Um estudo comparativo das cepas Feira de Santana (Bahia) e Porto Rico do Schistosoma Mansoni na infecção experimental do camundongo

Dois grupos de camundongos, infectados com cem cercárias do S. mansoni, um com a cepa Porto Rico e outro com a cepa Feira de Santana mostraram resultados semelhantes quanto à recuperação de esquistossômulos pulmonares, recuperação de vermes do sistema porta, número de ovos por grama de tecido no figado e intestinos, lesões histopatológicas e mortalidade. Na realidade as diferenças entre animais infectados pela mesma cepa foram maiores que quando os dados conjuntos das duas cepas foram considerados.

Inter-group conflict and intra-group punishment in an experimental contest game

We study how conflict in a contest game is influenced by rival parties being groups and by group members being able to punish each other. Our main motivation stems from the analysis of socio-political conflict. The relevant theoretical prediction in our setting is that conflict expenditures are independent of group size and independent of whether punishment is available or not. We find, first, that our results contradict the independence of group-size prediction: conflict expenditures of groups are substantially larger than those of individuals, and both are substantially above equilibrium. Towards the end of the experiment material losses in groups are 257% of the predicted level. There is, however, substantial heterogeneity in the investment behaviour of individual group members. Second, allowing group members to punish each other after individual contributions to the contest effort are revealed leads to even larger conflict expenditures. Now material losses are 869% of the equilibrium level and there is much less heterogeneity in individual group members' investments. These results contrast strongly with those from public goods experiments where punishment enhances efficiency and leads to higher material payoffs.

Comportamento experimental de amostras de Schistosoma mansoni em relação às formas clínicas de esquistossomose: I. Estudo em camundongos

Como já descrevemos em publicação anterior (Conceição, 1985), foram isoladas 20 amostras de S. mansoni de pacientes do sexo masculino com idades entre 13 e 30 anos, autóctones do distrito de Capitão Andrade, município de Itanhomi, no Vale do Rio Doce, em Minas Gerais. Das amostras, seis eram portadores de esquistossomose-infecção (tipo I), seis da forma hepatointestinal (tipo II) e oito da forma hepatoesplênica (tipo III), adaptadas inicialmente, à B. glabrata da mesma área. Cada uma das amostras foi inoculada em 48 camundongos em lotes de 16, respectivamente com 25,50 e 100 cercárias, mantendo-se 12 animais não infectados, com controles. Após 90 dias perfundiu-se o sistema porta de 12 animais (quatro de cada lote). Os animais mortos naturalmente em diversos períodos e a metade de cada lote sacrificada aos 90 e 180 dias foram estudados através dos seguintes parâmetros: 1§) determinação dos pesos de fígado, baço, pulmão e intestino; 2§) contagem de ovos em intestinos (proximal e mediano) e grosso (distal). O número de vermes obtidos pela perfusão nos três grupos em média de 21,9%, 22% e 17,8%% para os tipos I, II e III. A mortalidde natural média dos camundongos submetidos à infecção com 25, 50 e 100 cercárias, foi respectivamente, 12,4%, 23,2% para o grupo I; de 4,7% 19,3% e 22,2% para o grupo II e 11,4%, 29,5% e 41,6% para o grupo III, apresentando-se, portanto, proporcional aos inóculos. O peso dos órgãos dos animais infectados bem como o número de ovos de S. mansoni foi sempre proporcional ao inóculo e a contagem mais elevada nas partes mediana e proximal do intestino nos três grupos. Concluiu-se que não houve correlação entre as formas clínicas da esquistossomose e o comportamento das amostras de S. mansoni em camundongo, ressaltando-se que as alterações parasitológicas encontradas foram proporcionais ao inóculo empregado e ao tempo de infecção, evidenciando os aspectos quantitativos na determinação da doença.

