The anterior cruciate ligament in murine post-traumatic osteoarthritis: markers and mechanics.

BACKGROUND: Knee joint injuries, common in athletes, have a high risk of developing post-traumatic osteoarthritis (PTOA). Ligaments, matrix-rich connective tissues, play important mechanical functions stabilising the knee joint, and yet their role post-trauma is not understood. Recent studies have shown that ligament extracellular matrix structure is compromised in the early stages of spontaneous osteoarthritis (OA) and PTOA, but it remains unclear how ligament matrix pathology affects ligament mechanical function. In this study, we aim to investigate both structural and mechanical changes in the anterior cruciate ligament (ACL) in a mouse model of knee trauma. METHODS: Knee joints were analysed following non-invasive mechanical loading in male C57BL/6 J mice (10-week-old). Knee joints were analysed for joint space mineralisation to evaluate OA progression, and the ACLs were assessed with histology and mechanical testing. RESULTS: Joints with PTOA had a 33-46% increase in joint space mineralisation, indicating OA progression. Post-trauma ACLs exhibited extracellular matrix modifications, including COL2 and proteoglycan deposition. Additional changes included cells expressing chondrogenic markers (SOX9 and RUNX2) expanding from the ACL tibial enthesis to the mid-substance. Viscoelastic and mechanical changes in the ACLs from post-trauma knee joints included a 20-21% decrease in tangent modulus at 2 MPa of stress, a decrease in strain rate sensitivity at higher strain rates and an increase in relaxation during stress-relaxation, but no changes to hysteresis and ultimate load to failure were observed. CONCLUSIONS: These results demonstrate that ACL pathology and viscoelastic function are compromised in the post-trauma knee joint and reveal an important role of viscoelastic mechanical properties for ligament and potentially knee joint health.

Delirium.

Delirium is an acute and fluctuating disorder characterized by a disturbance in attention and cognition. Delirium is underdiagnosed by clinicians, but there are excellent diagnostic tools using history and physical examination that can assist clinicians in making the diagnosis in multiple settings (ie, CAM, CAM-ICU, 3D-CAM, bCAM, 4AT, and UB-CAM). Delirium is caused by underlying medical conditions and is often multifactorial, so a full diagnosis requires a careful assessment for a wide range of underlying conditions. Physical examination has not been well studied in this regard, but still can provide useful clues to the clinician.

Cartilage-Specific Cre Recombinase Transgenes/Alleles in the Mouse.

Cartilage is a specialized skeletal tissue with a unique extracellular matrix elaborated by its resident cells, chondrocytes. The tissue presents in several forms, including growth plate and articular cartilage, wherein chondrocytes follow a differential differentiation program and have different fates. The induction of gene modifications in cartilage specifically relies on mouse transgenes and knockin alleles taking advantages of transcriptional elements primarily active in chondrocytes at a specific differentiation stage or in a specific cartilage type. These transgenes/alleles have been widely used to study the roles of specific genes in cartilage development, adult homeostasis, and pathology. As cartilage formation is critical for postnatal life, the inactivation or significant alteration of key cartilaginous genes is often neonatally lethal and therefore hampers postnatal studies. Gold standard approaches to induce postnatal chondrocyte-specific gene modifications include the Cre-loxP and Tet-ON/OFF systems. Selecting the appropriate promoter/enhancer sequences to drive Cre expression is of crucial importance and determines the specificity of conditional gain- or loss-of-function models. In this chapter, we discuss a series of transgenes and knockin alleles that have been developed for gene manipulation in cartilage and we compare their expression patterns and efficiencies.

Anatomical Distribution of Ochronotic Pigment in Alkaptonuric Mice is Associated with Calcified Cartilage Chondrocytes at Osteochondral Interfaces.

Alkaptonuria (AKU) is characterised by increased circulating homogentisic acid and deposition of ochronotic pigment in collagen-rich connective tissues (ochronosis), stiffening the tissue. This process over many years leads to a painful and severe osteoarthropathy, particularly affecting the cartilage of the spine and large weight bearing joints. Evidence in human AKU tissue suggests that pigment binds to collagen. The exposed collagen hypothesis suggests that collagen is initially protected from ochronosis, and that ageing and mechanical loading causes loss of protective molecules, allowing pigment binding. Schmorl's staining has previously demonstrated knee joint ochronosis in AKU mice. This study documents more comprehensively the anatomical distribution of ochronosis in two AKU mouse models (BALB/c Hgd-/-, Hgd tm1a-/-), using Schmorl's staining. Progression of knee joint pigmentation with age in the two AKU mouse models was comparable. Within the knee, hip, shoulder, elbow and wrist joints, pigmentation was associated with chondrons of calcified cartilage. Pigmented chondrons were identified in calcified endplates of intervertebral discs and the calcified knee joint meniscus, suggesting that calcified tissues are more susceptible to pigmentation. There were significantly more pigmented chondrons in lumbar versus tail intervertebral disc endplates (p = 0.002) and clusters of pigmented chondrons were observed at the insertions of ligaments and tendons. These observations suggest that loading/strain may be associated with increased pigmentation but needs further experimental investigation. The calcified cartilage may be the first joint tissue to acquire matrix damage, most likely to collagen, through normal ageing and physiological loading, as it is the first to become susceptible to pigmentation.

