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Biomedical subjects

H M Berger

Publications and source records attributed to H M Berger.

At least 19 recordsLinked to original sources
PubMed1992

Recycling of glutathione during oxidative stress in erythrocytes of the newborn.

The ability of erythrocytes from newborn babies and adults to maintain reduced glutathione levels during oxidative stress was studied. In vitro incubation of erythrocytes with H2O2, with or without inactivation of catalase, caused a rapid depletion of reduced glutathione (GSH) and concomitant accumulation of oxidized glutathione followed by recovery of GSH and fall of oxidized glutathione to initial values in all subjects. Inactivation of catalase resulted in a 50% loss of intracellular glutathione (p less than 0.005), a larger maximum GSH depletion (p less than 0.05), and a longer GSH recovery time (p less than 0.005). Erythrocytes from newborn babies showed a smaller maximum GSH depletion (p less than 0.05) and a shorter GSH recovery time (p less than 0.005) compared with those from adults. These differences between the newborn and adult groups persisted after inactivation of catalase. An increase in maximum GSH depletion and GSH recovery time (p less than 0.005) was observed when a lower hematocrit was used for these GSH recovery studies. Effective glutathione recycling in erythrocytes may protect immature tissues of the newborn baby from peroxidative damage.

Adult↗
PubMed1992

Limited protection against iron-induced lipid peroxidation by cord blood plasma.

The ability of plasma from newborn babies (cord blood) and adults to inhibit iron-induced lipid peroxidation was compared. The caeruloplasmin and transferrin concentrations, and latent iron-binding capacity were lower in the babies (p less than 0.001). The plasma of many of the babies had no latent iron-binding capacity and contained non-protein-bound iron (measured by the bleomycin assay). The in vitro ability of plasma to inhibit iron-induced liposome peroxidation by either ferroxidase antioxidant activity (caeruloplasmin) or iron-binding antioxidant activity (transferrin) was measured. The antioxidant activity in both assays was decreased in the babies (p less than 0.001). The percentage inhibition of peroxidation in the iron-binding antioxidant assay correlated positively with the latent iron-binding capacity (p less than 0.001) and negatively with the presence of bleomycin-detectable iron (p less than 0.02) in the babies. This assay produced stimulation of peroxidation in 42% of the babies but none of the adults. The diminished capacity of cord blood plasma to prevent iron-induced lipid peroxidation may predispose the newborn baby to the toxic effects of oxygen.

Adult↗
PubMed1992

Effect of an exchange transfusion on plasma antioxidants in the newborn.

The effect of an exchange transfusion on antioxidants in the plasma of newborns with rhesus hemolytic disease was studied. The antioxidant concentrations in donor blood were similar to normal adult values except for the lower vitamin C concentrations. Exchange transfusion decreased the newborns' iron and ferritin levels and increased their ceruloplasmin and transferrin (primary antioxidants) concentrations and latent iron-binding capacity. The changes in secondary antioxidant concentrations were variable; uric acid and thiols were stable, vitamin C and bilirubin fell, and vitamin E rose. The total peroxyl-radical trapping capacity of the secondary antioxidants did not change significantly. The fall in levels of thiobarbituric acid reactive substances, an index of lipid peroxidation, was related to the lower levels present in the donor blood. Exchange transfusion rapidly produced variable changes in the concentrations of prooxidant and antioxidant substances in plasma and may thus influence free radical metabolism in the newborn.

Adult↗
PubMed1990

Iron overload, free radical damage, and rhesus haemolytic disease.

To test the hypothesis that iron overload induces free radical damage in rhesus haemolytic disease (RHD), cord blood plasma of babies with RHD was compared with that of controls matched for gestational age. Babies with RHD had higher ferritin levels, lower latent iron-binding capacity, increased concentrations of lipid-peroxidation products, and low vitamin C levels. Plasma of 3 RHD babies did not inhibit peroxidation stress. These findings, of iron overload and free radical damage, have implications for treatment of RHD.

