Spt6 Association with RNA Polymerase II Directs mRNA Turnover During Transcription.

Spt6 is an essential histone chaperone that mediates nucleosome reassembly during gene transcription. Spt6 also associates with RNA polymerase II (RNAPII) via a tandem Src2 homology domain. However, the significance of Spt6-RNAPII interaction is not well understood. Here, we show that Spt6 recruitment to genes and the nucleosome reassembly functions of Spt6 can still occur in the absence of its association with RNAPII. Surprisingly, we found that Spt6-RNAPII association is required for efficient recruitment of the Ccr4-Not de-adenylation complex to transcribed genes for essential degradation of a range of mRNAs, including mRNAs required for cell-cycle progression. These findings reveal an unexpected control mechanism for mRNA turnover during transcription facilitated by a histone chaperone.

Extensor tendon transfer for fracture-related extensor pollicis longus rupture: Long-term outcome case series.

BACKGROUND: Spontaneous rupture of the extensor pollicis longus (EPL) tendon following both nonoperative and operative treatment of distal radius fractures has been well described. PURPOSE: The purpose of this study was to assess long-term outcomes of extensor indicis proprius to EPL tendon transfers for patients following distal radius fracture and EPL tendon repair. STUDY DESIGN: Retrospective case series focusing on long-term clinical outcomes. METHODS: A retrospective review was conducted for patients who sustained a distal radius fracture and subsequently underwent extensor tendon transfer from 2005-2015 at a private practice center. Outcome measures including index finger (IF) metacarpophalangeal (MCP) and thumb interphalangeal (IP) active range of motion (ROM), digital extension against resistance, subjective complaints, and QuickDASH scores were recorded at final follow-up. RESULTS: Seven patients were included in the study. There were six females and one male subject, mean age of 54 ± 13 years at injury of EPL, and 5/7 involved the left upper extremity. For isolated function, 7/7 (100%) patients had isolated, active IF MCP extension, 6/7 (86%) could extend IF MCP and thumb IP against resistance. Mean IF MCP extension was 1° ± 2°, mean IF MCP flexion was 89° ± 2°, mean thumb IP extension was -5° ± 4°, and mean thumb IP flexion was 67° ± 15°. Mean QuickDASH score was 16 ± 14. CONCLUSIONS: This series shows good long-term functional and patient reported outcomes in patients following extensor indicis proprius to EPL tendon transfers at a single center.

Deglutarylation of glutaryl-CoA dehydrogenase by deacylating enzyme SIRT5 promotes lysine oxidation in mice.

A wide range of protein acyl modifications has been identified on enzymes across various metabolic processes; however, the impact of these modifications remains poorly understood. Protein glutarylation is a recently identified modification that can be nonenzymatically driven by glutaryl-CoA. In mammalian systems, this unique metabolite is only produced in the lysine and tryptophan oxidative pathways. To better understand the biology of protein glutarylation, we studied the relationship between enzymes within the lysine/tryptophan catabolic pathways, protein glutarylation, and regulation by the deglutarylating enzyme sirtuin 5 (SIRT5). Here, we identify glutarylation on the lysine oxidation pathway enzyme glutaryl-CoA dehydrogenase (GCDH) and show increased GCDH glutarylation when glutaryl-CoA production is stimulated by lysine catabolism. Our data reveal that glutarylation of GCDH impacts its function, ultimately decreasing lysine oxidation. We also demonstrate the ability of SIRT5 to deglutarylate GCDH, restoring its enzymatic activity. Finally, metabolomic and bioinformatic analyses indicate an expanded role for SIRT5 in regulating amino acid metabolism. Together, these data support a feedback loop model within the lysine/tryptophan oxidation pathway in which glutaryl-CoA is produced, in turn inhibiting GCDH function via glutaryl modification of GCDH lysine residues and can be relieved by SIRT5 deacylation activity.

Rate of Complications After Capitellum Fracture Fixation: A Systematic Review and Meta-Analysis.

