The Experts below are selected from a list of 72939 Experts worldwide ranked by ideXlab platform
Marc D. Grynpas - One of the best experts on this subject based on the ideXlab platform.
-
Chlorthalidone with potassium citrate decreases calcium oxalate stones and increases Bone Quality in genetic hypercalciuric stone-forming rats.
Kidney international, 2021Co-Authors: Nancy S. Krieger, Ignacio Granja, Luojing Chen, Daiana Spataru, Marc D. GrynpasAbstract:To study human idiopathic hypercalciuria we developed an animal model, genetic hypercalciuric stone-forming rats, whose pathophysiology parallels that of human idiopathic hypercalciuria. Fed the oxalate precursor, hydroxyproline, every rat in this model develops calcium oxalate stones. Using this rat model, we tested whether chlorthalidone and potassium citrate combined would reduce calcium oxalate stone formation and improve Bone Quality more than either agent alone. These rats (113 generation) were fed a normal calcium and phosphorus diet with hydroxyproline and divided into four groups: diets plus potassium chloride as control, potassium citrate, chlorthalidone plus potassium chloride, or potassium citrate plus chlorthalidone. Urine was collected at six, 12, and 18 weeks and kidney stone formation and Bone parameters were determined. Compared to potassium chloride, potassium citrate reduced urinary calcium, chlorthalidone reduced it further and potassium citrate plus chlorthalidone even further. Potassium citrate plus chlorthalidone decreased urine oxalate compared to all other groups. There were no significant differences in calcium oxalate supersaturation in any group. Neither potassium citrate nor chlorthalidone altered stone formation. However, potassium citrate plus chlorthalidone significantly reduced stone formation. Vertebral trabecular Bone increased with chlorthalidone and potassium citrate plus chlorthalidone. Cortical Bone area increased with chlorthalidone but not potassium citrate or potassium citrate plus chlorthalidone. Mechanical properties of trabecular Bone improved with chlorthalidone, but not with potassium citrate plus chlorthalidone. Thus in genetic hypercalciuric stone-forming rats fed a diet resulting in calcium oxalate stone formation, potassium citrate plus chlorthalidone prevented stone formation better than either agent alone. Chlorthalidone alone improved Bone Quality, but adding potassium citrate provided no additional benefit.
-
Chlorthalidone Is Superior to Potassium Citrate in Reducing Calcium Phosphate Stones and Increasing Bone Quality in Hypercalciuric Stone-Forming Rats
Journal of the American Society of Nephrology : JASN, 2019Co-Authors: Nancy S. Krieger, Ignacio Granja, Luojing Chen, Felix M. Ramos, Courtney Flotteron, Marc D. GrynpasAbstract:Background The pathophysiology of genetic hypercalciuric stone-forming rats parallels that of human idiopathic hypercalciuria. In this model, all animals form calcium phosphate stones. We previously found that chlorthalidone, but not potassium citrate, decreased stone formation in these rats. Methods To test whether chlorthalidone and potassium citrate combined would reduce calcium phosphate stone formation more than either medication alone, four groups of rats were fed a fixed amount of a normal calcium and phosphorus diet, supplemented with potassium chloride (as control), potassium citrate, chlorthalidone (with potassium chloride to equalize potassium intake), or potassium citrate plus chlorthalidone. We measured urine every 6 weeks and assessed stone formation and Bone Quality at 18 weeks. Results Potassium citrate reduced urine calcium compared with controls, chlorthalidone reduced it further, and potassium citrate plus chlorthalidone reduced it even more. Chlorthalidone increased urine citrate and potassium citrate increased it even more; the combination did not increase it further. Potassium citrate, alone or with chlorthalidone, increased urine calcium phosphate supersaturation, but chlorthalidone did not. All control rats formed stones. Potassium citrate did not alter stone formation. No stones formed with chlorthalidone, and rats given potassium citrate plus chlorthalidone had some stones but fewer than controls. Rats given chlorthalidone with or without potassium citrate had higher Bone mineral density and better mechanical properties than controls, whereas those given potassium citrate did not. Conclusions In genetic hypercalciuric stone-forming rats, chlorthalidone is superior to potassium citrate alone or combined with chlorthalidone in reducing calcium phosphate stone formation and improving Bone Quality.
