Consensus-Based Guidelines for Management of First-Time Patellar Dislocation in Adolescents.

BACKGROUND: The management of first-time patellar dislocation remains variable, with limited evidence to support or compare different operative and nonoperative modalities. The primary aim was to establish consensus-based guidelines for different components of nonoperative treatment following a first-time patellar dislocation. The secondary aim was to develop guidelines related to management after failed nonoperative treatment. The tertiary aim was to establish consensus-based guidelines for the management of first-time patellar dislocation with a concomitant osteochondral fracture. METHODS: A 29-question, multiple-choice, case-based survey was developed by 20 members of the Patellofemoral Research Interest Group of the Pediatric Research in Sports Medicine Society. The survey consisted of questions related to demographic information, management of first-time patellar dislocation without an osteochondral fracture, and management of first-time patellar dislocation with a 2 cm osteochondral fracture. The survey underwent 2 rounds of iterations by Patellofemoral Research Interest Group members and the final survey was administered to Pediatric Research in Sports Medicine members, using REDCap. Consensus-based guidelines were generated when more than 66% of respondents chose the same answer. RESULTS: Seventy-nine of 157 (50%) eligible members responded. Sixty-one were orthopaedic surgeons and 18 were primary sports medicine physicians. Eleven consensus-based guidelines were generated based on survey responses. Those that met the criteria for consensus included initial knee radiographs (99% consensus), nonoperative treatment for first-time patellar dislocation without an osteochondral fracture (99%), physical therapy starting within the first month postinjury (99%), with return to sport after 2 to 4 months (68%) with a brace (75%) and further follow-up as needed (75%). Surgical treatment was recommended if there were patellar subluxation episodes after 6 months of nonoperative treatment (84%). Patellar stabilization should be considered for a first-time dislocation with an osteochondral fracture (81.5%). CONCLUSION: Consensus-based guidelines offer recommendations for the management of first-time patellar dislocation with or without an osteochondral fracture. Several changing trends and areas of disagreement were noted in clinical practice. CLINICAL RELEVANCE: In the absence of high-level evidence, consensus-based guidelines may aid in clinical decision-making when treating patients following a first-time patellar dislocation. These guidelines highlight the evolving trends in clinical practice for the management of first-time patellar dislocation. Areas not reaching consensus serve as topics for future research.

Translation, cross-cultural adaptation and reliability of the International Knee Documentation Committee (IKDC) subjective knee form and the tampa scale for kinesiophobia (TSK) into Hebrew.

INTRODUCTION: The International Knee Documentation Committee-Subjective Form (IKDC-SF) is one of the most used measures for evaluating the quality of life among people experiencing knee pain but is not yet available in Hebrew. Similarly, the Tampa Scale for Kinesiophobia (TSK), used to evaluate fear of movement, is not available in Hebrew. This study aimed to determine the reliability and construct validity of the Hebrew IKDC-SF and TSK among people experiencing chronic knee pain. MATERIALS AND METHODS: Translation and cultural adaptation of the IKDC-SF and TSK questionnaires, followed by test-retest reliability within a two-week interval. We report on internal consistency, construct validity, and the psychometric properties of both questionnaires. RESULTS: Both questionnaires showed high internal consistency (Cronbach's α = 0.85 and 0.89, respectively) and test-retest reliability, expressed by the Intra-Class Correlation Coefficient (ICC = 0.89 and 0.80 respectively). The standard error of measurement, group smallest real difference and minimal detectable change for the IKDC-SF were 4.66, 9.13, and 12.91 points, and 3.64, 7.13, and 10.08 points for the TSK, respectively. CONCLUSION: We demonstrated that the Hebrew version of the IKDC-SF and TSK is reliable and valid for assessing QoL, function, and kinesiophobia among people experiencing chronic knee pain.

3D-printed Cutting Guides for Lower Limb Deformity Correction in the Young Population.

