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David Nadal

Publications and source records attributed to David Nadal.

32 records · Page 2Linked to original sources
PubMed2003

Low penetrance, broad resistance, and favorable outcome of interleukin 12 receptor beta1 deficiency: medical and immunological implications.

The clinical phenotype of interleukin 12 receptor beta1 chain (IL-12Rbeta1) deficiency and the function of human IL-12 in host defense remain largely unknown, due to the small number of patients reported. We now report 41 patients with complete IL-12Rbeta1 deficiency from 17 countries. The only opportunistic infections observed, in 34 patients, were of childhood onset and caused by weakly virulent Salmonella or Mycobacteria (Bacille Calmette-Guérin -BCG- and environmental Mycobacteria). Three patients had clinical tuberculosis, one of whom also had salmonellosis. Unlike salmonellosis, mycobacterial infections did not recur. BCG inoculation and BCG disease were both effective against subsequent environmental mycobacteriosis, but not against salmonellosis. Excluding the probands, seven of the 12 affected siblings have remained free of case-definition opportunistic infection. Finally, only five deaths occurred in childhood, and the remaining 36 patients are alive and well. Thus, a diagnosis of IL-12Rbeta1 deficiency should be considered in children with opportunistic mycobacteriosis or salmonellosis; healthy siblings of probands and selected cases of tuberculosis should also be investigated. The overall prognosis is good due to broad resistance to infection and the low penetrance and favorable outcome of infections. Unexpectedly, human IL-12 is redundant in protective immunity against most microorganisms other than Mycobacteria and Salmonella. Moreover, IL-12 is redundant for primary immunity to Mycobacteria and Salmonella in many individuals and for secondary immunity to Mycobacteria but not to Salmonella in most.

Adolescent↗
PubMed2003

Quantitative cytokine gene expression in human tonsils at excision and during histoculture assessed by standardized and calibrated real-time PCR and novel data processing.

Real-time reverse transcription polymerase chain reaction (RT-PCR) assays were developed for the quantification of expression of the genes for human interleukin (IL)-1beta, IL-2, IL-6, IL-8, IL-10, IL-12, IL-15, interferon (IFN)-gamma, tumor necrosis factor (TNF)-alpha, transforming growth factor (TGF)-beta and for the endogenous reference hydroxymethylbilane synthase (HMBS). The assays detected as little as five plasmid copies and were 100% specific. The creation and integration of a calibration sample into the assays permitted their calibration across experiments. To handle the high number of generated data, the correlator of advanced real-time assays (CARTA) software was designed to organize samples and to automatically control and analyze TaqMan real-time RT-PCR data. The RT-PCR assays were applied to quantify levels of cytokine gene expression in human palatine tonsils at excision and during 4 days of histoculture. Similar longitudinal patterns of cytokine gene expression were observed in all donors, but the variations in spontaneous expression levels between donors were large. The expression levels in histocultures were constant over time and similar to the expression levels at excision except for IL-6 and IL-8, which markedly increased following the first 24 h of culture, possibly due to the initial stress. The standardized and calibrated RT-PCR assays quantify gene expression of human cytokines proved sensitive and specific for the investigation of cell behavior at the molecular level and the newly established CARTA software, a reliable tool for rapid data handling. Tonsil histocultures could serve as a valuable ex vivo model system for further, donor-dependent, studies on activation or repression of cytokine gene expression.

Calibration↗
PubMed2003

Monitoring intracellular replication of Chlamydophila (Chlamydia) pneumoniae in cell cultures and comparing clinical samples by real-time PCR.

Strains of Chlamydophila pneumoniae may be associated with respiratory disease or atherosclerosis. Two real-time quantitative PCR assays targeting the species-specific genes Cpn0278 and ArgR were developed to compare the in vitro growth of respiratory strains AR39 and K6 with that of atherosclerotic strain A03 and to quantify C. pneumoniae in clinical samples. A third real-time PCR assay was designed to assess contamination with Mycoplasma spp. The assays targeting C. pneumoniae detected DNA concentrations corresponding to 10(4) to 10(-4) inclusion-forming units (IFU)/reaction and were highly specific. AR39 exhibited the longest lag phase and period of exponential growth; K6 augmented growth rates at higher inocula; and A03 grew at highest rates. Contamination with Mycoplasma spp. of AR39 and A03 unlikely accounted for growth differences between them. Numbers of IFU in C. pneumoniae-positive respiratory secretions varied within 4 to 5 orders of magnitude. The assays described may prove valuable for pathogenicity studies.

Base Sequence↗
PubMed2003

Quantitative detection of Moraxella catarrhalis in nasopharyngeal secretions by real-time PCR.

