Alteration of Golgi structure in senescent cells and its regulation by a G protein γ subunit

Cellular senescence is a process wherein proliferating cells undergo permanent cell cycle arrest while remaining viable. Senescence results in enhanced secretion of proteins that promote cancer and inflammation. We report here that the structure of the Golgi complex which regulates secretion is altered in senescent cells. In cells where senescence is achieved by replicative exhaustion or in cells wherein senescence has been induced with BrdU treatment dependent stress, the Golgi complex is dispersed. The expression of a G protein γ subunit, γ11, capable of translocation from the plasma membrane to the Golgi complex on receptor activation increases with senescence. Knockdown of γ11 or overexpression of a dominant negative γ3 subunit inhibits Golgi dispersal induced by senescence. Overall these results suggest that in cellular senescence an upregulated G protein gamma subunit mediates alterations in the structure of the Golgi.     

土壤中棉花黄萎病菌SYBR Green Ⅰ荧光RT-PCR定量检测技术研究

为实现田间土壤棉花黄萎病菌的早期检测,建立了土壤中棉花黄萎病菌的SYBR Green I荧光定量PCR检测方法。以含342bp PCR扩增产物的阳性质粒为参考,构建了标准曲线,并对该曲线的特异性、敏感性、可重复性进行了评价。结果表明,该方法具有快速、特异性强、敏感度高等特点。检测范围在3.8×103-3.8×108copies/μL之间有良好的线性关系,相关系数R2为0.996,扩增效率为101.5%,灵敏度比常规PCR方法高102倍。     

Effect of bacoside A on membrane-bound ATPases in the brain of rats exposed to cigarette smoke

Membrane-bound enzymes play a vital role in neuronal function through maintenance of membrane potential and impulse propagation. We have evaluated the harmful effects of chronic cigarette smoking on membrane-bound ATPases and the protective effect of Bacoside A in rat brain. Adult male albino rats were exposed to cigarette smoke for a period of 12 weeks and simultaneously administered with Bacoside A (the active principle isolated from Bacopa monniera) at a dosage of 10 mg/kg b.w/day, p.o. The levels of lipid peroxides as marker for evaluating the extent of membrane damage, the activities of Na+/K+-ATPase, Ca2+-ATPase and Mg2+-ATPase, and associated cations sodium (Na+), potassium (K+), calcium (Ca2+), and magnesium (Mg2+) were investigated in the brain. Neuronal membrane damage was evident from the elevated levels of lipid peroxides and decreased activities of membrane-bound enzymes. Disturbances in the electrolyte balance with accumulation of Na+ and Ca2+ and depletion of K+ and Mg2+ were also observed. Administration of Bacoside A inhibited lipid peroxidation, improved the activities of ATPases, and maintained the ionic equilibrium. The results of our study indicate that Bacoside A protects the brain from cigarette smoking induced membrane damage.     

Effect of Solanum trilobatum on the antioxidant status during diethyl nitrosamine induced and phenobarbital promoted hepatocarcinogenesis in rat

AIM: The methanolic extract of Solanum trilobatum (ST) is cytotoxic and exerts an inhibitory effect on tumor growth and in the present study, its role on the antioxidant status of N-diethylnitrosamine (DEN) induced and phenobarbital (PB) promoted hepatocarcinogenesis was assessed. METHODS: The protective role of ST on DEN induced and PB promoted hepatocarcinogenesis in Wistar rats was assessed from total nodular incidence, nodule multiplicity and volume of persistent nodules after an experimental period of 3 and 6 months following co-administration. The levels of thiobarbituric reactive substances (TBARS), glutathione (GSH) and activities of antioxidant enzymes were assessed in the haemolysate and liver of experimental animals to evaluate the antioxidant status. RESULTS: In DEN+PB+ST animals, the nodular incidence, multiplicity and volume reduced significantly compared to DEN+PB treated animals. In DEN+PB animals, the levels of TBARS increased significantly, whereas the levels of GSH and the activities of antioxidant enzymes-superoxide dismutase, catalase, glutathione reductase, glutathione peroxidase and glucose 6 phosphate dehydrogenase showed significant alterations compared to control both in the haemolysate and liver. However, in DEN+PB+ST animals, the levels of TBARS decreased significantly and the levels of GSH increased with favorable alterations in the activities of antioxidant enzymes in both the haemolysate and liver. CONCLUSION: The present results suggest that ST exerts its chemopreventive effects by modulating the antioxidant status during DEN induced hepatocarcinogenesis.     

Designing human m1 muscarinic receptor-targeted hydrophobic eigenmode matched peptides as functional modulators

A new proprietary de novo peptide design technique generated ten 15-residue peptides targeting and containing the leading nontransmembrane hydrophobic autocorrelation wavelengths, “modes”, of the human m₁ muscarinic cholinergic receptor, m₁AChR. These modes were also shared by the m₄AChR subtype (but not the m₂, m₃, or m₅ subtypes) and the three-finger snake toxins that pseudoirreversibly bind m₁AChR. The linear decomposition of the hydrophobically transformed m₁AChR amino acid sequence yielded ordered eigenvectors of orthogonal hydrophobic variational patterns. The weighted sum of two eigenvectors formed the peptide design template. Amino acids were iteratively assigned to template positions randomly, within hydrophobic groups. One peptide demonstrated significant functional indirect agonist activity, and five produced significant positive allosteric modulation of atropine-reversible, direct-agonist-induced cellular activation in stably m₁AChR-transfected Chinese hamster ovary cells, reflected in integrated extracellular acidification responses. The peptide positive allosteric ligands produced left-shifts and peptide concentration-response augmentation in integrated extracellular acidification response asymptotic sigmoidal functions and concentration-response behavior in Hill number indices of positive cooperativity. Peptide mode specificity was suggested by negative crossover experiments with human m₂ACh and D₂ dopamine receptors. Morlet wavelet transformation of the leading eigenvector-derived, m₁AChR eigenfunctions locates seven hydrophobic transmembrane segments and suggests possible extracellular loop locations for the peptide-receptor mode-matched, modulatory hydrophobic aggregation sites.     

Immunocytochemistry on scrape cytology in breast cancer: will it unearth the weaker positives?

OBJECTIVE: To standardize the technique of immunocytochemical (ICC) assessment of estrogen (ER) and progesterone receptor (PR) status in breast cancer by scrape cytology and to compare the results with immunohistochemistry on paraffin blocks. STUDY DESIGN: ICC assessment for ER and PR was done on scrape smears from tissue samples in 200 cases of primary breast cancer. The results were compared to those obtained from immunohistochemical (IHC) evaluation of formalin-fixed paraffin same tissue samples. RESULTS: ER/PR positivity rates as well as staining scores were compared between the scrape smears and tissue sections. The concordance between cytology and histology was 84% for ER and 90% for PR. Both the positivity rates and the staining intensity scores were higher for cytochemistry than for histochemistry. CONCLUSION: The ICC method on scrape smears is a simple test with rapid turnaround time. The sample required is small, and antigen loss due to fixation and processing is minimal. This new method gives a higher yield of hormone receptor positivity and, when used in conjunction with the IHC method, may improve the pickup rate of ER-positive cases, thereby playing an important role in risk stratification and therapeutic decision making in patients with breast cancer.