ABSTRACT Purpose: The aim of this study is to compare the hepatic protective effect of both remote and local postconditioning (POS). Methods: Twenty-eight Wistar rats were assigned into four groups: sham group(SHAM), ischemia-reperfusion group (IR), local ischemic POS group (lPOS) and remote ischemic POS group (rPOS). Animals were subjected to liver ischemia for 30 min. Local ischemic POS group consisted of four cycles of 5 min liver ischemia, followed by 5 min reperfusion (40 min). Remote ischemic POS group consisted of four cycles of 5 min hind limb ischemia, followed by 5 min hind limb perfusion after the main liver ischemia period. After 190 minutes median and left liver lobes were harvested for biochemical and histopathology analysis. Results: All the conditioning techniques were able to increase the level of bothglutathione reductase and peroxidase, showing higher values in the rPOS group when compared to the lPOS. Also, thiobarbituric acid reactive substances were higher in all intervention groups when compared to SHAM, but rPOS had the lower rates of increase, showing the best result. The histopathology analysis showed that all groups had worst injury levels than SHAM, but rPOS had lower degrees of damage when compared to the lPOS, although it was not statistically significant. Conclusion: Remote postconditioning is a promising technique to reduce liver ischemia-reperfusion injury, once it increased antioxidants substances and reduced the damage.

RESUMO A produção de álcoois pela hidrogenação do CO na presença de um catalisador, normalmente Cu/ZnO/Al2O3, em pressões de 50-100 bar e temperaturas na faixa de 220 a 300 °C, é uma importante rota de produção do metanol. Neste cenário, um novo catalisador foi sintetizado substituindo o ZnO por Nb2O5, que por sua vez, trata-se de uma matéria prima nacional com propriedades semicondutoras semelhantes ao óxido de zinco, sendo pouco investigada até o momento. Deste modo, esta pesquisa tem como objetivo avaliar o desempenho do catalisador Cu/Nb2O5/Al2O3 na reação hidrogenação do CO para produção de álcoois de cadeia curta, em especial o metanol. A síntese do catalisador foi feita via impregnação úmida, e seguiu a mesma proporção (% mássica) do catalisador comercial Hifuel R120 Cu/ZnO/Al2O3, sendo sua composição baseada na seguinte relação 18,7/50,5/30,8, respectivamente. O catalisador foi peletizado e caracterizado pelas técnicas de Fissisorção de N2, Difração de Raios X, Microscopia Eletrônica de Varredura, Microscopia Eletrônica de Transmissão, Dessorção a Temperatura Programada de NH3 e Distribuição de tamanhos de partículas por DLS. Os ensaios reacionais foram conduzidos a 250 ºC e 40 bar, usando uma mistura sintética de H2:CO (White Martins, 99%) de 2:1 em uma unidade experimental, sendo o produto líquido obtido, analisado por cromatografia gasosa e espectroscopia de infravermelho por transformada de Fourier (FTIR). O catalisador apresentou bons resultados na reação de hidrogenação do CO, produzindo principalmente álcoois de cadeia curta, o desempenho do catalisador foi comparado ao do Cu-ZnO-Al, sintetizado neste trabalho para comparação. Além disso, os resultados indicam que é possível atuar no preparo do catalisador ou nas condições reacionais para torná-lo mais seletivo ao metanol e obter uma maior conversão do gás de síntese.

ABSTRACT The production of alcohols by hydrogenation of CO in the presence of a catalyst, normally Cu/ZnO/Al2O3, at pressures of 50-100 bar and temperatures in the range of 220 to 300 ° C, is an important route for methanol production. In this scenario, a new catalyst was synthesized replacing ZnO by Nb2O5. This catalyst is a national raw material with semiconductor properties similar to zinc oxide, which has been little investigated so far. This research aims to evaluate the performance of the Cu/Nb2O5/Al2O3 catalyst in the hydrogenation reaction of CO for the production of short-chain alcohols, in particular or in methanol. The catalyst synthesis was made via wet impregnation, and followed the same proportion (% metric) of the commercial catalyst Hifuel R120 Cu/ZnO/Al2O3, with its specific composition in the following ratio 18,7/50,5/30,8, respectively. The catalyst was pelletized and characterized by the N2 physisorption, X-Ray Diffraction, Scanning Electron Microscopy, Transmission Electron Microscopy, Programmed Temperature Desorption and Size Distribution by DLS techniques. Clinical trials were conducted at 250 ºC and 40 bar, using a 2:1 mixture of H2:CO (White Martins, 99%) in an experimental unit the liquid product were analyzed by gas chromatography and infrared spectroscopy Fourier transform (FTIR). The catalyst shows good results in the hydrogenation reaction of CO, producing mainly short chain alcohols, the catalyst performance was compared to Cu-ZnO-Al, synthesized in this work. In addition, the results that can be performed in the preparation of the catalyst or in the reaction conditions to select the most selected filter for methanol and obtain a greater change in the recording gas.

