Intrinsic disorder of a nucleoplasmin-like histone chaperone specifies its discrete nuclear and nucleolar functions

Nucleoplasmin (NPM) histone chaperones regulate distinct processes in the nucleus and nucleolus. While intrinsically disordered regions (IDRs) are hallmarks of NPMs, it is not clear whether all NPM functions require these unstructured features. We assessed the importance of IDRs in a yeast NPM-like protein and found that regulation of rDNA copy number and genetic interactions with the nucleolar RNA surveillance machinery require the highly conserved FKBP prolyl isomerase domain, but not the NPM domain or IDRs. By contrast, transcriptional repression in the nucleus requires IDRs. Furthermore, multiple lysines in polyacidic serine/lysine motifs of IDRs are required for both lysine polyphosphorylation and NPM-mediated transcriptional repression. These results demonstrate that this NPM-like protein relies on IDRs only for some of its chromatin-related functions.

Cis-regulatory architecture and functions of a gene desert controlling pleiotropic expression and cardiac pacemaker development

 

Gene deserts are extensive genomic regions spanning more than 500 kilobases and enriched near developmental genes. Despite their proposed critical roles in development, the enhancer architecture, and biological functions of most gene deserts in mammalian genomes remain unknown. The Shox2 transcription factor is a key regulator of cardiac pacemaker differentiation and at the genomic level is flanked by a centromeric gene desert harboring a multitude of predicted cis-regulatory modules (CRMs). Using CRISPR-Cas9 we demonstrate a requirement of this gene desert for pleiotropic expression and embryonic survival through full control of Shox2 in the sinoatrial node (SAN). To decode the underlying chromatin architecture and CRM logic, we performed region-specific chromatin conformation capture, epigenomic analysis and transgenic in vivo reporter assays. While the Shox2 regulatory landscape was found partitioned into largely tissue-invariant chromatin loops, we identified a surprising cardiac-specific contact domain within the gene desert. Subsequent transgenic analysis revealed clustering of non-cardiac enhancers with activities in limb, craniofacial or neuronal populations in this domain, pointing to a potential tissue-specific 3D-mechanism for enhancer attenuation. In addition, SAN-chromatin assessment and H3K27ac profiling from human fetal cardiac compartments enabled the identification of a unique cardiac enhancer located outside of the contact domain and essential for robust Shox2 levels during cardiac pacemaker development. In summary, our results serve as a blueprint to investigate gene desert function in context to cardiac defects and identify the Shox2 gene desert as a robust cis-regulatory hub indispensable for pleiotropic patterning, cardiac pacemaker differentiation and embryonic survival.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Swiss National Science Foundation (SNSF),National Institutes of Health (NIH)

905 How to prioritise patients and safely resume elective surgery during the Covid-19 pandemic

Introduction

There are now over 2.5 million NHS patients awaiting elective surgery, with the most in orthopaedics. We present an algorithm and results for safely and equitably restarting surgery at COVID-light sites.

Method

An MDT applied the COVID-19 Algorithm for Resuming Elective Surgery (CARES) on 1169 patients awaiting elective orthopaedic surgery. It assessed safety, procedural efficacy, and biopsychosocial factors, to prioritise patients. They were assigned to five categories and underwent surgery at one of three COVID-light sites (1. access to HDU/ITU/Paediatrics/specialist equipment, 2. an NHS elective surgical unit and 3. a private elective surgical unit).

Results

21 ‘Urgent’ patients received expedited care; 118 were Level 1/2; 222 were Level 3; 808 were Level 4. In 6 weeks, 355 surgeries were performed, with Urgent and Level 1/2 cases performed soonest (mean 18 days, p < 0.001). 33 high-risk/complex/paediatric patients had surgery at Site 1 and the rest at Sites 2 and 3. No patients contracted COVID-19 within 2 weeks of surgery.

Conclusions

We validated a widely generalisable model to facilitate resumption of elective surgery in COVID-light sites. It enabled surgery for patients in most suffering, undergoing the most efficacious procedures and/or at highest risk of deterioration, without compromising patient-safety.

The compartmental distribution of knee osteoarthritis - a systematic review and meta-analysis

OBJECTIVES

For a population with knee osteoarthritis (OA), determine: 1) the prevalence of single compartmental, bicompartmental and tricompartmental OA, 2) the prevalence of isolated medial tibiofemoral, lateral tibiofemoral, or patellofemoral OA, and combinations thereof.

METHODS

PubMed and Web of Science databases, and reference lists of identified studies, were searched to find studies which reported on the compartmental distribution and prevalence of knee OA. Two independent reviewers assessed studies against pre-defined inclusion criteria and prevalence data were extracted along with subject characteristics. The methodological quality of each included study was assessed. A random-effects model meta-analysis was performed for each OA category to estimate the relative prevalence of OA in the knee compartments amongst people with knee OA.

