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Summary: Aging-associated muscle insulin resistance has been hypothesized to be due to decreased mitochondrial function, secondary to cumulative free radical damage, leading to increased intramyocellular lipid content. To directly test this hypothesis, we examined both in vivo and in vitro mitochondrial function, intramyocellular lipid content, and insulin action in lean healthy mice with targeted overexpression of the human catalase gene to mitochondria (MCAT mice). Here, we show that MCAT mice are protected from age-induced decrease in muscle mitochondrial function (∼30%), energy metabolism (∼7%), and lipid-induced muscle insulin resistance. This protection from age-induced reduction in mitochondrial function was associated with reduced mitochondrial oxidative damage, preserved mitochondrial respiration and muscle ATP synthesis, and AMP-activated protein kinase-induced mitochondrial biogenesis. Taken together, these data suggest that the preserved mitochondrial function maintained by reducing mitochondrial oxidative damage may prevent age-associated whole-body energy imbalance and muscle insulin resistance. [ABSTRACT FROM AUTHOR]

Age is a major risk factor for cardiovascular diseases, not only because it prolongs exposure to several other cardiovascular risks, but also owing to intrinsic cardiac aging, which reduces cardiac functional reserve, predisposes the heart to stress, and contributes to increased cardiovascular mortality in the elderly. Intrinsic cardiac aging in the murine model closely recapitulates age-related cardiac changes in humans, including left ventricular hypertrophy, fibrosis, and diastolic dysfunction. Cardiac aging in mice is accompanied by accumulation of mitochondrial protein oxidation, increased mitochondrial DNA mutations, increased mitochondrial biogenesis, as well as decreased cardiac SERCA2 protein. All of these age-related changes are significantly attenuated in mice overexpressing catalase targeted to mitochondria. These findings demonstrate the critical role of mitochondrial reactive oxygen species in cardiac aging and support the potential application of mitochondrial antioxidants to cardiac aging and age-related cardiovascular diseases. [Copyright &y& Elsevier]

Background & Aims: Telomere shortening is implicated in cancer and aging and might link these 2 biologic events. We explored this hypothesis in ulcerative colitis (UC), a chronic inflammatory disease that predisposes to colorectal cancer and in which shorter telomeres have been associated with chromosomal instability and tumor progression. Methods: Telomere length was measured by quantitative polymerase chain reaction in colonocytes and leukocytes of 2 different sets of UC patients and compared with normal controls across a wide range of ages. For a subset of patients, telomere length was measured in epithelium and stroma of right and left colon biopsy specimens. A third set of biopsy specimens was analyzed for phosphorylation of histone H2AX (γH2AX), a DNA damage signal, by immunofluorescence and for telomere length by quantitative fluorescence in situ hybridization. Relationships between telomere length, γH2AX intensity, age, disease duration, and age of disease onset were explored. Results: Colonocyte telomeres shorten with age almost twice as rapidly in UC patients as in normal controls. This extensive shortening occurs within approximately 8 years of disease duration. Leukocyte telomeres are slightly shorter in UC patients than in controls, but telomeres of colon stromal cells are unaffected. γH2AX intensity is higher in colonocytes of UC patients than in controls and is not dependent on age or telomere length. Conclusions: Colonocytes of UC patients show premature shortening of telomeres, which might explain the increased and earlier risk of cancer in this disease. Shorter leukocyte telomeres and increased γH2AX in colonocytes might reflect oxidative damage secondary to inflammation. [Copyright &y& Elsevier]

