FAK-mediated mechanotransduction in skeletal regeneration

The majority of cells are equipped to detect and decipher physical stimuli, and then react to these stimuli in a cell type-specific manner. Ultimately, these cellular behaviors are synchronized to produce a tissue response, but how this is achieved remains enigmatic. Here, we investigated the genetic basis for mechanotransduction using the bone marrow as a model system. We found that physical stimuli produced a pattern of principal strain that precisely corresponded to the site-specific expression of sox9 and runx2, two transcription factors required for the commitment of stem cells to a skeletogenic lineage, and the arrangement and orientation of newly deposited type I collagen fibrils. To gain insights into the genetic basis for skeletal mechanotransduction we conditionally inactivated focal adhesion kinase (FAK), an intracellular component of the integrin signaling pathway. By doing so we abolished the mechanically induced osteogenic response and thus identified a critical genetic component of the molecular machinery required for mechanotransduction. Our data provide a new framework in which to consider how physical forces and molecular signals are synchronized during the program of skeletal regeneration

Liposomal Packaging Generates Wnt Protein with In Vivo Biological Activity

Wnt signals exercise strong cell-biological and regenerative effects of considerable therapeutic value. There are, however, no specific Wnt agonists and no method for in vivo delivery of purified Wnt proteins. Wnts contain lipid adducts that are required for activity and we exploited this lipophilicity by packaging purified Wnt3a protein into lipid vesicles. Rather than being encapsulated, Wnts are tethered to the liposomal surface, where they enhance and sustain Wnt signaling in vitro. Molecules that effectively antagonize soluble Wnt3a protein but are ineffective against the Wnt3a signal presented by a cell in a paracrine or autocrine manner are also unable to block liposomal Wnt3a activity, suggesting that liposomal packaging mimics the biological state of active Wnts. When delivered subcutaneously, Wnt3a liposomes induce hair follicle neogenesis, demonstrating their robust biological activity in a regenerative context

Estrogen/Estrogen Receptor Alpha Signaling in Mouse Posterofrontal Cranial Suture Fusion

BACKGROUND: While premature suture fusion, or craniosynostosis, is a relatively common condition, the cause is often unknown. Estrogens are associated with growth plate fusion of endochondral bones. In the following study, we explore the previously unknown significance of estrogen/estrogen receptor signaling in cranial suture biology. METHODOLOGY/PRINCIPAL FINDINGS: Firstly, estrogen receptor (ER) expression was examined in physiologically fusing (posterofrontal) and patent (sagittal) mouse cranial sutures by quantitative RT-PCR. Next, the cranial suture phenotype of ER alpha and ER beta knockout (alphaERKO, betaERKO) mice was studied. Subsequently, mouse suture-derived mesenchymal cells (SMCs) were isolated; the effects of 17-beta estradiol or the estrogen antagonist Fulvestrant on gene expression, osteogenic and chondrogenic differentiation were examined in vitro. Finally, in vivo experiments were performed in which Fulvestrant was administered subcutaneously to the mouse calvaria. Results showed that increased ERalpha but not ERbeta transcript abundance temporally coincided with posterofrontal suture fusion. The alphaERKO but not betaERKO mouse exhibited delayed posterofrontal suture fusion. In vitro, addition of 17-beta estradiol enhanced both osteogenic and chondrogenic differentiation in suture-derived mesenchymal cells, effects reversible by Fulvestrant. Finally, in vivo application of Fulvestrant significantly diminished calvarial osteogenesis, inhibiting suture fusion. CONCLUSIONS/SIGNIFICANCE: Estrogen signaling through ERalpha but not ERbeta is associated with and necessary for normal mouse posterofrontal suture fusion. In vitro studies suggest that estrogens may play a role in osteoblast and/or chondrocyte differentiation within the cranial suture complex

Epidemiologische Erfassung der Wirbelfrakturen im Bergmannsheil Bochum zwischen 1996 und 2000

Eine epidemiologische Erfassung von Patienten mit Wirbelfrakturen lässt tiefe Einblicke in die Verknüpfung einzelner Faktoren, wie Alter, Unfallursache, neurologisches Defizit, Therapieoptionen erwarten. Daher wurden Daten von 562 Patienten des Bergmannsheil Bochum im Zeitraum von 1996 bis 2000 statistisch ausgewertet. Resultierend zeigte sich eine geschlechtstypische Altersverteilung, die durch unterschiedliche Risikofaktoren bedingt ist. Anhand der Unfallursache lassen sich bestimmte Faktoren, wie Frakturlokalisation, Begleitverletzung, Frakturtyp vorhersagen. So konnte ein signifikanter Zusammenhang zwischen Hochransanztraumen und Mehretagenfrakturen gestellt werden, welche mit einer Wahrscheinlichkeit von 96% mit einer Begleitverletzung einhergehen. Zusammenfassend kann behauptet werden, dass die von Magerl vorgeschlagene Klassifikation eine sinnvollen Beitrag zur Abschätzung des Risikos einer Begleitverletzung, eines neurologischen Defizits, sowie der Operationsindikation stellt

Reducing antipsychotic drugs in stable patients with chronic schizophrenia or schizoaffective disorder: a randomized controlled pilot trial

