Effects of Chronic Exposure to Mercury on Angiotensin-Converting Enzyme Activity and Oxidative Stress in Normotensive and Hypertensive Rats / Efeitos da Exposição Crônica ao Mercúrio sobre a Atividade da Enzima Conversora de Angiotensina e Estresse Oxidativo em Ratos Normotensos e Hipertensos

Abstract Background: Mercury's deleterious effects are associated with increased cardiovascular risk. Objective: To determine whether chronic exposure to inorganic mercury increases the activity of angiotensin-converting enzyme and its relationship with oxidative stress in several organs and tissues. Methods: We studied male Wistar and spontaneously hypertensive rats (SHR) (3-month-old) exposed or not to HgCl2 for 30 days. At the end of treatment, we investigated the following: changes in body weight, hemodynamic parameters, angiotensin-converting enzyme (ACE) activity and oxidative stress in the heart, aorta, lung, brain and kidney in hypertensive compared to normotensive animals. A value of p < 0.05 was considered significant. Results: Chronic exposure to HgCl2 did not affect weight gain in either group. Systolic blood pressure, measured weekly, did not increase in Wistar rats but showed a small increase in SHR rats. We also observed increases in left ventricular end-diastolic pressure and ACE activity in the plasma and hearts of normotensive rats. In the SHR+Hg group, ACE activity increased in plasma but decreased in kidney, lung, heart, brain and aorta. Oxidative stress was assessed indirectly by malondialdehyde (MDA) production, which increased in Hg-treated rats in both plasma and heart. In the SHR+Hg group, MDA increased in heart and aorta and decreased in lungs and brain. Conclusion: These results suggest that chronic exposure to inorganic mercury aggravates hypertension and produces more expressive changes in ACE activity and oxidative stress in SHRs. Such exposure affects the cardiovascular system, representing a risk factor for the development of cardiovascular disorders in normotensive rats and worsening of pre-existing risks for hypertension.

Resumo Fundamento: Os efeitos deletérios do mercúrio estão associados ao risco cardiovascular aumentado. Objetivo: Determinar se a exposição crônica ao mercúrio inorgânico aumenta a atividade da enzima conversora de angiotensina e sua relação com o estresse oxidativo em vários órgãos e tecidos. Métodos: Estudamos ratos Wistar e ratos espontaneamente hipertensos (SHR) (3 meses de idade) expostos ou não a HgCl2 por 30 dias. Ao final do tratamento, investigamos: alterações de peso, parâmetros hemodinâmicos, atividade da enzima conversora de angiotensina (ECA) e estresse oxidativo no coração, aorta, pulmão, cérebro e rim de animais hipertensos comparados a animais normotensos. Um valor de p < 0,05 foi considerado significativo. Resultados: A exposição crônica ao HgCl2 não afetou o ganho de peso em nenhum dos grupos. A pressão arterial sistólica, medida semanalmente, não aumentou em ratos Wistar, mas mostrou um pequeno aumento nos ratos SHR. Também observamos aumentos na pressão diastólica final do ventrículo esquerdo e na atividade da ECA no plasma e no coração de ratos normotensos. No grupo SHR + Hg, a atividade da ECA aumentou no plasma, mas diminuiu no rim, pulmão, coração, cérebro e aorta. O estresse oxidativo foi avaliado indiretamente pela produção de MDA, que aumentou nos ratos tratados com Hg tanto no plasma quanto no coração. No grupo SHR + Hg, o MDA aumentou no coração e na aorta e diminuiu nos pulmões e no cérebro. Conclusão: Estes resultados sugerem que a exposição crônica ao mercúrio inorgânico agrava a hipertensão e produz mudanças mais expressivas na atividade da ECA e no estresse oxidativo em SHRs. Essa exposição afeta o sistema cardiovascular, representando um fator de risco para o desenvolvimento de distúrbios cardiovasculares em ratos normotensos e para piorar riscos pré-existentes para hipertensão.

