Ultrasound for the assessment of bone quality in preterm and term infants.

OBJECTIVE: As 80% of intrauterine bone mineralization takes place during the last trimester of pregnancy, preterm infants should be supplemented postnatally with optimal doses of calcium, phosphate and vitamin D. Calcium and phosphate excretion in the urine may be used to monitor individual mineral requirements, but are sometimes difficult to interpret. The objective of this study was to assess the value of quantitative ultrasound (QUS) for the analysis of bone status in neonates. STUDY DESIGN: All admissions to three independent tertiary neonatal intensive care units were studied. In 172 preterm and term infants with a gestational age between 23 and 42 weeks (mean 33.8±5.0) and a birth weight from 405 to 5130 g (mean 2132±1091 g) bone status was evaluated prospectively by quantitative ultrasound velocity using a standardized protocol. Infants were followed in regular intervals up to their first discharge home. While measurements were conducted in weekly intervals initially (n=55), 2-week intervals were regarded as sufficient thereafter due to limited changes in QUS values within the shorter period. Infants with a birth weight below 1500 g were followed during outpatient visits until up to 17 months of age. RESULT: The intra-individual day-to-day reproducibility was 0.62%. QUS-values from the first week of life correlated significantly with gestational age and birth weight (r=0.5 and r=0.6; P<0.001). Small-for-gestational-age infants showed lower values for QUS than appropriate-for-gestational-age infants allowing for their gestational age. Follow-up measurements correlated positively with age and weight during the week of measurement (r=0.2 and r=0.4; P=0.001). Comparing bone quality at 40 weeks of age in infants born at term versus infants born at 24 to 28 weeks, preterm infants showed significantly lower QUS than term infants (P<.0001).There was a significant correlation of QUS with serum alkaline phosphatase (P=0.003), the supplementation with calcium, phosphate and vitamin D (P< 0.001 each), as well as risk factors for a reduced bone mineralization. No correlation was found between QUS and calcium or phosphate concentration in serum or urine. CONCLUSION: QUS is a highly reproducible, easily applicable and radiation-free technique that can be used to monitor bone quality in individual newborns. Further prospective randomized-trials are necessary to evaluate, if therapeutic interventions based on QUS are able to prevent osteopenia of prematurity.

Exportin 4: a mediator of a novel nuclear export pathway in higher eukaryotes.

Transport receptors of the importin beta superfamily account for many of the nuclear import and export events in eukaryotic cells. They mediate translocation through nuclear pore complexes, shuttle between nucleus and cytoplasm and co-operate with the RanGTPase system to regulate their interactions with cargo molecules in a compartment-specific manner. We used affinity chromatography on immobilized RanGTP to isolate further candidate nuclear transport receptors and thereby identified exportin 4 as the most distant member of the importin beta family so far. Exportin 4 appears to be conserved amongst higher eukaryotes, but lacks obvious orthologues in yeast. It mediates nuclear export of eIF-5A (eukaryotic translation initiation factor 5A) and possibly that of other cargoes. The export signal in eIF-5A appears to be complex and to involve the hypusine modification that is unique to eIF-5A. We discuss possible cellular roles for nuclear export of eIF-5A.

Randomized comparison of high-frequency ventilation with high-rate intermittent positive pressure ventilation in preterm infants with respiratory failure.

OBJECTIVE: In a randomized, controlled, multicenter trial, we tested the hypothesis that high-frequency ventilation (HFV) with a high lung volume strategy results in fewer treatment failures than intermittent positive pressure ventilation (IPPV) with high rates and low peak inspiratory pressures. STUDY DESIGN: Infants with a gestational age between >/=24 weeks and <30 weeks, requiring mechanical ventilation within 6 hours of birth, were randomly assigned to receive either IPPV or HFV until 240 hours after randomization, extubation, or meeting treatment failure criteria. Treatment failure, the primary end point, was determined when air leaks, an oxygenation index >35 to 45 (depending on gestational age), death, or chronic lung disease occurred. Chronic lung disease was defined as persistent requirement of mechanical ventilation, continuous positive airway pressure, or supplemental oxygen at a postmenstrual age of 36 weeks. Secondary end points included the incidence of intracranial hemorrhage. RESULTS: The third scheduled interim analysis led to termination of the trial after recruitment of 284 infants. Treatment failure criteria were met by 46% of infants receiving IPPV and 54% of infants receiving HFV (1-tailed primary hypothesis, P =.92; 2-tailed chi2 test, P =.15). Air leaks occurred in 31% and 42% (P =.042), CLD in 23% and 25%, and grade 3-4 intracranial hemorrhage in 13% and 14% of IPPV-treated and HFV-treated patients, respectively. The mortality rate before discharge was 10% in both groups. CONCLUSION: HFV with a high lung volume strategy did not cause less lung injury in preterm infants than IPPV with a high rate and low peak inspiratory pressures.

