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Biomedical subjects

H N Lafeber

Publications and source records attributed to H N Lafeber.

At least 55 records · Page 3Linked to original sources
PubMed1990

Glucose production and oxidation in preterm infants during total parenteral nutrition.

During total parenteral nutrition in preterm infants, glucose may be infused at high rates, but it is not known if the endogenous glucose production is fully suppressed under these circumstances. Eight preterm appropriate for gestational age (AGA) (birth wt: 1613 +/- 151 g, gestational age: 31.1 +/- 1.5 wk) and eight preterm small for gestational age (SGA) newborn infants (1185 +/- 241 g, 32.9 +/- 2.6 wk) receiving a glucose infusion rate of 7.55 +/- 0.56 and 8.16 +/- 0.65 mg/kg.min, respectively, were studied during continuous total parenteral nutrition at postnatal d 8. Glucose oxidation rate was determined with a primed constant infusion of [U-13C] glucose, measuring the 13CO2 production in breath gas by isotope ratio mass spectrometry and the glucose production rate in plasma by gas chromatography mass spectrometry. In breath gas of AGA and SGA infants, 60 and 65%, respectively, of the infused tracer appeared as 13CO2. The glucose production rates were 7.97 +/- 1.61 and 8.12 +/- 1.84 mg/kg.min in AGA and SGA infants, respectively, indicating that no significant endogenous glucose production occurred. The glucose oxidation calculated from the glucose production and 13CO2 production was 4.74 +/- 0.99 mg/kg.min in AGA infants and was significantly different from the carbohydrate oxidation rate of 6.62 +/- 1.23 mg/kg.min measured by simultaneous indirect calorimetry. In SGA infants, however, the glucose and carbohydrate oxidation rates were not significantly different at 5.33 +/- 1.56 and 6.16 +/- 2.45 mg/kg.min. It is concluded that 1-wk-old AGA or SGA preterm infants receiving total parenteral nutrition of 80 kcal/kg.d produce no endogenous glucose and their glucose oxidation rates are similar at 63-65% of the glucose infused. It is suggested that the significant difference between glucose and carbohydrate oxidation rates observed in AGA but not in SGA infants is due either to a higher rate of lipogenesis from carbohydrates, or, less likely, to a higher rate of glycogen oxidation.

Calorimetry↗
PubMed1990

[Bronchopulmonary dysplasia].

Bronchopulmonary dysplasia (BPD) is a serious lung disease which is increasingly recognised in prematurely born infants in neonatal intensive care units. Little is known about the cause of the disease, the treatment is mainly empirical. Although oxygen is well known to be one of the causal agents for BPD, it is, at the same time, part of its treatment. The neurodevelopmental outcome of infants with BPD is likely to be disturbed, while the lasting treatment often causes problems in the family. Because of the tendency to treat premature infants born after still younger pregnancies, neonatologists are facing a growing number of patients with BPD. In this article the presentation, pathogenesis, diagnostical approach, therapy and the course as well as the follow-up of our patients is discussed.

Bronchopulmonary Dysplasia↗
PubMed1990

Studies on the growth of the fetal guinea pig. The effects of nutritional manipulation on prenatal growth and plasma somatomedin activity and insulin-like growth factor concentrations.

In guinea pigs between days 41-46 of pregnancy prenatal growth has been manipulated by alteration of nutritional state. Three methods were used. Uterine artery ligation at day 30 of pregnancy depressed fetal growth rate by greater than 50% and was associated with falls in plasma insulin, IGF-1, cortisol, thyroid hormone, glucose, acetate and free fatty acid concentrations and rises in that of IGF-2, glucagon and amino acids. Fetal plasma was inhibitory to sulphate incorporation into pig costal cartilage. Complete food withdrawal from pregnant guinea pigs for 2 days at days 43-44 of pregnancy caused mild fetal growth retardation and similar changes in plasma constituents, except in that plasma IGF-2 concentrations were now depressed and plasma was not inhibitory to sulphate incorporation into pig costal cartilage. Production of hypoglycaemia by 4-times-daily maternal injections of glucose between days 41-46 of pregnancy accelerated fetal growth rate. It also elevated fetal plasma concentrations of insulin, IGF-1, IGF-2, sulphation-promoting activity, thyroid hormones, glucose and free fatty acids and depressed that of glucagon and amino acids. Fetal growth rate during the experimental period showed a good correlation with plasma glucose, insulin and IGF-1 and, to a certain extent, with sulphation-promoting activity. It did not correlate closely with fetal plasma IGF-2 concentration. Hepatic glycogen concentrations showed a good correlation with plasma IGF-2 levels.

Amino Acids↗
PubMed1989

Comparison of ketoconazole suspension and nystatin in the treatment of newborns and infants with oral candidosis.

