Publications by authors named "Christian Berger"

88 Publications

Tissue flossing of the thigh increases isometric strength acutely but has no effects on flexibility or jump height.

Eur J Sport Sci 2020 Dec 14:1-11. Epub 2020 Dec 14.

Institute of Sports Science, University of Graz, Graz, Austria.

The purpose of this study was to investigate the effects of a single floss band treatment of the thigh on hip and knee range of motion (ROM), knee extensor passive resistive torque (PRT), knee extensor maximum voluntary contraction (MVC) torque, and countermovement jump (CMJ) height. Sixteen healthy male volunteers were tested before and after both the flossing treatment and the control condition, in random order. For the flossing treatment, the floss band was wound around both thighs for 120 s, and the subject was then asked to perform 20 squats. During the control treatment, only the 20 squats were performed. Before and after the treatments, knee and hip ROM were assessed using a Thomas test with 3D motion caption. The PRT and MVC of the knee extensors were measured with a dynamometer, and the electromyographic (EMG) signal was collected from the vastus lateralis. CMJs were performed on a force plate. Compared to the control condition, the flossing treatment showed a positive effect on the MVC of the knee extensors (= 0.01); however, no effects on hip ROM (= 0.58), knee ROM (= 0.37), CMJ height (= 0.75), or PRT (= 0.22) were observed. Correlation analyses revealed that the increase in MVC was not significantly related to changes in the tension of the muscle-tendon unit (= -0.13; = 0.64) or vastus lateralis EMG (= 0.44; = 0.10). Since the increase in MVC cannot be explained by changes of the mechanical (PRT) or neuromuscular (EMG) properties, we speculate that an enhancement of growth hormone and norepinephrine levels following the compression release is instead responsible for the increase in MVC.
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http://dx.doi.org/10.1080/17461391.2020.1853818DOI Listing
December 2020

High-phosphorus diets reduce aortic lesions and cardiomyocyte size and modify lipid metabolism in Ldl receptor knockout mice.

Sci Rep 2020 11 27;10(1):20748. Epub 2020 Nov 27.

Institute of Agricultural and Nutritional Sciences, Martin Luther University Halle-Wittenberg, Von-Danckelmann-Platz 2, 06120, Halle (Saale), Germany.

The consumption of phosphorus in Western populations largely exceeds the recommended intake, while vitamin D supply is often insufficient. Both situations are linked to an increased cardiovascular risk. A 17-week two-factorial study with Ldl receptor mice was conducted to investigate the cardiovascular impact of dietary phosphorus [adequate (0.3%; P) vs. high (1.5%; P)] in combination with a low (50 IU/kg; D) or adequate vitamin D diet (1000 IU/kg; D). The data demonstrate that mice fed the P vs. P diets developed smaller vascular lesions (p = 0.013) and cardiac hypotrophy (p = 0.011), which were accompanied by diminished IGF1 and insulin signalling activity in their hearts. Vitamin D showed no independent effect on atherogenesis and heart morphology. Feeding P vs. P diets resulted in markedly reduced serum triacylglycerols (p < 0.0001) and cholesterol (p < 0.0001), higher faecal lipid excretion (p < 0.0001) and a reduced mRNA abundance of hepatic sterol exporters and lipoprotein receptors. Minor hypocholesterolaemic and hypotriglyceridaemic effects were also found in mice fed the D vs. D diets (p = 0.048, p = 0.026). To conclude, a high phosphorus intake strongly affected the formation of vascular lesions, cardiac morphology, and lipid metabolism, although these changes are not indicative of an increased cardiovascular risk.
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http://dx.doi.org/10.1038/s41598-020-77509-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7695849PMC
November 2020

Prior Anticoagulation in Patients with Ischemic Stroke and Atrial Fibrillation.

Ann Neurol 2021 01 17;89(1):42-53. Epub 2020 Oct 17.

Department of Neurology, Inselspital, Bern University Hospital, and University of Bern, Bern, Switzerland.

Objective: The aim was to evaluate, in patients with atrial fibrillation (AF) and acute ischemic stroke, the association of prior anticoagulation with vitamin K antagonists (VKAs) or direct oral anticoagulants (DOACs) with stroke severity, utilization of intravenous thrombolysis (IVT), safety of IVT, and 3-month outcomes.

Methods: This was a cohort study of consecutive patients (2014-2019) on anticoagulation versus those without (controls) with regard to stroke severity, rates of IVT/mechanical thrombectomy, symptomatic intracranial hemorrhage (sICH), and favorable outcome (modified Rankin Scale score 0-2) at 3 months.

Results: Of 8,179 patients (mean [SD] age, 79.8 [9.6] years; 49% women), 1,486 (18%) were on VKA treatment, 1,634 (20%) on DOAC treatment at stroke onset, and 5,059 controls. Stroke severity was lower in patients on DOACs (median National Institutes of Health Stroke Scale 4, [interquartile range 2-11]) compared with VKA (6, [2-14]) and controls (7, [3-15], p < 0.001; quantile regression: β -2.1, 95% confidence interval [CI] -2.6 to -1.7). The IVT rate in potentially eligible patients was significantly lower in patients on VKA (156 of 247 [63%]; adjusted odds ratio [aOR] 0.67; 95% CI 0.50-0.90) and particularly in patients on DOACs (69 of 464 [15%]; aOR 0.06; 95% CI 0.05-0.08) compared with controls (1,544 of 2,504 [74%]). sICH after IVT occurred in 3.6% (2.6-4.7%) of controls, 9 of 195 (4.6%; 1.9-9.2%; aOR 0.93; 95% CI 0.46-1.90) patients on VKA and 2 of 65 (3.1%; 0.4-10.8%, aOR 0.56; 95% CI 0.28-1.12) of those on DOACs. After adjustments for prognostic confounders, DOAC pretreatment was associated with a favorable 3-month outcome (aOR 1.24; 1.01-1.51).

