Glucosamine-induced endoplasmic reticulum stress affects GLUT4 expression via activating transcription factor 6 in rat and human skeletal muscle cells

AIMS/HYPOTHESIS: Glucosamine, generated during hyperglycaemia, causes insulin resistance in different cells. Here we sought to evaluate the possible role of endoplasmic reticulum (ER) stress in the induction of insulin resistance by glucosamine in skeletal muscle cells. METHODS: Real-time RT-PCR analysis, 2-deoxy-D: -glucose (2-DG) uptake and western blot analysis were carried out in rat and human muscle cell lines. RESULTS: In both rat and human myotubes, glucosamine treatment caused a significant increase in the expression of the ER stress markers immunoglobulin heavy chain-binding protein/glucose-regulated protein 78 kDa (BIP/GRP78 [also known as HSPA5]), X-box binding protein-1 (XBP1) and activating transcription factor 6 (ATF6). In addition, glucosamine impaired insulin-stimulated 2-DG uptake in both rat and human myotubes. Interestingly, pretreatment of both rat and human myotubes with the chemical chaperones 4-phenylbutyric acid (PBA) or tauroursodeoxycholic acid (TUDCA), completely prevented the effect of glucosamine on both ER stress induction and insulin-induced glucose uptake. In both rat and human myotubes, glucosamine treatment reduced mRNA and protein levels of the gene encoding GLUT4 and mRNA levels of the main regulators of the gene encoding GLUT4 (myocyte enhancer factor 2 a [MEF2A] and peroxisome proliferator-activated receptor-gamma coactivator 1alpha [PGC1alpha]). Again, PBA or TUDCA pretreatment prevented glucosamine-induced inhibition of GLUT4 (also known as SLC2A4), MEF2A and PGC1alpha (also known as PPARGC1A). Finally, we showed that overproduction of ATF6 is sufficient to inhibit the expression of genes GLUT4, MEF2A and PGC1alpha and that ATF6 silencing with a specific small interfering RNA is sufficient to completely prevent glucosamine-induced inhibition of GLUT4, MEF2A and PGC1alpha in skeletal muscle cells. CONCLUSIONS/INTERPRETATION: In this work we show that glucosamine-induced ER stress causes insulin resistance in both human and rat myotubes and impairs GLUT4 production and insulin-induced glucose uptake via an ATF6-dependent decrease of the GLUT4 regulators MEF2A and PGC1alpha

Rapporto sugli eventi sismici del Beneventano

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Detection of short-chain aldehydes in marine organisms: the diatom Thalassiosira rotula

Short-chain aldehydes are analysed by GC–MS and NMR after their transformation into the corresponding carboxyethylethylidene (CET) derivatives via Wittig reaction. The procedure implies the treatment of the aldehyde with (carbetoxyethylidene)- triphenylphosphorane under very mild conditions. The method is suitable for the detection of short and medium chain aldehydes. CET derivatives are easily prepared and can be utilised for the analysis of raw biological samples. The efficacy of the method has been tested in the identification of biologically active aldehydes in the marine diatom Thalassiosira rotula. At least two compounds, trans,trans-octadienal and 2-trans-4-trans-2,4,7-octatrienal, that have not been revealed in previous papers are unambiguously identified in the microalga

Le lenti del passato. Approcci multiscalari all'archeologia

Il presente volume raccoglie gli Atti del Convegno di Studi dal titolo "Le lenti del passato. Approcci multiscalari all'archeologia", tenutosi a Padova dal 21 al 22 dicembre 2021 e organizzato dagli allievi della Scuola di Specializzazione in Beni Archeologici dell'Università di Padova con il sostegno del Dipartimento dei Beni Culturali. Il Convegno, aperto a tutti gli Specializzandi inBeni Archeologici del terrirorio nazionale, ha visto il susseguirsi di numerose relazioni volte ad affrontare lo studio del dato archeologico secondo un approccio multiscalare e multidisciplinare, dalla più ampia osservazione del paesaggio e delle dinamiche di ampio respiro al singolo contesto archeologico, dallo studio dei manufatti alle analisi di laboratorio. Oggetto privilegiato dei contributi sono state le metodologie di indagini declinate secondo molteplici approcci, prendendo in analisi contesti estremamente variegati sia dal punto di vista della collocazione geografica che cronologica. Il volume, che raccoglie e organizza in quattro sezioni (Macroscala, Mesoscala, Scala di intransito, Microscala) queste ricerche, vuole rappresentare non solo l'esito editoriale di una fruttuosa esperienza di confronto ma anche uno spunto per futuri incontri di studi che vedano come protagonisti gli allievi delle Scuole di Specializzazione italiane

New birth-control aldehydes from the marine diatom Skeletonema costatum: characterization and biogenesis

The paper describes the identification of short-chain aldehydes (4–7) from the marine diatom Skeletonema costatum, and their effects on copepod egg viability and sea urchin cell division. Compounds 4–7 were isolated as carboethoxyethylidene (CET) derivatives and their characterization was performed by NMR and GCMS analyses. Evidence is presented to support the defensive role and biosynthetic origin of these compounds in S. costatum

Ultrasensitive nanoprobes based on metallo-dielectric crystals integrated onto optical fiber tips using the Breath Figures technique

We present recent results on the fabrication of metallo-dielectric structures on the optical fiber tip by using a selfassembly technique. Our studies aim to attain advanced nanostructured sensors by exploiting easy and low cost fabrication processes suitable to be employed in massive production of technologically advanced devices in the roadmap of the Lab on Fiber Technology. The pursued approach basically consists in the preliminary preparation of a patterned polymeric film by the breath figure technique, directly on the optical fiber tip, and in the successive metal deposition by evaporation. The experimental results demonstrate the successful creation of a metallo-dielectric honeycomb pattern on the optical fiber tip. The experimental spectral features are in good agreement with the numerical analysis, elucidating the photonic and plasmonic interactions occurring in the Lab onto the optical fiber tip. The sensing properties of the optical fiber probes have been successfully explored in terms of sensitivity to the surrounding refractive index changes demonstrating their potentialities for chemical and biological sensing application

Fiber Bragg Grating for Temperature Monitoring During Medical Radiofrequency Treatments

In this work, it is proposed the integration of fiber optic sensors with commercial medical instrumentation, for temperature monitoring during tumor radiofrequency thermal ablation (RFTA) treatments. The heat propagation over the area under treatment is measured by means of a specific configuration, consisting of several Fiber Bragg Grating (FBG) sensors properly bounded to the RFTA probe and being positioned close to the region reached by RF electrodes. Our ex-vivo experiments on ex vivo animal liver and kidney, confirm that we were able to monitor in real time the temperature increase during different and consecutive RF discharges performed with the laparoscopic bipolar device Habib 4x, with a temperature resolution of 0.1°C and a spatial resolution of 5mm