Diurnal variations in salivary protein carbonyl levels in normal and cognitively impaired human subjects

Oxidative stress has been documented in tissues and biofluids of subjects with sporadic Alzheimer disease (AD) and mild cognitive impairment (MCI). The aim of this study was to determine whether (a) salivary protein carbonyls are elevated in AD and MCI subjects, (b) salivary protein carbonyl contents in these groups exhibit diurnal variation, and (c) apolipoprotein E ɛ4 (apoE ɛ4) carrier status impacts salivary carbonyl concentrations or rhythmicity in the AD and MCI cohorts. Unstimulated saliva was collected at fixed intervals between 8 AM and 10 PM from 15 AD subject , 21 MCI subjects, and 30 cognitively-intact controls. Salivary protein carbonyl concentrations were measured by ELISA. ApoE genotyping was performed on the AD and MCI individuals. For all groups, mean protein carbonyl contents were significantly elevated at 2 PM relative to other time points surveyed. Mean salivary protein carbonyl concentrations did not differ among the diagnostic groups. ApoE ɛ4 carriers exhibited less temporal variation in salivary protein carbonyls relative to noncarriers. Thus, protein carbonyl content exhibits diurnal variation in adult human saliva. ApoE ɛ4 carrier status may impact oropharyngeal disease expression by attenuating the inherent diurnal variability in salivary redox homeostasis. Salivary protein carbonyls do not differentiate AD and MCI from normal individuals. In conclusion, oxidative stress has been documented in tissues and biofluids of subjects with sporadic AD and MCI. This article demonstrates that levels of protein carbonyls, a marker of oxidative stress, exhibit robust diurnal variation in the saliva of normal elderly, MCI, and AD subjects. Apolipoprotein E ɛ4 allele carrier status may attenuate this temporal variability in salivary redox homeostasis and thereby impact the natural history of oropharyngeal diseases.     

Rapamune Does Not Attenuate High Cholesterol-Induced Atherosclerosis in Rabbits

Solid-organ transplant recipients are prone to develop atherosclerosis. The objectives of this study were to investigate the effects of Rapamune (Wyeth Canada, Saint-Larent, QC, Canada) on the rabbit model of atherosclerosis. The rabbits were assigned to four groups: group I, regular diet (control); group II, 1% cholesterol diet; group III, control with Rapamune (1 mg/kg/d orally); and group IV, high cholesterol diet with Rapamune. Blood samples for serum lipids (triglycerides [TG], total cholesterol [TC], low-density lipoprotein cholesterol [LDL-C], high-density lipoprotein cholesterol [HDL-C]), as well as malondialdehyde, and protein carbonyls, the indices of oxidative stress were collected at the end of 2 months on the respective diet regimen. Aortic tissue for atherosclerotic changes were also collected for oxidative stress indices were also collected. Rapamune reduced serum levels of TG, TC, LDL-C, and HDL-C. Rapamune elevated the oxidative stress in rabbits on high cholesterol diet. Rapamune did not attenuate extent of atherosclerosis (group II vs. group IV, 45.00 ± 12.00 vs. 57.28 ± 2.99%); intimal thickness (group II vs. group IV, 32.38 ± 7.14 × 10³ vs. 21.90 ± 11.98 × 10³ μm²); intimal/medial ratio (group II vs. group IV, 0.50 ± 0.06 vs. 0.35 ± 0.06); and macrophage accumulation (group II vs. group IV, 69.72 ± 5.02 vs. 61.52 ± 8.94%) in the intima of rabbits on high cholesterol diet. The data suggest that (1) Rapamune increased the oxidative stress in rabbits on high cholesterol diet and (2) Rapamune did not attenuate the hypercholesterolemic atherosclerosis in the rabbit model.     

Mutagenicity of beta-alkyl substituted acrolein congeners in the Salmonella typhimurium strain TA100 and genotoxicity testing in the SOS chromotest.

