Endoglin is expressed in the chicken vasculature and is involved in angiogenesis

AbstractEndoglin is a component of the transforming growth factor β (TGF-β) receptor complex, highly expressed by endothelial cells. Mutations in the endoglin gene are responsible for hereditary hemorrhagic telangiectasia type 1 (HHT1), an autosomal dominant vascular disorder caused by a haploinsufficiency mechanism. Vascular lesions (telangiectasia and arteriovenous malformations) in HHT1 are associated with loss of the capillary network, suggesting the involvement of endoglin in vascular repair processes. Using the chick chorioallantoic membrane (CAM) as an angiogenic model, we have analyzed the expression and function of chicken endoglin. A pan-specific polyclonal antibody (pAb) recognized chicken endoglin as demonstrated by immunostaining and Western blot analysis. In ovo treatment of chicken embryos with this pAb resulted in a significantly increased area of CAM. This effect was likely mediated by modulation of the ligand binding to endoglin as this pAb was able to inhibit TGF-β1 binding. These results support the involvement of endoglin in the angiogenic process

Role of endoglin in cellular responses to transforming growth factor-beta. A comparative study with betaglycan

10 p.-7 fig.Endoglin (CD105) is the target gene for the hereditary hemorrhagic telangiectasia type I (HHT1), a dominantly inherited vascular disorder. It shares with betaglycan a limited amino acid sequence homology and being components of the membrane transforming growth factor-beta (TGF-beta) receptor complex. Using rat myoblasts as a model system, we found that overexpression of endoglin led to a decreased TGF-beta response to cellular growth inhibition and plasminogen activator inhibitor-1 synthesis, whereas overexpression of betaglycan resulted in an enhanced response to inhibition of cellular proliferation and plasminogen activator inhibitor-1 induced expression in the presence of TGF-beta. The regulation by endoglin of TGF-beta responses seems to reside on the extracellular domain, as evidenced by the functional analysis of two chimeric proteins containing different combinations of endoglin and betaglycan domains. Binding followed by cross-linking with 125I-TGF-beta1 demonstrated that betaglycan expressing cells displayed a clear increase (about 3. 5-fold), whereas endoglin expressing cells only displayed an slight increment (about 1.6-fold) in ligand binding with respect to mock transfectants. SDS-polyacrylamide gel electrophoresis analysis of radiolabeled receptors demonstrated that expression of endoglin or betaglycan is associated with an increased TGF-beta binding to the signaling receptor complex; however, while endoglin increased binding to types I and II receptors, betaglycan increased the binding to the type II receptor. Conversely, we found that TGF-beta binding to endoglin required the presence of receptor type II as evidenced by transient transfections experiments in COS cells. These findings suggest a role for endoglin in TGF-beta responses distinct from that of betaglycan.This work was supported by Comisión Interministerial de Ciencia y Tecnologı́a Grant CICYT-SAF97-0034, Comunidad Autónoma de Madrid (CAM), and Biomed Program of the European Community Grant BMH4-CT95-0995 (to C. B.)Peer reviewe

Usage of personal music players in adolescents and its association with noise-induced hearing loss: A cross-sectional analysis of Ohrkan cohort study data

Objective: To describe personal music player (PMP) usage among adolescents, sociodemographic determinants and association with audiometric notches. Design: Audiometric evaluation to assess hearing status, and standardized questionnaires to evaluate PMP listening behaviors, leisure noise exposures and self-reported hearing loss symptoms. Sociodemographic information was collected using a parent questionnaire. Noise exposure by PMP usage equivalent for a 40h week was estimated based on self-reported volume and duration of use. Study sample: A total of 2143 students (54% females) attending 9th grade in Regensburg, Germany, during 2009 to 2011. Results: Overall, 85% of the students reported using PMPs. Exposure level exceeded 80dB(A) in approximately one third, and 85dB(A) in one quarter, of those who used PMP. An audiometric notch was found in 2.3% of participants, but was not significantly associated with higher PMP exposure. Conclusions: PMP exposure above the occupational limits of 80 and 85dB(A) set by the Directive 2003/10/EC may be a risk factor for developing noise-induced hearing loss. Educational measures to ameliorate high risk behaviors in PMP usage are needed, particularly for socially disadvantaged groups

NS1 Protein of Parvovirus B19 Interacts Directly with DNA Sequences of the p6 Promoter and with the Cellular Transcription Factors Sp1/Sp3

The nonstructural proteins of parvovirus exert a variety of disparate functions during viral infection ranging from promoter regulation, involvement in DNA replication, and induction of apoptosis. Our interest was focused on the possible mechanism by which the NS1 protein mediates its effects on the p6 promoter of parvovirus B19. It is known that the p6 promoter is highly active in different cell lines and interaction with the viral NS1 protein results in a further increase of the activity. The protein may function by binding directly to the viral DNA or via an indirect binding through interaction with cellular transcription factors bound to the promoter. We examined the interaction of the NS1 protein with cellular transcription factors which are involved in regulating the promoter activity. After purified baculovirus-expressed NS1 protein in gel retardation assays was added, an altered complex formation was observed, indicating that NS1 protein interacts with Sp1/Sp3 transcription factors. Enzyme-linked immunosorbent assays verified these findings. The direct interaction of NS1 protein with p6 promoter elements was analyzed by a coprecipitation assay whereby labeled oligonucleotides spanning the entire promoter region were incubated with NS1 protein followed by an immunoprecipitation with NS1-specific antibodies. An eight-nucleotide-long, almost palindromic sequence (AGGGCGGA) was found as potential NS1-binding motif. Footprint analysis with oligonucleotides containing this DNA motif confirmed this result. Thus, transcriptional regulation by the NS1 protein may involve both the interaction with Sp1/Sp3 that binds to the promoter region and direct binding of NS1 to the promoter DNA

