Antibody and cytokine responses to Giardia excretory/secretory proteins in Giardia intestinalis-infected BALB/c mice.

The humoral and cellular responses against excretory/secretory proteins and soluble extracts of Giardia intestinalis were evaluated in the course of experimental G. intestinalis infection in BALB/c mice. Production of IgG1, IgG2a, IgA, and IgE antibodies against excreted/secreted proteins and soluble extract was detected after infection by G. intestinalis. Specific IgA antibody against E/S proteins and soluble extract form intestinal fluids in infected mice was detected by ELISA. The Western blotting identified proteins of 30, 58, 63, and 83 kDa for IgA and IgG, respectively. High proliferation rate in vitro of spleen cell and secretion of interleukin-4 (IL-4) at 21 days p.i. after stimulation with excreted/secreted proteins and low proliferative response in the presence of soluble extract in infected BALB/c mice was observed. High production of interferon gamma (IFN-γ) and interleukin-5 (IL-5) at the time of decreasing cyst output (14-21 days p.i.) in infected mice was recorded, suggesting the important role of these cytokines in the control of the infection. Interestingly, progressive and gradual increase of the interleukin-10 after stimulation with both preparations was recorded from 7 days until 28 days after infection, indicating the possible regulatory effect of these antigens on the immune response during Giardia infection. Therefore, the infection by Giardia duodenalis stimulates a mixed response Th1 and Th2, mainly stimulated by excretory/secretory antigens. The immunogenicity of these antigens may be a suitable for identification of the proteins related with the effective immune response in the course of infection by G. duodenalsis.

Experimental tuberculosis in the Wistar rat: a model for protective immunity and control of infection.

BACKGROUND: Despite the availability of many animal models for tuberculosis (TB) research, there still exists a need for better understanding of the quiescent stage of disease observed in many humans. Here, we explored the use of the Wistar rat model for the study of protective immunity and control of Mycobacterium tuberculosis (Mtb) infection. METHODOLOGY/PRINCIPAL FINDINGS: The kinetics of bacillary growth, evaluated by the colony stimulating assay (CFU) and the extent of lung pathology in Mtb infected Wistar rats were dependent on the virulence of the strains and the size of the infecting inoculums. Bacillary growth control was associated with induction of T helper type 1 (Th1) activation, the magnitude of which was also Mtb strain and dose dependent. Histopathology analysis of the infected lungs demonstrated the formation of well organized granulomas comprising epithelioid cells, multinucleated giant cells and foamy macrophages surrounded by large numbers of lymphocytes. The late stage subclinical form of disease was reactivated by immunosuppression leading to increased lung CFU. CONCLUSION: The Wistar rat is a valuable model for better understanding host-pathogen interactions that result in control of Mtb infection and potentially establishment of latent TB. These properties together with the ease of manipulation, relatively low cost and well established use of rats in toxicology and pharmacokinetic analyses make the rat a good animal model for TB drug discovery.

Development of Cryptosporidium parvum-induced gastrointestinal neoplasia in severe combined immunodeficiency (SCID) mice: severity of lesions is correlated with infection intensity.

We reported previously that Cryptosporidium parvum was able to induce intestinal tumors in severe combined immunodeficiency (SCID) mice treated with corticoids. To further characterize this Cryptosporidium-induced cell transformation, SCID mice treated with dexamethasone were challenged with C. parvum oocysts, and euthanatized sequentially after infection for histologic examination. Ki-67 was used as a marker of cellular proliferation. Our previous results were confirmed, and it was also found that mice receiving higher inocula (10(6)-10(7)) experienced more severe neoplastic development. Additionally, neoplastic changes were observed not only in the caecum but also in the stomach and duodenum of some animals. Interestingly, SCID mice (6/6) inoculated with 10(5)-10(7) oocysts showed high grade intraepithelial neoplasia or adenomas with high grade dysplasia in the caecum after Day 46 post-infection (PI). Immunohistochemistry for Ki-67 staining indicated the neoplastic process associated to cryptosporidiosis, and evidenced the first immunohistochemical alterations at early stages of the process, even at 3 weeks PI.