Effects of propofol pretreatment on lung morphology and heme oxygenase-1 expression in oleic acid-induced acute lung injury in rats

Abstract Purpose: To investigate the effects of propofol pretreatment on lung morphology and heme oxygenase-1 expression in oleic acid -induced acute lung injury in rats. Methods: A total of 32 male Sprague-Dawley rats (250-300g) were randomly divided into the following four groups (n=8/group): group C, group OA, group OA+PR, and group OA+IX to compare related parameter changes. Results: PaO2, PCO2, and PaO2/FiO2 were significantly different among the four treatment groups (P<0.05 or P<0.01). Lung wet/dry weight ratio and HO-1 protein expression also significantly differed among the groups (P<0.01). Immunohistochemistry showed that the expression of HO-1 in group OA+PR was stronger than those in groups OA, OA+IX, and C. Light microscopy revealed that pathological changes in lung tissues in group OA+PR were milder than those in group OA and group OA+IX. Electron microscopy showed that alveolar type II epithelial cell ultrastructure in group OA was relatively irregular with cell degeneration and disintegration and cytoplasmic lamellar bodies were vacuolized. Changes in group OA+PR were milder than those in group OA; however, they were more severe in group OA+IX than in group OA. Conclusion: Propofol significantly increases the expression of HO-1 in the lung tissueand prevents changes in lung morphology due to ALI in rats.

Effect of gold nanoparticles on superoxide dismutase and indoleamine 2, 3-dioxygenase in various rat tissues.

Gold nanoparticles have diverse applications and are being used in food and cosmetic industry, for drug delivery and in the diagnosis and treatment of cancer. However there is a need to study their biochemical mode of action. In this study, in vivo effect of gold nanoparticles on the activities of the two antioxidant enzymes — superoxide dismutase (SOD) and indoleamine 2,3-dioxygenase (IDO) was investigated in various tissues of rats. Rats were injected with 20 μg/kg body wt of 20 nm gold nanoparticles for three consecutive days through intraperitoneal route. The animals were sacrificed by CO2 asphyxiation 24 h after the last dose of gold nanoparticles. Results showed that treatment with gold nanoparticles caused no significant change in SOD activity in most of the tissues, except kidneys. In kidneys, gold nanoparticles caused a significant increase in SOD activity, when compared to the activity in control rats. However, treatment with gold nanoparticles altered the expression pattern of SOD activity in various tissues. For example, in control rats highest SOD activity was demonstrated in heart and least in kidneys and spleen. But, in gold nanoparticles treated rats, maximum SOD activity was observed in liver and the lowest in spleen. Gold nanoparticles caused no significant change in IDO activity in the studied tissues.

Proposta de um modelo murino de curta duração de resposta pulmonar alérgica aguda sem utilização de adjuvante / Proposed short-term model of acute allergic response, without adjuvant use, in the lungs of mice

OBJETIVO: Determinar se um protocolo curto de sensibilização com ovalbumina subcutânea, sem adjuvante, induziria uma resposta pulmonar eosinofílica em pulmões de camundongos similar àquela encontrada em protocolos previamente estabelecidos. MÉTODOS: Fêmeas adultas de camundongos BALB/c foram randomizadas e divididas em grupos de acordo com o número de sensibilizações com ovalbumina e o número/dosagem de provocação intranasal. O protocolo curto (10 dias) consistiu de uma sensibilização e três provocações com ovalbumina (100 µg). A contagem total e diferencial de células no lavado broncoalveolar, o nível de peroxidase eosinofílica no tecido pulmonar e o exame histopatológico dos pulmões foram realizados 24 h após a última provocação. RESULTADOS: Não houve diferenças significativas entre os grupos em relação às variáveis estudadas. O protocolo curto, assim como os outros protocolos estudados, induziu uma resposta eosinofílica pulmonar semelhante àquela do grupo controle positivo. CONCLUSÕES: A sensibilização por ovalbumina subcutânea sem o uso de adjuvante resultou em uma significativa resposta pulmonar alérgica em ratos, mesmo no grupo de protocolo curto. Nossos achados sugerem que esse protocolo curto pode ser utilizado como teste pré-clínico de primeira linha para a pesquisa de novos fármacos, reduzindo custos e o tempo de observação.

