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Biomedical subjects

D L Shannon

Publications and source records attributed to D L Shannon.

12 recordsLinked to original sources
PubMed1985

Body water content and distribution in nonpregnant adult female baboons.

Water contents of the various body water compartments were estimated in 16 nonpregnant adult female baboons and compared to human data. Total body water, extracellular water, and plasma volumes were determined by dilution studies. Intracellular water, interstitial water, blood volume, and red cell volume were calculated. The data were compatible with the finding that baboon females probably have less body fat than their human counterparts. Our data establish a basis for longitudinal studies of the changes in body water content and distribution during normal and pathological pregnancies.

Animals↗
PubMed1984

Amniotic fluid composition in normal baboon pregnancies.

In order to compare the chemical composition of baboon and human amniotic fluid, 70 amniotic fluid samples were obtained from 58 normal baboon pregnancies at times ranging from 88 to 178 days (term, 180 days). Protein content averaged (+/- S.E.) 0.67 +/- 0.26 gm/dl, osmolality averaged 263 +/- 1.1 mOsm/kg, and pH averaged 7.74 +/- 0.034 units. These variables were not affected by length of gestation. Creatinine content increased parabolically with duration of gestation (r = 0.74; p less than 0.001). Forty percent of the samples had delta OD450 values of 0; the others had delta OD450 values ranging from 0.002 to 0.145. No decline in delta OD450 with gestational maturity was evident. These data suggest that the chemical environment of the baboon fetus is similar but not identical to that of the human fetus.

Amniotic Fluid↗
PubMed1983

Maternal diabetes and neonatal macrosomia. II. Neonatal anthropometric measurements.

Anthropometric measurements were obtained within 12 h of birth in 52 infants of non-diabetic mothers and 61 infants of diabetic mothers. Most of the diabetic patients were under good control, only ten of 61 having postpartum hemoglobin A1c levels in excess of normal. Neonates were grouped as normally-grown or macrosomic. Birthweight, crown-heel length, head circumference and skinfold thickness were measured. In each diabetes class, macrosomic neonates had larger mean length, head circumference and skinfold thickness than their normally-grown peers. At equal birthweight, neonates of gestational diabetic mothers and of non-diabetic mothers were similar in length, head circumference and skinfold thickness. Neonates of permanently insulin-requiring diabetics were similar to their non-diabetic peers in length and head circumference but had thicker skinfold thicknesses. Anthropometric measurements do not permit differentiation of the origin of neonatal macrosomia.

Anthropometry↗
PubMed1983

Maternal diabetes and neonatal macrosomia. III. Neonatal body water estimates.

Body water estimates were obtained within 12 h of birth in 52 infants of non-diabetic mothers and 61 infants of diabetic mothers. Neonates were grouped as normally-grown or macrosomic. Total body water and extracellular water were estimated from antipyrine space and corrected bromide space, respectively. Intracellular water was assumed to be the difference between total and extracellular water. Infants of diabetic mothers, whether normally-grown or macrosomic, had markedly less mean total body water than normally-grown neonates of non-diabetic mothers. No effect of neonatal macrosomia or maternal diabetes on extracellular and intracellular water estimates could be detected with the techniques used. It is suggested that changes in total body water occur as a result of excessive fat accretion during fetal life.

Adipose Tissue↗
PubMed1983

Body water estimates in neonatal polycythemia.

To determine whether neonatal polycythemia and its treatment by partial exchange transfusion affect body water estimates, 10 normocythemic and eight polycythemic neonates were studied within 12 hours of birth. Total body water, extracellular water, and plasma volume were estimated immediately prior to and following exchange. Intracellular and interstitial water contents were calculated. There were no significant differences between normocythemic and preexchange polycythemic neonates in mean total body water, extracellular water, interstitial water, and intracellular water contents. In the polycythemic group, exchange did not affect mean total body water, but was associated with decreases in mean extracellular water and mean interstitial water and an increase in mean intracellular water. Mean transcapillary escape rate of T-1824 was not affected by exchange but was quite rapid both before (35 +/- SE 3%/hr) and after the procedure (30 +/- 4.9%/hr). These data suggest that moderate polycythemia in normal term neonates does not affect total and extravascular body water estimates, but that a fluid shift from the extracellular to the intracellular space may accompany the exchange procedure.

Body Water↗
PubMed1983

Plasma lipid levels in preterm neonates receiving parenteral fat emulsions.

Concentrations of various plasma lipid fractions were determined during 96 hours of continuous parenteral infusions of lipid emulsions in 10 normally-grown neonates whose birth-weights ranged from 960 to 1760 g and whose gestational ages ranged from 26 to 32 weeks. Total lipid, triglyceride, free glycerol, and free fatty acid concentrations were measured. During lipid infusions, mean plasma concentrations of all lipid fractions increased above the mean preinfusion values if 2 g/kg a day or more of lipid emulsion was used. There were no further significant increases in mean plasma lipid levels if the infused dosage was increased to 3 or 4 g/kg a day. At these higher infusion rates however, there were considerable individual variations. The only neonate less than 27 weeks of gestation had plasma lipid levels severalfold higher than any of his peers, his plasma was frankly creamy on visual inspection, and the study had to be stopped. Further investigations are needed to determine the optimal modalities of parenteral nutrition with fat emulsions.

