Comparison of temporal changes in established cardiovascular biomarkers after acute coronary syndrome between Caucasian and Chinese patients with diabetes mellitus

Abstract

Background: Population means of conventional cardiovascular biomarkers are known to differ between ethnic groups. In this study we performed detailed comparisons in the temporal pattern of these biomarkers between Caucasian and Chinese diabetic patients with acute coronary syndrome (ACS).

Methods: We studied differences in temporal changes of established cardiovascular biomarkers, including high-density lipoprotein (HDL), low-density lipoprotein (LDL), total cholesterol, cardiac Troponin T (TnT), NT-proBNP and C-reactive protein (CRP), in 48 Chinese and 48 clinically matched Caucasian patients with type 2 diabetes mellitus who were admitted for ACS. Blood samples were collected at regular time intervals during 30?days to 1?year after the index ACS.

Results: In the >30?day post ACS period, mean serum levels of LDL (2.16 vs. 1.47?mmol/L; p-value <0.001), total cholesterol (4.08 vs. 3.11?mmol/L; p-value <0.001), TnT (11.0 vs. 7.76?ng/L; p-value 0.010) and CRP (2.0 vs. 0.78?mg/L; p-value <0.001) were systematically higher in Caucasian than in Chinese patients. HDL and NT-proBNP levels were similar.

Conclusions: Our study showed clinically relevant differences in levels of established cardiovascular biomarkers between Caucasian and Chinese post ACS patients. Further cross-ethnic studies are warranted to determine secondary prevention treatment biomarker targets in specific populations.     

No association between the vitamin D pathway gene polymorphisms and bone biomarkers response to calcium and low dose calcitriol supplementation in postmenopausal Chinese women: a one-year prospective study

Abstract

Introduction: The aim of the study was to explore the association between the vitamin D pathway gene variations and the bone biomarkers response to calcium and low dose calcitriol supplementation in postmenopausal Chinese women.

Methods: A total of 110 healthy postmenopausal Chinese women (61.51?±?6.93?years) were enrolled. The participants were supplemented with calcium (600?mg/d) and calcitriol (0.25?μg/d), for 1?year. Four biomarkers, serum levels of beta C-terminal cross-linked telopeptides of type I collagen (β-CTX), amino-terminal propeptide of type I collagen (P1NP), parathyroid hormone (PTH) and 25-hydroxyvitamin D [25(OH)D] were measured at baseline and 12-month follow-up. Multivariate regression models were established to explore the statistical association between the change rate of the four biomarkers and 15?key genes within the vitamin D metabolic pathway.

Results: This exclusion process left 98 participants for analysis. Serum levels of P1NP, β-CTX and PTH were significantly decreased at the 12-month follow-up (all p?<?0.05). Serum 25(OH)D level had no significant change (p?>?0.05). No association was found between the vitamin D pathway gene polymorphisms and bone biomarkers response to calcium and low dose calcitriol supplementation.

Conclusions: Genetic background of postmenopausal Chinese women might not influence supplemental response of the biomarkers to calcium and low dose calcitriol.     

Body iron is a contributor to oxidative damage of DNA

The transition metal iron is catalytically highly active in vitro, and not surprisingly, body iron has been suggested to promote oxidative stress in vivo. In the current analysis we studied the association of serum ferritin concentration and serum soluble transferrin receptor concentration with daily urinary 8-hydroxydeoxyguanosine excretion, a marker of oxidative stress, in 48 mildly dyslipidemic men in East Finland. In multivariate linear regression analyses allowing for age, smoking, body mass index and physical exercise, serum ferritin concentration predicted the excretion rate at B = 0.17 (95% CI 0.08–0.26, P = 0.001), and serum soluble transferrin receptor to ferritin concentration ratio (TfR/ferritin) predicted the excretion rate at B = ? 0.13 (95% CI ? 0.21 to ? 0.05, P = 0.002). Our data suggest that body iron contributes to excess oxidative stress already at non-iron overload concentrations in these subjects.     