Ketoconazole suspension (20 mg per ml) was compared with nystatin (100,000 units per ml) in the treatment of oral candidosis in newborns and infants. In all patients Candida infection was proven by culture. Twenty patients were treated with ketoconazole and 15 patients with nystatin. Treatment was discontinued 2 days after clinical cure, or after 3 weeks. The investigator assessed the severity of the thrush and accompanying symptoms at the start of the study and at weekly controls. After one week all 20 patients on ketoconazole (100%) and 8 (53%) patients on nystatin were cured clinically. At the end of the treatment 12 patients on nystatin (80%) were cured. Clinical cure was confirmed by negative culture in 94% of the patients on ketoconazole and in 73% of the patients on nystatin. No side-effects were observed in the patients on ketoconazole. Only in the case of one patient on nystatin, was vomiting observed. This study shows that ketoconazole cures thrush faster and more effectively than nystatin.

Candidiasis, Oral↗
PubMed1989

Quantitation of oxidation of medium-chain triglycerides in preterm infants.

Medium-chain triglycerides, with a chain length of eight and 10 carbon atoms, form up to 50% of the total fat content in some preterm infant formulas. In 20 small preterm infants (birthwt: 1153 +/- 227 g; mean +/- SD) fed a special formula containing 40% MCT, a primed constant oral infusion study of 1-13C-potassium octanoate was conducted to quantify the oxidation of MCT. A plateau in 13C enrichment in breath CO2 was reached in all patients within 1-3 h. Simultaneously, substrate utilization was measured using a closed system indirect calorimeter. No significant difference was found between appropriate for gestational age (n = 8) and small for gestational age (n = 12) infants in the percentage of the administered tracer that was oxidized (44.9 +/- 9.1% versus 48.5 +/- 11.0%). In all patients, the recovery was calculated to be 47.1 +/- 10.2%, which is less than previously estimated and corresponds to a mean MCT oxidation of 1.26 +/- 0.27 g/kg/d. With indirect calorimetry, a total fat oxidation of 1.42 +/- 0.84 g/kg/d in appropriate for gestational age and 2.00 +/- 0.85 g/kg/d in small for gestational age infants was found, indicating that MCT accounted for around 85% of the total fat oxidation in appropriate for gestational age versus 65% in small for gestational age infants.

Breath Tests↗
PubMed1987

Pulse oximetry and transcutaneous oxygen tension in hypoxemic neonates and infants with bronchopulmonary dysplasia.

The reliability of pulse oximetry and transcutaneous oxygen tension (tcPO2) was investigated in hypoxemic neonates and older infants with chronic hypoxemia due to bronchopulmonary dysplasia (BPD). It was found that during severe hypoxemia (tcPO2 less than 40 mmHg and saturation less than 80%) pulse oximetry showed a better correlation with arterial saturation than tcPO2 with arterial oxygen tension. During mild hypoxemia and normoxemia (tcPO2 40-90 mmHg and saturation 80-95%) tcPO2 and pulse oximetry both showed a good correlation with arterial values. Above 95% saturation and a corresponding tcPO2 of 70-120 mmHg, the correlation between arterial and transcutaneous PO2 was better than that between pulse oximetric and arterial saturation. Computer recording and analysis of tcPO2 and pulse oximetry improves the quality of both noninvasive oxygenation parameters in older infants with BPD.

Birth Weight↗
PubMed1987

Multichannel recording and analysis of physiological data using a personal computer.

A flexible data acquisition system was designed for an Apple IIe computer. For implementation, we used a microcomputer capable of recording 4 channels simultaneously with a selectable sample rate; this information was saved on a floppy disc and the recordings could be evaluated later. This evaluation is accomplished by reproducing the analog signals on display and calculating a histogram after deleting artefacts in the signal.

Blood Gas Monitoring, Transcutaneous↗
PubMed1987

Studies on the growth of the fetal guinea pig. Changes in the plasma concentration of sulphation-promoting activity and of insulin-like growth factors during gestation.

Plasma sulphation-promoting activity, insulin-like growth factors (IGF)-I and -II and insulin concentrations have been measured in the developing guinea. Sulphation-promoting activity fell progressively from midgestation to term in a manner that correlated fairly closely with the decline in the fractional rate of body and liver growth. The changes in plasma concentrations of IGF-I, & -II were quite different, both being substantially higher than fetal plasma insulin concentration. IGF-I, like insulin, plasma concentration rose between 35 and 50 days, then declined as term approached. These changes correlated with phases of lipid, DNA and RNA synthesis, but not of glycogen synthesis in the fetal liver. Fetal Plasma IGF-II concentration was comparatively low until about 55 days gestation then rose sharply, at the time that large quantities of glycogen are deposited in the fetal liver and myelation is initiated in the fetal brain, to achieve very high levels by 60-63 days then declining as term approaches. Plasma IGF-I and -II, measured by radioimmunoassay and radioreceptor assay respectively, showed the same cross-reactivity or binding characteristics as peptides in human or rat plasma. On separation by hplc IGF-I consisted of two major fractions and IGF-II of one. This picture was the same if the peptides were from fetal or adult plasma. There was no evidence of a distinctly fetal class of IGF. Plasma IGF-I and -II concentrations did not correlate with changes in fetal size or fractional rate of growth.