Antioxidants↗
PubMed1989

The effect of a manometer on the mean airway pressure during hand ventilation, an in vitro study.

The effect of an on-line manometer on the variables of ventilation i.e. peak inspiratory pressure (PIP), mean airway pressure (MAP), positive end expiratory pressure (PEEP), and inspiratory to expiratory time ratio (I:E) was studied in vitro. Analysis of PIP, MAP, PEEP, and I:E was made during hand ventilation of a resuscitation mannequin at the preselected PIP of 15 and 25 cm water with and without a manometer. Use of the manometer decreased the range of variation in PIP, but the MAP was higher. This was due to an increased I:E while PEEP remained unchanged. An on-line manometer during hand ventilation prevents excessive PIP but may increase the MAP and therefore may not prevent development of a pneumothorax.

Air Pressure↗
PubMed1989

Neonatal pneumothorax drainage systems: in vitro evaluation.

We studied, in vitro, different commercially available components for pneumothorax drainage, i.e. drainage tubes, Heimlich flutter valve and vacuum control units. The drainage of a pneumothorax by a drainage tube was, as expected, directly dependent on Poiseuille's law and was influenced more by diameter than length. Of practical importance, a size 6 French gauge tube, used for the very small newborn, may not efficiently evacuate a pneumothorax due to a large air leak. The Heimlich flutter valve, though useful clinically, adds to the resistance of the system especially if fluids accumulate in the valve. All vacuum control units, adaptations of the basic three- or four-bottle pleural drainage system, functioned adequately but simple changes in construction may increase the safety of some of these systems.

Drainage↗
PubMed1989

Nonlipid formula components and fat absorption in the low-birth-weight newborn.

The relationship between nonlipid formula components and fat absorption in newborns is largely uninvestigated. Two formulas of identical fat blend but different protein quality and acid-base properties were fed to two groups of babies from birth and during 3-5 d balance periods in the third week of life. Babies receiving a formula of higher acidity containing predominantly curd protein absorbed a significantly lower percentage of their fat and nitrogen intake than babies receiving a curd-and-whey protein formula (fat absorptions of 73 +/- 11.0 and 85 +/- 8.0%, means +/- SD, p less than 0.04; N absorptions of 90 +/- 3.0 and 93 +/- 1.0%, p less than 0.03, respectively). The feces of the curd-formula babies contained a smaller proportion of long-chain, saturated fatty acids and a larger proportion of shorter-chain and unsaturated fatty acids. Fatty acid type and triglyceride structure are not the only factors influencing fat absorption in newborns. Other formula components may need modification to achieve maximum fat absorption.

Bile Acids and Salts↗
PubMed1989

The total free radical trapping ability of cord blood plasma in preterm and term babies.

The interaction between various antioxidants may be important in protecting the newborn baby against oxygen toxicity. We studied the total radical trapping capacity of the antioxidants in plasma (TRAP) and compared the TRAP level in the preterm and term baby (cord blood) with that in adults. In addition, the concentrations of various known antioxidants were measured and the theoretical contribution of these antioxidants to the TRAP calculated. The measured and calculated TRAP were higher in the newborn babies than the adults. The uric acid concentration was similar in the three groups but the vitamin C concentration was higher and the vitamin E and sulfhydryl concentrations were lower in the newborn babies. In contrast to the adult group, the measured TRAP in the newborn babies did not correlate with the calculated TRAP. This may be due to differences in inhibition or recycling of antioxidants in the newborn and adult groups. Theoretical considerations showed that there may be a large unidentified group of antioxidants that contribute to measured TRAP in plasma. Bilirubin and beta-carotene were measured (higher and lower concentrations, respectively, in the newborn) in an attempt to identify these antioxidants. The efficient plasma radical trapping capacity in the cord blood may partly compensate for deficiencies in other components of the antioxidant defenses, e.g. cellular enzymes, at the time of birth.

