Interleukin-6 G(--174)C polymorphism is associated with mental retardation in cystic periventricular leucomalacia in preterm infants

OBJECTIVE

The fetal inflammatory response syndrome involving proinflammatory cytokines such as interleukin-6 (IL-6) has been associated with cystic periventricular leukomalacia (cPVL). We evaluated whether the development of cPVL is associated with the IL-6 G(-174)C polymorphism.

METHODS

52 children with cPVL were compared to 46 preterm and 395 term controls using retrospective cohort analysis. IL-6 genotyping was performed using an allele specific polymerase chain reaction technique.

RESULTS

IL-6 G(-174)C polymorphisms did not differ between groups, but an association between mental retardation and the IL-6 C/C (78%) and G/C (43%) genotypes compared to the G/G (25%) genotype was found (p = 0.003 and 0.043, respectively; RR 3.11 (95% CI 1.54 to 6.29) and 1.79 (95% CI 1.10 to 2.92), respectively).

CONCLUSIONS

The IL-6 (-174) C/C and G/C genotypes were associated with mental retardation in cPVL and seem to modify the severity of perinatal brain injury.

Cytokine expression in serum and cerebrospinal fluid in non-inflammatory polyneuropathies

BACKGROUND

Pain is a common symptom in polyneuropathies (PNPs), although it is still not known why some PNPs are painful and others are painless. Increased pro-inflammatory cytokines have been found in conditions resulting in exaggerated pain states in animal studies. Recently, elevated pro-inflammatory cytokine levels have also been found in the cerebrospinal fluid (CSF) of patients suffering from complex regional pain syndrome. Pro-inflammatory cytokines have been shown to induce or increase inflammatory or neuropathic pain.

METHODS

Using chemiluminescent enzyme immunometric assays, cytokine levels in 36 patients with painful and painless non-inflammatory PNPs in serum and CSF were investigated. The severity of PNPs was measured with electroneurography (ENG). In subjects with normal results using conventional ENG, quantitative thermo-testing was performed to investigate small-nerve-fibre function.

RESULTS

Interleukin (IL)-6 and tumour necrosis factor (TNF)-alpha in serum or CSF did not differ between patients with (n = 18) or without (n = 18) painful PNPs, whereas patients with mechanical allodynia (n = 5) had elevated serum TNF-alpha levels compared to those without allodynia. TNF-alpha and IL-6 serum levels were higher in patients with severe (n = 21) compared to those with mild neuropathy (n = 15), and showed a positive correlation with severity of neuropathy.

CONCLUSIONS

Results suggest that nerve fibre degeneration and presence of mechanical allodynia in peripheral non-inflammatory neuropathy determine cytokine expression in serum.

Temporal evolution of nanoparticle aerosols in workplace exposure

The evolution in time of a nanoparticle (NP) aerosol released into a simulated workplace environment was investigated for different starting scenarios including (i) NP release into a particle-free atmosphere and (ii) release in presence of a pre-existing background aerosol. In each case, particle number distributions and total number concentrations in a 2 m(3) aerosol chamber were monitored over several hours. On the time scale and under the conditions relevant for workplace exposure, collisions between NP within their own size class and, if present, with the background aerosol were identified as the most important mechanism driving the change in particle size and number concentration. A model has been formulated on the basis of well-known aerosol dynamic principles to predict the evolution of NP number concentration for a defined source and a defined environment (a given background aerosol concentration). A dimensionless number is introduced to scale the rate of NP concentration change relative to background aerosol concentration and particle size, which scales inversely with the concentration of free NP in the atmosphere. Beyond the physical change, the emergence of binary agglomerates constitutes a change in chemical composition of the aerosol. It is shown that the NPs are still chemically present in the aerosol after becoming attached to background particles, thus remaining airborne while being invisible in the size distribution.

4G4G genotype of the plasminogen activator inhibitor-1 promoter polymorphism associates with disseminated intravascular coagulation in children with systemic meningococcemia

BACKGROUND

Meningococcal disease may present as sepsis, meningitis or a combination of both. Impaired fibrinolysis and massive elevation of the plasminogen activator inhibitor-1 (PAI-1) is a characteristic feature of meningococcal sepsis. We and others have reported an association between mortality and the functional 4G/5G promoter polymorphism of the PAI-1 gene in children with meningococcal sepsis.

