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Biomedical subjects

D K Stevenson

Publications and source records attributed to D K Stevenson.

At least 271 records · Page 15Linked to original sources
PubMed1985

Bilirubin production after supplemental oral vitamin E therapy in preterm infants.

The purpose of this investigation was to determine the influence of early vitamin E supplementation on the rate of heme catabolism (bilirubin production) in healthy preterm infants. Bilirubin production was estimated from the concentration of carbon monoxide in "end-tidal" gas. Serum vitamin E, hemoglobin, and bilirubin levels were determined by standard techniques. Thirty infants received supplementation with vitamin E or placebo in a double-blind, randomized fashion. Infants were studied on day 1 of life prior to therapy, and on days 3 and 7 postnatally. Results showed that in both placebo-supplemented and vitamin E-supplemented groups, vitamin E levels were significantly higher on days 3 and 7 compared with day 1. Bilirubin production was not significantly different on day 3 compared with day 1 in either group, but was significantly lower in both groups by day 7 compared with day 1. There were no significant differences in hemoglobin and serum bilirubin levels between the two groups at any point in time. In conclusion, although vitamin E supplementation significantly raises vitamin E levels, placebo-supplemented premature infants also achieve vitamin E sufficiency and a decrease in bilirubin production by day 7 of age.

Bilirubin↗
PubMed1985

Effect of tin protoporphyrin on the excretion rate of carbon monoxide in newborn rats after hematoma formation.

This study evaluated the efficacy of tin protoporphyrin (TP), a competitive inhibitor of heme oxygenase, in suppressing the total body excretion rate of carbon monoxide (CO), an index of total bilirubin formation, in neonatal rats with artificially created hematomas. Wistar rat litters less than 12 h old were each divided into three groups of similar weight and treated as follows: (a) saline control (S); (b) hematoma, 80 microliter blood (H); (c) TP, 65 mumol/kg, and hematoma (TP-H). CO excretion of the H group increased rapidly after hematoma formation, reaching a maximum value of 79 +/- 4 SE microliter/kg/h 25 h later. Treatment with TP did not affect the pattern of CO excretion or its magnitude (78 +/- 2 SE microliter/kg/h, 25 h posthematoma). The S group showed no increase in CO excretion at this time (40 +/- 2 SE microliter/kg/h). At the conclusion of the experiment (45 h posthematoma), the plasma total bilirubin levels were slightly lower in the TP-H rats (1.0 +/- 0.1 SE mg/dl) than in H rats (1.2 +/- 0.1 SE mg/dl). The S rats had a plasma total bilirubin concentration of 0.8 +/- 0.1 SE mg/dl. The hepatic and splenic heme oxygenase activities were decreased by 61% (p less than 0.001) and 48% (p less than 0.05), respectively, in the TP-H rats as compared to the H rats. The S and H rats had similar enzyme activities. The results of this study suggest that though single-dose TP decreased tissue heme oxygenase activity, it did not significantly affect total bilirubin formation.

Animals↗
PubMed1985

Intestinal flora in the second week of life in hospitalized preterm infants fed stored frozen breast milk or a proprietary formula.

Twenty infants fed stored frozen breast milk or a proprietary formula only had both aerobic and anaerobic cultures performed at a chronologic age of 8 to 14 days. Nine out of 10 stools from the infants fed stored frozen breast milk contained Enterobacteriaceae and one stool was sterile. One contained a Pseudomonas species; one contained anaerobic gram-positive rods; one contained anaerobic gram-negative rods; and four contained anaerobic gram-positive cocci. No anaerobes were found in six stools. Six stools had aerobic gram-positive cocci, none of which was hemolytic. Nine out of 10 stools from infants fed a proprietary formula had Enterobacteriaceae. Six stools had anaerobic gram-positive rods, three had anaerobic gram-negative rods, and four had gram-positive cocci. Four stools had no anaerobic bacteria. All 10 stools had nonhemolytic aerobic gram-positive cocci. Enterobacteriaceae were predominant in the stools of the infants fed either stored frozen breast milk or a proprietary formula, and the colony counts of aerobic bacteria were similar in both groups. This pattern of intestinal flora in hospitalized preterm infants in the second week of life is very different from that of normal term infants and may contribute to their increased incidence of systemic and localized infections. The use of stored frozen breast milk for the purpose of suppressing coliform and other potentially pathogenic organisms may not be effective in hospitalized preterm infants who have been treated previously with broad-spectrum, parenteral antibiotics.

