[The Wolf-Hirschhorn Syndrome]. / Das Wolf-Hirschhorn Syndrom.

Wolf-Hirschhorn syndrome (WHS) represents a complex developmental disorder characterized by craniofacial dysmorphism, short stature, hypotonia, psychomotor retardation and seizures caused by a terminal deletion of the short arm of chromosome 4. Depending on the extent of the deletion, variable midline defects, abnormalities of the skeletal or urogenital system as well as the central nervous system are observed. Approximately 1/3 of the infants will die in the first year of life even though survival for more than 30 years has been reported. Due to current high quality standards of ultrasonography, WHS can often be diagnosed prenatally. We present a clinical case and provide an overview of the current literature.

The Cause of Acute Respiratory Failure Predicts the Outcome of Noninvasive Ventilation in Immunocompromised Children.

BACKGROUND: Noninvasive ventilation (NIV) may be superior to conventional therapy in immunocompromised children with respiratory failure. METHODS: Mortality, success rate, prognostic factors and side effects of NIV for acute respiratory failure (ARF) were investigated retrospectively in 41 in children with primary immunodeficiency, after stem cell transplantation or chemotherapy for oncologic disease. RESULTS: In 11/41 (27%) children invasive ventilation was avoided and patients were discharged from ICU. In children with NIV failure ICU-mortality was 19/30 (63%). 8/11 (72%) children with NIV success had recurrence of ARF after 27 days. Only 4/11 (36%) children with first episode NIV success and 8/30 (27%) with NIV failure survived to hospital discharge. Lower FiO2, SpO2/FiO2 and blood culture positive bacterial sepsis were predictive for NIV success, while fungal sepsis or culture negative ARF were predictive for NIV failure. We observed catecholamine treatment in 14/41 (34%), pneumothorax in 2/41 (5%), mediastinal emphysema in 3/41 (7%), a life threatening nasopharyngeal hemorrhage and need for resuscitation during intubation in 5/41 (12%) NIV-episodes. CONCLUSIONS: The prognosis of ARF in immunocompromised children remains guarded independent of initial success or failure of NIV due to a high rate of recurrent ARF. Reversible causes like bacterial sepsis had a higher NIV response rate. Relevant side effects of NIV were observed.

Effects of short sustained lung inflations on cerebral blood flow and cerebral tissue oxygenation in the juvenile rabbit.

BACKGROUND: Sustained lung inflations improve oxygenation but may impair hemodynamics. This study aimed to determine effects of short sustained inflations on cerebral blood flow and cerebral tissue oxygenation in experimental lung injury. METHODS: Experiments were performed in 6 juvenile ventilated New Zealand white rabbits. The effects of a series of sustained inflations at 20, 25 and 30 cmH2O pressure for 15 seconds duration each on hemodynamics, cerebral blood flow and cerebral tissue oxygenation were determined by laser Doppler flowmetry and cerebral tissue oxygen tension measurement in naive animals, after surfactant depletion and subsequent fluid filling of the lung. RESULTS: During the series of sustained inflations the mean arterial blood pressure decreased by 73%, 52% and 32% and the mean cerebral blood flow decreased by 73%, 39% and 30% in naive animals, after surfactant depletion and with fluid filling of the lung respectively. Arterial oxygen saturation was maintained or increased, while mean cerebral tissue oxygenation decreased by 48% (naive), 8% (surfactant depletion) or increased by 81% (surfactant depletion and fluid filling). Three minutes after the sustained inflations blood gases were similar to the blood gases prior to the sustained inflations. CONCLUSION: A series of short sustained lung inflations of 15 seconds duration can impair cerebral blood flow but increase arterial oxygen saturation in this juvenile animal model. The combination of these effects resulted in either a decrease or increase in regional cerebral tissue oxygenation.

Brain oxygenation monitoring during neonatal resuscitation of very low birth weight infants.

