Perfluorophenyl azide functionalization of electrospun poly(para‐dioxanone)

Strategies to surface‐functionalize scaffolds by covalent binding of biologically active compounds are of fundamental interest to control the interactions between scaffolds and biomolecules or cells. Poly(para‐dioxanone) (PPDO) is a clinically established polymer that has shown potential as temporary implant, eg, for the reconstruction of the inferior vena cava, as a nonwoven fiber mesh. However, PPDO lacks suitable chemical groups for covalent functionalization. Furthermore, PPDO is highly sensitive to hydrolysis, reflected by short in vivo half‐life times and degradation during storage. Establishing a method for covalent functionalization without degradation of this hydrolyzable polymer is therefore important to enable the surface tailoring for tissue engineering applications. It was hypothesized that treatment of PPDO with an N‐hydroxysuccinimide ester group bearing perfluorophenyl azide (PFPA) under UV irradiation would allow efficient surface functionalization of the scaffold. X‐ray photoelectron spectroscopy and attenuated total reflectance Fourier‐transformed infrared spectroscopy investigation revealed the successful binding, while a gel permeation chromatography study showed that degradation did not occur under these conditions. Coupling of a rhodamine dye to the N‐hydroxysuccinimide esters on the surface of a PFPA‐functionalized scaffold via its amine linker showed a homogenous staining of the PPDO in laser confocal microscopy. The PFPA method is therefore applicable even to the surface functionalization of hydrolytically labile polymers, and it was demonstrated that PFPA chemistry may serve as a versatile tool for the (bio‐)functionalization of PPDO scaffolds

RGD constructs with physical anchor groups as polymer co-electrospinnable cell adhesives

The tissue integration of synthetic polymers can be promoted by displaying RGD peptides at the biointerface with the objective of enhancing colonization of the material by endogenous cells. A firm but flexible attachment of the peptide to the polymer matrix, still allowing interaction with receptors, is therefore of interest. Here, the covalent coupling of flexible physical anchor groups, allowing for temporary immobilization on polymeric surfaces via hydrophobic or dipole–dipole interactions, to a RGD peptide was investigated. For this purpose, a stearate or an oligo(ethylene glycol) (OEG) was attached to GRGDS in 51–69% yield. The obtained RGD linker constructs were characterized by NMR, IR and MALDI-ToF mass spectrometry, revealing that the commercially available OEG and stearate linkers are in fact mixtures of similar compounds. The RGD linker constructs were co-electrospun with poly(p-dioxanone) (PPDO). After electrospinning, nitrogen could be detected on the surface of the PPDO fibers by X-ray photoelectron spectroscopy. The nitrogen content exceeded the calculated value for the homogeneous material mixture suggesting a pronounced presentation of the peptide on the fiber surface. Increasing amounts of RGD linker constructs in the electrospinning solution did not lead to a detection of an increased amount of peptide on the scaffold surface, suggesting inhomogeneous distribution of the peptide on the PPDO fiber surface. Human adipose-derived stem cells cultured on the patches showed similar viability as when cultured on PPDO containing pristine RGD. The fully characterized RGD linker constructs could serve as valuable tools for the further development of tissue-integrating polymeric scaffolds

Sex-dependent diversity in ventral tegmental dopaminergic neurons and developmental programing: a molecular, cellular and behavioral analysis

The knowledge that diverse populations of dopaminergic neurons within the ventral tegmental area (VTA) can be distinguished in terms of their molecular, electrophysiological and functional properties, as well as their differential projections to cortical and subcortical regions has significance for key brain functions, such as the regulation of motivation, working memory and sensorimotor control. Almost without exception, this understanding has evolved from landmark studies performed in the male sex. However, converging evidence from both clinical and pre-clinical studies illustrates that the structure and functioning of the VTA dopaminergic systems are intrinsically different in males and females. This may be driven by sex differences in the hormonal environment during adulthood ('activational' effects) and development (perinatal and/or pubertal 'organizational' effects), as well as genetic factors, especially the SRY gene on the Y chromosome in males, which is expressed in a sub-population of adult midbrain dopaminergic neurons. Stress and stress hormones, especially glucocorticoids, are important factors which interact with the VTA dopaminergic systems in order to achieve behavioral adaptation and enable the individual to cope with environmental change. Here, also, there is male/female diversity not only during adulthood, but also in early life when neurobiological programing by stress or glucocorticoid exposure differentially impacts dopaminergic developmental trajectories in male and female brains. This may have enduring consequences for individual resilience or susceptibility to pathophysiological change induced by stressors in later life, with potential translational significance for sex bias commonly found in disorders involving dysfunction of the mesocorticolimbic dopaminergic systems. These findings highlight the urgent need for a better understanding of the sexual dimorphism in the VTA if we are to improve strategies for the prevention and treatment of debilitating conditions which differentially affect men and women in their prevalence and nature, including schizophrenia, attention/deficit hyperactivity disorder, autism spectrum disorders, anxiety, depression and addiction

Poundbury Camp in context – a new perspective on the lives of children from urban and rural Roman England

