Fabrizia Bamonti

Oxidative imbalance in patients with mild cognitive impairment and Alzheimer's disease

Increasing evidence supports a role of oxidative imbalance, characterized by impaired antioxidant enzymatic activity and increased reactive oxygen species (ROS) production, in mild cognitive impairment (MCI) and Alzheimers disease (AD) pathogenesis. Hyperhomocysteinemia, another risk factor for AD, also contributes to oxidative damage. Plasma total homocysteine (tHcy) and ROS levels, and total antioxidant capacity (TAC) were determined in 71 AD, 36 MCI and 28 vascular dementia (VaD) patients as well as in 44 age-matched controls. tHcy levels were significantly increased in patients with AD and VaD an a trend towards an increase in multiple domain MCI was observed. TAC was significantly decreased in AD as well as MCI, but not in VaD patients. In AD patients, a negative correlation was found between TAC and disease duration. ROS levels did not differ among groups, but were correlated with age. In conclusion, a pattern characterized by increased tHcy levels and decreased TAC is present in AD as well as MCI patients. While increased tHcy levels were also found in VaD, TAC modifications occur specifically in AD. ROS levels appear to be correlated with age rather than with a specific dementing disorder, thus leading to the hypothesis that oxidative imbalance observed in AD could be due to a decreased TAC.

Oxidative stress in kidney transplant patients.

Background. Little information is available about the role of oxidative stress in renal transplant patients. To evaluate the prevalence and severity of oxidative stress in renal transplantation, the authors conducted a cross-sectional study. Methods. In 112 cadaver or living-donor kidney transplant recipients with a follow-up of at least 6 months and with plasma creatinine less than or equal to 2.5 mg/dL, complete blood count, serum vitamin B12, serum folate (s-F), reactive oxygen species (ROS), thiol groups (−SH), total antioxidant activity (TAOC), serum homocysteine (Hcy), and intraerythrocyte folate (ery-F) were measured. Results. The mean levels of Hcy (21.1 &mgr;M vs. <10 &mgr;M), ROS (302.7 U. Carr (Carratelli units) vs. 250–300 U. Carr), and TAOC (410.6 &mgr;mol/HclO/mL vs. >350 &mgr;mol/HclO/mL), were higher than the reference interval, whereas −SH groups, vitamin B12, s-F, and ery-F were within the normal range. In the multivariate model, plasma creatinine (P =0.0062), vitamin B12 (P =0.0121), and TAOC (P =0.0007) were independently associated with oxidative stress. At multiple regression analysis, −SH groups and ROS were directly and inversely related to hematocrit (P =0.0007 and P =0.0073). There was also a negative correlation between −SH groups and blood pressure levels (P =0.0095). Conclusions. Renal transplant patients have a pattern of increased oxidant stress that is counterbalanced by an enhancement of the antioxidant mechanisms. Besides the well-known risk factors, the authors found that anemia is an independent risk factor for an increase of ROS. Further studies are needed to evaluate whether the correction of anemia might prevent or reduce the oxidative stress in renal transplant patients.

High tumor necrosis factor-α in levels in cerebrospinal fluid of cobalamin-deficient patients

We studied 14 patients with neurological manifestations of subacute combined degeneration (SCD) and 40 control patients not cobalamin (Cbl)‐deficient. The cerebrospinal fluid (CSF) markers of Cbl deficiency (Cbl and total homocysteine [tHCYS] levels) and the CSF levels of tumor necrosis factor (TNF)‐α and epidermal growth factor (EGF) were measured. Significantly higher levels of tHCYS and TNF‐α, and significantly lower levels of Cbl and EGF were found in the SCD patients. In human CSF, as in human serum and the rat central nervous system, decreased Cbl concentrations are concomitant with an increase in TNF‐α and a decrease in EGF‐levels. Ann Neurol 2004;56:886–890

Determinants of oxidative stress related to gender: relevance of age and smoking habit.

Abstract Background: Magnitude and major causes of oxidative stress may be different between sexes, although limitedly addressed in clinical studies with controversial results. The present study aimed to determine whether any gender-related difference exists concerning oxidative stress in a population of 332 subjects of both sexes, in a wide age range, with and without cigarette smoking habit. Methods: The Oxidative-INDEX was calculated after evaluation of serum hydroperoxides (ROMs) and total antioxidant capacity (OXY) by means of commercial kits (d-ROMs and Oxy-adsorbent Tests, Diacron, Italy) subtracting the OXY standardized variable from the ROMs standardized variable. Results: The Oxidative-INDEX resulted higher in women with respect to men (p<0.001), in smokers (p<0.01) than in non-smokers, and correlated with cigarette number (p<0.01), age (p<0.001), and post-menopausal status (p<0.001). The multivariate analysis identified age, high blood pressure, and smoking habit as factors independently associated with the Oxidative-INDEX in men, whereas cigarette smoking and age represented the independent risk factors for an elevated oxidative stress status in women. Conclusions: Gender-based differences in oxidative stress levels may provide a biochemical basis for the epidemiologic differences in the disease susceptibility between sexes, and suggest different strategies for risk assessment, diagnosis, and treatment specifically targeted to men and women.