Coordination of tRNA nuclear export with processing of tRNA.

Eukaryotic tRNAs are synthesized in the nucleus and need to be exported to the cytoplasm where they function in translation. tRNA export is mediated by exportin-t, which binds tRNA directly and with high affinity. tRNAs are initially synthesized as precursor molecules. Maturation to functional tRNA takes place in the nucleus, precedes export, and includes trimming of the 5' and 3' ends, posttranscriptional addition of the 3' CCA end, nucleoside modifications, and in some cases splicing. Here we address the question of how tRNA maturation is coordinated with export and thus how cytoplasmic accumulation of inactive maturation intermediates is avoided. This could, in principle, be achieved by nuclear retention of immature tRNA or by selective export of the fully mature form. We show that exportin-t has a strong preference for tRNA with correctly processed 5' and 3' ends and nucleoside modification. tRNA recognition by exportin-t can thus be considered as a quality control mechanism for these maturation steps prior to tRNA export. Surprisingly however, exportin-t can efficiently bind unspliced tRNA and intron-containing tRNA is exported when the rate of splicing is slow. During characterization of the exportin-t/tRNA interaction we found that exportin-t recognizes features in the tRNA that are conserved between prokaryotic and eukaryotic tRNAs. Our data suggest that correct tRNA shape, the 5' and 3' terminal ends, and the TpsiC loop are critical for exportin-t binding.

NTF2 mediates nuclear import of Ran.

Importin beta family transport receptors shuttle between the nucleus and the cytoplasm and mediate transport of macromolecules through nuclear pore complexes (NPCs). The interactions between these receptors and their cargoes are regulated by binding RanGTP; all receptors probably exit the nucleus complexed with RanGTP, and so should deplete RanGTP continuously from the nucleus. We describe here the development of an in vitro system to study how nuclear Ran is replenished. Nuclear import of Ran does not rely on simple diffusion as Ran's small size would permit, but instead is stimulated by soluble transport factors. This facilitated import is specific for cytoplasmic RanGDP and employs nuclear transport factor 2 (NTF2) as the actual carrier. NTF2 binds RanGDP initially to NPCs and probably also mediates translocation of the NTF2-RanGDP complex to the nuclear side of the NPCs. A direct NTF2-RanGDP interaction is crucial for this process, since point mutations that disturb the RanGDP-NTF2 interaction also interfere with Ran import. The subsequent nuclear accumulation of Ran also requires GTP, but not GTP hydrolysis. The release of Ran from NTF2 into the nucleus, and thus the directionality of Ran import, probably involves nucleotide exchange to generate RanGTP, for which NTF2 has no detectable affinity, followed by binding of the RanGTP to an importin beta family transport receptor.

Interleukin-1 receptor antagonist and interleukin-6 for early diagnosis of neonatal sepsis 2 days before clinical manifestation.

BACKGROUND: Neonatal sepsis is a common and life-threatening disorder, particularly among preterm infants. Early initiation of antibiotic therapy is frequently delayed because the first clinical signs of sepsis are non-specific and there are no reliable early laboratory indicators. We investigated the time course of expression and the prognostic power of the early inflammatory mediators interleukin-1 receptor antagonist (IL-1ra), interleukin-6 (IL-6), and circulating intercellular adhesion molecule-1 (cICAM-1) before clinical diagnosis of sepsis. METHODS: In a prospective multicentre study, we monitored 182 very-low-birthweight infants in six intensive-care units for occurrence of sepsis. During routine or clinically indicated blood sampling, an additional sample was collected for measurement of IL-1ra, IL-6, cICAM-1, and C-reactive protein (CRP). Infants were grouped into those with proven sepsis, no infection, or unclassified. The mean study duration was 34 days. Whenever sepsis occurred, a study period of 10 days was defined: day 0 was the day of clinical diagnosis of sepsis; days -4 to -1 were the 4 days before diagnosis; days +1 to +5 were the 5 days after. We compared the concentrations of the immune mediators during the 10-day study period with group-specific baseline values from before day -4. FINDINGS: 101 infants were included in the analysis: 21 with proven sepsis, 20 with no infection, and 60 unclassified. We excluded 57 because of incomplete datasets and 24 who had early-onset sepsis. IL-1ra and IL-6 increased significantly 2 days before diagnosis of sepsis; maximum median increases within the study period were 15-fold for IL-1ra and 12-fold for IL-6. The diagnostic sensitivities of IL-1ra, IL-6, and CRP concentrations on day 0 of diagnosis were 93%, 86%, and 43%, respectively; corresponding values on day -1 were 64%, 57%, and 18%. The specificities of IL-1ra, IL-6, and CRP concentrations were 92%, 83%, and 93%. cICAM-1 had a specificity of only 64%. INTERPRETATION: IL-1ra and IL-6 are superior to cICAM-1 and CRP as predictors of sepsis 1 or more days before clinical diagnosis. Ad-hoc measurement of these cytokines could allow earlier initiation of antibiotic therapy with corresponding improvement in outcome in very-low-birthweight infants with sepsis.

