Proposal of a histopathological predictive rule for the differential diagnosis between American tegumentary leishmaniasis and sporotrichosis skin lesions.

BACKGROUND: American tegumentary leishmaniasis (ATL) and sporotrichosis exhibit similar histopathology and low frequencies of microorganism detection. OBJECTIVES: This study seeks to identify microscopic alterations that can distinguish between these diseases. METHODS: Haematoxylin and eosin stained slides of 171 ATL and 97 sporotrichosis samples from active cutaneous lesions were examined for histopathological alterations. The lesions were diagnosed by isolating the agent (which was not visible) in culture. An intuitive diagnosis was assigned to each slide. The strength of the association between the histopathological findings and the diagnosis was estimated by an odds ratio, and each finding was graded according to a regression model. A score was assigned to each sample based on the histopathological findings. A study of the interobserver reliability was performed by calculating kappa coefficients of the histopathological findings and intuitive diagnoses. RESULTS: The markers 'macrophage concentration', 'tuberculoid granuloma' and 'extracellular matrix degeneration' were associated with ATL. 'Suppurative granuloma', 'stellate granuloma', 'different types of giant cells', 'granulomas in granulation tissue' and 'abscess outside the granuloma' were associated with a diagnosis of sporotrichosis. 'Macrophage concentration' and 'suppurative granuloma' had the highest (substantial and almost perfect, respectively) reliability. The regression model score indicated 92.0% accuracy. The intuitive diagnosis had 82.5% diagnostic accuracy and substantial reliability. CONCLUSIONS: Taking into account the clinical and epidemiological context, some histopathological alterations might be useful for the differential diagnosis between ATL and sporotrichosis cutaneous lesions in cases in which the aetiological agent is not visible.

Development of yolk sac inversion in Galea spixii and Cavia porcellus (Rodentia, Caviidae).

Caviomorph development includes an inverted yolk sac. Since principle processes are not understood, we investigated its differentiation in Galea and re-examined material from the guinea pig. Galea showed the typical caviomorph conditions in blastocyst development and the nature of the definitive yolk sac, formed of the visceral layer that became villous, proliferative, vascularized and attached to the uterus and placenta. In contrast to what was known before, in both species parts of the parietal yolk sac and a yolk sac cavity were temporarily present. Data suggest that early yolk sac development in caviomorphs is more complex than thought before.

Fish and apoptosis: molecules and pathways.

Apoptosis is a genetically controlled and evolutionarily conserved form of active cell death, albeit with an increase in complexity with continuing development. A high conservation at the functional and molecular level has been described between the players of the apoptotic machinery in invertebrates (Caenorhabditis elegans and Drosophila) and mammals. However, fish represent an excellent and advantageous model for the study of vertebrate development and disease, bridging the gap between the C. elegans/Drosophila and mouse/human models. Moreover, contrary to C. elegans and Drosophila, fish can be used for studying the development and function of vertebrate-specific organs and have a fully developed immune system similar to that of mammals. Last but not less important, both the environment and human health will obviously gain by using the knowledge generated through the use of fish models, for developing better prophylactic and therapeutic measures with impact on the aquaculture industry. In the present article, structural and functional data on the most important apoptosis related molecules, namely death-receptor, Bcl-2 and caspase families, and mechanisms are reviewed. The data point to the existence in fish of apoptotic pathways equivalent to those of mammals, making fish useful animal models for studying apoptosis, which may have great applicability for the advance of the knowledge on the role of apoptotic cell death in human apoptosis-related disorders as well as in pharmaceutical design.

Fish and apoptosis: studies in disease and pharmaceutical design.

The relevance of fish research has been rising due to the expansion of aquaculture and to the increasing use of fish as replacements for mammals in the study of human physiological and pathological issues. Fish have much smaller genomes compared to mammals, and zebrafish, fugu, medaka and spotted green puffer fish have the sequence of their genomes completed or near completion. Fish have several of the virtues of Drosophila melanogaster and Caenorhabditis elegans for apoptosis research, but offer additional advantages because they are vertebrates and have a developed immune system and apoptotic pathways similar to those of mammals. Many phenotypes in the zebrafish resemble human diseases and this fish has been increasingly used in pharmaceutical design of apoptosis modulating drugs. The roles of microRNAs, bcl-2, p53, insulin-like growth factor-binding protein-3, and cellular apoptosis susceptibility (CAS) and c-Myc genes (involved in the interaction apoptosis/cancer), and Abeta peptides, presenilin enhancer 2, cyclin-dependent kinase 5 and tau (factors with relevant roles in apoptosis-associated human neurodegenerative disorders), have also been successfully investigated in fish models. Results of research with fish that have advanced the knowledge on the participation of apoptosis in viral infections and of apoptosis and secondary necrosis in bacterial infections are also reviewed. It is expectable that the use of fish for research on apoptosis-related issues relevant for human physiology and pathology and for the design of apoptosis-modulating drugs will continue to increase.

