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Hirsch A.M.,University of California at Los Angeles | Valdes M.,Escuela Nacional de Ciencias Biologicas
Soil Biology and Biochemistry | Year: 2010

Micromonospora species have long been recognized as important sources of antibiotics and also for their unusual spores. However, their involvement in plant-microbe associations is poorly understood although several studies demonstrate that Micromonospora species function in biocontrol, plant growth promotion, root ecology, and in the breakdown of plant cell wall material. Our knowledge of this generally understudied group of actinomycetes has been greatly advanced by the increasing number of reports of their associations with plants, by the deployment of DNA cloning and molecular systematics techniques, and by the recent application of whole genome sequencing. Efforts to annotate the genomes of several Micromonospora species are underway. This information will greatly augment our knowledge of these versatile microorganisms. © 2009 Elsevier Ltd. All rights reserved.


Sanchez-Huerta K.,Escuela Nacional de Ciencias Biologicas | Sanchez-Huerta K.,National Institute of Pediatrics | Pacheco-Rosado J.,Escuela Nacional de Ciencias Biologicas | Gilbert M.E.,U.S. Environmental Protection Agency
Journal of Neuroendocrinology | Year: 2015

Thyroid hormone (TH) is essential for a number of physiological processes and is particularly critical during nervous system development. The hippocampus is strongly implicated in cognition and is sensitive to developmental hypothyroidism. The impact of TH insufficiency in the foetus and neonate on hippocampal synaptic function has been fairly well characterised. Although adult onset hypothyroidism has also been associated with impairments in cognitive function, studies of hippocampal synaptic function with late onset hypothyroidism have yielded inconsistent results. In the present study, we report hypothyroidism induced by the synthesis inhibitor propylthiouracil (10 p.p.m., 0.001%, minimum of 4 weeks), resulted in marginal alterations in excitatory postsynaptic potential (EPSP) and population spike (PS) amplitude in the dentate gyrus measured in vivo. No effects were seen in tests of short-term plasticity, and a minor enhancement of long-term potentiation of the EPSP slope was observed. The most robust synaptic alteration evident in hypothyroid animals was an increase in synaptic response latency, which was paralleled by a failure to maintain normal body temperature under anaesthesia, despite warming on a heating pad. Latency shifts could be reversed in hypothyroid animals by increasing the external heat source and, conversely, synaptic delays could be induced in control animals by removing the heat source, with a consequent drop in body and brain temperature. Thermoregulation is TH- dependent, and anaesthesia necessary for surgical procedures posed a thermoregulatory challenge that was differentially met in control and hypothyroid animals. Minor increases in field potential EPSP slope, decreases in PS amplitudes and increased latencies are consistent with previous reports of hypothermia in naive control rats. We conclude that failures in thyroid-dependent temperature regulation rather than direct action of TH in synaptic physiology are responsible for the observed effects. These findings stand in contrast to the synaptic impairments observed in adult offspring following developmental TH insufficiency, and emphasise the need to control for the potential unintended consequences of hypothermia in the interpretation of hypothyroid-induced changes in physiological systems, most notably synaptic transmission. © 2014 British Society for Neuroendocrinology.


Flores-Morales A.,Technological Institute of Tlaxcala Plateau | Jimenez-Estrada M.,National Autonomous University of Mexico | Mora-Escobedo R.,Escuela Nacional de Ciencias Biologicas
Carbohydrate Polymers | Year: 2012

The nixtamalization, production and storage of tortillas in refrigeration cause several changes on the starch structure, resulting in an increased crystallinity and therefore a higher content of resistant starch. The IR analysis for resistant starch (RS) showed a band at 1047 cm-1 associated to the retrogradation process; this band was due to the weakening of the intermolecular H-bonds. These associated together to form ordered regions. The Raman analysis shows a characteristic band at 856 cm-1 corresponding to C-C skeletal modes of glucose of α-1,4 glycosidic linkage starches, and a band at 480 cm-1 attributed to skeletal vibrations of the pyranose ring in the glucose unit of starches. These changes may be related to the polymerization degree of the starch molecules, as well as to the retrogradation of amylose and amylopectin. The spectrum of 13C CP-MAS/NMR for RS3 supports the results obtained by IR and Raman. Lipidic and proteic groups were observed which may be in the form of complexes with amylose. One can proclaim that the existence of the salt form is induced and stabilized by the interactions dominating the V amylose structure in the solid state. © 2011 Elsevier Ltd. All Rights Reserved.


