BRAF and MEK inhibitor combinations induce potent molecular and immunological effects in NRAS-mutant melanoma cells: Insights into mode of action and resistance mechanisms.

About 25% of melanoma harbor activating NRAS mutations, which are associated with aggressive disease therefore requiring a rapid antitumor intervention. However, no efficient targeted therapy options are currently available for patients with NRAS-mutant melanoma. MEK inhibitors (MEKi) appear to display a moderate antitumor activity and also immunological effects in NRAS-mutant melanoma, providing an ideal backbone for combination treatments. In our study, the MEKi binimetinib, cobimetinib and trametinib combined with the BRAF inhibitors (BRAFi) encorafenib, vemurafenib and dabrafenib were investigated for their ability to inhibit proliferation, induce apoptosis and alter the expression of immune modulatory molecules in sensitive NRAS-mutant melanoma cells using two- and three-dimensional cell culture models as well as RNA sequencing analyses. Furthermore, NRAS-mutant melanoma cells resistant to the three BRAFi/MEKi combinations were established to characterize the mechanisms contributing to their resistance. All BRAFi induced a stress response in the sensitive NRAS-mutant melanoma cells thereby significantly enhancing the antiproliferative and proapoptotic activity of the MEKi analyzed. Furthermore, BRAFi/MEKi combinations upregulated immune relevant molecules, such as ICOS-L, components of antigen-presenting machinery and the "don't eat me signal" molecule CD47 in the melanoma cells. The BRAFi/MEKi-resistant, NRAS-mutant melanoma cells counteracted the molecular and immunological effects of BRAFi/MEKi by upregulating downstream mitogen-activated protein kinase pathway molecules, inhibiting apoptosis and promoting immune escape mechanisms. Together, our study reveals potent molecular and immunological effects of BRAFi/MEKi in sensitive NRAS-mutant melanoma cells that may be exploited in new combinational treatment strategies for patients with NRAS-mutant melanoma.

Signaling-induced systematic repression of miRNAs uncovers cancer vulnerabilities and targeted therapy sensitivity.

Targeted therapies are effective in treating cancer, but success depends on identifying cancer vulnerabilities. In our study, we utilize small RNA sequencing to examine the impact of pathway activation on microRNA (miRNA) expression patterns. Interestingly, we discover that miRNAs capable of inhibiting key members of activated pathways are frequently diminished. Building on this observation, we develop an approach that integrates a low-miRNA-expression signature to identify druggable target genes in cancer. We train and validate our approach in colorectal cancer cells and extend it to diverse cancer models using patient-derived in vitro and in vivo systems. Finally, we demonstrate its additional value to support genomic and transcriptomic-based drug prediction strategies in a pan-cancer patient cohort from the National Center for Tumor Diseases (NCT)/German Cancer Consortium (DKTK) Molecularly Aided Stratification for Tumor Eradication (MASTER) precision oncology trial. In conclusion, our strategy can predict cancer vulnerabilities with high sensitivity and accuracy and might be suitable for future therapy recommendations in a variety of cancer subtypes.

Comparison of Mid-Infrared Handheld and Benchtop Spectrometers to Detect Staphylococcus epidermidis in Bone Grafts.

Bone analyses using mid-infrared spectroscopy are gaining popularity, especially with handheld spectrometers that enable on-site testing as long as the data quality meets standards. In order to diagnose Staphylococcus epidermidis in human bone grafts, this study was carried out to compare the effectiveness of the Agilent 4300 Handheld Fourier-transform infrared with the Perkin Elmer Spectrum 100 attenuated-total-reflectance infrared spectroscopy benchtop instrument. The study analyzed 40 non-infected and 10 infected human bone samples with Staphylococcus epidermidis, collecting reflectance data between 650 cm-1 and 4000 cm-1, with a spectral resolution of 2 cm-1 (Agilent 4300 Handheld) and 0.5 cm-1 (Perkin Elmer Spectrum 100). The acquired spectral information was used for spectral and unsupervised classification, such as a principal component analysis. Both methods yielded significant results when using the recommended settings and data analysis strategies, detecting a loss in bone quality due to the infection. MIR spectroscopy provides a valuable diagnostic tool when there is a tissue shortage and time is of the essence. However, it is essential to conduct further research with larger sample sizes to verify its pros and cons thoroughly.