Abstract Objectives: This study aimed to verify the presence of polyomavirus BK (BKPyV) in the saliva of kidney transplant recipients and to correlate it with blood viremia. Material and Methods: We have conducted a cross-sectional study with a sample involving 126 renal transplant recipients. 126 samples of saliva and 52 samples of blood were collected from these patients. Detection and quantification of BKPyV were performed using a real-time PCR. To compare the presence of BKPyV in blood and saliva, the binomial proportion test was used. To verify associations between salivary shedding BKPyV and post-transplant periods (in months), the Mann-Whitney test was used. Spearman's correlation was used to correlate the viral load in the saliva with blood of kidney transplant recipients. Results: The mean age of the study group was 51.11±12.45 years old, and 69 participants (54.8%) were female, with a mean post-transplantation time of 4.80±6.04 months. BKPyV was quantified in several samples of saliva and blood, with medians of 1,108 cp/mL and 1,255 cp/mL, respectively. Only 16/52 (30.8%) participants presented BKPyV in blood, and 59/126 (46.8%) excreted the virus in saliva (p=0.004). BKPyV shedding was found in patients at a shorter post-transplantation period (3.86±5.25, p=0.100). A weak correlation was observed between viral quantification in saliva and blood (Spearman's correlation coefficient=0.193). Conclusion: The results of this study suggested that, although saliva excretes more BKPyV than blood, there is no reliable correlation between salivary shedding and blood viremia, showing two independent compartments of viral replication.

ABSTRACT OBJECTIVE: In 1996, the Brazilian cardiovascular surgeon, Dr. Randas Batista, introduced a surgical technique called partial left ventriculectomy, where he admitted the possibility of reducing the diameter of the left ventricle through the sectioning of one section of its wall. After the publication of this study, thousands of case reports and procedure analysis have been published, and due to several disappointing results, many doctors and institutions failed to execute it. As the main objective of this study, stands out the search for success cases of ventriculectomy in the last 12 years and if during this period it was achieved some significant development in this procedure that allows obtaining lower mortality rate postoperatively. METHODS: Systematic review of indexed scientific literature over the past 12 years and the term "Partial Left Ventriculectomy". RESULTS: There has been a considerable number of reported successful cases and highly significant findings in regard to determining the most suitable region for the section, proper selection of the patients indicated to the procedure, including the influence of the coronary artery anatomy in the nomination procedure and the need for preservation of ventricular geometry to ensure better quality of ventricular contractions after the sectioning. CONCLUSION: This surgical procedure has been successfully performed, mainly in Japan, improvements in its efficiency were found and the need for a mathematical modeling of the slice to be severed is a prominent factor in many studies.

OBJETIVO: Avaliar a prevalência de excreção urinaria de vírus JC (VJC) e vírus BK (VBK) em pacientes HIV+ sem sintomas neurológicos. MÉTODOS: Amostras de urina de pacientes HIV+ sem sintomas neurológicos foram testados para a presença de VJC e VBK através da técnica de PCR. As amostras foram triadas para a presença de poliomavírus com par de primers complementares a região precoce do genoma do VBK e do VJC (AgT). A presença foi confirmada através de dois outros ensaios de PCR dirigidos a região do gene VP1 de ambos os vírus. A análise estatística foi realizada com auxílio do teste de Kruskal-Wallis para dados numéricos e Pearson ou Yater para variáveis categóricas. RESULTADOS: Ao todo foram inclusos no estudo 75 pacientes. A prevalência geral de excreção de poliomavírus na urina foi de 67/75 (89,3%). O DNA do vírus VBK foi detectado em 14/75 (18,7%) das amostras de urina, e o DNA do VJC foi detectado em 11/75 (14,7%) das amostras testadas. Ambos os vírus estavam presentes simultaneamente em 42/75 (56%) das amostras de urina. CONCLUSÃO: Encontramos, no presente estudo, uma alta taxa de excreção de VJC, VBK e excreção simultânea em pacientes HIV+. Ainda, esses resultados diferem de outros disponíveis na literatura.

