O. Castro e Silva

Possibility for a full optical determination of photodynamic therapy outcome

The efficacy of photodynamic therapy (PDT) depends on a variety of parameters: concentration of the photosensitizer at the time of treatment, light wavelength, fluence, fluence rate, availability of oxygen within the illuminated volume, and light distribution in the tissue. Dosimetry in PDT requires the congregation of adequate amounts of light, drug, and tissue oxygen. The adequate dosimetry should be able to predict the extension of the tissue damage. Photosensitizer photobleaching rate depends on the availability of molecular oxygen in the tissue. Based on photosensitizers photobleaching models, high photobleaching has to be associated with high production of singlet oxygen and therefore with higher photodynamic action, resulting in a greater depth of necrosis. The purpose of this work is to show a possible correlation between depth of necrosis and the in vivo photosensitizer (in this case, Photogem®) photodegradation during PDT. Such correlation allows possibilities for the development of a real time ...

Can efficiency of the photosensitizer be predicted by its photostability in solution

We have investigated a possible correlation between the photostability and photodynamic efficacy for different photosensitizers; hematoporphyrin derivatives and chlorines. To perform such analysis, we combined the depth of necrosis (dnec) measurement, expressed by the light threshold dose and a photodegradation parameter, measured from investigation of photosensitizer degradation in solution. The dnec analysis allows us to determine the light threshold dose and compare its value with the existent results in the literature. The use of simple models to understand basic features of Photodynamic Therapy (PDT) may contribute to the solid establishment of dosimetry in PDT, enhancing its use in the clinical management of cancers and others lesions. Using hematoporphyrin derivatives and chlorines photosensitizers we investigated their properties related to the photodegradation in solution and the light threshold dose (Dth) in rat livers.

Effect of methylene blue on the hemodynamic instability resulting from liver ischemia and reperfusion in rabbits.

The experimental investigation was performed to study the effects of methylene blue (MB) on hemodynamic, biochemical, and tissue changes among rabbits undergoing liver ischemia and reperfusion (IR). Twenty-four rabbits were randomized into 5 groups: 1, SHAM, control; 2, MB infusion bolus (3 mg/kg); 3, IR, hepatic ischemia for 60 minutes followed by 120 minutes of reperfusion; 4, MB-R, undergoing ischemia that had received an MB bolus infusion (3 mg/kg) prior to reperfusion; 5, R-MB, undergoing ischemia and MB bolus infusion after hemodynamic instability caused by reperfusion. The analysis included continuous recording of vital signs. Blood samples were collected at 0, 60, and 180 minutes of IR to determine blood gases as well as biochemical markers of liver function, nitric oxide, lipid peroxidation, and neutrophil activity. At the end of each experiment, liver tissue samples were collected for histological evaluation of parenchymae markers. Statistical analysis used two-way analysis of variance (ANOVA) tests with significance set at P<.05. Vital signs significantly improved with MB infusion, irrespective of whether it was applied before or after reperfusion. Blood gas data revealed different patterns among the SHAM, MB, IR, MB-R, and R-MB groups, without statistical significance, except for favorable lactate results in the R-MB group (P<.01), which displayed greater survival. Biochemical tests did not show significant differences among the groups, whereas histological analysis revealed favorable appearances for the MB-R and R-MB groups. The MB effect lasted long after reperfusion, suggesting that improvement in the hemodynamic parameters was not based on liver integrity, but rather was possibly related to endothelial function.

Evaluation of the Respiratory Muscle Strength of Cirrhotic Patients: Relationship With Child-Turcotte-Pugh Scoring System