Bacteria↗
PubMed1985

Nonimmune hydrops fetalis in association with hemangioma of the umbilical cord.

Nonimmune hydrops fetalis is becoming the predominant form of fetal hydrops due to the declining frequency of Rh isoimmunization. Reported is the preterm delivery of a hydropic twin with umbilical cord and cutaneous hemangiomata. The unusual umbilical angiomatous malformation was associated with marked edema of the cord. This produced an ultrasonographic abnormality detected antenatally as a multicystic mass in close approximation to the fetal abdomen. The hydropic twin responded to aggressive neonatal management. It appears that hemangiomata of the umbilical cord may be causally related to fetal hydrops and may represent another entry in the differential diagnosis of this disorder.

Adult↗
PubMed1984

Oxytocin and neonatal hyperbilirubinemia. Studies of bilirubin production.

We studied the effect of oxytocin induction or augmentation of labor on rates of bilirubin production in newborns at three different institutions. Bilirubin production, assessed quantitatively by the pulmonary excretion rate of carbon monoxide or qualitatively by the blood carboxyhemoglobin concentration, was not elevated when compared with appropriately matched control groups. Previous studies have implicated administration of large volumes of electrolyte-free dextrose solutions together with oxytocin as an important factor contributing to hemolysis in the infant. The mothers in our studies received minimal amounts of free water. We conclude that oxytocin induction or augmentation of labor does not result in neonatal hemolysis and subsequent hyperbilirubinemia when it is administered without large volumes of sodium-free intravenous solutions.

Bilirubin↗
PubMed1984

Pulmonary excretion of carbon monoxide in the human infant as an index of bilirubin production. IIc. Evidence for the possible association of cord blood erythropoietin levels and postnatal bilirubin production in infants of mothers with abnormalities of gestational glucose metabolism.

A total of 20 infants who had levels of erythropoietin (Ep), the major hormone regulating erythropoiesis, measured in their cord blood also had determinations of the pulmonary excretion rate of CO (VECO) performed, as an index of total bilirubin production. They were either infants of normal mothers or those of mothers with diabetes, gestational diabetes, and missed abnormalities of gestational glucose metabolism. The mean VECO (13.0 +/- 3.5 mu 1/kg/hr) and the mean Ep (20.0 +/- 9.7 SD mU/ml) of the infants with normal mothers (n = 9) were not different from the means previously established by our laboratories (13.9 +/- 3.5 SD mu 1/kg/hr, n = 20; and 23.7 +/- 12.8 SD mU/ml, n = 30, respectively); they were significantly lower than those of the infants of the abnormal mothers in this study. The 5 infants who had a cord blood Ep level greater than 50 mU/ml had a higher mean VECO, 27.8 +/- 7.1 mu 1/kg/hr, compared with 17.2 +/- 4.9 SD mu 1/kg/hr, of the six infants with cord blood Ep levels that were within 2 SD of the previously established normal mean cord blood Ep level (p less than .025). These data suggest that increased cord blood Ep levels and postnatal bilirubin production in infants whose mothers had abnormalities of gestational glucose metabolism are associated phenomena. Since polycythemia did not occur in these infants, ineffective erythropoiesis or mild, compensated hemolysis remains a likely cause of the increased total bilirubin production. In some cases, perinatal hypoxic stress may have affected the Ep response.(ABSTRACT TRUNCATED AT 250 WORDS)

Bilirubin↗
PubMed1984

Hydrogen gas excretion after sucrose gavage in the fasted rat.

