L’articolo presenta il percorso didattico svolto in una classe di seconda media con lo scopo di indagare lo sviluppo delle convinzioni degli allievi riguardo agli elementi e ai processi efficaci da ...attuare al fine di una risoluzione ottimale di un problema matematico. L’itinerario si compone di molteplici attività cooperative attraverso le quali trattare in modo puntuale i processi coinvolti nel ciclo della matematizzazione. Gli allievi hanno affrontato tali proposte con motivazione e interesse, apprezzando in particolare la multidisciplinarietà relativa alla comprensione e alla lettura di un testo. I risultati ottenuti mostrano come gli allievi, durante l’attività di risoluzione di un problema matematico, abbiano imparato a spostare il loro focus dal prodotto ai processi: l’attenzione che prima era rivolta unicamente al risultato matematico viene ora ad essere ripartita anche su processi importanti quali la lettura, l’applicazione di algoritmi, la scelta delle operazioni, l’attuazione di strategie metacognitive e la riflessione e l’interpretazione del risultato matematico ottenuto.
The cross-talk between beta cells and endothelium plays a key role in islet physiopathology and in the revascularization process after islet transplantation. However, the molecular mechanisms ...involved in this cross-talk are not fully elucidated. Extracellular vesicles (EVs) are secreted membrane nanoparticles involved in inter-cellular communication through the transfer of proteins and nucleic acids. The aims of this study were: 1) isolation and characterization of EVs from human islets; 2) evaluation of the pro-angiogenic effect of islet-derived EVs on human islet endothelial cells (IECs). EVs were isolated by ultracentrifugation from conditioned medium of human islets and characterized by nanotrack analysis (Nanosight), FACS, western blot, bioanalyzer, mRNA/microRNA RT-PCR array. On IECs, we evaluated EV-induced insulin mRNA transfer, proliferation, resistance to apoptosis, in vitro angiogenesis, migration, gene and protein profiling. EVs sized 236±54 nm, expressed different surface molecules and islet-specific proteins (insulin, C-peptide, GLP1R) and carried several mRNAs (VEGFa, eNOS) and microRNAs (miR-27b, miR-126, miR-130 and miR-296) involved in beta cell function, insulin secretion and angiogenesis. Purified EVs were internalized into IECs inducing insulin mRNA expression, protection from apoptosis and enhancement of angiogenesis. Human islets release biologically active EVs able to shuttle specific mRNAs and microRNAs (miRNAs) into target endothelial cells. These results suggest a putative role for islet-derived EVs in beta cell-endothelium cross-talk and in the neoangiogenesis process which is critical for engraftment of transplanted islets.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Introduction. The clinical course of Coronavirus Disease 2019 (COVID-19) is highly heterogenous, ranging from asymptomatic to fatal forms. The identification of clinical and laboratory predictors of ...poor prognosis may assist clinicians in monitoring strategies and therapeutic decisions. Materials and Methods. In this study, we retrospectively assessed the prognostic value of a simple tool, the complete blood count, on a cohort of 664 patients (F 260; 39%, median age 70 (56-81) years) hospitalized for COVID-19 in Northern Italy. We collected demographic data along with complete blood cell count; moreover, the outcome of the hospital in-stay was recorded. Results. At data cut-off, 221/664 patients (33.3%) had died and 453/664 (66.7%) had been discharged. Red cell distribution width (RDW) (χ2 10.4; p<0.001), neutrophil-to-lymphocyte (NL) ratio (χ2 7.6; p=0.006), and platelet count (χ2 5.39; p=0.02), along with age (χ2 87.6; p<0.001) and gender (χ2 17.3; p<0.001), accurately predicted in-hospital mortality. Hemoglobin levels were not associated with mortality. We also identified the best cut-off for mortality prediction: a NL ratio>4.68 was characterized by an odds ratio for in-hospital mortality OR=3.40 (2.40-4.82), while the OR for a RDW>13.7% was 4.09 (2.87-5.83); a platelet count>166,000/μL was, conversely, protective (OR: 0.45 (0.32-0.63)). Conclusion. Our findings arise the opportunity of stratifying COVID-19 severity according to simple lab parameters, which may drive clinical decisions about monitoring and treatment.
Purpose: Platelet-activating factor (PAF), a phospholipid mediator of inflammation, has been recently detected on tumor cells but
its effect in tumor development is largely undefined.
Experimental ...Design: To address its potential role in tumor biology, we inhibited intratumor PAF activity by engineering tumor cell lines to express
plasma PAF-acetylhydrolase (PAF-AH), the major PAF-inactivating enzyme, and studied their behavior in vitro and in vivo .