OBJECTIVE: To explore if regional cerebral tissue oxygen saturation monitoring by near-infrared spectroscopy (NIRS) is feasible during neonatal resuscitation of very low birth weight (VLBW) infants after birth. STUDY DESIGN: Cerebral tissue oxygen saturation was measured by NIRS in 51 VLBW infants (mean gestational age: 27.8 weeks) during the first 10 min after delivery. RESULT: A regional cerebral tissue oxygen saturation signal was available after a median (interquartile range) age of 52 (44 to 68) s. In three infants the signal was obtained after 10 min of age. After delivery cerebral tissue oxygen saturation rose continuously from 37 (31 to 49) % at 1 minute of age and reached a steady state in the range of 61 to 84% ∼7 min after birth. Percentiles of cerebral tissue oxygen saturation of this cohort of preterm infants are given. CONCLUSION: Cerebral tissue oxygen saturation monitoring is feasible during neonatal resuscitation of VLBW infants within the first minutes of life.

Comparison of monolithic and microparticulate columns for reversed-phase liquid chromatography of tryptic digests of industrial enzymes in cleaning products.

Enzymes of several classes used in the formulations of cleaning products were characterized by trypsin digestion followed by HPLC with UV detection. A polymeric monolithic column (ProSwift) was used to optimize the separation of both the intact enzymes and their tryptic digests. This column was adequate for the quality control of raw industrial enzyme concentrates. Then, monolithic and microparticulate columns were compared for peptide analysis. Under optimized conditions, the analysis of tryptic digests of enzymes of different classes commonly used in the formulation of cleaning products was carried out. Number of peaks, peak capacity and global resolution were obtained in order to evaluate the chromatographic performance of each column. Particulate shell-core C18 columns (Kinetex, 2.6 µm) showed the best performance, followed by a silica monolithic column (Chromolith RP-18e) and the conventional C18 packings (Gemini, 5 µm or 3 µm). A polymeric monolithic column (ProSwift) gave the worst performances. The proposed method was satisfactorily applied to the characterization of the enzymes present in spiked detergent bases and commercial cleaners.

Predictors of early nasal CPAP failure and effects of various intubation criteria on the rate of mechanical ventilation in preterm infants of <29 weeks gestational age.

INTRODUCTION: Delivery room management using early nasal continuous positive airway pressure (nCPAP) may delay surfactant therapy. OBJECTIVE: To identify factors associated with early nCPAP failure and effects of various intubation criteria on rate and time of intubation. DESIGN: Retrospective analysis of the first 48 h in infants of 23-28 weeks gestational age (GA) treated with sustained inflations followed by early nCPAP. RESULTS: Of 225 infants (GA 26.2±1.6 weeks) 140 (62%) could be stabilised with nCPAP in the delivery room, of whom 68 (49%; GA 26.9±1.5 weeks) succeeded on nCPAP with favourable outcome and 72 infants (51%; GA 26.3±1.4 weeks) failed nCPAP within 48 h at a median (IQR) age of 5.6 (3.3-19.3) h. History or initial blood gases were poor predictors of subsequent nCPAP failure. Intubation at fraction of inspired oxygen (FiO(2))≥0.35 versus 0.4 versus 0.45 instead of ≥0.6 would have resulted in unnecessary intubations of 16% versus 9% versus 6% of infants with nCPAP success but decreased the age at intubation of infants with nCPAP failure to 3.1 (2.2-5.2) versus 3.8 (2.5-8.7) versus 4.4 (2.7-10.9) h. CONCLUSIONS: Medical history or initial blood gas values are poor predictors of subsequent nCPAP failure. A threshold FiO(2) of ≥0.35-0.45 compared to ≥0.6 for intubation would shorten the time to surfactant delivery without a relevant increase in intubation rate. An individualised approach with a trial of early nCPAP and prompt intubation and surfactant treatment at low thresholds may be the best approach in very low birthweight infants.

A comprehensive chemoselective and enantioselective 2D-HPLC set-up for fast enantiomer analysis of a multicomponent mixture of derivatized amino acids.

A feasibility study on the fast enantioselective two-dimensional HPLC separation of racemic amino acid derivatives is presented. The method involves the on-line coupling of a narrow-bore C18 RP column in the first dimension to a short enantioselective column based on nonporous 1.5 microm particles modified with quinidine carbamate as chiral selector in the second dimension. Conceptually, the system was designed to enable both time-controlled repeated transfer of fractions of the eluate and detector-controlled transfer of selected fractions from column 1 to column 2. To avoid volume overloading of the second chiral column, a narrow-bore reversed phase column was installed in the first dimension. Due to the fast (less than 1.5 minutes) enantiomer separation that occurs in the second dimension, the overall analysis time for the two-dimensional separation of a mixture of nine racemic 3,5-dinitrobenzoyl amino acids was optimized at 16 minutes.