PURPOSE: This systematic review aimed to determine the incidence of complications following surgical fixation of an acute capitellum fracture. We secondarily aimed to compare the complication rate between anterior-to-posterior (A-P) versus posterior-to-anterior (P-A) screw insertion. METHODS: PubMed, EMBASE, and Scopus were searched to identify studies on surgical fixation of capitellum fractures in skeletally mature patients. The main outcome was the rate of complication after fracture fixation. Subgroup analysis was performed to assess the impact of the fixation technique on the outcomes after surgery. An inverse variance method using random or fixed effects models was used to perform a meta-analysis based on the degree of heterogeneity between studies. Study heterogeneity was evaluated using Q statistics to calculate the I2 index. RESULTS: We included 42 studies in the final analysis. The most reported complications after surgical fixation of capitellum fractures included elbow pain (21%), radiocapitellar arthritis (19%), hardware removal (17%), and heterotopic ossification (13%). When groups were stratified based on the direction of screw insertion, the mean rate of avascular necrosis was higher in the P-A direction (29% vs 11%). In comparison, the rate of revision fixation (2.9% vs 6.7%) and heterotopic ossification (7.3% vs 22%) were higher in the A-P direction. Transient posterior interosseous nerve palsy was reported in four patients in four studies, of whom three patients had A-P screw fixation. CONCLUSION: Fixation of a displaced capitellum fracture is recommended when possible. However, patients should be counseled about the potential risk of complications and chances of undergoing an unplanned surgery. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.

A temperature-sensitive FERONIA mutant allele that alters root hair growth.

In plants, root hairs undergo a highly polarized form of cell expansion called tip-growth, in which cell wall deposition is restricted to the root hair apex. In order to identify essential cellular components that might have been missed in earlier genetic screens, we identified conditional temperature-sensitive (ts) root hair mutants by ethyl methanesulfonate mutagenesis in Arabidopsis thaliana. Here, we describe one of these mutants, feronia-temperature sensitive (fer-ts). Mutant fer-ts seedlings were unaffected at normal temperatures (20°C), but failed to form root hairs at elevated temperatures (30°C). Map based-cloning and whole-genome sequencing revealed that fer-ts resulted from a G41S substitution in the extracellular domain of FERONIA (FER). A functional fluorescent fusion of FER containing the fer-ts mutation localized to plasma membranes, but was subject to enhanced protein turnover at elevated temperatures. While tip-growth was rapidly inhibited by addition of rapid alkalinization factor 1 (RALF1) peptides in both wild-type and fer-ts mutants at normal temperatures, root elongation of fer-ts seedlings was resistant to added RALF1 peptide at elevated temperatures. Additionally, at elevated temperatures fer-ts seedlings displayed altered reactive oxygen species (ROS) accumulation upon auxin treatment and phenocopied constitutive fer mutant responses to a variety of plant hormone treatments. Molecular modeling and sequence comparison with other Catharanthus roseus receptor-like kinase 1L (CrRLK1L) receptor family members revealed that the mutated glycine in fer-ts is highly conserved, but is not located within the recently characterized RALF23 and LORELI-LIKE-GLYCOPROTEIN 2 binding domains, perhaps suggesting that fer-ts phenotypes may not be directly due to loss of binding to RALF1 peptides.

Type I interferon is required for T helper (Th) 2 induction by dendritic cells.

Type 2 inflammation is a defining feature of infection with parasitic worms (helminths), as well as being responsible for widespread suffering in allergies. However, the precise mechanisms involved in T helper (Th) 2 polarization by dendritic cells (DCs) are currently unclear. We have identified a previously unrecognized role for type I IFN (IFN-I) in enabling this process. An IFN-I signature was evident in DCs responding to the helminth Schistosoma mansoni or the allergen house dust mite (HDM). Further, IFN-I signaling was required for optimal DC phenotypic activation in response to helminth antigen (Ag), and efficient migration to, and localization with, T cells in the draining lymph node (dLN). Importantly, DCs generated from Ifnar1-/- mice were incapable of initiating Th2 responses in vivo These data demonstrate for the first time that the influence of IFN-I is not limited to antiviral or bacterial settings but also has a central role to play in DC initiation of Th2 responses.

