Epitaxial Growth of a Thin Layer of Putative Cancer Cells under Limited Resources and in the Presence of an Alkylating Agent.

The dynamics of the Eden cluster in a 32x32 lattice is implemented using a stochastic model. A single-type of cells solid tumor is assumed. Duplication is probabilistic, and occurs when there is room in the immediate surroundings of a cell, otherwise the cell is inhibited by contact. The growth is epitaxial, the shape of the cluster is disk-like; the ratio between the numbers of perimeter cells; and bulk cells decreases as the cluster grows. Percolation is flagged by an inflection in the rate of growth. We assume that the inflection point actually flags a shortage of nutrients, thereafter the rate of growth decreases to zero. Cancer cells in culture, when deprived of nutrients, actually exhibit a similar behavior. Under the logistic hypothesis, the lattice contains nutrients to sustain the growth up to 1024 cells. The model is expanded to include a drug that pollutes the environment. The drug is an alkylating agent that hinders duplication, eventually causing the death of the cell. The logistic equation accounts for drug consumption. The probability of duplication with the drug decreases as the drug is consumed, eventually leading to relapse. Relapses and survival times are investigated as a function of the dose injected.

A new cynodont from the Upper Triassic Los Colorados Formation (Argentina, South America) reveals a novel paleobiogeographic context for mammalian ancestors.

Probainognathia is a derived lineage of cynodonts which encompass Mammalia as their crown-group. The rich record of probainognathians from the Carnian of Argentina contrasts with their Norian representation, with only one named species. Here we describe a new probainognathian, Tessellatia bonapartei gen. et sp. nov., from the Norian Los Colorados Formation of the Ischigualasto-Villa Unión Basin of Argentina. The new taxon, represented by a partial cranium with associated lower jaws, was analyzed through neutron and X-rays micro-tomography (µCT). The high-resolution neutron µCT data allowed the identification of a unique character combination, including features inaccessible through traditional techniques. We constructed the largest phylogenetic data matrix of non-mammalian cynodonts. The new species and its sister taxon, the Brazilian Therioherpeton cargnini, are recovered as probainognathians, closely related to Mammaliamorpha. We conducted the first quantitative paleobiogeographic analysis of non-mammalian cynodonts, focusing in probainognathians. The results indicate that Probainognathia and Mammaliamorpha originated in southwestern Gondwana (in the Brazilian Paraná Basin), which was an important center of diversification during the Triassic. Finally, the Chinese Lufeng Basin is identified as the ancestral area of Mammaliaformes. These new findings, besides adding to the knowledge of the poorly represented Norian cynodonts from the Los Colorados Formation, are significant to improve our understanding of probainognathian diversity, evolution, and paleobiogeographic history.

The ACROSS study: Long-term efficacy of fingolimod in patients with relapsing-remitting multiple sclerosis.

BACKGROUND: In chronic diseases such as multiple sclerosis requiring lifelong treatment, studies on long-term outcomes are important. OBJECTIVE: To assess disability and magnetic resonance imaging-related outcomes in relapsing multiple sclerosis patients from a Phase 2 study of fingolimod 10 or more years after randomization and to compare outcomes in patients who had a higher fingolimod exposure versus those with a lower fingolimod exposure. METHODS: ACROSS was a cross-sectional follow-up study of patients originally enrolled in a Phase 2 fingolimod proof-of-concept study (NCT00333138). Disability and magnetic resonance imaging-related outcomes were assessed in patients grouped according to fingolimod treatment duration, based on an arbitrary cut-off: ≥8 years (high exposure) and <8 years (low exposure). RESULTS: Overall, 175/281 (62%) patients participated in ACROSS; 104 (59%) of these were classified "high exposure." At 10 years, patients in the high-exposure group had smaller increases in Expanded Disability Status Scale (+0.55 vs. +1.21), and lower frequencies of disability progression (34.7% vs. 56.1%), wheelchair use (4.8% vs. 16.9%), or transition to secondary progressive multiple sclerosis (9.6% vs. 22.5%) than those in the low-exposure group. The high-exposure patients also had less progression in most magnetic resonance imaging-related outcomes. CONCLUSION: After 10 years of fingolimod treatment, disability progression was lower in the high-exposure group than in the low-exposure group.

Cognitive aspects of chaos in random networks.

A special case of deterministic chaos that is independent of the architecture of the connections has been observed in a computer model of a purely excitatory neuronal network. Chaos onsets when the level of connectivity is critically low. The results indicate a typical period-doubling route to chaos as the connectivity decreases. A cognitive interpretation of such type of chaos, based on information theory and phase-transitions, is proposed.