Mendez-Samperio P.,Escuela Nacional de Ciencias Biologicas
Journal of the Egyptian Society of Parasitology | Year: 2013

Trypanosomes cause a variety of tropical diseases that affect the livelihood of individuals worldwide. The currently used pharmaceutical treatments rely on chemotherapy. However, many of these drugs are very expensive, and highly toxic. In addition, parasite resistance to several of the therapeutic drugs used is increasing. Therefore, there is a growing need for new control measures for many of these diseases. One new approach is the use of antimicrobial peptides (AMPs) to disease control, since these peptides can be used as potential anti-parasite effector molecules. This review summarizes and discusses the parasiticidal properties of AMPs for treating trypanosome infections, highlighting their mechanisms of action and current status in development.


Mendez-Samperio P.,Escuela Nacional de Ciencias Biologicas
Korean Journal of Parasitology | Year: 2012

Helminthic infections affict over 1.5 billion people worldwide, while Mycobacterium tuberculosis infects one third of the world's population, resulting in 2 million deaths per year. Although tuberculosis and helminthic infections coexist in many parts of the world, and it has been demonstrated that the T-helper 2 and T-regulatory cell responses elicited by hel- minths can affect the ability of the host to control mycobacterial infection, it is still unclear whether helminth infections in fact affect tuberculosis disease. In this review article, current progress in the knowledge about the immunomodulation in- duced by helminths to diminish the protective immune responses to bacille Calmette-Guerin vaccination is reviewed, and the knowledge about the types of immune responses modulated by helminths and the consequences for tuberculosis are summarized. In addition, recent data supporting the signifcant reduction of both M. tuberculosis antigen-specifc Toll-like receptor (TLR) 2 and TLR9 expression, and pro-infammatory cytokine responses to TLR2 and TLR9 ligands in individuals with M. tuberculosis and helminth co-infection were discussed. This examination will allow to improve understanding of the immune responses to mycobacterial infection and also be of great relevance in combating human tuberculosis. © 2012, Korean Society for Parasitology and Tropical Medicine.


Villanueva I.,Escuela Nacional de Ciencias Biologicas | Alva-Sanchez C.,Escuela Nacional de Ciencias Biologicas | Pacheco-Rosado J.,Escuela Nacional de Ciencias Biologicas
Oxidative Medicine and Cellular Longevity | Year: 2013

Reactive oxygen species (ROS) are oxidizing agents amply implicated in tissue damage. ROS production is inevitably linked to ATP synthesis in most cells, and the rate of production is related to the rate of cell respiration. Multiple antioxidant mechanisms limit ROS dispersion and interaction with cell components, but, when the balance between ROS production and scavenging is lost, oxidative damage develops. Many traits of aging are related to oxidative damage by ROS, including neurodegenerative diseases. Thyroid hormones (THs) are a major factor controlling metabolic and respiratory rates in virtually all cell types in mammals. The general metabolic effect of THs is a relative acceleration of the basal metabolism that includes an increase of the rate of both catabolic and anabolic reactions. THs are related to oxidative stress not only by their stimulation of metabolism but also by their effects on antioxidant mechanisms. Thyroid dysfunction increases with age, so changes in THs levels in the elderly could be a factor affecting the development of neurodegenerative diseases. However, the relationship is not always clear. In this review, we analyze the participation of thyroid hormones on ROS production and oxidative stress, and the way the changes in thyroid status in aging are involved in neurodegenerative diseases. © 2013 I. Villanueva et al.


Mendez-Samperio P.,Escuela Nacional de Ciencias Biologicas
Infectious Diseases | Year: 2016

Helminth parasites are a major cause of global infectious diseases, affecting nearly one quarter of the world's population. The common feature of helminth infections is to skew the immune system towards a T-helper 2 (Th2) response that helps to control disease. Dendritic cells (DCs), which are professional antigen-presenting cells, play a critical role for Th2 skewing against helminth parasites. However, the molecular mechanisms by which helminth antigens activate DCs for Th2 polarization have not yet been clearly defined. This review provides a focused update on the major role of DCs for inducing and/or enhancing Th2 immune responses in helminthic infection and will discuss the main signalling-dependent and independent mechanisms by which helminth antigens activate DCs for Th2 skewing. © 2016 Society for Scandinavian Journal of Infectious Diseases