Cellular transcription factors that interact with p6 promoter elements of parvovirus B19

All transcripts of the human parvovirus B19 identified so far are regulated by a single promoter at map unit 6 of the viral genome, the so-called p6 promoter. This promoter is active in a wide variety of different cells. In order to identify cellular transcription factors involved in regulating promoter activity, we performed gel-retardation and supershift assays using the parts of the p6 promoter sequence shown previously to be protected in footprint experiments. Thereby, binding was demonstrated of the Oct-1 protein to an octamer motif within the p6 promoter and of the transcription factor Sp1 to three GC boxes. A specific preferential interaction of the factor Sp3 with one of these boxes was observed, indicating that the ratio Sp1:Sp3 may be involved in the regulation of promoter activity. Consensus sites for the regulatory protein YY1 are located close to the GC boxes and the octamer motif, to which this factor binds efficiently

The prevalence of audiometric notches in adolescents in Germany: The Ohrkan-study

Although there is concern about increasing hearing loss in adolescents caused by leisure noise exposure, prevalence data are scarce. In an US study, about 16-17% of adolescents were affected by audiometric notches. To estimate the prevalence of audiometric notches in adolescents in Germany, baseline data of the cohort study Ohrkan, recruitment during the school years 2009/2010 and 2010/2011 were analyzed. All students in grade 9 visiting any school in the city of Regensburg were eligible for participation. Data was collected via standardized questionnaires from students and their parents. In addition, students were asked to visit the University Clinics of Regensburg for ear examination including a tympanogram and the determination of hearing thresholds in air conduction audiometry. The prevalence of audiometric notches was determined in students with normal tympanogram in both ears and complete audiometry data. Audiometric notches were defined according to criteria used to analyse US data. Overall, 2149 students (1158 girls, 991 boys mainly aged 15-16 years) of the 3846 eligible adolescents (56%) participated. Among the 1843 adolescents with complete audiometry and tympanometry data, the prevalence of audiometric notches was 2.4% (95% confidence interval 1.7-3.1%). We could not confirm the high prevalence of audiometric notches as reported in National Health and Nutrition Examination Surveys for adolescents in the US. Differences in prevalence might be at least partly due to methodical differences in audiometry. Even if empirical evidence is presently ambiguous, it is reasonable to educate young people about the potential risks of high leisure noise exposure

Early indication of noise-induced hearing loss from PMP use in adolescents: A cross-sectional analysis

Context: Distortion product otoacoustic emissions (DPOAEs) may indicate preclinical noise-induced hearing loss (NIHL) in adolescents from unsafe personal music player (PMP) use. Aims: The objective, therefore, was to observe preclinical signs of NIHL in 9 th grade adolescents with clinically normal hearing by comparing DPOAE signals between different levels of A-weighted equivalent PMP exposure. Settings and Design: Subjects were recruited from all secondary-level schools located in the city of Regensburg, Germany during two academic years 2009/2010 and 2010/2011. Subjects and Methods: A-weighted equivalent sound pressure levels (SPLs) for a 40-hour work week (LAeq. 40h) were estimated from questionnaire responses on output and duration of PMP use of the previous week. Subjects were then categorized into four levels of exposure: 85 to = 90 A-weighted Decibel [dB(A)]. DPOAE signals were collected by trained audiological staff, applying a standard optimized protocol, at the Department of Otorhinolaryngology of the University Hospital Regensburg. Statistical Analysis Used: Mean DPOAE signals were compared between levels by unpaired t test. Novel linear regression models adjusting for other leisure noise exposures and with outcome variables DPoutcome and 4 kilo Hertz (kHz) DPOAEs estimated effects between levels. Results: A total of 1468 subjects (56% female, mostly aged 15 or 16 years) were available for analysis. Comparison of DPOAE means by PMP exposure typically showed no greater than 1 dB difference between groups. In fact, comparisons between >= 90 dB(A) and < 80 dB(A) presented the least differences in magnitude. Both DPoutcome and 4kHz linear regression models presented a weak association with the 4-level PMP exposure variable. An expected dose-response to PMP exposure was not observed in any analyses. Conclusions: DPOAE signal strength alone cannot indicate preclinical NIHL in adolescents

Total leisure noise exposure and its association with hearing loss among adolescents

<div><p></p><p><i>Objective:</i> To investigate total leisure noise exposure among adolescents and to assess its association with hearing. <i>Design:</i> Based on self-reported time spent on 19 leisure activities and associated mean sound pressure levels reported in the literature, total leisure noise exposure was evaluated and compared to noise at work limits (> 85 dB(A) = hazardous) in a cross-sectional survey. Tympanometry and pure-tone audiometry was performed in sound isolated rooms. <i>Study sample:</i> The study sample consists of 2143 pupils attending grade nine in any school in a German city 2009–2011 (mean age: 15.4 years; range: 13–19 years). Audiometric data were available for 1837 (85.8%) pupils (53.9% girls). <i>Results:</i> 41.9% of the 2143 adolescents who had provided self-reported data on leisure activities associated with noise exposure were estimated to be hazardously exposed to leisure time noise. The interaction of gender with total leisure time noise exposure was not significant. No association between leisure time noise exposure and audiometric notches could be detected. <i>Conclusion:</i> While hearing loss seems seldom in this age group, a high proportion of adolescents aged 15–16 years are exposed to noise levels during leisure time bearing long-term risks of hearing loss.</p></div