Gene transfer into vascular cells

AbstractThe goal of gene therapy is to introduce foreign deoxyribonucleic acid (DNA) into somatic cells to correct or prevent disorders caused by the malfunction of genes within a diseased individual. Overexpression of recombinant genes at specific sites within the vasculature can provide insights into vascular biology and potential treatments for various cardiovascular disorders such as restenosis. Methods for the introduction of foreign DNA into endothelial and vascular smooth muscle cells have been developed recently. These include the genetic modification of endothelium in vitro and implantation in vivo on arterial segments, direct infection of the arterial wall in vivo with a replication-defective retroviral vector expressing a recombinant gene and direct transfer of genes into vascular cells in vivo with use of liposomes. Although still in its formative stages, gene transfer into the vasculature holds promise as a potential treatment for vascular diseases, including atherosclerosis and restenosis. This approach may also provide insight into the role of specific gene products in the development of pathologic lesions

Nucleic Acid Determinants of Cytosine Deamination by Aid/Apobec Enzymes in Immunity and Epigenetics

A multitude of functions have evolved around cytosine within DNA, endowing the base with physiological significance beyond simple information storage. This versatility arises from enzymes that chemically modify cytosine to expand the potential of the genome. Cytosine can be methylated, oxidized, and deaminated to modulate transcription and immunologic diversity. At the crossroads of these modifications sit the AID/APOBEC family deaminases, which accomplish diverse functions ranging from antibody diversification and innate immunity to mRNA editing. In addition, novel roles have been proposed in oncogenesis and DNA demethylation. Behind these established and emerging physiologic activities remain important questions about the substrate specificity of these deaminases, reflecting a broader need to elucidate how AID/APOBEC enzymes engage their substrates for deamination. The work here addresses this larger question by focusing on the molecular basis of two important aspects of AID/APOBEC specificity: selectivity for DNA over RNA, and biochemical plausibility of deamination-coupled demethylation. To address these questions, we have synthesized chimeric nucleic acid substrates and characterized their reactivity with AID and the rest of the APOBEC family. With regards to nucleic acid selectivity, modifications to the 2\u27-position of the target nucleotide sugar significantly alter AID\u27s reactivity. Strikingly, within a substrate that is otherwise DNA, a single RNA-like 2\u27-hydroxyl substitution at the target cytosine is sufficient to compromise deamination. Alternatively, modifications that favor a DNA-like conformation (or sugar pucker) are compatible with deamination. Inversely, with unreactive 2\u27-fluoro-RNA substrates, AID\u27s deaminase activity was rescued by introducing a trinucleotide DNA patch spanning the target cytosine and two upstream nucleotides. With regards to demethylation, AID has substantially reduced activity on 5-methylcytosine relative to cytosine, its canonical substrate, and no detectable deamination of 5-hydroxymethylcytosine. This finding is explained by the reactivity of a series of modified substrates, where steric bulk at the 5-position was increasingly detrimental to deamination. We found that these nucleic acid determinants, localized to the nucleotide base and sugar, are conserved across the entire AID/APOBEC family. Taken together, we consolidate these findings into a unifying, mechanistic model for substrate engagement that clarifies the established and proposed functions of the AID/APOBEC family

Myelination in the auditory brainstem

The evolution of myelin was a major key event in vertebrates which aimed to enhance conduction velocity of electrical impulses in axons. Distinct myelination patterns along axons can shape the speed and timing of action potentials. Exact arrival time of inputs at target neurons are crucial for proper neural circuit function. Two key determinants for tuning conduction velocity of myelinated axons are the length of individual myelin sheaths together with the axon diameter. However, it remains unanswered who determines specific myelination patterns along axons – the oligodendrocyte or the axon? And further, when and how do structural parameters of myelinated axons develop in neural circuits in general, in terms of their functionally relevant myelination patterns, axonal morphology and nodes of Ranvier? A system with highest temporal demands is the mammalian sound localization system. Globular bushy cell (GBC) axons involved in circuits processing sound location information are some of the fastest and most precise conducting axons in the mammalian central nervous system. In the Mongolian gerbil (Meriones unguiculatus) GBCs that are tuned to low sound frequencies transmit sound signals to the binaural comparator neurons in the medial superior olive (MSO) where the arrival time of sound at the two ears (interaural time differences; ITDs) is computed. These differences can be as low as only a few microseconds and thus, computation of ITDs relies on explicitly fast and highly precise axons. To cope with the need for exact input timing, low-frequency GBC axons exhibit specific structural adaptations to adjust conduction velocity. Their exceptional thick axons combined with comparably short internodes result in unusual low ratios of internode length to axon diameter (L/d ratios) which in turn increase the conduction velocity along their axons. To gain insight into when and how the specific myelin sheath lengths, axon diameter and thus L/d ratios are established, we characterized the developmental time course of these structural parameters at timepoints before and after the onset of hearing. Our findings show the internode length is set prior to a significant axon diameter increase. While the internode length is established already two days before hearing onset, which is at P12, the axon diameter only increases five days after hearing onset, and thereby decreasing its L/d ratio. This strongly suggests that, at least in GBCs, the axon itself is the key determinant in ensuring that the required conduction velocity is met by adjusting its diameter retrospectively. Together with the length of myelin sheaths and the axon diameter, nodes of Ranvier are critical determinants of action potential speed and timing of and therefore the development of all these structures must be tightly regulated. By assessing the development of nodes of Ranvier we found that axon and node morphology by and large mature synchronously. Early nodal clusters appear already when myelination of GBC axons is initiated at P6/P7 and these premature clusters subsequently progress until reaching maturity during the 4th postnatal week. Interestingly, we were able to show that node maturation depends on the location along the axon with nodes closer to the cell body develop earlier compared to nodes close to the synaptic terminal

