Characterisation of strontium-containing apatite-wollastonite porous scaffolds

Porous strontium-doped apatite-wollastonite scaffolds were evaluated as potential substitutes for enhanced bone regeneration and the prevention of peri-prosthetic infections. Parent glasses of composition 35.5SiO2-7.1MgO-0.4CaF2-7.1P2O5-(49.9-x)CaO-xSrO mol%, where x = 0, 6.2, 12.5, 18.7, 24.9 or 37.4, were produced via the melt-quench route, ground and sieved <45 μm. Porous scaffolds were obtained following the foam-replication method and heat-treated at 1050 °C for 2 h for controlled nucleation and growth of the crystal phases. All six glasses produced were amorphous. Differential scanning calorimetry showed that the formation of the calcium silicate phase strongly depended on the amount of strontium contained in the parent glass, linearly moving to higher temperatures with increasing strontium. Morphological evaluation (scanning electron microscopy and micro-computed tomography) proved that the obtained scaffold porosity, about 55 vol%, did not depend on the strontium content. X-ray diffraction showed that strontium preferentially substituted in apatite, while only higher strontium compositions formed a strontium magnesium calcium silicate phase. Compressive and biaxial flexural strength were both comparable to cancellous bone. Compositions containing 0 %, 6.2 % and 12.5 % strontium showed excellent apatite forming ability when submerged in simulated body fluid, which then decreased with increasing strontium for the three higher-strontium compositions. Microbiological tests carried out on strontium-containing salts showed no effective antibacterial properties for strontium as a free element. Amongst the six strontium-containing glasses, only the 37.4 % strontium oxide glass showed antimicrobial effects against Pseudomonas aeruginosa in broth dilution tests. Proliferation and osteogenic differentiation of porous scaffolds were tested on human bone cells. No conclusive results were obtained for the G292 cell line. When scaffolds were tested with human primary mesenchymal stromal cells, an increase in DNA content was observed with increasing strontium, while enhanced alkaline phosphatase activity and increased collagen production were found for low strontium compositions

Effects of Weight Loss in Metabolically Healthy Obese Subjects after Laparoscopic Adjustable Gastric Banding and Hypocaloric Diet

Weight loss in metabolically healthy obese (MHO) subjects may result in deterioration of cardio-metabolic risk profile. We analyzed the effects of weight loss induced by laparoscopic adjustable gastric banding (LAGB) on cardio-metabolic risk factors in MHO and insulin resistant obese (IRO) individuals. This study included 190 morbidly obese non-diabetic subjects. Obese individuals were stratified on the basis of their insulin sensitivity index (ISI), estimated from an OGTT, into MHO (ISI index in the upper quartile) and IRO (ISI in the three lower quartiles). Anthropometric and cardio-metabolic variables were measured at baseline and 6-months after LAGB. Six months after LAGB, anthropometric measures were significantly reduced in both MHO and IRO. Percent changes in body weight, BMI, and waist circumference did not differ between the two groups. Fasting glucose and insulin levels, triglycerides, AST, and ALT were significantly reduced, and HDL cholesterol significantly increased, in both MHO and IRO subjects with no differences in percent changes from baseline. Insulin sensitivity increased in both MHO and IRO group. Insulin secretion was significantly reduced in the IRO group only. However, the disposition index significantly increased in both MHO and IRO individuals with no differences in percent changes from baseline between the two groups. The change in insulin sensitivity correlated with the change in BMI (r = −0.43; P<0.0001). In conclusion, our findings reinforce the recommendation that weight loss in response to LAGB intervention should be considered an appropriate treatment option for morbidly obese individuals regardless of their metabolic status, i.e. MHO vs. IRO subjects

Zirconia-containing radiopaque mesoporous bioactive glasses

cited By 13International audienceA radiopaque mesoporous bioactive glass (named MBGZ-7) was obtained through a combined sol-gel and evaporation induced self-assembling (EISA) route, adding zirconium propoxide to the synthesis batch as the zirconia precursor. The nitrogen sorption analysis confirmed the mesoporous nature of the glass. The assessment of in vitro bioactivity by soaking in acellular simulated body fluid (SBF) and SEM observation showed the deposition of hydroxyapatite crystals on its surface after one week. The good radiopacity level was demonstrated by comparing X-ray images of MBGZ-7 and a blank sample that did not contain radiopaque additives. It is envisaged the use of MBGZ-7 as a promising dispersed phase in composite materials for minimally invasive surgery procedures, such as injectable bone cements, in order to allow the visualization of the implant under fluoroscopic control, during both injection and follow-up. © 2014 Elsevier B.V

The growing role of bariatric surgery in the management of type 2 diabetes: evidences and open questions,” Obesity Surgery

Abstract The use of bariatric surgery in the clinical management of type 2 diabetes has been recently endorsed in the clinical practice recommendations released by the most influential diabetologic associations. However, authoritative critic voices about the application of metabolic surgery in type 2 diabetes continue to appear in diabetologic literature. In this review, we will try therefore to understand what the reasons for this apparent dichotomy. In this paper, we revised what we believe are now clear evidences about the role of bariatric surgery in the treatment of type 2 diabetes in patients with morbid obesity: the efficacy of bariatric surgery in metabolic control, the existence of plausible weight-independent metabolic mechanisms at least in some bariatric procedure, and the importance of the early referral to surgery in patients with firm indications. However, we stressed also the lack of clear high-quality long-term data about the effects of bariatric surgery in the prevention of both macro-and microvascular hard endpoints in patients with type 2 diabetes. The accrual of these results will be critical to completely clarify the risk/benefit ratio of bariatric surgery in diabetes, as compared to current pharmacologic therapies. This may be particularly important in patients in which data on longterm efficacy are still not completed, such as in patients with lower BMI levels

The Growing Role of Bariatric Surgery in the Management of Type 2 Diabetes: Evidences and Open Questions

The use of bariatric surgery in the clinical management of type 2 diabetes has been recently endorsed in the clinical practice recommendations released by the most influential diabetologic associations. However, authoritative critic voices about the application of metabolic surgery in type 2 diabetes continue to appear in diabetologic literature. In this review, we will try therefore to understand what the reasons for this apparent dichotomy. In this paper, we revised what we believe are now clear evidences about the role of bariatric surgery in the treatment of type 2 diabetes in patients with morbid obesity: the efficacy of bariatric surgery in metabolic control, the existence of plausible weight-independent metabolic mechanisms at least in some bariatric procedure, and the importance of the early referral to surgery in patients with firm indications. However, we stressed also the lack of clear high-quality long-term data about the effects of bariatric surgery in the prevention of both macro- and micro-vascular hard endpoints in patients with type 2 diabetes. The accrual of these results will be critical to completely clarify the risk/benefit ratio of bariatric surgery in diabetes, as compared to current pharmacologic therapies. This may be particularly important in patients in which data on long-term efficacy are still not completed, such as in patients with lower BMI levels

An aerosol-spray-assisted approach to produce mesoporous bioactive glass microspheres under mild acidic aqueous conditions

A mesoporous bioactive glass in the SiO2-CaO system was obtained for the first time by spray-drying an aqueous synthesis solution under mild acidic conditions. The obtained spherical particles showed high surface area and accessible porosity. They also showed a very high bioactivity, leading to the formation of hydroxyapatite and calcite after only 24 h in simulated body fluid. The in vitro cell culture results proved that the mesoporous particles are cytocompatible and might enhance the osteogenic differentiationof bone marrow stromal cells as they increased the alkaline phosphatase activity. The final bioactive mesoporous microspheres can be dispersed in composites in order to impart a high bioactivity and may be used as targeted drug delivery system