Age-matched Reference Values Research Articles

Abstract 59: New findings implicated in Coronary calcification in Chronic phase Kawasaki disease

Background: Kawasaki disease (KD) is a systemic vasculitis prevalent in infants and sometimes complicates coronary artery lesions (CALs). It has been well known that CALs gradually develop endothelial dysfunction, post-inflammatory arteriosclerotic changes, and finally coronary calcification. It has been also reported, recently, that vascular calcification is an active cell-driven process characterized by osteogenic differentiation of vascular smooth muscle cells, relating to the chronic inflammation and oxidative stress. In this study, in KD, we evaluated the possible implication of significant calcification prevalent in CALs to the long-term prognosis. Methods: We included 42 patients with a history of KD (age:18.3±6.7 year-old). The breakdown was 17 patients without CALs and 25 with CALs; 12 without calcification and 13 with calcification on multi-detector computed tomography. We measured %FMD as an endothelial function marker and hs-CRPs as an inflammatory marker, serum hydroperoxide and urinary 8-OHdG as oxidative stress markers, and the bone mineral density (BMD). Patients in CALs(-) group took no medicine and those in CALs(+) group were under antiplatelet and/or anticoagulant therapy, particularly, those with calcification were additionally administrated statin or ARB. Results: Values of %FMD in CALs(+) group were significantly lower compared with those in CALs(-) (p<0.05), and values in those with calcification were still lower than those without calcification (p<0.05). Values of hs-CRPs in CALs(+) group were significantly lower than those in CALs (p<0.05). 8-OHdG values as oxidative stress marker in CALs(+) group were significantly lower than those in CALs(-) (p<0.05). The BMD in CALs(+) group tended to be lower compared with the age-matched reference values (88.9±7.0% of normal). Conclusions: In KD chronic stage, the decreased %FMD may be an essential condition to occur coronary calcification. Decreased BMD in patients with coronary calcification suggested the possible existence of the skeletal and the vascular system in KD, similar to the mechanism of common vascular calcification.

Lymphocytes subsets reference values in childhood.

Immunophenotyping of blood lymphocyte subsets and activation markers is a basic tool in the diagnostic process of primary immunodeficiency diseases, its use becoming more and more widespread as the knowledge about these illnesses increases. However, the availability of reliable reference values, which need to be age-matched for the pediatric population, is a pre-requisite for the reliable interpretation of immunophenotyping data. Aim of this study is to analyze the lymphocyte subsets and activation markers distribution in children aged 0-18 years referring to the University Hospital of Padova and to create age-matched reference values expressed by percentiles, thus providing a valuable guideline for the interpretation of the immunophenotype.

Evaluation of lymphocyte subpopulations in cord blood of Bulgarian newborns.

Umbilical cord blood (UCB) is a clinically useful source of hematopoietic stem and progenitor cells for treatment of a wide variety of malignant and non-malignant disorders. An important way to completing infor- mation on the quality and composition of units for transplantation is more extensive immunophenotyping of UCB. Moreover, phenotyping of lymphocyte subpopulations is essential for the diagnosis and follow-up of children with immunodeficiencies and other immune disorders and therefore, establishment of age-matched reference values of lymphocyte subsets is a necessity for each population. The aim of this study was to determine the normal range of T and B lymphocytes, and NK cells as well as the CD4 and CD8 subpopulations of T cells in cord blood collected from healthy term infants. The relative and absolute number distributions (median, 5th and 95th percentile) of lymphocyte subsets in cord blood samples from 72 healthy newborns were examined by multi-colour flow cytometry with a view to obtaining reference values for Bulgarian neonates at birth. Mean percentages of lymphocyte subpopulations were: CD3 (62.27 ± 9.64), CD19 (17.47 ± 5.46), CD3- CD16/CD56+ (17.27 ± 8.4). Our results show the prevalence of helper-inducer CD3+CD4+ (44.88-8.21) compared to the suppressor-cytotoxic CD3+CD8+ (16.65 ± 4.54) T-cell subpopulation, which determines the positive CD4/CD8 ratio (2.86 ± 0.82; 1.4-4.8). Also, the absolute numbers of studied populations varied widely due to differences of the absolute number of lymphocytes in the samples. This study on distribution of lymphocyte subpopulations in UCB helps to enhance our knowledge about cell phenotypes in cord blood and improve characterization of products for cellular therapy, as well as contributes to the correct interpretation of laboratory results for infants with possible immune disorders. Our data can be used as normal intervals for lymphocyte subsets in Bulgarian neonates.