Objectives The current understanding of child morbidity in Roman England is dominated by studies of single sites/regions. Much of the data are derived from third to fifth century AD Poundbury Camp, Dorchester, Dorset, considered an unusual site due to high levels of non-adult morbidity. There is little understanding of children in rural areas, and whether Poundbury Camp was representative of Romano-British childhood. Materials and methods The study provides the first large scale analysis of child health in urban and rural Roman England, adding to the previously published intra-site analysis of non-adult paleopathology at Poundbury Camp. Age-at-death and pathology prevalence rates were reassessed for 953 non-adults (0–17 years) from five major urban, six minor urban, and four rural sites (first to fifth century AD). The data were compared to the results from 364 non-adults from Poundbury Camp. Results Rural sites demonstrated higher levels of infant burials, and greater prevalence of cribra orbitalia in the 1.1–2.5 year (TPR 64.3%), and 6.6–10.5 year cohorts (TPR 66.7%). Endocranial lesions were more frequent in the minor urban sample (TPR 15.9%). Three new cases of tuberculosis were identified in urban contexts. Vitamin D deficiency was most prevalent at Poundbury Camp (CPR 18.8%), vitamin C deficiency was identified more frequently in rural settlements (CPR 5.9%). Discussion The Poundbury Camp data on morbidity and mortality are not representative of patterns in Roman England and other major urban sites. Rural children suffered from a distinct set of pathologies described as diseases of deprivation, prompting reconsideration of how Romano-British land management affected those at the bottom of the social hierarchy

