Zooplankton assemblages in eutrophic reservoirs of the Brazilian semi-arid.

Species composition, density, and temporal dynamics of zooplankton were studied in six reservoirs in a semi-arid region in tropical northeastern Brazil (Rio Grande do Norte state). All the reservoirs are highly eutrophic, with high contents of total nitrogen (minimum of 1200 µg.L(-1)) and total phosphorus (minimum of 10 µg.L(-1)), and extremely high algal biomass was registered (surpassing 20 µg Chl a.L(-1)). All the reservoirs showed an enduring condition of high turbidity and phytoplankton assemblages dominated by cyanobacteria. Zooplankton also showed quantitative patterns suggestive of eutrophic conditions, expressed by high densities, mainly in Passagem das Traíras and Sabugi reservoirs. A spatial differentiation in the composition of the zooplankton community was registered. Rotifers (especially Keratella tropica, Brachionus havanensis, and Keratella americana) were the dominant forms in the zooplankton community of Itans, Passagem das Traíras, and Sabugi reservoirs, while calanoid copepods (mainly Notodiaptomus cearensis) dominated in the Armando Ribeiro, Gargalheiras, and Parelhas systems. The existence of novel relationships in zooplankton community composition in eutrophic reservoirs in this tropical semi-arid region must be considered in designating zooplankton indicators of eutrophic conditions.

Composition and abundance of zooplankton community of an impacted estuarine lagoon in Northeast Brazil.

Guaraíras Lagoon is a shallow coastal lagoon subject to intense human impacts, including shrimp aquaculture, urban expansion and agricultural activities, and is therefore vulnerable to eutrophication. With the aim of detecting the effects of human-mediated disturbance and environmental change in the lagoon, a spatial-temporal study was conducted in order to assess the actual ecological status of the lagoon and the species composition and density of the mesozooplankton, highlighting copepod assemblages. Algal biomass (chlorophyll-a) and total phosphorus concentration indicated that the lagoon is a meso-eutrophic coastal system in the inner part, and is oligotrophic in the areas influenced by the marine waters. High salinities were recorded in the lagoon, characterizing the lagoon as a coastal-marine ecosystem, rather than true estuarine. Mesozooplankton abundance fluctuated widely and showed marked spatial heterogeneity. The copepod assemblage was characterized by a coastal/estuarine group dominated by Oithona spp., Acartia lilljeborgi and Parvocalanus crassirostris in the inner areas of the lagoon, and a marine group characterized by the copepods Paracalanus quasimodo, Calanopia americana, Corycaeus (C.) speciosus and Monstrilloida in the area of marine influence. Thus, the spatial variability in the distribution of mesozooplankton species can be ascribed to the presence of a horizontal gradient of salinity and trophic conditions. Overall, the results showed that spatial variation in the water physicochemical characteristics of Guarairas Lagoon have significant effects on the structure and repartition of the mesozooplankton assemblages, which may potentially affect the functioning and biodiversity of this coastal ecosystem.

Rest and exercise hemodynamics after the Ross procedure: an echocardiographic study.

BACKGROUND: Aortic prosthetic valves with superior hemodynamic performance are associated with more complete regression of left ventricular hypertrophy and better left ventricular function postoperatively. The near normal function of the pulmonary autografts at rest is well documented, however, exercise data has been seldom reported. The purpose of this study is to evaluate the hemodynamic performance of pulmonary autografts in the aortic position and the homografts used to reconstruct the right ventricular outflow tract during conditions of high cardiac output by means of dobutamine stress echocardiography. METHODS: Between May 1995 and February 1998, 67 patients were submitted to a Ross operation at our institution. Twenty of these patients had a mean age of 28.6+/-8.3 years and a mean follow-up time of 15.7+/-5.9 months. They were studied by dobutamine stress echocardiography to evaluate rest and exercise hemodynamics of the pulmonary autografts as well as of the aortic and pulmonary homografts used to reconstruct the right ventricular outflow tract. Dobutamine infusion was started at 5 microg/kg with incremental doses up to 40 microg/kg in every case. RESULTS: With dobutamine infusion, heart rate increased from 71+/-10 to 142+/-11 beats/min, left ventricular systolic volume from 86.8+/-33.9 mL to 115.9+/-52.6 mL, and cardiac output from 6.3+/-2.9 L/min to 16.8+/-7.4 L/min. Left ventricular function was considered satisfactory at rest and during exercise in all patients. The mean gradient across the autograft increased from 1.03+/-0.95 mmHg to 4.03+/-2.05 mmHg and maximal instantaneous gradient from 2.45+/-2.21 mmHg to 9.54+/-4.85 mmHg. The mean effective orifice area for the autografts were 3.5+/-1.3 cm2 at rest and 3.3+/-1.4 cm2 during exercise. The patients with mild aortic insufficiency at rest had no increase in the degree of regurgitation with exercise. In the right ventricular outflow tract, the mean gradient across the homograft increased from 9.06+/-5.29 mmHg to 17.55+/-9.76 mmHg and maximal instantaneous gradient from 21.4+/-12.5 mmHg to 41.5+/-23.1 mmHg. CONCLUSIONS: Pulmonary autografts exhibit normal hemodynamic performance at rest and during exercise after the Ross operation. However, mild-to-moderate gradients are common at the right ventricular outflow tract and should be carefully monitored.

