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Biomedical subjects

G W Chance

Publications and source records attributed to G W Chance.

At least 55 records · Page 3Linked to original sources
PubMed1978

Development of a spin assay for reserve bilirubin loading capacity of human serum.

The capacity of human serum albumin to bind bilirubin is of paramount importance in the prevention of neurological damage due to hyperbilirubinemia in the neonate. Currently, there is no rapid, reliable method to determine the reserve bilirubin loading capacity of serum albumin. A method using electron spin resonance spectroscopy with a dianionic spin-label molecular probe [1-N-(2,2,6,6-tetramethyl-1-oxyl-4-piperidinyl)-5-N-(1-aspartate)-2,4-dinitrobenzene] is presented which yields the reserve binding capacity of the bilirubin high-affinity binding site on human serum albumin and reserve bilirubin loading capacity of serum in mg/dl. Clinical validation of this spin assay may improve the neonatal care of jaundiced newborns.

Bilirubin↗
PubMed1977

Impaired assimilation of nasojejunal feeds in healthy low-birth-weight newborn infants.

We compared nasojejunal with nasogastric tube feeding in 18 healthy low-birth-weight infants from eight to 15 days of age. NJ-fed infants had significantly more stools and excreted significantly more fat and potassium in their stools. Growth and weight gain did not differ between the groups during the study period. Future use of NJ feeding in LBW infants should take into account the possibility of malabsorption associated with this technique.

Enteral Nutrition↗
PubMed1977

Postnatal growth of infants of less than 1.3 kg birth weight: effects of metabolic acidosis, of caloric intake, and of calcium, sodium, and phosphate supplementation.

Weekly increments of length, weight, head circumference, and skinfold thickness in response to a series of dietary changes were measured in 108 healthy infants who weighed less than 1.3 kg at birth. The serial manipulations included prevention of late metabolic acidosis, increased caloric intake, and calcium, sodium, and phosphorus supplementation. The study comprised four phases; the infants were divided into ten groups according to dietary regimen. AGA and SGA infants were studied separately. Growth in length was primarily influenced by a change to a formula providing a higher caloric intake and a 60:40 whey protein/casein ratio. Correction of late metabolic acidosis, sodium, and phosphorus supplementation had minor additive effects on growth in length. Increased caloric intake also influenced growth of head circumference, but only in AGA infants. Only the sodium intake was shown to influence body weight increments significantly with the range of caloric intake used in the study (132 to 160 calories/kg/day).

Acidosis↗
PubMed1976

Electrolyte abnormalities in very low birthweight infants.

In 30 very low birth weight (VLBW) infants, fed a commercial formula at 200 ml/kg/24 hr to provide 160 cal/kg/24 hr, hyponatremia (plasma Na+ less than 130 mEq/liter) occurred in 23 patients (14 appropriate for gestational age (AGA), 9 small for gestational age (SGA)) between the ages of 2 and 6 weeks. In five infants the hyponatremia recurred even after adequate correction of the deficit. Calcium supplementation given to 14 of the infants did not affect the incidence or severity of hyponatremia. In AGA infants, the hyponatremia was more severe than in SGA babies. Hyperkalemia (plasma K+ greater than 5.5 mEq/liter) was more common in AGA than in SGA infants (16/17 AGA, 7/13 SGA). Decrease in mean plasma chloride concentrations was proportionate to the decrease in mean Na+. Urinary Na+ averaged 1.0 mEq/kg/24 hr and was equal between groups during the first balance at a mean age of 18 days. In subsequent balances it appeared to decrease more rapidly in noncalcium-supplemented than in calcium-supplemented infants, but the difference was not significant (P less than 0.1). Fecal excretion of Na+ did not differ between groups. Symptoms were unrelated to the degree of hyponatremia or hyperkalemia and were nonspecific. Hyponatremia in AGA infants occurred in 50% of instances when growth was less than or equal to 0.75 cm/week, whereas it occurred in only 13.5% of infants when growth exceeded 1 cm/week (P less than 0.01). A similar trend in SGA infants was not statistically significant (P less than 0.2).

