Dissecting the effects of free fatty acids on the thermodynamic stability of complex model membranes mimicking insulin secretory granules

A stepwise micro-DSC study of Small, Large and Giant Unilamellar Vesicles prepared as pure and mixed systems of DMPC, DPPC, DSPC and DOPC was performed, achieving the preparation of final model membranes whose phospholipid compositions represent the 75% in terms of the phospholipids tails and the 50% headgroups of the Insulin Secretory Granules (vesicles located in the pancreatic Langerhans \u3b2-cells and which are responsible for insulin and amylin storage and secretion in response to nutrient intake). Moreover, the effect of Free Fatty Acids, whose levels are recurrently altered in diabetic and/or obese subjects, on the thermodynamic stability of the final membranes was eventually investigated. The results allowed to discriminate each single thermodynamic contribution among the main factors that dictate the overall thermodynamic stability of these complex unilamellar systems evidencing mainly entropic effects hierarchically summarized as phospholipid unsaturations > phospholipid tail length > membrane curvature. The effect of the Free Fatty Acids highlighted a strong stabilizing effect on the membranes as well as more pronounced phase segregations in the case of saturated acids (palmitic and stearic), whereas the opposite effect was observed in the case of an unsaturated one (oleic)

Transcriptional control of the B3GALT5 gene by a retroviral promoter and methylation of distant regulatory elements

We focused on transcription factors and epigenetic marks that regulate the B3GALT5 gene through its retroviral long terminal repeat (LTR) promoter. We compared the expression levels of the B3GALT5 LTR transcript, quantitated by competitive RT-PCR, with those of the candidate transcription factors HNF1\u3b1/\u3b2 and Cdx1/2, determined by Western blot analysis, in colon cancer biopsies, various cell lines, and cell models serving as controls. We found that HNF1\u3b1/\u3b2 were easily detected, irrespective of the amount of LTR transcript expressed by the source, whereas Cdx1/2 were undetectable, and no sample lacking HNF1\u3b1/\u3b2 expressed the LTR transcript. On transfection in proper host cells, both HNF1\u3b1 and HNF1\u3b2 provided detectable LTR transcript, whereas shRNA-mediated silencing of HNF1\u3b2 impaired transcription. Treating cells with 5\u2032-aza-2\u2032-deoxycytidine (5AZA) strongly reduced expression, without affecting HNF1\u3b1/\u3b2, despite the lack of CpG islands in the LTR and proximal sequences. By electrophoresis mobility shift and luciferase reporter assays, the LTR promoter binding and activity did not correlate with the amounts of LTR transcript expressed in the cells and depended on the levels of the transcription factors. We conclude that HNF1\u3b1/\u3b2 are necessary but insufficient to activate and regulate B3GALT5 LTR transcription, which depends on unknown regulatory elements that are active when methylated and located outside of and far from the LTR promoter

Microsurgical Disconnection of Ruptured Intracranial Pial Arteriovenous Fistula Guided by Indocyanine Green Videoangiography.

Intracranial arteriovenous fistulas, rare causes of spontaneous intracerebral bleeding, are direct communications between an arterial feeder and an arterialized vein that drains a normal brain. Arteriovenous disconnection is the only effective treatment for this type of vascular malformation, which is often reached microsurgically due to the difficult endovascular access. Intraoperative indocyanine green videoangiography (ICG-VA) is a valuable help in identifying the arterialized draining vein and its direct communication with the arterial feeder and in confirming real-time interruption of the fistula. We describe the case of a 46-year-old man presenting with sudden onset of headache and left arm motor and sensory deficits associated with a frontoparietal hematoma evacuated 1 week earlier in another institution. Digital subtraction angiography showed a direct communication between an anterior parietal branch of the right middle cerebral artery and a parietal vein. Given the difficulty to reach the point of the fistula endovascularly because of the small caliber and tortuosity of the arterial feeder, as well as the short and relatively rapid flow through the arteriovenous communication, we decided to proceed with microsurgical treatment. Under intraoperative neurophysiologic monitoring the fistula was located with the aid of ICG-VA and interrupted (Video 1). Both control ICG-VA and postoperative angiogram confirmed resolution of the fistula. At a 3-month follow-up the patient had a complete neurologic recovery

Validation of an optical, computer-assisted technique for intraoperative tracking of 3-dimensional canine stifle joint motion

Background: Cranial cruciate ligament (CCL) rupture is the most common orthopedic pathology in dog and in men. In human, optical computer-assisted technique is considered as a repeatable and reliable method for the biomechanical assessment of joint kinematics and laxity in case of CCL surgery. Aim: To evaluate the repeatability and reliability afforded by clinical tests in terms of laxity measured by means of a computer-assisted tracking system in two canine CCL conditions: CCL-Intact, CCL-Deficient. Methods: Fourteen fresh frozen canine stifles were passively subjected to Internal/External (IE) rotation at 120\ub0 of flexion and Cranial drawer test (CC). To quantify the repeatability and the reliability, intra-class correlation coefficient (ICC) and the mean percent error were evaluated (\u394 r %). Results: The study showed a very good intra-class correlation, before and after CCL resection for kinematics tests. It was found a minimum ICC = 0.73 during the IE rotation in CCL-Intact and a maximum value of ICC = 0.97 for the CC displacement in CC-Deficient. IE rotation with CCL-Intact is the condition with the greatest \u394 r % = 14%, while the lowest \u394 r % = 6% was obtained for CC displacement in CCL-Deficient. Conclusion: The presented work underlined the possibility of using a computer-assisted method also for biomechanical studies concerning stifle kinematics and laxity

Acoustic Nature of the Boson Peak in Vitreous Silica

New temperature dependent inelastic x-ray (IXS) and Raman (RS) scattering data are compared to each other and with existing inelastic neutron scattering data in vitreous silica (v-SiO_2), in the 300 - 1775 K region. The IXS data show collective propagating excitations up to Q=3.5 nm^-1. The temperature behaviour of the excitations at Q=1.6 nm^-1 matches that of the boson peak found in INS and RS. This supports the acoustic origin of the excess of vibrational states giving rise to the boson peak in this glass.Comment: 10 pages and 4 figure

Performance optimization of InGaAs/InP SPADs for either low noise or high photon detection efficiency applications

InGaAs/InP Single-Photon Avalanche Diodes ( SPADs) can achieve high photon detection efficiency (PDE) with a thick absorber, but at the expense of higher dark count rate ( DCR). PDE and DCR also depend on the electric field inside the structure, which can be tailored in the design phase and influences the overall performance. We present the design and the experimental characterization of two different 10 mu m-diameter InGaAs/InP SPADs. The first one is intended for applications where low noise is the key requirement: at 225 K and 5 V excess bias, it features 1 kcps DCR, 25% PDE at 1550 nm and a timing jitter of 100 ps (FWHM). The second device is an InGaAs/InP SPAD optimized for PDE-enhanced applications, having a PDE up to 50% at 1550 nm, with a DCR of 20 kcps and a timing jitter of 70 ps (FWHM) at 225 K. Alternatively, it features a PDE of 37% at 1550 nm, with a DCR of just 3 kcps and a timing jitter of 100 ps (FWHM). When combined with a custom integrated circuit we developed, both devices show an afterpulsing probability as low as few percent with a gating frequency of 1 MHz and hold-off time of few microseconds at 225 K, allowing to achieve a photon count rate towards 1 Mcps