Elevated [Ca2+]i levels occur with decreased calpain activity in aged fibroblasts and their reversal by energy-rich compounds: new paradigm for Alzheimer's disease prevention.

Elevated intracellular Ca2+ levels in the aging brain are widely thought to hyperactivate Ca2+ signaling and Ca2+-dependent enzymes, leading to neuronal death through an excitatory mechanism in Alzheimer's disease (AD). This "Ca2+ overload" hypothesis has been questioned by our theoretical analyses. To better understand the relationship between the "level" and functionality of Ca2+ in aging, in this study we simultaneously measured intracellular Ca2+ transients and calpain activity in cultured human fibroblasts. We found that Ca2+ transitions elicited by bradykinin were indeed overstayed or elevated in levels in old cells but, remarkably, calpain activity was decreased compared to young cells. Also, treating young cells with the energy inhibitor rotenone or with H2O2 recapitulated the Ca2+ overstay and calpain inactivation found in old cells. More importantly, treating old cells with high-energy compounds such as phosphoenol pyruvate or phosphocreatine, which boosted cellular ATP content, reduced the Ca2+ overstay and re-activated calpain. Moreover, Ca2+ levels and calpain activity were dramatically raised in the dying cells killed by detergent. Finally, Ca2+ oscillations induced by low dose of bradykinin in old cells exhibited lower spike frequency, but higher overall levels. Collectively, these results suggest that (a) Ca2+ overload in old cells arises from an inefficient Ca2+ handling system compromised by age-related energy depletion and oxidative stress; and (b) despite elevated levels, the functionality of Ca2+ signaling has diminished in old cells. Thus, the study reinforces the concept that tonic promotion of bioenergetics and Ca2+ signaling function is a reasonable and new paradigm to protect the aging brain cells to prevent AD.

A new method for lung cancer prognosis via centrosome image feature analysis.

OBJECTIVE: To predict survival of resected stage I non-small cell lung cancer (NSCLC) patients through quantitative analysis and classification of centrosome features. STUDY DESIGN: Disordered centrosome amplification leads to the loss of regulated chromosome segregation, aneuploidy and chromosome instability and may be a biomarker of cancer prognosis. Resected, stage I NSCLC tissues from survivor and fatal cases were immunostained with gamma-tubulin and scanned by confocal microscopy. Regions of interest were selected to include 1 cell and at least 1 centrosome. Four hundred forty-six regions were imaged, including 903 centrosomes whose features were extracted and measured. After segmentation, 12 centrosome features were measured. After optimization, 6 non-redundant features were selected for statistical analysis and classification. RESULTS: Two statistical methods showed that for each feature, centrosomes from survivors differed significantly from centrosomes of fatalities. Centrosomes were classified into survival or fatal outcomes by centrosome features using linear discriminant analysis, support vector machines (SVMs) and further optimized using SVMs with bagging. Ten-fold cross-validation was applied. Classification accuracies were 74%, 79% and 85%, respectively. CONCLUSION: Centrosome features can be a prognostic biomarker for resected stage I NSCLC and may indicate patients who would benefit from additional adjuvant therapy.

High-energy compounds promote physiological processing of Alzheimer's amyloid-ß precursor protein and boost cell survival in culture.

Physiological or α-processing of amyloid-ß precursor protein (APP) prevents the formation of Aß, which is deposited in the aging brain and may contribute to Alzheimer's disease. As such, drugs promoting this pathway could be useful for prevention of the disease. Along this line, we searched through a number of substances and unexpectedly found that a group of high-energy compounds (HECs), namely ATP, phosphocreatine, and acetyl coenzyme A, potently increased APP α-processing in cultured SH-SY5Y cells, whereas their cognate counterparts, i.e., ADP, creatine, or coenzyme A did not show the same effects. Other HECs such as GTP, CTP, phosphoenol pyruvate, and S-adenosylmethionine also promoted APP α-processing with varying potencies and the effects were abolished by energy inhibitors rotenone or NaN(3). The overall efficacy of the HECs in the process ranged from three- to four-fold, which was significantly greater than that exhibited by other physiological stimulators such as glutamate and nicotine. This suggested that the HECs were perhaps the most efficient physiological stimulators for APP α-processing. Moreover, the HECs largely offset the inefficient APP α-processing in aged human fibroblasts or in cells impaired by rotenone or H(2) O(2). Most importantly, some HECs markedly boosted the survival rate of SH-SY5Y cells in the death process induced by energy suppression or oxidative stress. These findings suggest a new, energy-dependent regulatory mechanism for the putative α-secretase and thus will help substantially in its identification. At the same time, the study raises the possibility that the HECs may be useful to energize and strengthen the aging brain cells to slow down the progression of Alzheimer's disease.