RESULTS

16 studies (3,786 knees) met the inclusion criteria. High heterogeneity was measured. Normalised for knees with OA, estimated prevalence rates (95% CI) were: single compartmental 50% (31.5-58.3%), bicompartmental 33% (23.1-37.2%) and tricompartmental only 17% (8.8-24.8%). Isolated medial tibiofemoral OA, isolated patellofemoral OA, and combined medial tibiofemoral and patellofemoral OA were more common than tricompartmental disease, occurring in 27% (15.2-31.1%), 18% (9.9-22.7%) and 23% (14.1-27.3%) of people respectively. Single/bicompartmental patterns of disease involving the lateral tibiofemoral compartment were less common, summing to 15% (8.5-18.7%).

CONCLUSION

Three-quarters of people with knee OA do not have tricompartmental disease. This is not reflected in the frequency with which partial and combined partial knee arthroplasties are currently used.

TRIAL REGISTRATION NUMBER

PROSPERO systematic review protocol (CRD42019140345).

Development of a reference material for analysing naturally occurring radioactive material from the steel industry

Accurate measurement of naturally occurring radionuclides in blast furnace slag, a by-product of the steel industry, is required for compliance with building regulations where it is often used as an ingredient in cement. A matrix reference blast furnace slag material has been developed to support traceability in these measurements. Raw material provided by a commercial producer underwent stability and homogeneity testing, as well as characterisation of matrix constituents, to provide a final candidate reference material. The radionuclide content was then determined during a comparison exercise that included 23 laboratories from 14 countries. Participants determined the activity per unit mass for ²²⁶Ra, ²³²Th and ⁴⁰K using a range of techniques. The consensus values obtained from the power-moderated mean of the reported participant results were used as indicative activity per unit mass values for the three radionuclides: A₀(²²⁶Ra) = 106.3 (34) Bq·kg^-1, A₀(²³²Th) = 130.0 (48) Bq·kg^-1 and A₀(⁴⁰K) = 161 (11) Bq·kg^-1 (where the number in parentheses is the numerical value of the combined standard uncertainty referred to the corresponding last digits of the quoted result). This exercise helps to address the current shortage of NORM industry reference materials, putting in place infrastructure for production of further reference materials.

Classification of combined partial knee arthroplasty

AIMS

There has been a recent resurgence in interest in combined partial knee arthroplasty (PKA) as an alternative to total knee arthroplasty (TKA). The varied terminology used to describe these procedures leads to confusion and ambiguity in communication between surgeons, allied health professionals, and patients. A standardized classification system is required for patient safety, accurate clinical record-keeping, clear communication, correct coding for appropriate remuneration, and joint registry data collection.

MATERIALS AND METHODS

An advanced PubMed search was conducted, using medical subject headings (MeSH) to identify terms and abbreviations used to describe knee arthroplasty procedures. The search related to TKA, unicompartmental (UKA), patellofemoral (PFA), and combined PKA procedures. Surveys were conducted of orthopaedic surgeons, trainees, and biomechanical engineers, who were asked which of the descriptive terms and abbreviations identified from the literature search they found most intuitive and appropriate to describe each procedure. The results were used to determine a popular consensus.

RESULTS

Survey participants preferred "bi-unicondylar arthroplasty" (Bi-UKA) to describe ipsilateral medial and lateral unicompartmental arthroplasty; "medial bi-compartmental arthroplasty" (BCA-M) to describe ipsilateral medial unicompartmental arthroplasty with patellofemoral arthroplasty; "lateral bi-compartmental arthroplasty" (BCA-L) to describe ipsilateral lateral unicompartmental arthroplasty with patellofemoral arthroplasty; and tri-compartmental arthroplasty (TCA) to describe ipsilateral patellofemoral and medial and lateral unicompartmental arthroplasties. "Combined partial knee arthroplasty" (CPKA) was the favoured umbrella term.

CONCLUSION

We recommend bi-unicondylar arthroplasty (Bi-UKA), medial bicompartmental arthroplasty (BCA-M), lateral bicompartmental arthroplasty (BCA-L), and tricompartmental arthroplasty (TCA) as the preferred terms to classify CPKA procedures. Cite this article: Bone Joint J 2019;101-B:922-928.

Heterogeneous combinatorial expression of Hoxd genes in single cells during limb development

BACKGROUND

Global analyses of gene expression during development reveal specific transcription patterns associated with the emergence of various cell types, tissues, and organs. These heterogeneous patterns are instrumental to ensure the proper formation of the different parts of our body, as shown by the phenotypic effects generated by functional genetic approaches. However, variations at the cellular level can be observed within each structure or organ. In the developing mammalian limbs, expression of Hox genes from the HoxD cluster is differentially controlled in space and time, in cells that will pattern the digits and the forearms. While the Hoxd genes broadly share a common regulatory landscape and large-scale analyses have suggested a homogenous Hox gene transcriptional program, it has not previously been clear whether Hoxd genes are expressed together at the same levels in the same cells.

