Nuclear protein-1 is the common link for pathways activated by aging and obesity in chondrocytes: A potential therapeutic target for osteoarthritis.

Pathways leading to osteoarthritis (OA) are diverse depending on the risk factors involved; thus, developing OA therapeutics has been challenging. Here we report that nuclear protein-1 (Nupr1), a stress-inducible protein/transcription factor, is activated by pathways associated with obesity and aging in chondrocytes. Treatment of human chondrocytes with free fatty acids (palmitate and oleate; a model for high-fat diet/obesity) induced PERK signaling and increased expression of caspase-3, TRB3, and Nupr1. On the other hand, treatment of chondrocytes with menadione (oxidative stress inducer) induced oxidation of IRE1, activated antioxidant response (higher Nrf2 expression), and increased expression of Nupr1 and matrix metalloproteinases. Experimental OA was induced by destabilization of the medial meniscus (DMM) in the knee joints of Nupr1+/+ and Nupr1-/- mice. Loss of Nupr1 expression reduced the severity of cartilage lesions in this model. Together, our findings suggest that Nupr1 is a common factor activated by signaling pathways activated by obesity (ER stress) and age (oxidative stress) and a potential drug target for OA resulting from various risk factors.

Transferring With TACT: A Novel Tool to Standardize Transfer Decisions From a Level IV NICU.

BACKGROUND: Neonatal patients who no longer require level IV neonatal intensive care unit care are transferred to less acute levels of care. Standardized assessment tools have been shown to be beneficial in the transfer of patient care. However, no standardized tools were available to assist neonatal providers in the assessment and communication of the infants needs at transfer. PURPOSE: The purpose was to develop a Transfer Assessment and Communication Tool (TACT) that guides provider decision making in the transfer of infants from a level IV neonatal intensive care unit to a less acute level of care within a regionalized healthcare system. METHODS: Phase 1 included developing the first draft of the TACT using retrospective data, known variables from published literature, and study team expertise. In phase 2, the final draft of the TACT was created through feedback from expert neonatal providers in the regionalized care system using e-Delphi methodology. RESULTS: The first draft of the TACT, developed in phase 1, included 36 characteristics. In phase 2, nurses, nurse practitioners, and physician experts representing all levels of newborn care participated in 4 e-Delphi surveys to develop the final draft of the TACT, which included 74 weighted characteristics. IMPLICATIONS FOR PRACTICE AND RESEARCH: Potential benefits of the TACT include improved communication across healthcare teams, reduced risk for readmission, and increased caregiver visitation. The next steps are to validate the TACT for use either retrospectively or in real time, including characteristic weights, before implementation of this tool in the clinical setting.

Septicemia Due to Listeria monocytogenes Infection: A Systematic Review and Meta-Analysis.

Listeriosis is a rare bacterial infection associated with foodborne illness that can result in septicemia, a serious acute outcome. Sepsis is responsible for one in three deaths during hospitalization. The objective of this study was to conduct a systematic review and meta-analysis to estimate the proportion of Listeria monocytogenes infections resulting in septicemia. PubMed, Embase, Scopus, and Web of Science were searched from January 1, 2000, to April 1, 2018, for epidemiological studies that assessed studies focusing on L. monocytogenes infections with the outcome of septicemia. Articles in English, Spanish, and Portuguese using case-control, cohort, or outbreak studies reporting measures of association between L. monocytogenes and septicemia were included. Bias and heterogeneity were assessed using univariate meta-regression for region, sample size, study design, and report method. Nineteen articles were eligible for inclusion post-screening, the majority of which were conducted in Europe (n = 15); utilized a retrospective cohort design (n = 16); and collected data via routine or laboratory surveillance methods (n = 10). Prevalence of sepsis ranged from 4.2% to 100% among study populations of 6 to 1374 individuals. Overall, the proportion of listeriosis cases that developed sepsis was 46% (95% confidence interval [CI] 31.0-61.0%); for neonatal cases, 21.3% (95% CI 11.0-31.6%); and for maternal and neonatal cases, 18.8% (95% CI 10.7-26.8%). The heterogeneity was high for overall and group meta-analyses, but it could not be explained by the subanalyses for the overall proportion, whereas for neonatal, and neonatal and maternal cases combined, China had a significantly lower proportion than Europe and the United States. Septicemia following L. monocytogenes infection is a severe acute complication with 31-61% rate found overall; however, greater delineation of demographic data is needed to determine important risk factors. Future research should aim to address the gaps in knowledge in the long-term outcomes of sepsis from L. monocytogenes infection, and whether these outcomes differ from those due to other infections.

