Assessment of the tolerance angle for pedicle screw insertion.

Cannulation process intervenes before implantation of pedicle screw and depends on the surgeon's experience. A reliable experimental protocol has been developed for the characterization of the slipping behavior of the surgical tool on the cortical shell simulated by synthetic materials. Three types of synthetic foam samples with three different densities were tested using an MTS Acumen 3 A/T electrodynamic device with a tri-axis 3 kN Kistler load cell mounted on a surgical tool, moving at a constant rotational speed of 10° mm-1 and performing a three-step cannulation test. Cannulation angle varied between 10° and 30°. Synthetic samples were scanned after each tests, and cannulation coefficient associated to each perforation section was computed. Reproducibility tests resulted in an ICC for Sawbone samples of 0.979 (p < 0.001) and of 0.909 (p < 0.001) for Creaplast and Sawbone samples. Cannulation coefficient and maximum force in Z-axis are found the best descriptors of the perforation. Angular threshold for perforation prediction was found to be 17.5° with an area under the curve of the Receiver Operating Characteristic of 89.5%. This protocol characterizes the cannulation process before pedicle screw insertion and identifies the perforation tool angle until which the surgical tool slips on the cortical shell depending on bone quality.

A randomized, controlled, prehabilitation intervention to maximize early recovery (PRIMER) in liver transplantation.

Frailty and impaired functional status are associated with adverse outcomes on the liver transplant (LT) waitlist and after transplantation. Prehabilitation prior to LT has rarely been tested. We conducted a 2-arm patient-randomized pilot trial to evaluate the feasibility and efficacy of a 14-week behavioral intervention to promote physical activity prior to LT. Thirty patients were randomized 2:1 to intervention (n = 20) versus control (n = 10). The intervention arm received financial incentives and text-based reminders linked to wearable fitness trackers. Daily step goals were increased by 15% in 2-week intervals. Weekly check-ins with study staff assessed barriers to physical activity. The primary outcomes were feasibility and acceptability. Secondary outcomes included mean end-of-study step counts, short physical performance battery, grip strength, and body composition by phase angle. We fit regression models for secondary outcomes with the arm as the exposure adjusting for baseline performance. The mean age was 61, 47% were female, and the median Model for End-stage Liver Disease sodium (MELD-Na) was 13. One-third were frail or prefrail by the liver frailty index, 40% had impaired mobility by short physical performance battery, nearly 40% had sarcopenia by bioimpedance phase angle, 23% had prior falls, and 53% had diabetes. Study retention was 27/30 (90%; 2 unenrolled from intervention, 1 lost to follow-up in control arm). Self-reported adherence to exercise during weekly check-ins was about 50%; the most common barriers were fatigue, weather, and liver-related symptoms. End-of-study step counts were nearly 1000 steps higher for intervention versus control: adjusted difference 997, 95% CI, 147-1847; p = 0.02. On average, the intervention group achieved daily step targets 51% of the time. A home-based intervention with financial incentives and text-based nudges was feasible, highly accepted, and increased daily steps in LT candidates with functional impairment and malnutrition.

Sliding on cortical shell: Biomechanical characterization of the vertebral cannulation for pedicle screw insertion.

BACKGROUND: Pedicular screws pull-out has been well studied unlike their insertion. A need for characterizing cannulation before pedicle screw implantation is highlighted in literature and offers promising prospects for future intra-operation instrumentation. A reliable cannulation protocol for ex-vivo testing in swine and cadaver vertebrae is presented in this work to predict extra pedicular perforation. METHODS: An MTS Acumen 3 A/T electrodynamic device, with a tri-axis 3 kN Kistler load cell mounted on a surgical tool was used to reproduce surgeon's gesture by moving at a constant rotational speed of 10°/mm and performing a three-section test. Perforation of the pedicle's cortical shell was planned through a design of experiment on the surgical tool angle at the entry point. Samples were scanned before and after mechanical tests and reproducibility of the protocol was tested on synthetic foam. Computation of the angle between cannulation tool and pedicle cortical shell was performed as well as cannulation coefficient of each perforation section. FINDINGS: A total of 68 pedicles were tested: 19 perforated and 21 non-perforated human pedicles, 17 perforated and 16 non-perforated swine pedicles. The reproducibility of the protocol for cannulation coefficient computation resulted in an intraclass correlation coefficient of 0.979. Cannulation coefficients results presented variability within spinal levels as well as between swine and human model. Correlation between bone density and cannulation coefficient was found significant (p < 0.005). Torque measurement was found to be the best predictor of perforation. Threshold of angle for prediction of perforation was found to be 21.7°. INTERPRETATION: Characterizing pedicle cannulation enables to predict extra pedicular perforation. Influence of bone mineral density and patient-specific morphology on pedicle cannulation has been highlighted together with a comparison of swine and cadaver models.

