Dynamical disentanglement in an analysis of oscillatory systems: an application to respiratory sinus arrhythmia.

We develop a technique for the multivariate data analysis of perturbed self-sustained oscillators. The approach is based on the reconstruction of the phase dynamics model from observations and on a subsequent exploration of this model. For the system, driven by several inputs, we suggest a dynamical disentanglement procedure, allowing us to reconstruct the variability of the system's output that is due to a particular observed input, or, alternatively, to reconstruct the variability which is caused by all the inputs except for the observed one. We focus on the application of the method to the vagal component of the heart rate variability caused by a respiratory influence. We develop an algorithm that extracts purely respiratory-related variability, using a respiratory trace and times of R-peaks in the electrocardiogram. The algorithm can be applied to other systems where the observed bivariate data can be represented as a point process and a slow continuous signal, e.g. for the analysis of neuronal spiking. This article is part of the theme issue 'Coupling functions: dynamical interaction mechanisms in the physical, biological and social sciences'.

Distinct signatures of B-cell homeostatic and activation-dependent chemokine receptors in the development and progression of extragastric MALT lymphomas.

Chemokine receptors mediate migration and activation of lymphocytes through binding of their ligands. Recent studies have revealed important contributions of chemokine receptors to the development, progression, and dissemination of haematopoietic neoplasms. Because the chemokine receptor expression profile in extragastric MALT lymphoma is unknown, we performed a comprehensive study on tissue samples of parotid glands, parotid glands affected by Sjögren syndrome, extragastric MALT lymphoma, and extranodal diffuse large B-cell lymphoma (eDLBCL) originating from MALT lymphoma (transformed MALT lymphoma). By investigating the expression of 19 chemokine receptors by real-time PCR using a semi-quantitative approach and of four chemokine receptors (CCR1, CCR5, CXCR6, and XCR1) by immunohistochemistry, we show that the chemokine receptor expression profiles of extragastric MALT lymphomas differ substantially from those of extranodal DBLCL, with lower expression of CCR1, CCR8, and CXCR3, and the absence of expression of CX3CR1 and XCR1 in eDLBCL. Expression of CCR6, CCR7, CXCR3, CXCR4, and CXCR5, responsible for B-cell homing to secondary lymphoid tissue, was detected in both B-cell malignancies. Expression of CCR4 was just detected in trisomy 3-positive MALT lymphoma cases. Comparing gastric with extragastric MALT lymphomas, up-regulation of CXCR1 and CXCR2 accompanied by down-regulation of CCR8 and CX3CR1 and loss of XCR1 expression in extragastric MALT lymphomas appear to be key determinants for the site of origin of MALT lymphomagenesis. Our results support a model of stepwise progression of extragastric MALT lymphoma from a non-neoplastic event to Sjögren syndrome, to MALT lymphoma, and finally to overt eDLBCL, guided by differentially expressed B-cell homeostatic and activation-dependent chemokine receptors and their ligands.

Prolonged asystole provoked by head-up tilt testing.

We describe a patient with a history of neurocardiogenic syncopes who had a positive headup tilt test that resulted in an lasting asystole lasting 34 seconds. However, the previously carried out Schellong test with a 30-min phase of standing showed a normal result. The patient showed typical orthostatic symptoms while tilted at the angle of 75 degrees. Shortly before asystole occurred, heart rate variability showed high frequency bands, indicating vagal stimulation. The pathophysiology of neurocardiogenic syncope (NCS) in context with heart rate variability is discussed. This patient was successfully treated with propranolol. This case shows the utility of a provocative head-up tilt test in establishing the diagnosis of NCS. If the Schellong test is normal, still further examination by tilt-table test is indispensable.

International variation in disease burden of rotavirus gastroenteritis in children with community- and nosocomially acquired infection.