Interpretation: Prior DOAC therapy in patients with AF was associated with decreased admission stroke severity at onset and a remarkably low rate of IVT. Overall, patients on DOAC might have better functional outcome at 3 months. Further research is needed to overcome potential restrictions for IVT in patients taking DOACs. ANN NEUROL 2021;89:42-53.
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http://dx.doi.org/10.1002/ana.25917DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7756294PMC
January 2021

The MitraClip Procedure in Patients With Moderate Resting but Severe Exercise-Induced Mitral Regurgitation.

J Invasive Cardiol 2020 Jan;32(1):E1-E8

Department of Cardiology, Charité Berlin, Campus Benjamin Franklin, Hindenburgdamm 30, 12203 Berlin, Germany.

Background: Optimal timing for percutaneous mitral regurgitation (MR) treatment using MitraClip (Abbott Vascular) remains unclear. We evaluated the outcome after MitraClip in patients with moderate resting MR, progressing to severe exercise- induced MR (MR2+) compared to patients with severe resting MR (MR3).

Methods: We retrospectively investigated 221 patients undergoing MitraClip. All-cause deaths and heart failure (HF) hospitalizations were assessed as the combined primary endpoint.

Results: We identified 55 MR2+ and 166 MR3 patients. At baseline, MR3 patients showed higher STS scores (6.7 ± 7.3 vs 4.4 ± 5.5; P<.01), more HF hospitalizations in the 2 years prior to the procedure (51% vs 29%; P<.01), worse left ventricular ejection fraction (44.9 ± 16.5% vs 52.5 ± 14.3%; P<.01), larger left ventricular end-diastolic diameter (LVEDd; 57.0 ± 9.3 mm vs 51.7 ± 8.2 mm; P<.001), and larger left atrial volumes (118.3 ± 55.8 mL vs 98.6 ± 35.2 mL; P=.02). Long-term outcome according to the combined endpoint was significantly worse in MR3 patients (P=.01). HF hospitalizations significantly declined in both groups 2 years after MitraClip (P<.001 in MR3 patients, P=.03 in MR2+ patients). Multivariate Cox regression analysis revealed LVEDd (hazard ratio, 1.035; 95% confidence interval, 1.005-1.066; P=.02) and previous HF hospitalizations (hazard ratio, 1.813; 95% confidence interval, 1.016-3.234; P=.04) as strong outcome predictors.

Conclusions: Symptomatic patients with moderate resting and severe exercise-induced MR during handgrip echocardiography may represent an MR cohort at an earlier disease stage with improved treatment response following MitraClip implantation compared to individuals with severe resting MR. Larger left ventricular diameters and preprocedural HF hospitalizations were identified as independent adverse outcome predictors.
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January 2020

The Interplay of Adolescents' Aggression and Victimization with Friendship and Antipathy Networks within an Educational Prosocial Intervention.

J Youth Adolesc 2019 Oct 3;48(10):2005-2022. Epub 2019 Sep 3.

Department of Sociology, Interuniversity Center for Social Science Theory and Methodology (ICS), University of Groningen, Grote Rozenstraat 31, 9712 TG, Groningen, The Netherlands.

How the interplay between peer relationships and behaviors unfolds and how this differs between classrooms is an understudied topic. This study examined whether adolescents befriend or dislike peers whom they consider as aggressor or victim and whether these results differ in classrooms that received an intervention to promote prosocial behavior compared to classrooms without the intervention. The sample was composed of 659 seventh graders (M = 12.32; 48% girls) from nine intervention and seven control classrooms in eight schools in Santiago, Chile. It was hypothesized that adolescents in intervention classrooms would be less befriended and more disliked by classmates who considered them as aggressors, and more befriended and less disliked by classmates who considered them as victims, compared to control classrooms. Longitudinal multiplex social network analyses (RSiena) indicate that antipathies toward peers considered as aggressive and victimized were significantly lower in intervention classrooms than in control classrooms, but no significant differences were found for friendships. These findings suggest that the impact of an educational intervention may go beyond changing individual behavior and extend to the way peer relations develop in classrooms.
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http://dx.doi.org/10.1007/s10964-019-01105-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6813759PMC
October 2019

TAF-ChIP: an ultra-low input approach for genome-wide chromatin immunoprecipitation assay.

Life Sci Alliance 2019 08 22;2(4). Epub 2019 Jul 22.

Institute of Developmental Biology and Neurobiology, University of Mainz, Mainz, Germany

Chromatin immunoprecipitation (ChIP) followed by next generation sequencing (ChIP-Seq) is a powerful technique to study transcriptional regulation. However, the requirement of millions of cells to generate results with high signal-to-noise ratio precludes it in the study of small cell populations. Here, we present a tagmentation-assisted fragmentation ChIP (TAF-ChIP) and sequencing method to generate high-quality histone profiles from low cell numbers. The data obtained from the TAF-ChIP approach are amenable to standard tools for ChIP-Seq analysis, owing to its high signal-to-noise ratio. The epigenetic profiles from TAF-ChIP approach showed high agreement with conventional ChIP-Seq datasets, thereby underlining the utility of this approach.
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http://dx.doi.org/10.26508/lsa.201900318DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6653780PMC
August 2019

Classroom ability composition and the role of academic performance and school misconduct in the formation of academic and friendship networks.

J Sch Psychol 2019 06 28;74:58-73. Epub 2019 May 28.