Radiographic and clinical outcome of tibial plateau fractures treated with bone allograft.

BACKGROUND: To determine the clinical outcome of patients who had been treated with bone allografts during open reduction and internal fixation (ORIF) of tibial head fractures. METHODS: Patients who suffered a medial, lateral, or bicondylar fracture of the tibial plateau and underwent surgical treatment by open reduction and internal fixation (ORIF) using human femoral head bone allografts were included. Patients were invited to provide information for the following: Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), EuroQol Five Dimension score (EQ-5D), Lower Extremity Functional Scale (LEFS) and Parker Mobility Score. Bone mineral density (BMD) of the allograft area and the healthy human bone tissue were measured by quantitative computed tomography. RESULTS: A total of 22 patients with a mean follow-up time of 2.88 ± 2.46 years were included in our study. The most common fractures observed in this study were classified as Schatzker II (11 patients, 50.0%) or AO/OTA 41.B3 (12 patients, 54.5%) fractures. Postoperative WOMAC total was 13.0 (IQR = 16.3, range 0-33). Median quality of life (EQ-5D) score was 0.887 ± 0.121 (range 0.361-1.000). Median Lower Extremity Functional Scale (LEFS) score was 57.5 ± 19.0 (range 33-79). Mean Parker Mobility Score was 9 (range 6-9). Median bone mineral density (BMD) for the whole group was 300.04 ± 226.02 mg/cm3 (range - 88.68 to 555.06 mg/cm3) for region of interest (ROI 5) (central), 214.80 ± 167.45 mg/cm3 (range - 7.16 to 597.21 mg/cm3) for ROI 1-4 (marginal zones: medial, lateral, ventral, dorsal) and 168.14 ± 65.54 mg/cm3 (range 17.47-208.97 mg/cm3) for healthy bone tissue (femur and tibia). CONCLUSION: Based on WOMAC scores, LEFS, ambulatory status, and quality of life findings, it can be concluded that following tibial head ORIF with allograft bone patients has promising results.

Enhancing Bone Infection Diagnosis with Raman Handheld Spectroscopy: Pathogen Discrimination and Diagnostic Potential.

Osteomyelitis is a bone disease caused by bacteria that can damage bone. Raman handheld spectroscopy has emerged as a promising diagnostic tool for detecting bone infection and can be used intraoperatively during surgical procedures. This study involved 120 bone samples from 40 patients, with 80 samples infected with either Staphylococcus aureus or Staphylococcus epidermidis. Raman handheld spectroscopy demonstrated successful differentiation between healthy and infected bone samples and between the two types of bacterial pathogens. Raman handheld spectroscopy appears to be a promising diagnostic tool in bone infection and holds the potential to overcome many of the shortcomings of traditional diagnostic procedures. Further research, however, is required to confirm its diagnostic capabilities and consider other factors, such as the limit of pathogen detection and optimal calibration standards.

Strut Onlay Allograft in Revision Arthroplasty: Osseous Union and Clinical Outcome.

AIM: To evaluate the clinical outcome and the osseous union of strut onlay allografts (SOAs) used as adjunct in revision total joint arthroplasty (TJA). PATIENTS AND METHODS: Patients that had previously undergone SOA augmentation were considered for inclusion. Patients were invited to provide information for the following: Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), EuroQol five dimension score (EQ-5D) and Parker mobility score. Osseous union rates between SOA and the host bone were determined by radiograph with the Emerson classification system. Bone mineral density was measured via quantitative computed tomography. RESULTS: Seventeen patients were identified, at a mean follow-up of 2.8 years. The median total WOMAC score was 22 [interquartile range (IQR)=21]. The median EQ-5D score was 0.887 (IQR=0.350) (time trade-off). The Parker Mobility Score was 8.0 (IQR=3.5). Emerson stages of radiographic graft to host union were 'rounding off' in one case, 'partial bridging' in three and 'complete bridging' in 13. Quantitative computed tomography showed an average bone mineral density of approximately 1,300 mg/cm3. CONCLUSION: From our findings, it is concluded that SOAs used in revision total joint arthroplasty provide promising results and are recommended for broader clinical use. A complete osseous union between host and graft bone was observed in the majority of cases.

