Mechanical Stress Downregulates MHC Class I Expression on Human Cancer Cell Membrane

In our body, cells are continuously exposed to physical forces that can regulate different cell functions such as cell proliferation, differentiation and death. In this work, we employed two different strategies to mechanically stress cancer cells. The cancer and healthy cell populations were treated either with mechanical stress delivered by a micropump (fabricated by deep X-ray nanolithography) or by ultrasound wave stimuli. A specific down-regulation of Major Histocompatibility Complex (MHC) class I molecules expression on cancer cell membrane compared to different kinds of healthy cells (fibroblasts, macrophages, dendritic and lymphocyte cells) was observed, stimulating the cells with forces in the range of nano-newton, and pressures between 1 and 10 bar (1 bar = 100.000 Pascal), depending on the devices used. Moreover, Raman spectroscopy analysis, after mechanical treatment, in the range between 700–1800 cm⁻¹, indicated a relative concentration variation of MHC class I. PCA analysis was also performed to distinguish control and stressed cells within different cell lines. These mechanical induced phenotypic changes increase the tumor immunogenicity, as revealed by the related increased susceptibility to Natural Killer (NK) cells cytotoxic recognition.     

Recognition of morphometric vertebral fractures by artificial neural networks: analysis from GISMO Lombardia Database

Background

It is known that bone mineral density (BMD) predicts the fracture''s risk only partially and the severity and number of vertebral fractures are predictive of subsequent osteoporotic fractures (OF). Spinal deformity index (SDI) integrates the severity and number of morphometric vertebral fractures. Nowadays, there is interest in developing algorithms that use traditional statistics for predicting OF. Some studies suggest their poor sensitivity. Artificial Neural Networks (ANNs) could represent an alternative. So far, no study investigated ANNs ability in predicting OF and SDI. The aim of the present study is to compare ANNs and Logistic Regression (LR) in recognising, on the basis of osteoporotic risk-factors and other clinical information, patients with SDI≥1 and SDI≥5 from those with SDI = 0.

Methodology

We compared ANNs prognostic performance with that of LR in identifying SDI≥1/SDI≥5 in 372 women with postmenopausal-osteoporosis (SDI≥1, n = 176; SDI = 0, n = 196; SDI≥5, n = 51), using 45 variables (44 clinical parameters plus BMD). ANNs were allowed to choose relevant input data automatically (TWIST-system-Semeion). Among 45 variables, 17 and 25 were selected by TWIST-system-Semeion, in SDI≥1 vs SDI = 0 (first) and SDI≥5 vs SDI = 0 (second) analysis. In the first analysis sensitivity of LR and ANNs was 35.8% and 72.5%, specificity 76.5% and 78.5% and accuracy 56.2% and 75.5%, respectively. In the second analysis, sensitivity of LR and ANNs was 37.3% and 74.8%, specificity 90.3% and 87.8%, and accuracy 63.8% and 81.3%, respectively.

Conclusions

ANNs showed a better performance in identifying both SDI≥1 and SDI≥5, with a higher sensitivity, suggesting its promising role in the development of algorithm for predicting OF.     

In Situ Speciation and Distribution of Toxic Selenium in Hydrated Roots of Cowpea

