Quantitative sensory testing in the German Research Network on Neuropathic Pain (DFNS): somatosensory abnormalities in 1236 patients with different neuropathic pain syndromes

Neuropathic pain is accompanied by both positive and negative sensory signs. To explore the spectrum of sensory abnormalities, 1236 patients with a clinical diagnosis of neuropathic pain were assessed by quantitative sensory testing (QST) following the protocol of DFNS (German Research Network on Neuropathic Pain), using both thermal and mechanical nociceptive as well as non-nociceptive stimuli. Data distributions showed a systematic shift to hyperalgesia for nociceptive, and to hypoesthesia for non-nociceptive parameters. Across all parameters, 92% of the patients presented at least one abnormality. Thermosensory or mechanical hypoesthesia (up to 41%) was more frequent than hypoalgesia (up to 18% for mechanical stimuli). Mechanical hyperalgesias occurred more often (blunt pressure: 36%, pinprick: 29%) than thermal hyperalgesias (cold: 19%, heat: 24%), dynamic mechanical allodynia (20%), paradoxical heat sensations (18%) or enhanced wind-up (13%). Hyperesthesia was less than 5%. Every single sensory abnormality occurred in each neurological syndrome, but with different frequencies: thermal and mechanical hyperalgesias were most frequent in complex regional pain syndrome and peripheral nerve injury, allodynia in postherpetic neuralgia. In postherpetic neuralgia and in central pain, subgroups showed either mechanical hyperalgesia or mechanical hypoalgesia. The most frequent combinations of gain and loss were mixed thermal/mechanical loss without hyperalgesia (central pain and polyneuropathy), mixed loss with mechanical hyperalgesia in peripheral neuropathies, mechanical hyperalgesia without any loss in trigeminal neuralgia. Thus, somatosensory profiles with different combinations of loss and gain are shared across the major neuropathic pain syndromes. The characterization of underlying mechanisms will be needed to make a mechanism-based classification feasible.

Maternal interleukin-6 (-174) C/C polymorphism is associated with chorioamnionitis and cystic periventricular leucomalacia of the preterm infant

OBJECTIVE

To evaluate the association between maternal interleukin (IL)-6 G(-174)C polymorphism and cystic periventricular leukomalacia (cPVL) of the preterm newborn.

STUDY DESIGN

After searching a local database, we recruited 132 preterm infants with diagnosis of cPVL, 44 Caucasian mothers were also recruited to participate in this candidate gene-association study at a single teritary care center. Data related to maternal IL-6 G(-174)C polymorphisms were compared with 41 controls, and furthermore compared with data from umbilical cord blood samples from a consecutive birth cohort of 395 healthy newborns, and published data from Caucasian populations including 1104 adults, respectively. In addition, subgroup analysis was performed in cases with either history of preterm premature rupture of the membranes (PPROM) or clinical chorioamnionitis (CCA). IL-6 genotyping was performed using an allele-specific polymerase chain reaction technique.

RESULT

Frequencies of the IL-6 G(-174)C polymorphisms did not differ between cases (GG, 29.5%; GC, 54.5% and CC, 15.9%) and controls (GG, 34.2; GC, 51.2 and CC, 14.6%). Subgroup analysis of 31 cases with history of PPROM (GG, 25.8; GC, 54.8 and CC 19.4%) and controls did not reveal significant differences, but a significantly higher frequency of the CC genotype was found in 23 cases with a history of CCA (34.8%) compared with controls by either univariate (P=0.032; odds ratio 3.11, 95% confidence interval (CI) 1.11 to 8.68) or multivariate analysis (P=0.049, odds ratio 2.54, 95% CI 1.01 to 6.45). These data were confirmed by a comparing the CC genotype frequency to 395 term controls (CC 14.7%, P=0.005) and to the mean CC genotype frequency of 1104 Caucasian adults (CC 15.6%, P<0.0001).

CONCLUSION

Frequencies of the IL-6 G(-174)C polymorphisms did not differ between groups. Subgroup analysis revealed an association of the CC genotype with CCA and cPVL in the preterm newborn.

Photosystem I reaction center from the thermophilic cyanobacterium Mastigocladus laminosus

Photosystem I reaction center was isolated from the cyanobacterium Mastigocladus laminosus. It contained four different subunits with molecular masses (as determined by sodium dodecyl sulfate gels) of about 70,000 (subunit I), 16,000 (subunit II), 11,000 (subunit III), and 10,000 (subunit IV) daltons. The purified reaction center contained about 100 chlorophyll a molecules per P(700); however, they could be readily depleted down to about 50 chlorophyll a per P(700) without loss in the photochemical activities. The reaction center was active in cytochrome c photooxidation, but the photooxidation of an acidic cytochrome, like the Euglena cytochrome 552, required the presence of cations. The purified reaction center was found to be similar in several respects to the photosystem I reaction centers from higher plants and, especially, to the one isolated from green algae. Subunit I appeared on sodium dodecyl sulfate gels in the same position and possessed the same shape of an apparent double band as the corresponding subunits I of green plants and of algae. Subunits I and II of photosystem I reaction centers from Mastigocladus, higher plants, and green algae showed immunological crossreactivity. This observation might serve as biochemical evidence for the common evolution of the photosystem I reaction centers. In higher plants and green algae subunit II is a product of cytoplasmic ribosomes and therefore, a high degree of homology should have been preserved upon transfer of its gene from the prokaryote to the nucleus of the eukaryotes.

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.