Phylogenetic and sequence analyses of insect transferrins suggest that only transferrin 1 has a role in iron homeostasis

Iron is essential to life,but surprisingly little is known about how iron is managed in nonvertebrate animals.In mammals,the well-characterized transferrins bind iron and are involved in iron transport or immunity,whereas other members of the transferrin family do not have a role in iron homeostasis.In insects,the functions of transferrins are still poorly understood.The goals of this project were to identify the transferrin genes in a diverse set of insect species,resolve the evolutionary relationships among these genes,and predict which of the transferrins are likely to have a role in iron homeostasis.Our phylogenetic analysis of transferrins from 16 orders of insects and two orders of noninsect hexapods demonstrated that there are four orthologous groups of insect transferrins.Our analysis suggests that transferrin 2 arose prior to the origin of insects,and transferrins/,i,and 4 arose early in insect evolution.Primary sequence analysis of each of the insect transferrins was used to predict signal peptides,carboxyl-terminal transmembrane regions,GPI-anchors,and iron binding.Based on this analysis,we suggest that transferrins 2,and 4 are unlikely to play a major role in iron homeostasis.In contrast,the transferrin 1 orthologs are predicted to be secreted,soluble,iron-binding proteins.We conclude that transferrin 1 orthologs are the most likely to play an important role in iron homeostasis.Interestingly,it appears that the louse,aphid,and thrips lineages have lost the transferrin 1 gene and,thus,have evolved to manage iron without transferrins.     

The Growth Attainment,Hematological, Iron Status and Inflammatory Profile of Guatemalan Juvenile End-Stage Renal Disease Patients

BackgroundStunting, anemia and inflammation are frequently observed in children with end-stage renal disease (ESRD).ObjectivesTo assess anthropometric, hematological and inflammatory data and to study their potential interrelationship in Guatemalan juveniles undergoing hemodialysis (HD) and peritoneal dialysis (PD).Methods54 juveniles 7–20 years of age were recruited in FUNDANIER, Guatemala City: 27 on HD and 27 PD. Hemoglobin, serum iron, transferrin, serum transferrin receptor (sTfR), serum ferritin, transferrin saturation and iron-binding capacity, white blood cell count (WBC), erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), as well as IL-6, IL-1 and TNF-α, weight and height were determined by standard methods. Hepcidin–25 (Hep-25) was assessed by weak cation exchange time-of-flight mass-spectrometry.Results92% and 55% of HD and PD children, respectively, were stunted and 95% and 85% were anemic. Among iron status biomarkers, serum ferritin was massively increased and significantly higher in the HD group compared to the PD group. Hep-25 was also greatly elevated in both groups. 41% of HD patients showed increments in three or more inflammatory biomarkers, while it was 2 or less in all PD subjects.ConclusionsThe degree of stunting, the prevalence and severity of anemia in Guatemalan juvenile ESRD far exceed the national statistics for this low-income Central American country. Ferritin and Hep-25 concentrations were elevated, with the latter to an extraordinary magnitude. Additional biomarkers of inflammation not directly related to iron status were elevated as well. The role of both disease- and environment-related factors in combination best explains the magnitude of the biomarker abnormalities.     

Circulating miR-1, miR-133a,and miR-206 levels are increased after a half-marathon run

Abstract

Context: Circulating miRNAs are potential biomarkers that can be important molecules driving cell-to-cell communication.

Objective: To investigate circulating muscle-specific miRNAs in recreational athletes.

Materials and methods: Three miRNAs from whole plasma before and after a half-marathon were analyzed by qPCR.

Results: MiR-1, ?133a, and ?206 significantly increased after the race.

Discussion: Increased levels of miRNAs after exercise point to potential biomarkers and to the possibility of being functional players following endurance training.

Conclusion: These miRNAs are potential biomarkers of muscle damage or adaptation to exercise.     

Development of urea biosensor using non-covalent complexes of urease with aldehyde derivative of PEG and analysis on serum samples

Abstract

Non-covalent complexes of urease/polyethylene glycol (PEG)-aldehyde were synthesized using regular molar ratios of urease and PEG-aldehyde at room temperature. The physical properties of the non-covalent complexes were analyzed in order to investigate the impact of coupling ratio, temperature, pH, storage stability, and thermal stability. Urease activity was analyzed by UV–Vis spectrophotometer at 630?nm. The results showed that the strongest thermal resistance was obtained using n_U/n_PEG:1/1 (mg/mL) complex within all molar ratios tested. The enzymatic activity of n_U/n_PEG:1/1 complex doubled the activity of the free enzyme. Therefore, this complex was chosen to be used in the analyses. When coupled with PEG-aldehyde, urease exhibited improved activity between pH 4.0–9.0 and the optimum pH was found to be 7.0. The thermal inactivation results of the complex demonstrated that higher activity remained (40%) when compared with the free enzyme (10%) at 60?°C. The storage stability of the non-covalent complex was 4 weeks which was greater than the storage stability of the free enzyme. A kinetic model was suggested in order to reveal the mechanism of enzymatic conversion. Potentiometric urea biosensor was prepared using two different membranes: carboxylated poly vinyl chloride (PVC) and palmitic acid containing PVC. The potentiometric responses of both sensors were tested against pH and temperature and the best results were obtained at pH 7.0 and 20–30?°C. Also, selectivity of the suggested biosensors toward Na⁺, Li⁺ Ca²⁺, and K⁺ ions was evaluated and the reproducibility responses of the urea biosensors were measured with acceptable results.     

