The protective effect of cilostazol on isolated rabbit femoral arteries under conditions of ischemia and reperfusion: the role of the nitric oxide pathway

OBJECTIVES: The clinical significance of ischemia/reperfusion of the lower extremities demands further investigation to enable the development of more effective therapeutic alternatives. This study investigated the changes in the vascular reactivity of the rabbit femoral artery and nitric oxide metabolites under partial ischemia/ reperfusion conditions following cilostazol administration. METHODS: Ischemia was induced using infrarenal aortic clamping. The animals were randomly divided into seven groups: Control 90 minutes, Ischemia/Reperfusion 90/60 minutes, Control 120 minutes, Ischemia/Reperfusion 120/90 minutes, Cilostazol, Cilostazol before Ischemia/Reperfusion 120/90 minutes, and Ischemia 120 minutes/Cilostazol/ Reperfusion 90 minutes. Dose-response curves for sodium nitroprusside, acetylcholine, and the calcium ionophore A23187 were obtained in isolated femoral arteries. The levels of nitrites and nitrates in the plasma and skeletal muscle were determined using chemiluminescence. RESULTS: Acetylcholine-and A23187-induced relaxation was reduced in the Ischemia/Reperfusion 120/90 group, and treatment with cilostazol partially prevented this ischemia/reperfusion-induced endothelium impairment. Only cilostazol treatment increased plasma levels of nitrites and nitrates. An elevation in the levels of nitrites and nitrates was observed in muscle tissues in the Ischemia/Reperfusion 120/90, Cilostazol/Ischemia/Reperfusion, and Ischemia/ Cilostazol/Reperfusion groups. CONCLUSION: Hind limb ischemia/reperfusion yielded an impaired endothelium-dependent relaxation of the femoral artery. Furthermore, cilostazol administration prior to ischemia exerted a protective effect on endotheliumdependent vascular reactivity under ischemia/reperfusion conditions

Effect of the effluent released from the canine internal mammary artery after intraluminal and extraluminal perfusion of acetylcholine and adenosine diphosphate

Segments of the canine internal mammary artery (35 mm in length) were suspended in vitro in an organ chamber containing physiological salt solution (95% O2/5% CO2, pH = 7.4, 37°C). Segments were individually cannulated and perfused at 5 ml/minute using a roller pump. Vasorelaxant activity of the effluent from the perfused internal mammary arteries was bioassayed by measuring the decrease in tension induced by the effluent of the coronary artery endothelium-free ring which had been contracted with prostaglandin F2α (2 × 10-6 M). Intraluminal perfusion of adenosine diphosphate (10-5 M) induced significant increase in relaxant activity in the effluent from the perfused blood vessel. However, when adenosine diphosphate (10-5 M) was added extraluminally to the internal mammary artery, no change in relaxant activity in the effluent was noted. In contrast, acetylcholine produced significant increase in the relaxant activity on the effluent of the perfused internal mammary artery with both intraluminal and extraluminal perfusion. The intraluminal and extraluminal release of endothelium-derived relaxing factor (EDRF) by acetylcholine (10-5 M) can be inhibited by site-specific administration of atropine (10-5 M). These experiments indicate that certain agonists can induce the release of EDRF only by binding to intravascular receptors while other agonists can induce endothelium-dependent vasodilatation by acting on neural side receptors

Ultrasonic tissue characterization of vulnerable carotid plaque: correlation between videodensitometric method and histological examination