Aging↗
PubMed1987

Human milk vitamin content after pasteurisation, storage, or tube feeding.

We investigated the effect of the composition of the storage container, Holder pasteurisation, and conditions during tube feeding on the concentration of selected vitamins in human milk. Though the fat soluble vitamins A, D, and E were not affected, the concentration of several water soluble vitamins decreased. The lower vitamin C concentration of milk stored in polypropylene containers compared with milk stored in glass containers (29%) was not significant. Holder pasteurisation significantly lowered the concentrations of vitamins C (36%), folacin (31%), and B6 (15%). Tube feeding significantly lowered the concentrations of vitamins C (44%) and B6 (19%), and exposure to phototherapy seemed to lower the vitamin C concentration (53%) further. Low birthweight infants have increased vitamin requirements. Vitamin losses in expressed human milk before or during feeding may increase the incidence of vitamin deficiencies in these babies.

Enteral Nutrition↗
PubMed1986

Plastic blankets and heat shields decrease transmission of phototherapy light.

An in vitro study showed that the use of transparent plastic insulation to decrease heat loss from newborn infants substantially decreases the transmission of phototherapy light. The decrease is proportional to the number of plastic layers between the light source and the baby because of reflection from the surface of the plastic. This increases if the surface is irregular. Thickness and the type of plastic used had no effect.

Bedding and Linens↗
PubMed1985

Growth velocity and plasma amino acids in the newborn.

Plasma amino acid levels in newborn babies are often measured as part of a screening for inherited metabolic disease, or less commonly as part of a nutritional assessment. We have examined certain factors which affect the levels as measured in low birth weight babies during the first 3 wk of life. As in other studies, plasma amino acid concentrations were shown to fall with increasing gestational and postnatal age, and to reflect to some extent the amino acid composition of the dietary protein. In addition, however, plasma branched-chain amino acids and cystine were found to be inversely related to growth velocity and nitrogen retention. These results could be interpreted to suggest that some low birth weight babies were malnourished. However accompanying anthropometric and clinical data showed that these particular babies were healthy and growing rapidly; they were unlikely to be truly malnourished. Rather we suggest they were experiencing "protein economy" resulting from their high growth rate, and would, therefore, have benefited from increased dietary protein. It seems that growth velocity, as well as maturity and diet, must be considered when interpreting plasma amino acid values in an individual baby. There are two implications for the nutrition of the low birth weight baby. The higher plasma threonine concentrations found in the babies receiving the demineralized whey formula does prompt a word of caution when further increase in the whey:casein ratio is contemplated. At energy intakes around 130 kcal/kg/day, protein may become a limiting nutrient both in terms of quality and quantity.

Amino Acids↗
PubMed1979

Curd and whey proteins in the nutrition of low birthweight babies.

Some animals thrive more satisfactorily on a milk that contains whey and curd protein. For this reason human milk protein (which contains about 40% whey) may have some advantages over cows' milk protein (which contains about 15% whey) and so infants feeding formulae based on demineralised whey in which the protein has been modified to achieve a curd:whey ratio similar to that in human milk may also thrive more satisfactorily. As the exact situation in the human newborn is unclear, the effects of feeding a formula containing unmodified cows' milk protein (mainly curd) and one containing the same amount of modified cows' milk protein (curd and whey) were studied in 57 low birthweight babies during the first 3 months of life. During the early weeks of life the curd and whey group grew bigger, absorbed more nitrogen, and excreted proportionately less urea. These results suggest that a curd and whey formula has advantages in the protein nutrition of low birthweight babies, especially the preterm ones. We feel it would be unwise to reduce the protein content of a formula based on cows' milk below 15 g/1 unless it was modified to achieve a larger proportion of whey protein and hence, among other qualities, more cysteine. Although some of the qualities of human milk protein can be mimicked by the use of demineralised whey formulae, others cannot.

Animals↗