Complications Associated with Foodborne Listeriosis: A Scoping Review.

Listeria monocytogenes is a relatively rare but highly pathogenic bacterium that can cause foodborne infections. In the United States there are ∼1600 cases per year, 94% of which result in hospitalizations and 20% in deaths. Per-case burden is high because the disease also causes serious complications, including sepsis, encephalitis, meningitis, miscarriage, and stillbirth. The disease burden of L. monocytogenes is underestimated because some of these acute complications can also result in long-term outcomes. In this article, we conducted a scoping review of L. monocytogenes complications and longer term outcomes from articles published between 2000 and 2018. Search terms were developed for four major databases (PubMed, Scopus, Web of Science, and Embase) as well as gray literature and hand searches of review articles. We follow standard scoping review methodology and assessment. Out of 10,618 unique articles originally identified, 115 articles were included, representing 49 unique outcomes. The majority of studies were cohort designs (n = 67) and conducted in the United States or Europe (n = 98). Four major outcome groupings were death, neurological disorders, sepsis, and congenital infection. This study identifies substantial research on the common acute complications of L. monocytogenes and few long-term consequences of L. monocytogenes. We identify the need for additional studies to determine the longer term impacts of these acute complications.

Enteric Pathogens and Reactive Arthritis: Systematic Review and Meta-Analyses of Pathogen-Associated Reactive Arthritis.

The objective of this systematic review and meta-analysis was to estimate the proportion of postinfectious reactive arthritis (ReA) after bacterial enteric infection from one of four selected pathogens. We collected studies from PubMed, Web of Science, and Embase, which assessed the proportion of postinfectious ReA published from January 1, 2000 to April 1, 2018. Papers were screened independently by title, abstract, and full text; papers in English, Spanish, and Portuguese utilizing a case-control (CC) or cohort study design, with a laboratory confirmed or probable acute bacterial enteric infection and subsequent ReA, were included. The proportion of ReA cases was pooled between and across pathogens. Factors that can induce study heterogeneity were explored using univariate meta-regression, including region, sample size, study design, and ReA case ascertainment. Twenty-four articles were included in the final review. The estimated percentage of cases across studies describing Campylobacter-associated ReA (n = 11) was 1.71 (95% confidence interval [CI] 0.49-5.84%); Salmonella (n = 17) was 3.9 (95% CI 1.6-9.1%); Shigella (n = 6) was 1.0 (95% CI 0.2-4.9%); and Yersinia (n = 7) was 3.4 (95% CI 0.8-13.7%). Combining all four pathogens, the estimated percentage of cases that developed ReA was 2.6 (95% CI 1.5-4.7%). Due to high heterogeneity reflected by high I2 values, results should be interpreted with caution. However, the pooled proportion developing ReA from studies with sample sizes (N) <1000 were higher compared with N > 1000 (6% vs. 0.3%), retrospective cohort studies were lower (1.1%) compared with CC or prospective cohorts (6.8% and 5.9%, respectively), and those where ReA cases are identified through medical record review were lower (0.3%) than those identified by a specialist (3.9%) or self-report (12%). The estimated percentage of people who developed ReA after infection with Campylobacter, Salmonella, Shigella, or Yersinia is relatively low (2.6). In the United States, this estimate would result in 84,480 new cases of ReA annually.

Chronic Gastrointestinal and Joint-Related Sequelae Associated with Common Foodborne Illnesses: A Scoping Review.

