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Biomedical subjects

D K Rassin

Publications and source records attributed to D K Rassin.

At least 19 recordsLinked to original sources
PubMed1992

On the activity of gamma-aminobutyric acid and glutamate transporters in chick embryonic neurons and rat synaptosomes.

The uptake of radioactive gamma-aminobutyric acid (GABA) and D-aspartate and the effect of SKF 89976-A, a non-substrate inhibitor of the GABA transporter, on this uptake have been investigated. Neuronal cultures from eight-day-old chick embryos grown for three or six days in vitro, were used as a model. For comparison, we also used the P2-fraction from rat. Neuronal cultures grown for three and six days expressed high-affinity uptake systems for [3H]GABA and for D-[3H]aspartate with an increasing Vmax during this period. The lipophilic non-substrate GABA uptake inhibitor, SKF 89976-A, inhibited transporter mediated uptake of GABA both in cell cultures from chicken, and in P2-fractions from rat. The results also showed that SKF 89976-A was a poor inhibitor of the uptake of D-aspartate. We found no non-saturable uptake of D-aspartate.

Amino Acid Transport System X-AG↗
PubMed1992

Glutathione and tissue amino acid responses to light-exposed parenteral nutrients.

Effects of infusion of light-exposed (+L) or light-protected (-L) total parenteral nutrition solutions were investigated in rats. The parenteral infusions were carried out for 7 days through jugular cannulas in freely moving rats in metabolic cages. Plasma tyrosine and citrulline, hepatic methionine, valine, isoleucine, leucine and tyrosine, and biliary cystathionine were significantly greater in the -L than +L rats, whereas biliary arginine was significantly lower in the -L compared to +L rats. Bile flow, biliary inorganic phosphate and glucose were significantly lower, whereas biliary total glutathione (GSH+GSSG) was significantly greater in the -L compared to +L animals. These data suggest adverse effects on hepatobiliary function due to light exposure of parenteral nutrients. The endogenous markers used suggest that tight junction permeability, bile acid-independent flow, glutathione and amino acid homeostasis are altered by light exposure and that these changes can be minimized by light protection. The mechanisms involved in the induction of these changes need to be elucidated. The role of light exposure of parenteral nutrients during routine clinical use in the induction of hepatic dysfunction, a common metabolic complication of parenteral nutrition, needs to be considered.

Amino Acids↗
PubMed1992

Height, infant-feeding practices and cardiovascular functioning among 3 or 4 year old children in three ethnic groups.

Barker recently hypothesized that factors affecting prenatal and infant growth are related to adult blood pressure and CVD mortality. Predictions from Barker's hypothesis in regard to infant feeding were tested among a sample of 3 or 4 year old children. The relationship of infant-feeding characteristics (duration of breast-feeding, times of introduction of high fat, high carbohydrate, high potassium foods and table salt) to indicators of cardiovascular functioning (resting blood pressures and heart rates, and heart rate response to graded activity) while controlling for anthropometric (height, sum of seven skinfolds, BMI) and demographic (ethnicity, gender, social status) characteristics revealed that infant-feeding practices were not related to CV functioning in the predicted directions among this sample of 3 or 4 year old children. Furthermore, the positive relationship between height and systolic blood pressure was inconsistent with the Barker hypothesis.

Black or African American↗
PubMed1992

Hepatic function during short-term total parenteral nutrition: effect of exposure of parenteral nutrients to light.

Total parenteral nutrition (TPN) solutions either exposed to light (+L) or protected from light (-L) were infused for 5 days through jugular cannulas in freely moving rats placed in metabolic cages. At the end of the 5 day period, bile flow, biliary inorganic phosphate and biliary gamma-glutamyl transferase activity, as well as biliary concentrations of several essential and branch chain amino acids were significantly lower in the -L animals compared to +L animals. In addition, biliary glutathione was significantly lower in the +L animals. In both groups of animals, plasma tyrosine decreased significantly from pre-TPN values despite a doubling of plasma phenylalanine concentrations suggesting that tyrosine may become a conditionally essential amino acid in rats provided TPN. Our findings indicate that short-term parenteral infusion of light exposed TPN solutions alters hepatobiliary function as well as amino acid homeostasis and that the changes are minimized by light protection of the infusates. The exact mechanisms of the contribution of light exposure in the induction of hepatic dysfunction remain to elucidated.

Amino Acids↗
PubMed1991

Breast-feeding initiation in a triethnic population.