Identification of a tRNA-specific nuclear export receptor.

In eukaryotes, tRNAs are synthesized in the nucleus and after several maturation steps exported to the cytoplasm. Here, we identify exportin-t as a specific mediator of tRNA export. It is a RanGTP-binding, importin beta-related factor with predominantly nuclear localization. It shuttles rapidly between nucleus and cytoplasm and interacts with nuclear pore complexes. Exportin-t binds tRNA directly and with high affinity. Its cellular concentration in Xenopus oocytes was found to be rate-limiting for export of all tRNAs tested, as judged by microinjection experiments. RanGTP regulates the substrate-exportin-t interaction such that tRNA can be preferentially bound in the nucleus and released in the cytoplasm.

Mercury in human colostrum and early breast milk. Its dependence on dental amalgam and other factors.

The mercury concentration in 70 breast milk samples (Hg-M) from 46 mothers, collected within the first 7 days after delivery, was determined by cold vapour atomic absorption spectrometry. For comparison, 9 formula milk samples (reconstituted with Hg-free water) were investigated. The Hg-M in the human milk samples ranged from < 0.2 to 6.86 micrograms/L (median 0.37), in the formula milk samples from 0.4 to 2.5 micrograms/L (median 0.76). The Hg-M in the breast milk samples correlates positively with the number of maternal teeth with dental amalgam. The mean Hg-M of amalgam-free mothers was < 0.2 microgram/L, while milk from mothers with 1-4 amalgam fillings contained 0.57 microgram/L, with 5-7 fillings 0.50 microgram/L and with more than 7 fillings 2.11 micrograms/L. Hg-M correlated negatively to the day after delivery. Frequency of fish consumption tends to influence Hg-M positively, while the age of the mother shows no significant correlation. In the first 2 to 3 days after delivery some colostrum samples with Hg-M higher than in formula milk were found. Later on, the Hg-concentration in the breast milk was equal or even lower to that in formula milk. The higher Hg burden of infants' tissues from mothers with dental amalgam, as reported previously, must be explained (1) by a prenatal transfer of Hg from the mother's fillings through the placenta to the fetus, followed by a redistribution of this Hg in the body of the newborn, and (2) an additional burden via breast milk. Nevertheless, the comparison of Hg-M in breast and formula milk, the relatively moderate Hg burden in both kinds of milk, and the multiple manifest advantages of breast feeding speak against any limitation of nursing, even for mothers with a large number of dental amalgam fillings.

CRISP-3, a protein with homology to plant defense proteins, is expressed in mouse B cells under the control of Oct2.

The Oct2 transcription factor is expressed throughout the B-lymphoid lineage and plays an essential role during the terminal phase of B-cell differentiation. Several genes specifically expressed in B lymphocytes have been identified that contain a functional octamer motif in their regulatory elements. However, expression of only a single gene, the murine CD36 gene, has been shown to date to be dependent on Oct2. Here, we present the identification and characterization of a further gene, coding for cysteine-rich secreted protein 3 (CRISP-3), whose expression in B cells is regulated by Oct2. We show that CRISP-3 is expressed in the B-lymphoid lineage specifically at the pre-B-cell stage. By using different experimental strategies, including nuclear run-on experiments, we demonstrate that this gene is transcriptionally activated by Oct2. Furthermore, analysis of CRISP-3 expression in primary B cells derived from either wild-type or Oct2-deficient mice demonstrates the dependence on Oct2. Two variant octamer motifs were identified in the upstream promoter region of the crisp-3 gene, and Oct2 interacts with both of them in vitro. Cotransfection experiments with expression vectors for Oct1 and Oct2 together with a reporter driven by the crisp-3 promoter showed that transcriptional activation of this promoter can only be achieved with Oct2. The C-terminal transactivation domain of Oct2 is required for this activation. Finally, introducing specific mutations in the two variant octamer motifs revealed that both of them are important for full transcriptional activation by Oct2.

