Development of NMR and thermal shift assays for the evaluation of Mycobacterium tuberculosis isocitrate lyase inhibitors.

The enzymes isocitrate lyase (ICL) isoforms 1 and 2 are essential for Mycobacterium tuberculosis survival within macrophages during latent tuberculosis (TB). As such, ICLs are attractive therapeutic targets for the treatment of tuberculosis. However, there are few biophysical assays that are available for accurate kinetic and inhibition studies of ICL in vitro. Herein we report the development of a combined NMR spectroscopy and thermal shift assay to study ICL inhibitors for both screening and inhibition constant (IC50) measurement. Operating this new assay in tandem with virtual high-throughput screening has led to the discovery of several new ICL1 inhibitors

Acetyl-CoA-mediated activation of Mycobacterium tuberculosis isocitrate lyase 2

Isocitrate lyase is important for lipid utilisation by Mycobacterium tuberculosis but its ICL2 isoform is poorly understood. Here we report that binding of the lipid metabolites acetyl-CoA or propionyl-CoA to ICL2 induces a striking structural rearrangement, substantially increasing isocitrate lyase and methylisocitrate lyase activities. Thus, ICL2 plays a pivotal role regulating carbon flux between the tricarboxylic acid (TCA) cycle, glyoxylate shunt and methylcitrate cycle at high lipid concentrations, a mechanism essential for bacterial growth and virulence

Patient-specific RF safety assessment in MRI: Progress in creating surface-based human head and shoulder models

The interaction of electromagnetic (EM) fields with the human body during magnetic resonance imaging (MRI) is complex and subject specific. MRI radiofrequency (RF) coil performance and safety assessment typically includes numerical EM simulations with a set of human body models. The dimensions of mesh elements used for discretization of the EM simulation domain must be adequate for correct representation of the MRI coil elements, different types of human tissue, and wires and electrodes of additional devices. Examples of such devices include those used during electroencephalography, transcranial magnetic stimulation, and transcranial direct current stimulation, which record complementary information or manipulate brain states during MRI measurement. The electrical contact within and between tissues, as well as between an electrode and the skin, must also be preserved. These requirements can be fulfilled with anatomically correct surface-based human models and EM solvers based on unstructured meshes. Here, we report (i) our workflow used to generate the surface meshes of a head and torso model from the segmented AustinMan dataset, (ii) head and torso model mesh optimization for three-dimensional EM simulation in ANSYS HFSS, and (iii) several case studies of MRI RF coil performance and safety assessment

Frequency Dependence of Hearing Loss with Perforations

Abstrac

Complications of Chronic Suppurative Otitis Media AA Type-3 Years Experience at TUTH

This retrospective study was carried out in the Department of ORL and Head & Neck Surgery, Tribhuvan University Teaching Hospital, Maharajgunj, Kathmandu. Three hundred patients having atticoantral type of chronic suppurative otitis media underwent emergency or routine mastoid exploration from 14 April 1997 to 12 April 2000. Of the 300 patients, 64 (21.33%) had complications. Age of the patients with complications ranged from 5-38 years. Thirty eight (59.38%) patients were male while 26 (40.62%) were female. Forty eight (75%) had extracranial and 15 (23.44%) had intracranial complications while 1 (2.08%) had both extra and intracranial complications. Cholesteatoma was present in 233 (77.66%) patients and of these 48 (20.60%) had complications. Sixty seven (22.33%) patients had granulation tissue, of these 16 (23.88%) had complications.In cholesteatomatous cases 34 (70.83%) had extracranial complications. Intracranial complications were present in 14(29.17%) cholesteatomatous cases. In patients with granulation tissue extracranial complication was present in 14 (87.50%) patients and only one patient had intracranial complication.Combination of extra and intracranial complications were found in 1 patient with granulation tissue. When compared with types of pathology extracranial complications were higher in patients with granulation tissue (87.50% vs 70.83%) and intracranial complications were found more in cholesteatomatous cases (29.17% vs 6.26%). Both these findings were , however, statistically not significant. Reasons behind these findings may be presence of granulation tissue beneath the epithelium of choleateatoma, and association of both types of pathology with infection and inflammatory process. Key Words: Chronic Suppurative Otitis Media, Atticoantral Type, Mastoid Exploration, Complications