Cyclooxygenase-2/microsomal prostaglandin E synthase-1 complex in the preoptic-anterior hypothalamus of the mouse: involvement through fever to intravenous lipopolysaccharide.

AIM: Prostaglandin E2 (PGE2) is now well established as a central effector of pyrogen fever. However, questions remain on the source, local vs. blood-borne, of the compound for the early phase of the typically biphasic fever (Phases 1 and 2) to i.v. pyrogens. To verify the role of centrally formed PGE2, we examined the cyclooxygenase (COX)/prostaglandin E synthase (PGES) complex through fever to i.v. lipopolysaccharide (LPS). METHODS: Experiments were carried out in the conscious mouse and LPS effect was ascertained on all steps of expression - gene, protein, catalytic activity - of individual enzymes. The analysis was limited to the preoptic-anterior hypothalamus (AH/POA). RESULTS: We found upregulation of the COX2 transcript together with an upward trend for the mPGES1 transcript during Phase 1. Coincidentally, there was a progressive increase in COX2 and mPGES1 protein expression through Phases 1 and 2. Catalytic activity for COX1 and COX2 combined was instead enhanced only in Phase 2, while mPGES1 activity remained steady at an intrinsically high level. Other COX and PGES enzymes were not modified through either Phase, and COX2/mPGES1 changes subsided with fever defervescence. CONCLUSION: The findings confirm a key function of COX2 and mPGES1 for the synthesis of pyrogenic PGE2 and, at the same time, document their early response to LPS. We conclude that locally formed PGE2 in AH/POA is qualified for a role in the initiation of fever.

In vitro neutron irradiation of glioma and endothelial cultured cells.

To fully develop its potential boron neutron capture therapy (BNCT) requires the combination of a suitable thermal/epithermal neutron flux together with a selective intake of (10)B-boron nuclei in the target tissue. The latter condition is the most critical to be realized as none of the boron carriers used for experimental or clinical purposes proved at the moment an optimal selectivity for cancer cells compared to normal cells. In addition to complex physical factors, the assessment of the intracellular concentration of boron represent a crucial parameter to predict the dose delivered to the cancer cells during the treatment. Nowadays the dosimetry calculation and then the prediction of the treatment effectiveness are made using Monte Carlo simulations, but some of the model assumption are still uncertain: the radiobiological dose efficacy and the probability of tumour cell survival are crucial parameters that needs a more reliable experimental approach. The aim of this work was to evaluate the differential ability of two cell lines to selectively concentrate the boron-10 administered as di-hydroxyboryl-phenylalanine (BPA)-fructose adduct, and the effect of the differential boron intake on the damage produced by the irradiation with thermal neutrons; the two cell lines were selected to be representative one of normal tissues involved in the active/passive transport of boron carriers, and one of the tumour. Recent in vitro studies demonstrated how BPA is taken by proliferating cells, however the mechanism of BPA uptake and the parameters driving the kinetics of influx and the elimination of BPA are still not clarified. In these preliminary studies we analysed the survival of F98 and human umbilical vein endothelial cells (HUVEC) cells line after irradiation, using different thermal fluencies at the same level of density population and boron concentration in the growing medium prior the irradiation. This is first study performed on endothelium model obtained by a primary human cell line (HUVEC). The perspective application of this work is to develop a model able to foresee the effects produced by different combination of boron influx with a thermal neutron fluencies, applying a standardized radiobiological methodology, and in particular to continue the investigation of the radiobiological effects on the endothelium model as the main tissue involved in the transport of boronated molecules.

The amelioration of olfactory acuity upon sexual maturation might affect food preferences.

Upon sexual maturation, olfactory acuity in women ameliorates and starts oscillating across the cycle. During ovulation, mean olfactory threshold is 30 times lower than during bleeding. Interestingly, menstruated women undergo maleodorant trimethylaminuria. We argued that olfactory amelioration during ovulation might concur to a mating strategy, whereas olfactory impairment during bleeding might protect women against self-refusal. Testosterone and its 17ß-estradiol derivative might be responsible for the synchronization of these menstrual events. Furthermore, we posed the question whether olfactory detection amelioration upon sexual maturation might provoke a change in food preferences, for instance a reduction in fish consumption. A preliminary survey in Italy provided encouraging results: 15-44 year-old women have lower fish consumption than 3-14 year-old girls. Surprisingly, men exhibited the same behaviour, so new olfactory tests as well as testosterone measurements are under way.

Histology far away from Flatland: 3D roller-coasting into grade-dependent angiogenetic patterns in oligodendrogliomas.

