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Biomedical subjects

G M Chan

Publications and source records attributed to G M Chan.

At least 37 records · Page 2Linked to original sources
PubMed1993

Growth and bone mineral status of discharged very low birth weight infants fed different formulas or human milk.

The objective of this study was to determine whether the growth and bone mineral status of discharged preterm infants fed human milk differed from those of infants fed one of three different formulas varying in calcium content (545 mg/L, 660 mg/L, or 1290 mg/L). A randomized, blinded study was conducted for 16 weeks after discharge in 16 human milk-fed and 43 formula-fed infants. All formula-fed infants received one of the three study formulas from discharge to 8 weeks afterward, and the standard formula, which contained 545 mg/L calcium, from 8 to 16 weeks. The human milk-fed infants gained weight more slowly than the formula-fed infants. The human milk-fed infants also had lower gains in length and higher serum alkaline phosphatase values than the formula-fed infants. The infants who received the formula containing the highest calcium concentration (1290 mg/L) had greater bone mineral density during the first 8 weeks of the study. We conclude that preterm infants recently discharged from the hospital may benefit from higher calcium intake than is provided by either human milk or standard term formula.

Anthropometry↗
PubMed1992

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.

Absorptiometry, Photon↗
PubMed1992

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.

Adolescent↗
PubMed1992

Evaluation of liquid or powdered fortification of human milk on growth and bone mineralization status of preterm infants.

Thirty-five preterm (< 1500 g) infants were fed preterm human milk (PHM) supplemented with either powdered fortifier (PF) or liquid supplement (LS). Bone mineral content (BMC) of the distal third radius was measured by photon absorptiometry. Biochemical indices of nutritional and bone status were obtained every 2 weeks. The initial BMC for both feeding regimens were similar. BMC did not change over the study period for infants fed LS. Infants fed PF had BMC values greater than LS infants at weeks 2 and 4 of study. Only infants fed PF had BMC values that demonstrated a consistent increase. Serum total protein and phosphorus values were greater for PF infants at week 4 than LS infants. Weight, length, occipital-frontal circumference (OFC) gains, serum albumin, alkaline phosphatase, calcium, and vitamin D levels were similar in both groups. We conclude that products used to "enrich" PHM are adequate to meet the growth needs of the preterm infant. However, we found that infants fed the powdered fortified preterm human milk had higher bone mineralization than those fed the liquid supplemented human milk.

Blood Chemical Analysis↗
PubMed1991

Dietary calcium and bone mineral status of children and adolescents.

We studied 164 healthy, white children aged 2 to 16 years; there were 88 boys and 76 girls. By the method of single photon absorptiometry, we found that age, height, and weight correlated positively with bone mineral content of the radius bone. In the children's diet, most of those aged 2 to 11 years met the recommended dietary allowance (800 mg daily) for calcium. Children older than 11 years had low dietary calcium intake; only 15% met the recommended dietary allowance for calcium (1200 mg daily). Dietary calcium intake was associated with bone mineral status. Children ingesting more than 1000 mg of calcium daily had higher bone mineral content than those ingesting less. Almost all serum determinations of calcium, phosphate, magnesium, alkaline phosphatase, parathyroid hormone, 25-hydroxyvitamin D, and 1,25-dihydroxyvitamin D were within normal limits and had no correlation with children's bone mineral status.

Adolescent↗
PubMed1991

Selenium status of preterm infants fed human milk, preterm formula, or selenium-supplemented preterm formula.