The beta-alkyl substituted acrolein congeners crotonaldehyde, trans-2-pentenal, trans-2-hexenal, 2,4-hexadienal, and trans-2-heptenal were clearly mutagenic in a slightly modified preincubation Ames test with Salmonella typhimurium TA100 with and without S9 mix using a threefold bacterial cell density and a 90-min preincubation time, whereas trans-cis-2,6-nonadienal did not show any mutagenic activity. The greatest impediment to adequate mutagenicity testing of these compounds is their toxicity toward bacteria. Within the congener family tested, toxicity increases as a function of both chain length and lipophilicity, and it becomes more and more difficult to demonstrate mutagenicity. Mutagenicity decreases with increasing chain length. This effect may be explained by increasing toxicity. The effect of S9 mix seems to be mostly nonenzymatic detoxication by nonspecific scavanger protection of bacterial cytotoxicity. No indication could be found that bioactivation plays a role in S9-mediated reduction of bacterial cytotoxicity. Although positive mutagenic outcomes could be obtained with the SOS chromotest for other alpha, beta-unsaturated carbonyl compounds, these acrolein congeners were not genotoxic in this test, most probably because they are toxic for the Escherichia coli bacteria PQ37 and PQ243.     

Biliary proteins and their redox status changes in gallstone patients

Background Proteins might act as pronucleating agents of cholesterol crystallization in bile. However, little is known about the redox status of biliary proteins in humans and their interaction with crystallization of biliary cholesterol. Materials and methods Gallbladder biles were obtained at cholecystectomy from 86 symptomatic patients with either cholesterol gallstones (32 multiple and 32 solitary stones) or pigment stones (n = 22), and studied for protein redox status [carbonyl and sulfhydryl (PSH) concentrations], total lipid and protein levels and cholesterol saturation index (CSI). First appearance of cholesterol crystals in ultrafiltered bile (crystal observation time, COT) was studied with polarizing light microscopy during 21 days. Results Patients with cholesterol stones had significantly shorter COT (3 days vs. >21 days, P < 0·05), higher CSI (149 ± 10% vs. 97 ± 7%, P < 0·05) and higher total biliary proteins (1·96 ± 0·1 mg mL^?1 vs. 0·55 ± 0·1 mg mL^?1, P < 0·05) than patients with pigment stones. Patients with cholesterol stones had significantly lower (P < 0·05) level of protein sulfhydryl concentrations (18 ± 4 nmol mg^?1 protein vs. 49 ± 16 nmol mg^?1 protein), while total lipid and carbonyl proteins concentrations were similar between cholesterol and pigment stone patients. Crystallization probability was influenced by the number/type of gallstones (multiple > solitary > pigment stones, P = 0·009) and total protein concentration (high > low levels, P = 0·004). COT was negatively correlated with total protein content (r = ?0·45, P = 0·03). Conclusions Biles with cholesterol stones show high CSI and total protein concentration, and rapid COT, which is even faster in patients with multiple stones and high protein concentration. Low PSH levels in cholesterol stone patients point to a biochemical shift, potentially able to affect cholesterol crystallization.     

Foliar CO2 fixation in bean (Phaseolus vulgaris L.) submitted to elevated ozone: distinct changes in Rubisco and PEPc activities in relation to pigment content

Using open-top chambers, the impact of ozone (O(3)) on foliar carboxylases of bean (Phaseolus vulgaris L.) was investigated. From sowing, beans were exposed to non-filtered air (NF) and NF supplied with 40 (+40) and 80 (+80) nL L(-1) O(3). Twenty days after emergence, primary and first trifoliate leaves were sampled. Biochemical characteristics of leaves from +40 were quite similar to those from NF. Conversely, +80 induced distinct biochemical effects in primary and first trifoliate leaves. Regarding primary leaves, +80 reduced ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) activity by 33% whereas it stimulated phosphoenolpyruvate carboxylase (PEPc) activity by 376%. The reduction in Rubisco activity was accompanied by a decrease in both Rubisco subunit amounts and a consistent oxidative modification of the Rubisco small subunit (SSU). These changes came with a drastic loss in pigmentation. Regarding first trifoliate leaves, +80 stimulated Rubisco activity by 33% while it disturbed neither PEPc activity nor pigmentation. Surprisingly, the enhanced Rubisco activity was associated with a slight decrease in Rubisco protein quantity, which was not coupled with the formation of carbonyl groups in Rubisco-SSU.     

