Isolation and structural analysis of peptide mimotopes for the disialoganglioside GD2, a neuroblastoma tumor antigen

The disialoganglioside GalAcbeta1-4(NeuAcalpha2-8NeuAcalpha2-3)Galbeta1-4Glcbeta1-1Cer (GD2) is expressed on various tumors, including neuroblastoma, and was defined as a relevant tumor antigen. The monoclonal anti-GD2 antibody 14.18 is widely used for diagnostic purposes in neuroblastoma, and in its mouse/human chimeric form (ch14.18) now enters passive immunotherapeutic regimens in phase II clinical trials. This study aimed to generate structural mimics of the 14.18 epitope of GD2. Therefore, we used the ch14.18 antibody for selecting immunoreactive GD2 peptide mimotopes from a decamer phage display library. In all, 13 GD2 peptide mimics could be determined by biopanning and their specificity was demonstrated by exclusive recognition by the ch14.18 antibody. Furthermore, their nature of being GD2 mimics and their degree of mimicry was confirmed by competition with the natural antigen. When performing a comparative visualization of the GD2 epitope and selected mimotopes using a three-dimensional computer modeling system (BALLView), we demonstrated fitting of the GD2 molecule and the mimotopes in the antigen-binding pouch of a GD2 specific antibody. Moreover, the computer modeling argued for optimal affinity of the GD2 mimotopes. We thus provide evidence that the generation of GD2 peptide mimotopes is successful when using the neuroblastoma antibody ch14.18 for selection, and that this approach might offer a tool to develop a vaccination strategy against this malignant pediatric tumor.

Amniotic cavity cultures, blood cultures, and surface swabs in preterm infants--useful tools for the management of early-onset sepsis?

AIMS

To evaluate the potential benefit of amniotic fluid and amniotic/placental membrane cultures for the management of early-onset sepsis in preterm infants.

METHODS

The results of amniotic cavity cultures obtained during cesarean section and of peripheral blood cultures and surface swabs obtained from the preterm infant at the time of admission were analyzed with respect to the diagnosis of clinical sepsis in 221 preterm infants <34 weeks of gestation.

RESULTS

136 (61.5%) patients had negative amniotic cavity culture results or growth of contaminants, 56 (25.3%) had growth of Ureaplasma urealyticum, and 29 (13.1%) of other pathogens. The corresponding numbers for surface swabs were 82.8%, 11.6%, and 5.6%. A positive blood culture was found in only two neonates. Fifty-four patients (24.4%) had clinical early-onset sepsis. Patients with amniotic cavity culture results that were positive for other pathogens were significantly more likely to experience clinical sepsis than patients with negative culture results (51.7% vs 15.1%, OR 6.1, p<0.0001). Regarding surface swabs, this correlation did not reach statistical significance.

CONCLUSION

The strong association between positive amniotic cavity culture results and clinical early-onset sepsis supports the existence of a causal relation and provides evidence for the potential value of amniotic and/or placental membrane sampling in the management of early-onset sepsis in preterm infants. Surface swabs add no additional information and hence should not be performed routinely.

Subtelomeric rearrangements as neutral genomic polymorphisms

Submicroscopic chromosomal rearrangements affecting telomeres are important aetiological contributors to the development of mental retardation. Results from over 2,500 analysed patients with mental retardation demonstrated that about 5% have a subtelomeric aberration. However, some subtelomeric rearrangements have no phenotypic consequences. Due to the heterogeneity of such rearrangements and to the limited information about which monosomy or trisomy can be tolerated without phenotypic effect, conclusions about the association of a specific aberration and the phenotypical consequences are often hard to draw. We performed a study of subtelomeric aberrations with the aim to provide more insights into the understanding of such rearrangements as neutral genomic polymorphisms. We found two new polymorphisms: a duplication or triplication of the subtelomeric region of the long arm of chromosome 4 and a trisomy of the subtelomeric region of the short arm of chromosome 6 owing to a transposition to chromosome 22. These new data are presented and discussed in the context of the published literature.