Department of Sociology, University of Groningen, Grote Rozenstraat 31, Groningen, 9712, TG, the Netherlands. Electronic address:

This paper examined the association between friendship and academic networks and how the connections these networks have with academic performance and school misconduct differ when comparing three types of classrooms where students were grouped based on their academic ability (i.e., high-, low-, and mixed-ability). The sample was composed of 528 seventh to ninth graders (M = 15; 64.1% girls) from 12 classrooms (four in each category of ability grouping) across two waves in five schools in Chile. The effects of academic performance and school misconduct on receiving academic and friendship nominations were examined, as well as the interplay between academic and friendship relationships. Furthermore, the extent to which similarity in adolescents' academic performance and school misconduct contributed to the formation and maintenance of academic and friendship relationships was examined. Sex, socioeconomic status, and structural network features were also taken into account. Longitudinal social network analyses (RSiena) indicated that (1) in high-ability classrooms students chose high-achieving peers as academic partners; (2) in high-ability classrooms students avoided deviant peers (i.e., those high in school misconduct) as academic partners; and (3) academic relationships led to friendships, and vice versa, in both high- and low-ability classrooms. Whereas the interplay of friendship and academic relationships was similar in high- and low-ability classrooms, the formation and maintenance of academic networks unfolded differently in these two types of classrooms.
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http://dx.doi.org/10.1016/j.jsp.2019.05.006DOI Listing
June 2019

STRIPAK Members Orchestrate Hippo and Insulin Receptor Signaling to Promote Neural Stem Cell Reactivation.

Cell Rep 2019 06;27(10):2921-2933.e5

Faculty of Medicine and Dentistry, University of Plymouth, PL6 8BU Plymouth, UK. Electronic address:

Adult stem cells reactivate from quiescence to maintain tissue homeostasis and in response to injury. How the underlying regulatory signals are integrated is largely unknown. Drosophila neural stem cells (NSCs) also leave quiescence to generate adult neurons and glia, a process that is dependent on Hippo signaling inhibition and activation of the insulin-like receptor (InR)/PI3K/Akt cascade. We performed a transcriptome analysis of individual quiescent and reactivating NSCs harvested directly from Drosophila brains and identified the conserved STRIPAK complex members mob4, cka, and PP2A (microtubule star, mts). We show that PP2A/Mts phosphatase, with its regulatory subunit Widerborst, maintains NSC quiescence, preventing premature activation of InR/PI3K/Akt signaling. Conversely, an increase in Mob4 and Cka levels promotes NSC reactivation. Mob4 and Cka are essential to recruit PP2A/Mts into a complex with Hippo kinase, resulting in Hippo pathway inhibition. We propose that Mob4/Cka/Mts functions as an intrinsic molecular switch coordinating Hippo and InR/PI3K/Akt pathways and enabling NSC reactivation.
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http://dx.doi.org/10.1016/j.celrep.2019.05.023DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6581792PMC
June 2019

Combination of problem-based learning with high-fidelity simulation in CPR training improves short and long-term CPR skills: a randomised single blinded trial.

BMC Med Educ 2019 May 31;19(1):180. Epub 2019 May 31.

Department of Anesthesiology, University Medicine Greifswald, Greifswald, Germany.

Background: Performance of sufficient cardiopulmonary resuscitation (CPR) by medical personnel is critical to improve outcomes during cardiac arrest. It has however been shown that even health care professionals possess a lack of knowledge and skills in CPR performance. The optimal method for teaching CPR remains unclear, and data that compares traditional CPR instructional methods with newer modalities of CPR instruction are needed. We therefore conducted a single blinded, randomised study involving medical students in order to evaluate the short- and long-term effects of a classical CPR education compared with a bilateral approach to CPR training, consisting of problem-based learning (PBL) plus high fidelity simulation.

Methods: One hundred twelve medical students were randomized during a curricular anaesthesiology course to a control (n = 54) and an intervention (n = 58) group. All participants were blinded to group assignment and partook in a 30-min-lecture on CPR basics. Subsequently, the control group participated in a 90-min tutor-guided CPR hands-on-training. The intervention group took part in a 45-min theoretical PBL module followed by 45 min of high fidelity simulated CPR training. The rate of participants recognizing clinical cardiac arrest followed by sufficiently performed CPR was the primary outcome parameter of this study. CPR performance was evaluated after the intervention. In addition, a follow-up evaluation was conducted after 6 months.

Results: 51.9% of the intervention group met the criteria of sufficiently performed CPR as compared to only 12.5% in the control group on the day of the intervention (p = 0.007). Hands-off-time as a marker for CPR continuity was significantly less in the intervention group (24.0%) as compared to the control group (28.3%, p = 0.007, Hedges' g = 1.55). At the six-month follow-up, hands-off-time was still significantly lower in the intervention group (23.7% vs. control group: 31.0%, p = 0.006, Hedges' g = 1.88) but no significant difference in sufficiently performed CPR was detected (intervention group: 71.4% vs. control group: 54.5%, p = 0.55).

Conclusion: PBL combined with high fidelity simulation training leads to a measurable short-term increase in initiating sufficient CPR by medical students immediately after training as compared to classical education. At six month post instruction, these differences remained only partially.
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http://dx.doi.org/10.1186/s12909-019-1626-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6544917PMC
May 2019

Ternary nanocomposites of reduced graphene oxide, polyaniline and hexaniobate: hierarchical architecture and high polaron formation.

Beilstein J Nanotechnol 2018 26;9:2936-2946. Epub 2018 Nov 26.

School of Materials and National Graphene Institute, The University of Manchester, Booth St E, Manchester M13 9PL, United Kingdom.

