Analysis of the Bactericidal Activity of Naive Rabbit Serum against Staphylococcus aureus

Staphylococcus aureus is a commensal bacterium that can also act as an opportunistic pathogen, causing a wide range of diseases in humans and in economically important livestock such as cows and rabbits. S. aureus quickly develops resistance against antibiotics and also evades the immune system of the host. As current treatments are difficult and expensive, new antibiotics, vaccines and the use of elements of the immune system are currently being studied as novel control approaches. A novel bactericidal mechanism able to kill S. aureus present in naive rabbit serum (NRS) was previously discovered in our laboratory. The bactericidal activity of the NRS had been characterized and the importance of the wall teichoic acids (WTA) on the bacteria for susceptibility was identified previously, but the mechanism involved in the bacterial killing remained unknown. In this study the role of the WTA as the bacterial receptor that interacts with the ‘killing factor’ present in the NRS was established. The importance of WTA modifications were also determined in pathogen resistance to the NRS killing mechanism. Use of bacterial cell wall material as an affinity matrix led to the identification of secreted phospholipase A2 (sPLA2) as a potential part of the bactericidal mechanism. The use of a range of inhibitors and specific antibodies confirmed sPLA2 as part of the killing mechanism. Purified sPLA2 from a number of species was tested and cobra sPLA2 (cvPLA2) was able to kill S. aureus in buffer but led to bacterial growth when added to NRS. This suggests that cvPLA2 interacts with rabbit serum components and this results in inactivation of both cvPLA2 and the bactericidal activity of the NRS. Annexin A1, a known regulator of PLA2, was identified through mass spectrometry as a serum protein also bound to the cell wall affinity matrix. This protein enhanced the bactericidal activity of cvPLA2 against S. aureus by direct protein-protein interaction. A model of NRS staphylococcal activity is presented

INVESTIGATING MEDIATION WHEN COUNTERFACTUALS ARE NOT METAPHYSICAL: DOES SUNLIGHT UVB EXPOSURE MEDIATE THE EFFECT OF EYEGLASSES ON CATARACTS?

We investigate the degree to which a reduction in ocular sunlight ultra-violet B (UVB) exposure mediates a relationship between wearing eyeglasses and a decreased risk of cataracts. An estimand is proposed in which causal effects are estimated locally within strata based on potential UVB exposure without glasses and the degree to which glasses use reduces UVB exposure. We take advantage of the structure of the data in which the counterfactual UVB exposures if the participants in the study who wore glasses had not worn glasses are considered observable

FACTORES QUE INFLUYEN EN LA AUTOMEDICACION DE LOS ESTUDIANTES DE LA FACULTAD DE CIENCIAS DE LA SALUD DE LA UNIVERSIDAD ANDINA NÉSTOR CÁCERES VELÁSQUEZ JULIACA

El estudio busco como objetivo  determinar  y analizar los factores que influyen en la autome- dicacion  de los estudiantes  de la Facultad  de Ciencias  de la Salud de la Universidad  Andina Néstor  Cáceres  Velásquez  Juliaca.  Metodóloga:    Se aplicó un cuestionario  estructurado  de 14 items recolectando   la información  de las dos variables.  Se realizó  un estudio  descriptivo transversal  explicativo,   aplicándose   una encuesta  a 335 alumnos  de la facultad  de ciencias de la salud de la UANCV. La prueba  de la hipótesis  se realizó mediante  el uso del estadístico de relación  Chi cuadrado.  Resultados:   Al estudiar  la frecuencia  de la automedicación   de 335 estudiantes  se obtuvo  los siguientes  resultados:  el 63% (210) de estudiantes  se automedica  a veces,  el 21% (70) de estudiantes  que se automedica  frecuentemente,   y un  16% (55) de los estudiantes  no se automedican.   Se logro demostrar  que los factores:  personales,  culturales, económicos  y sociales  tienen  influencia  sobre  la frecuencia  de automedicaci6n   de los estudiantes  de la facultad  de ciencias  de la salud de la UANCV  durante  los meses  de Agosto  a Noviembre  del 2011. En conclusión,   la automedicacion   es una práctica  común  de estudiantes universitarios;   puede  ocasionar  consecuencias   severas y a veces  fatales.

Simplified structural design and LCA of reinforced concrete beams strengthening techniques

This work provides the Life Cycle Assessment (LCA) of four commonly used strengthening techniques of re- inforced concrete beams. Firstly, it provides a simplified methodology to size the strengthening, overcoming the need of extensive knowledge in structures. Secondly, it provides the application of LCA to the selected techni- ques. The method improves the applicability of LCA to buildings, analyzes the environmental differences be- tween techniques, and reveals the importance of the anchoring method as well as the enormous benefit in reusing building structures. Results obtained for conventional beams are displayed in tables ready to use in LCAs with broader boundary systems

High-performance optical fiber humidity sensor based on lossy mode resonance using a nanostructured polyethylenimine and graphene oxide coating

