Vaccine development for zoonotic viral diseases caused by positive‑sense single‑stranded RNA viruses belonging to the Coronaviridae and Togaviridae families (Review)

Outbreaks of zoonotic viral diseases pose a severe threat to public health and economies worldwide, with this currently being more prominent than it previously was human history. These emergency zoonotic diseases that originated and transmitted from vertebrates to humans have been estimated to account for approximately one billion cases of illness and have caused millions of deaths worldwide annually. The recent emergence of severe acute respiratory syndrome coronavirus-2 (coronavirus disease 2019) is an excellent example of the unpredictable public health threat causing a pandemic. The present review summarizes the literature data regarding the main vaccine developments in human clinical phase I, II and III trials against the zoonotic positive-sense single-stranded RNA viruses belonging to the Coronavirus and Alphavirus genera, including severe acute respiratory syndrome, Middle east respiratory syndrome, Venezuelan equine encephalitis virus, Semliki Forest virus, Ross River virus, Chikungunya virus and O'nyong-nyong virus. That there are neither vaccines nor effective antiviral drugs available against most of these viruses is undeniable. Therefore, new explosive outbreaks of these zoonotic viruses may surely be expected. The present comprehensive review provides an update on the status of vaccine development in different clinical trials against these viruses, as well as an overview of the present results of these trials.

Effects of boric acid and potassium metaborate on cytokine levels and redox stress parameters in a wound model infected with methicillin‑resistant Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus (MRSA) infections are usually found in hospital settings and, frequently, in patients with open wounds. One of the most critical virulence factors affecting the severity and recurrence of infections is the biofilm; increasing antibiotic resistance due to biofilm formation has led to the search for alternative compounds to antibiotics. The present study aimed to use boric acid and potassium metaborate against MRSA infection in a fibroblast wound model. For this purpose, a two-part experiment was designed: First, MRSA strains were used for the test, and both boric acid and potassium metaborate were prepared in microdilution. In the second step, an MRSA wound model was prepared using a fibroblast culture, and treatments with boric acid and potassium metaborate were applied for 24 h. For the evaluation of the effects of treatment, cell viability assay (MTT assay), analysis of redox stress parameters, including total oxidant status and total antioxidant capacity analyses, lactate dehydrogenase analysis and immunohistochemical staining were performed. In addition, IL-1β and IL-10 gene expression levels were assayed. According to the results, potassium metaborate was more effective and exhibited a lower toxicity to fibroblast cells compared to boric acid; moreover, potassium metaborate decreased the level of prooxidant species and increased the antioxidant status more effectively than boric acid. The IL-1β level in the bacteria group was high; however, boric acid and potassium metaborate significantly decreased the expression levels of inflammatory markers, exhibiting the potential to improve the resolution of the lesion. On the whole, the findings of the present study suggest that boric acid and potassium metaborate may be effective on the tested microorganisms.

Metabolic and Metabolomic Insights Regarding the Omega-3 PUFAs Intake in Type 1 Diabetes Mellitus

Type 1 diabetes mellitus (T1DM) is currently considered an autoimmune disease characterized by the destruction of pancreatic β-cells, insulin deficiency, and dysglycemia. Dietary factors, including omega-3 polyunsaturated fatty acids (ω-3 PUFAs), were reported to influence T1DM. Therefore, a better understanding of the potential role of ω-3 PUFAs in the development and progression of T1DM will help to improve the clinical management of the disease. In this review, we explored the current understanding of molecular mechanisms and signaling pathways induced by ω-3 PUFAs and the beneficial effects of ω-3 PUFAs intake in the prevention and treatment of T1DM, as well as the underlying possible metabolomic (lipidomics) changes.

Apoptosis is induced by sub-acute exposure to 3-MCPD and glycidol on Wistar Albino rat brain cells

3-chloropropane-1,2-diol (3-MCPD) and its toxic metabolite glycidol were classified by the International Agency for Research on Cancer (IARC) as belonging to group 2B and 2A for humans. This study aimed to determine the sub-acute toxicity of these agents. Rats were exposed to 3-MCPD at 0.87 and 10 mg/kg/bw and glycidol (2,4 and 37,5 mg/kg/bw) for 90 days. miR-21 gene expression levels significantly decreased in all group's cerebellar tissues compared with control. Exposure to 10 mg/kg/bw 3-MCPD showed significant increases in PTEN in brain as compared to control group. The Akt gen expressions were significantly decreased in 3-MCPD and glycidol groups when compared to control group brains. Additionally, Caspase 3 and AIF immunopositivity significantly increased in 3-MCPD high dose and glycidol high dose groups in cerebellum granular layers compared to control. The results of the present study conclude that 3-MCPD and glycidol can induce apoptosis in rat brain tissue.

