Oxidative stress caused by inactivation of glutathione peroxidase and adaptive responses

Reactive oxygen species (ROS) are generated as by-products of cellular metabolism, primarily in the mitochondria. When the cellular production of ROS exceeds the cell's antioxidant capacity, cellular macromolecules such as lipids, proteins and DNA can be damaged. Because of this, 'oxidative stress' is thought to contribute to aging and pathogenesis of a variety of human diseases. However, in the last 10-15 years, a considerable body of evidence has accumulated that ROS serve as subcellular messengers, and play a role in gene regulation and signal transduction pathways, which may be involved in defensive mechanisms against oxidative stress. This review focuses on oxidative stress caused by the inactivation of glutathione peroxidase (GPx), a major peroxide scavenging enzyme. GPx is inactivated by a variety of physiological substances, including nitric oxide and carbonyl compounds in vitro and in cell culture. Decreased GPx activity has also been reported in tissues where oxidative stress occurs in several pathological animal models. The accumulation of increased levels of peroxide resulting from inactivation of GPx may act as a second messenger and regulate expression of anti-apoptotic genes and the GPx itself to protect against cell damage. These findings suggest that GPx undergoes inactivation under various conditions such as nitroxidative stress and glycoxidative stress, and that these changes are a common feature of various types of oxidative stress which may be associated with the modification of redox regulation and cellular function.     

Speeding up direct <Superscript>15</Superscript>N detection: hCaN 2D NMR experiment

Experiments detecting low gyromagnetic nuclei have recently been proposed to utilize the relatively slow relaxation properties of these nuclei in comparison to ¹H. Here we present a new type of ¹⁵N direct-detection experiment. Like the previously proposed CaN experiment (Takeuchi et al. in J Biomol NMR 47:271–282, 2010), the hCaN experiment described here sequentially connects amide ¹⁵N resonances, but utilizes the initial high polarization and the faster recovery of the ¹H nucleus to shorten the recycling delay. This allows recording 2D ¹⁵N-detected NMR experiments on proteins within a few hours, while still obtaining superior resolution for ¹³C and ¹⁵N, establishing sequential assignments through prolines, and at conditions where amide protons exchange rapidly. The experiments are demonstrated on various biomolecules, including the small globular protein GB1, the 22 kDa HEAT2 domain of eIF4G, and an unstructured polypeptide fragment of NFAT1, which contains many SerPro sequence repeats.     

Circulating Exosomal microRNAs as Biomarkers of Colon Cancer

Purpose

Exosomal microRNAs (miRNAs) have been attracting major interest as potential diagnostic biomarkers of cancer. The aim of this study was to characterize the miRNA profiles of serum exosomes and to identify those that are altered in colorectal cancer (CRC). To evaluate their use as diagnostic biomarkers, the relationship between specific exosomal miRNA levels and pathological changes of patients, including disease stage and tumor resection, was examined.

Experimental Design

Microarray analyses of miRNAs in exosome-enriched fractions of serum samples from 88 primary CRC patients and 11 healthy controls were performed. The expression levels of miRNAs in the culture medium of five colon cancer cell lines were also compared with those in the culture medium of a normal colon-derived cell line. The expression profiles of miRNAs that were differentially expressed between CRC and control sample sets were verified using 29 paired samples from post-tumor resection patients. The sensitivities of selected miRNAs as biomarkers of CRC were evaluated and compared with those of known tumor markers (CA19-9 and CEA) using a receiver operating characteristic analysis. The expression levels of selected miRNAs were also validated by quantitative real-time RT-PCR analyses of an independent set of 13 CRC patients.

Results

The serum exosomal levels of seven miRNAs (let-7a, miR-1229, miR-1246, miR-150, miR-21, miR-223, and miR-23a) were significantly higher in primary CRC patients, even those with early stage disease, than in healthy controls, and were significantly down-regulated after surgical resection of tumors. These miRNAs were also secreted at significantly higher levels by colon cancer cell lines than by a normal colon-derived cell line. The high sensitivities of the seven selected exosomal miRNAs were confirmed by a receiver operating characteristic analysis.

Conclusion

Exosomal miRNA signatures appear to mirror pathological changes of CRC patients and several miRNAs are promising biomarkers for non-invasive diagnosis of the disease.     