Positive correlation between insulin resistance and iron overload-induced oxidative stress in patients with fanconi anemia (FA)- and non-FA-related bone marrow failure: The results of a multicenter study

This study investigated the relationship between DNA, protein, and lipid oxidations and insulin resistance in patients with Fanconi anemia (FA)- and non-FA-related bone marrow failure. Sixteen patients with FA, 7 non–FA-related aplastic anemia, and 10 controls were included in the study. Fasting blood glucose, simultaneous insulin, hepcidin, ferritin, 8-hydroxy deoxyguanosine (8-OHdG), protein carbonyls, malondialdehyde (MDA), and homeostatic model assessment–insulin resistance (HOMA-IR) were investigated in the patients and controls. Diepoxybutane test–positive (DEB+) patients were diagnosed with FA, whereas DEB-patients were diagnosed as non-FA. 8-OHdG levels in both FA and non-FA patients were significantly higher than those in the controls (P = .001 and P = .005, respectively). Serum ferritin levels were also higher in FA and non-FA patients than in the controls (P = .0001 and P = .005, respectively). Insulin resistance (IR) was significantly higher in FA patients than in non-FA patients and controls (P = .005 and P = .015, respectively). Significant differences were observed between 8-OHdG, ferritin, and MDA levels in patients with or without IR (P = .009, P = .001, and P = .013, respectively). Moderate and strong relations of 44% and 85% were determined between IR and ferritin levels in patients with FA or non-FA (P = .08 and P = .014, respectively). FA and non-FA patients exhibited a tendency to IR. IR was related to ferritin levels, and ferritin levels were also correlated with oxidative stress. These findings suggest that the increased rate of IR in patients with FA and non-FA may derive from increased oxidative stress, which may in turn be due to elevated serum ferritin levels.     

Increased plasma malondialdehyde and protein carbonyl levels and lymphocyte DNA damage in patients with angiographically defined coronary artery disease

We investigated the oxidative modifications of lipids, proteins and DNA, three potential molecular targets of oxidative stress, in 30 patients with angiographically defined coronary artery disease (CAD) and 30 healthy control subjects. In addition, we examined relationships between these oxidative modifications and the severity of vascular lesions in patients with CAD. Malondialdehyde (MDA) and protein carbonyl (PC) levels, as well as ferric reducing antioxidant power (FRAP), were measured in the plasma. DNA damage was evaluated as single strand breaks (SSBs), formamidopyrimidine glycosylase (Fpg) and endonuclease III (E-III)-sensitive sites by the comet assay in DNA isolated from lymphocytes. MDA and PC levels increased, but FRAP values decreased, in patients as compared to controls. However, these values did not vary with the number of affected coronary vessels and were not correlated with Duke score, a parameter of the severity of vascular lesions in patients with CAD. We also found that lymphocyte DNA damage (SSBs, Fpg and E-III sites) were increased in patients. Although there were no significant differences in SSBs values in patients grouped according to affected vessel number, Fpg and E-III sites increased. We also detected significant correlations between Duke scores and SSBs and Fpg sites. Serum cholesterol, triglyceride and LDL-cholesterol levels were found to increase, but HDL-cholesterol levels decreased in CAD patients, but these lipids were not correlated with Duke scores. The results of this study reinforce the presence of increased combined oxidative modifications in lipid, protein and DNA in patients with CAD. However, lymphocyte DNA damage seems to be a more reliable assay than MDA and PC determinations to detect the severity of vascular lesions in patients.     

