Browsing by Author "Ghandorah, Salim"

Now showing 1 - 2 of 2
  • Thumbnail Image
    ItemOpen Access
    Analyzing the Nanomechanical Oscillations of Brain Tumor Cells using Optical Tweezers
    (2019-01-02) Ghandorah, Salim; Amrein, Matthias; Ghasemloonia, Ahmad; Green, Francis H. Y.; Mahoney, Douglas J.
    Under the microscope, cells manifest nanomechanical oscillations (also known as vibrations and fluctuations). While the exact source of these oscillations is unknown, they may reflect the numerous inherent active processes of living cells. The sum of these active processes of cell characterizes its phenotype and function. Therefore, we hypothesize that the oscillation spectrum is unique for each cell type, and reflective of its functional state, allowing phenotypically-different cell types to be differentiated and functional changes in the cells to be followed. To test this hypothesis, we employed a novel, highly sensitive tool, optical tweezers, to record the oscillations of two brain tumor cells and applied advanced multivariate analysis to statistically evaluate the difference between the oscillation spectra. Two main sub aims were addressed; (1) To find optimal conditions for the optical tweezers setup for single cell oscillation measurements, and (2) To establish statistical methods to differentiate cells based on their oscillation patterns. Our results showed feature-rich spectra of different cell types over a frequency range from a few Hertz (Hz) to 50 kHz. The multivariate analysis generated two separate clusters for each cell type. The analysis also allowed evaluation of the spectra for features that are strongly associated with differences and the features that are common among cells. My thesis expands the current knowledge of cellular oscillations. While previous studies demonstrated a correlation between the metabolic activity of cells and overall magnitude of oscillations, spectral decomposition was either not reported or showed few, if any, cell-specific frequencies. In conclusion, the recording of oscillation spectra of single cells using optical tweezers, followed by multivariate statistical analysis is a promising method to differentiate cell types and follow cellular functions in real-time.
  • Thumbnail Image
    ItemOpen Access
    Characteristics of Donor-Specific anti-HLA Antibodies (DSA) Impacting different Renal Allograft Outcomes
    (2015-04-20) Ghandorah, Salim; Berka, Noureddine; Khan, Faisal
    AMR is the major complication of renal transplantation that significantly affects the allograft survival. Complement fixation of Donor specific anti-HLA antibodies is the hallmark of AMR. Different methods have been developed to detect harmful DSAs. However, not all DSAs have the same detrimental effect, as different antibody characteristics (timing, specificity, strength, and complement-fixing ability) might trigger distinct immune responses. Here, we assessed DSA characteristics in renal transplant patients. Thirty-nine patients with de novo DSA were analyzed for the DSA MFI values, C1q positivity and IgG subclasses. IgG1 was the predominant IgG subclass (49.4%), followed by IgG3 (24.7%), IgG2 (16%), and IgG4 (9.9%). Among DSA characteristics, DSA MFI and IgG1 subclass were strongly correlated with C1q positivity (p= 0.01 and p= 0.009, respectively). Further studies are needed to investigate the clinical relevance of high MFI DSA and IgG1 subclass in improving the utility of the C1q assay in predicting graft outcomes.