Biochemistry and pathology of radical-mediated protein oxidation

Ethanol-induced cardiomyocyte toxicity implicit autophagy and NFkB transcription factor

Chronic ethanol (EtOH) consumption causes early detrimental consequences in many tissues including the myocardium, though the molecular mechanisms leading to the alcoholic cardiomyopathy (ACM) still remain to be elucidated. Here, we studied several biomolecular changes occurring in cardiomyoblasts after their exposure to sublethal concentrations of EtOH and the potential synergistic effect with methylmercury (MM) or doxorubicin (DOXO), which are known to produce direct myocardial dysfunction. In addition, the possible role of autophagic responses and Nuclear Factor kappa-B (NFkB) modulation in early post-alcoholic myocardial damage has been investigated. H9c2 rat cardiomyoblasts were incubated for fifteen days with a sub-lethal concentrations of EtOH (1-1000 μM). In particular, treatment of H9c2 cells with EtOH produced an increase of reactive oxygen species (ROS) and the activation of autophagy. Furthermore, chronic exposure to EtOH, was accompanied by a translocation of NFkB into the nucleus dose-dependently. Finally, co-incubation of EtOH (1-1000 μM) with sublethal concentrations of MM or DOXO showed a prominent apoptotic death of cardiomyoblasts accompanied by ROS overproduction, autophagy activation and by an increased nuclear translocation of NFkB as compared to untreated cells. Thus, EtOH produces early changes in cardiomyoblasts characterized by oxidative stress, reactive autophagy and NFkB modulation at concentrations unable to produce direct cell death. Combination of EtOH with cardiotoxic pollutants or drugs makes the cardiomyocyte vulnerable to exogenous insults leading to apoptosis. These data contribute to better identify molecular mechanisms underlying early stages of alcoholic cardiomyopathy and suggest novel strategies to counteract integrated risk of cardiotoxicity in chronic alcohol consumption.

Tuning Structures and Properties for Developing Novel Chemical Tools toward Distinct Pathogenic Elements in Alzheimer's Disease

Multiple pathogenic factors [e.g., amyloid-β (Aβ), metal ions, metal-bound Aβ (metal-Aβ), reactive oxygen species (ROS)] are found in the brain of patients with Alzheimer's disease (AD). In order to elucidate the roles of pathological elements in AD, chemical tools able to regulate their activities would be valuable. Due to the complicated link among multiple pathological factors, however, it has been challenging to invent such chemical tools. Herein, we report novel small molecules as chemical tools toward modulation of single or multiple target(s), designed via a rational structure-property-directed strategy. The chemical properties (e.g., oxidation potentials) of our molecules and their coverage of reactivities toward the pathological targets were successfully differentiated through a minor structural variation [i.e., replacement of one nitrogen (N) or sulfur (S) donor atom in the framework]. Among our compounds (1-3), 1 with the lowest oxidation potential is able to noticeably modify the aggregation of both metal-free Aβ and metal-Aβ, as well as scavenge free radicals. Compound 2 with the moderate oxidation potential significantly alters the aggregation of Cu(II)-Aβ₄₂. The hardly oxidizable compound, 3, relative to 1 and 2, indicates no noticeable interactions with all pathogenic factors, including metal-free Aβ, metal-Aβ, and free radicals. Overall, our studies demonstrate that the design of small molecules as chemical tools able to control distinct pathological components could be achieved via fine-tuning of structures and properties.

Structural and immunological characterization of hydroxyl radical modified human IgG: Clinical correlation in rheumatoid arthritis

Structural alterations in proteins under oxidative stress have been widely implicated in the immuno-pathology of various disorders. This study has evaluated the extent of damage in the conformational characteristics of IgG by hydroxyl radical (OH) and studied its implications in the immuno-pathology of rheumatoid arthritis (RA). Using various biophysical and biochemical techniques, changes in aromatic microenvironment of the IgG and the protein aggregation became evident after treatment with OH. The SDS-PAGE study confirmed the protein aggregation while far ultraviolet circular dichroism spectroscopy (Far-UV CD) and fourier transform infrared spectroscopy (FTIR) inferred towards the alterations in secondary structure of IgG under OH stress. Dynamic light scattering showed that the modification increased the hydrodynamic radius and polydispersity of IgG. The free arginine and lysine content reduced upon modification. OH induced aggregation was confirmed by enhanced thioflavin-T (ThT) fluorescence and red shift in the congo red (CR) absorbance. The study on experimental animals reiterates the earlier findings of enhanced immunogenicity of OH treated IgG (OH-IgG) compared to that of native IgG. OH-IgG strongly interacted with the antibodies derived from the serum of 80 rheumatoid arthritis (RA) patients. The overwhelming and strong tendency of OH-IgG to bind the antibodies derived from the serum of RA patients points towards the modification of IgG under patho-physiological conditions in RA that generate neo-epitopes and eventually cause the generation of auto antibodies that circulate in the patient sera. Further studies on this aspect may possibly lead to the development of a biomarker for RA.