Skeletal muscle abnormalities and exercise capacity in adults with a Fontan circulation

ObjectivesThe peripheral muscle pump is key in promoting cardiac filling during exercise, especially in subjects who lack a subpulmonary ventricle (the Fontan circulation). A muscle-wasting syndrome exists in acquired heart...

Autonomic dysfunction in ICU-acquired weakness: a prospective observational pilot study

Intensive care unit-acquired weakness (ICU-AW) is a frequent complication of critical illness. It is unknown if patients with ICU-AW also have autonomic dysfunction, another frequent neurological complication of critical illness. We hypothesized that patients who develop ICU-AW also develop autonomic dysfunction. Furthermore, we hypothesized that patients with ICU-AW are more prone to develop autonomic dysfunction compared to patients without ICU-AW. This was an observational cohort study of patients newly admitted to the ICU. Autonomic dysfunction was measured daily using heart rate variability (HRV) to a maximum of 15 days after admission. ICU-AW was diagnosed using the Medical Research Council score. Abnormal HRV was defined using age-matched reference values. The association between ICU-AW and HRV was analyzed using linear mixed effects models. We included 83 patients, 15 (18 %) of whom were diagnosed with ICU-AW. Of 279 HRV measurements, 204 could be analyzed. Abnormal HRV was found in all critically ill patients irrespective of the presence of ICU-AW (ICU-AW 100 % (IQR 71-100) vs. no ICU-AW 100 % (IQR 40-100); p = 0.40). Mechanical ventilation, sedation, norepinephrine, heart rate, and HRV artifacts were identified as confounders for HRV. ICU-AW was not associated with HRV. Abnormal HRV is frequent in critically ill patients, both with and without ICU-AW. It is unlikely that patients with ICU-AW are more prone to develop abnormal HRV. However, we found that abnormal HRV may not be an accurate indicator of autonomic dysfunction because of confounders.

Common variable immunodeficiency and idiopathic primary hypogammaglobulinemia: two different conditions within the same disease spectrum

Patients with hypogammaglobulinemia who do not fulfill all the classical diagnostic criteria for common variable immunodeficiency (reduction of two immunoglobulin isotypes and a reduced response to vaccination) constitute a diagnostic and therapeutic dilemma, because information concerning the clinical and immunological characteristics of these patients with idiopathic primary hypogammaglobulinemia is not available. In 44 common variable immunodeficiency and 21 idiopathic primary hypogammaglobulinemia patients we determined the clinical phenotypes and performed flow cytometric immunophenotyping to assess the pathophysiological B-cell patterns and memory B-cell subset counts. Age-matched B-cell subset reference values of 130 healthy donors were generated. Severe pneumonia and bronchiectasis occurred at similar frequencies in idiopathic primary hypogammaglobulinemia and common variable immunodeficiency. Although IgG levels were only moderately reduced compared to common variable immunodeficiency, 12 of 21 idiopathic primary hypogammaglobulinemia patients required immunoglobulin replacement. Non-infectious disease-related clinical phenotypes (autoimmune cytopenia, polyclonal lymphocytic proliferation and persistent unexplained enteropathy) were exclusively observed in common variable immunodeficiency and were associated with early peripheral B-cell maturation defects or B-cell survival defects. T-cell dependent memory B-cell formation was more severely affected in common variable immunodeficiency. Furthermore, 14 of 21 idiopathic primary hypogammaglobulinemia patients showed normal peripheral B-cell subset counts, suggestive for a plasma cell defect. In conclusion, idiopathic primary hypogammaglobulinemia patients who do not fulfill all diagnostic criteria of common variable immunodeficiency have moderately decreased immunoglobulin levels and often a normal peripheral B-cell subset distribution, but still suffer from serious infectious complications.