Procaine-The Controversial Geroprotector Candidate: New Insights Regarding Its Molecular and Cellular Effects

Since its discovery in 1905 and its employment in everyday medical practice as a local anesthetic, to its highly controversial endorsement as an "anti-aging" molecule in the sixties and seventies, procaine is part of the history of medicine and gerontoprophylaxis. Procaine can be considered a "veteran" drug due to its long-time use in clinical practice, but is also a molecule which continues to incite interest, revealing new biological and pharmacological effects within novel experimental approaches. Therefore, this review is aimed at exploring and systematizing recent data on the biochemical, cellular, and molecular mechanisms involved in the antioxidant and potential geroprotective effects of procaine, focusing on the following aspects: (1) the research state-of-the-art, through an objective examination of scientific literature within the last 30 years, describing the positive, as well as the negative reports; (2) the experimental data supporting the beneficial effects of procaine in preventing or alleviating age-related pathology; and (3) the multifactorial pathways procaine impacts oxidative stress, inflammation, atherogenesis, cerebral age-related pathology, DNA damage, and methylation. According to reviewed data, procaine displayed antioxidant and cytoprotective actions in experimental models of myocardial ischemia/reperfusion injury, lipoprotein oxidation, endothelial-dependent vasorelaxation, inflammation, sepsis, intoxication, ionizing irradiation, cancer, and neurodegeneration. This analysis painted a complex pharmacological profile of procaine: a molecule that has not yet fully expressed its therapeutic potential in the treatment and prevention of aging-associated diseases. The numerous recent reports found demonstrate the rising interest in researching the multiple actions of procaine regulating key processes involved in cellular senescence. Its beneficial effects on cell/tissue functions and metabolism could designate procaine as a valuable candidate for the well-established Geroprotectors database.

Targeting Bacterial Sortases in Search of Anti-Virulence Therapies with Low Risk of Resistance Development

Increasingly ineffective antibiotics and rapid spread of multi- and pan-resistant bacteria represent a global health threat; hence, the need of developing new antimicrobial medicines. A first step in this direction is identifying new molecular targets, such as virulence factors. Sortase A represents a virulence factor essential for the pathogenesis of Gram-positive pathogens, some of which have a high risk for human health. We present here an exhaustive collection of sortases inhibitors grouped by relevant chemical features: vinyl sulfones, 3-aryl acrylic acids and derivatives, flavonoids, naphtoquinones, anthraquinones, indoles, pyrrolomycins, isoquinoline derivatives, aryl β-aminoethyl ketones, pyrazolethiones, pyridazinones, benzisothiazolinones, 2-phenyl-benzoxazole and 2-phenyl-benzofuran derivatives, thiadiazoles, triazolothiadiazoles, 2-(2-phenylhydrazinylidene)alkanoic acids, and 1,2,4-thiadiazolidine-3,5-dione. This review focuses on highlighting their structure–activity relationships, using the half maximal inhibitory concentration (IC₅₀), when available, as an indicator of each compound effect on a specific sortase. The information herein is useful for acquiring knowledge on diverse natural and synthetic sortases inhibitors scaffolds and for understanding the way their structural variations impact IC₅₀. It will hopefully be the inspiration for designing novel effective and safe sortase inhibitors in order to create new anti-infective compounds and to help overcoming the current worldwide antibiotic shortage.

