[Increased report completeness and satisfaction with structured neurotological reporting in the interdisciplinary assessment of vertigo]. / Erhöhte Befundvollständigkeit und gesteigerte Zuweiserzufriedenheit bei strukturierter neurootologischer Befunderhebung in der interdisziplinären Schwindelabklärung.

BACKGROUND: Results of neurotological function diagnostics in the context of interdisciplinary vertigo assessment are usually formulated as free-text reports (FTR). These are often subject to high variability, which may lead to loss of information. The aim of the present study was to evaluate the completeness of structured reports (SR) and referrer satisfaction in the neurotological assessment of vertigo. MATERIALS AND METHODS: Neurotological function diagnostics performed as referrals (n = 88) were evaluated retrospectively. On the basis of the available raw data, SRs corresponding to FTRs from clinical routine were created by means of a specific SR template for neurotological function diagnostics. FTRs and SRs were evaluated for completeness and referring physician satisfaction (n = 8) using a visual analog scale (VAS) questionnaire. RESULTS: Compared to FTRs, SRs showed significantly increased overall completeness (73.7% vs. 51.7%, p < 0.001), especially in terms of patient history (92.5% vs. 66.7%, p < 0.001), description of previous findings (87.5% vs. 38%, p < 0.001), and neurotological (33.5% vs. 26.7%, p < 0.001) and audiometric function diagnostics (58% vs. 32.3%, p < 0.001). In addition, SR showed significantly increased referring physician satisfaction (VAS 8.8 vs. 4.9, p < 0.001). CONCLUSION: Neurotological SRs enable a significantly increased report completeness with higher referrer satisfaction in the context of interdisciplinary assessment of vertigo. Furthermore, SRs are particularly suitable for scientific data analysis, especially in the context of big data analyses.

Bone conducted vibration is an effective stimulus for otolith testing in cochlear implant patients.

BACKGROUND: Treatment with a cochlear implant (CI) poses the risk of inducing a behaviorally unmeasurable air-bone gap leading to false negative absence of cervical and ocular vestibular evoked myogenic potentials (cVEMPs, oVEMPs) to air conducted sound (ACS). OBJECTIVE: To investigate VEMP response rates to ACS and bone conducted vibration (BCV) in CI patients and the applicability of the B81 transducer for BCV stimulation. METHODS: Prospective experimental study including unilateral CI patients, measuring cVEMPs and oVEMPs to ACS and to BCV, comparing response rates, signed asymmetry ratios, latencies, and amplitudes. RESULTS: Data of 13 CI patients (mean age 44±12 years) were analyzed. For the CI side, oVEMP and cVEMP response rates were significantly higher for BCV (77%cVEMP, 62%oVEMP) compared to ACS (23%cVEMP, 8%oVEMP). For the contralateral side, no difference between response rates to ACS (85%cVEMP, 69%oVEMP) and BCV (85%cVEMP, 77%oVEMP) was observed. Substantially higher asymmetries were observed for ACS (-88±23%for cVEMPs, -96±11%for oVEMPs) compared to BCV (-12±45%for cVEMPs, 4±74%for oVEMPs). CONCLUSIONS: BCV is an effective stimulus for VEMP testing in CI patients. The B81 is a feasible stimulator.

Management of transmodiolar and transmacular cochleovestibular schwannomas with and without cochlear implantation.

INTRODUCTION: Hearing rehabilitation with cochlear implants has attracted increasing interest also for patients with cochleovestibular schwannoma. The authors report their experience with the surgical management of tumors with rare transmodiolar or transmacular extension and outcomes after cochlear implantation (CI). METHODS: This retrospective case series included nine patients with either primary intralabyrinthine tumors or secondary invasion of the inner ear from the internal auditory canal. The primary endpoint with CI, performed in six patients, was word recognition score at 65 dB SPL (sound pressure level). Secondary endpoints were intra- and postoperative electrophysiological parameters, impedance measures, the presence of a wave V in the electrically evoked (via the CI) auditory brainstem responses, the specifics of postoperative CI programming, and adverse events. RESULTS: Hearing rehabilitation with CI in cases of transmodiolar tumor growth could be achieved only with incomplete tumor removal, whereas tumors with transmacular growth could be completely removed. All six patients with CI had good word recognition scores for numbers in quiet conditions (80-100% at 65 dB SPL, not later than 6 to 12 months post CI activation). Four of these six patients achieved good to very good results for monosyllabic words within 1-36 months (65-85% at 65 dB SPL). The two other patients, however, had low scores for monosyllables at 6 months (25 and 15% at 65 dB SPL, respectively) with worsening of results thereafter. CONCLUSIONS: Cochleovestibular schwannomas with transmodiolar and transmacular extension represent a rare entity with specific management requirements. Hearing rehabilitation with CI is a principal option in these patients.

