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Biomedical subjects

H Bard

Publications and source records attributed to H Bard.

At least 91 records · Page 5Linked to original sources
PubMed1980

Elective delivery and the neonatal respiratory distress syndrome.

A prospective study was carried out to determine how often moderate or severe respiratory distress syndrome in infants delivered electively after 32 weeks' gestation or more is avoidable. During a 9-month period 64 such newborns were evaluated. The disease was considered avoidable in 14 (22%) since the indication for elective delivery was questionable. The mean birth weight and gestational age of these 14 infants were 2550 +/- 430 g and 36.3 +/- 1.7 weeks, and the mortality was 14%. This study demonstrated that elective delivery can produce severe neonatal complications, that despite their availability diagnostic tests of fetal age and maturity of the fetal lungs are not being used universally, and that the indications for elective delivery in cases of premature rupture of the membranes must be re-evaluated.

Adult↗
PubMed1980

Relationship of 2,3-diphosphoglycerate and 2,3-diphosphoglycerate mutase in various mammals.

To investigate a possible mechanism involved in the regulation of 2,3-diphosphoglycerate (2,3-DPG) synthesis, 2,3-DPG mutase (DPGM) was measured in different mammals presenting large differences in 2,3-DPG concentration between fetal, neonatal and adult life to see the activity of this enzyme, necessary for 2,3-DPG synthesis, was related to the levels of 2,3-DPG. The data demonstrated that the minimal levels of 2,3-DPG in the adult sheep are likely due to the very low levels of DPGM. Also these findings show that the increases in 2,3-DPG levels, found in the newborn sheep during the 1st week of life, in adult rabbit and guinea pig when compared with their fetuses, are not due to an increase in levels of the DPGM.

2,3-Diphosphoglycerate↗
PubMed1979

Perinatal changes of 2,3-diphosphoglycerate and oxygen affinity in mammals not having fetal type hemoglobins.

The interrelationship of 2,3-diphosphoglycerate (2,3-DPG) and P50 levels during the fetal and postnatal life were determined in two mammalian species which do not have a switchover of hemoglobin type at the end of their fetal development. In the guinea pig and rabbit, the 2,3-DPG levels remain low during fetal life and increase only after birth remaining elevated throughout adult life. The adult levels were reached at 2 days of age in the guinea pig and the 20th day in rabbit. Fetal P50 values increased only after birth, paralleling the rise in the 2,3-DPG. The rapidity of the postnatal rise in 2,3-DPG and decrease in P50 appears related to the maturity of the newborn animal at birth in these species.

Animals↗
PubMed1979

Red cell oxygen affinity, hemoglobin type, 2,3-diphosphoglycerate, and pH as a function of fetal development.

Studies were carried out on fresh cord blood obtained at delivery from nonstressed normal fetuses ranging from 24 to 42 weeks of gestation, to determine the relationship of 2,3-diphosphoglycerate (DPG), the intracellular red cell and extracellular pH, and the proportions of adult and fetal hemoglobin in regulating the position of fetal red cell oxygen affinity in utero. There was a significant positive correlation between P50 and gestational age (r = .62, P less than .001), the linear regression increased from 17.8 to 22.5 mm Hg. There was also a significant positive correlation between P50 and the percentage of adult type hemoglobin (HbA) (r = .67, P less than .001). In contrast gestational age had no effect of 2,3-DPG levels, the mean and SD was 14.86 +/- 2.04 mol/gm of Hb or delta pH between plasma and red cell, the mean was 0.187 +/- SD 0.032. However, there was a significant negative correlation between the intraerythrocyte hydrogen ion concentration and DPG level (r = .5, P less than .025). It is concluded therefore that the decrease in fetal oxygen affinity as gestation progresses is related mainly to the increase in the amount of HbA and the levels of DPG or delta pH between plasma and red cells are not a function of gestational age.

Blood↗
PubMed1978

Red cell oxygen affinity in fetal sheep: role of 2,3-DPG and adult hemoglobin.