Discovery of natural naphthoquinones as sortase A inhibitors and potential anti-infective solutions against Staphylococcus aureus

Three natural naphthoquinones were screened to find new anti-virulence agents as inhibitors against sortase A from Staphylococcus aureus (SaSrtA) by quantifying the increase in fluorescence intensity upon substrate cleavage at various concentrations. The 5-hydroxy-1,4-naphthalenedione derivatives, juglone and plumbagin, demonstrated a potent inhibitory effect, with IC₅₀ values of 1.78 μM, respectively, 16.71 μM. The related 2-hydroxy-1,4-naphthalenedione derivative, lawsone, demonstrated the selectivity of the chemical scaffold having no significant effect on SaSrtA. The experimental assay was reinforced by molecular docking experiments, antimicrobial, and toxicological studies. Molecular docking studies and the electrophilic character analysis suggest bonding to the enzyme active cysteine residue by a Michael addition reaction. None of the compounds had a significant effect on the concentration of total thiol proteins in the Daphnia magna toxicological assay after 24 hr exposure. Juglone and plumbagin moderately inhibited biofilm formation with no significant effect on bacterial growth of S. aureus, Enterococcus faecalis, and Staphylococcus epidermidis, indicating a selective anti-virulence profile.

Overview of the effects of chemical mixtures with endocrine disrupting activity in the context of real-life risk simulation: An integrative approach (Review)

Research over the past years has indicated that chronic human exposure to very low doses of various chemical species in mixtures and administered via different routes (percutaneous, orally, etc.) should be the main focus of new biochemical and toxicological studies. Humans have daily contact with various chemicals, such as food additives, pesticides from fruits/vegetables, antibiotics (and other veterinary drugs) from meat, different types of preservatives from cosmetics, to name a few. Simultaneous exposure to this wide array of chemicals does not produce immediate effects, but summative effect/s over time that may be clinically manifested several years thereafter. Classical animal studies designed to test the toxic outcome of a single chemical are not suitable to assess, and then extrapolate to humans, the effects of a whole mixture of chemicals. Testing the aftermath of a combination of chemicals, at low doses, around or below the no observed adverse effect is stressed by many toxicologists. Thus, there is a need to reformulate the design of biochemical and toxicological studies in order to perform real-life risk simulation. This review discuss the potential use of computational methods as a complementary tool for in vitro and in vivo toxicity tests with a high predictive potential that could contribute to reduce animal testing, cost and time, when assessing the effects of chemical combinations. This review focused on the use of these methods to predict the potential endocrine disrupting activity of a mixture of chemicals.

Predictive power of the Triticum root elongation test for the assessment of novel anti‑proliferative therapies

The use of alternative techniques to reduce the number of animals used in anticancer research is an issue of current interest. The aim of this study was to validate the use of a simple and efficient alternative tool for the assessment of the potential of novel anti‑proliferative agents. A set of 20 compounds with various mechanisms were tested in the Triticum aestivum root elongation assay, using aminophylline as negative control. Hierarchical cluster analyses were performed using the furthest neighbor method based on Euclidean distance measure, and the compounds were statistically analyzed in reference to their anti‑proliferative pattern registered in the NCI60 human tumor cell line anticancer drug screen. A correlation between the Triticum test results and the NCI60 anti‑proliferative profile was made for a number of human cells that we defined as the Triticum cell panel. Linear equations were computed that can be used to transform the inhibitory effect measured in any future Triticum assay in order to predict the effect on particular human cells. Of the tested anti‑proliferative agents, methotrexate, colchicine, cantharidin, cisplatin and verapamil produced a growth inhibition over 50%. On the whole, the findings of this study suggest that the Triticum test can be used to detect several types of anti‑proliferative mechanisms, particularly those targeting tubulin, rendering it a useful tool with which to identify novel mitotic spindle inhibitors.

Neuroprotective effects of Scrophularia buergeriana extract against glutamate-induced toxicity in SH-SY5Y cells

