Temporomandibular Joint Disorder Complaints in Tinnitus: Further Hints for a Putative Tinnitus Subtype

OBJECTIVE: Tinnitus is considered to be highly heterogeneous with respect to its etiology, its comorbidities and the response to specific interventions. Subtyping is recommended, but it remains to be determined which criteria are useful, since it has not yet been clearly demonstrated whether and to which extent etiologic factors, comorbid states and interventional response are related to each other and are thus applicable for subtyping tinnitus. Analyzing the Tinnitus Research Initiative Database we differentiated patients according to presence or absence of comorbid temporomandibular joint (TMJ) disorder complaints and compared the two groups with respect to etiologic factors. METHODS: 1204 Tinnitus patients from the Tinnitus Research Initiative (TRI) Database with and without subjective TMJ complaints were compared with respect to demographic, tinnitus and audiological characteristics, questionnaires, and numeric ratings. Data were analysed according to a predefined statistical analysis plan. RESULTS: Tinnitus patients with TMJ complaints (22% of the whole group) were significantly younger, had a lower age at tinnitus onset, and were more frequently female. They could modulate or mask their tinnitus more frequently by somatic maneuvers and by music or sound stimulation. Groups did not significantly differ for tinnitus duration, type of onset (gradual/abrupt), onset related events (whiplash etc.), character (pulsatile or not), hyperacusis, hearing impairment, tinnitus distress, depression, quality of life and subjective ratings (loudness etc.). CONCLUSION: Replicating previous work in tinnitus patients with TMJ complaints, classical risk factors for tinnitus like older age and male gender are less relevant in tinnitus patients with TMJ complaints. By demonstrating group differences for modulation of tinnitus by movements and sounds our data further support the notion that tinnitus with TMJ complaints represents a subgroup of tinnitus with clinical features that are highly relevant for specific therapeutic management

Paired Associative Stimulation of the Auditory System: A Proof-Of-Principle Study

Background Paired associative stimulation (PAS) consisting of repeated application of transcranial magnetic stimulation (TMS) pulses and contingent exteroceptive stimuli has been shown to induce neuroplastic effects in the motor and somatosensory system. The objective was to investigate whether the auditory system can be modulated by PAS. Methods Acoustic stimuli (4 kHz) were paired with TMS of the auditory cortex with intervals of either 45 ms (PAS(45 ms)) or 10 ms (PAS(10 ms)). Two-hundred paired stimuli were applied at 0.1 Hz and effects were compared with low frequency repetitive TMS (rTMS) at 0.1 Hz (200 stimuli) and 1 Hz (1000 stimuli) in eleven healthy students. Auditory cortex excitability was measured before and after the interventions by long latency auditory evoked potentials (AEPs) for the tone (4 kHz) used in the pairing, and a control tone (1 kHz) in a within subjects design. Results Amplitudes of the N1-P2 complex were reduced for the 4 kHz tone after both PAS(45 ms) and PAS(10 ms), but not after the 0.1 Hz and 1 Hz rTMS protocols with more pronounced effects for PAS(45 ms). Similar, but less pronounced effects were observed for the 1 kHz control tone. Conclusion These findings indicate that paired associative stimulation may induce tonotopically specific and also tone unspecific human auditory cortex plasticity

A microscopic semiclassical confining field equation for U(1)U(1) lattice gauge theory in 2+1 dimensions

We present a semiclassical nonlinear field equation for the confining field in 2+1--dimensional $U(1)$ lattice gauge theory (compact QED). The equation is derived directly from the underlying microscopic quantum Hamiltonian by means of truncation. Its nonlinearities express the dynamic creation of magnetic monopole currents leading to the confinement of the electric field between two static electric charges. We solve the equation numerically and show that it can be interpreted as a London relation in a dual superconductor.Comment: 21 pages, epsf postscript figures included, full postscript available at ftp://ftp.th.physik.uni-frankfurt.de/pub/cbest/micro.ps.Z or http://www.th.physik.uni-frankfurt.de/~cbest/pub.htm

Non-invasive electrical and magnetic stimulation of the brain, spinal cord, roots and peripheral nerves: Basic principles and procedures for routine clinical and research application. An updated report from an I.F.C.N. Committee