Intra-Operative Inspired Fraction of Oxygen and the Risk of Surgical Site Infections in Patients with Type 1 Surgical Incisions

BACKGROUND

Whether the fraction of inspired oxygen (F_IO₂) influences the risk of surgical site infection (SSI) is controversial. The World Health Organization and the World Federation of Societies of Anesthesiologists offer conflicting recommendations. In this study, we evaluate simultaneously three different definitions of F_IO₂ exposure and the risk of SSI in a large surgical population.

PATIENTS AND METHODS

Patients with clean (type 1) surgical incisions who developed superficial and deep organ/space SSI within 30 days after surgery from January 2003 through December 2012 in five surgical specialties were matched to specialty-specific controls. Fraction of inspired oxygen exposure was defined as (1) nadir F_IO₂, (2) percentage of operative time with F_IO₂ greater than 50%, and (3) cumulative hyperoxia exposure, calculated as the area under the curve (AUC) of F_IO₂ by time for the duration in which F_IO₂ greater than 50%. Stratified univariable and multivariable logistic regression models tested associations between F_IO₂ and SSI.

RESULTS

One thousand two hundred fifty cases of SSI were matched to 3,248 controls. Increased oxygen exposure, by any of the three measures, was not associated with the outcome of any SSI in a multivariable logistic regression model. Elevated body mass index (BMI; 35+ vs. <25, odds ratio [OR] 1.78, 95% confidence interval [CI] 1.43-2.24), surgical duration (250+ min vs. <100 min, OR 1.93, 95% CI 1.48-2.52), diabetes mellitus (OR 1.37, 95% CI 1.13-1.65), peripheral vascular disease (OR 1.52, 95% CI 1.10-2.10), and liver cirrhosis (OR 2.48, 95% CI 1.53-4.02) were statistically significantly associated with greater odds of any SSI. Surgical sub-group analyses found higher intra-operative oxygen exposure was associated with higher odds of SSI in the neurosurgical and spine populations.

CONCLUSION

Increased intra-operative inspired fraction of oxygen was not associated with a reduction in SSI. These findings do not support the practice of increasing F_IO₂ for the purpose of SSI reduction in patients with clean surgical incisions.

Cytotoxicity, oxidative stress, and apoptosis in K562 leukemia cells induced by an active compound from pyrano-pyridine derivatives

Recent studies have reported the potential of pyrano-pyridine compounds in inhibiting cell growth and apoptosis induction in cancer cells. Here, we investigated the effect of new pyrano-pyridine derivatives on proliferation, oxidative damages, and apoptosis in K562 leukemia cells. Among different tested compounds, we found 8-(4-chlorobenzylidene)-2-amino-4-(4-chlorophenyl)-5, 6, 7, 8-tetrahydro-6-phenethyl-4H-pyrano-[3,2-c]pyridine-3-carbonitrile (4-CP.P) as the most effective compound with IC50 value of 20 μM. Gel electrophoresis, fluorescence microscopy, and flow cytometry analyses indicated the apoptosis induction ability of 4-CP.P in K562 cells. Further analyses revealed that 4-CP.P induces significant increase in cellular reactive oxygen species production, lipid peroxidation, protein oxidation, and total thiol depletion. Interestingly, while 4-CP.P significantly increased the activity of superoxide dismutase, it reduced the catalase activity in a time-dependent manner. These data propose that 4-CP.P treatment causes free radicals accumulation that ultimately leads to oxidative stress condition and apoptosis induction. Therefore, we report the 4-CP.P as a novel, potent compound as a chemotherapeutic agent in cancer treatment.

Photodynamic micelles for amyloid β degradation and aggregation inhibition

Polymeric micelles loaded with chlorin e6 and Tanshinone I (TAS) were prepared and employed for photodegrading amyloid β (Aβ) aggregates and inhibiting Aβ fibrillation.