AB1459-HPR Despite low disease activity patients with poly- and dermatomyositis perceive activity limitation, reduced grip force and quality of life longitudinally

BackgroundPolymyositis (PM) and dermatomyositis (DM) are idiopathic inflammatory myopathies with muscle weakness and reduced muscle endurance. The impairments lead to activity limitation, participation restriction and reduced quality of life.ObjectivesTo investigate...

Challenges of Newborn Severe Combined Immunodeficiency Screening Among Premature Infants

Newborn screening for severe combined immunodeficiency (SCID) is currently being performed in many states. It is important to address diagnostic challenges while outcomes are emerging from the first several years of screening. We present the case of a premature infant whose initial newborn screen was strongly positive for SCID. Subsequent lymphocyte subset analysis by flow cytometry was difficult to interpret due to the lack of age-matched reference values, a history of prenatal corticosteroid administration, and the possibility of maternal or posttransfusion engraftment. A repeat newborn screen for SCID ultimately revealed a normal result, confirming the initial newborn screen as a false positive. This case report reveals several of the diagnostic challenges unique to newborn SCID screening in premature infants and highlights the potential for states to address the feasibility of a standard protocol in this population.

Impact of Treatment with Tyrosine Kinase Inhibitors (TKIs) On Blood Levels of Growth Hormone-Related Parameters, Testosterone, and Inhibin B in Juvenile Rats and Pediatric Patients with Chronic Myeloid Leukemia (CML)

AbstractAbstract 3752 Background:Long-term treatment with TKIs is of special concern in pediatric patients (pts) with CML as these drugs -beside their specific inhibition of the BCR-ABL oncogene- exert multiple off-target effects. Among these the precise influence on the longitudinal growth and the reproductive endocrine system –being of particular interest in growing organisms– is still not clarified. We therefore investigated in blood serum the growth hormone-related parameter insulin-like growth factor-binding protein 3 (IGFBP3) as well as testosterone (Testo) and inhibin B (InB) in an animal model of juvenile rats and pediatric pts with CML chronically exposed to TKIs. Methods:In 23 pts (13 males; age: 7.8 – 18.9 years, median: 12.8 yrs) with CML in chronic phase being enrolled into the pediatric trial CML-Paed II (ClinicalTrials.gov identifier NCT00445822) blood serum was collected at three months intervals in the morning and sent in for central analysis at the study reference laboratory. Pts were receiving standardized imatinib (IMA) treatment (260–300 mg/sqm) for 3–58 months (median: 18 months).In addition, in an animal model 4 week-old male Wistar rats were cohorted (controls, groups A, B, C; each n=10 animals) and exposed over 10 weeks to either IMA, dasatinib (DASA), or bosutinib (BOSU) at varying concentrations via the drinking water (controls: water only; IMA: A) 1mM, B) 2 mM, C) 2 mM at three days per week [Monday–Wednesday]; DASA and BOSU, respectively: A) 50 μM, B) 100 μM, C) 100 μM at 3 days per week). Blood was collected at prepubertal age (6 weeks old), pubertal age (8 weeks old), and at adult age (14 weeks old), respectively. Serum levels of IGFBP3 (in all pts), Testo, and InB (in males) were measured by commercially available ELISA in humans and rats. Results:IGFBP3 levels were determined in 21 pediatric pts and were found still within the normal, however, uniformly in the very low range (Z-score: −1 to −2) compared to age-matched reference values (p<0.001). In male pts serum levels of Testo (n=13) and InB (n=11) were within normal age-related reference ranges according to Tanner puberty score. No clear pattern of rising or falling Testo or InB levels during TKI treatment could be observed.In rats, compared to controls serum IGFBP3 levels (range: 19–40 ng/ml) were highly significantly lowered (range: 7–16 ng/ml; p-values <0.01 - <0.001) for all TKIs tested, at all concentrations applied, and at all ages when investigated. Also longitudinal bone growth retardation occurred in these animals as described elsewhere (Tauer JT et al. 2011 ASH Abstract #1597; Tauer JT et al. 2012 EHA Abstract #1256). Keeping in mind that the number of animals tested at each age group was rather small, Testo levels under IMA exposure tended to be non-significantly lowered at postpubertal age compared to controls while no significant differences were found under DASA and BOSU exposure. Also for all TKIs tested in rats, InB serum levels did not significantly differ compared to controls. Conclusion:Impairment of longitudinal growth in pediatric pts on TKIs has been described in several reports as well as in animal models (Suttorp M, et al 2012). Besides direct off-target effects on differentiation and metabolic activity of bone resorbing and forming cells (osteoclasts and osteoblasts) involved in bone remodelling, TKI treatment probably results also in lowered growth hormone secretion. Based on these first data from a small cohort of pts it seems reasonable to monitor growth hormone-related parameters like IGFBP3 regularly in pediatric pts with CML. Our data do not confirm a general inhibitory effect on Testo and InB blood levels neither in pts nor in rats. Thus, testicular toxicity due to TKI seems unlikely, however, clinically individual cases with impaired gonadal function and/or late-onset puberty remain to be investigated. Acknowledgment:This investigation was supported by grants DFG SU122–3/1, Peter Escher Foundation (Leipzig), and Foerderkreis Sonnenstrahl e.V. (Dresden). Disclosures:No relevant conflicts of interest to declare.

