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Biomedical subjects

C Garza

Publications and source records attributed to C Garza.

At least 37 records · Page 2Linked to original sources
PubMed1992

Bone mineralization outcomes in human milk-fed preterm infants.

We evaluated bone mineralization by single photon absorptiometry at 2 y in a cohort of preterm infants studied since birth. Infants were fed human milk fortified with Ca [to achieve 80 mg/dL (19.96 mmol/L)] and P [40 mg/dL (12.91 mmol/L)] from wk 2 through 8 after birth. After hospital discharge, infants were divided into two groups (HM and F) determined by the timing of the introduction of cow milk-based formula. Mid-radius bone mineral content (BMC) was assessed in 10 infants who were breast-fed (HM) for a minimum of 2 mo after hospital discharge and 11 who were bottle-fed (F). The mean duration of human milk-feeding differed by design between HM and F groups (31 +/- 15 versus 11 +/- 3 wk, respectively). Although we had observed previously that group F had significantly greater BMC values at 16, 25, and 52 wk compared with values in group HM, we found similarities in BMC values (180 +/- 30 mg/cm) between groups at 2 y. The 2-y cohort comprised healthy infants and the groups had similar birth weights, lengths of gestation, and values for weight (10.8 +/- 1.1 kg), length (82 +/- 2 cm), and bone width (7.8 +/- 1.1 mm). Follow-up outcomes at 2 y in preterm infants fed fortified human milk in hospital suggest that if they continue to receive human milk after hospital discharge, radius BMC will "catch-up" to that of similar infants given formula in the posthospitalization period.

Bone Density↗
PubMed1992

Milk production by mothers of premature infants: influence of cigarette smoking.

The volume of milk produced by mothers who smoked cigarettes (n = 11) and control subjects who did not smoke (n = 29) was compared after the delivery of their preterm infants (28 to 32 weeks gestation). Milk production was significantly less among those who smoked, with or without adjusting for age, race, parity, gravidity, weight-for-height, prior nursing experience, customary alcohol and caffeine intake, infant birth weight, and pumping frequency. Each mother maintained her milk production using an electrical breast pump and without the stimulus of her infant suckling at the breast. Daily frequency and duration of breast pump usage were similar in the two groups. At 2 weeks postpartum, 24-hour milk volumes were 406 +/- 262 mL for mothers who smoked and 514 +/- 338 mL for control subjects. Between 2 to 4 weeks postpartum, the mean change in 24-hour milk volume (milliliters per 24 hours) of control subjects increased (+113 +/- 179 mL, P < .005), whereas milk volume of mothers who smoked cigarettes remained unchanged (-47 +/- 122 mL, P = .25). The percentage change in milk volume between 2 and 4 weeks for the combined groups was significantly related to four factors: pumping frequency, change in daily pumping frequency, day of initiation of pumping, and smoking status. Total and protein nitrogen, lactose, calcium, and phosphorous concentrations did not differ in milks from mothers who smoked cigarettes and mothers who did not smoke.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Lactation performance of rural Mesoamerindians.