Infecção experimental de Lutzomyia whitmani em cães infectados com Leishmania braziliensis braziliensis

Lutzomyia (N.) whitmani foi infectada em lesões leishmanióticas de três de nove cães parasitados por Leishmania braziliensis braziliensis . Os índices de infecção desses flebotomíneos foram 8,3% (1/12), 7,1% (1/14) e 1,8% (3,160), respectivamente. Por outro lado, 180 Lu. whitmani que se alimentaram em áreas não-ulceradas em um dos cães foram negativos, após dissecação. É discutida a potencialidade de Lu. whitmani como vector de L.B. braziliensis na região endêmica de Três Braços, Bahia, Brasil.

Experimental infection of Lutzomyia longipalpis fed on a patient with cutaneous leishmaniasis due to Leishmania mexicana amazonensis

The authors were able to infect phlebotomine sandflies on a human case of American Cutaneous Leishmaniasis by feeding females of Lutzomyia longipalpis on a patient with a lesion due to Leishmania mexicana amazonensis.

Studies in search of a suitable experimental insect model for xenodiagnosis of hosts with Chagas' disease: 2 - Attempts to upgrade the reliability and the efficacy of xenodiagnosis in chronic Chagas' disease

In order to upgrade the reliability of xenodiagnosis, attention has been directed towards population dynamics of the parasite, with particular interest for the following factors: 1. Parasite density which by itself is not a research objective, but by giving an accurate portrayal of parasite development and multiplication, has been incorporated in screening of bugs for xenodiagnosis. 2. On the assumption that food availability might increase parasite density, bugs from xenodiagnosis have been refed at biweekly intervals on chicken blood. 3. Infectivity rates and positives harbouring large parasite yields were based on gut infections, in which the parasite population comprised of all developmental forms was more abundant and easier to detect than in fecal infections, thus minimizing the probability of recording false negatives. 4. Since parasite density, low in the first 15 days of infection, increases rapidly in the following 30 days, the interval of 45 days has been adopted for routine examination of bugs from xenodiagnosis. By following the enumerated measures, all aiming to reduce false negative cases, we are getting closer to a reliable xenodiagnostic procedure. Upgrading the efficacy of xenodiagnosis is also dependent on the xenodiagnostic agent. Of 9 investigated vector species, Panstrongylus megistus deserves top priority as a xenodiagnostic agent. Its extraordinary capability to support fast development and vigorous multiplication of the few parasites, ingested from the host with chronic Chagas' disease, has been revealed by the strikingly close infectivity rates of 91.2% vs. 96.4% among bugs engorged from the same host in the chronic and acute phase of the disease respectively (Table V), the latter comporting an estimated number of 12.3 x 10[raised to the power of 3] parasites in the circulation at the time of xenodiagnosis, as reported previously by the authors (1982).

A contribution to the study of acute schistosomiasis (an experimental trial)

In an attempt to establish an experimental model of acute schistosomiasis, sequential histological changes were investigated in the skin, lung, liver and spleen of mice infected with 30 or 100 cercariae of Schistosoma mansoni according to four sets of experiments: single infection, repeated infections, unisexual infection and infection in mice born from infected mothers. Animals were killed every other day from exposure up to 50 days after infection. Only mild, isolated, focal inflammatory changes were found before the appearance of mature eggs in the liver, even when repeated infections were made. Severe changes of reactive hepatitis and splenitis appeared suddenly when the first mature eggs were deposited, around the 37th to 42nd day after infection. The mature eggs induced lytic and coagulative necrosis of hepatocytes around them which was soon followed by dense infiltration of eosinophils. So, mature egg-induced lesions appeared as the major factors in the pathogenesis of acute schistosomiasis in mice. Mice born from infected mothers were apparently able to rapidly modulate the egg-lesions, forming early fibrotic granulomas. The murine model of acute schistosomiasis appeared adequate for the study of pathology and pathogenesis of acute schistosomiasis.