Paediatric Reference Values for the Peripheral T cell Compartment

Immunophenotyping of blood lymphocyte subpopulations is an important tool in the diagnosis of immunological and haematological diseases. Paediatric age-matched reference values have been determined for the major lymphocyte populations, but reliable reference values for the more recently described T lymphocyte subpopulations, like different types of memory T lymphocytes, recent thymic emigrants, regulatory T cells and CXCR5(+) helper T lymphocytes, are not sufficiently available yet. We determined reference values for the absolute and relative sizes of T lymphocyte subpopulations in healthy children using the lysed whole blood method, which is most often used in diagnostic procedures. When the absolute numbers of some or all T lymphocyte subpopulations fall outside these reference ranges, this may indicate disease. The reference values show the course of T lymphocyte development in healthy children. Absolute T lymphocyte numbers increase 1.4-fold during the first months of life, and after 9-15 months, they decrease threefold to adult values; this is mainly caused by the expansion of recent thymic emigrants and naive cells. Helper and cytotoxic T lymphocytes show the same pattern. Regulatory T cells increase in the first 5 months of life and then gradually decrease to adult values, although the absolute numbers remain small. The relative number of CXCR5(+) cells within the CD4(+) CD45RO(+) T lymphocytes increases during the first 6 months of life and then remains more or less stable around 20%.

TACI Expression is Low Both in Human and Mouse Newborns

To the Editor: We read with high interest the recent article titled ‘Age-matched reference values for B-cell subpopulation and CVID classifications in children’ by Schatorjé and colleagues [1]. The authors studied the expression of TACI and BAFF-R in both newborn and infant age groups starting from cord blood. In this sudy, they reported that while the percentage of BAFF-R+ B cells do not change during the first year of life, TACI+ B cell percentage showed an age-dependent increase. In accordance with these human studies by Schatorjé and colleagues, we found that murine newborn B cells also had low percentage of TACI+ B cells while BAFF-R and BCMA expressing B cell percentages were comparable to those of adult mice [2]. We have analyzed the expression and function of BAFF system molecules in newborn mice because newborns of mice and humans share several aspects of their hematopoietic development and function. For example both human and mice newborns do not respond to T cell-independent type 2 (TI-2) antigens such as bacterial polysaccharide vaccines [3]. In addition to low TACI expression in newborn mice [2], we also showed that low B cell TACI expression correlated with impaired immunoglobulin secretion, plasma cell generation and proliferation of B cells in response to either BAFF or APRIL stimulation in this age group. These results provided a rational explanation for the weak immunogenicity of TI-2 antigens in newborns because we could render the TI-2 antigen NP-Ficoll immunogenic in newborns by using the adjuvant CpG that increases TACI expression [4]. Finally as with CVID patients with TACI mutations, we found that BAFF levels were increased in newborn mice and in TACI knock-out mice, further supporting a role for TACI in modulating BAFF expression. Thus, the demonstration of low TACI expression in human infants reported by Schatorjé and colleagues signifies yet another similarity between mice and human immune system and underscores the relevance of studies on the BAFF system components conducted in mice as organismal models.