EARLY MECHANICAL VENTILATION IS DELETERIOUS AFTER ASPIRATION-INDUCED LUNG INJURY IN RABBITS

We investigated whether mechanical ventilation after aspiration is deleterious when started before surfactant therapy. Gas exchange and lung mechanics were measured in rabbits after aspiration either mechanically ventilated before or after lavage with diluted surfactant or Ringer's solution. Lung injury was induced by intratracheal instillation of 2 mL/kg of a betain/HCl pepsin mixture. After 30 min of spontaneous breathing, ventilation was started in 12 rabbits, which were then treated by lavage with diluted surfactant (15 mL/kg body weight; 5.3 mg/mL, group MVpre S) or with Ringer's solution (1 mL/kg; group MVpre R). Another 12 rabbits were treated by lavage while spontaneously breathing and were then connected to the ventilator (MVpost S and MVpost R). Sham control rabbits were mechanically ventilated for 4 h. At the end of experiment, PaO2/FiO2 ratio in MVpost S was five times higher than in MVpre S (P=0.0043). Lung mechanics measurements showed significant difference between MVpre S and MVpost S (P=0.0072). There was histopathologic evidence of decreased lung injury in MVpost S. Immediate initiation of ventilation is harmful when lung injury is induced by aspiration. Further investigations are needed to clarify whether the timing of lavage with diluted surfactant has an impact on the treatment of patients with aspiration or comparable types of direct lung injury.

Lack of correlation between fatty acid oxidation disorders and haemolysis, elevated liver enzymes, low platelets (HELLP) syndrome?

AIM

Fatty acid beta-oxidation defects comprise a heterogeneous group of disorders that may precipitate acute life threatening metabolic crises particularly during catabolic episodes. Several studies have demonstrated a possible association between fatty acid beta-oxidation defects, including long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency and severe pregnancy complications. However, the precise percentage of women with haemolysis, elevated liver enzymes, low platelets (HELLP) syndrome associated with foetal fatty acid beta-oxidation defects is not known.

METHODS

We carried out a multicentre retrospective study on 88 infants, born to women with HELLP syndrome. Acylcarnitine profiles from blood dried on filter paper cards were analysed by tandem mass spectrometry for the diagnosis of fatty acid beta-oxidation defects. In addition, we screened for the common long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency mutation using a standard restriction fragment length polymorphism polymerase chain reaction method.

RESULTS

None of the infants studied carried the common long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency mutation. There was no evidence of fatty acid beta-oxidation defects, including long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency, as expected by unremarkable acylcarnitine profiles, while three infants with fatty acid beta-oxidation defects were diagnosed in the control group.

CONCLUSIONS

Neither foetal long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency, including heterozygosity for the common long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency mutation, nor fatty acid beta-oxidation defects in general are a major risk factor for HELLP syndrome in Austria.

Association between congenital toxoplasmosis and preterm birth, low birthweight and small for gestational age birth

OBJECTIVE

To determine the association between congenital toxoplasmosis and preterm birth, low birthweight and small for gestational age birth.

DESIGN

Multicentre prospective cohort study.

SETTING

Ten European centres offering prenatal screening for toxoplasmosis.

POPULATION

Deliveries after 23 weeks of gestation in 386 women with singleton pregnancies who seroconverted to toxoplasma infection before 20 weeks of gestation. Deliveries after 36 weeks in 234 women who seroconverted at 20 weeks or later, and tested positive before 37 weeks.

METHODS

Comparison of infected and uninfected births, adjusted for parity and country of birth.

MAIN OUTCOME MEASURES

Differences in gestational age at birth, birthweight and birthweight centile.

RESULTS

Infected babies were born or delivered earlier than uninfected babies: the mean difference for seroconverters before 20 weeks was -5.4 days (95% CI: -1.4, -9.4), and at 20 weeks or more, -2.6 days (95% CI: -0.5, -4.7). Congenital infection was associated with an increased risk of preterm delivery when seroconversion occurred before 20 weeks (OR 4.71; 95% CI: 2.03, 10.9). No significant differences were detected for birthweight or birthweight centile.