The aim of this study was to investigate the antioxidant and anti-apoptotic activities, as well as the underlying mechanisms of action, of Scrophularia buergeriana (S. buergeriana) extract (SBE) in glutamate-induced SH-SY5Y cell death. The roots of S. buergeriana were extracted with 70% ethanol, and standardized SBE was used in this study. To induce cytotoxicity, the SH-SY5Y cells were exposed to glutamate for 3 h, or pre-treated with SBE for 1 h, and subsequently incubated with glutamate for 3 h. The neuro-protective effects were assessed by measuring cell viability and the total glutathione contents using commercial kits. The antioxidant and anti-apoptotic mechanisms of action of SBE were evaluated by western blot analysis. The results confirmed that glutamate-induced toxicity was caused by reactive oxygen species (ROS) production, leading to oxidative stress and DNA damage, thus leading to cell death. However, treatment of the SH-SY5Y cells with SBE significantly increased the viability of the cells exposed to glutamate by upregulating the levels of antioxidant proteins, such as superoxide dismutase (SOD)1, SOD2 and glutathione peroxidase-1 (GPx-1), and directly enhancing the total glutathione contents. Furthermore, SBE attenuated DNA impairment and decreased B-cell lymphoma-2 (Bcl-2)-associated X protein (Bax), cleaved caspase-3 and cleaved poly(adenosine diphosphate (ADP)-ribose) polymerase (PARP) activation. In addition, SBE upregulated Bcl-2 expression via p38 mitogen-activated protein kinases (MAPKs). On the whole, the findings of this study demonstrated that SBE exerts neuroprotective effects against glutamate-induced cell toxicity through its antioxidant and anti-apoptotic activities.

The Akt pathway in oncology therapy and beyond (Review)

Protein kinase B (Akt), similar to many other protein kinases, is at the crossroads of cell death and survival, playing a pivotal role in multiple interconnected cell signaling mechanisms implicated in cell metabolism, growth and division, apoptosis suppression and angiogenesis. Akt protein kinase displays important metabolic effects, among which are glucose uptake in muscle and fat cells or the suppression of neuronal cell death. Disruptions in the Akt-regulated pathways are associated with cancer, diabetes, cardiovascular and neurological diseases. The regulation of the Akt signaling pathway renders Akt a valuable therapeutic target. The discovery process of Akt inhibitors using various strategies has led to the identification of inhibitors with great selectivity, low side-effects and toxicity. The usefulness of Akt emerges beyond cancer therapy and extends to other major diseases, such as diabetes, heart diseases, or neurodegeneration. This review presents key features of Akt structure and functions, and presents the progress of Akt inhibitors in regards to drug development, and their preclinical and clinical activity in regards to therapeutic efficacy and safety for patients.

Insulin-Leptin Axis, Cardiometabolic Risk and Oxidative Stress in Elderly with Metabolic Syndrome

Insulin and leptin have an overlapping anorexigenic action as well as opposite effects on glucose and lipid metabolism. The study focuses on the biochemical and clinical relevance of new indices of insulin-leptin axis utilized in the study of the relationships between leptinemia, insulin sensitivity and oxidative stress, in elderly subjects with metabolic syndrome. We conducted clinical studies on elderly people with metabolic syndrome versus control subjects by creating new insulin-adipogenic indices, namely Insulin-to-Leptin Ratio (ILR) and Insulin-Adipogenic Resistance index (IAR-index). Inflammation and oxidative stress biomarkers evaluated were the high-sensitivity C-reactive protein (hsCRP), the advanced oxidation protein products (AOPP), and the serum antioxidant capacity measured as ferric reducing antioxidant potential (FRAP). The metabolic syndrome group showed significantly (p<0.01) lower levels of ILR and not significant (p=0.09) higher values of IAR-index, as compared to the control group. In metabolic syndrome subjects, the IAR-index was significantly positively correlated with uric acid (r=0.313, p<0.05), FRAP (r=0.347, p<0.05) and AOPP (r=0.677, p<0.01), and negatively correlated with HDL-cholesterol (r=- 0.340, p<0.05) as well as with the ratio FRAP/uric acid (r=- 0.315, p<0.05). ILR and IAR-index reflected the biological state of adipose and pancreatic β-cells and seem to depict the adipo-insular axis status related to metabolic and oxidative stress better than individual markers. Therefore, ILR and IAR-index could represent integrated high-potential biomarkers for disease and patient stratification.

Molecular Docking and Screening Studies of New Natural Sortase A Inhibitors

To date, multi-drug resistant bacteria represent an increasing health threat, with a high impact on mortality, morbidity, and health costs on a global scale. The ability of bacteria to rapidly and permanently acquire new virulence factors and drug-resistance elements requires the development of new antimicrobial agents and selection of new proper targets, such as sortase A. This specific bacterial target plays an important role in the virulence of many Gram-positive pathogens, and its inhibition should produce a mild evolutionary pressure which will not favor the development of resistance. A primary screening using a fluorescence resonance energy transfer assay was used to experimentally evaluate the inhibitory activity of several compounds on sortase A. Using molecular docking and structure-activity relationship analyses, several lead inhibitors were identified, which were further tested for antimicrobial activity using the well diffusion test and minimum inhibitory concentration. The toxicity was assessed using the Daphnia magna test and used as a future screening filter. Three natural compounds were identified in this study as promising candidates for further development into therapeutically useful anti-infective agents that could be used to treat infections caused by multi-drug resistant bacterial pathogens which include sortase A in their enzymatic set.

