[Structured ABEV Exercises for the Treatment of vestibular dysfunction]. / Strukturierte ABEV-Übungen zur Behandlung vestibulärer Funktionsstörungen.

INTRODUCTION: In addition to medication, the standard clinical treatment for vestibular vertigo primarily includes physical therapy in the form of regular exercises. Vertidisan is a future digital health application (DiGA) for structured dizziness therapy. Its content is multimodal and consists of Adaptive Balance and Eye Movements and Visual Stimulation (ABEV) exercises, which are expected to have an anti-vertigo effect through neural learning. METHODS: A cohort study with 104 patients with intra-individual control was conducted to examine the clinical efficacy of solely 16 ABEV exercises for the treatment of peripheral vestibulopathies which are also used digitally in the future DiGA Vertidisan. Using the short version vertigo symptom scale short form1 vertigo and related symptoms (VSS-sf1-VER) of the vertigo-specific and validated VSS rating scale (Vertigo Symptom Scale) as the primary outcome variable, the vertigo scores before therapy (time T0) were compared with the corresponding data at the end of a period of 12-16 weeks (time T1). RESULTS: Complete datasets on T0 and T1 were available for N=104 patients. The mean VSS-sf1-V score decreased from 3.80 (median 4, SD 0.47) to 0.92 (median 1, SD 1.19) from T0 to T1 (weeks 12-16). The result is statistically significant (p=0.001) and shows a high clinical effect size. CONCLUSION: In summary, the analysis of the dizziness score shows a statistically and clinically significant reduction in dizziness through the use of the 16 ABEV exercises.

A multidisciplinary systematic review of the treatment for chronic idiopathic tinnitus.

The majority of tinnitus patients are affected by chronic idiopathic tinnitus, and almost 60 different treatment modalities have been reported. The present study is a multidisciplinary systematic analysis of the evidence for the different forms of treatment for chronic tinnitus. The results are used to form the basis of an S3 guideline. A systematic search was carried out in PubMed and the Cochrane Library. The basis for presenting the level of evidence was the evidence classification of the Oxford Centre of Evidence-based Medicine. Whenever available, randomised controlled trials were given preference for discussing therapeutic issues. All systematic reviews and meta-analyses were assessed for their methodological quality, and effect size was taken into account. As the need for patient counselling is self-evident, specific tinnitus counselling should be performed. Due to the high level of evidence, validated tinnitus-specific, cognitive behavioural therapy is strongly recommended. In addition, auditory therapeutic measures can be recommended for the treatment of concomitant hearing loss and comorbidities; those should also be treated with drugs whenever appropriate. In particular, depression should be treated, with pharmacological support if necessary. If needed, psychiatric treatment should also be given on a case-by-case basis. With simultaneous deafness or hearing loss bordering on deafness, a CI can also be indicated. For auditory therapeutic measures, transcranial magnetic or direct current stimulation and specific forms of acoustic stimulation (noiser/masker, retraining therapy, music, and coordinated reset) for the treatment of chronic tinnitus the currently available evidence is not yet sufficient for supporting their recommendation.

Risk factors for nasal malignancies in German men: the South-German Nasal cancer study.

BACKGROUND: There are few studies of the effects of nasal snuff and environmental factors on the risk of nasal cancer. This study aimed to investigate the impact of using nasal snuff and of other risk factors on the risk of nasal cancer in German men. METHODS: A population-based case-control study was conducted in the German Federal States of Bavaria and Baden-Württemberg. Tumor registries and ear, nose and throat departments provided access to patients born in 1926 or later. RESULTS: Telephone interviews were conducted with 427 cases (mean age 62.1 years) and 2.401 population-based controls (mean age 60.8 years). Ever-use of nasal snuff was associated with an odds ratio (OR) for nasal cancer of 1.45 (95% confidence interval [CI] 0.88-2.38) in the total study population, whereas OR in smokers was 2.01 (95% CI 1.00-4.02) and in never smokers was 1.10 (95% CI 0.43-2.80). The OR in ever-smokers vs. never-smokers was 1.60 (95% CI 1.24-2.07), with an OR of 1.06 (95% CI 1.05-1.07) per pack-year smoked, and the risk was significantly decreased after quitting smoking. Exposure to hardwood dust for at least 1 year resulted in an OR of 2.33 (95% CI 1.40-3.91) in the total population, which was further increased in never-smokers (OR 4.89, 95% CI 1.92-12.49) in analyses stratified by smoking status. The OR for nasal cancer after exposure to organic solvents for at least 1 year was 1.53 (1.17-2.01). Ever-use of nasal sprays/nasal lavage for at least 1 month rendered an OR of 1.59 (1.04-2.44). The OR after use of insecticides in homes was 1.48 (95% CI 1.04-2.11). CONCLUSIONS: Smoking and exposure to hardwood dust were confirmed as risk factors for nasal carcinoma. There is evidence that exposure to organic solvents, and in-house use of insecticides could represent novel risk factors. Exposure to asbestos and use of nasal snuff were risk factors in smokers only.

