Involvement of mitogen- and stress-activated protein kinase (MSK)1 in BMP-6-induced chondrocyte differentiation.

Bone morphogenetic proteins (BMPs) are involved in several cellular responsive actions, such as development, cell differentiation, and apoptosis, via their specific transmembrane receptors. In particular, BMPs promote the differentiation and maturation of bone and cartilage from mesenchymal stem cells. Based on comprehensive analyses performed with a large number of antibodies, mitogen- and stress-activated protein kinase (MSK)1 was found to be immediately phosphorylated in the mouse chondrocyte precursor cell line, ATDC5, upon BMP-6 stimulation. The overexpression and knockdown of MSK1 in ATDC5 cells also enhanced and suppressed BMP-6-induced chondrocyte differentiation, respectively. Similar to ATDC5 cells, an ex vivo organ culture system using mouse embryonic metatarsal bones also demonstrated that BMP-6-mediated MSK1 activation might play a role in chondrocyte differentiation. Using several inhibitors, the p38 kinase pathway was confirmed to be implicated in BMP-6-induced phosphorylation of MSK1. Furthermore, MSK1 mutants lacking kinase activities and those lacking serine/threonine residues targeted by p38 kinase severely impaired their ability to potentiate BMP-6-induced chondrogenic differentiation of ATDC5 cells. Interestingly, a loss-of-function study for Smad4 perturbed BMP-6-induced phosphorylation of p38 kinase to inhibit BMP-6-mediated chondrocyte differentiation via MSK1 activation. Overall, both Smad-dependent and independent pathways require BMP-6-induced chondrocyte differentiation via MSK1 activation in ATDC5 cells.

Dual targeting of brain region-specific kinases potentiates neurological rescue in Spinocerebellar ataxia type 1.

A critical question in neurodegeneration is why the accumulation of disease-driving proteins causes selective neuronal loss despite their brain-wide expression. In Spinocerebellar ataxia type 1 (SCA1), accumulation of polyglutamine-expanded Ataxin-1 (ATXN1) causes selective degeneration of cerebellar and brainstem neurons. Previous studies revealed that inhibiting Msk1 reduces phosphorylation of ATXN1 at S776 as well as its levels leading to improved cerebellar function. However, there are no regulators that modulate ATXN1 in the brainstem-the brain region whose pathology is most closely linked to premature death. To identify new regulators of ATXN1, we performed genetic screens and identified a transcription factor-kinase axis (ZBTB7B-RSK3) that regulates ATXN1 levels. Unlike MSK1, RSK3 is highly expressed in the human and mouse brainstems where it regulates Atxn1 by phosphorylating S776. Reducing Rsk3 rescues brainstem-associated pathologies and deficits, and lowering Rsk3 and Msk1 together improves cerebellar and brainstem function in an SCA1 mouse model. Our results demonstrate that selective vulnerability of brain regions in SCA1 is governed by region-specific regulators of ATXN1, and targeting multiple regulators could rescue multiple degenerating brain areas.

8-Oxoguanine DNA glycosylase 1 selectively modulates ROS-responsive NF-κB targets through recruitment of MSK1 and phosphorylation of RelA/p65 at Ser276.

Nuclear factor kappa B (NF-κB) activity is regulated by various posttranslational modifications, of which Ser276 phosphorylation of RelA/p65 is particularly impacted by reactive oxygen species (ROS). This modification is responsible for selective upregulation of a subset of NF-κB targets; however, the precise mechanism remains elusive. ROS have the ability to modify cellular molecules including DNA. One of the most common oxidation products is 8-oxo-7,8-dihydroguanine (8-oxoGua), which is repaired by the 8-oxoguanine DNA glycosylase1 (OGG1)-initiated base excision repair pathway. Recently, a new function of OGG1 has been uncovered. OGG1 binds to 8-oxoGua, facilitating the occupancy of NF-κB at promoters and enhancing transcription of pro-inflammatory cytokines and chemokines. In the present study, we demonstrated that an interaction between DNA-bound OGG1 and mitogen-and stress-activated kinase 1 is crucial for RelA/p65 Ser276 phosphorylation. ROS scavenging or OGG1 depletion/inhibition hindered the interaction between mitogen-and stress-activated kinase 1 and RelA/p65, thereby decreasing the level of phospho-Ser276 and leading to significantly lowered expression of ROS-responsive cytokine/chemokine genes, but not that of Nfkbis. Blockade of OGG1 binding to DNA also prevented promoter recruitment of RelA/p65, Pol II, and p-RNAP II in a gene-specific manner. Collectively, the data presented offer new insights into how ROS signaling dictates NF-κB phosphorylation codes and how the promoter-situated substrate-bound OGG1 is exploited by aerobic mammalian cells for timely transcriptional activation of ROS-responsive genes.

