. However, some of the mothers had indices of status lower than normal limits for non-pregnant women. These values, particularly after 30 d post-partum, indicate that these mothers might be at nutritional risk and that the nutrient supplementation received during pregnancy was insufficient to meet demands. There was an increase with the stage of lactation for haematocrit, serum vitamin B12, serum zinc, serum albumin, milk folate and saturation of its binding protein, but there was a decrease for milk protein, total and whey-bound iron and zinc, and lactoferrin. Mothers who took folate supplements during pregnancy had higher serum folate levels immediately after birth than those not taking the supplements but no differences were found at later stages of lactation. Milk composition was not affected. Partial weaning did not affect the maternal nutritional status or the milk composition except for iron which was higher in milk from mothers who were partially breastfeeding.(ABSTRACT TRUNCATED AT 250 WORDS)

Concentration and distribution pattern of selected micronutrients in preterm and term milk from urban Brazilian mothers during early lactation.

The purpose of this study was to assess the concentration and binding pattern of zinc, iron, folate and vitamin B12 in milk of Brazilian women of low socioeconomic status giving birth at term or preterm, during early lactation. Protein, fat, total solids and ash concentrations were also determined. Protein and zinc concentrations decreased significantly as lactation proceeded whereas milk fat and folate increased with the lactation period. Total solids, ash, iron and vitamin B12 remained unchanged. Zinc was present mainly in the whey fraction while less than half of the total iron was present in this fraction, with no significant change due to stage of lactation. Unsaturated folate and vitamin B12 binding capacities and percentage of saturation of the folate binding protein increased with the stage of lactation. The vitamin B12 binding protein was highly unsaturated in all samples. There was no significant difference between term and preterm samples in the parameters investigated. Correlation analysis between milk components indicated significant relationships between total solids and fat, total zinc and whey zinc, folate and total folate binding capacity, unsaturated and total folate binding capacity, and unsaturated and total B12 binding capacity. In general, the nutrient concentrations found in this study are in good agreement with published data on milk composition of women from developed countries, with the possible exceptions of folate, which was lower, and iron, which was higher. The correlation of folate concentration with its binding protein found in this work supports the hypothesis of a regulatory role for folate levels in milk exerted by the folate binding protein in the mammary gland.

Characterization of the vitamin B12-binding protein isolated from sow's milk and its affinity for cyanocobalamin and other corrinoids.

1. Unsaturated vitamin B12-binding protein was isolated from sow's milk whey by affinity chromatography on a vitamin B12-Sepharose column with a yield of 54% (3920-fold purification). The purified binding protein was homogeneous by the criteria of polyacrylamide gel electrophoresis and high speed sedimentation equilibrium. 2. The isolated vitamin B12-binding protein was a glycoprotein with 24% carbohydrates (fucose, galactose, mannose, galactosamine, glucosamine and sialic acid) and high levels of aspartic and glutamic acids. The protein which has a molecular weight of 61,800 determined by ultracentrifugation, consisted of a single polypeptide chain, bound vitamin B12 on an equimolar basis and had a partial specific volume of 0.697 ml/g (mechanical oscillator technique). 3. Its dissociation constant, Kd, for cyanocobalamin was 8.8 x 10(-10)M. The binding protein showed similar affinities for hydroxo-, methyl-, and adenosylcobalamin when compared to cyanocobalamin relative affinity ratios, but lower affinities (31-49%) for cobinamide, Co-alpha-[adenyl] cobamide and Co-alpha-[2-methyl-adenyl] cobamide. Therefore, the substitution of the axial ligand to the cobalt atom in the corrin ring of vitamin B12 had no effect on affinity, whereas the differences in the nucleotide part of the molecule caused a small decrease in energy of the interaction. 4. The present results indicate close similarity of the vitamin B12-binding protein from sow's milk to vitamin B12-binding proteins from other sources, especially those from human milk and from porcine gastric mucosa (nonintrinsic factor). Whether this similarity extends to antigenic and physiological properties remains to be investigated.