CTXA hip: the effect of partial volume correction on volumetric bone mineral density data for cortical and trabecular bone

This study compares the results of computed tomography X-ray absorptiometry (CTXA) hip volumetric BMD (vBMD) analyses of cortical and trabecular bone with and without partial volume correction. For cortical bone in some circumstances, corrected cortical volumes were negative and corrected vBMD was very high. For trabecular bone, the correction effects are smaller. CTXA volumetric data should be interpreted with caution.

PURPOSE

Previous studies have reported concerns about the reliability of CTXA hip cortical vBMD measurements generated using partial volume (PV) correction (the "default" analysis, with cortical PV correction). To date, no studies have examined the results of the alternative ("new") analysis (with trabecular PV correction). This study presents in vivo and phantom data comparing the corrected and uncorrected data for cortical and trabecular bone respectively.

METHODS

We used the commercial QCTPro CTXA software to analyze CT scans of 129 elderly Chinese men and women and an anthropomorphic European Proximal Femur phantom (EPFP) and accessed data for two alternative scan analyses using the database dump utility. The CTXA software gives the user two methods of performing the PV correction: (1) a default analysis in which only cortical bone results are corrected; (2) a new analysis in which only trabecular bone results are corrected. Both methods are based on a numerical recalculation of vBMD values without any change in volume of interest (VOI) placement.

RESULT

In vivo, the results of the two analyses for integral bone were the same while cortical and trabecular results were different. PV correction of cortical bone led to a decrease of cortical volume for all four VOIs: total hip (TH), femoral neck (FN), trochanter (TR), and intertrochanter (IT) volumes were reduced on average by 7.8 cm³, 0.9 cm³, 2.5 cm³, and 4.3 cm³ respectively. For TR, where cortex was thinnest, average corrected cortical volume was negative (- 0.4± 1.3 cm³). Corrected cortical vBMD values were much larger than uncorrected ones for TH, FN, and IT. Scatter plots of corrected cortical vBMD against cortical bone thickness showed that elevated results correlated with thinner cortices. When trabecular bone was corrected for the PV effect, trabecular volumes of TH, FN, TR, and IT were reduced on average by 7.9 cm³, 0.8 cm³, 2.6 cm³, and 4.4 cm³ respectively, while vBMD measurements were increased correspondingly. The trabecular volume and vBMD measurements of the two datasets both had highly positive correlations. For the EPFP, the PV-corrected FN data deviated from the nominal phantom value, but was closer for the TR and IT VOIs. Both corrected and uncorrected data overestimated trabecular vBMD, with the corrected results showing greater deviation from nominal values.

CONCLUSION

The default and new CTXA analyses for volumetric data generate different results, both for cortical and trabecular bone. For cortical bone, the uncorrected results are subject to partial volume effects but the correction method of the default analysis overcorrects the effect leading to in part unreasonable results for cortical bone volume and BMD. For trabecular bone, the correction effects are smaller. CTXA volumetric data should be interpreted with caution.

Porphyromonas gingivalis Induces Insulin Resistance by Increasing BCAA Levels in Mice

Insulin resistance is one of the critical pathogeneses of type 2 diabetes mellitus (T2DM). Elevated levels of plasma branched-chain amino acids (BCAAs) are associated with insulin resistance. Recent studies have demonstrated the role of Porphyromonas gingivalis in the development of insulin resistance. However, the mechanisms by which P. gingivalis induces insulin resistance are still unclear. The purpose of this study was to investigate whether P. gingivalis induces insulin resistance through BCAA biosynthesis. We established a murine model of periodontitis by infecting mice with P. gingivalis. Alveolar bone loss, insulin sensitivity, and the plasma level of BCAAs were measured. A P. gingivalis BCAA aminotransferase-deficient strain (∆bcat) was constructed, and its kinetic growth, biofilm formation, and in vivo colonization were compared with its wild-type strain. Alveolar bone loss, insulin sensitivity, and the plasma level of BCAAs of the mice infected with either wild-type strain or ∆bcat strain were further measured. We found that periodontal infection with P. gingivalis significantly upregulated the plasma level of BCAAs and aggravated the high-fat diet (HFD)-induced insulin resistance. Bcat deletion did not alter the growth, biofilm formation, and in vivo colonization of P. gingivalis. More important, the ∆bcat strain was unable to upregulate the plasma level of BCAAs and induce insulin resistance in HFD-fed mice. These findings suggest that the BCAA biosynthesis of P. gingivalis plays a critical role in the development of insulin resistance in the HFD-fed mice. The BCAA biosynthesis pathways may provide a potential target for the disruption of linkage between periodontitis and T2DM.

