Interleukins and inflammatory markers in in-stent restenosis after femoral percutaneous transluminal angioplasty.

BACKGROUND: Inflammatory activity may influence results of percutaneous transluminal angioplasty (PTA). The purpose of this study was to evaluate the relationship between (1) proinflammatory markers (interleukin [IL]-6, IL-8, tumor necrosis factor α (TNF-α), and highly sensitive C-reactive protein [CRP]); (2) type 1 T helper cell marker (IL-12); and (3) Type 2 T helper cell marker (transforming growth factor-ß [TGF-ß]) and in-stent restenosis, 6 months after femoral PTA with stent implantation. METHODS: We performed a single-center prospective study with 26 patients with peripheral artery disease requiring PTA and stenting. As control, we studied 26 patients who were submitted to diagnostic angiography. Serum samples were collected before stent implantation, 24 hr and 6 months after the procedure. To detect restenosis, a new angiography was obtained at 6 months. RESULTS: Restenosis was observed in 10 (38.5%) patients who underwent PTA and stenting. There was a trend to increased levels of IL-6, TNF-α, TGF-ß, and IL-12 24 hr after PTA and stenting compared with pretreatment. IL-8 levels showed a statistically significant reduction 24 hours after versus pretreatment (P < 0.05), 6 months vs. pretreatment, and 6 months vs. 24 hr (P < 0.01). There was no statistical difference between cytokine levels when comparing restenosis and no restenosis groups. CRP levels were already high at pretreatment. CONCLUSIONS: No inflammatory marker was independently identified as risk factor for in-stent restenosis, 6 months after femoral PTA with stent implantation. The question that remains is whether acute phase reactants will be clinically useful to predict the individual risk for in-stent restenosis.

Methylene blue administration in the compound 48/80-induced anaphylactic shock: hemodynamic study in pigs / Administração de azul de metileno no choque anafilático induzido por composto 48/80: estudo hemodinâmico em suínos

PURPOSE: To verify if the methylene blue (MB) administration prevents and/or reverses the compound 48/80 (C48/80)-induced anaphylactic shock in pigs. METHODS: Female Dalland pigs were anesthetized and had the hemodynamic parameters recorded during the necessary time to administer some drugs and observe their effect. The animals were randomly assigned to one of the five groups: 1) control; 2) MB: the animals received a bolus injection of MB (2 mg/kg) followed by continuous infusion of MB (2.66 mg/Kg/h delivered by syringe infusion pump); 3) C48/80: the animals received a bolus injection of C48/80 (4 mg/kg); 4) C48/80+MB: the animals received a bolus injection of C48/80 (4 mg/kg) and 10 minutes after the C48/80 administration the animals received a bolus injection of MB (2 mg/kg) followed by continuous infusion of MB (2.66 mg/Kg/h delivered by syringe infusion pump); 5) MB+C48/80: the animals received a bolus injection of MB (2 mg/kg) and 3 minutes later they received a bolus injection of C48/80 (4 mg/kg). RESULTS: The intravenous infusion of MB alone caused no changes in the mean arterial pressure (MAP) showing that the administered MB dose was safe in this experimental model. The C48/80 was effective in producing experimental anaphylactic shock since it was observed a decrease in both MAP and cardiac output (CO) after its administration. The MB did not prevent or reverse the C48/80-induced anaphylactic shock in this model. In fact, the MAP of the animals with anaphylactic shock treated with MB decreased even more than the MAP of the animals from the C48/80 group. On the other hand, the C48/80-induced epidermal alterations disappeared after the MB infusion. CONCLUSION: Despite our data, the clinical manifestations improvement brings some optimism and does not allow excluding the MB as a possible therapeutic option in the anaphylactic shock.