RESULTS

We report a high degree of heterogeneity in the expression of the Hoxd11 and Hoxd13 genes. We analyzed single-limb bud cell transcriptomes and show that Hox genes are expressed in specific combinations that appear to match particular cell types. In cells giving rise to digits, we find that the expression of the five relevant Hoxd genes (Hoxd9 to Hoxd13) is unbalanced, despite their control by known global enhancers. We also report that specific combinatorial expression follows a pseudo-time sequence, which is established based on the transcriptional diversity of limb progenitors.

CONCLUSIONS

Our observations reveal the existence of distinct combinations of Hoxd genes at the single-cell level during limb development. In addition, we document that the increasing combinatorial expression of Hoxd genes in this developing structure is associated with specific transcriptional signatures and that these signatures illustrate a temporal progression in the differentiation of these cells.

Differences in trochlear parameters between native and prosthetic kinematically or mechanically aligned knees

INTRODUCTION

Kinematic (KA) and mechanical (MA) alignment techniques are two different philosophies of implant positioning that use the same TKA implants. This might generate differences in the resulting prosthetic trochleae parameters between the two techniques of alignment. Our study aim was to test the following hypotheses : (1) mechanically or kinematically aligned femoral implant understuffs the native trochlear articular surface and poorly restores the native groove orientation, and (2) the orientation of the prosthetic trochlear groove and trochlear fill are different between MA and KA.

METHODS

Three-dimensional models of the femur were made from segmentation of preoperative Magnetic Resonance Imaging scans (MRIs) of ten subjects with isolated medial tibiofemoral osteoarthritis. In-house planning and analysis software kinematically and mechanically aligned a modern cruciate retaining femoral component and determined differences in parameters of the trochlear fit between native and prosthetic trochleae, and between KA and MA prosthetic trochleae.

RESULTS

The MA prosthetic trochleae did not fill (understuffed) the entire length of the native medial facet and the proximal 70% of the native groove and lateral facet, and oriented the trochleae groove 8° more valgus than native. The KA prosthetic trochleae understuffed the proximal 70% of the native trochleae, and had a groove 6° more valgus than native. The KA trochleae understuffed the medial facet distally and oriented the groove 2° less valgus and 3° more internally rotated than the MA trochleae.

CONCLUSION

MA and KA prosthetic trochleae substantially understuff and create a prosthetic groove more valgus compared to native trochlear anatomy, and they also differed between each other regarding trochleae stuffing and groove alignment. Although randomized trials have not shown differences in patellofemoral complications between KA and MA, a femoral component designed specifically for KA that more closely restores the native trochlear anatomy might improve patient reported satisfaction and function.

LEVEL OF EVIDENCE

Level 2 controlled laboratory study.

Alignment options for total knee arthroplasty: A systematic review

In spite of improvements in implant designs and surgical precision, functional outcomes of mechanically aligned total knee arthroplasty (MA TKA) have plateaued. This suggests probable technical intrinsic limitations that few alternate more anatomical recently promoted surgical techniques are trying to solve. This review aims at (1) classifying the different options to frontally align TKA implants, (2) at comparing their safety and efficacy with the one from MA TKAs, therefore answering the following questions: does alternative techniques to position TKA improve functional outcomes of TKA (question 1)? Is there any pathoanatomy not suitable for kinematic implantation of a TKA (question 2)? A systematic review of the existing literature utilizing PubMed and Google Scholar search engines was performed in February 2017. Only studies published in peer-reviewed journals over the last ten years in either English or French were reviewed. We identified 569 reports, of which 13 met our eligibility criteria. Four alternative techniques to position a TKA are challenging the traditional MA technique: anatomic (AA), adjusted mechanical (aMA), kinematic (KA), and restricted kinematic (rKA) alignment techniques. Regarding osteoarthritic patients with slight to mid constitutional knee frontal deformity, the KA technique enables a faster recovery and generally generates higher functional TKA outcomes than the MA technique. Kinematic alignment for TKA is a new attractive technique for TKA at early to mid-term, but need longer follow-up in order to assess its true value. It is probable that some forms of pathoanatomy might affect longer-term clinical outcomes of KA TKA and make the rKA technique or additional surgical corrections (realignment osteotomy, retinacular ligament reconstruction etc.) relevant for this sub-group of patients. Longer follow-up is needed to define the best indication of each alternative surgical technique for TKA. Level I for question 1 (systematic review of Level I studies), level 4 for question 2.