Feasibility of energy adaptive angular meshing for perpendicular and parallel magnetic fields in a grid based Boltzmann solver

PURPOSE

To develop the enabling algorithmic techniques which allow forward-peaked adaptive angular meshing to be compatible with angular advection of magnetic fields within a deterministic Grid Based Boltzmann Solver (GBBS) for MRI-guided radiotherapy, and establish appropriate energy adaptive meshing schemes which minimize total numerical degrees of freedom while preserving high dosimetric accuracy for parallel and perpendicular magnetic fields.

METHODS

A framework to independently adapt angular mesh resolution and basis function refinement of forward and backscattering hemispheres is developed, uniquely accommodating angular advection introduced by magnetic fields. Upwind stabilization techniques to accurately transfer fluence between hemispheres having different discretization are established. To facilitate oblique beam and magnetic field orientations, cardinal forward-peaked mesh orientations were devised to balance requirements for acyclic space-angle sweep ordering, while ensuring the beam predominantly overlaps the forward hemisphere. Energy-dependent fluence anisotropy is investigated, leading to adaptive angular meshing schemes for parallel and perpendicular magnetic fields. Calculated dose distributions were validated against GEANT4 Monte Carlo calculations on slab geometry and anthropomorphic phantoms.

RESULTS

Forward-peaked and isotropic energy adaptive angular meshing schemes were developed for parallel and perpendicular magnetic fields respectively, which reduce the number of elements solved by 52.8% and 47.7% respectively compared to static discretization using 32 quadratic elements while retaining over 97% of points passing the gamma 1%/1 mm criterion against Monte Carlo.

CONCLUSIONS

Techniques to preserve angular upwind-stabilization between hemispheres of a forward-peaked mesh and establish an acyclic directed space-angle sweep graph enabled energy-adaptive meshing schemes to be developed while accurately solving for magnetic fields. This substantially reduced the numerical degrees of freedom while retaining excellent dosimetric agreement with Monte Carlo. These algorithmic underpinnings contribute towards a fast deterministic GBBS for MRI-guided radiotherapy.

[Interaction of health literacy and second-hand smoke exposure on psychopathological symptoms of middle school students]

Objective: To explore the interaction of health literacy and second-hand smoke exposure on psychopathological symptoms of middle school students. Methods: From November 2015 to January 2016, 22 628 middle school students from Shenyang of Liaoning Province, Bengbu of Anhui Province, Xinxiang of Henan Province, Ulanqab of Inner Mongolia Autonomous Region, Chongqing Municipality, and Yangjiang of Guangdong Province were enrolled by using the multi-stage cluster convenience sampling method. A questionnaire was used to collect the data including demographic information, health literacy, second-hand smoke exposure, and psychopathological symptoms. A multivariate logistic regression model was used to analyze the interaction of health literacy and second-hand smoke exposure on psychopathological symptoms of middle school students. Results: The age of students was (15.36±1.79) years old, of which 10 990 were boys, accounting for 48.6% of total students. The detection rate of psychopathological symptoms was 29.1% (6 581/22 628). The detection rate of psychopathological symptoms in those who were exposed to second-hand smoke was 38.1% (2 401/6 304), which was higher than that in the non-second-hand smoke exposure group [25.6% (4 180/16 324)] (P<0.001). The OR (95%CI) of the interaction between medium and low levels of overall health literacy, low level of interpersonal dimension of health literacy and second-hand smoke exposure was 1.19 (1.15-1.24), 2.00 (1.92-2.10) and 1.59 (1.52-1.66), respectively. Conclusion: There was a positive interaction between middle and low levels of overall health literacy, low level of interpersonal dimension of health literacy and second-hand smoke exposure on psychopathological symptoms of middle school students.

Functional role of SIRT1-induced HMGB1 expression and acetylation in migration, invasion and angiogenesis of ovarian cancer

OBJECTIVE

Ovarian cancer is a commonly occurred tumor in females. High motility group box-1 protein (HHMB1) is a chromosome-related protein with multiple functions. A recent study revealed critical roles of HMGB1 in occurrence and progression of ovarian cancer. Sirtuin 1 (SIRT1) is a recently identified novel molecule, which regulates acetylation of HMGB1. Whether SIRT1 is involved in migration, invasion or angiogenesis of ovarian cancer is unclear. This study aims to investigate the role of SIRT1-induced HMGB1 acetylation in migration, invasion, and angiogenesis in ovarian cancer.

