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Biomedical subjects

B A Baker

Publications and source records attributed to B A Baker.

18 recordsLinked to original sources
PubMed1990

The pattern of childhood hepatitis B infection in two Gambian villages.

Serologic markers of hepatitis B virus (HBV) infection were measured in children from Manduar and Keneba, two adjacent villages in The Gambia, in 1980 and in 1984. The rate of HBV infection over the 4 years differed markedly: in Manduar 71% of children who were less than 5 years of age in 1980 became infected, whereas in Keneba only 37% became infected. Male children were more frequent carriers of either HBs or e antigen than were female children. Marked clustering of hepatitis B surface antigen (HBsAg) antigenemia within sibling relationships was shown in both villages. The chance of the youngest child in a household being a carrier of HBsAg was strongly related to the number of antigen-positive siblings. Four years later, 53% of children who were initially positive for HBsAg and 33% who were positive for hepatitis B e antigen still carried these antigens. Jaundice was not observed.

Adolescent↗
PubMed1990

Plasma prolactin and clinical outcome in preterm infants.

Plasma prolactin was measured weekly in 280 preterm infants. The complex gestational age dependent pattern of postnatal prolactin release has been defined and reference standards provided. Plasma prolactin was higher in girls, with increasing divergence between the sexes from the third week onwards, and higher after two weeks, in infants of mothers with pregnancy related hypertension. Diet, assigned randomly, exerted a major effect on plasma prolactin, with significantly higher values in infants fed donor breast milk or standard formula than in those fed a protein, energy, and mineral enriched preterm formula. After adjusting for confounding factors, infants with the lowest plasma prolactin concentrations (less than 1000 mU/l, 32.9 micrograms/l) occurring usually at a nadir between days 5 and 12, showed a 120% increase in the duration of ventilatory assistance required, a 20% increase in the number of days to attain full enteral feeds, and a 30% decrease in length gain. We suggest preterm birth disrupts the normal perinatal pattern of prolactin release and that those infants who develop relatively low plasma concentration have an adverse outcome. Our data add to the broader debate on whether preterm infants require multiple endocrine replacement treatment.

Age Factors↗
PubMed1989

High alkaline phosphatase activity and growth in preterm neonates.

In a study on 857 infants born preterm, high peak plasma alkaline phosphatase activity was independently related to slower growth rate in the neonatal period, and to a highly significant reduction in attained length at 9 months and 18 months post term. At 18 months the deficit in body length associated with peak neonatal plasma alkaline phosphase activity of 1200 IU/l or more was 1.6 cm (95% confidence interval 0.9 to 2.3 cm) after adjusting for confounding factors. The strength and magnitude of this association between high plasma alkaline phosphase activity and body length was greater than that for any other factor identified, including the infant's sex and the presence of fetal growth retardation. Data are presented that support the view that the high plasma alkaline phosphatase activity reflected early bone mineral substrate deficiency resulting in metabolic bone disease. We speculate that even silent early bone disease may interfere with the control of subsequent linear growth and emphasise the potential importance of providing preterm infants, especially those fed human milk, with adequate substrate for bone mineralisation.

Alkaline Phosphatase↗
PubMed1989

Verapamil-associated Stevens-Johnson syndrome.

Stevens-Johnson syndrome (SJS) is a complication infrequently associated with the use of calcium-channel blocking agents. A 59-year-old woman developed symptoms typical of SJS approximately ten days following the initiation of sustained-release verapamil for hypertension management. Symptoms consisted of a generalized red macular rash associated with swelling of the face, tongue, lips, and mouth as well as a fever of 40 degrees C. Resolution of symptoms began approximately four days after verapamil discontinuation. Rechallenge with verapamil was not performed. Although SJS appears to be a rare adverse effect of this drug, the potential complications warrant the inclusion of SJS in the differential diagnosis of patients presenting with malaise, fever, rash, and a history of verapamil ingestion.

Female↗
PubMed1988

Plasma testosterone in preterm infants with cryptorchidism.