Abstract: Although cytostasis and cytotoxicity induced by cancer chemotherapy drugs targeting topoisomerase II (topoII) arise in specific cell cycle phases, it is unknown whether the drug-initiated DNA damage triggering these responses, or the repair (reversal) of this damage, differs between cell cycle phases or between drug classes. Accordingly, we used a flow cytometric alkaline unwinding assay to measure DNA damage (strand breakage (SB)) and SB repair in each cell cycle compartment of human cancer cell lines treated with clinically relevant concentrations of doxorubicin, daunomycin, etoposide, and mitoxantrone. We found that treated HeLa and A549 cells exhibited the greatest SB in G2/M phase, the least in G1 phase, and generally an intermediate amount in S phase. The cell cycle phase specificity of the DNA damage appeared to be predictive of the cell cycle phase of growth arrest. Furthermore, it appeared to be dependent on topoIIα expression as the extent of SB did not differ between cell cycle compartments in topoIIα-diminished A549(VP)28 cells. HeLa cells were apparently unable to repair doxorubicin-initiated SB. The rate of repair of etoposide-initiated SB in HeLa cells and of mitoxantrone-initiated SB in HeLa and A549 cells was similar in each cell cycle compartment. In A549 cells, the rate of repair of doxorubicin and etoposide-initiated SB differed between cell cycle phases. Overall, these results indicate that the cell cycle phase specificity of cytostasis and cytotoxicity induced in tumor cells by topoII-targeting drugs may be directly related to the cell cycle phase specificity of the drug-initiated DNA damage. Analysis by cell cycle compartment appears to clarify some of the intercellular heterogeneity in the extent of drug-initiated DNA damage and cytotoxicity previously observed in cancer cells analyzed as a single population; this approach might be useful in resolving inconsistent results reported in investigations of tumor cell topoII content versus response to topoII-targeting drugs. [Copyright &y& Elsevier]

There is controversy over how to best manage patients with inflammatory bowel disease and flat low-grade dysplasia (fLGD) in the colon. We performed a retrospective analysis of formalin-fixed paraffin-embedded colon tissues with fLGD from 37 patients undergoing surveillance colonoscopy for inflammatory bowel disease from 1990 to 2015 at the University of California at San Francisco Medical Center, to determine whether detection of aneuploidy is associated with later development of high-grade dysplasia (HGD) or colorectal cancer. Medical data were collected from the patients for a mean follow-up time of 37 months. Using flow cytometry analysis of paraffin-embedded colon tissue, we detected aneuploidy in 15 of 37 samples with fLGD (40.5%). By comparison, aneuploidy was detected in 14 of 15 samples with flat HGD (93.3%) and 2 of 45 samples that were negative for dysplasia (4.4%). The univariate hazard ratio for subsequent detection of HGD or colorectal cancer in patients with fLGD and aneuploidy was 5.3 (95% CI, 1.542−24.121) within a mean follow-up time of 37 months. The presence of aneuploidy therefore identifies patients with fLGD in colon tissue who have an increased risk for HGD or colorectal cancer and may provide supportive evidence to a morphologic impression or suspicion of flat HGD. [ABSTRACT FROM AUTHOR]

Sarcopenia and exercise intolerance are major contributors to reduced quality of life in the elderly for which there are few effective treatments. We tested whether enhancing mitochondrial function and reducing mitochondrial oxidant production with SS-31 (elamipretide) could restore redox balance and improve skeletal muscle function in aged mice. Young (5 mo) and aged (26 mo) female C57BL/6Nia mice were treated for 8-weeks with 3 mg/kg/day SS-31. Mitochondrial function was assessed in vivo using 31P and optical spectroscopy. SS-31 reversed age-related decline in maximum mitochondrial ATP production (ATPmax) and coupling of oxidative phosphorylation (P/O). Despite the increased in vivo mitochondrial capacity, mitochondrial protein expression was either unchanged or reduced in the treated aged mice and respiration in permeabilized gastrocnemius (GAS) fibers was not different between the aged and aged+SS-31 mice. Treatment with SS-31 also restored redox homeostasis in the aged skeletal muscle. The glutathione redox status was more reduced and thiol redox proteomics indicated a robust reversal of cysteine S-glutathionylation post-translational modifications across the skeletal muscle proteome. The gastrocnemius in the age+SS-31 mice was more fatigue resistant with significantly greater mass compared to aged controls. This contributed to a significant increase in treadmill endurance compared to both pretreatment and untreated control values. These results demonstrate that the shift of redox homeostasis due to mitochondrial oxidant production in aged muscle is a key factor in energetic defects and exercise intolerance. Treatment with SS-31 restores redox homeostasis, improves mitochondrial quality, and increases exercise tolerance without an increase in mitochondrial content. Since elamipretide is currently in clinical trials these results indicate it may have direct translational value for improving exercise tolerance and quality of life in the elderly. fx1 [ABSTRACT FROM AUTHOR]