Histomic and transcriptomic features of MRI-visible and invisible clinically significant prostate cancers are associated with prognosis.

Magnetic resonance imaging (MRI) is increasingly used to triage patients for prostate biopsy. However, 9% to 24% of clinically significant (cs) prostate cancers (PCas) are not visible in MRI. We aimed to identify histomic and transcriptomic determinants of MRI visibility and their association to metastasis, and PCa-specific death (PCSD). We studied 45 radical prostatectomy-treated patients with csPCa (grade group [GG]2-3), including 30 with MRI-visible and 15 with MRI-invisible lesions, and 18 men without PCa. First, histological composition was quantified. Next, transcriptomic profiling was performed using NanoString technology. MRI visibility-associated differentially expressed genes (DEGs) and Reactome pathways were identified. MRI visibility was classified using publicly available genes in MSK-IMPACT and Decipher, Oncotype DX, and Prolaris. Finally, DEGs and clinical parameters were used to classify metastasis and PCSD in an external cohort, which included 76 patients with metastatic GG2-4 PCa, and 84 baseline-matched controls without progression. Luminal area was lower in MRI-visible than invisible lesions and low luminal area was associated with short metastasis-free and PCa-specific survival. We identified 67 DEGs, eight of which were associated with survival. Cell division, inflammation and transcriptional regulation pathways were upregulated in MRI-visible csPCas. Genes in Decipher, Oncotype DX and MSK-IMPACT performed well in classifying MRI visibility (AUC = 0.86-0.94). DEGs improved classification of metastasis (AUC = 0.69) and PCSD (AUC = 0.68) over clinical parameters. Our data reveals that MRI-visible csPCas harbor more aggressive histomic and transcriptomic features than MRI-invisible csPCas. Thus, targeted biopsy of visible lesions may be sufficient for risk stratification in patients with a positive MRI.

Engineering Innervated Musculoskeletal Tissues for Regenerative Orthopedics and Disease Modeling.

Musculoskeletal (MSK) disorders significantly burden patients and society, resulting in high healthcare costs and productivity loss. These disorders are the leading cause of physical disability, and their prevalence is expected to increase as sedentary lifestyles become common and the global population of the elderly increases. Proper innervation is critical to maintaining MSK function, and nerve damage or dysfunction underlies various MSK disorders, underscoring the potential of restoring nerve function in MSK disorder treatment. However, most MSK tissue engineering strategies have overlooked the significance of innervation. This review first expounds upon innervation in the MSK system and its importance in maintaining MSK homeostasis and functions. This will be followed by strategies for engineering MSK tissues that induce post-implantation in situ innervation or are pre-innervated. Subsequently, research progress in modeling MSK disorders using innervated MSK organoids and organs-on-chips (OoCs) is analyzed. Finally, the future development of engineering innervated MSK tissues to treat MSK disorders and recapitulate disease mechanisms is discussed. This review provides valuable insights into the underlying principles, engineering methods, and applications of innervated MSK tissues, paving the way for the development of targeted, efficacious therapies for various MSK conditions.

High-quality FLORET UTE imaging for clinical translation.

