Reversion of cardiovascular remodelling in renovascular hypertensive 2K-1C rats by renin-angiotensin system inhibitors.

OBJECTIVES: Evaluate whether the RAS dual blockade would induce additional beneficial effects on cardiovascular remodelling when compared to monotherapy in renal hypertensive two kidneys-one clip (2K-1C) rats. METHODS: Hypertensive 2K-1C and normotensive (2K) rats were treated for 14 days with submaximal doses of losartan (LOS), enalapril (ENA), losartan plus enalapril (LOS + ENA) or vehicle (water). Blood pressure and some parameters of cardiovascular remodelling were evaluated. RESULTS: Systolic blood pressure (SBP) was higher in 2K-1C (209 ± 3 mm Hg, P < .05) than in 2K (113 ± 1 mm Hg) rats. There was an additional effect in 2K-1C treated with LOS + ENA (153 ± 9 mm Hg) on lowering SBP when compared to LOS (184 ± 12 mm Hg) or ENA (177 ± 9 mm Hg). None of the treatments had effect on SBP in 2K rats. In 2K-1C, cardiomyocyte hypertrophy was reduced by all treatments, although the cardiac hypertrophy indexes remained unchanged. 2K-1C aortas presented medial thickening that was partially reduced by the treatments. Intimal hyperplasia observed in 2K-1C (15.56 ± 0.89 µm vs 8.24 ± 0.80 µm) was reversed by ENA (9.52 ± 0.45 µm) or LOS + ENA (8.17 ± 0.53 µm). Collagen deposition was increased in 2K-1C hearts (1.77 ± 0.16 vs 1.28 ± 0.09) and aortas (8.1 ± 0.6 vs 5.2 ± 0.2). Treatment with LOS reduced (1.12 ± 0.14%) and ENA (0.81 ± 0.11%) or LOS + ENA (0.86 ± 0.11%) additionally diminished collagen only in 2K-1C hearts. CONCLUSIONS: Submaximal doses of ACEi and/or ARB have inhibitory actions on cardiac remodelling and vascular hypertrophy not entirely dependent on their effects on blood pressure normalization in renovascular hypertensive rats. Combined therapy produced additional reduction in blood pressure than monotherapy despite a similar inhibition on cardiovascular remodelling.

5-Lipoxygenase activity increases susceptibility to experimental Paracoccidioides brasiliensis infection.

Paracoccidioidomycosis (PCM) is a systemic mycosis caused by the thermodimorphic fungus Paracoccidioides brasiliensis. Leukotrienes and lipoxins are lipid mediators produced after 5-lipoxygenase (5-LO) activation that exhibit pro- and anti-inflammatory roles, respectively. Here, we have investigated the contribution of 5-LO enzymatic activity in PCM using an experimental model of P. brasiliensis infection. B6.129 wild-type (B6.129) and 5-LO-deficient (5-LO(-/-)) mice were intravenously inoculated with a virulent strain of P. brasiliensis (Pb18), and the survival rate of the infected mice was investigated on different days after yeast infection. 5-LO(-/-) mice exhibited an increased survival rate associated with a decreased number of CFU. The resistance of 5-LO(-/-) during PCM was associated with augmented nitric oxide (NO) production and the formation of compact granulomas. In addition, the absence of 5-LO was associated with a diminished number of CD4(+) CD25(+) regulatory T cells, higher levels of gamma interferon and interleukin-12, and increased T-bet (a T-box transcription factor that directs Th1 lineage commitment) mRNA levels in the lungs. Taken together, our results show for the first time that 5-LO enzymatic activity increases susceptibility to P. brasiliensis, suggesting that this pathway may be a potential target for therapeutic intervention during PCM.

A scanning electron microscopy study of diseased root surfaces conditioned with EDTA gel plus Cetavlon after scaling and root planing.