Studies were carried out during fetal life in sheep to determine the relationship of 2,3-diphosphoglycerate (DPG), the intracellular red cell and extracellular pH, and the switchover to adult hemoglobin synthesis in regulating the position of the fetal red cell oxygen-affinity curve in utero. Adult hemoglobin first appeared near 120 days of gestation. The mean oxygen tension at which hemoglobin is half saturated (P50) prior to 120 days of gestation remained constant at 13.9 +/- 0.3 (SD) Torr and then increased gradually as gestation continued, reaching 19 Torr at term. During the interval of fetal life studied, the level of DPG was 4.43 +/- 1.63 (SD) micromol/g Hb and the deltapH between plasma and red blood cells was 0.227 +/- 0.038 (SD); neither was affected by gestational age. The decrease in the red cell oxygen affinity after 120 days of gestation ocrrelated with the amount of adult hemoglobin present in the fetus (r = 0.78; P less than 0.001). This decrease can be attributed only to the amount of the adult-type hemoglobin present, and not to DPG, or to changes in the deltapH between plasma and red blood cells, because both remained stable during the last trimester.

Animals↗
PubMed1976

The postnatal hypotransferrinemia of early preterm newborn infants.

Preterm newborns were found to be markedly hypotransferrinemic when compared with normal term infants. At birth the concentration of transferrin in sera from preterm infants of gestational age equal to or less than 32 weeks is 45% of that found in normal term infant sera. The preterm infant transferrin levels slowly rise so that 7-8 weeks after birth they are 78% of the level found in the sera of normal term infants. We also found that the serum transferrin concentrations at birth correlate with gestational age. Therefore, the transferrin levels postnatally in early preterm infants reflect postconceptional rather than postnatal age.

Animals↗
PubMed1976

The adaptation of the fetal red cells of newborn lambs to extrauterine life: the role of 2,3-diphosphoglycerate and and adult hemoglobin.

The purpose of this study was to determine the interrelationship of the rise and fall of 2,3-diphosphoglycerate (DPG) with the increase in adult hemoglobin and the decrease in red cell oxygen hemoglobin affinity after birth in normal lambs. It was found that the mean maximum DPG level was 26.71 +/- 4.98 mol/g Hb at 7.5 +/- 1.1 days. At the same time the mean P50 and adult hemoglobin level was 27.0 +/- 1.4 mm Hg and 31.1 +/- 11.i%, respectively. In the individual lambs, the level of their maximum DPG correlated inversely with the amount of adult hemoglobin (r-0.77, P less than 0.05). Once the DPG began to decrease, there was an inverse correlation between the DPG and the adult hemoglobin present in the red cell (r = 0.68, P less than 0.001). It appeared that the rise in DPG postanatally is only a compensatory mechanism until an adequate amount of adult hemoglobin is present. This fact was borne out by the second part of the study in which exchange transfusions with adult red cells were performed on five newborn lambs during the first 24 hr after birth and aborted the rise in DPG.

Adaptation, Physiological↗
PubMed1975

Correction of the malabsorption of the preterm infant with a medium-chain triglyceride formula.

After receiving milk-based formula for one week, 16 preterm infants, weighing 1,300 to 1,800 gm, were fed two isocaloric formulas containing either medium-chain or long-chain triglycerides for 15 days; the alternate formula was given for a second period of identical duration. While receiving MCT, the infants had greater (P smaller than 0.01) percent fat absorption (83.4 leads to 97.1%) and weight gain (7.5 leads to 11.5 gm/kg/100 calories). Because metabolic acidosis occurred with the LCT formula, the chloride content was adjusted to that of the MCT were confirmed and, in addition, there was a higher (P smaller than .01) percent retention of nitrogen (67.3 leads to 82.1).

Body Weight↗
PubMed1975

The postnatal decline of hemoglobin F synthesis in normal full-term infants.

Studies were carried out during the 1st yr of life in normal infants born at term to determine the proportions of fetal hemoglobin (Hb F) and adult hemoglobin (Hb A) being synthesized, in order to describe the complete switchover from Hb F to Hb A synthesis during postnatal life. 53 blood samples from 37 infants were incubated in an amino acid mixture containing [14C]leucine and chromatographed on DEAE-Sephadex for separation of Hb F and Hb A fractions. The completeness of the CEAE-Sephadex separation of Hb A and Hb F at an age when the major portion of synthesis was of the adult type of hemoglobin was confirmed by globin chain chromatography with the use of carboxylmethyl cellulose. There was a rapid decline in Hb F synthesis postnatally until 16-20 wk of age when levels of 3.2% plus or minus SD 2.1% were reached. By combining this data with that previously published, the complete switchover from Hb F to Hb A synthesis can be described in humans in relation to postconceptional age. It follows a sigmoid curve; the steep portion, which lies between the 30th and 52nd postconceptional week, is preceded and follwoed by plateaus averaging 95% and 7% Hb F synthesis, respectively.

Age Factors↗