Protection of lipid peroxidation and carbonyl formation in proteins by capsaicin in human erythrocytes subjected to oxidative stress

Capsaicin (8-methyl-N-vanillyl-6-nonemide) is the major pungent principle found in hot peppers of the plant genus Capsicum. The present work was undertaken to investigate the antioxidative property of capsaicin on markers of oxidative stress; membrane lipid peroxidation (formation of malondialdehyde) and membrane carbonyl groups in human erythrocytes. The effect of capsaicin has been compared with l-ascorbic acid. Subjecting erythrocytes to oxidative stress by incubating them with t-BHP caused a significant increase in MDA level and protein carbonyl group content above the basal value. The presence of capsaicin (10 microm) in the incubation medium protected the erythrocytes from t-BHP-induced oxidative stress as evidenced by the decrease in MDA level and protein carbonyl group content, l-ascorbic acid also showed similar protective effect. The results conclusively prove the efficacy of the antioxidant property of capsaicin. This evidence suggests that dietary factors that act as antioxidants to decrease membrane lipid peroxidation and protein carbonyl formation may contribute to a protective effect against cancer, atherosclerosis and age related diseases. This antioxidant effect may, in part, explain the high consumption of capsicum in certain regions of the world.     

Effect of insulin and growth hormone on rat heart and liver oxidative stress in control and caloric restricted animals

In order to know if insulin-like signalling is involved in the control of oxidative stress in mammalian tissues in relation to aging, ad libitum-fed and caloric restricted Wistar rats were treated during 2 weeks with GH and insulin. The most consistent effect of the hormonal treatments was an increase in plasma IGF-1 levels. Caloric restriction during 6 weeks decreased ROS generation and oxidative DNA damage in heart mitochondria and this was reversed by insulin treatment. The decrease in oxidative damage to liver nuclear DNA induced by caloric restriction was also reversed by GH and insulin. In the liver, however, insulin and GH decreased mitochondrial ROS generation while they increased oxidative damage to mitochondrial DNA. GH and insulin decreased three different markers of oxidative modification of liver proteins, while they increased lipoxidation-dependent markers. This last result is related to the increase in phospholipid unsaturation induced in the liver by both hormones. The results suggest that the idea that insulin-like signalling controls oxidative stress in mammals cannot be generalized since both prooxidant and protective effects of GH and insulin are observed depending on the particular parameter and tissue selected.     

Effects of concurrent exercise training on muscle dysfunction and systemic oxidative stress in older people with COPD

Oxidative stress is associated with disease severity and limb muscle dysfunction in COPD. Our main goal was to assess the effects of exercise training on systemic oxidative stress and limb muscle dysfunction in older people with COPD. Twenty‐nine outpatients with COPD (66‐90 years) were randomly assigned to a 12‐week exercise training (ET; high‐intensity interval training (HIIT) plus power training) or a control (CT; usual care) group. We evaluated mid‐thigh muscle cross‐sectional area (CSA; computed tomography); vastus lateralis (VL) muscle thickness, pennation angle, and fascicle length (ultrasonography); peak VO₂ uptake (VO_2peak) and work rate (W_peak) (incremental cardiopulmonary exercise test); rate of force development (RFD); maximal muscle power (P_max; force‐velocity testing); systemic oxidative stress (plasma protein carbonylation); and physical performance and quality of life. ET subjects experienced changes in mid‐thigh muscle CSA (+4%), VL muscle thickness (+11%) and pennation angle (+19%), VO_2peak (+14%), W_peak (+37%), RFD (+32% to 65%), P_max (+38% to 51%), sit‐to‐stand time (?24%), and self‐reported health status (+20%) (all P < 0.05). No changes were noted in the CT group (P > 0.05). Protein carbonylation decreased among ET subjects (?27%; P < 0.05), but not in the CT group (P > 0.05). Changes in protein carbonylation were associated with changes in muscle size and pennation angle (r = ?0.44 to ?0.57), exercise capacity (r = ?0.46), muscle strength (r = ?0.45), and sit‐to‐stand performance (r = 0.60) (all P < 0.05). The combination of HIIT and power training improved systemic oxidative stress and limb muscle dysfunction in older people with COPD. Changes in oxidative stress were associated with exercise‐induced structural and functional adaptations.