Effects of a low birthweight infant formula containing human milk levels of docosahexaenoic and arachidonic acids.

Long-chain (LC) polyunsaturated fatty acids (PUFA) (LCP) are considered conditionally essential nutrients for low birth weight infants (LBWI). Therefore, enrichment of LBWI formulae with metabolites both linoleic (omega-6) and alpha-linolenic (omega-3) acids at levels typical for human milk has been recommended. However, previous feeding trials with LCP-enriched formulae evaluated only a dietary supplementation with omega-3 LCP from fish oils alone or with both omega-3 and omega-6 LCP at levels considerably lower than usual human milk contents. We studied the effects of an LBWI formula providing the major omega-3 and omega-6 LCP, docosahexaenoic and arachidonic acids, in amounts similar to those in average human milk. Twenty-seven LBWIs were enrolled in this study when they tolerated full enteral feeding (> or = 130 ml milk/kg/day). Infants either received their own mother's milk (n = 8, birthweight 1218 +/- 146 g, gestational age 30.2 +/- 1.5 weeks, mean +/- SD) fortified with protein and minerals (FM-85, Nestle Ag, Munchen, Germany; dosage 5 g/100 ml milk) or were randomly assigned to blinded batches of an LBWI formula (Prematil, Milupa AG, Friedrichsdorf, Germany) without LCP (n = 10, 1280 +/- 229 g, 31.1 +/- 3.1 weeks) or with LCP (n = 9, 1253 +/- 334 g, 30.4 +/- 3.3 wks.). During the study period of 21 days, the three feeding groups did not differ in growth and feeding tolerances as assessed by occurrence of gastric residuals, spitting, or abdominal distention; however, firms stools were noted more frequently in the two formula groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Airway pressure measurements during high-frequency positive pressure ventilation in extremely low birth weight neonates.

OBJECTIVES: Evaluation of a modified, computer-controlled, shutter method to determine the complete intrapulmonary pressure course and to ascertain the expiratory time constant for the respiratory system during high-frequency positive pressure ventilation. DESIGN: Prospective clinical study. SETTING: Neonatal intensive care unit in a university hospital. PATIENTS: Sixteen premature newborns (mean gestational age 26 +/- 2 [SD] wks, birth weight 741 +/- 138 g) were studied at various times during their clinical course. MEASUREMENTS AND RESULTS: Installation of the shutter and air flow interruption did not result in any impairment of clinical and respiratory conditions. Time constants were between 58 and 190 msecs. In six patients, an inadvertent positive end-expiratory pressure (1 to 4.5 cm H2O) was found; in these patients only, expiratory time set at the respirator was < 4 time constants. In 13 measurements of nine patients, measured intrapulmonary peak inspiratory pressure was considerably lower (1 to 5 cm H2O) than that value set at the respirator. CONCLUSIONS: The computer-controlled shutter method is noninvasive and applicable without impairment, even in preterm neonates with birth weights of < 1000 g. This method provides important information to optimize respiratory therapy, particularly knowledge of the individual time constant. To avoid inadvertent positive end-expiratory pressure and gas trapping, expiratory time should be > 4 time constants.

[Intrapulmonary pressure measurements in high frequency ventilation of extremely small premature infants. The triggered airway occlusion method]. / Intrapulmonale Druckmessungen bei Hochfrequenzbeatmung extrem kleiner Frühgeborener. Die getriggerte Luftwegsverschlussmethode.

The interrupter technique is an established method for measuring the intrapulmonary pressure in mechanically ventilated patients. We have developed a computer controlled method enabling us to interrupt the respiratory flow at precisely reproducible occlusion times (triggered by the respirator). It is therefore possible to determine the intrapulmonary pressure course in inspiration and expiration and the time constant for the upper respiratory tract (including the intratracheal tube) even in high-frequency ventilation. In 16 premature infants (mean birth weight 741 +/- 138 g, gestational age 26.1 +/- 1.9 weeks) we measured time constants between 58 and 190 msec for the intrapulmonary pressure decrease in expiration. An inadvertent PEEP between 1 and 4.5 cmH2O was found in 6 out of 23 examinations (ventilation frequency between 67 and 150/min, expiration times between 250 and 500 msec). The relation of expiration time to time constant was less than 4 in these cases only. The triggered interrupter technique is a useful, noninvasive method for monitoring the intrapulmonary pressure in neonates without disturbing the patient. Particularly in critically ill infants the measurements are the basis for optimal respirator settings.

[Indirect determination of the intrapulmonary pressure course in the lung model in high frequency ventilation]. / Indirekte Bestimmung des intrapulmonalen Druckverlaufes am Lungenmodell bei Hochfrequenzbeatmung.