Animals↗
PubMed1987

Studies on the growth of the fetal guinea pig. Effects of reduction in uterine blood flow on the plasma sulphation-promoting activity and on the concentration of insulin-like growth factors-I and -II.

The effects of prenatal growth restriction caused by uterine artery ligation at midgestation has been studied in pregnant guinea pigs. Ligation of a uterine artery at day 30 of pregnancy commonly caused a reduction in fetal growth of greater than 45% by days 40-65 of gestation. This was associated with substantial delays in the development of a number of fetal tissues and in particular that of the skeleton which remained cartilagenous for longer than normal. Hence normally by day 50 of pregnancy clear evidence of epiphyseal ossification in the long bones of the fore- and hindlimbs was present, but in growth retarded fetuses of less than 50% of normal size such evidence was sparce. Delayed skeletal development and the slowing of fetal growth rate correlated well with marked depression of plasma sulphation-promoting activity. Indeed plasma from fetuses that were less than 40% of normal size inhibited sulphate incorporation into pig costal cartilage. This indicated the presence of inhibitory factors in the plasma of such fetuses, an interpretation that was re-inforced by the observation that plasma IGF-II concentrations were 2-4 times above normal. In contrast plasma IGF-I concentration was depressed upto 50% by growth retardation in line with the fall in fetal plasma insulin concentration. The changes in plasma sulphation-promoting activity and of IGF-I are consistent with slowing of DNA, RNA and protein synthesis and of gene expression in tissues of the growth-retarded fetus. The elevated fetal plasma IGF-II concentration provided further evidence that in the fetal guinea pig this hormone has a potentially glyconeogenic action and maintains essential glycogen stores.

Animals↗
PubMed1984

Studies on the growth of the fetal guinea pig. Changes in plasma hormone concentration during normal and abnormal growth.

The endocrine changes associated with fetal growth retardation caused by unilateral uterine artery ligation of guinea pigs at day 30 of pregnancy were studied. Plasma hormone levels in fetuses that, about 20 or 30 days later, were 35-50% of normal size were measured by radioimmunoassay. The small fetuses were severely hypoglycaemic and hypoinsulinaemic; both showing close correlation and relationship to the degree of growth retardation. Plasma thyroid and cortisol and concentrations were much lower than normal and that glucagon and androstenedione were much higher. Plasma growth hormone level appeared to be unaffected by growth retardation. The developmental changes in glucagon and thyroid hormone concentrations were consistent with a delay in the timing of prenatal events in growth-retarded fetuses. However the late cortisol rise, although somewhat blunted, still occurred at 58-60 in the small fetal guinea pigs.

Adrenocorticotropic Hormone↗
PubMed1984

Studies on the growth of the fetal guinea pig. The effects of ligation of the uterine artery on organ growth and development.

The effects of reduced maternal placental blood flow on the growth and development of the fetal guinea pig have been studied by unilateral ligation of the uterine artery at day 30 of pregnancy. Fetal guinea pigs were investigated about 20 or 30 days later. In about one-third of cases fetal death occurred, in another third fetuses less than 60% of normal weight were observed and in the remainder all fetuses were in the normal weight range. In the growth retarded fetuses prenatal growth occurred at about 50% of the rate in control. There was no postnatal 'catch up' as growth still remained lower than in controls. Restricted fetal growth affected particularly development of the visceral tissues in which case size declined in proportion to body weight. Brain and adrenal by comparison were less affected as their contribution to total body weight increased, but even so in the severely retarded fetuses the mass of both fell. The responses of the liver were in general consistent with a delay in the pattern of development. Thus DNA, RNA, protein and haematopoietic cell content changes occurred later than normal. In contrast an enhanced deposition of glycogen was apparent in the liver of the growth-retarded fetus. The results indicate some of the ways in which nutritional deprivation of the fetuses leads to reprogramming of growth and maturation of selected fetal tissues to allow non-essential changes to await more favourable times.

Animals↗
PubMedDate not supplied

Calculated mean arterial blood pressure in critically ill neonates.

Mean arterial pressure (MAP) is the area under the pressure wave form averaged over the cardiac cycle. A widely used rule of thumb to estimate MAP of peripheral arterial pressure waves in adults is adding one-third of the pulse pressure (PP) to diastolic arterial pressure (DAP). However, radial artery pressure waves in newborns differ from those in adults and resemble proximal aortic pressure waves, so that the above-mentioned calculation of MAP may not be correct. The present study was set up to obtain an arithmetical approximation to derive MAP from blood pressure waves measured in the radial artery of the neonate. We accurately recorded about 300 invasively obtained blood pressure curves in the radial artery of 10 neonates admitted for intensive care. We found that MAP in the radial artery in these neonates can be well approximated by adding 46.6% PP to DAP (range 43.0-50.1%). We suggest that the rule of thumb to derive MAP from radial artery waves in the neonate to be approximately the average of systolic and diastolic pressure, as opposed to adding one-third of the pulse pressure to the diastolic value in the adult.

Blood Pressure↗