Cardiovascular diseases are the leading cause of death in most developed nations. While it has received the least public attention, aging is the dominant risk factor for developing cardiovascular diseases, as the prevalence of cardiovascular diseases increases dramatically with increasing age. Cardiac aging is an intrinsic process that results in impaired cardiac function, along with cellular and molecular changes. Mitochondria play a great role in these processes, as cardiac function is an energetically demanding process. In this review, we examine mitochondrial dysfunction in cardiac aging. Recent research has demonstrated that mitochondrial dysfunction can disrupt morphology, signaling pathways, and protein interactions; conversely, mitochondrial homeostasis is maintained by mechanisms that include fission/fusion, autophagy, and unfolded protein responses. Finally, we describe some of the recent findings in mitochondrial targeted treatments to help meet the challenges of mitochondrial dysfunction in aging. [ABSTRACT FROM AUTHOR]

Cardiac aging is an intrinsic process that results in impaired cardiac function, along with cellular and molecular changes. These degenerative changes are intimately associated with quality control mechanisms. This review provides a general overview of the clinical and cellular changes which manifest in cardiac aging, and the quality control mechanisms involved in maintaining homeostasis and retarding aging. These mechanisms include autophagy, ubiquitin-mediated turnover, apoptosis, mitochondrial quality control and cardiac matrix homeostasis. Finally, we discuss aging interventions that have been observed to impact cardiac health outcomes. These include caloric restriction, rapamycin, resveratrol, GDF11, mitochondrial antioxidants and cardiolipin-targeted therapeutics. A greater understanding of the quality control mechanisms that promote cardiac homeostasis will help to understand the benefits of these interventions, and hopefully lead to further improved therapeutic modalities. [ABSTRACT FROM AUTHOR]

Abstract: BAC arrays were used to evaluate genomic instability along the colon of patients with ulcerative colitis (UC). Genomic instability increases with disease progression and biopsies more proximal to dysplasia showed increased instability. Pan-colonic field copy number gain or loss involving small (<1Mb) regions were detected in most patients and were particularly apparent in the UC progressor patients who had dysplasia or cancer. Chromosomal copy gains or losses affecting large regions were mainly restricted to dysplastic biopsies. Areas of significant chromosomal losses were detected in the UC progressors on chromosomes 2q36, 3q25, 3p21, 4q34, 4p16.2, 15q22, and 16p13 (p-value⩽0.04). These results extend our understanding of the dynamic nature of pan-colonic genomic instability in this disease. [Copyright &y& Elsevier]

Objectives: We investigated the effect of reducing mitochondrial oxidative stress by the mitochondrial-targeted antioxidant peptide SS-31 in hypertensive cardiomyopathy. Background: Oxidative stress has been implicated in hypertensive cardiovascular diseases. Mitochondria and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase have been proposed as primary sites of reactive oxygen species (ROS) generation. Methods: The mitochondrial targeted antioxidant peptide SS-31 was used to determine the role of mitochondrial oxidative stress in angiotensin II (Ang)-induced cardiomyopathy as well as in Gαq overexpressing mice with heart failure. Results: Ang induces mitochondrial ROS in neonatal cardiomyocytes, which is prevented by SS-31, but not the nontargeted antioxidant N-acetyl cysteine (NAC). Continuous administration of Ang for 4 weeks in mice significantly increased both systolic and diastolic blood pressure, and this was not affected by SS-31 treatment. Ang was associated with up-regulation of NADPH oxidase 4 (NOX4) expression and increased cardiac mitochondrial protein oxidative damage, and induced the signaling for mitochondrial biogenesis. Reducing mitochondrial ROS by SS-31 substantially attenuated Ang-induced NOX4 up-regulation, mitochondrial oxidative damage, up-regulation of mitochondrial biogenesis, and phosphorylation of p38 mitogen-activated protein kinase and prevented apoptosis, concomitant with amelioration of Ang-induced cardiac hypertrophy, diastolic dysfunction, and fibrosis, despite the absence of blood pressure-lowering effect. The NAC did not show any beneficial effect. The SS-31 administration for 4 weeks also partially rescued the heart failure phenotype of Gαq overexpressing mice. Conclusions: Mitochondrial targeted peptide SS-31 ameliorates cardiomyopathy resulting from prolonged Ang stimulation as well as Gαq overexpression, suggesting its potential clinical application for target organ protection in hypertensive cardiovascular diseases. [Copyright &y& Elsevier]

