The design of a drug that successfully overcomes the constraints imposed by the blood−brain barrier (BBB, which acts as a gatekeeper to the entry of substances into the brain) requires an understanding of the biological firewall. It is also of utmost importance to understand the physicochemical properties of the said drug and how it engages the BBB to avoid undesired side effects. Since fewer than 5% of the tested molecules can pass through the BBB, drug development pertaining to brain-related disorders takes inordinately long to develop. Furthermore, in most cases it is also unsuccessful for allied reasons. Several drug delivery systems (DDSs) have shown excellent potential in drug delivery across the BBB while demonstrating minimal side effects. This mini-review summarizes key features of the BBB, recapitulates recent advances in our understanding of the BBB, and highlights existing strategies for the delivery of drug to the brain parenchyma.

Melatonin referred as the hormone of darkness is mainly secreted by pineal gland, its levels being elevated during night and low during the day. The effects of melatonin on insulin secretion are mediated through the melatonin receptors (MT1 and MT2). It decreases insulin secretion by inhibiting cAMP and cGMP pathways but activates the phospholipaseC/IP3 pathway, which mobilizes Ca 2+ from organelles and, consequently increases insulin secretion. Both in vivo and in vitro, insulin secretion by the pancreatic islets in a circadian manner, is due to the melatonin action on the melatonin receptors inducing a phase shift in the cells. Melatonin may be involved in the genesis of diabetes as a reduction in melatonin levels and a functional interrelationship between melatonin and insulin was observed in diabetic patients. Evidences from experimental studies proved that melatonin induces production of insulin growth factor and promotes insulin receptor tyrosine phosphorylation. The disturbance of internal circadian system induces glucose intolerance and insulin resistance, which could be restored by melatonin supplementation. Therefore, the presence of melatonin receptors on human pancreatic islets may have an impact on pharmacotherapy of type 2 diabetes. Arch Endocrinol Metab.2015;59(5):391-9

There are many reasons for dental implant failure, the development of bacteremia is concern for dentists. This is due to the possibility of unfavorable result such as implant loss or the need for re-treatment. In general, antibiotic prophylaxis is recommended for high risk patients such as individuals with an immunodeficiency, infectious endocarditis, or previous prosthetic instrumentation. However regarding clinically healthy, low and moderate risk individuals the use of antibiotics in implant dentistry is controversial. Another major concern regarding the over prescription of antibiotics is the selection of antibiotic resistant bacteria. A better understanding of the efficacy of prophylactic treatments regarding dental implantation is crucial. Thus a literature review and comparison of survival rates of dental implants with regimens of no, pre or post prophylaxis was performed using systematic literature review using reliable electronic databases. Retrospective or prospective controlled studies were examined for the influence of preoperative and/or postoperative or no antibiosis on dental implant success rate. Of the 11406 implants used in this literature review, cases with no antibiotics had a 92 % success rate, cases with pre-op antibiotic alone had a 96% success rate, cases with post-op antibiotic alone had a 97% success rate and cases with both pre and post-op antibiotic had a success rate of 96%. Thus, the results from this literature review show a > 90% success rate when antibiotics are used compared to when they are not used. Thus, no benefit is seen from the use of antibiotic prophylaxis in low and moderate risk dental implant patients.KeywordsDental implants; Pre-operative prophylactics; Post-operative prophylactics; Success rate

The shape-dependent properties of gold nanostars (NSs) have motivated massive research efforts in the field of colloidal chemistry to gain a better control over the morphology of these promising nanostructures. Nevertheless, this challenge requires a better understanding of the atomic-scale processes leading to the formation of stellated nanoparticles. We hereby report an unprecedented in situ study focused on the seed-mediated synthesis of symmetric gold NSs performed by radiolysis in methanol. We take advantage of the spatial and temporal resolutions of liquid-cell transmission electron microscopy to unravel the key effects of the growth speed, seed-crystal morphology, and dimethylamine functionalization on the formation mechanisms, shape, and stability of NSs enclosed by high-index facets. Surprisingly, the stellation processes transforming icosahedral nanoparticles into NSs with 20 sharp arms entails a continuous restructuring of NS facets driven by surface diffusion, which provide a fresh look at faceting mechanisms.