Conditions for highly efficient and reproducible round-window stimulation in humans.

Round-window stimulation is a new clinical approach for the application of active middle-ear implants. To investigate factors influencing the efficiency of round-window stimulation, experiments in 6 human temporal bones were performed with different actuator geometries and coupling conditions. The experiments show that the amplitude ratio between stapes and round-window actuator vibration is most efficient when using a 1.0-mm diameter rod with a 30° inclined tip geometry and an attached silicone pad. In this case, the amplitude ratio is 0.34 for frequencies up to 1.5 kHz and 0.27 for frequencies up to 20 kHz, with a standard deviation of only 4-6 dB at most frequencies. The analysis of data presented here and in a companion paper suggests that control of proper round-window membrane pretension as well as the inclined tip geometry are the major requirements for maximal performance.

[Structuring of inpatient case management to improve quality and cost-effectiveness of inpatient healthcare providers from a university hospital's point of view]. / Strukturierung des stationären Fallmanagements für die Verbesserung von Qualität und Wirtschaftlichkeit stationärer Gesundheitsdienstleister aus Sicht eines Universitätsklinikums.

OBJECTIVE: In hospitals, case management (CM) on hospital wards is essential for maintaining a high level of quality and efficiency of care. The present study examined how CM at the Point of Care (POC) can be optimized and which potentials exist. METHODS: The potentials for optimization of typical case management processes performed on hospital wards were analyzed using a structured interview guide. For this purpose, a field study was performed in 24 German hospital departments of tertiary care. Structured interviews were conducted with homogeneous focus groups. The results were evaluated using an extended Balanced Score Card approach and discussed afterwards with the focus groups. RESULTS: Above all, the process quality and safety of case management as well as ensuring the relevant documentation at the POC appears to offer significant potential for optimization. An essential approach to eventually realize the potential for optimization is the reduction of fragmentation of the micro-processes associated with the case management duties on inpatient wards. This homogenization of these activities ideally requires a new and interdisciplinary acting profession, the clinical case managers. CONCLUSION: The homogenization of the case management activities on hospital wards by clinical case managers has the potential and possibilities to relieve both medical and nursing staff of these activities, while improving the quality and efficiency of care for patients, staff and cross-sectoral healthcare provider at the same time.

Implantability of endaurally insertable active vibratory middle-ear implants - an anatomical study.

Background: Hearing loss is often treated with an acoustic hearing aid. However, distortion and insufficient gain may cause problems. Active non-acoustic vibratory middle-ear implants (AMEI) may contribute to solve this problem. We recently developed an AMEI which is to be implanted completely through the patient's external auditory canal. The device uses a light-emitting diode (LED) in the external auditory canal that stimulates a photovoltaic sensor, placed in the middle ear, through the intact tympanic membrane. This results in activation of a vibratory miniaturized piezoelectric displacement transducer (MDT) (actuator) coupled to the auditory organ. Aims/objectives: The aim of this study was to evaluate the anatomical implantability of the novel AMEI using an exclusively endaural approach. Materials and methods: The internal components of our AMEI were implanted into 39 human temporal bones. The surgical procedure and the optimal size and anatomical fitting were systematically evaluated. Results: We can show here that implantation of all components of this novel AMEI into anatomical specimens proves to be a quick and easy procedure, performed using an endaural approach. Conclusions and significance: The anatomical data of this study establish the basis for further technical development of our AMEI and other future implantable hearing systems.

