Acute Activation of Oxidative Pentose Phosphate Pathway as First-Line Response to Oxidative Stress in Human Skin Cells.

Integrity of human skin is endangered by exposure to UV irradiation and chemical stressors, which can provoke a toxic production of reactive oxygen species (ROS) and oxidative damage. Since oxidation of proteins and metabolites occurs virtually instantaneously, immediate cellular countermeasures are pivotal to mitigate the negative implications of acute oxidative stress. We investigated the short-term metabolic response in human skin fibroblasts and keratinocytes to H2O2 and UV exposure. In time-resolved metabolomics experiments, we observed that within seconds after stress induction, glucose catabolism is routed to the oxidative pentose phosphate pathway (PPP) and nucleotide synthesis independent of previously postulated blocks in glycolysis (i.e., of GAPDH or PKM2). Through ultra-short (13)C labeling experiments, we provide evidence for multiple cycling of carbon backbones in the oxidative PPP, potentially maximizing NADPH reduction. The identified metabolic rerouting in oxidative and non-oxidative PPP has important physiological roles in stabilization of the redox balance and ROS clearance.

Diagnosing virtual patients: the interplay between knowledge and diagnostic activities.

Clinical reasoning theories agree that knowledge and the diagnostic process are associated with diagnostic success. However, the exact contributions of these components of clinical reasoning to diagnostic success remain unclear. This is particularly the case when operationalizing the diagnostic process with diagnostic activities (i.e., teachable practices that generate knowledge). Therefore, we conducted a study investigating to what extent knowledge and diagnostic activities uniquely explain variance in diagnostic success with virtual patients among medical students. The sample consisted of N = 106 medical students in their third to fifth year of university studies in Germany (6-years curriculum). Participants completed professional knowledge tests before diagnosing virtual patients. Diagnostic success with the virtual patients was assessed with diagnostic accuracy as well as a comprehensive diagnostic score to answer the call for more extensive measurement of clinical reasoning outcomes. The three diagnostic activities hypothesis generation, evidence generation, and evidence evaluation were tracked. Professional knowledge predicted performance in terms of the comprehensive diagnostic score and displayed a small association with diagnostic accuracy. Diagnostic activities predicted comprehensive diagnostic score and diagnostic accuracy. Hierarchical regressions showed that the diagnostic activities made a unique contribution to diagnostic success, even when knowledge was taken into account. Our results support the argument that the diagnostic process is more than an embodiment of knowledge and explains variance in diagnostic success over and above knowledge. We discuss possible mechanisms explaining this finding.

High prevalence of periodontal disease in patients with NASH- possible association of poor dental health with NASH severity.

INTRODUCTION AND OBJECTIVES: Recent translational research indicated a bidirectional relationship between NASH (non-alcoholic steatohepatitis) and periodontitis; however, few clinical cohorts have studied this in detail. Thus we investigated this assumed association in a well-defined cohort. MATERIALS AND METHODS: Data were generated prospectively for 132 patients (32 patients with NASH and 100 unselected, consecutively collected, anonymized controls from a local dental practice): detailed periodontal parameters, i.e., pocket-probing-depths (PPD), bleeding-on-probing (BOP), plaque-index, and utilization of dental care were assessed and correlated with relevant hepatic parameters (liver stiffness via fibroscan, AST, ALT, bilirubin, and MELD-score). Gingiva samples were tested for Porphyromonas gingvalis (P.g.) and Actinobacillus actinomyctemcomitans (A.a.) by PCR. RESULTS: 87.5% of NASH patients and 47% of controls suffered from moderate to severe periodontitis (p=0.01). Liver stiffness was significantly correlated with elevated PPD (p=0.02) and BOP (p=0.03). 34 % of the NASH patients did not make use of regular dental health care. In these patients, AST (p=0.04), MELD score (p<0.01), and liver stiffness (p=0.01) were significantly elevated compared to those who see a dentist regularly. The severity of NASH was not associated with the intraoral detection of P.g. and A.a. CONCLUSIONS: The present study suggests that NASH might be associated with periodontitis, irrespective of the intraoral presence of P.g. and A.a. Moreover, regular dental care utilization might mitigate the course of NASH, and patients should be reminded by their hepatologists of the importance of regular dental visits. Future studies should investigate the role of regular dental care and additional anti-inflammatory treatments of the oral cavity.