La pedagogía de las ciberprotestas: Un análisis psicosocial

El presenta trabajo es el primer acercamiento a un proceso de reelaboración crítica al acontecer sociopolítico cotidiano a partir de un estiramiento teórico del concepto de pedagogía. El énfasis de esta reelaboración es la explicación de lo social y lo político en los acontecimientos más importantes que emanan de las redes sociales en Internet, circunscritos a objetos de análisis tangibles como las ciberprotestas más significativas en el contexto mexicano. Se trata de un análisis psicosocial instalado en el cruce socio-histórico entre las nociones de programación pedagógica-ciberprotestas, configurando un modelado social en la acción colectiva en México y en general en el mundo, desde la primavera árabe, el #15-M, el #OccupyWallStreet, #TodosSomosAyotzinapa pasando por #YoSoy132, hasta el #MeTo

Social networks, popularity and social influence. The case of the cyber protests against the Telecommunications law in Mexico, 2014

El artículo discute dos hipótesis sobre la influencia social que se ejerce en las redes sociales de Internet. La discusión se centra en el poder de la popularidad y la posición de los activistas políticos a la hora de protestar en un medio cibernético como twitter. El caso analizado es el de la ciberprotesta contra la ley de telecomunicaciones en México en 2014. Entre las conclusiones del estudio se destaca el efecto de la popularidad en las redes sociales como estrategia para la promoción de los conflictos que detonan el contagio de ideas y tendencias en la red. Una tesis muy similar a la propuesta por Manuel Castells sobre los programadores de la red, actores sociales que gracias a su posición y jerarquía tienen una serie de recursos y ventajas.The article discusses two hypotheses about the social influence exerted on social networking sites. The discussion focuses on the power of the popularity and position of political activists in protesting in a cyber environment as twitter. The case analyzed is the cyberprotest against telecommunications law in Mexico in 2014. The conclusion of the study the effects is the effect of popularity in social networks as a strategy for promoting the conflicts that trigger the spread of ideas and trends highlights on the network. A thesis very similar to that proposed by Manuel Castells on network programmers, social actors thanks to its position and hierarchy have a number of resources and advantages

Redes sociales y efectos políticos: Reflexiones sobre el impacto de twitter México

El artículo expone un marco explicativo sobre el impacto político de las redes sociales. El marco expuesto parte del análisis de algunos a acontecimientos políticos surgidos a raíz de acontecimientos en redes sociales como twitter. Al final se valora el impacto de estos hechos en la vida pública del país, llegando a una importante disyuntiva de si ¿las redes contaminan a la sociedad o son un espejo de la misma?The paper presents a framework explaining the political impact of social networks. The exposed part of the analysis of some political developments arising out of events in social networks like twitter. At the end we have evaluated the impact of these events in the country's public life, leading to a major dilemma of whether networks "pollute the society or are a mirror of it

Deterioration the Properties of Contaminated Natural Rubber with Some Species of Microorganisms.

The rubber materials are very important in our lives because of its properties and suitability for many applications, and it is a direct target of numerous microorganisms such as bacteria and fungi and there effect on rubber, especially natural rubber poly (cis-1,4-isoprene), as it contains organic material and water, it dealt with the current study. The effect of contaminate (fungi) during bad conditions of transportation and Storage, genus Aspergillus Niger was isolated from contaminated samples for both types (SMR20, SVR20) and study the physical and mechanical properties, which included tensile strength and elongation at break, hardness, abrasion and extraction in addition to the study influenced main constituent of natural rubber growth of fungus using the technique of infrared spectrum. The results showed a negative influence on the physical and mechanical properties for the growth of fungus, in addition to the disappearance of some bands of natural rubber such as   (C-H) and (C-N) bands. Keywords: Deterioration, Natural Rubber, SMR20, SVR20, poly (cis-1,4-isoprene), microorganisms, fungi

A Review Study of Mechanical Fatigue Testing Methods for Small-Scale Metal Materials

A review on the mechanical characterization of materials at small- scale is presented. The concentration is on the different micro- and nano-scale testing techniques, classify, summarize, and compare all of these techniques that are currently available. The variety of materials investigated by the scientific and industrial communities and the mechanical quantities identified by such methodologies. Finally, the perspectives of studies on fatigue of the small scale metal materials are offered. Keywords:  Fatigue crack ; small-scale; nano-scale;  MEMS; cyclic load; thin film