CONCLUSION

Babies with congenital toxoplasmosis were born earlier than uninfected babies but the mechanism leading to shorter length of gestation is unknown. Congenital infection could precipitate early delivery or prompt caesarean section or induction of delivery. We found no evidence for a significant association between congenital toxoplasmosis and reduced birthweight or small for gestational age birth.

Knowledge-based computer-aided decision support in prenatal toxoplasmosis screening (TempToxopert)

The development of TempToxopert aimed at assisting clinicians in analysing the results of prenatal toxoplasmosis screening tests. Expert knowledge about diagnostics, screening strategies, and treatment of toxoplasmosis during pregnancy was collected and represented as a rule-based decision graph. Based on actual and past individual findings, the system generates case-specific interpretative reports consisting of a diagnostic hypothesis, recommendations for further treatment, and interpretations of specific test results.

Monocyte switch in neonates: high phagocytic capacity and low HLA-DR expression in VLBWI are inverted during gestational aging

Pre-term neonates are at high risk to develop early-onset sepsis which possibly is caused by an immature immune system. Monocytes play a pivotal role as professional phagocytic and antigen-presenting cells in the innate immunity. In the present study, we investigated in monocytes from cord blood the expression of human leukocyte antigen (HLA)-DR as a marker for antigen-presenting capability, the expression of the high-affinity receptor for IgG (FcgammaRI/CD64), and the capacity to phagocytize non-opsonized Escherichia coli. We compared 70 infants in three groups according to their gestational age (group I: 20 very low birth weight infants (VLBWI), 24-31 weeks of gestation; group II: 25 pre-term infants, 32-36 weeks of gestation, and group III: 25 term neonates). The expression of CD64 as well as the phagocytic capacity of monocytes from cord blood were highest in VLBWI (p < 0.05 and p < 0.01, respectively). In contrast, HLA-DR expression was significantly (p < 0.05) diminished in VLBWI, which possibly leads to a reduced antigen-presenting capacity. We conclude that monocytes have different functional properties during gestational aging, which perhaps participate in the high incidence of infections in VLBWI.

A novel technique to measure position-dependent resistance changes in the vertebral arteries postmortem: new insights into the aetiology of SIDS?

AIM

A central respiratory regulation disturbance--triggered by impaired oxygen supply to the brainstem--is being discussed as an aetiological factor in sudden infant death syndrome. In this experimental study, further insight was sought into how far cervical spine movements may induce critical narrowing of the vertebral arteries.

METHODS

In 10 infant bodies, the vertebral arteries were cannulated close to their origin and perfused with a fluid bolus of 5 ml in 2 s. The intravascular peak pressure created was memorized. Individual resistance indices were computed for every vertebral artery by relating the average pressure maximum from 10 measurements each with maximal rotation of the neck to either side alone and then with additional hyperextension of the cervical spine to the average peak pressure in neutral head position.

RESULTS

Alterations of position-induced pressure changes occurred in the vertebral arteries of all children. Considering exclusively the combined movements of rotation plus extension, resistance increased ipsi- and contralaterally--no matter which side the head was turned--in three infants. A further three reacted with resistance surges only contralateral to the direction of rotation, and one only ipsilateral. Double contralateral associated with only one-directional ipsilateral rise was observed twice, and vice versa once.

CONCLUSION

The presented method enables crude quantification of postmortem dynamic resistance alterations in the vertebral arteries. How far such measurements reflect authentic circulatory conditions during life remains to be assessed.

