No effect of cigarette smoking dose on oxidized plasma proteins

Abstract

Cigarette smoking is a major source of oxidative stress. Protein carbonyls have been used as a biomarker of oxidative stress because of the relative stability of carbonylated proteins and the high protein concentration in blood. Increased levels of carbonyl groups have been found in serum proteins of smokers compared to nonsmokers. However, neither the dose effect of current cigarette smoke nor other predictors of oxidative stress have been studied. Hence, we used an Enzyme-Linked Immunosorbent Assay (ELISA) to evaluate plasma protein carbonyls in smokers recruited in the Early Lung Cancer Action Project (ELCAP) program. The lung cancer screening program enrolled current and former smokers age 60 years and over without a prior cancer diagnosis. A total of 542 participants (282 men and 260 women) completed a baseline questionnaire and provided blood samples for the biomarker study. Protein oxidation was measured by derivatization of the carbonyl groups with 2,4-dinitrophenylhydrazine (DNPH) and ELISA quantitation of the DNPH group. Current smoking status was confirmed with urinary cotinine. The mean (+/-S.D.) protein carbonyl level was 17.9+/-2.9 nmol carbonyl/ml plasma. Protein carbonyls did not differ significantly by gender. Carbonyl levels were higher among current than former smokers, but these differences did not attain statistical significance, nor did differences by urine cotinine levels, pack-years, pack/day among current smokers, and smoking duration. In a multiple regression analysis, higher protein carbonyl levels were independently associated with increasing age (0.59 nmol/ml increase per 10 years, 95% CI 0.14, 1.05, p=0.01), African-American vs. white race/ethnicity, (1.30 nmol/ml, 95% CI 0.4, 2.19, p=0.008), and lower educational attainment (0.75 nmol/ml, 95% CI 0.12, 1.38, p=0.02). Although we found no significant difference between current vs. past cigarette smoking and protein carbonyls in this older group of smokers, associations were found for age, ethnicity, and educational attainment. Our results indicate that the measurement of plasma carbonyls by this ELISA technique is still an easy and suitable method for studies of diseases related to oxidative stress.

Plasma carbonyls do not correlate with lung function or computed tomography measures of lung density in older smokers

“…The Western blot study also examined differences in oxidized serum proteins between heavy and light smokers and found none. We also found no association of protein carbonyl content with cumulative or current smoking dose in the EMCAP study, although associations were found with age, ethnicity, educational attainment and obesity in this cohort (Yeh et al 2008), in agreement with prior studies (Baynes 1991, Giugliano et al 1996. Several studies have shown that protein carbonylation increases with the age of cells, organelles and tissues of varied species and has been associated to an exponential increase in molecular oxidative damage due to senescence of cells which leads to an imbalance with antioxidant mechanisms that occurs with age (reviewed by Chakravati & Chakravati 2007).…”

“…Protein carbonyls were measured on specimens stored for several years at −70°C. Stadtman and Levine (2003) have demonstrated the stability of protein carbonyls in storage for 10 years at −80°C and we have previously demonstrated expected associations in this cohort (Yeh et al 2008). …”

“…We previously validated use of this spirometer for this cohort against a dry seal, rolling-barrel spirometer (Barr et al 2008). Airflow obstruction was defined by a pre-bronchodilator FEV 1 /FVC (forced expiratory volume in one second/forced vital capacity) ratio <0.70, and severity was defined following ATS and ERS (European Respiratory Society) thresholds for COPD (Celli & MacNee 2004) based on pre-bronchodilator measures (>80% predicted, mild; 50-80% predicted, moderate and <50% predicted, severe).…”

Influence of Chronic Cigarette Smoking on Serum Biochemical Profile in Male Human Volunteers

“…: +91-8554-255761; Fax: +91-8554-255244; E-mail: vdp 1975@yahoo.co.in radicals and volatile aldehydes which are probably the major causes of damage to biomolecules. 4) The highly unstable free radicals attack important cellular constituents including DNA, proteins and other opportune targets, particularly cell membranes and the oxidative stress generated is implicated in the pathogenesis. 5,6) Electrolytes and minerals are involved as catalysts in most cellular enzyme catalyzed reactions and assume a major role in metabolism.…”

Effect of cigarette smoking on liver function test and some other related parameters

“…The risk of death in the smokers measured by the number of cigarettes smoked daily, the duration of smoking, the degree of inhalation and the age of initiation 3,4 . Cigarette smoke contains over 4000 different chemicals, 400 of which are proven to be carcinogenic; it also contains various oxidants such as oxygen free radicals and volatile aldehydes which are probably the major causes of damage to biomolecules 5 . Cigarette smoking yields chemical substances with high cytotoxic potentials 6 .…”