PURPOSE: To develop a robust 3D ultrashort-TE (UTE) protocol that can reproducibly provide high-quality images, assessed by the ability to yield clinically diagnostic images, and is suitable for clinical translation. THEORY AND METHODS: Building on previous work, a UTE sampled with Fermat looped orthogonally encoded trajectories (FLORET) was chosen as a starting point due to its shorter, clinically reasonable scan times. Modifications to previous FLORET implementations included gradient waveform frequency limitations, a new trajectory ordering scheme, a balanced SSFP implementation, fast gradient spoiling, and full inline reconstruction. FLORET images were collected in phantoms and humans on multiple scanners and sites to demonstrate these improvements. RESULTS: The updates to FLORET provided high-quality images in phantom, musculoskeletal, and pulmonary applications. The gradient waveform modifications and new trajectory ordering scheme significantly reduced visible artifacts. Fast spoiling reduced acquisition time by 20%-28%. Across the various scanners and sites, the inline image quality was consistent and of diagnostic quality. Total image acquisition plus reconstruction time was less than 4 min for musculoskeletal and pulmonary applications with reconstructions taking less than 1 min. CONCLUSION: Recently developed improvements for the FLORET sequence have enabled robust, high-quality UTE acquisitions with short acquisition and reconstruction times. This enables clinical UTE imaging as demonstrated by the implementation of the sequence and acquisition on five MRI scanners, at three different sites, without the need for any additional system characterization or measurements.

Revision to the musculoskeletal domain of the BILAG-2004 index to incorporate ultrasound findings.

OBJECTIVES: To improve the definitions of inflammatory arthritis within the musculoskeletal (MSK) domain of the BILAG-2004 index by incorporating imaging findings and clinical features predictive of response to treatment. METHODS: The BILAG MSK Subcommittee proposed revisions to the BILAG-2004 index definitions of inflammatory arthritis, based on review of evidence in two recent studies. Data from these studies were pooled and analysed to determine the impact of the proposed changes on the severity grading of inflammatory arthritis. RESULTS: The revised definition for severe inflammatory arthritis includes definition of 'basic activities of daily living'. For moderate inflammatory arthritis, it now includes synovitis, defined by either observed joint swelling or MSK US evidence of inflammation in joints and surrounding structures. For mild inflammatory arthritis, the definition now includes reference to symmetrical distribution of affected joints and guidance on how US may help re-classify patients as moderate or no inflammatory arthritis. Data from two recent SLE trials were analysed (219 patients). A total of 119 (54.3%) were graded as having mild inflammatory arthritis (BILAG-2004 Grade C). Of these, 53 (44.5%) had evidence of joint inflammation (synovitis or tenosynovitis) on US. Applying the new definition increased the number of patients classified as moderate inflammatory arthritis from 72 (32.9%) to 125 (57.1%), while patients with normal US (n = 66/119) could be recategorized as BILAG-2004 Grade D (inactive disease). CONCLUSIONS: Proposed changes to the definitions of inflammatory arthritis in the BILAG-2004 index will result in more accurate classification of patients who are more or less likely to respond to treatment.

Chromatin Kinases Act on Transcription Factors and Histone Tails in Regulation of Inducible Transcription.

The inflammatory response requires coordinated activation of both transcription factors and chromatin to induce transcription for defense against pathogens and environmental insults. We sought to elucidate the connections between inflammatory signaling pathways and chromatin through genomic footprinting of kinase activity and unbiased identification of prominent histone phosphorylation events. We identified H3 serine 28 phosphorylation (H3S28ph) as the principal stimulation-dependent histone modification and observed its enrichment at induced genes in mouse macrophages stimulated with bacterial lipopolysaccharide. Using pharmacological and genetic approaches, we identified mitogen- and stress-activated protein kinases (MSKs) as primary mediators of H3S28ph in macrophages. Cell-free transcription assays demonstrated that H3S28ph directly promotes p300/CBP-dependent transcription. Further, MSKs can activate both signal-responsive transcription factors and the chromatin template with additive effects on transcription. Specific inhibition of MSKs in macrophages selectively reduced transcription of stimulation-induced genes. Our results suggest that MSKs incorporate upstream signaling inputs and control multiple downstream regulators of inducible transcription.

LRRC8A-containing chloride channel is crucial for cell volume recovery and survival under hypertonic conditions.