Solid-phase capture and release of arginine peptides by selective tagging and boronate affinity chromatography.

A method for the selection of arginine-containing peptides from a mixture by a solid phase capture and release technique is presented. The method is based on the covalent modification of the guanidine group of arginine with 2,3-butanedione and phenylboronic acid under alkaline conditions. Using polymeric materials with immobilised phenylboronic acid the arginine-peptides can be captured on a solid support while arginine-free peptides are not covalently bound and can be washed away. Finally, the arginine-peptides can be cleaved again from the boronic acid beads due to the reversibility of the reaction. The recovered peptides are then analysed by liquid chromatography-tandem mass spectrometry. The method was optimised with model peptides with regard to the non-specific binding of arginine-free peptides and quantitative cleavage of the label after the selection step. Using an adequate protocol, the applicability towards more complex samples was successfully tested with a tryptic digest of a mixture of three standard proteins.

Short-term outcome in infants with a birthweight less than 501 grams.

AIM: To report survival and morbidity until discharge in preterm infants <501 g with life support started immediately after birth. METHODS/STUDY DESIGN: Cohort study of all preterm infants with birthweights < 501 g born in three tertiary perinatal centres between 1 January 1998 and 31 December 2001 (gestational age (GA) 25.2 [21.0-30.7] wk; birthweight 435 [290-500] g; median [range]). RESULTS: A total of 107 infants with birthweights <501 g were born. Twenty-nine were stillborn. A prenatal decision to initiate life support immediately after birth was reached in 9/37 (24%) infants <24.0 wk GA and in 39/42 (93%) infants > or =24.0 wk GA. Survival was 3/37 (8%) and 26/41 (63%) in infants <24 wk GA and > or =24.0 wk GA, respectively. Twenty-nine of the 48 infants with immediate life support (60%) survived (95% CI: 46-75%). Forty-two of these 48 (88%) infants were small for gestational age. No infant without immediate life support survived (0/30). Twenty-three (79%) survivors developed chronic lung disease (CLD) and eight (28%) received photocoagulation for retinopathy of prematurity (ROP). CONCLUSION: In this population of extremely low birthweight infants, survival was higher than in previous studies when life support was provided immediately after birth. Short-term morbidity was similar to other studies. The presented data on survival support our concept to offer immediate life support after birth in preterm infants with birthweights <501 g. The long-term outcome of these infants needs to be assessed urgently.

Monolithic silica columns with chemically bonded beta-cyclodextrin as a stationary phase for enantiomer separations of chiral pharmaceuticals.

An enantioselective silica rod type chiral stationary phase (CSP) is presented; a novel combination of the well known enantiomer separation properties of beta-cyclodextrin and the unique properties concerning the flow behavior of silica monoliths. Two different synthesis routes are described, and it was found that the in situ modification of a plain silica rod column turned out to be the best. The chromatographic behaviour of the beta-cyclodextrin silica rod was studied and compared with a very similar commercially available beta-cyclodextrin bonded particulate material (ChiraDex). Even if the amount of beta-cyclodextrin bound to the silica rod was only about half of the amount of beta-cyclodextrin bound to ChiraDex) particles, good resolutions were achieved for a set of chiral test components like Chromakalin, Prominal, Oxazepam, Methadone and some other drugs. By taking advantage of the unique features of the silica rods relating to their flat H/u (Van Deemter) curves, fast enantiomer separations could be demonstrated.

Enantiomer separation of N-protected amino acids by non-aqueous capillary electrophoresis and high-performance liquid chromatography with tert.-butyl carbamoylated quinine in either the background electrolyte or the stationary phase.