Calcium↗
PubMed1976

Late hyponatremia in very low birthweight infants. (less than 1.3 kilograms).

Late hyponatremia (plasma Na+ less than 130 mEq/liter) occurred frequently (on 54 of 159 occasions) in 46 very low virthweight (VLBW) infants (less than 1.3 kg at birth) between 2 and 6 weeks of age while receiving a sodium intake of less than or equal to 2 mEg/kg/24 hr. To elucidate possible pathogenetic mechanisms five groups of such infants were studied while receiving a commercially available formula reconstituted to give two different volumes and two different Na+ concentrations. Sodium intake in the nonsupplemented (NS) infants (n = 23) was less than 2 mEq/kg/24 hr. Supplemented (S) infants (n = 16) received approximately 3 mEq Na+/kg/24 hr. A further group of seven infants given a high volume (200 ml/kg/24 hr), high caloric (100 cal/dl) formula and Na+ supplementation (to 3 mEq/kg/24 hr) was also included. Infants were studied from age 14 days until they weighed 1.80 +/- 0.05 kg at a mean age of 47 days. At the time of start of the study, 6 of 20 NS and 6 of 19 S infants were hyponatremic. After supplementation only two episodes of hyponatremia occurred in S infants, both during the first study week, whereas the high incidence of hyponatremia in NS infants period. During baseline urine collections all infants excreted between 80 and 100 ml/kg/24 hr urine, but those receiving 150 ml/kg/24 hr formula decreased their urinary output rapidly to 50 ml/kg/24 hr, whereas infants receiving high volume feeds (200 ml/kg/24 hr) did not decrease their urinary output until the third balance at an average age of 45 days. All infants excreted between 1.0 and 1.2 mEq/kg/24 hr of sodium in their urine during the initial collection. Nonsupplemented infants reduced their urinary Na+ excretion more rapidly than supplemented babies (NS: from 1.03 to 0.55 mEq/kg/24 hr, first vs second balance; S: from 1.00 to 0.80 mEq/kg/24 hr, first vs third balance). Mean potassium excretion remained unchanged in NS and S infants during the study period and was not affected by the volume or caloric content of the formula. Extracellular volume (ECV) and total body water (TBW) were measure serially, and there were no differences between S and NS infants in the distribution of body water. The percentage of TBW and ECV decreased in all groups with increasing postnatal age.

Body Water↗
PubMed1975

Growth and mineral metabolism in very low birth weight infants. I. Comparison of the effects of two modes of NaHCO3 treatment of late metabolic acidosis.

Twenty-six infants weighing less than 1,300 g at birth were divided into pairs according to birth weight (900-1,100 and 1,101-1,300 g) and gestational age ("appropriate" (AGA) = mean 31 weeks; and "small" (SGA) = mean 34 weeks). One member of the pairs was then allocated randomly to one of two treatment regimens with oral sodium bicarbonate. Group A was treated whenever base excess was greater than -8mEq/liter as detected on twice weekly testing and/or when suspected to be acidotic from failure to gain weight. In group B, base excess was maintained within 1 SD of normal (-3.2 +/- 1.7 mEq/liter). The infants received Enfalac 200 ml/kg/24 hr, at 67 cal/100 ml, with vitamin D 400 IU/24 hr added from age 2 weeks. The following measurements were made: daily weight, weekly length, skinfold thickness, head circumference, twice weekly blood pH, PaCO2, base excess, and weekly plasma total calcium, ionic calcium, total magnesium, inorganic phosphorus, and total protein. There were six pairs of each of AGA and SGA infants and two unpaired group A infants. Weekly weight gains did not differ between group A and group B or between AGA and SGA. Length increment was greater in AGA than in SGA babies (0.94 +/- 0.02 vs 0.85 +/- 0.04 cm/week) but not significantly so (P less than 0.1), and in group B babies compared to group A babies (0.973 +/- 0.029 vs 0.83 +/- 0.037 cm/week) (P less than 0.01). Plasma pH was lower in group A (7.23 +/- 0.02) than in group B (7.30 +/- 0.02) and calcium ion activity higher (group A 2.72 +/- 0.04; group B 2.51 +/- 0.06 mEq/liter) between ages 20 and 29 days. Plasma magnesium was higher in group A (1.77 +/- 0.04 mEq/liter) than in group B (1.56 +/- 0.06 mEq/liter) from age 20 to 39 days. Inorganic phosphorus concentrations were consistently higher in group A than in group B, but the differences did not reach significance. Mean total protein concentrations did not rise above 4.5 g/100 ml and tended to be higher in babies of group A than of group B. Bone age was retarded in all babies. Radiographs available for 7 of 13 SGA infants were normal, whereas 6 of 11 radiographs of AGA babies showed some osteoporotic changes.

