Márcio Luís Lucas

Protective effect of allopurinol in the renal ischemia–reperfusion in uninephrectomized rats

The effect of allopurinol (an inhibitor of xanthine oxidase) on oxidative stress, renal dysfunction, and histologic alterations was evaluated during the renal ischemia--reperfusion in uninephrectomized rats. Renal malondialdehyde and serum creatinine levels significantly increased after renal ischemia--reperfusion. However, the pretreatment with allopurinol demonstrated a protector effect in these parameters. Renal ischemia--reperfusion provoked a significant renal damage in the operated group. Tubular atrophy and interstitial fibrosis were attenuated by allopurinol when given prior to the surgery. In our study, allopurinol had a strong tendency to exert a beneficial effect during renal ischemia--reperfusion in uninephrectomized rats.

The role of nitric oxide pathway in the renal ischemia-reperfusion injury in rats.

INTRODUCTION Nitric oxide (NO), synthesized from L-arginine by the enzyme nitric oxide synthase (NOS), seems to play an ambiguous role during tissue ischemia-reperfusion injury. Our objective was to evaluate the effects of L-arginine, a NO donor, and N(G)-nitro-L-arginine-methylester (L-NAME), a NOS inhibitor, on oxidative stress, renal dysfunction, histologic alterations and surgical mortality rate induced by renal ischemia-reperfusion (RIR) in uninephrectomized rats. MATERIALS AND METHODS One-hundred and ninety-seven Wistar rats were randomized into five experimental groups. Group 1: sham operation; group 2: right uninephrectomy (UNI); group 3: UNI + RIR in the contralateral kidney; group 4: UNI + L-NAME (20 mg/kg; intraperitoneally) + RIR; and group 5: UNI + L-arginine + RIR. The effect of the drugs was evaluated by lipid peroxidation measured by the renal malondialdehyde (MD) content and chemiluminescence (CL) levels, serum creatinine (Cr) levels, urinary volume, tubular necrosis and athrophy, inflammatory infiltrate, interstitial fibrosis as histologic evaluation and surgical mortality rate after the procedures. A P value less than 0.05 was considered significant. RESULTS Right uninephrectomy did not alter the renal parameters. RIR increased Cr levels (at 24 and 96 h of reperfusion), index of lipid peroxidation (both MD and QL levels), and worsened the histologic aspects. Pretreatment with L-arginine reduced the kidney levels of QL when compared with the non-treated group (5574 +/- 909 vs. 13 660 +/- 1104 cps/mg of protein; P < 0.05) but increased the MD levels (0.97 +/- 0.24 vs. 0.79 +/- 0.06 nmol/mg of protein; P < 0.05). Moreover, L-arginine attenuated the increment of Cr levels, inflammatory infiltrate and tubular athrophy in rats subjected to RIR (P < 0.05). On the other hand, pretreatment with L-NAME increased both CL (17 482 +/- 4397 vs. 13 660 +/- 1104 cps/mg of protein; P < 0.05) and MD levels (1.16 +/- 0.11 vs. 0.79 +/- 0.06 nmol/mg of protein; P < 0.05). Furthermore, L-NAME worsened the renal dysfunction (P < 0.05) at 192 h after the RIR, and surgical mortality rates were similar (P > 0.05). CONCLUSION L-arginine has a tendency to exert a beneficial effect on renal damage during RIR in rats. Moreover, L-NAME seems to worsen the renal damage by increasing the kidney-levels of CL and impairment of renal function probably due to reduction of NO production.

The Effects of Allopurinol in Hepatic Ischemia and Reperfusion: Experimental Study in Rats

Background/Aims: Some studies have shown that postischemic hepatic dysfunction is mainly due to oxygen free radicals that are generated by xanthine oxidase. The present study was undertaken to determine the effect of allopurinol, an inhibitor of xanthine oxidase, on oxidative stress, liver injury and histologic alterations induced by hepatic ischemia-reperfusion in rats. Methods: One hundred and sixty Wistar rats were used and divided into three groups. Group 1: sham operation; group 2: 50 min of ischemia followed by 1 h of reperfusion, and group 3: pretreatment with allopurinol and 50 min of ischemia followed by 1 h of reperfusion. The effect of allopurinol was evaluated by plasma levels of alanine aminotransferase and aspartate aminotransferase, histopathologic studies, and lipid peroxidation measured by the thiobarbituric acid reactive substances method and chemiluminescence initiated by tert-butyl hydroperoxide technique. Results: Ischemia followed by reperfusion promoted an increase in lipid peroxidation of the hepatic cells when compared to the sham-operated group (p < 0.05). This increase was attenuated in the group treated with allopurinol (p < 0.05). Allopurinol also showed a protective effect on hepatocellular necrosis (p < 0.05), and the plasma levels of liver enzymes returned earlier to the normal range in rats pretreated with allopurinol in comparison to those that did not receive the drug (p < 0.05). Conclusions: Allopurinol exerted a protective effect on hepatic ischemia and reperfusion in rats. The administration of this drug prior to liver operations should be considered to be submitted to trials in humans.