Association between vitamin D receptor (FokI) genetic variant rs2228570 and iron profile in hemodialysis patients

Iron deficiency is a common etiology of anemia that causes suboptimal response to erythropoietin therapy in hemodialysis (HD) patients. This study investigated the association between vitamin D receptor (VDR) genetic variant (FokI) rs2228570 with iron indices (serum iron, transferrin, transferrin saturation, and ferritin). Sixty adequately hemodialyzed patients subdivided into two groups; 31 patients with transferrin saturation (TSAT)?<?20% and 29 with TSAT?>?20% who received I.V sodium ferric gluconate, calcium, and vitamin D. Sixty normal healthy were selected as the control group.. VDR genetic variant (SNP rs2228570) was genotyped in all subjects using PCR/RFLP. HD patients showed a higher frequency of rs2228570 FF genotype (38.3%) than controls (31.7%). The frequency of ff genotype and f allele in patients (8.4 and 35% respectively) were significantly lower than controls (25 and 46.7% respectively). Allele model (f vs. F): OR 0.721, 95% CI 0.521–0.998, P?=?0.049. While (ff vs. FF): OR 0.452, 95% CI 0.223–0.917, P = 0.028. The distribution of Ff?+?ff genotypes in HD cases with TSAT?>?20% was higher than in HD cases with TSAT?<?20%, Dominant model (Ff +ff vs FF): OR 2.753, 95% CI 1.902–3.409, P?=?0.048. f allele showed lower frequency in low TSAT group than high TSAT group (27.4 vs. 43.1%) with significant P value (P?=?0.042) with allele model (f vs. F): OR 2.012, 95% CI 1.923–4.226, P?=?0.042. Fok-1 ff, Ff?+?ff genotypes were significantly associated with TSAT?>?20% with a protective effect against low TSAT in HD patients.

     

Long-term stability of parameters of antioxidant status in human serum

Abstract

The antioxidant status of serum or plasma can be determined using several commercially available assays. Here, four different assays, total antioxidant status (TAS), its second-generation assay (TAS2), biological antioxidant potential (BAP), and enzymatic assay using horseradish peroxidase (EAOC), were applied on human serum samples to test the temperature stability of antioxidants, upon storage of serum for 12 months. The two or three most commonly used temperatures for storage, that is, ? 20, ? 70 (or ? 80), and ? 196°C, were selected. The general conclusion is that all assays were stable at the temperatures tested. In addition, there were almost no statistically significant differences between the samples stored at different temperatures. Only the rank order of the EAOC assay was not very good in samples stored at ? 20°C. Also three components contributing to the total antioxidant capacity, uric acid, creatinine and bilirubin, showed no statistically significant differences between the temperatures. Therefore, storage at ? 20°C is sufficient to maintain a proper assay outcome of most of the total antioxidant assays, although storage at ? 70/80°C is to be preferred for longer storage times.     

Iron deficiency in obese postmenopausal women

Objective: This study evaluates whether the iron deficiency suggested in children and adolescents with overweight is also present with increasing age. Research Methods and Procedures: We examined 50 consecutive postmenopausal nondiabetic white women with a BMI ≥30 kg/m² and 50 non‐obese seemingly healthy women as a control group. In addition to the traditional indices of iron status, we measured the soluble transferrin receptor (sTfR) levels, a sensitive and highly quantitative indicator of early iron deficiency not influenced by the acute phase response. Results: Obese women have higher serum sTfR levels than control subjects [1.38 (range, 0.89 to 2.39) vs. 1.16 mg/dL (range, 0.69 to 2.03 mg/dL); p < 0.001]. However, no difference in ferritin concentration was observed between the groups [70.50 (range, 18 to 219) vs. 69.50 ng/mL (range, 24 to 270 ng/mL); p = not significant]. A positive correlation between BMI and sTfR concentration was detected. On multiple regression analyses, BMI (positively) and ferritin (inversely) were independent predictors accounting for sTfR. Discussion: These results suggest that a moderate degree of iron deficiency is also present among adult women with obesity. The determination of sTfR is useful in the evaluation of iron status in this condition. Further studies with a greater number of patients are required to investigate the relationship between tissue iron concentrations and obesity.     