Regulation of cell volume is essential for tissue homeostasis and cell viability. In response to hypertonic stress, cells need rapid electrolyte influx to compensate water loss and to prevent cell death in a process known as regulatory volume increase (RVI). However, the molecular component able to trigger such a process was unknown to date. Using a genome-wide CRISPR/Cas9 screen, we identified LRRC8A, which encodes a chloride channel subunit, as the gene most associated with cell survival under hypertonic conditions. Hypertonicity activates the p38 stress-activated protein kinase pathway and its downstream MSK1 kinase, which phosphorylates and activates LRRC8A. LRRC8A-mediated Cl- efflux facilitates activation of the with-no-lysine (WNK) kinase pathway, which in turn, promotes electrolyte influx via Na+/K+/2Cl- cotransporter (NKCC) and RVI under hypertonic stress. LRRC8A-S217A mutation impairs channel activation by MSK1, resulting in reduced RVI and cell survival. In summary, LRRC8A is key to bidirectional osmotic stress responses and cell survival under hypertonic conditions.

Spinal fusion surgery use among adults with low back pain enrolled in a digital musculoskeletal program: an observational study.

OBJECTIVES: To compare 12-month spinal fusion surgery rates in the setting of low back pain among digital musculoskeletal (MSK) program participants versus a comparison cohort who only received usual care. STUDY DESIGN: Retrospective cohort study with propensity score matched comparison cohort using commercial medical claims data representing over 100 million commercially insured lives. METHODS: All study subjects experienced low back pain between January 2020 and December 2021. Digital MSK participants enrolled in the digital MSK low back program between January 2020 and December 2021. Non-participants had low back pain related physical therapy (PT) between January 2020 and December 2021. Digital MSK participants were matched to non-participants with similar demographics, comorbidities and baseline MSK-related medical care use. Spinal fusion surgery rates at 12 months post participation were compared. RESULTS: Compared to non-participants, digital MSK participants had lower rates of spinal fusion surgery in the post-period (0.7% versus 1.6%; p < 0.001). Additionally, in the augmented inverse probability weighting (AIPW) model, digital MSK participants were found to have decreased odds of undergoing spinal fusion surgery (adjusted odds ratio: 0.64, 95% CI: 0.51-0.81). CONCLUSIONS: This study provides evidence that participation in a digital MSK program is associated with a lower rate of spinal fusion surgery.

Preparing MSK radiologists of the future.

The future will bring increasing demands for specialty training of MSK radiologists. These will include requirements for further standardization of curriculum, educational methods, and documentation. This will place further burdens (both temporal and financial) on the fellowship programs and may lead to termination of some programs. There is a risk that increasingly bureaucratic training requirements may "crowd out" the basic conceptual education necessary for the continued growth and relevance of the subspecialty. Educators must find ways to incorporate these aspects into programs even when they are not mandated.

A radiographic artificial intelligence tool to identify candidates suitable for partial knee arthroplasty.

INTRODUCTION: Knee osteoarthritis is a prevalent condition frequently necessitating knee replacement surgery, with demand projected to rise substantially. Partial knee arthroplasty (PKA) offers advantages over total knee arthroplasty (TKA), yet its utilisation remains low despite guidance recommending consideration alongside TKA in shared decision making. Radiographic decision aids exist but are underutilised due to clinician time constraints. MATERIALS AND METHODS: This research develops a novel radiographic artificial intelligence (AI) tool using a dataset of knee radiographs and a panel of expert orthopaedic surgeons' assessments. Six AI models were trained to identify PKA candidacy. RESULTS: 1241 labelled four-view radiograph series were included. Models achieved statistically significant accuracies above random assignment, with EfficientNet-ES demonstrating the highest performance (AUC 95%, F1 score 83% and accuracy 80%). CONCLUSIONS: The AI decision tool shows promise in identifying PKA candidates, potentially addressing underutilisation of this procedure. Its integration into clinical practice could enhance shared decision making and improve patient outcomes. Further validation and implementation studies are warranted to assess real-world utility and impact.