BACKGROUND: To establish the correlation between quantitative analysis based on B-mode ultrasound images of vulnerable carotid plaque and histological examination of the surgically removed plaque, on the basis of a videodensitometric digital texture characterization. METHODS: Twenty-five patients (18 males, mean age 67 ± 6.9 years) admitted for carotid endarterectomy for extracranial high-grade internal carotid artery stenosis (≥ 70% luminal narrowing) underwent to quantitative ultrasonic tissue characterization of carotid plaque before surgery. A computer software (Carotid Plaque Analysis Software) was developed to perform the videodensitometric analysis. The patients were divided into 2 groups according to symptomatology (group I, 15 symptomatic patients; and group II, 10 patients asymptomatic). Tissue specimens were analysed for lipid, fibromuscular tissue and calcium. RESULTS: The first order statistic parameter mean gray level was able to distinguish the groups I and II (p = 0.04). The second order parameter energy also was able to distinguish the groups (p = 0,02). A histological correlation showed a tendency of mean gray level to have progressively greater values from specimens with < 50% to >75% of fibrosis. CONCLUSION: Videodensitometric computer analysis of scan images may be used to identify vulnerable and potentially unstable lipid-rich carotid plaques, which are less echogenic in density than stable or asymptomatic, more densely fibrotic plaques

Acesso venoso central de longa duração: experiência com 79 cateteres em 66 pacientes

Procedures such as bone marrow transplantation, chemotherapy, total parenteral nutrition and hemodialysis increasingly require long-term central venous access (LTCVA). According to the indication, fully implantable catheters (with a reservoir) or partially catheters (Broviac- Hickman) are used. In the present study, we evaluated 79 catheres consecutively implanted into 66 patient treated at the University Hospital, Faculty of Medicine of Ribeirão Preto, USP, from January 1993 to June 1997. The following parameters were evaluated: indication of venous access, type of catheter implanted, technique used, early and late complications, and duration of the implant. Thirty four of the 66 patients (51,5%) were men. Mean patient age was 28.2 years. There was a predominance of catheter implantation for chemotherapy in 55 (69.5%) patients and for bone marrow transplantation in 12 (15.2%). Twenty eight catheters with a reservoir (35.5%) and 51 partially implantable catheters (64.5%) were implanted. As to the technique used, 71,4% of the catheters were implanted by percutaneous puncture and the remaining ones by open venous dissection and catheterization. Two types of complications related to the technique occured, 9 infections and 8 late occlusions. The mean duration of catheter was 371 days for the Broviac-Hickman catheters and 395 days for the totally implantable catheters. No death occured due to the implants. The rates of early and late complications observed in the present series are similar to those reported in the literature.Procedimentos, como o transplante de medula óssea, a quimioterapia, a nutrição parenteral total e a hemodiálise, exigem a necessidade cada vez maior do acesso venoso central de longa duração (AVCLD). Utilizam-se, de acordo com a indicação, cateteres totalmente implantáveis (com reservatório) e parcialmente implantáveis (Broviac-Hickman ). Foram avaliados setenta e nove (79) cateteres implantados, consecutivamente, em sessenta e seis (66) pacientes, tratados no Hospital das Clínicas da Faculdade de Medicina de Ribeirão Preto da USP, no período de janeiro de 1993 a junho de 1997. Avaliaram-se os seguintes parâmetros: indicação do acesso venoso, tipo de cateter implantado, técnica utilizada, complicações precoces e tardias e duração do implante. Dos sessenta e seis (66) pacientes, trinta e quatro (34) (51,5%) eram homens. A idade média foi de 28,2 anos. Houve predomínio de indicação de implante de cateter para realizar-se a quimioterapia em cinquenta e cinco (55) (69,5%) pacientes e transplante de medula óssea em doze (12) (15,2%). Foram implantados vinte e oito (28) (35,5%) cateteres com reservatório e cinqüenta e um (51) (64,5%) parcialmente implantáveis. Quanto à técnica utilizada, 71,4% foram implantados por punção percutânea e os demais por dissecção e cateterização venosa, a céu aberto. Ocorreram duas complicações relacionadas à técnica, nove (9) infecções e oito (8) oclusões tardias. A duração média da implantação dos cateteres foi trezentos e setenta e um (371) dias para os cateteres Broviac- Hickman e trezentos e noventa e cinco (395) para o totalmente implantável. Não houve óbito associado aos implantes. Os índices de complicações precoces e tardias, observadas nesta casuística, assemelham- se aos dados encontrados na literatura

