Maternal-administered physical activity enhances bone mineral acquisition in premature very low birth weight infants.

OBJECTIVE: To determine if physical activity delivered by an infant's mother would be as effective in promoting bone mineral acquisition in preterm very low birth weight (VLBW) infants as the same intervention administered by a trained therapist. PATIENTS AND METHODS: Preterm VLBW infants were randomized to receive daily physical activity administered by the infant's mother (MOM, n=11) or a trained therapist (OT, n=11), or control (n=11). Physical activity consisted of range of motion movements against passive resistance to all extremities for 5 to 10 min daily. All infants were fed mother's milk with fortification to 24 kcal oz(-1). Dual energy x-ray of the forearm bone area (BA, cm(2)), mineral content (BMC, g), and density (BMD, g/cm(2)) and measurement of bone formation (bone-specific alkaline phosphatase, BAP) and resorption (urine pyridinium crosslinks of collagen, Pyd) were obtained at study entry and at 2.0 kg of body weight. RESULT: Forearm BA and BMC gains were greater in MOM and OT infants compared to the control infants despite similar postnatal growth rate and nutrient intake. Serum BAP levels decreased in controls but remained unchanged in MOM and OT infants. Urine Pyd levels were similar at baseline to 2.0 kg for all groups. These findings suggest greater bone growth and mineral acquisition in MOM and OT infants than control infants. CONCLUSION: This study demonstrates that a physical activity program administered by the infant's own mother is as equally effective as therapist-administered physical activity in promoting greater bone growth and mineral acquisition in preterm VLBW infants.

The use of fat-free human milk in infants with chylous pleural effusion.

OBJECTIVE: The purpose of this study is to describe the processing of human milk to remove its fat content and its use in seven infants with chylothorax. STUDY DESIGN: The mother's milk was centrifuged at 3000 r.p.m. for 15 min at 2 degrees C. After centrifugation, the milk separated into a solidified-fat top layer and a lower liquid portion. The fat-free liquid portion was then poured into collection cups and frozen for the patient's use at a later date. A sample of the mother's milk before and after processing was stored and analyzed for fat, sodium, potassium, calcium and zinc. RESULTS: The mean fat removed was 5+/-1 g/dl (mean+/-s.d.), which was the same as the pre-fat content of the mother's milk. Seven infants with chylous pleural effusions used the fat-free human milk. All infants started on the fat-free milk after a month of age for an average of 16 days duration (7 to 34 days range). There was no reaccumulation of the chylous pleural effusions with the use of the fat-free mother's milk. Mother's milk electrolytes were similar before and after processing. CONCLUSION: Fat-free human milk may be an important additional dietary therapy for infants with chylothorax and may add the immunologic properties of human milk that other feedings cannot provide.

Uteroplacental insufficiency affects epigenetic determinants of chromatin structure in brains of neonatal and juvenile IUGR rats.

Intrauterine growth retardation (IUGR) increases the risk of neuroendocrine reprogramming. In the rat, IUGR leads to persistent changes in cerebral mRNA levels. This suggests lasting alterations in IUGR cerebral transcriptional regulation, which may result from changes in chromatin structure. Candidate nutritional triggers for these changes include altered cerebral zinc and one-carbon metabolite levels. We hypothesized that IUGR affects cerebral chromatin structure in neonatal and postnatal rat brains. Rats were rendered IUGR by bilateral uterine artery ligation; controls (Con) underwent sham surgery. At day of life 0 (d0), we measured cerebral DNA methylation, histone acetylation, expression of chromatin-affecting enzymes, and cerebral levels of one-carbon metabolites and zinc. At day of life 21 (d21), we measured cerebral DNA methylation and histone acetylation, as well as the caloric content of Con and IUGR rat breast milk. At d0, IUGR significantly decreased genome-wide and CpG island methylation, as well as increased histone 3 lysine 9 (H3/K9) and histone 3 lysine 14 (H3/K14) acetylation in the hippocampus and periventricular white matter, respectively. IUGR also decreased expression of the chromatin-affecting enzymes DNA methyltransferase 1 (DNMT1), methyl-CpG binding protein 2 (MeCP2), and histone deacetylase (HDAC)1 in association with increased cerebral levels of zinc. In d21 female IUGR rats, cerebral CpG DNA methylation remained lower, whereas H3/K9 and H3/K14 hyperacetylation persisted in hippocampus and white matter, respectively. In d21 male rats, IUGR decreased acetylation of H3/K9 and H3/K14 in these respective regions compared with controls. Despite these differences, caloric, fat, and protein content were similar in breast milk from Con and IUGR dams. We conclude that IUGR results in postnatal changes in cerebral chromatin structure and that these changes are sex specific.

