Parametric geometry modeling of the carotid artery bifurcation: the need for new flow metrics
Although well established correlations now exist between regions of reversed flow and sites of arterial disease [1], little evidence is available for methodologies that systematically compare how geometrical differences affect such relationships. Drawing on techniques developed in aerodynamic design, a parametric tuning-fork geometry model of the carotid artery bifurcation - based on the glass models described in [2] - is here employed to investigate the impact of bulb size and the angle of the internal carotid artery (ICA) on time-averaged shear stress. Since we seek to directly compare the effect of varying these geometric parameters, we demonstrate the need for a new metric, the integral of negative mean shear stress (INMSS), to highlight the stronger correlation between the extent of reversed flow and bulb width relative to the angle of the ICA.
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Toluene degradation via a unique metabolic route in indigenous bacterial species
Tanneries are the primary source of toluene pollution in the environment and toluene due to its hazardous effects has been categorized as persistent organic pollutant. Present study was initiated to trace out metabolic fingerprints of three toluene-degrading bacteria isolated from tannery effluents of Southern Punjab. Using selective enrichment and serial dilution methods followed by biochemical, molecular and antibiotic resistance analysis, isolated bacteria were subjected to metabolomics analysis. GC–MS/LC–MS analysis of bacterial metabolites helped to identify toluene transformation products and underlying pathways. Three toluene-metabolizing bacteria identified as Bacillus paralicheniformis strain KJ-16 (IUBT4 and IUBT24) and Brevibacillus agri strain NBRC 15538 (IUBT19) were found tolerant to toluene and capable of degrading toluene. Toluene-degrading potential of these isolates was detected to be IUBT4 (10.35 ± 0.084 mg/h), IUBT19 (14.07 ± 3.14 mg/h) and IUBT24 (11.1 ± 0.282 mg/h). Results of GC–MS analysis revealed that biotransformation of toluene is accomplished not only through known metabolic routes such as toluene 3-monooxygenase (T3MO), toluene 2-monooxygenase (T2MO), toluene 4-monooxygenase (T4MO), toluene methyl monooxygenase (TOL), toluene dioxygenase (Tod), meta- and ortho-ring fission pathways. But additionally, confirmed existence of a unique metabolic pathway that involved conversion of toluene into intermediates such as cyclohexene, cyclohexane, cyclohexanone and cyclohexanol. LC–MS analysis indicated the presence of fatty acid amides, stigmine, emmotin A and 2, 2-dinitropropanol in supernatants of bacterial cultures. As the isolated bacteria transformed toluene into relatively less toxic molecules and thus can be preferably exploited for the eco-friendly remediation of toluene.