Mendez-Samperio P.,Escuela Nacional de Ciencias Biologicas
Peptides | Year: 2010

Antimicrobial peptides are predominantly small cationic polypeptides that are classified together on the basis of these molecules to directly kill or inhibit the growth of microorganisms including mycobacteria, and to activate mechanisms of cellular and adaptive immunity. Various families of antimicrobial peptides have been identified, including the cathelicidins. The cathelicidin family is characterised by a conserved N-terminal cathelin domain and a variable C-terminal antimicrobial domain that can be released from the precursor protein after cleavage by proteinases. LL-37 is the C-terminal part of the only human cathelicidin identified to date called human cationic antimicrobial protein (hCAP18), which is mainly expressed by neutrophils and epithelial cells. The cathelicidin hCAP18/LL-37 is a multifunctional molecule that may mediate various host responses, including bactericidal action, chemotaxis, epithelial cell activation, angiogenesis, epithelial wound repair and activation of chemokine secretion. The antimicrobial peptide LL-37 is produced from human cells during infection of mycobacteria and exerts a microbicidal effect. The discussion will (1) describe recent work on the antimicrobial and immunomodulatory functions of the cathelicidin hCAP18/LL-37, (2) highlight the effectiveness of the cathelicidin hCAP18/LL-37 as a potent component in antimycobacterial immune responses and (3) summarise current progress in the understanding of the therapeutic application of hCAP18/LL-37 and its derivates antimicrobial peptides in mycobacterial infection. © 2010 Elsevier Inc. All rights reserved.


Meza-Marquez O.G.,Escuela Nacional de Ciencias Biologicas | Gallardo-Velazquez T.,Escuela Nacional de Ciencias Biologicas | Osorio-Revilla G.,Escuela Nacional de Ciencias Biologicas
Meat Science | Year: 2010

Chemometric MID-FTIR methods were developed to detect and quantify the adulteration of mince meat with horse meat, fat beef trimmings, and textured soy protein. Also, a SIMCA (Soft Independent Modeling Class Analogy) method was developed to discriminate between adulterated and unadulterated samples. Pure mince meat and adulterants (horse meat, fat beef trimmings and textured soy protein) were characterized based upon their protein, fat, water and ash content. In order to build the calibration models for each adulterant, mixtures of mince meat and adulterant were prepared in the range 2-90% (w/w). Chemometric analyses were obtained for each adulterant using multivariate analysis. A Partial Least Square (PLS) algorithm was tested to model each system (mince meat+adulterant) and the chemical composition of the mixture. The results showed that the infrared spectra of the samples were sensitive to their chemical composition. Good correlations between absorbance in the MID-FTIR and the percentage of adulteration were obtained in the region 1800-900cm-1. Values of R2 greater than 0.99, standard errors of calibration (SEC) in the range to 0.0001-1.278 and standard errors of prediction (SEP estimated) between 0.001 and 1.391 for the adulterant and chemical parameters were obtained. The SIMCA model showed 100% classification of adulterated meat samples from unadulterated ones. Chemometric MID-FTIR models represent an attractive option for meat quality screening without sample pretreatments which can identify the adulterant and quantify the percentage of adulteration and the chemical composition of the sample. © 2010 Elsevier Ltd.


Mendez-Samperio P.,Escuela Nacional de Ciencias Biologicas
International Journal of Infectious Diseases | Year: 2010

Interleukin (IL)-12 is a multifunctional cytokine acting as a key regulator of cell-mediated immune responses through the differentiation of naïve CD4+ T cells into type 1 helper T cells (Th1) producing interferon-γ. As our knowledge of IL-12 family members is rapidly growing, it will be important to specify their involvement in the regulation of mycobacterial infection. This article is a review of the current knowledge regarding the functions of the IL-12 family cytokines in the immune host defense system against mycobacteria. Specifically, this review aims to describe recent scientific evidence concerning the protective role of some members of the IL-12 family cytokines for the control of mycobacterial infection, as well as to summarize knowledge of the potential use of the IL-12 family members as potent adjuvants in the prevention and treatment of mycobacterial infectious diseases. In addition, recent data supporting the importance of the IL-12 family members in mycobacterial diseases in relation to Th17 function are discussed. This examination will help to improve our understanding of the immune response to mycobacterial infection and also improve vaccine design and immunotherapeutic intervention against tuberculosis. © 2009 International Society for Infectious Diseases.

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