Isolation of Nipah virus from Malaysian Island flying-foxes

In late 1998, Nipah virus emerged in peninsular Malaysia and caused fatal disease in domestic pigs and humans and substantial economic loss to the local pig industry. Surveillance of wildlife species during the outbreak showed neutralizing antibodies to Nipah virus mainly in Island flying-foxes (Pteropus hypomelanus) and Malayan flying-foxes (Pteropus vampyrus) but no virus reactive with anti-Nipah virus antibodies was isolated. We adopted a novel approach of collecting urine from these Island flying-foxes and swabs of their partially eaten fruits. Three viral isolates (two from urine and one from a partially eaten fruit swab) that caused Nipah virus-like syncytial cytopathic effect in Vero cells and stained strongly with Nipah- and Hendra-specific antibodies were isolated. Molecular sequencing and analysis of the 11,200-nucleotide fragment representing the beginning of the nucleocapsid gene to the end of the glycoprotein gene of one isolate confirmed the isolate to be Nipah virus with a sequence deviation of five to six nucleotides from Nipah virus isolated from humans. The isolation of Nipah virus from the Island flying-fox corroborates the serological evidence that it is one of the natural hosts of the virus.     

Reciprocal adaptive response of human peripheral lymphocytes induced by bleomycine or gamma rays.

The adaptive response and reciprocal adaptive response induced in vitro by exposure to low doses of gamma rays (0.05 Gy) or bleomycin (0.05 microg/ml) in human peripheral blood lymphocytes were assessed by the frequency of chromosome aberrations. Gamma rays (1.5 Gy) or bleomycin (1.5 microg/ml) were used as the challenge doses. In the experiments, blood samples from 5 healthy donors were investigated. It has been found that low doses of bleomycin and gamma rays induced a reciprocal adaptive response to high doses of gamma rays or bleomycin. Moreover, the results confirmed that the adaptive response did not correlate with the radiosensitivity of the peripheral blood lymphocytes.     

Fine needle aspiration cytology of late-stage callus in stress fracture. A case report

BACKGROUND: Fine needle aspiration cytology (FNAC) is effective in the diagnosis of bone lesions when combined with careful radiologic and clinical evaluation. The cytologic features of callus have not been described before in the English-language literature. CASE: An 18-year-old female presented with a pain in the right lower leg that had been present for two months. Clinical and radiologic findings suggested either stress fracture or periosteal osteosarcoma. The aspiration specimen showed individually scattered, oval cells with moderate amounts of pale pink cytoplasm. The cells contained a single eccentrically located nucleus with evenly distributed, fine chromatin. Osteoclastic giant cells were scattered in the smears. A cytologic diagnosis of benign bone-forming lesion, compatible with callus in fracture, was made. The diagnosis of late-stage callus was confirmed by subsequent histologic examination. CONCLUSION: Typical cases of stress fracture do not need histologic examination, but some cases may be confused with benign and malignant bone tumors. The typical and unique cytologic features of late-stage callus combined with clinical and radiologic findings may prevent the use of more invasive diagnostic procedures and can be a choice for management.     

Prediction of phosphorylation sites using SVMs

MOTIVATION: Phosphorylation is involved in diverse signal transduction pathways. By predicting phosphorylation sites and their kinases from primary protein sequences, we can obtain much valuable information that can form the basis for further research. Using support vector machines, we attempted to predict phosphorylation sites and the type of kinase that acts at each site. RESULTS: Our prediction system was limited to phosphorylation sites catalyzed by four protein kinase families and four protein kinase groups. The accuracy of the predictions ranged from 83 to 95% at the kinase family level, and 76-91% at the kinase group level. The prediction system used-PredPhospho-can be applied to the functional study of proteins, and can help predict the changes in phosphorylation sites caused by amino acid variations at intra- and interspecies levels.     

Ischemia-responsive protein (irp94) is up-regulated by endoplasmic reticulum stress

The expression of the ischemia-responsive protein (irp94) was enhanced by endoplasmic reticulum (ER) stress inducing drugs such as brefeldin A (BFA), calcium ionophor A23187, dithiothreitol (DTT) and tunicamycin in fisher rat thyroid epithelial cell line (FRTL-5 cells). In particular, irp94 mRNA expression was increased dose dependently by tunicamycin, and there was increased irp94 expression when the cells were incubated with the thyroid-stimulating hormone (TSH) together.