Mitogen- and stress-activated protein kinase (MSK1/2) regulated gene expression in normal and disease states.

The mitogen- and stress-activated protein kinases (MSK) are epigenetic modifiers that regulate gene expression in normal and disease cell states. MSK1 and 2 are involved in a chain of signal transduction events bringing signals from the external environment of a cell to specific sites in the genome. MSK1/2 phosphorylate histone H3 at multiple sites, resulting in chromatin remodeling at regulatory elements of target genes and the induction of gene expression. Several transcription factors (RELA of NF-κB and CREB) are also phosphorylated by MSK1/2 and contribute to induction of gene expression. In response to signal transduction pathways, MSK1/2 can stimulate genes involved in cell proliferation, inflammation, innate immunity, neuronal function, and neoplastic transformation. Abrogation of the MSK-involved signaling pathway is among the mechanisms by which pathogenic bacteria subdue the host's innate immunity. Depending on the signal transduction pathways in play and the MSK-targeted genes, MSK may promote or hinder metastasis. Thus, depending on the type of cancer and genes involved, MSK overexpression may be a good or poor prognostic factor. In this review, we focus on mechanisms by which MSK1/2 regulate gene expression, and recent studies on their roles in normal and diseased cells.

Patient Factors Affect Ergonomic Strain of Endoscopists During Colonoscopy.

INTRODUCTION: Endoscopic procedures place a great deal of muscular strain on providers, especially over the span of their careers. In this study we quantitatively analyzed the effects of patient factors such as age, body mass index, and sex on the ergonomics of endoscopists performing colonoscopies. METHODS: Surface electromyography (sEMG) was used to measure ergonomic strain of physicians while performing colonoscopies in several key muscle groups. The percent of the maximum voluntary contraction (%MVC) was used as a measure of muscular strain. Data was then analyzed based on the patient characteristics above. RESULTS: Endoscopists performing colonoscopies on female patients (n = 47) experienced significantly higher ergonomic strain in their right trapezius and right posterior forearm muscle groups when compared to colonoscopies performed on males (n = 35) (%MVC R-trapezius: Male: 8.2; Female: 8.9; p = 0.048); (%MVC R-posterior forearm: Male: 10.4; Female: 11.6; p = 0.0006). Operators experienced greater strain in the same muscle groups when performing colonoscopies on patients with BMI ≤ 25 (n = 25) when compared to patients with BMI > 25 (n = 57) (%MVC R-trapezius: BMI < 25: 9.7; BMI ≥ 25: 8.2; p = 0.0002); (%MVC R-posterior forearm: BMI < 25: 11.9; BMI ≥ 25: 10.8; p = 0.0001). CONCLUSION: Physicians experienced greater ergonomic strain when performing colonoscopies on female patients and on patients with a BMI < 25. We believe that these factors potentially impact the tortuosity of the colon and therefore influence the difficulty of navigating the endoscope. These results may aid physicians in gauging the anticipated difficulty of colonoscopies based on patient factors. Increased awareness of their posturing and ergonomics during challenging cases will alleviate musculoskeletal injuries in the long run.

Preoperative frailty assessment in older patients with colorectal cancer: use of clinical and radiological tool.

PURPOSE: The Memorial Sloan Kattering Frailty Index (MSK-FI) and the Skeletal Muscle Index (SMI) have recently gained attention as markers of frailty and decreased physiologic reserve, and are promising as predictors of adverse postoperative outcomes in patients undergoing oncologic surgery. The objective of this study was to establish the prognostic accuracy of these indexes in a cohort of patients with colorectal cancer subjected to surgical intervention. METHODS: We performed an observational study including all patients older than 60 years, subjected to colorectal cancer surgery between January 2010 and May 2020, and stratified our cohort based on the presence of frailty, as defined by MSK-FI ≥ 3. Computed tomography was used to calculate SMI, using a standardized institutional protocol. A multivariable analysis was used to study the association between these novel indexes with adverse postoperative outcomes in our cohort. RESULTS: A total of 216 patients were included. Among these, 56 (26%) qualified as frail and 132 (62%) had a low SMI. On multivariable analysis (adjusted by patient and intraoperative characteristics), frailty was associated with increased risk of having a major postoperative complication (OR 29.78, 95%CI 10.36-85.71) and increased admission to the intensive care unit (OR 4.99, 95%CI 1.55-16.06), while both frailty and low SMI were associated with prolonged length of stay (OR 11.22, 95%CI 8.91-13.53 and OR 0.14, 95% CI 0.06-0.20, respectively). CONCLUSION: MSK-FI ≥ 3 and low SMI are associated with adverse postoperative outcomes in elderly patients undergoing colorectal cancer surgery. Implementing this practical tool in routine clinical practice, may help identify patients that would benefit from surgical prehabilitation and preoperative optimization to improve outcomes.