OBJETIVO: Verificar se a administração de azul de metileno (AM) previne e/ou reverte o choque anafilático induzido por composto 48/80 (C48/80) em suínos. MÉTODOS: Porcos fêmeas Dalland foram anestesiados e tiveram os parâmetros hemodinâmicos registados durante o tempo necessário para administrar algumas drogas e observar seu efeito. Os animais foram aleatoriamente destribuídos em um dos cinco grupos: 1) controle, 2) AM: os animais receberam uma injeção em bolus de AM (2mg/kg), seguido de infusão contínua de AM (2,66mg/Kg /h por bomba de infusão de seringa); 3) C48/80: os animais receberam uma injeção em bolus de C48/80 (4mg/kg); 4) C48/80 + AM: os animais receberam uma injeção em bolus de C48/80 (4mg/kg) e 10 minutos após a administração de C48/80 os animais receberam uma injeção em bolus de AM (2mg/kg), seguido de infusão contínua de AM (2,66mg/kg/h por bomba de infusão de seringa); 5) AM+C48/80: os animais receberam uma injeção em bolus de AM (2mg/kg) e três minutos depois, receberam uma injeção em bolus de C48/80 (4mg/kg). RESULTADOS: A infusão intravenosa de AM não causou mudanças na pressão arterial média (PAM), mostrando que a dose de AM administrada foi segura neste modelo experimental. O C48/80 foi eficaz na indução do choque anafilático experimental, uma vez que foi observada redução na PAM e débito cardíaco (DC), após a sua administração. O AM não preveniu ou reverte o choque anafilático induzido por C48/80 neste modelo. Na verdade, a PAM dos animais com choque anafilático tratados com AM diminuiu mais do que o PAM dos animais do grupo C48/80. Por outro lado, as alterações epidérmicas induzidas pelo C48/80 desapareceu após a infusão do AM. CONCLUSÃO: Apesar dos resultados a melhora clínica das manifestações anafiláticas permite considerar a possibilidade do azul de metileno como opção terapêutica no tratamento do choque anafilático.

Methylene blue administration in the compound 48/80-induced anaphylactic shock: hemodynamic study in pigs.

PURPOSE: To verify if the methylene blue (MB) administration prevents and/or reverses the compound 48/80 (C48/80)-induced anaphylactic shock in pigs. METHODS: Female Dalland pigs were anesthetized and had the hemodynamic parameters recorded during the necessary time to administer some drugs and observe their effect. The animals were randomly assigned to one of the five groups: 1) control; 2) MB: the animals received a bolus injection of MB (2 mg/kg) followed by continuous infusion of MB (2.66 mg/Kg/h delivered by syringe infusion pump); 3) C48/80: the animals received a bolus injection of C48/80 (4 mg/kg); 4) C48/80+MB: the animals received a bolus injection of C48/80 (4 mg/kg) and 10 minutes after the C48/80 administration the animals received a bolus injection of MB (2 mg/kg) followed by continuous infusion of MB (2.66 mg/Kg/h delivered by syringe infusion pump); 5) MB+C48/80: the animals received a bolus injection of MB (2 mg/kg) and 3 minutes later they received a bolus injection of C48/80 (4 mg/kg). RESULTS: The intravenous infusion of MB alone caused no changes in the mean arterial pressure (MAP) showing that the administered MB dose was safe in this experimental model. The C48/80 was effective in producing experimental anaphylactic shock since it was observed a decrease in both MAP and cardiac output (CO) after its administration. The MB did not prevent or reverse the C48/80-induced anaphylactic shock in this model. In fact, the MAP of the animals with anaphylactic shock treated with MB decreased even more than the MAP of the animals from the C48/80 group. On the other hand, the C48/80-induced epidermal alterations disappeared after the MB infusion. CONCLUSION: Despite our data, the clinical manifestations improvement brings some optimism and does not allow excluding the MB as a possible therapeutic option in the anaphylactic shock.

Óxido-nítrico-sintases e doenças cardiovasculares / Nitric oxide synthases and cardiovascular disease

O conhecimento das óxido-nítrico-sintases (NOSs) é de extrema importância científica, não só para o entendimento de novos mecanismos fisiopatológicos, mas, também, por ser um alvo para descoberta de novas intervenções terapêuticas. Assim, o propósito deste texto é o de atualizar o papel das NOSs nos mecanismos fisiopatológicos das principais doenças cardiovasculares: infarto agudo do miocárdio, síndrome metabólica, insuficiência cardíaca e outras doenças cardiovasculares. Incluindo conceitos adicionais, discute-se, também, o duplo papel das NOSs na fisiopatologia das doenças cardiovasculares.