OBJECTIVE: To determine whether a short-term protocol using subcutaneous sensitization with ovalbumin, without the use of adjuvants, would induce an eosinophilic response in the lungs of mice similar to that observed in previous, well-established protocols. METHODS: Adult female BALB/c mice were randomized and divided into groups according to the number of sensitizations with ovalbumin and the number/dosage of intranasal ovalbumin challenges. The short-term protocol (10 days) consisted of one sensitization with ovalbumin and three ovalbumin challenges (100 µg). Total and differential cell counts in BAL fluid, levels of eosinophil peroxidase in lung tissue, and histopathological examination of the lungs were performed 24 h after the last ovalbumin challenge. RESULTS: No significant differences were found among the groups regarding the variables studied. The short-term protocol, as well as the other protocols studied, induced an eosinophilic response similar to that obtained in the positive control. CONCLUSIONS: Subcutaneous sensitization with ovalbumin and without the use of adjuvants resulted in a significant allergic response in the lungs of mice, even in the short-term protocol group. Our findings suggest that this short-term protocol can be used as a first-line pre-clinical test for the study of new medications, reducing the costs and observation periods.

Atividade da catalase no pulmão, rim e intestino delgado não isquemiado de ratos após reperfusão intestinal / Catalase activity in lung, kidney and small bowel non-ischemic in rats after intestinal reperfusion

OBJETIVO: Avaliar a atividade catalase, após lesão por isquemia e reperfusão intestinal e estudar as alterações deste antioxidante em órgãos situados à distância do insulto inicial. MÉTODOS: Utilizaram-se 18 ratos do tipo Wistar, aleatoriamente distribuídos em três grupos. 1-Controle, 2-Simulação e 3-Isquemia/Reperfusão. Neste último, realizou-se isquemia no íleo, por 60 minutos, seguida de reperfusão por 30 minutos. No grupo 2 efetuou-se apenas uma laparotomia. Foram retirados, de todos os animais, segmentos do intestino com e sem reperfusão, além do pulmão e rim direitos para exame com microscopia óptica. A atividade da catalase foi aferida em espectrofotômetro ajustado para 240 nm. Utilizaram-se os testes estatísticos Mann e Whitney e Kruskal Wallis. RESULTADOS: Observou-se aumento significante (p < 0.05), da atividade da catalase nas porções do intestino isquemiado e não isquemiado, além do pulmão. Houve redução da atividade enzimática no rim. No grupo com reperfusão observaram-se alteração nas vilosidades, infiltrado inflamatório em todas as vísceras, além de áreas de atelectasia pulmonar. CONCLUSÃO: O estresse oxidativo intestinal, em ratos, causa alterações bioquímicas à distância com mobilização dos mecanismos de defesa antioxidante pulmonar, em segmento intestinal não isquemiado e no rim, com esgotamento precoce das reservas deste último, no entanto, sem lesão celular relevante, destas vísceras.

OBJECTIVE: This study aimed to assess the catalase activity after ischemia and reperfusion and to study the changes of this antioxidant in organs located far from the initial insult. METHODS: Eighteen Wistar rats were randomly divided into three groups. 1-Control, 2-Simulation and 3-Ischemia and Reperrfusion. In the latter it was done an ischemia of the ileum for 60 minutes followed by reperfusion for 30 minutes. In group 2 only laparotomy was performed. From all animals it was taken segments of the reperfused and non reperfused intestine, as well of the right kidney and lung to be evaluated under light microscopy. Catalase activity was measured in spectrophotometer with a wavelength set to 240 nm. It was used Mann Whitney and Kruskal Wallis statistical tests. RESULTS: There was a significant increase (p <0.05) in the catalase activity not only at small bowel ischemic and non-ischemic segments but also at lungs. However the enzymatic activity decreases in the kidney. In all organs studied at reperfusion group it was found a slight villi derangement, mild congestion and infiltration with inflammatory cells, and areas of pulmonary atelectasis. CONCLUSION: The intestinal oxidative stress in rats causes biochemical changes at distance, with mobilization of antioxidant defense mechanisms in lung, non-ischemic intestinal segment and kidney, with early decrease in this last organ, however, with no relevant cellular damage.

Long term dietary restriction ameliorates swimming exercise-induced oxidative stress in brain and lung of middle-aged rat.