SIRT4 coordinates the balance between lipid synthesis and catabolism by repressing malonyl CoA decarboxylase.

Lipid metabolism is tightly controlled by the nutritional state of the organism. Nutrient-rich conditions increase lipogenesis, whereas nutrient deprivation promotes fat oxidation. In this study, we identify the mitochondrial sirtuin, SIRT4, as a regulator of lipid homeostasis. SIRT4 is active in nutrient-replete conditions to repress fatty acid oxidation while promoting lipid anabolism. SIRT4 deacetylates and inhibits malonyl CoA decarboxylase (MCD), an enzyme that produces acetyl CoA from malonyl CoA. Malonyl CoA provides the carbon skeleton for lipogenesis and also inhibits fat oxidation. Mice lacking SIRT4 display elevated MCD activity and decreased malonyl CoA in skeletal muscle and white adipose tissue. Consequently, SIRT4 KO mice display deregulated lipid metabolism, leading to increased exercise tolerance and protection against diet-induced obesity. In sum, this work elucidates SIRT4 as an important regulator of lipid homeostasis, identifies MCD as a SIRT4 target, and deepens our understanding of the malonyl CoA regulatory axis.

Mobile snapshot hyperspectral imaging device for skin evaluation using diffractive optical elements.

OBJECTIVE: A mobile handheld snapshot hyperspectral imaging device was developed and tested for in vivo skin evaluation using a new spectral imaging technology. METHODS: The device is equipped with four different LED light sources (VIS, 810 nm, 850 nm, and 940 nm) for illumination. Based on a diffractive optical element (DOE) combined with a CMOS sensor chip, a snapshot hyperspectral imager is achieved for the application on human skin. The diffractive optical element (DOE) consists of a two-dimensional array of identically repeated diffractive microstructures. One hyperspectral image for all wavelength regions is taken within a few seconds. Complex recalculation of the VIS spectral distribution and image information from the received DOE image requires several minutes, depending on computing performance. A risk assessment on the irradiation sources shows no risk of harm due to the LED radiation. RESULTS: Skin tone color patches experiments reproducibly deliver images and spectra of different skin tones. First in vivo use of the device identified pigmentation changes within the field of view. CONCLUSION: We present a working mobile snapshot hyperspectral imaging tool based on diffractive optical elements. This device or future developments thereof can be used for broad skin evaluation in vivo.

Multi-wavelength, handheld laser speckle imaging for skin evaluation.

OBJECTIVE: A handheld device was developed and qualified for in vivo human skin evaluation using laser speckle imaging technology. METHODS: Each laser speckle device prototype allows the choice of up to three different laser wavelengths in the range of 400 nm to 800 nm in total. Speckle pattern analysis gives various speckle parameters, for example, speckle contrast, speckle size, speckle modulation or fractal dimension. The developed laser speckle device prototypes were evaluated investigating three skin issues. RESULTS: We receive reproducible results from the speckle imaging device. For skin ageing, we found significant changes within three age groups. The effect of a methyl nicotinate treatment was clearly visible and quantifiable using a moorFLPI device as well as our speckle imaging device. In terms of basal cell carcinoma diagnosis, we found significant differences between normal and diseased skin, even though the number of samples was limited. CONCLUSION: As shown with first application examples, it was possible to demonstrate the potential of the method for skin evaluation in vivo.

Assessment of Diagnostic Competences With Standardized Patients Versus Virtual Patients: Experimental Study in the Context of History Taking.

