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Biomedical subjects

E F Bell

Publications and source records attributed to E F Bell.

At least 55 records · Page 3Linked to original sources
PubMed1986

Effects of environmental warming on blood components dispensed in syringes for neonatal transfusions.

We examined the quality of blood components dispensed in syringes for transfusion into neonates, including the effects on quality of environmental conditions to which blood is exposed when it is transfused into neonates nursed in warm-air incubators or under radiant warmers. Syringes of blood placed in incubators rapidly warmed to 36 degrees C. Blood placed under radiant warmers operated at full power was heated rapidly to temperatures approaching 45 degrees C, and all blood components exhibited evidence of falling pH and cellular damage after 6 hours exposure to radiant energy. Erythrocyte damage was suggested by an increase in plasma hemoglobin, potassium, and lactic dehydrogenase. Platelets lost the ability to recover from hypotonic shock. Granulocytes exhibited a marked defect in the ability to produce superoxide anion after stimulation. The excessive warming and functional abnormalities exhibited by all blood components exposed to infrared energy were abrogated when syringes were shielded by covering them with aluminum foil. The clinical importance of these experimental findings remains to be established. Meanwhile, it would seem prudent either to shield syringes of blood placed under radiant warmers by covering them with aluminum foil or to limit the volume of a single transfusion to a quantity that can be infused within a relatively brief period.

Blood Transfusion↗
PubMed1986

Effect of sucrose ingestion on plasma glutamate concentrations in humans administered monosodium L-glutamate.

Plasma glutamate concentrations in human subjects are markedly lower when monosodium L-glutamate (MSG) is ingested in consomme with starch than when ingested in consomme alone. This study investigated whether sucrose had a similar effect. Six normal adult subjects (three male, three female) ingested two servings of beef consomme each providing 50 mg MSG/kg body weight in a randomized crossover design. One serving of consomme contained no added carbohydrate; the other provided 0.5 g sucrose/kg body weight. Ingestion of the consomme without sucrose significantly (p less than 0.05) increased the mean plasma glutamate concentration from baseline (4.44 +/- 0.97 mumol/dl) to a peak value of 18.1 +/- 6.99 mumol/dl 30 min after dosing. The area under the plasma glutamate concentration-time curve was 553 +/- 238 mumol/dl X min. When the consomme contained 0.5 g sucrose/kg body weight, both the mean peak plasma glutamate concentration (5.48 +/- 2.19 mumol/dl) and the area under the curve (105 +/- 46 mumol/dl X min) were significantly lower. These data confirm that metabolizable carbohydrate has a significant effect on plasma glutamate concentration response after MSG loading.

Administration, Oral↗
PubMed1986

Effects of equimolar doses of L-methionine, D-methionine and L-methionine-dl-sulfoxide on plasma and urinary amino acid levels in normal adult humans.

Plasma and urinary amino acid levels were measured in four normal adult subject administered equimolar quantities (0.0605 mmol/kg body wt) of L-methionine, D-methionine and L-methionine-dl-sulfoxide in a randomized crossover design. Plasma total methionine concentrations increased significantly (P less than 0.05) over base line (3.7 +/- 1.2 mumol/dl; mean +/- SD) after loading with each compound. Mean peak plasma methionine levels were 9.8 +/- 1.1, 14.4 +/- 2.3 and 5.2 +/- 1.0 mumol/dl after loading with L-methionine, D-methionine and L-methionine sulfoxide, respectively. D-Methionine accounted for the increased plasma levels seen after D-methionine loading. None of the three compounds affected plasma cystine, cysteine or taurine concentrations. Plasma methionine sulfoxide concentrations were not affected by loading with D- or L-methionine but increased significantly after ingestion of L-methionine sulfoxide. Urinary methionine excretion was 20 times higher after ingestion of D-methionine than after ingestion of L-methionine or L-methionine sulfoxide, with the increase due to D-methionine excretion. Urinary excretion of methionine sulfoxide and its N-acetyl derivatives was not significantly higher after loading with methionine sulfoxide. The data indicate that adult humans do not utilize D-methionine efficiently as a methionine source but probably do utilize L-methionine-dl-sulfoxide.

Adult↗
PubMed1986

Plasma glutamate concentrations in 1-year-old infants and adults ingesting monosodium L-glutamate in consommé.