Post-traumatic osteoarthritis development is not modified by postnatal chondrocyte deletion of Ccn2.

CCN2 is a matricellular protein involved in several crucial biological processes. In particular, CCN2 is involved in cartilage development and in osteoarthritis. Ccn2 null mice exhibit a range of skeletal dysmorphisms, highlighting its importance in regulating matrix formation during development; however, its role in adult cartilage remains unclear. The aim of this study was to determine the role of CCN2 in postnatal chondrocytes in models of post-traumatic osteoarthritis (PTOA). Ccn2 deletion was induced in articular chondrocytes of male transgenic mice at 8 weeks of age. PTOA was induced in knees either surgically or non-invasively by repetitive mechanical loading at 10 weeks of age. Knee joints were harvested, scanned with micro-computed tomography and processed for histology. Sections were stained with Toluidine Blue and scored using the Osteoarthritis Research Society International (OARSI) grading system. In the non-invasive model, cartilage lesions were present in the lateral femur, but no significant differences were observed between wild-type (WT) and Ccn2 knockout (KO) mice 6 weeks post-loading. In the surgical model, severe cartilage degeneration was observed in the medial compartments, but no significant differences were observed between WT and Ccn2 KO mice at 2, 4 and 8 weeks post-surgery. We conclude that Ccn2 deletion in chondrocytes does not modify the development of PTOA in mice, suggesting that chondrocyte expression of CCN2 in adults is not a crucial factor in protecting cartilage from the degeneration associated with PTOA.This article has an associated First Person interview with the first author of the paper.

Conditional targeting in mice reveals that hepatic homogentisate 1,2-dioxygenase activity is essential in reducing circulating homogentisic acid and for effective therapy in the genetic disease alkaptonuria.

Alkaptonuria is an inherited disease caused by homogentisate 1,2-dioxygenase (HGD) deficiency. Circulating homogentisic acid (HGA) is elevated and deposits in connective tissues as ochronotic pigment. In this study, we aimed to define developmental and adult HGD tissue expression and determine the location and amount of gene activity required to lower circulating HGA and rescue the alkaptonuria phenotype. We generated an alkaptonuria mouse model using a knockout-first design for the disruption of the HGD gene. Hgd tm1a -/- mice showed elevated HGA and ochronosis in adulthood. LacZ staining driven by the endogenous HGD promoter was localised to only liver parenchymal cells and kidney proximal tubules in adulthood, commencing at E12.5 and E15.5 respectively. Following removal of the gene trap cassette to obtain a normal mouse with a floxed 6th HGD exon, a double transgenic was then created with Mx1-Cre which conditionally deleted HGD in liver in a dose dependent manner. 20% of HGD mRNA remaining in liver did not rescue the disease, suggesting that we need more than 20% of liver HGD to correct the disease in gene therapy. Kidney HGD activity which remained intact reduced urinary HGA, most likely by increased absorption, but did not reduce plasma HGA nor did it prevent ochronosis. In addition, downstream metabolites of exogenous 13C6-HGA, were detected in heterozygous plasma, revealing that hepatocytes take up and metabolise HGA. This novel alkaptonuria mouse model demonstrated the importance of targeting liver for therapeutic intervention, supported by our observation that hepatocytes take up and metabolise HGA.

Concentric lamellae - novel microanatomical structures in the articular calcified cartilage of mice.

The structure, ultrastructure and function of hyaline articular cartilage (HAC) and subchondral bone (SCB), and their involvement in the pathogenesis of osteoarthritis (OA) have been extensively researched. However, much less attention has been focused on the intervening tissue, articular calcified cartilage (ACC) and its role in the initiation and progression of OA. Using both light microscopy (LM) and transmission electron microscopy (TEM), a study of ACC in wild type (WT) mice, and mice with genetic osteoarthropathies (AKU) was undertaken to further understand the role played by ACC in the early stages of OA.Tibio-femoral joints were obtained from BALB/c WT and BALB/c AKU mice aged between 7 and 69 weeks. One joint was processed for routine histological analysis. The tip of the medial femoral condyle (MFC), which contained HAC, ACC, and SCB, was dissected from the contra-lateral joint and processed for TEM.In WT and AKU mice novel microanatomical structures, designated concentric lamellae, were identified surrounding chondrocytes in the ACC. The lamellae appeared to be laid down in association with advancement of the tidemark indicating they may be formed during calcification of cartilage matrix. The lamellae were associated with hypertrophic chondrocytes throughout the ACC.Novel microanatomical structures, termed concentric lamellae, which were present around hypertrophic chondrocytes in the ACC are described for the first time. Their apparent association with mineralisation, advancement of the tidemark, and greater abundance in a model of osteoarthropathy indicate their formation could be important in the pathogenesis of OA and AKU.