[Management of transmodiolar and transmacular cochleovestibular schwannomas with and without cochlear implantation. German version]. / Management transmodiolärer und transmakulärer Vestibularis- und Cochlearisschwannome mit und ohne Cochleaimplantation.

INTRODUCTION: Hearing rehabilitation with cochlear implants has attracted increasing interest also for patients with cochleovestibular schwannoma. The authors report their experience with the surgical management of tumors with rare transmodiolar or transmacular extension and outcomes after cochlear implantation (CI). METHODS: This retrospective case series included nine patients with either primary intralabyrinthine tumors or secondary invasion of the inner ear from the internal auditory canal. The primary endpoint with CI, performed in six patients, was word recognition score at 65 dB SPL (sound pressure level). Secondary endpoints were intra- and postoperative electrophysiological parameters, impedance measures, the presence of a wave V in the electrically evoked (via the CI) auditory brainstem responses, the specifics of postoperative CI programming, and adverse events. RESULTS: Hearing rehabilitation with CI in cases of transmodiolar tumor growth could be achieved only with incomplete tumor removal, whereas tumors with transmacular growth could be completely removed. All six patients with CI had good word recognition scores for numbers in quiet conditions (80-100% at 65 dB SPL, not later than 6 to 12 months post CI activation). Four of these six patients achieved good to very good results for monosyllabic words within 1-36 months (65-85% at 65 dB SPL). The two other patients, however, had low scores for monosyllables at 6 months (25 and 15% at 65 dB SPL, respectively) with worsening of results thereafter. CONCLUSIONS: Cochleovestibular schwannomas with transmodiolar and transmacular extension represent a rare entity with specific management requirements. Hearing rehabilitation with CI is a principal option in these patients.

Sclerosing odontogenic carcinoma: current diagnostic and management considerations concerning a most unusual neoplasm.

Sclerosing odontogenic carcinoma (SOC) is a primary intraosseous carcinoma of the jaws that has been listed as a separate entity for the first time in the latest version of the World Health Organization classification of Head and Neck Tumours (2017). The aim of this study was to analyse and interpret the existing literature on SOC in the context of a clinical case treated in the authors' department. A systematic search of the PubMed database was performed in accordance with the PRISMA guidelines, yielding nine cases of SOC reported so far. In summary, characteristic clinical and radiological features of SOC include asymptomatic swelling, location predominantly in the mandible, tumour primarily lytic in appearance, presence of cortical bone destruction, and lack of metastatic spread. Due to the rarity of the disease, close collaboration between oral/maxillofacial surgeons and pathologists is crucial to avoid misdiagnosis. With complete excision, no recurrence of SOC should be expected.

Legal, financial, and public health consequences of transfusion-transmitted hepatitis C virus in persons with haemophilia.

BACKGROUND: Since the first cases of acquired immunodeficiency syndrome in persons with haemophilia were reported in 1982, much has been written about the consequences of human immunodeficiency virus (HIV) contamination of the blood supply. Relatively little attention has been paid to similar hepatitis C virus (HCV) concerns since the first cases of HCV-infected persons with haemophilia were identified in 1989. METHODS: We review the history, public health, policy, and financial consequences of blood supply policy decisions made for persons with haemophilia who received HCV-contaminated blood products in eight countries that were severely impacted by viral contamination of the blood supply during the 1980s, contrasting these findings with those reported previously for HIV contamination of the blood supply during the same time-period. A Medline search and a hand search of retrieved bibliographies of English-language articles on HCV concerns in haemophilia patients published from 1989 to 2006 were performed. RESULTS: Our review identified that two- to eightfold more persons with haemophilia in the eight countries contracted HCV vs. HIV from contaminated blood products during the 1980s. Opportunistic infections and immunosuppression-related complications among persons with haemophilia developed shortly after these patients received HIV-infected blood products whereas hepatic complications among HCV-infected persons with haemophilia are just now being diagnosed two decades after these individuals received HCV-contaminated blood products. Policy makers in four countries conducted official public inquiries into blood safety decisions related to HIV- and/or HCV-contamination of the blood supply. More than 20 countries allocated compensation funds for HIV-infected persons with haemophilia (mean award ranging from $37 000 to 400 000) whereas only the UK, Canada, and Ireland allocated compensation funds for HCV-infected persons with haemophilia (mean award ranging from $37 000 to 50 000). CONCLUSION: While the clinical impact among persons with haemophilia of HCV contamination of the blood supply in the 1980s was larger than the impact of HIV contamination of the blood supply during this time-period, the policy response was smaller. Consideration should be given to adopting support programmes for HCV-infected persons with haemophilia in countries that do not have these programs.