Angiogenesis plays a key role in tumour progression, and undergoes structural changes associated to tumour biology itself. Although vessel density can be easily evaluated in brain tumours using a traditional immuno-histochemical approach, other parameters of conceptual/biological interest, such as the complex patterns of vascular growth, cannot be fully understood using a traditional bi-dimensional evaluation. We use here surgical specimens derived from oligodendrogliomas as a model for a novel elucidative 3D reconstruction of the grade-dependent vascular arborisation in brain tumours.

Dynamics of cell membrane passive depolarization: a phase portrait.

Does a persistent blockage of the ionic pumps bring cell membrane voltage to zero? This apparently trivial question of basic cellular Biology stirred up an intriguing problem of nonlinear dynamics. A 3-ion model based on continuity and charge conservation proves that membrane voltage actually sets on a negative value, meaning that chemical equilibrium is never reached, rather an inversion of the Na+ concentration gradient occurs, usually hours after the blockage of the pumps. Experimental tests carried out with PC12 cells incubated with Oubaine for a period of 24 hours show an increase of cytosolic Na+ of about 266 mM/l with respect to a control sample. The result is compatible with an inversion of the Na+ gradient, which eventually brings the membrane voltage to a negative value. Reactivation of the Na+-K+ pumps even after a prolonged period of blockage (late repolarization) should lead to repolarization and revival of the cell. In the 3D space of the ionic concentrations, the dynamics of passive depolarization reveals an intriguing topology, all trajectories being stacked in parallel planes, each set ending to a unique fixed point via an infinitely dense set of lines. The dynamics of repolarization has a different phase portrait, especially in the case of late repolarization. Thus, a sequence of depolarization- repolarization cycles may result in a path wandering in the phase space, or in a closed loop, depending on the timing of the sequence.

Regulation of the sea urchin early H2A histone gene expression depends on the modulator element and on sequences located near the 3' end.

Transcription of the sea urchin early histone genes occurs transiently during early cleavage, reaching the maximum at the morula stage and declining to an undetectable level at the gastrula stage. To identify the regulatory elements responsible for the timing and the levels of transcription of the H2A gene, we used promoter binding studies in nuclear extracts and microinjection of a CAT transgene driven by the early H2A promoter. We found that morula and gastrula nuclear proteins produced indistinguishable DNase I footprint patterns on the H2A promoter. Two sites of interactions, centred on the modulator/enhancer and on the CCAAT box respectively, were detected. Deletion of the modulator or coinjection of an excess of modulator sequences severely affected the expression of two transgenes driven by the enhancer-less and modulator-containing H2A promoter. Finally, a DNA fragment containing 3' coding and post-H2A spacer sequences, where upon silencing three micrococcal nuclease hypersensitive sites were previously mapped, specifically repressed at the gastrula stage the expression of the transgene driven by the H2A promoter. These results indicate that the modulator is essential for the expression of early H2A gene and that sequences for downregulation are localized near the 3' end of the H2A gene.

Modulator factor-binding sequence of the sea urchin early histone H2A promoter acts as an enhancer element.

The sea urchin early H2A histone gene, like the other four members of the repeating units, is transiently expressed during very early development. To investigate the mechanisms underlying the faithful expression of the early H2A gene, we focused our attention on the modulator element. We showed by DNase I cleavage protection patterns that the modulator includes the upstream sequence element 1 (USE1) and mapped at nucleotides -137 to -108 in the early H2A gene promoter. Functional tests conducted by microinjection into sea urchin embryos then showed that the modulator element binds the transcriptional factor called modulator-binding factor 1 (MBF-1). We found in fact that coinjection of an excess of the MBF-1-binding site, either as the modulator or as the USE1, efficiently impaired the activity of the H2A promoter. An unexpected finding was the expression of the reporter gene from the early H2A promoter at the gastrula stage of embryonic development, when the early histone genes are transcriptionally silent. In addition, we also found that the modulator element was active at the gastrula stage. The potential enhancer activity of the modulator was tested by microinjecting several constructs containing single or multiple copies of the modulator element placed 5' or 3' to a thymidine kinase gene (tk) promoter in both sea urchin embryos and Xenopus laevis oocytes and determining the expression of a reporter chloramphenicol acetyltransferase gene under the control of the linked tk promoter. We found that an oligonucleotide bearing the MBF-1-binding site activates the expression of the reporter gene independently of the position and orientation. We conclude that the modulator binds the MBF-1 activator and that it is a transcriptional enhancer of the early H2A histone gene.