OBJECTIVE: To evaluate the prevalence of the urinary excretion of BKV and JCV in HIV-infected patients without neurological symptoms. METHODS: Urine samples from HIV-infected patients without neurological symptoms were tested for JC virus and BK virus by PCR. Samples were screened for the presence of polyomavirus with sets of primers complementary to the early region of JCV and BKV genome (AgT). The presence of JC virus or BK virus were confirmed by two other PCR assays using sets of primers complementary to the VP1 gene of each virus. Analysis of the data was performed by the Kruskal-Wallis test for numerical data and Pearson or Yates for categorical variables. RESULTS: A total of 75 patients were included in the study. The overall prevalence of polyomavirus DNA urinary shedding was 67/75 (89.3%). Only BKV DNA was detected in 14/75 (18.7%) urine samples, and only JCV DNA was detected in 11/75 (14.7%) samples. Both BKV and JCV DNA were present in 42/75 (56.0%) samples. CONCLUSION: In this study we found high rates of excretion of JCV, BKV, and simultaneous excretion in HIV+ patients. Also these results differ from the others available on the literature.

OBJETIVO: O objetivo principal deste estudo foi comparar o desempenho das escalas de sedação de Ramsay e Richmond em pacientes críticos sob ventilação mecânica em um hospital universitário. MÉTODOS: Estudo prospectivo onde foram incluídos todos os pacientes sob ventilação mecânica com pelo menos 48 horas de internação, durante quatro meses, totalizando 45 pacientes. Foram avaliados diariamente a modalidade de sedação, dose dos sedativos e analgésicos e o nível de sedação através das escalas de Ramsay e Richmond. O teste T de Student, os índices de correlação de Pearson e Spearman, e a elaboração de curvas Receiver Operating Characteristic (ROC) foram utilizados para a análise estatística. RESULTADOS: A mortalidade geral observada foi de 60%. Nesta série, o tempo de sedação e a dose de sedativos utilizada não se correlacionaram com a mortalidade. Sedação profunda (Ramsay > 4 ou Richmond < -3) correlacionou-se positivamente com uma maior probabilidade de morte, com uma área sob a curva (ASC) > 0,78. Níveis adequados de sedação (Ramsay 2 a 4 ou Richmond 0 a -3) correlacionaram-se sensivelmente à probabilidade de sobrevivência, com uma ASC > 0,80. Em 63 evoluções (8,64%) foram observados níveis baixos de sedação, porém não se evidenciou nenhuma correlação entre a ocorrência de agitação e prognósticos desfavoráveis. Houve uma boa correlação entre as escalas Ramsay e Richmond (Pearson > 0,810 - p<0,0001). CONCLUSÃO: Neste estudo, as escalas de Ramsay e Richmond mostraram-se equivalentes para a avaliação de sedações profunda, insuficiente e adequada e ambos demonstraram boa correlação com mortalidade em pacientes excessivamente sedados.

OBJECTIVE: The main purpose of this study was to compare performance of the Ramsay and Richmond sedation scores on mechanically ventilated critically ill patients, in a university-affiliated hospital. METHODS: This was a 4-month prospective study, which included a total of 45 patients mechanically ventilated, with at least 48 hours stay in the intensive care unit. Each patient was assessed daily for sedation mode, sedative and analgesic doses and sedation level using the Ramsay and Richmond scores. Statistical analysis was made using Student's t-test, Pearson's and Spearman's correlation, and constructing ROC-curves. RESULTS: A high general mortality of 60% was observed. The length of sedation and daily dose of medication did not correlate with mortality. Deep sedation (Ramsay > 4 or Richmond < -3) was positively correlated with probability of death with an AUC > 0.78. An adequate level of sedation (Ramsay 2 to 4 or Richmond 0 to -3) was sensitively correlated with probability of survival with an AUC > 0.80. A low level of sedation was observed in 63 days evaluated (8.64%), and no correlation was found between occurrence of agitation and unfavorable outcomes. Correlation between Ramsay and Richmond scores (Pearson's > 0.810 - p<0.0001) was good. CONCLUSION: In this study, Ramsay and Richmond sedation scores were similar for the assessment of deep, insufficient and adequate sedation. Both have good correlation with mortality in over sedated patients.