The kinematic alignment technique for TKA reliably aligns the femoral component with the cylindrical axis

INTRODUCTION

Kinematic alignment (KA) technique is an alternative technique for positioning a TKA, which aims a patient-specific implant positioning in order to reproduce the pre-arthritic knee anatomy. Because reliability in implant positioning is of interest to obtain reproducible good functional results, our study tests the hypothesis that the medial and lateral distal and posterior positions of the planned and surgically implanted kinematically aligned femoral component are similar.

METHODS

Preoperative knee magnetic resonance imaging (MRI) and postoperative knee computed tomography (CT) of 13 patients implanted with a KA Persona^® TKA (Zimmer, Warsaw, USA) using manual instrumentation (kinematically-aligned TKA procedure pack^®, Zimmer Biomet, Warsaw, USA) were segmented to create 3D femoral models. The kinematic alignment position of the femoral component was planned on the 3D model created from the preoperative MRI. Differences in the positions of the planned and surgically implanted kinematically-aligned femoral component were determined with in-house analysis software.

RESULTS

The average differences between the medial and lateral distal and posterior positions of the planned and surgically implanted kinematically-aligned femoral component were inferior to 1mm and no statistically significant. In terms of variability, 62% (8/13) of performed implants matched all four positions within 1.5mm, and the maximum difference was 3mm.

CONCLUSION

In this small series, intraoperative kinematic positioning of the femoral component with the specific manual instrumentation closely matched the planned position, which suggests that this technique reliably aligned the flexion-extension axis of the femoral component to the cylindrical axis.

LEVEL OF EVIDENCE

Level 3.

Mechanical alignment technique for TKA: Are there intrinsic technical limitations?

BACKGROUND

Mechanically aligned (MA) total knee arthroplasty (TKA) is affected by disappointing functional outcomes in spite of the recent improvements in surgical precision and implant designs. This might suggest the existence of intrinsic technical limitations. Our study aims to compare the prosthetic and native trochlear articular surfaces and to estimate the extent of collateral ligament imbalance, which is technically uncorrectable by collateral ligament release when TKA implants are mechanically aligned.

STUDY HYPOTHESIS

Conventional MA technique generates a high rate of prosthetic overstuffing of the distal groove, distal lateral trochlear facet and distal lateral femoral condyle (Hypothesis 1), and technically uncorrectable collateral ligament imbalance (hypothesis 2)? Disregarding the distal femoral joint line obliquity (DFJLO) when performing femoral cuts explains distal lateral femoral prosthetic stuffing and uncorrectable imbalance (hypothesis 3)?

METHODS

Twenty patients underwent a conventional MA TKA. Pre-operative MRI-based 3D knee models were generated and MA TKA was simulated. Native and prosthetic trochlear articular surfaces were compared using in-house analysis software. Following the automatic determination by the planning software of the size of the extension and flexion gaps, an algorithm was applied to balance the gaps and the frequency and amplitude of technically uncorrectable knee imbalance were estimated.

RESULTS

The conventional MA technique generates a significant slight distal lateral femoral prosthetic overstuffing (mean 0.6mm, 0.8mm, 1.25mm for the most distal lateral facet point, groove, and at the most distal point of lateral femoral condyle, respectively) and a high rate of type 1 and 2 uncorrectable knee imbalance (30% and 40%, respectively). The incidence of distal lateral prosthetic overstuffing (trochlea and condyle) and uncorrectable knee imbalance were strongly to very strongly correlated with the DFJLO (r=0.53 to 0.89).

CONCLUSION

Conventional MA technique for TKA generates frequent lateral distal femoral prosthetic overstuffing and technically uncorrectable knee imbalance secondary to disregarding the DFJLO when adjusting the femoral component frontal and axial rotations, respectively.

LEVEL OF EVIDENCE

level 4.

The effect of long-term bisphosphonate therapy on trabecular bone strength and microcrack density

Objectives

Bisphosphonates (BP) are the first-line treatment for preventing fragility fractures. However, concern regarding their efficacy is growing because bisphosphonate is associated with over-suppression of remodelling and accumulation of microcracks. While dual-energy X-ray absorptiometry (DXA) scanning may show a gain in bone density, the impact of this class of drug on mechanical properties remains unclear. We therefore sought to quantify the mechanical strength of bone treated with BP (oral alendronate), and correlate data with the microarchitecture and density of microcracks in comparison with untreated controls.

Methods

Trabecular bone from hip fracture patients treated with BP (n = 10) was compared with naïve fractured (n = 14) and non-fractured controls (n = 6). Trabecular cores were synchrotron scanned and micro-CT scanned for microstructural analysis, including quantification of bone volume fraction, microarchitecture and microcracks. The specimens were then mechanically tested in compression.

