1,721,013 research outputs found
Hyaluronan as tunable drug delivery system
No full textThe hyaluronan (HA) polymer is an important macromolecule of extracellular matrix with remarkable structure and functions: it is a linear and unbranched polymer without sulphate or phosphate groups and has key role in several biological processes in mammals. It is ubiquitous in mammalian tissues with several and specific functions, influencing cell proliferation and migration as well as angiogenesis and inflammation. To exert these important functions in tissues HA modifies the concentration and size. Considering this HA content in tissues is carefully controlled by different mechanisms including covalent modification of the synthetic enzymes and epigenetic control of their gene expression. The function of HA is also critical in several pathologies including cancer, diabetes and chronic inflammation. Among these biological roles, the structural properties of HA allow to use this polymer in regenerative medicine including cosmetics and drug delivery. HA takes advantage from its capacity to form gels even at concentration of 1% producing scaffolds with very intriguing mechanical properties. These hydrogels are useful in regenerative medicine as biocompatible material for advanced therapeutic uses. In this review we highlight the biological aspects of HA addressing the mechanisms controlling the HA content in tissues and its role as drug delivery system
A nutrient sentinel stands guard outside the cell
No full textNutrient sensing is a critical cell function that regulates survival and growth by adjusting metabolism. During nutrient shortage, autophagy enables the recycling of major cellular components to prevent cell death. Understanding the mechanisms that trigger and control autophagy is of fundamental importance, as this degradative pathway plays a pivotal role in many diseases. Gubbiotti et al. report the identification of a new player, the proteoglycan decorin, which functions as a nutrient sensor in the extracellular matrix and controls autophagy in the heart
Espressione genica ed analisi proteica nelle lesioni del tendine d’Achille: studio comparativo tra area lesionata e area sana dello stesso tendine
No full textIntroduzione: La matrice extracellulare (ECM) di 19 tendini di Achille umani lesionati è stata analizzata comparando la composizione di campioni prelevati dall’area prossima alla zona di rottura e campioni prelevati da un’area apparentemente sana dello stesso tendine. Obiettivo dello studio è stato analizzare l’espressione genica e le molecole della ECM, così come le metalloproteasi (MMPs) e gli inibitori tissutali delle metalloproteasi (TIMPs) implicati nel turnover dell’ECM, in modo da valutare l’attività cellulare e cosa potrebbe essere accaduto nelle lesioni del tendine d’Achille. L’ipotesi dello studio è che nello stesso tendine ci sono differenze nell’espressione genica delle molecole dell’ECM e nell’attività delle metalloproteasi tra aree lesionate ed aree apparentemente sane. Materiali e Metodi: L’espressione genica e le principali molecole dell’ECM (collagene tipo I e IX, decorina e versicano (GAGs), inclusi gli enzimi implicati nel loro metabolismo come le MMP2 e 9 e TIMP1 e 2, sono state analizzate mediante metodiche di real time RT-PCR, di zimografia e di Fluorophore Assisted Carbohydrate Electrophoresis.
Risultati: Non è stata osservata l’espressione del gene per il collagene tipo IX. L’espressione dei geni per il collagene tipo I, GAGs, MMPs e TIMPs è stata maggiormente rappresentata nell’area della lesione tendinea (p<0.05). L’espressione delle MMPs è stata confermata dalla zimografia che ha mostrato un marcato incremento dell’attività della MMP9 nell’area della lesione tendinea (p<0.05). La composizione chimica del tendine è risultata diversa nelle due aree analizzate: nella sana il contenuto in GAGs era significativamente più alto che nell’area lesionata (p<0.05).
Conclusioni: L’assenza dell’espressione del gene per il collagene tipo IX testimonia che non vi è metaplasma fibrocartilaginea nelle rotture tendinee come descritto per le tendinopatie. Nell’area lesionata, i tenociti cercano di ripristinare la normale composizione dell’ECM incrementando la sintesi proteica ma senza produzione effettiva di GAGs: la scarsa quantità di GAGs nell’area lesionata indica che i processi catabolici prevalgono su quelli sintetici. Tali dati supportano l’ipotesi che le zone di rottura di un tendine d’Achille sono sottoposte and un marcato riarrangiamento a livello molecolare causato dall’attività delle MMPs e dei TIMPs e ne sottolinea il loro ruolo nella patologia tendinea
Gene expression and protein analysis in ruptured human Achilles tendons. A comparison between ruptured and healthy area of the same tendon
No full textIntroduction: We studied the extracellular matrix (ECM) of 19 ruptured human Achilles tendons, comparing the tissue composition of specimens taken from area close to the rupture with specimens harvested from an apparently healthy area in the same tendon. The hypothesis was that the metabolism of these molecules is altered in patients with Achilles tendon rupture.