Role of vascular reactive oxygen species in regulating cytochrome P450-4A enzyme expression in Dahl salt-sensitive rats

OBJECTIVE

The potential contribution of CYP4A enzymes to endothelial dysfunction in Dahl salt-sensitive rats was determined by comparison to SS-5^BN consomic rats having chromosome 5 carrying CYP4A alleles from the BN rat introgressed into the SS genetic background.

METHODS

The following experiments were performed in cerebral arteries from HS-fed SS and SS-5^BN rats ± the SOD inhibitor DETC and/or the superoxide scavenger Tempol: (i) endothelial function was determined via video microscopy ± acute addition of the CYP4A inhibitor DDMS or Tempol; (ii) vascular oxidative stress was assessed with DHE fluorescence ± acute addition of DDMS, l-NAME, or PEG-SOD; and (iii) CYP4A protein levels were compared by western blotting.

RESULTS

In DETC-treated SS-5^BN and HS-fed SS rats, (i) DDMS or Tempol ameliorated vascular dysfunction, (ii) DDMS reduced vascular oxidative stress to control levels, (iii) chronic Tempol treatment reduced vascular CYP4A protein expression, and (iv) combined treatment with Tempol and l-NAME prevented the reduction in CYP4A protein expression in MCA of HS-fed SS rats.

CONCLUSION

The CYP4A pathway plays a role in vascular dysfunction in SS rats and there appears to be a direct role of reduced NO availability due to salt-induced oxidant stress in upregulating CYP4A enzyme expression.

A lysosome targetable versatile fluorescent probe for imaging viscosity and peroxynitrite with different fluorescence signals in living cells

The lysosome, which acts as the cellular recycling centre, is filled with numerous hydrolases that can degrade most cellular macromolecules. The abnormalities of the lysosome are closely associated with diseases, such as Heřmanský-Pudlák syndrome, Griscelli syndrome and Chédiak-Higashi syndrome. Studies have shown that abnormal viscosity and the accumulation of reactive oxygen species (ROS) in the lysosome will disorder the normal function of the lysosome. In this research, a versatile fluorescent probe Lyso-NA has been developed for the multi-channel imaging of lysosomal viscosity and peroxynitrite (ONOO^-). When excited at 550 nm, the Lyso-NA exhibited about a 50-fold increase in fluorescence at 610 nm and also with the increasing viscosity from 1.0 cP to 1410 cP, and about a 3.5-fold increase in fluorescence at 510 nm (excitation at 440 nm) together with the increasing ONOO^-. These satisfactory response properties make it possible to use Lyso-NA to monitor changes in both viscosity and ONOO^- inside the lysosome. To achieve its practical application, it was further demonstrated that Lyso-NA exhibits low cytotoxicity, and good cell permeability, and could be used to monitor lysosomal viscosity and ONOO^- in living cells.

Role of resveratrol in regulation of cellular defense systems against oxidative stress

Resveratrol, a natural polyphenolic compound, is found in various kinds of fruits, plants, and their commercial products such as red wine. It has been demonstrated to exhibit a variety of health-promoting effects including prevention and/or treatment of cardiovascular diseases, inflammation, diabetes, neurodegeneration, aging, and cancer. Cellular defensive properties of resveratrol can be explained through its ability of either directly neutralizing reactive oxygen species/reactive nitrogen species (ROS/RNS) or indirectly upregulating the expression of cellular defensive genes. As a direct antioxidant agent, resveratrol scavenges diverse ROS/RNS as well as secondary organic radicals with mechanisms of hydrogen atom transfer and sequential proton loss electron transfer, thereby protecting cellular biomolecules from oxidative damage. Resveratrol also enhances the expression of various antioxidant defensive enzymes such as heme oxygenase 1, catalase, glutathione peroxidase, and superoxide dismutase as well as the induction of glutathione level responsible for maintaining the cellular redox balance. Such defenses could be achieved by regulating various signaling pathways including sirtuin 1, nuclear factor-erythroid 2-related factor 2 and nuclear factor κB. This review provides current understanding and information on the role of resveratrol in cellular defense system against oxidative stress. © 2017 BioFactors, 44(1):36-49, 2018.