Anthropometry, body composition and dietary intake of 30 lactating Otomi Indians of Capulhuac, Mexico, were studied to identify maternal factors which potentially limit lactation and thereby infant growth. Human milk production, milk composition, and maternal dietary intake, body weight, skinfold thicknesses, and body composition were measured at 4 and 6 months postpartum. The 2H2O dose-to-mother method was used to estimate milk production and maternal total body water (TBW). Fat-free mass (FFM) was calculated as TBW/0.73. Body fat was computed as body weight minus FFM. Human milk samples were analyzed for energy, nitrogen, lactose and fat using standard analytical methods. Maternal diet was assessed by three 24-h intake recalls. Mean (SD) milk production was 885 (146) and 869 (150) g/d at 4 and 6 months, respectively. Milk concentrations of protein nitrogen (1.23 (0.17) mg/g) and lactose (66.6 (2.8) mg/g) were comparable to, but the concentrations of fat (22.2 (6.7) mg/g) and energy (0.54 (0.06) kcal/g) were lower than, values observed in economically privileged populations. Maternal height, weight, and BMI were 1.47 (0.06) m, 50.3 (6.0) kg, and 23.4 (3.1) kg/m2, respectively. Maternal TBW, FFM and body fat were 55.8 (4.6)%, 76.4 (6.3)%, and 23.6 (6.4)%, expressed as a percentage of body weight, respectively. Maternal energy and protein intakes averaged 1708 (338) kcal/d and 40 (10) g/d, respectively. Milk production was negatively correlated with maternal body fat (P = 0.006). Energy and fat concentrations in the milk of the Otomi women were positively related to their weight (P = 0.002), BMI (P = 0.05), and body fat (P = 0.004). Energy concentrations in milk were not related to rates of milk production (r = 0.24; P = 0.23). Nor was milk production or composition significantly associated with maternal dietary intake. Lactation performance of these Otomi women correlated significantly with maternal body size and composition, but not current dietary intake.

Adipose Tissue↗
PubMed1991

Absorption of carbon 13-labeled rice in milk by infants during acute gastroenteritis.

To determine whether rice cereal could be used to complement a cow milk-based diet in the nutritional management of infants with acute diarrhea, we assessed its digestion and absorption in eight affected male infants, 69 to 131 days of age. They received cow milk formula with 5.4% lactose (diluted 1:1 with water and precooked rice cereal) 5 to 22 hours after admission and rehydration. The first feeding consisted of milk diluted with carbon 13-enriched rice cereal. A 48-hour fecal collection and balance study was performed. Rice cereal was reasonably well absorbed (84.0% to 95.8%) by seven of the eight infants. The study was repeated in seven of the infants after they had recovered. Our results indicated that rice cereal is well absorbed by young infants with acute diarrhea and that it is an adequate nutrient supplement for this patient population.

Acute Disease↗
PubMed1991

Measurement of milk intake: tracer-to-infant deuterium dilution method.

The tracer-to-infant deuterium dilution method for the measurement of milk intake was evaluated in twenty breast-fed and twenty formula-fed infants. The isotope method was compared with conventional direct-weighing techniques. Human milk intake was assessed by 5 d test-weighing. Intakes of formula, supplemental foods, and water were determined by pre- and post-weighing of feeding bottles. An oral dose of 200 mg 2H2O/kg body-weight was given to each infant, and urine was sampled daily for 14 d. 2H enrichment of the urine was measured by gas-isotope-ratio mass spectrometry. Milk intakes estimated from the deuterium dilution method were consistently higher than those from direct-weighing; the mean difference between methods was 106 (SD 47) g/d or 14% for the breast-fed group and 70 (SD 155) g/d or 8% for the formula-fed group. Estimates of intake for some infants varied substantially between the two methods of measurement. When the estimated values of human milk intake were corrected for environmental water influx and insensible water loss during breast-feeding, the relative bias decreased to 5%. Correction of the estimated values of formula intake for environmental water influx decreased the relative bias to 1-2%. The acceptability of the deuterium dilution method to determine milk intake depends on the goals and the tolerance for error in group and individual intake estimates of a given study.

Body Height↗
PubMed1991

Energy requirements of breast-fed infants.

Current recommendations for energy intake are reviewed in light of emerging data on energy intakes of breast-fed infants and on total daily energy expenditure of infants. For determination of energy requirements, the historical approach based on observed intakes of healthy infants is compared with a newly proposed approach based on energy expenditure and deposition. A data set of exclusively breast-fed infants is used to illustrate the circuity of either approach. Energy intake, expenditure, and stores must be evaluated in an assessment of dietary adequacy. Ultimately, energy requirements of infants should reflect growth rate, body composition, and level of physical activity conducive to optimal health and neurobehavioral development.

Basal Metabolism↗
PubMed1991

Vitamin K in colostrum and mature human milk over the lactation period--a cross-sectional study.