Femtosecond laser-induced two-photon polymerization of inorganic-organic hybrid materials for applications in photonics.

Investigations of two-photon polymerization of inorganic-organic hybrid materials initiated by femtosecond Ti:sapphire laser pulses are performed. First applications of this technique for the fabrication of three-dimensional microstructures and photonic crystals in inorganic-organic hybrid polymers with a structure size down to 200 nm and a periodicity of 450 nm are discussed.

Genomic structure and refined chromosomal localization of the mouse Ptch2 gene.

The vertebrate Patched 2 (Ptch2) gene encodes a putative membrane-embedded protein which may have roles in Hedgehog signaling during development and in tumorigenesis. We determined the genomic structure of the mouse Ptch2 gene and show that Ptch2 is composed of 22 exons spanning approximately 18 kb of genomic DNA. The exon-intron boundaries were found to be conserved within the human and mouse Ptch2 genes. Analysis of the 5' flanking region revealed a CpG island, the putative promoter region and the transcriptional start site while a polyadenylation signal as well as a mRNA destabilizing motif were identified in the 3' flanking region. Single-strand conformation polymorphism analysis was used to map mouse Ptch2 to chromosome 4 between the microsatellite markers D4Mit20 and D4Mit334.

Structural basis for pterin antagonism in nitric-oxide synthase. Development of novel 4-oxo-pteridine antagonists of (6R)-5,6,7,8-tetrahydrobiopterin.

Pathological nitric oxide (NO) generation in sepsis, inflammation, and stroke may be therapeutically controlled by inhibiting NO synthases (NOS). Here we targeted the (6R)-5,6,7,8-tetrahydro-l-biopterin (H(4)Bip)-binding site of NOS, which, upon cofactor binding, maximally increases enzyme activity and NO production from substrate l-arginine. The first generation of H(4)Bip-based NOS inhibitors employed a 4-amino pharmacophore of H(4)Bip analogous to antifolates such as methotrexate. We developed a novel series of 4-oxo-pteridine derivatives that were screened for inhibition against neuronal NOS (NOS-I) and a structure-activity relationship was determined. To understand the structural basis for pterin antagonism, selected derivatives were docked into the NOS pterin binding cavity. Using a reduced 4-oxo-pteridine scaffold, derivatives with certain modifications such as electron-rich aromatic phenyl or benzoyl groups at the 5- and 6-positions, were discovered to markedly inhibit NOS-I, possibly due to hydrophobic and electrostatic interactions with Phe(462) and Ser(104), respectively, within the pterin binding pocket. One of the most effective 4-oxo compounds and, for comparisons an active 4-amino derivative, were then co-crystallized with the endothelial NOS (NOS-III) oxygenase domain and this structure solved to confirm the hypothetical binding modes. Collectively, these findings suggest (i) that, unlike the antifolate principle, the 4-amino substituent is not essential for developing pterin-based NOS inhibitors and (ii), provide a steric and electrostatic basis for their rational design.

Allosteric regulation of neuronal nitric oxide synthase by tetrahydrobiopterin and suppression of auto-damaging superoxide.