BACKGROUND: The great impact of rotavirus disease on morbidity and medical health care costs in industrialized countries together with the withdrawal of the live oral rotavirus vaccine have made a reassessment of rotavirus gastroenteritis necessary. Such a reassessment should provide sufficient data for developing alternative disease prevention strategies and for allocating resources efficiently. OBJECTIVES: To compare characteristics and management of community- and nosocomially acquired rotavirus disease in Austria, Germany and Switzerland. PATIENTS AND METHODS: In a prospective, population-based, trinational (Austria, Germany, Switzerland), multicenter (9 cities, 10 hospitals and 30 pediatric practices) study, a total of 174 552 children months and 78 516 hospital days were evaluated. Participants were all children 4 years of age and younger, who either presented at one of the pediatric practices with community-acquired gastroenteritis, or who had acquired gastroenteritis nosocomially. From December, 1997, to May, 1998, prospective antigen testing was done by enzyme-linked immunosorbent assay, and serotyping was done by reverse transcription polymerase chain reaction. Disease severity was scored by the Vesikari severity scale. RESULTS: Rotavirus was detected in 29.5, 27 and 37.5% of children with community-acquired gastroenteritis and in 57, 69 and 49% of children with nosocomial gastroenteritis in Austria, Germany and Switzerland, respectively. Severity of community-acquired rotavirus gastroenteritis was more pronounced in Austria (median severity score, 11) than in Germany (median score, 9) or Switzerland (median score, 10). However, only 2% of Austrian and Swiss children compared with 12% of German children presented to their pediatricians more than four times. Nosocomially acquired rotavirus gastroenteritis was mildest in Austria but occurred within the shortest median duration of hospitalization (4 days vs. 5 and 7 in Germany and Switzerland, respectively). In a multivariant analysis age, family size, day care, breast-feeding and nationality were not predictive factors for enhanced risk to contract rotavirus infection. Alimentation was changed frequently; diet was used between 23 and 83%; special formulas were used between 10 and 57%. CONCLUSION: The cumulative experience from three European countries suggest that rotavirus is an important cause of diarrhea in Central Europe, but significant local differences clearly demonstrate the need for obtaining national data as a reliable basis for control and prevention of the disease.

[Effects of speech therapy with poetry on heart rate variability and well-being]. / Wirkungen der Therapeutischen Sprachgestaltung auf Herzfrequenz-Variabilität und Befinden.

BACKGROUND: Anthroposophical Therapeutic Speech uses poems and exercises which typically induce rhythmical breathing. Speaking influences respiration and thus directly heart rate variability (HRV), in particular via respiratory sinus arrhythmia which, together with the slower rhythms of HRV, may be regarded as an indicator of sympathovagal balance. In chronomedicine numerous frequency ratios between physiological rhythms, especially in trophotropic phases, have been established. Integer ratios occur frequently and seem to be associated with the optimization of physiological processes. In larger groups the average pulse respiration quotient is about 4:1. QUESTION: Can systematic effects on HRV, and thus on autonomic balance, be established through special speech therapy? SUBJECTS AND METHODS: In two trained therapists and 7 untrained subjects the influence of different speech exercises and texts on HRV was investigated. With untrained subjects a total of 105 one-hour sessions, divided into speech and control exercises, was performed. The overall well-being and quality of well-being were assessed with questionnaires. Control evaluations were made in the same setting. RESULTS: As a simultaneous effect, during speech exercises and texts typical intra- and inter-individually reproducible patterns in heart rate variability were observed. Reciting poems with a hexameter metric generates 2 oscillations with a 2:1 frequency ratio in the HRV spectrum. As immediate effects there were a significant drop in heart rate after speech sessions as well as a strengthening of vagus-related HRV parameters, especially after hexameter exercises. In comparison to control sessions the subjects felt significantly better, too. The different metric and poetic character of the texts was reflected clearly in the results.

Lymphocyte diversity in a 9-year-old boy with idiopathic CD4+ T cell lymphocytopenia.

Since CD4+ lymphocytopenia can be caused by disturbed thymic T-cell maturation, we investigated the T-cell subsets of a 9-year-old boy fulfilling the diagnostic criteria for CD4+ lymphocytopenia in a follow-up period of 4 years. We found (I) reduced CD45RA expression, (II) enhanced CD45RO expression and (III) a significant increase in gamma delta TCR-bearing T cells. An accelerated apoptosis (11%) was observed in the CD45RO+, but not CD45RA+ subset. These findings provide evidence that a disturbed thymic T-cell maturation process might play a role in the pathogenesis of CD4+ lymphocytopenia.