BACKGROUND: Three-dimensional (3D) virtual surgical planning technology has advanced applications in the correction of deformities of long bones by enabling the production of 3D stereolithographic models, patient-specific instruments and surgical-guiding templates. Herein, we describe the implementation of this technology in young patients who required a corrective osteotomy for a complex 3-plane (oblique plane) lower-limb deformity. PATIENTS AND METHODS: A total of 17 patients (9 males, average age 14.7 y) participated in this retrospective study. As part of preoperative planning, the patients' computerized tomographic images were imported into a post-processing software, and virtual 3D models were created by a segmentation process. Femoral and tibial models and cutting guides with locking points were designed according to the deformity correction plan. They were used for both planning and as intraoperative guides. Clinical parameters, such as blood loss and operative time were compared with a traditional surgical approach group. RESULTS: All osteotomies in the 3D group were executed with the use intraoperative customized cutting guides which matched the preoperative planning simulation and allowed easy fixation with prechosen plates. Surgical time was 101±6.2 minutes for the 3D group and 126.4±16.1 minutes for the control group. The respective intraoperative hemoglobin blood loss was 2.1±0.2 and 2.5+0.3 g/dL.Clinical and radiographic follow-up findings showed highly satisfactory alignment of the treated extremities in all 3D intervention cases, with an average time-to-bone union (excluding 2 neurofibromatosis 1 patients) of 10.3 weeks (range 6 to 20 wk). CONCLUSION: The use of 3D-printed models and patient-specific cutting guides with locking points improves the clinical outcomes of osteotomies in young patients with complex bone deformities of the lower limbs. LEVEL OF EVIDENCE: Level III.

Surgical Treatment of Congenital and Obligatory Dislocation of the Patella in Children.

BACKGROUND: Congenital (fixed) dislocations and obligatory (habitual) patellar dislocations represent a complex clinical and surgical challenge. Numerous treatment options, offering different perspectives, and surgical solutions are reported in the literature.We implemented the surgical technique principles, originally described by Stanisavljevic, for congenital (fixed) and obligatory (habitual) patellar dislocations, with slight modifications. METHODS: We retrospectively evaluated the results of group of 12 patients (15 knees), operated between the years 2002 and 2013. The procedure includes extensive subperiosteal quadriceps realignment and soft tissue medial plication, followed by distal realignment through patellar tendon splitting. The outcome measures were patellar stability, knee range of motion, Pedi-IKDC knee function score, and the PODCI global function score. RESULTS: The study group included 12 patients, 9 females and 3 males (15 knees) whose mean age was 5 years 2 months at diagnosis and 7 years 5 months at surgery. Nine patients had an underlying diagnosed genetic background [Down syndrome (n=6), Larsen syndrome (n=2), nail-patella syndrome (n=1)]. The mean follow-up was 46.2 months. Eleven patients, gained stable patella with no recurrence of dislocation. Postoperative knee active extension was improved significantly (P<0.0001) for all patients. The average postoperative Pedi-IKDC and PODCI scores were significantly higher (P<0.001) among the idiopathic group. CONCLUSIONS: These results suggest that the Stanisavljevic procedure principles with modifications, provides an efficient method for treatment of fixed and obligatory patellar dislocation. In our opinion, young age at surgery played an important role in the surgical outcome. LEVEL OF EVIDENCE: Level IV-therapeutic.

Defective planar cell polarity in polycystic kidney disease.

Morphogenesis involves coordinated proliferation, differentiation and spatial distribution of cells. We show that lengthening of renal tubules is associated with mitotic orientation of cells along the tubule axis, demonstrating intrinsic planar cell polarization, and we demonstrate that mitotic orientations are significantly distorted in rodent polycystic kidney models. These results suggest that oriented cell division dictates the maintenance of constant tubule diameter during tubular lengthening and that defects in this process trigger renal tubular enlargement and cyst formation.

François Gros: from antibiotics to messenger RNA.

François Gros was a prominent French Molecular Biologist who made a major contribution to the discovery of messenger RNA in 1961. He pursued outstanding research on bacterial mRNA and its translation into proteins followed by pioneering work on muscle differentiation. I was lucky to be among his graduate students and owe much of my success in science to him. In this short text I will describe how the initial post-war studies of François guided him to discover the existence of short-lived RNA in bacteria, the messenger RNA containing the information for protein synthesis. I will also recount the influence he had on his students and their carrier in science.