Vitamin K was quantitated in the milk of four groups of 15 mothers from 1 d to 6 mo postpartum in a cross-sectional study. Concentrations were 7.52 +/- 5.90 and 6.36 +/- 5.32 nmol/L (3.39 +/- 2.66 and 2.87 +/- 2.40 micrograms/L) in colostrum and mature milk, respectively. Differences between colostrum and mature milk or among samples of mature milk collected at 1, 3, and 6 mo were not statistically significant. Because of significantly increased volumes of milk over the lactation period, approximately twice as much vitamin K was delivered in mature milk as in colostrum. Within normal ranges, concentrations of vitamin K in milk were not predicted by dietary intake of vegetables or fat. Vitamin K was correlated with fat in colostrum and was localized in the lipid core of the milk fat globule but was not associated with membranes. Vitamin K in human milk is insufficient to meet recommended intakes for infants aged less than 6 mo. Population and clinical studies are needed to assess the vitamin K status of exclusively breast-fed infants and to evaluate current recommendations.

Adult↗
PubMed1991

Heart rates of breast-fed and formula-fed infants.

Heart rates of 46 breast-fed and formula-fed infants were monitored continuously for approximately 18 h at 1 or 4 months of age. Heart rate differed significantly by age (1 month greater than 4 months; p less than 0.001) and feeding mode (breast-fed less than formula-fed; p less than 0.001). Approximately 58% of the variability in heart rate could be attributed to feeding mode, sex, and age. Heart rate was correlated significantly with energy intake (r = 0.60; p less than 0.001), but not sleeping metabolic rate or total daily energy expenditure. Energy intake accounted for none of the variability in heart rate beyond that explained by feeding mode, sex, and age.

Age Factors↗
PubMed1991

Origin of intact lactoferrin and its DNA-binding fragments found in the urine of human milk-fed preterm infants. Evaluation by stable isotopic enrichment.

The origin of intact (78-kD) lactoferrin found in the urine of human milk-fed preterm infants was investigated using human milk containing proteins enriched with [13C]leucine and [15N2]lysine or [2H4]lysine. Mothers of infants selected for the study were infused i.v. with [13C] leucine and [15N2]lysine or [2H4]lysine to label milk proteins. The labeled milk was collected from each mother, pooled, fortified with a lyophilized human milk fraction, and fed to her preterm infant by continuous orogastric infusion for a period of 48 h. Urine was collected from each infant for 96 h. Intact lactoferrin (78 kD) and DNA-binding lactoferrin fragments (51 and 39 kD) were purified from the urine by affinity chromatography on columns of immobilized single-stranded DNA-agarose. The concentration and isotopic enrichment of the intact lactoferrin and DNA-binding fragments were determined separately after their isolation by high-performance reverse-phase (phenyl) chromatography. Mass spectral analyses indicated that the isotopic enrichment of the purified urinary lactoferrin was 87 to 100% of that in the labeled human milk lactoferrin. Similar results were obtained for the isolated DNA-binding lactoferrin fragments. The ratios of isotopically labeled leucine to lysine in the purified milk lactoferrins and urinary lactoferrins were similar for each mother/infant pair. Isotopically labeled lysine, added to the milk as free amino acid, was not incorporated into the purified urinary lactoferrin. These results demonstrate that undegraded (78-kD) lactoferrin of maternal origin is absorbed by the gut and excreted intact in the urine of preterm infants; nearly all of the urinary lactoferrin was of maternal origin. The possible immunoregulatory functions of the absorbed intact, maternal lactoferrin are discussed.

DNA-Binding Proteins↗
PubMed1990

Energy intakes of human milk-fed infants during the first year.

