Identification of a chemical that inhibits the mycobacterial UvrABC complex in nucleotide excision repair

Bacterial DNA can be damaged by reactive nitrogen and oxygen intermediates (RNI and ROI) generated by host immunity, as well as by antibiotics that trigger bacterial production of ROI. Thus a pathogen's ability to repair its DNA may be important for persistent infection. A prominent role for nucleotide excision repair (NER) in disease caused by Mycobacterium tuberculosis (Mtb) was suggested by attenuation of uvrB-deficient Mtb in mice. However, it was unknown if Mtb's Uvr proteins could execute NER. Here we report that recombinant UvrA, UvrB, and UvrC from Mtb collectively bound and cleaved plasmid DNA exposed to ultraviolet (UV) irradiation or peroxynitrite. We used the DNA incision assay to test the mechanism of action of compounds identified in a high-throughput screen for their ability to delay recovery of M. smegmatis from UV irradiation. 2-(5-Amino-1,3,4-thiadiazol-2-ylbenzo[f]chromen-3-one) (ATBC) but not several closely related compounds inhibited cleavage of damaged DNA by UvrA, UvrB, and UvrC without intercalating in DNA and impaired recovery of M. smegmatis from UV irradiation. ATBC did not affect bacterial growth in the absence of UV exposure, nor did it exacerbate the growth defect of UV-irradiated mycobacteria that lacked uvrB. Thus, ATBC appears to be a cell-penetrant, selective inhibitor of mycobacterial NER. Chemical inhibitors of NER may facilitate studies of the role of NER in prokaryotic pathobiology.     

Biotransformation of (20S)-20-hydroxymethylpregna-1,4-dien-3-one by four filamentous fungi

Microbial transformation of (20S)-20-hydroxymethylpregna-1,4-dien-3-one (1) by four filamentous fungi, Cunninghamella elegans, Macrophomina phaseolina, Rhizopus stolonifer, and Gibberella fujikuroi, afforded nine new, and two known metabolites 2–12. The structures of these metabolites were characterized through detailed spectroscopic analysis. These metabolites were obtained as a result of biohydroxylation of 1 at C-6β, -7β, -11α, -14α, -15β, -16β, and -17α positions, except metabolite 2 which contain an O-acetyl group at C-22. These fungal strains demonstrated to be efficient biocatalysts for 11α-hydroxylation. Compound 1, and its metabolites were evaluated for the first time for their cytotoxicity against the HeLa cancer cell lines, and some interesting results were obtained.     

Interaction Between Selenium and Mercury in Biological Samples of Pakistani Myocardial Infarction Patients at Different Stages as Related to Controls

It has been speculated that trace elements may a play role in the pathogenesis of heart diseases. In the present study, we aimed to assess the levels of selenium (Se) and mercury (Hg) in biological samples (whole blood, urine, and scalp hair) of myocardial infarction (MI) patients of both genders (age range 45–60 years) at the first, second, and third heart attack (n?=?130), hospitalized in a cardiac ward of a civil hospital of Hyderabad City (Pakistan). For comparison, healthy age-matched referent subjects (n?=?61) of both genders were also selected. Se and Hg in biological samples were measured by electrothermal atomic absorption spectrometry and cold vapor atomic absorption spectrometry, prior to microwave acid digestion, respectively. The validity of the methodology was checked by biological certified reference materials. During this study, 78 % of the 32 registered patients of third MI attack (aged >50 years) died. The concentration of Se was decreased in scalp hair and blood samples of MI patients, while Hg was higher in all biological samples as compared to referent subjects. Se concentration was inversely associated with the risk of MI attacks in both genders. These results add to an increasing body of evidence that Se is a protective element for cardiovascular health.     

Viral respiratory infections among Hajj pilgrims in 2013

Middle East respiratory syndrome coronavirus(MERS-Co V) has emerged in the Arabian Gulf region, with its epicentre in Saudi Arabia, the host of the ‘Hajj' which is the world's the largest mass gathering. Transmission of MERS-Co V at such an event could lead to its rapid worldwide dissemination. Therefore, we studied the frequency of viruses causing influenza-like illnesses(ILI) among participants in a randomised controlled trial at the Hajj 2013. We recruited 1038 pilgrims from Saudi Arabia, Australia and Qatar during the first day of Hajj and followed them closely for four days. A nasal swab was collected from each pilgrim who developed ILI. Respiratory viruses were detected using multiplex RT-PCR. ILI occurred in 112/1038(11%) pilgrims. Their mean age was 35 years, 49(44%) were male and 35(31%) had received the influenza vaccine pre-Hajj. Forty two(38%) pilgrims had laboratory-confirmed viral infections; 28(25%) rhinovirus, 5(4%) influenza A, 2(2%) adenovirus, 2(2%) human coronavirus OC43/229 E, 2(2%) parainfluenza virus 3, 1(1%) parainfluenza virus 1, and 2(2%) dual infections. No MERS-Co V was detected in any sample. Rhinovirus was the commonest cause of ILI among Hajj pilgrims in 2013. Infection control and appropriate vaccination are necessary to prevent transmission of respiratory viruses at Hajj and other mass gatherings.     

