Age-dependent improvement of hearing ability in children: an international approach.

OBJECTIVES: Pure-tone auditory thresholds in children are below the standardized hearing threshold levels described by ). The development of hearing ability in Chinese and German children at different ages is analyzed and compared with data in the literature. Extended high frequencies above 8 kHz are included due to their vulnerability to noise. DESIGN: Ninety-one children in China and 197 children at a typical primary school in Germany underwent audiometric tests at 17 frequencies ranging from 125 Hz to 16 kHz. To analyze effects of age the children were assessed in age groups of 6 to 9, 9 to 12, and 13 to 16 years of age. RESULTS: Children in China and Germany have the poorest hearing sensitivity at low frequencies (below 1 kHz) and the best sensitivity at the extended high frequencies above 8 kHz. The mean deviations (both ears) from the standard thresholds for adults 18 to 25 years of age, averaged over all frequencies, are 6.7 dB for Chinese and 7.1 dB for German children in the youngest age groups. In the Chinese age group of 9- to 12-year olds the averaged threshold is 4.5 dB and for the same German age group 3.6 dB. For the Chinese age group of 13- to 16-year olds the averaged threshold is 3.3 dB. The improvements of the older German age group compared with the younger are significant at p < 0.05 and are nearly twice as high compared with the comparable Chinese age groups. CONCLUSIONS: Age-dependent improvements of hearing ability are evident in children and should be considered in evaluating audiometric test results. Audiometric tests in the extended high-frequency range could be used as an early warning system for future degeneration of hearing ability.

Pure-tone auditory threshold in school children.

To determine pure-tone auditory thresholds, 197 screened children at a typical primary school in a German town (~70,000 inhabitants) were examined. All children underwent a tympanometry and an audiometry at 17 frequencies from 125 to 16 kHz. Regarding age effects, two groups (6-8 and 9-12 years) were analyzed. The cross-sectional research was supplemented by a follow-up study with 35 children of the first graders 3 years later. School children have the poorest hearing sensitivity at low frequencies (below 1 kHz) and the best sensitivity at the extended high frequencies above 8 kHz. Hearing thresholds are rising significantly with age. Through all frequencies, averaged improvements were 3.8 dB (right ear) and 3.7 dB (left ear) at the cross-sectional study and 3.7 dB (right ear) and 5.1 dB (left ear) at the longitudinal study. The overall deviation (left and right) from the standard thresholds for adults were 7.4 and 3.6 dB for the younger and older age groups, respectively. The ear canal volume (ECV) measured by tympanometric tests was at mean with 1.06 cm(3) for the 6- to 8-year age group significantly lower (p < 0.001) in comparison with 1.18 cm(3) for the 9- to 12-year age group. Also, girls had significant (p < 0.001) smaller ECV (mean 1.07 cm(3)) than boys (1.17 cm(3)). Auditory performance improves with rising age in school children.

Neurogenic transdifferentiation of human adipose-derived stem cells? A critical protocol reevaluation with special emphasis on cell proliferation and cell cycle alterations.

Adipose-derived stem cells (ASCs) are reported to display multilineage differentiation potential, including neuroectodermal pathways. The aim of the present study was to critically re-evaluate the potential neurogenic (trans-)differentiation capacity of ASCs using a neurogenic induction protocol based on the combination of isobutylmethylxanthine (IBMX), indomethacin and insulin. ASCs isolated from lipo-aspirate samples of five healthy female donors were characterized and potential neurogenic (trans-)differentiation was assessed by means of immunohistochemistry and gene expression analyses. Cell proliferation and cell cycle alterations were studied, and the expression of CREB/ATF transcription factors was analyzed. ASCs expressed CD59, CD90 and CD105, and were tested negative for CD34 and CD45. Under neurogenic induction, ASCs adopted a characteristic morphology comparable to neur(on)al progenitors and expressed musashi1, ß-III-tubulin and nestin. Gene expression analyses revealed an increased expression of ß-III-tubulin, GFAP, vimentin and BDNF, as well as SOX4 in induced ASCs. Cell proliferation was significantly reduced under neurogenic induction; cell cycle analyses showed a G2-cell cycle arrest accompanied by differential expression of key regulators of cell cycle progression. Differential expression of CREB/ATF transcription factors could be observed on neurogenic induction, pointing to a decisive role of the cAMP-CREB/ATF system. Our findings may point to a potential neurogenic (trans-)differentiation of ASCs into early neur(on)al progenitors, but do not present definite evidence for it. Especially, the adoption of a neural progenitor cell-like morphology must not automatically be misinterpreted as a specific characteristic of a respective (trans-)differentiation process, as this may as well be caused by alterations of cell cycle progression.