Kinetics of iron passage through subcellular compartments of rabbit reticulocytes

Summary The kinetics of the separate processes of Fe₂(III)-transferrin binding to the transferrin receptor, transferrin-receptor internalization, iron dissociation from transferrin, iron passage through the membrane, and iron mobilization into the cytoplasm were studied by pulse-chase experiments using rabbit reticulocytes and⁵⁹Fe,¹²⁵I-labeled rabbit transferrin. The binding of⁵⁹Fe-transferrin to transferrin receptors was rapid with an apparent rate constant of 2×10⁵ m ^–1 sec^–1. The rate of internalization of⁵⁹Fe-transferrin was directly measured at 520±100 molecules of Fe₂(III)-transferrin internalized/sec/cell with 250±43 sec needed to internalize the entire complement of reticulocyte transferrin receptors. Subsequent to Fe₂(III)-transferrin internalization the flux of⁵⁹Fe was followed through three compartments: internalized transferrin, membrane, and cytosol.A process preceding iron dissociation from transferrin and a reaction involving membrane-associated iron required 17±2 sec and 34±5 sec, respectively. Apparent rate constants of 0.0075±0.002 sec^–1 and 0.0343±0.0118 sec^–1 were obtained for iron dissociation from transferrin and iron mobilization into the cytosol, respectively. Iron dissociation from transferrin is the rate-limiting step. An apparent rate constant of 0.0112±0.0025 sec^–1 was obtained for processes involving iron transport through the membrane although at least two reactions are likely to be involved. Based on mechanistic considerations, iron transport through the membrane may be attributed to an iron reduction step followed by a translocation step. These data indicate that the uptake of iron in reticulocytes is a sequential process, with steps after the internalization of Fe₂(III)-transferrin that are distinct from the handling of transferrin.     

Transferrin receptor expression and the regulation of placental iron uptake

Placental transferrin receptors, located at the apical side of syncytiotrophoblast, mediate placental iron uptake. Regulation of transferrin receptors on the fetal-maternal exchange area could be a major determinant in the regulation of trans-placental iron transport.Transferrin receptor expression in cultured human term cytotrophoblasts is on a much lower level than in choriocarcinoma cells, with a higher proportion of receptors located on the cell surface. Differentiation of cells, either due to longer culture periods or to 8-bromo-cAMP treatment does not lead to an increase of transferrin receptor expression. In vitro, the level of expression is largely regulated by the cellular density in the culture dishes. Low cellular occupancy of the dish leads to a high level of transferrin receptors. Treatment with iron-sources results in a down regulation of transferrin receptors.Thus, though the level of transferrin receptors in cultured normal trophoblast is at a constant level, unaffected by differentiation, high levels of maternal transferrin-iron availability can lead to a decrease in placental iron uptake. This feed-back mechanism makes placental iron uptake independent of maternal iron stores.Abbreviations hCG human Chorionic Gonadotrophin - TfR Transferrin Receptor     

Histopathological indices and inflammatory response in the digestive gland of the mussel Mytilus galloprovincialis as biomarker of immunotoxicity to silver nanoparticles

Background: Histopathological assessments approaches in bivalves have become an important tool in environmental toxicology. This study seeks to develop a quantitative histopathological index (Ih) and inflammation score as biomarkers in the aim to assess the health status of nanoparticles exposed mussels.

Methods: Digestive gland hematoxylin and eosin (H&;E) stained sections from Mytilus galloprovincialis were assessed after in vivo exposure (for 3, 6 and 12?h) to silver nanoparticles (Ag-NPs?Results: Silver nanoparticles clearly induced histopathological alterations in digestive gland (maximum inflammation 2.75 with AgNP?p?Ih with AgNP?p?Ih were recorded after uptake routes were blockade: AgNP?p?Conclusions: Histopathological assessments showed to be promising tool in nanotoxicity which seems to depend on nanoparticles size, exposure time and interestingly to uptake routes. It was not clear: is it the length of exposure or the size of particles is more impactful.     

Hyperglycaemia,oxidative stress and inflammatory markers

Introduction: The increasing prevalence of hyperglycaemia implicates a state of oxidative stress and inflammation. Traditional and emerging biomarkers associated with increasing hyperglycaemia were assessed to clarify their role they play in hyperglycaemia.