Molecular Cloning and Functional Characterization of the Dehydrin (IpDHN) Gene From Ipomoea pes-caprae

Dehydrin (DHN) genes can be rapidly induced to offset water deficit stresses in plants. Here, we reported on a dehydrin gene (IpDHN) related to salt tolerance isolated from Ipomoea pes-caprae L. (Convolvulaceae). The IpDHN protein shares a relatively high homology with Arabidopsis dehydrin ERD14 (At1g76180). IpDHN was shown to have a cytoplasmic localization pattern. Quantitative RT-PCR analyses indicated that IpDHN was differentially expressed in most organs of I. pes-caprae plants, and its expression level increased after salt, osmotic stress, oxidative stress, cold stress and ABA treatments. Analysis of the 974-bp promoter of IpDHN identified distinct cis-acting regulatory elements, including an MYB binding site (MBS), ABRE (ABA responding)-elements, Skn-1 motif, and TC-rich repeats. The induced expression of IpDHN in Escherichia coli indicated that IpDHN might be involved in salt, drought, osmotic, and oxidative stresses. We also generated transgenic Arabidopsis lines that over-expressed IpDHN. The transgenic Arabidopsis plants showed a significant enhancement in tolerance to salt/drought stresses, as well as less accumulation of hydrogen peroxide (H₂O₂) and the superoxide radical (O₂ ^-), accompanied by increasing activity of the antioxidant enzyme system in vivo. Under osmotic stresses, the overexpression of IpDHN in Arabidopsis can elevate the expression of ROS-related and stress-responsive genes and can improve the ROS-scavenging ability. Our results indicated that IpDHN is involved in cellular responses to salt and drought through a series of pleiotropic effects that are likely involved in ROS scavenging and therefore influence the physiological processes of microorganisms and plants exposed to many abiotic stresses.

Dynamic Thiol/Disulphide Homeostasis in Children and Adolescents with Non-Autoimmune Subclinical Hypothyroidism

OBJECTIVE

To evaluate the thiol/disulphide homeostasis in children with non-autoimmune subclinical hypothyroidism (SHT).

SUBJECTS AND METHODS

Thiol/disulphide homeosta sis, involving native thiol (SH), disulphide (SS), and total thiol (SS + SH), was evaluated in 60 children and adolescents who were negative for thyroid auto-antibodies (anti-thyroid peroxidase, anti-thyroglobulin) and had a thyroid-stimulating hormone (TSH) value of > 5 mIU/L, and in 40 sex- and age-matched healthy control subjects who were negative for thyroid autoantibodies and had normal TSH levels. Lipid profiles and urine iodine levels were also determined.

RESULTS

SH (466 ± 32.8 vs. 462 ± 32.1 μmol/L p = 0.59), SH + SS (508 ± 34.0 vs. 506 ± 32.7 μmol/L, p = 0.81), SS (21 ± 5.5 vs. 22 ± 5.8 μmol/L, p = 0.41), SS/SH (4.5 ± 1.2 vs. 4.8 ± 1.3%, p = 0.36), SS/SH + SS (4.1 ± 1.0 vs. 4.3 ± 1.1%, p = 0.36) and SH/SH + SS (91 ± 2.1 vs. 91 ± 2.1%, p = 0.31) levels were similar in children with SHT and control subjects (p > 0.05). There was no difference between total cholesterol, triglyceride, and low-density lipoprotein levels in SHT patients and controls. No difference was detected between the patients with or without iodine deficiency in the SHT group in terms of thiol/disulphide homeostasis parameters.

CONCLUSION

The status of dynamic thiol/disulphide homeostasis did not change in children and adolescents with non-autoimmune SHT. Future studies are needed for the evaluation of oxidative stress in patients with long-standing non-autoimmune SHT.

A near-infrared xanthene fluorescence probe for monitoring peroxynitrite in living cells and mouse inflammation model

A novel near-infrared xanthene fluorescence probe for monitoring peroxynitrite in vitro and in vivo.

Role of Mitochondrial Reactive Oxygen Species in the Activation of Cellular Signals, Molecules, and Function

Mitochondria are a major source of intracellular energy and reactive oxygen species in cells, but are also increasingly being recognized as a controller of cell death. Here, we review evidence of signal transduction control by mitochondrial superoxide generation via the nuclear factor-κB (NF-κB) and GATA signaling pathways. We have also reviewed the effects of ROS on the activation of MMP and HIF. There is significant evidence to support the hypothesis that mitochondrial superoxide can initiate signaling pathways following transport into the cytosol. In this study, we provide evidence of TATA signal transductions by mitochondrial superoxide. Oxidative phosphorylation via the electron transfer chain, glycolysis, and generation of superoxide from mitochondria could be important factors in regulating signal transduction, cellular homeostasis, and cell death.