The recognition of Moraxella catarrhalis as an important cause of respiratory tract infections has been protracted, mainly because it is a frequent commensal organism of the upper respiratory tract and the diagnostic sensitivity of blood or pleural fluid culture is low. Given that the amount of M. catarrhalis bacteria in the upper respiratory tract may change during infection, quantification of these bacteria in nasopharyngeal secretions (NPSs) by real-time PCR may offer a suitable diagnostic approach. Using primers and a fluorescent probe specific for the copB outer membrane protein gene, we detected DNA from serial dilutions of M. catarrhalis cells corresponding to 1 to 10(6) cells. Importantly, there was no difference in the amplification efficiency when the same DNA was mixed with DNA from NPSs devoid of M. catarrhalis. The specificity of the reaction was further confirmed by the lack of amplification of DNAs from other Moraxella species, nontypeable Haemophilus influenzae, H. influenzae type b, Streptococcus pneumoniae, Streptococcus oralis, Streptococcus pyogenes, Bordetella pertussis, Corynebacterium diphtheriae, and various Neisseria species. The assay applied to NPSs from 184 patients with respiratory tract infections performed with a sensitivity of 100% and a specificity of up to 98% compared to the culture results. The numbers of M. catarrhalis organisms detected by real-time PCR correlated with the numbers detected by semiquantitative culture. This real-time PCR assay targeting the copB outer membrane protein gene provided a sensitive and reliable means for the rapid detection and quantification of M. catarrhalis in NPSs; may serve as a tool to study changes in the amounts of M. catarrhalis during lower respiratory tract infections or following vaccination against S. pneumoniae, H. influenzae, or N. meningitidis; and may be applied to other clinical samples.

Bacterial Outer Membrane Proteins↗
PubMed2003

Prevalence of enteroaggregative Escherichia coli among children with and without diarrhea in Switzerland.

In a prospective study between July 1999 and September 2000, stool specimens of children below the age of 16 years with (n = 187) and without (n = 137) diarrhea were tested for the presence of enterovirulent bacteria by standard culture methods and by PCR. Targets for the PCR were the plasmid pCVD432 for enteroaggregative Escherichia coli (EAEC), the verotoxin 1 and verotoxin 2 genes for enterohemorrhagic E. coli, ipaH for enteroinvasive E. coli (EIEC) and Shigella spp., genes coding for heat-stable and heat-labile toxins for enterotoxigenic E. coli (ETEC), and the eaeA gene for enteropathogenic E. coli. The following bacteria could be associated with diarrhea: Salmonella enterica (P = 0.001), Campylobacter spp. (P = 0.036), ETEC (P = 0.012), and EAEC (P = 0.006). The detection of EAEC, ETEC, and S. enterica was strongly associated with a history of recent travel outside of Switzerland. EAEC isolates were found in the specimens of 19 (10.2%) of 187 children with diarrhea and in those of 3 (2.2%) of 137 children without diarrhea (P = 0.006) and were the most frequently detected bacteria associated with diarrhea. Among the children below the age of 5 years, the specimens of 18 (11.9%) of 151 with diarrhea were positive for EAEC, while this agent was found in the specimens of 2 (2.2%) of 91 controls (P = 0.007). Enteropathogenic E. coli isolates were found in the specimens of 30 (16.4%) of the patients and in those of 15 (10.9%) of the controls, with similar frequencies in all age groups (P > 0.05). We conclude that EAEC bacteria are involved in a significant proportion of diarrhea cases among children. Children younger than 5 years of age are more often affected by EAEC than older children.

Adolescent↗
PubMed2002

An investigation of the steady-state pharmacokinetics of oral valacyclovir in immunocompromised children.

Valacyclovir was administered to 28 immunocompromised children (ages 5-12 years) to obtain preliminary pharmacokinetic and safety information. Patients were randomized to valacyclovir regimens of 250 mg (9.4-13.3 mg/kg) or 500 mg (13.9-27.0 mg/kg) twice daily or 500 mg (13.2-21.7 mg/kg) 3 times a day. Acyclovir pharmacokinetics were evaluated at steady state. Valacyclovir was rapidly absorbed and converted to acyclovir. Mean (+/-SD) acyclovir peak concentrations from 250 mg and 500 mg valacyclovir were 4.11+/-1.41 and 5.19+/-1.96 microg/mL, respectively. Corresponding single dose area-under-curve values were 12.14+/-6.60 and 14.49+/-4.69h microg/mL. By using historical data for intravenous acyclovir as reference, the overall estimate of acyclovir bioavailability from valacyclovir was 48%, 2- to 4-fold greater than for oral acyclovir. In general, adverse events were not attributable to valacyclovir and were consistent with disease-related expectations and concomitant therapies. Dosage options for using valacyclovir in children are discussed.

