Newborn Plasma Research Articles

Age-dependent changes of plasma renin concentration in humans.

1. Plasma renin concentration (PRC) in newborns greatly exceeded PRC in children and adults. PRC in cord plasma of newborns was higher than peripheral venous PRC in their mothers. PRC in the newborns increased further in the first 48 h post partum and then gradually decreased. 2. The mean PRC of healthy children and adults on free sodium intake decreased with age by an exponential function. 3. The absolute increase of PRC in response to upright posture (PRCupright — PRCrecumbent) decreased with age. The relative increase of PRC in response to upright posture (PRCuprjght:PRCrecumbent) remained unchanged with age, the PRC in upright posture being about twice the basal PRC in all age groups.

Fibrinogen derivatives with a higher molecular weight than that of the parent molecule in cord vein plasma of newborns. II. Further characterization from pooled plasma.

Fibrinogen derivatives with a higher molecular weight than that of the parent molecule in cord vein plasma of newborns. II. Further characterization from pooled plasma.

Fibrinogen derivatives with a higher molecular weight than that of the parent molecule in cord vein plasma of newborns. I. Identification in single plasma samples.

Fibrinogen derivatives with a higher molecular weight than that of the parent molecule in cord vein plasma of newborns. I. Identification in single plasma samples.

Thyrotropin levels in the plasma of newborns with congenital goiter.

Immediately after birth thyrotropin (TSH) levels in plasma are higher in newborns than in adults (1). 48 hours later the elevated TSH levels decline by two thirds. From the 3rd day on they gradually reach adult levels. In three newborns with congenital goiter due to high iodine intake by their mothers during pregnancy, Job et al. (2) found excessively high TSH levels in plasma. This prompted us to investigate plasma TSH, PBI, TBI, total T4 and bone age in 23 newborns with congenital goiter. 43 normal newborns served as controls in order to establish normal ranges. Plasma TSH was determined by the double antibody radioimmunoassay according to Odell et al. (3).

Plasma deoxycorticosterone in normal and abnormal pregnancy.

Using a competitive protein binding method, plasma deoxycorticosterone (DOC) was measured in 43 pregnant women. Elevated levels were first detected at 23–24 weeks and peak values were found near term. Mixed cord plasma DOC levels were significantly higher than maternal levels at the time of delivery, suggesting that the feto-placental unit was the source of the elevated maternal DOC. Suppression of maternal pituitaryadrenal axis with dexamethasone did not lower maternal plasma DOC levels. Following delivery both maternal and newborn plasma DOC rapidly fell, reaching normal adult levels within 24–30 hr. An umbilical arterial-venous gradient of plasma DOC at the time of birth was not found, suggesting that the fetal adrenal itself was not the sole source of the DOC arising from the feto-placental unit. Maternal plasma DOC levels of 7 women with toxemia of pregnancy during the third trimester were not significantly different from levels found in women with normal pregnancies of similar duration.

Binding of drugs to cord plasma

The purpose of the present work is to compare the binding of several drugs—diphenylhydantoin (DPH), cephalothin (CPT), cephaloglycin (CPG), imipramine (IMI), and diazoxide (DX) to plasma from adults and from newborns. Adult plasma was collected from 3 healthy subjects and cord plasma from 9 term newborns. The drugs, except for DX, were 14C labeled. After equilibrium dialysis with the plasma sample, the % binding of drug to plasma was determined. In this series, the average albumin in the adult plasma is 4.1 and in cord plasma 3.4 gm%. For each of the drugs studied, the binding to adult plasma is greater than to cord plasma. The average value for binding of DPH to cord plasma is 74% compared to 83% bound in adult samples. Using CPT, 72% of the drug is bound in cord plasma and 80% in adult plasma. CPG is not highly bound and the difference is not striking (60% to cord plasma and 63% to adult plasma). The binding of IMI to adult plasma is 89% and to cord plasma is 74%, but this drug is bound to plasma proteins other than albumin since binding to 3% human albumin is only 61%. DX is a very hightly bound drug in both cord plasma (88%) and adult plasma (92%). The differences in binding between adult and newborn plasma can be correlated most clearly with reduced albumin concentration in the newborn. If adult plasma is diluted to the albumin concentration of cord plasma, the binding data are similar to that for cord plasma. The infant, with normally lower plasma albumin levels, will therefore have a greater fraction of free drug in plasma which is available for tissue distribution and for glomerular filtration.

Plasma lipids of newborn and adult ruminants and of lambs from birth to weaning

The plasma lipid concentrations of newborn lambs, kids and calves and of adult ruminants in 0various physiological states have been reported. In newborn ruminants plasma lipid concentrations were 20–40 % of those found in their dams at parturition.The concentrations of blood lipids have also been estimated in five lambs from birth to weaning at 90 days post partum. The plasma free fatty acid concentrations rose to a maximum at about 45 days post partum and then declined. Possible reasons for this elevation in plasma free fatty acids have been discussed with reference to published data on age changes in lambs of plasma glucose and volatile fatty acid concentrations. The concentration of plasma esterified lipids, mainly phospholipids and cholesterol esters, were very low at birth and rose to reach maximum values at about 20 days post partum before declining to adult values at weaning. These changes have been discussed in relation to diet and rumen development.