Adoption of low tidal volume ventilation in the emergency department: A quality improvement intervention.

BACKGROUND: Ventilator tidal volumes of >8 mL/kg of predicted body weight (PBW) may increase the risk of lung injury. We sought to evaluate the impact of a quality improvement intervention among intubated Emergency Department (ED) patients to protocolize the prescription of low tidal volume ventilation. METHODS: In this before-and-after study, the average tidal volume delivered to ED patients receiving volume assist-control ventilation was compared before (2007-2014) and after (2015-2016) implementation of a ventilator initiation protocol (the quality improvement intervention). The intervention emphasized 1) measurement of the patient's height to calculate PBW and therefore tailor the tidal volume to estimated lung size (<8 mL/kg PBW), and 2) focused education and reference materials for ED physicians and respiratory therapists. RESULTS: Among ventilated ED patients meeting inclusion criteria in the before (N = 2185) and after (N = 774) cohorts, the mean (±SD) tidal volume decreased from 9.0 ±â€¯1.4 mL/kg to 7.2 ±â€¯0.9 mL/kg PBW following the intervention (absolute difference 1.8 mL/kg, 95% confidence interval 1.7 to 1.9 mL/kg, p < 0.001). The proportion of patients receiving low tidal volume ventilation increased after the intervention (72%), as compared to before (23%). Low tidal volume ventilation continued to be utilized at 24 h after ICU admission in patients who remained intubated in the cohort following the intervention (mean tidal volume 7.3 mL/kg PBW). CONCLUSIONS: Pairing a ventilator initiation protocol with focused education and resources for emergency physicians and respiratory therapists was associated with a significant reduction in tidal volume delivered to ED patients.

Set2 methyltransferase facilitates cell cycle progression by maintaining transcriptional fidelity.

Methylation of histone H3 lysine 36 (H3K36me) by yeast Set2 is critical for the maintenance of chromatin structure and transcriptional fidelity. However, we do not know the full range of Set2/H3K36me functions or the scope of mechanisms that regulate Set2-dependent H3K36 methylation. Here, we show that the APC/CCDC20 complex regulates Set2 protein abundance during the cell cycle. Significantly, absence of Set2-mediated H3K36me causes a loss of cell cycle control and pronounced defects in the transcriptional fidelity of cell cycle regulatory genes, a class of genes that are generally long, hence highly dependent on Set2/H3K36me for their transcriptional fidelity. Because APC/C also controls human SETD2, and SETD2 likewise regulates cell cycle progression, our data imply an evolutionarily conserved cell cycle function for Set2/SETD2 that may explain why recurrent mutations of SETD2 contribute to human disease.

Collection of Common Knee Patient-reported Outcome Instruments by Automated Mobile Phone Text Messaging in Pediatric Sports Medicine.

