3-D ultrasound quantification of neonatal cerebral ventricles in different head positions.

We determined the influence of head position on lateral ventricular cerebral volume in low-birth-weight infants by three-dimensional (3-D) ultrasound (US). Thirty-nine neonates were examined prospectively in a controlled and blinded study. We used a freehand 3-D US system to acquire data sets after head positioning for 3 h on left and right side in random order. The borders of the lateral ventricles were marked in stored cross-sections. Volumes were calculated as mean of duplicate measurements. Median volume of lateral cerebral ventricles was 1.03 (quartiles 0.78-1.36) mL. Median left ventricular volume was slightly larger than right one (p = 0.13). Down-side lateral ventricles showed smaller volumes than up-side positioned ventricles (p < 0.01). Freehand 3-D US allows quantification of small volumes as neonatal lateral cerebral ventricles. Head position influences the lateral cerebral ventricle volume in low-birth-weight infants.

3-D sonographic volume measurement of the cerebral ventricular system: in vitro validation.

This in vitro study evaluates the accuracy and observer dependency of a freehand three-dimensional (3-D) ultrasound system for measuring cerebral ventricular volume in infants. A sphere, a cylinder, and three cerebral ventricle phantoms were made of agarose and embedded in an echogenic matrix after measuring true volumes by water displacement. Volumes of the models were calculated by 3-D software after manual contour marking on ultrasound cross-sections. Mean +/- SD sonographic volume was 94.6%+/-7.3% (n = 130) of true volumes. Intraobserver variation (n = 10) was 2.3%-5.3% for complete investigation (scanning and marking), and 1.8%-4.1% for marking alone. Difference of means (n = 10) between two observers was 7.6% to 10.8% for complete investigation, and 0.6% to 1.6% for the marking process. We conclude that 3-D freehand ultrasonography may be useful for examining ventricle dilatation in infancy.

Zinc deficiency in rapidly growing preterm infants.

Symptomatic zinc deficiency was observed in a 24-week gestation, 640 g birthweight infant fed exclusively with maternal breast milk. Our hypothesis was that subclinical Zn deficiency is not uncommon in very low birthweight infants because fortified human milk and preterm formula may contain little Zn. Zinc serum concentrations determined in 26 consecutive very low birthweight infants (gestational age 23-32, median 27 weeks), prior to discharge, at a chronological age of 37-121 (median 72) d, were found between 1.0 and 14.0 (median 6.4) micromol/l, in 14 infants they were below the normal range of 7.6-15.0 micromol/l. Serum alkaline phosphatase and iron intake did not correlate with Zn concentrations. Nutritional supply of Zn and other trace elements by breast milk fortifiers and infant formulas currently used in Germany does not appear to meet the demands of rapidly growing extremely low birthweight infants during the first months of life.

Prenatal diagnosis of cystic fibrosis.

Cystic fibrosis is the most common autosomal recessive genetic disorder in the Caucasian population (1:2000-1:4000) (Warwick, W. J. (1978) Helv. Paediatr. Acta 33, 117-125). This defect is characterized by chronic obstructive pulmonary disease, pancreatic exocrine insufficiency and abnormally high perspiration electrolytes in most patients (Talamo et al. (1985) In: The metabolic basis of inherited diseases, pp. 1887-1917). The elevated electrolyte level provides the most reliable diagnostic test for cystic fibrosis homozygotes. Although prospects for cystic fibrosis patients have improved, genetically homozygous cystic fibrosis is effectively a lethal disease. Because of the seriousness of the disease, many families with one affected child desire a prenatal diagnosis when a second pregnancy occurs. Despite extensive research, the biochemical basis of cystic fibrosis remains unknown. Secondary effects on microvillar enzymes allow second trimester diagnosis (17-18 weeks of gestation (Brock, D. H. J. (1983) Lancet II, 941-943). First trimester prenatal diagnosis for cystic fibrosis became possible with DNA technology. Application of polymorphic marker loci to problems of prenatal diagnosis and carrier-testing is discussed.

Cystic fibrosis: typing 48 German families with linked DNA probes.

Two hundred and thirty five subjects from 48 German cystic fibrosis (CF) families were typed for restriction fragment length polymorphisms (RFLPs) detected by the probes pmet H, pmet D, and pJ 3.11, known to be tightly linked to the CF gene. Gene and haplotype frequencies suggest a linkage disequilibrium with the CF locus. The analysis of the predictive value of this typing in individual CF families indicates that the combined use of these probes provides a powerful diagnostic system both for carrier detection and prenatal diagnosis. In 33 out of 48 families carriers and non-carriers could be identified, and in 26 of these 33 families prenatal diagnosis could discriminate between affected and unaffected offspring.

Artificial surfactant in preterm rabbits with and without respiratory distress syndrome: difference of in vitro and in vivo activities.

Sixty-eight rabbit fetuses of 27 days gestation were tracheotomised, artificially ventilated, and their lung mechanics studied in a body-enclosing plethysmograph. The animals were treated by tracheal instillation of natural surfactant concentrate or large unilamellar vesicles containing dipalmitoylphosphatidylcholine:egg phosphatidylglycerol, 9:1. Both preparations were highly surface active in terms of film adsorption and surface tension-lowering potential. Before treatment, the lung mechanics were analysed to indicate the presence of respiratory distress syndrome (RDS). Controls received 0.15 M saline. Differences were found between the in vitro and in vivo activities of both preparations in some animals. In 30 preterm animals with partial lung maturity and without respiratory distress syndrome, no significant effect could be achieved with either the natural or the artificial surfactant. In 38 animals with severe RDS, the tidal volume and compliance increased markedly within 15 min of substitution of both preparations. Compliance increased to 178% of the initial value in ventilated, control animals, to 391% in animals treated with natural, and to 344% in animals treated with artificial surfactant.

Activation of active Na transport in sheep Purkinje fibres by external K or Rb ions.

The intracellular Na activity (aiNa) of sheep Purkinje fibres bathed in solutions with and without K (Rb) is studied by means of Na sensitive microelectrodes. Perfusion with K (Pb) free media increases aiNa. Upon reapplication of K (Pb) containing solutions aiNa decreases and cell membrane hyperpolarizes transiently. After an initial delay attributed to K (Rb) equilibration in the extracellular space, the decline of aiNa and membrane potential towards their respective resting values is approximately monoexponential and displays the same time constant (tau). The tau values and aiNa in the steady state vary with the extracellular K (Rb) concentration ([K]0, [Rb]0). According to a simple model the activation of the Na pump by external K (Rb) can be estimated from the time constants or the aiNa steady state values at various [K]0 ([Rb]0). Half maximal activation occurs at 1.6-3.7 mM K (Rb). External K and Rb ions are equipotent activators of the Na pump in sheep Purkinje fibres.