In the present investigation, a scanning electron microscopy analysis was performed to evaluate the effects of the topical application of ethylenediaminetetraacetic acid (EDTA) gel associated with Cetavlon (EDTAC) in removing the smear layer and exposing collagen fibers following root surface instrumentation. Twenty-eight teeth from adult humans, single rooted and scheduled for extraction due to periodontal reasons, were selected. Each tooth was submitted to manual (scaling and root planing) instrumentation alone or combined with ultrasonic instruments, with or without etching using a 24% EDTAC gel. Following extraction, specimens were processed and examined under a scanning electron microscope. A comparative morphological semi-quantitative analysis was performed; the intensity of the smear layer and the decalcification of cementum and dentinal surfaces were graded in 12 sets using an arbitrary scale ranging from 1 (area covered by a smear layer) to 4 (no smear layer). Root debridement with hand instruments alone or combined with ultrasonic instruments resulted in a similar smear layer covering the root surfaces. The smear layer was successfully removed from the surfaces treated with EDTAC, which exhibited numerous exposed dentinal tubules and collagen fibers. This study supports the hypothesis that manual instrumentation alone or instrumentation combined with ultrasonic instrumentation is unable to remove the smear layer, whereas the subsequent topical application of EDTAC gel effectively removes the smear layer, uncovers dentinal openings and exposes collagen fibers.

Characterization of CD4+CD25+ natural regulatory T cells in the inflammatory infiltrate of human chronic periodontitis.

Periodontitis is an infectious disease, where putative periodontopathogens trigger chronic inflammatory and immune responses against periodontal structures, in which an unbalanced host response is also determinant to the disease outcome. It is reasonable to assume that patient susceptibility to periodontal tissue destruction could be determined by the balance between the response against periodontopathogens and regulatory mechanisms of these events mediated by suppressive T cells. In the present study, we identified and characterized natural regulatory T cells (Tregs) in the inflammatory infiltrate of human chronic periodontitis (CP) with emphasis on phenotypic analyses that were carried out to address the participation of Tregs in CP. Results showed that patients with CP presented increased frequency of T lymphocytes and CD4+CD25+ T cells in the inflammatory infiltrate of gingival tissues. These cells exhibited the phenotypic markers of Tregs such as forkhead box p3 (Foxp3), CTLA-4, glucocorticoid-inducible TNFR, CD103, and CD45RO and seemed to be attracted to the inflammation site by the chemokines CCL17 and CCL22, as their expression and its receptor CCR4 were increased in CP patients. Moreover, besides the increased detection of Foxp3 mRNA, diseased tissues presented high expression of the regulatory cytokines IL-10 and TGF-beta. In addition, the inflammatory infiltrate in CP biopsies was composed of CD25+Foxp3+ and CD25+TGF-beta+ cells, thus corroborating the hypothesis of the involvement of Tregs in the pathogenesis of CP. Finally, these results indicate that Tregs are found in the chronic lesions and must be involved in the modulation of local immune response in CP patients.

Scanning electron microscopy of the apical structure of human teeth.

The objective of this research was to evaluate, by scanning electron microscopy, the apical structure of extracted human permanent teeth with different degrees of pulp and periapical pathology. A total of 25 teeth were extracted: 5 teeth with vital pulp (group I); 10 teeth with pulp necrosis without radiographically visible periapical lesion (group II); 10 teeth with pulp necrosis with radiographically visible periapical lesion (group III). The root apex was sectioned and processed for scanning electron microscopy. In groups I and II, fibers covered the root cementum and there was no cementum resorption or microorganisms. There were areas of cementum resorption in group III with microorganisms on the root apex surface (biofilm) and no fibers. The authors conclude that the presence of chronic periapical lesions causes severe changes in the apical structure with a destruction of fibers and different degrees of cementum resorption forming lacunae in which bacterial biofilm persisted.

Evaluation of the contamination and disinfection methods of toothbrushes used by 24- to 48-month-old children.