experimental investigations on formalin-fixed human mandibles

Problemstellung: Die vorliegende experimentelle Untersuchung diente der Analyse der Genauigkeit eines modernen dentalen Volumentomographen (KaVo 3D eXam, KaVo Dental GmbH, Biberach/Riß, Deutschland) bei der Darstellung vestibulärer Knochenläsionen in fünf unterschiedlichen Auflösungen. Dabei sollten vestibuläre Mindestknochenstärken für die Diagnostik beschrieben und der Effekt der gewählten Bildauflösung auf die Visualisierung der Strukturen geklärt werden. Material und Methoden: Die in vitro Untersuchung erfolgte an elf Formalin-fixierten, vollständig präparierten menschlichen Unterkieferhälften. An jedem Fragment wurden durch standardisierte Präparation einzelne Knochenläsionen (Fenestrationen, Dehiszenzen, horizontale parallele Sägeschnitte) vestibulär an den Zahnwurzeln bis zu einer Gesamtzahl von 62 Defektregionen angelegt. Die anschließende radiologische Untersuchung wurde in fünf unterschiedlichen Bildauflösungen (Voxelgrößen mit 0,125, 0,2 mm, 0,25 mm, 0,3 mm und 0,4 mm Kantenlänge) bei einer Stromstärke von 5 mA und einer Betriebsspannung von 120 kV vorgenommen. Zur Auswertung wurde die 3D Imaging- Software Invivo 4 (Anatomage Inc., San Jose, Californien) verwendet. Es erfolgte für jede Aufnahme eine Vermessung der drei bestimmenden Defektparameter Höhe, Breite und Tiefe im Arch-Section-Mode, sowie eine zusätzliche Analyse der Defekthöhen im Volume-Render-Mode des Programmes. Für die Sägeschnitte erfolgte eine Ermittlung ihrer Streckenlängen in der Vertikalansicht. Zusätzlich wurde eine mikroskopische Untersuchung mithilfe eines Stereoauflichtmikroskopes (Zeiss Stemi SV11; Carl Zeiss, Göttingen, Deutschland) und der Software Axiovision Rel. 4.8 (Carl Zeiss, Göttingen, Geutschland) zur Ermittlung der entsprechenden Referenzwerte vorgenommen. Der statistischen Analyse zum Vergleich der radiologischen und mikroskopischen Messwerte dienten das Bland-Altman-Verfahren und der gepaarte t- Test. Zur Überprüfung der Genauigkeit und Reproduzierbarkeit der angewandten Methoden wurden im Rahmen der Fehlerberechnung der Methodenfehler nach Dahlberg und der Reliabilitätskoeffizienten nach Houston ermittelt. Ergebnisse: Die DVT- Aufnahmen erlaubten eine Vermessung der Defekte in allen drei Raumebenen. Beim Vergleich der röntgenologisch erhobenen Werte mit der Referenz wurde eine Abhängigkeit der Darstellung von der verwendeten Bildauflösung und von der Knochenstärke der zu untersuchenden Struktur nachgewiesen. Mit Voxelgrößen von 0,25 mm Kantenlänge und kleiner konnte eine präzise Darstellung bei gleichzeitig geringem Risiko einer falsch-negativen Diagnostik (<10%) für Knochendicken ab 0,4 mm erreicht werden. In beiden Ansichtsmodi bewegten sich die mittleren Abweichungen von der Referenz für sämtliche untersuchte Läsionsarten und -parameter in klinisch vernachlässigbaren Dimensionen (0,02 bis 0,52 mm) mit den besten Resultaten für die Fenestrationen. Eine Betrachtung der Differenzen der korrespondierenden Messwertepaare aus der röntgenologischen und stereomikroskopischen Untersuchung anhand der graphischen Darstellung in den Bland-Altman-Plots wies eine gleichmäßige Verteilung mit geringer Streuung auf. Für Voxelgrößen von 0,3 und 0,4 mm Kantenlänge lagen die mittleren Abweichungen von der Referenz ebenfalls in klinisch akzeptablen Bereichen (0,04 bis 0,67 mm) bei jedoch deutlich höherer Falsch-Negativ-Rate von über 40% für Fenestrationen und Dehiszenzen und 80% für die Untersuchung der Sägeschnitte. Knochendicken unter 0,6 mm wurden nicht erkannt. Zudem fiel die Diagnostik der peridentalen Strukturen im Hinblick auf die Aspekte Bildqualität und Kontrast deutlich schwerer als in höheren Bildauflösungen. Schlussfolgerungen: Grundsätzlich wurde für das Gerät KaVo 3D eXam eine maßstabsgetreue, überlagerungs- und verzerrungsfreie Bildgebung für peridentale vestibuläre Knochenstrukturen nachgewiesen. Eine für den klinischen Alltag ausreichend präzise Darstellung bei gleichzeitig geringem Risiko einer falsch-negativen Diagnostik für Knochendicken ab 0,4 mm wurde mit Voxelgrößen von 0,25 mm Kantenlänge und kleiner erreicht. Bei der Analyse in niedrigeren Bildauflösungen sowie in der 3DRendering- Ansicht war ein signifikanter Anstieg der Falsch-Negativ-Rate zu verzeichnen. Mit Abnahme der Voxelgröße wurde eine Zunahme des Spaltauflösungsvermögens und damit eine bessere Darstellung feiner Knochendicken deutlich, ein Einfluss auf die Messgenauigkeit war hingegen nur in sehr geringem Maße festzustellen.Introduction: The aim of this study was to evaluate the accuracy of a commercially available cone-beam computed tomography (CBCT) dental imaging system (KaVo 3D eXam, KaVo Dental GmbH, Biberach/Riß, Deutschland) for its application in the diagnosis of periodontal bony defects. The main focus was on the investigation of the influence of voxel resolution and bone thickness on the identification of intrabony lesions in CBCT. Materials and methods: Artificial osseous defects (fenestrations, dehiscences and horizontal, parallel cuts) were created in the buccal bone of eleven halves of prepared and formalin-fixed human mandibles by standardized preparation to a number of 62 regions of interest. Linear measurements of CBCT scans in five resolutions (0.125, 0.2, 0.25, 0.3 and 0.4 mm voxel size data sets) were performed with the KaVo 3D eXam CBCT scanner (KaVo Dental GmbH, Biberach/Riß, Germany) and the 3D-Imaging software Invivo 4 (Anatomage Inc., San Jose, California). The results were compared to a microscopical examination of the defects with a stereomicroscope (Zeiss Stemi SV11; Carl Zeiss, Göttingen, Germany) and the software Axiovision Rel. 4.8 (Carl Zeiss, Göttingen, Germany). Regarding the fenestrations and dehiscences the three main parameters (height, width and depth) were analyzed separately on CBCT scans and microscopic images. Additionally the defect heights were considered in a 3D rendering-view of the radiographic scans. For the horizontal cuts their length was measured in vertical sections. Comparing these methods of measurement, the accuracy of the KaVo 3D eXam was determined by using the Bland-Altman Analysis and the paired t-test. To describe the reliability and reproducibility of the applied methods, the repeatability error (Dahlberg) and the coefficient of reliability (Houston) were calculated. Results: The periodontal defects could be measured in CBCT in all three planes. Comparing the linear measurements of the radiographic scans to those of the microscopical examination showed that the image obtained was highly dependent on voxel resolution and thickness of the investigated structures. For a resolution of 0.25 mm voxel data sets and higher precise imaging with low rate of false-negatives (<10% for all types of defects) was achieved. Areas with a bone thickness of less than 0.4 mm could not be detected properly. The CBCT measurements showed mean deviations of 0.02 to 0.52 mm with best results for the fenestrations. Clinically these discrepancies could be classified negligibly small. Considering the differences of the corresponding measured values Bland-Altman Analysis proved low spread and equal distribution. For 0.3 and 0.4 mm voxel data sets the mean deviations (0.04 to 0.67 mm) were equally acceptable for standard clinical implications, but with significantly higher rate of false-negatives (40% of fenestrations and dehiscences, 80% of the horizontal cuts). The smallest bone thickness measured was 0.6 mm. In terms of image quality and contrast the identification of the peridental structures was more difficult in lower resolutions. Conclusions: Kavo 3D eXam in general provided distortion-free imaging of peridental structures in three planes, without overlap and true to scale. For standard clinical implications 0.25, 0.2 and 0.125 mm voxel data sets permitted precise radiological diagnostics with low false-negative-rates for a bone-thickness greater than 0,4 mm. Measurements in lower resolutions and in 3D-rendering-view of the scans resulted in substantial increase of the false-negative-rate. Lower voxel-size led to increasing spatial resolution and more precise imaging of delicate bony structures, while showing only little influence on measurement accuracy