To strengthen the burden estimates for chronic sequelae of foodborne illness, we conducted a scoping review of the current literature for common foodborne pathogens and their associated sequelae. We aim to describe the current literature and gaps in knowledge of chronic sequelae associated with common foodborne illnesses. A comprehensive search was conducted in PubMed, EMBASE, and Web of Science for peer-reviewed articles published January 1, 2000 to April 1, 2018. Articles available in English, of any epidemiological study design, for 10 common foodborne pathogens (Campylobacter, Salmonella, Escherichia coli, Listeria, Shigella, Cryptosporidium, Cyclospora, Giardia, Yersinia, and norovirus) and their associated gastrointestinal (GI)- and joint-related sequelae were included. Of the 6348 titles screened for inclusion, 380 articles underwent full-text review; of those 380, 129 were included for data extraction. Of the bacterial pathogens included in the search terms, the most commonly reported were Salmonella (n = 104) and Campylobacter (n = 99); E. coli (n = 55), Shigella (n = 49), Yersinia (n = 49), and Listeria (n = 15) all had fewer results. Norovirus was the only virus included in our search, with 28 article that reported mostly GI-related sequelae and reactive arthritis (ReA) reported once. For parasitic diseases, Giardia (n = 26) and Cryptosporidium (n = 18) had the most articles, and no results were found for Cyclospora. The most commonly reported GI outcomes were irritable bowel syndrome (IBS; n = 119) and inflammatory bowel disease (n = 29), and ReA (n = 122) or "joint pain" (n = 19) for joint-related sequelae. Salmonella and Campylobacter were most often associated with a variety of outcomes, with ReA (n = 34 and n = 27) and IBS (n = 17 and n = 20) reported most often. This scoping review shows there are still a relatively small number of studies being conducted to understand specific pathogen/outcome relationships. It also shows where important gaps in the impact of chronic sequelae from common foodborne illnesses still exist and where more focused research would best be implemented.

Clostridium difficile Enterocolitis in a Captive Geoffroy's Spider Monkey (Ateles geoffroyi) and Common Marmosets (Callithrix jacchus).

Clostridium difficile is a well-documented cause of enterocolitis in several species, including humans, with limited documentation in New World nonhuman primates. We report several cases of C. difficile-associated pseudomembranous enterocolitis, including a case in a Geoffroy's spider monkey (Ateles geoffroyi) and several cases in common marmosets (Callithrix jacchus). The histologic lesions included a spectrum of severity, with most cases characterized by the classic "volcano" lesions described in humans and several other animal species. C. difficile was isolated from the colon of the spider monkey, while the presence of toxin A or toxin B or of the genes of toxin A or B by polymerase chain reaction served as corroborative evidence in several affected marmosets. C. difficile should be considered a cause of enterocolitis in these species.

Relationship between the extent of vascular injury and the evolution of surgically induced osteochondrosis lesions in a piglet model.

Ostechondritis dissecans (OCD) is an orthopaedic disease characterized by formation of osteochondral defects in developing joints. Epiphyseal cartilage necrosis (osteochondrosis [OC]) caused by focal failure of vascular supply is the known precursor lesion of OCD, but it remains to be established how the severity of vascular failure drives lesion healing or progression. In the current study we have implemented a novel piglet model of induced osteochondrosis of the lateral trochlear ridge of the femur to determine the role that the extent of ischemia plays in the development and progression of OC/OCD lesions. Ten 4-week-old Yorkshire piglets underwent surgical interruption of the vascular supply to the entirety (n = 4 pigs) or the distal half (n = 6 pigs) of the lateral trochlear ridge of the femur. At 2, 6, and 12 weeks postoperatively, distal femora were evaluated by magnetic resonance imaging (MRI) to determine the fate of induced OC lesions. At 12 weeks, piglets were euthanized, and the surgical sites were examined histologically. After complete devascularization, lesion size increased between the 6- and 12-week MRI by an average of 24.8 mm2 (95% CI: [-2.2, 51.7]; p = 0.071). During the same period, lesion size decreased by an average of 7.6 mm2 (95% CI: [-24.5, 19.4]; p = 0.83) in piglets receiving partial devascularization. At 12 weeks, average ± SD lesion size was larger (p<0.001) in piglets undergoing complete (73.5 ± 17.6 mm2) vs. partial (16.5 ± 9.8 mm2) devascularization. Our study demonstrates how the degree of vascular interruption determines lesion size and likelihood of healing in a large animal model of trochlear OC.