OBJETIVO: A tosse manualmente assistida (TMA) consiste na compressão vigorosa do tórax no início da expiração espontânea ou da fase expiratória da ventilação mecânica. Tendo em vista a utilização rotineira da TMA na unidade de terapia intensiva, a proposta deste estudo foi analisar os efeitos dessa técnica no comportamento da mecânica do sistema respiratório de pacientes submetidos a suporte ventilatório total. MÉTODOS: Foram estudados 16 pacientes intubados, sedados e submetidos à ventilação mecânica controlada, sem participação interativa com o ventilador. A mecânica do sistema respiratório e a saturação periférica de oxigênio foram mensuradas antes e após a aplicação de TMA e após a aspiração traqueal. Foram realizadas 10 aplicações bilaterais da técnica por paciente, com intervalos de 3 ciclos respiratórios entre cada aplicação. RESULTADOS: Os dados evidenciaram a diminuição da pressão resistiva e da resistência do sistema respiratório e aumento da saturação periférica de oxigênio após a aplicação da TMA associada à aspiração traqueal. Não foram evidenciadas alterações das pressões de pico, platô e complacência do sistema respiratório após a aplicação da TMA. CONCLUSÕES: A TMA foi capaz de alterar a mecânica do sistema respiratório, mais especificamente aumentando as forças resistivas através do deslocamento de secreção. A técnica pode ser considerada eficaz e segura para pacientes em pós-operatório imediato. A associação entre TMA e aspiração traqueal mostrou-se benéfica, alcançando os objetivos propostos: deslocamento e remoção de secreção das vias aéreas.

OBJECTIVE: Manually assisted coughing (MAC) consists of a vigorous thrust applied to the chest at the beginning of a spontaneous expiration or of the expiratory phase of mechanical ventilation. Due to routine use of MAC in intensive care units, the objective of this study was to assess the effects of MAC on respiratory system mechanics in patients requiring full ventilatory support. METHODS: We assessed 16 sedated patients on full ventilatory support (no active participation in ventilation). Respiratory system mechanics and oxyhemoglobin saturation were measured before and after MAC, as well as after endotracheal aspiration. Bilateral MAC was performed ten times on each patient, with three respiratory cycle intervals between each application. RESULTS: Data analysis demonstrated a decrease in resistive pressure and respiratory system resistance, together with an increase in oxyhemoglobin saturation, after MAC combined with endotracheal aspiration. No evidence of alterations in peak pressures, plateau pressures or respiratory system compliance change was observed after MAC. CONCLUSIONS: The use of MAC alters respiratory system mechanics, increasing resistive forces by removing secretions. The technique is considered safe and efficacious for postoperative patients. Using MAC in conjunction with endotracheal aspiration provided benefits, achieving the proposed objective: the displacement and removal of airway secretions.

Um total de 316 amostras de lavado de nasofaringe obtidas de crianças em acompanhamento ambulatorial com até dois anos de idade durante episódio de doença aguda do trato respiratório foram processadas para detecção do vírus sincicial respiratório (VSR) utilizando três diferentes técnicas: isolamento viral, imunofluorescência direta e reação em cadeia por polimerase (RT-PCR). Destas amostras, 36 (11,4%) foram positivas para o VSR. A RT-PCR foi a técnica mais sensível, com positividade em 35 (11,1%) das amostras, seguindo-se a imunofluorescência direta (25/316, 7,9%) e o isolamento viral (20/315, 6,3%) (p < 0,001). Uma amostra foi positiva pela imunofluorescência e negativa pela RT-PCR, e 11/36 (31,4%) foram positivas somente pela RT-PCR. Concluímos que a RT-PCR é mais sensível que a imunofluorescência e o isolamento viral para detecção do VRS em amostras de aspirado de nasofaringe de recém-nascidos e lactentes.

A total of 316 samples of nasopharyngeal aspirate from infants up to two years of age with acute respiratory-tract illnesses were processed for detection of respiratory syncytial virus (RSV) using three different techniques: viral isolation, direct immunofluorescence, and PCR. Of the samples, 36 (11.4%) were positive for RSV, considering the three techniques. PCR was the most sensitive technique, providing positive findings in 35/316 (11.1%) of the samples, followed by direct immunofluorescence (25/316, 7.9%) and viral isolation (20/315, 6.3%) (p < 0.001). A sample was positive by immunofluorescence and negative by PCR, and 11 (31.4%) were positive only by RT-PCR. We conclude that RT-PCR is more sensitive than IF and viral isolation to detect RSV in nasopharyngeal aspirate specimens in newborn and infants.