Speech-in-noise intelligibility does not correlate with efferent olivocochlear reflex in humans with normal hearing.

CONCLUSION: According to the presented data, speech-in-noise intelligibility (SI) does not correlate with olivocochlear efferent activity - as measured by contralateral suppression (CS) of distortion product otoacoustic emissions (DPOAE) in humans with normal auditory threshold. OBJECTIVES: Literature data indicate a possible role of the medial olivocochlear efferents in speech intelligibility, especially in background noise. The objective of this study was to investigate this relationship. MATERIALS AND METHODS: SI was evaluated in three independent sessions by determining the ratio speech level/noise level, at which 50% of the words are understood (i.e. speech reception threshold, SRT). Efferent activity was inferred measuring CS of DPOAE, using two different paradigms with extensive variation of stimulus parameters and duplicate measurements. RESULTS: For optimum measurement of CS, the study was restricted to subjects (n =49) with valid DPOAE down to primary tone levels L1=47/L2 =20 dB SPL. Average SRT was -6.66 dB (-4.50 to -7.65 dB, SD 0.63 dB). CS increased with decreasing primary tone levels, with mean absolute CS values in the range of 0.6-6 dB SPL. Test-retest repeatability was good. Statistical evaluation revealed no significant relationship between SI and CS of DPOAE.

Hyposmotic stimulation-induced nitric oxide production in outer hair cells of the guinea pig cochlea.

Nitric oxide (NO) production during hyposmotic stimulation in outer hair cells (OHCs) of the guinea pig cochlea was investigated using the NO sensitive dye DAF-2. Simultaneous measurement of the cell length and NO production showed rapid hyposmotic-induced cell swelling to precede NO production in OHCs. Hyposmotic stimulation failed to induce NO production in the Ca2+-free solution. L-NG-nitroarginine methyl ester (L-NAME), a non-specific NO synthase inhibitor and gadolinium, a stretch-activated channel blocker inhibited the hyposmotic stimulation-induced NO production whereas suramin, a P2 receptor antagonist did not. S-nitroso-N-acetylpenicillamine (SNAP), a NO donor inhibited the hyposmotic stimulation-induced increase in the intracellular Ca2+ concentrations ([Ca2+]i) while L-NAME enhanced it. 1H-[1,2,4]oxadiazole[4,3a]quinoxalin-1-one, an inhibitor of guanylate cyclase and KT5823, an inhibitor of cGMP-dependent protein kinase (PKG) mimicked effects of L-NAME on the Ca2+ response. Transient receptor potential vanilloid 4 (TRPV4), an osmo- and mechanosensitive channel was expressed in the OHCs by means of immunohistochemistry. 4alpha-phorbol 12,13-didecanoate, a TRPV4 synthetic activator, induced NO production in OHCs. These results suggest that hyposmotic stimulation can induce NO production by the [Ca2+]i increase, which is presumably mediated by the activation of TRPV4 in OHCs. NO conversely inhibits the Ca2+ response via the NO-cGMP-PKG pathway by a feedback mechanism.

Hyposmotic stimulation-induced nitric oxide production in outer hair cells of the guinea pig cochlea.

