MiR-193b deregulation is associated with Parkinson's disease

PGC-1α/FNDC5/BDNF has found to be a critical pathway in neurodegeneration. MicroRNAs (miR(NA)s) are non-coding regulatory RNAs whose dysregulation has been observed in multiple neurological disorders, and miRNA-mediated gene deregulation plays a decisive role in PD. Here, candidate miRNA was chosen based on the literature survey and in silico studies. Chronic and acute models of PD were created using MPP+-treated SH-SY5Y cells. Twenty PD patients and 20 healthy volunteers were recruited. RT-qPCR was performed to assess the expression of miRNA and genes. Severe mitochondrial dysfunction induced by acute MPP+ treatment instigated compensatory mechanisms through enhancing expression of PGC-1α/FNDC5/BDNF pathway genes, while chronic MPP+ toxicity led to down-regulated levels of the genes in SH-SY5Y cells. PD peripheral blood mononuclear cells (PBMCs) also showed decreased expression of target genes. There were significant changes in the level of miR-193b in both models, as well as PD PBMCs. Moreover, miR-193b overexpression significantly affected PGC-1α, FNDC5 and TFAM levels. Interestingly, down-regulations of PGC-1α, FNDC5, BDNF and TFAM were inversely correlated with miR-193b up-regulation in PD PBMCs. This study showed the deregulation of PGC-1α/FNDC5/BDNF pathway in PD models and PBMCs, verifying its importance in neurodegeneration. Our findings also revealed that miR-193b functions in PD development, possibly through regulating PGC-1α/FNDC5/BDNF pathway, suggesting miR-193b as a potential biomarker for PD diagnosis.     

Mechanistic and structural insights into the in vitro inhibitory action of hypericin on glutathione reductase purified from baker's yeast

This work aims at studying the interaction between glutathione reductase (GR) and hypericin. The type of inhibition was determined by measuring changes in GR activity at increasing concentrations of hypericin as well as at varying concentrations of glutathione disulfide (GSSG) and nicotinamide adenine dinucleotide phosphate (NADPH), and the binding pose of hypericin was predicted by molecular docking. Accordingly, hypericin emerges as an effective inhibitor of GR. When the variable substrate is GSSG, the type of inhibition is competitive. When the variable substrate is NADPH, however, the type of inhibition appears to be linear mixed‐type competitive. Our computational analyses suggest that hypericin binds in the large intermonomer cavity of GR, and that it may interfere with the normal positioning/functioning of the redox‐active disulfide center at the enzyme's active site. Overall, besides its contributory role in promoting oxidative stress via the formation of reactive oxygen species in photodynamic therapy, hypericin can also weaken cancer cells through inhibiting GR.     

Gastric xanthoma: a diagnostic problem on brushing cytology smears

OBJECTIVE: To describe the cytologic findings of gastric xanthomas and to compare them with the findings of signet-ring adenocarcinoma because atypical xanthoma cells can be easily confused with signet-ring adenocarcinoma cells. STUDY DESIGN: Five cases of gastric xanthoma that were confirmed by biopsy reports were selected for study. The patients' ages ranged between 50 and 58 years; 4 were men and 1 was a woman. Twenty-one cases of signet-ring adenocarcinoma confirmed by biopsy reports were selected for comparison. Special staining was performed. RESULTS: The brushing cytology smears of the 5 cases of xanthoma revealed atypical cells, so initially they were reported as suspicious for signet-ring adenocarcinoma and biopsy examination advised. After learning of the histologic diagnosis of xanthoma, we performed special staining. The xanthoma cells were negative with periodic acid-Schiff (PAS) stain but showed a positive reaction with Oil red 0 and weakly positive reaction with Masson trichrome. Signet-ring adenocarcinoma cells showed a strongly positive reaction with PAS stain. CONCLUSION: Gastric brushing cytology findings of xanthomas have not been described before. At times the differentiation of atypical xanthoma cells from signet-ring adenocarcinoma cells is very difficult on brushing cytology smears. In this study the nuclear changes and special stains helped differentiate the 2 lesions.     

Ca-binding to Bacillus licheniformis alpha-amylase (BLA)

Ca-induced renaturation of Bacillus licheniformis alpha-amylase in the presence of urea has been employed to determine the binding constants of the ion. The native enzyme is folded at 3M urea while the Ca-depleted protein is largely unfolded at this denaturant concentration. Refolding of the protein has been monitored by circular dichroism and the titration curves have been analyzed assuming a model of three independent binding sites. The stoichiometry has been taken from X-ray studies. The refolded protein exhibits a secondary structure that is similar but not identical to that of the native protein. The binding constants have been used to construct a phase diagram that illustrates the contribution of Ca-binding to the resistance against urea unfolding.     

Lessons from peroxisome-deficient Chinese hamster ovary (CHO) cell mutants

Cells with a genetic defect affecting a biological activity and/or a cell phenotype are generally called "cell mutants" and are a highly useful tool in genetic, biochemical, as well as cell biological research. To investigate peroxisome biogenesis and human peroxisome biogenesis disorders, more than a dozen complementation groups of Chinese hamster ovary (CHO) cell mutants defective in peroxisome assembly have been successfully isolated and established as a model system. Moreover, successful PEX gene cloning studies by taking advantage of rapid functional complementation assay of CHO cell mutants invaluably contributed to the accomplishment of isolation of pathogenic genes responsible for peroxisome biogenesis diseases. Molecular mechanisms of peroxisome assembly are currently investigated by making use of such mammalian cell mutants.