Adiponectin: possible link between metabolic stress and oxidative stress in the elderly

OBJECTIVE

The aim of this study was to evaluate the relationships between the serum levels of adiponectin and systemic oxidative stress exerted on lipids, proteins, as well as endothelial function and cardiovascular diseases (CVD) risk markers, in elderly subjects with metabolic syndrome (MS).

METHODS

The serum advanced glycation and oxidation protein products, low-density lipoprotein susceptibility to oxidation (oxLDL), nitric oxide metabolic pathway products (NOx), serum lipid peroxidation, as well as total antioxidant/oxidative capacity (TAC/TOC), were analyzed in elderly subjects with MS (n = 44), compared to aged-matched control (n = 39).

RESULTS

We pointed out significantly lower levels of adiponectin in elderly MS subjects concomitantly with significantly higher levels of oxidative stress and CVD risk markers. Significant positive correlations were found between serum adiponectin levels and HDL-cholesterol (p < 0.05) and the total cholesterol/LDL-cholesterol ratio (p < 0.01). Additionally, adiponectin levels were significantly inversely associated with insulin resistance index (HOMA-IR, r = -0.348; p < 0.05) and serum lipid peroxidation (r = -0.337; p < 0.05), and significantly positively with the antioxidant capacity (TAC, r = 0.339; p < 0.05). Conversely, adiponectin levels were significantly negatively (r = -0.310; p < 0.05) associated with serum uric acid concentration.

CONCLUSIONS

The major protective role of adiponectin versus stress related to an impaired glucose and lipid metabolism suggests that adiponectin plays a critical role in adiposity-related metabolic stress and redox homeostasis.

Akt inhibitors in cancer treatment: The long journey from drug discovery to clinical use (Review)

Targeted cancer therapies are used to inhibit the growth, progression, and metastasis of the tumor by interfering with specific molecular targets and are currently the focus of anticancer drug development. Protein kinase B, also known as Akt, plays a central role in many types of cancer and has been validated as a therapeutic target nearly two decades ago. This review summarizes the intracellular functions of Akt as a pivotal point of converging signaling pathways involved in cell growth, proliferation, apoptotis and neo‑angiogenesis, and focuses on the drug design strategies to develop potent anticancer agents targeting Akt. The discovery process of Akt inhibitors has evolved from adenosine triphosphate (ATP)‑competitive agents to alternative approaches employing allosteric sites in order to overcome the high degree of structural similarity between Akt isoforms in the catalytic domain, and considerable structural analogy to the AGC kinase family. This process has led to the discovery of inhibitors with greater specificity, reduced side-effects and lower toxicity. A second generation of Akt has inhibitors emerged by incorporating a chemically reactive Michael acceptor template to target the nucleophile cysteines in the catalytic activation loop. The review outlines the development of several promising drug candidates emphasizing the importance of each chemical scaffold. We explore the pipeline of Akt inhibitors and their preclinical and clinical examination status, presenting the potential clinical application of these agents as a monotherapy or in combination with ionizing radiation, other targeted therapies, or chemotherapy.

Correlation between erythropoietin serum levels and erythrocyte susceptibility to lipid peroxidation in elderly with type 2 diabetes

Erythropoietin (EPO), a key hormone involved in red blood cell formation has been recently acknowledged for its pleiotropic actions and protective role in ageing and various pathological conditions concurrent with oxidative stress, vascular diseases and metabolic abnormalities such as diabetes mellitus. The aim of the study was to evaluate the relationship between circulating erythropoietin levels and oxidative stress biomarkers, in elderly with type 2 diabetes (T2DM). The study was carried out in 67 subjects with T2DM (69 ± 5 years; n = 37) without anemia, and aged-matched controls (70 ± 6 years; n = 30). EPO serum levels, erythrocyte susceptibility to lipid peroxidation (ESP) and total antioxidant capacity (TAC) were evaluated. Lower EPO levels (p < 0.01) and higher ESP values (p < 0.001) were found in T2DM group, compared to healthy subjects. EPO levels showed significant negative associations with ESP, both in T2DM subjects (r = -0.565; p < 0.001) and in all study population (r = -0,600; p < 0,001; n = 67). In conclusion, we provide new data regarding the cytoprotective effect of EPO exerted at systemic level on erythrocyte membrane, in the particular state of impaired glucose metabolism associated with oxidative stress, in the elderly.