Performance of dual-energy x-ray absorptiometry in evaluating bone, lean body mass, and fat in pediatric subjects.

We studied the performance of the dual-energy x-ray absorptiometry method in evaluating bone mineral, fat, and lean soft tissue mass. This method was accurate in quantifying known small amounts of calcium, lard, and lean tissue mass. It was also accurate in evaluating small animal ashed bones, fat, and muscle mass. The analytic sensitivity of the method was 40 mg for calcium, 180 mg for fat, and 270 mg for lean tissue mass. The method was highly correlated to the single-photon absorptiometry method in measuring bone mineral content at the radius bone in 32 children, r = 0.998. There was a difference between the two methods in older children. Long-term precision for a small bone phantom was 2.0%. Total-body, lumbar, and radial bone scans were performed on 14 newborn infants whose gestational ages ranged from 28 to 41 weeks. Both total-body bone mineral and fat mass increased with gestational age and weight. The infant's total-body calcium was also associated with length and lumbar and radial bone densities. The lumbar bone density was associated with birth weight, gestational age, length, body mass index, body fat, and radial bone density. Male infant's lumbar bone density to total-body calcium ratio was higher than female infant's lumbar bone density ratio. Dual-energy x-ray absorptiometry may be used in pediatrics with high accuracy, sensitivity, and precision.

Effects of human milk or formula feeding on the growth, behavior, and protein status of preterm infants discharged from the newborn intensive care unit.

The growth, behavior, and protein status of 59 healthy preterm (mean gestational age 30 wk) infants fed either human milk or one of three infant formulas were studied post-discharge from the hospital. Formula-fed infants received either a standard term formula, a standard preterm formula, or an experimental preterm formula from discharge to 8 wk of age. From 8 to 16 wk, all formula-fed infants received the standard term formula. At 2, 8, and 16 wk, anthropometric, dietary intake, blood biochemistry, amino acid, and Brazelton Neonatal Behavioral Assessment measurements were evaluated. Weights, lengths, and head circumferences were similar for all feeding groups at discharge. After discharge all formula-fed infants were heavier than human milk-fed infants. Length and head circumference values and plasma urea nitrogen and retinol-binding protein concentrations were not different among dietary groups. Formula-fed infants had higher plasma concentrations of numerous amino acids compared with those of human milk-fed infants during the first 8 wk but not at 16 wk. There were no differences among the feeding groups in the Brazelton assessment. This study found little effect on the growth or behavioral or protein status of preterm infants discharged from the hospital who were fed either human milk or formulas designed for term or preterm infants.

Growth and bone mineralization of normal breast-fed infants and the effects of lactation on maternal bone mineral status.

To determine if human milk provides for adequate growth and bone mineralization during the lst yr of life, 91 term infants were evaluated. Infants were divided into three groups human milk alone, human milk with supplemental vitamin D, and Similac. Lactating mothers who were receiving supplements of calcium and vitamin D were also studied to determine the effects of lactation on their bone mineral status. Blood was drawn from infants and mothers for measurements of serum calcium, phosphate, alkaline phosphatase, and 25-hydroxyvitamin D. Bone mineral content was measured by photon absorptiometry. Growth was similar between breast-fed and formula-fed infants. Regardless of type of feeding, male infants grew heavier and longer than corresponding female infants. Serum calcium and phosphate levels were similar among the three infant groups: only 25-hydroxyvitamin D levels at 4 months and serum alkaline phosphatase at 2 wk and 6 months of age were different among the three infant groups. Biochemical and vitamin D values were similar among the lactating mothers. There were no differences in infant bone mineral content among the three groups, but male infants had higher bone mineral content than female infants. There were no effects of the duration of lactation of maternal bone mineral content or vitamin D status.