Knowledge of nitric oxide synthases (NOSs) is of scientific importance, not only for our understanding of new pathophysiological mechanisms, but also a target for the discovery of new therapeutic interventions. Thus, the purpose of this paper is to update the role of NOSs in the pathophysiological mechanisms of major cardiovascular diseases: acute myocardial infarction, metabolic syndrome, heart failure and other cardiovascular diseases. Including additional concepts the NOSs dual role in the pathophysiology of cardiovascular diseases is also being discussed.

Disfunção endotelial vasoplégica / The endothelial vasoplegic dysfunction

Embora a maioria dos estados de choque circulatório esteja associada com diminuição do débito cardíaco, uma situação distinta ocorre nos casos de choques por diminuição da capacitância vascular, na qual a situação de vasoplegia associa-se à elevação do débito cardíaco, configurando uma situação hiperdinâmica com hipotensão grave resistente a altas doses de catecolaminas. O mau prognóstico parece mais bem correlacionado com a baixa resistência vascular, levando à conclusão de que a vasoplegia é o fator prognóstico determinante. Dessa forma, o controle parácrino da capacitância vascular passa a ser um fator extremamente importante para investigações clínicas e experimentais na busca de novos conhecimentos fisiopatológicos e terapêuticos que possam contribuir para o tratamento e prognóstico da vasoplegia. Assim, a disfunção endotelial “vasoplégica” estaria presente nos estados de choque distributivo causada por ações de citocinas que estimulam liberação patológica de fatores relaxantes do endotélio, principalmente do óxido nítrico (sepse, anafilaxia, reações anafilactoides e vasoplegias relacionadas à circulação extracorpórea). Ressalte-se que a disfunção endotelial está associada a todos os tipos de estado de choque, disfunção essa abordada nessa revisão.

Although most circulatory shock conditions are associated with decreased cardiac output, a different situation occurs in cases of circulatory shock by decreasing vascular capacitance vasoplegia when the condition is associated with elevation of cardiac output by setting a hyperdynamic state with hypotension resistant to high doses of catecholamines. The poor prognosis appears better correlated with low vascular resistance, leading to the conclusion that the vasoplegia prognostic factor is decisive. Thus, the paracrine control of vascular capacitance becomes an extremely important factor for clinical and experimental investigations in research of new pathophysiological and therapeutic knowledge that may contribute to the treatment and prognosis of vasoplegia. Thus, endothelial "vasoplegic" dysfunction would be present in the distributive shock states caused by the actions of cytokines that stimulate pathological release of endothelial relaxing factors, mainly nitric oxide (sepsis, anaphylaxis, anaphylactic reactions and vasoplegias related to cardiopulmonary bypass). It is noteworthy that endothelial dysfunction is associated with all types of shocks and this impairment is discussed in this review.

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.

Diabetes and vascular disease: basic concepts of nitric oxide physiology, endothelial dysfunction, oxidative stress and therapeutic possibilities.

The vascular manifestations associated with diabetes mellitus (DM) result from the dysfunction of several vascular physiology components mainly involving the endothelium, vascular smooth muscle and platelets. It is also known that hyperglycemia-induced oxidative stress plays a role in the development of this dysfunction. This review considers the basic physiology of the endothelium, especially related to the synthesis and function of nitric oxide. We also discuss the pathophysiology of vascular disease associated with DM. This includes the role of hyperglycemia in the induction of oxidative stress and the role of advanced glycation end-products. We also consider therapeutic strategies.

Methylene blue improves hemodynamic shock but increases lipoperoxidation in severe acute pancreatitis pig model.

