A nanoformulation of siRNA and its role in cancer therapy: In vitro and in vivo evaluation

Overexpression of anti-apoptotic Bcl-2 is often observed in a wide variety of human cancers. It prevents the induction of apoptosis in neoplastic cells and contributes to resistance to chemotherapy. RNA interference has emerged as an efficient and selective technique for gene silencing. The potential to use small interfering RNA (siRNA) as a therapeutic agent for the treatment of cancer has elicited a great deal of interest. However, insufficient cellular uptake and poor stability have limited its therapeutic applications. The purpose of this study was to prepare chitosan nanoparticles via ionic gelation of chitosan by tripolyphosphate for effective delivery of siRNA to silence the anti-apoptotic Bcl-2 gene in neoplastic cells. Chitosan nanoparticles loaded with siRNA were in the size range 190 to 340 nm with a polydispersive index ranging from 0.04 to 0.2. They were able to completely bind with siRNA, provide protection against nuclease degradation, and enhance the transfection. Cell culture studies revealed that nanoparticles with entrapped siRNA could efficiently silence the antiapoptotic Bcl-2 gene. Studies on Swiss albino mice showed that siRNA could be effectively delivered through nanoparticles. There was significant decrease in the tumor volume. Blocking the expression of anti-apoptotic Bcl-2 can enhance the sensitivity of cancerous cells to anti-cancer drugs and the apoptosis rate. Therefore, nanoformulations with siRNA can be promoted as an adjuvant therapy in combination with anti-cancer drugs.     

S-Nitroso-N-acetylpenicillamine impregnated endotracheal tubes for prevention of ventilator-associated pneumonia

The chances of ventilator-associated pneumonia (VAP) increases 6–20 folds when an endotracheal tube (ETT) is placed in a patient. VAP is one of the most common hospital-acquired infections and comprises 86% of the nosocomial pneumonia cases. This study introduces the idea of nitric oxide-releasing ETTs (NORel-ETTs) fabricated by the incorporation of the nitric oxide (NO) donor S-nitroso-N-acetylpenicillamine (SNAP) into commercially available ETTs via solvent swelling. The impregnation of SNAP provides NO release over a 7-day period without altering the mechanical properties of the ETT. The NORel-ETTs successfully reduced the bacterial infection from a commonly found pathogen in VAP, Pseudomonas aeruginosa, by 92.72 ± 0.97% when compared with the control ETTs. Overall, this study presents the incorporation of the active release of a bactericidal agent in ETTs as an efficient strategy to prevent the risk of VAP.     

A 286 bp upstream regulatory region of a rice anther-specific gene, OSIPP3, confers pollen-specific expression in Arabidopsis

OSIPP3 gene (coding for pectin methylesterase inhibitor protein) was isolated from a pre-pollinated inflorescence-specific cDNA library by differential screening of stage-specific libraries from Oryza sativa. OSIPP3 is present in the genome of rice as a single copy gene. OSIPP3 gene was expressed exclusively in the pre-pollinated spikelets of rice. Upstream regulatory region (URR) of OSIPP3 was isolated and a series of 5′-deletions were cloned upstream of GUS reporter gene and were used to transform Arabidopsis. OSIPP3_del1 and del2 transgenic plants showed GUS expression in root, anther and silique, while OSIPP3_del3 showed GUS activity only in anthers and siliques. Pollen-specific expression was observed in case of plants harboring OSIPP3_del4 construct. It can, therefore, be concluded that the OSIPP3 URR between ?178 and +108 bp is necessary for conferring pollen-specific expression in Arabidopsis.     

Gold nanoparticle-based detection of genomic DNA targets on microarrays using a novel optical detection system

The development of a nanoparticle-based detection methodology for sensitive and specific DNA-based diagnostic applications is described. The technology utilizes gold nanoparticles derivatized with thiol modified oligonucleotides that are designed to bind complementary DNA targets. A glass surface with arrays of immobilized oligonucleotide capture sequences is used to capture DNA targets, which are then detected via hybridization to the gold nanoparticle probes. Amplification with silver allows for detection and quantitation by measuring evanescent wave induced light scatter with low-cost optical detection systems. Compared to Cy3-based fluorescence, silver amplified gold nanoparticle probes provide for a approximately 1000-fold increase in sensitivity. Furthermore, direct detection of non-amplified genomic DNA from infectious agents is afforded through increased specificity and even identification of single nucleotide polymorphisms (SNP) in human genomic DNA appears feasible.     