High range of motion in the first ten postoperative days after TKA does not predict superior outcome in the long run.

INTRODUCTION: To retrospectively investigate the early postoperative range of motion (ROM) (days 4, 7, 10) after total knee arthroplasty (TKA) and to test for associations (a) with long-term outcome in terms of ROM and (b) with a disease-specific knee score. MATERIALS AND METHODS: A retrospective analysis was performed in patients with previous primary TKA. Data taken from the medical records were ROM from preoperative and postoperative days 4, 7 and 10 and 1 year. As patient-reported outcome the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC Score) was taken from preoperative and one year after TKA. RESULTS: 316 patients (330 knees) were available. Only negligible correlations were determined between ROM at twelve months postoperative and ROM in the early postoperative days (days 4, 7, 10). Similarly, only negligible correlations were determined between ROM in the early postoperative days (days 4, 7, 10) and the 1-year WOMAC. CONCLUSION: From the main findings it would seem that steepness of ROM ascent in the early postoperative days is of minor importance for (a) long-term ROM and (b) long-term knee score outcome after TKA.

Medial unicondylar knee arthroplasty should be reserved for patients with complete joint space collapse.

PURPOSE: To determine whether preoperative radiologic joint space width (JSW) is related to the outcome of medial unicondylar knee arthroplasty (UKA) (primary hypothesis). METHODS: A retrospective comparative analysis was performed. One group was comprised of UKA patients with preoperative JSW 0-1 mm. Another group was made up of patients with preoperative JSW ≥ 2 mm (range 0-4 mm). The JSW was measured from preoperative weight-bearing Schuss-view radiographs. The clinical outcome was determined with the Western Ontario and MacMaster Universities (WOMAC) Osteoarthritis Index score preoperatively and 1 year after medial UKA. Implant survival data were obtained from the arthroplasty register of Tyrol. RESULTS: There were 80 patients with a preoperative JSW 0-1 mm (age 66, BMI 27.8) and 70 patients with a preoperative JSW ≥ 2 mm (age 64, IQR 15, BMI 28.1). WOMAC total was 10 ± 10 in patients with 0-1 mm JSW and 25 ± 47 in patients with ≥ 2 mm JSW at 1 year postoperative (p = 0.052). WOMAC pain at 1 year postoperative was 7 ± 16 in patients with 0-1 mm JSW and 18 ± 46 in patients with ≥ 2 mm JSW (p = 0.047). WOMAC function at 1 year postoperative was 10 ± 9 in patients with 0-1 mm JSW and 17 ± 51 in patients with ≥ 2 mm JSW (p = 0.048). In patients with 0-1 mm JSW 5 year prosthesis survival was 92.3% and in patients with ≥ 2 mm JSW, it was 81.1% (p = 0.016). CONCLUSIONS: In patients with preoperative complete joint space collapse (0-1 mm JSW), clinical outcome was superior to that of patients with incomplete joint space collapse. This was true for both 1 year postoperative WOMAC pain and WOMAC function and for 5 year implant survival rates. On the basis of our findings, it is recommended that 'complete joint space collapse' especially be used to achieve best clinical outcome in medial UKA surgery. LEVEL OF EVIDENCE: IV.

Influence of Nutrient Media Compared to Human Synovial Fluid on the Antibiotic Susceptibility and Biofilm Gene Expression of Coagulase-Negative Staphylococci In Vitro.