PURPOSE: Study hemodynamic pattern and lipoperoxidation during methylene blue (MB) treatment on taurocholate - enterokinase induced acute pancreatitis (AP). METHODS: Thirty pigs were equally divided in control group; MB group; AP group; MB previous AP group; and MB after 90 min of induced AP group. MB was given iv in a bolus dose (2 mg.kg-1) followed by maintenance dose (2 mg.kg-1.h-1). Hemodynamic parameters were recorded continuously during 180 min by Swan-Ganz catheter. Blood samples were taken every 60 min to determine arterial and venous nitrate, malondialdehyde (MDA) and amylase. Pancreatic tissue was removed for histopathologic study. RESULTS: In AP group MBP and CO decreased over time 33% (p<0.05) and 52% (p<0.05), respectively. In MB previous induced-AP group, there was 70 minutes delay (p<0.05) to decrease MBP and CO. In MB group arterial and venous nitrite decreased (p<0.05) over time. MB infusion increased (p>0.05) serum MDA when associated to AP. After induced AP, MB did not reverse MBP and CO decrease. There was no difference in serum amylase and necro-hemorrhagic findings with MB treatment. CONCLUSIONS: In this taurocholate-induced AP model MB treatment delayed hemodynamic shock and decreases serum nitrate levels but increases serum MDA levels. No volemic replacement was done and it may have been a mitigated factor to a poor tissue perfusion and impairment microcirculation. Further investigations are needed to elucidate MB treatment role during AP treatment.

Glycol methacrylate-embedding medium to study morphological alterations of saphenous vein under brief and crescent pressurizations.

PURPOSE: This study sought to evaluate the efficiency of glycol methacrylate-embedding medium to detect morphological alterations of human saphenous vein submitted to brief and crescent pressurizations. METHODS: Saphenous veins of 20 CABG patients were randomly distributed into four experimental groups (control, 100, 200 and 300 mmHg pressures during 15 seconds). To quantify the percentage of endothelium spread over vein surface a microscope magnification of 100x was used for measurements. Morphometric analysis was performed using videomicroscopy with the Leica Qwin software in conjunction with a Leica microscope, videocamera, and an on-line computer. RESULTS: A slight tendency of quantitative increase was observed in all parameters including percentage of endothelium spread over vein surface and thickness of saphenous vein walls (intima and media layers). CONCLUSIONS: The glycol methacrylate-embedding allowed sections with adequate resolution of structural details and revealed to be an extremely useful method to study pressurized human saphenous veins.

Plasma nitrate/nitrite (NOx) is not a useful biomarker to predict inherent cardiopulmonary bypass inflammatory response.

BACKGROUND AND AIM: There were strong evidences that nitric oxide has capital importance in the progressive vasodilatation associated with varied circulatory shock forms, including systemic inflammatory response syndrome (SIRS), in patients undergoing cardiac surgeries for cardiopulmonary bypass (CPB). If CPB procedures, per se, are the inciting stimulus for inflammation, plasma nitrate/nitrite (NOx) excretion would be expected to be higher in these patients rather than in patients operated without CPB. In consequence, we hypothesized that increased levels of NOx would be predictive for vasoplegic syndrome. METHODS: Thirty patients were assigned to three groups: Group 1--coronary artery bypass graft (CABG) roller pump CPB; Group 2--CABG centrifugal vortex pump CPB; and Group 3--heart valve surgery roller pump CPB. Sampling of venous blood for chemiluminescence plasma NOx dosage was achieved at the following time points: (1) before anesthesia induction; (2) after anesthesia induction; (3) before heparin infusion; (4) after heparin infusion; (5) CPB-30 minutes; (6) CPB-60 minutes; (7) before protamine infusion; (8) after protamine infusion; and (9) on return to the recovery area. RESULTS: There were no intergroup differences regarding age and anesthetic regimen, and the number of arteries grafted was not different between the CABG groups. There were no NOx statistic differences, neither among the three groups of patients or among the surgery time. In addition, there was no correlation among NOx, lactate, and hemoglobin. CONCLUSIONS: Considering the inflammatory process intrinsic to CPB, this study reinforces the idea that plasma NOx is not useful as a biomarker of inflammatory response onset, which may or may not lead to SIRS and/or vasoplegic syndrome.