François Gros était un éminent biologiste moléculaire français qui a contribué de manière décisive à la découverte de l'ARN messager en 1961. Il a poursuivi des recherches remarquables sur l'ARNm bactérien et sa traduction en protéines, suivies de travaux pionniers sur la différenciation musculaire. J'ai eu la chance d'être l'un de ses étudiants de thèse d'État et je lui dois une grande partie de ma réussite scientifique. Dans ce court texte, je décrirai comment les études initiales d'après-guerre de François l'ont amené à découvrir l'existence d'un ARN à courte durée de vie dans les bactéries, l'ARN messager, qui contient l'information nécessaire à la synthèse des protéines. Je raconterai également l'influence qu'il a eue sur ses étudiants et leur carrière scientifique.

SWI/SNF chromatin remodeler complex within the reward pathway is required for behavioral adaptations to stress.

Enduring behavioral changes upon stress exposure involve changes in gene expression sustained by epigenetic modifications in brain circuits, including the mesocorticolimbic pathway. Brahma (BRM) and Brahma Related Gene 1 (BRG1) are ATPase subunits of the SWI/SNF complexes involved in chromatin remodeling, a process essential to enduring plastic changes in gene expression. Here, we show that in mice, social defeat induces changes in BRG1 nuclear distribution. The inactivation of the Brg1/Smarca4 gene within dopamine-innervated regions or the constitutive inactivation of the Brm/Smarca2 gene leads to resilience to repeated social defeat and decreases the behavioral responses to cocaine without impacting midbrain dopamine neurons activity. Within striatal medium spiny neurons, Brg1 gene inactivation reduces the expression of stress- and cocaine-induced immediate early genes, increases levels of heterochromatin and at a global scale decreases chromatin accessibility. Altogether these data demonstrate the pivotal function of SWI/SNF complexes in behavioral and transcriptional adaptations to salient environmental challenges.

Patellar Instability in Young Athletes.

This article summarizes the latest research related to pediatric patellar instability. The epidemiology, patterns of patellar instability, and underlying pathoanatomy are unique in children and adolescents. Information related to the natural history and predictive factors of patellar instability in young patients would allow for better patient counseling and management decisions. The components of nonoperative treatment for first patellar dislocation are outlined. Physeal-respecting surgical techniques, including medial patellofemoral ligament reconstruction in skeletally immature patients, are discussed. The indications and outcomes for quadricepsplasty to address more complex instability patterns are presented. Evaluation and management strategies for specific anatomic risk factors is provided.

Involvement of SMARCA2/BRM in the SWI/SNF chromatin-remodeling complex in schizophrenia.

Chromatin remodeling may play a role in the neurobiology of schizophrenia and the process, therefore, may be considered as a therapeutic target. The SMARCA2 gene encodes BRM in the SWI/SNF chromatin-remodeling complex, and associations of single nucleotide polymorphisms (SNPs) to schizophrenia were found in two linkage disequilibrium blocks in the SMARCA2 gene after screening of 11 883 SNPs (rs2296212; overall allelic P = 5.8 x 10(-5)) and subsequent screening of 22 genes involved in chromatin remodeling (rs3793490; overall allelic P = 2.0 x 10(-6)) in a Japanese population. A risk allele of a missense polymorphism (rs2296212) induced a lower nuclear localization efficiency of BRM, and risk alleles of intronic polymorphisms (rs3763627 and rs3793490) were associated with low SMARCA2 expression levels in the postmortem prefrontal cortex. A significant correlation in the fold changes of gene expression from schizophrenic prefrontal cortex (from the Stanley Medical Research Institute online genomics database) was seen with suppression of SMARCA2 in transfected human cells by specific siRNA, and of orthologous genes in the prefrontal cortex of Smarca2 knockout mice. Smarca2 knockout mice showed impaired social interaction and prepulse inhibition. Psychotogenic drugs lowered Smarca2 expression while antipsychotic drugs increased it in the mouse brain. These findings support the existence of a role for BRM in the pathophysiology of schizophrenia.

Human papillomavirus type 8 E2 protein unravels JunB/Fra-1 as an activator of the beta4-integrin gene in human keratinocytes.

