Graziela Saraiva Reis

Oxidative-Stress Biomarkers in Patients with Pulmonary Hypertension

This controlled, prospective, nonrandomized clinical investigation has as its chief strength the fact that it was done in humans with active disease and apparently on fairly modest therapeutic regimens. The aim was to present the results of oxidative-stress biomarkers in humans suffering from pulmonary artery hypertension (PAH). Inflammation and oxidative stress are essential in PAH with increased lipid peroxidation and reduced antioxidant defenses. Twenty-four adult patients of both sexes, with a mean age of 21 years, were subdivided into 2 groups: a control group of 12 healthy, nonsmoking volunteers and a PAH group (PAHG) of 12 volunteers with PAH receiving outpatient treatment. Oxidative stress was evaluated by plasma activity of reduced glutathione (GSH); lipid peroxidation was expressed by malondialdehyde (MDA) and lipid hydroperoxide (ferrous oxidation of xylenol orange [FOX] assay); vitamin E was measured by high-performance liquid chromatography and tumor necrosis factor-α (TNF-α) by enzyme-linked immunosorbent assay. Statistical analyses showed significant differences for (1) the TNF-α measure, with highest values in PAHG patients; (2) the plasma GSH, with lowest values in PAHG patients; (3) vitamin E, with the lowest concentrations in PAHG patients; (4) MDA measure, with highest values in PAHG patients; and (5) the lipid hydroperoxide FOX measure, with highest values in PAHG patients. In conclusion, inflammation and oxidative stress are present in patients with PAH, as confirmed by increased lipid peroxidation, reduced GSH, and low concentrations of vitamin E.

Forças mecânicas e veias safenas humanas: implicação na revascularização do miocárdio

Vascular endothelial cells are exposed to a variety of in vivo mechanical forces, specifically, shear stress for the blood flow, tensile stress from the compliance of the vessel wall and the hydrostatic pressure from containment of blood within inside the vasculature. Many authors studied hemodynamic, functional and morphological human saphenous veins alterations caused by these different forces with conflictant results. This review text was motivated with the specific aim of analyze literature data and some experimental data carried out in our laboratory. The adopted review subjects were: 1) Endothelial responses and gene regulation to shear stress; 2) Effects of the hydrostatic pressure in the endothelial cell morphology, gene expression of the endothelial cellular surface and proliferation of endothelial cells; 3) Effects of the traction on the human saphenous vein endothelium.

Disfunção endotelial causada pela pressão aguda de distensão em veias safenas humanas utilizadas para revascularização do miocárdio

OBJECTIVE: To study morphofunctional alterations induced by brief pressure increases in human saphenous veins utilized in coronary artery bypass grafting. METHOD: Saphenous veins of 20 patients undergoing coronary artery bypass grafting, were distributed into four experimental groups, control, 100 mmHg, 200 mmHg and 300 mmHg, and submitted to pressure distention over 15 seconds using Krebs solution. The evaluation included CD34 immunohistochemistry and an In vitro vascular reactivity study in organ chambers. RESULTS: The main experimental findings were 1) From pressures of 200 mmHg there was a tendency to reduce the CD34 expression which became statistically significant at 300 mmHg; 2) There was no impairment of the contraction and relaxation as evidenced by in vitro vascular reactivity tests. CONCLUSION: Although vascular reactivity impairment was not demonstrated in vitro, the CD34 expression, measured by imunohistochemistry, shows there is endothelium dysfunction at pressures of 300 mmHg.

Immunohistochemical evaluation of three nitric oxide synthase isoforms in human saphenous vein exposed to different degrees of distension pressures.

The effect of short duration and different degrees of distension pressures was investigated by means of immunohistochemistry of the three nitric oxide synthase isoforms in the human saphenous vein conventionally harvested from 20 patients submitted to coronary artery bypass graft. The human saphenous vein distal portion was divided into four segments, each one allocated to a different group. In Group I (control group), the human saphenous vein segment was not exposed to distension pressure. In Groups II, III, and IV, the human saphenous vein segment was exposed to 100, 200, and 300 mmHg of distension pressure, respectively. The distension pressures were applied and maintained with Krebs solution for 15 s. The human saphenous vein of the control group presented endothelial nitric oxide synthase and neuronal nitric oxide synthase in both endothelial and smooth muscle cells, while the inducible nitric oxide synthase appeared predominantly in the medial layer. Neither 100 nor 200 mmHg of pressurization affected the immunostaining of any nitric oxide synthase isoform. However, the human saphenous vein segments exposed to 300 mmHg of distension pressure showed a reduction in endothelial nitric oxide synthase content in the endothelium, but not in the tunica media. This lower endothelial nitric oxide synthase immunostaining in the intimal cells was associated with endothelial denudation. Therefore, we conclude that care should be taken when handling the human saphenous vein since just a few seconds of distension pressure above the normal systemic pressure can be sufficient to disrupt the endothelium reducing the amount of endothelial nitric oxide synthase and impairing the graft quality.

Exhaled breath condensate collection for nitrite dosage: a safe and low cost adaptation

PURPOSE Standardization of a simple and low cost technique of exhaled breath condensate (EBC) collection to measure nitrite. METHODS Two devices were mounted in polystyrene boxes filled either with crushed ice/salt crystals or dry ice/crushed ice. Blood samples were stored at -70 degrees C for posterior nitrite dosages by chemiluminescence and the Griess reaction. RESULTS a) The use of crushed ice/dry ice or salt revealed sufficient EBC room air collection, but was not efficient for patients under ventilation support; b) the method using crushed ice/salt collected greater EBC volumes, but the nitrite concentrations were not proportional to the volume collected; c) The EBC nitrite values were higher in the surgical group using both methods; d) In the surgical group the nasal clip use diminished the EBC nitrite concentrations in both methods. CONCLUSIONS The exhaled breath condensate (EBC) methodology collection was efficient on room air breathing. Either cooling methods provided successful EBC collections showing that it is possible to diminish costs, and, amongst the two used methods, the one using crushed ice/salt crystals revealed better efficiency compared to the dry ice method.

A utilização do condensado do exalado pulmonar poderá ser incorporada à rotina de unidades de tratamento intensivo

Endogenous production of nitric oxide can be detected and monitored in exhaled air of men and animals. The main objective of this review was to discuss if nitric oxide in exhaled breath condensate is a useful tool when investigating respiratory dysfunctions in intensive care units. Specialized literature reveals an increasing interest in the use of exhaled breath condensate as a non-invasive method to investigate pulmonary disease. However, a standardized method for its collection is lacking, and use of different methods of respiratory support complicates comparison among different studies. In addition, the same specialized literature review emphasized possible difficulties for routine use of the exhaled breath condensate in intensive care patients, mainly under mechanical ventilation. Until exhaled breath condensate becomes a routine tool of research and monitoring of intensive care patients, more specific studies and technologies are still necessary. Its importance has been related to physiological control of the pulmonary function and to physiopathology of pulmonary disease involving chronic inflammation and oxidative stress.