B-Lymphocyte Reconstitution after Repeated Rituximab Treatment in a Child with Steroid-Dependent Autoimmune Hemolytic Anemia

We report the detailed long-term reconstitution of B-lymphocyte subpopulations, immunoglobulins, and specific antibody production after two courses of rituximab in a young, previously healthy girl with steroid-dependent autoimmune hemolytic anemia. B-lymphocyte subpopulations were surprisingly normal directly after reconstitution. However, there was a slower reconstitution after the second rituximab course, especially of non-switched and switched memory B-lymphocytes, and a temporary decline in IgM below age-matched reference values.

Bone Metabolism in Cholestatic Children Before and After Living-Related Liver Transplantation—a Long-Term Prospective Study

Bone disorders are common in children with end-stage liver diseases, especially those associated with cholestasis. Abnormal hepatocyte function, disordered vitamin D metabolism and calcium-phosphorous homeostasis, malnutrition, and immunosuppressive treatment are potential risk factors of bone tissue pathology before and after transplantation.The aim of the study was to analyze the long-term effect of successful living-related liver transplantation (LRLTx) on skeletal status and bone metabolism in cholestatic children.Eighteen cholestatic children (1.4±0.5yr old; 12 females [F]/6 males [M]) qualified for LRLTx were analyzed; 16 (5F/11M) of them participated in long-term observation (V4). Serum levels of osteocalcin (OC), procollagen type 1 N-terminal propeptide (P1NP), cross-linked telopeptide of type 1 collagen (CTx), insulin-like growth factor I (IGF-I), IGF-I binding protein 3 (IGFBP-3), parathyroid hormone (PTH), 25-hydroxyvitamin D (25(OH)D), and 1,25-dihydroxyvitamin D (1,25(OH)2D) were assayed before (V0) and 6mo (V1), 12mo (V2), 18mo (V3), and 4.4yr (V4) after LRLTx. Total body bone mineral content (TBBMC) and total body bone mineral density (TBBMD) were measured by dual-energy X-ray absorptiometry (DXA) at the same pattern.Before LRLTx, the OC, P1NP, CTx, IGF-I, and IGFBP-3 levels as well as TBBMC and TBBMD were decreased compared with age-matched control group. The mean serum levels of 25(OH)D and 1,25(OH)2D were within reference ranges from V0 to V4. After LRLTx, the OC, P1NP, CTx, IGF-I, and IGFBP-3 as well as TBBMC and TBBMD reached the age-matched reference values. At V4, the level of P1NP decreased below and the PTH increased above the reference range that coincided with reduced Z-scores of both TBBMC (−1.11±1.24) and TBBMD (−1.00±1.19). P1NP and CTx, both measured at V3, correlated with IGF-I at V2 (R=0.86, p=0.014 and R=0.78, p=0.021, respectively) and PTH at V3 for P1NP and V1 for CTx (R=0.64, p=0.048 and R=0.54, p=0.038, respectively). The TBBMC changes between V0 and V4 correlated with IGF-I (R=0.68, p=0.015) and 1,25(OH)2D (R=0.54, p=0.025), both assayed at V1. The change of TBBMC Z-scores between V0 and V4 correlated with P1NP at V1 (R=0.69, p=0.002). The TBBMD changes between V0 and V4 correlated with CTx at V1 (R=0.54, p=0.027) and P1NP change between V0 and V1 (R=0.51, p=0.038).In short-term observation, successful LRLTx led to bone metabolism normalization triggered by probable anabolic action of IGF-I and PTH and manifested by TBBMC and TBBMD increases. In long-term horizon, moderately impaired DXA assessed bone status coincided with disturbances in bone metabolism. Bone metabolism markers, especially P1NP and CTx, appeared to be good predictors of changes in bone status evaluated by DXA.

