The Photosynthetic Pancreas: From Fantasy to Reality

Islets of Langerhans implantation is a viable method to treat type I diabetes. Unfortunately, during islets isolation their vascular system is disrupted, and they need external supply of oxygen and other nutrients. A photosynthetic bioartificial device was constructed to support the oxygen consumption of the islets and to treat type I diabetes. The bioartificial device is built in layers where the core is an illumination module composed of a LED array and a light guide. The next layer is immobilized photosynthetic organism (Synechococcus lividus). An oxygen-permeable silicon/Teflon membrane separates the photosynthetic layer from the islets of Langerhans layer. This layer is protected from the immune system of the body by a porous Teflon membrane. The device is powered by batteries that supply electricity to a LED array. The oxygen produced by S. lividus is consumed by implanted islets of Langerhans that produce insulin and allow the reversal of diabetes in the patient. In this chapter, we demonstrate the ability of S. lividus to produce oxygen after being implanted for prolonged periods and eventually the ability of the device containing S. lividus and the islets of Langerhans to reverse diabetes for 10 days. To achieve this task, we developed improved media to grow cyanobacteria and, inter alia, developed a method to disperse light uniformly and in very short distances

The real-world safety profile of sodium-glucose co-transporter-2 inhibitors among older adults (≥ 75 years): a retrospective, pharmacovigilance study

BackgroundAs indications for sodium-glucose co-transporter-2 inhibitors (SGLT2i) are expanding, a growing number of older adults have become candidates for treatment. We studied the safety profile of SGLT2i among older adults.MethodsA retrospective, pharmacovigilance study of the FDA's global database of safety reports. To assess reporting of pre-specified adverse events following SGLT2i among adults (< 75 years) and older adults (>= 75), we performed a disproportionality analysis using the sex-adjusted reporting odds ratio (adj.ROR).ResultsWe identified safety reports of 129,795 patients who received non-insulin anti-diabetic drugs (NIAD), including 24,253 who were treated with SGLT2i (median age 60 [IQR: 51-68] years, 2,339 [9.6%] aged >= 75 years). Compared to other NIAD, SGLT2i were significantly associated with amputations (adj.ROR = 355.1 [95%CI: 258.8 - 487.3] vs adj.ROR = 250.2 [79.3 - 789.5]), Fournier gangrene (adj.ROR = 45.0 [34.5 - 58.8] vs adj.ROR = 88.0 [27.0 - 286.6]), diabetic ketoacidosis (adj.ROR = 32.3 [30.0 - 34.8] vs adj.ROR = 23.3 [19.2 - 28.3]), genitourinary infections (adj.ROR = 10.3 [9.4 - 11.2] vs adj.ROR = 8.6 [7.2 - 10.3]), nocturia (adj.ROR = 5.5 [3.7 - 8.2] vs adj.ROR = 6.7 [2.8 - 15.7]), dehydration (adj.ROR = 2.5 [2.3 - 2.8] vs adj.ROR = 2.6 [2.1 - 3.3]), and fractures (adj.ROR = 1.7 [1.4 - 2.1] vs adj.ROR = 1.5 [1.02 - 2.1]) in both adults and older adults, respectively. None of these safety signals was significantly greater in older adults (P-interaction threshold of 0.05). Acute kidney injury was associated with SGLT2i in adults (adj.ROR = 1.97 [1.85 - 2.09]) but not in older adults (adj.ROR = 0.71 [0.59 - 0.84]). Falls, hypotension, and syncope were not associated with SGLT2i among either adults or older adults.ConclusionIn this global post-marketing study, none of the adverse events was reported more frequently among older adults. Our findings provide reassurance regarding SGLT2i treatment in older adults, although careful monitoring is warranted

Sugar-induced cephalic-phase insulin release is mediated by a T1r2+T1r3-independent taste transduction pathway in mice

Sensory stimulation from foods elicits cephalic phase responses, which facilitate digestion and nutrient assimilation. One such response, cephalic-phase insulin release (CPIR), enhances glucose tolerance. Little is known about the chemosensory mechanisms that activate CPIR. We studied the contribution of the sweet taste receptor (T1r2+T1r3) to sugar-induced CPIR in C57BL/6 (B6) and T1r3 knockout (KO) mice. First, we measured insulin release and glucose tolerance following oral (i.e., normal ingestion) or intragastric (IG) administration of 2.8 M glucose. Both groups of mice exhibited a CPIR following oral but not IG administration, and this CPIR improved glucose tolerance. Second, we examined the specificity of CPIR. Both mouse groups exhibited a CPIR following oral administration of 1 M glucose and 1 M sucrose but not 1 M fructose or water alone. Third, we studied behavioral attraction to the same three sugar solutions in short-term acceptability tests. B6 mice licked more avidly for the sugar solutions than for water, whereas T1r3 KO mice licked no more for the sugar solutions than for water. Finally, we examined chorda tympani (CT) nerve responses to each of the sugars. Both mouse groups exhibited CT nerve responses to the sugars, although those of B6 mice were stronger. We propose that mice possess two taste transduction pathways for sugars. One mediates behavioral attraction to sugars and requires an intact T1r2+T1r3. The other mediates CPIR but does not require an intact T1r2+T1r3. If the latter taste transduction pathway exists in humans, it should provide opportunities for the development of new treatments for controlling blood sugar

Long-term viability and function of transplanted islets macroencapsulated at high density are achieved by enhanced oxygen supply