The papillomavirus life cycle parallels keratinocyte differentiation in stratifying epithelia. We have previously shown that the human papillomavirus type 8 (HPV8) E2 protein downregulates beta4-integrin expression in normal human keratinocytes, which may trigger subsequent differentiation steps. Here, we demonstrate that the DNA binding domain of HPV8 E2 is sufficient to displace a cellular factor from the beta4-integrin promoter. We identified the E2-displaceable factor as activator protein 1 (AP-1), a heteromeric transcription factor with differentiation-specific expression in the epithelium. beta4-Integrin-positive epithelial cells displayed strong AP-1 binding activity. Both AP-1 binding activity and beta4-integrin expression were coregulated during keratinocyte differentiation suggesting the involvement of AP-1 in beta4-integrin expression. In normal human keratinocytes the AP-1 complex was composed of JunB and Fra-1 subunits. Chromatin immunoprecipitation assays confirmed that JunB/Fra-1 proteins interact in vivo with the beta4-integrin promoter and that JunB/Fra-1 promoter occupancy is reduced during keratinocyte differentiation as well as in HPV8 E2 positive keratinocytes. Ectopic expression of the tethered JunB/Fra-1 heterodimer in normal human keratinocytes activated the beta4-integrin promoter, while coexpression of HPV8 E2 reverted the JunB/Fra-1 effect. In summary, we identified a novel mechanism of human beta4-integrin regulation that is specifically targeted by the HPV8 E2 protein mimicking transcriptional conditions of differentiation. This may explain the early steps of how HPV8 commits its host cells to the differentiation process required for the viral life cycle.

The transcription factor JunD mediates transforming growth factor {beta}-induced fibroblast activation and fibrosis in systemic sclerosis.

OBJECTIVES: Transforming growth factor ß (TGFß) has been identified as a key player in fibrotic diseases. However, the molecular mechanisms by which TGFß activates fibroblasts are incompletely understood. Here, the role of JunD, a member of the activator protein 1 (AP-1) family of transcription factors, as a downstream mediator of TGFß signalling in systemic sclerosis (SSc), was investigated. METHODS: The expression of JunD was analysed by real-time PCR, immunofluorescence, western blotting and immunohistochemistry. The canonical Smad pathway was specifically targeted by small interfering (si)RNA. The expression of extracellular matrix proteins in JunD deficient (JunD(-/-)) fibroblasts was analysed by real-time PCR and hydroxyproline assays. The mouse model of bleomycin-induced dermal fibrosis was used to assess the role of JunD in experimental fibrosis. RESULTS: JunD was overexpressed in SSc skin and in cultured fibroblasts in a TGFß dependent manner. The expression of JunD colocalised with pSmad 3 in fibrotic skin and silencing of Smad 3 or Smad 4 by siRNA prevented the induction of JunD by TGFß. JunD(-/-) fibroblasts were less responsive to TGFß and released less collagen upon stimulation with TGFß. Moreover, JunD(-/-) mice were protected from bleomycin-induced fibrosis with reduced dermal thickening, decreased myofibroblast counts and lower collagen content of lesional skin. CONCLUSIONS: These data demonstrate that JunD is overexpressed in SSc and that JunD is a mediator of the profibrotic effects of TGFß. Considering that inhibitors of AP-1 signalling have recently been developed and are available for clinical trials in SSc, these findings may have translational implications.

The human SWI/SNF subunit Brm is a regulator of alternative splicing.

The SWI/SNF (mating-type switch/sucrose nonfermenting) complex involved in chromatin remodeling on promoters has also been detected on the coding region of genes. Here we show that SWI/SNF can function as a regulator of alternative splicing. We found that the catalytic subunit Brm favors inclusion of variant exons in the mRNA of several genes, including E-cadherin, BIM, cyclin D1 and CD44. Consistent with this, Brm associates with several components of the spliceosome and with Sam68, an ERK-activated enhancer of variant exon inclusion. Examination of the CD44 gene revealed that Brm induced accumulation of RNA polymerase II (RNAPII) with a modified CTD phosphorylation pattern on regions encoding variant exons. Altogether, our data suggest that on genes regulated by SWI/SNF, Brm contributes to the crosstalk between transcription and RNA processing by decreasing RNAPII elongation rate and facilitating recruitment of the splicing machinery to variant exons with suboptimal splice sites.

Mitochondrial dysfunction contributes to impaired insulin secretion in INS-1 cells with dominant-negative mutations of HNF-1alpha and in HNF-1alpha-deficient islets.

