Using Computer Programs In Higher Education - Good Practice In Mathematics

We report on our experience in teaching (applied) mathematics both for mathematicians and non-mathematicians using computer algebra systems and spreadsheet calculation programs. Advantages and disadvantages are discussed and some recommendations are given

ArgR is an essential local transcriptional regulator of the arcABC-operon in Streptococcus suis and crucial for biological fitness in acidic environment

Streptococcus suis is one of the most important pathogens in pigs and can also cause severe infections in humans. Despite its clinical relevance very little is known about the factors contributing to its virulence. Recently, we identified a new putative virulence factor in Streptococcus suis, the arginine deiminase system (ADS), an arginine catabolic enzyme system encoded by the arcABC-operon, which enables Streptococcus suis to survive in acidic environment. In this study, we focused on ArgR, an ADS associated regulator belonging to the ArgR/AhrC arginine repressor family. Using an argR knock-out strain we could show that ArgR is essential for arcABC-operon expression and necessary for the biological fitness of Streptococcus suis. By cDNA expression microarray analyses and quantitative real time RT-PCR we found that the arcABC-operon is the only gene cluster regulated by ArgR, which is in contrast to many other bacteria. Reporter gene analysis with gfp under the control of the arcABC promoter demonstrated that ArgR is able to activate the arcABC promoter. Electrophoretic mobility shift assays with fragments of the arcABC promoter and recombinant ArgR, and chromatin immunoprecipitation with antibodies directed against ArgR revealed that ArgR interacts with the arcABC promoter in vitro and in vivo by binding to a region from -147 to 72 bp upstream of the transcriptional start point. Overall our results show that in Streptococcus suis ArgR is an essential, system specific transcriptional regulator of the ADS directly interacting with the arcABC promoter in vivo

Role of glucose and CcpA in capsule expression and virulence of Streptococcus suis

Streptococcus suis is one of the most important pathogens in pigs and is also an emerging zoonotic agent. After crossing the epithelial barrier, S. suis causes bacteraemia, resulting in meningitis, endocarditis and bronchopneumonia. Since the host environment seems to be an important regulatory component for virulence, we related expression of virulence determinants of S. suis to glucose availability during growth and to the sugar metabolism regulator catabolite control protein A (CcpA). We found that expression of the virulence-associated genes arcB, representing arcABC operon expression, cps2A, representing capsular locus expression, as well as sly, ofs, sao and epf, differed significantly between exponential and early stationary growth of a highly virulent serotype 2 strain. Deletion of ccpA altered the expression of the surface-associated virulence factors arcB, sao and eno, as well as the two currently proven virulence factors in pigs, ofs and cps2A, in early exponential growth. Global expression analysis using a cDNA expression array revealed 259 differentially expressed genes in early exponential growth, of which 141 were more highly expressed in the CcpA mutant strain 10¿ccpA and 118 were expressed to a lower extent. Interestingly, among the latter genes, 18 could be related to capsule and cell wall synthesis. Correspondingly, electron microscopy characterization of strain 10¿ccpA revealed a markedly reduced thickness of the capsule. This phenotype correlated with enhanced binding to porcine plasma proteins and a reduced resistance to killing by porcine neutrophils. Taken together, our data demonstrate that CcpA has a significant effect on the capsule synthesis and virulence properties of S. suis

Computations of a film cooled turbine rotor blade with non-uniform inlet temperature distribution using a three-dimensional viscous procedure

A numerical investigation of film cooling on a turbine rotor blade has been carried out. The computations were performed with a 3D-Navier-Stokes code utilizing an unstructured solution adaptive grid methodology. The code uses a low Reynolds number k-epsilon model for prescribing the Reynolds stresses. The results show that there is a significant interaction between the coolant flow and the secondary flow near the hub and the tip of the turbine blade. It was observed that, by blowing on the pressure side of the blade some of the cooling air was transported through the tip gap of the blade to the suction side of the blade where the coolant flow interacts with the secondary flow field

The Arteriovenous Loop: Engineering of Axially Vascularized Tissue

Background: Most of the current treatment options for large-scale tissue defects represent a serious burden for the patients, are often not satisfying, and can be associated with significant side effects. Although major achievements have already been made in the field of tissue engineering, the clinical translation in case of extensive tissue defects is only in its early stages. The main challenge and reason for the failure of most tissue engineering approaches is the missing vascularization within large-scale transplants. Summary: The arteriovenous (AV) loop model is an in vivo tissue engineering strategy for generating axially vascularized tissues using the own body as a bioreactor. A superficial artery and vein are anastomosed to create an AV loop. This AV loop is placed into an implantation chamber for prevascularization of the chamber inside, e.g., a scaffold, cells, and growth factors. Subsequently, the generated tissue can be transplanted with its vascular axis into the defect site and anastomosed to the local vasculature. Since the blood supply of the growing tissue is based on the AV loop, it will be immediately perfused with blood in the recipient site leading to optimal healing conditions even in the case of poorly vascularized defects. Using this tissue engineering approach, a multitude of different axially vascularized tissues could be generated, such as bone, skeletal or heart muscle, or lymphatic tissues. Upscaling from the small animal AV loop model into a preclinical large animal model could pave the way for the first successful attempt in clinical application. Key Messages: The AV loop model is a powerful tool for the generation of different axially vascularized replacement tissues. Due to minimal donor site morbidity and the possibility to generate patient-specific tissues variable in type and size, this in vivo tissue engineering approach can be considered as a promising alternative therapy to current treatment options of large-scale defects