Pulmonary abnormalities are observed in chronic hepatopathy. The measurement of the maximum inspiratory and expiratory pressure may evaluate lung function and the risks associated with hepatic transplantation. Thus, the present work sought to evaluate the respiratory muscle strength of 29 patients between 17 and 63 years old who were enrolled for liver transplantation. The patients were classified according to Child-Turcotte-Pugh score as A, B, or C, and also according to a physiotherapeutic evaluation, which included measurement of respiratory muscle strength by means of a digital manovacuometer, which determines the maximum inspiratory pressure (MaxIP) and the maximum expiratory pressure (MaxEP). The tests were performed with seated individuals having their nostrils obstructed by a nasal clip. The MaxIP was measured during the effort initiated in the residual volume, whereas the MaxEP was measured during the effort initiated in the total pulmonary capacity, keeping pressures stable for at least 1 second. The statistical analysis was performed through using the Mann-Whitney test with a 5% level of significance. The MaxIP values of Child A 95.5 +/- 40.507 cm H(2)O (average +/- DP) and Child B 87.2 +/- 35.02 patients were higher than those for Child C patients (34.83 +/- 3.68; P < .05). Similar results were observed for the MaxEP of Child A and B groups (116.25 +/- 31.98 and 97.28 +/- 31.08, respectively; P < .05), versus the Child C group (48.16 +/- 22.60). Between groups A and B, the MaxEP were similar (P > .05). We concluded that Child C patients display muscle weakness significantly greater than that of subjects classified as Child A or B.

EFEITOS DO PRÉ-CONDICIONAMENTO HEPÁTICO EM RATOS CIRRÓTICOS, SUBMETIDOS À ISQUEMIA E REPERFUSÃO HEPÁTICA RESULTADOS PRELIMINARES

We studied the influence of ischemic preconditioning in rat liver cirrhosis.The cirrhosis were induced in wistar rat with occlusion of biliary duct before 30 days operation and divided into group A, ischemic preconditioning and ischemic/reperfusion, and group B, only ischemic/reperfusion. In group A the preconditioning consisted of 5 min ischemic and 10 min reperfusion. The ischemic/reperfusion consisted of 20 min ischemic and 120 min reperfusion for both groups. The level of respiratory control reason (RCR) in the liver tissue 120 min after reperfusion was not difference significantly in the groups. Therefore it suggests that the preconditioning cam be viability and another object of studies must be rated in future this work.

EVOLUÇÃO DA FIBROSE BILIAR SECUNDÁRIA EM RATOS TRATADOS MEDIANTE DERIVAÇÃO BÍLIO-DUODENAL OU BÍLIO-JEJUNAL COM ALÇA DE ROUX MEDINDO 5, 10 E 15 CM

A modalidade de derivacao bilio-digestiva empregada no tratamento da colestase extra-hepatica cronica pode influenciar na reparacao das lesoes hepaticas. Avaliou-se o desempenho das derivacoes bilio-duodenal e bilio-jejunal em Y de Roux com alca exclusa de diferentes comprimentos na reparacao das lesoes morfologicas e funcionais do figado de ratos com fibrose biliar secundaria. Foram utilizados ratos Wistar, com 15 dias de obstrucao biliar, alocados em 5 grupos de 6 animais. O grupo OB caracterizou as alteracoes da fibrose biliar. Os animais remanescentes foram tratados mediante derivacao com o duodeno (grupo DBD), e com o jejuno, em alca exclusa de 5cm (grupo DBJ5), 10cm (grupo DBJ10) e 15cm (grupo DBJ15), sendo reavaliados 3 meses depois. Outros 6 animais foram submetidos a intervencao simulada e considerados grupo controle (IS). Todos animais foram submetidos a avaliacao morfometrica do figado, analise bioquimica do sangue e microbiologica da bile, estudo da funcao mitocondrial hepatica e verificacao do peso umido do figado e do baco. Na analise estatistica adotou-se o nivel de significância de 5%. Houve aumento significativo do peso estimado, em g/Kg de peso corporal, dos ductos biliares, da fibrose e dos hepatocitos nos animais do grupo OB (medianas de 1,30; 10,03 e 37,0) em relacao aos animais controles (IS) (medianas de 0,03; zero e 29,37). Apos tratamento, ocorreu regressao significativa do peso estimado dos ductos biliares e da fibrose, com valores medianos de 0,22 e 0,22 para o grupo DBD, 0,45 e 3,31 para o grupo DBJ5 e 0,22 e 5,0 para o grupo DBJ15. Houve regressao significativa do peso estimado dos hepatocitos apenas nos grupos derivados com o jejuno, com valores medianos de 31,93; 24,46 e 28,52. Ocorreu aumento significativo do peso umido do figado e do baco no grupo OB (medianas em g/Kg de peso corporal de 49,85 e 5,71) em relacao ao grupo IS (30,0 e 3,04). Houve regressao significativa do peso do figado em todos os tratamentos e do peso do baco nos animais tratados com derivacao bilio-jejunal, (valores medianos de 35,59 e 2,53 para DBJ5, 37,54 e 2,82 para DBJ10 e 32,73 e 2,93 para DBJ15). Apos o tratamento, surgiram infiltrado inflamatorio misto, nos espacos portais, refluxo enterobiliar e contaminacao bacteriana da bile. Houve aumento significativo no consumo de oxigenio pela mitocondrias hepaticas nos estados 3 e 4 no grupo OB (medianas de 101,55 e 31,05 nanoatomos de O2/mgprot./min), em relacao ao grupo IS (medianas de 57,22 e 15,51). Apos o tratamento, normalizou-se o consumo energetico apenas nos animais do grupo DBJ15 (medianas de 52,38 e 14,8). O desempenho da derivacao biilio-jejunal indica a importância de avaliar alternativas que possam minimizar o contato do conteudo enterico com a via biliar.