Cryptosporidium parvum, a potential cause of colic adenocarcinoma.

BACKGROUND: Cryptosporidiosis represents a major public health problem. This infection has been reported worldwide as a frequent cause of diarrhoea. Particularly, it remains a clinically significant opportunistic infection among immunocompromised patients, causing potentially life-threatening diarrhoea in HIV-infected persons. However, the understanding about different aspects of this infection such as invasion, transmission and pathogenesis is problematic. Additionally, it has been difficult to find suitable animal models for propagation of this parasite. Efforts are needed to develop reproducible animal models allowing both the routine passage of different species and approaching unclear aspects of Cryptosporidium infection, especially in the pathophysiology field. RESULTS: We developed a model using adult severe combined immunodeficiency (SCID) mice inoculated with Cryptosporidium parvum or Cryptosporidium muris while treated or not with Dexamethasone (Dex) in order to investigate divergences in prepatent period, oocyst shedding or clinical and histopathological manifestations. C. muris-infected mice showed high levels of oocysts excretion, whatever the chemical immunosuppression status. Pre-patent periods were 11 days and 9.7 days in average in Dex treated and untreated mice, respectively. Parasite infection was restricted to the stomach, and had a clear preferential colonization for fundic area in both groups. Among C. parvum-infected mice, Dex-treated SCID mice became chronic shedders with a prepatent period of 6.2 days in average. C. parvum-inoculated mice treated with Dex developed glandular cystic polyps with areas of intraepithelial neoplasia, and also with the presence of intramucosal adenocarcinoma. CONCLUSION: For the first time C. parvum is associated with the formation of polyps and adenocarcinoma lesions in the gut of Dex-treated SCID mice. Additionally, we have developed a model to compare chronic muris and parvum cryptosporidiosis using SCID mice treated with corticoids. This reproducible model has facilitated the evaluation of clinical signs, oocyst shedding, location of the infection, pathogenicity, and histopathological changes in the gastrointestinal tract, indicating divergent effects of Dex according to Cryptosporidium species causing infection.

Raman microspectrometry of laser-reshaped rabbit auricular cartilage: preliminary study on laser-induced cartilage mineralization.

Laser-assisted cartilage reshaping (LACR) is a relatively novel technique designed to noninvasively and permanently restructure cartilaginous tissue. It is believed that heat-induced stress relaxation, in which a temperature-mediated disruption of H2O binding is associated with conformational alterations in the proteoglycan and collagen-rich matrix, constitutes the underlying mechanism of LACR. Several reports have suggested that laser-mediated cartilage mineralization may contribute to the permanent shape change of laser-reshaped cartilage. In an effort to validate these results in the context of Er:glass LACR, we performed a preliminary Raman microspectrometric study to characterize the crystal deposits in laser-irradiated chondrocytes and extracellular matrix. For the first time, we identified intracellular calcium sulfate deposits and extracellular calcium phosphate (apatite) crystals in laser-reshaped rabbit auricular cartilage. Calcium carbonate deposits are localized in both irradiated and nonirradiated samples, suggesting that this mineral plays no role in conformational retention. In our discussion, we elaborate on the possible molecular and cellular mechanisms responsible for intra- and extracellular crystallization, and propose a novel hypothesis on the formation of apatite, inasmuch as the biological function of this mineral (providing structure and rigidity in bones and dental enamel) may be extrapolated to the permanent shape change of laser-irradiated cartilage.

Laser cartilage reshaping in an in vivo rabbit model using a 1.54 microm Er:Glass laser.