Patogenesis of pipe-stem fibrosis of the liver (experimental observation on murine Schistosomiasis)

Mice infected with 30 cercariae of Schistosoma mansoni developed portal and septal fibrosis due to the massive and concentrated deposition of eggs in the periportal areas which occurred following the 16th week after infection. The lesion resembled pipe-stem fibrosis seen in human hepatosplenic schistosomiasis in the following characters: portal fibrosis interconnecting portal spaces as well as portal spaces and central canals; portal inflammation; periovular granulomas; vascular obstruction and telangiectasia. The liver parenchyma maintained its normal architecture. Vascular injection techniques with Indian ink and vinylite revealed that the portal system developed numerous dilated collateral venules coming from the large and medium-sized portal branches, about 10 weeks after schistosome infection. The lodging of schistosome eggs into these collaterals resulted in granulomatous inflammation and fibrosis along all the portal tracts, thus forming the pipe-stem lesion. Although not readily demonstrable grossly, the pipe-stem fibrosis of murine schistosomiasis has many similarities with the human lesion and can be considered to have the same basic pathogenesis.

The impact of penicillinase on cefamandole treatment and prophylaxis of experimental endocarditis due to methicillin-resistant Staphylococcus aureus.

Beta-lactams active against methicillin-resistant Staphylococcus aureus (MRSA) must resist penicillinase hydrolysis and bind penicillin-binding protein 2A (PBP 2A). Cefamandole might share these properties. When tested against 2 isogenic pairs of MRSA that produced or did not produce penicillinase, MICs of cefamandole (8-32 mg/L) were not affected by penicillinase, and cefamandole had a > or =40 times greater PBP 2A affinity than did methicillin. In rats, constant serum levels of 100 mg/L cefamandole successfully treated experimental endocarditis due to penicillinase-negative isolates but failed against penicillinase-producing organisms. This suggested that penicillinase produced in infected vegetations might hydrolyze the drug. Indeed, cefamandole was slowly degraded by penicillinase in vitro. Moreover, its efficacy was restored by combination with sulbactam in vivo. Cefamandole also uniformly prevented MRSA endocarditis in prophylaxis experiments, a setting in which bacteria were not yet clustered in the vegetations. Thus, while cefamandole treatment was limited by penicillinase, the drug was still successful for prophylaxis of experimental MRSA endocarditis.

Long-term follow-up of high-dose chemotherapy with autologous stem-cell transplantation and response-adapted whole-brain radiotherapy for newly diagnosed primary CNS lymphoma: results of the multicenter Ostdeutsche Studiengruppe Hamato-Onkologie OSHO-53 phase II study

Introduction: We previously reported the results of a phase II study for patients with newly diagnosed primary CNS lymphoma (PCNSL) treated with autologous peripheral blood stem-cell transplantation (aPBSCT) and responseadapted whole brain radiotherapy (WBRT). The purpose of this report is to update the initial results and provide long-term data regarding overall survival, prognostic factors, and the risk of treatment-related neurotoxicity.Methods: A long-term follow-up was conducted on surviving primary central nervous system lymphoma patients having been treated according to the ,,OSHO-53 study", which was initiated by the Ostdeutsche Studiengruppe Hamatologie-Onkologie. Between August 1999 and October 2004 twentythree patients with an average age of 55 and median Karnofsky performance score of 70% were enrolled and received high-dose mthotrexate (HD-MTX) on days 1 and 10. In case of at least a partial remission (PR), high-dose busulfan/ thiotepa (HD-BuTT) followed by aPBSCT was performed. Patients without response to induction or without complete remission (CR) after HD-BuTT received WBRT. All patients (n=8), who are alive in 2011, were contacted and Mini Mental State examination (MMSE) and the EORTC QLQ-C30 were performed.Results: Eight patients are still alive with a median follow-up of 116,9 months (79 - 141, range). One of them suffered from a late relapse eight and a half years after initial diagnosis of PCNSL, another one suffers from a gall bladder carcinoma. Both patients are alive, the one with the relapse of PCNSL has finished rescue therapy and is further observed, the one with gall baldder carcinoma is still under therapy. MMSE and QlQ-C30 showed impressive results in the patients, who were not irradiated. Only one of the irradiated patients is still alive with a clear neurologic deficit but acceptable quality of life.Conclusions: Long-term follow-up of our patients, who were included in the OSHO-53 study show an overall survival of 30 percent. If WBRT can be avoided no long-term neurotoxicity has been observed and the patients benefit from excellent Quality of Life. Induction chemotherapy with two cycles of HD-MTX should be intensified to improve the unsatisfactory OAS of 30 percent.