Fat Emulsions, Intravenous↗
PubMed1982

Maternal diabetes and neonatal macrosomia. I. Postpartum maternal hemoglobin A1c levels and neonatal hypoglycemia.

Hemoglobin A1c (HgbA1c) levels were determined within 24 hours after delivery in 88 nondiabetic and 73 diabetic women belonging to White's classes A to D. Diet-controlled gestational diabetic women had mean (+/- SE) Hgb A1c levels similar to those of nondiabetics (5.8 +/- 0.18% vs 5.7 +/- 0.08%). Mean Hgb A1c levels were higher in insulin-requiring gestational (6.4 +/- 0.20%, P less than .05) and permanent (6.5 +/- 0.27%, P less than .05) diabetics than in nondiabetics. The proportions of subjects with levels above the normal range were also larger in the insulin-requiring groups. Mean Hgb A1c levels and the proportions of abnormally high levels were similar for mothers of macrosomic and of normally grown neonates in the nondiabetic as well as in the various diabetes groups. There was no correlation between maternal Hgb A1c level and neonatal birth weight, either real or relative. There were also no statistically significant differences in mean Hgb A1c levels between mothers of neonates with or without hypoglycemia within four hours of birth. Hgb A1c measurement did not permit differentiation between those mothers of macrosomic neonates who were diabetic and those who were not. In conclusion, although Hgb A1c level has been shown to reflect diabetic control, our data suggest that it may not be reliable as an indicator of fine tuning during the third trimester of pregnancy or as a predictor of the effects of diabetes on the fetus.

Adult↗
PubMed1981

Chemical changes in human skeletal muscle during fetal development.

Skeletal muscle samples obtained from 6 nonmacerated stillborn fetuses and 18 liveborn neonates who died within 24 h of birth were analyzed. Gestational age ranged from 19 to 44 weeks. 17 neonates were normally grown (NG) and 7 were intrauterine growth retarded (IGR). Chemical components were expressed in milliliters or grams per 100 g of tissue. As gestation progressed, total water (TW) and extracellular water (ECW) contents decreased, intracellular water (ICW) content and nitrogen content remained stable, and intracellular/total water ratio (ICW/TW) increased. Fat content was negligible throughout gestation. Compared to their NG peers, IGR neonates had muscle with decreased ECW and increased ICW/TX, whereas TW, ICW and nitrogen contents were similar. These preliminary data provide a basis for further studies of muscle composition and for discussion of existing hypotheses on the effect of fetal growth retardation upon body composition.

Body Composition↗
PubMed1981

Neonatal polycythemia: II. Plasma, blood and red cell volume estimates in relation to hematocrit levels and quality of intrauterine growth.

Volumes of plasma (PV), blood (BV), and red cells (RCV) were estimated within 32 hours of birth in 39 neonates with normal growth, 14 neonates with intrauterine growth retardation, and 20 neonates with macrosomia. Total PV, BV, and RCV increased linearly with birth weight and were unaffected by deviation in the quality of fetal growth. In proportion to body weight, PV/kg, BV/kg, and RCV/kg correlated neither with birth weight nor with the quality of intrauterine growth. Neonates with umbilical vein hematocrit (UV Hct) levels 51% to 60%, 61% to 65%, and 66% to 77% had progressively lower, but not statistically different, mean PV/kg (38.1 +/- 4.49, 37.6 +/- 5.41, and 34.8 +/- 5.16 ml/kg, respectively). On the other hand, they had progressively higher mean BV/kg (90 +/- 10.1 vs 101 +/- 13.7 ml/kg, P less than .002, and vs 110 +/- 19.0 ml/kg, P less than .001). They also had progressively higher mean RCV/kg (52 +/- 7.4, 64 +/- 8.7, and 75 +/- 16.4 ml/kg, P less than .001). Although PV/kg did not correlate with UV Hct, both BV/kg and RCV/kg increased linearly with increasing UV Hct (r = .58 and r = .79, respectively). Volume estimates were repeated after partial exchange transfusion in 29 neonates. Mean UV Hct decreased from 63 +/- 5.9% preexchange to 51 +/- 5.2% postexchange (P less than .001), mean PV increased from 37.7 +/- 5.56 to 47.6 +/- 7.99 ml/kg (P less than .001) and mean RCV decreased from 67 +/- 16.5 to 51 +/- 12.3 ml/kg (P less than .001). Despite precautions to keep the partial exchange isovolemic, mean BV decreased from 105 +/- 18.7 to 98 +/- 18.0 ml/kg (P = .001) and the mean PV increase (10 ml/kg) was less than the mean RCV decrease (16 ml/kg). These data suggest that neonates with polycythemic have normal PV but their RCV and BV are elevated in direct proportion to UV Hct. "Isovolemic" partial exchange transfusion decreases UV Hct, RCV, and BV and increases PV.

Blood Volume↗