The speciation and spatial distribution of selenium (Se) in hydrated plant tissues is not well understood. Using synchrotron-based x-ray absorption spectroscopy and x-ray fluorescence microscopy (two-dimensional scanning [and associated mathematical model] and computed tomography), the speciation and distribution of toxic Se were examined within hydrated roots of cowpea (Vigna unguiculata) exposed to either 20 µm selenite or selenate. Based upon bulk solution concentrations, selenate was 9-fold more toxic to the roots than selenite, most likely due to increased accumulation of organoselenium (e.g. selenomethionine) in selenate-treated roots. Specifically, uptake of selenate (probably by sulfate transporters) occurred at a much higher rate than for selenite (apparently by both passive diffusion and phosphate transporters), with bulk root tissue Se concentrations approximately 18-fold higher in the selenate treatment. Although the proportion of Se converted to organic forms was higher for selenite (100%) than for selenate (26%), the absolute concentration of organoselenium was actually approximately 5-fold higher for selenate-treated roots. In addition, the longitudinal and radial distribution of Se in roots differed markedly: the highest tissue concentrations were in the endodermis and cortex approximately 4 mm or more behind the apex when exposed to selenate but in the meristem (approximately 1 mm from the apex) when exposed to selenite. The examination of the distribution and speciation of Se in hydrated roots provides valuable data in understanding Se uptake, transport, and toxicity.Selenium (Se) is an essential micronutrient for humans and other animals (Rayman, 2008). At elevated concentrations, however, it is toxic, and the concentration range from deficiency to lethality is unusually narrow (Terry et al., 2000). Plants represent a direct entrance to the wider food chain as the main sources of dietary Se (Rayman, 2008). The uptake and accumulation of Se by plants is an important process in controlling the health risks resulting from Se deficiency or toxicity. Se toxicity to plants has been observed in arid and semiarid soils derived from seleniferous rocks and shales, although anthropogenic contamination is also of concern (Terry et al., 2000). Therefore, it is important that the mechanisms of Se uptake, transformation, and toxicity in plants are understood in order to reduce health risks.Selenite (Se[IV]) and selenate (Se[VI]) are the two dominant inorganic species in soils depending upon the redox potential and pH (Elrashidi et al., 1987). The mechanism of Se[VI] uptake is well known: it is taken up by plant roots via the high-affinity sulfate transporters (Terry et al., 2000) due to the similarity between Se[VI] and sulfate. By contrast, little is known about the uptake mechanism involved in Se[IV] in plant roots. Some studies suggested that Se[IV] is taken up via passive diffusion (Shrift and Ulrich, 1969; Arvy, 1993). Recently, Zhao et al. (2010) reported that the uptake of Se[IV] is mediated by the silicon (Si) influx transporter Lsi1 (OsNIP2;1) in rice (Oryza sativa). Furthermore, Se[IV] uptake was found to occur via both passive diffusion and phosphate transporters in the marine coccolithophore Emiliania huxleyi (Araie et al., 2011). Apart from the difference in their mechanisms of uptake, they also differ in their mobility within plants (Li et al., 2008). Se[VI] is relatively easily translocated from roots to shoots, whereas Se[IV] tends to accumulate within the roots (Arvy, 1993). Despite this important progress, much less is known about the sites of uptake of Se[IV]/Se[VI] and their possible chemical transformations in hydrated plant roots. This information regarding the in situ distribution and chemical forms of Se would be helpful in elucidating the mechanism(s) responsible for Se uptake, transformation, and toxicity in plants.Recent advances in synchrotron-based techniques allow in situ measurement of the distribution of metal(loid)s in hydrated fresh plant tissues (Kopittke et al., 2011, 2012; Lombi et al., 2011a). In particular, the prototype Maia detector system, jointly developed by the Australian Synchrotron, the Commonwealth Scientific and Industrial Research Organization, and the Brookhaven National Laboratory, represents a new-generation x-ray fluorescence detector and real-time processing approach that provides unprecedented capabilities in in situ element imaging and measurement (Lombi et al., 2011b). The Maia uses an annular array of 384 silicon-diode detectors positioned in a backscatter geometry to subtend a large solid angle (approximately 1.3 steradian) and to achieve high count-rate capacity (Kirkham et al., 2010). Data acquisition times are approximately 10 to 100 times faster in the Maia than for other detectors, thereby allowing analysis of highly hydrated biological specimens (e.g. roots) without observable damage (Lombi et al., 2011a). This has allowed us to overcome the analytical challenges of examining the two-dimensional and virtual three-dimensional distribution of low-concentration metal(loid)s in hydrated and fresh plant tissues (Kopittke et al., 2011, 2012; Lombi et al., 2011a, 2011c).In this study, we investigated the speciation and quantified the longitudinal and radial distribution of Se in hydrated roots of cowpea (Vigna unguiculata) exposed to either Se[IV] or Se[VI]. Cowpea is a model species of rhizotoxicity and is also one of the most important food legume crops in the semiarid tropics, where Se toxicity is often a concern. The chemical forms of Se in cowpea roots were first examined using x-ray absorption spectroscopy (XAS). Second, with x-ray fluorescence microscopy (µ-XRF), we used two-dimensional imaging (coupled with an associated mathematical model to calculate concentrations of Se within various tissues of the root cylinder) to determine the spatially resolved distribution of Se within root tissues. Additionally, sequential tomography was used to provide virtual three-dimensional reconstructions of Se distribution in roots, enabling comparison of computed tomography with the mathematical model.     