Cryptorchidism is common in infants born preterm, yet the mechanism for its occurrence is still debated. In a study of 21 premature babies with cryptorchidism at 18 months post-term and 21 case matched controls, cryptorchid preterm infants failed to show the normal rise in plasma testosterone in the first postnatal week. This rise is thought to relate to residual maternal human chorionic gonadotrophin in the neonatal circulation. Infants with cryptorchidism also failed to show the later testosterone surge in the second month which has been related to endogenous gonadotrophin release. We speculate that inadequate stimulation of testosterone release by human chorionic gonadotrophin in the fetus might contribute to the pathogenesis of cryptorchidism in preterm infants. Our findings have implications for the medical treatment or possible prophylaxis of undescended testes in premature babies.

Age Factors↗
PubMed1988

Low plasma triiodothyronine concentrations and outcome in preterm infants.

A major association has been found between low plasma triiodothyronine concentrations in preterm neonates and their later developmental outcome. Plasma triiodothyronine concentration was measured longitudinally in 280 preterm infants below 1850 g birth weight. Babies whose lowest recorded concentration was less than 0.3 nmol/l had, at 18 months' corrected age, 8.3 and 7.4 point disadvantages in Bayley mental and motor scales and a 8.6 point disadvantage on the academic scale of Developmental Profile II, even after adjusting for a range of antenatal and neonatal factors known to influence later development. Low concentrations of triiodothyronine were strongly associated with infant mortality, but not after adjusting for the presence of respiratory illness. There was no association between plasma triiodothyronine concentrations and somatic growth up to 18 months, and no association with necrotising enterocolitis or later cerebral palsy. Data on postnatal changes in plasma triiodothyronine concentrations are presented for reference purposes. While cited reference ranges for plasma triiodothyronine concentration appear suitable for well infants above 1500 g birth weight, smaller or ill babies often have very low values for many weeks. Our data are relevant to the debate on endocrine 'replacement' treatment in premature babies.

Age Factors↗
PubMed1988

Comparative bioavailability of two oral sustained-release procainamide products.

The bioavailability characteristics of two sustained-release oral procainamide preparations, Procan SR and Pronestyl-SR, were compared in 10 patients with arrhythmias. Each patient was randomly assigned to receive either Procan SR 1 g or Pronestyl-SR 1 g, both administered orally every six hours. The initial drug was continued for 48 hours (eight doses), at which time the second drug, given at the same dosage and dosing interval, was substituted for a 48-hour period. Serum samples for procainamide determination were obtained hourly between 42 and 48 and between 90 and 96 hours after initiation of procainamide therapy. Values for area under the serum concentration-time curve (AUC) during the steady-state dosing interval, maximum serum drug concentration (Cmax), minimum serum drug concentration (Cmin), Cmax:Cmin ratio (representing fluctuations in serum drug concentrations within the dosing interval), and the time to maximum serum drug concentration (tmax) were determined. Mean ( +/- S.D.) tmax values for Procan SR and Pronestyl-SR were 2.2 +/- 0.8 hours and 3.8 +/- 1.1 hours, respectively. Only the differences between tmax values were statistically significant. The study had an 83% chance of detecting a 20% difference in AUC values. The chances of detecting a 20% difference in values for Cmax and Cmin were 62% and 71%, respectively. These two preparations would probably possess similar therapeutic properties when given at the same dosage and dosing schedule; however, studies with larger subject populations are needed to project bioavailability data to the general population.

Aged↗
PubMed1987

An automated enzymic micromethod for the measurement of fat in human milk.

Most (98%) of the fat in human milk is present as triglycerides. This paper describes the use of a clarification procedure that enables the level of human milk fat to be determined by measurement of glycerol released by enzymic hydrolysis of triglycerides. The method requires only 10-50 microliters milk, thus presenting a possible technique for work with small mammals, and is suitable for use with autoanalysers, permitting rapid sample throughput.

Autoanalysis↗
PubMed1986

Breast milk jaundice in premature infants.

In randomised study of 186 preterm infants those fed on maternal or banked breast milk had a significantly higher peak bilirubin concentration and a more prolonged jaundice than infants fed an artificial preterm formula and were over four times more likely to achieve plasma bilirubin values above 200 mumol/l (11.7 mg/100 ml). This dietary effect was seen even in a high risk subgroup of sick ventilated infants below 1500 g who were receiving restricted enteral intakes. We suggest that breast milk jaundice in preterm infants may increase clinical intervention. Our findings are discussed in the light of epidemiological data suggesting an association between moderate hyperbilirubinaemia (greater than 170 mumol/l) and neurodevelopmental outcome.