This study tested the hypothesis that infants metabolize glutamate more slowly than adults. Eight 1-yr-old infants ingested 160 ml of a beef consommé providing monosodium L-glutamate at 0, 25, and 50 mg/kg body weight. Plasma glutamate and aspartate concentrations were measured sequentially for the next 2 h. The results were compared to values noted in nine adult subjects ingesting equivalent doses of monosodium L-glutamate in consommé. In adults, mean (+/- SD) peak plasma glutamate concentrations were 5.59 +/- 1.56, 10.2 +/- 2.08, and 17.0 +/- 8.06 mumol/dl, respectively; the area under the plasma glutamate concentration time curves were 96 +/- 42, 257 +/- 80, and 442 +/- 303 mumol/dl X min, respectively. In infants, the mean (+/- SD) peak plasma glutamate concentrations were 6.94 +/- 1.43, 10.6 +/- 2.36, and 12.0 +/- 1.16 mumol/dl, respectively; the plasma glutamate area under the curve values were 47 +/- 28, 191 +/- 85, and 358 +/- 105 mumol/dl X min, respectively. The data indicate that the plasma glutamate concentration response in 1-yr-old infants ingesting MSG at these glutamate doses is no higher than values observed in adult subjects.

Administration, Oral↗
PubMed1986

Estimation of 24-hour energy expenditure from shorter measurement periods in premature infants.

We performed continuous indirect calorimetry for 24 h on nine occasions in small premature infants. Oxygen consumption, carbon dioxide production, respiratory quotient, and energy expenditure were calculated for each 2-h period. The mean energy expenditure during the first 6 h was within 6.5% of the mean for the whole 24-h period in all but one case. The mean error in estimating total daily energy expenditure from 6-h measurements was 0.9%. Because positive and negative errors tend to offset each other, we also calculated the mean absolute error, which was 5.6%. The mean coefficient of variation in energy expenditure among the 2-h periods was 11.0%. The mean coefficients of variation in oxygen consumption, carbon dioxide production, and respiratory quotient were 12.8, 9.9, and 14.1%, respectively. Total daily energy expenditure of small premature infants can be estimated from measurements as short as 6 h with sufficient accuracy for most purposes.

Calorimetry↗
PubMed1985

Energy intake, norepinephrine excretion, and oxygen consumption in low birthweight infants.

Eleven healthy, appropriately grown low birthweight infants, ages 3-15 days and 28-33 weeks gestation, were the subjects of this study. Energy intake, urinary norepinephrine excretion, and metabolic rate as reflected in VO2 were examined concurrently. Energy intakes were recorded. Simultaneous collection of a timed urine for norepinephrine excretion and measurement of VO2 using indirect calorimetry were performed. A servo control device was used to maintain an abdominal skin temperature of 36.5 degrees C. The results demonstrated increases in energy intake, urinary norepinephrine, and VO2 with advancing postnatal age. Simple linear regression analysis revealed significant positive correlations between energy intake and VO2 (p less than 0.003), norepinephrine excretion and VO2 (p less than 0.003), postnatal age and VO2 (p less than 0.01), and postnatal age and energy intake (p less than 0.001). Multiple regression analysis revealed a strong positive correlation between urinary norepinephrine excretion and VO2, and energy intake and VO2. When postnatal age was added to the multiple linear regression analysis as a variable, energy intake was no longer strongly correlated with VO2. This implies postnatal age and energy intake are closely linked in this study, and further studies are needed to better define these relationships.

Birth Weight↗
PubMed1985

Assessment of lipid peroxidation in newborn infants and rabbits by measurements of expired ethane and pentane: influence of parenteral lipid infusion.

Peroxidation of the unsaturated fatty acid constituents of tissue is one proposed mechanism of in vivo oxidant damage. Products of unsaturated fatty acid peroxidation include the volatile hydrocarbons ethane and pentane. These volatile hydrocarbons are eliminated in expired air and reflect in vivo lipid peroxidation. Newborn infants excrete 16 pmol of ethane per kilogram body weight per minute and 15 pmol of pentane per kilogram body weight per minute. This compares with 1.4 pmol of ethane per kilogram body weight per minute and 1.3 pmol of pentane per kilogram body weight per minute in healthy adult men. Infants receiving total parenteral nutrition including intravenous lipid emulsion excrete more than 100 pmol of pentane per kilogram body weight per minute. Newborn rabbits, delivered at term, also excrete more pentane while receiving lipid emulsion infusion. In the newborn rabbit, the amount of pentane exhaled increases linearly with the dose of lipid emulsion. Blood and tissue thiobarbituric acid reactants are also increased in newborn rabbits after administration of lipid emulsion. These results indicate that lipid peroxidation is quantitatively greater in infants than in adult humans and can be significantly increased by parenteral administration of lipid emulsion.