Half of Postoperative Deaths After Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy Could be Preventable: A French Root Cause Analysis on 5562 Patients.

OBJECTIVE: To perform a retrospective root-cause analysis of postoperative death after CRS and HIPEC procedures. BACKGROUND: The combination of CRS and HIPEC is an effective therapeutic strategy to treat peritoneal surface malignancies, however it is associated with significant postoperative mortality. METHODS: All patients treated with a combination of CRS and HIPEC between January 2009 and December 2018 in 22 French centers and died in the hospital, were retrospectively analyzed. Perioperative data of the 101 patients were collected by a local senior surgeon with a sole junior surgeon. Three independent experts investigated the typical root cause of death and provided conclusions on whether postoperative death was preventable (PREV group) or not (NON-PREV group). A typical root cause of preventable postoperative death was classified on a cause-and-effect diagram. RESULTS: Of the 5562 CRS+HIPEC procedures performed, 101 in-hospital deaths (1.8%) were identified, of which a total of 18 patients of 70 years old and above and 20 patients with ASA score of 3. Etiology of peritoneal disease was mainly colorectal. A total of 54 patients (53%) were classified in the PREV group and 47 patients (47%) in the NON-PREV group. The results of the study show that in the PREV group, WHO performance status 1-2 was more frequent and the Median Peritoneal Cancer Index was higher compared with those of the NON-PREV group. The cause of death in the PREV group was classified as: (i) preoperatively for debatable indication (59%), (ii) intraoperatively (30%) and (iii) postoperatively in 17 patients (31%). A multifactorial cause of death was found in 11 patients (20%). CONCLUSION: More than half of the postoperative deaths after combined CRS and HIPEC may be preventable, mainly by following guidelines regarding preoperative selection of the patients and adequate intraoperative decisions.

MicroRNA-29b Contributes to Collagens Imbalance in Human Osteoarthritic and Dedifferentiated Articular Chondrocytes.

OBJECTIVE: Decreased expression of collagen type II in favour of collagen type I or X is one hallmark of chondrocyte phenotype changes in osteoarthritic (OA) cartilage. MicroRNA- (miR-) 29b was previously shown to target collagens in several tissues. We studied whether it could contribute to collagen imbalance in chondrocytes with an impaired phenotype. METHODS: After preliminary microarrays screening, miR-29b levels were measured by RT- quantitative PCR in in vitro models of chondrocyte phenotype changes (IL-1ß challenge or serial subculturing) and in chondrocytes from OA and non-OA patients. Potential miR-29b targets identified in silico in 3'-UTRs of collagens mRNAs were tested with luciferase reporter assays. The impact of premiR-29b overexpression in ATDC5 cells was studied on collagen mRNA levels and synthesis (Sirius red staining) during chondrogenesis. RESULTS: MiR-29b level increased significantly in IL-1ß-stimulated and weakly in subcultured chondrocytes. A 5.8-fold increase was observed in chondrocytes from OA versus non-OA patients. Reporter assays showed that miR-29b targeted COL2A1 and COL1A2 3'-UTRs although with a variable recovery upon mutation. In ATDC5 cells overexpressing premiR-29b, collagen production was reduced while mRNA levels increased. CONCLUSIONS: By acting probably as a posttranscriptional regulator with a different efficacy on COL2A1 and COL1A2 expression, miR-29b can contribute to the collagens imbalance associated with an abnormal chondrocyte phenotype.