Abstract: Werner syndrome (WS) is a human autosomal recessive genetic instability and cancer predisposition syndrome with features of premature aging. Several genetically determined mouse models of WS have been generated, however, none develops features of premature aging or an elevated risk of neoplasia unless additional genetic perturbations are introduced. In order to determine whether differences in cellular phenotype could explain the discrepant phenotypes of Wrn −/− mice and WRN-deficient humans, we compared the cellular phenotype of newly derived Wrn −/− mouse primary fibroblasts with previous analyses of primary and transformed fibroblasts from WS patients and with newly derived, WRN-depleted human primary fibroblasts. These analyses confirmed previously reported cellular phenotypes of WRN-mutant and WRN-deficient human fibroblasts, and demonstrated that the human WRN-deficient cellular phenotype can be detected in cells grown in 5% or in 20% oxygen. In contrast, we did not identify prominent cellular phenotypes present in WRN-deficient human cells in Wrn −/− mouse fibroblasts. Our results indicate that human and mouse fibroblasts have different functional requirements for WRN protein, and that the absence of a strong cellular phenotype may in part explain the failure of Wrn −/− mice to develop an organismal phenotype resembling Werner syndrome. [Copyright &y& Elsevier]

Oxidative and nitrosative damage are major contributors to cone cell death in retinitis pigmentosa (RP). In this study, we explored the effects of augmenting components of the endogenous antioxidant defense system in models of RP, rd1, and rd10 mice. Unexpectedly, overexpression of superoxide dismutase 1 (SOD1) in rd1 mice increased oxidative damage and accelerated cone cell death. With an elaborate mating scheme, genetically engineered rd10 mice with either inducible expression of SOD2, Catalase, or both in photoreceptor mitochondria were generated. Littermates with the same genetic background that did not have increased expression of SOD2 nor Catalase provided ideal controls. Coexpression of SOD2 and Catalase, but not either alone, significantly reduced oxidative damage in the retinas of postnatal day (P) 50 rd10 mice as measured by protein carbonyl content. Cone density was significantly greater in P50 rd10 mice with coexpression of SOD2 and Catalase together than rd10 mice that expressed SOD2 or Catalase alone, or expressed neither. Coexpression of SOD2 and Catalase in rd10 mice did not slow rod cell death. These data support the concept of bolstering the endogenous antioxidant defense system as a gene-based treatment strategy for RP, and also indicate that coexpression of multiple components may be needed.Molecular Therapy (2009) 17 5, 778–786 doi:10.1038/mt.2009.47 [ABSTRACT FROM AUTHOR]

Summary: Background: Aspirin and other non-steroidal anti-inflammatory drugs (NSAID) probably decrease the risk of colorectal neoplasia; however their effect on development of oesophageal adenocarcinoma is less clear. We aimed to assess the role of NSAID in the development of oesophageal adenocarcinoma and precursor lesions in people with Barrett''s oesophagus—a metaplastic disorder that confers a high risk of oesophageal adenocarcinoma. Methods: We did a prospective study of the relation between duration, frequency, and recency of NSAID use and the risk of oesophageal adenocarcinoma, aneuploidy, and tetraploidy in a cohort of 350 people with Barrett''s oesophagus followed for 20 770 person-months. We used proportional-hazards regression to calculate hazard ratios (HR) adjusted for age, sex, cigarette use, and anthropometric measurements. Findings: Median follow-up was 65·5 months (range 3·1–106·9). Compared with never users, HR for oesophageal adenocarcinoma (n=37 cases) in current NSAID users was 0·32 (95% CI 0·14–0·76), and in former users was 0·70 (0·31–1·58). 5-year cumulative incidence of oesophageal adenocarcinoma was 14·3% (95% CI 9·3–21·6) for never users, 9·7% (4·5–20·5) for former users, and 6·6% (3·1–13·6) for current NSAID users. When changes in NSAID use during follow up were taken into account, the associations were strengthened: HR for oesophageal adenocarcinoma for current users at baseline or afterwards was 0·20 (95% CI 0·10–0·41) compared with never users. Compared with never users, current NSAID users (at baseline and follow-up) had less aneuploidy (n=35 cases; 0·25 [0·12–0·54]) and tetraploidy (n=45 cases; 0·44 [0·22–0·87]). Interpretation: NSAID use might be an effective chemopreventive strategy, reducing the risk of neoplastic progression in Barrett''s oesophagus. [Copyright &y& Elsevier]