OBJECTIVE

Multicenter study to investigate the association of the 4G/5G PAI-1 polymorphism and disseminated intravascular coagulation (DIC) in children with meningococcal disease in a Central European population.

PATIENTS/METHODS

Blood samples and clinical information of 326 previously healthy children with meningococcal infection were collected from 95 pediatric hospitals in Germany, Switzerland, Italy, and Austria from 2000 to 2002.

RESULTS

DIC, defined as platelet counts below 100 G L(-1), increased D-dimer levels and prolonged prothrombin time, was significantly associated with the 4G4G genotype [31 of 63 (49%) vs. 55 of 175 (31%), P = 0.014], resulting in a hazard ratio (HR) of 1.5 (95% confidence interval 1.1-2.1) to develop DIC. Carriers of the 4G4G genotype showed significantly lower platelet counts (183 G L(-1) vs. 227 G L(-1), P = 0.009) on admission. Fibrinogen and C-reactive protein levels were not associated with the PAI-1 4G/5G polymorphism, nor were white blood cell counts.

CONCLUSIONS

Our data show a correlation between the 4G4G genotype of the PAI-1 gene and development of DIC in meningococcal infection.

A review of the genetics of essential hypertension

PURPOSE OF REVIEW

Essential hypertension affects more than 20% of the adult population, and has a multifactorial origin arising from an interaction between susceptibility genes and environmental factors. Several strategies have been used to identify hypertension susceptibility genes. This review highlights recent efforts in genetic dissection of essential hypertension.

RECENT FINDINGS

Recently, further chromosomal regions harboring blood pressure loci have emerged in genome-wide linkage studies. Findings from a new systematic two-dimensional genome scan are presented, as well as sex-specific loci linked to hypertension in inbred rodent models. Many case-control association studies have been carried out, but results so far have been equivocal. This review discusses some interesting studies combining linkage and association strategies using gene-gene interactions, and studies the use of haplotypes instead of SNPs. Two novel hypertension susceptibility genes are presented, and a short summary on new insights into genes of the renin-angiotensin and adrenergic systems is given.

SUMMARY

To date, linkage and association studies have not been convincing. Genome-wide association studies may prove to be an effective approach to the problems posed by complex traits. Combined with candidate gene approaches, it is hoped this strategy will yield convincing evidence for genes associated with essential hypertension.

Protein C promoter polymorphisms associate with sepsis in children with systemic meningococcemia

Meningococcal disease may present as sepsis, meningitis or a combination of both. Protein C (PC) is an important regulator of thrombin activity. Two polymorphisms in the promoter region of PC (C-1654T, A-1641G) have been shown to affect PC levels. In patients with meningococcal sepsis, low PC levels have been correlated with increased severity and poor outcome. We established a multicenter case-control study to determine whether PC promoter polymorphisms are associated with occurrence and outcome of meningococcal disease and sepsis. 288 previously healthy children with meningococcal infection from 97 pediatric hospitals in Germany, Switzerland, Italy, and Austria and 309 healthy controls were included in the study. A strong age-dependant effect was found. Patients younger than 1 year carried significantly more often the CG-CG genotype than healthy controls (28.6% vs. 17.8%, P = 0.04). Carriers of the CG allele showed a 3.43-fold increased odds ratio (OR) to develop sepsis (95% CI: 1.05-11.20; 85.7% vs. 63.6%, P = 0.036). The TA-TA genotype conferred a protective role for the development of sepsis (P = 0.017) with a Haldane OR of 0.09 (95% CI: 0.01-0.94). Systolic blood pressure values were significantly decreased in patients carrying the CG-CG genotype (70 vs. 86 mmHg, P = 0.005), and the need for adrenergic support significantly higher (70% vs. 26%, P = 0.018), resulting in an OR of 6.61 (95% CI: 1.28-34.14). These findings show that in young children PC promoter genotype is associated with susceptibility for meningococcal disease, the development of meningococcal sepsis, lower blood pressure, and need for adrenergic support.