Epiphyseal cartilage vascular architecture at the distal humeral osteochondritis dissecans predilection site in juvenile pigs.

Failure of endochondral ossification due to interruption of the vascular supply to the epiphyseal cartilage is a critical step in the development of osteochondritis dissecans (OCD). Herein we describe the vascular architecture of the distal humeral epiphyseal cartilage in pigs and identify characteristic features that have been associated with sites predisposed to OCD development across species. Distal humeral specimens were harvested from pigs (n = 5, ages = 1, 10, 18, 30, and, 42 days old) and imaged at 9.4T magnetic resonance imaging (MRI) using a 3D gradient recalled echo sequence. The MRI data were processed using a quantitative susceptibility mapping (QSM) pipeline to visualize the vascular architecture. Specimens were also evaluated histologically to identify the presence of ischemic epiphyseal cartilage necrosis (osteochondrosis [OC]-latens) and associated failure of endochondral ossification (OC-manifesta). The QSM data enabled visualization of two distinct vascular beds arising from the perichondrium at the lateral and medial aspects of the distal humeral epiphysis. Elongated vessels originating from these beds coursed axially to supply the lateral and medial thirds of epiphyseal cartilage. At 18 days of age and older, a shift from perichondrial to transosseous blood supply was noted axially, which appeared more pronounced on the lateral side. This shift coincided with histologic identification of OC-latens (30- and 42-day-old specimens) and OC-manifesta (18- and 42-day-old specimens) lesions in the corresponding regions. The vascular anatomy and its evolution at the distal humeral epiphysis closely resembles that previously reported at predilection sites of knee OCD, suggesting a shared pathophysiology between the knee and elbow joints.

Detection of early metaphyseal changes in a piglet model of Legg-Calvé-Perthes disease using quantitative mapping of MRI relaxation times.

Legg-Calvé-Perthes disease (LCPD) is a childhood hip disorder characterized by ischemic injury to the epiphysis of the femoral head, but changes to the metaphysis have also been implicated in its pathogenesis. Quantitative magnetic resonance imaging (MRI) relaxation time mapping techniques are potentially useful to detect injury in LCPD, but studies to date have focused on the epiphysis. The purpose of this study was to assess whether T2, T1ρ, adiabatic T1ρ, and adiabatic T2ρ relaxation times can detect early metaphyseal changes in an LCPD piglet model. Complete epiphyseal ischemia of one femoral head was surgically induced and confirmed using contrast-enhanced MRI in n = 10 6-week-old piglets; the contralateral side was unoperated. The bilateral hips were imaged 1 week after surgery in vivo at 3T MRI using relaxation time mapping and contrast-enhanced MRI. Relaxation times and thicknesses of the metaphyseal primary and secondary spongiosa were measured and compared between the ischemic and contralateral-control femoral heads using paired t-tests. In the ischemic femoral heads, T2 relaxation times were significantly increased in the primary spongiosa (6.7 ± 9.8 ms, p = 0.029), and T2, T1ρ, adiabatic T1ρ, and adiabatic T2ρ relaxation times were significantly decreased in the secondary spongiosa (respectively: -13.3 ± 9.3 ms, p = 0.013; -32 ± 23 ms, p < 0.001; -43 ± 41 ms, p = 0.009; and -39 ± 13 ms, p < 0.001). The secondary spongiosa thickness was also significantly decreased in the ischemic femoral heads (p < 0.001). In conclusion, T2, T1ρ, adiabatic T1ρ, and adiabatic T2ρ relaxation time mapping techniques can detect early changes in the metaphysis following ischemic injury to the epiphysis of the femoral head in a piglet model of LCPD.

