Identification and optimization of pyridine carboxamide-based scaffold as a drug lead for Mycobacterium tuberculosis

New drugs with novel mechanisms of action are urgently needed to tackle the issue of drug-resistant tuberculosis. Here, we have performed phenotypic screening using the Pathogen Box library obtained from the Medicines for Malaria Venture against Mycobacterium tuberculosis in vitro. We have identified a pyridine carboxamide derivative, MMV687254, as a promising hit. This molecule is specifically active against M. tuberculosis and Mycobacterium bovis Bacillus Calmette-Guérin (M. bovis BCG) but inactive against Enterococcus faecalis, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumanii, Pseudomonas aeruginosa, and Escherichia coli pathogens. We demonstrate that MMV687254 inhibits M. tuberculosis growth in liquid cultures in a bacteriostatic manner. Surprisingly, MMV687254 was as active as isoniazid in macrophages and inhibited M. tuberculosis growth in a bactericidal manner. Mechanistic studies revealed that MMV687254 is a prodrug and that its anti-mycobacterial activity requires AmiC-dependent hydrolysis. We further demonstrate that MMV687254 inhibits M. tuberculosis growth in macrophages by inducing autophagy. In the present study, we have also carried out a detailed structure-activity relationship study and identified a promising novel lead candidate. The identified novel series of compounds also showed activity against drug-resistant M. bovis BCG and M. tuberculosis clinical strains. Finally, we demonstrate that in contrast to MMV687254, the lead molecule was able to inhibit M. tuberculosis growth in a chronic mouse model of infection. Taken together, we have identified a novel lead molecule with a dual mechanism of action that can be further optimized to design more potent anti-tubercular agents.

Bilateral ptosis: An unusual presentation of mid brain tuberculoma

Central nervous system tuberculoma can have different clinical manifestations like headache, seizures, papilledema or other signs of raised intracranial pressure depending up on the site and number of tuberculoma. We report a case of 56 year old female reported with history of bilateral asymmetric ptosis of one month duration,with no other neurological defecit. Magnetic resonance imaging (MRI) brain revealed well defined ring enhancing lesion in the medial aspect of left hemi midbrain with diffuse disproportionate perilessional edema. Contrast Enhanced Computed Tomogram (CECT) of chest and abdomen revealed features of disseminated tuberculosis. She was diagnosed as a case of disseminated tuberculosis and started on antitubercular therapy with steroids and the ptosis almost resolved after 01 month of antitubercular therapy. Our case report is unique in the sense that only few cases of midbrain tuberculoma causing occulomotor abnormalities are reported in literature.

Profile of burn sepsis challenges and outcome in an exclusive children's hospital in Chennai, India

A group of 273 paediatric patients admitted to Kanchi Kamakoti Childs Trust Hospital Burn Unit, Chennai, India between the years 2004 to 2010 were analysed retrospectively. Of these, 89 were suffering from sepsis and septic shock and 15 died. Strict adherence to antibiotic administration and to the Paediatric Intensive Care Unit (PICU) and management protocol improved the outcome, especially in 2009 and 2010.

Steroid-unresponsive hypereosinophilic syndrome

Hypereosinophilic syndrome in children is rare and is characterised by sustained over-production of eosinophils. An 11-year-old boy was diagnosed with hypereosinophilic syndrome as per standard criteria. He was treated initially with intravenous methylprednisolone, followed by oral prednisolone, to which he showed a limited response. The highest absolute eosinophil count was 27.0×10(9)/L. He was commenced on imatinib mesylate but, because of no response, he was switched to hydroxyurea combined with low-dose prednisolone to which he showed improvement with decreasing levels of eosinophils.

