ABSTRACT
Mannheimia haemolytica leukotoxin (LKT) is a known cause of bovine respiratory disease (BRD) which results in severe economic losses in the cattle industry (up to USD 1 billion per year in the USA). Vaccines based on LKT offer the most promising measure to contain BRD outbreaks and are already commercially available. However, insufficient LKT yields, predominantly reflecting a lack of knowledge about the LKT expression process, remain a significant engineering problem and further bioprocess optimization is required to increase process efficiency. Most previous investigations have focused on LKT activity and cell growth, but neither of these parameters defines reliable criteria for the improvement of LKT yields. In this article, we review the most important process conditions and operational parameters (temperature, pH, substrate concentration, dissolved oxygen level, medium composition and the presence of metabolites) from a bioprocess engineering perspective, in order to maximize LKT yields.
Subject(s)
Animals , Cattle , Bacterial Toxins/biosynthesis , Mannheimia haemolytica/metabolism , Bovine Respiratory Disease Complex/microbiology , Exotoxins/biosynthesis , Temperature , Trace Elements , Carbon/metabolism , Mannheimia haemolytica/pathogenicity , Amino Acids/metabolism , Hydrogen-Ion Concentration , KinetinABSTRACT
A healthy gut consists of commensal flora,epithelial layer and gut-associated lymphoid tissue (GALT). GALT is hyporesponsive to commensal flora and dietary antigens,but can recognize and at-tack pathogens. Accumulating evidence suggests that dendritic cells (DCs) play a crucial role in managing this paradoxical situation and maintaining the complex homeostasis in gut. Influenced by intestinal epithelial cells (IECs) and commensal flora,intestinal DCs possess unique properties that enable them to regulate T-helper 2 (Th2) cells,regulatory T cells (Tregs) and immunoglobulin A (IgA)-producing cells in a steady state. During infection,intestinal DCs are involved in the induction of effector lymphocytes, although they are also responsible for initiating pathogenic responses in inflammatory bowel diseases (IBDs). Therefore, intestinal DCs are associated with not only the maintenance of immune tolerance to commensal flora,but also the induction of protective immune responses against pathogens. This review outlines the roles of commensal flora, epithelial layer, and GALT in mucosal homeostasis and inflammation and summarizes recent progress in DCs-mediated intestinal immune homeostasis.
ABSTRACT
Los síntomas compatibles con vaginitis y vaginosis, son la causa más frecuente de consulta al ginecólogo. La descarga vaginal abundante y el prurito, constituyen la primera sospecha de estas patologías. Sin embargo, debemos tener presente que el aumento significativo de lactobacilos, conocido como lactobacilosis, puede expresarse también con los mismos síntomas y signos de una vulvovaginitis micótica. Si esta condición se mantiene en el tiempo, puede provocar un grado de acidez anormal en la vagina, y puede llevar a una lisis de las células epiteliales que se conoce como vaginosis citolítica. Este diagnóstico, aunque es poco frecuente, debemos sospecharlo especialmente, en aquellas mujeres que relatan tener múltiples consultas por candidiasis vaginal, con escasa o nula respuesta frente a la terapia antimicótica.
The symptoms consistent with vaginitis and vaginosis are the most common cause of the visit to the gynecologist. Heavy vaginal discharge and pruritus are the first suspicion of this pathology. However, the significant increase in lactobacilli, known as lactobacilosis can be expressed also with the same symptoms and signs of a fungal vulvovaginitis. If this condition is maintained overtime, can cause abnormal acidity in the vagina, and may lead to epithelial cell lysis, which is known as cytolytic vaginosis. This diagnosis, although rare, should be suspected especially in women who reported having multiple consultations for vaginal candidiasis, with little or no response to antifungal therapy.