Adult↗
PubMed1984

Tympanic membrane temperature of term and preterm neonates.

Deep body temperatures of 70 term and 24 preterm newborn infants were measured at two sites: deep rectum (5 cm beyond the anus) and tympanic membrane. A significant correlation was found between deep rectal and tympanic membrane temperatures in both term and preterm infants. Mean deep rectal and tympanic membrane temperatures in term infants were 37.01 degrees C and 36.83 degrees C, respectively. Mean deep rectal and tympanic membrane temperatures in preterm infants were both 36.69 degrees C.

Body Temperature↗
PubMed1984

Temperature measurement in term and preterm neonates.

Body temperatures of 99 term and 44 preterm infants were measured at four sites: core (5 cm beyond the anus, with an electronic telethermometer), rectum (2 cm, with a mercury-in-glass thermometer), axilla, and between the skin and mattress. Temperatures measured at the four sites agreed closely in this group of largely normothermic infants. However, five of seven term infants with abnormal core temperature (greater than 1.5 SD below or above the mean) would have been judged to be normothermic by each of the three other measurements. The temperatures in preterm infants were lower and varied less with the site of measurement, indicating a smaller core-surface temperature gradient because of their relative lack of thermal insulation by body fat. Axillary temperature was as reliable as rectal temperature measured in the usual way with a mercury-in-glass thermometer. Measurement of the temperature between the skin and mattress was nearly as accurate as the other more frequently used methods. Ninety percent of temperatures were within 0.1 degree C of their final stabilization readings by 5 minutes for each type of thermometer and measurement site.

Axilla↗
PubMed1984

Fulminant neonatal septicemia due to Hemophilus parainfluenzae.

A woman with premature rupture of membranes and chorioamnionitis gave birth to a 0.73-kg infant at 28 weeks' gestation. The infant died of fulminant septicemia caused by Hemophilus parainfluenzae. This organism should be recognized as a potential cause of chorioamnionitis and neonatal septicemia.

Female↗
PubMed1983

Renal response in low-birth-weight neonates. Results of prolonged intake of two different amounts of fluid and sodium.

Changes in renal function and extracellular fluid volume during the first ten days of life were studied in two groups of low-birth-weight neonates receiving different fluid and sodium intakes from the third to the tenth day. Group 1 neonates received less fluid and sodium and fewer calories than group 2 neonates. Renal function and inulin space were measured before (day 2) and after (day 8) the neonates received the different fluid and sodium managements. Group 2 neonates (on the eight day) had less weight loss, lower plasma sodium and osmolal concentrations, and a similar inulin space per kilogram of body weight as on day 2. Group 1 neonates had more weight loss and a smaller inulin space on day 8 compared with day 2. Low-birth-weight neonates receiving high fluid and sodium loads from days 2 through 8 did not have a contraction of extracellular fluid volume as did those receiving lower fluid and sodium intakes during this period; as a result, the former group had a dilutional decrease in the plasma sodium level and osmolality.

Extracellular Space↗
PubMed1983

Infant incubators and radiant warmers.

Incubators and radiant warmers are used to maintain the body temperature of newborn infants. This is best done so that the energy expended for metabolic heat production is minimized. The heat output of these devices is usually regulated by servocontrol to keep the skin temperature constant at a site on the abdomen where a thermistor probe is attached. In incubators, air temperature can also be controlled as an alternative to skin temperature servocontrol. Increased ambient humidity, heat shields and clothing have been used to decrease the evaporative or nonevaporative heat loss of infants in incubators under certain conditions. Double-walled incubators, by adding a second inner layer of Plexiglas, reduce radiant heat loss. They may also reduce total heat loss, but only if air temperature is controlled rather than skin temperature. The minimal oxygen consumption under a radiant warmer is the same or perhaps slightly higher than it is for the same infant in an incubator. Compared with incubators, the partition of body heat loss is quite different under radiant warmers. Radiant warmers increase convective and evaporative heat loss and insensible water loss but eliminate radiant heat loss or change it to net gain. A heat shield of thin polyethylene film can be used with a radiant warmer to reduce heat loss by convection and evaporation. The major advantage of the radiant warmer is the easy access it provides to critically-ill infants without disturbing the thermal environment. Its major disadvantage is the increase in insensible water loss produced by the radiant warmer. Most infants can be safely and adequately cared for in either incubator or radiant warmer bed.