Maturity Onset Diabetes of the Young-type 3 (MODY-3) has been linked to mutations in the transcription factor hepatic nuclear factor (HNF)-1alpha, resulting in deficiency in glucose-stimulated insulin secretion. In INS-1 cells overexpressing doxycycline-inducible HNF-1alpha dominant-negative (DN-) gene mutations, and islets from Hnf-1alpha knock-out mice, insulin secretion was impaired in response to glucose (15 mm) and other nutrient secretagogues. Decreased rates of insulin secretion in response to glutamine plus leucine and to methyl pyruvate, but not potassium depolarization, indicate defects specific to mitochondrial metabolism. To identify the biochemical mechanisms responsible for impaired insulin secretion, we used (31)P NMR measured mitochondrial ATP synthesis (distinct from glycolytic ATP synthesis) together with oxygen consumption measurements to determine the efficiency of mitochondrial oxidative phosphorylation. Mitochondrial uncoupling was significantly higher in DN-HNF-1alpha cells, such that rates of ATP synthesis were decreased by approximately one-half in response to the secretagogues glucose, glutamine plus leucine, or pyruvate. In addition to closure of the ATP-sensitive K(+) channels with mitochondrial ATP synthesis, mitochondrial production of second messengers through increased anaplerotic flux has been shown to be critical for coupling metabolism to insulin secretion. (13)C-Isotopomer analysis and tandem mass spectrometry measurement of Krebs cycle intermediates revealed a negative impact of DN-HNF-1alpha and Hnf-1alpha knock-out on mitochondrial second messenger production with glucose but not amino acids. Taken together, these results indicate that, in addition to reduced glycolytic flux, uncoupling of mitochondrial oxidative phosphorylation contributes to impaired nutrient-stimulated insulin secretion with either mutations or loss of HNF-1alpha.

Increased DNA damage sensitivity and apoptosis in cells lacking the Snf5/Ini1 subunit of the SWI/SNF chromatin remodeling complex.

The gene encoding the SNF5/Ini1 core subunit of the SWI/SNF chromatin remodeling complex is a tumor suppressor in humans and mice, with an essential role in early embryonic development. To investigate further the function of this gene, we have generated a Cre/lox-conditional mouse line. We demonstrate that Snf5 deletion in primary fibroblasts impairs cell proliferation and survival without the expected derepression of most retinoblastoma protein-controlled, E2F-responsive genes. Furthermore, Snf5-deficient cells are hypersensitive to genotoxic stress, display increased aberrant mitotic features, and accumulate phosphorylated p53, leading to elevated expression of a specific subset of p53 target genes, suggesting a role for Snf5 in the DNA damage response. p53 inactivation does not rescue the proliferation defect caused by Snf5 deficiency but reduces apoptosis and strongly accelerates tumor formation in Snf5-heterozygous mice.

Dimer composition and promoter context contribute to functional cooperation between AP-1 and NFAT.

The transcription factors activator protein 1 (AP-1) and nuclear factor of activated T-cells (NFAT) cooperate to induce the expression of cytokines during the immune response. While much is known about the signaling pathways and physical interactions between NFAT and AP-1 dimers following lymphocyte activation, few studies have addressed the role of AP-1 composition in modulating NFAT:AP-1-dependent transcription. We examined the function of specific AP-1 complexes using "tethered" AP-1 dimers with defined composition. We found that NFAT can functionally cooperate with all AP-1 dimers tested. Noteworthy, Jun approximately Jun-containing dimers, which are relatively inactive when tested on an AP-1-dependent promoter, are effective co-activators of an NFAT:AP-1-dependent promoter. Interestingly, specific AP-1 dimer combinations behave differently when tested on interleukin 2 (IL2) and interleukin 4 (IL4) gene regulatory regions. Moreover, the requirement for NFAT to activate each of the promoters is different. Our results suggest that higher NFAT levels are necessary to activate the IL4 promoter. Hence changes in AP-1 composition and the level of participating NFAT proteins can differentially influence cytokine gene expression, resulting in biological consequences for the modulation and dynamics of the immune response.

SWI/SNF chromatin remodeling and cancer.

The SWI/SNF complex contributes to the regulation of gene expression by altering the chromatin structure. Depending on the context, it can be involved in either transcriptional activation or repression. Growing genetic and molecular evidence indicate that subunits of the SWI/SNF complex act as tumor suppressors in human and mice. Results from biochemical and transfection studies suggest also that SWI/SNF participates either in the inhibition or activation of several oncogenes and tumor suppressor genes and/or control their transcriptional activity. These activities provide molecular insight into the mechanism underlying SWI/SNF function in tumor suppression.

