Isolation of Acanthamoeba isolates belonging to T2, T3, T4 and T7 genotypes from environmental samples in Ankara, Turkey

Acanthamoeba keratitis is a blinding infection that is becoming increasingly important in human health. Early diagnosis is a prerequisite for successful treatment and requires identification of Acanthamoeba at the genotypic level. The genus Acanthamoeba consists of both pathogenic and non-pathogenic species and has been recently classified into 13 different genotypes, T1-T12 and T14. More importantly, 95% of Acanthamoeba isolates that produce keratitis belong to T4 genotypes. In this study, we attempted to determine whether predominance of T4 isolates in Acanthamoeba keratitis is due to greater virulence or greater prevalence. We isolated 18 Acanthamoeba isolates from environmental samples in Ankara, Turkey and determined their pathogenic potential by means osmotolerance, temperature tolerance and in vitro cytotoxicity assays using corneal epithelial cells. Ribosomal DNA sequencing revealed that 10 isolates belong to T2, 5 belong to T3, 2 belong to T4 and one belongs to T7 genotype. As expected, T3 and T4 isolates exhibited the most pathogenic traits and were osmotolerant, temperature tolerant and exhibited severe corneal epithelial cell cytotoxicity indicating their pathogenic potential. Overall these data indicate that high frequency of T4 isolates in keratitis cases may well be due to their greater virulence. This is the first report presenting environmental distribution of Acanthamoeba in Ankara, Turkey

Acanthamoeba castellanii induces host cell death via a phosphatidylinositol 3-kinase-dependent mechanism

Granulomatous amoebic encephalitis due to Acanthamoeba castellanii is a serious human infection with fatal consequences, but it is not clear how the circulating amoebae interact with the blood-brain barrier and transmigrate into the central nervous system. We studied the effects of an Acanthamoeba encephalitis isolate belonging to the T1 genotype on human brain microvascular endothelial cells, which constitute the blood-brain barrier. Using an apoptosis-specific enzyme-linked immunosorbent assay, we showed that Acanthamoeba induces programmed cell death in brain microvascular endothelial cells. Next, we observed that Acanthamoeba specifically activates phosphatidylinositol 3-kinase. Acanthamoeba-mediated brain endothelial cell death was abolished using LY294002, a phosphatidylinositol 3-kinase inhibitor. These results were further confirmed using brain microvascular endothelial cells expressing dominant negative forms of phosphatidylinositol 3-kinase. This is the first demonstration that Acanthamoeba-mediated brain microvascular endothelial cell death is dependent on phosphatidylinositol 3-kinase

Determination of the scale of pattern and distribution in Helicteres isora L (Sterculiaceae)

Helicteres isora L. is a traditional multipurpose plant used by indigenous community and villagers inall the three major climatic zones in Sri Lanka. It naturally occurs in the edges of forests and indisturbed secondary vegetation. It is fastly disappearing in the wet zone due to land clearing and highextraction rates. The present study was conducted to understand the pattern and the scale of distributionof H. isora in order to provide information for biodiversity conservation and further to enable thesustainable use.Twelve natural populations were identified in wet, intermediate and dry zones and the distribution ofindividuals was studied using gradient directed transect method. The t test was performed for eachpopulation to detect the pattern of distribution and pattern analysis was carried out to determine thescale of pattern.Out of twelve populations surveyed, only five populations showed contagious distribution (p < 0.05)while seven populations showed random pattern of distribution. This indicates that the populations ofH isora do not fall into a particular pattern of distribution in nature. This may be due to the highdisturbance present in and around the populations.The results of the pattern analysis reveal more peaks in smaller block sizes (2m2) and larger blocksizes (32m2) indicating aggregated pattern in respective block sizes. Peaks in smaller block sizes aredue to the morphology of the plant as it produces new plants from roots. Peaks at larger block sizesare due to the extrinsic factors and these results could be utilized in the in- situ conservation of Hisora .

Histoplasmosis in Sri Lanka - a masquerader in a strange land: A Case Report

We present a patient with an oral mucosal ulcer who was diagnosed with disseminated histoplasmosis. This fungal infection is endemic in the United States, and thus may be not considered in the differential diagnosis of oral ulcers in Sri Lanka. Furthermore, it may mimic many common diseases found in Sri Lanka. It is therefore important to be aware of this entity, since it is potentially curable if diagnosed and treated early.</p