1,721,514 research outputs found
Uno studente fuori sede: Virgilio a Cremona
No full textIndagine sulla tradizione biografica e le testimonianze a proposito della permanenza di Virgilio a Cremona
Francesco Filelfo a Cremona tra campagna e scuola
No full textSi individuano attraverso l'epistolario e le "Odae" i due periodi di soggiorno di Francesco Filelfo a Cremona e si presentano i problemi affrontati con ripercussioni sulla sua attività letteraria
Molto più che una visita: Carlo Borromeo a Cremona nel 1575
No full textAnalisi della visita apostolica di Carlo Borromeo a Cremona nel 1575
Atomic force microscopy: a tool to quantitatively perform morpho-dimensional characterization of lipid rafts
No full textBACKGROUND: Lipid rafts are transient liquid-ordered domains that are enriched in sphingolipids, cholesterol and signalling proteins, resistant to solubilization by nonionic detergents at low temperatures. Atomic force microscopy (AFM), providing nanometer spatial resolution and operating in physiological-like conditions without fixation staining, or labeling, is an useful tool to quantitatively perform a morpho-dimensional characterization of lipid rafts (1).
AIM: The observation and the characterization of phase separation in purified plasma membranes is important for better understanding the lateral organization of the plasma membrane and lipid rafts.
METHODS: Lipid rafts were purified by ultracentrifugation on discontinuous sucrose gradient using extraction with Triton X-100. AFM imaging was performed using a Multimode Nanoscope IIIa. Topography AFM images were collected in tapping mode operating in liquid buffer. Membrane samples were visualized changing the temperature over a large range (25-40°C) using a heating control system (Multimode AFM high temperature heater).
RESULTS AND CONCLUSIONS: we have applied tapping mode AFM imaging to investigate MDA-MB-231 human breast cancer cells lipid rafts purified by ultracentrifugation on discontinuous sucrose gradient using Triton X-100. At room temperature, tapping mode AFM imaging showed membrane patches with microdomains protruding from their surface, with lateral dimensions in the range of 100-500nm in agreement with the range expected for lipid rafts as reported in literature. Interestingly, the size of the microdomains depend strongly on the temperature, when the temperature is increased (above 30°C) the smaller microdomains (less than 100nm in diameter) disappear while the larger microdomains (>500nm in diameter) are reduced in size. These data suggest that the dynamics of domain growth, and the distribution of domain sizes strongly depend on the temperature.
1 A Cremona et al. Atomic force microscopy imaging of lipid rafts of human breast cancer cells. Biochim Biophys Acta 2012. 1818(12):2943-9
Musicisti a Cremona fino all’Ottocento: viaggiatori o passanti? Cronaca di eventi mancati
No full textTra i viaggiatori illustri che si trovarono a passare a Cremona vi furono Marchetto Cara, Luigi Boccherini e Wolfganga Amadeus Mozart con il padre Leopold. Il contributo descrive le occasioni per cui queste illustri personalità soggiornarono nella città lombarda e analizza la mancata risonanza di quello che poteva essere, e non fu, un evento storico
THE USE OF ATOMIC FORCE MICROSCOPY TOGETHER WITH CLASSICAL BIOCHEMICAL TECHNIQUES TO STUDY ALTERATIONS OF MEMBRANE MICRODOMAINS INDUCED BY DHA IN MDA-MB-231 BREAST CANCER CELLS
Full text linkToday, the Western diet is substantially enriched in n-6 PUFAs (shifting the balance from the optimal n-6:n-3 ratio of 1–5:1 to approximately 20:1) due to the increased consumption of food items rich in n-6 and simultaneous reduction of fish intake. Diet enriched in n-6 PUFAs determines an unbalance between bioactive lipid mediators that are involved in regulating inflammation. These bioactive products can contribute to the development of numerous chronic diseases, including cancer. Many studies have demonstrated that genetic factors contribute only for 5% to the onset of cancer, while 95% is due to environmental conditions factors, including lifestyle-related factors (tobacco, alcohol and physical activity), external stimuli (radiation and infections) and diet that represents about 30–35% of the risk factors.