These guidelines provide an up-date of previous IFCN report on "Non-invasive electrical and magnetic stimulation of the brain, spinal cord and roots: basic principles and procedures for routine clinical application" (Rossini et al., 1994). A new Committee, composed of international experts, some of whom were in the panel of the 1994 "Report", was selected to produce a current state-of-the-art review of non-invasive stimulation both for clinical application and research in neuroscience. Since 1994, the international scientific community has seen a rapid increase in non-invasive brain stimulation in studying cognition, brain-behavior relationship and pathophysiology of various neurologic and psychiatric disorders. New paradigms of stimulation and new techniques have been developed. Furthermore, a large number of studies and clinical trials have demonstrated potential therapeutic applications of non-invasive brain stimulation, especially for TMS. Recent guidelines can be found in the literature covering specific aspects of non-invasive brain stimulation, such as safety (Rossi et al., 2009), methodology (Groppa et al., 2012) and therapeutic applications (Lefaucheur et al., 2014). This up-dated review covers theoretical, physiological and practical aspects of non-invasive stimulation of brain, spinal cord, nerve roots and peripheral nerves in the light of more updated knowledge, and include some recent extensions and developments

augustin

Green tea catechins (GTC) have been shown to inhibit the activities of enzymes involved in folate uptake. Hence, regular green tea drinkers may be at risk of impaired folate status. The present experiments aimed at studying the impact of dietary GTC on folate concentrations and metabolism. In a human pilot study (parallel design) healthy men consumed for 3 weeks 6 capsules (~670 mg GTC) per day (2 capsules with each principal meal) containing aqueous extracts of the leaves of Camellia sinensis (n=17) or placebo (n=16). No differences in plasma folate concentrations were observed between treatments. We further fed groups of 10 male rats diets fortified with 0, 0.05, 0.5, 1, or 5 g GTC/kg for 6 weeks. Only at the highest intake, GTC significantly decreased serum 5-methyl-tetrahydrofolate concentrations in rats, while mRNA concentrations of reduced folate carrier, proton-coupled folate transporter/heme carrier protein 1, and dihydrofolate reductase (DHFR) remained unchanged in intestinal mucosa. Using an in vitro enzyme activity assay, we observed a time-and dose-dependent inhibition of DHFR activity by epigallocatechin gallate and a green tea extract. Our data suggest that regular green tea consumption is unlikely to impair folate status in healthy males, despite the DHFR inhibitory activity of GTC. K e y w o r d s : folates, catechins, bioavailability, human, rat MATERIAL AND METHODS Dihydrofolate reductase activity The inhibition of human dihydrofolate reductase (DHFR) activity by (-) epigallocatechin gallate (EGCG) and a standardized green tea extract (Polyphenon 60 (P60); Sigma Chemical Co., St Louis, MO, USA) was measured using a commercial dihydrofolate reductase assay kit (Sigma-Aldrich) according to the manufacturer's protocol. Methotrexate, a well-known competitive DHFR inhibitor was used as a positive control. EGCG and P60 were dissolved in ultra pure-water (containing 1% ascorbic acid (w/v) (Merck KGaA, Darmstadt, Germany) to stabilize the catechins) on the day of the experiments. DHFR was used at a final activity of 1.5 x 10 -3 units per reaction. Final concentrations of EGCG and methotrexate were 1000, 100 and 10 nmol/L per reaction. P60 was used at final concentrations of 1428 .57, 142.86, and 14.29 µg/L and, thus, contained 1060 , 106, and 10.6 nmol/L EGCG and 1427.3 nmol/L of the gallated catechins (EGCG, ECG and gallocatechin gallate), respectively. Rat study Fifty male Wistar rats (Harlan Winkelmann GmbH, Borchen, Germany) with an initial body weight of 99.8 ± 2.0 g (mean ± SEM) were randomized into 5 groups of 10 animals each and housed pair-wise with sawdust bedding under controlled environmental conditions (23 ± 2°C and 65 ± 5% relative humidity, 12 h dark-light cycle). The rats were kept for 5 days on a folate-adjusted rat diet for growing animals containing 2 mg of folic acid/kg (C1027; Altromin GmbH, Lage, Germany) and thereafter received their respective experimental diets consisting of the standard diet supplemented with 0, 0.05, 0.5, 1, or 5 g green tea catechins per kg diet using P60 as the source of catechins (see The animal experiment was conducted in accordance with the German Guidelines and Regulations on Animal Care (Deutsches Tierschutzgesetz, 2006) and was approved by the University of Kiel Ethics Committee on Animal Care. Human pilot study Healthy males were recruited by advertisement at the University and local community of Reading (United Kingdom) and amongst volunteers who previously participated in nutritional trials at the Hugh Sinclair Human Nutrition Unit. Inclusion criteria were: male gender, 18-55 y of age, and a BMI in the range of 22-32 kg/m 2 . Subjects were excluded from the trial if they were diagnosed with any illness or on long-term medication, used dietary supplements, participated in >5 h of aerobic exercise activity per week, or were involved in a clinical trial within 3 months prior to the study. The study protocol was approved by the University of Reading ethics committee and all subjects gave written informed consent before participation. A standardized aqueous green tea extract prepared from the leaves of Camellia sinensis L. (a kind gift of Cognis Deutschland GmbH & Co KG, Monheim am Rhein, Germany) was used to make the green tea extract (GTE) capsules. The