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Biomedical subjects

A Doulis

Publications and source records attributed to A Doulis.

3 recordsLinked to original sources

Dermatofibrosarcoma protuberans occuring in a child.

Dermatofibrosarcoma protuberans (DFSP) usually occurs in adults, however it can also occur in infancy and childhood. Diagnosis of DFSP in children is quite difficult given the rarity of the tumor and its variegated appearance. The behavior of this neoplasm is of borderline or intermediate malignancy with a high rate of recurrence but limited metastatic potential. We present the case of an eleven-year old boy who presented with a slightly raised, not tender lesion on his right shoulder. It had appeared two years before as a red-brown plaque and since then it had gradually grown to a nodule. An excisional biopsy was performed, and the diagnosis of DFSP was made based on the histological and immunohistochemical findings.

Biopsy↗

Separation of plant membrane lipids by multiple solid-phase extraction.

Plant membrane lipids were separated by multiple solid-phase extraction (SPE) in a single run. Elution was performed continuously through the modulated stationary phase employing only non-aqueous solvent systems. At the different stages of the glycerolipid separation the SPE manifold combined arninopropyl, arninopropyl/silica gel and silica gel/aminopropyl weak anion exchanger columns. The glycerolipid extract of pigment-containing plant tissues was cleared from the pigments onto the aminopropyl column. The aminopropyl column with the glycerolipid extract was then connected to a silica gel column from which monogalactosyldiacylglycerol, phosphatidylethanolamine, phosphatidylglycerol and digalactosyldiacylglycerol were eluted as individual fractions. The elution was performed under polarity, pH and temperature gradient conditions. To continue the separation, the aminopropyl column was discarded and the silica gel column containing the remaining glycerolipid extract was connected to an aminopropyl anion exchanger column. Individual fractions of sulfoquinovosyldiacylglycerol, phosphatidylcholine and phosphatidylinositol were now eluted. The separation process was supported by ammonium counter ions and by the polarity gradient of the elution systems used. The membrane lipids were isolated from pigment-containing (rice and maize leaves and rice leafy stems) and pigment-free (rice roots) tissues. The repeatability for a standard glycerolipid mixture was 2-6% (n=7), and for rice leaf lipid extracts, 3-7% (n=5). Glycerolipid recovery was 87-95%.

Chromatography, Thin Layer↗

Determination of glycerolipid composition of rice and maize tissues using solid-phase extraction.

Currently available techniques for the separation and characterization of different glycerolipids are complicated and/or time consuming. By modulating the stationary phase in a solid-phase extraction (SPE) manifold, efficient and rapid separation of plant membrane lipids was achieved. The glycerolipids from rice and maize tissues were separated into seven classes (monogalactosyldiacylglycerol, digalactosyldiacylglycerol, phosphatidylethanolamine, phosphatidylcholine, sulphoquinovosyldiacylglycerol, phosphatidylinositol and phosphatidylglycerol). The pigments present in the rice and maize leaves and rice stems were successfully removed from the total lipid extracts. Pigment-free plant tissue (rice roots) was also analysed. The fatty acid profile of each lipid class isolated by SPE agreed well with those obtained by other separation techniques. The recovery of glycerolipids was at least 87%.

Fatty Acids↗