PURPOSE: The purpose of this study was to evaluate: (1) in vivo the contamination by mutans streptococci (MS) of toothbrushes after use on 52 children (24-48 months old) by a single dentist; (2) in vivo the efficacy of 3 solutions (Periogard, Brushtox, and a Cosmocil CQa and Myacide pharma BPa-based experimental solution) in the disinfection of these toothbrushes through a randomized clinical trial; and (3) in vitro the antimicrobial activity of the solutions by the agar diffusion test using 15 microbial strains. METHODS: In the in vivo trial, children were randomly assigned to 1 of 4 groups (N=13) and a 4-stage changeover system was used with a 1-week interval between each stage. Solutions were used by a different group of children in each stage. Children were submitted to a 1-minute brushing (without toothpaste) performed by a single professional, followed by random spraying of the test solutions and microbiological analysis. RESULTS: Brushtox, Periogard, and the experimental solution reduced/prevented the formation of MS colonies/biofilms on the toothbrush bristles compared to the control (sterile tap water; P<.001). Periogard and the experimental solution showed significantly greater reduction of colonies/biofilms compared to Brushtox (P<.01). In the in vitro experiment, Periogard exhibited the greatest inhibition halo average, followed by the experimental solution, Brushtox, and sterile tap water (P<.05). CONCLUSIONS: After a single brushing, severe contamination by mutans streptococci colonies/biofilms was observed on all toothbrushes sprayed with sterile tap water (control). Although Brushtox presented better results than sterile tap water, Periogard and the experimental solution showed greater efficacy against formation of MS colonies/ biofilms on the toothbrush bristles and exhibited larger microbial growth inhibition halos.

CCR5 controls immune and metabolic functions during Toxoplasma gondii infection.

CCR5, an important receptor related to cell recruitment and inflammation, is expressed during experimental Toxoplasma gondii infection. However, its role in the immunopathology of toxoplasmosis is not clearly defined yet. Thus, we inoculated WT and CCR5(-/-) mice with a sub lethal dose of the parasite by oral route. CCR5(-/-) mice were extremely susceptible to infection, presenting higher parasite load and lower tissue expression of IL-12p40, IFN-γ, TNF, IL-6, iNOS, Foxp3, T-bet, GATA-3 and PPARα. Although both groups presented inflammation in the liver with prominent neutrophil infiltration, CCR5(-/-) mice had extensive tissue damage with hepatocyte vacuolization, steatosis, elevated serum triglycerides and transaminases. PPARα agonist Gemfibrozil improved the vacuolization but did not rescue CCR5(-/-) infected mice from high serum triglycerides levels and enhanced mortality. We also found intense inflammation in the ileum of CCR5(-/-) infected mice, with epithelial ulceration, augmented CD4 and decreased frequency of NK cells in the gut lamina propria. Most interestingly, these findings were accompanied by an outstanding accumulation of neutrophils in the ileum, which seemed to be involved in the gut immunopathology, once the depletion of these cells was accompanied by reduced local damage. Altogether, these data demonstrated that CCR5 is essential to the control of T. gondii infection and to maintain the metabolic, hepatic and intestinal integrity. These findings add novel information on the disease pathogenesis and may be relevant for directing future approaches to the treatment of multi-deregulated diseases.

Fulminant gastrointestinal hemorrhage due to Strongyloides stercoralis hyperinfection in an AIDS patient.

Strongyloides stercoralis is an endemic nematode to tropical and subtropical regions of the globe. The parasite is capable of autoinfection, which is limited by an intact immune response. In immunocompromised hosts, hyperinfection and dissemination can occur and have a high index of mortality. A hyperinfection syndrome with dissemination is frequently associated with corticosteroid administration and other conditions (malignancies and organ transplantation). Interestingly, although strongyloidiasis is common among AIDS patients in endemic areas, the hyperinfection syndrome is rarely noted. We report here on a rare manifestation of fulminant gastrointestinal hemorrhage due to hyperinfection of strongyloidiasis in a female drug-abusing, alcoholic HIV/AIDS patient.

A case presentation of a fatal dengue myocarditis showing evidence for dengue virus-induced lesion.