Bacterial antibiotic resistance and biofilm formation are mechanisms usually involved in the pathogeny of implant-related infections. Worldwide, antibiotic susceptibility tests are usually carried out using nutrient-rich media. Clinical routine laboratories and even research centers use for example EUCAST or CLSI for guidelines. In this study, we investigated the effect of different nutrient media on the antibiotic susceptibility and icaADBC gene expression of bacteria in biofilm. As media, Müller-Hinton Bouillon (MHB), Tryptic Soy Broth (TSB) and human synovial fluid (SF) diluted 1:4 in phosphate buffered saline (PBS), each also supplemented with 1% glucose, were used. The influence of different nutrient media on the antibiotic susceptibility of coagulase-negative staphylococci (CoNS) was evaluated by counting of colony-forming units (CFU) and by checking the metabolic activity of the bacteria. We used reverse transcriptase and real-time qPCR to investigate the influence of nutrient media on the biofilm gene expression. We used two-way analysis of variance (ANOVA). p < 0.05 was considered to be statistically significant. Significant differences in growth and antibiotic susceptibility were detected in all strains tested among the different media used. The nutrient media showed influence on the cell viability of all bacteria after antibiotic treatment. IcaADBC gene expression was significantly influenced by glucose and all nutrient media. The results highlight the influence of glucose on the antibiotic susceptibility, growth and gene expression of all strains tested. For all strains, a significant difference in bacterial recovery, viability and gene expression were found when compared to biofilm grown in SF.

Pathological Fracture of the Tibia as a First Sign of Hyperparathyroidism - A Case Report and Systematic Review of the Current Literature.

BACKGROUND/AIM: Pathological fractures are rare, suspicious and in some cases mentioned as the first sign of a malignant tumor. We present an uncommon case with a pathological fracture of the tibia diaphysis as the first sign of severe hyperparathyroidism. CASE REPORT: We report the case of a female patient who was referred to the emergency department with a history of progressively worsening pain in the lower left leg and an inability to fully bear weight. No history of trauma or any other injury was reported. An x-ray revealed an extensive osteolytic lesion in the tibial shaft with cortical bone destruction. CONCLUSION: Our case, together with very few cases described in the current literature, emphasizes that in the presence of hypercalcemia and lytic lesions primary hyperparathyroidism should always be considered as a differential diagnosis. Lytic bone lesions can lead to pathological fractures and severe impairment of quality of life.

The balance between the intronic miR-342 and its host gene Evl determines hematopoietic cell fate decision.

Protein-coding and non-coding genes like miRNAs tightly control hematopoietic differentiation programs. Although miRNAs are frequently located within introns of protein-coding genes, the molecular interplay between intronic miRNAs and their host genes is unclear. By genomic integration site mapping of gamma-retroviral vectors in genetically corrected peripheral blood from gene therapy patients, we identified the EVL/MIR342 gene locus as a hotspot for therapeutic vector insertions indicating its accessibility and expression in human hematopoietic stem and progenitor cells. We therefore asked if and how EVL and its intronic miRNA-342 regulate hematopoiesis. Here we demonstrate that overexpression (OE) of Evl in murine primary Lin- Sca1+ cKit+ cells drives lymphopoiesis whereas miR-342 OE increases myeloid colony formation in vitro and in vivo, going along with a profound upregulation of canonical pathways essential for B-cell development or myelopoietic functions upon Evl or miR-342 OE, respectively. Strikingly, miR-342 counteracts its host gene by targeting lymphoid signaling pathways, resulting in reduced pre-B-cell output. Moreover, EVL overexpression is associated with lymphoid leukemia in patients. In summary, our data show that one common gene locus regulates distinct hematopoietic differentiation programs depending on the gene product expressed, and that the balance between both may determine hematopoietic cell fate decision.

Antibacterial and Anti-Biofilm Activity of Omega-3 Polyunsaturated Fatty Acids against Periprosthetic Joint Infections-Isolated Multi-Drug Resistant Strains.