Compound 48/80 induces endothelium-dependent and histamine release-independent relaxation in rabbit aorta.

Compound 48/80 (C48/80) is a synthetic condensation product of N-methyl-p-methoxyphenethylamine with formaldehyde and is an experimental drug used since the 1950s to induce anaphylactic shock through histamine release. This study was carried out to further elucidate the mechanism by which this drug induces nitric oxide (NO) release. Our specific goals were: (a) to verify if C48/80's relaxation occurs through the stimulation of histamine receptors; (b) to evaluate the endothelium-dependent relaxation induced by C48/80; (c) to identify NO as the endothelium-relaxing factor released by C48/80; (d) to identify the NO synthase (NOS) responsible for NO release; and (e) to verify if the relaxation induced by C48/80 is calcium and cyclic guanidine monophosphate (cGMP) dependent. Rabbit aorta segments, with and without endothelium, were suspended in organ chambers (25ml) filled with Krebs solution maintained at 37 degrees C, bubbled with 95% O(2)/5% CO(2) (pH 7.4). Phenylephrine was used to contract the segments. Other protocol drugs included H(1)- and H(2)-receptor antagonists, cyclooxygenase, NOS, guanylyl cyclase and phospholipase C (PLC) inhibitors. Endothelium-dependent relaxation induced by C48/80 was also studied in calcium-free Krebs solution associated with a calcium chelator. In summary, our investigation demonstrated that the C48/80 vasodilating action: (a) does not depend on H(1) and H(2) histamine receptors; (b) is NO endothelium-dependent; (c) is dependent on the endothelial constitutive NOS (NOS-3) isoform activation; (d) is cGMP-dependent; and that NOS-3 activation by C48/80: (a) is independent of PLC up to 25mug/ml and (b) is partially dependent of this lipase in higher doses.

Methylene blue improves hemodynamic shock but increases lipoperoxidation in severe acute pancreatitis pig model / Azul de metileno melhora as condições hemodinâmicas do choque circulatório, mas aumenta a peroxidação lipídica em um modelo suino de pancreatite aguda grave

PURPOSE: Study hemodynamic pattern and lipoperoxidation during methylene blue (MB) treatment on taurocholate - enterokinase induced acute pancreatitis (AP). METHODS: Thirty pigs were equally divided in control group; MB group; AP group; MB previous AP group; and MB after 90 min of induced AP group. MB was given iv in a bolus dose (2mg.kg-1) followed by maintenance dose (2 mg.kg-1.h-1). Hemodynamic parameters were recorded continuously during 180 min by Swan-Ganz catheter. Blood samples were taken every 60 min to determine arterial and venous nitrate, malondialdehyde (MDA) and amylase. Pancreatic tissue was removed for histopathologic study. RESULTS: In AP group MBP and CO decreased over time 33 percent (p<0.05) and 52 percent (p<0.05), respectively. In MB previous induced-AP group, there was 70 minutes delay (p<0.05) to decrease MBP and CO. In MB group arterial and venous nitrite decreased (p<0.05) over time. MB infusion increased (p>0.05) serum MDA when associated to AP. After induced AP, MB did not reverse MBP and CO decrease. There was no difference in serum amylase and necro-hemorrhagic findings with MB treatment. CONCLUSIONS: In this taurocholate-induced AP model MB treatment delayed hemodynamic shock and decreases serum nitrate levels but increases serum MDA levels. No volemic replacement was done and it may have been a mitigated factor to a poor tissue perfusion and impairment microcirculation. Further investigations are needed to elucidate MB treatment role during AP treatment.

