The mammalian cell entry (Mce) operon 3 (mce3) is one of four homologous mce operons of Mycobacterium tuberculosis, encoding six (Mce3A-F) invasin-like membrane-associated proteins. Previous studies have shown that recombinant expression of Mce1A encoded by the mce1 operon in Escherichia coli allows this non-pathogenic bacterium to invade and survive inside macrophages, and latex beads coated with Mce1A are internalized by non-phagocytic HeLa cells. However, the role of other mce1 operon proteins (Mce1B-F) and proteins encoded by the operons mce2-4 in facilitating the internalization of M. tuberculosis in mammalian cells has not been studied. This study was carried out to determine whether Mce proteins encoded by the mce3 operon also facilitated the internalization of latex beads by HeLa cells. Recombinant pure Mce3A and lipoprotein LprM (Mce3E) were expressed and purified from E. coli cells. Mce1A expressed as a fusion protein with glutathione S-transferase (GST-Mce1A) and GST alone, purified similarly from E. coli cells, were used as control proteins. Fluorescent latex beads coated with purified proteins were used to study their uptake by HeLa cells using fluorescence microscopy, flow cytometry and electron microscopy. Fluorescence microscopy and flow cytometry showed an association of HeLa cells with beads coated with both Mce3A and LprM, whilst GST-Mce1A and GST yielded the expected results. Transmission electron microscopy confirmed the uptake of beads coated with Mce3A or LprM by HeLa cells. The data showed that Mce3A encoded by the mce3 operon facilitated the uptake and internalization of latex beads by HeLa cells. The data also showed, for the first time, the role of another Mce protein (LprM/ Mce3E) in facilitating the interaction and internalization of M. tuberculosis by mammalian cells. INTRODUCTIONThe incidence of tuberculosis continues to climb, mostly in developing countries but also among select population groups in developed countries (Frieden et al., 2003). The World Health Organization has estimated that nearly onethird of the world population is now latently infected with Mycobacterium tuberculosis and 8-10 million people develop active disease resulting in 2 million deaths each year (Corbett et al., 2003;Frieden et al., 2003). Latent M. tuberculosis infection is achieved by strategies involving invasion and replication of the bacterium in host macrophages and blunting or modification of the host immune response, which eventually allows persistence of the dormant bacterium (Glickman & Jacobs, 2001;Hingley-Wilson et al., 2003). M. tuberculosis also has the ability to invade other non-phagocytic cells such as epithelial and endothelial cells (García-Pérez et al., 2003;Mehta et al., 2006). Furthermore, in situ PCR analyses of apparently normal human lung tissues have shown the presence of M. tuberculosis DNA in macrophages, dendritic cells and non-professional phagocytic cells such as type II pneumocytes, Hep-2 cells, endothelial cells and fibroblasts. These observations indicate intracellular pe...

A 45-year-old male presented with a large mass in the left axilla. FNA cytology was interpreted as Hodgkin's disease (HD), lymphocyte depletion (LD) type, but histopathologic and immunohistochemical examination showed features of Ki-1-positive anaplastic large cell lymphoma. Unrepresentative sampling by the FNA from the tumour periphery resulted in a false impression of dual reactive and neoplastic cell populations, which together with the frequent Reed-Sternberg-like cells led to the initial erroneous impression of HD. Therefore, the cytologic diagnosis of HD, LD should be approached with caution.

Renal aspergillomas have been reported only rarely. We report a case of Aspergillus flavus colonization of the renal pelvis and upper ureter of a patient with concomitant urinary schistosomiasis. The diagnosis was based on the demonstration of characteristic hyphal elements on direct microscopy and isolation of the fungus in culture. The patient was successfully treated with liposomal amphotericin B. This case emphasizes the importance of direct microscopic examination of urine specimens for prompt diagnosis of fungal infections of the urogenital system. Renal aspergilloma should be considered in the differential diagnosis of filling defects of the urinary tract, especially in patients who are immunocompromised.

Objective: To describe histological and ultrastructural changes of cardiomyocytes in experimental rats following subplantar administration of carrageenin. Material and Methods: In adult rats, an acute inflammatory reaction was induced by subplantar injection of 0.1 ml of 1% sterile carrageenin solution. In a total of 10 rats, which developed gangrene of tails in 5- to 12-cm-long segments, were killed and their internal organs fixed in 10% formaldehyde solution and subsequently processed for paraffin embedding. Later, blocks of the ventricular heart tissue were refixed and reprocessed for Araldite embedding and ultrastructure observation. Similarly, the cardiac muscle of control, carrageenin-injected rats which did not develop vascular thrombosis was processed. Results: The cardiomyocytes of rats injected with carrageenin showed focal dystrophic alterations, enlarged mitochondria with densely packed concentrically oriented cristae, and many dense and irregularly shaped deposits with microgranular helicoid organization. Normal cardiomyocytes were observed in control rats. Complicating thrombosis of tail blood vessels leading to extensive tail necroses were also histologically confirmed. Conclusion: These findings demonstrate specific pathogenic effect in the cardiovascular system of the carrageenin-treated rats.