Lanreotide and octreotide complexed with technetium-99m: labeling, stability and biodistribution studies

Lanreotídeo e octreotídeo são octapeptídeos cíclicos análogos da somatostatina e têm sido marcados com Tecnécio-99m para uso em diagnóstico na Medicina Nuclear. Os peptídeos são preparados em solução tampão ftalato/tartarato contendo um agente redutor. O objetivo deste estudo foi a otimização da marcação direta variando alguns parâmetros e a avaliação da estabilidade radioquímica e biodistribuição em animais. Os peptídeos marcados foram obtidos com alta eficiência de marcação e sem a necessidade de etapa de purificação no final do processo. Os melhores resultados de radiomarcação corresponderam á razão molar de SnCl2.2H2O/peptídeo de 4,5. Os peptídeos-99mTc mostraram-se radioquimicamente estáveis por 6 horas. Octreotídeo-99mTc mostrou-se relativamente mais suscetível frente à cisteína do que o lanreotídeo-99mTc. Os peptídeos-99mTc foram principalmente distribuídos no trato gastrointestinal, porém o lanreotídeo-99mTc mostrou maior captação pelo fígado do que o octreotídeo-99mTc. Os resultados indicaram que os produtos podem ser obtidos com alto rendimento radioquímico e com procedimento simples, permitindo estudos posteriores para avaliação de sua eficácia em radiodiagnóstico.Lanreotide and Octreotide are cyclic octapeptide analogues of somatostatin that were labeled with the radioisotope Technetium-99m for use in diagnostic nuclear medicine. The peptides were processed in a tartrate/phthalate buffer solution containing reducing agent. The purpose of this investigation was to optimize direct labeling by varying some parameters, and to evaluate radiochemical stability and biodistribution in animals. The marked peptides were obtained with high labeling efficiency and no need for subsequent purification. Best radiolabeling results corresponded to a molar ratio of SnCl2.H2O/peptide of 4.5. 99mTc-peptides were radiochemically stable for 6 hours. 99mTc-octreotide was relatively more susceptible to cysteine challenge than 99mTc-lanreotide. 99mTc-peptides were mainly distributed in the gastrointestinal tract but 99mTc-lanreotide showed a greater uptake by the liver than 99mTc-octreotide. Results indicated that the products can be obtained with high radiochemical yield, in a simple routine appropriate for further studies to assess their efficacy in radiodiagnosis

Determination of splenomegaly by CT: Is there a place for a single measurement?

OBJECTIVE. Our objective was to determine if there is a single parameter that can be used as a marker of splenomegaly using CT.MATERIALS AND METHODS. Splenic length, width, and thickness were measured in 249 CT scans and multidimensional indexes were obtained from the multiplication of these measurements. Volume was calculated by summing the volumes of multiple contiguous scans. The relationship of the spleen to the left liver lobe and inferior third of the left kidney was also evaluated. Linear equations were obtained to correlate each measurement to the splenic volume.RESULTS. The unidimensional measurements with best correlation to volume were splenic length (r = 0.8 1, p < 0.01) and width (r = 0.804, p < 0.0 1). Correlation was better for the multidimensional indexes (r = 0.95, p < 0.0 1). Using a previously described upper limit of normality for splenic volume of 314.5 cm(3) in the linear regression equation obtained, a maximum spleen length of 9.76 cm was the upper limit of normality. The relation of the lowest point of the spleen to the inferior third of the kidney also showed that if the spleen reached or extended below this portion of the kidney, it could be used as evidence of splenomegaly (p < 0.005), although it had a low sensitivity.CONCLUSION. Splenic length and multidimensional indexes correlate well with splenic CT volume. A splenic length of 9.76 cm can be used to accurately diagnose splenomegaly and can replace multiple-measurement, time-consuming methods in the clinical routine.Univ Catolica Brasilia, BR-71966700 Taguatinga, DF, BrazilUniv Fed Sao Paulo, Dept Diagnost Imaging, Sao Paulo, BrazilHarvard Univ, Sch Med, Beth Israel Deaconess Med Ctr, Dept Radiol, Boston, MA 02115 USAUniv Fed Sao Paulo, Dept Diagnost Imaging, Sao Paulo, BrazilWeb of Scienc

Ureterolithiasis signs on unenhanced helical computed tomography: iconographic essay and literature review

The most important diagnostic sign of ureterolithiasis is the direct visualization of the stone within the ureter. However, in some patients with ureterolithiasis stone visualization may be impaired due to stone small size or low attenuation, respiratory artifacts between data acquisitions, low amount of retroperitoneal fat or recent elimination of the stone. In this context, we describe many secondary computed tomography signs of ureteral obstruction that may useful in the diagnosis of inconclusive cases, and also quantify the degree of urinary obstruction.O principal sinal diagnóstico de ureterolitíase na tomografia computadorizada é a visualização direta do cálculo no interior do ureter. Todavia, a sua caracterização pode ser prejudicada devido a suas pequenas dimensões, variação da respiração entre a aquisição dos cortes tomográficos, escassez de gordura retroperitoneal ou eliminação recente do cálculo. Neste contexto, foram descritos diversos sinais secundários de obstrução ureteral, observados na tomografia computadorizada, que podem auxiliar no diagnóstico de casos duvidosos, além de quantificar o grau de obstrução urinária.Universidade Federal de São Paulo (UNIFESP) Escola Paulista de Medicina Departamento de Diagnóstico por ImagemUNIFESP, EPM, Depto. de Diagnóstico por ImagemSciEL

Beneficial effect of tetracycline prophylaxis in a sepsis model mimicking portal and systemic bacterial translocation routes

Universidade Federal de São Paulo, Dept Pediat, São Paulo, BrazilUniversidade Federal de São Paulo, Dept Microbiol & Infect Dis, São Paulo, BrazilUniversidade Federal de São Paulo, Dept Pediat, São Paulo, BrazilUniversidade Federal de São Paulo, Dept Microbiol & Infect Dis, São Paulo, BrazilWeb of Scienc