OBJETIVO: estudar o perfil hemodinâmico e a lipoperoxidação durante o tratamento com azul de metileno (AM) de pancreatite aguda (PA) induzida por taurocolato-enteroquinase. MÉTODOS: Trinta porcos foram igualmente divididos em: grupo controle, grupo AM; grupo PA; grupo AM prévio à PA; grupo AM após 90 minutos após a indução da PA. O AM foi administrado sob a forma de bolus EV (2mg.kg-1) seguido por dose de manutenção (2 mg.kg-1.h-1). Os parâmetros hemodinâmicos foram registrados continuamente durante 180 min com auxílio de cateter de Swan-Ganz. Amostras sanguíneas foram colhidas a cada 60 min para a determinação arterial e venosa de nitrato, malondialdeido (MDA) and amilase. Removeu-se tecido pancreático para estudo histopatológico. RESULTADOS: No grupo PA a pressão arterial media (PAM) e o débito cardíaco (DC) diminuíram respectivamente 33 por cento (p<0.05) e 52 por cento (p<0.05) no decorrer do tempo. No grupo AM prévio à indução da PA ocorreu 70 minutes de demora (p<0.05) para as diminuições da PAM e DC. No grupo AM houve diminuição temporal do nitrato arterial e venoso (p<0.05). A infusão de AM aumentou os valores de MDA sérico quando associado a PA (p>0.05). Após a indução da PA a infusão de AM não reverteu as quedas da PA e DC. Não houve diferenças nos níveis de amilase sérica e achados histológicos com o tratamento com o azul de metileno. CONCLUSÕES: No presente modelo de PA induzida por taurocolato o AM retardou o desenvolvimento do choque circulatório, diminuiu os níveis de nitrato mas aumentou os níveis de MDA. Não se realizou nenhum tipo de reposição volêmica que poderia melhorar a perfusão tecidual e melhora da microcirculação. Investigações adicionais são necessárias para elucidar o papel terapêutico do AM no tratamento da PA aguda.

Glycol methacrylate-embedding medium to study morphological alterations of saphenous vein under brief and crescent pressurizations / Inclusão em glicol metacrilato para estudar alterações morfológicas de veias safenas humanas submetidas a pressurizações breves e crescentes

PURPOSE: This study sought to evaluate the efficiency of glycol methacrylate-embedding medium to detect morphological alterations of human saphenous vein submitted to brief and crescent pressurizations. METHODS: Saphenous veins of 20 CABG patients were randomly distributed into four experimental groups (control, 100, 200 and 300 mmHg pressures during 15 seconds). To quantify the percentage of endothelium spread over vein surface a microscope magnification of 100x was used for measurements. Morphometric analysis was performed using videomicroscopy with the Leica Qwin software in conjunction with a Leica microscope, videocamera, and an on-line computer. RESULTS: A slight tendency of quantitative increase was observed in all parameters including percentage of endothelium spread over vein surface and thickness of saphenous vein walls (intima and media layers). CONCLUSIONS: The glycol methacrylate-embedding allowed sections with adequate resolution of structural details and revealed to be an extremely useful method to study pressurized human saphenous veins.

OBJETIVO: Avaliar a inclusão em glicol metacrilato para estudar alterações morfológicas de veias safenas humanas submetidas a pressurizações breves e crescentes. MÉTODOS: Veias safena de 20 pacientes submetidos a cirurgia de revascularização do miocárdio foram distribuídas ao acaso em quatro grupos experimentais (controle, pressões de 100, 200 e 300 mmHg durante 15 segundos). Para quantificar a percentagem da superfície venosa recoberta por endotélio utilizou-se o aumento de 100x. A análise morfométrica foi realizada utilizando-se videomicroscopia com auxílio do software Leica Qwin em conjunto com um microscópio Leica e videocâmera, acoplados a um computador. RESULTADOS: Observou-se uma leve tendência de aumento quantitativo de todos os parâmetros avaliados, incluindo a percentagem de superfície recoberta por endotélio e a espessura das paredes das veias safenas. CONCLUSÕES: A inclusão em glicol metracrilato permitiu secções com adequada resolução dos detalhes estruturais, revelando-se um método extremamente útil para o estudo de veias safenas humanas pressurizadas.

Mechanical forces and human saphenous veins: coronary artery bypass graft implications.

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.

Endothelium dysfunction caused by acute pressure distension of human saphenous vein used for myocardial revascularization.

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 immunohistochemistry, shows there is endothelium dysfunction at pressures of 300 mmHg.