Post-illumination cellular effects of photodynamic treatment

Increased interest in clinical application of photodynamic therapy (PDT) in various medical fields poses a demand for better understanding of processes triggered by photo-treatment. Most of the work on PDT performed so far has focused on the immediate effects of photo-treatment. It is generally accepted that cellular damage occurs during light exposure and within a short period thereafter. If cells are not killed during the PDT, they might recover, depending on the extent of the photo-induced damage. Little is known, however, about the relationship between the properties of photosensitizers (PSs) and the delayed consequences of PDT. The aim of this work was to investigate cellular responses to sub-lethal photodynamic treatment and how toxicogenic potency may be affected by molecular features of the PS. Results demonstrated that for cationic porphyrin-based PSs, lipophilicity is the main factor determining the fate of the cells in the 24-hour post-illumination period. PSs with amphiphilic properties initiated oxidative reactions that continued in the dark, long after light exposure, and caused suppression of metabolism and loss of cell viability with concomitant changes in electrophoretic mobility of proteins, including caspases. Apoptotic activity was not stimulated in the post-illumination period. This study demonstrated that in PDT mediated by amphiphilic cationic metalloporphyrin PSs, even when immediate photo-damage is relatively mild, destructive oxidative processes initiated during PDT continue in the absence of light to substantially impair metabolism, and that post-illumination protein modification may modify utilization of cell death pathways.

Titin isoforms are increasingly protected against oxidative modifications in developing rat cardiomyocytes

During the perinatal adaptation process N2BA titin isoforms are switched for N2B titin isoforms leading to an increase in cardiomyocyte passive tension (F_passive). Here we attempted to reveal how titin isoform composition and oxidative insults (i.e. sulfhydryl (SH)-group oxidation or carbonylation) influence F_passive of left ventricular (LV) cardiomyocytes during rat heart development. Moreover, we also examined a hypothetical protective role for titin associated small heat shock proteins (sHSPs), Hsp27 and αB-crystallin in the above processes. Single, permeabilized LV cardiomyocytes of the rat (at various ages following birth) were exposed either to 2,2'-dithiodipyridine (DTDP) to provoke SH-oxidation or Fenton reaction reagents (iron(II), hydrogen peroxide (H₂O₂), ascorbic acid) to induce protein carbonylation of cardiomyocytes in vitro. Thereafter, cardiomyocyte force measurements for F_passive determinations and Western immunoblot assays were carried out for the semiquantitative determination of oxidized SH-groups or carbonyl-groups of titin isoforms and to monitor sHSPs' expressions. DTDP or Fenton reagents increased F_passive in 0- and 7-day-old rats to relatively higher extents than in 21-day-old and adult animals. The degrees of SH-group oxidation or carbonylation declined with cardiomyocyte age to similar extents for both titin isoforms. Moreover, the above characteristics were mirrored by increasing levels of HSP27 and αB-crystallin expressions during cardiomyocyte development. Our data implicate a gradual build-up of a protective mechanism against titin oxidation through the upregulation of HSP27 and αB-crystallin expressions during postnatal cardiomyocyte development.

Emerging Roles of Ganoderma Lucidum in Anti-Aging

Ganoderma lucidum is a white-rot fungus that has been viewed as a traditional Chinese tonic for promoting health and longevity. It has been revealed that several extractions from Ganoderma lucidum, such as Ethanol extract, aqueous extract, mycelia extract, water soluble extract of the culture medium of Ganoderma lucidum mycelia, Ganodermasides A, B, C, D, and some bioactive components of Ganoderma lucidum, including Reishi Polysaccharide Fraction 3, Ganoderma lucidum polysaccharides I, II, III, IV, Ganoderma lucidum peptide, Ganoderma polysaccharide peptide, total G. lucidum triterpenes and Ganoderic acid C1 could exert lifespan elongation or related activities. Although the use of Ganoderma lucidum as an elixir has been around for thousands of years, studies revealing its effect of lifespan extension are only the tip of the iceberg. Besides which, the kinds of extractions or components being comfrimed to be anti-aging are too few compared with the large amounts of Ganoderma lucidum extractions or constituients being discovered. This review aims to lay the ground for fully elucidating the potential mechanisms of Ganoderma lucidum underlying anti-aging effect and its clinical application.

