Biochemical Basis And Clinical Consequences Of Glucolipotoxicity: A Primer

Both glucose and fatty acids may have good/adaptive or toxic/maladaptive actions on the pancreatic beta cell, depending on their concentrations. Hyperglycemia, via metabolic intermediates, may result in multiple cellular effects that are toxic to the pancreatic beta cell and indeed other tissues. While free fatty acids may affect cellular processes beyond lipid metabolism by interacting with transcription factors, triglyceride rich lipoproteins are endothelial cell-toxic and facilitate atherogenesis. The paradigm of glucolipotoxicity espouses that increased glucose and fatty acid levels act synergistically in causing toxicity to pancreatic islets and other organs, a process that eventually leads to the multiple defects seen in the metabolic syndrome and diabetes mellitus. © 2012 Elsevier Inc

Oyster shell-derived nano-hydroxyapatite and proanthocyanidin pretreatment on dentinal tubule occlusion and permeability before and after acid challenge—an in vitro study

Abstract This in vitro study evaluated the dentinal tubule occlusion (TO), depth of penetration (DoP), and dentin permeability (DP) of oyster shell-derived nanohydroxyapatite (os-nHAp) with and without 15% proanthocyanidin (PA) pretreatment. os-nHAp was synthesized via the precipitation method and it was characterized. The morphology and particle size of os-nHAp were analyzed using a high-resolution transmission electron microscope (HRTEM). Cytotoxicity of os-nHAp, PA/os-nHAp, and casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) was assessed by (3-(4,5-dimethythiazol-2-yl) 2,5-diphenyl tetrazolium bromide (MTT) assay using human osteosarcoma (MG-63) cell line. One hundred and ninety-seven dentin discs of 3 mm thickness were prepared from the crown portion of extracted human teeth. The dentinal surfaces of the discs were etched for 2 min with 6% citric acid to simulate dentin hypersensitivity. Five discs were randomly selected and the patency of dentinal tubules was confirmed using a scanning electron microscope (SEM). The remaining 192 discs were divided into four groups (n = 48) depending on the type of remineralization as follows: group 1: os-nHAp, group 2: PA/os-nHAp, group 3: CPP-ACP, and group 4: no treatment. The remineralization protocol was followed for 21 days. Out of the 48 dentin discs in each group, 32 discs were used to evaluate dentinal tubule occlusion (TO) and depth of penetration (DoP) using SEM. The remaining 16 discs were subjected to an assessment of dentin permeability (DP) using a hydraulic conductance model. TO, DoP and DP were evaluated after remineralization and acid challenge. Characterization studies confirmed the presence of pure phase apatite. HRTEM confirmed the nanometric particle size of os-nHAp. MTT assay results showed that all the tested materials exhibited >80% cell viability when tested up to a concentration of 100 µg/mL. The results demonstrated a significantly higher mean percentage of TO, DoP, and lesser mean DP after remineralization in groups 1, 2, and 3 (p < 0.05). After the acid challenge, group 3 showed a significant reduction in TO and DoP, and increased DP (p < 0.05). However, no such changes were observed in groups 1 and 2. Within the limitations of this study, it can be concluded that os-nHAp and PA/os-nHAp could serve as potential and durable therapeutic agents in the treatment of dentin hypersensitivity. Graphical Abstrac

Chronic Macular Oedema as a Late MIRAgel-Related Complication

Background: MIRAgel® (MIRA, Waltham, MA, USA) is a hydrogel scleral buckle introduced in 1979 to treat rhegmatogenous retinal detachments. Its use was discontinued because late complications that require surgical removal were reported. Methods: Case report. Results: We report a case of left eye MIRAgel® buckle surgery 28 years ago presenting with a tender palpable erythematous swelling at the lower lid, with marked conjunctival chemosis and progressive ophthalmoplegia. Imaging revealed a large, well-defined, horseshoe-shaped lesion in the extraconal space of the left orbit with globe distortion, with histological confirmation of an expanded hydrogel buckle. He recovered well following removal of the explant but developed chronic macular oedema a year later, which persisted despite sub-Tenon’s triamcinolone injections. Repeat imaging demonstrated remaining hydrogel explant. Macular oedema settled well upon successful surgical removal with no recurrence to date. Conclusion: Our case is the first to describe macular oedema as a late MIRAgel-related complication, with complete removal of the explant being the definitive treatment. Macular oedema indicates postoperative inflammation secondary to the remaining explant fragments. Given the friability of hydrolysed MIRAgel®, we recommend ophthalmologists to warn patients regarding the possibility of further inflammation in the globe or the orbit in case of incomplete removal