GD1a modulates GM-CSF-induced cell proliferation

AbstractGangliosides have been extensively described to be involved in the proliferation and differentiation of various cell types, such including hematopoietic cells. Our previous studies on murine models of stroma-mediated myelopoiesis have shown that gangliosides are required for optimal capacity of stromal cells to support proliferation of myeloid precursor cells, being shed to the supernatant and selectively incorporated into myeloid cell membranes. Here we describe the effect of gangliosides on the specific granulocyte–macrophage colony-stimulating factor (GM-CSF)-induced proliferation. For that, we used the monocytic FDC-P1 cell line, which is dependent upon GM-CSF for survival and proliferation. Cells were cultured in the presence of GM-CSF and exogenous gangliosides (GM3, GD1a or GM1) or in the absence of endogenous ganglioside synthesis by the use of a ceramide-synthase inhibitor, d-PDMP. We observed that exogenous addition of GD1a enhanced the GM-CSF-induced proliferation of the FDC-P1 cells. Also, we detected an increase in the expression of the α isoform of the GM-CSF receptor (GMRα) as well as of the transcription factor C/EBPα. On the contrary, inhibition of glucosylceramide synthesis was accompanied by a decrease in cell proliferation, which was restored upon the addition of exogenous GD1a. We also show a co-localization of GD1a and GMR by immunocytochemistry. Taken together, our results suggest for the first time that ganglioside GD1a play a role on the modulation of GM-CSF-mediated proliferative response, which might be of great interest not only in hematopoiesis, but also in other immunological processes, Alzheimer disease, alveolar proteinosis and wherever GM-CSF exerts its effects

Virtual Determination of Blood Urea Obtained from Rats Fed Normo or Hypoprotein Diet

The urea cycle represents a metabolic pathway of great relevance to the nitrogen homeostasis of mammals. In addition, the metabolites involved in their reactions play a key role in the pathogenesis of some diseases and clinical situations. Therefore, it is essential to health professionals understand this metabolic pathway. Objectives: This learning object aims to illustrate the biochemical reactions of urea cycle, contextualizing clinically the main metabolites involved, as well as to present an interactive virtual urea determination in blood serum of rats fed with normo and hypoprotein diet. Materials and Methods: This object was developed with HTML5 and contains: a) hypertexts, images explaining the urea cycle, its importance and related pathologies; b) animations of the intracellular chemical reactions involved in the route of urea synthesis; c) animations simulating laboratory activities. Results and Discussion: The animated simulation of a standard urea curve, followed by virtual determination of urea in blood serum samples were developed, associated with some interactive questions to measure the user's learning. The object was assessed by undergraduate students of Basic Biochemistry. The navigation features, design and interactivity have been evaluated as excellent by about 85% of them. Conclusion: This learning object can be considered an adequate teaching resource as well as an innovative support in the construction of theoretical and practical knowledge of Biochemistry for students of health area

Virtual Practice of Biochemistry: Ascendant Chromatography on Paper of Amino acids.

Chromatography is a method used for analyses of mixture components based on different criteria: adsorbility, solubility, molecular mass, ionic charge and affinity. It is an important subject of Biochemistry. This work reports the development and the validation of a software that simulated a laboratory activity named Ascendant Chromatography on Paper of Aminoacids. The organization and the multimedia material collection were done during the 2008/2 semester. The most representative images were inserted into the learning object. The tool used for the software development was Adobe® Flash® CS3. The first application of this object was in Biochemistry I (Pharmacy-UFRGS) in 2009/1. Using this experience, a new version was developed which was tested by the students of the same subject in 2009/2. After a 50-minute class (theoretical-practical), the students of both semesters were divided in two groups. Group I answered a questionnaire about chromatography basic concepts and after used the software. Group II was submitted to an inverse protocol. The groups also evaluated the technical aspects of the software animation/simulation and the activity carried out. Associating both applications results (2009/1 and 2009/2), the present learning object can be valid as a support for practical teaching of basic biochemistry

Evaluation of Serum Lactate Dehydrogenase Activity in a Virtual Environment

Introduction: Lactate dehydrogenase is a citosolic enzyme involved in reversible transformation of pyruvate to lactate. It participates in anaerobic glycolysis of skeletal muscle and red blood cells, in liver gluconeogenesis and in aerobic metabolism of heart muscle. The determination of its activity helps in the diagnosis of various diseases, because it is increased in serum of patients suffering from myocardial infarction, acute hepatitis, muscular dystrophy and cancer. This paper presents a learning object, mediated by computer, which contains the simulation of the laboratory determination serum lactate dehydrogenase activity measured by the spectrophotometric method, based in the decrease of absorbance at 340 nm. Materials and Methods: Initially, pictures and videos were obtained recording the procedure of the methodology. The most representative images were selected, edited and inserted into an animation developed with the aid of the tool Adobe ® Flash ® CS3. The validation of the object was performed by the students of Biochemistry I (Pharmacy-UFRGS) from the second semester of 2009 and both of 2010. Results and Discussion: The analysis of students' answers revealed that 80% attributed the excellence of the navigation program, the display format and to aid in learning. Conclusion: Therefore, this software can be considered an adequate teaching resource as well as an innovative support in the construction of theoretical and practical knowledge of Biochemistry. Available at: http://www6.ufrgs.br/gcoeb/LD