Assessment of fructose overload in the metabolic profile and oxidative/nitrosative stress in the kidney of senescent female rats

The aging process is a complex phenomenon that leads the body to several changes, affecting its integrity and resulting in chronic pathologies, which compromises health and quality of life of elderly people. Animals supplemented with fructose have been used as an experimental model for induction of insulin resistance. The objective of this study was to evaluate the metabolic effects and the levels of oxidative/nitrosative stress in the kidney of senescent rats with a high fructose intake. The animals were allocated into 4 groups: young control (Y), aged control (A), young fructose (YF) and aged fructose (AF). Groups Y and A received water and groups YF and AF received fructose (100g/L) in the water, both ad libitum. After 12weeks of high fructose intake, the animals were sacrificed to collect their kidneys, blood and the thoracic aorta. The results are presented as mean±SE, analyzed by the One-Way ANOVA test with Newman-Keuls post-test; significant at p<0.05. The fructose overload caused metabolic dysfunctions and insulin resistance, confirming the efficacy of the chosen model. In this study, we observed a body weight gain in the studied groups (except in the elderly fructose group), and an increase in general caloric intake, diuresis and adipose tissue; insulin resistance, increased fasting glucose, triglycerides and cholesterol in the fructose groups. We also found a loss of renal function, increased oxidative/nitrosative stress and inflammation, and a reduction of antioxidants and a lower vasodepressor response in the studied groups, especially those who consumed fructose. In summary, our data showed that aging or high fructose intake contributed to the increase of oxidative/nitrosative stress in animals, demonstrating that at the dose and the period of fructose treatment utilized in this study, fructose was not able to aggravate several aspects which were already altered by aging. We believe that the high fructose intake simulates most of the effects of aging, and this understanding would be useful to prevent or minimize many of the alterations caused by this condition.

Effect of Oxidation and Protein Unfolding on Cross-Linking of β-Lactoglobulin and α-Lactalbumin

Oxidation and heat treatment can initiate changes in the amino acid composition, structure, solubility, hydrophobicity, conformation, function, and susceptibility to proteolysis of proteins. These can result in adverse consequences for mammals, plants, foodstuffs, and pharmaceuticals. This study investigated whether and how individual or combined treatment with heat, a commonly encountered factor in industrial processing, and H₂O₂ alters the structure and composition of two major milk whey proteins, α-lactalbumin and β-lactoglobulin, and mixtures of these. Thermal treatment induced reducible cross-links in isolated β-lactoglobulin, but not isolated α-lactalbumin under the conditions employed. Cross-linking occurred at lower temperatures and to a greater extent in the presence of low concentrations of H₂O₂. H₂O₂ did not induce cross-linking in the absence of heat. Mixtures of α-lactalbumin and β-lactoglobulin showed similar behavior, except that mixed α-lactalbumin-β-lactoglobulin dimers were detected. Cross-linking was associated with formation of sulfenic acids (RS-OH species), oxidation of methionine residues, cleavage of disulfide bonds in α-lactalbumin, altered conformation of disulfide bonds in β-lactoglobulin, alterations in the fluorescence intensity and maximum emission wavelength of endogenous tryptophan residues, and binding of the hydrophobic probe 8-anilinonaphthalenesulfonate. These data are consistent with increased unfolding and subsequent aggregation of the protein, with these changes being maximized in the presence of both heat and H₂O₂. The enhanced aggregation detected with H₂O₂ is consistent with additional pathways to aggregation above that induced by heat alone. These mechanistic insights provide potential strategies for modulating the extent and nature of protein modification induced by thermal and oxidant treatment.

Hypoglycemic and Hypolipidemic Effects of Seed Extract from Antidesma bunius (L.) Spreng in Streptozotocin-induced Diabetic Rats

BACKGROUND

Antidesma bunius (L.) Spreng has been reported to possess various beneficial medicinal properties. Scientific information about this plant is limited. This study was therefore, designed to determine hypoglycaemic and hypolipidemic effects of ethanol seed extract from A. bunius (ABSE). Antioxidant activity and also acute toxicity were conducted.

METHODOLOGY

The hypoglycaemic and hypolipidemic effects were studied by oral giving ABSE at a dose of 250 mg kg -1 to streptozotocin-induced diabetic rats daily for 6 weeks. Antioxidant activity was studied using DPPH assay. The ABSE at the doses of 500, 1000, 1500 and 2000 mg kg -1 were employed in the acute toxicity study.