Development of the Valued Living Questionnaire - Comprehension Support version (VLQ-CS) and validation in adults with acquired brain injury.

PURPOSE: Valued living (acting in accordance with personal values) is associated with better outcomes after acquired brain injury (ABI), but its measurement using the Valued Living Questionnaire (VLQ) may not be valid due to comprehension errors relating to structure and content. We aimed to modify the VLQ to improve its accessibility and evaluate construct validity and reliability in an ABI cohort. MATERIALS AND METHODS: Adaptations made in the VLQ - Comprehension Support version (VLQ-CS) used established communication support methods and addressed common comprehension errors. 103 community-dwelling participants (34% female; mean age 52.17, range 19-79) with ABI (66% stroke, 16% TBI, 18% other) completed the VLQ-CS, and measures of convergent (valued living, mood, wellbeing, psychological inflexibility) and divergent validity (subjective memory). Test-retest reliability was evaluated with repeated administrations 6-8 weeks apart for a subset of participants (n = 44), using Intraclass Correlation Coefficients (ICCs). RESULTS: Convergent validity was supported; VLQ-CS scores were positively correlated with measures of valued living (r=.60-.65) and wellbeing (r=.64-.67), and negatively correlated with depression (r=-0.56-.58), anxiety (r=-0.35-.38) and psychological inflexibility (r=-0.37-.41). Divergent validity was marginal (r=-0.29). Test-retest reliability was good for the VLQ-CS Composite score (ICC=.80). CONCLUSIONS: The VLQ-CS shows promise as a valid, reliable measure of valued living post-ABI. Future research should extend to neurotypical and other clinical populations.

Valued living or values-based action is associated with better functional and psychosocial outcomes after acquired brain injury (ABI) and is therefore an important target for intervention.Measurement of valued living needs to be clear, easily understood, and relevant for people with cognitive and communication impairments associated with ABI and other conditions.The Valued Living Questionnaire ­ Comprehension Support version (VLQ-CS) was developed to optimise accessibility and reduce comprehension errors.The VLQ-CS is valid, reliable and fit-for-purpose as a measure of valued living for people with ABI.

Career Choices and Experiences in Role Transition: A Multistate Survey of Pediatric-Focused Hospital-Based Nurse Practitioners.

INTRODUCTION: We examined factors influencing pediatric hospital-based APPs' career decisions and described the transition to practice experiences. METHOD: We conducted a cross-sectional, descriptive electronic survey using a novel instrument to examine APP career decisions and transition to practice experiences among APPs in four Southeastern children's hospitals. RESULTS: There were 158 respondents composed of family nurse practitioners (NPs) (30%), primary care pediatric NPs (24%), and acute care pediatric NPs (18%). APPs chose their career to further their education (46%) and because of interest in pediatrics (18%). Most APPs had experience in pediatrics on APP graduation and were well prepared for the role (47%) and to care for pediatric patients (56%). Nearly two-thirds of APPs had an orientation. DISCUSSION: Early exposure to pediatrics influenced APP career choices and increased career preparedness. Although most APPs had an orientation, future studies should assess the impact of orientation on patient, professional, and organizational outcomes.

Naturally occurring osteochondrosis latens lesions identified by quantitative and morphological 10.5 T MRI in pigs.