A non-aqueous CE method was developed for evaluating the chiral discrimination potential of cinchona alkaloids and different kinds of carbamoylated derivatives of quinine and quinidine type chiral selectors towards acidic analytes, in particular a series of various Bz (benzoyl), DNB (3,5-dinitrobenzoyl) and DNZ (3,5-dinitrobenzyloxycarbonyl) amino acid derivatives. In this study, the enantioselectivity values obtained in non-aqueous CE with tert.-butyl carbamoylated quinine as chiral additive have been compared with the values found for the same series of selectands in HPLC using the same selector immobilized onto silica as chiral stationary phase. Similarly to the background electrolyte used in CE an ethanol-methanol mixture (60:40, v/v) containing 100 mM octanoic acid and 12.5 mM ammonia has been selected as HPLC mobile phase. Under these conditions, a good correlation (r = 0.954) between the enantioselectivities observed with the two techniques has been obtained. Thus the non-aqueous CE method can be applied as a screening tool for the rapid evaluation of the chiral discrimination potential of a large set of newly developed chiral selectors derived from quinine and related alkaloids.

Enantioseparation of various amino acid derivatives on a quinine based chiral anion-exchange selector at variable temperature conditions. Influence of structural parameters of the analytes on the apparent retention and enantioseparation characteristics.

The influence of temperature on the performance of an enantioselective anion-exchange type chiral selector (SO) was systematically investigated. The resolution of the enantiomers of 23 N-acylated amino acids (selectands, SAs) on a covalently immobilized quinine tert.-butylcarbamate chiral stationary phase (CSP) was studied under linear chromatographic conditions over a temperature range of 0-85 degrees C with hydro-organic buffers (pHa 6.0) as mobile phases. The apparent enantioseparation factors increased considerably at low column temperatures, indicating that enthalpic contributions are the dominating thermodynamic driving force for chiral recognition for all investigated SAs. Retention factors gave non-linear van't Hoff plots, while the corresponding apparent enantioseparation factors showed linear van't Hoff behavior. Correlations between magnitude and sign of the relative thermodynamic parameters of enantioselective adsorption (deltadeltaG, deltadeltaH and deltadeltaS) and specific structural features of the analytes, i.e., steric and electronic nature of the various side chains and the N-acyl groups, are discussed with the aim to rationalize their possible contributions to the overall chiral recognition.

Epinephrine treatment of hypotension in very low birthweight infants.

UNLABELLED: The aim of this study was to examine the influence of a continuous infusion of epinephrine (adrenaline) on mean arterial blood pressure (MABP), heart rate, urine output and base deficit in very low birthweight infants (VLBWI) with systemic hypotension. In VLBWI who received an infusion of epinephrine for at least 12 h the mean urine output, administered fluid volume, base deficit and administered buffer 12 h before and 12 h during the infusion were recorded. If the infusion was shorter, but given for at least 2 h, the mean heart rate and MABP 2 h before and 2 h during the infusion were recorded. Thirty-one infants with a gestational age of 26 (23-30) wk [median (minimum-maximum)] and birthweight 690 (390-1310) g were included in this retrospective chart review. The patients received an infusion of epinephrine at a postnatal age of 3 (1-21) d. The doses ranged between 0.05 and 2.6 microg kg(-1) per minute within the first 24 h of administration. Three of 31 infants received epinephrine on 2 different occasions. The MABP [+7 (-1 to 13) mmHg, p=0.000001] and the heart rate [+10 (-10 to 42) bpm, p=0.000036] increased significantly (n = 34), whereas total volume administration and urine output remained the same between the 2 periods (Wilcoxon matched pairs test). The base deficit increased significantly [-3 (-10.2 to 2.6), p = 0.0014, n = 19] without a change in the administration of buffer. CONCLUSION: The infusion of epinephrine increased the MABP and the heart rate without decreasing urine output in VLBWI with hypotension not responding to a dopamine infusion up to 15 microg kg(-1) per minute. A potential adverse effect was an increase in metabolic acidosis.

On-column deracemization of an atropisomeric biphenyl by quinine-based stationary phase and determination of rotational energy barrier by enantioselective stopped-flow HPLC and CEC.