In vitro effects of prolonged exposure to quercetin and epigallocatechin gallate of the peripheral blood mononuclear cell membrane

The study aimed to assess biophysical changes that take place in the peripheral blood mononuclear cell (PBMC) membranes when exposed in vitro to 10 μM quercetin or epigallocatechin gallate (EGCG) for 24 and 48 h. PBMCs isolated from hypercholesterolemia patients were compared to those from normocholesterolemia subjects. The membrane fluidity and transmembrane potential were evaluated and the results were correlated with biochemical parameters relevant to oxidative stress, assessed in the patients' plasma. The baseline value of PBMC membrane anisotropy for the hypercholesterolemia patients was lower than that of the control group. These results correlated with the plasma levels of advanced glycation end products, which were significantly higher in the hypercholesterolemia group, and the total plasma antioxidant status, which was significantly higher in normocholesterolemia subjects. In the case of normocholesterolemia cells in vitro, polyphenols induced a decrease in membrane anisotropy (7.25-11.88% at 24 h, 1.82-2.26% at 48 h) and a hyperpolarizing effect (8.30-8.90% at 24 h and 4.58-13.00% at 48 h). The same effect was induced in hypercholesterolemia cells, but only after 48 h exposure to the polyphenols: the decrease in membrane anisotropy was 5.70% for quercetin and 2.33% for EGCG. After 48 h of in vitro incubation with the polyphenols, PBMCs isolated from hypercholesterolemia patients exhibited the effects that had been registered in cells from normocholesterolemia subjects after 24 h exposure. These results outlined the beneficial action of the studied polyphenols, quercetin and EGCG, as dietary supplements in normocholesterolemia and hypercholesterolemia patients.

Analysis of circulating microRNAs that are specifically increased in hyperlipidemic and/or hyperglycemic sera

MicroRNAs (miRNAs) are small non-coding RNA sequences that regulate gene expression post-transcriptionally by translation inhibition or mRNA degradation. The aim of the present study was to analyze serum miRNAs modulated by hyperlipidemia and/or hyperglycemia and to correlate them with biochemical parameters within lipid metabolism. Five selected circulating miRNAs (miR-125a-5p, miR-146a, miR-10a, miR-21 and miR-33a) were individually analyzed by TaqMan miRNA assays along with lipid and inflammation parameters in sera from 20 hyperlipidemic (HL) and/or hyperglycemic (HG) patients, and compared with data from five normolipidemic/normoglycemic subjects. Results showed: (1) the levels of all the analyzed circulating miRNA were increased in HL sera and correlated positively with sera's lipid and inflammatory parameters; (2) circulating miR-125a-5p and miR-146a levels were increased in HG and/or HL sera; (3) all selected miRNAs were detected in α-lipoprotein fraction from sera, and miR-33a was also present in β-lipoprotein fraction; (4) miRNA concentrations were increased in the α-lipoprotein fraction from HL sera. These data show a statistically significant correlation of the analyzed miRNA with increased lipids, specifically with α- and β-lipoproteins, and CRP and IL-1β levels in HL and/or HG sera, suggesting a contribution of these miRNAs to the atherosclerotic process.

Alzheimer's disease treated patients showed different patterns for oxidative stress and inflammation markers

Alzheimer's disease (AD) is the most common type of dementia accounting for 60-80% of the reported cases. The aim of this study was to evaluate levels of certain parameters of oxidative stress and markers of endothelial dysfunction in the blood of 21 AD patients under standard treatment compared with 10 controls, in an attempt to elucidate the contribution of AD to the total oxidative stress status of the patients. Results indicate that IL-6, TNF-α, ADMA and homocysteine levels were significantly elevated in AD patients. Protein carbonyls levels were higher in AD group, while glutathione reductase and total antioxidant capacity were lower, depicting decreased defense ability against reactive oxygen species. Besides, a higher level of advanced glycation end-products was observed in AD patients. Depending on the treatment received, a distinct inflammatory and oxidative stress profile was observed: in Rivastigmine-treated group, IL6 levels were 47% lower than the average value of the remaining AD patients; homocysteine and glutathione reductase were statistically unchanged in the Rivastigmine and Donepezil-Memantine, respectively Donepezil group. Although the study is based on a limited population, the results could constitute the basis for further studies regarding the effect of medication and diet on AD patients.