Exhaustive exercise may generate oxidative stress in brain and reported findings are conflicting. Long term dietary restriction (DR) may be useful in the inhibiting of free oxygen radicals generated during exhaustive exercise in the brain of rat. Hence, in this study we evaluated beneficial effects of long term DR on the oxidative stress and antioxidant enzyme systems in brain cortex and lung in rats after different intensities of swimming exercise. Sprague-Dawley rats (60) were assigned as DR and ad libitum (AL) groups, and each group was further subdivided into three groups namely control (sedentery), submaximal exercise (endurance exercise) and maximal exercise (exhaustive swimming exercise) groups. Animals in the endurance exercise group swam 5 days/week for 8 weeks while exhaustive swimming group was subjected to an acute bout of exercise. With the increase in intensity of exercise, degree of lipid peroxidation (LP) and protein oxidation (PO) were also increased in DR and AL groups; however rate of increase was lower in DR group than AL group. Glutathione (GSH) and glutathione peroxidase (GSH-Px) activity were lower but glutathione reductase (GR) activity was higher in DR group compared to AL group in endurance and exhaustive swimming exercise. With increase in exercise intensity, GSH and GR enzyme activity decreased, whereas an increase was observed in GSH-Px enzyme activity. There was no difference in LP, PO, GSH and GR activity between DR and AL groups. GSH-Px activity in brain cortex was significantly lower in DR group than in AL group and sedentary rats. Results indicate that long term dietary restriction may protect against endurance and exhaustive swimming exercise-induced oxidative stress in rats by inhibiting oxidative stress.

Magnitud del enfisema inducido por elastasa: posible relación con el tipo de daño agudo pulmonar / Elastase induced emphysema: possible relationship with the type of acute lung injury

Introduction: Intratracheal instillation of elastase induces diffuse alveolar damage and emphysema development. However, the Syrian Golden hamster develops more severe emphysema than the Sprague-Dawley rat. Although it is known that early events after elastase instillation determine the magnitude of emphysema development, it is not known if there are species differences in the initial pattern of lung response to elastase. Objective: To evaluate whether rats and hamster differ in the early lung response to elastase, using biochemical markers of acute lung injury. Results: Whereas the rat shows a large increase in alveolar-capillary permeability and few hemorrhagic changes, the hamster shows significant amount of hemorrhage and a small increase in alveolar capillary permeability. Conclusions: There are differences between rats and hamsters in the initial lung response to elastase that could influence the magnitude of emphysema development.

Introducción: El modelo de instilación intratraqueal de elastasa induce daño alveolar difuso y destrucción de la matriz extracelular con desarrollo de enfisema. Sin embargo, el hámster Syrian Golden desarrolla enfisema más severo que el de la rata Sprague-Dawley. Si bien se sabe que los eventos tempranos después de la instilación de elastasa determinan la magnitud del enfisema, se desconoce si existen diferencias entre especies en la respuesta pulmonar temprana. Objetivo: Evaluar si existen diferencias entre ratas y hamsters en la respuesta pulmonar inicial después de la elastasa, mediante el uso de marcadores bioquímicos de daño pulmonar agudo. Resultados: Mientras la rata experimenta un gran aumento de permeabilidad alvéolo-capilar y pocos fenómenos hemorrágicos, el hamster presenta abundante hemorragia y escaso aumento de la permeabilidad. Conclusiones: Existen diferencias entre ratas y hamsters en la respuesta pulmonar inicial frente a la elastasa, que podrían tener relación con las diferencias en magnitud del enfisema.

Atelectasis Induced by Thoracotomy Causes Lung Injury during Mechanical Ventilation in Endotoxemic Rats

Atelectasis can impair arterial oxygenation and decrease lung compliance. However, the effects of atelectasis on endotoxemic lungs during ventilation have not been well studied. We hypothesized that ventilation at low volumes below functional residual capacity (FRC) would accentuate lung injury in lipopolysaccharide (LPS)-pretreated rats. LPS-pretreated rats were ventilated with room air at 85 breaths/min for 2 hr at a tidal volume of 10 mL/kg with or without thoracotomy. Positive end-expiratory pressure (PEEP) was applied to restore FRC in the thoracotomy group. While LPS or thoracotomy alone did not cause significant injury, the combination of endotoxemia and thoracotomy caused significant hypoxemia and hypercapnia. The injury was observed along with a marked accumulation of inflammatory cells in the interstitium of the lungs, predominantly comprising neutrophils and mononuclear cells. Immunohistochemistry showed increased inducible nitric oxide synthase (iNOS) expression in mononuclear cells accumulated in the interstitium in the injury group. Pretreatment with PEEP or an iNOS inhibitor (1400 W) attenuated hypoxemia, hypercapnia, and the accumulation of inflammatory cells in the lung. In conclusion, the data suggest that atelectasis induced by thoracotomy causes lung injury during mechanical ventilation in endotoxemic rats through iNOS expression.