Abstract: Ulcerative colitis (UC) is an inflammatory disease of the colon that is associated with increased risk of colorectal cancer associated with genomic instability. We have previously demonstrated that genomic instability is present in UC patients with colonic neoplasia, and hypothesized that the chromosomal alterations may be taking place in regions that are susceptible to mutation or that provide a growth advantage to a cell undergoing neoplastic transformation. In this study, we used two polymerase chain reaction (PCR)-based DNA fingerprinting techniques (arbitrarily primed PCR and inter-simple-sequence-repeat PCR) to study the process of genomic instability. The two techniques of DNA fingerprinting cross-validate the instability observed in these studies. We analyzed the molecular basis of 10 commonly altered DNA bands obtained from DNA fingerprints of biopsies from various histologic grades of UC patients with dysplasia or cancer (UC Progressors). We determined that the band changes in the fingerprint truly represent changes in DNA sequence, and that the fingerprinting provides highly reproducible results. Furthermore, our investigation revealed that 40% of alterations involve repetitive sequences. Two frequently deleted sequences in 6q27 and 2q14 were studied further because they were frequently abnormal in the dysplastic and nondysplastic tissue of UC Progressors. The losses from 6q27 and 2q14 were confirmed by loss of heterozygosity and real-time PCR analysis. Both of these regions in chromosomes 6 and 2 are surrounded by highly repetitive and mobile LINE-1 elements, possibly making the region susceptible to mutational change. These regions were affected (lost) in UC Progressors but not in UC patients who were neoplasia free. Loss of heterozygosity at 6q27 has been described in ovarian and other cancers, while the 2q14 region has been implicated in prostate and sporadic colon cancers. Both regions are likely to contain tumor-suppressor genes. In conclusion, the genomic instability in UC Progressors can occur in regions that are susceptible to change and are locations of putative tumor-suppressor genes. [Copyright &y& Elsevier]

The Werner syndrome (WS) protein (WRN), a DNA helicase/exonuclease, is required for genomic stability and avoidance of cancer. Current evidence suggests that WRN is involved in the resolution of stalled and/or collapsed replication forks. This function is indicated, in part, by replication defects in WS cells and by hypersensitivity to agents causing major structural aberrations in DNA that block replication. We show here that antisense suppression of WRN in two human glioma cell lines reproduces hallmarks of the drug cytotoxicity profile of WS cells, namely, hypersensitivity to 4-nitroquinoline 1-oxide, camptothecin and hydroxyurea. We also show that antisense-treated cells are hypersensitive to methyl-lexitropsin, a site-specific alkylating agent that produces mainly N3-methyladenine, a cytotoxic and replication-blocking lesion. Antisense-treated cells are hypersensitive to O6-methylguanine adducts as well, but only when repair by O6-methylguanine–DNA methyltransferase is lacking. Our results illustrate the drug sensitivity caused by deficiency of WRN in a uniform genetic background. They extend the WRN DNA damage sensitivity spectrum to methyl base adducts that can result in blocked replication, and suggest that WRN may be required for resumption of processive replication when incomplete repair of DNA damage leaves blocking lesions at forks. The evidence that highly disparate lesions fall within the purview of WRN, and that abrogating DNA repair can reveal dependence on WRN, suggests that WRN may protect the genome from the lethal, mutagenic and carcinogenic effects of widely diverse DNA damage arising from endogenous processes and environmental agents. [Copyright &y& Elsevier]

Presents a study that focused on the use of oligonucleotide-based microarrays to characterize gene expression profiles in each of Barrett's esophagus (BE) tissues. Similarity of BE to each of the normal tissues; Description of the Barrett's esophagus condition; Complication in persons with chronic gastroesophageal reflux disease.