Dengue is a prevalent arthropod-borne viral disease in tropical and subtropical areas of the globe. Dengue clinical manifestations include asymptomatic infections; undifferentiated fever; dengue fever, which is characterized by fever, headache, retroorbital pain, myalgia, and arthralgia; and a severe form of the disease denominated dengue haemorrhagic fever/dengue shock syndrome, characterized by haemoconcentration, thrombocytopenia, and bleeding tendency. However, atypical manifestations, such as liver, central nervous system, and cardiac involvement, have been increasingly reported. We report an atypical and rare presentation of dengue disease marked by a dramatic and fatal cardiogenic shock due to acute myocarditis. Histopathological analysis of heart tissue showed several multifocal areas of muscle necrosis and intense interstitial oedema associated with clusters of virus particles inside the cardiomyocytes and in the interstitial space, providing evidence of a possible direct action of dengue virus on myocardium.

Persistence of epoxy-based sealer residues in dentin treated with different chemical removal protocols.

The presence of residual endodontic sealer in the pulp chamber may cause discoloration of the dental crown and interfere with the adhesion of restorative materials. The aim of this study was to compare the efficacy of different solvents in removing residues of an epoxy resin-based sealer (AH Plus) from the dentin walls of the pulp chamber, by scanning electron microscopy (SEM). Forty-four bovine incisor dental crown fragments were treated with 17% EDTA and 2.5% NaOCl. Specimens received a coating of AH Plus and were left undisturbed for 5 min. Then, specimens were divided in four groups (n = 10) and cleaned with one of the following solutions: isopropyl alcohol, 95% ethanol, acetone solution, or amyl acetate solution. Negative controls (n = 2) did not receive AH Plus, while in positive controls (n = 2) the sealer was not removed. AH Plus removal was evaluated by SEM, and a score system was applied. Data were analyzed by Kruskal-Wallis and Dunn tests. None of the solutions tested was able to completely remove AH Plus from the dentin of the pulp chamber. Amyl acetate performed better than 95% ethanol and isopropyl alcohol (p < 0.05), but not better than acetone (p > 0.05) in removing the sealer from dentin. No significant differences were observed between acetone, 95% ethanol, and isopropyl alcohol (p > 0.05). It was concluded that amyl acetate and acetone may be good options for cleaning the pulp chamber after obturation with AH Plus.

Heme oxygenase inhibition enhances neutrophil migration into the bronchoalveolar spaces and improves the outcome of murine pneumonia-induced sepsis.

A reduction of the neutrophil migration into the site of infection during cecal ligation and puncture-induced sepsis increases host mortality. Inhibition of heme oxygenase (HO) prevents this neutrophil paralysis and improves host survival in the cecal ligation and puncture model. Taking into account that almost 50% of all sepsis cases are a consequence of pneumonia, we designed the present study to determine the role of HO in an experimental model of pneumonia-induced sepsis. The objective of this study was to evaluate whether the inhibition of HO improves the outcome and pathophysiologic changes of sepsis induced by an intratracheal instillation of Klebsiella pneumoniae. The pretreatment of mice subjected to pneumonia-induced sepsis with ZnDPBG (zinc deuteroporphyrin 2,4-bis glycol), a nonspecific HO inhibitor, increased the number of neutrophils in the bronchoalveolar spaces, reduced the bacterial load at the site of infection, and prevented the upregulation of CD11b and the downregulation of CXCR2 on blood neutrophils. Moreover, the pretreatment with ZnDPBG decreased alveolar collapse, attenuating the deleterious changes in pulmonary mechanics and gas exchanges and, as a consequence, improved the survival rate of mice from 0% to ∼20%. These results show that heme oxygenase is involved in the pathophysiology of pneumonia-induced sepsis and suggest that HO inhibitors could be helpful for the management of this disease.

Oropouche virus experimental infection in the golden hamster (Mesocrisetus auratus).