Doping Induced Internal Stress Reduction in Diamondlike Carbon Films Deposited by Pulsed Laser Ablation

We have investigated the effect of dopants on the reduction of internal compressive stress in diamond-like carbon (DLC) films prepared by pulsed laser deposition on Si(100) substrates. A novel target configuration was used to incorporate dopants into DLC films by sequential pulsed laser ablation of two targets. These dopants include copper, titanium and silicon. The thickness of the DLC films deposited was measured in the range 400nm - 600nm using a profilometer. Raman spectroscopy was employed to analyze the chemistry of the films. The shifts of the G-peak position in the Raman spectrum, due to different concentrations of dopant, were used to estimate the internal stress changes. All of the films showed a Raman spectrum typical of DLC films containing a high fraction of sp3 species, with the G-peak centered at around 1510–1560cm−1. The shift of the G-peak due to the presence of dopants was observed for all the DLC films as compared to the undoped one. It was found that Ti has the strongest tendency to reduce the compressive stress of DLC films. This effect increases with increasing concentration of dopants. Silicon was also observed to have this effect, but the G-peak position did not appear to shift with different Si concentrations. Buckling occurred in the as-deposited, undoped DLC film because of the relief of the large compressive stress accumulated in the film, while all the doped DLC films showed good adhesion to the substrate. The results are discussed combining the atomic structure of DLC and the structure and properties of the dopants.

Profile of children abused by burning

In an analysis of paediatric burn admissions to a hospital in India during the years 1992-2007, 9.3% of burn injuries were found to be secondary to abuse. These had valid documented evidence and child neglect was excluded. This incidence of child abuse has been on the rise in the last seven years and was more evident due to careful investigation by a team comprising a plastic surgeon, a paediatrician, a legal expert, a psychologist, and a social worker. As with the incidence reported by many other researchers, most of the injuries were caused by scalding.

Boron Carbide-Silicon Carbide Laminated Ceramics for Ballistic Protection

The paper describes the development of tough boron carbide-silicon carbide ceramic laminates with enhanced ballistic performance for armor application. Laminates with strong interfaces can provide high fracture toughness and damage tolerance along with improved ballistic protection. The enhancement of the mechanical/ballistic performance of laminates is obtained through design of controlled residual stresses in separate layers. The research produced a fundamental knowledge of the interrelationships between processing, residual stresses, and mechanical behavior of boron carbide based multilayered ceramic composites with an enhanced understanding of laminate’s fracture toughness, strength, and Young’s modulus. It was expected that the newly developed laminates would have necessary mechanical properties to increase maximum critical velocity of dwell/penetration transition during impact experiments.

Core-modified hexaphyrins; characterization of two- and four-ring inverted 26 pi aromatic macrocycles

[reaction: see text] Synthesis and structural characterization of aromatic core-modified 26 pi hexaphyrin analogues are reported.

Porphyrins in photodynamic therapy - a search for ideal photosensitizers

The utility of light as a therapeutic agent can be traced back over thousands of years when it was used in Ancient Egypt, India and China to treat a variety of skin diseases like psoriasis, vitiligo, rickets, cancer and psychosis. The isolation of porphyrins and their inherent tumor localizing properties coupled with its ability to generate reactive singlet oxygen when activated by light of particular wavelength which in turn results in cytotoxicity led to the emergence of a new modality namely, photodynamic therapy (PDT) as a therapeutic tool. The higher degree of selectivity offered by this modality and fewer side effects when compared to chemotherapy and radiotherapy has prompted the researchers around the globe to generate new photosensitizers. Porphyrins and expanded porphyrins are one class of molecules under intense investigation due to their photosensitizing ability for PDT application. Expanded porphyrins result from the expansion of the phi electron conjugation by increasing the number of heterocyclic rings or bridging carbons of the existing porphyrin framework. These chromophores show strong absorptions in the red region (650-800 nm) compared to that of normal 18phi porphyrins. The strong absorption of light by a water soluble nontoxic photosensitizing molecule in the therapeutic window resulting in maximum penetration of light into the tissues coupled with high singlet oxygen production will conceptualize an ideal photosensitizer. This review highlights various porphyrinoid sensitizers reported till date and their photosensitizing ability both in vitro and in vivo studies. Furthermore, the urgent need for developing ideal photosensitizer for PDT will also be highlighted.