RESULTS

The results revealed that ABSE significantly (p<0.05) reduced the blood glucose level and recovered the pathology of hematological values, but significantly (p<0.05) increased the body weight and slightly increased serum insulin of the diabetic rats. However, ABSE recovered pathology of hematological values, but affected renal and hepatic functions in the treated rats by producing an alteration of creatinine, albumin, total protein, BUN and ALP. Interestingly, ABSE increased WBC and HDL, but reduced CHOL, LDL and TG both in normal and diabetic ABSE treated rats. The ABSE possessed relatively low antioxidant activity with IC50 of 2174±14.24 mg mL -1 compared to vitamin C (1.48±0.07 μg mL -1). Fortunately, ABSE did not produce any symptoms of acute toxicity and mortality in the rats.

CONCLUSION

The ethanol seed extract from A. bunius possesses hypoglycemic and hypolipidemic effects. The ABSE also recovered the pathology of the hematology but may cause renal dysfunction in the diabetic rats. The hypoglycemic and hypolipidemic effects are likely due to its antioxidant and insulin secretion activities.

Evaluation of dynamic thiol-disulfide homeostasis in very low-birth-weighted preterms

BACKGROUND

Thiols are organic compounds containing sulfhydryl groups which exert antioxidant effects via dynamic thiol-disulfide homeostasis. The shift towards disulfides indicates the presence of oxidative environment. Thiol-disulfide homeostasis has not been evaluated in neonates. We aimed to evaluate dynamic thiol-disulfide homeostasis in preterm infants.

METHODS

Preterm infants with birth weight less than 1500 g (25-32 weeks of gestation) were included. Infants with major congenital anomaly, perinatal asphyxia, twin to twin transfusion and infants who were mechanically ventilated and nil by mouth for more than 3 days or fed with formula, had intraventricular hemorrhage ≥ grade 2 or sepsis, received blood/blood product transfusion or inotrope treatment and developed bronchopulmonary dysplasia or retinopathy of prematurity (≥ stage 3), and died were excluded thereafter. Serum thiol-disulfide homeostasis was evaluated for three times: (Baseline, first week, third week). Serum native thiol, total thiol and disulfide were measured (µmol/Lt), disulfide:native thiol, disulfide:total thiol, and native thiol:total thiol ratios were calculated. Wilcoxon's test was used to analyze the significance of change in measurements. Baseline results were analyzed for gender and mode of delivery.

RESULTS

Eighty preterm infants [1255 (1080-1415) grams] were included. Baseline values were native thiol: 209.54 ± 41.83 µmol/L; total thiol: 251.70 ± 45.82 µmol/L; disulfide: 21.08 ± 7.43 µmol/Lt; disulfide:native thiol: 10.49 ± 4.62; disulfide:total thiol: 8.45 ± 2.93; native thiol:total thiol: 83.10 ± 5.87. Thiol levels increased in each measurement, disulfide and disulfide/thiol ratios increased in the first week, decreased in the third week, ratio of native/total thiol decreased in the first week, increased in the third week. No effect of gender or mode of delivery on baseline thiol-disulfide homeostasis was detected.

CONCLUSIONS

The shift in the thiol-disulfide equilibrium towards disulfides in the first week can be attributed to subjection of infants to many oxidative insults. Furthermore, the thiol predominance in the third week could be explained by the decrease in oxidative events and increase in feeding as a supply of antioxidants. This study, displaying the levels of the dynamic thiol-disulfide homeostasis in preterm infants without obvious risks for increased oxidative stress, may provide acceptable range for thiol-disulfide homeostasis in recovering preterm infants.

Biochemical, Histopathological and Molecular Responses in Gills of Leuciscus cephalus Exposed to Metals

Gills are major targets for acute metal toxicity in fish, due to their permanent contact with aquatic pollutants. To assess the effects of metals on gills of the Leuciscus cephalus (chub), fish individuals were collected from two sites in the Tur River, Romania, in upstream (site 1) and downstream (site 2) of a metal pollution source. Quantitative and hyperspectral analyses showed that Zn, Sr, and Fe concentrations were significantly higher in gills from site 2 compared with site 1. Malondialdehyde and advanced oxidation protein products levels increased 17 and 28%, respectively, whereas reduced glutathione level diminished significantly in the gills of fish collected from site 2 compared to site 1. The activities of superoxide dismutase, catalase, and glutathione-S-transferase increased significantly at 41, 21, and 28%, respectively. Proliferating cell nuclear antigen (PCNA) protein levels, as well as the amount of DNA damage, were significantly increased for site 2 compared with site 1. The induced oxidative stress generated hyperplasia, hypertrophy, and inflammation in the epithelial cells and apoptosis. Hence, this could suggest that gill cells have tried to counteract the oxidative stress-induced DNA fragmentation by PCNA up-regulation, but the PCNA expression decreased on longer time due to the low level of GSH, resulting in apoptosis.