The influence of sociodemographic factors on the initiation of breast-feeding was evaluated in a triethnic population from Galveston, Tex. Breast-feeding rates were 44.3% among Anglo-Americans, 13.5% among blacks, and 26.6% among Mexican-Americans. Mexican ethnicity, education levels among Anglo-Americans, and marital status were associated with the initiation of breast-feeding. Odds ratios for breast-feeding were 1.94 (95% confidence interval, 1.10 to 3.43) times higher in Mexican-American compared with black women, and 1.94 (95% confidence interval, 1.34 to 2.83) times higher in married than unmarried women. Anglo-American ethnicity and education, as main effects, were not significantly associated with breast-feeding, but their interaction was. Among Anglo-American women (in comparison with black women), the odds ratios of breast-feeding increased with education level, ranging from 1.84 for those with less than an eighth grade education to 7.46 for those with some college. In contrast to recent findings suggesting that education was more important than ethnicity in predicting breast-feeding, the odds of breast-feeding among Anglo-American compared with black women depended on the level of maternal education, but the odds of breast-feeding for Mexican-American vs black women did not depend on education.

Adult↗
PubMed1991

Effect of protein/energy ratio on growth and behavior of premature infants: preliminary findings.

Premature infants weighing less than 1550 gm at birth were randomly assigned to receive one of three formulas identical in composition except for protein content (2.2, 2.7, and 3.2 gm.100 kcal-1) to determine the effects on growth, protein nutritional status, and behavior. Data collected for 2 weeks from the time of achieving an enteral energy intake of 100 kcal.kg-1.day-1 included measurements of weight, length, head circumference, and skin-fold thickness, and concentrations of plasma amino acids, serum total protein, prealbumin, retinol-binding protein, and urea nitrogen. In a subset of infants, behavior was assessed at the end of the feeding study with the Neonatal Behavior Assessment Scale. Except for the concentrations of plasma amino acids, there were no significant differences in growth or in other biochemical measurements among the three groups, but there were significant differences in the orientation, habituation, and stability clusters of the behavior assessment. Further, there were significant correlations between the plasma amino acid values and the behavioral clusters. These preliminary data suggest a relationship between protein intake in the neonatal period and behavioral outcome at the end of the feeding period in the absence of differences in growth and gross markers of protein nutritional status. The behavioral items noted to differ among the groups may indicate later cognitive outcome; detailed studies about behavioral responses to neonatal dietary intakes and later outcome seem indicated.

Amino Acids↗
PubMed1991

Feeding the premature infant after hospital discharge: growth and biochemical responses.

We conducted a double-blinded, randomized trial in premature infants after hospital discharge to test the hypotheses that growth and biochemical responses in those fed a formula with a reduced protein content (1.3 gm/dl) would be similar to those in infants fed a standard infant formula (protein 1.5 gm/dl). Twenty low birth weight infants were followed for 16 weeks from the time of hospital discharge. Growth (weight, length, and head circumference) and biochemical responses (total protein, prealbumin, retinol-binding protein, and blood urea nitrogen values) were similar in the two groups of infants. Plasma amino acids reflected the differences in protein intakes and were similar to previously reported values for premature infants fed human milk or formula. These results demonstrate similar growth and biochemical responses in preterm infants fed a standard infant formula and a formula with a protein content closer to that of human milk.

Amino Acids↗
PubMed1991

Enhanced GFR response to oral versus intravenous arginine administration in normal adults.