Results

BP bone was 28% lower in strength than untreated hip fracture bone, and 48% lower in strength than non-fractured control bone (4.6 MPa vs 6.4 MPa vs 8.9 MPa). BP-treated bone had 24% more microcracks than naïve fractured bone and 51% more than non-fractured control (8.12/cm²vs 6.55/cm²vs 5.25/cm²). BP and naïve fracture bone exhibited similar trabecular microarchitecture, with significantly lower bone volume fraction and connectivity than non-fractured controls.

Conclusion

BP therapy had no detectable mechanical benefit in the specimens examined. Instead, its use was associated with substantially reduced bone strength. This low strength may be due to the greater accumulation of microcracks and a lack of any discernible improvement in bone volume or microarchitecture. This preliminary study suggests that the clinical impact of BP-induced microcrack accumulation may be significant.

Cite this article: A. Jin, J. Cobb, U. Hansen, R. Bhattacharya, C. Reinhard, N. Vo, R. Atwood, J. Li, A. Karunaratne, C. Wiles, R. Abel. The effect of long-term bisphosphonate therapy on trabecular bone strength and microcrack density. Bone Joint Res 2017;6:602–609. DOI: 10.1302/2046-3758.610.BJR-2016-0321.R1.

The influence of spine-hip relations on total hip replacement: A systematic review

Sagittal pelvic kinematics along with spino-pelvic angular parameters have recently been studied by numerous investigators for their effect on total hip replacement (THR) clinical outcomes, but many issue of spine-hip relations (SHR) are currently unexplored. Therefore, our review aims at clarifying the following questions: is there any evidence of a relationship between articular impingement/dislocation risk in primary THR and (1) certain sagittal pelvic kinematics patterns, (2) pelvic incidence, and (3) types of SHRs? A systematic review of the existing literature utilising PubMed and Google search engines was performed in January 2017. Only clinical or computational studies published in peer-reviewed journals over the last five years in either English or French were reviewed. We identified 769 reports, of which 12 met our eligibility criteria. A review of literature shows that sagittal pelvic kinematics, but not the pelvic incidence, influences the risk of prosthetic impingement/dislocation. We found no study having assessed the relationship between this risk and the types of SHRs. Sagittal pelvic kinematics is highly variable among individuals and certain kinematic patterns substantially influences the risk of prosthetic impingement/dislocation. Recommendations for cup positioning are therefore switching from a systematic to a patient-specific approach, with the standing cup orientation Lewinneck safe zone progressively giving way to a new parameter of interest: the functional orientation of the cup. Based on a recently published classification for SHRs, We propose a new concept of "kinematically aligned THR" for the purposes of THR planning. Further studies are needed to investigate the relevance of such a classification towards the assumptions and hypothesis we have made. Level of evidence,- Level IV, systematic review of level III and IV studies.

Spine-hip relations add understandings to the pathophysiology of femoro-acetabular impingement: A systematic review

Relationship between hip pathoanatomy and symptomatic FAI has been reported to be weak. This is explained by the reciprocal interaction between proximal femur and acetabular anatomies, but potentially also by the individual spine-hip relations (SHR). The key-answer for a complete understanding of the pathophysiology of FAI might lie in the comprehension of the SHRs, which have not yet been fully addressed. Therefore we conducted a systematic review to answer the subsequent questions: Is there any evidence of a relationship between FAI and (1) sagittal pelvic kinematics, (2) pelvic incidence, and (3) types of SHRs? A systematic review of the existing literature utilizing PubMed and Google search engines was performed in December 2016. Only studies published in peer-reviewed journals over the last ten years in either English or French were reviewed. We identified 90 reports, of which 9 met our eligibility criteria. Review of literature shows Caucasian FAI patients have a pelvis with higher anterior tilt, lesser sagittal mobility, and lower pelvic incidence compared to healthy patients. We found no study having assessed the relationship between SHR and FAI. In order to help further investigations at answering questions 3 and 4, we have developed a classification for SHRs. The classification according spino-pelvic parameters allows identifying patient at risk regarding FAI occurrence. Higher anterior pelvic tilt in standing, sitting and squatting positions and lower pelvic incidence have been found to correlate with symptomatic FAI. Because defining the individual SHR might increase the understanding of the pathophysiology of hip impingement, we have developed a classification for SHRs.

LEVEL OF EVIDENCE

Level IV, systematic review of Level III and IV studies.