The effect of a 3-day fast on the functional ability of the adult rat to hydrolyze and absorb sucrose was determined. The evaluation was based on previous studies which have shown the total amount of hydrogen gas (H2) excreted by the animal to reflect the extent of undigested carbohydrate entering the colon from the small intestine. H2 excretion was measured using a gas chromatographic technique in experimental (72 h fasted) and control (12 h fasted) animals after administration of sucrose by gastric gavage. Total H2 excretion was 3-fold higher in the experimental animals (n = 5) than in the controls (n = 5) (p less than 0.005) indicating a significant increase of sucrose malabsorption in the experimental animals. Administration of a second dose of sucrose 8 to 9 h after the first dose (refeeding) resulted in markedly decreased malabsorption relative to the first administration in both experimental (n = 2) and control (n = 2) animals. These results suggest that a 3-day fast markedly impairs the ability of the intestine to hydrolyze and absorb sucrose and that refeeding rapidly restores the ability to utilize this substrate. H2 excretion was similar between experimental and control animals after the administration of lactulose, a nonabsorbed and nondigested carbohydrate, suggesting that the observed results of the sucrose studies were independent of any possible changes in the intestinal microflora.

Animals↗
PubMed1984

Neonatal bilirubin production estimated from "end-tidal" carbon monoxide concentration.

The relationship between the pulmonary excretion rate of carbon monoxide (VECO) and the concentration of CO, in a sample of breath, drawn through a nasopharyngeal catheter at end-expiration, was assessed in 25 studies of nine preterm and 14 term infants. The VECO and this approximate end-tidal sample of CO (ETCO) correlated significantly over a wide range of CO elimination rates: VECO = 10.45 ETCO + 2.25 (n = 25, r = 0.95). The ETCO correctly predicted elevations in VECO greater than 2 SD of the mean VECO for normal infants (13.9 +/- 3.5 microliter/kg/h), with 90% sensitivity and 73% specificity (p less than 0.01). Three subjects with Rh isoimmune hemolytic disease were easily identified by the ETCO as well as the VECO. The ETCO is a simple, noninvasive measurement for rapidly identifying infants with significant hemolytic disease.

Bilirubin↗
PubMed1984

The bacterial content of breast milk after the early initiation of expression using a standard technique.

This study was initiated to evaluate the effect of early expression on the bacterial colony count of human milk. Significant bacterial contamination (greater than or equal to 10,000 colony-forming units/ml milk) was more common in 11 mothers who delayed the onset of expression of their milk compared with mothers who began to express their milk in the immediate postpartum period (n = 15) or who began to nurse their own full-term infants soon after delivery (n = 9). These data suggest that mothers who are separated from their prematurely born or sick infants should begin to express milk for their own infants as soon after birth as possible to provide milk with low bacterial contamination for frozen storage and later use.

Bacteria↗
PubMed1984

Pulmonary excretion rate of carbon monoxide as an index of total bilirubin formation in adult male Wistar rats with common bile duct ligation.

Total bilirubin formation (TBF) in the rat after a short period of common bile duct ligation was studied by measuring the pulmonary excretion rate of CO (VECO). At postoperative day 3, the VECO of experimental animals was higher when compared with the preoperative VECO (p less than 0.005); whereas the VECO of control animals did not change. Also, on the 3rd postoperative day, the relative rate of early labeling of bilirubin following the administration of delta-aminolevulinic acid-5-14C, a preferential hepatic heme synthesis precursor, was similar between the experimental and control animals; only the experimental animals had an abnormal peroxide hemolysis test. We conclude that common bile duct ligation in the rat is associated with elevations in the VECO, indicating significant increases in TBF, and the source of the increase is probably of erythropoietic origin. This finding may be relevant to the understanding of the pathophysiology of obstructive jaundice in human neonates.

Animals↗
PubMed1984

The role of bilirubin production in breast-fed infants with elevated serum bilirubin concentrations at 2 weeks of life.