Background: Implantable medical devices, such as prosthetics, catheters, and several other devices, have revolutionized medicine, but they increase the infection risk. In previous decades, commercially available antibiotics lost their activity against coagulase-negative Staphylococci (CoNS) and several other microorganisms. Docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) are the two major omega-3 polyunsaturated fatty acids (ω-3 PUFAs) with antimicrobial properties. Materials and Methods: In this study, we tested the EPA and the DHA for its antibacterial and anti-biofilm activity in vitro against Staphylococcus epidermidis, Staphylococcus aureus, and different CoNS as reference strains and isolated from patients undergoing orthopedic treatment for implant infections. The tests were carried out with the strains in planktonic and biofilm form. Cytotoxicity assay was carried out with EPA and DHA using human gingival fibroblasts HGF-1. Results: The highest concentration of EPA and DHA promoted the complete killing of S. epidermidis 1457 and S. aureus ATCC 25923 in planktonic form. The fatty acids showed low activity against P. aeruginosa. EPA and DHA completely killed or significantly reduced the count of planktonic bacteria of the patient isolated strains. When incubated with media enriched with EPA and DHA, the biofilm formation was significantly reduced on S. epidermidis 1457 and not present on S. aureus ATCC 25923. The reduction or complete killing were also observed with the clinical isolates. The pre-formed biofilms showed reduction of the cell counting after treatment with EPA and DHA. Conclusion: In this study, the ω-3 PUFAs EPA and DHA showed antimicrobial and anti-biofilm activity in vitro against S. aureus, S. epidermidis, and P. aeruginosa, as well as against multi-drug resistant S. aureus and CoNS strains isolated from patients undergoing periprosthetic joint infections (PJI) treatment. Higher concentrations of the fatty acids showed killing activity on planktonic cells and inhibitory activity of biofilm formation. Although both substances showed antimicrobial activity, EPA showed better results in comparison with DHA. In addition, when applied on human gingival fibroblasts in vitro, EPA and DHA showed a possible protective effect on cells cultured in medium enriched with ethanol. Further studies are required to confirm the antimicrobial activity of EPA and DHA against multi-drug resistant strains and pan-drug resistant strains.

Variation of BMP2 Concentration and Its Activity in Bone Grafts Obtained from Patients Undergoing Hip Replacement Surgery.

AIM: Bone morphogenetic protein 2 (BMP2) is a member of a subgroup of the transforming growth factor beta superfamily and triggers various signaling events which in turn stimulate chondrogenesis, osteogenesis, angiogenesis and extracellular matrix remodeling leading to fracture healing. In this study, we quantified the concentration of BMP2 in fresh human bone grafts obtained from 40 patients undergoing hip replacement surgery. Besides the concentration, the activity of the detected BMP2 was also investigated. MATERIALS AND METHODS: In this study, the concentration of BMP2 in fresh human bone grafts obtained from 40 patients undergoing hip replacement surgery was quantified. Human BMP2 enzyme-linked immunosorbent assays and bicinchoninic acid quantification was used to determine the total concentration of protein present in each sample. To determine the activity of the BMP2 found in each bone sample, alkaline phosphatase activity was measured by colorimetric assay. RESULTS: The amount of BMP2 seemed to vary slightly between the patients. Taking into consideration the patient's gender, we observed that male patients presented slightly more BMP2 in comparison with females. When analyzing the activity of BMP2, we observed that in female patients, the activity was slightly higher in comparison to males. This variation may be caused by a number of factors, including but not limited to gender, age, osteoporosis and previous diseases. This information shows that the osteogenic potential of different bone graft samples is not consistent. CONCLUSION: The activity of BMP2 in femur heads obtained from patients undergoing total hip replacement surgery showed significant variation according to gender and age. The measurement of bone proteins activity might be promising as a qualitative method in bone banks and should be further investigated.

[Trochleoplasty: Surgical technique : Video article]. / Trochleaplastik: Operationstechnik : Videobeitrag.

A 29-year-old physically active patient presented with recurrent right-sided patellar dislocation. Clinical and radiological investigation showed patellar instability with stable cruciate and collateral ligaments, excess internal rotation of the right femur, as well as trochlear dysplasia. Treatment consisted of trochleoplasty in combination with medial patellofemoral ligament reconstruction.

Long Non-coding RNAs as Functional and Structural Chromatin Modulators in Acute Myeloid Leukemia.

