Enhancing the Formation of the New Trigonal Polymorph in Isotactic Propene-1-Pentene Copolymers: Determination of the X-ray Crystallinity

Ernesto Pérez,María L. Cerrada,Rosario Benavente,José M. Gómez-Elvira 한국고분자학회 2011 Macromolecular Research Vol.19 No.11

A metallocene copolymer of isotactic propene and 1-pentene was subjected to different crystallization conditions with 13 mol% of 1-pentene counits, aiming to enhance the formation of a new trigonal modification of iPP. Since it was not possible to obtain a diffractogram for the amorphous sample of cPPe13 at room temperature,the X-ray crystallinity was determined using the profile of the molten polymer, extrapolated to room temperature according to the resulting temperature coefficients. The X-ray diffraction results indicate a very interesting polymorphism in this copolymer; when crystallized from solution, amazingly high degrees of crystallinity - as high as 65%- are obtained, and this value is similar to those obtained for the iPP homopolymer. Further, the enthalpy of melting for a 100% crystalline sample of the trigonal modification was estimated from those crystallinities and the actual enthalpies of melting.

Diet-induced obese mice exhibit altered immune responses to early Salmonella Typhimurium oral infection

Ricardo Ernesto Ramírez-Orozco,Elena Franco Robles,Victoriano Pérez Vázquez,Joel Ramírez Emiliano,Marco Antonio Hernández Luna,Sergio López Briones 한국미생물학회 2018 The journal of microbiology Vol.56 No.9

Obesity is a chronic disease associated with different metabolic diseases as well as alterations in immune cell function. It is characterized by a chronic systemic low grade inflammation. There are several studies demonstrating the influence of obesity on the impaired immune response to infection. However, it is not completely clear whether the obese environment influences the development or maintenance of the immune response against infections. The aim of this study was to determine how obesity induced by a high-fat diet affects the immune response to an early oral Salmonella infection. Four groups of mice were kept in separate cages. Two of these designated as controls, fed with a normal diet; whereas other two groups were fed with a high fat diet for 10 weeks. Some mice were used for Salmonella oral infection. After 7 days of oral infection with S. Thypimurium the proportions of spleen cell subsets expressing activation markers in normal diet and HFD obese mice were stained with monoclonal antibodies and analyzed by flow cytometry. Also, mRNA levels of different cytokines were quantified by RT-PCR. It was found that obesity affects the function of the immune system against an early oral Salmonella infection, decreasing NK cells, altering the expression of activation molecules as well as cytokines mRNA levels. Interestingly, the expression some activation molecules on T lymphocytes was reestablished after Salmonella infection, but not the CD25 expression. Immune alterations could lead to immunosuppression or increased susceptibility to infections in HFD obese mice.

Characterization and Properties of Ethylene-Propylene Copolymers Synthesized with Homogeneous and Supported Metallocene Catalyst in the Whole Range of Compositions

Javier Arranz-Andrés,Inmaculada Suárez,Rosario Benavente,Ernesto Pérez 한국고분자학회 2011 Macromolecular Research Vol.19 No.4

Two series of ethylene-propylene copolymers were synthesized in the whole composition range using a metallocene catalyst, one in the homogeneous phase (H copolymers), and the other with the catalyst supported in silica (S copolymers). Some differences were found between the two groups. Therefore, the amount of ethylene needed to obtain a certain proportion of the γ form is lower in the H than in S series. Moreover, the composition to obtain the pseudo hexagonal form is also different for the two groups. On the other hand, degree of crystallinity, crystal sizes and microhardness values display a similar variations with the comonomer content of the two series. Consequently, from a macroscopic point of view, materials with similar macroscopic mechanical properties can be produced using both supported and homogeneous metallocene catalysts despite the structural differences.