Transplantation of encapsulated islets can cure diabetes without immunosuppression, but oxygen supply limitations can cause failure. We investigated a retrievable macroencapsulation device wherein islets are encapsulated in a planar alginate slab and supplied with exogenous oxygen from a replenishable gas chamber. Translation to clinically-useful devices entails reduction of device size by increasing islet surface density, which requires increased gas chamber pO Here we show that islet surface density can be substantially increased safely by increasing gas chamber pO to a supraphysiological level that maintains all islets viable and functional. These levels were determined from measurements of pO profiles in islet-alginate slabs. Encapsulated islets implanted with surface density as high as 4,800 islet equivalents/cm in diabetic rats maintained normoglycemia for more than 7 months and provided near-normal intravenous glucose tolerance tests. Nearly 90% of the original viable tissue was recovered after device explantation. Damaged islets failed after progressively shorter times. The required values of gas chamber pO were predictable from a mathematical model of oxygen consumption and diffusion in the device. These results demonstrate feasibility of developing retrievable macroencapsulated devices small enough for clinical use and provide a firm basis for design of devices for testing in large animals and humans

Losing the rose tinted glasses: Neural substrates of unbiased belief updating in depression.

Recent evidence suggests that a state of good mental health is associated with biased processing of information that supports a positively skewed view of the future. Depression, on the other hand, is associated with unbiased processing of such information. Here, we use brain imaging in conjunction with a belief update task administered to clinically depressed patients and healthy controls to characterize brain activity that supports unbiased belief updating in clinically depressed individuals. Our results reveal that unbiased belief updating in depression is mediated by strong neural coding of estimation errors in response to both good news (in left inferior frontal gyrus and bilateral superior frontal gyrus) and bad news (in right inferior parietal lobule and right inferior frontal gyrus) regarding the future. In contrast, intact mental health was linked to a relatively attenuated neural coding of bad news about the future. These findings identify a neural substrate mediating the breakdown of biased updating in major depression disorder, which may be essential for mental health

VISTA Variables in the <i>Vía Láctea</i> (VVV): Halfway Status and Results

The VISTA Variables in the Vía Láctea (VVV) survey is one of six near-infrared ESO public surveys, and is now in its fourth year of observing. Although far from being complete, the VVV survey has already delivered many results, some directly connected to the intended science goals (detection of variable stars, microlensing events, new star clusters), others concerning more exotic objects, e.g., novae. Now, at the end of the fourth observing period, and comprising roughly 50% of the proposed observations, the status of the survey, as well some of results based on the VVV data, are presented.Facultad de Ciencias Astronómicas y Geofísica

Interpreting the Energy-Dependent Anisotropy of Colloidal Nanorods Using Ensemble and Single-Particle Spectroscopy

We report the use of polarized excitation spectroscopy in the study of the polarized optical properties of II–VI semiconducting nanorods. This technique provides a quantitative measure for analyzing the polarization-dependent electronic structure of ensembles of semiconducting nanoparticles in colloidal solutions. We develop a procedure to quantify the anisotropy of nanorod excitations and the influence of the dielectric environment which yields results in qualitative agreement with theoretical predictions of nanorod absorption properties. Excitation measurements of nanorod ensembles and single-particle excitation and emission polarization measurements are used to interpret ensemble measurements on the molecular frame. At the single-particle level, we find a large dispersion in the angles between excitation and emission polarization curves. This contrasts with the conventional picture of CdSe electronic transitions, in which the crystal axes dictate the symmetry of excitations. Such geometrically heterogeneous excitations suggest that perturbations of the physical structure adjust the polarization properties of individual nanorods from those of an ideal theoretical nanorod

NeutrAvidin Functionalization of CdSe/CdS Quantum Nanorods and Quantification of Biotin Binding Sites using Biotin-4-Fluorescein Fluorescence Quenching

We developed methods to solubilize, coat, and functionalize with NeutrAvidin elongated semiconductor nanocrystals (quantum nanorods, QRs) for use in single molecule polarized fluorescence microscopy. Three different ligands were compared with regard to efficacy for attaching NeutrAvidin using the “zero-length cross-linker” 1-ethyl-3-[3-(dimethylamino)­propyl]­carbodiimide (EDC). Biotin-4-fluorescene (B4F), a fluorophore that is quenched when bound to avidin proteins, was used to quantify biotin binding activity of the NeutrAvidin coated QRs and biotin binding activity of commercially available streptavidin coated quantum dots (QDs). All three coating methods produced QRs with NeutrAvidin coating density comparable to the streptavidin coating density of the commercially available quantum dots (QDs) in the B4F assay. One type of QD available from the supplier (ITK QDs) exhibited ∼5-fold higher streptavidin surface density compared to our QRs, whereas the other type of QD (PEG QDs) had 5-fold lower density. The number of streptavidins per QD increased from ∼7 streptavidin tetramers for the smallest QDs emitting fluorescence at 525 nm (QD525) to ∼20 tetramers for larger, longer wavelength QDs (QD655, QD705, and QD800). QRs coated with NeutrAvidin using mercaptoundecanoicacid (MUA) and QDs coated with streptavidin bound to biotinylated cytoplasmic dynein in single molecule TIRF microscopy assays, whereas Poly­(maleic anhydride-<i>alt</i>-1-ocatdecene) (PMAOD) or glutathione (GSH) QRs did not bind cytoplasmic dynein. The coating methods require optimization of conditions and concentrations to balance between substantial NeutrAvidin binding vs tendency of QRs to aggregate and degrade over time