A KAP1 phosphorylation switch controls MyoD function during skeletal muscle differentiation.

The transcriptional activator MyoD serves as a master controller of myogenesis. Often in partnership with Mef2 (myocyte enhancer factor 2), MyoD binds to the promoters of hundreds of muscle genes in proliferating myoblasts yet activates these targets only upon receiving cues that launch differentiation. What regulates this off/on switch of MyoD function has been incompletely understood, although it is known to reflect the action of chromatin modifiers. Here, we identify KAP1 (KRAB [Krüppel-like associated box]-associated protein 1)/TRIM28 (tripartite motif protein 28) as a key regulator of MyoD function. In myoblasts, KAP1 is present with MyoD and Mef2 at many muscle genes, where it acts as a scaffold to recruit not only coactivators such as p300 and LSD1 but also corepressors such as G9a and HDAC1 (histone deacetylase 1), with promoter silencing as the net outcome. Upon differentiation, MSK1-mediated phosphorylation of KAP1 releases the corepressors from the scaffold, unleashing transcriptional activation by MyoD/Mef2 and their positive cofactors. Thus, our results reveal KAP1 as a previously unappreciated interpreter of cell signaling, which modulates the ability of MyoD to drive myogenesis.

Growth State-Dependent Activation of eNOS in Response to DHA: Involvement of p38 MAPK.

Our laboratory previously reported that docosahexaenoic acid (DHA) differentially activates p38 mitogen-activated protein kinase (MAPK) in growing and quiescent human endothelial cells, which represent the dysfunctional and healthy states in vivo, respectively. Since endothelial nitric oxide synthase (eNOS) activity differs between healthy and dysfunctional endothelial cells, and p38 MAPK reportedly regulates both the activity and expression of eNOS, we hypothesized that the beneficial actions of DHA on endothelial cells are due to eNOS activation by p38 MAPK. The contribution of mitogen- and stress-activated protein kinase (MSK), a p38 MAPK substrate, was also investigated. Growing and quiescent EA.hy926 cells, prepared on Matrigel®-coated plates, were incubated with inhibitors of p38MAPK or MSK before adding DHA. eNOS phosphorylation and levels were quantified by Western blotting. Treatment with 20 µM DHA activated eNOS in both growth states whereas 125 µM DHA suppressed eNOS activation in growing cells. Quiescent cells had higher basal levels of eNOS than growing cells, while 125 µM DHA decreased eNOS levels in both growth states. p38 MAPK inhibition enhanced eNOS activation in quiescent cells but suppressed it in growing cells. Interestingly, 125 µM DHA counteracted these effects of p38 MAPK inhibition in both growth states. MSK was required for eNOS activation in both growth states, but it only mediated eNOS activation by DHA in quiescent cells. MSK thus affects eNOS via a pathway independent of p38MAPK. Quiescent cells were also more resistant to the apoptosis-inducing effect of 125 µM DHA compared to growing cells. The growth state-dependent regulation of p38MAPK and eNOS by DHA provides novel insight into the molecular mechanisms by which DHA influences endothelial cell function.

Ultrashort Echo Time Magnetic Resonance Imaging Techniques: Met and Unmet Needs in Musculoskeletal Imaging.