Rotavirus infection as cause of tacrolimus elevation in solid-organ-transplanted children.

Rotavirus (RV) is the most common cause of diarrheal illness in children. We report three solid-organ-transplanted patients in whom RV infection caused increased trough levels of the immunosuppressive macrolide tacrolimus (TAC) by mechanisms that are still under investigation. The virus was detected for longer in the feces of these patients than in infants not receiving immunosuppressive therapy. In association with short-term monitoring of blood trough levels of TAC, the dosage should be reduced early if symptoms of an acute gastroenteritis are present.

Elevated tacrolimus trough levels in association with mycophenolate mofetil-induced diarrhea: a case report.

The combination of tacrolimus (TAC) and mycophenolate mofetil (MMF) is frequently used for immunosuppression after organ transplantation (Tx), but the pharmacokinetics and interactions between the two drugs are poorly elucidated. We describe here the increase of TAC trough levels during MMF-induced diarrhea in a 8-yr-old boy after kidney Tx. Early dose reduction of TAC, together with short-term monitoring of TAC trough levels in the presence of diarrhea, is recommended.

A prospective evaluation of community acquired gastroenteritis in paediatric practices: impact and disease burden of rotavirus infection.

AIMS: To examine the disease burden and epidemiology of community acquired rotavirus gastroenteritis in Austrian children treated in a paediatric practice. METHODS: A prospective, population based, multicentre study in four paediatric practices and two children's hospitals (Innsbruck and Leoben). Children

Economic impact of community- and nosocomially acquired rotavirus gastroenteritis in Austria.

OBJECTIVE: To determine the average costs per child for rotavirus (RV) acute gastroenteritis from different perspectives, from the hospital's, third-party payer's, pediatrician's and family's perspectives as well as in summary from the societal one. MATERIALS AND METHODS: This cost-of-illness study is based on data collected alongside a 6-month prospective, laboratory-confirmed epidemiologic study that evaluated the disease burden of RV infection in Austrian children < or =48 months of age. The study population at risk to contract a community- and nosocomially acquired acute gastroenteritis comprised 9,687 children. All of the 51 children with community-acquired and 33 with nosocomially acquired RV acute gastroenteritis were included in this analysis. The annual costs were estimated by means of extrapolation. RESULTS: For community-acquired RV acute gastroenteritis, the average costs from the hospital's perspective were EURO (EUR) 97.8, from the third party payer's perspective 95.6 EUR, followed by 29.9 EUR and 9.8 EUR from the family's and pediatrician's perspectives, respectively. For nosocomially acquired RV acute gastroenteritis the average costs from the hospital's perspective were 1,494 EUR and from the third party payer's and family's perspectives 831 EUR and 116.8 EUR, respectively. In summary the average costs from the societal point of view for community-acquired RV acute gastroenteritis were 250 EUR and for nosocomial infections 2,442 EUR. After extrapolation the estimated total annual costs were 7.17 EUR million to 0.97 EUR million (13.6%) caused by community-acquired RV acute gastroenteritis and 6.2 EUR million (86.4%) caused by nosocomial RV acute gastroenteritis. CONCLUSION: This cost-of-illness study clearly demonstrates the great impact of RV acute gastroenteritis, mainly of nosocomially acquired infection, on medical health care costs in Austria. To cut costs efforts in disease prevention should be encouraged.

Congenital sodium diarrhea is an autosomal recessive disorder of sodium/proton exchange but unrelated to known candidate genes.