Acyclovir↗
PubMed2002

Diagnostic accuracy of G-CSF, IL-8, and IL-1ra in critically ill children with suspected infection.

OBJECTIVE: To elucidate the diagnostic accuracy of granulocyte colony-stimulating factor (G-CSF), interleukin-8 (IL-8), and interleukin-1 receptor antagonist (IL-1ra) in identifying patients with sepsis among critically ill pediatric patients with suspected infection. DESIGN AND SETTING: Nested case-control study in a multidisciplinary neonatal and pediatric intensive care unit (PICU) PATIENTS: PICU patients during a 12-month period with suspected infection, and plasma available from the time of clinical suspicion (254 episodes, 190 patients). MEASUREMENTS AND RESULTS: Plasma levels of G-CSF, IL-8, and IL-1ra. Episodes classified on the basis of clinical and bacteriological findings into: culture-confirmed sepsis, probable sepsis, localized infection, viral infection, and no infection. Plasma levels were significantly higher in episodes of culture-confirmed sepsis than in episodes with ruled-out infection. The area under the receiver operating characteristic curve was higher for IL-8 and G-CSF than for IL-1ra. Combining IL-8 and G-CSF improved the diagnostic performance, particularly as to the detection of Gram-negative sepsis. Sensitivity was low (<50%) in detecting Staphylococcus epidermidis bacteremia or localized infections. CONCLUSIONS: In this heterogeneous population of critically ill children with suspected infection, a model combining plasma levels of IL-8 and G-CSF identified patients with sepsis. Negative results do not rule out S. epidermidis bacteremia or locally confined infectious processes. The model requires validation in an independent data-set.

Area Under Curve↗
PubMed2002

Hyperlipidemia in HIV-infected children treated with protease inhibitors: relevance for cardiovascular diseases.

Cases of severely hypercholesterolemic HIV-infected children taking protease inhibitors (PIs) have been reported. Because high cholesterol levels (> or =15 mmol/L), as seen in homozygous familial hypercholesterolemia (FH), may lead to heart disease in childhood, the authors performed a systematic retrospective survey of all plasma lipid levels recorded for children who had received ritonavir or nelfinavir between 1995 and 2001 in Switzerland. Administration of PIs was associated with a significant increase in plasma cholesterol levels, which was more pronounced for those given ritonavir (from 3.3 +/- 0.7 mmol/L, n = 5 to 6.3 +/- 2.8 mmol/L, n = 19 [mean +/- SD]; p =.03) than for nelfinavir (from 3.0 +/- 0.7 mmol/L, n = 11 to 4.9 +/- 1.0 mmol/L, n = 30; p = <.001). Cholesterol levels exceeded 10.0 mmol/L in 3 of 49 (6%) PI-treated children and culminated at 13.8 mmol/L. Plasma cholesterol levels in PI-treated children were comparable with levels reported for heterozygous FH children but were all lower than in homozygous FH children. Because heterozygous FH patients usually develop heart disease in middle age, the authors conclude that the risk for heart disease in PI-treated children is minimal. Long-term monitoring of these children, however, will be necessary.

Cardiovascular Diseases↗
PubMed2002

Three consecutive outbreaks of Serratia marcescens in a neonatal intensive care unit.

We investigated an outbreak of Serratia marcescens in the neonatal intensive care unit (NICU) of the University Hospital of Zurich. S. marcescens infection was detected in 4 children transferred from the NICU to the University Children's Hospital (Zurich). All isolates showed identical banding patterns by pulsed-field gel electrophoresis (PFGE). In a prevalence survey, 11 of 20 neonates were found to be colonized. S. marcescens was isolated from bottles of liquid theophylline. Despite replacement of these bottles, S. marcescens colonization was detected in additional patients. Prospective collection of stool and gastric aspirate specimens revealed that colonization occurred in some babies within 24 hours after delivery. These isolates showed a different genotype. Cultures of milk from used milk bottles yielded S. marcescens. These isolates showed a third genotype. The method of reprocessing bottles was changed to thermal disinfection. In follow-up prevalence studies, 0 of 29 neonates were found to be colonized by S. marcescens. In summary, 3 consecutive outbreaks caused by 3 genetically unrelated clones of S. marcescens could be documented. Contaminated milk could be identified as the source of at least the third outbreak.

Animals↗
PubMed2002

Use of simple heuristics to target macrolide prescription in children with community-acquired pneumonia.