Body Temperature↗
PubMed1983

Air versus skin temperature servocontrol of infant incubators.

Air temperature servocontrol was compared with skin temperature servocontrol and manual control as methods for regulating the heat output of a single-walled incubator (Air-Shields C-86) (1) when optimally used in the laboratory and (2) when operated by staff nurses in the nursery. The subjects were eight premature infants with birth weights between 1.07 and 1.54 kg. When the three methods were used to produce neutral air and skin temperatures during 2-hour measurement periods in the laboratory, there were no differences in mean air, skin, or rectal temperature, metabolic heat production, or body heat loss. There were also no differences among the three methods in mean air, skin, or rectal temperature when used by the nurses in the nursery for periods of 24 hours. When incubator wall temperature is stable, air temperature servocontrol can be used as effectively as skin temperature servocontrol to operate infant incubators.

Body Temperature Regulation↗
PubMed1983

Effects of a parenteral nutrition regimen containing dicarboxylic amino acids on plasma, erythrocyte, and urinary amino acid concentrations of young infants.

Plasma, erythrocyte, and urinary amino acid concentrations were measured in young infants infused with a solution containing glutamate and aspartate. Eight infants (1.2 to 2.8 kg) were fed parenterally (80 kcal/kg/day) with two regimens containing dextrose (15 g/kg/day), amino acids (2 g/kg/day), and lipid (2 g/kg/day) for successive 3-day periods in a cross-over design. The regimens differed only in the amino acid source. One regimen (I) provided glutamate (1.5 mmol/kg/day) and aspartate (1.0 mmol/kg/day), while the other regimen (II) did not. The mean (+/- SD) plasma glutamate concentration was slightly, but significantly higher (89.9 +/- 28.5 microM) during infusion of regimen I than regimen II (66.5 +/- 19.8 microM), but values did not differ significantly from values observed in normal, orally fed premature infants (107 +/- 36 microM). No significant differences were noted in either plasma or erythrocyte aspartate concentrations, or in erythrocyte glutamate concentration. Since plasma and erythrocyte levels of dicarboxylic amino acids remained within the normal range, the data indicate no hazard to young infants from infusion of dicarboxylic amino acids at this level.

Amino Acids↗
PubMed1983

Performance characteristics of two double-walled infant incubators.

Two double-walled incubators, the Air Shields C-100 and the Ohio IC, were evaluated for performance characteristics. The Ohio incubator heated more rapidly from room temperature to 36 degrees C, but overshot the preset air temperature and produced greater fluctuation in air temperature due to the operation of the servocontrol system at equilibrium. Neither incubator produced excessive air currents, sound levels, or carbon dioxide accumulation.

Air Movements↗
PubMed1983

Effects of intravenously administered safflower oil emulsion on respiratory gas exchange of low-birth-weight infants.

Safflower oil emulsion (Liposyn 10%) was infused intravenously to supplement energy intake in five low-birth-weight infants. Respiratory gas exchange was measured before and after the addition of fat emulsion in doses of 1-2 g of fat/kg/day to an intravenous feeding regimen of dextrose and amino acids. The oxygen consumption and carbon dioxide production rates were greater during fat infusion in all infants, but the mean respiratory quotient was not different. The increase in energy intake provided by the fat emulsion exceeded the increase in energy expenditure, allowing more energy to be stored for growth.

Emulsions↗
PubMed1983

Water requirement of premature newborn infants.

Two groups of studies related to the water requirement of premature infants are reviewed. The first examined the effects of several environmental factors on insensible water loss (IWL) and oxygen consumption of 20 low-birth-weight infants. Incubator air temperature above the neutral zone increased IWL, as did the use of a radiant heat source instead of a conventional incubator. A plastic heat shield slightly reduced IWL of infants in incubators. The second group of studies examined the effects of excess water intake in premature infants. 170 infants were randomly assigned to receive "low" (average estimated requirement for birth weight and age) or "high" (excess) volume water intake. The high-volume group became dehydrated less often but had a greater incidence of patient ductus arteriosus and necrotizing enterocolitis.

Dehydration↗