Results: 309 participants attending a rural diabetic screening program were categorised into control and quintile groups based upon glucose levels: 1st quintile - <4.5?mmol/L and 4th, 5th quintile - >6.1?mmol/L. Significant results were obtained for anthropometric data and biochemical markers - glucose, HbA1c and total cholesterol (P?P?P?P?Conclusion: This study provided further evidence that inflammatory and oxidative stress biomarkers may contribute to diagnostic information associated with preclinical increases in BGL. Further we have provided a unique study in the analysis of ratios of inflammatory biomarkers and correlations with increasing BGL.     

COVID-19 compromises iron homeostasis: Transferrin as a target of investigation

ImportanceSince the beginning of the COVID-19 pandemic, numerous metabolic alterations have been observed in individuals with this disease. It is known that SARS-CoV-2 can mimic the action of hepcidin, altering intracellular iron metabolism, but gaps remain in the understanding of possible outcomes in other pathways involved in the iron cycle.ObjectiveTo profile iron, ferritin and hepcidin levels and transferrin receptor gene expression in patients diagnosed with COVID-19 between June 2020 and September 2020.Design, setting and participantsCross-sectional study that evaluated iron metabolism markers in 427 participants, 218 with COVID-19 and 209 without the disease.ExposuresThe primary exposure was positive diagnose to COVID-19 in general population of Santo André and São Bernardo cities. The positive and negative diagnose were determinate through RT-qPCR.Main outcomes and measuresDevido a evidências de alterações do ciclo do ferro em pacientes diagnosticados com COVID-19 e devido a corregulação entre hepcidina e receptor de transferrina, uma análise da expressão gênica deste último, poderia trazer insights sobre o estado de ferro celular. A hipótese foi confirmada, mostrando aumento da expressão de receptor de transferrina concomitante com redução do nível de hepcidina circulante.ResultsSerum iron presented lower values in individuals diagnosed with COVID-19, whereas serum ferritin presented much higher values in infected patients. Elderly subjects had lower serum iron levels and higher ferritin levels, and men with COVID-19 had higher ferritin values than women. Serum hepcidin was lower in the COVID-19 patient group and transferrin receptor gene expression was higher in the infected patient group compared to controls.Conclusions and relevanceCOVID-19 causes changes in several iron cycle pathways, with iron and ferritin levels being markers that reflect the state and evolution of infection, as well as the prognosis of the disease. The increased expression of the transferrin receptor gene suggests increased iron internalization and the mimicry of hepcidin action by SARS-CoV-2, reduces iron export via ferroportin, which would explain the low circulating levels of iron by intracellular trapping.     

Species specificity of iron delivery in hybridomas

Summary Studies with Human x Human (HxH), Human x Mouse (HxM), and Mouse x Mouse (MxM) hybridomas have enabled us to define specific factors that affect hybridoma growth in a species-specific manner. Three transferrins and three lipophilic iron chelates have been tested for their ability to support hybridoma proliferation and antibody production. The results of these studies demonstrate that HxH hybridomas do not respond to bovine transferrin a⁺ concentrations up to 100 μg/ml and are approximately 100-fold less responsive to mouse transferrin than to human transferrin. HxM and MxM hybridomas respond equally to human or mouse transferrin but are 100-fold less sensitive to bovine transferrin. An antibody to the human transferrin receptor inhibited the growth-promoting activity of human or mouse transferrin on HxH hybridomas but was ineffective on HxM hybridomas. This semonstrated the functionality of the human transferrin receptor in HxH hybridomas and that human, mouse, and bovine transferrin were interacting through the mouse transferrin receptor in HxM hybridomas. HxH and HxM hybridomas respond similarly to three different iron chelates exhibiting 80 to 110% of the growth response to human transferrin. MxM hybridomas fail to respond to the iron chelates at similar concentrations, suggesting that the human genome present in the other hybridoma species confers a unique ability for utilizing iron when delivered in this form.     