Free and total plasma malondialdehyde in chronic renal insufficiency and in dialysis patients

BACKGROUND Available data about oxidative status in patients with end-stage renal disease (ESRD) or on dialysis are contradictory. The present cross-sectional study aimed to investigate the role of renal insufficiency and dialysis on lipid peroxidation. To separate the effects of uraemia from dialysis-induced stress, we enrolled 26 patients with renal insufficiency on conservative treatment (ESRD), 23 on peritoneal dialysis (PD), 30 on haemodialysis (HD) and 30 controls. METHODS Plasma malondialdehyde (MDA) levels, both total (tMDA) and free (fMDA), were measured as indexes of oxidative stress by gas chromatography-mass spectrometry. Bound MDA (bMDA) levels were calculated as the difference between tMDA and fMDA. RESULTS Total and bMDA concentrations were significantly higher in patients than in controls (ESRD > HD > PD). In PD and HD patients, fMDA levels were similar and significantly higher than in ESRD. Multivariate analysis, with tMDA, fMDA and bMDA as dependent variables, showed similar and significant tMDA and bMDA relations with residual renal function (t = -2.160, P = 0.035) and albumin (t = -2.049, P = 0.045). Erythropoietin dose affected only fMDA values (t = -2.178, P = 0.034). CONCLUSIONS Free and bMDA concentrations identified different MDA patterns. Bound MDA, not excreted by kidneys, accounts alone for high tMDA concentrations in ESRD patients, while both fMDA and bMDA contribute to tMDA values in dialysis patients. These findings show that increased tMDA could be indicative not only of recent lipid peroxidation, and they also highlight the importance of evaluating free, bound and total MDA in patients with reduced renal function in order to assess their oxidative status.

Oxidative stress and homocysteine metabolism in patients with lupus nephritis.

The objective of this study was to compare oxidative status and homocysteinemia in patients with lupus nephritis (LN) and in controls. Total antioxidant capacity (TAC), reactive oxygen species (ROS), homocysteine and related vitamins were measured in 68 patients with LN and in 50 controls. LN patients had lower TAC (p = 0.05) and higher ROS and homocysteinemia (p = 0.01) than controls. TAC, significantly lower in active than in quiescent LN (p = 0.01), was correlated with albuminemia (p = 0.02), inversely with proteinuria (p = 0.01) and anti-DNA antibodies (p = 0.004). ROS values, higher both in active and in inactive LN, correlated with age (p = 0.02), C-reactive protein (CRP) (p = 0.0005) and inversely with prednisone dosage (p = 0.05). At multivariate analysis, CRP (p = 0.04) and age (p = 0.005) were independent ROS predictors. Homocysteine, higher in active than in quiescent LN (p = 0.016) and in patients with antiphospholipid antibodies (p=0.05), correlated with serum creatinine (p = 0.00001) and proteinuria (p = 0.015). At multivariate analysis serum creatinine (p = 0.006) and active nephritis (p = 0.003) were independent predictors of hyperhomocysteinemia. Patients with LN showed impaired oxidative status, even without clinical signs of renal activity. ROS production may be counterbalanced by adequate antioxidant capacity in some patients with quiescent LN. The association of hyperhomocysteinemia and antiphospholipid antibodies positivity may increase the risk of cardiovascular and/or thrombotic events in LN patients. Lupus (2010) 19, 65—72.

Determination of serum holotranscobalamin concentrations with the AxSYM active B12 assay: cut-off point evaluation in the clinical laboratory

Abstract Background: A reliable early marker is required for diagnosis of cobalamin deficiency. We calculated an appropriate holotranscobalamin (HoloTC) cut-off point for identifying cobalamin deficiency using an immunoenzymatic assay. Methods: Determination of the cut-off threshold and correlation between HoloTC and the other diagnostic parameters routinely used for vitamin B12 deficiency [total vitamin B12 (tB12), folate, homocysteine] were measured in 250 routine blood specimens from 107 men (mean age 59.0±18.8 years) and 143 women (mean age 54.2±23.1 years). The inclusion criterion was serum tB12 concentration ≤221 pmol/L. Results: Analytical performance results agreed with those reported by others. A weak correlation (R=0.42) was found between HoloTC and tB12. A 40 pmol/L cut-off threshold was chosen for HoloTC and the associated sensitivity and specificity was 0.86 and 0.66, respectively. Out of 250 tested samples, 126 showed tB12 concentrations 139–221 pmol/L (gray zone, GZ) and 124 had tB12 concentrations <139 pmol/L (low, L). Values less than the cut-off for HoloTC were present in 68.2% and 37.9% of cases in the GZ and L group, respectively (p<0.01), and in 53.2% of subjects. Conclusions: Our results confirmed the analytical reliability of the AxSYM HoloTC assay. The method is adequate for routine use and a cut-off threshold of 40 pmol/L is appropriate for assessing cobalamin deficiency in populations with reduced tB12 values. Clin Chem Lab Med 2010;48:249–53.