Assessing faculty attitudes after participation in an interprofessional teaching scholars programme.

Promoting interprofessional education (IPE) and practice is a priority in academic health centres; however, implementation of IPE can be challenging. Recognizing the need for faculty development in teaching, and specifically IPE, the University of California, Davis Schools of Health launched the Interprofessional Teaching Scholars Program (ITSP) in 2014. Two cohorts of 11 faculty scholars each completed the nine-month programme and participated in this longitudinal comparative study in which pre- and post-assessments using a validated survey instrument were administered to measure changes in faculty attitudes towards IPE and collaborative practice. There was a statistically significant increase in the summated scores on all three of the subscales: Attitudes Towards Interprofessional Health Care Teams, Attitudes Towards IPE, and Attitudes Towards Interprofessional Learning in the Academic Setting. The results suggest that the ITSP was associated with positive changes in faculty attitudes related to interprofessional collaboration and teamwork.

Nitisinone Arrests but Does Not Reverse Ochronosis in Alkaptonuric Mice.

Alkaptonuria (AKU) is an ultrarare autosomal recessive disorder resulting from a deficiency of homogentisate 1,2 dioxygenase (HGD), an enzyme involved in the catabolism of phenylalanine and tyrosine. Loss of HGD function prevents metabolism of homogentisic acid (HGA), leading to increased levels of plasma HGA and urinary excretion. Excess HGA becomes deposited in collagenous tissues and subsequently undergoes polymerisation, principally in the cartilages of loaded joints, in a process known as ochronosis. This results in an early-onset, devastating osteoarthropathy for which there is currently no effective treatment. We recently described the natural history of ochronosis in a murine model of AKU, demonstrating that deposition of ochronotic pigment begins very early in life and accumulates with age. Using this model, we were able to show that lifetime treatment with nitisinone, a potential therapy for AKU, was able to completely prevent deposition of ochronotic pigment. However, although nitisinone has been shown to inhibit ochronotic deposition, whether it can also facilitate removal of existing pigment has not yet been examined. We describe here that midlife administration of nitisinone to AKU mice arrests further deposition of ochronotic pigment in the tibiofemoral joint, but does not result in the clearance of existing pigment. We also demonstrate the dose-dependent response of plasma HGA to nitisinone, highlighting its efficacy for personalised medicine, where dosage can be tailored to the individual AKU patient.

Faculty development to enhance humanistic teaching and role modeling: a collaborative study at eight institutions.

BACKGROUND: There is increased emphasis on practicing humanism in medicine but explicit methods for faculty development in humanism are rare. OBJECTIVE: We sought to demonstrate improved faculty teaching and role modeling of humanistic and professional values by participants in a multi-institutional faculty development program as rated by their learners in clinical settings compared to contemporaneous controls. DESIGN: Blinded learners in clinical settings rated their clinical teachers, either participants or controls, on the previously validated 10-item Humanistic Teaching Practices Effectiveness (HTPE) questionnaire. PARTICIPANTS: Groups of 7-9 participants at 8 academic medical centers completed an 18-month faculty development program. Participating faculty were chosen by program facilitators at each institution on the basis of being promising teachers, willing to participate in the longitudinal faculty development program. INTERVENTION: Our 18-month curriculum combined experiential learning of teaching skills with critical reflection using appreciative inquiry narratives about their experiences as teachers and other reflective discussions. MAIN MEASURES: The main outcome was the aggregate score of the ten items on the questionnaire at all institutions. KEY RESULTS: The aggregate score favored participants over controls (P = 0.019) independently of gender, experience on faculty, specialty area, and/or overall teaching skills. CONCLUSIONS: Longitudinal, intensive faculty development that employs experiential learning and critical reflection likely enhances humanistic teaching and role modeling. Almost all participants completed the program. Results are generalizable to other schools.

Ochronotic osteoarthropathy in a mouse model of alkaptonuria, and its inhibition by nitisinone.

