Showing papers by "Milan Mazúr published in 1997"
TL;DR: Movement of line-like samples with lengths from 5 to 50 mm along the x-axis of the double TE104 rectangular cavity has been analyzed and the correlation between observed and theoretically predicted dependencies is very good.
29 citations
TL;DR: In this paper, the salen complex CuL and the corresponding tetrahydrosalen complex H4]L were investigated by ESR spectroscopy and molecular orbital calculations, and X-ray structure determination of CuL confirmed a slightly distorted planar geometry of the CuN2O2 coordination core.
23 citations
TL;DR: The observation of 1H NMR ceramide resonance in high-malignant brain tumors emphasizes the dramatic role of aberrant gangliosides and ceramide precursors on the grade of malignancy and invasiveness.
Abstract: 1. The high-resolution 1H NMR (MRS) spectra of human brain tumor homogenates revealed a broad resonance at 5.3-5.4 ppm in glioblastoma multiforme (N = 16) and brain metastases (N = 3). The broad resonance was identified as ceramide, a sphingosine-fatty acid combination portion of ganglioside, indicating an elevated abundance of monounsaturated fatty acids. GLC analysis of gangliosides in the highly malignant glioblastoma multiforme revealed that the elevated monounsaturated fatty acid is oleic acid (C18:1). The resonance at 5.3-5.4 ppm region was not detectable in normal human brain (N = 2), in meningiomas (N = 2), or in low-grade astrocytomas (N = 12). In normal human brain the abundance of monounsaturated fatty acid is minimal. 2. This investigation was made possible because the method of producing homogenate resulted in (i) no loss of lipids during the process and (ii) a well-homogenised sample, with (iii) no loss in chemical integrity. 3. The properties of tumor gangliosides include antigenic specificity and immunosuppressive activity and the ceramide, a sphingosine-fatty acid combination, noticeably influences the ganglioside immunosuppressive activity. 4. The observation of 1H NMR ceramide resonance in high-malignant brain tumors emphasizes the dramatic role of aberant gangliosides and ceramide precursors on the grade of malignancy and invasiveness. 5. Further insight into the specific nature of the ceramide portion of gangliosides in grading the malignancy of brain tumors should be investigated further.
10 citations
TL;DR: In this article, a modification to the previously described sample alignment tool which allowed the precise and reproducible positioning of cylindrical samples along the vertical central axis of the rectangular cavity is described.
Abstract: A significant source of errors in quantitative electron paramagnetic resonance measurements is incorrect sample positioning in the microwave cavity. In this article a modification to our previously described sample alignment tool which allowed the precise and reproducible positioning of cylindrical samples along the vertical central axis of the rectangular cavity is described. These revisions allow cylindrical sample movement in the horizontal (y,z) plane which is perpendicular to the cavity x axis. Using this upgrade, the new sample setup procedure is now able to position samples precisely and reproducibly at arbitrary points in the intracavity space.
10 citations