BACKGROUND & AIMS: Congenital sodium diarrhea (CSD) is caused by defective sodium/proton exchange with only 6 sporadic cases reported. The genetics of the disease have not been established. We studied 5 infants with secretory diarrhea, identified in a circumscribed rural area in Austria, to define the mode of transmission and the involvement of candidate genes known to encode for sodium/proton exchangers (NHEs). METHODS: We collected clinical and laboratory data from 5 affected patients, analyzed the pedigrees of their families, and performed homozygosity mapping and multipoint linkage analysis studies in 4 candidate regions known to contain NHE genes. RESULTS: The diagnosis of CSD in 4 of 5 patients was based on daily fecal sodium excretion between 98 and 190 mmol/L, hyponatremia, metabolic acidosis, and low-to-normal urinary sodium concentrations. Pedigree analysis of the affected 2 CSD families revealed parental consanguinity and a common single ancestor 5 generations ago. Homozygosity mapping and/or multipoint linkage analysis excluded the NHE1 locus on chromosome 1, NHE2 locus on chromosome 2, NHE3 locus on chromosome 5, and NHE5 locus on chromosome 16 as potential candidate genes for CSD in this pedigree. Results on NHE4 were inconclusive because the precise chromosomal location of this NHE gene in humans is currently unknown. CONCLUSIONS: Our data indicate that CSD is an autosomal recessive disorder but is not related to mutations in the NHE1, NHE2, NHE3, and NHE5 genes encoding for currently known sodium/proton exchangers.

Distribution of rotavirus VP4 genotypes and VP7 serotypes among nonhospitalized and hospitalized patients with gastroenteritis and patients with nosocomially acquired gastroenteritis in Austria.

To assess the potential benefits of a reassortant tetravalent rotavirus vaccine, we investigated stool specimens from children in three different groups by reverse transcription-PCR (RT-PCR) for rotavirus G and P types: (i) children not hospitalized with community-acquired rotavirus-acute gastroenteritis (RV-AGE), (ii) children hospitalized for RV-AGE, and (iii) children with nosocomially acquired RV-AGE. From a total of 553 samples investigated, 335 were positive by enzyme-linked immunosorbent assay, of which 294 (88%) were positive by RT-PCR. Among the RT-PCR-positive samples, the predominant types were G1P[8] (84%), followed by G4P[8] (9%) and G3P[8] (2%). No differences between the three groups were observed, suggesting that community vaccination will diminish the most cost-relevant cases of hospitalizations and nosocomial infections.

[Thrombolysis with recombinant tissue-type plasminogen activator (rt-PA) in 13 children: a case series]. / Thrombolyse mit rekombinantem Gewebe-Plasminogenaktivator (rt-PA) bei 13 Kindern: Eine Fallserie.

Since thromboembolic events (TE) are rare among children there is only limited information on the optimal choice of antithrombotic agents, dose and duration of antithrombotic therapy. Recombinant tissue plasminogen activator (rt-PA) is increasingly used for thrombolytic therapy of organ- and limb threatening thrombosis in children. We investigated retrospectively the efficacy and safety of rt-PA in 13 children treated consecutively between 1996-1999, following the same protocol. The median age was 3.9 years (3 days to 16 years). All children suffered from underlying diseases. In addition, 7 children had cardiac catheters and central venous catheters and two children suffered from Factor V Leiden mutation. Seven children presented with a TE in the arterial system, 6 with one in the venous system. All children were treated with continuous infusion of rt-PA (median dose 0.05; 0.0125-0.2 mg/kg/h) together with low-dose standard heparin (median dose 8; 5-15 IU/kg/h). Thrombolysis was performed for a median time period of 102 hours (6 hours to 16 days). Treatment effects on the thrombus were regularly confirmed by ultrasound. Plasma levels of fibrinogen and haemoglobin decreased moderately during treatment. No cumulative effect or increased dose requirement of rt-PA was detected during extended treatment. Patency of obstructed vessels was achieved in all children. One child developed severe gastrointestinal bleeding. Six children (46%) developed minor bleeding at the site of catheter puncture. One child developed rethrombosis at the site of the previous thrombus 2 weeks after completion of rt-PA treatment. Under rigorous laboratory and ultrasound control, our protocol using low dose rt-PA over a prolonged period of time was effective and safe.

Effective T cell regeneration following high-dose chemotherapy rescued with CD34+ cell enriched peripheral blood progenitor cells in children.