Effects of increased dietary calcium intake upon the calcium and bone mineral status of lactating adolescent and adult women.

We studied the effectiveness of an increased calcium (Ca) diet in preventing bone mineral loss in lactating adolescent mothers. Three groups of lactating women were studied: 15 control adolescents consuming their usual Ca diet (900 mg/d), 21 experimental adolescents consuming a high-Ca diet (greater than 1600 mg/d), and 12 adults. At 2 and 16 wk postpartum, serum calcium, phosphate, magnesium, albumin, alkaline phosphatase, vitamin D, parathyroid hormone (PTH), and calcitonin (CT) were determined. Bone mineral analyses were performed by photon absorptiometry. By 16 wk the control adolescent group had a 10% decrease in bone mineral content (BMC) and increased PTH and CT. The experimental adolescent and adult groups had no significant change in BMC during the study. There was a positive correlation (r = 0.45, p less than 0.01) between dietary Ca intake and BMC in all adolescents. Data suggest that bone loss during lactation in adolescents may be prevented with adequate dietary Ca intakes.

Bone mineral status in children with phenylketonuria--relationship to nutritional intake and phenylalanine control.

The mineral status in phenylketonuria (PKU) was measured by single-photon densitometry of the distal radius and plasma concentrations in 26 subjects. Bone mineral content increased normally with age in the younger children despite strict dietary restrictions. Subjects aged greater than 8 y, however, were frequently below the normal curve for bone mineral content. Blood phenylalanine concentrations were significantly higher in the older group of subjects and this correlated with decreased compliance with dietary prescriptions. PKU children had significantly decreased plasma concentrations of alkaline phosphatase, magnesium, and parathyroid hormone. Subnormal concentrations of plasma zinc and plasma and red blood cell (RBC) copper were common, but RBC zinc was normal. We conclude that compliance with dietary therapy for PKU is associated with normal bone mineral development in young children. Older patients with PKU who follow the diet less carefully are at risk for low bone mineral content.

Effect of pantothenic acid status on the content of the vitamin in human milk.

Seventeen lactating women who delivered preterm infants (between 28 to 34 wk of gestational age) and 26 nursing mothers of term infants participated in the study. Each term mother kept a record of 2-day dietary intakes, collected urines for 2 days, and provided fore and hind milk samples and a fasting blood sample at 2 and 12 wk postpartum. Each of preterm women provided fore and hind milk samples once a week for 16 wk starting 2 wk postpartum. The method of determining pantothenic acid content in milk samples was validated, and the vitamin was quantitated by the radioimmunoassay. The average pantothenate levels in fore and hind samples of preterm milk (3.31 and 3.72 micrograms/ml, respectively) were significantly (p less than 0.05) higher than those of term milk (2.64 and 2.48 micrograms/ml, respectively). No significant change was observed in pantothenic acid content within a feeding or with the progress of nursing in both groups. The vitamin content of human milk was compared with the minimum requirement of the Infant Formula Act of 1980. The pantothenate level in term milk was significantly (p less than 0.05) correlated with the vitamin level in maternal circulation and with that of the dietary intake and urinary excretion.

Reserve bilirubin binding capacity assessed by difference spectroscopy: assay statistics and results on newborn sera.