Expression of sphingosine-1-phosphate receptors and lysophosphatidic acid receptors on cultured and xenografted human colon, breast, melanoma, and lung tumor cells.

The lysophospholipids sphingosine-1-phosphate (S1P) and lysophosphatidic acid (LPA) are small lipid molecules with a variety of physiological roles. Additionally, their involvement in the initiation and progression of malignant tumors has been increasingly recognized in recent years. However, the data on the expression of S1P and LPA receptors on different cancer cells are very few. Real-time polymerase chain reaction was used for the analysis of mRNA expression of five S1P((1-5)) and three LPA((1-3)) receptors on a large panel of 13 colon, breast, melanoma, and lung cancer cell lines. Furthermore, the modulation of S1P and LPA receptor mRNA expression was studied upon xenotransplantation of tumor cells into severe combined immunodeficient (SCID) mice. The S1P and LPA receptors were expressed to a variable degree on all tumor cell lines tested (with exception of colon cancer SW480). Most notably, tumor cell lines in vitro expressed S1P(2) mRNA that was down-regulated upon xenotransplantation, whereas LPA(2) receptor mRNA was strongly expressed both in vitro and in vivo (except by breast cancer cells). The latter was especially distinctive for small cell lung tumor cells. The S1P and LPA receptors are differentially expressed on tumor cell lines in vitro. Their expression is modulated upon xenografting into SCID mice in vivo.

High concentrations of phenylalanine stimulate peroxisome proliferator-activated receptor gamma: implications for the pathophysiology of phenylketonuria.

If left untreated, the common inherited metabolic disorder phenylketonuria (PKU) presents with mental retardation and reduced brain weight. The underlying molecular reasons for these deficits are unknown so far. Using human neuroblastoma cells as a model for normal human neuroblasts, elevated phenylalanine concentrations suppressed proliferation of these cells in culture. Furthermore, microarray and functional assays of these cells revealed that both phenylalanine and the known PPARgamma agonist rosiglitazone regulated the same set of genes causing subsequently similar changes in the functional assays. The lowered brain weight of PKU patients may thus be the result of reduced neuroblast proliferation caused by phenylalanine-induced stimulation of PPARgamma receptors. The observation that high concentrations of small substrates can activate receptors may serve as a new paradigm for other metabolic diseases and provides a new approach for the treatment of these disorders by application of specific receptor antagonists.

Noise exposure and auditory thresholds of military musicians: a follow up study.

BACKGROUND: Military musicians are working in a noisy environment with high sound exposure levels above the international standards. Aim of the current study is to find out, whether they develop the expected hearing impairments. Adherence to the regulations for prevention in musicians is more difficult than in other occupational fields. METHODS: In an interval of 13.3 years, 36 out of 58 male military musicians of a German army music corps were subjected twice to an audiometric audit. There were no exclusion criteria apart from acute ENT infections (three musicians). These results were compared with one another and evaluated by means of statistical methods for relationships with several factors. RESULTS: At frequencies below 3 kHz, the follow-up audiograms were up to 5 dB better than the preliminary examination. From 4 kHz up to 8 kHz the preliminary investigations showed less hearing impairment. Averaging all frequencies the improvement of hearing ability was around 1 dB. Above 1 kHz the average hearing of the right ear was up to 7 dB better than that of the left ear. Age-induced hearing loss was 3 to 8 dB lower than predicted by ISO standards over the entire frequency range. The side of the ear (right/left) and the frequency (3, 4, and 6 kHz) were significant (p < 0.05) in hearing loss, whereas the influence of the instrument and the acoustic traumata were not. CONCLUSION: Despite the high noise levels, the average hearing ability of the 36 military musicians during the investigation period only slightly deteriorated in the noise-sensitive frequencies (3, 5 and 6 kHz). Music may be less harmful than industrial noise, or the long-term auditory training of the musicians leads to a delayed presbycusis.

Noise exposure and auditory thresholds of German airline pilots: a cross-sectional study.