Substrate channelling in 2-oxo acid dehydrogenase multienzyme complexes

Heteronuclear NMR spectroscopy and other experiments indicate that the true substrate of the E1 component of 2-oxo acid dehydrogenase complexes is not lipoic acid but the lipoyl domain of the E2 component. E1 can recognize the lipoyl-lysine residue as such, but reductive acylation ensues only if the domain to which the lipoyl group is attached is additionally recognized by virtue of a mosaic of contacts distributed chiefly over the half of the domain that contains the lipoyl-lysine residue. The lipoyl-lysine residue may not be freely swinging, as supposed hitherto, but may adopt a preferred orientation pointing towards a nearby loop on the surface of the lipoyl domain. This in turn may facilitate the insertion of the lipoyl group into the active site of E1, where reductive acylation is to occur. The results throw new light on the concept of substrate channelling and active-site coupling in these giant multifunctional catalytic machines.     

DNA Ligase C1 Mediates the LigD-Independent Nonhomologous End-Joining Pathway of Mycobacterium smegmatis

Nonhomologous end joining (NHEJ) is a recently described bacterial DNA double-strand break (DSB) repair pathway that has been best characterized for mycobacteria. NHEJ can religate transformed linear plasmids, repair ionizing radiation (IR)-induced DSBs in nonreplicating cells, and seal I-SceI-induced chromosomal DSBs. The core components of the mycobacterial NHEJ machinery are the DNA end binding protein Ku and the polyfunctional DNA ligase LigD. LigD has three autonomous enzymatic modules: ATP-dependent DNA ligase (LIG), DNA/RNA polymerase (POL), and 3′ phosphoesterase (PE). Although genetic ablation of ku or ligD abolishes NHEJ and sensitizes nonreplicating cells to ionizing radiation, selective ablation of the ligase activity of LigD in vivo only mildly impairs NHEJ of linearized plasmids, indicating that an additional DNA ligase can support NHEJ. Additionally, the in vivo role of the POL and PE domains in NHEJ is unclear. Here we define a LigD ligase-independent NHEJ pathway in Mycobacterium smegmatis that requires the ATP-dependent DNA ligase LigC1 and the POL domain of LigD. Mycobacterium tuberculosis LigC can also support this backup NHEJ pathway. We also demonstrate that, although dispensable for efficient plasmid NHEJ, the activities of the POL and PE domains are required for repair of IR-induced DSBs in nonreplicating cells. These findings define the genetic requirements for a LigD-independent NHEJ pathway in mycobacteria and demonstrate that all enzymatic functions of the LigD protein participate in NHEJ in vivo.     

Ecotourism and ecological restoration

The fast pace of tourism development around the world is causing untold damage to some of the most endangered ecological systems. From Dubai to Honolulu and from Cancun to Beijing, the environmental impacts of tourism are alarming. Ecological restoration (ER) of disturbed lands should be an important approach to sensitive tourism planning. This paper addresses the need for restoring biodiversity and how ecotourism has shown to be a strong force in the field of ER. Two examples (one each of private and community based ecotourism) incorporating ER will be highlighted in this paper: Phinda Game Reserve, South Africa and the Baboon Sanctuary in Belize. We call for greater dialogue across disciplines, notably ER, conservation science and ecotourism.     

An improved microwave assisted one-pot synthesis, and biological investigations of some novel aryldiazenyl chromeno fused pyrrolidines

An improved microwave assisted one-pot method for the synthesis of twelve new aryldiazenylchromeno [4,3-b] pyrrolidines via intramolecular azomethine ylide cycloaddition route is described. The method is efficient and advantageous over conventional and solvent-free thermal methods. The stereochemistry of the compounds was confirmed on the basis of various NMR experiments, and finally by single crystal X-ray diffraction data. N-Methyl or ethyl pyrrolidine based heterocycles gave good biological activities.