Substituição da valva aórtica com auto-enxerto pulmonar (cirurgia de Ross). Experiência inicial / Aortic valve replacement with pulmonary autograft (Ross procedure). Initial experience

Objetivo - Relatar a experiência cirúrgica inicial de 4 casos com a utilizaçäo do auto-enxerto pulmonar para substituiçäo da valva aórtica. Métodos - Quatro pacientes masculinos, brancos, com idades entre 23 e 46 anos, portadoras de valvopatia aórtica, forma submetidos a substituiçäo da valva aórtica pelo auto-enxerto pulmonar pela técnica de substituiçäo total da raiz aórtica. Para a reconstituiçäo da via de saída do ventrículo direito foram utilizados homo-enxertos pulmonares e aórtico conservad em soluçäo de antibióticos. Todos tiveram controle pós-operatório com eco-doppler (ECO) e estudo hemodinâmica para a avaliaçäo da funçäo dos auto e homo-enxertos implantados. Resultados - Todos apresentaram excelentes evoluçäo pós-operatória, sem necessidade de drogas inotrópicas e em ritmo sinusal. Os resultados obtidos através do ECO e estudo hemodinâmico revelaram excelente fuçäo dos auto-enxertos implantados sem gradiente em 3 casos e gradiente médio residual de 15 mmHg em um. Näo se observou reguriaçäo aórtica em 3 casos e insuficiência leve no 4o. ano. Os homo-enxertos implantados no lado direito do coraçäo apresentaram excelentes funcäo, sem gradiente em 2 anos e gradiente médio de 6 e 8 mmHg nos outros dois. Conclusäo - A cirurgia do auto-enxerto pulmonar deve ser implantada de forma definitiva em nosso meio

Purpose - Report the initial surgical experience with four cases utilizing a pulmonary autograft for aortic valve replacement Methods - Four patients, all males, white, age between 23 and 46 years having aortic valve disease were submitted to aortic valve replacement with a pulmonary autograft using the root replacement technique. Right ventricular out flow tracts were reconstructed with antibiotic sterilized pulmonary or aortic homografts. All patients had control bidimensional eco-doppler (ECO) and hemodynamic study to evaluate the function of the implanted auto and homografts. Results - All patients had an excelent postoperative recovery, without the necessity of inotropic drugs. All presented in normal sinus rhythm. Postoperative ECO and hemodynamic studies revealed excelent function of the implanted autografts, without gradients in three and with a 15mmHg mean residual gradient in one case. There was no regurgitation in three cases and only trace aortic insufficiency in one. The right sided homografts also showed good function, with no gradient in two cases and mean systolic gradient of 6 and 8mmHg in the other two. Conclusion - The pulmonary autograft procedure should be implemented definitelly in our country

Dose-dependent study of liver lipid peroxidation related parameters in rats treated with pp'-DDT.

Rats treated with increasing doses of pp'-DDT (60, 100 and 180 mg/kg body wt.) i.p., for 24 h, showed a dose-independent increase in liver cytochrome P450 levels, together with an increase in lipid peroxidation, measured as production of thiobarbituric acid reactants. This oxidant condition elicited in the liver by DDT was not accompanied by any change in the activity of NADPH-cytochrome c reductase or in the rate of superoxide anion generation by liver microsomal fraction. The activities of superoxide dismutase and glutathione peroxidase were found to be increased in the higher dose DDT-treated rats, without any change in those from catalase and glutathione reductase. The results presented showed an oxidant condition in the liver elicited by DDT treatment of rats, without any adequate hypothesis proposed to explain these data.

Condrossarcoma da parede toracicaTecnica de resseccao e reparo do defeito. / Chondrosarcoma of the thoracic wall - Ressection thecnics and defect repair

O caso de um paciente portador de um grande condrossarcoma da parede toracica anterior e apresentado. A tecnica de resseccao do tumor, bem como a reconstrucao da parede toracica com tela de polipropileno e um retalho miocutaneo pediculado e apresentada em detalhes