Both oral protein ingestion and intravenous amino acid infusions have been shown to increase glomerular filtration rate (GFR) and renal plasma flow (RPF) in normal subjects. Although the mechanism of this effect is not known, the renal responses to these loads have been associated with increases in peripheral glucagon concentrations. Conflicting data exist concerning the role of glucagon in the hyperfiltration response after an oral protein meal or administration of an intravenous amino acid mixture. Using a single amino acid as the stimulus for hyperfiltration, we compared the renal responses in six normal subjects to 30 gm oral arginine-HCl, intravenous arginine-HCl, and intravenous glucagon infused at the rate of 10 ng/kg/min. GFR, RPF, and glucagon concentration, as well as levels of plasma amino acids and selected gastrointestinal hormones, were measured for six 30-minute clearance periods after each load. Significant rises in mean peak GFR were noted after both oral arginine (104 +/- 5 ml/min x 1.73 m2 to 145 +/- 9 ml/min x 1.73 m2, p less than 0.02) and intravenous arginine (118 +/- 10 ml/min x 1.73 m2 to 134 +/- 11 ml/min x 1.73 m2, p = 0.02) administration. Mean peak RPF rose significantly after oral arginine (510 +/- 26 ml/min x 1.73 m2 to 710 +/- 32 ml/min x 1.73 m2, p less than 0.01) but not after intravenous arginine (616 +/- 60 ml/min x 1.73 m2 to 687 +/- 64 ml/min x 1.73 m2, p = 0.18). Intravenous glucagon infusion also increased both mean peak GFR (99 +/- 9 ml/min x 1.73 m2 to 149 +/- 10 ml/min x 1.73 m2, p less than 0.01) and RPF (514 +/- 48 ml/min x 1.73 m2 to 771 +/- 38 ml/min x 1.73 m2, p less than 0.01) significantly. We found the mean peak percent rise in GFR (43% +/- 13%) and RPF (42% +/- 12%) after oral arginine to be notably greater than that after intravenous arginine (14% +/- 5% and 13% +/- 9%, respectively). However, the mean peak percent rise in glucagon concentration after oral arginine was significantly lower than that after intravenous arginine (62% +/- 25% versus 479% +/- 176%, respectively, p = 0.04). Infusion of glucagon increased GFR (54% +/- 13%) and RPF (55% +/- 12%) to a degree similar to that seen after oral arginine, but again with a significantly higher mean peak percent rise in peripheral glucagon concentrations when compared with the rise after oral arginine (798% +/- 348% vs 62% +/- 25%, p less than 0.05).(ABSTRACT TRUNCATED AT 400 WORDS)

Administration, Oral↗
PubMed1990

Cord blood gamma glutamyl transferase activity: effect of gestational age, gender, and perinatal events.

Gamma glutamyl transferase (GGT) activity was measured in cord blood of 125 preterm and term neonates ranging from 26 to 42 weeks of gestation. The enzyme activity was higher in cord blood of infants from 33 to 37 weeks' gestation than in those of younger or older gestation. Furthermore, GGT activity in infants of greater than 37 weeks' gestation was significantly higher in male than in female infants. There were no significant correlations between GGT and Apgar scores, regardless of gestational age. However, GGT activity in term infants with a history of perinatal events suggestive of stress (meconium passage in utero, fetal decelerations, tight nuchal cord, or difficult delivery) was significantly higher than in term infants without such perinatal history. No such association existed in infants of less than 38 weeks' gestation. Infants of 33 to 37 weeks' gestation delivered vaginally had significantly higher cord GGT activity than those delivered by cesarean section. This difference was not apparent in younger or older infants. These data suggest that GGT activity reflects gender, gestational age, route of delivery, and perinatal stress. Further investigation is required to establish the reasons for these differences and to determine the usefulness of such enzyme activity in the delineation of liver dysfunction during postnatal development.

Birth Weight↗
PubMed1990

Ethnicity, infant-feeding practices, and childhood adiposity.

There has been professional concern that the type of milk used for infant-feeding may lead to adiposity. Studies of the relationship between infant milk-feeding and adiposity, however, have led to inconsistent results. This study investigated the relationship of infant-feeding practices to three indicators of adiposity: body weight, body mass index (BMI) and sum of seven skinfolds. The sample includes children at 3 or 4 years of age, in three ethnic groups. Multivariate techniques assessed the relationship among practices of infant-feeding with three indicators of adiposity, while considering potential confounding variables. Although a weak bivariate relationship was detected between the duration of breastfeeding and body weight, none of the measures of infant-feeding were related to the three indicators of adiposity. Black-American girls had smaller skinfolds than Anglo- or Mexican-American girls, with no ethnic group differences among boys. Concerns about adiposity due to methods of infant-feeding can be allayed, at least among 3- or 4-year-old children.

Black or African American↗
PubMed1989

Growth, serum biochemistries, and amino acids of term infants fed formulas with amino acid and protein concentrations similar to human milk.

