Cytotoxicity and morphological transforming potential of cobalt nanoparticles,microparticles and ions in Balb/3T3 mouse fibroblasts: an in vitro model

We previously described the behaviour of different cobalt forms, i.e., cobalt nanoparticles (CoNP), cobalt microparticles (CoMP) and cobalt ions (Co²⁺), in culture medium (dissolution, interaction with medium components, bioavailability) as well as their uptake and intracellular distribution in Balb/3T3 mouse fibroblasts (Sabbioni, Nanotoxicology, 2012). Here, we assess the cytotoxicity and morphological transformation of CoNP compared not only to Co²⁺, but also to CoMP and to released Co products. Cytotoxicity reached maximum at 4-h exposure, with ranking CoMP > CoNP > Co²⁺. However, if we consider toxicity as a function of intracellular Co, toxicity of the ionic forms seems to prevail over the particles. Co forms other than Co²⁺ released from particles had toxicity intermediate between particles and ions. Alterations in concentrations of essential elements (Cu, Mg, Zn) in cells exposed to Co particles may contribute to toxicity. Both CoMP and CoNP (but not Co²⁺ and other released Co forms) induced morphological transformation (CoMP > CoNP). This was dependent on reactive oxygen species production and lipid peroxidation, as indicated by inhibition of type III foci with ascorbic acid. The present results suggest that the previously demonstrated massive mitochondrial and nuclear Co internalisation and DNA adduct formation by CoMP and CoNP (Sabbioni, Nanotoxicology, 2012) induce toxicity and transformation. On the contrary, the role of ions released by particles in culture medium is negligible. Thus, both the chemical and the physical properties of Co particles contribute to cytotoxicity and morphological transformation.     

Fibrillin-1 (FBN1) gene frameshift mutations in Marfan patients: genotype–phenotype correlation

Marfan syndrome (MFS) is a multisystemic disease associated with mutations in the fibrillin-1 gene. Most of the reported mutations are missense substitutions mainly affecting the epidermal growth factor (EGF)-like protein domain structure and the calcium-binding (cb) site. The aim of our study was to investigate the correlation between fibrillin-1 frameshift mutations and the clinical phenotype in patients affected by MFS. In 48 out of 66 Marfan patients a pathogenetic mutation was found. We detected novel mutations causing premature termination codon in exons 19, 37, 40 and 41 of four Italian patients. The first mutation in exon 19 (cbEGF #8 domain) results in a clinical phenotype involving mainly the skeletal and cardiovascular systems. Interestingly, we noticed that, while mutations in exons 37 and 41 (eight cysteine domains #4 and #5) are milder, the mutation in exon 40 (cbEGF #24 domain) is more severe and causes major cardiovascular involvement with thoracic and abdominal aortic aneurysms. It is noteworthy that the degree of the severity in the phenotype of one of our patients and another from the literature carrying a mutation in exon 41 could be explained with alterations in mRNA expression.     

Chronic expression of P-selectin on endothelial cells stimulated by the T-cell cytokine, interleukin-3

P-selectin expressed on the surface of endothelium mediates leukocyte adhesion in vitro and rolling in vivo. Several inducers of cell-surface P-selectin expression on endothelial cells (EC) have previously been identified, all of which yield transient cell-surface expression of P- selectin lasting minutes to a few hours. We now show that a T- lymphocyte product, interleukin-3 (IL-3), stimulates the long-term endothelial cells (HUVEC). IL-3 induced cell-surface P-selectin expression in two phases. An initial peak at 10 minutes was followed by a prolonged upregulation beginning 16 hours after IL-3 addition and lasting at least 4 days. The level of P-selectin expression induced by IL-3 added for 48 hours was similar to that induced by treatment of HUVEC for 10 minutes with thrombin, and the effect of adding IL-3 for 48 hours followed by thrombin for 10 minutes was additive. Induction of cell-surface P-selectin expression by IL-3 was blocked by pretreatment of EC with a blocking monoclonal antibody against the IL-3 receptor alpha-chain. Lipopolysaccharide (LPS), tumor necrosis factor alpha (TNF alpha) and a mutant form of IL-3 with decreased potency did not induce cell-surface P-selectin expression after 48 hours' incubation with HUVEC, suggesting that the effect was specific to IL-3. The increase in cell-surface P-selectin expression occurring after 16 hours of incubation with IL-3 was accompanied by a similar prolonged increase in the steady-state mRNA level that was not observed at 10 minutes after IL-3 addition. As T-lymphocyte infiltration is a hallmark of chronic inflammation, our observations suggest that the secretion of IL-3 by T lymphocytes may serve to maintain the inflammatory state during chronic inflammation.     

Cutaneous polyarteritis nodosa in a child and a review of the literature

The cutaneous form of polyarteritis nodosa in children is extremely rare. Findings are usually limited to the skin, muscles and joints. It has a benign but often chronic course. We describe an 8-y-old girl with cutaneous PAN, with extensive livedo reticularis on lower and upper extremities, tender subcutaneous nodules, arthralgia and right ankle swelling. Skin biopsy revealed vasculitis of small and medium-sized blood vessels characterized by fibrinoid necrosis. The use of prednisolone resulted in clinical improvement initially, but recurrence occurred during tapering. She showed marked improvement with additional high dose methyl prednisolone monthly.     

View-invariant representations of familiar objects by neurons in the inferior temporal visual cortex

A view-invariant representation of objects in the brain would have many computational advantages. Here we describe a population of single neurons in the temporal visual cortex (IT) that have view-invariant representations of familiar objects. Ten real plastic objects were placed in the monkeys' home cages for a period of time before neurophysiological experiments in which neuronal responses were measured to four views of each object. The macaques performed a visual fixation task, and had never been trained in object discrimination. The majority of the visual neurons recorded were responsive to some views of some objects and/or to the control stimuli, as would be expected from previous studies. However, a small subset of these neurons were responsive to all views of one or more of the objects, providing evidence that these neurons were coding for objects, rather than simply for individual views or visual features within the image. This result was confirmed by information theoretic analyses, which showed that the neurons provided information about which object was being seen, independently of the view. The coding scheme was shown to be sparse distributed, with relatively independent information being provided by the different neurons. Hypotheses about how these view-invariant cells are formed are described.