Inducible nitric oxide synthase (iNOS): role in asthma pathogenesis.

Asthma is one of the most common chronic inflammatory disorder of the airways of the lungs, affecting more than 300 million people all over the world. Nitric oxide (NO) is endogenously produced in mammalian airways by nitric oxide synthase (NOS) and is known to regulate many aspects of human asthma, including the modulation of airway and vascular smooth muscle tone and the inflammation. Asthmatic patients show an increased expression of inducible nitric oxide synthase (iNOS) in airway epithelial cells and an increased level of NO in exhaled air. Using various NO inhibitors (non-specific or iNOS-specific) and gene knock-out experiments, controversial results have been obtained regarding iNOS's beneficial and deleterious effects in the disease. In the present review, we have attempted to summarize the results of these experiments and also the genetic studies being undertaken to understand the role of iNOS in asthma. It is argued that extensive biochemical, clinical and genetic studies will be required to assess the precise role of NO in the asthma. This may help in designing selective and more potent iNOS inhibitors and NO donors for developing novel therapeutics for the asthma patients.

Metabolismo del glutatión y desarrollo posnatal del pulmón de la rata / Glutathione metabolism during postnatal development of the rat lung

Background: Significant changes in lung antioxidants occur in preparation for birth. Little is known about physiological regulation of antioxidants in the postnatal period. Aim: To study the glutathione system in the lungs during postnatal development. Material and methods: In the lungs of 7, 15, 21, 50 and 70 days old Sprague-Dawley rats we measured total and oxidized glutathione content as well as the activity of the limiting enzyme in glutathione synthesis (y-GCS) and of the enzymes glutathione peroxidase (GPx) and glutathione reducíase (GRd). Results: Between 7 and 15 days the activities of GPx and GRd increase 32 percent and 26 percent, respectively (p <0.001). Whereas GPx activity remains high throughout the rest of the study period, GRd activity decreases progressively reaching adulthood values at 7 days. y-GCS activity shows a gradual increase that reaches significance at 50 days when it doubles values observed at 7 days (p <0.05). A significant correlation was found between GPx and GRd activities over the entire period (r =0.62, p <0.0001). Strength of the correlation is age dependent due to the differences in time course of the enzyme changes. Whereas total GSH does not change, oxidized glutathione decreases from 7 percent at 7 and 15 days to 4 percent later on (p <0.01). Conclusions: The activity of several enzymes involved in glutathione metabolism increases during postnatal development of the rat lung. Interpretation of lung responses to injurious agents needs to be done taking into consideration the physiological regulation of antioxidants during postnatal development.

Macrophage elastase (MMP-12): a pro-inflammatory mediator?

As many metalloproteinases (MMPs), macrophage elastase (MMP-12) is able to degrade extracellular matrix components such as elastin and is involved in tissue remodeling processes. Studies using animal models of acute and chronic pulmonary inflammatory diseases, such as pulmonary fibrosis and chronic obstrutive pulmonary disease (COPD), have given evidences that MMP-12 is an important mediator of the pathogenesis of these diseases. However, as very few data regarding the direct involvement of MMP-12 in inflammatory process in the airways were available, we have instilled a recombinant form of human MMP-12 (rhMMP-12) in mouse airways. Hence, we have demonstrated that this instillation induced a severe inflammatory cell recruitment characterized by an early accumulation of neutrophils correlated with an increase in proinflammatory cytokines and in gelatinases and then by a relatively stable recruitment of macrophages in the lungs over a period of ten days. Another recent study suggests that resident alveolar macrophages and recruited neutrophils are not involved in the delayed macrophage recruitment. However, epithelial cells could be one of the main targets of rhMMP-12 in our model. We have also reported that a corticoid, dexamethasone, phosphodiesterase 4 inhibitor, rolipram and a non-selective MMP inhibitor, marimastat could reverse some of these inflammatory events. These data indicate that our rhMMP-12 model could mimic some of the inflammatory features observed in COPD patients and could be used for the pharmacological evaluation of new anti-inflammatory treatment. In this review, data demonstrating the involvement of MMP-12 in the pathogenesis of pulmonary fibrosis and COPD as well as our data showing a pro-inflammatory role for MMP-12 in mouse airways will be summarized.