The underlying mechanisms regulating the activity of the family of homodimeric nitric oxide synthases (NOSs) and, in particular, the requirement for (6R)-5,6,7,8-tetrahydro-L-biopterin (H(4)Bip) are not fully understood. Here we have investigated possible allosteric and stabilizing effects of H(4)Bip on neuronal NOS (NOS-I) during the conversion of substrate, L-arginine, into L-citrulline and nitric oxide. Indeed, in kinetic studies dual allosteric interactions between L-arginine and H(4)Bip activated recombinant human NOS-I to increase L-arginine turnover. Consistent with this was the observation that H(4)Bip, but not the pterin-based NOS inhibitor 2-amino-4,6-dioxo-3,4,5,6,8,8a,9,10-octahydrooxazolo[1, 2-f]-pteridine (PHS-32), caused an L-arginine-dependent increase in the haem Soret band, indicating an increase in substrate binding to recombinant human NOS-I. Conversely, L-arginine was observed to increase in a concentration-dependent manner H(4)Bip binding to pig brain NOS-I. Secondly, we investigated the stabilization of NOS quaternary structure by H(4)Bip in relation to uncoupled catalysis. Under catalytic assay conditions and in the absence of H(4)Bip, dimeric recombinant human NOS-I dissociated into inactive monomers. Monomerization was related to the uncoupling of reductive oxygen activation, because it was inhibited by both superoxide dismutase and the inhibitor N(omega)-nitro-L-arginine. Importantly, H(4)Bip was found to react chemically with superoxide (O(2)(-.)) and enzyme-bound H(4)Bip was consumed under O(2)(-.)-generating conditions in the absence of substrate. These results suggest that H(4)Bip allosterically activates NOS-I and stabilizes quaternary structure by a novel mechanism involving the direct interception of auto-damaging O(2)(-.).

Endothelial nitric-oxide synthase (type III) is activated and becomes calcium independent upon phosphorylation by cyclic nucleotide-dependent protein kinases.

Endothelial nitric-oxide synthase (NOS-III) is defined as being strictly dependent on Ca(2+)/calmodulin (CaM) for activity, although NO release from endothelial cells has been reported to also occur at intracellular free Ca(2+) levels that are substimulatory for the purified enzyme. We demonstrate here that NOS-III, but neither NOS-I nor -II, is rapidly and strongly activated and phosphorylated on both Ser and Thr in the presence of cGMP-dependent protein kinase II (cGK II) and the catalytic subunit of cAMP-dependent protein kinase (cAK) in vitro. Phosphopeptide analysis by mass spectrometry identified Ser(1177), as well as Ser(633) which is situated in a recently defined CaM autoinhibitory domain within the flavin-binding region of human NOS-III. Phosphoamino acid analysis identified a putative phosphorylation site at Thr(495) in the CaM-binding domain. Importantly, both cAK and cGK phosphorylation of NOS-III in vitro caused a highly reproducible partial (10-20%) NOS-III activation which was independent of Ca(2+)/CaM, and as much as a 4-fold increase in V(max) in the presence of Ca(2+)/CaM. cAK stimulation in intact endothelial cells also increased both Ca(2+/)CaM-independent and -dependent activation of NOS-III. These data collectively provide new evidence for cAK and cGK stimulation of both Ca(2+)/CaM-independent and -dependent NOS-III activity, and suggest possible cross-talk between the NO and prostaglandin I(2) pathways and a positive feedback mechanism for NO/cGMP signaling.

Inhibition of neuronal nitric oxide synthase by 4-amino pteridine derivatives: structure-activity relationship of antagonists of (6R)-5,6,7,8-tetrahydrobiopterin cofactor.

The family of nitric oxide synthases (NOS) catalyzes the conversion of L-arginine to L-citrulline and nitric oxide (NO), an important cellular messenger molecule which has been implicated in the pathophysiology of septic shock and inflammatory and neurodegenerative disease states. NOS can be maximally activated by the ubiquitous cofactor, (6R)-5,6,7,8-tetrahydrobiopterin (H(4)Bip), and antagonists of H(4)Bip may be of therapeutic importance to inhibit pathologically high NO formation. The 4-amino substituted analogue of H(4)Bip was reported to be a potent NOS inhibitor. Therefore, we developed a series of novel 4-amino pteridine derivatives, anti-pterins, to pharmacologically target the neuronal isoform of nitric oxide synthase (NOS-I). To functionally characterize the pterin/anti-pterin interaction and establish a structure-activity relationship (SAR), we systematically altered the substituents in the 2-, 4-, 5-, 6-, and 7-position of the pteridine nucleus. Varying the substitution pattern in the 2-, 5-, and 7-position resulted in no significant inhibitory effect on enzyme activity. In contrast, bulky substituents in the 6-position, such as phenyl, markedly increased the inhibitory potency of the reduced 4-amino-5,6,7,8-tetrahydropteridines, possibly as a consequence of hydrophobic interactions within NOS-I. However, this was not the case for the aromatic 4-amino pteridines. Interestingly, chemical modification of the 4-amino substituent by dialkyl/diaralkylation together with 6-arylation of the aromatic 2,4-diamino pteridine resulted in potent and efficacious inhibitors of NOS-I, suggesting possible hydrophilic and hydrophobic interactions within NOS-I. This SAR agrees with (a) the recently published crystal structure of the oxygenase domain of the inducible NOS isoform (NOS-II) and (b) the comparative molecular field analysis of selected NOS-I inhibitors, which resulted in a 3D-QSAR model of the pterin binding site interactions. Further optimization should be possible when the full length structure of NOS-I becomes available.