Bilirubin binding properties of newborn sera and assay parameters have been investigated using a difference spectroscopy procedure [9]. Reserve bilirubin binding capacity, serum bilirubin and the total bilirubin binding capacity can be determined using only 40 microliters of serum. The measured total binding capacities agreed with the theoretical binding capacities calculated from serum albumin concentrations assuming a 1 : 1 molar binding ratio of bilirubin to albumin; in 102 assays on newborn sera, the ratio of experimental to theoretical total binding capacity was 1.04. Bilirubin binding capacity measurements were linear over the range 0--600 mg/l. Day to day precision of binding capacity determinations on 6 albumin controls yielded coefficients of variation between 4.1 and 7.2%. Recovery for the reserve bilirubin binding capacity determinations was 99.6%. In a study of 22 newborns, reserve bilirubin binding capacities showed an inverse relationship with the changes in serum bilirubin concentrations. None of the newborns included in our study appeared to be in dange of bilirubin encephalopathy.

Calcium intake and bone density of lactating women in their late childbearing years.

Researchers have shown through epidemiological surveys that osteoporosis results in hip, vertebra, or long bone fractures in at least 10% of women over 50 years of age. The primary objective of this study was to determine calcium intake and bone mineral content in lactating women in their later childbearing years. Eight lactating women over 37 years of age were compared with eight nulliparous women to determine differences in dietary intake of energy, protein, vitamin D, calcium, and phosphorus. Anthropometric measurements, bone density measurements, serum calcium, serum phosphate, and serum alkaline phosphatase measurements were made at 2 weeks and 6 weeks postpartum. Intakes of protein, vitamin D, and calcium were significantly lower in the diets of control women. No significant differences were found in biochemical analysis (except for a significantly lower serum phosphorus in the control group of women), bone density, nutrition assessment, or physical assessment between lactating and control groups. Thus, when dietary calcium intake is greater than the RDA for lactating women, bone mineral content is not affected during the first 6 weeks of lactation.

Postpartum body composition changes in lactating and non-lactating primiparas.

The objective of this study is to evaluate the postpartum body composition changes in lactating versus non-lactating or formula-feeding primiparas during the first 12 wk. Twenty primiparous females (age range 17-35 y) who decided to nurse or formula feed their infant were studied. The non-lactating mothers (n = 6) were younger (21 versus 29 y) and had a lower prepregnancy weight (55 kg versus 63 kg) than the lactating mothers (n = 14). Body weight, height, waist and hip measurements, 3-d dietary and activity records, skin-fold thickness from triceps, suprailiac, midthigh, and midupper arm circumference, and total body composition were evaluated at three time periods (at delivery, at 6 wk, and at 12 wk postpartum). Total body composition for bone mineral, lean, and fat mass was measured by dual energy x-ray absorptiometry. At delivery and 6 wk postpartum, the weights and heights were similar between the two groups. By 12 wk postpartum, the formula-feeding group had a weight loss that was different from delivery, 66 +/- 10 kg to 59 +/- 8 kg, P < 0.03. There was no significant weight change in the lactating group during the study. The weight loss consisted of more lean mass than fat mass. The total body bone mineral content did not differ between the two groups during the study. Both groups had reduction in their waist size from delivery to 12 wk postpartum. But only the non-lactating mothers had reductions in their hip and midthigh measurements. There were no changes between the two groups in the skin-fold measurements. Lactating mothers had a higher total daily calories (1974 +/- 318 versus 1464 +/- 178 calories, P < 0.002) and fat intake (63 +/- 14 versus 47 +/- 9 g, P < 0.02) than the non-lactating mothers. The energy expenditure was similar between both groups. In conclusion, during the first 12 wk postpartum, non-lactating mothers who were younger and weighed less prepregnancy lost body weight and had more waist, hip, and midthigh size reductions compared to lactating mothers.

Evaluation of transthyretin as a monitor of protein-energy intake in preterm and sick neonatal infants.

