Papers by Juliana Gonçalves
Planta Medica, 2010
Nuclear factor-kappaB is a key transcription factor activated by pro-inflammatory signals, like i... more Nuclear factor-kappaB is a key transcription factor activated by pro-inflammatory signals, like interleukin-1beta (IL-1), being required for the expression of many inflammatory and catabolic mediators, such as nitric oxide (NO), that play an important role in arthritic diseases. This work aimed at screening and identifying natural inhibitors of IL-induced NF-kappaB activation and NO production in human articular chondrocytes. Five essential oils obtained from four plants of the Iberian flora, Mentha x piperita L. (Lamiaceae), Origanum virens L. (Lamiaceae), Lavandula luiseri L. (Lamiaceae), and Juniperus oxycedrus L. subsp. oxycedrus (Cupressaceae), were screened for their ability to prevent IL-1-induced NO production. The oil showing higher inhibitory activity was fractionated, concentrated, analyzed for composition elucidation and prepared for further assays. For this purpose, the human chondrocytic cell line C-28/I2 was used to evaluate NF-kappaB activation by determining the cytoplasmic levels of the total and phosphorylated forms of the inhibitory protein, I kappaB-alpha, and the NF-kappaB-DNA binding activity. The essential oil from the leaves of J. oxycedrus in a concentration of 0.02 % (v/v) achieved the greatest inhibition (80 +/- 8%) of IL-1-induced NO production. Chemical analysis showed that this essential oil is predominantly composed of monoterpene hydrocabons, being alpha-pinene [2,6,6-trimethyl-bicyclo(3.1.1)hept-3-ene] the major constituent (76 %). Similarly to the effect of the whole oil, a fraction containing 93% alpha-pinene reduced significantly IL-1-induced I kappaB-alpha degradation. Moreover, alpha-pinene also decreased I kappaB-alpha phosphorylation, NF-kappaB-DNA binding activity, and NO production. Another fraction containing oxygenated mono- and sesquiterpenes was nearly as effective as alpha-pinene. The ability of the alpha-pinene-containing fraction to reduce IL-1-induced NF-kappaB activation and NO production warrants further studies to demonstrate the usefulness of alpha-pinene in the treatment of arthritic diseases and other conditions in which NF-kappaB and NO play pathological roles.
Arthritis Research & Therapy, 2009
Introduction Disorders that affect glucose metabolism, namely diabetes mellitus (DM), may favor t... more Introduction Disorders that affect glucose metabolism, namely diabetes mellitus (DM), may favor the development and/or progression of osteoarthritis (OA). Thus far, little is known regarding the ability of chondrocytes to adjust to variations in the extracellular glucose concentration, resulting from hypoglycemia and hyperglycemia episodes, and so, to avoid deleterious effects resulting from deprivation or intracellular accumulation of glucose. The aim of this study was to compare the ability of normal and OA chondrocytes to regulate their glucose transport capacity in conditions of insufficient or excessive extracellular glucose and to identify the mechanisms involved and eventual deleterious consequences, namely the production of reactive oxygen species (ROS). Methods Chondrocytes, isolated from normal and OA human cartilage, were maintained in high-density monolayer cultures, in media without or with 10 or 30 mM glucose. Glucose transport was measured as the uptake of 2-deoxy-D-glucose (2-DG). Glucose transporter-1 (GLUT-1) mRNA and protein content were evaluated by real-time RT-PCR and western blot, respectively. ROS production was measured with 2',7'-dichlorodihydrofluorescein diacetate. Results Basal and IL-1β-induced 2-DG uptake, including the affinity (1.066 ± 0.284 and 1.49 ± 0.59 mM) and maximal velocity (0.27 ± 0.08 and 0.33 ± 0.08 nmol/μg protein/hour), and GLUT-1 content were identical in normal and OA chondrocytes. Glucose deprivation increased 2-DG uptake and GLUT-1 protein both in normal and OA chondrocytes. Exposure to high glucose (30 mM) for 18 or 48 hours decreased those parameters in normal but not in OA chondrocytes. GLUT-1 mRNA levels were unaffected by high glucose, either in normal or OA chondrocytes. The high glucose-induced reduction in GLUT-1 protein in normal chondrocytes was reversed by treatment with a lysosome inhibitor. High glucose induced ROS production, which lasted significantly longer in OA than in normal chondrocytes. Conclusions Normal human chondrocytes adjust to variations in the extracellular glucose concentration by modulating GLUT-1 synthesis and degradation which involves the lysosome pathway. Although capable of adjusting to glucose deprivation, OA chondrocytes exposed to high glucose were unable downregulate GLUT-1, accumulating more glucose and producing more ROS. Impaired GLUT-1 downregulation may constitute an important pathogenic mechanism by which conditions characterized by hyperglycemia, like DM, can promote degenerative changes in chondrocytes that can facilitate the progression of OA.
De acordo com a mecânica clássica de Hamilton, um sistema de partículas interagentes tem energia ... more De acordo com a mecânica clássica de Hamilton, um sistema de partículas interagentes tem energia total :
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Papers by Juliana Gonçalves