-
association between fluoride magnesium aluminum and Bone Quality in renal osteodystrophy
Bone, 2004Co-Authors: Marc D. Grynpas, Adeline Ng, G Hercz, R KandelAbstract:Introduction: Trace elements are known to influence Bone metabolism; however, their effects may be exacerbated in renal failure because dialysis patients are unable to excrete excess elements properly. Our study correlated Bone Quality in dialysis patients with levels of Bone fluoride, magnesium, and aluminum. A number of studies have linked trace elements, including fluoride, magnesium, and aluminum, to the development of renal osteodystrophy (ROD). However, little is known about the relationship between trace elements and changes in Bone Quality in ROD patients. The purpose of this study was to examine Bone Quality in ROD patients, and correlate differences in Bone Quality to trace element concentrations in Bone. Bone Quality encompasses parameters that contribute to the mechanical integrity of the Bone. Methods: One hundred fifty-three anterior iliac crest Bone biopsies from patients with ROD were examined and subdivided into five groups based on the pathological features. Parameters contributing to Bone Quality, such as Bone structure and remodeling, connectivity, mineralization, and microhardness, were assessed and correlated to Bone chemical composition. In addition, clinical symptoms of ROD were assessed and correlated with Bone composition. Results and Conclusions: There were no differences in Bone architecture between the different ROD Bone groups; however, differences in Bone mineralization and microhardness were observed. Increase in Bone fluoride was associated with increased osteoid parameters and decreased Bone microhardness. Bone mineralization and microhardness decreased with increasing Bone magnesium content and intact parathyroid hormone (PTH) level. Moreover, Bone magnesium increased with intact PTH levels. The relationship between PTH, Bone magnesium, mineralization, and microhardness was primarily observed in aplastic Bone disorder. Furthermore, Bone magnesium and aluminum contents were positively associated with Bone pain and proximal myopathy in these patients. Most importantly, fluoride, magnesium, and aluminum showed significant correlations with one another. These results suggested that in ROD, Bone fluoride may diminish Bone microhardness by interfering with mineralization. Magnesium may be involved in the suppression of PTH secretion, lowering Bone turnover thus leading to an increase in Bone mineralization profile and microhardness in aplastic Bone disorder. The effects of fluoride and magnesium on Bone Quality may be exacerbated by their interaction with aluminum.
Eleftherios Tsiridis - One of the best experts on this subject based on the ideXlab platform.
-
The biomechanical effect of Bone Quality and fracture topography on locking plate fixation in periprosthetic femoral fractures
Injury, 2014Co-Authors: Andreas Leonidou, Mehran Moazen, Panagiotis Lepetsos, Simon Graham, George A. Macheras, Eleftherios TsiridisAbstract:Optimal management of periprosthetic femoral fractures (PFF) around a well fixed prosthesis (Vancouver B1) remains controversial as adequate fixation needs to be achieved without compromising the stability of the prosthesis. The aim of this study was to highlight the effect of Bone Quality i.e. canal thickness ratio (CTR), and fracture topography i.e. fracture angle and its position in relation to the stem, on the biomechanics of a locking plate for a Vancouver B1 fracture. A previously corroborated simplified finite element model of a femur with a cemented total hip replacement stem was used in this study. Canal thickness ratio (CTR) and fracture topography were altered in several models and the effect of these variations on the von Mises stress on the locking plate as well as the fracture displacement was studied. Increasing the CTR led to reduction of the von Mises stress on the locking plate as well as the fracture movement. In respect to the fracture angle with the medial cortex, it was shown that acute angles resulted in lower von Mises stress on the plate as opposed to obtuse angles. Furthermore, acute fracture angles resulted in lower fracture displacement compared to the other fractures considered here. Fractures around the tip of the stem had the same biomechanical effect on the locking plate. However, fractures more distal to the stem led to subsequent increase of stress, strain, and fracture displacement. Results highlight that in good Bone Quality and acute fracture angles, single locking plate fixation is perhaps an appropriate management method. On the contrary, for poor Bone Quality and obtuse fracture angles alternative management methods might be required as the fixation might be under higher risk of failure. Clinical studies for the management of PFF are required to further support our findings.
-
evaluation of fracture topography and Bone Quality in periprosthetic femoral fractures a preliminary radiographic study of consecutive clinical data
Injury-international Journal of The Care of The Injured, 2013Co-Authors: Andreas Leonidou, Mehran Moazen, Simon Graham, Eleftherios Tsiridis, D Skrzypiec, Joseph PagkalosAbstract:Abstract The unique configuration of periprosthetic femoral fractures (PFFs) is a major determinant of the subsequent management. The aim of this preliminary study was to investigate potential relationships between fracture angle (FA), fracture level (FL) and Bone Quality of Vancouver type B PFF. The FA, FL and the canal thickness ratio (CTR) were quantified for 27 patient X-rays. The CTR is an indicator of the underlying Bone Quality. Relationships between these factors were studied for the whole X-ray set, for a subgroup involving fracture above the tip of the stem and for subgroups with stable and unstable implants. When considering all cases, no significant correlation was found between the FA and any other measurement. Considering only cases with unstable implants, a statistically significant correlation was found between the FA and the FL ( R 2 = 0.489, p = 0.002). No correlation was found between FA and any other measurement for stable implants suggesting that FA could be considered as an independent factor when classifying B1 fractures. Considering all cases, a weak correlation was found between CTR and FL ( R 2 = 0.152, p = 0.044) suggesting that fractures below the tip of the stem may indicate a lower Bone Quality. This preliminary study suggests that the effect of FA on the optimal management of Vancouver type B1 fractures could be considered, independent of the Quality of the Bone or fracture position. Furthermore, fractures around or below the tip of the stem may suggest a poor Bone Quality. Larger number of patients is required to confirm these initial findings.