This review article summarizes recent technical developments in ultrashort echo time (UTE) magnetic resonance imaging of musculoskeletal (MSK) tissues with short-T2 relaxation times. A series of contrast mechanisms are discussed for high-contrast morphological imaging of short-T2 MSK tissues including the osteochondral junction, menisci, ligaments, tendons, and bone. Quantitative UTE mapping of T1, T2*, T1ρ, adiabatic T1ρ, magnetization transfer ratio, MT modeling of macromolecular proton fraction, quantitative susceptibility mapping, and water content is also introduced. Met and unmet needs in MSK imaging are discussed. EVIDENCE LEVEL: 1 TECHNICAL EFFICACY: Stage 3.

Smaller hands and less experience are associated with greater ergonomic strain during endoscopic procedures.

INTRODUCTION: Up to 89% of physicians who routinely perform endoscopy experience some type of musculoskeletal pain. In this study, we sought to quantitatively analyze provider factors that influence ergonomic strain during live endoscopic procedures. METHODS: Surface electromyography (sEMG) was used to measure ergonomic strain on physicians while performing upper and lower endoscopies. EMG data were normalized to a maximal voluntary contraction (MVC) recording for each muscle group, yielding a %MVC value. Subgroup analyses were performed based on glove size, physician training level, specialty, and handedness. RESULTS: A total of 165 upper (n = 68) and lower (n = 97) endoscopies were recorded. Endoscopists with small hand sizes had significantly higher ergonomic strain in the left anterior and posterior forearm muscle compartments as compared to endoscopists with medium or large hands (%MVC L-anterior: small: 9.1 ± 1.1; medium: 6.4 ± 1.2; large: 5.9 ± 1.6; p < 0.001); (%MVC L-posterior: small: 12.0 ± 0.8; medium: 9.4 ± 1.3; large: 8.8 ± 1.4; p < 0.001). Additionally, upper body muscle groups had significantly higher ergonomic strain in endoscopists with less lifetime endoscopic experience (%MVC R-trapezius: expert: 8.4 ± 1.2; novice: 9.3 ± 1.2; p < 0.05); (%MVC R-deltoid: expert: 6.1 ± 1.4; novice: 8.5 ± 1.3; p < 0.001). There were no significant ergonomic differences between surgeons or gastroenterologists and no differences between right- and left-handed dominant individuals. CONCLUSIONS: Endoscopists with small hands experienced great ergonomic strain in their left forearm. Our data support the widely held belief that "one size does not fit all" and will hopefully spark change in the design of future endoscopes by device manufacturers. Our data also support that the experience level of the endoscopist contributed significantly to ergonomic performance, likely due to postural differences leading to decreased upper body strain. Therefore, it remains critically important to educate young proceduralists on strategies for ergonomic relief early in his or her endoscopic training program that can ameliorate ergonomic strain that accrues over the lifetime of a physician's career.

Daphnetin inhibits α-MSH-induced melanogenesis via PKA and ERK signaling pathways in B16F10 melanoma cells.

Daphnetin is a dehydroxylated derivative of coumarin isolated from Daphne species. However, the effect of daphnetin on melanogenesis has not been elucidated. This study aims to investigate the inhibitory effect of daphnetin on melanogenesis in α-melanocyte stimulating hormone (α-MSH)-treated B16F10 cells and its potential mechanism. Melanin content analysis and cellular tyrosinase activity assay showed that daphnetin inhibited melanin biosynthesis in α-MSH-treated B16F10 cells. Immunoblotting and qRT-PCR also indicated that daphnetin suppressed the expression of microphthalmia-associated transcription factor, a mastering transcription factor of melanogenesis and its downstream melanogenic enzymes including tyrosinase and tyrosinase-related proteins. Moreover, daphnetin downregulated the phosphorylation of PKA, ERK, MSK1, and CREB. Additionally, daphnetin inhibited melanin synthesis in UVB-irradiated HaCaT conditioned medium system suggesting that daphnetin has potential as an antipigmentation activity in a physiological skin condition. Our data propose that daphnetin inhibits melanogenesis via modulating both the PKA/CREB and the ERK/MSK1/CREB pathways.