Nanostructured systems, such as nanocomposites, are potential materials for usage in different fields since synergistic effects of their components at the nanoscale domain may improve physical/chemical properties when compared to individual phases. We report here the preparation and characterisation of a new nanocomposite composed of polyaniline (PANI), reduced graphene oxide (rGO) and hexaniobate (hexNb) nanoscrolls. Atomic force microscopy images show an interesting architecture of rGO flakes coated with PANI and decorated by hexNb. Such features are attributed to the high stability of the rGO flakes prepared at room temperature. Detailed characterisation by X-ray photoelectron and Raman spectroscopies indicates an intermediate reduction degree for the rGO component and high doping degree of the PANI chains compared to the neat polymer. The latter feature can be attributed to cooperative effects of PANI chains with rGO flakes and hexNb nanoscrolls, which promote conformational changes of the polymer backbone (secondary doping). Spectroscopic and electrochemistry data indicate a synergetic effect on the ternary nanocomposite, which is attributed to interactions between the components resulting from the morphological aspects. Therefore, the new nanocomposite presents promising properties for development of new materials in the film form on substrates for sensing or corrosion protection for example.
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http://dx.doi.org/10.3762/bjnano.9.272DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6278754PMC
November 2018

Friendship Selection and Influence Processes for Physical Aggression and Prosociality: Differences between Single-Sex and Mixed-Sex Contexts.

Sex Roles 2018 13;78(9):625-636. Epub 2017 Sep 13.

2Department of Psychology, Pontificia Universidad Católica de Chile, Santiago, Chile.

The present study examined to what extent selection and influence processes for physical aggression and prosociality in friendship networks differed between sex-specific contexts (i.e., all-male, all-female, and mixed-sex classrooms), while controlling for perceived popularity. Whereas selection processes reflect how behaviors shape friendships, influence processes reveal the reversed pattern by indicating how friends affect individual behaviors. Data were derived from a longitudinal sample of early adolescents from Chile. Four all-male classrooms ( = 150 male adolescents), four all-female classrooms ( = 190 female adolescents), and eight mixed-sex classrooms ( = 272 students) were followed one year from grades 5 to 6 ( = 13). Analyses were conducted by means of stochastic-actor-based modeling as implemented in RSIENA. Although it was expected that selection and influence effects for physical aggression and prosociality would vary by context, these effects showed remarkably similar trends across all-male, all-female, and mixed-sex classrooms, with physical aggression reducing and with prosociality increasing the number of nominations received as best friend in all-male and particularly all-female classrooms. Further, perceived popularity increased the number of friendship nominations received in all contexts. Influence processes were only found for perceived popularity, but not for physical aggression and prosociality in any of the three contexts. Together, these findings highlight the importance of both behaviors for friendship selection independent of sex-specific contexts, attenuating the implications of these gendered behaviors for peer relations.
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http://dx.doi.org/10.1007/s11199-017-0818-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5897469PMC
September 2017

Adolescents' Friendships, Academic Achievement, and Risk Behaviors: Same-Behavior and Cross-Behavior Selection and Influence Processes.

Child Dev 2019 03 16;90(2):e192-e211. Epub 2018 Feb 16.

University of Groningen.

This study examined to what extent adolescents' and their friends' risk behaviors (i.e., delinquency and alcohol use) hinder or promote their academic achievement (grade point average [GPA]), and vice versa. Longitudinal data were used (N = 1,219 seventh- to ninth-grade adolescents; M  = 13.69). Results showed that risk behaviors negatively affected adolescents' GPA, whereas GPA protected against engaging in risk behaviors. Moreover, adolescents tended to select friends who have similar behaviors and friends' behaviors became more similar over time (same-behavior selection and influence). Furthermore, although same-behavior effects seemed to dominate, evidence was found for some cross-behavior selection effects and a tendency in seventh grade for cross-behavior influence effects. Concluding, it is important to investigate the interplay between different behaviors with longitudinal social network analysis.
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http://dx.doi.org/10.1111/cdev.13045DOI Listing
March 2019

Capacitive pressure sensing with suspended graphene-polymer heterostructure membranes.

Nanoscale 2017 Nov;9(44):17439-17449

School of Materials and National Graphene Institute, University of Manchester, Manchester, M13 9PL, UK.

We describe the fabrication and characterisation of a capacitive pressure sensor formed by an ultra-thin graphene-polymer heterostructure membrane spanning a large array of micro-cavities each up to 30 μm in diameter with 100% yield. Sensors covering an area of just 1 mm show reproducible pressure transduction under static and dynamic loading up to pressures of 250 kPa. The measured capacitance change in response to pressure is in good agreement with calculations. Further, we demonstrate high-sensitivity pressure sensors by applying a novel strained membrane transfer and optimising the sensor architecture. This method enables suspended structures with less than 50 nm of air dielectric gap, giving a pressure sensitivity of 123 aF Pa mm over a pressure range of 0 to 100 kPa.
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http://dx.doi.org/10.1039/c7nr04621aDOI Listing
November 2017

Novel Tenascin-C Haplotype Modifies the Risk for a Failure to Heal After Rotator Cuff Repair.

Am J Sports Med 2017 Nov 27;45(13):2955-2964. Epub 2017 Sep 27.

Center for Medical Statistics, Informatics, and Intelligent Systems, Medical University of Vienna, Vienna, Austria.

Background: Several single-nucleotide polymorphisms (SNPs) in the TNC gene have recently been found to be associated with degenerative rotator cuff tears.

Hypothesis: Exonic SNPs in the TNC gene are related to the risk for a failure to heal after rotator cuff repair.

Study Design: Case-control study; Level of evidence, 3.

Methods: A total of 302 patients from the Vienna area and European Caucasian ancestry underwent mini-open rotator cuff repair for a full-thickness superior or posterosuperior tear and were assessed for the integrity of the repair 1 year postoperatively with a real-time 7.5- to 10-MHz ultrasound linear array transducer. Outcomes were classified as intact (complete footprint coverage), small (<200 mm), or large (≥200 mm) recurrent defect. Patients were genotyped for 15 previously identified risk SNPs within a 49-kbp segment of the TNC gene with the KASP genotyping technology or the Ion-Torrent Personal Genome Machine System.