Nitric oxide (NO) production during hyposmotic stimulation in outer hair cells (OHCs) of the guinea pig cochlea was investigated using the NO sensitive dye DAF-2. Simultaneous measurement of the cell length and NO production showed rapid hyposmotic-induced cell swelling to precede NO production in OHCs. Hyposmotic stimulation failed to induce NO production in the Ca(2+)-free solution. L-N(G)-nitroarginine methyl ester (L-NAME), a non-specific NO synthase inhibitor and gadolinium, a stretch-activated channel blocker inhibited the hyposmotic stimulation-induced NO production whereas suramin, a P2 receptor antagonist did not. S-nitroso-N-acetylpenicillamine (SNAP), a NO donor inhibited the hyposmotic stimulation-induced increase in the intracellular Ca(2+) concentrations ([Ca(2+)](i)) while L-NAME enhanced it. 1H-[1,2,4]oxadiazole[4,3a]quinoxalin-1-one, an inhibitor of guanylate cyclase and KT5823, an inhibitor of cGMP-dependent protein kinase (PKG) mimicked effects of L-NAME on the Ca(2+) response. Transient receptor potential vanilloid 4 (TRPV4), an osmo- and mechanosensitive channel was expressed in the OHCs by means of immunohistochemistry. 4alpha-phorbol 12,13-didecanoate, a TRPV4 synthetic activator, induced NO production in OHCs. These results suggest that hyposmotic stimulation can induce NO production by the [Ca(2+)](i) increase, which is presumably mediated by the activation of TRPV4 in OHCs. NO conversely inhibits the Ca(2+) response via the NO-cGMP-PKG pathway by a feedback mechanism.

Papillomavirus E2 protein induces expression of the matrix metalloproteinase-9 via the extracellular signal-regulated kinase/activator protein-1 signaling pathway.

Papillomaviruses are involved in the development of cancers of the female cervix, head and neck, and skin. An excellent model to study papillomavirus-induced tumor induction and progression is the New Zealand White rabbit, where the skin is infected with the cottontail rabbit papillomavirus (CRPV). This leads to the formation of benign tumors that progress into invasive and metastasizing carcinomas without the need for cofactors. We have shown previously that specific mutations in the transactivation domain of the transcription/replication factor E2 cause a dramatic loss in the tumor induction efficiency of the viral genome and a major deficiency in tumor progression as we show now. By comparing wild-type (WT) and mutant E2-induced skin tumors, we found high levels of matrix metalloproteinase-9 (MMP-9) protein and transcripts in WT CRPV-E2-induced tumors in contrast to certain mutant CRPV-E2-induced papillomas and normal uninfected skin. Stable cell lines and reporter assays revealed that E2 from different papillomavirus types is able to transactivate the MMP-9 promoter via the promoter-proximal activator protein-1 (AP-1) site as shown in reporter gene assays with mutant MMP-9 promoter constructs. Furthermore, WT E2 but not mutant E2 strongly transactivated a minimal promoter reporter construct with multiple AP-1 sites. The MMP-9 protein induced in cells expressing E2 degrades collagen matrices as measured in Matrigel-based invasion/mobility assays. E2-induced MMP-9 expression can be blocked by a chemical inhibitor of mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) kinase 1 (PD 098059), suggesting that E2 activates the MAPK/ERK signaling pathway, which is further supported by the induction of ERK1 in CRPV-E2-transfected cells.

Technical note on microcatheter implantation for local inner ear drug delivery: surgical technique and safety aspects.

HYPOTHESIS: Despite its invasiveness, the temporary implantation of a microcatheter into the middle ear cavity is an appropriately safe method for providing continuous drug delivery to the inner ear. BACKGROUND: For the application of drugs to the inner ear, different delivery strategies are available ranging from intratympanic injections to temporarily implanted microcatheters. It has recently been demonstrated that the choice of the drug delivery system influences the pharmacokinetics in the inner ear. If a continuous drug application over several weeks is required, a secure placement of the delivery device (i.e., the microcatheter) is necessary to guarantee efficient drug delivery and to avoid unwanted side effects. STUDY DESIGN: Retrospective chart review. MATERIALS AND METHODS: During 2000 to 2005, 25 patients with acute unilateral severe-to-profound hearing loss or anacusis and failure of systemic high-dose glucocorticoid and rheological therapy were offered an intratympanic delivery of glucocorticoids via a temporarily implanted catheter and an external pump for up to 4 weeks as a salvage treatment option. The standardized surgical implantation and fixation technique developed for the microcatheter were characterized by six elements: 1) a medial and a lateral tunnel connected by a groove in the posterior wall of the bony ear canal, 2) stabilization of the catheter with bone wax and soft tissue plugs in the tunnels, 3) an ear canal packing, 4) a series of fixating sutures along the catheter, 5) an adhesive dressing, and 6) additional tapes at the connecting line between pump and catheter. At the end of the implantation period, the catheter was removed by a second surgical procedure allowing for evaluation of the catheter position and the condition of the middle ear space. RESULTS: Adverse events included catheter dislocation, catheter obstruction, formation of mild granulation tissue in the middle ear cavity, tympanic membrane defects, and ear canal skin defects. With introduction of an improved implantation and fixation technique, the number of catheter dislocations could be significantly reduced. No complications were observed on long-term follow-up. CONCLUSION: If the pharmacokinetics or pharmacodynamics of a specific local inner ear therapy approach requires a continuous intratympanic drug application (e.g., to restore hearing in patients with severe or profound hearing loss), the temporary implantation of a microcatheter by a standardized surgical technique is a feasible and appropriately safe method for providing continuous drug delivery to the inner ear.