Profilaxia antimicrobiana em cirurgia vascular periférica: cefalosporina ainda é o padrão-ouro?

In peripheral vascular surgery, cephalosporins are nowadays regarded as the first choice for operative antibiotic prophylaxis. We have recently observed changes in colonizing patterns, pathogen prevalence and antibiotic susceptibility to antimicrobials. Multiresistant pathogens are becoming more frequent in vascular surgical wound infections, showing regional and local variations as to prophylactic antibiotic susceptibility. Data from the available literature so far have shown no strong evidence for a change in routine surgical antibiotic prophylaxis. We must consider regional and institutional prevalence of pathogen resistance and patterns of antibiotic susceptibility to establish specific guidelines for the use of alternative antibiotics.

Análise crítica das indicações e resultados do tratamento cirúrgico da doença carotídea

Treatment of carotid disease has been in focus over the past years, especially with the advent of the endovascular technique, which supports use of carotid angioplasty and stenting (CAS) in “high-risk” patients for carotid endarterectomy (CAE). We analyzed current outcomes of the treatment for carotid disease using both techniques. Furthermore, we performed some comments based on data from the literature, particularly in high-risk patients. We conclude that, up to the present moment, there is no evidence and justification for large use of CAS in patients with carotid disease, even in high-risk patients, such as in octogenarians. However, we believe that CAS could be useful in the treatment of a small number of patients with carotid disease (less than 4%), such as those with hostile neck, previous cervical radiation and in some cases of high carotid stenosis. When performed using the required technical skills, CAE is still the best choice for patients with carotid disease.

Role of the L-Arginine/Nitric Oxide Pathway in Renal Ischaemia-reperfusion in Rats

OBJECTIVE To study the role of the L-arginine/nitric oxide (NO) pathway during renal ischaemia-reperfusion in rats. DESIGN Randomised experimental study. SETTING Teaching hospital, Brazil. ANIMALS 97 male Wistar rats randomly assigned to 4 groups for the assessment of renal dysfunction and to 6 groups for the assessment of the oxidative stress induced on renal cell membranes by ischaemia-reperfusion. INTERVENTIONS The animals underwent sham-operation or renal ischaemia-reperfusion (n = 9 each) with or without pretreatment with L-arginine (a NO donor) or L-NAME (N(omega)-nitro-L-arginine methyl ester--an inhibitor of NO production) (n = 10 each). MAIN OUTCOME MEASURES Serum creatinine concentrations and oxidative stress by chemiluminescence initiated by the tert-butyl hydroperoxide technique. RESULTS Renal ischaemia-reperfusion significantly worsened renal dysfunction and increased oxidative stress in the ischaemia-reperfusion group after 24 and 96 hours of reperfusion compared with the control group (p < 0.05). Pretreatment with L-NAME slightly but not significantly increased serum creatinine concentrations after 24 and 96 hours of reperfusion together with activity of reactive oxygen species during renal ischaemia-reperfusion. L-arginine also significantly protected renal function and reduced the increment in the amount of chemiluminescence induced by giving L-NAME during 24 and 96 hours of reperfusion (p < 0.05). CONCLUSION The L-arginine/NO pathway seems to have a slightly protective effect on the kidney after renal ischaemia-reperfusion injury in rats. These results need to be confirmed by studies in human beings.

Tratamento cirúrgico dos aneurismas da aorta abdominal: existe diferença dos resultados entre homens e mulheres?