Uwe Wolfram - One of the best experts on this subject based on the ideXlab platform.
-
peroperative estimation of Bone Quality and primary dental implant stability
Journal of The Mechanical Behavior of Biomedical Materials, 2019Co-Authors: Benjamin Voumard, Ghislain Bernard Maquer, Peter Heuberger, Philippe K Zysset, Uwe WolframAbstract:Abstract Objectives Dental implants are widely used to restore function and appearance. It may be essential to choose the appropriate drilling protocol and implant design in order to optimise primary stability. This could be achieved based on an assessment of the implantation site with respect to Bone Quality and objective biomechanical descriptors such as stiffness and strength of the Bone-implant system. The aim of this ex vivo study is to relate these descriptors with Bone Quality, with a pre-implantation indicator of implant stability: pilot-hole drilling force (Fdrilling), and with two post-implantation indicators: maximal implantation torque (Timplantation) and resonance frequency analysis (RFA). Methods Eighty trabecular Bone specimens were cored from human vertebrae and bovine tibiae. Bone volume fraction (BV/TV), a representative for Bone Quality, was obtained through micro-computed tomography scans. Implants were kept in controlled laboratory conditions following standard surgical procedures. Forces and torques were recorded and RFA was assessed after implantation. Off-axis compression tests were conducted on the implants until failure. Implant stability was identified by stiffness and ultimate force (Fultimate). The relationships between BV/TV, Stiffness, Fultimate and Fdrilling, Timplantation, RFA were established. Results Fdrilling correlated well with BV/TV of the implantation site (r2 = 0.81), stiffness (r2 = 0.75) and Fultimate (r2 = 0.80). Timplantation correlated better with stiffness (r2 = 0.86) and Fultimate (r2 = 0.94) than RFA (r2 = 0.77 and r2 = 0.74, respectively). Conclusion Our results indicate that BV/TV and Bone-implant stability can be directly estimated by the force needed for the pilot drilling that occurs during the site preparation before implantation. Moreover, implantation torque outperforms RFA for evaluating the mechanical competence of the Bone-implant system.
John P Bilezikian - One of the best experts on this subject based on the ideXlab platform.
-
dxa based Bone strain index a new tool to evaluate Bone Quality in primary hyperparathyroidism
The Journal of Clinical Endocrinology and Metabolism, 2021Co-Authors: Gaia Tabacco, Carmelo Messina, Anda Mihaela Naciu, Gianfranco Sanson, Luca Rinaudo, Roberto Cesareo, Stefania Falcone, Silvia Manfrini, Nicola Napoli, John P BilezikianAbstract:CONTEXT Primary hyperparathyroidism (PHPT) is associated with impaired Bone Quality and increased fracture risk. Reliable tools for the evaluation of Bone Quality parameters are not yet clinically available. Bone Strain Index (BSI) is a new metric for Bone strength based on Finite Element Analysis from lumbar spine and femoral neck dual-energy x-ray absorptiometry (DXA) images. OBJECTIVE To assess the lumbar spine (LS), femoral neck (FN), and total hip (TH) BSI in PHPT patients compared with controls and to investigate the association of BSI with vertebral fractures (VFs) in PHPT. METHODS This case-control study enrolled 50 PHPT patients and 100 age- and sex-matched control subjects from an outpatient clinic. The main outcome measures were LS-BSI, FN-BSI, and TH-BSI. RESULTS FN Bone mineral density (BMD) and one-third distal radius BMD were lower in the PHPT group than in controls (FN 0.633 ± 0.112 vs 0.666 ± 0.081, P = 0.042; radius 0.566 ± 0.07 vs 0.625 ± 0.06, P < 0.001). PHPT group has significant lower TBS score compared with controls (1.24 ± 0.09 vs 1.30 ± 0.10, P < 0.001). BSI was significantly higher at LS (2.28 ± 0.59 vs 2.02 ± 0.43, P = 0.009), FN (1.72 ± 0.41 vs 1.49 ± 0.35, P = 0.001), and TH (1.51 ± 0.33 vs 1.36 ± 0.25, P = 0.002) in PHPT. LS-BSI showed moderate accuracy for discriminating VFs (AUC 0.667; 95% CI, 0.513-0.820). LS-BSI ≥ 2.2 and was a statistically significant independent predictor of VFs, with an adjusted odds ratio ranging from 5.7 to 15.1. CONCLUSION BSI, a DXA-derived Bone Quality index, is impaired in PHPT and may help to identify PHPT subjects at high risk of fractures.