As the course of schizophrenic disorders is often chronic, treatment guidelines recommend continuous maintenance treatment to prevent relapses, but antipsychotic drugs can cause many side effects. It, therefore, seems reasonable to try to reduce doses in stable phases of the illness or even try to stop medication. We conducted a 26 weeks, randomized, rater blind, feasibility study to examine individualized antipsychotic dose reduction versus continuous maintenance treatment (Register Number: NCT02307396). We included chronic, adult patients with schizophrenia or schizoaffective disorder, who were treated with any antipsychotic drug except clozapine, who had not been hospitalized in the last 3 years and who were in symptomatic remission at baseline. The primary outcome was relapse of positive symptoms. Symptom severity, social functioning and side effects were also examined as secondary outcomes. 20 patients were randomized. Relapse rates in the two groups were not significantly different. No patient had to be hospitalized. One patient in the control group dropped out. The mean reduction of antipsychotic dose in the individualized dose-reduction group was 42%, however only one patient discontinued drug completely. There were no significant differences in efficacy or safety outcomes. This randomized trial provides evidence, that reduction of antipsychotic medication in chronic stable schizophrenic patients may be feasible. The results need to be confirmed in a larger trial with a longer follow-up period

Evaluation of Differences in Individual Treatment Response in Schizophrenia Spectrum Disorders: A Meta-analysis

IMPORTANCE: An assumption among clinicians and researchers is that patients with schizophrenia vary considerably in their response to antipsychotic drugs in randomized clinical trials (RCTs). OBJECTIVE: To evaluate the overall variation in individual treatment response from random variation by comparing the variability between treatment and control groups. DATA SOURCES: Cochrane Schizophrenia, MEDLINE/PubMed, Embase, PsycINFO, Cochrane CENTRAL, BIOSIS Previews, ClinicalTrials.gov, and World Health Organization International Clinical Trials Registry Platform from January 1, 1955, to December 31, 2016. STUDY SELECTION: Double-blind, placebo-controlled, RCTs of adults with a diagnosis of schizophrenia spectrum disorders and prescription for licensed antipsychotic drugs. DATA EXTRACTION AND SYNTHESIS: Means and SDs of the Positive and Negative Syndrome Scale pretreatment and posttreatment outcome difference scores were extracted. Data quality and validity were ensured by following the PRISMA guidelines. MAIN OUTCOMES AND MEASURES: The outcome measure was the overall variability ratio of treatment to control in a meta-analysis across RCTs. Individual variability ratios were weighted by the inverse-variance method and entered into a random-effects model. A personal element of response was hypothesized to be reflected by a substantial overall increase in variability in the treatment group compared with the control group. RESULTS: An RCT was simulated, comprising 30 patients with schizophrenia randomized to either the treatment or the control group. The different components of variation in RCTs were illustrated with simulated data. In addition, we assessed the variability ratio in 52 RCTs involving 15 360 patients with a schizophrenia or schizoaffective diagnosis. The variability was slightly lower in the treatment compared with the control group (variability ratio = 0.97; 95% CI, 0.95-0.99; P = .01). CONCLUSIONS AND RELEVANCE: In this study, no evidence was found in RCTs that antipsychotic drugs increased the outcome variance, suggesting no personal element of response to treatment but instead indicating that the variance was slightly lower in the treatment group than in the control group; although the study cannot rule out that subsets of patients respond differently to treatment, it suggests that the average treatment effect is a reasonable assumption for the individual patient

The demographics and outcomes in patients with bilateral distal radius fractures.

Although distal radius fractures are quite common, bilateral distal radius fractures seldomly occur. Due to this, treatment is primarily based on surgeon experience with unilateral fractures, however bi- lateral fractures add a level of complexity : loss of functional independence. The purpose of this study was to examine a cohort of patients with bilateral distal radius fractures to identify differences in demographics, mechanism of injury, and outcomes to further our understanding of these rare injuries. 23 patients were identified retrospectively over a 5-year period that met inclusion criteria. The medical records were reviewed with multiple demographic and clinical parameters recorded and analyzed. Males were more likely to sustain high-energy mechanisms (80% vs. 53%). Patients(90% vs. 46%) and were more likely to be treated operatively (80% vs. 62%). The most commonly associated injury was a head injury (30%). All patients treated non-operatively reported minimal/no pain upon final follow-up where 57% of patients treated operatively noted regular pain. 75% of patients with medical comorbidities had minimal/no pain upon final follow- up. Conclusions : Patients with bilateral fractures were more likely to be younger males who suffered from higher energy mechanisms. Age was a critical factor in determining treatment strategy. Rates of associated head injuries were elevated, which is an important factor for the clinician to keep in mind when treating this population. As we further our understanding of this unique population, we can improve our treatment approaches and subsequently attain better outcomes

Killer incentives: rivalry, performance and risk-taking among German fighter pilots, 1939-45

Using newly collected data on death rates and aerial victories of more than 5,000 German fighter pilots during World War II, we examine the effects of public recognition on performance and risk-taking. When a particular pilot is honoured publicly, both the victory rate and the death rate of his former peers increase. Fellow pilots react more if they come from the same region of Germany, or if they worked closely with him. Our results suggest that personal rivalry can be a prime motivating force, and that non-financial rewards can lead to a crowd-in of both effort and risk-taking via social connections