Phenotypic characterization of a DFNA6 family showing progressive low-frequency sensorineural hearing impairment.

Only three autosomal dominant hearing loss loci (DFNA1, DFNA6/14/38 and DFNA54) have been reported to be associated with predominantly low-frequency (<2kHz) sensorineural hearing impairment (LFSNHI). The DFNA6 locus was previously mapped to chromosome 4p16.3. It was showed that WFS1 is located in this region. This study presents a six-generation family from Hungary with nonsyndromic, post-lingual, bilateral, symmetric, progressive LFSNHI, that discloses positive linkage to the DFNA6 region. Eleven genetically affected family members have LFSNHI. The HI is started before the age of 25 years. The severity of HI varies from mild to moderate, related to age. Progression was mild but significant at all frequencies causing a flat type audiogram. High-resolution temporal bone CT scan showed normal external, middle and inner ear without any osseus malformations in the temporal bone. Studying genotype-phenotype correlations will enhance our understanding of normal and disturbed hearing process.

High frequency of ENG and ALK1/ACVRL1 mutations in German HHT patients.

Morbus Osler or HHT (hereditary hemorrhagic telangiectasia) is a disorder of the fibrovascular tissue that is inherited in an autosomal dominant way with frequency rates between 1:2,500 and 1:40,000. The disease provokes malformations of the blood vessels sometimes resulting in life-threatening complications. Presently, two genes involved in the development of HHT have been identified: ACVRL1 and ENG. Both of them encode proteins that belong to the TGF-beta receptor complex family and play an essential role in the formation of the vascular system. Recently, several mutations in ACVRL1 and ENG have been described in other European populations. However, no data concerning mutation frequencies in the German population have been reported so far. Therefore, we screened our collective of German HHT patients (28 single cases and 11 familial cases) for mutations in both genes by direct sequencing. We detected 11 mutations already described elsewhere and 19 novel ones. Furthermore, evidence for the pathogenic role of four new missense mutations was collected by screening a healthy control collective using RFLP analysis. Interestingly, the majority of ACVRL1 mutations represented missense mutations, whereas mutations in ENG mostly resulted in a shortened protein. Our results demonstrate the importance of ACVRL1 and ENG mutations in German HHT patients displaying mutation frequencies over 80%.

In vitro expansion of human nasoseptal chondrocytes reveals distinct expression profiles of G1 cell cycle inhibitors for replicative, quiescent, and senescent culture stages.

In vitro expansion of chondrocytes for tissue-engineering applications is limited by forms of growth arrest known as quiescence and replicative senescence. At the molecular level cyclin-dependent kinase inhibitors (CDKIs) are involved in mediating growth arrest in the G1 phase of the cell cycle. Using ribonuclease protection assays and immunocytochemical staining methods, we quantitatively analyzed expression profiles of G1 cell cycle inhibitors at the mRNA and protein levels. These inhibitors included the CDKIs of the CIP/KIP family (p21CIP1 p27KIP1, and p57KIP2) and the INK4 family (p15INK4b, p16INK4a, p18INK4c, and p19INK4d) as well as the retinoblastoma protein-family (pRb, p107, and p130) and the tumor suppressor p53. Analysis was carried out in proliferating, quiescent, and senescent states of primary cultures of adult human nasoseptal chondrocytes. The most pronounced effect (p < 0.0001) between cultures in proliferation and cultures in growth arrest was an increased expression of the CDKIs p57KIP2 and p15INK4b for quiescent growth arrest, and of p16INK4a, p15INK4b, and p57KIP2 for senescent growth arrest. Thus, these cell cycle inhibitors represent potential candidates for selective intervention to promote cellular multiplication of chondrocytes undergoing in vitro expansion for tissue-engineering applications. Possible methods of modulation include the targeted elimination of specifically identified cell cycle inhibitors by antisense technologies.