BACKGROUND: Patient-reported outcome (PRO) instruments measure health status in a variety of domains. With the proliferation of mobile phones, delivering PROs across patient-friendly platforms (eg, apps, text messaging) may increase completion rates, particularly among children. The purpose of this study was to validate the collection of common knee PROs in sports medicine with text messaging by correlating text-messaging responses with paper delivery in adolescents. METHODS: Patients presenting to a hospital-based pediatric orthopaedic sports medicine clinic with a knee injury were enrolled prospectively. Paper versions of the Pediatric International Knee Documentation Committee (Pedi-IKDC) Subjective Knee Evaluation Form and the Pediatric Functional Activity Brief Scale (Pedi-Fab Scale) were completed during initial clinic visits. Over the next 72 hours, patients completed the text message delivery of the Pedi-IKDC and Pedi-Fab Scale. Correlations between paper and text message delivery of the 2 PROs were assessed. RESULTS: Ninety-one patients (mean age: 16.0±2.0 y; 48% females) enrolled in the text-messaging study, with 55 (60.4%) completing the Pedi-Fab Scale, 48 (52.7%) completing the Pedi-IKDC, and 39 (42.9%) completing both PROs. The intraclass correlation coefficient between the paper and mobile phone delivery of the Pedi-Fab Scale was 0.95 (P<0.001; 95% confidence interval, 0.91-0.97). The intraclass correlation coefficient between the paper and mobile phone delivery of the Pedi-IKDC was 0.96 (P<0.001; 95% confidence interval, 0.93-0.98). Average Pedi-Fab scores on paper (M=12.7) and mobile phone (M=12.3) were not significantly different (P=0.52). Similarly, average Pedi-IKDC scores on paper (M=68.8) and mobile phone (M=67.7) were not significantly different (P=0.41). Average completion time for the text delivered Pedi-Fab and Pedi-IKDC were 102±224 and 159±155 minutes, respectively. High school enrollment (P=0.025), female sex (P=0.036), and race (P=0.002) were significantly associated with text completion of Pedi-IKDC. CONCLUSIONS: Text message delivery using mobile phones permits valid assessment of Pedi-IKDC and Pedi-Fab scores in adolescents. Questionnaire delivery by automated text messaging allows asynchronous response and may increase compliance and reduce the labor cost of collecting PROs. LEVEL OF EVIDENCE: Level III-prospective cohort study.

Serial Casting in Neuromuscular and Syndromic Early-onset Scoliosis (EOS) Can Delay Surgery Over 2 Years.

BACKGROUND: The primary goal in managing early-onset scoliosis (EOS) is delaying/preventing surgical intervention while allowing improved spinal growth and chest wall and lung development to improve life expectancy. The effectiveness of serial casting for patients with neuromuscular and syndromic EOS is unclear. METHODS: Patients from 2 multicenter registries who underwent serial casting for nonidiopathic scoliosis (NIS) were reviewed retrospectively. Comparisons were made between precasting and postcasting major and compensatory curves and spine height. The need for surgical intervention and any treatment complications were documented. Risk factors for major curve progression from baseline to casting cessation were evaluated via univariate analysis. RESULTS: Forty-four patients (23 females; 21 males) with NIS (26 syndromic, 18 neuromuscular) and a mean age of 3.2 years at baseline were included. Mean follow-up and casting duration was 3.9 and 2.0 years, respectively. There were no statistically significant differences between mean precasting and postcasting major curve (55 vs. 60 degrees; P=0.348), minor curve (31 vs. 33 degrees; P=0.510), or rib-vertebra angle difference (18 vs. 29 degrees; P=0.840). However, thoracic height (15.5 vs. 16.8 cm; P=0.031) and lumbar height (8.9 vs. 9.8 cm; P=0.013) were significantly greater upon casting cessation. Currently, 13 patients (30%) have had successful casting (improvement of major curve ≥10 degrees) while 24 patients (55%) experienced major curve progression (worsening), and 19 patients (43%) required surgical intervention. Mean time from first casting to surgery was 34.5±15.1 months. There were no statistically significant predictors for major curve progression on univariate analysis. CONCLUSIONS: Spinal deformity progression despite casting and the subsequent need for surgical intervention for NIS were significantly higher compared with those reported for idiopathic EOS. However, serial casting did afford a substantial delay in surgical intervention. Ultimately, serial casting for neuromuscular or syndromic EOS is an effective strategy for delaying surgical intervention, despite suboptimal radiographic outcomes. LEVEL OF EVIDENCE: Level III.

Assessing the Need for Common Perioperative Laboratory Tests in Pediatric Patients With Femoral Shaft Fractures.