In the past, weight and weight gain have been the two parameters used frequently in neonatal units to monitor nutrition among high-risk infants. Our investigation sought to assess how several anthropometric measures (weight, length, head circumference, arm:head circumference ratio, and tricep skinfold) and serum albumin, transthyretin, and transferrin concentrations reflect protein and energy intake. After monitoring 42 preterm and 40 sick infants over 3 consecutive weeks, we found that transthyretin concentration proved the only serum protein which accurately measured energy and protein intakes in less than 1 week from dietary manipulation. Among preterm infants, as protein and energy intakes rose, transthyretin concentration increased significantly (p less than 0.001). Preterm infants ingested 79 +/- 39 kcal/kg/day and 2.04 +/- 1.02 g protein/kg/day at the first assessment point after birth and rose to 103 +/- 34 kcal/kg/day and 2.64 +/- 0.94 g protein/kg/day. Likewise, transthyretin measured 10.83 +/- 3.91 mg/dl at the initial measurement and rose to 14.80 +/- 4.44 at the second measurement time. Although protein intakes measured slightly lower in the sick group, their intakes correlated to transthyretin concentration (assessment time 1, r = 0.39; time 2, r = 0.33; time 3, r = 0.33). Thus, transthyretin concentration in neonatal infants offers a rapid, accurate, and moderately inexpensive way to monitor protein-energy adequacy.

Relation of forearm's bone and soft tissues to infant's body composition.

Small portable units using the dual X-ray absorptiometry method (pDEXA) are becoming available to evaluate a localized region of the body such as the forearm. The purpose of this study was to evaluate the relationship between infant's forearm measurements of bone mineral, lean, and fat mass and total body composition. Twenty-two infants participated in this study. Mean age of the infants was 21 d with a weight range of 1-3.6 kg. All infants were stable and had their forearm and total body scanned on the same day. The long-term precision error for the pDEXA was 0.4%. The infant's total body was scanned by the XR-26 (Norland Medical Systems, Fort Atkinson,WI). Forearm bone mineral content, bone mineral density (BMD), fat mass, and lean mass correlated to total body mineral content (BMC) (r = 0.84, p < 0.001), total body BMD (r = 0.73, p < 0.001), total fat mass (r = 0.53, p < 0.05), and total body lean mass (r = 0.80, p < 0.001). Forearm BMC, lean, and fat mass correlated significantly with body weight and length (r = 0.73-0.94). In conclusion, forearm measurements of bone mineral, fat, and lean mass reflect total body bone mineral, fat, and lean mass in small infants.

Cloning of delta12- and delta6-desaturases from Mortierella alpina and recombinant production of gamma-linolenic acid in Saccharomyces cerevisiae.

Two cDNA clones with homology to known desaturase genes were isolated from the fungus Mortierella alpina. The open reading frame in one clone encoded 399 amino acids and exhibited delta12-desaturase activity when expressed in Saccharomyces cerevisiae in the presence of endogenous fatty acid substrate oleic acid. The insert in another clone contained an open reading frame encoding 457 amino acids and exhibited delta6-desaturase activity in S. cerevisiae in the presence of exogenous fatty acid substrate linoleic acid. Expression of the delta12-desaturase gene under appropriate media and temperature conditions led to the production of linoleic acid at levels up to 25% of the total fatty acids in yeast. When linoleic acid was provided as an exogenous substrate to the yeast cultures expressing the delta6-desaturase activity, the level of gamma-linolenic acid reached 10% of the total yeast fatty acids. Co-expression of both the delta6- and delta12-desaturase cDNA resulted in the endogenous production of gamma-linolenic acid. The yields of gamma-linolenic acid reached as high as 8% of total fatty acids in yeast.

Patterns of postnatal weight changes in infants with very low and extremely low birth weights.

