ABSTRACT
@#Leishmaniasis is a neglected and endemic disease that affects poorest population mainly in developing countries. Thymus provides an essential complex environment for T cell maturation and differentiation during leishmania infection. The aim of this study was to investigate the pathological alterations of the Thymus during early Leishmania amazonensis murine infection. BALB/c mice were infected with 105 amastigotes for 24 h, 3 days, 7 days, 15 days or 30 days. At different times of infection, the relative weight of the Thymus was obtained, and the Thymus cellularity was determined by counting total cells of one thymic lobe. The thymic lobe was, alternatively, processed for standard Haematoxylin and Eosin protocol. Our results suggest thymic alteration during the early days of BALB/c mice infection with L. amazonensis. The thymic hypertrophy was accompanied by histological alterations in Thymus architecture with thickening cortex at 3 days p.i. and loss of an evident delimitation between the cortex and medulla at 7 days p.i. when compared to the control mice. That is the first time that Thymus hypertrophy was observed during the early leishmaniasis. However, how it may contribute to infection susceptibility requires further investigation.
ABSTRACT
We assessed the virulence factor profile and in vitro antifungal susceptibility of 27 hospital isolates of C. albicans; 19 of these were from infections (16 urinary and three blood), and the other eight were isolated from sites of colonization (two from hands of health professionals, and six from central venous catheters). The virulence factors assayed were germ tube formation and production of extracellular products (hemolysins, proteinases, and phospholipases). Susceptibility to fluconazole, itraconazole, voriconazole and amphotericin B was determined by E-test. Regarding the virulence factors, the infection isolates produced significantly more hemolysin and germ tubes than the colonization isolates (p<0.05). There were no significant differences in the production of other factors between isolates from the two sources (p>0.05). Amphotericin B showed the lowest minimum inhibitory concentrations for all the isolates. The highest resistance was observed for the azoles, especially in the clinical isolates. These results suggest that the capacity of C. albicans to produce hemolysins and germ tubes may be associated with its pathogenic potential. Colonization isolates may pose a high risk of nosocomial infection, especially when the yeasts show resistance to antifungals.
O perfil de virulência e o de susceptibilidade in vitro aos antifúngicos de 27 amostras de C. albicans de origem hospitalar foi avaliado, sendo que 19 delas foram isoladas de infecções (16 urinárias e três sanguíneas) e as outras oito foram isoladas de colonização (duas de mãos de profissionais da saúde e seis de cateter venoso central). Os seguintes fatores de virulência foram investigados: formação de tubo germinativo e produção de compostos extracelulares (hemolisinas, proteinases e fosfolipases). Suscetibilidade ao fluconazol, itraconazol, voriconazol e anfotericina B foram determinadas por E-test. Em relação aos fatores de virulência, os isolados de infecção produziram significativamente mais hemolisina e tubos germinativos do que os de colonização (p<0.05). Não houve diferença significativa na produção das outras enzimas, entre os isolados das duas fontes (p>0.05). Anfotericina B mostrou as menores concentrações inibitórias mínimas para todos os isolados. Maiores índices de resistência foram observados aos azólicos, especialmente entre os isolados clínicos. Estes resultados sugerem que a capacidade de C. albicans produzir hemolisinas e tubos germinativos pode estar associada com seu potencial patogênico. Por outro lado, leveduras em colonização podem oferecer alto risco para infecção hospitalar, especialmente quando têm perfil de resistência aos antifúngicos.
Subject(s)
Humans , Candida albicans/isolation & purification , Candida albicans/pathogenicity , Hemolysin Proteins , Cross InfectionABSTRACT
The medullary raphe nuclei are involved in central autonomic regulation. In all species investigated, electrical stimulation of the raphe nuclei causes cardiovascular responses, although these changes vary between species. The present study was designed to investigate the participation of these nuclei in cardiovascular regulation in the hamster. We studied the effect on arterial blood pressure (BP) and heart rate (HR) of electrical stimulation (isolated cathodal square wave pulses for 10 sec at 100 Hz, 40-100 muA and 1-msec pulse duration) within the medullary raphe nuclei in urethane-anesthetized (1.2 g/kg, iv, after ether induction) golden hamsters (Mesocricetus auratus, 130 to 150 g, either sex). Electrical stimulation of the same sites was performed on a group of paralysed (Flaxedi1(, 1 mg/kg, iv) and artificially ventilated animals. Stimulation sites were histologically defined and maps of the stimuli were obtained for the effect of electrical stimulation on arterial blood pressure. In another series of experiments L-glutamate (0.18 M) was microinjected (75 to 150 nl) into the nucleus raphe obseurus. Electrical stimulation of the raphe nuclei produced predominantly pressor responses (delta =+ 12 to + 100 mmHg; 49.3 per cent of the stimulated sites). Hypotension (delta =-5 to -20 mmHg; 14.6 per cent of the stimulated sites) and no change in BP (35.3 per cent) were evoked from fewer stimulation sites. Pressor responses were also predominant in paralysed animals (delta =+ 15 to + 95 mmHg; 62.5 per cent of the stimulated sites), and after microinjection of L-glutamate into the raphe obscurus (delta = +35 to + 135 mmHg). The present results demonstrate that in the hamster the stimulation of these nuclei evokes mainly pressor responses. These responses are similar to those obtained in the rat and guinea pig but opposite to those observed in the cat and rabbit.