Evidence that BDNF regulates heart rate by a mechanism involving increased brainstem parasympathetic neuron excitability

Autonomic control of heart rate is mediated by cardioinhibitory parasympathetic cholinergic neurons located in the brainstem and stimulatory sympathetic noradrenergic neurons. During embryonic development the survival and cholinergic phenotype of brainstem autonomic neurons is promoted by brain-derived neurotrophic factor (BDNF). We now provide evidence that BDNF regulates heart rate by a mechanism involving increased brainstem cardioinhibitory parasympathetic activity. Mice with a BDNF haploinsufficiency exhibit elevated resting heart rate, and infusion of BDNF intracerebroventricularly reduces heart rate in both wild-type and BDNF+/− mice. The atropine-induced elevation of heart rate is diminished in BDNF+/− mice and is restored by BDNF infusion, whereas the atenolol-induced decrease in heart rate is unaffected by BDNF levels, suggesting that BDNF signaling enhances parasympathetic tone which is diminished with BDNF haploinsufficiency. Whole-cell recordings from pre-motor cholinergic cardioinhibitory vagal neurons in the nucleus ambiguus indicate that BDNF haploinsufficiency reduces cardioinhibitory vagal neuron activity by increased inhibitory GABAergic and diminished excitatory glutamatergic neurotransmission to these neurons. Our findings reveal a previously unknown role for BDNF in the control of heart rate by a mechanism involving increased activation of brainstem cholinergic parasympathetic neurons Mice with reduced BDNF levels exhibit elevated heart rate, and infusion of BDNF into the brain normalizes heart rate by a mechanism involving increased brainstem cardioinhibitory parasympathetic activity. Recordings from pre-motor cholinergic cardioinhibitory vagal neurons (CVNs) in the nucleus ambiguus indicate that BDNF increases CVN activity by increasing excitatory glutamatergic and decreasing inhibitory GABAergic neurotransmission to these neurons. Perhaps factors that increase parasympathetic tone (e.g., exercise) reduce resting heart rate, in part, by a BDNF-mediated mechanism

Bares y cantinas gay en Guadalajara. La vida nocturna como espacios de organización y resistencia

Esta investigación trata de las identidades dentro del movimiento lésbico–gay– bisexual–transgénero–transexual-queer-intersexual-asexual (LGBT+) en el Área Metropolitana de Guadalajara (AMG), y la manera en la que los miembros de este movimiento utilizan los establecimientos nocturnos de entretenimiento como trincheras y espacios de encuentro, los cuales ofrecen diversas posibilidades de formas alternativas de expresión social y cultural en un contexto mayoritariamente conservador. Para adentrarnos un poco más en la comunidad LGBT+ nos pareció pertinente rescatar algunos de los conceptos menos conocidos por la sociedad mexicana. Uno de ellos es el transgénero que incluye a las personas que tienen una identidad de género que difiere del sexo que les fue asignado al nacer (MFMER, 2020). Por otro lado, el término queer es usado por algunos jóvenes como una identidad para no identificarse como hombre o mujer, lo que también se conoce como géneros binarios (APA, 2017). Otro término que quisimos explicar es el intersexual, el cual se refiere a las variaciones corporales de las características sexuales (genitales, gónadas, niveles hormonales, cromosomas) que se originan durante el desarrollo de la diferenciación sexual en la etapa embrionaria (Pérez, 2020). Y finalmente la asexualidad, que es una orientación sexual en la cual una persona experimenta poca o ninguna atracción sexual hacia otra persona o ningún deseo de contacto sexual (Kaur, 2019).ITESO, A.C

Bares y cantinas gay en Guadalajara. La vida nocturna como espacios de organización y resistencia

Esta investigación trata de las identidades dentro del movimiento lésbico–gay– bisexual–transgénero–transexual-queer-intersexual-asexual (LGBT+) en el Área Metropolitana de Guadalajara (AMG), y la manera en la que los miembros de este movimiento utilizan los establecimientos nocturnos de entretenimiento como trincheras y espacios de encuentro, los cuales ofrecen diversas posibilidades de formas alternativas de expresión social y cultural en un contexto mayoritariamente conservador.ITESO, A.C