Advanced oxidative and glycoxidative protein damage markers in the elderly with type 2 diabetes

We aimed to explore the association of advanced oxidation and advanced glycation of proteins, and their interrelations with endothelial nitric oxide synthesis, oxidative stress, metabolic profile as well as other atherosclerotic risk markers in prediabetic and diabetic elderly subjects. Advanced glycation end products (AGEs), advanced oxidation protein products (AOPPs), low-density lipoprotein susceptibility to oxidation (oxLDL) and nitric oxide metabolic pathway products (NOx) were assessed in subjects with impaired fasting glucose (prediabetes, IFG; n=90), and type 2 diabetes mellitus (T2DM, n=95) versus control subjects (n=88). Higher levels of AOPPs, AGEs, oxLDL, NOx, atherosclerosis risk markers, and insulin resistance were pointed out in IFG and T2DM groups compared with control. Strong positive associations (p<0.01) of AGEs with fasting glucose and HbA1c were found in both hyperglycemic groups, whereas AOPPs were significantly correlated (p<0.01) only in T2DM. In T2DM, AGEs and AOPPs significantly (p<0.01) correlated with insulin resistance index HOMA-IR, oxLDL and small LDL particle size (TG/HDL-C), and positively with NOx. Direct associations of AGEs and AOPPs with TC/HDL-C and oxLDL/HDL-C, and AGEs-AOPPs interrelations (p<0.01) were identified in IFG and T2DM groups. AGEs and AOPPs in combination with oxLDL and NOx could be important biomarkers for evaluating the association between diabetes and atherosclerotic disorders in aging diabetic patients.

BIOLOGICAL SIGNIFICANCE

In the present study we have made an attempt to approach the biological and clinical significance of the oxidative and glycoxidative protein damage, in subjects with prediabetes and type-2 diabetes mellitus. AGEs and AOPPs in combination with oxLDL and NOx appear to be important biomarkers for evaluating the association between diabetes and atherosclerotic disorders in aging diabetic patients. More importantly, this cluster of biomarkers that links the short term, "real time" metabolic impairment parameters (NOx, serum glucose, HOMA-IR, serum lipid profile) and the "metabolic memory" markers resulting from the long-term hyperglycemia and hyperlipidemia-induced oxidative stress (HbA1c, AGEs, AOPPs and oxLDL), could be valuable in predicting not only vascular complications in T2DM, but also the onset of diabetes, hence enabling therapeutic interventions from the early stages of diabetes. This article is part of a Special Issue entitled: Posttranslational Protein modifications in biology and Medicine.

Vitamin D status and oxidative stress markers in the elderly with impaired fasting glucose and type 2 diabetes mellitus

BACKGROUND AND AIMS

Vitamin D deficiency has been identified in the elderly as a potential risk factor for cardiovascular disease development, possibly through its association with other risk factors, such as type 2 diabetes mellitus (T2DM), hypercholesterolemia and hypertension. The aim of this cross-sectional study was to evaluate the vitamin D status in elderly subjects with impaired fasting glucose (IFG) or T2DM, and to examine its relationships to systemic oxidative stress and biochemical markers of endothelial dysfunction.

METHODS

Serum 25-hydroxyvitamin D [25(OH)D], fasting glucose, insulin, lipid profile, advanced glycation end products (AGEs), advanced oxidation protein products (AOPPs), low-density lipoprotein susceptibility to oxidation (oxLDL) and nitric oxide metabolic pathway products (NOx) were analyzed in elderly subjects with IFG (n=30) and T2DM (n=35) compared with aged-matched controls (n=25).