The objective of this work was to characterize histopatologically and morphometrically the alterations of the mouse liver during the acute infection by the MORC-2 strain of Trypanosoma cruzi. This strain showed marked tropism by the liver, with numerous nests of amastigotes in the examined sections. The liver of the infected animals was constituted by smaller cells, with granular cytoplasm. In some areas, the sinusoids were congested and the Kuppfer cells were hipertrofied and hiperplasic. The hepatic tissue showed circumscribed foci of inflammatory cells into necrotic areas, sinusoids, around the contrilobular veins and the portal spaces. The centrilobular vein was dilated and congested, with focal necrosis and rupture of the wall in some regions. The portal spaces were disorganized, sometimes with intense inflammatory infiltrate. In some areas it was possible to observe cystic degeneration (spongis hepatis). In the hepatic tissue, nests of amastigotes, of variable sizes, were observed, some surrounded by chronic inflammatory infiltrate. In the portal space, the relative volume of the biliary ducts and blood vessels, as well as the surface density of the arteries was greater in the infected group

El objetivo de este trabajo fue caracterizar histopatológicamente y morfométricamente las alteraciones del tejido hepático de ratón, durante la fase aguda de la infección por la cepa MORC-2 de Trypanosoma cruzi. Esta cepa mostró acentuado tropismo por el hígado, con numerosos nidos de amastigotes en los cortes examinados. El hígado de los animales infectados estaba constituido por células menores, con citoplasma granuloso. En algunas áreas, los sinusoides estaban congestionados y las células de Kupffer hipertróficas e hiperplásicas. El tejido hepático mostró focos circunscritos de células inflamatorias en áreas de necrosis, sinusoides, en torno de las venas centrolobulillares y de los espacios porta. La vena centrolobulillar estaba dilatada y congestionada, con necrosis focales y ruptura de la pared en algunos campos. Los espacios porta estaban desorganizados, a veces, con intenso infiltrado inflamatorio. En algunas áreas fue posible observar degeneración cística (spongis hepatis). Por todo el tejido hepático se observaron nidos de amastigotes, de tamaño variable, algunos rodeados por infiltrado inflamatorio crónico. En el espacio porta, el volumen relativo de los conductos biliares y vasos sanguíneos, así como la densidad de superficie de las arterias fueron mayores en el grupo infectado

OBJETIVO: Estudar o efeito da esplenectomia na infecção intra-abdominal com bactérias da flora enteral, liberadas para a cavidade abdominal através de uma lesão induzida no cólon de ratos Wistar. MÉTODOS: Foram utilizados 64 animais, sendo 20 do Grupo A1 (normais sem sutura da lesão), 22 do Grupo A2 (normais com sutura da lesão) e 22 do Grupo B (esplenectomizados e com sutura da lesão). Os animais foram submetidos à laparotomia mediana e a indução da peritonite intra-operatória foi obtida através de lesão do cólon previamente distendido pela introdução de uma sonda naso-gástrica via retal e injeção de 2 ml de soro fisiológico. Foram realizados exames bacteriológicos de lavado abdominal obtido por swab esterelizado e exame microscópico de segmento suturado do cólon de amostras obtidas dos grupos A2 e B com 48hs, 96hs e 12 dias de pós-operatório. Todos os animais foram submetidos a necropsia por ocasião do óbito ou no 12º. dia de pós-operatório quando os sobreviventes foram sacrificados. RESULTADOS: Agentes bacterianos semelhantes foram encontrados nos três grupos: E.coli (100%); Enterococcus faecalis (97%); P. mirabilis (90%); Klebsiela pneumoniae (70%); Citobacter freundi (70%) e Enterobacter aglomerans (63%). O exame microscópico revelou menor reação inflamatória no grupo esplenectomizado. A causa da morte na maioria foi peritonite nas primeiras 96hs. Houve alto índice de significância de mortalidade entre os animais do Grupo B (80%) em relação ao Grupo A2 (sem mortalidade) e em relação ao Grupo A1 (35%). CONCLUSÃO: Houve alto índice de significância de mortalidade em vigência de peritonite nos animais esplenectomizados em relação aos animais que não foram esplenectomizados.