BACKGROUND: Femoral shaft fractures are a common cause for hospital admission and surgery in pediatric patients, and laboratory studies are often ordered for historical concerns of excessive bleeding. Recent literature has challenged these assumptions, and unnecessary testing causes undue pain and costs in children. No previous studies have offered evidence-based recommendations for perioperative laboratories in isolated pediatric femoral shaft fractures. METHODS: We retrospectively reviewed all patients presenting with femoral shaft fractures at our pediatric trauma center between 2013 and 2017. Patients with multitrauma injuries, metabolic/neuromuscular diseases, or intensive care unit stays were excluded. Necessity of laboratory tests was determined by rates of anemia, blood transfusions, specialist consultations, and delayed surgeries. Ordering patterns were recorded, with cost estimation based on Healthcare Bluebook. RESULTS: We reviewed 95 patients (mean age, 7.9±4.8 y; 70 males). Treatments included elastic nails (33/95, 34.7%), reamed intramedullary nails (24/95, 25.3%), plates/screws (12/95, 12.6%), and spica casting (26/95, 27.4%). Of 32 patients with preoperative coagulation laboratories, 11 were abnormal; however none resulted in hematology consultations or procedure delays. Seventy-five patients (78.9%) and 15 patients (15.8%) had complete blood counts preoperatively and postoperative day 1, respectively. Four patients (4.2%) had hemoglobin<8 g/dL postoperatively, however, there were no perioperative blood transfusions. Of these 4, 3 underwent either reamed intramedullary nails or open reduction internal fixation with plates/screws. Twenty-six patients (27.4%) had preoperative basic metabolic panels that did not alter medical care. On the basis of our criteria, over 72% of laboratories appeared unnecessary, with a total potential cost of $8567. Over 80% of orders were from the emergency department by residents or attending physicians. CONCLUSIONS: Perioperative laboratory orders may be unnecessary in most isolated pediatric femoral shaft fractures, subjecting patients to extraneous costs, and associated pain. However, laboratories may be justified based on clinical circumstances or for older patients treated with reamed nails or plates/screws. Evidence-based recommendations for perioperative laboratory orders offer the potential to improve quality and value and minimize harm in pediatric orthopaedic trauma. LEVEL OF EVIDENCE: Level III-retrospective comparative study (therapeutic).

Perioperative Ketorolac for Supracondylar Humerus Fracture in Children Decreases Postoperative Pain, Opioid Usage, Hospitalization Cost, and Length-of-Stay.

BACKGROUND: There is a need for improved opioid stewardship in orthopedic surgery through multimodal analgesia strategies. Perioperative administration of ketorolac in children undergoing closed reduction and percutaneous pinning (CRPP) for displaced supracondylar humerus (SCH) fracture may decrease pain, reduce opioid requirements, and decrease hospitalization costs. METHODS: Retrospective case-control investigation of children (aged, 1 to 14) treated with CRPP for closed, modified Gartland type III extension-type SCH fractures at a single children's hospital between 2011 and 2017. Patients that received ketorolac perioperatively (cases) were randomly matched 1:2 by sex and age (±1 y) with patients that did not receive ketorolac (controls). Data abstraction included demographic and perioperative details including inpatient Wong-Baker FACES pain ratings and analgesic requirements. Analysis included 2-tailed Mann-Whitney U and χ tests. RESULTS: In total, 342 patients were studied including 114 cases and 228 controls. Age (mean, 6.2±2.4 y), sex ratio (M:F, 1.28:1), operative time, and number of pins used were equivalent between groups. Mean pain rating at 0 to 29 minutes postoperatively was lower in the ketorolac group (0.7±1.9) than in controls (1.4±2.6, P=0.017), as well as at 30 to 120 minutes postoperatively (1.1±2.3 and 1.7±2.8, respectively, P=0.036), as seen in Figure 1. Patients in the ketorolac group received a lower number of inpatient oxycodone doses (1.0±0.6) than control patients (1.2±0.5, P=0.003). Mean postoperative length-of-stay (LOS) was 50.0% longer for control patients (20.4±11.3 h) than the ketorolac patients (13.6±8.8 h, P<0.001). Ketorolac administration was associated with 40.4% lower inpatient hospitalization cost compared to control patients, providing a 33.8 times return on investment. There was no difference in the 90-day complication rate between patient groups (P=0.905). CONCLUSIONS: The complementary administration of ketorolac reduces postoperative pain and opioid use in children with displaced supracondylar humerus fractures. Perioperative ketorolac is also associated with reduced LOS following CRPP for supracondylar humerus fractures and offers significant cost savings opportunities. LEVEL OF EVIDENCE: Level 3-Therapeutic: Case-Control Study.