One of the determinants of intrapulmonary pressure during machine ventilation at a given time constant of the respiratory system is the duration of expiration. At high frequencies of ventilation with short expiration times substantial gas trapping can occur with end-expiratory increase in transpulmonary pressure (inadvertent PEEP). The occlusion technique allows measurement of the intrapulmonary pressure at the airway opening because of equilibration throughout the respiratory tract. The complete intrapulmonary pressure curve can be obtained, if occlusion takes place at progressively increasing intervals after the beginning of a breath. We present a computer-assisted method for measuring the occlusion pressure at defined time points throughout the respiratory cycle. A lung simulator is ventilated by a Sechrist ventilator. The tube leading to the simulator is occluded every 5 breaths, the time point of the occlusion being advanced progressively into each breath. Occlusion pressure is compared to intrapulmonary pressure measured directly by an intrapulmonary probe. All of this is controlled by a personal computer. We are able to demonstrate that, at ventilation frequencies of up to 600/min pressure curves measured indirectly correspond sufficiently well with pressures recorded directly in the lung model. An automatic evaluation of the measurements is possible even with a tube leakage of up to 70%.

[Pregnancies in females following kidney and pancreas transplantation]. / Schwangerschaften bei Frauen nach Nieren- bzw. Pankreastransplantation

Uraemic patients are in general infertile. Ovarian function is, however, restored after successful renal transplantation, thus making conception possible. We followed up 14 patients after renal transplantation involving 16 pregnancies. Two patients became pregnant twice, one with twins and the other following renal and pancreatic transplantation--the first recorded in the world. Caesarean section was performed in all patients due to increasing serum creatinin levels, avoid pre-eclampsia or premature rupture of membranes. Both, mother and child in all cases progressed without complications, although these pregnancies are associated with high risk for both. Therefore, a close co-operation between the mother, the nephrologist, the transplantation centre, the gynaecologist and the paediatrician is a prerequisite for a possible favourable course.

[Pharmacokinetics of theophylline and caffeine in premature infants with apnea (author's transl)]. / Pharmakokinetik von Theophyllin und Coffein bei Frühgeborenen mit Apnoen.

In apneic premature infants treated with theophylline or caffeine the pharmacokinetics of the methylxanthines were investigated. Orally applied caffeine and theophylline were rapidly absorbed reaching peak plasma levels at 1-2 and 1-4 h resp. The plasma concentration of free theophylline was significantly higher (p less than 0.001) in prematures than in adults. In prematures and adults only 5 resp. 8% of caffeine were bound to the plasma proteins. The salivary methylxanthine concentration corresponds to the plasma concentration of the free drugs. The mean plasma half-live of theophylline was 22.3 h, the clearance 28.3 ml/kg/h and the volume of distribution 0.9 l/kg. For caffeine a plasma half-live of 70.6 h, a clearance of 8.6 ml/h/kg and a volume of distribution of 0.84 l/kg was found. A first oral dose of 7-9 mg/kg theophylline or caffeine should be administered to reach rapidly effective plasma concentrations of about 10 micrograms/ml. To maintain a mean plasma concentration of about 10 micrograms/ml, a daily oral maintenance dose of 5-9 mg/kg theophylline or 2 mg/kg caffeine should be given. High concentrations of unchanged caffeine and theophylline were excreted in the urine of premature infants indicating immaturity of the metabolizing hepatic enzymes. In prematures treated with theophylline caffeine was found in plasma as a metabolite of theophylline.

[Treatment of the dyspnea syndrome by continuous negative pressure (author's transl)]. / Uber die Behandlung des Atemnotsyndroms durch kontinuierlich negativen Druck. Eine neue Methode zur Abdichtung bei CNP

It has been firmly established that CPTP is of great value in the treatment of IRDS and other respiratory insufficiencies. We believe that CPTP is best applied in the form of CNP. A method is described to safely and tightly close the CNP--chamber using self adhering plastic sheets.

[Combination of CPPB with IPPV (author's transl)]. / Die Kombination von Spontanatmung unter erhöhtem Atemwegsdruck mit maschineller Beatmung durch intermittierenden Druck

A combination of CPPB and IPPV has been used successfully in our hospital for therapy of children with IRDS, when their spontaneous breathing under CPAP was not sufficient and to get children progressively used to spontaneous respiration after prolonged periods of controlled ventilation. The Assistor 644 and Servoventilator 900 respirators are not equipped for the combination of CPPB and IPPV. We describe the modifications of both respirators which we introduced to be able to use them for CPPB alone as well as for the combination of CPPB with CPPV.