Influence of transferrin glycans on receptor binding and iron-donation

Human bi-bi-antennary transferrin (Tf) was partially deglycosylated by subsequently incubating with one or more of the following exoglycosidases: neuraminidase, β-galactosidase or N-Acetyl-β-D-glucosaminidase. Aglyco-Tf obtained from serum of a patient suffering from the Carbohydrate Deficient Glycoprotein syndrome was isolated. Receptor binding and the Tf and iron uptake capacities of the fully glycosylated-, partially deglycosylated- and aglyco-Tf were compared using the human hepatoma cell line PLC/PRF/5. No difference in binding capacity between the iso-Tf fractions could be demonstrated, however, the Tf and iron uptake capacity of aglyco-Tf was clearly reduced compared with the other Tf fractions. This revised version was published online in November 2006 with corrections to the Cover Date.     

Association of galectin-3 with changes in left ventricular function in recent-onset dilated cardiomyopathy

Abstract

Background: The course of newly diagnosed dilated cardiomyopathy (DCM) varies from persistent reduction of left ventricular ejection fraction (LVEF) to recovery or even worsening. The aim of the present study was to examine the prognostic value of selected biomarkers with regard to changes in LVEF.

Methods: Main inclusion criterion was LVEF ≤45% with exclusion of coronary artery or valvular heart disease. The primary endpoint was LVEF ≤35% in the follow-up echocardiogram. Galectin-3, N-terminal prohormone of brain natriuretic peptide (NT-proBNP) and C-reactive protein (CRP) were related to the endpoint.

Results: Data from 80 DCM patients (55 male, mean age 53 years) were analyzed. Median LVEF was 25% (IQR 25–30). The endpoint was met for 24 patients (30%). These had higher baseline levels of galectin-3 (median 20.3?ng/mL [IQR 14.3–26.9] vs. 14.7?ng/mL [IQR 10.9–17.7], p?=?0.007) and NT-proBNP (3089?pg/mL [IQR 1731–6694] vs. 1498?pg/mL [IQR 775–3890]; p?=?0.004) in univariate Cox regression analysis. ROC analysis revealed that CRP (median 0.4?mg/dL [IQR 0.2–1.2]) was also related to the endpoint (p?=?0.043).

Conclusion: Higher levels of galectin-3, NT-proBNP, and CRP were associated with LVEF ≤35% in our cohort. An approach utilizing a combination of biomarkers for patient management should be assessed in further studies.     

The synthetic polyphenol tert-butyl-bisphenol inhibits myoglobin-induced dysfunction in cultured kidney epithelial cells

Abstract

Rhabdomyolysis caused by severe burn releases extracellular myoglobin (Mb) that accumulates in the kidney and urine (maximum [Mb] ～ 50 μM) (termed myoglobinuria). Extracellular Mb can be a pro-oxidant. This study cultured Madin-Darby-canine-kidney-Type-II (MDCK II) cells in the presence of Mb and tested whether supplementation with a synthetic tert-butyl-polyphenol (tert-butyl-bisphenol; t-BP) protects these renal cells from dysfunction. In the absence of t-BP, cells exposed to 0–100 μM Mb for 24 h showed a dose-dependent decrease in ATP and the total thiol (TSH) redox status without loss of viability. Gene expression of superoxide dismutases-1/2, haemoxygenase-1 and tumour necrosis factor increased and receptor-mediated endocytosis of transferrin and monolayer permeability decreased significantly. Supplementation with t-BP before Mb-insult maintained ATP and the TSH redox status, diminished antioxidant/pro-inflammatory gene responses, enhanced monolayer permissiveness and restored transferrin uptake. Overall, bolstering the total antioxidant capacity of the kidney may protect against oxidative stress induced by experimental myoglobinuria.     

Long-term stability of oxidative stress biomarkers in human serum

The storage time and storage temperature might affect stability of oxidative stress biomarkers, therefore, they have to be analyzed after long-term storage of serum samples. The stability of three biomarkers reflecting oxidative stress: reactive oxygen metabolites (ROM) for hydroperoxides, total thiol levels (TTL) for the redox status and biological antioxidant potency (BAP) for the antioxidant status, was investigated at several time points during 60 months of storage at ?20 and ?80?°C. Biomarkers ROM and BAP showed a very good stability during storage for 60 months at both temperatures. In addition, the correlation of the data after 60 months of storage compared with the starting data was very good with correlation coefficients >0.9. The TTL assay showed good results in serum samples stored at ?80?°C, but not in samples stored at ?20?°C. Serum samples for analysis of the set of oxidative stress biomarkers ROM, BAP and TTL can be stored up to 60 months at ?80?°C. ROM and BAP can also be stored at ?20?°C during this period. The present results are very important for the biomarker-related epidemiological studies that make use of biobanks with samples stored for many years and for new project planning, including sample storage conditions.