BACKGROUND: Standardized patients (SPs) have been one of the popular assessment methods in clinical teaching for decades, although they are resource intensive. Nowadays, simulated virtual patients (VPs) are increasingly used because they are permanently available and fully scalable to a large audience. However, empirical studies comparing the differential effects of these assessment methods are lacking. Similarly, the relationships between key variables associated with diagnostic competences (ie, diagnostic accuracy and evidence generation) in these assessment methods still require further research. OBJECTIVE: The aim of this study is to compare perceived authenticity, cognitive load, and diagnostic competences in performance-based assessment using SPs and VPs. This study also aims to examine the relationships of perceived authenticity, cognitive load, and quality of evidence generation with diagnostic accuracy. METHODS: We conducted an experimental study with 86 medical students (mean 26.03 years, SD 4.71) focusing on history taking in dyspnea cases. Participants solved three cases with SPs and three cases with VPs in this repeated measures study. After each case, students provided a diagnosis and rated perceived authenticity and cognitive load. The provided diagnosis was scored in terms of diagnostic accuracy; the questions asked by the medical students were rated with respect to their quality of evidence generation. In addition to regular null hypothesis testing, this study used equivalence testing to investigate the absence of meaningful effects. RESULTS: Perceived authenticity (1-tailed t81=11.12; P<.001) was higher for SPs than for VPs. The correlation between diagnostic accuracy and perceived authenticity was very small (r=0.05) and neither equivalent (P=.09) nor statistically significant (P=.32). Cognitive load was equivalent in both assessment methods (t82=2.81; P=.003). Intrinsic cognitive load (1-tailed r=-0.30; P=.003) and extraneous load (1-tailed r=-0.29; P=.003) correlated negatively with the combined score for diagnostic accuracy. The quality of evidence generation was positively related to diagnostic accuracy for VPs (1-tailed r=0.38; P<.001); this finding did not hold for SPs (1-tailed r=0.05; P=.32). Comparing both assessment methods with each other, diagnostic accuracy was higher for SPs than for VPs (2-tailed t85=2.49; P=.01). CONCLUSIONS: The results on perceived authenticity demonstrate that learners experience SPs as more authentic than VPs. As higher amounts of intrinsic and extraneous cognitive loads are detrimental to performance, both types of cognitive load must be monitored and manipulated systematically in the assessment. Diagnostic accuracy was higher for SPs than for VPs, which could potentially negatively affect students' grades with VPs. We identify and discuss possible reasons for this performance difference between both assessment methods.

Learning to diagnose accurately through virtual patients: do reflection phases have an added benefit?

BACKGROUND: Simulation-based learning with virtual patients is a highly effective method that could potentially be further enhanced by including reflection phases. The effectiveness of reflection phases for learning to diagnose has mainly been demonstrated for problem-centered instruction with text-based cases, not for simulation-based learning. To close this research gap, we conducted a study on learning history-taking using virtual patients. In this study, we examined the added benefit of including reflection phases on learning to diagnose accurately, the associations between knowledge and learning, and the diagnostic process. METHODS: A sample of N = 121 medical students completed a three-group experiment with a control group and pre- and posttests. The pretest consisted of a conceptual and strategic knowledge test and virtual patients to be diagnosed. In the learning phase, two intervention groups worked with virtual patients and completed different types of reflection phases, while the control group learned with virtual patients but without reflection phases. The posttest again involved virtual patients. For all virtual patients, diagnostic accuracy was assessed as the primary outcome. Current hypotheses were tracked during reflection phases and in simulation-based learning to measure diagnostic process. RESULTS: Regarding the added benefit of reflection phases, an ANCOVA controlling for pretest performance found no difference in diagnostic accuracy at posttest between the three conditions, F(2, 114) = 0.93, p = .398. Concerning knowledge and learning, both pretest conceptual knowledge and strategic knowledge were not associated with learning to diagnose accurately through reflection phases. Learners' diagnostic process improved during simulation-based learning and the reflection phases. CONCLUSIONS: Reflection phases did not have an added benefit for learning to diagnose accurately in virtual patients. This finding indicates that reflection phases may not be as effective in simulation-based learning as in problem-centered instruction with text-based cases and can be explained with two contextual differences. First, information processing in simulation-based learning uses the verbal channel and the visual channel, while text-based learning only draws on the verbal channel. Second, in simulation-based learning, serial cue cases are used to gather information step-wise, whereas, in text-based learning, whole cases are used that present all data at once.

Learning clinical reasoning: how virtual patient case format and prior knowledge interact.