The selenium status of 46 orally fed vitamin E-sufficient preterm infants (birth weight less than 1700 gm) was studied longitudinally for 3 weeks to determine the efficacy of selenium supplementation. Infants were fed either human milk (n = 21; 24 ng selenium/ml), preterm formula (n = 13; 7.8 ng selenium/ml), or preterm formula supplemented with sodium selenite (n = 12; 34.8 ng selenium/ml). Plasma and erythrocyte selenium and glutathione peroxidase activity and urinary and dietary selenium content were evaluated on study day 1 (day enteral feeds reached 100 kcal/kg/day) and weekly for 3 weeks. Throughout the study, selenium intakes of infants fed preterm formula plus sodium selenite were greater than those of infants fed human milk, which were greater than those of infants fed preterm formula (p less than 0.001). After 3 weeks no differences were observed among groups for plasma or erythrocyte selenium or glutathione peroxidase. Plasma selenium and glutathione peroxidase values within all groups were low compared with those reported for term infants fed human milk. Whereas urinary selenium levels of infants fed preterm formula plus sodium selenite were greater than those of infants fed preterm formula at weeks 1 and 2 (p less than 0.01), infants fed human milk and preterm formula had lower levels at week 3 than on study day 1 (p less than 0.05). We conclude that blood selenium measurements typically used to monitor selenium status do not reflect dietary selenium intakes of orally fed preterm infants.

Enteral Nutrition↗
PubMed1988

Calcium and phosphorus requirements in bone mineralization of preterm infants.

We studied postnatal bone mineralization, as measured by photon absorptiometry, in 36 preterm infants (birth weight less than 1600 gm) who were fed (1) a commercial premature formula containing 117 mg calcium and 58.8 mg phosphorus per 100 kcal, (2) the same formula containing a higher concentration of phosphorus (82 mg/100 kcal), (3) the same formula with higher concentrations of calcium (140 mg/100 kcal) and phosphorus (82 mg/100 kcal), or (4) their mother's milk. Serum calcium, phosphorus, protein, albumin, bicarbonate, 25-hydroxyvitamin D, and alkaline phosphatase levels were measured at the start of the study and every 2 weeks until the infants achieved a weight of 1900 gm. Birth weights and gestational ages were similar in all four groups. The human milk group had lower serum phosphate and bone mineral values than those in the three formula groups. Bone mineral content was similar in the three formula groups. However, only the formulas of the first and third groups allowed approximation of the intrauterine bone mineralization curve. Bone mineral content in infants fed human milk was below the intrauterine rate.

Bone and Bones↗
PubMed1987

Effects of soy formulas on mineral metabolism in term infants.

We studied 40 healthy term infants who received a soy-based formula containing either a single carbohydrate (glucose polymers) or dual carbohydrates (glucose polymers and sucrose). Ten exclusively breast-fed infants served as controls for the first four months of the study. All infants were studied at 2 weeks, 2 months, and 4 months of age for anthropometric development, biochemical values, and bone mineral content. There were no differences among the three groups in weight, length, or head circumference gains. Serum levels of calcium, phosphorus, magnesium, copper, 25-hydroxycholecalciferol, and alkaline phosphatase were also similar. However, at 4 months of age, the breast-fed group had a higher plasma zinc level than both formula-fed groups, and at 2 and 4 months of age, it had higher bone mineral content and bone density.

Calcium↗
PubMed1987

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.

Adolescent↗
PubMed1987

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.

Adult↗
PubMed1986

Nutritional support of very-low-birth-weight infants requiring prolonged assisted ventilation.

We studied the influence of nutritional support on weight loss and time to regain birth weight (BW) (less than 1500 g) in infants requiring prolonged assisted ventilation. A total of 134 infants admitted between 1980 and 1982 were reviewed. Birth weight, gestational age, lowest recorded daily weight and percentage of loss, days to recover BW, energy intake, and nutrient source during the BW-recovery period were determined. A decrease in weight loss (13% to 10%) and in mean (+/- SD) recovery time (20.9 +/- 7.3 days to 13.8 +/- 6.4 days) in very-low-birth-weight, critically ill infants was noted. The use of parenteral feeding routes increased, as well as tolerance of initial enteral feedings following parenteral support. We attribute the decreased convalescence period for BW recovery to improved nutrition secondary to the increased use and earlier initiation of parenteral nutrition.

Body Weight↗
PubMed1985

Posthospitalization growth and bone mineral status of normal preterm infants. Feeding with mother's milk or standard formula.