OBJECTIVE: The cockpit workplace of airline pilots is a noisy environment. This study examines the hearing thresholds of pilots with respect to ambient noise and communication sound. METHODS: The hearing of 487 German pilots was analysed by audiometry in the frequency range of 125 Hz-16 kHz in varying age groups. Cockpit noise (free-field) data and communication sound (acoustic manikin) measurements were evaluated. RESULTS: The ambient noise levels in cockpits were found to be between 74 and 80 dB(A), and the sound pressure levels under the headset were found to be between 84 and 88 dB(A).The left-right threshold differences at 3, 4 and 6 kHz show evidence of impaired hearing at the left ear, which worsens by age.In the age groups <40/≥40 years the mean differences at 3 kHz are 2/3 dB, at 4 kHz 2/4 dB and at 6 kHz 1/6 dB.In the pilot group which used mostly the left ear for communication tasks (43 of 45 are in the older age group) the mean difference at 3 kHz is 6 dB, at 4 kHz 7 dB and at 6 kHz 10 dB. The pilots who used the headset only at the right ear also show worse hearing at the left ear of 2 dB at 3 kHz, 3 dB at 4 kHz and at 6 kHz. The frequency-corrected exposure levels under the headset are 7-11 dB(A) higher than the ambient noise with an averaged signal-to-noise ratio for communication of about 10 dB(A). CONCLUSIONS: The left ear seems to be more susceptible to hearing loss than the right ear. Active noise reduction systems allow for a reduced sound level for the communication signal below the upper exposure action value of 85 dB(A) and allow for a more relaxed working environment for pilots.

A DNA barcode library for Germany's mayflies, stoneflies and caddisflies (Ephemeroptera, Plecoptera and Trichoptera).

Mayflies, stoneflies and caddisflies (Ephemeroptera, Plecoptera and Trichoptera) are prominent representatives of aquatic macroinvertebrates, commonly used as indicator organisms for water quality and ecosystem assessments. However, unambiguous morphological identification of EPT species, especially their immature life stages, is a challenging, yet fundamental task. A comprehensive DNA barcode library based upon taxonomically well-curated specimens is needed to overcome the problematic identification. Once available, this library will support the implementation of fast, cost-efficient and reliable DNA-based identifications and assessments of ecological status. This study represents a major step towards a DNA barcode reference library as it covers for two-thirds of Germany's EPT species including 2,613 individuals belonging to 363 identified species. As such, it provides coverage for 38 of 44 families (86%) and practically all major bioindicator species. DNA barcode compliant sequences (≥500 bp) were recovered from 98.74% of the analysed specimens. Whereas most species (325, i.e., 89.53%) were unambiguously assigned to a single Barcode Index Number (BIN) by its COI sequence, 38 species (18 Ephemeroptera, nine Plecoptera and 11 Trichoptera) were assigned to a total of 89 BINs. Most of these additional BINs formed nearest neighbour clusters, reflecting the discrimination of geographical subclades of a currently recognized species. BIN sharing was uncommon, involving only two species pairs of Ephemeroptera. Interestingly, both maximum pairwise and nearest neighbour distances were substantially higher for Ephemeroptera compared to Plecoptera and Trichoptera, possibly indicating older speciation events, stronger positive selection or faster rate of molecular evolution.

Critical behavior of nonequilibrium phase transitions to magnetically ordered states.

We describe nonequilibrium phase transitions in arrays of dynamical systems with cubic nonlinearity driven by multiplicative Gaussian white noise. Depending on the sign of the spatial coupling we observe transitions to ferromagnetic or antiferromagnetic ordered states. We discuss the phase diagram, the order of the transitions, and the critical behavior. For global coupling we show analytically that the critical exponent of the magnetization exhibits a transition from the value 1/2 to a nonuniversal behavior depending on the ratio of noise strength to the magnitude of the spatial coupling.

[Impact of gender on the utilization of outpatient health service for adult ADHD]. / Welchen Einfluss hat das Geschlecht auf das Inanspruchnahmeverhalten bei adulter ADHS im Rahmen einer Spezialambulanz?

OBJECTIVE: There is only scarce knowledge of gender differences in adult ADHD. Thus, we studied a large population of adults referred to a specialized ambulance for adult ADHD for possible gender differences regarding age, ADHD core and associated psychopathology, severity of symptoms and subjective burden from the disorder. METHODS: We analyzed data from 776 adult patients, who had been referred to a specialized ambulance for ADHD. 275 male and 236 female patients were diagnosed with ADHD. Standardized self-rating and expert-rating instruments of the Homburg ADHD Scales for adults (HASE) were used for diagnosis and assessment. RESULTS: Male and female patients did not differ significantly regarding their prevalence of admittance, age at diagnosis of ADHD, ADHD subtype according to DSM-IV, symptom severity and subjective burden from the disorder. CONCLUSIONS: More female than male patients as could be expected from epidemiological data were referred to the ambulance suggesting that males with ADHD are less disposed for psychiatric support. No major differences regarding clinical aspects of ADHD have to be considered between male and female patients, except a higher prevalence of symptoms of emotional dysregulation, which are more prominent in female patients.