Age‐matched Reference Values for B‐lymphocyte Subpopulations and CVID Classifications in Children

Age-matched reference values are generally presented with 5th and 95th percentiles as 'normal' reference range. However, they are mostly determined in relatively small groups, which renders this presentation inaccurate. We determined reference values for B-lymphocyte subpopulations in healthy children with the statistical method of tolerance intervals that deals far better with the relatively small numbers tested, and compared these to the cut-off values used in the currently used EUROclass classification for common variable immunodeficiency disorders (CVID) in children. CVID is a heterogeneous group of primary immunodeficiency diseases characterized by low serum immunoglobulin levels and inadequate response to vaccination. Disease-modifying heterozygous amino acid substitutions in TACI are found in around ±10% of CVID patients. Interestingly, we found that age is the primary determinant of TACI-expression on B-lymphocytes, independent of switched memory B-lymphocyte numbers. Immunophenotyping of B-lymphocyte subpopulations is increasingly used to classify patients with CVID into subgroups with different clinical prognosis according to the composition of their B-lymphocyte compartment. These classifications were mainly developed with data obtained in adults. Because of the maturing paediatric immune system, they may not be equally applicable in children: our and other age-matched reference values show great changes in the composition of the B-lymphocyte compartment during development. Although the greatest changes in B-lymphocyte subpopulations occur below the age of 2 years, when the diagnosis of CVID cannot yet be made, it is likely that a classification developed in adults cannot be used to classify the prognosis of children.

Assessment of plasmatic immunoglobulin G, A and M levels in septic shock patients

Polyvalent immunoglobulin (Ig) therapy has been tested as adjunctive treatment in sepsis and septic shock, but its efficacy is still a matter of debate. This has been explained because clinical trials were mostly performed on small numbers of patients. Moreover, the endogenous level of circulating Ig in patients was never taken into account. In this study, plasmatic Ig classes and protein concentrations were measured at Days (D) 1–2, D3–4 and D5–7 in 62 septic shock patients. At D1–2 as well as at D3–4, patients presented with a significant reduction of plasmatic IgG concentrations. Indeed, at D1–2, 61% of the patients had IgG level below the lowest limit of our age-matched reference values. Plasmatic IgM levels were decreased as well in comparison with reference values from the lab whereas IgA concentrations were not modified. Circulating IgG and IgM concentrations tends to increase overtime. Indeed, at D5–7, most patients (61%) had IgG and IgM levels within the range of normal values. These alterations did not appear to be associated with increased mortality, morbidity or severity after septic shock. However, at D1–2 and D3–4, decreased circulating Ig level was significantly correlated with reduced plasmatic protein concentrations. Overall, our results suggest that an apparent hypogammaglobulinemia is present at D1–2 and D3–4 in septic shock patients, which seems to be related with reduced circulating protein concentration after septic shock. These results need to be confirmed in a larger cohort of patients.

Decreased Response After Conjugated Meningococcal Serogroup C Vaccination in Children With Down Syndrome