Results: All recurrent defects were atraumatic failures, and the overall failure rate was 39.7%. Of the traditional risk factors, only the initial tear size was significantly associated with a failure to heal. In a multinomial logistic regression model, the T allele at rs1138545 [C>T] was protective for a large recurrent defect (odds ratio = 0.16; 95% CI, 0.09-0.31). The role of rs1138545 was further backed by haplotype analysis, which showed that the combination of the C allele at rs1138545 [C>T], the A allele at rs2104772 [A>T], and the G allele at rs10759752 [A>G] formed the risk-related haplotype [CAG]. The CAG haplotype was associated with large recurrent defects ( P < .0001; haplotype frequency, 0.394; haplotype score, 4.518). Exonic marker rs1138545 transcribed into all isoforms of the TNC protein, whereas exonic marker rs2104772, which has been associated with Achilles tendinopathy before, transcribed only into large isoforms of the TNC protein.

Conclusion: Recurrent defects after rotator cuff repairs are clinically relevant, and a heritable component of the disorder is plausible on the basis of a genetic association with 8 TNC variants. Characterization of TNC sequences that favor tendon healing will help engineer new products in regenerative medicine.
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http://dx.doi.org/10.1177/0363546517729810DOI Listing
November 2017

Temperature-responsive miRNAs in orchestrate adaptation to different ambient temperatures.

RNA 2017 09 19;23(9):1352-1364. Epub 2017 Jun 19.

Institute of Organismic and Molecular Evolutionary Biology, Anthropology, Johannes Gutenberg University, 55099 Mainz, Germany.

The majority of genes are expressed in a temperature-dependent manner, but the way in which small RNAs may contribute to this effect is completely unknown as we currently lack an idea of how small RNA transcriptomes change as a function of temperature. Applying high-throughput sequencing techniques complemented by quantitative real-time PCR experiments, we demonstrate that altered ambient temperature induces drastic but reversible changes in sequence composition and total abundance of both miRNA and piRNA populations. Further, mRNA sequencing reveals that the expression of miRNAs and their predicted target transcripts correlates inversely, suggesting that temperature-responsive miRNAs drive adaptation to different ambient temperatures on the transcriptome level. Finally, we demonstrate that shifts in temperature affect both primary and secondary piRNA pools, and the observed aberrations are consistent with altered expression levels of the involved Piwi-pathway factors. We further reason that enhanced ping-pong processing at 29°C is driven by dissolved RNA secondary structures at higher temperatures, uncovering target sites that are not accessible at low temperatures. Together, our results show that small RNAs are an important part of epigenetic regulatory mechanisms that ensure homeostasis and adaptation under fluctuating environmental conditions.
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http://dx.doi.org/10.1261/rna.061119.117DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5558905PMC
September 2017

Ethnic Identity Development and Acculturation Preferences Among Minority and Majority Youth: Norms and Contact.

Child Dev 2017 05 20;88(3):743-760. Epub 2017 Mar 20.

Pontificia Universidad Católica.

This article tests a longitudinal model of the antecedents and consequences of changes in identification with indigenous (Mapuche) among indigenous and nonindigenous youth in Chilean school contexts over a 6-month period (633 nonindigenous and 270 Mapuche students, M  = 12.47 and 12.80 years, respectively). Results revealed that in-group norms supporting contact and quality of intergroup contact at Time 1 predicted student's changes in Mapuche identification at Time 2, which in turn predicted changes in support for adoption of Chilean culture and maintenance of Mapuche culture at Time 2; some of the relationships between these variables were found to be moderated by age and ethnicity. Conceptual and policy implications are addressed in the Discussion.
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http://dx.doi.org/10.1111/cdev.12788DOI Listing
May 2017

How School Norms, Peer Norms, and Discrimination Predict Interethnic Experiences Among Ethnic Minority and Majority Youth.

Child Dev 2016 09;87(5):1436-51

Pontificia Universidad Católica de Chile.

This research tests how perceived school and peer norms predict interethnic experiences among ethnic minority and majority youth. With studies in Chile (654 nonindigenous and 244 Mapuche students, M = 11.20 and 11.31 years) and the United States (468 non-Hispanic White and 126 Latino students, M = 11.66 and 11.68 years), cross-sectional results showed that peer norms predicted greater comfort in intergroup contact, interest in cross-ethnic friendships, and higher contact quality, whereas longitudinal results showed that school norms predicted greater interest in cross-ethnic friendships over time. Distinct effects of school and peer norms were also observed for ethnic minority and majority youth in relation to perceived discrimination, suggesting differences in how they experience cross-ethnic relations within school environments.
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http://dx.doi.org/10.1111/cdev.12608DOI Listing
September 2016

Adolescent Peer Relations and Socioemotional Development in Latin America: Translating International Theory into Local Research.

New Dir Child Adolesc Dev 2016 Jun;2016(152):45-58

Pontificia Universidad Católica de Chile.

Peer relations constitute a main developmental context for adolescents. Peers offer an instance for identity definition and set the norms of acceptable and valued characteristics, behaviors, and attitudes, representing a societal model that allows and restrains avenues for adolescents' socioemotional development. The present article departs from these considerations to review research on adolescents' peer relations in Latin America from a socioemotional perspective. First, approaches to adolescence are discussed, with a main focus on attachment and identity theories, based on a bioecological framework. Then, a review of research in Latin America on friendships, school climate, and intergroup relations is presented. The discussion addresses the tension between theories and evidence generated in developed societies and highlights the particularities of Latin American youth, stressing the need for collecting local data.
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http://dx.doi.org/10.1002/cad.20161DOI Listing
June 2016

The Protective Role of Friendship Quality on the Wellbeing of Adolescents Victimized by Peers.