INTRODUCTION: Clinical reasoning has been fostered with varying case formats including the use of virtual patients. Existing literature points to different conclusions regarding which format is most beneficial for learners with diverse levels of prior knowledge. We designed our study to better understand which case format affects clinical reasoning outcomes and cognitive load, dependent on medical students' prior knowledge. METHODS: Overall, 142 medical students (3 rd to 6 th year) were randomly assigned to either a whole case or serial cue case format. Participants worked on eight virtual patients in their respective case format. Outcomes included diagnostic accuracy, knowledge, and cognitive load. RESULTS: We found no effect of case format on strategic knowledge scores pre- vs post-test (whole case learning gain = 3, 95% CI. -.01 to .01, serial cue learning gain = 3, 95% CI. -.06 to .00 p = .50). In both case formats, students with high baseline knowledge (determined by median split on the pre-test in conceptual knowledge) benefitted from learning with virtual patients (learning gain in strategic knowledge = 5, 95% CI .03 to .09, p = .01) while students with low prior knowledge did not (learning gain = 0, 95%CI -.02 to .02). We found no difference in diagnostic accuracy between experimental conditions (difference = .44, 95% CI -.96 to .08, p = .22), but diagnostic accuracy was higher for students with high prior knowledge compared to those with low prior knowledge (difference = .8, 95% CI 0.31 to 1.35, p < .01). Students with low prior knowledge experienced higher extraneous cognitive load than students with high prior knowledge (multiple measurements, p < .01). CONCLUSIONS: The whole case and serial cue case formats alone did not affect students' knowledge gain or diagnostic accuracy. Students with lower knowledge experienced increased cognitive load and appear to have learned less from their interaction with virtual patients. Cognitive load should be taken into account when attempting to help students learn clinical reasoning with virtual patients, especially for students with lower knowledge.

Assembly and Characterization of a Slingshot DNA Nanostructure for the Analysis of Bivalent and Bispecific Analytes with Biosensors.

The characterization of novel therapeutic antibodies with multivalent or multispecific binding sites requires new measurement modalities for biosensors, to discriminate the engagement of antigens via one, two, or even more binding moieties. The presentation of antigens on a sensor surface in a well-controlled spatial arrangement is a prerequisite for the successful interpretation of binding kinetics measurements of multivalent analytes, but the adjustment of defined distances between immobilized ligands is difficult to achieve in state-of-the-art biosensor systems. Here, we introduce a simple DNA nanostructure resembling a slingshot, which can be configured with two identical or two different antigens (bivalent or bispecific), which are spaced at a defined distance. We characterize the slingshot structure with a chip-based biosensor using electrically switchable DNA nanolevers and demonstrate that bivalent and monovalent antibodies selectively interact with slingshots that have been functionalized with two identical or two different antigens, respectively. The dissociation kinetics are quantified in real-time measurements and we show that the slingshot structure enables a clear differentiation between affinity and avidity effects.

Ex-527 inhibits Sirtuins by exploiting their unique NAD+-dependent deacetylation mechanism.

Sirtuins are protein deacetylases regulating metabolism and stress responses. The seven human Sirtuins (Sirt1-7) are attractive drug targets, but Sirtuin inhibition mechanisms are mostly unidentified. We report the molecular mechanism of Sirtuin inhibition by 6-chloro-2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide (Ex-527). Inhibitor binding to potently inhibited Sirt1 and Thermotoga maritima Sir2 and to moderately inhibited Sirt3 requires NAD(+), alone or together with acetylpeptide. Crystal structures of several Sirtuin inhibitor complexes show that Ex-527 occupies the nicotinamide site and a neighboring pocket and contacts the ribose of NAD(+) or of the coproduct 2'-O-acetyl-ADP ribose. Complex structures with native alkylimidate and thio-analog support its catalytic relevance and show, together with biochemical assays, that only the coproduct complex is relevant for inhibition by Ex-527, which stabilizes the closed enzyme conformation preventing product release. Ex-527 inhibition thus exploits Sirtuin catalysis, and kinetic isoform differences explain its selectivity. Our results provide insights in Sirtuin catalysis and inhibition with important implications for drug development.

Proteinase K improves quantitative acylation studies.

Acetylation is a common PTM of proteins but is still challenging to analyze. Only few acetylome studies have been performed to tackle this issue. Yet, the detection of acetylated proteins in complex cell lysates remains to be improved. Here, we present a proteomic approach with proteinase K as a suitable protease to identify acetylated peptides quantitatively. We first optimized the digestion conditions using an artificial system of purified bovine histones to find the optimal protease. Subsequently, the capability of proteinase K was demonstrated in complex HEK293 cell lysates. Finally, SILAC in combination with MudPIT was used to show that quantification with proteinase K is possible. In this study, we identified a sheer number of 557 unique acetylated peptides originating from 633 acetylation sites.