Mycobacterial infection in farmed turbot Scophthalmus maximus.

Mycobacteriosis (piscine tuberculosis) has been reported to affect a wide range of freshwater and marine fish species; however, this is the first report describing mycobacterial infections in turbot Scophthalmus maximus. High numbers of granulomas were initially observed in the organs of moribund farmed turbot. Bacteriological analysis of organs with granulomas led to the isolation of Mycobacterium marinum. Further analysis, to determine the prevalence of the infection in the farm and to identify its source, showed the occurrence of a dual infection by M. marinum and M. chelonae. The presence of Nocardia sp. in some of the fish infected with mycobacteria was also detected. The presence of granulomas in internal organs of apparently healthy fish indicated a high prevalence of the disease, a conclusion that was supported by isolating mycobacteria from all fish with or without granulomas. The infection was probably responsible for the mortality observed (approximately 2% mo(-1)), as most of the recently dead fish presented high numbers of granulomas and isolation of mycobacteria was possible from all of the fish. The isolation of M. marinum from the inlet water suggested this as the most plausible source for the infection occurring in the farm.

Electron microscopic evidence that expression of capsular polysaccharide by Photobacterium damselae subsp. piscicida is dependent on iron availability and growth phase.

The expression of capsular polysaccharide (CPS) by the fish pathogen Photobacterium damselae subsp. piscicida was analysed in the virulent strain DI 21 in relation to the growth phase and presence or absence of available iron in the culture medium. Bacterial cells were processed for electron microscopy by a procedure that improves visualisation of the capsule through stabilisation with polycationic ferritin, and electron micrographs of ultrathin sections were scanned with an acquired computerised image analyser to measure capsular area. Cells grown under iron-limited conditions always had a significantly lower amount of capsular material on their surfaces than iron-supplemented cells, even when cells from different culture phases were compared. Irrespective of the presence or absence of iron in the culture medium the amount of CPS decreased with the age of the culture, i.e., from early log phase to late log phase to stationary phase. The in vivo significance of this regulatory role of iron remains to be investigated.

In vivo production of A-protein, lipopolysaccharide, iron-regulated outer membrane proteins and 70-kDa serine protease by Aeromonas salmonicida subsp. salmonicida.

Using specific immunostaining of Western blots, the in vivo expression of several putative virulence factors of Aeromonas salmonicida subsp. salmonicida was demonstrated in infected muscle tissue of Atlantic salmon and rainbow trout. Three virulent isolates of A. salmonicida were used. One isolate was chosen because in vitro it was apparently a non-producer of the 70-kDa serine protease. Infected furuncle tissue was centrifuged and samples of the pellet and supernatant probed for evidence that the components of interest were bacterial cell-associated or secreted. The A-protein was detected in pelleted furuncle material but not in the supernatant. Lipopolysaccharide, both high and low molecular mass, was present in the pellet but only high molecular mass lipopolysaccharide was detected in the furuncle supernatant. Iron-regulated outer membrane proteins were detected in the furuncle pellet. The 70-kDa serine protease was detected in the furuncle supernatant of both protease-producing strains. However, whilst the protease-deficient isolate was demonstrated to produce low levels of the 70-kDa protease when grown in vitro under iron restricted conditions, none could be detected in vivo.

Study of antibodies in paracoccidioidomycosis: follow-up of patients during and after treatment.

The relevance of the humoral response in the prognosis of paracoccidioidomycosis was assessed by measuring the serological responses of individual patients to Paracoccidioides brasiliensis by double immunodiffusion (DID). Sixty-six patients with paracoccidiodomycosis were studied. Sera from 31 individuals were tested before and during treatment with sulfonamide (Group I). Sera from a further 35 individuals were tested after completion of a 2-year course of treatment (Group II). In Group I, clinical improvement was associated with a decrease in antibody titer in all patients. The only patient in this group who had a clinical relapse during specific treatment presented with a 4-fold increase in antibody titer immediately before relapse. In Group II, nine patients remained antibody positive at follow-up (61.9 +/- 40.0 months), despite their good physical health, indicating that the detection of antibodies to P. brasiliensis by the DID test does not necessarily indicate active disease. These data suggest that changes in antibody titers to P. brasiliensis detected by DID may be useful indicators of the extent of active disease. Measurement of antibody titers may be valuable for determining the prognosis of the infection and for deciding on a suitable treatment protocol.