The reversible enantiomerization of axially chiral 2'-dodecyloxy-6-nitrobiphenyl-2-carboxylic acid was studied in the presence of a brush type chiral stationary phase based on O-(tert-butylcarbamoyl) quinine as chiral selector unit by stopped-flow high-performance liquid chromatography (sfHPLC) and capillary electrochromatography (sfCEC). After initial separation of the enantiomers in the first section of the column, the flow was stopped and the resolved species allowed to enantiomerize on-column. From this conversion, which could be determined from the enantiomeric ratios at different enantiomerization times, kinetic rate constants were calculated. By sfHPLC at a constant temperature of 15 degrees C, kinetic rate constants in the presence of the CSP were found to be 4.1 x 10(-5) s(-1) and 2.2 x 10(-5) s(-1) for the (-) and (+)-enantiomers, respectively, corresponding to half-lives of 279 and 530 min. Thus, apparent activation energies of enantiomerization were calculated to be 93.0 and 94.6 kJ mol(-1) for the (-) and (+)-enantiomers. On the macroscopic level, the apparent difference of rotational energy barriers and kinetic rate constants for both enantiomers is reflected as deracemization. For example, starting from a racemic mixture, an enantiomeric excess (ee) of 14% was seen in the stopped-flow HPLC experiment described after an enantiomerization time of 220 min at 15 degrees C, and a maximal ee of 17% can be approximated after infinite enantiomerization time. There is good agreement between HPLC and CEC results as well as their experimental errors, confirming that the new sfCEC technique may be a valuable and convenient tool to study interconversion processes.

Development of stereoselective nonaqueous capillary electrophoresis system for the resolution of cationic and amphoteric analytes.

A stereoselective ion-pair nonaqueous capillary electrophoresis (NACE) method employing the partial filling technique with N-derivatized amino acids, e.g., (R)- and (S)-3,5-dinitrobenzoyl-leucine (DNB-Leu), as chiral selector for the separation of "pseudoenantiomeric" cinchona alkaloid derivatives and other structurally related basic compounds like the enantiomers of mefloquine is presented. Originating from NACE with cinchona alkaloid derivatives as chiral counterions, this method was developed by application of the reciprocity principle of chiral recognition, which was proven to be valid for stereoselective ion-pair capillary electrophoresis (CE). A variety of basic and amphoteric selectands (SAs) could be well resolved. Thereby, the separation was primarily based on stereoselective ion-pair formation of corresponding SA stereoisomers and mobility differences of free and complexed (ion-paired) SAs. Additionally, in the case of diastereomeric SAs, naturally existing mobility differences between the diastereomers played also a role, but was shown by control experiments with racemic DNB-Leu and without selector (SO) to be of minor contribution to overall separation selectivity. Due to its simplicity, speed, and good reproducibility, the established method can be utilized for fast screening of cationic as well as amphoteric chiral compounds, and therefore is a valuable tool in the development of new chiral selectors and chiral stationary phases. Small sample amounts of the SO (4-5 mg) and only analytical amounts of SAs are needed, and about 20-50 compounds per day can be tested.

Capillary electrochromatography in anion-exchange and normal-phase mode using monolithic stationary phases.

Hydrophilic macroporous weak and strong anion-exchange stationary phases have been prepared in a monolithic format within untreated fused-silica capillaries by the simple thermally or UV-initiated polymerization of 2-dimethylaminoethyl methacrylate, 2-hydroxyethyl methacrylate and ethylene dimethacrylate in the presence of a binary porogenic mixture of dodecanol and cyclohexanol. The tertiary amino functionalities were then alkylated in situ to afford strong anion-exchangers. These new monolithic stationary phases with optimized porous properties were used for the CEC separation of various organic anions. Thus, a mixture of 2-substituted propionic acid drugs (profens) was separated in 13 min and high column efficiencies of up to 231,000 plates/m were achieved. The separation of substituted benzoic acids indicates that the selectivity results primarily from the anion-exchange interactions, while electrophoretic migration contributes only slightly. In addition, these hydrophilic anion-exchangers are also able to separate weakly acidic, neutral and basic compounds such as phenols, xanthines and aromatic amines in normal-phase electrochromatographic mode.

Congenital neuroblastoma mimicking early onset sepsis.