Enhancing diagnostic competence with self-explanation prompts and adaptable feedback.

CONTEXT: The fostering of diagnostic competence is an important goal of medical education. Worked-example cases with integrated errors represent a promising method of doing so. OBJECTIVES: This study investigates whether the provision of self-explanation prompts and adaptable feedback fosters diagnostic competence in a computer-supported learning environment based on worked-example cases with integrated errors. METHODS: A total of 103 medical students participated in the study. After a test of prior diagnostic competence, learners studied worked examples with integrated errors for cases of heart failure of different causes in a computer-based learning environment. The worked examples started with the description of a clinical situation in which a student apprentice diagnoses a patient and commits errors in the conclusions he draws from the information presented. Participants were randomly assigned to four learning conditions that varied in two factors: self-explanation prompts and adaptable feedback. In the self-explanation prompts condition, students were prompted to reflect on the errors. Independently of the condition, the student apprentice in the worked example receives feedback on his diagnosis. In the adaptable feedback condition, students were able to adjust the level of elaboration of the feedback. A post-test of diagnostic competence was administered. RESULTS: Adaptable feedback had a positive effect on important aspects of diagnostic competence (strategic knowledge: F(1,93)  = 4.15, p < 0.05, partial η(2)  = 0.04; decision-oriented practical knowledge: F(1,93)  = 4.41, p < 0.05, partial η(2)  = 0.05), whereas self-explanation prompts did not further improve the effectiveness of the learning environment. CONCLUSIONS: In the use of worked examples with integrated errors, the provision of adaptable feedback whereby learners have control over the amount of feedback they receive seems to be advantageous to the development of important decision-oriented aspects of diagnostic competence. Additional help to stimulate reflection about the error by self-explanation prompts does not seem to be critical.

Inhibition of the human deacylase Sirtuin 5 by the indole GW5074.

Sirtuins are NAD(+) consuming protein deacylases involved in many cellular processes from DNA-repair to metabolism. Their contribution to age-related and metabolic diseases makes them attractive pharmaceutical targets. Few pharmacological inhibitors have been reported yet for human Sirt5 since substrates and assays for reliable testing of its activity were unavailable until recently, and most modulators of other Sirtuins were not tested against Sirt5 and therefore have only partially characterized isoform selectivities. We used here improved substrates and assays for testing of known Sirtuin inhibitors for their effects on two activities of human Sirt5, the generic Sirtuin activity deacetylation and the more pronounced Sirt5 activity desuccinylation. Our tests show that most of the compounds have no significant effect on either Sirt5 activity. The indole GW5074, however, was found to be a potent inhibitor for Sirt5's desuccinylation activity, identifying a first pharmacological scaffold for development into Sirt5-specific inhibitors. Interestingly, the compound showed weaker effects in Sirt5 deacetylation assays and also varying potencies against different peptide sequences, indicating a substrate-specific effect of GW5074.

Developing a Simulation to Foster Prospective Mathematics Teachers' Diagnostic Competencies: the Effects of Scaffolding.

To assess individual students' abilities and misconceptions in mathematics, teachers need diagnostic competencies. Although research has addressed the quality of teachers' diagnostic competencies in recent years, it is not very clear how to foster these competencies effectively in the course of prospective teachers' university education. Research suggests that simulations with instructional support are promising tools for fostering complex competencies. We have developed a simulation that aims at measuring and fostering prospective primary school teachers' competencies to assess students' mathematical abilities and misconceptions based on their written task solutions. In this study, we analysed data from prospective primary school mathematics teachers who used one of three different versions of the simulation. Two versions contained a specific type of scaffolding, while the third version did not contain scaffolding. Specifically, the two scaffolding types were content-related scaffolding that emphasized the use of specific pedagogical content knowledge, and strategic scaffolding that emphasized diagnostic activities. The results suggest that integrating scaffolding into the simulation did not substantially influence participants' overall perception of the simulation regarding presence, authenticity, or perceived cognitive load. Compared to participants in a control group without intervention, participants who used the simulation with scaffolding had higher diagnostic accuracy regarding overall assessment of students' competence level. However, only content-related scaffolding but not strategic scaffolding or no scaffolding tended to improve participants' competence in identifying students' specific misconceptions. The results provide a first empirical basis for further development of the simulation.