We tested the hypothesis that amino acid intake from infant formulas modified to be similar to human milk would result in indices of protein metabolism more like those in human milk-fed infants. Formula-fed infants received for 12 weeks one of three isocaloric formulations of a whey-adapted formula that differed in protein concentration: 11, 13, or 15 g/L. Infants consumed similar volumes of formula or human milk. Serum urea nitrogen concentrations reflected the protein content of the diets. Plasma indices of protein nutritional status were normal and did not differ among groups. Growth rates of all infants were normal and similar. Serum indicators of protein nutritional status varied with age, which made comparisons of formula-fed infants with human milk-fed infants difficult. Plasma concentrations of leucine and isoleucine at 4 weeks of age were higher in infants fed the formula containing 15 g protein/L when compared with those of infants fed the other two formulas or human milk. At 8 and 12 weeks of age, all formula-fed infants had plasma amino acid profiles that did not differ significantly from each other except for isoleucine, which was lower in the 11-g/L group. We found that providing formulas with an amino acid pattern similar to that of human milk did not produce a plasma amino acid pattern identical to that of the breast-fed infant. This observation suggests that other factors, such as the hormonal response to feeding, differing nutritional bioavailability of amino acids from human and bovine milk proteins, and the changing quantity and type of amino acids with advancing lactation, influence plasma amino acid concentrations.

Amino Acids↗
PubMed1989

Altered glycine and taurine conjugation of bile acids following aluminum administration to rats.

Aluminum contaminates components of intravenous nutrient solutions and accumulates in the liver with parenteral feeding. Abnormalities in hepatic function associated with aluminum accumulation include increased serum bile acid concentration and glucuronyl transferase activity and reduced mixed function oxidase levels and bile flow. Whether there are other biochemical responses of the liver to aluminum is unclear. We report the effects of aluminum administration on bile acid conjugation in rats given aluminum intravenously as follows: group I, 1 mg/kg/day for 14 days; group II, 5 mg/kg/day for 14 days; and group III, 5 mg/kg/day for 7 days. Taurine-conjugated bile acids were reduced and glycine/taurine elevated in all groups compared with pair-fed controls. Glycine/taurine was greater in group II versus III and varied directly with serum bile acid concentration. These findings suggest that aluminum administration is associated with decreased taurine conjugation of bile acids, a phenomenon that may be associated with cholestasis.

Aluminum↗
PubMed1989

Safety of long-term large doses of aspartame.

Safety of long-term administration of 75 mg/kg of aspartame per day was evaluated with the use of a randomized, double-blind, placebo-controlled, parallel-group design in 108 male and female volunteers aged 18 to 62 years. Subjects received either aspartame or placebo in capsule form three times daily for 24 weeks. No persistent changes over time were noted in either group in vital signs; body weight; results of standard laboratory tests; fasting blood levels of aspartame's constituent amino acids (aspartic acid and phenylalanine), other amino acids, and methanol; or blood formate levels and 24-hour urinary excretion of formate. There also were no statistically significant differences between groups in the number of subjects experiencing symptoms or in the number of symptoms per subject. These results further document the safety of the long-term consumption of aspartame at doses equivalent to the amount of aspartame in approximately 10 L of beverage per day.

Adolescent↗
PubMed1988

Human milk supplementation. Delivery of energy, calcium, phosphorus, magnesium, copper, and zinc.

Human milk when fed to preterm infants is frequently supplemented with human milk fortifiers that provide an additional source of protein, energy, and minerals. Human milk that was provided by the mother of a preterm infant, and that was supplemented with commercially available human milk fortifiers, was assessed under simulated syringe-pump and bolus feeding circumstances for the delivery of energy, calcium, phosphorus, copper, magnesium, and zinc to an infant. In general, the nutrients were not completely delivered with syringe-pump feedings, with the greatest losses occurring in the concentrations of calcium and phosphorus. The losses were more pronounced with the use of a powdered fortifier than with the use of a liquid fortifier. Little or no change in the concentrations of the various nutrients were observed with simulated bolus feeding. We suggest that human milk fortified with supplements be fed with care to assure complete delivery of the nutrients and that infants receiving such feedings be monitored to assure adequate nutritional status.

Calcium↗
PubMed1988

Growth and total body water in premature infants fed "in-utero" or "ex-utero".

Total body water and anthropometric measurements were compared in two groups of premature infants. The first group included infants with birthweights less than 1,501 g who were fed under usual clinical circumstances and studied at a bodyweight of 1,800-2,100 g ("Ex-utero"); the second group of infants had a birthweight of 1,800 to 2,100 g and were studied within the first week of life ("In-utero"). Triceps and subscapular skinfold thicknesses were significantly greater in "Ex-utero" infants than in "In-utero" infants, whereas body length was significantly greater in the latter group compared to the former. There were no difference in total body water, abdominal skinfold thickness, or midarm circumference between the two groups. These data suggest that feeding premature infants a standard premature infant formula under established guidelines leads to differences in body and fat distribution but not total body water compared to infants nourished "in utero".

Arm↗