Outcomes research analysis of continuous intratympanic glucocorticoid delivery in patients with acute severe to profound hearing loss: basis for planning randomized controlled trials.

CONCLUSIONS: The data presented herein form the basis for conducting randomized placebo-controlled clinical trials evaluating the safety and efficacy of salvage treatment in patients with idiopathic sudden severe sensorineural hearing loss (but not anacusis) refractory to initial systemic therapy. Comparison of different application protocols and drug delivery systems will allow assessment of the value of continuous versus intermittent intratympanic glucocorticoid drug delivery. OBJECTIVES: To describe and critically evaluate the results of continuous intratympanic glucocorticoid delivery in patients with acute unilateral severe and profound sensorineural hearing loss refractory to initial systemic therapy and to compare the outcome with a historical control group. MATERIAL AND METHODS: In a retrospective chart review, treatment results were analyzed in 23 patients with acute severe and profound hearing loss and failure of systemic standard therapy who received a continuous intratympanic delivery of glucocorticoids as a salvage treatment. Audiological results were compared within the local therapy group and with the results of an historical control group who did not receive salvage treatment. The study and control groups were matched with respect to hearing loss after initial systemic treatment failure. RESULTS: The average pure-tone threshold after intratympanic salvage treatment showed a statistically significant improvement of 15 dB (95% CI 7-24 dB; p<0.001). After exclusion of patients with complete anacusis, i.e. a non-measurable hearing threshold, the local therapy group showed a significantly better improvement (mean 19 dB; 95% CI 6-32 dB) than the historical control group (mean 5 dB; 95% CI -2-11 dB; p<0.05).

GJB2 mutations in patients with non-syndromic hearing loss from Northeastern Hungary.

Mutations in the GJB2 gene encoding the gap-junction protein connexin 26 have been identified in many patients with childhood hearing impairment (HI). One single mutation, c.35delG, accounts for the majority of mutations in Caucasian patients with HI. In the present study we screened 500 healthy control individuals and a group of patients with HI from Northeastern Hungary for GJB2 mutations. The patients' group consisted of 102 familial from 28 families and 92 non-familial cases. The most common mutation in the Hungarian population is the c.35delG, followed by the c.71G>A (p.W24X) mutation. 34.3% of the patients in the familial group were homozygous, and 17.6% heterozygous for 35delG. In the non-familial group the respective values were 37% and 18% (allele frequency: 46.2%). In the general population an allele frequency of 2.4% was determined. Several patients were identified with additional, already described or new GJB2 mutations, mostly in heterozygous state. The mutation c.380G>A (p.R127H) was formerly found only in heterozygous state and its disease relation was controversial. We demonstrated the presence of this mutation in a family with three homozygous patients and 4 heterozygous unaffected family members, a clear indication of recessively inherited HI. Furthermore, we provided evidence for the pathogenic role of two new mutations, c.51C>A (p.S17Y) and c.177G>T (p.G59V), detected in the present study. In the latter case the pattern of inheritance might be dominant. Our results confirm the importance of GJB2 mutations in the Hungarian population displaying mutation frequencies that are comparable with those in the Mediterranean area.

Mutation A1555G in the 12S rRNA gene and its epidemiological importance in German, Hungarian, and Polish patients.

The A1555G mutation in the 12SrRNA gene has been associated with aminoglycoside induced and nonsyndromic sensorineural hearing impairment. In this study we analyzed Hungarian, Polish and German patients with nonsyndromic severe to profound hearing impairment of unknown origin for this mutation. The frequency of the A1555G mutation in the Hungarian hearing impaired population was below 1.8 %. Three out of 125 Polish patients carrying the A1555G mutation were identified. Among German patients one carrier was found (0.7 %) revealing a homoplastic A1555G mutation, whereas no mutation was detected in control individuals with normal hearing (frequency < 0.6%). In summary the frequencies of the A1555G mutation are low in the hearing impaired as well as in the normal population in Hungary, Poland and Germany. Since the importance of this mutation and its relationship with aminoglycoside exposure is not well understood yet, patients with nonsyndromic hearing impairment should be routinely screened for this mutation to avoid aminoglycoside induced hearing impairment due to increased sensitivity of maternal relatives.