A Feasibility Study of In-Situ Damage Visualization in Basalt-Fiber Reinforced Polymers with Open-Source Digital Volume Correlation.

This work analyses damage formation within the bulk of basalt fiber-reinforced polymers (BFRP) by means of open-source Digital Volume Correlation (DVC). Volumetric image data were obtained from conventional in-situ X-Ray computed micro-tomography (µCT) of samples loaded in tension. The open-source image registration toolkit Elastix was employed to obtain full 3D displacement fields from the image data. We assessed the accuracy of the DVC results using the method of manufactured solution and showed that the approach followed here can detect deformation with a magnitude in the order of a fiber diameter which in the present case is 17 µm. The beneficial influence of regularization on DVC results is presented on the manufactured solution as well as on real in-situ tensile testing CT data of a BFRP sample. Results of the correlation showed that conventional µCT equipment in combination with DVC can be used to detect defects which could previously only be visualized using synchrotron facilities or destructive methods.

FINCA - a conceptual framework to improve interprofessional collaboration in health education and care.

The health care system in Germany and in many other countries is facing fundamental challenges due to demographic change, which require new integrated care concepts and a revision of the collaboration between health care professions in everyday clinical practice. Internationally, several competency framework models have been proposed, but a framework that explicitly conceptualizes collaborative activities to improve interprofessional problem-solving competency in health care is still missing. Such a framework should define contextual, person-related, process-related, and outcome-related variables relevant to interprofessional problem solving in health care. Against this background, we present a conceptual framework to improve interprofessional collaboration in health education and care (FINCA) developed with scientific consideration of empirical data and various theoretical references. FINCA reflects an interprofessional learning and interaction process involving two persons from different health care professions and with different individual learning prerequisites. These two initially identify a problem that is likely to require interprofessional collaboration at some point. FINCA acknowledges the context of interprofessional learning, teaching, and working as well as its action-modifying context factors. We follow the reasoning that individual learning prerequisites interact with the teaching context during learning activities. At the heart of FINCA are observable collaborative activities (information sharing and grounding; negotiating; regulating; executing interprofessional activities; maintaining communication) that can be used to assess individuals' cognitive and social skills. Eventually, the framework envisages an assessment of the outcomes of interprofessional education and collaboration. The proposed conceptual framework provides the basis for analysis and empirical testing of the components and variables it describes and their interactions across studies, educational interventions, and action-modifying contexts. FINCA further provides the basis for fostering the teaching and learning of interprofessional problem-solving skills in various health care settings. It can support faculty and curriculum developers to systematize the implementation and improvement of interprofessional teaching and learning opportunities. From a practical perspective, FINCA can help to better align curricula for different health professions in the future. In principle, we also see potential for transferability of the framework to other areas where different professions collaborate.

Miniaturization of Non-Assembly Metallic Pin-Joints by LPBF-Based Additive Manufacturing as Perfect Pivots for Pantographic Metamaterials.

This work introduced additively manufactured non-assembly, miniaturized pin-joints for pantographic metamaterials as perfect pivots. The titanium alloy Ti6Al4V was utilized with laser powder bed fusion technology. The pin-joints were produced using optimized process parameters required for manufacturing miniaturized joints, and they were printed at a particular angle to the build platform. Additionally, this process optimization will eliminate the requirement to geometrically compensate the computer-aided design model, allowing for even further miniaturization. In this work, pin-joint lattice structures known as pantographic metamaterials were taken into consideration. The mechanical behavior of the metamaterial was characterized by bias extension tests and cyclic fatigue experiments, showing superior levels of performance (no sign of fatigue for 100 cycles of an elongation of approximately 20%) in comparison to classic pantographic metamaterials made with rigid pivots. The individual pin-joints, with a pin diameter of 350 to 670 µm, were analyzed using computed tomography scans, indicating that the mechanism of the rotational joint functions well even though the clearance of 115 to 132 µm between the moving parts is comparable to the nominal spatial resolution of the printing process. Our findings emphasize new possibilities to develop novel mechanical metamaterials with actual moving joints on a small scale. The results will also support stiffness-optimized metamaterials with variable-resistance torque for non-assembly pin-joints in the future.