BACKGROUND: Alkaptonuria (AKU) is a rare metabolic disease caused by deficiency of homogentisate 1,2 dioxygenase, an enzyme involved in tyrosine catabolism, resulting in increased circulating homogentisic acid (HGA). Over time HGA is progressively deposited as a polymer (termed ochronotic pigment) in collagenous tissues, especially the cartilages of weight bearing joints, leading to severe joint disease. OBJECTIVES: To characterise blood biochemistry and arthropathy in the AKU mouse model (Hgd-/-). To examine the therapeutic effect of long-term treatment with nitisinone, a potent inhibitor of the enzyme that produces HGA. METHODS: Lifetime levels of plasma HGA from AKU mice were measured by high-performance liquid chromatography (HPLC). Histological sections of the knee joint were examined for pigmentation. The effect of nitisinone treatment in both tissues was examined. RESULTS: Mean (±SE) plasma HGA levels were 3- to 4-fold higher (0.148±0.019 mM) than those recorded in human AKU. Chondrocyte pigmentation within the articular cartilage was first observed at 15 weeks, and found to increase steadily with mouse age. Nitisinone treatment reduced plasma HGA in AKU mice throughout their lifetime, and completely prevented pigment deposition. CONCLUSIONS: The AKU mouse was established as a model of both the plasma biochemistry of AKU and its associated arthropathy. Early-stage treatment of AKU patients with nitisinone could prevent the development of associated joint arthropathies. The cellular pathology of ochronosis in AKU mice is identical to that observed in early human ochronosis and thus is a model in which the early stages of joint pathology can be studied and novel interventions evaluated.

Establishing electronic health record competency testing for first-year residents.

BACKGROUND: Despite widespread use of electronic health records (EHRs), it is unclear whether residents possess the EHR skills to perform required tasks. OBJECTIVE: We assessed first-year residents' skills on specific EHR tasks. METHODS: Incoming residents were required to participate in EHR training before starting clinical rotations. The training team developed an assessment tool for 19 EHR tasks. Senior residents used a structured template to assess interns. RESULTS: For ambulatory workflow skills, most participants (range, 70%-100%) demonstrated competence. The 3 skills for which interns needed the most assistance were (1) creating and routing a result note (17 of 68, 25%), (2) deleting a medication or changing a dose in reconciling medications (10 of 68, 15%), and (3) finding results for the past 90 days (10 of 68, 15%). For inpatient workflow skills, most interns (range, 63%-100%) demonstrated competence. The 3 skills in which interns needed the most assistance were (1) placing a referral order at discharge (23 of 68, 34%), (2) finding a temperature on a flow sheet and trending it over time (14 of 68, 21%), and (3) creating a discharge summary, having it reviewed, and forwarding it to the primary care physician (14 of 68, 21%). CONCLUSIONS: Our results should help EHR training teams at other institutions to better understand the strengths and weakness of EHR training approaches and to target training on tasks with the greatest performance deficits as well as toward underperforming individuals or groups.

An academic-community partnership to improve care for the underserved.

Despite the need for a robust primary care workforce, the number of students and residents choosing general internal medicine careers continues to decline. In this article, the authors describe their efforts at the University of California, Davis School of Medicine to bolster interest in internal medicine careers and improve the quality of care for medically underserved populations through a tailored third-year residency track developed in partnership with the Sacramento County Department of Health and Human Services. The Transforming Education and Community Health (TEACH) Program improves continuity of care between inpatient and outpatient settings, creates a new multidisciplinary teaching clinic in the Sacramento County health system, and prepares residents to provide coordinated care for vulnerable populations. Since its inception in 2005, 25 residents have graduated from the TEACH Program. Compared with national rates, TEACH graduates are more likely to practice general internal medicine and to practice in medically underserved settings. TEACH residents report high job satisfaction and provide equal or higher-quality diabetes care than that indicated by national benchmarks. The authors provide an overview of the TEACH Program, including curriculum details, preliminary outcomes, barriers to continued and expanded implementation, and thoughts about the future of the program.

Effects of race and ethnicity on the incidence of venous thromboembolism.

Although there is strong evidence that the prevalence of venous thrombo-embolism (VTE) varies significantly among different ethnic/racial groups, the genetic, physiologic and/or clinical basis for these differences remain largely undefined. African-American patients have a significantly higher rate of incident VTE, particularly following exposure to a provoking risk factor such as surgery, medical illness, trauma, etc. In addition, African-Americans are more likely to be diagnosed with pulmonary embolism (PE) than deep-vein thrombosis (DVT) compared to Caucasian and other racial groups. On the other extreme, Asians/Pacific Islanders have a 70% lower prevalence of VTE and this is true for both idiopathic VTE and provoked, or 'secondary', VTE. Hispanics have a significantly lower prevalence of VTE compared to Caucasians, but higher than Asians/Pacific Islanders. The incidence of recurrent VTE varies depending on gender, type of thromboembolic event and race. Further research is needed in order to determine the fundamental differences between racial/ethnic groups that explain the observed differences in the prevalence of VTE. Race/ethnicity should be considered an important factor in the risk-stratification of patients with suspected VTE or patients at some risk for developing VTE.