Oropouche virus (OROV), of the family Bunyaviridae, is the second most frequent arbovirus causing febrile disease in Brazil. In spite of this, little is known about pathogenesis of OROV infection. This report describes an experimental model of OROV in golden hamster (Mesocricetus auratus). Following subcutaneous inoculation of OROV, over 50% of the animals developed disease characterized by lethargy, ruffled fur, shivering, paralysis, and approximately one third died. Animals were sacrificed on days 1, 3, 5, 8 and 11 post-inoculation to collect tissue samples from brain, heart, liver, lung, spleen, muscle and blood for virus titration, histology and OROV immunohistochemistry. OROV was detected in high titers in blood, liver and brain, but not in the other organs. Histopathology revealed meningoencephalitis and hepatitis, with abundant OROV antigen detected in liver and brain. Diffuse galectin-3 immunostaining in brain and liver supports microglial and Kupfer cells activation. This is the first description of an experimental model for OROV infection and should be helpful to study pathogenesis and possibly to test antiviral interventions such as drugs and vaccine candidates.

Fulminant gastrointestinal hemorrhage due to Strongyloides stercoralis hyperinfection in an AIDS patient

Strongyloides stercoralis is an endemic nematode to tropical and subtropical regions of the globe. The parasite is capable of autoinfection, which is limited by an intact immune response. In immunocompromised hosts, hyperinfection and dissemination can occur and have a high index of mortality. A hyperinfection syndrome with dissemination is frequently associated with corticosteroid administration and other conditions (malignancies and organ transplantation). Interestingly, although strongyloidiasis is common among AIDS patients in endemic areas, the hyperinfection syndrome is rarely noted. We report here on a rare manifestation of fulminant gastrointestinal hemorrhage due to hyperinfection of strongyloidiasis in a female drug-abusing, alcoholic HIV/AIDS patient.

Viability of Streptococcus mutans toothbrush bristles.

PURPOSE: Employing microbial culture, the purpose of this study was to assess in vitro the viability of Streptococcus mutans on toothbrush bristles relative to the drying time. METHODS: Forty-five toothbrushes were soaked in a suspension containing S. mutans (ATCC 25175) in a 1,720.000 cfu/mL concentration (0.5 McFarland scale) for 4 minutes, rinsed in sterile tap water, and assigned to 9 groups. Group 1 toothbrushes were immediately incubated in CaSaB CaSaB (bacitracin sucrose broth-selective enrichment broth) culture medium for 4 days. Toothbrushes from groups 2 to 9 were kept at room temperature for 4, 8, 12, 24, 36, 48, 60, and 72 hours, respectively, and subsequently incubated in CaSaB culture medium. RESULTS: It was observed that micro-organisms were present on toothbrushes of groups 1 to 3, ranging from 50 to 100+ cfu. From the 12-hour drying period on, there was no growth of S. mutans. Regarding the S. mutans cfu, the results were expressed in scores and submitted to the Kruskal Wallis statistical test. It was observed that groups 1 to 3 were similar to each other (P>.05) and differed significantly (P<.001) from other groups, which, in turn, behaved similarly (P>0.05). From the 12-hour drying period on, there was a statistically significant decrease in the number of S. mutans cfu (P<.01). CONCLUSION: It may be concluded that Streptococcus mutans remained viable on the toothbrushes' bristles for up to 8 hours.

CCR5-dependent regulatory T cell migration mediates fungal survival and severe immunosuppression.