composition of the GTE is given in The trial was designed as a double-blind placebo-controlled parallel study. Thirty-one volunteers were randomly assigned to one of two treatment groups (GTE, n=16 or placebo, n=15) with similar BMI and age (data not shown). Subjects took 6 capsules per day, two with each principal meal, for 3 weeks and were instructed to limit their daily tea and coffee consumption to ≤ 3 cups, but to otherwise maintain their normal diet and exercise patterns. Compliance was determined by counting of the returned capsules at the end of the trial and was high (>98%). Blood samples (20 ml) were drawn into tubes containing 0.05 mL 15% K 3 EDTA (Vacutainer; Becton Dickinson UK Ltd., Oxford, UK) after an overnight fast on the first and last day of the intervention period. Plasma was immediately obtained by centrifugation (1,000 x g, 10 min) and 3 ml aliquots were stored at -80°C until analysis. Folate quantification by HPLC Procedures for extraction and purification of folates from human plasma and rat serum and liver samples by strong anion exchange solid-phase extraction were described previously by Witthoft et al. (18). Dialysed rat serum (500 µl/g) was used to ensure complete deconjugation of folate polyglutamates in liver samples; modified from Patring et al. (19). Analyses were performed using an HPLC system (Agilent 1100) consisting of a 104 10-formyltetrahydrofolate (10-HCO-H 4 folate), and 5,10-methenyltetrahydrofolate (5,10-CH + -H 4 folate) (a gift of Merck Eprova AG, Schaffhausen, Switzerland, except 10-HCO-H 4 folate, which was purchased from Schircks Laboratories, Jona, Switzerland). Quantification was based on a multilevel (n=7) external calibration curve with a linear range over 1.2-118.0 ng/mL for H 4 folate, 0.6-93.1 ng/mL for 5-CH 3 -H 4 folate, 0.9-184.1 ng/mL for 10-HCO-H 4 folate and 9.3-184.5 ng/mL for 5,10-CH + -H 4 folate. mRNA quantification RNA was isolated from rat duodenal mucosa using the RNeasy Lipid Tissue Kit (Qiagen GmbH, Hilden, Germany) according to the manufacturer's protocol. DNA digestion was performed with RNase-Free DNase Set (Qiagen). RNA integrity was checked by electrophoresis on a denaturing agarose gel and ethidium bromide staining. The concentration and purity of isolated RNA was determined by measuring the absorbance (AB) at 260 and 280 nm in a spectrophotometer (DU800, Beckmann Instruments; Munich, Germany). A ratio of >1.8 between AB 260nm and AB 280nm was considered as acceptable. RNA aliquots were stored at -80°C until analysis. Primer pairs of β-actin, reduced folate carrier (RFC) and proton-coupled folate transporter/heme carrier protein-1 (PCFT/HCP1) were designed to the corresponding sequences of Rattus norvegicus mRNA with Primer3 software (http://frodo.wi.mit.edu/cgi-bin/primer3/ primer3_www.cgi; 03.05.2007) and purchased from MWGBiotech AG (Ebersberg, Germany). The sequences of primers used in this study were as follows: Sense primer for β-actin, 5´-GGGGTGTTGAAGGTCTCAAA-3´, antisense primer for β-actin, 5´-TGTCACCAACTGGGACGATA-3´; sense primer for RFC, 5´-GGCTCGTGTTCTACCTCTGC-3´, antisense primer for RFC, 5´-GGTAGTCGGTGAGCAGGAAG-3´; sense primer for PCFT/HCP1, 5´-TGAGCTAAGCACACCCCTCT-3´, antisense primer for PCFT/HCP1, 5´-TCCGTACCCTGTGAACATGA-3´. The product size was 90 base pair (bp) for β-actin; 183 bp for RFC and 217 bp for PCFT/HCP1. QuantiTect ® Primer Assay (Qiagen) was used for DHFR mRNA amplification, with a product size of 88 bp. For one-step quantitative reverse transcriptase polymerase chain reaction (one-step qRT-PCR) two aliquots of RNA were amplified. External relative standard curves of total RNA were determined with each run. Data was normalized by dividing the concentrations of RFC, PCFT/HCP1 or DHFR by the concentrations of β-actin mRNA. Each PCR reaction (final volume 20 µl) contained 0.5 µmol/L of each primer, 10 µl of 2x QuantiTect ® SYBR ® Green RT-PCR Master Mix (Qiagen), 0.2 µl QuantiTect RT-Mix (Qiagen), 8 µl of RNA dilution and 1.4 µl water. Real-time cycler conditions were set according to the manufacturers protocol to 40 cycles with annealing temperatures of 56°C for β-actin, 59°C for RFC, 56°C for PCFT/HCP1 and 55°C for DHFR, respectively. Quantification and melting curves of the amplified products were analysed using the RotorGene 6.0 software (Corbett Lifescience; Sydney, Australia). Melting curve analyses and agarose gel electrophoresis with ethidium bromide staining were performed to exclude non-specific products. Statistical analyses Statistical calculations were performed with GraphPad Prism 4 software (GraphPad Software Inc., San Diego, CA, USA). Analyses of the data from the rat study and the in vitro assay were performed by means of a one-way ANOVA followed by Dunnetts test for multiple comparisons of group means between animals receiving GTC or control diet. Analyses of the data from the human pilot study were performed by means of a paired Student's t-test for comparison of baseline vs. treatment and by means of an unpaired Student's t-test for comparisons between subjects receiving GTE or placebo. Reported values are means ± SEM and effects were considered significant at P<0.05. RESULTS Dihydrofolate reductase activity in vitro Both pure EGCG and P60, at concentrations of 1000 for EGCG and 1060 nmol/L for EGCG from P60, respectively, time-dependently inhibited DHFR activity Serum and liver folate concentrations in rats Feed consumption and final body mass (318.7 ± 4.8 g) of the Wistar rats were similar in all groups. Intake of diets containing 0.5% GTC over a period of 42 days significantly decreased the serum concentration of 5-CH 3 -H 4 folate compared to control rats, whereas the concentrations of H 4 folate remained unchanged ( Relative mRNA levels of reduced folate carrier and dihydrofolate reductase in rat duodenal mucosa The housekeeping gene β-actin was expressed at similar levels in all animals and no significant differences in the relative mRNA levels of RFC, PCFT/HCP1 or DHFR in the duodenal mucosa were observed Plasma folate concentrations in humans Consumption of 670 mg of GTC per day or placebo did not affect plasma folate concentrations in healthy male volunteers. No significant differences in plasma concentrations of 5-CH 3 -H 4 folate were observed between the treatment groups at baseline (placebo, 16.3 ± 2.6 nmol/L; GTE, 19.1 ± 2.4 nmol/L) or after intervention (placebo, 15.5 ± 2.1 nmol/L; GTE, 17.6 ± 2.4 nmol/L). DISCUSSION Green tea is a widely consumed beverage in many countries and contains appreciable amounts of polyphenols. Catechins (flavanols) are the major subclass of bioactive compounds within the polyphenol fraction of green tea. Epidemiological studies associated a high dietary intake of catechins with a reduced risk to suffer from a variety of diseases (reviewed in 20), including certain forms of cancer (21). The underlying molecular and cellular mechanisms by which green tea catechins may mediate anticarcinogenic acitivty seem to be diverse: Cell culture experiments as well as studies in rodents indicate that green tea catechin may inhibit angiogenesis via a down-regulation of vascular endothelial growth factor (reviewed in 22). Furthermore it has been suggested that the anticancer activity of green tea catechins against different kind of cancers may find an explanation in direct targeting of lipid rafts (23). Recent in vitro studies have shown that epigallocatechin gallate (EGCG), the predominant catechin in green tea, competitively inhibits the enzyme dihydrofolate reductase (DHFR) (9, 13). DHFR inhibition is the mechanism by which so-called antifolates, such as the cytostatic drug methotrexate, inhibit cell division and reduce tumor growth (15, 24). Co-administration of folic acid and the DHFR inhibitors methotrexate and pyrimethamine, respectively, reduced plasma folate concentrations in rats The commercial green tea extract Polyphenon 60 (P60) used in the rat study and its principle bioactive ingredient EGCG inhibited DHRF activity time-and concentration-dependently in vitro In order to study whether or not the effects observed in vitro bear a meaning for the more complex physiological processes in vivo, Wistar rats were fed for 42 days with diets fortified with increasing concentrations of green tea catechins (GTC) using a standardized green tea extract (P60). The diets contained 2 mg folic acid per kg, which is equivalent to twice the dietary recommendations for laboratory rats as given by the National Research Council (28). It is noteworthy that folates synthesized by the microflora of the large intestine are absorbed and may significantly contribute to blood folate concentrations (reviewed in 29). The diet used in this study was therefore formulated to provide a minimum of substrate to the intestinal microflora to limit bacterial folate synthesis. Only in those animals fed the highest concentrations of the green tea extract (0.5% GTC), did we observe a significant decrease in serum 5-CH 3 -H 4 folate concentrations as compared to the control group ( At a given substrate affinity and substrate concentration, the capacity of enzymatic turnover of folates as well as the amount of their carrier-mediated transport across cellular membranes is mainly affected by the amount of enzymes/carriers present at the tissue level. Because catechins are known to alter the gene expression for a variety of proteins (35), we quantified relative mRNA concentrations of the RFC, PCFT/HCP1, and DHFR in the duodenal mucosa of rats fed GTC. No significant differences in mRNA concentrations of RFC, PCFT/HCP1, and of DHFR were found between the experimental groups The current findings suggested that GTC might decrease serum folate concentrations only if supplied at supra-nutritional doses. A 70 kg human would have to drink almost 100 cups of green tea infusion per day to match the highest dose fed to rats in the present study. Because such a human study would be unfeasible as well as unrealistic, we designed a pilot study with a standardized green tea extract to assess whether or not regular consumption of high doses of GTC might affect plasma folate concentrations in humans. The intake of 670 mg of GTC per day, which corresponds to about 20 cups of green tea, caused no significant differences in plasma concentrations of 5-CH 3 -H 4 folate between the treatment and placebo groups, both of which consuming a normal diet containing on average ~328 ± 26 µg folate/d. Insufficient dietary intake of folates for as short as 2-3 weeks has been reported to result in reduced blood concentrations of the vitamin (30). Our findings therefore suggest that green tea drinking is unlikely to affect plasma folate concentrations in healthy, free-living subjects and that a longer treatment period and/or even higher doses of dietary GTC may be necessary to induce changes in folate concentrations, if possible at all. Further human studies with GTC and a standardized supply of folic acid (in the absence of naturally occurring reduced folates) are warranted to investigate the influence of GTC on DHFR activity in vivo. In addition, the measurement of (oxidized) serum folic acid should be considered because folic acid has been found in serum of subjects consuming folic acid-fortified foods for 5 d (11). Based on the experiments presented here, it appears unlikely that daily green tea consumption, even at high levels, may affect folate concentrations in healthy humans. Acknowledgement