Materials and Methods: We compared the gene expression and the protein localization of the main ECM molecules (collagen type I, decorin and versican) including enzymes involved in their metabolism as matrix metalloproteases (MMP2 and 9) and tissue inhibitory of metalloproteinase (TIMP 1 and 2) using a Real Time PCR, zymography and FACE analysis.
Results: The gene expression of proteoglycans core protein, collagen type I, MMPs and TIMPs is more represented in the area close to the tendon rupture (p<0.05). The expression of MMPs was confirmed by zymography analysis, showing a marked increase of gelatinolytic activity in area close to the tendon rupture (p<0.05). The chemical composition of tendon changes showing that in the healthy area the carbohydrate content is higher than the ruptured area (p<0.05).
Discussion/Conclusions: In the ruptured area, the tenocytes tried to restore the normal proteoglycan pattern increasing the core protein synthesis but without the normal glycosaminoglycan production. Our data support the hypothesis that, in human tendons, the tissue in the area of rupture undergoes marked rearrangement at molecular levels based on the MMP2 activity, and support the role of MMPs in the tendon pathology
Gene expression and protein analysis in ruptured human Achilles tendons. A comparison between ruptured and healthy area of the same tendon
No full textIntroduction: We studied the extracellular matrix (ECM) of 19 ruptured human Achilles tendons, comparing the tissue composition of specimens taken from area close to the rupture with specimens harvested from an apparently healthy area in the same tendon. Aim of this study was to analyze gene expression and ECM molecules as well as MMPs and TIMPs involved in ECM turnover, in order to asses the cellular activity and what might happen in Achilles tendon rupture. The hypothesis was that in the same tendon there are many differences in gene expression of ECM molecules and metalloproteinases activity between ruptured and macroscopically healthy areas. Materials and Methods: We compared the gene expression and the protein localization of the main ECM molecules (collagen type I and IX, decorin and versican) including enzymes involved in their metabolism as matrix metalloproteases (MMP2 and 9) and tissue inhibitory of metalloproteases (TIMP 1 and 2) using a real time RT-PCR, zymography and Fluorophore Assisted Carbohydrate Electrophoresis analysis. Results: We didn’t observe any collagen IX gene expression. The gene expression of collagen type I, proteoglycans GAGs, MMPs and TIMPs was more represented in the area close to the tendon rupture (p<0.05). The expression of MMPs was confirmed by zymography analysis, showing a marked increase of MMP9 activity in area close to the tendon rupture (p<0.05). The chemical composition of tendon changed showing that in the healthy area the GAGs content was higher than the ruptured area (p<0.05). Conclusions: The lack of gene expression of collagen IX testifies that there wasn’t any fibrocartilagineous metaplasia as described in tendinopathy. In the ruptured area, the tenocytes tried to restore the normal proteoglycan pattern increasing the protein synthesis but without the normal glycosaminoglycan production. The low amount of GAGs in the ruptured area indicates that the catabolic processes prevail over the synthetic activity. Our data support the hypothesis that, in human tendons, the tissue in the area of rupture undergoes marked rearrangement at molecular levels based on the MMP’s activity, and support the role of MMPs in the tendon pathology
A Nonradioactive Method to Measure Hyaluronan Synthase Activity
No full textHyaluronan (HA) is a component of the extracellular matrix that is involved in many physiological and pathological processes. As HA modulates several functions (i.e., cell proliferation and migration, inflammation), its presence in the tissues can have positive or negative effects. HA synthases (HAS) are a family of three isoenzymes located on the plasma membrane that are responsible for the production of such polysaccharide and, therefore, their activity is critical to determine the accumulation of HA in tissues. Here, we describe a nonradioactive method to quantify the HAS enzymatic activity in crude cellular membrane preparation
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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