OBJECTIVE: To evaluate perioperative results in patients submitted to elective conventional open repair of abdominal aortic aneurysm, comparing the results between women and men in relation to perioperative mortality and morbidity, as well as long term outcomes. PATIENTES AND METHODS: Between December 1983 and December 2003, 675 patients were submitted to infrarenal abdominal aortic aneurysm repair. We divided these patients into two groups: men (n = 575) and women (n = 100). Demographic and operative data, as well as perioperative outcomes were obtained from chart review. Discharged patients formed a retrospective cohort, in which the late causes of death and survival were evaluated. RESULTS: The mean age was similar, but no statistical difference was observed between men and women (68.9 ± 9.1 versus. 67.4 ± 7.1 years; P = 0.089). The presence of hypertension was significantly higher in women (73 versus 62.4%; P = 0.042), and coronary artery disease and history of smoking were more prevalent in men (P <0.05). The overall mortality rate was 2.8%, without any significant difference between women and men (4 versus 2.6%, respectively; P = 0.43). Perioperative morbidity was similar in both groups (14% for women; 18.4% for men; P 0.05). The survival rates in 1, 3, 5, and 10 years were similar in the groups, with a 5-year survival of 71% for women and 72% for men (P 0.05). Cardiovascular disease was the main late death cause in both groups, followed by renal complications in women and neoplasia in men. CONCLUSION: Perioperative mortality and morbidity rates did not significantly increase in women after conventional infrarenal abdominal aortic aneurysm repair. Furthermore, long term results were similar in both genders.

A endarterectomia carotídea é a melhor opção para os pacientes com doença carotídea

The good long term outcome of carotid endarterectomy (CE) was recognized for the first time after publication of the seminal study by Prof. DeBakey in 19751. Since then, CE has been one of the most analyzed and investigated vascular surgical procedures. In the beginning of the 1990s, the results and surgical indications for carotid disease were well established for symptomatic patients with the publication of NASCET (North American Symptomatic Carotid Endarterectomy Trial) and ECST (European Carotid Surgery Trial) in 1991 and for asymptomatic patients, with ACAS (Executive Committee for the Asymptomatic Carotid Atherosclerosis Study) in 19942-4.

Acompanhamento de um modelo de indução de cirrose em ratos mediante vídeolaparoscopia

The authors present a model of experimental videolaparoscopy to evaluate the hepatotoxicity induced by carbon tetrachloride (CCl4) in rats. Nodules in hepatic surface and significative increase of hepatobiliar function tests (alanine aminotransferase, aspartate aminotransferase, alkaline phosphastase, and gammaglutamyltranspeptidase) were observed in rats treated with CCl4. Furthermore, liver cirrhosis was diagnosed by histopathologic study in all rats submitted to administration of CCl4. In this manner, experimental videolaparoscopy in rats seems be a excelent diagnostic method that merits further investigation to explore the physiologic consequences of laparoscopic surgery.

Taxa de mortalidade em ratos submetidos à isquemia e reperfusão hepática, tratados ou não com alopurinol

A isquemia transitoria hepatica tem sido cada vez mais amplamente utilizada. Contudo, essa atitude, embora muitas vezes benefica, e contrabalancada pelos efeitos adversos advindos da isquemia hepatica e da congestao esplenica, assim como, das consequencias da reperfusao. O objetivo dos autores e determinar os efeitos da isquemia seletiva em animais pre-tratados ou nao com alopurinol, inibidor da xantina oxidase sobre a mortalidade dos animais. Foram utilizados 30 ratos assim divididos: Grupo I (n=10): pre-tratados com alopurinol e submetidos a laparotomia e exposicao do pediculo hepatico por 45 minutos. Grupo II (n=10): tratados com alopurinol e submetidos a isquemia hepatica seletiva por 45 minutos. Grupo III (n=10): submetidos apenas a isquemia por 45 minutos. A mortalidade pos-operatoria foi avaliada a cada 24 horas, por um periodo de 10 dias. Entre os animais do grupo I, nao foram observados obitos, entretanto, naqueles dos grupos II e III, as mortalidades globais foram respectivamente 20 e 46,7%. Diferenca estatisticamente significativa, apenas, entre a mortalidade observada no grupo III em relacao ao controle (p<0,05). A mortalidade pos-operatoria no grupo de animais submetidos a isquemia sem pre-tratamento com alopurinol ascende as cifras de 46,67% dos animais, enquanto naqueles pre-tratados com alopurinol houve um importante decrescimo para 20%. Embora sem uma distincao estatisticamente significativa, reflete uma tendencia de um efeito protetor do alopurinol na isquemia e reperfusao hepatica.