Paracoccidioidomycosis, a debilitating pulmonary mycosis, is caused by the dimorphic fungus Paracoccidioides brasiliensis. The infection results in the formation of granulomas containing viable yeast cells that are the fungal sources for disease reactivation. Because CD4+CD25+ regulatory T cells (Tregs) are in the lesions of patients with paracoccidioidomycosis, the migration of Treg cells is dependent on the axis chemokine-chemokine receptors, and CCR5 ligands are produced in P. brasiliensis-induced lesions, we investigated the role of CCR5 in the control of the infection. The results showed that CCR5-/- mice are more efficient in controlling fungal growth and dissemination and exhibited smaller granulomas than wild-type (WT) mice. In the absence of CCR5, the percentage of CD4+CD25+ T cells expressing Foxp3, glucocorticoid-induced TNFR (GITR), CD103, CD45low, and CTLA-4 in the granulomas was significantly decreased. Interestingly, P. brasiliensis infection resulted in an absence of T cell proliferation in response to Con A in WT but not CCR5-/- mice that was abrogated by anti-CTLA-4 mAb and anti-GITR mAb. Moreover, the adoptive transfer of CD4+CD25+ but not CD4+CD25- T cells from infected WT to infected CCR5-/- mice resulted in a significant increase in fungal load. Overall, CCR5 is a key receptor for the migration of Treg cells to the site of P. brasiliensis infection, leading to down-modulation of effector immune response and the long-term presence of the fungus in the granulomas. Thus, a tight control of Treg cell migration to the granulomatous lesions could be an important mechanism for avoiding exacerbation and reactivation of the disease.

Comparative morphology of reproductive and trophic eggs in melipona bees (Apidae, Meliponini)

The process of cell provisioning and oviposition (POP) in stingless bees involves highly complex interactionsbetween the queen and workers. During this process, workers can usually lay two types of eggs, referred toas reproductive and trophic. Reproductive worker-laid eggs are unfertilized but develop into males whereastrophic worker-laid eggs are eaten by the queen immediately after oviposition. Although the egg-layingactivity of reproductive workers varies considerably among species, the laying of trophic eggs appears to bethe rule in Melipona bees. In this work, we examined whether the morphology of eggs laid by workers andqueens of M. scutellaris, M. compressipes fasciculata and M. asilvai was similar to that of other Meliponaspecies. Egg morphology was examined by scanning electron microscopy whereas egg size was measured bylight microscopy. In all of the species studied, the chorion of queen and worker reproductive eggs showed acharacteristic reticulate pattern. The surface of trophic eggs was not reticulate and had an irregular appearancefollowing fixation. Trophic eggs were also invariably smaller than queen-laid eggs and were sometimessmaller than worker-laid reproductive eggs. These findings indicate that trophic eggs can be smaller than theeggs of functional workers, which suggests that the development of this type of egg is probably associatedwith different physiological adaptations.

Schirrous invasive ductal carcinoma of the breast overexpress p53 oncoprotein

CONTEXT: Breast cancer is the most important neoplasm in adult women, and its worldwide incidence is growing. The tumoral stroma is very important for modulating the growth and invasion of the tumor itself. The relationship between these two components is not completely understood. Schirrous carcinoma is a variant of ductal invasive carcinoma in which the stroma is very desmoplastic, and the importance of this finding still a motive for debate in the literature. OBJECTIVE: To compare the desmoplastic reactions against biological markers, such as estrogen and progesterone receptors, oncoprotein c-erbB-2 and oncoprotein p53, with the objective of studying the relationship between the tumoral stroma and epithelial cancer cells. TYPE OF STUDY: Retrospective study. SETTING: Cancer Hospital A C Camargo and Faculty of Medicine of Ribeirão Preto, University of São Paulo, São Paulo, Brazil. SAMPLE: 107 adult women operated because of ductal invasive carcinoma. The cases were separated into 4 groups according to the desmoplastic reaction -- less than 15 percent, between 15-50 percent, 51-85 percent, and more than 85 percent fibrosis. The grade of fibrosis was determined by picrus-sirius staining and quantified by using a microscope with a stereo-imaging grid. Immunohistochemical methods were used to determine the expression of the hormonal receptors and c-erbB-2/p53 oncoprotein. MAIN MEASUREMENTS: Extent of desmoplastic reaction versus expression of estrogen and progesterone receptors, oncoprotein c-erbB-2, and oncoprotein p53. RESULTS: The results showed that schirrous carcinoma expresses oncoprotein p53 more frequently than other carcinomas with less extensive desmoplastic reaction. There were no differences between the grade of fibrosis and the other biological markers. CONCLUSION: The intense stromatous reaction in invasive ductal carcinoma may modulate the expression of p53. Further investigations should be made with the aim of understanding how this expression determines the proliferative activity in schirrous carcinoma, and whether this overexpression is secondary to mutation of the p53 gene or due to modulation of other molecules of the stroma