A discrepancy between current recommendations for energy intakes and the reported intakes of human milk-fed infants has led to the suggestion that energy requirements of infants should be reevaluated. Gross energy intakes of 1-month-old, exclusively breast-fed infants are similar to recommended amounts of metabolizable energy; however, by 4 months of age, gross energy intakes of exclusively breast-fed infants are significantly less than current recommendations. Weight-for-age percentiles also fall during that period. Energy intakes (measured in kilocalories per kilogram) persist at less than recommended amounts, and weight-for-age percentiles continue to drop after solid foods are added to the diet. Energy intakes of formula-fed infants appear significantly higher than those of infants who are fed human milk. Growth rates, total daily energy expenditure, sleeping metabolic rates, minimal rates of energy expenditure, rectal temperature, and heart rates have been found to be lower in breast-fed infants. The maintenance of energy intakes and growth trajectories during the period of demand supplementation with solid foods suggests that intakes, growth rates, and rates of energy expenditure of human milk-fed infants are physiologic responses to an appropriate dietary intake.

Body Weight↗
PubMed1990

Energy utilization of breast-fed and formula-fed infants.

Breast-fed and formula-fed infants (n = 65) were studied at 1 and 4 mo of age to elucidate differences in energy utilization between feeding groups. Gross energy intake at 1 mo was comparable between groups but was statistically different at 4 mo. Weight, length, and weight gain were not different between groups. Energy expenditure 0-4 h postprandially did not differ between feeding groups. Sleeping metabolic rates (SMRs) were not different but minimal observable energy expenditures standardized by weight were lower among 4-mo-old breast-fed infants (p less than 0.03). No differences were found between feeding groups in thermic effect of feeding (TEF). Activity patterns revealed that breast-fed infants slept less than formula-fed infants (p less than 0.04). Disparities in energy intake observed between breast-fed and formula-fed infants at 4 mo of age did not result in statistically significant differences in growth rate, SMR, or TEF.

Analysis of Variance↗
PubMed1990

Dietary protein and nitrogen balance in lactating and nonlactating women.

Adaptive responses of body protein metabolism to dietary protein intakes of 1.0 g.kg body wt-1.d-1 were determined by nitrogen balance and urinary 3-methylhistidine excretion in lactating and nonlactating women. Despite higher energy intakes (p less than 0.04), lactating women had lower nitrogen balances compared with nonlactating postpartum and nulliparous women (p less than 0.001). Nitrogen losses in milk did not account entirely for these differences. Nitrogen balance showed linear (p less than 0.04) and quadratic (p less than 0.03) trends over time postpartum among the lactating women. Urinary 3-methylhistidine excretion also was reduced (p less than 0.05) in lactating compared with nonlactating women. These observations suggest that protein intakes of 1.0 g.kg body wt-1.d-1 in lactating women are associated with adaptive responses that promote the conservation of skeletal muscle protein stores and that currently recommended dietary protein allowances may be insufficient to meet the nutritional needs of well-nourished lactating women.

Adaptation, Physiological↗
PubMed1990

Basal and postprandial metabolic rates in lactating and nonlactating women.

Basal and postprandial metabolic rates were determined by indirect calorimetry in lactating, nonlactating postpartum, and nulliparous women who received a controlled diet of protein at 1.0 g.kg-1.d-1 and energy that approximated usual intake levels on the basis of diet records. Milk production was measured by the test-weighing procedure and by milk expression. Basal metabolic rates (BMRs) were similar among all groups of women. No relationships were detected between BMRs and postpartum time in lactating women. In contrast, postprandial metabolic rates (PMRs) increased (P less than 0.01) in lactating compared with nonlactating women. Milk nitrogen concentrations but not energy showed a linear relationship with PMR (r = 0.86, P less than 0.001). The energy cost of milk production was estimated to be 125% of the energy output in milk. Thus, increased energy needs during lactation are associated not only with milk production but also with elevated PMRs. This increase was met by an increase in dietary energy intakes of 50% above the intakes of nonlactating counterparts.

Adult↗
PubMed1990

Molecular forms of lactoferrin in stool and urine from infants fed human milk.