Vascular relaxation of canine visceral arteries after ischemia by means of supraceliac aortic cross-clamping followed by reperfusion

<p>Abstract</p> <p>Background</p> <p>The supraceliac aortic cross-clamping can be an option to save patients with hipovolemic shock due to abdominal trauma. However, this maneuver is associated with ischemia/reperfusion (I/R) injury strongly related to oxidative stress and reduction of nitric oxide bioavailability. Moreover, several studies demonstrated impairment in relaxation after I/R, but the time course of I/R necessary to induce vascular dysfunction is still controversial. We investigated whether 60 minutes of ischemia followed by 30 minutes of reperfusion do not change the relaxation of visceral arteries nor the plasma and renal levels of malondialdehyde (MDA) and nitrite plus nitrate (NOx).</p> <p>Methods</p> <p>Male mongrel dogs (n = 27) were randomly allocated in one of the three groups: sham (no clamping, n = 9), ischemia (supraceliac aortic cross-clamping for 60 minutes, n = 9), and I/R (60 minutes of ischemia followed by reperfusion for 30 minutes, n = 9). Relaxation of visceral arteries (celiac trunk, renal and superior mesenteric arteries) was studied in organ chambers. MDA and NOx concentrations were determined using a commercially available kit and an ozone-based chemiluminescence assay, respectively.</p> <p>Results</p> <p>Both acetylcholine and calcium ionophore caused relaxation in endothelium-intact rings and no statistical differences were observed among the three groups. Sodium nitroprusside promoted relaxation in endothelium-denuded rings, and there were no inter-group statistical differences. Both plasma and renal concentrations of MDA and NOx showed no significant difference among the groups.</p> <p>Conclusion</p> <p>Supraceliac aortic cross-clamping for 60 minutes alone and followed by 30 minutes of reperfusion did not impair relaxation of canine visceral arteries nor evoke biochemical alterations in plasma or renal tissue.</p

Effects of 830 and 670 nm Laser on Viability of Random Skin Flap in Rats

Objective: This study aimed to investigate the effect of 830 and 670 nm diode laser on the viability of random skin flaps in rats. Background data: Low-level laser therapy (LLLT) has been reported to be successful in stimulating the formation of new blood vessels and reducing the inflammatory process after injury. However, the efficiency of such treatment remains uncertain, and there is also some controversy regarding the efficacy of different wavelengths currently on the market. Materials and methods: Thirty Wistar rats were used and divided into three groups, with 10 rats in each. A random skin flap was raised on the dorsum of each animal. Group 1 was the control group, group 2 received 830 nm laser radiations, and group 3 was submitted to 670 nm laser radiation (power density = 0.5 mW/cm(2)). The animals underwent laser therapy with 36 J/cm(2) energy density (total energy = 2.52 J and 72 sec per session) immediately after surgery and on the 4 subsequent days. The application site of laser radiation was one point at 2.5 cm from the flap's cranial base. The percentage of skin flap necrosis area was calculated on the 7th postoperative day using the paper template method. A skin sample was collected immediately after to determine the vascular endothelial growth factor (VEGF) expression and the epidermal cell proliferation index (KiD67). Results: Statistically significant differences were found among the percentages of necrosis, with higher values observed in group 1 compared with groups 2 and 3. No statistically significant differences were found among these groups using the paper template method. Group 3 presented the highest mean number of blood vessels expressing VEGF and of cells in the proliferative phase when compared with groups 1 and 2. Conclusions: LLLT was effective in increasing random skin flap viability in rats. The 670 nm laser presented more satisfactory results than the 830 nm laser.National Council for Scientific and Technological Development (CNPq)National Council for Scientific and Technological Development (CNPq)Fundacao de Apoio ao Ensino, Pesquisa e Assistencia (FAEPA)Fundacao de Apoio ao Ensino, Pesquisa e Assistencia (FAEPA