Tetrahydrobiopterin inhibits monomerization and is consumed during catalysis in neuronal NO synthase.

The biosynthesis of nitric oxide (NO) is catalyzed by homodimeric NO synthases (NOS). For unknown reasons, all NOS co-purify with substoichiometric amounts of (6R)-5,6,7,8-tetrahydrobiopterin (H(4)Bip) and require additional H(4)Bip for maximal activity. We examined the effects of H(4)Bip and pterin-derived inhibitors (anti-pterins) on purified neuronal NOS-I quaternary structure and H(4)Bip content. During L-arginine turnover, NOS-I dimers time dependently dissociated into inactive monomers, paralleled by a loss of enzyme-associated pterin. Dimer dissociation was inhibited when saturating levels of H(4)Bip were added during catalysis. Similar results were obtained with pterin-free NOS-I expressed in Escherichia coli. This stabilizing effect of H(4)Bip was mimicked by the anti-pterin 2-amino-4,6-dioxo-3,4,5,6,8,8a,9, 10-octahydro-oxazolo[1,2f]-pteridine (PHS-32), which also displaced NOS-associated H(4)Bip in a competitive manner. Surprisingly, H(4)Bip not only dissociated from NOS during catalysis, but was only partially recovered in the solute (50.0 +/- 16.5% of control at 20 min). NOS-associated H(4)Bip appeared to react with a NOS catalysis product to a derivative distinct from dihydrobiopterin or biopterin. Under identical conditions, reagent H(4)Bip was chemically stable and fully recovered (95.5 +/- 3.4% of control). A similar loss of both reagent and enzyme-bound H(4)Bip and dimer content was observed by NO generated from spermine NONOate. In conclusion, we propose a role for H(4)Bip as a dimer-stabilizing factor of neuronal NOS during catalysis, possibly by interfering with enzyme destabilizing products.

Autoinhibition of neuronal nitric oxide synthase: distinct effects of reactive nitrogen and oxygen species on enzyme activity.

Nitric oxide (NO) synthases (NOSs), which catalyse the oxidation of L-arginine to L-citrulline and an oxide of nitrogen, possibly NO or nitroxyl (NO-), are subject to autoinhibition by a mechanism that has yet to be fully elucidated. In the present study we investigated the actions of NO and other NOS-derived products as possible autoregulators of enzyme activity. With the use of purified NOS-I, L-arginine turnover was found to operate initially at Vmax (0-15 min, phase I) although, despite the presence of excess substrate and cofactors, prolonged catalysis (15-90 min, phase II) was associated with a rapid decline in L-arginine turnover. Taken together, these observations suggested that one or more NOS products inactivate NOS. Indeed, exogenously applied reactive nitrogen oxide species (RNSs) decreased Vmax during phase I, although with different potencies (NO->NO> ONOO-) and efficacies (NO>NO-=ONOO-). The NO scavengers oxyhaemoglobin (HbO2; 100 microM) and 1H-imidazol-1 - yloxy - 2 - (4-carboxyphenyl) - 4,5 - dihydro - 4,4,5,5 - tetramethyl - 3 -oxide (CPTIO; 10 microM) and the ONOO- scavenger GSH (7 mM) had no effect on NOS activity during phase I, except for an endogenous autoinhibitory influence of NO and ONOO-. However, superoxide dismutase (SOD; 300 units/ml), which is thought either to increase the half-life of NO or to convert NO- to NO, lowered Vmax in an NO-dependent manner because this effect was selectively antagonized by HbO2 (100 microM). This latter observation demonstrated the requirement of SOD to reveal endogenous NO-mediated autoinhibition. Importantly, during phase II of catalysis, NOS became uncoupled and began to form H2O2 because catalase, which metabolizes H2O2, increased enzyme activity. Consistent with this, exogenous H2O2 also inhibited NOS activity during phase I. Thus during catalysis NOS is subject to complex autoinhibition by both enzyme-derived RNS and H2O2, differentially affecting enzyme activity.