Rheumatoid arthritis patients have elevated antibodies to cross-reactive and non cross-reactive antigens from Proteus microbes

BACKGROUND AND OBJECTIVE

Although a large number of independent studies have shown a paramount role for Proteus mirabilis in the aetiopathogenesis of rheumatoid arthritis (RA), this hypothesis is still controversial among rheumatologists. The main obstacle to its acceptance is the impression that increased Proteus antibodies in RA patients is a secondary phenomenon, occurring as the result of cross-reactivity between bacterial and self-antigens. To shed light on this problem, we examined the link between antibodies to various cross-reactive and non cross-reactive antigenic peptides from P. mirabilis and analysed the relationship between these antibodies and disease severity in patients with RA.

METHODS

Using the ELISA method, serum samples from 70 RA patients and 20 healthy controls were screened for total and class-specific antibodies against three human cross-reactive and non-crossreactive synthetic peptides from P. mirabilis haemolysin, urease C and urease F enzymes. An antibody index, which comprised the total concentration of antibodies against these peptides in each sample, was correlated with the biochemical parameters of disease activity and/or severity, such as the erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) and rheumatoid factors (RF). Furthermore, anti-peptide antibody indices were evaluated among RA patients with different levels of disease activity as defined by ESR and CRP.

RESULTS

Significantly elevated levels of total and class-specific IgG antibodies against the 3 Proteus peptides were observed among RA patients compared to healthy controls (p < 0.001). Active RA patients had elevated IgM antibodies against all peptides compared to healthy subjects (p < 0.001). However, no such elevation was observed in IgA anti-peptide antibodies in RA patients. A positive correlation was observed between the antibody indices and ESR (p < 0.001) and CRP (p < 0.01) concentrations, but not the RF status or disease duration. Furthermore, more than 90% of active RA patients showed positive values for the Proteus anti-peptide indices.

CONCLUSION

The elevated levels of antibodies against Proteus antigenic epitopes (which are cross-reactive or non cross-reactive with human tissue antigens) observed indicates that this enhanced bacterial immune response in RA patients is specifically triggered by Proteus microbes. Furthermore, the correlation of anti-peptide antibody indices with the biochemical markers of disease activity indicates that these antibodies exert damaging cytotoxic effects on joint tissues during the course of the disease.

The diagnosis and treatment of nonspecific neck pain and whiplash

Nonspecific (simple) neck pain is the commonest cause of neck symptoms and results from postural and mechanical causes. It includes pain following whiplash injury provided there is no bony injury or objective neurological deficit. The anatomy of the cervical spine is described, with the degenerative changes that are seen in patients with nonspecific neck pain, but also occur with ageing. The poor correlation between the degree of degeneration and presence and severity of symptoms is noted. A lack of specific pathology is also a feature of whiplash. The epidemiology, clinical presentation, investigation, and complications of nonspecific neck pain are described with a discussion of the controversial aspects of natural history, prognosis and therapy. Chronic whiplash is very common in some countries, but nonexistent in other countries and the factors which might explain this difference are considered. There is a great need for better quality studies to explore pathogenesis, natural history and factors including therapy that influence outcome.

Endothelial dysfunction in cold type complex regional pain syndrome

The authors examined endothelial function in cold type chronic complex regional pain syndrome (CRPS) I using acetylcholine- and sodium nitroprusside-induced vasodilation combined with laser Doppler flowmetry in 14 patients and 10 controls. On the affected side, acetylcholine-induced vasodilation was significantly reduced in comparison to controls and the unaffected extremity. No significant differences were found after application of sodium nitroprusside. The results demonstrate impaired endothelial function in chronic CRPS I.

Quantitative sensory testing in the German Research Network on Neuropathic Pain (DFNS): Standardized protocol and reference values

