Biology subjects

George, S.

Publications and source records attributed to George, S..

3 recordsLinked to original sources

bioRxiv2018

An algorithm for automated, noninvasive detection of cortical spreading depolarizations based on EEG simulations

We present a novel signal processing algorithm for automated, noninvasive detection of Cortical Spreading Depolarizations (CSDs) using electroencephalography (EEG) signals and validate the algorithm on simulated EEG signals. CSDs are waves of neurochemical changes that suppress neuronal activity as they propagate across the brains cortical surface. CSDs are believed to mediate secondary brain damage after brain trauma and cerebrovascular diseases like stroke. We address key challenges in detecting CSDs from EEG signals: (i) decay of high spatial frequencies as they travel from the cortical surface to the scalp surface; and (ii) presence of sulci and gyri, which makes it difficult to track the CSD waves as they travel across the cortex. Our algorithm detects and tracks \"wavefronts\" of the CSD wave, and stitches together data across space and time to decide on the presence of a CSD wave. To test our algorithm, we provide different models and complex patterns of CSD waves, including different widths of CSD suppressions, and use these models to simulate scalp EEG signals using head models of 4 subjects from the OASIS dataset. Our results suggest that the average width of suppression that a low-density EEG grid of 40 electrodes can detect is 1.1 cm, which includes a vast majority of CSD suppressions, but not all. A higher density EEG grid having 340 electrodes can detect complex CSD patterns as thin as 0.43 cm (less than minimum widths reported in prior works), among which single-gyrus propagation is the hardest to detect because of its small suppression area.

bioengineering↗

bioRxiv2018

Comparison of two commercial ELISA kits for detection of rubella specific IgM and IgG antibodies

Enzyme linked immunosorbent assay (ELISA) plays an important role in laboratory confirmation of congenital rubella syndrome (CRS), postnatal rubella and seroprevalence studies in different populations. Variation of results are documented for samples tested by different commercial kits. The Enzygnost rubella ELISA, widely used in the WHO network, is expensive and not readily available. In the present study, performance of the Euroimmun ELISA was compared to the Enzygnost ELISA for detection of rubella specific IgM and IgG antibodies.\n\nTwo hundred and eighty five serum samples collected from suspected CRS patients identified through a recently initiated surveillance for CRS at six sentinel hospitals and 435 serum samples from a serosurvey of pregnant women from these sites, were available for testing of rubella specific IgM and IgG antibodies respectively. Qualitative agreement (concordance percentage and Cohens Kappa coefficient -{kappa}) was evaluated for both IgM and IgG assays. Bland - Altman plots were used to assess the difference in quantitative agreement for IgG titers.\n\nGood qualitative agreement between the two ELISA kits was observed for detection of both anti rubella IgM (94.7% agreement and k of 0.86) and IgG (96.3% agreement and k of 0.84). Sensitivity and specificity of Euroimmun assays compared to Enzygnost was 100% and 93.1% for IgM and 95.9% and 100% for IgG respectively. Bland - Altman analysis for paired quantitative results of rubella specific IgG yielded a mean difference of 0.781 IU/ml with majority of values (97.1%) within {+/-} 2 SD of the mean difference. Euroimmun ELISA provided on an average, higher titers as compared to Enzygnost.\n\nOur study findings suggest that Euroimmun ELISA may be considered for detection of rubella specific IgM in suspected CRS cases and rubella specific IgG in surveillance studies.

microbiology↗

bioRxiv2017

Development of a targeted sequencing approach to identify prognostic, predictive and diagnostic markers in paediatric solid tumours

The implementation of personalised medicine in childhood cancers has been limited by a lack of clinically validated multi-target sequencing approaches specific for paediatric solid tumours. In order to support innovative clinical trials in high-risk patients with unmet need, we have developed a clinically relevant targeted sequencing panel spanning 311 kb and comprising 78 genes involved in childhood cancers. A total of 132 samples were used for the validation of the panel, including Horizon Discovery cell blends (n=4), cell lines (n=15), formalin-fixed paraffin embedded (FFPE, n=83) and fresh frozen tissue (FF, n=30) patient samples. Cell blends containing known single nucleotide variants (SNVs, n=528) and small insertion-deletions (indels n=108) were used to define panel sensitivities of [≥]98% for SNVs and [≥]83% for indels [95% CI] and panel specificity of [≥]98% [95% CI] for SNVs. FFPE samples performed comparably to FF samples (n=15 paired). Of 95 well-characterised genetic abnormalities in 33 clinical specimens and 13 cell lines (including SNVs, indels, amplifications, rearrangements and chromosome losses), 94 (98.9%) were detected by our approach. We have validated a robust and practical methodology to guide clinical management of children with solid tumours based on their molecular profiles. Our work demonstrates the value of targeted gene sequencing in the development of precision medicine strategies in paediatric oncology.

genomics↗