J Youth Adolesc 2016 09 26;45(9):1877-88. Epub 2016 May 26.

Escuela de Psicologia, Pontificia Universidad Católica de Chile, Av. Vicuña Mackenna 4860, Macul, 7820436, Santiago, Chile.

Although studies on peer relations acknowledge that having friends constitutes a protective factor against being victimized by peers at school, it is not enough for this factor to operate. The quality of these friendships does play a role too. The present study explored the moderating role of friendship-quality dimensions (closeness, support, disclosure, and affection) on peer victimization and wellbeing. 614 young adolescents (4th to 6th graders, 50.1 % girls) were assessed three times over 1 year. Analyses were conducted to determine moderation effects, differentiated by gender. Results showed that only disclosure and support interact with victimization and affect wellbeing, especially for girls. Implications for studying peer relations, acknowledging gender differences, are discussed.
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http://dx.doi.org/10.1007/s10964-016-0504-4DOI Listing
September 2016

Hippo pathway regulates neural stem cell quiescence.

Cell Cycle 2016 06 8;15(12):1525-6. Epub 2016 Apr 8.

a Institute of Genetics, University of Mainz , Mainz , Germany.

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http://dx.doi.org/10.1080/15384101.2016.1171653DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4934065PMC
June 2016

Cell-Autonomous and Non-cell-autonomous Function of Hox Genes Specify Segmental Neuroblast Identity in the Gnathal Region of the Embryonic CNS in Drosophila.

PLoS Genet 2016 Mar 25;12(3):e1005961. Epub 2016 Mar 25.

Institute of Genetics, University of Mainz, Mainz, Germany.

During central nervous system (CNS) development neural stem cells (Neuroblasts, NBs) have to acquire an identity appropriate to their location. In thoracic and abdominal segments of Drosophila, the expression pattern of Bithorax-Complex Hox genes is known to specify the segmental identity of NBs prior to their delamination from the neuroectoderm. Compared to the thoracic, ground state segmental units in the head region are derived to different degrees, and the precise mechanism of segmental specification of NBs in this region is still unclear. We identified and characterized a set of serially homologous NB-lineages in the gnathal segments and used one of them (NB6-4 lineage) as a model to investigate the mechanism conferring segment-specific identities to gnathal NBs. We show that NB6-4 is primarily determined by the cell-autonomous function of the Hox gene Deformed (Dfd). Interestingly, however, it also requires a non-cell-autonomous function of labial and Antennapedia that are expressed in adjacent anterior or posterior compartments. We identify the secreted molecule Amalgam (Ama) as a downstream target of the Antennapedia-Complex Hox genes labial, Dfd, Sex combs reduced and Antennapedia. In conjunction with its receptor Neurotactin (Nrt) and the effector kinase Abelson tyrosine kinase (Abl), Ama is necessary in parallel to the cell-autonomous Dfd pathway for the correct specification of the maxillary identity of NB6-4. Both pathways repress CyclinE (CycE) and loss of function of either of these pathways leads to a partial transformation (40%), whereas simultaneous mutation of both pathways leads to a complete transformation (100%) of NB6-4 segmental identity. Finally, we provide genetic evidences, that the Ama-Nrt-Abl-pathway regulates CycE expression by altering the function of the Hippo effector Yorkie in embryonic NBs. The disclosure of a non-cell-autonomous influence of Hox genes on neural stem cells provides new insight into the process of segmental patterning in the developing CNS.
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http://dx.doi.org/10.1371/journal.pgen.1005961DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4807829PMC
March 2016

The Hippo signalling pathway maintains quiescence in Drosophila neural stem cells.

Nat Commun 2016 Jan 29;7:10510. Epub 2016 Jan 29.

Institute of Genetics, Johannes Gutenberg University, 55099 Mainz, Germany.

Stem cells control their mitotic activity to decide whether to proliferate or to stay in quiescence. Drosophila neural stem cells (NSCs) are quiescent at early larval stages, when they are reactivated in response to metabolic changes. Here we report that cell-contact inhibition of growth through the canonical Hippo signalling pathway maintains NSC quiescence. Loss of the core kinases hippo or warts leads to premature nuclear localization of the transcriptional co-activator Yorkie and initiation of growth and proliferation in NSCs. Yorkie is necessary and sufficient for NSC reactivation, growth and proliferation. The Hippo pathway activity is modulated via inter-cellular transmembrane proteins Crumbs and Echinoid that are both expressed in a nutrient-dependent way in niche glial cells and NSCs. Loss of crumbs or echinoid in the niche only is sufficient to reactivate NSCs. Finally, we provide evidence that the Hippo pathway activity discriminates quiescent from non-quiescent NSCs in the Drosophila nervous system.
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http://dx.doi.org/10.1038/ncomms10510DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4740179PMC
January 2016

Why do early adolescents bully? Exploring the influence of prestige norms on social and psychological motives to bully.

J Adolesc 2016 Jan 14;46:45-56. Epub 2015 Nov 14.

C.R.I.d.e.e., Università Cattolica del Sacro Cuore, Gemelli 1, 20123 Milano, Italy. Electronic address:

The present study examines psychological (e.g., Machiavellianism) and social (i.e., perceived popularity) motives for bullying, exploring the effects that classroom prestige norms for physical and relational aggression may have on these associations. A longitudinal multilevel study design was adopted, which included 978 5th to 7th graders from four Chilean schools. Participants were assessed three times over one year on self reports on bullying and Machiavellianism, and peer reports on popularity. Classroom prestige norms were calculated as the within classroom association between peer perceived coolness and aggression. Both Machiavellianism and perceived popularity were associated with bullying. However, hierarchical linear modeling analyses showed that Machiavellianism, but not perceived popularity, predicted bullying after controlling for baseline scores. Classroom prestige norms for relational aggression increased the association between Machiavellianism and bullying. Separate models were tested for boys and girls, showing no differences. Results are discussed in light of conceptual and methodological considerations.
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http://dx.doi.org/10.1016/j.adolescence.2015.10.020DOI Listing
January 2016

Different topologies in three manganese-μ-azido 1D compounds: magnetic behavior and DFT-quantum Monte Carlo calculations.