RESULTS

25(OH)D levels in the IFG and T2DM groups were significantly lower than in controls (31.9±1.9 and 28.5±1.9 vs 39.4±2.4 ng/mL, p<0.001), and associated with significantly (p<0.001) higher levels of the oxidative stress parameters AGEs, AOPPs, oxLDL and NOx. Hypovitaminosis D [25(OH)D)<30 ng/ml] markedly enhanced the oxidative stress and cardiovascular risk in hyperglycemic subjects compared with sufficient vitamin D [25(OH)D)≥30 ng/mL] status subjects. In subjects with IFG and T2DM (n=65), the vitamin D status was significantly inversely correlated both with oxLDL (r=-0.413, p=0.001) and AOPPs (r=-0.475, p<0.001), and strongly positively associated with highdensity lipoprotein cholesterol (r=0.609, p<0.001).

CONCLUSIONS

In the elderly with impaired glucose metabolism the vitamin D status is inversely associated with levels of circulating markers of oxidative stress and endothelial dysfunction, especially in subjects with hypovitaminosis D.

Quercetin and epigallocatechin gallate effects on the cell membranes biophysical properties correlate with their antioxidant potential

Quercetin and epigallocatechin gallate are two of the most abundant polyphenols in dietary plants, including apples, onions, red wine and green tea. The bioactivity of polyphenols is linked to their ability to interact with cell membranes without being internalized. The aim of the present study was to assess the short-time effect of these polyphenols on membrane anisotropy and transmembrane potential of U937 monocytes and Jurkat T lymphoblasts. Results showed that quercetin and epigallocatechin gallate induced, after 20 minutes cell exposure, a dose-dependent increase of membrane anisotropy and polarization. Anisotropy increase was correlated with the reduction of lipid peroxidation. Our results could indicate that the antioxidant capacity of the tested polyphenols is due to their stabilizing effect on the cell membranes, thus contributing to cell protection in various pathologies and as adjuvant therapy in highly toxic treatment regimens.

Quercetin and epigallocatechin gallate induce in vitro a dose-dependent stiffening and hyperpolarizing effect on the cell membrane of human mononuclear blood cells

The bioactivity of polyphenols is closely linked to their ability to interact with biological membranes. The study evaluates the in vitro effect of quercetin and epigallocatechin on the membrane anisotropy and transmembrane potential of peripheral blood mononuclear cells (PBMCs) isolated from 26 type 2 diabetes mellitus patients compared to 25 age matched controls. The in vitro assays were analyzed in correlation with the biochemical and inflammatory profile of the subjects and with insulin resistance parameters (HOMA-IR, plasma resistin) as well. For type 2 diabetes patients, the increase of HOMA-IR and resistin concentration was associated with a significant decrease of the PBMCs membrane anisotropy. The two tested polyphenols induced a dose-dependent hyperpolarizing effect and stiffening of the cell membranes for all tested subjects. Physiological levels of quercetin and epigallocatechin gallate had the tendency to normalize the PBMCs membrane anisotropy of the cells isolated from diabetes patients, bringing it to the level of cells isolated from normoglycemic ones. Epigallocatechin gallate induced higher effects compared to quercetin on the membranes isolated from subjects with higher cardiovascular risk. The decrease of membrane fluidity and the hyperpolarizing effect could explain the cardiovascular protective action of the tested compounds.

An inter-laboratory validation of methods of lipid peroxidation measurement in UVA-treated human plasma samples

Lipid peroxidation products like malondialdehyde, 4-hydroxynonenal and F(2)-isoprostanes are widely used as markers of oxidative stress in vitro and in vivo. This study reports the results of a multi-laboratory validation study by COST Action B35 to assess inter-laboratory and intra-laboratory variation in the measurement of lipid peroxidation. Human plasma samples were exposed to UVA irradiation at different doses (0, 15 J, 20 J), encoded and shipped to 15 laboratories, where analyses of malondialdehyde, 4-hydroxynonenal and isoprostanes were conducted. The results demonstrate a low within-day-variation and a good correlation of results observed on two different days. However, high coefficients of variation were observed between the laboratories. Malondialdehyde determined by HPLC was found to be the most sensitive and reproducible lipid peroxidation product in plasma upon UVA treatment. It is concluded that measurement of malondialdehyde by HPLC has good analytical validity for inter-laboratory studies on lipid peroxidation in human EDTA-plasma samples, although it is acknowledged that this may not translate to biological validity.