Frequencies of GJB2 mutations in German control individuals and patients showing sporadic non-syndromic hearing impairment.

Mutations in the GJB2 gene encoding the gap-junction protein connexin 26 have been identified in many patients with childhood hearing impairment (HI). One single mutation, 35delG (30delG), accounts for up to 70% of all analyzed European patients with autosomal recessive inherited HI and 10% of patients with HI of unknown origin, respectively. We screened 188 control individuals and 342 German patients with non-syndromic sporadic HI for the 35delG, compound heterozygosity and other GJB2 mutations by PCR, restriction enzyme based screening, SSCP and sequencing. In all patients, non-progressive hearing impairment varied from moderate to profound involving all frequencies. This study revealed one novel silent mutation (438C/T), three novel gene variants resulting in amino acid substitutions (K112E, T123S, K223R) and two novel HI-related mutations (I82M, 313del14).

Second family with hearing impairment linked to 19q13 and refined DFNA4 localisation.

Until now, over 30 loci have been identified by linkage analysis of affected families that segregate non-syndromic and dominantly inherited forms of hearing impairment (DFNA). A German family with a non-syndromic progressive hearing impairment transmitted in autosomal dominant mode was linked to 19q13.3-q13.4 by a genome-wide scan. Due to the low lod-score (1.85 at theta=0.05) for APOC2-locus we extended the fine mapping attempt with further markers in the same chromosomal region. This resulted in significant evidence for linkage to the markers D19S246 and D19S553 (two-point lod-score of 4.05 and 3.55 at theta=0.0) and a candidate critical region of 14 cM between markers D19S412 and D19S571. This region shows partial overlap with the previously reported DFNA4 critical region. The human gene BAX is orthologous to the rodent Bcl2-related apoptosis gene that is temporally expressed during the postnatal period in the developing inner ear of the mouse. BAX, mapping at a distance of no more than 0.73 cM distally to marker D19S553 appeared a likely candidate in our pedigree but genomic sequencing of coding regions and exon/intron boundaries excluded disease-related mutations. However, additional ESTs in the same region remain to be tested.

Chromosome 11 monosomy in conjunction with a mutated SDHD initiation codon in nonfamilial paraganglioma cases.

Paragangliomas of the head and neck region are a group of rare, usually benign, slow-growing tumors developing from paraganglionic chemoreceptors in most patients. Mutations in a subunit of the mitochondrial enzyme II complex (succinate dehydrogenase [SDHD]) were shown to be responsible for the formation of paragangliomas. In addition, loss of heterozygosity (LOH) on chromosome 11, mainly in 11q23 (PGL1), was observed recently. We analyzed DNA derived from tumor sections of three unrelated paraganglioma patients (one case with multiple paragangliomas, two cases with single tumors; all of them sporadic cases) for mutations in the SDHD gene by direct sequencing. Microsatellite-based LOH was performed, and events of chromosomal loss were validated by fluorescence in situ hybridization (FISH) on paraffin-embedded tumor and normal tissue by using centromeric satellite DNA. Sequence analysis revealed mutations in SDHD exon 1 in all patients, affecting the initiation codon (M1V). Another alteration was detected in exon 2 but was lacking in tumor DNA and therefore classified as polymorphism (H50R). LOH and FISH analyses demonstrated partial/total monosomy for chromosome 11 in the tumor samples tested. A common genetic mechanism appears to be the pathophysiologic basis for sporadic tumor development because the proposed two-hit model comprising both LOH and point mutation is manifest in our patients. Loss of chromosome 11 regions, including the deletion of PGL1 and PGL2 loci, may result in a more severe phenotype, as exemplified by the development of multiple tumors in one of the patients.