Acidosis↗
PubMed1975

Growth and mineral metabolism in very low birth weight infants. II. Effects of calcium supplementation on growth and divalent cations.

Infants of two groups, one of 16, one of 14 infants, who weighed less than 1.3 kg at birth (mean 1.01 +/- 0.05 kg), were studied from age 14 days until they reached 1.8 kg body weight. Infants were pair-matched for gestational age and birth weight and one member was randomly allocated to two treatment groups. Infants in group A received no calcium supplement and those in group B received calcium lactate, 800 mg/kg/24 hr hr, in divided doses with each feed. All were fed "Improved" SMA, 200 ml/kg/24 hr, 160 cal/kg/24 hr, and were given a multivitamin preparation containing 500 IU vitamin D2/dose. The infants' weekly length gain did not differ between groups (1.08 +/- 0.04 cm/week vs 1.11 +/- 0.04 cm/week; mean +/- SEM). Mean weight and head cercumference increments also were similar (group A, 163 +/- 6 g/week; 1.12 +/- 0.03 cm/week; group B, 170 +/- 6 g/week and 1.18 +/- 0.03 cm/week). An increase in blood pH from 7.33 +/- 0.01 to 7.41 +/- 0.01 (P less than 0.01) in group A babies was associated with a decrease in PCO2 from 44.2 +/- 1.0 to 38.9 +/- 1.4 mm Hg. Values remained unchanged with age in group B babies...

Birth Weight↗
PubMed1973

Transportation of sick neonates, 1972: an unsatisfactory aspect of medical care.

An analysis of personnel and facilities used for transfer of sick newborn infants to the Neonatal Intensive Care Unit of The Hospital for Sick Children, Toronto during the months November 1971 and February to April 1972 showed many deficiencies. In many instances severely ill patients were accompanied by inadequately trained staff, transport incubators were either inadequate to maintain the babies' temperatures or were used inappropriately, resuscitation facilities were not available and oxygen concentrations could neither be measured nor varied as desired.Infants who weighed less than 1500 g. at birth and who died following transfer had significantly lower mean body temperatures on arrival at the referral hospital than those who survived. Mean transport incubator temperatures were too low in all groups of infants but were lower in those who died, although the difference was not statistically significant.

Age Factors↗
PubMed1971

Maternal factors in neonatal hypocalcaemia: a study in three ethnic groups.

To assess the significance of various maternal and neonatal factors in the aetiology of neonatal tetany we have investigated the serum calcium, phosphorus, magnesium, and heat-labile alkaline phosphatase of 250 mothers from three ethnic groups at several stages of pregnancy and the serum calcium, phosphorus, and magnesium of many of their infants. Subclinical hypocalcaemia was found to be much commoner in full-term infants on the sixth day of life than is generally appreciated, especially during the winter months and in babies of Asian parents. It is considered that this is a result of high phosphorus loads in artificial milks and is also influenced by maternal vitamin D and possibly calcium intake during pregnancy. The importance of ensuring that Asian women take adequate vitamin D supplements during pregnancy is stressed.

Alkaline Phosphatase↗