To the Editors: Meningococcal serogroup C conjugate (MenC) vaccine is a part of the Dutch immunization program since 2002. In the MenC vaccine, the polysaccharide antigen is linked to the protein carrier tetanus toxoid with the aim to achieve an adequate immune response at an early age, which would not be possible with a pure polysaccharide vaccine. The immune response to a conjugate vaccine is characterized by T-cell-dependent isotype switching to IgG-antibodies, especially IgG1, and induction of immunologic memory. In a catch-up campaign, all children (1–18 years) were offered a single dose of MenC in the Netherlands in 2002. Blood samples were obtained from 19 children (mean age, 10.6; range, 5.3–17.4 years) with Down syndrome (DS) during regular hospital visits 3 months (n = 7; mean, 13 weeks; range, 39–107 days), or around 1 year (n = 12; mean, 50 weeks; range, 275–447 days), after this single dose of MenC vaccination. MenC polysaccharide (PS)-specific IgG, IgM, and IgA concentrations were measured using an antibody capture enzyme-linked immunosorbent assay.1 Results were compared with reference values of healthy adults from the same laboratory, 1 month (n = 12) and 1 year (n = 11) after single MenC vaccination. At 3 months postvaccination, geometric mean MenC/PS-specific IgG, IgA, and IgM serum values were 5.5 (range, 1.4–41), 0.71 (0.03–11), and 0.61 (0.10–7.5) μg/mL, compared with 26 (5.6–59), 5.6 (2.1–11), and 5.2 (1.7–35) μg/mL in healthy controls (P = 0.014, 0.028, and 0.12 were assessed by Mann-Whitney U test, respectively). One year after vaccination, geometric mean MenC/PS-specific IgG, IgA, and IgM values were 2.7 (0.78–15), 0.19 (0.02–1.2), and 0.28 (0.15–0.76) μg/mL, whereas reference values were 4.5 (0.68–19), 0.79 (0.13–3.8), and 0.71 (0.16–5.1) μg/mL (P = 0.204, 0.019, <0.001 were assessed by Mann-Whitney U test, respectively). The 19 children with DS did reach protective, but lower levels of vaccine protection after a single MenC vaccination, in comparison with healthy adults, despite the fact that 9 of them showed hypergammaglobulinemia according to age-matched reference values.2 Assaying specific antibody production against well-defined antigens can be used as a model to assess T-cell-dependent (antiprotein) and T-cell-independent (antipolysaccharide) antibody responses; conjugated protein-polysaccharide vaccines like MenC show aspects of both the types of responses. Impaired specific antibody responses to unconjugated pneumococcal polysaccharide have been described in DS, suggesting a B-lymphocyte problem.3 Impaired responses to influenza, hepatitis B, and tetanus (protein prototype) have been described as well, suggesting an additional T-lymphocyte or T-B interaction problem.3 Not unexpectedly, therefore, our data show that protein conjugation does not fully overcome the impaired antibody production to this polysaccharide antigen in DS. Of course, decreased antibody production upon vaccination may have clinical implications as well. Children with DS have frequent respiratory infections, but an increased frequency of meningococcal disease has not been described in recent surveys, either in the pre-4 or post-MenC5 era, but specific attention was not given to this subject. Thus, it is as yet unclear whether children with DS are at greater risk of meningococcal disease, or whether they would benefit from an additional dose of conjugated meningococcal vaccination. Further studies are needed to elucidate this. Maaike A. Kusters, MD Department of Pediatrics Jeroen Bosch Hospital Els C. M. Jol-Van Der Zijde, BASC Department of Pediatrics Leiden University Medical Center Leiden, The Netherlands Rianne H. J. M. Gijsbers, MSc Esther de Vries, MD, PhD Department of Pediatrics Jeroen Bosch Hospital ′s-Hertogenbosch, The Netherlands

Evaluation of lumbosacral nerve root conduction in chickens by electrophysiological testing including high-resolution spinal magnetic stimulation

The value of avian models in peripheral nerve research recently became substantiated by the immunobiological similarity of avian inflammatory demyelinating polyradiculoneuropathy to human Guillain–Barré syndrome providing an alternative animal model for experimental autoimmune neuritis. As electrophysiologic evaluation of nerve roots is essential part of the diagnosis of polyradiculoneuropathies in humans, it would be favourable to have similar research methods available for juvenile chickens. Hence, this study was performed (1) to establish a tool-set that allows for reproducible evaluation of the tibial/sciatic nerve and its nerve roots, (2) to achieve age-matched reference values, and (3) to trace the kinetics of peripheral nerve maturation within chickens.Nine chickens underwent serial electrodiagnostic examinations between the age of 6 and 15 weeks. Several methods of sensory and motor nerve fiber stimulation of the tibial/sciatic nerve were tested and modified or established. Ultimately, scalp-recorded somatosensory evoked potentials, compound muscle action potentials elicited by tibial/sciatic nerve electrical as well as spinal magnetic stimulation and motor nerve conduction velocity were available for tibial/sciatic nerve and nerve root evaluation in chickens. Base values were obtained for all investigations and parameters. Results indicated that the maturation of the nerve fibers is incomplete up to the age of 15 weeks.The methods tested here provide an excellent tool-set for quantitative tibial/sciatic nerve and nerve root assessment in avian polyradiculoneuropathies, especially within the scope of longitudinal monitoring of the disease course.