Influence of the route of sensitization on local and systemic immune responses in a murine model of type I allergy

The pathophysiological and immunological characteristics of allergic immune responses are controlled by a variety of factors. We have studied the extent to which the route of sensitization influences allergen-specific IgE synthesis and local airway inflammation using a mouse model of allergic sensitization to the major birch pollen allergen Bet v 1. Sensitization of BALB/c mice with recombinant (r)Bet v 1 was performed using intraperitoneal (i.p.), subcutaneous (s.c.) or aerosol (a.s.) sensitization protocols. Mice were analysed for allergen-specific serum antibodies by ELISA and IgE-dependent basophil degranulation. Proliferative responses and cytokine production of splenocytes were measured upon Bet v 1 stimulation in vitro. Bronchoalveolar lavages were performed after airway challenge with aerosolized birch pollen extract for assessment of eosinophilic airway inflammation and local cytokine production in vivo. Highest allergen specific IgE levels and IgE-dependent basophil degranulation were achieved using the SC route. High IL-5 production by spleen and lung cells was associated with pronounced eosinophilia in bronchoalveolar lavages. After i.p. sensitization, despite giving the highest IgG levels, only low IgE levels, basophil degranulation and IL-5 production were seen. On the other hand, a.s. sensitization, resulting in the lowest systemic IgE and IL-5 levels, led to a comparably strong airway inflammation as the s.c. route. Our finding that the route of sensitization can result in a dissociation of local and systemic immune responses may contribute to a better understanding of the pathogenesis of allergic diseases and help to develop new treatment strategies.

Perinatal asphyxia in the rat has lifelong effects on morphology, cognitive functions, and behavior

Perinatal asphyxia (PA) is a major determinant of neurological morbidity and mortality in the neonatal period. Many studies have been investigating neurological deficits following PA, including seizures, cerebral palsy, mental retardation, as well as psychiatric deficits. Most research performed so far has been focusing on acute or subacute sequelae and has uncovered a variety of morphological, neurochemical, behavioral, and cognitive changes following PA. However, information on long-term sequelae of animals that underwent a period of PA is scanty. Perinatally asphyxiated rats at the end of their life span present with immunohistochemical and synaptic changes as well as changes in brain protein expression. Furthermore, deficits in cognitive function tested in the Morris water maze and changes in social behavior were described. In this review, we are summarizing and discussing reported effects of global PA on morphology, cognitive functions, and behavior in rats at the end of their life span.

Evaluation of an amikacin loading dose for nosocomial infections in very low birthweight infants

AIM

To develop a simplified amikacin dosage regimen for nosocomial infections in preterm infants including a loading dose in order to achieve therapeutic Maximum Serum Concentrations early in the course of therapy.

METHODS

Open, non-comparative study during November 2000 to April 2001. The modified amikacin dosing and monitoring protocol included a loading dose of 10 mg/kg in the first week of life, followed by a maintenance regimen of 7.5 mg/kg every 24 h. After the first week of life the corresponding doses were 17 mg/kg (loading) and 15 mg/kg (maintenance). A peak level was measured 30 min after the second dose, a trough level immediately before the third dose.

RESULTS

Twenty-five very low birthweight infants (median birthweight 739 g, median gestational age 25 wk) who had 34 episodes of amikacin treatment were included in the analysis. Median amikacin peak and trough values were 37.1 micromol/l and 6.3 micromol/l, respectively. Twenty-nine of all peak levels (85%) and 30 of all trough levels (88%) were within the targeted range of >35 micromol/l and <8.5 micromol/l, respectively. All patients with elevated trough levels were of extremely low birthweight and were born in the 24th week of gestation. Hearing evaluations were performed in 17 of 19 surviving infants at discharge home, all of which gave normal results.

CONCLUSION

The new amikacin dosing protocol yielded targeted peak and trough concentrations in a high percentage of very low birthweight infants with nosocomial infection after the first week of life. Our simplified dosage regimen achieved acceptable serum concentrations in all birthweight and gestational age groups, with the exception of extremely low birthweight infants weighing less than 700 g and/or with a gestational age of 24 wk or less. Only limited information can be gained from our data regarding the use of amikacin during the first week of life.