In vitro pharmacological study of femoral artery vascular reactivity after inferior canine hindlimb ischemia/reperfusion: effects of in vivo nitric oxide blocker infusion.

The aim of the investigation was to study the possible effects of in vivo infusion of nitric oxide (NO) blockers upon the in vitro endothelium-dependent femoral reactivity. The experimental model tested herein was the inferior canine hindlimb global ischemia induced by infrarenal abdominal aortic cross-clamping followed by reperfusion. The NO blockers employed in the tests were N(G)-nitro-l-arginine methyl ester (L-NAME), aminoguanidine (AMG), and methylene blue (MB), which were infused immediately after the anesthesia induction. The research protocol was standardized in two main experimental groups, control and ischemia/reperfusion (I/R) injury, randomized in eight subgroups including controls and NO blockers. The femoral artery vascular reactivity was studied in vitro with the aid of a setup consisting of eight organ chambers, where segments of 4-5 mm were suspended and connected to force transducers in the presence of indomethacin to block the cyclooxygenase pathway. The NO-release pathway was evaluated by using specific pharmacological agonists in the in vitro experiments. The L-NAME in vivo infusion led to in vitro endothelium dysfunction in both groups and was associated with high mortality in the animals submitted to I/R. AMG and MB, two clinically used drugs, did not cause in vitro endothelium dysfunction in either of the two groups, which gives evidence that these drugs are not deleterious in the milieu of I/R injury. Nitrite/nitrate plasma levels were not significant except for the L-NAME groups, which presented significant NO decrease.

Disfunção endotelial causada pela pressão aguda de distensão em veias safenas humanas utilizadas para revascularização do miocárdio / Endothelium dysfunction caused by acute pressure distension of human saphenous vein used for myocardial revascularization

OBJETIVO: Estudar as alterações morfofuncionais induzidas por pressão de distensão, em veias safenas humanas utilizadas para revascularização do miocárdio. MÉTODO: Foram estudadas veias safenas de 20 pacientes, distribuídas em quatro grupos experimentais: controle, 100, 200 e 300 mmHg, submetidos a distensões pressóricas com solução de Krebs por 15 segundos. A metodologia utilizada incluiu: 1) Imunohistoquímica do CD34; 2) Estudo in vitro da reatividade vascular em câmaras de órgãos. RESULTADOS: Os principais achados experimentais foram: 1) A partir da pressurização com 200 mmHg, observou-se uma tendência à diminuição da expressão do CD34, tornando-se estatisticamente significante com 300 mmHg; 2) Não houve comprometimento da contratilidade e dos relaxamentos estudados in vitro. CONCLUSÕES: Embora o estudo in vitro não tenha demonstrado comprometimento da reatividade vascular das veias estudadas, o estudo imunohistoquímico do CD34 mostrou que existe disfunção endotelial com pressurizações de 300 mmHg.

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.

Forças mecânicas e veias safenas humanas: implicação na revascularização do miocárdio / Mechanical forces and human saphenous veins: coronary artery bypass graft implications

As células endoteliais vasculares estão expostas a uma variedade de forças mecânicas in vivo, resultantes do fluxo sangüíneo pulsátil. Dentre essas forças, destacam-se: forças de cisalhamento, tangenciais à parede do vaso, produzidas pelo atrito com o fluxo sangüíneo viscoso, tensão de complacência da parede vascular e a pressão hidrostática do conteúdo sangüíneo no interior da vasculatura. Diversos autores estudaram as alterações hemodinâmicas, funcionais e morfológicas em veias safenas humanas causadas por esses tipos de forças com resultados conflitantes. A motivação dessa revisão foi analisar dados da literatura e alguns dados experimentais do nosso laboratório. Os aspectos revistos são: 1) Respostas endoteliais e regulação gênica causadas pelo shear stress; 2) Efeitos da pressão hidrostática na morfologia da célula endotelial, expressão gênica da superfície celular endotelial e proliferação das células endoteliais, 3) Efeitos da tração no endotélio de veias safenas humanas.