A Functional and Phylogenetic Comparison of Quorum Sensing Related Genes in Brucella melitensis 16M

Aniel Jessica Leticia Brambila-Tapia,Ernesto Pérez-Rueda 한국미생물학회 2014 The journal of microbiology Vol.52 No.8

A quorum-sensing (QS) system is involved in Brucella melitensissurvival inside the host cell. Two transcriptional regulatorsidentified in B. melitensis, BlxR and VjbR, regulatethe expression of virB, an operon required for bacterial intracellularpersistence. In this work, 628 genes affected byVjbR and 124 by BlxR were analyzed to gain insights intotheir functional and taxonomical distributions among theBacteria and Archaea cellular domains. In this regard, theCluster of Orthologous Groups (COG) genes and orthologousgenes in 789 nonredundant bacterial and archaeal genomeswere obtained and compared against a group ofrandomly selected genes. From these analyses, we found 71coaffected genes between VjbR and BlxR. In the COG comparison,VjbR activated genes associated with intracellulartrafficking, secretion and vesicular transport and defensemechanisms, while BlxR affected genes related to energyproduction and conversion (with an equal effect) and translation,ribosomal structure and biogenesis, posttranslationalmodifications and carbohydrate and amino acid metabolism(with a negative effect). When the taxonomical distributionof orthologous genes was evaluated, the VjbR- and BlxRrelatedgenes presented more orthologous genes in Crenarchaeota(Archaea), Firmicutes, and Tenericutes and fewergenes in Proteobacteria than expected by chance. These findingssuggest that QS system exert a fine-tuning modulationof gene expression, by which VjbR activates genes relatedto infection persistence and defense, while BlxR repressesgeneral bacterial metabolism for intracellular adaptations. Finally, these affected genes present a degree of presenceamong Bacteria and Archaea genomes that is different fromthat expected by chance.

SLAMF7 is critical for phagocytosis of haematopoietic tumour cells via Mac-1 integrin

Chen, Jun,Zhong, Ming-Chao,Guo, Huaijian,Davidson, Dominique,Mishel, Sabrin,Lu, Yan,Rhee, Inmoo,Pé,rez-Quintero, Luis-Alberto,Zhang, Shaohua,Cruz-Munoz, Mario-Ernesto,Wu, Ning,Vinh, Donald C.,Si Nature Publishing Group 2017 Nature Vol. No.

<P>Cancer cells elude anti-tumour immunity through multiple mechanisms, including upregulated expression of ligands for inhibitory immune checkpoint receptors(1,2). Phagocytosis by macrophages plays a critical role in cancer control(3-6). Therapeutic blockade of signal regulatory protein (SIRP)-alpha, an inhibitory receptor on macrophages, or of its ligand CD47 expressed on tumour cells, improves tumour cell elimination in vitro and in vivo(7-10), suggesting that blockade of the SIRP alpha-CD47 checkpoint could be useful in treating human cancer(11-14). However, the prophagocytic receptor(s) responsible for tumour cell phagocytosis is(are) largely unknown. Here we find that macrophages are much more efficient at phagocytosis of haematopoietic tumour cells, compared with non-haematopoietic tumour cells, in response to SIRP alpha-CD47 blockade. Using a mouse lacking the signalling lymphocytic activation molecule (SLAM) family of homotypic haematopoietic cell-specific receptors, we determined that phagocytosis of haematopoietic tumour cells during SIRP alpha-CD47 blockade was strictly dependent on SLAM family receptors in vitro and in vivo. In both mouse and human cells, this function required a single SLAM family member, SLAMF7 (also known as CRACC, CS1, CD319), expressed on macrophages and tumour cell targets. In contrast to most SLAM receptor functions(15-17), SLAMF7-mediated phagocytosis was independent of signalling lymphocyte activation molecule-associated protein (SAP) adaptors. Instead, it depended on the ability of SLAMF7 to interact with integrin Mac-1 (refs 18-20) and utilize signals involving immunoreceptor tyrosine-based activation motifs(21,22). These findings elucidate the mechanism by which macrophages engulf and destroy haematopoietic tumour cells. They also reveal a novel SAP adaptor-independent function for a SLAM receptor. Lastly, they suggest that patients with tumours expressing SLAMF7 are more likely to respond to SIRP alpha-CD47 blockade therapy.</P>