Anti-pterins as tools to characterize the function of tetrahydrobiopterin in NO synthase.

Nitric oxide synthases (NOS) are homodimeric enzymes that NADPH-dependently convert L-arginine to nitric oxide and L-citrulline. Interestingly, all NOS also require (6R)-5,6,7, 8-tetrahydro-L-biopterin (H4Bip) for maximal activity although the mechanism is not fully understood. Basal NOS activity, i.e. that in the absence of exogenous H4Bip, has been attributed to enzyme-associated H4Bip. To elucidate further H4Bip function in purified NOS, we developed two types of pterin-based NOS inhibitors, termed anti-pterins. In contrast to type II anti-pterins, type I anti-pterins specifically displaced enzyme-associated H4Bip and inhibited H4Bip-stimulated NOS activity in a fully competitive manner but, surprisingly, had no effect on basal NOS activity. Moreover, for a number of different NOS preparations basal activity (percent of Vmax) was frequently higher than the percentage of pterin saturation and was not affected by preincubation of enzyme with H4Bip. Thus, basal NOS activity appeared to be independent of enzyme-associated H4Bip. The lack of intrinsic 4a-pterincarbinolamine dehydratase activity argued against classical H4Bip redox cycling in NOS. Rather, H4Bip was required for both maximal activity and stability of NOS by binding to the oxygenase/dimerization domain and preventing monomerization and inactivation during L-arginine turnover. Since anti-pterins were also effective in intact cells, they may become useful in modulating states of pathologically high nitric oxide formation.

Mapping of a defined neurocan binding site to distinct domains of tenascin-C.

Neurocan is a member of the aggrecan family of proteoglycans which are characterized by NH2-terminal domains binding hyaluronan, and COOH-terminal domains containing C-type lectin-like modules. To detect and enhance the affinity for complementary ligands of neurocan, the COOH-terminal neurocan domain was fused with the NH2-terminal region of tenascin-C, which contains the hexamerization domain of this extracellular matrix glycoprotein. The fusion protein was designed to contain the last downstream glycosaminoglycan attachment site and was expressed as a proteoglycan. In ligand overlay blots carried out with brain extracts, it recognized tenascin-C. The interaction was abolished by the addition of EDTA, or TNfn4,5, a bacterially expressed tenascin-C fragment comprising the fourth and fifth fibronectin type III module. The fusion protein directly reacted with this fragment in ligand blot and enzyme-linked immunosorbent assay procedures. Both tenascin-C and TNfn4,5 were retained on Sepharose 4B-linked carboxyl-terminal neurocan domains, which in BIAcore binding studies yielded a KD value of 17 nM for purified tenascin-C. We conclude that a divalent cation-dependent interaction between the COOH-terminal domain of neurocan and those fibronectin type III repeats is substantially involved in the binding of neurocan to tenascin-C.

Cloning and functional expression of the murine homologue of proteinase 3: implications for the design of murine models of vasculitis.

Anti-neutrophil cytoplasmic autoantibodies recognizing conformational epitopes (c-ANCA) of proteinase 3 (PR3) from azurophil granules are a diagnostic hallmark in Wegener's granulomatosis (WG). Because a functional PR3 homologue has not been identified in rodents, it is difficult to assess immunopathological responses in rats or mice immunized with patients' derived c-ANCA or human PR3. Here we report the full length cDNA cloning and functional expression of murine PR3 in HMC-1 cells. Recombinant murine PR3 shows highly similar substrate specificities towards synthetic peptides and is inhibited by human alpha1-proteinase inhibitor like human PR3. However, neither human c-ANCA, rabbit sera nor mouse monoclonal antibodies to human PR3 recognize the murine homologue. Consequently, it is unlikely that disease observed in mice after immunization with c-ANCA or human PR3 is caused by pathogenic antibodies directed against mouse PR3. Recombinant human-mouse chimaeric variants will be a valuable new tool to localize the disease-specific immunodominant epitopes in human PR3.