Juvenile osteochondritis dissecans (JOCD) is a pediatric orthopedic disorder that involves the articular-epiphyseal cartilage complex and underlying bone. Clinical disease is often characterized by the presence of radiographically apparent osteochondral flaps and fragments. The existence of early JOCD lesions (osteochondrosis latens [OCL] and osteochondrosis manifesta [OCM]) that precede the development of osteochondral flaps and fragments is also well recognized. However, identification of naturally occurring OCL lesions (confined to cartilage) using noninvasive imaging techniques has not yet been accomplished. We hypothesized that 10.5 T magnetic resonance imaging (MRI) can identify naturally occurring OCL lesions at predilection sites in intact joints of juvenile pigs. Unilateral elbows and knees (stifles) were harvested from three pigs aged 4, 8, and 12 weeks, and scanned in a 10.5 T MRI to obtain morphological 3D DESS images, and quantitative T2 and T1ρ relaxation time maps. Areas with increased T2 and T1ρ relaxation times in the articular-epiphyseal cartilage complex were identified in 1/3 distal femora and 3/3 distal humeri and were considered suspicious for OCL or OCM lesions. Histological assessment confirmed the presence of OCL or OCM lesions at each of these sites and failed to identify additional lesions. Histological findings included necrotic vascular profiles associated with areas of chondronecrosis either confined to the epiphyseal cartilage (OCL, 4- and 8-week-old specimens) or resulting in a delay in endochondral ossification (OCM, 12-week-old specimen). Future studies with clinical MR systems (≤7 T) are needed to determine whether these MRI methods are suitable for the in vivo diagnosis of early JOCD lesions in humans.

Pathology in Practice.

In collaboration with the American College of Veterinary Pathologists.

Overexpression of Peroxiredoxin 3 in Cartilage Reduces the Severity of Age-Related Osteoarthritis But Not Surgically Induced Osteoarthritis in Mice.

OBJECTIVE: The study objective was to determine whether overexpression of the mitochondrial antioxidant peroxidase, peroxiredoxin 3 (Prx3), reduces the severity of osteoarthritis (OA) in mice. METHODS: Age-related OA (age 18 and 24 months) and OA induced by destabilization of the medial meniscus (DMM at age 6 months) were assessed in male mice that overexpress a human Prdx3 transgene encoding the Prx3 protein. Lox-stop-lox-Prdx3 (iPrdx3) mice were crossed with aggrecan-CreERT2 mice to produce iPrdx3AgCreERT2 or with Col2Cre to produce iPrdx3Col2Cre mice. Germline transgenics (Prdx3Tg) were also evaluated. Prx3 protein level was assessed by immunoblotting and functionally after induction of elevated mitochondrial hydrogen peroxide (H2 O2 ) using menadione. Histological sections of stifle joints were scored for cartilage damage (Articular Cartilage Structure score [ACS]), osteophytes, and synovial hyperplasia and were evaluated by histomorphometry. RESULTS: Overexpression of Prx3 maintained mitochondrial membrane integrity and inhibited p38 phosphorylation in the presence of elevated H2 O2 . ACS scores of 18-month-old iPrdx3AgCreERT2 mice (mean ± SD, 4.88 ± 5.05) were significantly lower than age-matched iPrdx3 controls (11.75 ± 6.34, P = 0.002) and trended lower in the 18-month Prdx3Tg group (P = 0.14), whereas no significant differences between experimental and control groups at 24 months of age or in OA induced by DMM surgery were noted. Osteophyte scores trended lower in the 18-month-old Prdx3Tg group (P = 0.09) and at 24 months in the iPrdx3Col2Cre mice (P = 0.05). There were no significant group differences in synovial hyperplasia or histomorphometric measures. CONCLUSION: Overexpression of the mitochondrial peroxidase Prx3 reduced the severity of age-related OA, but not at advanced ages and not in DMM-induced OA in younger mice.

T1ρ and T2 mapping detect acute ischemic injury in a piglet model of Legg-Calvé-Perthes disease.