In this study, a rapid optical fiber sensor for humidity with high sensitivity and wide detection range has been constructed, based on lossy mode resonance (LMR). A thin film made of alternating polyethylenimine (PEI) and graphene oxide (GO) layers was selected as sensitive coating. It was deposited on a SnO2-sputtered fiber core in a dip-assisted layer-by-layer assembly. The structure and surface chemistry of the raw materials were investigated by means of Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Key properties such as sensitivity, linearity, hysteresis, stability and response and recovery times were characterized. The sensor exhibited excellent sensitivity, especially at high relative humidity (RH) levels, and short reaction and retrieval periods. This research provides a viable and practical way to fabricate high performance humidity optical fiber sensors with GO-based nanostructured coatings

Analysis of LEDGF/p75 expression regulation

Background To replicate, retroviruses must insert DNA copies of their RNA genomes into the host genome. This integration process is catalyzed by the viral integrase protein. The site of viral integration has been shown to be non-random and retrovirus-specific. LEDGF/p75, a splice variant encoded by PSIP1 gene and described as a general transcription coactivator, was identified as a tethering factor binding both to chromatin and to lentiviral integrases, thereby affecting integration efficiency as well as integration site selection. LEDGF/p75 is still a poorly characterized protein, and its cellular endogenous function has yet to be fully determined. In order to start unveiling the roles of LEDGF/p75 in the cell, we started to investigate the mechanisms involved in the regulation of LEDGF/p75. Materials and methods To identify PSIP1 minimal promoter and associated regulatory elements, we cloned a region starting 5 kb upstream the transcription start site (TSS, +1 reference position) to the ATG start codon (+816), as well as systematic truncations, in a plasmid containing the firefly luciferase reporter gene. These constructs were co-transfected into HEK293 cells with a plasmid encoding the Renilla luciferase under the pTK promoter as an internal control for transfection efficiency. Both luciferase activities were assessed by luminescence as an indicator of promoter activity. Results Luciferase assays identified regions -76 to +1 and +1 to +94 as two independent minimal promoters showing respectively a 3.7x and 2.3x increase in luciferase activity. These two independent minimal promoters worked synergistically increasing luciferase activity up to 16.3x as compared to background. Moreover, we identified five regulatory blocks which modulated luciferase activity depending on the DNA region tested, three enhancers (- 2007 to -1159, -284 to -171 and +94 to +644) and two silencers (-171 to -76 and +796 to +816). However, the silencing effect of the region -171 to -76 is dependent on the presence of the +94 to +644 region, ruling out the enhancer activity of the latter. Computational analysis of PSIP1 promoter revealed the absence of TATA box and initiator (INR) sequences, classifying this promoter as nonconventional. TATA-less and INR-less promoters are characterized by multiple Sp1 binding sites, involved in the recruitment of the RNA pol II complex. Consistent with this, PSIP1 promoter contains multiple putative Sp1 binding sequences in regions -76 to +1 and +1 to +94

Longitudinal Analysis of Antibody Responses to Trachoma Antigens Before and After Mass Drug Administration.

Blinding trachoma, caused by the bacteria Chlamydia trachomatis, is a neglected tropical disease targeted for elimination by 2020. A major component of the elimination strategy is mass drug administration (MDA) with azithromycin. Currently, program decisions are made based on clinical signs of ocular infection, but we have been investigating the use of antibody responses for post-MDA surveillance. In a previous study, IgG responses were detected in children lacking clinical evidence of trachoma, suggesting that IgG responses represented historical infection. To explore the utility of serology for program evaluation, we compared IgG and IgA responses to trachoma antigens and examined changes in IgG and IgA post-drug treatment. Dried blood spots and ocular swabs were collected with parental consent from 264 1-6 year olds in a single village of Kongwa District, central Tanzania. Each child also received an ocular exam for detection of clinical signs of trachoma. MDA was given, and six months later an additional blood spot was taken from these same children. Ocular swabs were analyzed for C. trachomatis DNA and antibody responses for IgA and total IgG were measured in dried bloods spots. Baseline antibody responses showed an increase in antibody levels with age. By age 6, the percentage positive for IgG (96.0%) was much higher than for IgA (74.2%). Antibody responses to trachoma antigens declined significantly six months after drug treatment for most age groups. The percentage decrease in IgA response was much greater than for IgG. However, no instances of seroreversion were observed. Data presented here suggest that focusing on concordant antibody responses in children will provide the best serological surveillance strategy for evaluation of trachoma control programs

Magnetómetro Kerr: análisis de ruido e instrumentación

El magnetómetro Kerr ha mostrado ser una de las herramientas más ágiles y eficaces para el estudio y la caracterización de materiales magnéticos (películas delgadas). En este artículo se describen los tipos de ruido inherentes a l montaje de ésta herramienta y la forma como pueden ser minimizados: así mismo, se realiza un análisis descriptivo de diferentes tipos de montajes prácticos. El criterio de diseño empleado para la instrumentación de este montaje se basa en las técnicas de eliminación de ruido utilizadas. Como aspecto central se presenta la reducción de ruido por wave/els. Para poder llegar a proponer una nueva alternativa de instrumentación y control más versátil y económica. Por último, se realiza un análisis comparativo en relación con otras técnicas de caracterización de materia les magnéticos