BACKGROUND AND OBJECTIVES: The potential applications for facial laser cartilage reshaping (LCR) have generated increasing clinical interest. This study aimed to evaluate in vivo LCR of the rabbit ear using a 1.54 micro m Er:Glass laser in combination with contact cooling. STUDY DESIGN/MATERIALS AND METHODS: LCR was performed in vivo on 12 rabbit ears using a 1.54 micro m Er:Glass laser (Aramis, Quantel Medical, Clermont Ferrand, France) connected to a 4 mm chilled (+5 degrees C) handpiece placed in contact to the skin. Ear curvature was predetermined using a perforated cylindrical guide also used to standardize laser beam delivery. The treatment consisted of 15 spots (3 millisecond, 7 pulses, 12 J/cm(2), 2 Hz, 84/cm(2) cumulative fluence) applied on 10 contiguous parallel rows along the ear. After irradiation, the aluminum jig was replaced by a holder (10 mm diameter plastic tube) maintaining the curvature. This holder was secured with sutures and covered by an adhesive gauze bandage dressing to keep new form during 7 days. In order to assess thermal damage, biopsies were taken on irradiated areas and 1 week, 3 weeks and 6 weeks and studied using haematoxylin-erythrosin-safran (HES) and orcein staining and PCNA to detect cells in cycle. RESULTS: Using the laser with the parameters given above, no immediate visible effects were observed on the skin (no swelling, no bleaching). There were also no late visible side effects like crusting, or blistering. The laser treatment produced changes in the shape of every ear after the dressing was removed. A slight tendency to recover its initial shape was observed for each ear. However, the curvature was stabilized after 10 days and the average shape retention was 64+/-4% at 6 weeks, with a curvature radius of 7.25+/-0.75 mm, instead of 5 mm initially. Histological examination of the laser irradiated side at 1 week showed an intact epidermis. A reduced inflammation process was seen in the dermis. A modification of half of the layer of cartilage was observed at the opposite side where the laser irradiation was applied and proliferative cells were detected inside. At 3 weeks, an important chondroblastic proliferation was observed around the area of contracted cartilage. At 6 weeks, significant thickening of the cartilage layer was observed (from 300 to 490 micro m) and new chondrocytes were clearly seen. CONCLUSIONS: Rabbit ear cartilage can be reshaped with an Er:Glass laser. This technique could offer exciting possibilities that may help patients whose cartilage-lined joints have been affected by disease or trauma. This technique could be certainly utilized to correct alar cartilage deformities and septum deviation of cleft lips.

Benzo(a)pyrene-coated onto Fe2O3 particles-induced apoptotic events in the lungs of Sprague-Dawley rats.

Because benzo(a)pyrene (B(a)P)-coated onto hematite (Fe(2)O(3)) particle-induced adverse effects might alter cell homeostasis in lungs, we investigated the induction of some apoptotic events by such a concurrent exposure on this relevant organ target. Sprague-Dawley rats were intratracheally instilled with Fe(2)O(3) (3 mg), B(a)P (3 mg) or B(a)P (3 mg)-coated onto Fe(2)O(3) particles (3 mg). Forty-eight hours later, both the tumor necrosis factor-receptor and the mitochondrial pathways were studied. We found that exposure to B(a)P (1.13-fold, P<0.05) or to B(a)P-coated onto Fe(2)O(3) particles (1.15-fold, P<0.05) increased caspase 3 activity. However, only the concurrent exposure activated both the caspases 8 (1.21-fold, P<0.05) and 9 (1.27-fold, P<0.05). After exposure to either chemical alone, there was a discrepancy between the findings on tumor necrosis factor-alpha and caspase 8, on one hand, and on cytochrome c and caspase 9, on the other hand. Hence, we suggested that the oxidative stress induced by Fe(2)O(3) or B(a)P will continuously lower or deplete caspase activities, thereby reducing or even avoiding the activation of the apoptotic pathways. In addition, transcriptional induction of p53 gene by Fe(2)O(3) (1.73-fold, P<0.01) or B(a)P-coated onto Fe(2)O(3) particles (1.53-fold, P<0.01) was observed. Taken together, the present results support the underlying hypothesis that the influence of Fe(2)O(3) in B(a)P/Fe(2)O(3) mixtures on the ability of B(a)P to induce some of the events firmly involved in the apoptotic pathways will also be one of the ways that Fe(2)O(3) can affect B(a)P toxicity in lungs.