Nancy S. Krieger - One of the best experts on this subject based on the ideXlab platform.
-
Chlorthalidone with potassium citrate decreases calcium oxalate stones and increases Bone Quality in genetic hypercalciuric stone-forming rats.
Kidney international, 2021Co-Authors: Nancy S. Krieger, Ignacio Granja, Luojing Chen, Daiana Spataru, Marc D. GrynpasAbstract:To study human idiopathic hypercalciuria we developed an animal model, genetic hypercalciuric stone-forming rats, whose pathophysiology parallels that of human idiopathic hypercalciuria. Fed the oxalate precursor, hydroxyproline, every rat in this model develops calcium oxalate stones. Using this rat model, we tested whether chlorthalidone and potassium citrate combined would reduce calcium oxalate stone formation and improve Bone Quality more than either agent alone. These rats (113 generation) were fed a normal calcium and phosphorus diet with hydroxyproline and divided into four groups: diets plus potassium chloride as control, potassium citrate, chlorthalidone plus potassium chloride, or potassium citrate plus chlorthalidone. Urine was collected at six, 12, and 18 weeks and kidney stone formation and Bone parameters were determined. Compared to potassium chloride, potassium citrate reduced urinary calcium, chlorthalidone reduced it further and potassium citrate plus chlorthalidone even further. Potassium citrate plus chlorthalidone decreased urine oxalate compared to all other groups. There were no significant differences in calcium oxalate supersaturation in any group. Neither potassium citrate nor chlorthalidone altered stone formation. However, potassium citrate plus chlorthalidone significantly reduced stone formation. Vertebral trabecular Bone increased with chlorthalidone and potassium citrate plus chlorthalidone. Cortical Bone area increased with chlorthalidone but not potassium citrate or potassium citrate plus chlorthalidone. Mechanical properties of trabecular Bone improved with chlorthalidone, but not with potassium citrate plus chlorthalidone. Thus in genetic hypercalciuric stone-forming rats fed a diet resulting in calcium oxalate stone formation, potassium citrate plus chlorthalidone prevented stone formation better than either agent alone. Chlorthalidone alone improved Bone Quality, but adding potassium citrate provided no additional benefit.
-
Chlorthalidone Is Superior to Potassium Citrate in Reducing Calcium Phosphate Stones and Increasing Bone Quality in Hypercalciuric Stone-Forming Rats
Journal of the American Society of Nephrology : JASN, 2019Co-Authors: Nancy S. Krieger, Ignacio Granja, Luojing Chen, Felix M. Ramos, Courtney Flotteron, Marc D. GrynpasAbstract:Background The pathophysiology of genetic hypercalciuric stone-forming rats parallels that of human idiopathic hypercalciuria. In this model, all animals form calcium phosphate stones. We previously found that chlorthalidone, but not potassium citrate, decreased stone formation in these rats. Methods To test whether chlorthalidone and potassium citrate combined would reduce calcium phosphate stone formation more than either medication alone, four groups of rats were fed a fixed amount of a normal calcium and phosphorus diet, supplemented with potassium chloride (as control), potassium citrate, chlorthalidone (with potassium chloride to equalize potassium intake), or potassium citrate plus chlorthalidone. We measured urine every 6 weeks and assessed stone formation and Bone Quality at 18 weeks. Results Potassium citrate reduced urine calcium compared with controls, chlorthalidone reduced it further, and potassium citrate plus chlorthalidone reduced it even more. Chlorthalidone increased urine citrate and potassium citrate increased it even more; the combination did not increase it further. Potassium citrate, alone or with chlorthalidone, increased urine calcium phosphate supersaturation, but chlorthalidone did not. All control rats formed stones. Potassium citrate did not alter stone formation. No stones formed with chlorthalidone, and rats given potassium citrate plus chlorthalidone had some stones but fewer than controls. Rats given chlorthalidone with or without potassium citrate had higher Bone mineral density and better mechanical properties than controls, whereas those given potassium citrate did not. Conclusions In genetic hypercalciuric stone-forming rats, chlorthalidone is superior to potassium citrate alone or combined with chlorthalidone in reducing calcium phosphate stone formation and improving Bone Quality.