Abnormal resting-state cortical coupling in chronic tinnitus

<p>Abstract</p> <p>Background</p> <p>Subjective tinnitus is characterized by an auditory phantom perception in the absence of any physical sound source. Consequently, in a quiet environment, tinnitus patients differ from control participants because they constantly perceive a sound whereas controls do not. We hypothesized that this difference is expressed by differential activation of distributed cortical networks.</p> <p>Results</p> <p>The analysis was based on a sample of 41 participants: 21 patients with chronic tinnitus and 20 healthy control participants. To investigate the architecture of these networks, we used phase locking analysis in the 1–90 Hz frequency range of a minute of resting-state MEG recording. We found: 1) For tinnitus patients: A significant decrease of inter-areal coupling in the alpha (9–12 Hz) band and an increase of inter-areal coupling in the 48–54 Hz gamma frequency range relative to the control group. 2) For both groups: an inverse relationship (r = -.71) of the alpha and gamma network coupling. 3) A discrimination of 83% between the patient and the control group based on the alpha and gamma networks. 4) An effect of manifestation on the distribution of the gamma network: In patients with a tinnitus history of less than 4 years, the left temporal cortex was predominant in the gamma network whereas in patients with tinnitus duration of more than 4 years, the gamma network was more widely distributed including more frontal and parietal regions.</p> <p>Conclusion</p> <p>In the here presented data set we found strong support for an alteration of long-range coupling in tinnitus. Long-range coupling in the alpha frequency band was decreased for tinnitus patients while long-range gamma coupling was increased. These changes discriminate well between tinnitus and control participants. We propose a tinnitus model that integrates this finding in the current knowledge about tinnitus. Furthermore we discuss the impact of this finding to tinnitus therapies using Transcranial Magnetic Stimulation (TMS).</p