Heparinase-Modified Thrombelastography in Term and Preterm Neonates

Thrombelastography (TEG) appears to be a promising test to assess coagulation in infants and children. TEG enables a rapid assessment of hemostatic function with only 300 microL of whole blood and provides information about plasmatic coagulation, platelet function, and fibrinolysis. In this study, we used TEG to assess the coagulation system of preterm and term neonates to determine the effects of their deficient coagulation factor levels on global hemostatic function. Heparinase-modified TEG, platelet and red blood cell count, plasma fibrinogen, and prothrombin time were assessed in four groups of clinically stable infants: severely preterm (gestational age [GA], 27-31 wk), moderately preterm (GA, 32-36 wk), term (GA, 36-40 wk), and former preterm (corrected GA, 34-40 wk). Healthy adult volunteers served as a control group. When compared with the adult group, thromboelastography revealed no defects in coagulation from groups of clinically stable infants, documenting the functional integrity of coagulation despite, in part, decreased conventional coagulation variables. Because clinically stable preterm and term infants show a relatively small incidence of bleeding, despite prolonged conventional coagulation tests, TEG may better reflect the hemostatic potential of these patients compared with conventional coagulation tests.

IMPLICATIONS

This study assessed the coagulation of preterm and term infants by thrombelastography and found functional integrity of coagulation despite, in part, decreased conventional coagulation variables.

Preterm male infants need more initial respiratory support than female infants

Female infants have a significantly greater chance of surviving than male infants at similar birthweights and gestational ages, and have an advantage over males for a better outcome with less morbidity.

CONCLUSION

The exact mechanisms responsible for the gender differences, with a better chance of survival of female infants, remain to be determined. The paper by Elsmén et al. provides an important contribution to this most important area of clinical research.

Brain abscesses after Serratia marcescens infection on a neonatal intensive care unit: differences on serial imaging

Serratia are known to be a possible cause of severe cerebral infections in neonates. We describe imaging of three premature infants infected with Serratia marcescens. Born in the 31( st), 25( th) and 28( th) weeks of gestation, they presented with signs of septicaemia on postnatal days 9, 24 and 32. Initial sonography showed cysts in the first child, two areas with anechoic centre and echogenic rim in the second, and several echogenic areas in the third. Lesions were seen on CT, of low density in two cases and minimally increased density in the third. MRI in the first patient showed cysts with incomplete contrast enhancement of the lesions, while patient 2 showed five ring-enhancing fluid-containing lesions with thick walls. In the third patient two abscesses with contrast enhancement and several high-signal spots were seen. We discuss the pathophysiology of the lesions and the impact of the various imaging methods.

Reference values for amplitude-integrated electroencephalographic activity in preterm infants younger than 30 weeks' gestational age

OBJECTIVE

To prospectively investigate the development of amplitude-integrated electroencephalographic (aEEG) activity during the first 2 weeks of life in neurologically normal and clinically stable preterm infants <30 weeks' gestational age (GA).

PATIENTS AND METHODS

Infants with a GA of <30 weeks admitted to the neonatal intensive care unit of the Vienna University Children's Hospital (Vienna, Austria) were studied prospectively by using aEEG and cranial ultrasound. Clinically stable infants without clinical or sonographic evidence of neurologic abnormalities were eligible for inclusion in the reference group. The distribution of 3 background aEEG activity patterns (discontinuous low-voltage, discontinuous high-voltage, and continuous), presence of sleep-wake cycles, and number of bursts per hour in the reference group were determined by visual analysis.

RESULTS

Seventy-five infants (median GA: 27 weeks; range: 23-29 weeks) were eligible for inclusion in the reference group and had aEEG recordings during the first 2 weeks of life available. Analysis of aEEG background activity showed that with higher GA the relative amount of continuous activity increased while discontinuous patterns decreased. The number of bursts per hour decreased with increasing GA. Cyclical changes in aEEG background activity resembling early sleep-wake cycles were observed in all infants.