Acute myeloid leukemia is a hematopoietic neoplasm of dismal prognosis that results from the accumulation of immature myeloid blasts in the bone marrow and the peripheral blood. It is strongly dependent on epigenetic regulation for disease onset, maintenance and in response to treatment. Epigenetic regulation refers to the multiple chemical modifications of DNA or DNA-associated proteins that alter chromatin structure and DNA accessibility in a heritable manner, without changing DNA sequence. Unlike sequence-specific transcription factors, epigenetic regulators do not necessarily bind DNA at consensus sequences, but still achieve reproducible target binding in a manner that is cell and maturation-type specific. A growing body of evidence indicates that epigenetic regulators rely, amongst other factors, on their interaction with untranslated RNA molecules for guidance to particular targets on DNA. Non (protein)-coding RNAs are the most abundant transcriptional products of the coding genome, and comprise several different classes of molecules with unique lengths, conformations and targets. Amongst these, long non-coding RNAs (lncRNAs) are species of 200 bp to >100 K bp in length, that recognize, and bind unique and largely uncharacterized DNA conformations. Some have been shown to bind epigenetic regulators, and thus constitute attractive candidates to mediate epigenetic target specificity. Herein, we postulate that lncRNAs are central players in the unique epigenetic programming of AML and review recent evidence in support of this view. We discuss the value of lncRNAs as putative diagnostic, prognostic and therapeutic targets in myeloid leukemias and indicate novel directions in this exciting research field.

Patient satisfaction after total knee arthroplasty is better in patients with pre-operative complete joint space collapse.

AIM OF THE STUDY: To determine if pre-operative radiologic minimal joint space width (mJSW) is related to the outcome of total knee arthroplasty (TKA) (primary hypothesis). Likewise, the aim was to test if pre-operative mJSW is related to prosthesis survival (secondary hypothesis). METHODS: A retrospective comparative analysis was performed. Group 1 was comprised of patients with pre-operative mJSW 0-1 mm. Group 2 were patients with pre-operative mJSW ≥ 2 mm. The clinical outcome was determined with the Western Ontario and MacMaster Universities Osteoarthritis Index (WOMAC) score pre-operatively and one year after TKA. Only patients with pre-operative weight-bearing radiographs and complete WOMAC score data were accepted. RESULTS: Available for analysis were 377 patients, of whom 188 were allocated to Group 1 (118 female, 70 male, age 70 ± 11 years) and 189 to Group 2 (118 female, 71 male, age 70 ± 13 years). Pre-operative WOMAC total and WOMAC subscores showed no significant differences between groups. Post-operatively, the WOMAC total was significantly better in Group 1 than in Group 2, 10 ± 22 and 19 ± 31, respectively (p < 0.001, Power 97.5%). Similarly, the WOMAC subscores for pain, stiffness, and function were also significantly better in Group 1 than in Group 2. Five-year prosthesis survival was 94.2 and 91.6% in Groups 1 and 2, respectively (p = 0.07, Power 71%). DISCUSSION: Patients with pre-operative complete joint space collapse (0 to 1 mm mJSW) achieve a significantly better WOMAC result from TKA than do those with a mJSW equal to or greater than 2 mm. From our findings, it is recommended that "complete joint space collapse" especially be used as an indication for TKA surgery. CONCLUSION: Our study was underpowered to sufficiently show an effect of pre-operative mJSW on prosthesis survival.

Correction to: EVI2B is a C/EBPα target gene required for granulocytic differentiation and functionality of hematopoietic progenitors.

Since publication of this article, the authors identified an error in the acknowledgments section. The original sentence in acknowledgments reads as follows.

Incubation of Immune Cell Grafts With MAX.16H5 IgG1 Anti-Human CD4 Antibody Prolonged Survival After Hematopoietic Stem Cell Transplantation in a Mouse Model for Fms Like Tyrosine Kinase 3 Positive Acute Myeloid Leukemia.