Results: When transfected with PAF-AH, KS-Imm human Kaposi’s sarcoma cells implanted in SCID mice and B16F10 mouse melanoma cells
implanted in syngenic C57Bl/6J mice showed significantly reduced vascularization and growth allowing longer survival compared
with control tumors. The amounts of bioactive PAF extracted from PAF-AH-transfected tumors were significantly reduced. In vitro , expression of PAF-AH did not influence cell proliferation, whereas it inhibited PAF-dependent cell motility in Kaposi’s
sarcoma cells that express PAF-receptor but not in melanoma cells that did not express it. On the other hand, PAF-induced
endothelial tubulogenesis in Matrigel was inhibited by incubation with supernatant from PAF-AH-transfected melanoma cells,
indicating that PAF-AH inhibits in vitro neoangiogenesis.
Conclusions: We demonstrated that in situ PAF inactivation affects tumor vascularization and growth through inhibition of neoangiogenesis and, in the case of cells
expressing PAF receptor, also tumor cell motility.
In the present study, we evaluated whether motility of Kaposi's sarcoma (KS) spindle cells induced by HIV-1 Tat protein is dependent on the synthesis of platelet-activating factor (PAF). The results ...obtained indicate that Tat induced a dose-dependent synthesis of PAF from KS cells at a concentration as low as 0.1 ng/ml. PAF production started rapidly after Tat stimulation, peaking at 30 minutes and declining thereafter. Tat-induced cell migration was also a rapid event starting at 30 minutes. The motility was abrogated by addition of a panel of chemically unrelated PAF receptor antagonists (WEB 2170, CV 3988, CV 6209, and BN 52021), suggesting that the synthesized PAF mediates the motogenic effect of Tat. This effect was also present on cells plated on a type-I collagen-, fibronectin-, or basement membrane extract-coated surface. Expression of PAF receptor-specific mRNA was detected in KS cells. In addition, examination of the cytoskeletal organization showed that Tat-mediated KS cell redistribution of actin filaments and shape change was also inhibited by a PAF receptor antagonist. Moreover, PAF receptor blockade prevented the up-regulation of β1 integrin and the down-regulation of αvβ3 observed after stimulation of KS cells with Tat. In conclusion, the results of the present study indicate that Tat-induced PAF synthesis plays a critical role in triggering the events involved in motility of KS cells.
Although CD40 is expressed by several tumor lines and is up-regulated in tumor vascular endothelium, its role in tumor biology is still unclear. In the present study, we investigated the role of CD40 ...in the growth and vascularization of Kaposi's sarcoma (KS). In vitro, stimulation of CD40 induced migration of KS cells and inhibited vincristine-induced apoptosis. Similarly, the CD40 engagement on endothelial cells resulted in cell contraction, migration, and prevention of serum withdrawal-apoptosis. To understand the biological relevance of CD40 in vivo, KS cells were engineered to express and release a soluble form of CD40 (KS-sCD40) able to disrupt CD40-CD154 interaction. SCID mice s.c. injected with KS-sCD40 cells developed tumors that were significantly smaller than those induced by control cells (KS-neo). In addition, KS-sCD40 tumors showed several areas of necrosis, diffuse presence of apoptotic cells, and poor vascularization. In contrast, KS-neo tumors showed few or absent areas of necrosis and apoptosis and intense vascularization. Moreover, anti-CD40 Abs stimulated neo-angiogenesis in a murine model in which s.c. implantation of Matrigel was used as a vehicle for the delivery of mediators. These observations provide demonstration that CD40 supports tumor cell survival, growth, and neo-vascularization of KS.
Platelet-activating factor (PAF) is a phospholipid mediator of inflammation which has been implicated in rejection. The interaction of anti-alpha-galactosyl natural antibodies (anti-alpha gal Abs) ...with endothelial cells is the initial step for the development of xenograft rejection. In our study, we stimulated porcine aortic endothelial cells (PAEC) with anti-alpha gal IgG to investigate the synthesis of PAF from PAEC and its biological consequences.
PAF was extracted and chromatographically purified from cultured PAEC stimulated with baboon anti-alpha gal Abs. The Abs induced a dose-dependent synthesis of PAF peaking after 30 min of incubation, and decreasing thereafter. Concomitant cell shape change, motility, and cytoskeleton redistribution were observed. These events were prevented by addition of a panel of PAF-receptor antagonists. An SV40 T-large antigen-immortalized PAEC line was engineered to express PAF acetyl-hydrolase (PAF-AH) cDNA, the major PAF-inactivating enzyme. These transfected cells exposed to anti-alpha gal Abs showed reduced cell contraction and motility compared with empty vector-transfected cells. Moreover, in PAEC stimulated with anti-alpha gal Abs, the synthesis of PAF promoted the adhesion of a monocytic cell line as shown by the inhibitory effect of PAF-receptor antagonists and of PAF-AH expression. Finally, studies on cell monolayer demonstrated an enhanced permeability 48 hr after exposure to anti-alpha gal Abs, and this increase was prevented by PAF-inactivation and by PAF-receptor blockade.
These results demonstrate that on stimulation with anti-alpha gal Abs, PAEC synthetize PAF which can contribute to several vascular events involved in xenograft rejection.
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