This study investigated the sensitivity of T1ρ and T2 relaxation time mapping to detect acute ischemic injury to the secondary ossification center (SOC) and epiphyseal cartilage of the femoral head in a piglet model of Legg-Calvé-Perthes disease. Six piglets underwent surgery to induce global right femoral head ischemia and were euthanized 48 h later. Fresh operated and contralateral-control femoral heads were imaged ex vivo with T1, T2, and T1ρ mapping using a 9.4T magnetic resonance imaging scanner. The specimens were imaged a second time after a freeze/thaw cycle and then processed for histology. T1, T2, and T1ρ measurements in the SOC, epiphyseal cartilage, articular cartilage, and metaphysis were compared between operated and control femoral heads using paired t tests. The effects of freeze/thaw, T1ρ spin-lock frequency, and fat saturation were also investigated. Five piglets with histologically confirmed ischemic injury were quantitatively analyzed. T1ρ was increased in the SOC (101 ± 15 vs. 73 ± 16 ms; p = 0.0026) and epiphyseal cartilage (84.9 ± 9.2 vs. 74.3 ± 3.6 ms; p = 0.031) of the operated versus control femoral heads. T2 was also increased in the SOC (28.7 ± 2.0 vs. 22.7 ± 1.7; p = 0.0037) and epiphyseal cartilage (57.4 ± 4.7 vs. 49.0 ± 2.7; p = 0.0041). No changes in T1 were detected. The sensitivities of T1ρ and T2 mapping in detecting ischemic injury were maintained after a freeze/thaw cycle, and T1ρ sensitivity was maintained after varying spin-lock frequency and applying fat saturation. In conclusion, T1ρ and T2 mapping are sensitive in detecting ischemic injury to the SOC and epiphyseal cartilage of the femoral head as early as 48 h after ischemia induction.

Systemic versus free antibiotic delivery in preventing acute exogenous implant related infection in a rat model.

We studied systemic ceftriaxone, and free/local tobramycin and doxycycline in a controlled rat model representing a generic acute exogenous joint infection. We hypothesized that evidence of infection (quantitative colony forming units [CFU], qualitative scanning electron microscopy [SEM], histopathology) (1a) would be reduced with local versus systemic antibiotic, (1b) any antibiotic would be superior to control, (2) there would be a difference among antibiotics, and (3) antibiotic would not be detectable in serum at 4-week euthanasia. Study groups included infected and noninfected (1) control (no treatment), (2) systemic ceftriaxone (daily), (3) local tobramycin, and (4) local doxycycline (10 rats/group; power = 0.8). With IACUC approval, a reliable acute exogenous joint infection was created by slowly injecting 50-µl, 104 CFU Staphylococcus aureus, into the distal femoral medullary canal. The antibiotic formulation was introduced locally to the femoral canal and joint space. After 4 weeks, serum, pin, bone, and synovium were obtained. CFU/ml of bone and synovium were quantified using macrotiter method. SEM imaged biofilm on the surface of the pin, histopathology identified tissue response, liquid chromatography/mass spectrometry quantified plasma antibiotic. (1) Groups receiving any antibiotic reported lower CFU/ml in synovium compared with no treatment. (2) In the synovium, free/local tobramycin reduced CFU/ml to a greater extent than free/local doxycycline (p < 0.05). (3) Antibiotic in plasma after the local application was nondetectable in all groups after 4 weeks. SEM revealed no difference in biofilm on pin among all groups.

Dietary saturated fatty acid palmitate promotes cartilage lesions and activates the unfolded protein response pathway in mouse knee joints.

Increased intake of dietary saturated fatty acids has been linked to obesity and the development of Osteoarthritis (OA). However, the mechanism by which these fats promote cartilage degradation and the development of OA is not clearly understood. Here, we report the effects of consumption of common dietary saturated and unsaturated fatty acids, palmitate and oleate, respectively, on body weight, metabolic factors, and knee articular cartilage in a mouse model of diet-induced obesity. Mice fed on a diet rich in saturated or unsaturated fatty acid gained an equal amount of weight; however, mice fed a palmitate diet, but not a control or oleate diet, exhibited more cartilage lesions and increased expression of 1) unfolded protein response (UPR)/endoplasmic reticulum (ER) stress markers including BIP, P-IRE1α, XBP1, ATF4, and CHOP; 2) apoptosis markers CC3 and C-PARP; and 3) negative cell survival regulators Nupr1 and TRB3, in knee articular cartilage. Palmitate-induced apoptosis was confirmed by TUNEL staining. Likewise, dietary palmitate was also increased the circulatory levels of classic proinflammatory cytokines, including IL-6 and TNF-α. Taken together, our results demonstrate that increased weight gain is not sufficient for the development of obesity-linked OA and suggest that dietary palmitate promotes UPR/ER stress and cartilage lesions in mouse knee joints. This study validates our previous in vitro findings and suggests that ER stress could be the critical metabolic factor contributing to the development of diet/obesity induced OA.