There are in vitro and in vivo evidences that the DHA and EPA administration is able to reduce cancer proliferation increase apoptosis as well as inhibit angiogenesis and metastasis, and to influence cancer differentiation. Several molecular mechanisms have been proposed for the anticancer activity of n-3 PUFAs, including inhibition of cell proliferation, anti-angiogenic action and enhancement of apoptosis. The multiple actions of n-3 PUFAs appear to involve multiple mechanisms that connect the cell membrane, the cytosol, and the nucleus. N-3 PUFAs may act also modulating cell membrane FA composition.
The plasma membrane is involved in many aspects of cell biology, including proliferation, differentiation and apoptosis. Phospholipids (PLs) fatty acid composition within cell membrane play a key role in maintaining its fluidity, structure and function. Thus, changes in membrane PLs fatty acid composition can influence the function of cells. In particular, n-3 PUFAs incorporated into membrane PLs can potentially affect a variety of plasma membrane physical properties including membrane thickness, fluidity and elasticity, structure and function in particular of membrane microdomains (lipid rafts); moreovere they can cause alteration of cell signaling pathways that lead to altered transcription factor activity and changes in gene expression. We have observed that DHA is incorporated in breast cancer cell membrane with different specificity for the PLs moiety. Moreover, we have demonstrated that the treatment with DHA determines a reduction of cell proliferation, inhibition of EGFR activity and induction of apoptotic process, suggesting that these effects might be the consequences of cell membrane alterations induced by FAs.
The main purpose of my research project was to analyze the effects of PUFA administration on membrane microdomain structure and function in breast cancer cells by a combination of biophysical and biochemical techniques. In my study I have used Atomic Force Microscopy (AFM) to perform a morpho-dimensional characterization of lipid rafts as Detergent-Resistant Membrane (DRM) isolated from MDA-MB-231 breast cells (estrogen receptor negative and over-expressing Epidermal growth factor receptor (EGFR)).
AFM providing nanometer spatial resolution and operating in physiological-like conditions without fixation, staining, or labeling, appears to be a useful tool to visualize and quantitatively characterize the topology of biological membranes as well as of their protein content.
AFM imaging of DRM fractions showed membrane patches whose height corresponds to the one awaited for a single lipid bilayer as well as the presence of microdomains with lateral dimensions in the order of a few hundreds of nanometers. Moreover, AFM-immunolabeling using specific antibodies suggested the presence, in these microdomains, of a characteristic marker of lipid rafts, the protein flotillin-1. In addition, my results suggested that AFM could be an useful tool to study the phase coexistence of a Liquid-disordered (Ld) and Liquid-ordered (Lo) domain in purified membrane microdomains.
Finally, I have investigated the role of lipid changes induced by DHA in membrane microdomain structure and function by biochemical tecniques. The data showed that the incubation with DHA determines its incorporation in all PLs, with different specificity for PI, PS and PC, and a reduction of sphingomyelin (SM) and cholesterol (Chol) content in membrane microdomains. Moreover, I have demonstrated that DHA can exclude key proteins, such as EGFR and Ras, from membrane microdomains, modifying their downstream signaling, such as Erk1/2 and Akt
Illuminismo e massoneria a Cremona (1776-1786)
No full textLa tesi tratta del ruolo che Isidoro Bianchi, Giambattista Biffi e la loggia massonica "San Paolo la Celeste" hanno avuto nella diffusione dei Lumi a Cremona negli anni 1776-178
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
Johann Caspar Steube, un avventuriero del Settecento a Cremona
No full textPresentazione e analisi delle pagine dal diario di J.C.Steube (tradotte in italiano) riguardanti la permanenza a Cremona dal 1773 al 1775 circa
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