Increased free malondialdehyde concentrations in smokers normalise with a mixed fruit and vegetable juice concentrate: a pilot study.

Abstract Background: Cigarette smoking, a cardiovascular risk factor leading to oxygen free radical formation, is involved in the development of serious pathological conditions. On the other hand, a healthy diet and adequate supplementation can help prevent many diseases. The aim of our study was to evaluate in healthy light smokers the effects of supplementation with mixed fruit and vegetable juice powder concentrate on homocysteine metabolism and oxidative status. Methods: In this pilot study, 32 healthy volunteers, 16 light smokers and 16 non-smokers, on twice daily supplementation were monitored at time zero and after 30days. Plasma homocysteine, and serum vitamin B12 and folate concentrations were measured by immunoenzymatic assays; reactive oxygen species, total antioxidant capacity and thiol groups by spectrophotometric methods; and total and free malondialdehyde concentrations by gas chromatography-mass spectrometry with isotopic dilution. Results: Baseline free malondialdehyde concentrations were significantly higher in smokers than in non-smokers and normalised after 30-day supplementation. Baseline results for all the other parameters remained unchanged after supplementation, with no significant differences between smokers and non-smokers. Conclusion: This is the first study showing a significant decrease in free malondialdehyde levels in light smokers after 1-month phytonutrient supplementation.

HFE Gene Mutations and Oxidative Stress Influence Serum Ferritin, Associated with Vascular Damage, in Hemodialysis Patients

Background/Aims: Hyperferritinemia has been associated with cardiovascular mortality in hemodialysis patients. The aim of this study was to evaluate whether serum ferritin was affected by iron and oxidative status and by genetic factors (HFE mutations and the Ala9Val MnSOD polymorphism), and to assess the association between ferritin and cardiovascular damage evaluated by ecocolor-Doppler. Methods: 63 hemodialysis patients were tested for HFE and MnSOD genotype by restriction analysis and oxidative status; vascular damage was assessed by measuring intima-media thickness, and by detecting plaques at carotid and femoral arteries. Results: Ferritin was correlated with transferrin saturation (p = 0.003), decreased iron-specific serum antioxidant activity (p = 0.01), age (p = 0.03), and C282Y and H63D HFE mutations (p = 0.05), but not with the MnSOD polymorphism. Ferritin was associated with advanced vascular damage, as evaluated by the presence of plaques, both at carotid (p = 0.03) and femoral arteries (p = 0.001), the other risk factors being age and low albumin. Low iron-specific antioxidant activity was associated with carotid plaques (p = 0.03). Conclusion: In hemodialysis patients, hyperferritinemia reflects a relative increase in iron availability and a decrease in iron-specific antioxidant activity, is favored by HFE mutations, and represents a risk factor for advanced cardiovascular damage.

Loss of epidermal growth factor regulation by cobalamin in multiple sclerosis.

We investigated whether the physiological regulation of cerebrospinal fluid (CSF) levels of tumor necrosis factor (TNF)-alpha, epidermal growth factor (EGF), and nerve growth factor (NGF) by cobalamin (Cbl) that is observed in rat and human central nervous system (CNS) is retained in the CSF of patients with multiple sclerosis (MS). The study involved 158 MS patients grouped on the basis of the different clinical courses (relapsing-remitting (RR), secondary-progressive (SP), and primary-progressive (PP)), and 76 gender- and age-matched control patients with other non-inflammatory and non-neoplastic neurological diseases. The MS patients were therapy-free at the time of lumbar puncture. CSF Cbl and EGF were blindly measured by means of radioimmunoassays, and CSF TNF-alpha, and NGF by means of highly sensitive enzyme-linked immunosorbent assays. Serum EGF was also measured in 38 of the MS patients and 20 healthy controls. CSF Cbl levels were significantly higher (RR patients 27.9+/-9.7 pg/ml, p<0.0001 vs. C; SP patients 25.4+/-8 pg/ml, p<0.02 vs. C), and CSF TNF-alpha and EGF levels significantly lower in the patients with the RR (TNF-alpha 28.3+/-23.4 x 10(-3) pg/ml, p<0.0001 vs. C; EGF 129.9+/-44.8 pg/ml, p<0.02 vs. C) or SP (TNF-alpha 20.5+/-20.5 x 10(-3) pg/ml, p<0.001 vs. C; EGF 116.5+/-24.8 pg/ml, p<0.05 vs. C) clinical course than in controls (Cbl 21+/-4.6 pg/ml; TNF-alpha 75.6+/-34.7 x 10(-3) pg/ml; EGF 170.2+/-54.8 pg/ml). There were no differences in CSF NGF or serum EGF levels between any of the MS clinical courses and controls. Our results indicate that: (a) the positive Cbl-mediated regulation of myelino- and oligodendrocyte-trophic EGF is lost in the CSF of RR- or SP-MS patients; (b) the decrease in EGF levels in the CSF may be one factor impeding CNS remyelination in MS; and (c) the PP clinical course may have different pathogenetic mechanism(s) also on the basis of the molecules investigated in this study.