BACKGROUND: Study the effects of splenectomy on the intra-abdominal infection by bowel flora, consequent to a colonic injury in Wistar rats. METHODS: We used 64 animals, 20 for Group A1 (normal with colon lesion left open), 22 for Group A2 (normal with colon lesion sutured) and 22 for Group B (spleen removed). The animals were submitted to a laparatomy through a midline abdominal incision and peritonitis was induced by a colonic lesion in the colon previously distended with 2 ml of saline introduced in the rectum. Bacteriological studies of the abdominal wash obtained with a sterilized swab and microscopic studies of samples of the segment of the sutured colon obtained at 48hrs, 96hrs and on the 12 post op day, were made in each group. All rats were submitted to an autopsy on the day of death or on the 12th post op day when the survivors were sacrificed. RESULTS: Similar bacteria were found in the three groups. E. coli (100%); Enterococcus fecalis (97%); Klebsiela pneumoniae (70%); Citrobacter freundi (70%) and Enterobacter aglomerans (63%). In the first 96 hours the rats without spleen had a lesser inflammatory reaction when compared to the group with spleen. The leading cause of death was generalized peritonitis in the first 96 hours. There was a significant statistical difference in the mortality rate between Group B (80%), Group A2 (no mortality) and Group A1 (35%). CONCLUSION: There was a significant statistical difference in the mortality rate caused by peritonitis between the groups with splenectomy when compared to the group with no splenectomy.

Camundongos normais, utilizados como filtros biológicos, foram inoculados endovenosamente, com tripomastigotas sangüícolas da derivada RCL da cepa RC do T. cruzi. Decorridas 48 horas, os animais foram submetidos ao xenodiagnóstico e à punção cardíaca para semeadura do sangue em meio de Warren. No estômago dos triatomíneos e em cultura a 28°C, os tripomastigotas diferenciaram-se em formas arredondadas (esferomastigotas e/ou amastigotas). Esse comportamento das formas sangüícolas largas tem sido observado com freqüência e nos leva a inferir que a biologia do T. cruzi não estaria apenas relacionada com a cepa, mas, eventualmente, com populações do parasita.

The study of the behaviour of T. cruzi strains in animals as in human beings, runs into great difficulties when the attempt is made to relate the morphology of this parasite to its biological behaviour. The thin forms are able to penetrate vertebrate cells faster than the broad forms. So, faced with the biological complexity of the T. cruzi strains and substrains it was decided to investigate the behaviour of its blood forms obtained from normal mice as biological filters. These mice were endovenously inoculated with blood trypomastigotes from derivated RCL of the T. cruzi RC strain. Forty-eight hours later, the animals went through xenodiagnosis and heart punch in order to sow the blood in Warren's medium. The trypomastigotes became round (spheromastigotes and/or amastigotes) in the stomach of the triatomines and cultures at 28°C. The behaviour of the broad forms has been frequently observed and leads to the conclusion that the biology of the T. cruzi is not only related to the strain, but, sometimes, to the parasite population.

Camundongos normais, utilizados como filtros biológicos, foram inoculados endovenosamente, com tripomastigotas sangüícolas da derivada RCL da cepa RC do T. cruzi. Decorridas 48 horas, os animais foram submetidos ao xenodiagnóstico e à punção cardíaca para semeadura do sangue em meio de Warren. No estômago dos triatomíneos e em cultura a 28°C, os tripomastigotas diferenciaram-se em formas arredondadas (esferomastigotas e/ou amastigotas). Esse comportamento das formas sangüícolas largas tem sido observado com freqüência e nos leva a inferir que a biologia do T. cruzi não estaria apenas relacionada com a cepa, mas, eventualmente, com populações do parasita.

The study of the behaviour of T. cruzi strains in animals as in human beings, runs into great difficulties when the attempt is made to relate the morphology of this parasite to its biological behaviour. The thin forms are able to penetrate vertebrate cells faster than the broad forms. So, faced with the biological complexity of the T. cruzi strains and substrains it was decided to investigate the behaviour of its blood forms obtained from normal mice as biological filters. These mice were endovenously inoculated with blood trypomastigotes from derivated RCL of the T. cruzi RC strain. Forty-eight hours later, the animals went through xenodiagnosis and heart punch in order to sow the blood in Warren's medium. The trypomastigotes became round (spheromastigotes and/or amastigotes) in the stomach of the triatomines and cultures at 28°C. The behaviour of the broad forms has been frequently observed and leads to the conclusion that the biology of the T. cruzi is not only related to the strain, but, sometimes, to the parasite population.