The nationwide multicenter trials of the German Research Network on Neuropathic Pain (DFNS) aim to characterize the somatosensory phenotype of patients with neuropathic pain. For this purpose, we have implemented a standardized quantitative sensory testing (QST) protocol giving a complete profile for one region within 30 min. To judge plus or minus signs in patients we have now established age- and gender-matched absolute and relative QST reference values from 180 healthy subjects, assessed bilaterally over face, hand and foot. We determined thermal detection and pain thresholds including a test for paradoxical heat sensations, mechanical detection thresholds to von Frey filaments and a 64 Hz tuning fork, mechanical pain thresholds to pinprick stimuli and blunt pressure, stimulus/response-functions for pinprick and dynamic mechanical allodynia, and pain summation (wind-up ratio). QST parameters were region specific and age dependent. Pain thresholds were significantly lower in women than men. Detection thresholds were generally independent of gender. Reference data were normalized to the specific group means and variances (region, age, gender) by calculating z-scores. Due to confidence limits close to the respective limits of the possible data range, heat hypoalgesia, cold hypoalgesia, and mechanical hyperesthesia can hardly be diagnosed. Nevertheless, these parameters can be used for group comparisons. Sensitivity is enhanced by side-to-side comparisons by a factor ranging from 1.1 to 2.5. Relative comparisons across body regions do not offer advantages over absolute reference values. Application of this standardized QST protocol in patients and human surrogate models will allow to infer underlying mechanisms from somatosensory phenotypes.

Haplotypes of the beta-2 adrenergic receptor associate with high diastolic blood pressure in the Caerphilly prospective study

OBJECTIVES

Current evidence demonstrates that both genetic and environmental factors influence blood pressure. The sympathetic nervous system is a key player in blood pressure control and functional genetic variants of the beta-2 adrenergic receptor (B2AR) have been identified and implicated in the pathogenesis of hypertension. The present study aimed to determine the effects of common haplotypes of the B2AR gene upon blood pressure in the Caerphilly Prospective Study.

DESIGN

Two thousand five hundred and twelve men (aged 45-59 years) participated in the study. We selected individuals in the upper (n = 347) and lower (n = 279) quintiles of the diastolic blood pressure distribution fixed at two time points [phase 2 (1984-88) or phase 3 (1989-93)] as cases and controls.

METHODS

We analysed two functional polymorphisms (Arg16Gly and Gln27Glu) of B2AR and their haplotypes.

RESULTS

We found a higher risk of hypertension in individuals homozygous for the Gln27 compared to those individuals homozygous for Glu27 [odds ratio (OR) = 1.94; 95% confidence interval (CI) = 1.34-2.81; P = 0.001]. Three haplotypes (Gly16Gln27, Gly16Glu27 and Arg16Gln27) were present in both quintile groups. Logistic regression analysis showed that haplotypes with a Gln27 allele (Gly16Gln27 and Arg16Gln27) conferred a significantly higher risk for hypertension than the Gly16Glu27 haplotype (OR = 1.55; 95% CI = 1.11-2.17, OR = 1.37; 95% CI = 1.04-1.81; P = 0.009 and P = 0.027, respectively). However, there was no evidence to support a statistically significant difference in odds ratios for the Gly16Gln27 and Arg16Gln27 haplotypes (P = 0.477), suggesting that it is the Gln27 allele alone, rather than any haplotype, which best explains the association.

CONCLUSIONS

In a prospectively studied Caucasian male cohort, high diastolic blood pressure was associated with B2AR haplotypes containing the pro-downregulatory Gln27 variant.

Polymorphisms in the Interleukin-1 Gene Cluster in Children and Young Adults with Systemic Meningococcemia

BACKGROUND

An association has been described between mortality in children with meningococcal disease and functional polymorphisms in the interleukin-1 (IL1) cluster. We undertook a multicenter study to evaluate associations of these polymorphisms in a Central European population.

PATIENTS AND METHODS

The study involved 95 Middle European pediatric hospitals. We collected blood samples from, and clinical information about, 285 previously healthy children with meningococcal infection. We used a newly developed multiplexed mutagenic separated PCR assay to analyze 6 polymorphisms within the IL1 cluster: IL1A (-889)C/T, IL1A (+4845)G/T, IL1B (-511)C/T, IL1B (-31)C/T, IL1B (+3954), and IL1RA (+2018)C/T. We studied the same polymorphisms in a comparison group of 481 healthy newborns.

RESULTS

Genotype frequencies between patients and the comparison group differed significantly only for the IL1RA (+2018)C/T variant: The CC genotype was more frequent in patients (11%) than in healthy controls (5%; P = 0.008). In the patient group, the C allele was significantly more prevalent (67%) in nonsurvivors than in survivors (42%; P = 0.02).

CONCLUSION

The IL1RA (+2018)C/T polymorphism is associated with the risk of meningococcal disease and with its outcome.