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.

The cytoprotective effect of a nitric oxide donor drug on gastric mucous membrane of rats treated with ketoprofen, a non-steroidal anti-inflammatory drug.

BACKGROUND: Non-steroidal anti-inflammatory drugs are considered today a very important group of medication, with a wide variety of therapeutic use, in different areas of modern medicine. Despite their beneficial effects on the patient, these drugs show a high incidence of side effects, mainly in the gastrointestinal tract. The physiopathological mechanisms of non-steroidal anti-inflammatory drugs induced lesions and the gastric mucosa defense mechanism became an important source for medical research, especially those which try to evaluate the role of nitric oxide as a cytoprotective agent. AIM: To define a possible cytoprotective effect of a nitric oxide donor, isosorbide dinitrate, on the gastric mucous of rats submitted to non-steroidal anti-inflammatory drugs ketoprofen treatment. METHODS: Adult male Wistar rats, previously submitted to starvation for 24 hours and divided in three groups: group I (standard): animals that received isotonic saline solution intragastric by gavage and intravenous. Group II (control-ketoprofen): animals that received isotonic saline solution intragastric by gavage and ketoprofen intravenous. Group III (nitrate/ketoprofen): animals that received 2mM solution of isosorbide dinitrate intragastric by gavage and ketoprofen intravenous. Later on, these animals were sacrificed and had their stomach removed and submitted to macroscopical, microscopical and biochemical studies. The evaluated parameters were: a) gastric lesion index; b) gastric mucous layer thickness; c) gastric tissue nitrate/nitrite (NOx) concentration and d) gastric tissue malondialdehyde concentration. RESULTS: a) Gastric lesion index evaluation showed a smaller statistically significant incidence on the animals of group III; b) group III showed a thicker mucous layer, which also was statistically significant, when compared to group II; c) the variation on tissue nitrate/nitrite concentration was similar in all three groups, without statistical significance when compared to each other. CONCLUSION: Isosorbide dinitrate has a cytoprotective activity on the gastric mucosa of rats submitted to ketoprofen action.

Hemodynamic and vascular endothelium function studies in healthy pigs after intravenous bolus infusion of methylene blue.

OBJECTIVE: Clinical benefit of methylene blue (MB) treating NO-induced vasoplegia has been reported in sepsis, systemic inflammatory response syndrome (SIRS) in cardiac surgery and anaphylactic shock, but its safety is sometimes questioned, mainly regarding its hemodynamic effects and the possibility of causing endothelium dysfunction. To examine the nitric oxide plasma levels and cardiovascular effects of the infusion of MB in vivo and its effects on endothelium-dependent and endothelium-independent in vitro vascular relaxation. METHODS: The study protocol included two experimental groups of female pigs: Group I (Control) - the animals (n=6) did not receive MB; Group II (MB)--the animals received 3 mg/kg of MB intravenous bolus infusion. After fifteen minutes of hemodynamic parameter recording the animals were sacrificed by exsanguination, and in vitro studies were conducted using segments of coronary, hepatic, superior mesenteric and renal arteries, to determine the effect of MB on the arterial endothelium function with regard to NO release. Nitric oxide plasma levels (NOx) were measured in each of the experimental groups. RESULTS: The results obtained in the present investigation were: 1) intravenous infusion of MB (3.0 mg/kg) caused no hemodynamic changes; 2) absolute and percent plasma NOx values did not differ between the experimental groups; and 3) in vitro study of vascular relaxation showed no significant difference between groups. These results show that MB intravenous infusion seems to be safe. This finding agrees with data from clinical experiments where MB was used to treat vasoplegic syndrome after cardiopulmonary bypass, systemic inflammatory response syndrome (SIRS) and anaphylaxis. These results were not unexpected because, as in healthy subjects, hemodynamics is only fine tuned and not fully under NO control; therefore, MB inhibiting guanylyl cyclase is not expected to do anything. CONCLUSION: Intravenous use of MB, at the investigated dose, did not cause any abnormal hemodynamic responses or impairment of endothelium-dependent relaxation.