Bilirubin↗
PubMed1985

Production of insulin resistance by hyperinsulinaemia in man.

It has been proposed that hyperinsulinaemia may cause or exacerbate insulin resistance. The present studies were undertaken to test this hypothesis in man. Glucose utilization, glucose production, and overall glucose metabolism at submaximally and maximally effective plasma insulin concentrations (approximately 80 and approximately 1700 mU/l), and monocyte and adipocyte insulin binding were measured in normal volunteers on two occasions: once after 40 h of hyperinsulinaemia (25-35 mU/l) produced by infusion of insulin and once after infusion of saline (75 mmol/l; plasma insulin approximately 10 mU/l). After 40 h of hyperinsulinaemia, glucose utilization and overall glucose metabolism at submaximally and maximally effective plasma insulin concentrations were both slightly, but significantly, reduced compared with values observed after the infusion of saline (p less than 0.05), whereas glucose production rates were unaffected. Monocyte and adipocyte binding were also unaffected. These results indicate that hyperinsulinaemia of the magnitude observed in insulin resistant states, such as obesity, can produce insulin resistance in man. Assuming that human insulin sensitive tissues possess spare insulin receptors and that monocyte and adipocyte insulin binding accurately reflect insulin binding in insulin-sensitive tissues, the decreased maximal responses to insulin and the lack of change in insulin binding suggest that this insulin resistance occurred at a post-binding site.

Adipose Tissue↗
PubMed1976

The relative effects of a low-protein-high-carbohydrate diet on the free amino acid composition of liver and muscle.

1. Free amino acid concentrations in the plasma have been compared with those in liver and quadriceps muscle, in rats fed on diets containing 209 (control) and 31 (low-protein) g protein/kg. The effects of the low-protein diet on diurnal variations in these values were also measured. 2. In the plasma, the total amino acid concentration was significantly lower in animals given the low-protein diet, at all times of day except 12.00 hours. In the liver, and to a lesser extent the muscle, total amino acid concentration was maintained. 3. In the control animals, diurnal variation in the concentrations of both essential and nonessential amino acids was very similar in plasma, liver and muscle. In animals given the low-protein diet, although the same diurnal pattern was maintained for non-essential amino acids, that occurring among the essential amino acids had virtually disappeared 4. In plasma, the mean 24 h concentration of essential amino acids decreased from 2-43 mmol/l in control animals to only 1-29 mmol/l in the low-protein-fed animals. Concentrations in muscle and liver were reduced by a similar proportion (from 8-60 to 5-56 mumol/g and from 8-67 to 5-05 mumol/g respectively). Conversely the concentrations of non-essential amino acids in animals given the low-protein diet were increased in plasma (from 1-53 to 2-00 mmol/l), muscle (from 12-5 to 14-3 mumol/g), and liver (from 16-8 to 20-5 mumol/g), muscle showing the lowest increase. 5. With the exceptions of lysine, threonine, cystine and tyrosine, the concentrations of all other essential amino acids were reduced more in liver than in muscle. The relationship between this and the failure to maintain plasma albumin concentations is discussed.

Amino Acids↗
PubMed1976

The effect of cortisone acetate on the course of development of experimental protein-energy malnutrition in rats.

1. The role of corticosteroids in determining which clinical features of protein-energy malnutrition develop on a deficient diet has been studied by the administration of cortisone acetate to experimentally malnourished rats fed ad lib. on a mixture containing 31 g protein/kg. 2. Daily administration of 1-25 mg cortisone acetate did not affect dietary intake, which remained the same as in saline (9 g sodium chloride/l)-injected controls. Plasma albumin concentrations, however, increased from a low value of 25-7 g/l to 47-2 g/l and this was accompanied by an increase both in liver weight and protein content. On the other hand, the protein content of muscle decreased. 3. These changes in the protein contents of liver and muscle were associated with alterations in the corresponding free amino acid pools. The free amino acid content of muscle generally decreased, but in liver many amino acids were increased.

Adrenal Cortex Hormones↗