Identification of Genes for a Complex Trait: Examples from Hypertension

Essential hypertension (EH) affects approximately 20% of the adult population, and has a multifactorial origin arising from an interaction between susceptibility genes and environmental factors. Several strategies and methods have been used to identify hypertension susceptibility genes. This review is thought to highlight current strategies for a better understanding of their limitations and strengths in a complex trait like EH. Linkage analysis is less effective at identifying common variants with modest effects typical for complex traits, and has therefore proved to be largely unsuccessful in EH. No candidate gene was assessed by a human linkage study so far. Possible redesigns of the linkage approach for complex diseases may include larger sample sizes and dense marker maps. Genetic association studies may be an effective approach to the problems posed by complex traits. With the explosion of genotyping technologies, genome-wide association studies have become feasible, and small-scale association studies have become plentiful. The different types of association studies are reviewed and issues that are important to consider when interpreting association studies of complex traits are discussed. Properly defined phenotypes, large enough sample cohorts to achieve sufficient statistical power, carefully matched samples to avoid population stratification are all integral parts of a high-quality association study. Multiple testing often results in false-positive results by chance, and inconclusive results may arise from ignoring linkage disequilibrium of the tested polymorphism, an effect avoidable by haplotype analysis. A new evolutionary development of the candidate gene approach is introduced which will extent traditional association study settings gaining better understanding of complex diseases like hypertension and might give better chances to evaluate association studies for their functional relevance.

4G/5G promoter polymorphism in the plasminogen-activator-inhibitor-1 gene in children with systemic meningococcaemia

Meningococcal disease may present as sepsis, meningitis or a combination of both. Impaired fibrinolysis and massive elevation of the plasminogen activator inhibitor-1 (PAI-1) is a characteristic feature of meningococcal sepsis. Previously, an association between mortality and the functional 4G/5G promoter polymorphism of the PAI-1gene in a cohort of UK and Dutch children with meningococcal sepsis was reported. We carried out a prospective, multicentre study to investigate the association of the 4G/5G PAI-1 polymorphism, diagnosis, and outcome in meningococcal disease in a Central European and UK population. Blood samples and clinical information of 347 previously healthy children with meningococcal infection were collected from 95 paediatric hospitals in Germany, Switzerland, Italy, the United Kingdom, and Austria from 2000 until 2002. Mortality was significantly associated with the 4G/4G genotype (12 of 90 (13%) vs. 15 of 240 (6%), P = 0.037), resulting in an odds ratio of 2.31. The diagnosis of sepsis (independent of symptoms of meningitis) was significantly more frequent in carriers of the 4G/4G genotype (P = 0.01), resulting in an odds ratio of 2.21 to develop sepsis. Meningitis was not associated with the PAI-1 4G/5G polymorphism, and allele frequencies were similar in patient and control groups.

CONCLUSION

Our data show a correlation between the 4G/4G genotype in the plasminogen activator inhibitor-1 gene and poor outcome in children with meningococcal infection. In addition, 4G homozygous patients were prone to develop sepsis. We found no influence of the plasminogen activator inhibitor-1 polymorphism on the susceptibility to invasive meningococcal infection.

Interaction between histamine-induced itch and experimental muscle pain

Itch sensation can be inhibited by simultaneously applied cutaneous pain at the same skin site via a central mechanism. Deep muscle pain is often associated with sensory changes in the corresponding dermatome. We investigated whether experimentally induced muscle pain has any influence on histamine-induced itch and vice versa in a double blind placebo-controlled study. Experiments were performed in 18 healthy subjects. In nine individuals control iontophoresis of histamine into the forearm produced a distinct itch sensation. Another nine individuals participated in an additional experiment in which histamine and saline were iontophoresed on the forearm in a randomized double-blinded two-way crossover design after intramuscular injection of capsaicin into the ipsilateral brachioradial muscle. Capsaicin-induced muscle pain reduced itch sensation significantly. In contrast, capsaicin-induced muscle pain increased significantly after cutaneous histamine application compared to muscle pain after iontophoresis of saline (placebo). These novel data indicate that muscle pain inhibits itch and histamine increases muscle pain. A bi-directional interaction between cutaneous histamine-sensitive afferents and nociceptive muscle afferents via central mechanisms is suggested.