OBJECTIVE: To describe (1) short-term postnatal weight loss and gain patterns in infants with very low and extremely low birth weights and (2) the variables that may affect these weight change patterns. DESIGN: Descriptive, retrospective review. SETTING: University hospital in the intermountain western United States. SUBJECTS: Sixty-two charts of infants admitted to a university neonatal intensive care unit from July 1990 through November 1992 were reviewed. Infants who weighed 1000 grams or less were categorized as extremely low birth weight (ELBW) and infants weighing 1001 to 1500 grams were categorized as very low birth weight (VLBW). Each group was comprised of 31 infants. Fifty percent of the sample were male, and 50% were female. Eighty-five percent of the sample were Anglo-American, and 15% were non-Anglo-American. MEASURES: Data were collected on a three-part data collection tool and included demographic and treatment variables. RESULTS: A significant difference was found in the maximum percent weight lost between the two groups, with the ELBW group losing a mean of 14.77% of birth weight and the VLBW group losing a mean of 11.35% of birth weight (t = 2.45, p < 0.05). The day the infants reached their nadir weight was significantly different between the two groups. The ELBW group reached their nadir on day of life 7, and the VLBW group reached their nadir on day of life 6 (t = 2.00, p < 0.05). No significant difference was noted in the time to return to birth weight between the two groups, with a mean of 15 days to return to birth weight. Factors associated with postnatal weight changes were intraventricular hemorrhage, use of diuretics and steroids, day of life when nadir weight occurred, and maximum percent of weight lost. Many of the independent variables were significantly interrelated to each other (r = -0.90 to r = 0.91, p < 0.01 to p < 0.001). However, only the variables that correlated with time to return to birth weight were entered into the regression analysis. These variables included number of days diuretics were given before return to birth weight, maximum percent of weight lost, and day of life the infants reached their nadir weight. Number of days diuretics were given before return to birth weight correlated significantly with time to return to birth weight (r = 0.77, F = 26.66, p < 0.0001) although maximum percent of weight lost and day of life the infants reached their nadir weight had a minimal effect. CONCLUSIONS: Further research into the effects of diuretic therapy on weight changes in this population of infants may lead to interventions to minimize the negative effects of diuretics on return to birth weight. In addition, the older growth charts may not be applicable to this population of infants. Generation of new growth charts that provide growth curves based on these data could be useful in developing nutritional therapies that would promote growth and possibly decrease the length of hospital stay for these infants.

The effects of acidification on human milk's cellular and nutritional content.

OBJECTIVE: Fortification of human milk for preterm infants is necessary and a common newborn intensive care practice. Currently, acidified human milk as part of a human milk fortifier is being fed to preterm infants. However, there are little data on the acidification effects on mother's milk. The aim of this study is to determine the effects of acidification on human milk's cellular and nutritional composition. STUDY DESIGN: One hundred milk samples were collected from eight mothers who had infants in the neonatal intensive care unit. All milk samples were frozen at 4 °C. The frozen samples were thawed and divided into two equal aliquots, control and acidified. The control milk sample had its pH determined while the other sample was acidified to pH 4.5. Each milk sample was examined for pH, white cells, total protein, creamatocrit, lipase activity and free fatty acids. RESULT: Mean pH of the human milk control was 6.8 ± 0.1 (M ± s.d.) with the acidified milk at 4.5 ± 0.1. Acidification caused a 76% decrease in white cells, a 56% decrease in lipase activity and a 14% decrease in the total protein but a 36% increase in the creamatocrit. CONCLUSION: Acidification of human milk causes significant changes of the milk's cellular and nutritional components that may not be beneficial to preterm infants.

Effect of carotenoid supplementation on plasma carotenoids, inflammation and visual development in preterm infants.

OBJECTIVE: Dietary carotenoids (lutein, lycopene and ß-carotene) may be important in preventing or ameliorating prematurity complications. Little is known about carotenoid status or effects of supplementation. STUDY DESIGN: This randomized controlled multicenter trial compared plasma carotenoid levels among preterm infants (n=203, <33 weeks gestational age) fed diets with and without added lutein, lycopene and ß-carotene with human milk (HM)-fed term infants. We assessed safety and health. RESULT: Plasma carotenoid levels were higher in the supplemented group at all time points (P<0.0001) and were similar to those of term HM-fed infants. Supplemented infants had lower plasma C-reactive protein (P<0.001). Plasma lutein levels correlated with the full field electroretinogram-saturated response amplitude in rod photoreceptors (r=0.361, P=0.05). The supplemented group also showed greater rod photoreceptor sensitivity (least squares means 6.1 vs 4.1; P<0.05). CONCLUSION: Carotenoid supplementation for preterm infants raises plasma concentrations to those observed in HM-fed term infants. Carotenoid supplementation may decrease inflammation. Our results point to protective effects of lutein on preterm retina health and maturation.