Deletion of JNK Enhances Senescence in Joint Tissues and Increases the Severity of Age-Related Osteoarthritis in Mice.

OBJECTIVE: To determine the role of JNK signaling in the development of osteoarthritis (OA) induced by joint injury or aging in mice. METHODS: In the joint injury model, 12-week-old wild-type control, JNK1-/- , JNK2-/- , and JNK1fl/fl JNK2-/- aggecan-CreERT 2 double-knockout mice were subjected to destabilization of the medial meniscus (DMM) (n = 15 mice per group) or sham surgery (n = 9-10 mice per group), and OA was evaluated 8 weeks later. In the aging experiment, wild-type control, JNK1-/- , and JNK2-/- mice (n = 15 per group) were evaluated at 18 months of age. Mouse knee joints were evaluated by scoring articular cartilage structure, toluidine blue staining, osteophytes, and synovial hyperplasia, by histomorphometric analysis, and by immunostaining for the senescence marker p16INK 4a . Production of matrix metalloproteinase 13 (MMP-13) in cartilage explants in response to fibronectin fragments was measured by enzyme-linked immunosorbent assay. RESULTS: There were no differences after DMM surgery between the wild-type and the JNK-knockout mouse groups in articular cartilage structure, toluidine blue, or osteophyte scores or in MMP-13 production in explants. All 3 knockout mouse groups had increased subchondral bone thickness and area of cartilage necrosis compared to wild-type mice. Aged JNK-knockout mice had significantly worse articular cartilage structure scores compared to the aged wild-type control mice (mean ± SD 52 ± 24 in JNK1-/- mice and 60 ± 25 in JNK2-/- mice versus 32 ± 18 in controls; P = 0.02 and P = 0.004, respectively). JNK1-/- mice also had higher osteophyte scores. Deletion of JNK resulted in increased expression of p16INK 4a in the synovium and cartilage in older mice. CONCLUSION: JNK1 and JNK2 are not required for the development of OA in the mouse DMM model. Deletion of JNK1 or JNK2 is associated with more severe age-related OA and increased cell senescence, suggesting that JNK may act as a negative regulator of senescence in the joint.

The effect of vitamin K insufficiency on histological and structural properties of knee joints in aging mice.

Objective: While a role for vitamin K in maintaining joint tissue homeostasis has been proposed based on the presence of vitamin K dependent proteins in cartilage and bone, it is not clear if low vitamin K intake is causally linked to joint tissue degeneration. To address this gap, we manipulated vitamin K status in aging mice to test its effect on age-related changes in articular cartilage and sub-chondral bone. Methods: Eleven-month old male C57BL6 mice were randomly assigned to a low vitamin K diet containing 120 mcg phylloquinone/kg diet (n = 32) or a control diet containing 1.5 mg phylloquinone/kg diet (n = 30) for 6 months. Knees were evaluated histologically using Safranin O and H&E staining, as well as using micro-CT. Results: Eleven mice in the low vitamin K diet group and three mice in the control group died within the first 100 days of the experiment (p = 0.024). Mice fed the low vitamin K diet had higher Safranin-O scores, indicative of more proteoglycan loss, compared to mice fed the control diet (p ≤ 0.026). The articular cartilage structure scores did not differ between the two groups (p ≥ 0.190). The sub-chondral bone parameters measured using micro CT also did not differ between the two groups (all p ≥ 0.174). Conclusion: Our findings suggest low vitamin K status can promote joint tissue proteoglycan loss in older male mice. Future studies are needed to confirm our findings and obtain a better understanding of the molecular mechanisms underlying the role of vitamin K in joint tissue homeostasis.