BACKGROUND: Macrolides are the first-line antibiotic treatment of community-acquired pneumonia (CAP). Owing to alarming resistance rates among invasive Streptococcus pneumoniae isolates, particularly in young children, macrolide use should be restricted to patients infected with susceptible pathogens, eg, Mycoplasma pneumoniae. OBJECTIVE: To develop a simple clinical prediction rule for identifying M pneumoniae as the cause of CAP in children. DESIGN AND SETTING: Prospective cohort study in 253 children with radiologically confirmed CAP in a walk-in clinic of a tertiary care hospital. MAIN OUTCOME MEASURES: Mycoplasma infection, proven by results of antibody testing of paired serum samples (gold standard). We compared the area under the receiver operating characteristic curve (c statistic) of the following 2 prediction models: a scoring system derived from logistic regression analysis and a fast-and-frugal decision tree. RESULTS: Mycoplasma pneumoniae infection was confirmed in 32 (13%) of 253 children. A scoring system based on duration of fever and patient age yielded a c statistic of 0.84 (95% confidence interval [CI], 0.77-0.91), compared with that of the decision tree (c = 0.76 [95% CI, 0.70-0.83]). The scoring system identified 75% of all cases as being at high or very high risk for M pneumoniae infection; the decision tree, 72% at high risk. The scoring system would curtail macrolide prescriptions by 75%; the decision tree, by 68%. CONCLUSIONS: In children with CAP, simple clinical decision rules identify patients at risk for M pneumoniae infection. At present US macrolide resistance rates among invasive S pneumoniae isolates, both rules increase the chance of prescribing effective first-line antibiotics compared with general macrolide administration.

Anti-Bacterial Agents↗
PubMed2002

Epstein-Barr virus (EBV) DNA levels in palatine tonsils and autologous serum from EBV carriers.

A real-time polymerase chain reaction was employed to detect and quantitate Epstein-Barr virus (EBV) DNA in tonsils and autologous sera from EBV-seropositive children. EBV DNA was found in 95% of tonsils from 21 children and in 50% from 18 children with serum IgG titers to the virus capsid antigen (VCA) of > or =1:160 and 1:10 to 1:80, respectively (P = 0.002). Tonsils from children with titers > or =1:160 harbored more EBV DNA copies per mg tissue (mean, 1,237; range, < 2-13,998) than from children with titers 1:10 to 1:80 (mean, 23; range, < 2-226; P < 0.0001). By contrast, EBV DNA was detected only in serum from 25% of 20 children with titers > or = 1:160. Thus, ample differences in tonsillar EBV replication are mirrored inconstantly by detectable EBV in autologous serum suggesting that EBV DNA quantitation in tonsils may serve for refined monitoring of individuals at risk of EBV-associated lymphoproliferation.

Carrier State↗
PubMed2002

Turicella otitidis and Corynebacterium auris do not cause otitis media with effusion in children.

BACKGROUND: The recently described coryneform bacteria and were first detected in the middle ear of patients with acute otitis media and chronic otitis media. Whether these bacteria play an essential role in the pathogenesis of otitis media with effusion (OME) is unclear. METHODS: In a prospective study 60 children with OME and 205 controls were evaluated to determine the incidence of and. Swabs from the external auditory canal (EAC) and the middle ear effusion (MEE) of OME children undergoing tympanotomy, ventilation tube insertion or both were cultured. Swabs from the EAC from healthy children served as controls. RESULTS: In control children was found in EAC swabs from 23 of 205 (11.2%) and in 32 of 205 (15.6%). was isolated from 14 of 60 (23.3%) OME patients from the EAC only and in 6 of 60 (10.0%) OME patients from both EAC and MEE. was isolated in 2 of 60 (3.3%) from the EAC only and in 1 of 60 (1.7%) from both EAC and MEE. In no patient did or grow exclusively from MEE. CONCLUSION: and may be part of the normal bacterial flora of the EAC in some children. Neither organism seems to cause OME in children.

Age Distribution↗
PubMed2002

Rates of detection of Neisseria meningitidis in tonsils differ in relation to local incidence of invasive disease.

Nasopharyngeal swabbing substantially underestimates carriage of Neisseria meningitidis. Real-time PCR assays were employed to examine the presence of a broad range of bacteria and of N. meningitidis groups B and C, respectively, in tonsils from 26 individuals from Oxford, England, and 72 individuals from Zurich, Switzerland. The detection limit of each PCR system was DNA from one bacterial cell per reaction mixture. Tonsillar DNA did not inhibit amplification of meningococcal gene sequences, and N. meningitidis was detected in tonsils exposed to the bacterium. Whereas in both sets of patients other bacteria were detected, N. meningitidis group B and group C were only found in tonsils from Oxford where the incidence of invasive meningococcal disease is much higher than in Zurich. These observations suggest that PCR-based methods could be used for the detection of meningococcal carriage and that difference in disease incidence could be explained by different transmission rates in the community rather than host genetics or coexisting infections.

Adolescent↗