Dual luciferase gene reporter assays to study miRNA function.

This chapter describes one of the most reliable quantitative assays to test the silencing of a possible target gene by a specific miRNA using a luciferase reporter gene. The experimental procedure first consists in cloning both the wild-type and mutated forms of the 3'UTR of the miRNA predicted mRNA target downstream of a firefly luciferase reporter. Next, each construct is co-transfected together with the miRNA into HeLa cells, and the reporter expression is monitored. Changes in luciferase levels will indicate whether or not a miRNA can bind to the UTR and regulate its expression.

NMR measurement of LDL particle number using the Vantera Clinical Analyzer.

BACKGROUND: The Vantera Clinical Analyzer was developed to enable fully-automated, high-throughput nuclear magnetic resonance (NMR) spectroscopy measurements in a clinical laboratory setting. NMR-measured low-density lipoprotein particle number (LDL-P) has been shown to be more strongly associated with cardiovascular disease outcomes than LDL cholesterol (LDL-C) in individuals for whom these alternate measures of LDL are discordant. OBJECTIVE: The aim of this study was to assess the analytical performance of the LDL-P assay on the Vantera Clinical Analyzer as per Clinical Laboratory Standards Institute (CLSI) guidelines. RESULTS: Sensitivity and linearity were established within the range of 300-3500 nmol/L. For serum pools containing low, medium and high levels of LDL-P, the inter-assay, intra-assay precision and repeatability gave coefficients of variation (CVs) between 2.6 and 5.8%. The reference interval was determined to be 457-2282 nmol/L and the assay was compatible with multiple specimen collection tubes. Of 30 substances tested, only 2 exhibited the potential for assay interference. Moreover, the LDL-P results from samples run on two NMR platforms, Vantera Clinical Analyzer and NMR Profiler, showed excellent correlation (R(2)=0.96). CONCLUSIONS: The performance characteristics suggest that the LDL-P assay is suitable for routine testing in the clinical laboratory on the Vantera Clinical Analyzer, the first automated NMR platform that supports NMR-based clinical assays.

Improved omnidirectional reflectors in chalcogenide glass and polymer by using the silver doping technique.

We describe the fabrication and characterization of omnidirectional reflectors based on silver-doped chalcogenide glass and polymer. We deposited periodically alternating layers of thermally evaporated Ge33As12Se55 chalcogenide glass, sputtered silver, and spun-cast polyamide-imide polymer. The silver was subsequently dissolved into each adjacent chalcogenide glass layer, either by exposing the multilayer to visible light (photodoping) or by heating the sample. The resultant silver concentration within the chalcogenide glass layers is estimated to be ~20 at. %. Silver doping red-shifts the band edge of the glass, and produces an increase of ~0.3-0.4 in the refractive index. The glass retains good transparency in the near infrared after doping, and the technique enables the omnidirectional bandwidth to be increased from ~100 nm to ~200 nm in the 1550 nm wavelength region.

[The Inflammatory Bowel Disease Stress Inventory (IBD-SI). A measure of psychosocial stress in patients with IBD]. / Fragebogen zur Messung der psychosozialen Belastungen bei chronisch-entzündlichen Darmerkrankungen (FBCED): Konstruktion und Evaluation.

The "Inflammatory Bowel Disease Stress Inventory (IBD-SI)" measures a broad spectrum of disease-specific every day stress factors in patients with inflammatory bowel disease (IBD). Based on a multistage factor analysis on 300 CED patients, the final form comprises 32 items assigned to 8 different domains: depressed mood, doctor-patient relationship, anxiety about loss of bowel control, occupational impairment, worries about deteriovation, stress from medical treatment, impairment of sexuality/partnership and physical complaints. In addition, a global stress score can be obtained. The reliability values of the 8 subscales with 4 items each indicate a good internal consistency (alpha = 0.76 - 0.89) and a high retest reliability (r = 0.75 - 0.92). Significant correlations with medical and psychological variables supports the external validity of this questionnaire.