NGF and romantic love

Romantic love is the catalyst behind the spread of the human life. The neurobiology of love embraces the hypothesis that what we call "romantic attachment" or "romantic love" may be at least in part the expression of biological factors. A corollary of this hypothesis states that it is possible to learn much about the nature of human love by studying the molecules involved in the expression of social and affiliative behaviours. Under this theoretical framework, we have investigated the changes in plasma neurotrophin levels in subjects with early stage romantic love. A positive association between the intensity of early romantic feelings and serum levels of nerve growth factor (NGF) has been identified. These findings link love with biologically relevant pathways for neuron survival and illuminate the biochemical correlates of such a complex feeling that so deeply affects our own lives. The progresses in the neurobiology of love suggest that this kind of research may open a new window onto our understanding of the very nature of human romantic bonding.     

Vitiligo: A Possible Model of Degenerative Diseases

Vitiligo is characterized by the progressive disappearance of pigment cells from skin and hair follicle. Several in vitro and in vivo studies show evidence of an altered redox status, suggesting that loss of cellular redox equilibrium might be the pathogenic mechanism in vitiligo. However, despite the numerous data supporting a pathogenic role of oxidative stress, there is still no consensus explanation underlying the oxidative stress-driven disappear of melanocytes from the epidermis. In this study, in vitro characterization of melanocytes cultures from non-lesional vitiligo skin revealed at the cellular level aberrant function of signal transduction pathways common with neurodegenerative diseases including modification of lipid metabolism, hyperactivation of mitogen-activated protein kinase (MAPK) and cAMP response element-binding protein (CREB), constitutive p53-dependent stress signal transduction cascades, and enhanced sensibility to pro-apoptotic stimuli. Notably, these long-term effects of subcytotoxic oxidative stress are also biomarkers of pre-senescent cellular phenotype. Consistent with this, vitiligo cells showed a significant increase in p16 that did not correlate with the chronological age of the donor. Moreover, vitiligo melanocytes produced many biologically active proteins among the senescence-associated secretory phenotype (SAPS), such as interleukin-6 (IL-6), matrix metallo proteinase-3 (MMP3), cyclooxygenase-2 (Cox-2), insulin-like growth factor-binding protein-3 and 7 (IGFBP3, IGFBP7). Together, these data argue for a complicated pathophysiologic puzzle underlying melanocytes degeneration resembling, from the biological point of view, neurodegenerative diseases. Our results suggest new possible targets for intervention that in combination with current therapies could correct melanocytes intrinsic defects.     

The Antimicrobial Domains of Wheat Puroindolines Are Cell-Penetrating Peptides with Possible Intracellular Mechanisms of Action

The puroindoline proteins (PINA and PINB) of wheat display lipid-binding properties which affect the grain texture, a critical parameter for wheat quality. Interestingly, the same proteins also display antibacterial and antifungal properties, attributed mainly to their Tryptophan-rich domain (TRD). Synthetic peptides based on this domain also display selectivity towards bacterial and fungal cells and do not cause haemolysis of mammalian cells. However, the mechanisms of these activities are unclear, thus limiting our understanding of the in vivo roles of PINs and development of novel applications. This study investigated the mechanisms of antimicrobial activities of synthetic peptides based on the TRD of the PINA and PINB proteins. Calcein dye leakage tests and transmission electron microscopy showed that the peptides PuroA, Pina-M and Pina-W→F selectively permeabilised the large unilamellar vesicles (LUVs) made with negatively charged phospholipids mimicking bacterial membranes, but were ineffective against LUVs made with zwitterionic phospholipids mimicking eukaryotic membranes. Propidium iodide fluorescence tests of yeast (Saccharomyces cerevisiae) cells showed the peptides were able to cause loss of membrane integrity, PuroA and Pina-M being more efficient. Scanning electron micrographs of PINA-based peptide treated yeast cells showed the formation of pits or pores in cell membranes and release of cellular contents. Gel retardation assays indicated the peptides were able to bind to DNA in vitro, and the induction of filamental growth of E. coli cells indicated in vivo inhibition of DNA synthesis. Together, the results strongly suggest that the PIN-based peptides exert their antimicrobial effects by pore formation in the cell membrane, likely by a carpet-like mechanism, followed by intracellular mechanisms of activity.