Fine-mapping the MHC locus in juvenile idiopathic arthritis (JIA) reveals genetic heterogeneity corresponding to distinct adult inflammatory arthritic diseases

Objectives

Juvenile idiopathic arthritis (JIA) is a heterogeneous group of diseases, comprising seven categories. Genetic data could potentially be used to help redefine JIA categories and improve the current classification system. The human leucocyte antigen (HLA) region is strongly associated with JIA. Fine-mapping of the region was performed to look for similarities and differences in HLA associations between the JIA categories and define correspondences with adult inflammatory arthritides.

Methods

Dense genotype data from the HLA region, from the Immunochip array for 5043 JIA cases and 14 390 controls, were used to impute single-nucleotide polymorphisms, HLA classical alleles and amino acids. Bivariate analysis was performed to investigate genetic correlation between the JIA categories. Conditional analysis was used to identify additional effects within the region. Comparison of the findings with those in adult inflammatory arthritic diseases was performed.

Results

We identified category-specific associations and have demonstrated for the first time that rheumatoid factor (RF)-negative polyarticular JIA and oligoarticular JIA are genetically similar in their HLA associations. We also observe that each JIA category potentially has an adult counterpart. The RF-positive polyarthritis association at HLA-DRB1 amino acid at position 13 mirrors the association in adult seropositive rheumatoid arthritis (RA). Interestingly, the combined oligoarthritis and RF-negative polyarthritis dataset shares the same association with adult seronegative RA.

Conclusions

The findings suggest the value of using genetic data in helping to classify the categories of this heterogeneous disease. Mapping JIA categories to adult counterparts could enable shared knowledge of disease pathogenesis and aetiology and facilitate transition from paediatric to adult services.

Noninvasive Measurement Techniques for Monitoring of Microvascular Function in the Diabetic Foot

There are, currently, 3 established clinical techniques routinely employed to determine the risk of ulceration in the diabetic foot. These are assessment of the circulation, the nervous control of sensation, and foot sensitivity to loading. Macrovascular measurements are used to assess sufficiency of the arterial supply to the foot. Evaluation of somatic neuropathy provides an indication of loss of plantar sensation. Skin pressure measurements indicate abnormalities in plantar loading. This combined approach is effective in allowing preventative measures to be applied prior to the onset of ulceration. In contrast, clinical measurement of microvascular function in the diabetic foot is uncommon. Indeed, there remains uncertainty regarding the importance of micro-vascular complications in the development of foot ulcers. This is in part due to the difficulty of making in vivo measurements of microvascular function. This article evaluates 3 noninvasive measurement techniques for routine micro-vascular assessment of the diabetic foot: transcutaneous oxygen tension, laser Doppler flowmetry, and near-infrared spectroscopy. These techniques can be used to obtain useful parameters of microvascular function including surface oxygen, blood flow, intracellular oxygenation, and cellular respiration. In principle, such measurements can be related to underlying pathophysiology, for example, microangiopathy or autonomic neuropathy. This article considers how these general techniques can be adapted to support routine clinical measurement of microvascular function, particularly in the neuropathic diabetic foot.

Sugar-Protein Connectivity Impacts on the Immunogenicity of Site-Selective Salmonella O-Antigen Glycoconjugate Vaccines

A series of glycoconjugates with defined connectivity were synthesized to investigate the impact of coupling Salmonella typhimurium O-antigen to different amino acids of CRM₁₉₇ protein carrier. In particular, two novel methods for site-selective glycan conjugation were developed to obtain conjugates with single attachment site on the protein, based on chemical modification of a disulfide bond and pH-controlled transglutaminase-catalyzed modification of lysine, respectively. Importantly, conjugation at the C186-201 bond resulted in significantly higher anti O-antigen bactericidal antibody titers than coupling to K37/39, and in comparable titers to conjugates bearing a larger number of saccharides. This study demonstrates that the conjugation site plays a role in determining the immunogenicity in mice and one single attachment point may be sufficient to induce high levels of bactericidal antibodies.

A feasibility study into the use of three-dimensional printer modelling in acetabular fracture surgery

There are a number of challenges associated with the operative treatment of acetabular fractures. The approach used is often extensive, while operative time and perioperative blood loss can also be significant. With the proliferation of 3D printer technology, we present a fast and economical way to aid the operative planning of complex fractures. We used augmented stereoscopic 3D CT reconstructions to allow for an appreciation of the normal 3D anatomy of the pelvis on the fractured side and to use the models for subsequent intraoperative contouring of pelvic reconstruction plates. This leads to a reduction in the associated soft tissue trauma, reduced intraoperative time and blood loss, minimal handling of the plate, and reduced fluoroscopic screening times. We feel that the use of this technology to customize implants, plates, and the operative procedure to a patient's unique anatomy can only lead to improved outcomes.