Avaliaçäo de tubo valvulado de pericárdio bovino em um modelo experimental animal / Evaluation of a valvulated conduit of bovine pericardium in an animal experimental model

Doenças congênitas, como a atresia pulmonar e a tétrade de Fallot, entre outras, têm sido corrigidas com o uso de condutos extracardíacos. Existe uma variedade de condutos, valvulados ou nao, que possibilita o acesso do fluxo sangüíneo do ventrículo direito à circulaçao pulmonar. Contudo, os tubos plásticos com válvulas biológicas ou metálicas apresentam problemas de degeneraçao e obstruçao da prótese e peeling do tubo, além do alto custo. A experiência adquirida com o pericárdio bovino tratado, mostrando-se impermeável e de fácil sutura, possibilitou a confecçao de tubos valvulados que, neste estudo, foram avaliados quanto a obstruçao, calcificaçao e dilataçao. A utilizaçao de um modelo experimental animal permitiu a avaliaçao periódica detalhada por ecodopplercardiografia e cateterismo durante um, três e seis meses de evoluçao. As peças recuperadas foram estudadas por microscopia óptica e raios X, com a análise de diversas regioes da bioprótese. O exame macroscópico mostrou o pericárdio dos tubos preservados com sinais de pseudo-endotelizaçao, e a maioria das válvulas com calcificaçao moderada, mas ainda com boa funçao. Sao apresentados e discutidos a técnica operatória empregada sem circulaçao extracorpórea e os resultados com o seguimento de cinco animais (carneiros), durante seis meses. Os autores concluem que o enxerto tubular valvulado de pericárdio bovino mostrou bons resultados na via de saída do ventrículo direito, permitindo prever um resultado satisfatório quando empregado em seres humanos, pela conhecida relaçao de degeneraçao acelerada das próteses biológicas no modelo experimental estudado, muitas vezes maior que no homem.

Patogênese das cardiomiopatias: a participaçäo da microcirculaçäo / Pathogenesis of cardiomyopathies: the involvement of microcirculation

Os autores discutem a participaçao da microcirculaçao na gênese das cardiomiopatias. Após breve revisao sobre microcirculaçao e alteraçoes microvasculares com suas conseqüências, discutem alguns modelos de cardiomiopatias com evidências da participaçao de alteraçoes da microcirculaçao na sua gênese.

Evoluçäo da cardiopatia experimentalmente induzida em coelhos infectados com Trypanosoma cruzi / Course of experimental cardiopathy in rabbits infected with Trypanosoma cruzy

Coelhos jovens de ambos os sexos (1-2 meses de idade), outbred, inoculados com tripomastigotas da cepa Colômbia de Trypanosoma cruzi desenvolveram lesöes cardíacas, marco e microscópicas, além de características parasitológicas e imunológicas, muito semelhantes às observadas na doença de Chagas humana, tanto na fase aguda como na fase crônica. Na fase aguda a síndrome cardíaca caracteriza-se macroscopicamente por discreta cardiomegalia, com dilataçäo de câmaras direitas, e miscroscopicamente por miocardite focal pouco acentuada; na fase crônica, por cardiomegalia moderada ou acentuada, com hipertrofia e dilataçäo de câmaras e adelgaçamento da ponta (aneurisma apical), predominantemente do ventrículo esquerdo, e por miocardite focal, com áreas de necrose miocitolítica e degeneraçäo de miocélulas, associadas a infiltrado inflamátorio, principalmente composto de linfócitos, e fibrose intersticial. Devido à reproduçäo de aspectos da doença cardíaca chagástica humana em tempo relativamente curto, à simplicidade, à disponibilidade para múltiplos pesquisadores e ao baixo custo, o modelo representado pelo coelho constitui uma alternativa para estudos dos mecanismos, patologia e tratamento da cardiopatia chagásica