Open Problems in (Hyper)Graph Decomposition

Large networks are useful in a wide range of applications. Sometimes problem instances are composed of billions of entities. Decomposing and analyzing these structures helps us gain new insights about our surroundings. Even if the final application concerns a different problem (such as traversal, finding paths, trees, and flows), decomposing large graphs is often an important subproblem for complexity reduction or parallelization. This report is a summary of discussions that happened at Dagstuhl seminar 23331 on "Recent Trends in Graph Decomposition" and presents currently open problems and future directions in the area of (hyper)graph decomposition

Short and Intense Tailor-Made Notched Music Training against Tinnitus: The Tinnitus Frequency Matters

Tinnitus is one of the most common diseases in industrialized countries. Here, we developed and evaluated a short-term (5 subsequent days) and intensive (6 hours/day) tailor-made notched music training (TMNMT) for patients suffering from chronic, tonal tinnitus. We evaluated (i) the TMNMT efficacy in terms of behavioral and magnetoencephalographic outcome measures for two matched patient groups with either low (≤8 kHz, N = 10) or high (>8 kHz, N = 10) tinnitus frequencies, and the (ii) persistency of the TMNMT effects over the course of a four weeks post-training phase. The results indicated that the short-term intensive TMNMT took effect in patients with tinnitus frequencies ≤8 kHz: subjective tinnitus loudness, tinnitus-related distress, and tinnitus-related auditory cortex evoked activity were significantly reduced after TMNMT completion. However, in the patients with tinnitus frequencies >8 kHz, significant changes were not observed. Interpreted in their entirety, the results also indicated that the induced changes in auditory cortex evoked neuronal activity and tinnitus loudness were not persistent, encouraging the application of the TMNMT as a longer-term training. The findings are essential in guiding the intended transfer of this neuro-scientific treatment approach into routine clinical practice

Diclofenac Hypersensitivity: Antibody Responses to the Parent Drug and Relevant Metabolites

Background: Hypersensitivity reactions against nonsteroidal antiinflammatory drugs (NSAIDs) like diclofenac (DF) can manifest as Type I-like allergic reactions including systemic anaphylaxis. However, except for isolated case studies experimental evidence for an IgE-mediated pathomechanism of DF hypersensitivity is lacking. In this study we aimed to investigate the possible involvement of drug-and/or metabolite-specific antibodies in selective DF hypersensitivity. Methodology/Principal Findings: DF, an organochemically synthesized linkage variant, and five major Phase I metabolites were covalently coupled to carrier proteins. Drug conjugates were analyzed for coupling degree and capacity to crosslink receptor-bound IgE antibodies from drug-sensitized mice. With these conjugates, the presence of hapten-specific IgE antibodies was investigated in patients' samples by ELISA, mediator release assay, and basophil activation test. Production of sulfidoleukotrienes by drug conjugates was determined in PBMCs from DF-hypersensitive patients. All conjugates were shown to carry more than two haptens per carrier molecule. Immunization of mice with drug conjugates induced drug-specific IgE antibodies capable of triggering mediator release. Therefore, the conjugates are suitable tools for detection of drug-specific antibodies and for determination of their anaphylactic activity. Fifty-nine patients were enrolled and categorized as hypersensitive either selectively to DF or to multiple NSAIDs. In none of the patients' samples evidence for drug/metabolite-specific IgE in serum or bound to allergic effector cells was found. In contrast, a small group of patients (8/59, 14%) displayed drug/metabolite-specific IgG. Conclusions/Significance: We found no evidence for an IgE-mediated effector mechanism based on haptenation of protein carriers in DF-hypersensitive patients. Furthermore, a potential involvement of the most relevant metabolites in DF hypersensitivity reactions could be excluded