Novel Non-Peptide Inhibitors against SmCL1 of Schistosoma mansoni: In Silico Elucidation,Implications and Evaluation via Knowledge Based Drug Discovery

Schistosomiasis is a major endemic disease known for excessive mortality and morbidity in developing countries. Because praziquantel is the only drug available for its treatment, the risk of drug resistance emphasizes the need to discover new drugs for this disease. Cathepsin SmCL1 is the critical target for drug design due to its essential role in the digestion of host proteins for growth and development of Schistosoma mansoni. Inhibiting the function of SmCL1 could control the wide spread of infections caused by S. mansoni in humans. With this objective, a homology modeling approach was used to obtain theoretical three-dimensional (3D) structure of SmCL1. In order to find the potential inhibitors of SmCL1, a plethora of in silico techniques were employed to screen non-peptide inhibitors against SmCL1 via structure-based drug discovery protocol. Receiver operating characteristic (ROC) curve analysis and molecular dynamics (MD) simulation were performed on the results of docked protein-ligand complexes to identify top ranking molecules against the modelled 3D structure of SmCL1. MD simulation results suggest the phytochemical Simalikalactone-D as a potential lead against SmCL1, whose pharmacophore model may be useful for future screening of potential drug molecules. To conclude, this is the first report to discuss the virtual screening of non-peptide inhibitors against SmCL1 of S. mansoni, with significant therapeutic potential. Results presented herein provide a valuable contribution to identify the significant leads and further derivatize them to suitable drug candidates for antischistosomal therapy.     

Photodynamic Effect of Ni Nanotubes on an HeLa Cell Line

Nickel nanomaterials are promising in the biomedical field, especially in cancer diagnostics and targeted therapy, due to their distinctive chemical and physical properties. In this experiment, the toxicity of nickel nanotubes (Ni NTs) were tested in an in vitro cervical cancer model (HeLa cell line) to optimize the parameters of photodynamic therapy (PDT) for their greatest effectiveness. Ni NTs were synthesized by electrodeposition. Morphological analysis and magnetic behavior were examined using a Scanning electron microscope (SEM), an energy dispersive X-ray analysis (EDAX) and a vibrating sample magnetometer (VSM) analysis. Phototoxic and cytotoxic effects of nanomaterials were studied using the Ni NTs alone as well as in conjugation with aminolevulinic acid (5-ALA); this was performed both in the dark and under laser exposure. Toxic effects on the HeLa cell model were evaluated by a neutral red assay (NRA) and by detection of intracellular reactive oxygen species (ROS) production. Furthermore, 10–200 nM of Ni NTs was prepared in solution form and applied to HeLa cells in 96-well plates. Maximum toxicity of Ni NTs complexed with 5-ALA was observed at 100 J/cm² and 200 nM. Up to 65–68% loss in cell viability was observed. Statistical analysis was performed on the experimental results to confirm the worth and clarity of results, with p-values = 0.003 and 0.000, respectively. Current results pave the way for a more rational strategy to overcome the problem of drug bioavailability in nanoparticulate targeted cancer therapy, which plays a dynamic role in clinical practice.     

Increased Susceptibility to Salmonella Infection in Signal Regulatory Protein α-Deficient Mice

Recent studies have shed light on the connection between elevated erythropoetin production/spleen erythropoiesis and increased susceptibility to Salmonella infection. In this article, we provide another mouse model, the SIRPα-deficient (Sirpα(-/-)) mouse, that manifests increased erythropoiesis as well as heightened susceptibility to Salmonella infection. Sirpα(-/-) mice succumbed to systemic infection with attenuated Salmonella, possessing significantly higher bacterial loads in both the spleen and the liver. Moreover, Salmonella-specific Ab production and Ag-specific CD4 T cells were reduced in Sirpα(-/-) mice compared with wild-type controls. To further characterize the potential mechanism underlying SIRPα-dependent Ag-specific CD4 T cell priming, we demonstrate that lack of SIRPα expression on dendritic cells results in less efficient Ag processing and presentation in vitro. Collectively, these findings demonstrate an indispensable role of SIRPα for protective immunity to Salmonella infection.