The growth and bone mineralization were studied in ten preterm infants fed human milk and 14 preterm infants fed cow's milk-based formula. After discharge from the hospital, at 42, 48, and 56 weeks' postmenstrual age, anthropometric measures of weight, length, occipital frontal circumference, mid-upper arm circumference, triceps, and subscapular skin folds were obtained. Blood was drawn for determinations of serum calcium, phosphorus, 25-hydroxyvitamin D, alkaline phosphatase, and albumin levels. Bone mineral analyses were performed by photon absorptiometry. Mean (+/- SD) gestational ages in nursing and formula-fed infants were similar (32.0 +/- 2.5 vs 31.5 +/- 1.5 weeks), as were their mean (+/- SD) birth weights (1.76 +/- 0.42 vs 1.52 +/- 0.30 kg). After hospitalization, both groups had similar rates of growth in weight, length, head circumference, mid-upper arm circumference, triceps, and subscapular skinfold thickness. The formula-fed group had higher serum phosphorus levels at 42 weeks, higher serum calcium levels at 48 weeks, and higher serum albumin concentrations at 56 weeks than the breast-fed group. By 56 weeks' postmenstrual age, the bone mineral content was higher in the formula-fed group. Our data suggest that after hospitalization, preterm infants fed their own mother's milk have similar growth patterns but a different bone mineralization rate compared with preterm infants fed a standard cow's milk-based formula.

Alkaline Phosphatase↗
PubMed1984

Bone mineral status in childhood accidental fractures.

We studied the bone mineral and calcium (Ca) status of 17 children who suffered an accidental fracture in 1980. These children were matched by age and sex to a nonfractured control group. Blood was drawn for serum Ca, phosphorus, magnesium, 25-hydroxycholecalciferol ( calcidiol ), alkaline phosphatase, and albumin. Bone mineral content (BMC) was evaluated by photon absorptiometry. There were no differences in serum values between the two groups. Twelve (71%) of the 17 children in the fracture group had a lower BMC than their matched controls. The BMC of the fracture group was lower than their controls, 0.423 +/- 0.042 v 0.461 +/- 0.037 g/cm. Four of the 15 in the fracture group ingested less than 60% of the recommended dietary allowance (RDA) for Ca and P (800 mg/day), while all the controls were ingesting at least 60% of the RDA. Four children of the fracture group who were ingesting less Ca and P than those of the control group also had low BMC.

Alkaline Phosphatase↗
PubMed1984

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.

Adult↗
PubMed1984

A microassay for serum dialyzable calcium and magnesium by ion chromatography.

We describe a method for determining dialyzable calcium and dialyzable magnesium in 50-microliter volumes of routinely handled aerobic serum. Calcium and magnesium concentrations were measured by ion chromatography after a 1-min equilibrium dialysis. Day-to-day precision (coefficient of variation, CV) was 3.8% for dialyzable calcium and 4.5% for dialyzable magnesium. Dilution of serum with water 1:1 as well as storage at 4 or -20 degrees C had no significant effects. Reference intervals for dialyzable calcium (58.1-68.1 mg/l) and magnesium (12.3-17.1 mg/l) were determined for 26 healthy adults. Lack of interference and the ability to determine simultaneously several analytes on a single specimen are advantages of the chromatographic method.

Adult↗
PubMed1984

Comparison of serum total calcium, dialyzable calcium, and dialyzable magnesium in well and sick neonates.

We studied the relation of serum total calcium, dialyzable calcium, and dialyzable magnesium in 61 well and sick newborn infants aged 7-76 h. The infants' serum total calcium, dialyzable calcium and magnesium concentrations (ion chromatography method) were studied in comparison with the infant's history and sickness scale. We found that serum total calcium and dialyzable magnesium were lower in sick infants compared to well infants. Both serum total and dialyzable calcium concentrations initially decreased and then increased by about 30 h of age. Serum dialyzable magnesium concentrations increased with our infants' age. Serum total calcium values correlated significantly with the infant's birth weight, gestational age, 1-min Apgar score, respiratory distress, severity of sickness, serum bilirubin and sodium concentrations.

Aging↗