PATIENTS AND METHODS

In ovarian cancer cell line, SIRT1 expression was potentiated. Western blot and immunofluorescence were used to measure HMGB1 expression, acetylation level, and nuclear translocation. Scratch assay and transwell chamber methods were used to examine cell migration and invasion potency. A mouse model with ovarian cancer cell transplantation was generated to measure induced nitric oxide synthase (iNOs) and CD105 expression.

RESULTS

Compared to adjacent tissues, ovarian cancer tissues had significantly decreased SIRT1 expression. In ovarian cancer cells, SIRT1 over-expression decreased HMGB1 and acetylation levels, and SIRT1 knockdown facilitated HMGB1 expression and acetylation. SIRT1 over-expression also suppressed nuclear translocation of HMGB1. Meanwhile, SIRT1 could suppress, migration and angiogenesis of ovarian cancer cells via HMGB1.

CONCLUSIONS

SIRT1 over-expression effectively inhibited HMGB1 expression and acetylation, thus inhibiting ovarian cancer migration, invasion and angiogenesis. HMGB1 modulated behaviors of ovarian cancer via SIRT1. Therefore, SIRT1 might work as a treatment target for managing ovarian cancer migration.

The Predictive Value of Sarcopenia and Its Individual Criteria for Cardiovascular and All-Cause Mortality in Suburb-dwelling Older Chinese

OBJECTIVES

The aim of the present study is to investigate the associations between the Asian Working Group for Sarcopenia (AWGS) sarcopenic definition, and its individual criteria, and risk of cardiovascular disease (CVD) and all-cause mortality in the Chinese elderly.

METHODS

Longitudinal analysis of 1,264 participants aged 60 years or older at baseline (2013-2014) living in suburban areas, China. Sarcopenia was defined according to the recommended algorithm of AWGS. Muscle mass was measured by a direct segmental multifrequency bioelectrical impedance analysis. Muscle strength was assessed by handgrip strength, and physical performance measured via usual walking speed.

RESULTS

Cox proportional hazard models were used to assess the risk of CVD and all-cause mortality. After 40 months of follow-up, forty-eight deaths (4.2%) died in this cohort. The mortality rate with sarcopenia was 4.7% in men and 3.8% in women. After adjusting for potential confounders, the risk of all-cause death was 4.15 times higher in subjects with sarcopenia. Furthermore, low muscle mass (HR: 2.62, 95% CI 1.34-5.13) and low grip strength (HR: 5.79; 95% CI 2.28-14.71), but not walking speed, were found to be significantly associated with all-cause mortality. Risk of CVD mortality was significantly greater in sarcopenia. Low grip strength and low walking speed were associated with 11 times (HR: 11.03, 95% CI 1.58-77.02) and 13 times (HR: 13.02; 95% CI 1.18-143.78) higher risk of CVD mortality.

CONCLUSIONS

Sarcopenia and components of sarcopenia were associated with greater CVD and all-cause mortality. Pertinent prevention or rehabilitation programs projects should look to promote healthy aging in different types of sarcopenia group.

[Association of health literacy and smoking behaviors among middle school students in six cities of China]

Objective: To explore the association between the health literacy (HL) and smoking behaviors in middle school students. Methods: From November 2015 to January 2016, middle school students in Shenyang City of Liaoning Province, Bengbu City of Anhui Province, Xinxiang City of Henan Province, Ulanqab City of Inner Mongolia Autonomous Region, Chongqing City and Yangjiang City of Guangdong Province were enrolled by using a multistage stratified cluster sampling method. A total of 23 137 questionnaires were issued and 22 628 questionnaires were valid. A questionnaire survey was conducted to collect demographic information, HL and smoking behaviors. The low, middle, and high-level group were classified according to the tertile of HL score. A multiple logistic regression model was conducted to explore the association between the HL and smoking behaviors. Results: The age of subjects was (15.4±1.8) years old, and HL score was (104.1±18.7) points. The proportion of former smoking, recent smoking and passive smoking was 9.2% (2 071), 2.8% (635) and 27.9% (6 304), respectively. The proportion of former smokers who tried to quit smoking was 50.1% (1 037/2 071). Compared to the high-level HL, the low-level HL increased the risk of former smoking [OR (95%CI): 1.85 (1.61-2.13)], recent smoking [OR (95%CI): 1.68 (1.33-2.14)] and passive smoking [OR (95%CI): 1.34 (1.23-1.46)], and decreased the likelihood of smoking cessation [OR (95%CI): 0.70 (0.53-0.92)], after adjusting for the gender, school type, registered residence, household structure, accommodation type, educational level of patients, and self-reported family economic status. Conclusion: The HL of middle school students was related to their smoking behaviors.

