Ambient air pollution, asthma drug response, and telomere length in African American youth.

BACKGROUND: Telomere length (TL) can serve as a potential biomarker for conditions associated with chronic oxidative stress and inflammation, such as asthma. Air pollution can induce oxidative stress. Understanding the relationship between TL, asthma, and air pollution is important for identifying risk factors contributing to unhealthy aging in children. OBJECTIVES: We sought to investigate associations between exposures to ambient air pollutants and TL in African American children and adolescents and to examine whether African ancestry, asthma status, and steroid medication use alter the association. METHODS: Linear regression was used to examine associations between absolute telomere length (aTL) and estimated annual average residential ozone (O3) and fine particulate matter with a diameter of 2.5 µm or less (PM2.5) exposures in a cross-sectional analysis of 1072 children in an existing asthma case-control study. African ancestry, asthma status, and use of steroid medications were examined as effect modifiers. RESULTS: Participants' aTLs were measured by using quantitative PCR. A 1-ppb and 1 µg/m3 increase in annual average exposure to O3 and PM2.5 were associated with a decrease in aTL of 37.1 kilo-base pair (kb; 95% CI, -66.7 to -7.4 kb) and 57.1 kb (95% CI, -118.1 to 3.9 kb), respectively. African ancestry and asthma were not effect modifiers; however, exposure to steroid medications modified the relationships between TL and pollutants. Past-year exposure to O3 and PM2.5 was associated with shorter TLs in patients without steroid use. CONCLUSION: Exposure to air pollution was associated with shorter TLs in nonasthmatic children and adolescents. This was not the case for asthmatic children as a group, but those receiving steroid medication had less shortening than those not using steroids. Reduced exposure to air pollution in childhood might help to preserve TL.

Glutathione Depletion, Pentose Phosphate Pathway Activation, and Hemolysis in Erythrocytes Protecting Cancer Cells from Vitamin C-induced Oxidative Stress.

The discovery that oxidized vitamin C, dehydroascorbate (DHA), can induce oxidative stress and cell death in cancer cells has rekindled interest in the use of high dose vitamin C (VC) as a cancer therapy. However, high dose VC has shown limited efficacy in clinical trials, possibly due to the decreased bioavailability of oral VC. Because human erythrocytes express high levels of Glut1, take up DHA, and reduce it to VC, we tested how erythrocytes might impact high dose VC therapies. Cancer cells are protected from VC-mediated cell death when co-cultured with physiologically relevant numbers of erythrocytes. Pharmacological doses of VC induce oxidative stress, GSH depletion, and increased glucose flux through the oxidative pentose phosphate pathway (PPP) in erythrocytes. Incubation of erythrocytes with VC induced hemolysis, which was exacerbated in erythrocytes from glucose-6-phosphate dehydrogenase (G6PD) patients and rescued by antioxidants. Thus, erythrocytes protect cancer cells from VC-induced oxidative stress and undergo hemolysis in vitro, despite activation of the PPP. These results have implications on the use of high dose VC in ongoing clinical trials and highlight the importance of the PPP in the response to oxidative stress.

FDA Approval Summary: Olaparib Monotherapy in Patients with Deleterious Germline BRCA-Mutated Advanced Ovarian Cancer Treated with Three or More Lines of Chemotherapy.

On December 19, 2014, the FDA approved olaparib capsules (Lynparza; AstraZeneca) for the treatment of patients with deleterious or suspected deleterious germline BRCA-mutated (gBRCAm) advanced ovarian cancer who have been treated with three or more prior lines of chemotherapy. The BRACAnalysis CDx (Myriad Genetic Laboratories, Inc.) was approved concurrently. An international multicenter, single-arm trial enrolled 137 patients with measurable gBRCAm-associated ovarian cancer treated with three or more prior lines of chemotherapy. Patients received olaparib at a dose of 400 mg by mouth twice daily until disease progression or unacceptable toxicity. The objective response rate (ORR) was 34% with median response duration of 7.9 months in this cohort. The most common adverse reactions (≥20%) in patients treated with olaparib were anemia, nausea, fatigue (including asthenia), vomiting, diarrhea, dysgeusia, dyspepsia, headache, decreased appetite, nasopharyngitis/pharyngitis/upper respiratory infection, cough, arthralgia/musculoskeletal pain, myalgia, back pain, dermatitis/rash, and abdominal pain/discomfort. Myelodysplatic syndrome and/or acute myeloid leukemia occurred in 2% of the patients enrolled on this trial.

Protease analysis by neoepitope approach reveals the activation of MMP-9 is achieved proteolytically in a test tissue cartilage model involved in bone formation.

A principle of regulation of matrix metalloproteinase (MMP) activity has been introduced as the cysteine-switch mechanism of activation (Springman et al. 1990). According to this mechanism, a critical Cys residue found in the auto-inhibitory propeptide domain of latent proenzyme is important to determine whether or not activation is turned on or off. The mechanism further allows for multiple modes of activation. To determine whether or not activation is accomplished proteolytically within a rat test cartilage model, protease analysis by the neoepitope approach, which relies upon a set of antibodies, was applied. One is used to identify the MMP-9 proenzyme bearing the critical cysteine residue, the other to identify any enzyme present bearing a new NH2-terminus 89FQTFD. This is indicative of MMP-9 lacking the cysteine switch. The antibody set has been applied to frozen tissue sections and analyzed by light and electron microscopic methods. Results reveal that activation of the MMP-9 protease involves limited proteolysis resulting in propeptide domain release. Here we report the observed changes of protease form to indigenous cells and extracellular matrix, thereby making it possible to uncover the features of MMP-9 activation within a specified set of tissue circumstances where a cartilage model is transformed into definitive bone. This manuscript contains online supplemental material at http://www.jhc.org. Please visit this article online to view these materials.