Effects of maternal metaboHc acidosis on the human fetus and newborn infant

The effects of maternal metabolic acidosis on fetal acid-base balance have been studied by comparing the P_co₂, pH, and bicarbonate levels in maternal, fetal, and newborn human blood plasma. Observations have been made without superimposed maternal acidosis during and following the slow infusion of ammonium chloride and during and following more rapid infusion. The results demonstrate that maternal metabolic acidosis is not necessarily accompanied by fetal or neonatal metabolic acidosis. Despite significant reductions in the maternal plasma HCO⁻₃ and pH, the fetal levels remain relatively unchanged. As the maternal pH falls, the usual transplacental pH gradient is virtually eliminated.

FACTITIAL HYPERKALEMIA DUE TO ICING BEFORE ANALYSIS

Both adult and newborn blood plasma potassium concentration rose significantly when whole blood was kept on ice for periods of 5 hours. This appears to be due to inhibition of red cell glycolysis. The rise in plasma potassium concentration of blood from newborn infants is significantly greater than that occurring in blood from adults; this difference is a function of the neonate's increased red cell volume. Meaningful interpretation of potassium concentration, particularly in the newly born, demands that the plasma be separated immediately. The plasma potassium concentration of normal newborns at birth does not differ significantly from adults; in this study the mean value in 20 infants was 4.81 mEq/l.

A peculiar benzidine-positive protein fraction in the plasma of newborns and children with various hemolytic conditions.

A peculiar benzidine-positive protein fraction in the plasma of newborns and children with various hemolytic conditions.

PLASMA CORTISONE AND CORTISOL LEVELS AT BIRTH AND DURING THE NEONATAL PERIOD.

Cortisol and cortisone were measured in maternal and cord plasma, as well as in newborn plasma, by a double isotope dilution derivative assay. An assessment of the reproducibility, precision and sensitivity of the method is presented. It was found that cortisone concentration in cord plasma is greater than in maternal plasma, that following birth the plasma level of cortisone is maintained during at least the first week of life, and that both cortisol and cortisone concentration increased following the administration of ACTH.

Lipoprotein lipase in plasma of the normal newborn: preliminary report.

SummaryLipoprotein lipase in plasma after heparin administration has been studied in six newborn infants immediately after birth and in six normal children between the ages of 7 and 17 years. The activity of lipoprotein lipase was, according to the suggestions of Boberg & Carlson [1], evaluated: (1) as the elimination rate of this enzyme from plasma, expressed in terms of half‐life, and (2) as the value for the lipoprotein lipase activity extrapolated at zero time after the heparin injection, expressed in terms of μEq of fatty acids released from a triglyceride substrate, per ml plasma per min.The values for the lipoprotein lipase activity in plasma thus obtained were not appreciably lower in the newborns than in the older children. The elimination rate of the lipoprotein lipase activity amounted in the newborns to 15.4 min and in the older children to 13.3 min (average values); if there was any difference, the elimination of lipoprotein lipase seemed thus to be a little slower in the first‐mentioned group. The implication of these findings is discussed in relation to the possible role of dietary fat as inducer of the production of the production of the lipoprotein lipase enzyme.

Excretion of phenol red and inulin by the fetal and the newborn rabbit.

Simultaneous clearances of phenol red (PSP) and inulin (in) were measured in fetal, newborn and adult rabbits. The clearances were determined from single injection and single blood and urine collections. This method tends to reduce the numerical values of the clearances but not to change the ratios of the two clearances when compared with clearances obtained by conventional methods in adult rabbits. The CPSP/Cin ratio fell from a fetal value of 0.4 to a newborn level of 0.2 and then rose to approximate the adult ratio of 2.0 by 1 month after birth. The use of plasma PSP concentrations both above and below the adult TmPSP did not influence significantly the clearance ratios in young animals. The percentage of total PSP not bound to plasma proteins, determined by ultrafiltration, was more in the newborn plasma (30%) than in adult plasma (4%). Both are greater than might be predicted from an adsorption isotherm using constants determined in adult blood by others. It was concluded that the rise in clearance ratio with age probably reflected both an increase in filtration with age and a greater increase in tubular secretion with age; and that these factors were more important than corresponding changes in the binding of PSP by plasma proteins in young and adult animals.

Prothrombin activity of blood of the newborn.

SummaryWhen adult and newborn plasmas were mixed in varying proportions, the prothrombin time which was 12 seconds for each plasma remained unaltered in the series of mixtures. This suggests that the prothrombin activity i.e., the concentration of active prothrombin, is the same in the plasma of the newborn baby as in that of the adult.