Despite the constant development of innovative therapeutic options for hematological malignancies, the gold-standard therapy regimen for curative treatment often includes allogeneic hematopoietic stem cell transplantation (HSCT). The graft-vs.-leukemia effect (GVL) is one of the main therapeutic goals that arises from HSCT. On the other hand, graft-vs.-host disease (GVHD) is still one of the main and most serious complications following allogeneic HSCT. In acute myeloid leukemia (AML), HSCT together with high-dose chemotherapy is used as a treatment option. An aggressive progression of the disease, a decreased response to treatment, and a poor prognosis are connected to internal tandem duplication (ITD) mutations in the Fms like tyrosine kinase 3 (FLT3) gene, which affects around 30% of AML patients. In this study, C3H/HeN mice received an allogeneic graft together with 32D-FLT3ITD AML cells to induce acute GVHD and GVL. It was examined if pre-incubation of the graft with the anti-human cluster of differentiation (CD) 4 antibody MAX.16H5 IgG1 prevented the development of GVHD and whether the graft function was impaired. Animals receiving grafts pre-incubated with the antibody together with FLT3ITD AML cells survived significantly longer than mice receiving untreated grafts. The observed prolonged survival due to MAX.16H5 incubation of immune cell grafts prior to transplantation may allow an extended application of additional targeted strategies in the treatment of AML.

MicroRNA-143 targets ERK5 in granulopoiesis and predicts outcome of patients with acute myeloid leukemia.

Hematopoiesis, the formation of blood cells from hematopoietic stem cells (HSC), is a highly regulated process. Since the discovery of microRNAs (miRNAs), several studies have shown their significant role in the regulation of the hematopoietic system. Impaired expression of miRNAs leads to disrupted cellular pathways and in particular causes loss of hematopoietic ability. Here, we report a previously unrecognized function of miR-143 in granulopoiesis. Hematopoietic cells undergoing granulocytic differentiation exhibited increased miR-143 expression. Overexpression or ablation of miR-143 expression resulted in accelerated granulocytic differentiation or block of differentiation, respectively. The absence of miR-143 in mice resulted in a reduced number of mature granulocytes in blood and bone marrow. Additionally, we observed an association of high miR-143 expression levels with a higher probability of survival in two different cohorts of patients with acute myeloid leukemia (AML). Overexpression of miR-143 in AML cells impaired cell growth, partially induced differentiation, and caused apoptosis. Argonaute2-RNA-Immunoprecipitation assay revealed ERK5, a member of the MAPK-family, as a target of miR-143 in myeloid cells. Further, we observed an inverse correlation of miR-143 and ERK5 in primary AML patient samples, and in CD34+ HSPCs undergoing granulocytic differentiation and we confirmed functional relevance of ERK5 in myeloid cells. In conclusion, our data describe miR-143 as a relevant factor in granulocyte differentiation, whose expression may be useful as a prognostic and therapeutic factor in AML therapy.

Progress in Knee Arthroscopy Skills of Residents and Medical Students: A Prospective Assessment of Simulator Exercises and Analysis of Learning Curves.

OBJECTIVE: Knee arthroscopies are very common orthopedic procedures. For a number of reasons, including increased public awareness for medical errors, patient safety, strict regulations governing duty-hours for residents, surgeons' liability, and an increasing emphasis on the efficient use of operating room time, interest in simulator training is on the rise. It was the purpose of this study to analyze learning curves of medical students and orthopedic resident surgeons using a virtual knee arthroscopy simulator. DESIGN: Learning curves of medical students and orthopedic residents were measured perspective using an arthroscopic training simulator for 2 different exercises. Time, camera and probe movement as well as camera and probe roughness were the parameters to be compared. Mean and standard deviation of the initial and the final score for the consecutively performed exercises as well as their slope were reported. SETTING: The study was performed at the Medical University of Innsbruck, Department of Orthopaedic Surgery. Level of clinical care: institutional. PARTICIPANTS: A Students Group (n = 10) consisting of medical students at the Medical University of Innsbruck with no prior knowledge of arthroscopy but interest in orthopedic surgery was selected. The group was compared to a Residents Group (n = 9) which was comprised of orthopedic resident surgeons who had learned arthroscopy in operation courses. All participants involved in the study did several repetitions of the described exercises. RESULTS: Both groups improved their skills after several repetitions. Residents were on average faster, moved the camera less, and touched the cortical tissue less than the students. For certain parameters students showed a steeper improvement curve than did residents, because the students started from a different experience level. CONCLUSIONS: In conclusion, our results demonstrate the usefulness of virtual knee arthroscopy simulators as an important tool for improving surgical and arthroscopic skills in orthopedic resident surgeons, and medical students.