Preliminary evaluation of GLP-1R PET in the diagnosis and risk stratification of pheochromocytomas

Noninvasive imaging methods for the diagnosis and risk stratification of pheochromocytomas (PHEOs) remain a great clinical challenge. The glucagon-like peptide-1 receptor (GLP-1R) has been validated to be overexpressed in PHEOs and therefore may be a reliable target for PHEOs. In this study, we firstly synthesized a novel radiotracer 68Ga-NOTA-MAL-Cys39-exendin-4 that specifically targets GLP-1R and evaluated the performance of GLP-1R PET for the diagnosis and risk stratification of PHEOs. Cys39-exendin-4 was conjugated to NOTA-MAL and then radiolabeled with 68Ga. The reaction was completed within 20 min with a yield of 91.6 ± 2.8%. In vitro cell uptake studies validated its high specificity. PET images showed promising tumor visualization with high uptake (1.88 ± 0.10 %ID/g for PC-12 poorly differentiated tumors and 1.09 ± 0.003 %ID/g for PC-12 highly differentiated tumors at 30min after injection). There was a significant difference in the uptake of 68Ga-NOTA-MAL-Cys39-exendin-4 between PC-12 poorly and highly differentiated tumors (p < 0.001), but no significant difference could be observed by 18F-FDG PET. Biodistribution results confirmed the findings of GLP-1R PET and demonstrated that 131I-MIBG couldn't be used for the risk stratification of PHEOs. Immunohistochemistry (IHC) staining revealed differences in GLP-1R expression between PC-12 poorly and highly differentiated tumor tissues. These results demonstrated that 68Ga-NOTA-MAL-Cys39-exendin-4 can specifically target GLP-1R with favorable pharmacokinetic properties. GLP-1R PET can be used for PHEOs detection and has potential for the risk stratification of PHEOs.

Induction of zonal-specific cellular morphology and matrix synthesis for biomimetic cartilage regeneration using hybrid scaffolds

Cartilage is anisotropic in nature and organized into distinct zones. Our goal was to develop zonal-specific three-dimensional hybrid scaffolds which could induce the generation of zonal-specific cellular morphology and extracellular matrix (ECM) composition. The superficial and middle zones comprised two layers of hyaluronic acid (HA) hydrogel which enveloped specifically orientated or randomly arranged polylactic acid nanofibre meshes. The deep zone comprised a HA hydrogel with multiple vertical channels. Primary bovine chondrocytes were seeded into the individual zonal scaffolds, cultured for 14 days and then the ECM was analysed. The aligned nanofibre mesh used in the superficial zone induced an elongated cell morphology, lower glycosaminoglycan (GAG) and collagen II production, and higher cell proliferation and collagen I production than the cells in the middle zone scaffold. Within the middle zone scaffold, which comprised a randomly orientated nanofibre mesh, the cells were clustered and expressed more collagen II. The deep zone scaffold induced the highest GAG production, the lowest cell proliferation and the lowest collagen I expression of the three zones. Assembling the three zones and stabilizing the arrangement with a HA hydrogel generated aligned, randomly aggregated and columnar cells in the superficial, middle and deep zones. This study presents a method to induce zonal-specific chondrocyte morphology and ECM production.

Vascular endothelial growth factor A/Vascular endothelial growth factor receptor 2 axis promotes human dental pulp stem cell migration via the FAK/PI3K/Akt and p38 MAPK signalling pathways

AIM

To investigate the effects of vascular endothelial growth factor A (VEGFA) and the underlying molecular mechanisms on the migration of human dental pulp stem cells (hDPSCs).

METHODOLOGY

The expression of VEGFA in inflammatory pulp tissue and lipopolysaccharide (LPS)-stimulated dental pulp cells was examined by immunofluorescence staining and qRT-PCR. The migration of hDPSCs was detected using transwell migration and wound healing assays. The activation of FAK, PI3K, Akt and p38 signalling was evaluated by Western blot analysis. Silence RNA (siRNA) technology was utilized to knockdown the expression of VEGFR1 (Flt-1) and VEGFR2 (Flk-1/KDR). PF573228 (inhibitor of FAK), LY294002 (inhibitor of PI3K), SB203580 (inhibitor of p38) and SU5416 (inhibitor of VEGFR2) were employed to investigate the effect of VEGFA on the migratory mechanism of hDPSCs. Data were analysed statistically using the Student's t-test or one-way ANOVA.