The DEXLIFE study methods: identifying novel candidate biomarkers that predict progression to type 2 diabetes in high risk individuals

The incidence of type 2 diabetes (T2D) is rapidly increasing worldwide and T2D is likely to affect 592 million people in 2035 if the current rate of progression is continued. Today, patients are diagnosed with T2D based on elevated blood glucose, either directly or indirectly (HbA1c). However, the information on disease progression is limited. Therefore, there is a need to identify novel early markers of glucose intolerance that reflect the underlying biology and the overall physiological, metabolic and clinical characteristics of progression towards diabetes. In the DEXLIFE study, several clinical cohorts provide the basis for a series of clinical, physiological and mechanistic investigations in combination with a range of--omic technologies to construct a detailed metabolic profile of high-risk individuals across multiple cohorts. In addition, an exercise and dietary intervention study is conducted, that will assess the impact on both plasma biomarkers and specific functional tissue-based markers. The DEXLIFE study will provide novel diagnostic and predictive biomarkers which may not only effectively detect the progression towards diabetes in high risk individuals but also predict responsiveness to lifestyle interventions known to be effective in the prevention of diabetes.

The amino acid response to a mixed meal in patients with type 2 diabetes: effect of sitagliptin treatment

AIMS

Amino acid (AA) metabolism is altered in type 2 diabetes (T2D), and fasting levels of α-hydroxybutyrate (α-HB), a biomarker for insulin resistance, have been suggested to track AA metabolism. We investigated the changes in AA and α-HB induced by a mixed-meal tolerance test (MTT) and the effects of sitagliptin treatment.

METHODS

Forty-seven T2D patients [56 ± 7 years, body mass index (BMI) 29.9 ± 4.2 kg/m(2) ] were randomized to sitagliptin (100 mg/day, 6 weeks) or placebo. Seven age- and BMI-matched non-diabetic subjects served as control (CT).

RESULTS

During a 5-h MTT, branched-chain AA (BCAA) peaked earlier in T2D than CT [75(25) vs. 62(3) mmol/l · h over 2 h, median(interquartile range), p = 0.05], and rose higher [5-h increment: 31(23) vs. 19(24) mmol/l · h, p = 0.05]. Fasting α-HB was higher [7.5(2.7) vs. 5.9(1.3) µg/ml, p = 0.04 T2D vs. CT], and its meal-induced increments were larger [24(99) vs. -41(86) µg/ml · h, p = 0.006]. Plasma non-esterified fatty acids (NEFA) declined during MTT, but their increments were greater in patients (53 ± 16 vs. 35 ± 10 mEq/l · h, p = 0.005). Compared to placebo, both BCAA [-6.4(21.1) vs. 0.0(48.0) mmol/l · h, p = 0.01] and α-HB increments [-114(250) vs. 114(428) µg/ml · h, p = 0.002] decreased with sitagliptin, and meal-induced NEFA suppression was improved. Changes in BCAA and α-HB were reciprocally related to changes in insulin sensitivity (ρ = -0.37 and -0.43, p ≤ 0.01).

CONCLUSIONS

T2D is associated with a hyperaminoacidaemic response to MTT, which circulating α-HB levels track. Sitagliptin-induced glycaemic improvement was associated with reductions in BCAA and α-HB excursions and better NEFA suppression, in parallel with improved insulin sensitivity, confirming that α-HB is a readout of metabolic overload.

Comparison of photocatalytic degradation of dyes in relation to their structure

The photocatalytic degradation of a series of six acid dyes (Direct Red 80, Direct Red 81, Direct Red 23, Direct Violet 51, Direct Yellow 27, and Direct Yellow 50) has been tested compared in terms of color removal, mineralization, and toxicity (Lactuca sativa L. test) after photocatalysis on immobilized titanium dioxide. The dyes were examined at their natural pH and after hydrolysis at pH 12. Results show that hydrolysis decreases strongly the efficiency of color removal, that full mineralization takes much longer reaction time than color removal, and that toxicity is only very partially reduced. Some structural parameters, related to the structure and the topology of the dye molecules, could be correlated with the apparent color removal rates at natural pH.

Which factors determine the wear rate of large-diameter metal-on-metal hip replacements? Multivariate analysis of two hundred and seventy-six components

BACKGROUND

Determining the relationship between clinical factors and engineering analysis of retrieved hip implants can help our understanding of the mechanism of device failure. This is particularly important for metal-on-metal hip arthroplasties because the most common cause of failure is unexplained. We sought to understand the variation in wear rates in a large series of retrieved metal-on-metal hip arthroplasty components.

METHODS

We prospectively recorded preoperative, intraoperative, and postoperative data to study the effect on both head and cup wear rates of the following variables: patient sex, cause of failure, manufacturer type, resurfacing or modular design, blood cobalt and chromium levels, edge-loading, femoral head size, and cup inclination angle. We analyzed 276 components (138 femoral head and acetabular cup couples) retrieved from failed metal-on-metal hip replacements.