The carboxyhemoglobin level (COHb), an accepted qualitative index of bilirubin production, was measured in normal, full-term, breast-fed (n = 9) or formula-fed (n = 11) infants at 2 days and 2 weeks of life. The mean COHb did not differ significantly at 2 days and 2 weeks in either of the groups, nor did the mean COHb differ between the groups at 2 weeks. The mean serum bilirubin concentration was lower in the formula-fed infants compared to the breast-fed infants at 2 weeks (p less than 0.05). The mean serum bilirubin concentration decreased by only 14 percent among the breast-fed infants, and actually increased in three infants by 2 weeks. In comparison, the mean serum bilirubin concentration of the formula-fed infants decreased by 61 percent (p less than 0.05), with the serum bilirubin concentration decreasing in each infant by 2 weeks. These findings are consistent with the generally held belief that bilirubin production is not the primary etiology of elevated serum bilirubin concentrations associated with breast-feeding in the second week of life. However, continued high bilirubin production at 2 weeks may contribute to the potential for significant jaundice in some infants with impaired hepatic function or increased enterohepatic circulation of bilirubin.

Bilirubin↗
PubMed1984

Carbon monoxide in blood: an improved microliter blood-sample collection system, with rapid analysis by gas chromatography.

We examined the sensitive assay for carboxyhemoglobin based on reaction with K3Fe(CN)6 and gas chromatography of the liberated CO. Our improvements included increased baseline stability, shorter analysis time, and simpler standardization. EDTA-containing Vacutainer Tubes (lavender-stoppered) increase the carboxyhemoglobin content of blood stored in them. The carboxyhemoglobin content of blood stored in capillary tubes containing solid heparin and saponin remained stable for two weeks. Using our improved procedures, we measured the carboxyhemoglobin content of blood from adults and neonates collected via venipuncture or heel or fingersticks. We observed no significant difference in carboxyhemoglobin content of blood obtained by venipuncture or heel stick for premature infants, 0.19 +/- 0.04 vs 0.18 +/- 0.03 mL of CO per 100 mL of blood, respectively (mean +/- SD). Nonsmoking adults (n = 19) had CO values (mean +/- SD) of 0.19 +/- 0.03 and 0.17 +/- 0.04 mL per 100 mL of blood, and smoking adults (n = 7) gave CO values of 0.96 +/- 0.49 and 0.91 +/- 0.49 mL/dL, for venipuncture and fingerstick, respectively.

Adult↗
PubMed1983

Tuberculosis in unvaccinated children, adolescents, and young adults: a city epidemic.

In an epidemic of tuberculosis 41 new patients presented with the disease or were traced. The index patient was a part time barman in a public house. Four children in his family and four who lived in the same block of flats were infected. Only seven of the 41 patients had been vaccinated with BCG. This epidemic indicates that the schools vaccination programme should be continued and the public made aware that tuberculosis still exists.

Adolescent↗
PubMed1983

Maternal beta-adrenergic tocolysis and neonatal bilirubin production.

The potential for beta-adrenergic drugs to increase total bilirubin formation via cyclic adenosine monophosphate-mediated stimulation of hepatic microsomal heme oxygenase in the human neonate was evaluated. The pulmonary excretion rate of endogenously produced carbon monoxide (VeCO), an index of total bilirubin formation (TBF), was measured in 18 preterm neonates whose mothers received beta-adrenergic drugs for tocolysis and in 18 preterm neonates whose mothers were untreated. The mean VeCO of the neonates in the former group (17.2 +/- 7.3 microL/kg/hr) was the same as that in the latter group (17.4 +/- 6.2 microL/kg/hr); both values were elevated when compared with the mean VeCO of 20 term newborns (13.9 +/- 3.5 microL/kg/hr). Our findings indicate that TBF is not significantly increased in neonates whose mothers received beta-adrenergic drugs before delivery.

Adrenergic beta-Agonists↗