Dalton Trans 2015 Nov 9;44(42):18632-42. Epub 2015 Oct 9.

Institut für Physikalische and Theoretische Chemie, Technische Universität Graz, Stremayrgasse 9, A-8010 Graz, Austria.

The syntheses and structural characterization of three new monodimensional azido-bridged manganese(ii) complexes with empirical formulae [Mn(N3)2(aminopyz)2]n (1), [Mn(N3)2(4-azpy)2]n (2) and [Mn(N3)2(4-Bzpy)2]n (3) (pyz = pyrazine (1,4-diazine)), 4-azpy = 4-azidopyridine and 4-Bzpy = 4-benzoylpyridine) are reported. 1 is a monodimensional compound with double EO azido bridges, 2 is an alternating monodimensional compound with double end-on and double end-to-end azido bridges in the sequence di-EO-di-EE and 3 is a monodimensional compound with double end-on and double end-to-end azido bridges in the sequence di-EO-di-EO-diEO-di-EO-di-EE. The magnetic properties of 1-3 are reported. Periodic DFT calculations were performed to estimate the J values and quantum Monte Carlo simulations were carried out using the calculated J values to check their accuracy in comparison with the experimental magnetic measurements. From this theoretical analysis, two appealing features of the di-EO Mn(ii) compounds can be extracted: first, the exchange coupling becomes more ferromagnetic when the Mn-N-Mn bridging angle becomes larger and the spin density of the bridging nitrogen atoms has an opposite sign to that of the Mn(II) centers.
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http://dx.doi.org/10.1039/c5dt03034jDOI Listing
November 2015

[Telestroke in eastern Switzerland].

Ther Umsch 2015 Sep;72(9):557-60

1 Klinik für Neurologie, Kantonsspital St.Gallen.

The establishment of stroke networks is an approach to forward guideline driven stroke care to hospitals without full-time neurological service. Tele- stroke networks are evidence based for remote neurological support of acute stroke patients, administration of thrombolysis safely as well as increasing thrombolysis rates. Since 2011 the district hospital in Grabs was linked to the stroke center at the cantonal hospital St. Gallen which provided teleconsultations with full-scale audiovisual communication and access to brain images 24 hours per day 7 days per week. Regarding quality and safety issues the experiences were promising including the selection of patients for appropriate treatment with allocation to systemic thrombolysis or en dovascular reperfusion therapy. As perspective it may definitely contribute to better supply of rural areas with acute stroke therapy but also other specializations and neurological indications may benefit from telemedical support
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http://dx.doi.org/10.1024/0040-5930/a000718DOI Listing
September 2015

Aggressive and Prosocial? Examining Latent Profiles of Behavior, Social Status, Machiavellianism, and Empathy.

J Youth Adolesc 2015 Dec 19;44(12):2230-44. Epub 2015 May 19.

The University of Texas at Austin, Austin, TX, USA.

The present study tests whether aggression and prosocial behavior can coexist as part of a socially functional and adaptive profile among early adolescents. Using a person-centered approach, the study examined early adolescents' likelihood of being classified into profiles involving aggressive and prosocial behavior, social status (popular, liked, cool), machiavellianism, and both affective and cognitive components of empathy (empathic concern and perspective taking, respectively). Participants were 1170 early adolescents (10-12 years of age; 52% male) from four schools in metropolitan Santiago, Chile. Through latent profile analysis, three profiles emerged (normative-low aggressive, high prosocial-low aggressive, and high aggressive-high popular status). Both empathic concern and perspective taking were higher in the high prosocial-low aggressive profile, whereas the high aggressive-high popular status profile had the lowest scores on both empathy components as well as machiavellianism. No profile emerged where aggressive and prosocial behaviors were found to co-exist, or to be significantly above the mean. The results underscore that aggressive behavior is highly contextual and likely culturally specific, and that the study of behavioral profiles should consider social status as well as socio-emotional adjustment indicators. These complex associations should be taken into consideration when planning prevention and intervention efforts to reduce aggression or school bullying and to promote positive peer relationships.
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http://dx.doi.org/10.1007/s10964-015-0298-9DOI Listing
December 2015

Composition of a neuromere and its segmental diversification under the control of Hox genes in the embryonic CNS of Drosophila.

J Neurogenet 2014 Sep-Dec;28(3-4):171-80. Epub 2014 Jul 8.

Institute of Genetics, University of Mainz , Mainz , Germany.

Studies performed at the level of single, identified cells in the fruitfly Drosophila have decisively contributed to our understanding of the mechanisms underlying the development and function of the nervous system. This review highlights some of the work based on single-cell analyses in the embryonic/larval CNS that sheds light on the principles underlying formation and organization of an entire segmental unit and its divergence along the anterior/posterior body axis.
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http://dx.doi.org/10.3109/01677063.2013.868459DOI Listing
June 2015

Inhibition of voltage-gated Na⁺ channels by the synthetic cannabinoid ajulemic acid.

Anesth Analg 2014 Jun;118(6):1238-45

From the *Department of Anesthesia and Critical Care Medicine, and † Department of Neurology and Clinical Neurophysiology, Medizinische Hochschule Hannover, Hannover, Germany.