Safe Transportation in-Spica Following Surgical Treatment of Infantile DDH: Solutions and Threats.

BACKGROUND: Government regulations mandate appropriate vehicular restraints for children under 4 years of age. Patients treated for infantile developmental dysplasia of the hip (DDH) with spica casts often require special accommodations. Previous work suggests that car seat loaner programs may help achieve these goals while avoiding the need for costly ambulance transportation. The purpose of this study was to evaluate our center's experience with postdischarge transportation in a large population of DDH infants and identify future threats to our program. METHODS: We performed a retrospective review of patients 4 years or younger of age who underwent closed or open reduction for DDH at our center between 2011 and 2018. Only the initial surgery of staged procedures was included. Patient demographic factors were recorded, as were procedure type, final restraint used for postdischarge transportation, and any potential discharge delays secondary to transportation issues. Costs were compared amongst transportation options. RESULTS: Our cohort consisted of 130 patients (mean age, 1.4±0.9 y; 98 females) treated for DDH. In total 41 children (31.5%) underwent closed reduction procedures, whereas 89 patients (68.5%) underwent open reductions. After reduction, 62 (47.7%) received 2-legged spica casts and 68 (52.3%) received 1.5-legged casts. The most common restraint was a hospital-loaned Hippo car seat (73, 55.8%) followed by family-owned car seats (27, 20.8%). Eight patients (6.2%) experienced delays in discharge while waiting for adequate restraints, 6 patients (4.6%) were transported by ambulance, and 4 patients (3.1%) left against medical advice with inadequate restraints. CONCLUSIONS: Following surgical treatment of DDH, over 50% of patients with a spica cast were discharged using our center's car seat loaner program. However, availability and cost can present barriers for patients, with 4.6% of patients still being transported home by ambulance and 3.1% with inadequate restraints against medical advice. Costs of car seats are significant both for patients' families intending to purchase them, as well as for hospitals maintaining loaner programs and replacing used/lost seats. Moving forward, the recent cessation of production of the most common "spica car seat" threatens the longevity of existing loaner programs and calls renewed attention to the issue of safe transportation in-spica from providers and car-seat manufacturers alike. LEVEL OF EVIDENCE: Level III.

Quantitative Characterization of Bivalent Probes for a Dual Bromodomain Protein, Transcription Initiation Factor TFIID Subunit 1.

Multivalent binding is an efficient means to enhance the affinity and specificity of chemical probes targeting multidomain proteins in order to study their function and role in disease. While the theory of multivalent binding is straightforward, physical and structural characterization of bivalent binding encounters multiple technical difficulties. We present a case study where a combination of experimental techniques and computational simulations was used to comprehensively characterize the binding and structure-affinity relationships for a series of Bromosporine-based bivalent bromodomain ligands with a bivalent protein, Transcription Initiation Factor TFIID subunit 1 (TAF1). Experimental techniques-Isothermal Titration Calorimetry, X-ray Crystallography, Circular Dichroism, Size Exclusion Chromatography-Multi-Angle Light Scattering, and Surface Plasmon Resonance-were used to determine structures, binding affinities, and kinetics of monovalent ligands and bivalent ligands with varying linker lengths. The experimental data for monomeric ligands were fed into explicit computational simulations, in which both ligand and protein species were present in a broad range of concentrations, and in up to a 100 s time regime, to match experimental conditions. These simulations provided accurate estimates for apparent affinities (in good agreement with experimental data), individual dissociation microconstants and other microscopic details for each type of protein-ligand complex. We conclude that the expected efficiency of bivalent ligands in a cellular context is difficult to estimate by a single technique in vitro, due to higher order associations favored at the concentrations used, and other complicating processes. Rather, a combination of structural, biophysical, and computational approaches should be utilized to estimate and characterize multivalent interactions.