The molecular forms of lactoferrin (LF) were examined in stools and urine collected at 2.5 or 5 wk of age from very low birth wt infants fed either a cow's milk formula or a fortified human milk preparation. LF was not found by Western blotting in excreta from infants fed cow's milk. In contrast, intact and fragmented forms of LF were detected in stools and concentrated urine of each infant who received human milk. Only intact LF was detected in the fortified human milk preparation, whereas many types of LF fragments were present in the stools and urine. The approximate molecular wt of the most prominent fragments were 44, 38, 34, and 32 kD. However, the stools also displayed lower molecular wt fragments that were not found in urines of those infants. The LF fragments in those excreta were similar in size to those produced in vitro by limited digestion of apo-LF with trypsin. Furthermore, fragments produced by in vitro proteolysis were immunoreactive in an ELISA for LF. Thus, the fragments of LF in stools of very low birth wt infants fed human milk appeared to be produced by in vivo proteolysis, and the close resemblance between the LF fragments in the stools and urine suggests that the urinary LF fragments originated in the gastrointestinal tract. It remains unclear, however, whether the whole LF molecules that were fragmented were derived solely from ingested LF in human milk or in part from LF produced by the infant in response to human milk feedings.

Animals↗
PubMed1990

Energy expenditure and deposition of breast-fed and formula-fed infants during early infancy.

The energy intake, expenditure, and deposition of 40 breast-fed and formula-fed infants were investigated at 1 and 4 mo of age to explore possible differences in energy utilization between feeding groups. Energy intake was calculated from 5-d test-weighing records or pre- and postweighing of formula bottles, in combination with bomb calorimetry of the milks. Total daily energy expenditure (TDEE) was determined by the doubly labeled water method. Sleeping metabolic rate (SMR) and minimal observable energy expenditure were measured by indirect calorimetry. Activity was estimated as the difference between TDEE and SMR. Energy deposition was estimated from dietary intake and TDEE. Energy intakes were significantly higher for the formula-fed than breast-fed infants at 1 mo (118 +/- 17 versus 101 +/- 16 kcal/kg/d) and 4 mo (87 +/- 11 versus 72 +/- 9 kcal/kg/d) (p less than 0.001). TDEE averaged 67 +/- 8 and 64 +/- 7 kcal/kg/d at 1 mo and 73 +/- 9 and 64 +/- 8 kcal/kg/d at 4 mo for the formula-fed and breast-fed infants, respectively, and differed between feeding groups (p less than 0.04). SMR and minimal observable energy expenditure (kcal/min) were higher among the formula-fed infants at 1 and 4 mo (p less than 0.005). The energy available for activity and the thermic effect of feeding did not differ between feeding groups. Rates of weight gain (g/d) and energy deposition (kcal/kg/d) tended to be greater among the formula-fed infants at 1 and 4 mo (p less than 0.006).(ABSTRACT TRUNCATED AT 250 WORDS)

Basal Metabolism↗
PubMed1990

Comparison of energy expenditure estimated in healthy infants using the doubly labelled water and energy balance methods.

The doubly labelled water method was used to estimate energy expenditure in 20 formula-fed infants (10 aged 1 month and 10 aged 4 months). We then compared the energy expenditure values with energy balance values calculated from energy intake and energy cost of growth. Our purpose was to compare various published equations for calculating CO2 expiration rates (and thus energy expenditure values) from the isotopic data. Those equations in which we used measured values for 18O and 2H isotope dilution spaces and estimated or measured values for insensible water losses yielded energy expenditure values (69.7 +/- 8.4 kcal/kg/d) that agreed most closely with energy balance data (70.3 +/- 11.9 kcal/kg/d). Equations in which we used a constant ratio of 1.03 between the 2H and 18O isotope dilution spaces resulted in energy expenditure values (66.3 +/- 10.2 kcal/kg/d) lower than those predicted by the energy balance data. Data analysis by nonlinear curve fitting compared to logarithmic transformation did not alter the estimates of energy expenditure obtained in these infants.

Child Development↗