Background: The synthetic cannabinoid ajulemic acid has been demonstrated to alleviate pain in patients suffering from chronic neuropathic pain. Cannabinoids interact with several molecules within the pain circuit, including a potent inhibition of voltage-gated sodium channels. In this study, we closely characterized this property on neuronal and nonneuronal sodium channels.

Methods: The inhibition of sodium inward currents by ajulemic acid was studied in vitro. Human embryonic kidney 293t cells were used as the expression system for Nav1.2, 1.3, 1.4, 1.5, 1.5N406K, 1.5F1760A, and 1.7; Nav1.8 was transiently expressed in ND7/23 cells. Nav1.2, Nav1.3, and Nav 1.8 were from rats, and Nav1.4, Nav1.5, and Nav1.7 were of human origin. Sodium currents were analyzed by means of the whole cell patch-clamp technique. The investigated concentrations of ajulemic acid were 0.1, 0.3, 1, 3, 10, and 30 μmol/L.

Results: Ajulemic acid reversibly and concentration-dependently inhibited all voltage-gated sodium channel (Nav) isoforms investigated in this study, including Nav1.2, 1.3, 1.4, 1.5, 1.7, and 1.8. Tonic block of resting channels yielded half-maximal inhibitory concentration values between 2 and 9 μmol/L and was strongly enhanced on inactivated channels, suggesting state-dependent inhibition by ajulemic acid. Tonic block did not differ significantly when comparing Nav1.2 and Nav1.3, Nav1.4 and Nav1.5, and Nav1.7 and Nav1.8. Statistical analysis of other combinations of subunits (e.g., Nav1.2 and Nav1.4) by analysis of variance yielded a significant difference in block. Although we did not observe any relevant use-dependent block, ajulemic acid induced a strong hyperpolarizing shift of the voltage dependency of fast inactivation and modest shift of slow inactivation. The local anesthetic-insensitive Nav1.5 constructs N406K and F1760A displayed a preserved sensitivity to block by ajulemic acid. Finally, we found that low concentrations of ajulemic acid efficiently inhibited Navβ4 peptide-mediated resurgent currents in Nav1.5.

Conclusions: Our data suggest that block of sodium channels can be a relevant mechanism by which ajulemic acid alleviates neuropathic pain. The potent inhibition of resurgent currents and the preserved block on local anesthetic-insensitive channels indicates that ajulemic acid interacts with a conserved but yet unknown site of sodium channels.
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http://dx.doi.org/10.1213/ANE.0000000000000188DOI Listing
June 2014

Lidocaine reduces neutrophil recruitment by abolishing chemokine-induced arrest and transendothelial migration in septic patients.

J Immunol 2014 Jan 29;192(1):367-76. Epub 2013 Nov 29.

Department of Anesthesiology, Intensive Care and Pain Medicine, University Hospital Münster, 48149 Münster, Germany.

The inappropriate activation, positioning, and recruitment of leukocytes are implicated in the pathogenesis of multiple organ failure in sepsis. Although the local anesthetic lidocaine modulates inflammatory processes, the effects of lidocaine in sepsis are still unknown. This double-blinded, prospective, randomized clinical trial was conducted to investigate the effect of lidocaine on leukocyte recruitment in septic patients. Fourteen septic patients were randomized to receive either a placebo (n = 7) or a lidocaine (n = 7) bolus (1.5 mg/kg), followed by continuous infusion (100 mg/h for patients >70 kg or 70 mg/h for patients <70 kg) over a period of 48 h. Selectin-mediated slow rolling, chemokine-induced arrest, and transmigration were investigated by using flow chamber and transmigration assays. Lidocaine treatment abrogated chemokine-induced neutrophil arrest and significantly impaired neutrophil transmigration through endothelial cells by inhibition of the protein kinase C-θ while not affecting the selectin-mediated slow leukocyte rolling. The observed results were not attributable to changes in surface expression of adhesion molecules or selectin-mediated capturing capacity, indicating a direct effect of lidocaine on signal transduction in neutrophils. These data suggest that lidocaine selectively inhibits chemokine-induced arrest and transmigration of neutrophils by inhibition of protein kinase C-θ while not affecting selectin-mediated slow rolling. These findings may implicate a possible therapeutic role for lidocaine in decreasing the inappropriate activation, positioning, and recruitment of leukocytes during sepsis.
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http://dx.doi.org/10.4049/jimmunol.1301363DOI Listing
January 2014

Long-term live cell imaging and automated 4D analysis of drosophila neuroblast lineages.

PLoS One 2013 8;8(11):e79588. Epub 2013 Nov 8.

Institute of Molecular Biotechnology of the Austrian Academy of Sciences, Vienna, Austria.

The developing Drosophila brain is a well-studied model system for neurogenesis and stem cell biology. In the Drosophila central brain, around 200 neural stem cells called neuroblasts undergo repeated rounds of asymmetric cell division. These divisions typically generate a larger self-renewing neuroblast and a smaller ganglion mother cell that undergoes one terminal division to create two differentiating neurons. Although single mitotic divisions of neuroblasts can easily be imaged in real time, the lack of long term imaging procedures has limited the use of neuroblast live imaging for lineage analysis. Here we describe a method that allows live imaging of cultured Drosophila neuroblasts over multiple cell cycles for up to 24 hours. We describe a 4D image analysis protocol that can be used to extract cell cycle times and growth rates from the resulting movies in an automated manner. We use it to perform lineage analysis in type II neuroblasts where clonal analysis has indicated the presence of a transit-amplifying population that potentiates the number of neurons. Indeed, our experiments verify type II lineages and provide quantitative parameters for all cell types in those lineages. As defects in type II neuroblast lineages can result in brain tumor formation, our lineage analysis method will allow more detailed and quantitative analysis of tumorigenesis and asymmetric cell division in the Drosophila brain.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0079588PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3832664PMC
July 2014