Effect of tetracycline hydrochloride application on dental pulp stem cell metabolism-booster or obstacle for tissue engineering?

Introduction: Stem cells and scaffolds are an important foundation and starting point for tissue engineering. Human dental pulp stem cells (DPSC) are mesenchymal stem cells with self-renewal and multi-directional differentiation potential, and are ideal candidates for tissue engineering due to their excellent biological properties and accessibility without causing major trauma at the donor site. Tetracycline hydrochloride (TCH), a broad-spectrum antibiotic, has been widely used in recent years for the synthesis of cellular scaffolds to reduce the incidence of postoperative infections. Methods: In order to evaluate the effects of TCH on DPSC, the metabolism of DPSC in different concentrations of TCH environment was tested. Moreover, cell morphology, survival rates, proliferation rates, cell migration rates and differentiation abilities of DPSC at TCH concentrations of 0-500 µg/ml were measured. Phalloidin staining, live-dead staining, MTS assay, cell scratch assay and real-time PCR techniques were used to detect the changes in DPSC under varies TCH concentrations. Results: At TCH concentrations higher than 250 µg/ml, DPSC cells were sequestered, the proportion of dead cells increased, and the cell proliferation capacity and cell migration capacity decreased. The osteogenic and adipogenic differentiation abilities of DPSC, however, were already inhibited at TCH con-centrations higher than 50 µg/ml. Here, the expression of the osteogenic genes, runt-related transcription factor 2 (RUNX2) and osteocalcin (OCN), the lipogenic genes lipase (LPL), as well as the peroxisome proliferator-activated receptor-γ (PPAR-γ) expression were found to be down-regulated. Discussion: The results of the study indicated that TCH in concentrations above 50 µg/ml negatively affects the differentiation capability of DPSC. In addition, TCH at concentrations above 250 µg/ml adversely affects the growth status, percentage of living cells, proliferation and migration ability of cells.

High incidence of periodontitis in patients with ascitic decompensated cirrhosis.

BACKGROUND: Periodontitis has been associated with various liver diseases. However, the relevance of periodontitis in the progression of decompensated cirrhosis remains inconclusive. In particular, it is unclear whether the common periodontitis pathogens, Porphyromonas gingivalis (P. gingivalis) and Actinobacillus actinomycetemcomitans (A. actinomycetemcomitans), can be detected not only in the oral mucosa but also in ascites and stool. AIM: To investigate the significance of periodontitis, P. gingivalis, and A. actinomycetemcomitans in cirrhosis patients with ascitic decompensation. METHODS: This prospective study was conducted at the University Hospital Hamburg-Eppendorf, a tertiary center in Northern Germany. A cohort of 27 patients with ascitic decompensated liver cirrhosis underwent dental examinations to assess the association between periodontitis and various clinical parameters of cirrhosis, as well as patient outcomes. PCR was used to test gingival samples, ascites, and stool for the presence of P. gingivalis and A. actinomycetemcomitans. Gingival samples were collected by probing the deepest gum pocket of a sextant and wiping them on a cotton swab. RESULTS: Periodontitis was diagnosed in 22 out of 27 (82%) ascite patients, which is significantly more common than in a control cohort of 100 unselected patients (59%, P = 0.04). P. gingivalis was detected in the gingiva of six patients, and one of them also had P. gingivalis in their stool. However, P. gingivalis was not found in the ascites of any patient. Five out of six patients with P. gingivalis had periodontitis (83%). A. actinomycetemcomitans was not detected in any sample. Patients without periodontitis had a significantly higher mortality rate compared to those with periodontitis, and survival (Kaplan-Meier analysis) was longer in patients with periodontitis (P = 0.02). Transplant-free survival was also more common in patients with periodontitis compared to those without (63% vs 0%, P = 0.02). CONCLUSION: Decompensated cirrhotic patients frequently suffer from periodontitis. However, there was no evidence of the translocation of P. gingivalis or A. actinomycetemcomitans into ascites. The survival of cirrhotic patients with periodontitis was not reduced.