The ex vivo enrichment for the CD34+ cell fraction of PBPC, while it retains the capacity to restore haematopoiesis and potentially reduces a contamination by tumour cells, implements a depletion of T cells. To test whether such a setting adversely affects T cell reconstitution, we monitored T cells in four paediatric patients after CD34+ selected PBPC transplantation. The dose of CD34+ cells, which were enriched to 74%, median, was 7.1 x 10(6)/kg, median, that of T cells was 0.071 x 10(6)/kg, median. The patients were homogenous with respect to features with a potential to effect T cell reconstitution (low median age, (35 years); stage IV malignant tumours in first CR, uncomplicated post-treatment course). The results of sequential FACS analyses showed that by 9 months after treatment all four patients had recovered (1) a normal T cell count (CD3+ cells 1434/microl, median); (2) a normal CD4+ cell count (816/microl, median), while CD8+ cells were recovered (>330/microl) already by 3 months; (3) a normal CD4/CD8 ratio (1.8, median), as a result of an augmented growth of CD4+ cells between 3 and 6 months (increase of CD4+ cells 4.9-fold, median, CD8+ cells 1.1-fold, median). Expansion of cells with a CD45RA+ phenotype (thymus-derived T cells) predominated; from 3 to 6 months the increase of CD4+/CD45RA+ T cells was 130-fold, that of CD4+/CD45RO+ cells was 1.7-fold; CD8+/CD45RA+ cells increased 9-fold, CD8+/CD45RO+ cells increased 2.1-fold, indicating effective thymopoiesis. The findings demonstrate that in paediatric patients the setting of HD-CTX rescued with autologous CD34+ selected PBPC per se is not predictive of an impaired T cell recovery. High thymic activity may be a key factor for the rapid restoration of T cells.

Further evidence that Cerebrolysin protects cortical neurons from neurodegeneration in vitro.

The effects of Cerebrolysin on isolated chicken cortical neurons in an iron induced oxidative stress model and in a combined iron-glutamate model have been examined. In a first part of experiments it has been shown that under low serum conditions exposure of neurons to different concentrations of ammonium-iron (III)citrate (1, 5 microM AC-Fe3+) for 8 days caused a significant reduction in neuronal survival. Cerebrolysin not only prevented iron induced neurodegeneration, demonstrating that ionic iron was responsible for the cell damage, moreover, it increased the neuronal viability up to tenfold with respect to the controls. In the second part of the study neurons pre-incubated for 8 days with AC-Fe3+ were additionally lesioned with 1 mM L-glutamate and allowed to recover for another 48 h. Under these conditions cerebrolysin again clearly counteracted the in vitro destructive effects of glutamate. Besides consequences on the viability and survival of neurons Cerebrolysin increased abundance of the microtubule-associated protein MAP2, which is known to play a an important role in maintaining normal neuronal function.

Flow-cytometric evaluation of oxidative burst in phagocytic cells of children with cystic fibrosis.

OBJECTIVES: The objective of this study was to assess the dye 2', 7'-dichlorofluorescein (DCF) assay in screening for alterations in polymorphonuclear cell (PMN) and monocyte (MC) oxidative burst of cystic fibrosis (CF) patients. STUDY DESIGN: 56 CF patients aged between 2 and 20 years were investigated. Purified cells were stimulated with phorbolmyristate acetate (PMA) and zymosan (ZX). A range for DCF fluorescence for PMA- and ZX-stimulated and non-stimulated cells was established based on data from 60 healthy controls. RESULTS: PMNs showed both enhancement and impairment. A deficient oxidative burst was detected in a total of 14 CF patients caused by abnormally high mean fluorescence intensity (MFI) of resting cells. Enhanced oxidative burst was seen in 6 CF patients. CF patients responded differently to PMA or ZX stimulation. Pseudomonas aeruginosa colonization significantly enhanced (p<0.005) the MFI of resting PMNs. MCs of CF patients showed a significantly (p<0.05) enhanced oxidative burst after stimulation with PMA compared to healthy controls, but no differences could be observed after stimulation with ZX. Serum concentrations of interleukin-6 were elevated in all CF patients, in particular in those with activation of both PMNs and MCs. CONCLUSION: The DCF assay shows for the first time the heterogeneity of the oxidative burst reaction in CF patients. In our opinion, the DCF assay is a reliable method for detecting pathological oxidative burst in CF patients.