CONCLUSIONS

Normal values for aEEG background activity were determined in preterm infants <30 weeks' GA. Clinically stable and neurologically normal preterm infants exhibit at least 2 different patterns of aEEG activity. There is a correlation between the GA and the relative duration of continuous aEEG activity.

Patient with partial trisomy 9q and learning disability but no pyloric stenosis

Partial trisomy of the long arm of chromosome 9 represents a very rare and heterogeneous group of chromosomal aberrations. Associated clinical features include learning disability and pyloric stenosis. We present the first patient to be reported with a duplication of the chromosome region 9q22.1-->q33. The patient (female, age 17 years) presented with growth retardation, microcephaly, facial dysmorphia, oesophageal atresia, aortic stenosis, ventricular septal defect, atrial septal defect II, hypothyroidism, and learning disability, but no pyloric stenosis. A review of all cases of partial trisomy 9q reported in the literature demonstrates that learning disability is a characteristic feature of this group of chromosomal aberrations. However, there are cases of duplications of the same chromosome 9 material, with and without pyloric stenosis. This study provides new information for future genetic counselling, especially in cases of prenatal diagnosis of partial trisomy 9q.

Pain and stress management in the Neonatal Intensive Care Unit — A national survey in Austria

Neonates are sensitive to pain and vulnerable to both its short-term and long-term effects. Management of analgesia is thought to be hampered by lack of awareness that newborns are capable of experiencing pain and by fears about adverse effects associated with analgesics. The purpose of this study was to assess current medical practice in preventive analgesia and sedation in the neonate throughout Austria. This report details the results of a survey in 28 neonatal intensive care units (NICUs) in Austria. Data collection took place from October to December 2001. All NICUs reported the capability of newborns to experience and express pain and nearly all stated the possibility of pain affecting morbidity. Validated scores for pain assessment were used by 11% of NICUs, standardized protocols for analgesia existed in 75%, and 100% practiced non-pharmacological treatment strategies. The use of preventive measures in routinely performed painful procedures ranged from 8% to 96%. For example, only 8% of NICUs prevent distress and pain prior to umbilical vessel catheterization, 29% prior to subcutaneous injections and 46% prior to heel lancing. Nearly all NICUs apply analgesia before lumbar puncture and thoracic-drain placement, and all use analgesic and/or sedative medication in elective intubation.

CONCLUSION

There is widespread awareness among neonatologists of the importance and effects of distress caused by pain in newborns. However, the necessity of providing sufficient analgesia is underestimated. Further information on the safety of analgesic drugs in neonatology is imperative.

Magnetic resonance imaging in foetuses with bilateral moderate ventriculomegaly and suspected anomaly of the corpus callosum on ultrasound scan

OBJECTIVE

The diagnosis of anomalies of the corpus callosum (ACC) in foetuses with bilateral moderate ventriculomegaly (BMV) is difficult by means of ultrasound scan. The aim of this study was to examine the value of the additional investigation with magnetic resonance imaging (MRI) in foetuses with BMV and suspected ACC on ultrasound scan. Pathogenesis and clinical presentation of BMV and ACC are discussed.

METHODS

41 foetuses with central nervous system (CNS) anomalies on ultrasound scan were assessed by ultrasonography and MRI from 1999 to 2001. Eight of these 41 foetuses presented with BMV and suspected ACC on ultrasound scan and were prospectively included in the study. Foetal investigations with sonography and MRI were analysed with regard to diagnostic confidence; results were correlated with post partum findings. Six of these 41 foetuses presented with BMV without suspected ACC on ultrasound scan and were retrospectively analysed.

RESULTS

Ultrasonography suspected ACC in 8 foetuses with BMV. MRI confirmed the presence of ACC in 4 of these 8 cases. MRI additionally showed ACC in two of the six retrospectively analysed foetuses with BMV without suspected ACC on ultrasound scan. Prenatal MRI diagnosis was confirmed after delivery in all cases.

CONCLUSION

MRI is more sensitive than ultrasonography in the evaluation of ACC in foetuses with BMV. For prenatal screening ultrasound still remains the investigation of choice.