Histopathology of experimental myiasis in mice as a result of infestation and experimental implantation of Dermatobia hominis larvae.

A laboratory model of myiasis as a result of Dermatobia hominis (L.) larvae was developed using mice as hosts. Mice in three groups were each infested with one newly hatched larva and skin biopsies processed for histopathology at 4, 12, and 20 d postinfestation (dpi). Mice in three other groups were each subjected to implantation of one larva collected from an infested (donor) mouse at 4, 12, and 20 dpi. Skin lesions of these receptor mice were then assessed at 10, 14, and 6 d postimplantation (dpimp), respectively. The inflammatory process in infested mice at 4 dpi was discrete, consisting of a thin necrotic layer around the larva, edema, many neutrophils, few eosinophils, mast cells, and proliferation of fibroblasts. At 12 dpi, there was a thicker necrotic layer, edema, many neutrophils and eosinophils, few mast cells, neoformation of capillaries, proliferation of the endothelium and fibroblasts, and early stages of fibrosis. These histopathological characteristics together with fibrosis were observed over a large area of the lesion at 20 dpi. Mice submitted to larval implantations demonstrated similar skin histopathology to that seen in the infested rodents, 10 dpimp corresponding to 12 dpi and 6 or 14 dpimp to 20 dpi. In all mice, the progressive acute inflammatory process followed a sequence linked to factors such as size of larvae and presence of secretory-excretory products. Both infested mice and those implanted experimentally with D. hominis larvae were shown to be suitable models for the study of the parasite-host relationship in this important zoonotic myiasis.

Soluble inflammatory markers as predictors of liver histological changes in patients with chronic hepatitis C virus infection.

Host immune response seems to be mainly responsible for the progression of liver disease among patients with hepatitis C virus (HCV) infection. Immune activation involves the release of cytokines and their receptors that can be measured in plasma samples. The study aimed to evaluate the association between plasma levels of chemokines and soluble tumor necrosis factor receptors (sTNFR) and liver histological changes among patients with chronic HCV infection. Seventy-one treatment-naive patients were included. Plasma levels of CCL2, CCL3, CCL11, CCL24, CXCL9, CXCL10, sTNFR1, and sTNFR2 were measured and liver histological findings were reviewed. Plasma levels of CXCL9, sTNFR1, and sTNFR2 were significantly associated with liver fibrosis, with higher median levels found among patients with moderate/severe fibrosis (F >or= 2) if compared to those with no or mild fibrosis (p = 0.014; p = 0.012; p = 0.009, respectively). Plasma sTNFR2 levels were significantly associated with necroinflammatory activity, with higher median levels among patients with moderate/severe activity (A >or= 2) if compared to those with no or mild activity (2.34 ng/mL vs. 1.99 ng/mL; p = 0.019). In conclusion, plasma levels of CXCL9, sTNFR1, and sTNFR2 were independently associated with liver histological changes, suggesting a role of TNF activation and Th1-type cell-mediated immune response in the pathogenesis of HCV infection.

Lymphadenopathy and expression of nodal mast cells and eosinophils in the myiasis by human bot fly.

Wistar rats (Rattus norvegicus) infested with Dermatobia hominis (L. Jr., 1781) had their axillary lymph nodes removed and histopathologically processed. Follicular hyperplasia in the germinal center was noted from 2 d postinfestation (dpi), exhibiting a high number of centerblasts, mitotic and apoptotic cells, and a thin parafollicular area. The paracortex showed hyperplasia rich in dendritic cells, immunoblasts, and endothelial venules, with diapedesis seen from 4 dpi onward. Hyperplasia of the medullar sinus also was first observed at this point, as well as dilated lymphatic sinus, lymph, macrophages, neutrophils, mast cells, and eosinophils. Medullar strings were expanded and filled with immunoblasts, mitotic cells, and plasmocytes. Lymphadenitis was not observed. The expression of mast cells was similar for both myiasis-affected and control rats but increased significantly (mastocytosis) at 7 and 15 d postlarval emergence (dple). Eosinophilia was observed at 4, 10, 15, 20, and 28 dpi as well as at 2, 7, and 15 dple, particularly on the last three observations of dpi and the earliest dple. This experimental approach allowed progressive tissue reactions in the lymph nodes to be monitored during myiasis, particularly those involving mast cells and eosinophils. These reactions abated and complete repair was observed at 60 dple.

Mammary adenocarcinoma of viral genesis in CF-1 mice

No biotério de pequenos animais da Fundaçäo Ezequiel Dias verificou-se em camundongos frequência mensal média de 0,83 por cento de nódulos tumorais subcutâneos, entre abril de 1991 e julho de 1992. Os achados macroscópicos e à microscopia óptica e eletrônica foram compatíveis com o quadro de adenocarcinoma mamário de origem viral do tipo MuMTV (Murine Mammary Tumor Virus)

Effect of scorpion toxin on the enterochromaffin-like cells in normal and trypanosoma cruzi-infected rats: a morphological study

A injeçäo intravenosa de toxina escorpiônica ( Tityus serrulatus) en ratos normais e infectados pelo Trypanosoma cruzi näo causou alteraçöes morfológicas ultra-estruturais das células enterocromafins-like (ECL) do estômago, embora tenha induzido a aumento significativo da secreçäo do suco gástrico