Plasma vitamin C concentrations in patients with cystic fibrosis: evidence of associations with lung inflammation.

Vitamin C status and possible associations with the disease process in cystic fibrosis (CF) patients were investigated. Plasma vitamin C concentrations in patients from two different mid-European populations (Swiss, n = 62; Austrian, n = 60) taking no or low-dose vitamin C from multivitamin supplements did not differ from each other or from control subjects (n = 34). Vitamin C concentrations decreased with age (5.05 mumol.L-1, y-1). When followed up for 12 mo, patients had the highest plasma vitamin C concentrations in February and the lowest in May and August (P < 0.01); the decrease in vitamin C was accompanied by increases in plasma malondialdehyde (P < 0.001) and tumor necrosis factor alpha concentrations (P < 0.01). During supplementation with vitamin E for 2 mo or beta-carotene for 12 mo vitamin C concentrations did not change. They correlated inversely with white blood cell count (r = -0.36, P = 0.008), bands (r = -0.36, P = 0.02), alpha 1-acid glycoprotein (r = -0.45, P = 0.002), interleukin 6 (r = -0.46, P = 0.0006), and neutrophil elastase/alpha 1-proteinase inhibitor complexes (r = -0.34, P = 0.02). In patients with vitamin C concentrations < 40 mumol/L, all indexes of inflammation were relatively high, whereas those with concentrations > 80 mumol/L (upper quartile of control subjects) showed clearly lower values. These results are consistent with the hypothesis that by scavenging oxygen free radicals vitamin C interacts with an inflammation-amplifying cycle of activation of alveolar macrophages and neutrophils, release of proinflammatory cytokines and oxygen free radicals, and inactivation of antiproteases.

Detection of 100% of the CFTR mutations in 63 CF families from Tyrol.

We identified 100% of the CFTR gene mutations, including three novel mutations, in 126 unrelated cystic fibrosis chromosomes from Tyrol, Austria. The frequency of the major mutation deltaF508 (74.6%) was not significantly different in Tyrolian CF-patients than in patients from Bavaria (71.0%) and Middle- and Northern Germany (71.9%), but was significantly higher than in patients from Styria (58.1%) or Northern Italy (47.6%). Interestingly, the distribution of the next most frequent mutations, R1162X (8.7%) 2183AA-->G, 2789+5G-->A and G542X (2.4% each), was more similar to the distribution of these mutations among CF-patients from Northern Italy than to those from Styria, Bavaria or Middle- and Northern Germany. Nine further mutations occurred once or twice. One of these, the missense mutation M1101K, is rare worldwide but very frequent in the Hutterite brethren, a small founder population which came from Southern Austria to Northern America. Three other different mutations (deltaL453, 1874insT and 4108delT) were present in single Tyrolian families and have not been described before. The identification of 100% of CFTR gene mutations in a particular CF population demonstrates the power of genetic analysis for the diagnosis and counselling of CF families in this restricted geographical area of Austria. Our study provides evidence for a closer genetic relation between CF patients from Tyrol and those from Bavaria or Middle- and Northern Germany as well as Northern Italy, than between CF patients from the two Austrian states Tyrol and Styria.

Chronic granulomatous disease assessed by single-cell granulocyte oxidative burst activity.

Here we report on a case of chronic granulomatous disease (CGD) in a 3-year-old boy who suffered from severe repeated bacterial infections including multiple liver abscesses. The case is of interest because (1) the disease is very rare (it is the first case of CGD diagnosed at the Clinic for Pediatric Medicine, University of Innsbruck), (2) the diagnosis, based on clinical parameters and the nitrobluetetrazolium test was completed and validated by single-cell measurements of respiratory-burst activity of the patient's granulocytes in a fluorescence-activated cell sorter (FACS), and (3) the applied FACS method, adapted in our laboratory, presents one of the most sensitive and reliable methods to evaluate this aspect of disturbed granulocyte function.