Differential Effect of gamma-radiation-induced Heme Oxygenase-1 Activity in Female and Male C57BL/6 Mice

Ionizing radiation produces reactive oxygen species, which exert diverse biological effects on cells and animals. We investigated alterations of heme oxygenase (HO) and non-protein thiols (NPSH), which are known as two major anti-oxidant enzymes, in female and male C57BL/6 mice in the lung, liver, and brain after whole-body gamma-irradiation with 10 Gy (1-7 days) as well as in the lung after whole-thorax gamma-irradiation (WTI) with 12.5 Gy (1-26 weeks). Most significant alteration of HO activity was observed in the liver, which elevated 250% in males. NPSH level in female liver was increased on the 5th-7th days but decreased in males on the 3rd day. In the lung, the elevation of HO activity in both sexes and the pattern of NPSH change were similar to that of the liver. On the other hand, the increase of HO activity on the 16th week and the decrease of NPSH level on the 2nd week were observed only in male lung after WTI. This study shows that the liver is the most sensitive tissue to gamma-irradiation-induced alterations of HO activity in both female and male mice. In addition, there exists significant differential effect of gamma-irradiation on anti-oxidant system in female and male mice.

Induction of inflammatory cell accumulation using human mast cell tryptases.

The aim of this study was to investigate the effects of human tryptases on inflammatory cell accumulation in vivo. Various concentrations of purified lung or skin tryptases were injected into the peritoneum of BALB/c mouse. At 6 hours or 16 hours following injection, cells from the peritoneal lavage were collected and stained with modified Wright's stain. Differential cell counts were performed and results were expressed as absolute numbers of each cell type per mouse peritoneum. The results showed a dose-dependent infiltration of neutrophils with a maximal increase of up to 32 fold or 43 fold in numbers at 16 hours following an injection of skin and lung tryptases, respectively. Skin tryptase was able to attract more eosinophils than lung tryptase. Significant increases in lymphocyte and macrophage numbers were also observed. In conclusion, both skin and lung tryptases are able to induce nucleated cell accumulation in the peritoneum of mice with similar specificity and potency.

Lung Matrix Metalloproteinase-9 Correlates with Cigarette Smoking and Obstruction of Airflow

Cigarette smoking is the most important risk factor for obstruction of airflow in chronic obstructive pulmonary disease (COPD). Matrix metalloproteinases (MMPs) or an imbalance between MMPs and their inhibitors, the tissue inhibitors of MMP (TIMPs), is considered to play a role in the pathogenesis of COPD. We investigated whether the MMPs expression or the imbalance between MMPs and TIMP-1 is associated with the amount of cigarette smoking and the FEV1 value, in the lung parenchyma of 26 subjects (6 non-smokers and 20 cigarette smokers). First, we performed zymographic analysis to identify the profile of the MMPs, which revealed gelatinolytic bands mainly equivalent to MMP-9 in the smokers. We then measured, using enzyme immunoassay, the concentrations of MMP-9 and its inhibitor, TIMP-1. Correlation analysis revealed that both the MMP-9 concentrations and the molar ratios of MMP-9 to TIMP-1 (MMP-9/TIMP-1) were correlated with the amount of cigarette smoking. Furthermore, MMP-9 concentrations were inversely correlated with FEV1. In conclusion, this study shows that MMP-9 expression in human lung parenchyma is associated with cigarette smoking and also with the obstruction of airflow, suggesting that MMP-9 may play a role in the pathogenesis of the cigarette smoke-induced obstruction of airflow known as the characteristic of COPD.