Purine metabolism controls innate lymphoid cell function and protects against intestinal injury.

Inflammatory bowel disease (IBD) is a condition of chronic inflammatory intestinal disorder with increasing prevalence but limited effective therapies. The purine metabolic pathway is involved in various inflammatory processes including IBD. However, the mechanisms through which purine metabolism modulates IBD remain to be established. Here, we found that mucosal expression of genes involved in the purine metabolic pathway is altered in patients with active ulcerative colitis (UC), which is associated with elevated gene expression signatures of the group 3 innate lymphoid cell (ILC3)-interleukin (IL)-22 pathway. In mice, blockade of ectonucleotidases (NTPDases), critical enzymes for purine metabolism by hydrolysis of extracellular adenosine 5'-triphosphate (eATP) into adenosine, exacerbates dextran-sulfate sodium-induced intestinal injury. This exacerbation of colitis is associated with reduction of colonic IL-22-producing ILC3s, which afford essential protection against intestinal inflammation, and is rescued by exogenous IL-22. Mechanistically, activation of ILC3s for IL-22 production is reciprocally mediated by eATP and adenosine. These findings reveal that the NTPDase-mediated balance between eATP and adenosine regulates ILC3 cell function to provide protection against intestinal injury and suggest potential therapeutic strategies for treating IBD by targeting the purine-ILC3 axis.

X-ray micro-computed tomography (µCT): an emerging opportunity in parasite imaging.

X-ray micro-computed tomography (µCT) is a technique which can obtain three-dimensional images of a sample, including its internal structure, without the need for destructive sectioning. Here, we review the capability of the technique and examine its potential to provide novel insights into the lifestyles of parasites embedded within host tissue. The current capabilities and limitations of the technology in producing contrast in soft tissues are discussed, as well as the potential solutions for parasitologists looking to apply this technique. We present example images of the mouse whipworm Trichuris muris and discuss the application of µCT to provide unique insights into parasite behaviour and pathology, which are inaccessible to other imaging modalities.

Preoperative Patellofemoral Chondromalacia is Not a Contraindication for Fixed-Bearing Medial Unicompartmental Knee Arthroplasty.

BACKGROUND: Patellofemoral chondromalacia (PFCM) has historically been considered a contraindication for unicompartmental knee arthroplasty (UKA), but there is limited data assessing PFCM's impact on the results of fixed-bearing UKA. Our objective was to assess the impact of medial patellar and/or medial trochlear PFCM on overall and patellofemoral-specific 2-year outcomes after fixed-bearing medial UKA. METHODS: Intraoperative notes defined the presence and location of PFCM during fixed bearing medial UKA. Outcome measures included the New Knee Society Score (NKSS), Kneeling Ability Score (KAS) and Forgotten Joint Score (FJS-12). Thirty-one knees with PFCM (PFCM group), and 52 knees without PFCM (N-PFCM group) were included for analysis. Mann-Whitney U tests assessed the statistical significance of observed differences, and a Bonferroni correction was applied, adjusting threshold for significance to P = .005. RESULTS: At minimum follow-up of 2 years, no statistical differences were detected between the N-PFCM and PFCM groups in the postoperative NKSS (159 vs 157, P = .731), preoperative to postoperative NKSS change (P = .447), FJS-12 (70.5 vs 67.6, P = .471), or KAS (71% vs 65%, P = .217). Patients with isolated patellar chondromalacia (n = 13) demonstrated trends toward worse outcomes according to NKSS (147, P = .198), FJS-12 (58, P = .094), and KAS (46%, P = .018), but were statistically insignificant. No failures occurred in either group. CONCLUSION: Functional outcomes of fixed-bearing medial UKA are not adversely impacted by the presence of PFCM involving the medial patellar facet and/or medial or central trochlea. Further follow-up is needed to determine longer-term implications of fixed-bearing medial UKA in patients with PFCM.

