Quantitative Determination of Plasmodium Parasitemia by Flow Cytometry and Microscopy

The traditional light microscopy has limitations for precise growth assays of malaria parasites in culture or for assessment of new compounds for antimalarial activity; the speed and high reproducibility of flow cytometry can overcome these limitations. A flow cytometric method using PicoGreen, a DNA-binding fluorochrome, was developed with optimal precision suitable for performing growth assays of low-parasitemia field isolates. In addition, intra- and inter-person reproducibility of the flow cytometric and the microscopic method were compared in order to quantitatively demonstrate the improved precision. RNase treatment contributed to the precision of the flow cytometric measurements by enhancing the signal-to-noise ratios. Coefficients of variation of the method were smaller than 10% for 0.1% or higher parasitemia samples. The intra- and inter-person coefficients of variation of the flow cytometric method were three to six times smaller than those of the microscopic method. The flow cytometric method developed in this study yielded substantially more precise results than the microscopic method, allowing determination of parasitemia levels of 0.1% or higher, with coefficients of variation smaller than 10%. Thus, the PicoGreen method could be a reliable high sensitivity assay for analysis of low parasitemia samples and might be applied to a high throughput system testing antimalarial drug activity.

Effect of Rapamycin on the Cell Cycle Arrest of T Lymphocytes

PURPOSE: Rapamycin (RPM) and its analogues are known for their potent immunosuppressant and anti-proliferative properties, which stem from their ability to modulate the signal transduction pathways involved in cell cycle progression from the G1 to S phase. Thus, RPM has been shown to inhibit the proliferation of a number of non-immune cell types, including hepatocytes, vascular smooth cells and fibroblasts. In addition to its effects on proliferation, RPM may also play a role in the regulation of apoptosis under certain circumstances. METHODS: The effects of RPM on the activation, proliferation and expression of cytotoxic effector molecules were examined on Molt-4 human T-lymphocyte by determining its effects on apoptosis, cell viability, reactive oxygen species (ROS) production and mitochondrial dysfunction. Cells were cultured in the presence or absence of RPM, and then analyzed by Flow cytometry after staining with PI (propidium iodide). RESULTS: The viability of Molt-4 T cells dose- and time-dependently decreased on the addition of RPM. CONCLUSION: RPM induced cytotoxicity was characterized by G2/M phase cell cycle arrest. In addition, a pharmacological scavenging study of ROS, including H2O2, revealed the cytotoxicity was mainly induced by the generation of ROS, which might modulate the expression of Bak protein and mitochondrial dysfunction.

A case report of pigmented dermatofibrosarcoma protuberans (Bednar tumor)

Bednar tumor was described by Bednar in 1957. The histologic pattern of this tumor shows similar to dermatofibrosarcoma protuberans (DFSP) but melanin pigments are scattered within the tumor, It's rare neoplasm accounting for approximately 1-5% of all case of DFSP. Clinically, this tumor is considered to be intermediated malignancy, because of slow growth and frequent local recurrence and lack of distant metastasis. The majority are located on the trunk and the upper and lower extremities, but extremely rate in the head and neck area. Microscopically, this tumor is characterized by tight storiform spindle cells and long slender cells that admixed with a small population of melanin containing dendritic cells. This dendritic cells are the primary features distinguising this lesion from conventional DFSP. Complete surgical excision and close follow-up case are necessany for this neoplasm because of probable intermediate malignancy. A patient was admitted to Our Department of Oral and Maxillofacial Surgery due to swelling on right parotid area and numbness of the right lower lip on September, 1994, By clinical examinations and C-T finding, we dignosed tentatively as myxoma or pleomorphic adenoma. Surgical excision of this tumor was performed with parotidectomy and mandibular osteotomy under the frozen biopsy. By final microscopic and electromicroscopic examination and immunohistochemical study, this tumor was diagnosed as Bednar tumor. So, we report a case of pigmented DFSP with review of literatures.