UNLABELLED: A newborn girl presented with symptoms of severe early onset sepsis but also with systemic hypertension (SH) at age 3 h. Plasma catecholamine (CAT) levels were extremely elevated, reflecting increased release of CAT from a congenital neuroblastoma (NB). Clinical symptoms at time of admission were: prolonged capillary refill (5 s), tachycardia, tachydyspnoea, metabolic acidosis (pH 7.17, lactate 11.8 mmol/l), fever (38.4 degrees C) and SH: 90/50/65 mmHg (systolic/diastolic/mean). The infant experienced organ failure (lung, heart, liver). A retroperitoneal dumbbell tumour was detected. Plasma CAT levels at age 15 h were: noradrenaline 219 nmol/l; adrenaline 13 nmol/l; and dopamine 65.3 nmol/l. SH responded to intermittent alpha-adrenergic blockage. CAT-related symptoms ceased within 1 week. The intraspinal NB was surgically removed when cord compression became symptomatic. The neurological and developmental state is normal at age 17 months. The abdominal NB regressed spontaneously. CONCLUSION: A neuroblastoma should be considered in newborn infants presenting with a shock-like condition together with systemic hypertension.

Reaction monitoring of platinum(II) complex--5'-guanosine monophosphate adduct formation by ion exchange liquid chromatography/electrospray ionization mass spectrometry.

Cisplatin and four structurally related platinum(II) complexes were incubated with guanosine 5'-monophosphate (5'-GMP) in water at 37 degrees C. The adduct formation reactions were monitored with cation- and anion-exchange liquid chromatography/electrospray ionization mass spectrometry. In addition to mono- and bis-adducts of guanosine 5'-monophosphate with the platinum(II) complexes, other molecular species, presumably with a binuclear structure (two platinum(II) centres), were detected in the reaction mixtures, which have not been reported previously, indicating an unexpected complexity of adduct formation. Anion-exchange chromatography revealed the presence of isomers of two complexes which presumably result from the restricted rotation at the platinum-- N-7 (5'-GMP) bonds. All reaction products were characterized in both the positive and negative ion modes. Furthermore, preliminary kinetics and half-times of complex formation were investigated for cisplatin and two other platinum(II) complexes, monitoring the relative concentrations of free 5'-GMP and of mono- and bis-GMP adducts as a function of time (250 h) using an internal standard protocol with thymidine 5'-monophosphate.

Stereoselective effects of (R)- and (S)-carvedilol in humans.

Carvedilol is currently used as the racemic mixture, (R,S)-carvedilol, consisting of equal amounts of (R)-carvedilol, an alpha-blocker, and (S)-carvedilol, an alpha- and beta-blocker, which have never been tested in their optically pure forms in human subjects. We performed a randomized, double-blind, placebo-controlled, crossover study in 12 healthy male volunteers. Subjects received single oral doses of 25 mg (R,S)-carvedilol, 12.5 mg (R)-carvedilol, 12.5 mg (S)-carvedilol, and placebo at 8 AM as well as at 8 PM. Exercise was performed at 11 AM, and heart rate and blood pressure were measured at rest and after 10 min of exercise. Urine was collected between 10 AM and 6 PM, as well as between 10 PM and 6 AM, and the amounts of urinary 6-hydroxy-melatonin sulfate (aMT6s) were determined by RIA. Compared to placebo, (R)-carvedilol increased heart rate during exercise (+4%, P < 0.05) and recovery (+10%, P < 0.05); (S)-carvedilol decreased heart rate during exercise (-14%, P < 0.05) and recovery (-6%, P < 0.05), and systolic blood pressure during exercise (-12%, P < 0.05); (R,S)-carvedilol decreased heart rate during exercise (-11%, P < 0.05), and systolic blood pressure at rest (-7%, P < 0.05) and during exercise (-10%, P < 0.05). None of the agents had any significant effect on the release of aMT6s. Our results indicate that only (S)-carvedilol causes beta-blockade, whereas (R)-carvedilol appears to increase sympathetic tone, presumably as a physiological reaction to the decrease of blood pressure caused by alpha-blockade. None of the drugs had any influence on melatonin release. The weak clinical net effect of beta-blockade of (R,S)-carvedilol at rest might be one reason why this drug causes fewer side effects than other beta-blockers, such as a reduction of nocturnal melatonin release.