A central role for hepatic conventional dendritic cells in supporting Th2 responses during helminth infection.

Dendritic cells (DCs) are the key initiators of T-helper (Th) 2 immune responses against the parasitic helminth Schistosoma mansoni. Although the liver is one of the main sites of antigen deposition during infection with this parasite, it is not yet clear how distinct DC subtypes in this tissue respond to S. mansoni antigens in vivo, or how the liver microenvironment might influence DC function during establishment of the Th2 response. In this study, we show that hepatic DC subsets undergo distinct activation processes in vivo following murine infection with S. mansoni. Conventional DCs (cDCs) from schistosome-infected mice upregulated expression of the costimulatory molecule CD40 and were capable of priming naive CD4(+) T cells, whereas plasmacytoid DCs (pDCs) upregulated expression of MHC class II, CD86 and CD40 but were unable to support the expansion of either naive or effector/memory CD4(+) T cells. Importantly, in vivo depletion of pDCs revealed that this subset was dispensable for either maintenance or regulation of the hepatic Th2 effector response during acute S. mansoni infection. Our data provides strong evidence that S. mansoni infection favors the establishment of an immunogenic, rather than tolerogenic, liver microenvironment that conditions cDCs to initiate and maintain Th2 immunity in the context of ongoing antigen exposure.

Modulation of dendritic cell alternative activation and function by the vitamin A metabolite retinoic acid.

The archetypal Th2 cytokine IL-4 has previously been shown to alternatively activate murine macrophages and, more recently, dendritic cells (DCs) both in vitro and in vivo. IL-4 has also been shown to induce Aldh1a2 (aldehyde dehydrogenase 1a2) expression in murine macrophages recruited to the peritoneal cavity. However, the influence of IL-4 on DC Aldh1a2 induction in vivo has not yet been addressed. In this work, we found that DCs show enhanced aldehyde dehydrogenase enzyme activity in vivo, which led us to investigate the impact of the vitamin A metabolite all-trans retinoic acid (RA) on DC alternative activation and function. Antagonism of RA receptors reduced production of resistin-like molecule alpha by DCs responding to IL-4, while addition of exogenous RA enhanced production of this marker of alternative activation. Functionally, RA increased DC induction of CD4(+) T-cell IL-10, while reducing CD4(+) T-cell IL-4 and IL-13, revealing a previously unidentified role for RA in regulating the ability of alternatively activated DCs to influence Th2 polarization.

A unique DNA methylation signature defines a population of IFN-γ/IL-4 double-positive T cells during helminth infection.

Th1 and Th2 cell fates are traditionally viewed as mutually exclusive, but recent work suggests that these lineages may be more plastic than previously thought. When isolating splenic CD4(+) T cells from mice infected with the parasitic helminth Schistosoma mansoni, we observed a defined population of IFN-γ/IL-4 double-positive cells. These IFN-γ(+) IL-4(+) cells showed differences in DNA methylation at the Ifng and Il4 loci when compared with IFN-γ(+) IL-4(-) (Th1) and IFN-γ(-) IL-4(+) (Th2) cells, demonstrating that they represent a distinct effector cell population. IFN-γ(+) IL-4(+) cells also displayed a discrete DNA methylation pattern at a CpG island within the body of the Gata3 gene, which encodes the master regulator of Th2 identity. DNA methylation at this region correlated with decreased Gata3 levels, suggesting a possible role in controlling Gata3 expression. These data provide important insight into the molecular mechanisms behind the co-existence of Th1 and Th2 characteristics.