Trans-arachidonic acids generated during nitrative stress induce a thrombospondin-1-dependent microvascular degeneration

Nitrative stress has an important role in microvascular degeneration leading to ischemia in conditions such as diabetic retinopathy and retinopathy of prematurity. Thus far, mediators of nitrative stress have been poorly characterized. We recently described that trans-arachidonic acids are major products of NO(2)(*)-mediated isomerization of arachidonic acid within the cell membrane, but their biological relevance is unknown. Here we show that trans-arachidonic acids are generated in a model of retinal microangiopathy in vivo in a NO(*)-dependent manner. They induce a selective time- and concentration-dependent apoptosis of microvascular endothelial cells in vitro, and result in retinal microvascular degeneration ex vivo and in vivo. These effects are mediated by an upregulation of the antiangiogenic factor thrombospondin-1, independently of classical arachidonic acid metabolism. Our findings provide new insight into the molecular mechanisms of nitrative stress in microvascular injury and suggest new therapeutic avenues in the management of disorders involving nitrative stress, such as ischemic retinopathies and encephalopathies.     

Pesticides DEET,fipronil and maneb induce stress granule assembly and translation arrest in neuronal cells

Pesticides entering our body, either directly or indirectly, are known to increase the risk of developing neurodegenerative disorders. The pesticide-induced animal models of Parkinson's disease and Alzheimer's disease recapitulates many of the pathologies seen in human patients and have become popular models for studying disease biology. However, the specific effect of pesticides at the cellular and molecular levels is yet to be fully established. Here we investigated the cellular effect of three commonly used pesticides: DEET, fipronil and maneb. Specifically, we looked at the effect of these pesticides in the formation of stress granules and the concomitant translational arrest in a neuronal cell line. Stress granules represent an ensemble of non-translating mRNAs and appear in cells under physiological stress. Growing evidence indicates that chronic stress may covert the transient stress granules into amyloids and may thus induce neurodegeneration. We demonstrate here that all three pesticides tested induce stress granules and translation arrest through the inactivation of the eukaryotic initiation factor, eIF2α. We also show that oxidative stress could be one of the major intermediary factors in the pesticide-induced stress granule formation and that it is a reversible process. Our results suggest that prolonged pesticide exposure may result in long-lived stress granules, thus compromising the neuronal stress response pathway and leading to neurodegeneration.     

Protease activated receptor-2 (PAR2): possible target of phytochemicals

The use of phytochemicals either singly or in combination with other anticancer drugs comes with an advantage of less toxicity and minimal side effects. Signaling pathways play central role in cell cycle, cell growth, metabolism, etc. Thus, the identification of phytochemicals with promising antagonistic effect on the receptor/s playing key role in single transduction may have better therapeutic application. With this background, phytochemicals were screened against protease-activated receptor 2 (PAR2). PAR2 belongs to the superfamily of GPCRs and is an important target for breast cancer. Using in silico methods, this study was able to identify the phytochemicals with promising binding affinity suggesting their therapeutic potential in the treatment of breast cancer. The findings from this study acquires importance as the information on the possible agonists and antagonists of PAR2 is limited due its unique mechanism of activation.     

One-pot synthesis and anticancer studies of 2-arylamino-5-aryl-1,3,4-thiadiazoles

A series of 2-arylamino-5-aryl-1,3,4-thiadiazoles 1a-j were synthesized and screened for their anticancer activity against various human cancer cell lines. The novel one-pot synthesis of 1,3,4-thiadiazoles was achieved by refluxing aryl aldehydes, hydrazine hydrate, and aryl isothiocyanates in methanol followed by oxidative cyclization with ferric ammonium sulfate. The compounds 1g-j with trimethoxyphenyl at the C-5 position displayed extremely potent anticancer activity with at least twofold selectivity (IC₅₀: 4.3-9.2 μM). The nature of substituent on the C-2 arylamino ring may be critical in opting for the selectivity towards a particular cancer cell.     

A Study of NADP+- linked Isocitrate Dehydrogenase from Germinating Mung Bean (Vigna radiata)

NADP⁺- linked isocitrate dehydrogenase has been purified to apparent homogeneity from 36 h germinated mung beans by ammonium sulphate fractionation, heat treatment, acid treatment, and DEAE — Cellulose column chromatography. The enzyme was purified to 150 fold with 15% recovery. The preparation showed single protein band on native PAGE and was free from bound nucleotides and coloured pigments (A₂₈₀/A₂₆₀ = 1.4). The molecular weight was found to be 141,000 and was made of four identical subunits (mol wt 36,000). Thermal inactivation at 50, 53, and 55 °C revealed simple first order kinetics and t_1/2 was found to be 38, 10, and 3 min, respectively. The enzyme exhibited absolute specificity for NADP⁺ and substrate. The K_m for isocitrate and NADP⁺ was 28.57 µM and 70 µM, respectively. The enzyme appeared to be regulated by various metabolites of Krebs’ cycle intermediates.     

Using indirect methods to understand the impact of forced migration on long-term under-five mortality

Despite the large numbers of displaced persons and the often-lengthy periods of displacement, little is known about the impact of forced migration on long-term under-five mortality. This paper looks at the Brass Method (and adaptations of this method) and the Preceding Birth Technique in combination with a classification of women by their migration and reproductive histories, in order to study the impact of forced migration on under-five mortality. Data came from the Demography of Forced Migration Project, a study on mortality, fertility and violence in the refugee and host populations of Arua District, Uganda and Yei River District, Sudan. Results indicate that women who did not migrate in a situation of conflict and women who repatriated before the age of 15, had children with the highest under-five mortality rates compared with women who were currently refugees and women who repatriated after the age of 15.     

Structural alterations in cell organelles induced by photodynamic treatment with chlorin p6-histamine conjugate in human oral carcinoma cells probed by 3D fluorescence microscopy

We have explored the intracellular cell organelle's structural alterations after photodynamic treatment with chlorin p₆-histamine conjugate (Cp₆-his) in human oral cancer cells. Herein, the cells were treated with Cp₆-his (10 μm) and counterstained with organelle-specific fluorescence probes to find the site of intracellular localization using confocal microscopy. For photodynamic therapy (PDT), the cells were exposed to ~30 kJ/m² red light (660 ± 20 nm) to induce ~90% cytotoxicity. We used the three-dimensional (3D) image reconstruction approach to analyze the photodynamic damage to cell organelles. The result showed that Cp₆-his localized mainly in the endoplasmic reticulum (ER) and lysosomes but not in mitochondria and Golgi apparatus (GA). The 3D model revealed that in necrotic cells, PDT led to extensive fragmentation of ER and fragmentation and swelling of GA as well. Results suggest that the indirect damage to GA occurred due to loss of connection between ER and GA. Moreover, in damaged cells with no sign of necrosis, the perinuclear ER appeared condensed and surrounded by several small clumps at the peripheral region of the cell, and the GA was observed to form a single condensed structure. Since these structural changes were associated with apoptotic cell death, it is suggested that the necrotic and apoptotic death induced by PDT with Cp₆-his is determined by the severity of damage to ER and indirect damage to GA. The results suggest that the indirect damage to cell organelle apart from the sites of photosensitizer localization and the severity of damage at the organelle level contribute significantly to the mode of cell death in PDT.