Plasma and urine amino acid pattern in preterm infants on enteral nutrition: impact of gestational age

Plasma and urine amino acids were determined by ion-exchange chromatography in 80 healthy preterm infants divided into three groups: (1) 23 0/7-28 0/7, (2) 28 1/7-32 0/7 and (3) 32 1/7-35 0/7 weeks of gestation. Samples were collected from days 5 to 57 of life, when infants were exclusively orally fed. Infants with evidence of underlying diseases were excluded. Concentrations of most plasma amino acids increased with gestational and maturational age; urinary excretion followed an opposite course. Few amino acids depended on postnatal age. Plasma amino acids did not correlate inversely to their counterparts in urine indicating that plasma amino acids do not simply reflect kidney function. Some amino acids in blood and urine were linked to nutrient intake and body weight. Our data clearly indicate the heterogeneity of the preterm cohort; therefore, gestational age-matched reference values have to be used for diagnostic purposes in preterm infants.

Effect of age and height on trunk sway during stance and gait

The aim of the studies reported here was to quantify changes in balance control for stance and gait tasks with age and to pinpoint possible advantages and difficulties in using these tasks and measures derived from them to identify pathological balance control in patients. Some 470 normal subjects in the age range 6 to 82 were examined for a battery of 14 stance and gait tasks. During the tasks, angular velocity transducers mounted at lumbar 1-3 measured pitch and roll angular velocities of the body. A combination of outcome measures from several tasks was used to create an overall balance control index. Three types of sensory analyses on pitch angle and velocity amplitudes for stance trials were used to quantify possible changes in the contributions of visual, somatosensory and vestibular inputs to balance control with age for 2-legged stance tasks. Correlation analysis on task variables was used to determine the relationship of subjects' age and height on outcome measures. Outcome measures showed a characteristic "L" or "U" shaped profile with a rapid decrease in values between 7 and 25 years of age, a plateau until 55 then a gradual increase with age after 55 years of age for most stance and gait tasks. The sensory analysis technique using differences between stance tests indicated that visual contributions to balance control continuously increased with age between the ages of 15 and 80, and vestibular and lower leg somatosensory contributions remain relatively constant with age. Sensory analysis calculated as commonly-used quotients of outcome measures revealed large variance across all ages, asymmetric distributions, and no clear trends in sensory contributions to stance with age. A third technique based on a discriminant function analysis using measures from model patient populations indicated that proprioceptive but not vestibular contributions first increased with age and then decreased after 55 years of age. Correlations of outcome measures with age and height indicated that both contributed equally to changes in outcome measures between the ages of 7 and 25, otherwise height had no effect. We conclude that both stance and gait tasks should be selected for identifying changes in balance control from that of healthy persons with a preference for gait tasks as these show less variation with age. Because of the large increases in variance in the elderly and those younger than 20 years, appropriate age-matched reference values should be employed to ascertain if trunk sway is out of normal ranges.

Feasibility of bioelectrical impedance analysis in children with a severe generalized cerebral palsy

Objective The need is strong for an accurate and easy-to-perform test to evaluate the nutritional state of children who have a severe generalized cerebral palsy, defined as a severe motor handicap and an intellectual disability. For that purpose, we determined the feasibility of bioelectrical impedance analysis (BIA) in these children and evaluated their nutritional state. Methods BIA recordings were done in 35 children who had a severe generalized cerebral palsy using a single-frequency BIA device. In addition, arm span and body weight were determined. Components of feasibility were whether the children tolerated the recording and felt comfortable and whether the recording could be performed in a reproducible way (prescribed body position and stable resistance and reactance values). All recordings were performed at specialized children’s daycare centers or schools. Results One child (3%) did not tolerate the recording, whereas the remaining 34 children (71%) felt comfortable. Most children (74%) could be placed in the prescribed position, but stability of resistance values was low. Stability of resistance values was positively influenced by older age, a quiet location for the recording, feeling comfortable, and a small number of people in the room. For 29 children, we were able to calculate values for total body water and fat-free mass. Compared with age-matched reference values, these values were significantly decreased in all age groups. Conclusions The present pilot study has demonstrated that BIA recording is a feasible nutritional assessment method in children who have severe generalized cerebral palsy. Because the test procedure was well tolerated by most children, its value for use in this specific population deserves further investigation.