Selective peroxidation and externalization of phosphatidylserine in normal human epidermal keratinocytes during oxidative stress induced by cumene hydroperoxide

Reactive oxygen species not only modulate important signal transduction pathways, but also induce DNA damage and cytotoxicity in keratinocytes. Hydrogen peroxide and organic peroxides are particularly important as these chemicals are widely used in dermally applied cosmetics and pharmaceuticals, and also represent endogenous metabolic intermediates. Lipid peroxidation is of fundamental interest in the cellular response to peroxides, as lipids are extremely sensitive to oxidation and lipid-based signaling systems have been implicated in a number of cellular processes, including apoptosis. Oxidation of specific phospholipid classes was measured in normal human epidermal keratinocytes exposed to cumene hydroperoxide after metabolic incorporation of the fluorescent oxidation-sensitive fatty acid, cis-parinaric acid, using a fluorescence high-performance liquid chromatography assay. In addition, lipid oxidation was correlated with changes in membrane phospholipid asymmetry and other markers of apoptosis. Although cumene hydroperoxide produced significant oxidation of cis-parinaric acid in all phospholipid classes, one phospholipid, phosphatidylserine, appeared to be preferentially oxidized above all other species. Using fluorescamine derivatization and annexin V binding it was observed that specific oxidation of phosphatidylserine was accompanied by phosphatidylserine translocation from the inner to the outer plasma membrane surface where it may serve as a recognition signal for interaction with phagocytic macrophages. These effects occurred much earlier than any detectable changes in other apoptotic markers such as caspase-3 activation, DNA fragmentation, or changes in nuclear morphology. Thus, normal human epidermal keratinocytes undergo profound lipid oxidation with preference for phosphatidylserine followed by phosphatidylserine externalization upon exposure to cumene hydroperoxide. It is therefore likely that normal human epidermal keratinocytes exposed to similar oxidative stress in vivo would under go phosphatidylserine oxidation/translocation. This would make them targets for macrophage recognition and phagocytosis, and thus limit their potential to invoke inflammation or give rise to neoplastic transformations.     

The relationship between posttraumatic stress disorder and smoking outcome expectancies among U.S. military veterans who served since September 11, 2001

Posttraumatic stress disorder (PTSD) is associated with increased rates of smoking although little is known regarding the mechanisms underlying this relationship. The current study examined expectations about smoking outcomes among smokers with and without PTSD. The sample included 96 veterans (mean age of 34 years) and included 17% women and 50% racial minorities. Smoking expectancies were measured with the Smoking Consequences Questionnaire-Adult (Copeland, Brandon, & Quinn, 1995). Consistent with previous work suggesting that smokers with PTSD smoke in an effort to reduce negative affect, unadjusted analyses indicated that smokers with PTSD (n = 38) had higher expectations that smoking reduces negative affect than smokers without PTSD (d = 0.61). Smokers with PTSD also had increased expectancies associated with boredom reduction (d = 0.48), stimulation (d = 0.61), taste/sensorimotor manipulation aspects of smoking (d = 0.73), and social facilitation (d = 0.61). Results of hierarchical linear regression analyses indicated that PTSD symptom severity was uniquely associated with these expectancies beyond the effects of gender and nicotine dependence. More positive beliefs about the consequences of smoking may increase risk of continued smoking among those with PTSD who smoke. Further understanding of smoking expectancies in this group may help in developing interventions tailored for this vulnerable population.     

Oral Cancer Screening at Workplace in India��One-year Follow-up

Background:

Oral cancer remains the commonest form of cancer and cancer-related deaths among Indian males due to popularity of avoidable risk factors such as tobacco and alcohol use. A workplace oral cancer screening and tobacco cessation study was commenced on World No Tobacco Day 2007 at a chemical industry in rural Maharashtra.

Aims:

The objectives were to screen the employees for oral neoplasia and to correlate it with their tobacco consumption pattern. In addition, the objective was to provide tobacco cessation services at the workplace.

Materials and Methods:

This is an interventional cohort study among 104 employees of a chemical industrial unit in rural Maharashtra. Naked eye examination of the oral cavity was performed for all employees by a doctor irrespective of the tobacco habits at the beginning and at the end of 1 year. In between, the tobacco users were regularly examined during each follow-up.

Statistical analysis used:

Through personal interviews of the participants, data were manually recorded and were transferred to electronic data base. Data analysis was conducted in STATA™ 8.2 on intention to treat basis.

Results and Conclusions:

Among the 104 employees, 50 (48.08%) were current tobacco users at the beginning of the program. Oral precancers were seen exclusively among 20 (40%) tobacco users. After 1 year of workplace tobacco cessation intervention, 80% of oral precancers regressed. This shows that screening of the oral cavity at the workplace is effective when combined with tobacco cessation.     

Palmitoylcarnitine, and important component of the repair system in the synaptosome membrane, in oxidative stress

Oxidative stress is accompanied by a considerable rise of palmitic acid incorporation into phosphatidylethanolamine of synaptosome membranes due to activation of lysophosphatidylethanolamine palmitoyltransferase and carnitine palmitoyltransferase. In the absence of ATP carnitine palmitoyltransferase plays an essential role in reacylation of phosphatidylethanolamine, and palmitoylcarnitine serves as a reserve pool of palmitoyl coenzyme A. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 123, No. 6, pp. 649–652, June, 1997