RESULTS

The expression levels of VEGFA in inflammatory pulp tissue in vivo and LPS-stimulated dental pulp cells in vitro were significantly greater than those in the control groups (P < 0.05). Vascular endothelial growth factor A promoted the migration of hDPSCs in a concentration-dependent manner. Several signalling pathways, including FAK, PI3K, Akt and p38, were activated by VEGFA in a dose- and time-dependent manner in hDPSCs. The VEGFA-induced migration of hDPSCs was significantly inhibited with drug inhibitors such as PF573228, LY294002, SB203580 or SU5416 (P < 0.05). These signalling pathways activated by VEGFA stimulation were significantly suppressed by pre-treatment with inhibitor of VEGFR2 (SU5416) or transfection with siRNA of VRGFR2 (P < 0.05) but not VEGFR1 siRNA.

CONCLUSIONS

Vascular endothelial growth factor A/VEGFR2 axis promoted the migration of hDPSCs via the FAK/PI3K/Akt and p38 MAPK signalling pathways. These findings reveal a novel molecular mechanism for cell migration of hDPSCs, which may contribute to the remodelling of pulp tissue and dentine.

Beam Energy and Centrality Dependence of Direct-Photon Emission from Ultrarelativistic Heavy-Ion Collisions

The PHENIX collaboration presents first measurements of low-momentum (0.4<p_{T}<3  GeV/c) direct-photon yields from Au+Au collisions at sqrt[s_{NN}]=39 and 62.4 GeV. For both beam energies the direct-photon yields are substantially enhanced with respect to expectations from prompt processes, similar to the yields observed in Au+Au collisions at sqrt[s_{NN}]=200. Analyzing the photon yield as a function of the experimental observable dN_{ch}/dη reveals that the low-momentum (>1  GeV/c) direct-photon yield dN_{γ}^{dir}/dη is a smooth function of dN_{ch}/dη and can be well described as proportional to (dN_{ch}/dη)^{α} with α≈1.25. This scaling behavior holds for a wide range of beam energies at the Relativistic Heavy Ion Collider and the Large Hadron Collider, for centrality selected samples, as well as for different A+A collision systems. At a given beam energy, the scaling also holds for high p_{T} (>5  GeV/c), but when results from different collision energies are compared, an additional sqrt[s_{NN}]-dependent multiplicative factor is needed to describe the integrated-direct-photon yield.

Reconstruction of the pelvic ring after total en bloc sacrectomy using a 3D-printed sacral endoprosthesis with re-establishment of spinopelvic stability: a retrospective comparative study

AIMS

The aim of this study was to describe the use of 3D-printed sacral endoprostheses to reconstruct the pelvic ring and re-establish spinopelvic stability after total en bloc sacrectomy (TES) and to review its outcome.

PATIENTS AND METHODS

We retrospectively reviewed 32 patients who underwent TES in our hospital between January 2015 and December 2017. We divided the patients into three groups on the basis of the method of reconstruction: an endoprosthesis group (n = 10); a combined reconstruction group (n = 14), who underwent non-endoprosthetic combined reconstruction, including anterior spinal column fixation; and a spinopelvic fixation (SPF) group (n = 8), who underwent only SPF. Spinopelvic stability, implant survival (IS), intraoperative haemorrhage rate, and perioperative complication rate in the endoprosthesis group were documented and compared with those of other two groups.

RESULTS

The mean overall follow-up was 22.1 months (9 to 44). In the endoprosthesis group, the mean intraoperative hemorrhage was 3530 ml (1600 to 8100). Perioperative complications occurred in two patients; both had problems with wound healing. After a mean follow-up of 17.7 months (12 to 38), 9/10 patients could walk without aids and 8/10 patients were not using analgesics. Imaging evidence of implant failure was found in three patients, all of whom had breakage of screws and/or rods. Only one of these, who had a local recurrence, underwent re-operation, at which solid bone-endoprosthetic osseointegration was found. The mean IS using re-operation as the endpoint was 32.5 months (95% confidence interval 23.2 to 41.8). Compared with the other two groups, the endoprosthesis group had significantly better spinopelvic stability and IS with no greater intraoperative haemorrhage or perioperative complications.

CONCLUSION

The use of 3D-printed endoprostheses for reconstruction after TES provides reliable spinopelvic stability and IS by facilitating osseointegration at the bone-implant interfaces, with acceptable levels of haemorrhage and complications. Cite this article: Bone Joint J 2019;101-B:880-888.