JunD protects against chronic kidney disease by regulating paracrine mitogens.

The AP-1 transcription factor, composed of Jun and Fos proteins, plays a crucial role in the fine tuning of cell proliferation. We showed previously that AP-1 complexes are activated during the proliferative response that parallels the development of renal lesions after nephron reduction, but little is known about the specific role of individual Jun/Fos components in the deterioration process. Here we used JunD knockout (JunD-/-) mice and an experimental model of chronic renal injury (75% nephron reduction) to explore the role of JunD. Nephron reduction resulted in an initial compensatory growth phase that did not require JunD. JunD, however, was essential to inhibit a second wave of cell proliferation and to halt the development of severe glomerular sclerosis, tubular dilation, and interstitial fibrosis. We show that the effects of junD inactivation are not cell autonomous and involve upregulation of the paracrine mitogen, TGF-alpha. Expression of a transgene (REM) encoding a dominant negative isoform of the EGFR, the receptor for TGF-alpha, prevented the second wave of cell proliferation and the development of renal lesions in bitransgenic JunD-/-/REM mice. We propose that JunD is part of a regulatory network that controls proliferation to prevent pathological progression in chronic renal diseases.

Role of heterodimerization of c-Fos and Fra1 proteins in osteoclast differentiation.

Bone resorbing osteoclasts are specialized macrophages that cannot differentiate in the absence of c-Fos, a member of the dimeric transcription factor AP-1 (activator protein-1). However, osteoclast differentiation in the absence of c-Fos can be rescued in vitro and in vivo by Fra1, a Fos-like protein and transcriptional target of c-Fos. To enable AP-1 proteins binding to DNA, c-Fos or Fra1 must heterodimerize with a partner such as c-Jun, JunB and JunD. In this study, we investigated the dimerization partners of c-Fos and Fra1 required for osteoclast differentiation using synthetic "single-chain" AP-1 dimers in which c-Fos or Fra1 is tethered via a linker to Jun proteins. When c-Fos was analyzed in combination with any Jun protein, including a c-Jun mutant lacking major phosphorylation sites for c-Jun amino-terminal kinase (JNK), osteoclasts were efficiently formed from c-Fos-deficient hematopoietic precursors. However, Fra1 in combination with any Jun protein could not rescue osteoclastogenesis. The ability to rescue was compared to transcriptional activity measured in transient transfection assays using promoters driven by consensus AP-1 sites or a composite AP-1/NFAT binding site. These data show that a single Jun/c-Fos dimer is sufficient for osteoclast differentiation, likely due to its transactivation ability for a broader range of promoters, in particular consensus AP-1 sites. We propose that Fra1 together with a dimerization partner different from Jun proteins can rescue osteoclast differentiation in c-Fos-deficient precursors.

HMG-I(Y) and the CBP/p300 coactivator are essential for human papillomavirus type 18 enhanceosome transcriptional activity.

A strong epithelial specific enhancer drives transcription of the human papillomavirus type 18 (HPV18) oncogenes. Its activity depends on the formation of a higher-order nucleoprotein complex (enhanceosome) involving the sequence-specific JunB/Fra2 transcription factor and the HMG-I(Y) architectural protein. Here we show that proteins from HeLa cell nuclear extract cover almost all of the HPV18 enhancer sequences and that it contains seven binding sites for the purified HMG-I(Y) protein, providing evidence for a tight nucleoprotein structure. Binding of HMG-I(Y) and the AP1 heterodimer from HeLa nuclear extract to overlapping sites of the core enhanceosome is cooperative. The integrity of this specific HMG-I(Y) binding site is as essential as the AP1 binding site for the enhancer function, indicating the fundamental role played by this architectural protein. We demonstrate that the CBP/p300 coactivator is recruited by the HPV18 enhanceosome and that it is limiting for transcriptional activation, since it is sequestered by the adenovirus E1A protein and by the JunB/Fra2 positive factor in excess. We show the involvement of JunB and p300 in vivo in the HPV18 transcription by chromatin immunoprecipitation of HPV18 sequences in HeLa cells.