Effect of thyroid hormone on the alcohol dehydrogenase activities in rat tissues

The effects of thyroid hormone on hepatic and gastric alcohol dehydrogenase (ADH) activities (nM of NADH/min/mg of cytosolic protein) have been investigated in male Sprague Dawley rats treated with thyroxine (1 mg/kg, po) for 14 days. Whereas hepatic ADH activity in thyroxine-treated rats decreased by 61.3% of control rats (26.4 vs 43.2, p<0.001), gastric ADH activity increased by 262.9% of control rats (4.9 vs 1.9, p<0.001). As for the activities of the lung and kidney, thyroxine treatment did not produce any statistically significant changes. These data suggest that thyrotoxicosis causes a decrease of hepatic alcohol metabolism, and that the increase of gastric ADH activity in thyrotoxic rats can partly restore the first-pass metabolism of ethanol.

Diagnosis of tuberculous pleural effusion.

Tuberculosis is a common cause of pleural effusion in India. Diagnosis can be made in a majority of patients from the clinical features, pleural fluid examination (including cytology, biochemistry and bacteriology), and pleural biopsy. Adenosine deaminase estimation in pleural fluid is occasionally useful. Newer diagnostic techniques include lysozyme or interferon gamma estimation, immunodiagnostic methods and polymerase chain reaction. Although promising, they still need to be studied further before their routine use can be recommended.

Superóxido dismutasa, glutatión y malonaldehído en las soluciónes de perfusión y reperfusión pulmonar: estudio experimental murino / Superoxido dismutase, glutathoine and malonaldehide in pulmonary perfusión and reperfusión: Murine experimental study

Introducción: Las especies oxidantes son producto del metabolismo del oxígeno molecular, están reguladas por acción de receptores como la enzima superóxido dismutasa (SOD) y el glutation (GLU). Estos radicales oxidantes pueden generarse durante el periodo de isquemia-reperfusión ocasionando peroxidación lipídica, el malonaldehído (MAL) es un producto de este mecanismo de daño celular. Objetivo: Utilizando un modelo experimental murino de perfusión in situ y reperfusión ex vivo a través del ventrículo derecho, fue evaluada la actividad de SOD, y las concentraciones de GLU y MAL en las soluciones de perfusión y de reperfusión pulmonar recolectadas a través de un catéter colocado en la ventrículo izquierdo, antes y después de preservar el bloque pulmonar durante 24 h a 4ºC en solución de Krebs-Henseleit (KH). Material y métodos: 14 ratones de la cepa Balb-c fueron divididos en dos grupos de estudio. Grupo 1 (n = 7): El bloque pulmonar se perfundió con solución KH únicamente durante el tiempo necesario para exanguinarlo; Grupo 2 (n = 7): Al igual que el Grupo 1, el bloque pulmonar se perfundió con solución KH para exanguinarlo, inmediatamente después se sumergió en solución KH durante 24 h a 4ºC, transcurrido el tiempo de isquemia, el bloque fue reperfundido con solución KH durate 24 H a 4ºC, transcurrido el tiempo de isquemia, el bloque fue reperfundido con solución KH durante 30'. Utilizando estuches comerciales y espectrofotometría, se determinó la actividad de la enzima SOD y las concentraciones de GLU y MAL en las soluciones de perfusión y de reperfusión recolectadas. Resultados: No fueron encontradas diferencias en la actividad de SOD y en las concentraciones de GLU y MAL, obtenidas al exanguinar los bloques en los grupos de estudio 1 y 2. Los tres parámetros evaluados fueron mayores en la solución de perfusión obtenida al exanguinar los bloques antes de preservarlos y disminuyeron significativamente en la solución de reperfusión obtenida post-preservación pulmonar

Inhibition of angiotensin converting enzyme from sheep tissues by captopril, lisinopril and enalapril.

Inhibition of angiotensin converting enzyme(EC 3.4,15.1, ACE) in presence of captopril, lisinopril and enalapril were investigated in kidney, lung and serum of sheep using Hip-His-Leu(HHL) as substrate. The activity in kidney, lung and serum was inhibited at HHL concentration above 5 mM. The inhibitory constants (IC50) ranged between 5.6 nM for serum ACE with lisinopril and 70000 nM for renal ACE with enalapril while Ki ranged from 1.0 nM for serum ACE with lisinopril to 12000 nM for kidney ACE with enalapril. Differences in inhibition observed in different tissues suggest that the inhibitors may block function(s) of ACE to varying degrees in each tissue.