Brain caspase-3 and intestinal FABP responses in preterm and term rats submitted to birth asphyxia

Neonatal asphyxia can cause irreversible injury of multiple organs resulting in hypoxic-ischemic encephalopathy and necrotizing enterocolitis (NEC). This injury is dependent on time, severity, and gestational age, once the preterm babies need ventilator support. Our aim was to assess the different brain and intestinal effects of ischemia and reperfusion in neonate rats after birth anoxia and mechanical ventilation. Preterm and term neonates were divided into 8 subgroups (n=12/group): 1) preterm control (PTC), 2) preterm ventilated (PTV), 3) preterm asphyxiated (PTA), 4) preterm asphyxiated and ventilated (PTAV), 5) term control (TC), 6) term ventilated (TV), 7) term asphyxiated (TA), and 8) term asphyxiated and ventilated (TAV). We measured body, brain, and intestine weights and respective ratios [(BW), (BrW), (IW), (BrW/BW) and (IW/BW)]. Histology analysis and damage grading were performed in the brain (cortex/hippocampus) and intestine (jejunum/ileum) tissues, as well as immunohistochemistry analysis for caspase-3 and intestinal fatty acid-binding protein (I-FABP). IW was lower in the TA than in the other terms (P<0.05), and the IW/BW ratio was lower in the TA than in the TAV (P<0.005). PTA, PTAV and TA presented high levels of brain damage. In histological intestinal analysis, PTAV and TAV had higher scores than the other groups. Caspase-3 was higher in PTAV (cortex) and TA (cortex/hippocampus) (P<0.005). I-FABP was higher in PTAV (P<0.005) and TA (ileum) (P<0.05). I-FABP expression was increased in PTAV subgroup (P<0.0001). Brain and intestinal responses in neonatal rats caused by neonatal asphyxia, with or without mechanical ventilation, varied with gestational age, with increased expression of caspase-3 and I-FABP biomarkers.

Liver Mitochondrial Function in Familial Amyloidotic Polyneuropathy

The objective of the present study was to analyze hepatic mitochondrial function in patients with familial amyloidotic polyneuropathy (FAP) undergoing cadaveric donor orthotopic liver transplantation. From February 2005 to May 2007, eight patients with FAP, ranging in age from 34 to 41 years and with Model for End-Stage Liver Disease scores ranging from 24 to 29. Underwent orthotopic transplantation using a liver from a deceased donor by the piggyback method. Immediately before beginning the recipient hepatectomy in a patient with FAP, a biopsy was obtained for analysis of mitochondrial function (FAP group). The control group consisted of 15 patients undergoing hepatic surgery to treat small tumors of the liver. Mitochondrial respiration was determined on the basis of oxygen consumption by energized mitochondria using a polarographic method. The membrane potential of the mitochondria was determined spectrofluorometrically. Data were analyzed statistically by the Mann-Whitney test, with the level of significance set at 5%. State 3 and 4 values, respiratory control ratio, and membrane potential were 47 +/- 8 versus 28 +/- 10 natoms O/min/mg protein (P < .05); 14 +/- 3 vs 17 +/- 7 nat.O/min/mg.prot.mit. (P > .05); 3.6 +/- .5 vs 1.7 +/- 0.7 (P < .05); and 135 +/- 5.2 vs 135 +/- 6 mV (P > .05) for control versus FAP patients, respectively, demonstrating a decreased energy status of the liver in FAP.