RESULTS

We found a high rate of edge-loading (64%), but only forty-three (31%) of 138 hips had a cup inclination angle of >55°. Multivariate analysis showed that the most important factor responsible for the variation in wear rate was the presence or absence of edge-loading, even when adjusted for cup inclination angle. Strong positive correlations were found between acetabular cup and femoral head wear rates and between wear rates and both blood cobalt and chromium ion levels.

CONCLUSIONS

Multivariate analysis of nine factors found that edge-loading was the most important predictor of wear rate and occurred in two-thirds of failed metal-on-metal hip replacements. The majority did not have excessive cup inclination angles: 68% had an inclination angle of ≤55°. This finding, together with the relatively low median wear rate of the components in our study, suggests that cup position and/or wear rate may not be the only outcome related to failure of metal-on-metal hip replacements.

Quantification of the difference between 3D CT and plain radiograph for measurement of the position of medial unicompartmental knee replacements

The aim of this study was to quantify the differences in measurements obtained from 3D Computed Tomography and plain radiograph, for the positioning of the tibial component of the Oxford unicompartmental knee replacement. Post-operative 3D Computed Tomography data and plain radiographs (long antero-posterior (AP) and short lateral) were obtained for 28 knees of patients who had undergone medial unicompartmental knee replacement. Parameters of the orientation/positioning of the tibial component: Varus/valgus, posterior tibial slope and rotation were measured with both modalities. Bland-Altman plots were used to calculate the 1.96 standard deviation limits of agreement (LOA) between imaging modalities. Intra class correlation was used to assess inter-method and inter-rater reliability (>0.81 = very good reliability). Radiographs were less reliable in all parameters, when compared with 3D CT (intra class correlation coefficients: tibial rotation 0.94 vs 0.96, varus/valgus 0.76 vs 0.94, and posterior tibial slope 0.82 vs 0.92). The LOA were -4.9° to 3.4° for varus/valgus (bias -0.7°, one third >3° different); -4.9° to 0.1° for posterior tibial slope (bias -2.4°, one third >3° different); and -20.6° to 16.1° for rotation (bias -2.2°, one third >10° different). There was some disagreement between measurement by 3D Computed Tomography and plain radiograph for all three parameters of tibial component orientation, especially tibial rotation. This will be particularly relevant to research into the relationship between the accuracy of implant positioning/orientation and patient satisfaction/implant survival rates. This method offers a more reliable standard for the reporting of knee arthroplasty.

The relationship between the angle of version and rate of wear of retrieved metal-on-metal resurfacings: a prospective, CT-based study

We measured the orientation of the acetabular and femoral components in 45 patients (33 men, 12 women) with a mean age of 53.4 years (30 to 74) who had undergone revision of metal-on-metal hip resurfacings. Three-dimensional CT was used to measure the inclination and version of the acetabular component, femoral version and the horizontal femoral offset, and the linear wear of the removed acetabular components was measured using a roundness machine. We found that acetabular version and combined version of the acetabular and femoral components were weakly positively correlated with the rate of wear. The acetabular inclination angle was strongly positively correlated with the rate of wear. Femoral version was weakly negatively correlated with the rate of wear. Application of a threshold of > 5 μm/year for the rate of wear in order to separate the revisions into low or high wearing groups showed that more high wearing components were implanted outside Lewinnek's safe zone, but that this was mainly due to the inclination of the acetabular component, which was the only parameter that significantly differed between the groups. We were unable to show that excess version of the acetabular component alone or combined with femoral version was associated with an increase in the rate of wear based on our assessment of version using CT.

Evaluation of program performance and expenditures in a report of performance measures (RPM) via a case study of two Florida county tuberculosis programs

Health Department (HD) managers at both state and local levels are in desperate need of tools to assist in monitoring and evaluating programs. The purpose of this study is to assess the feasibility and utility of linking program performance scores and expenditures into a Report of Performance Measures (RPM). We analyzed secondary data on performance indicators, selected by HD staff, and expenditures, related to six surveillance activities, from two, similar, high-incidence, tuberculosis (TB) programs in Florida from 2002 to 2003. We compared the findings between the county HDs as an illustration of basic cost-effectiveness benchmarking, based on the cost-effectiveness grid. Data included here provide examples of: (1) two instances in which one county was operating relatively inefficiently compared to the other; (2) two instances in which performance and expenditures were similar for the counties; and (3) two instances in which one county spent more for higher performance scores than the other. These data illustrate how the RPM can be used to facilitate benchmarking, a basic evaluation tool. They also demonstrate ways to identify potential operational inefficiencies in a single time period and ultimately over time. It is thus likely to be a feasible and useful management tool.