Peroxyl radical- and photo-oxidation of glucose 6-phosphate dehydrogenase generates cross-links and functional changes via oxidation of tyrosine and tryptophan residues

Protein oxidation is a frequent event as a result of the high abundance of proteins in biological samples and the multiple processes that generate oxidants. The reactions that occur are complex and poorly understood, but can generate major structural and functional changes on proteins. Current data indicate that pathophysiological processes and multiple human diseases are associated with the accumulation of damaged proteins. In this study we investigated the mechanisms and consequences of exposure of the key metabolic enzyme glucose-6-phosphate dehydrogenase (G6PDH) to peroxyl radicals (ROO^•) and singlet oxygen (¹O₂), with particular emphasis on the role of Trp and Tyr residues in protein cross-linking and fragmentation. Cross-links and high molecular mass aggregates were detected by SDS-PAGE and Western blotting using specific antibodies. Amino acid analysis has provided evidence for Trp and Tyr consumption and formation of oxygenated products (diols, peroxides, N-formylkynurenine, kynurenine) from Trp, and di-tyrosine (from Tyr). Mass spectrometric data obtained after trypsin-digestion in the presence of H₂¹⁶O and H₂¹⁸O, has allowed the mapping of specific cross-linked residues and their locations. These data indicate that specific Tyr-Trp and di-Tyr cross-links are formed from residues that are proximal and surface-accessible, and that the extent of Trp oxidation varies markedly between sites. Limited modification at other residues is also detected. These data indicate that Trp and Tyr residues are readily modified by ROO^• and ¹O₂ with this giving products that impact significantly on protein structure and function. The formation of such cross-links may help rationalize the accumulation of damaged proteins in vivo.

A single cysteine post-translational oxidation suffices to compromise globular proteins kinetic stability and promote amyloid formation

Oxidatively modified forms of proteins accumulate during aging. Oxidized protein conformers might act as intermediates in the formation of amyloids in age-related disorders. However, it is not known whether this amyloidogenic conversion requires an extensive protein oxidative damage or it can be promoted just by a discrete, localized post-translational modification of certain residues. Here, we demonstrate that the irreversible oxidation of a single free Cys suffices to severely perturb the folding energy landscape of a stable globular protein, compromise its kinetic stability, and lead to the formation of amyloids under physiological conditions. Experiments and simulations converge to indicate that this specific oxidation-promoted protein aggregation requires only local unfolding. Indeed, a large scale analysis indicates that many cellular proteins are at risk of undergoing this kind of deleterious transition; explaining how oxidative stress can impact cell proteostasis and subsequently lead to the onset of pathological states.

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The population of aggregation-prone states by natural proteins does not require their extensive oxidation.

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A single residue irreversible oxidation suffices to promote the formation of amyloid fibrils.

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Under oxidative stress, many cellular proteins are at risk of aggregating into toxic species.

Shellfish: Nutritive Value, Health Benefits, and Consumer Safety

Shellfish is a major component of global seafood production. Specific items include shrimp, lobsters, oysters, mussels, scallops, clams, crabs, krill, crayfish, squid, cuttlefish, snails, abalone, and others. Shellfish, in general, contain appreciable quantities of digestible proteins, essential amino acids, bioactive peptides, long-chain polyunsaturated fatty acids, astaxanthin and other carotenoids, vitamin B₁₂ and other vitamins, minerals, including copper, zinc, inorganic phosphate, sodium, potassium, selenium, iodine, and also other nutrients, which offer a variety of health benefits to the consumer. Although shellfish are generally safe for consumption, their exposure to diverse habitats, the filter feeding nature of shellfish such as oysters, clams, and mussels, and unhealthy farming and handling practices may occasionally entail health risks because of possible presence of various hazards. These hazards include pathogenic organisms, parasites, biotoxins, industrial and environmental pollutants, heavy metals, process-related additives such as antibiotics and bisulfite, and also presence of allergy-causing compounds in their bodies. Most of the hazards can be addressed by appropriate preventive measures at various stages of harvesting, farming, processing, storage, distribution, and consumption. Furthermore, consumer safety of shellfish and other seafood items is strictly monitored by international, governmental, and local public health organizations. This article highlights the nutritional value and health benefits of shellfish items and points out the various control measures to safeguard consumer safety with respect to the products.

Eukaryotic translation initiation factor 2 subunit α (eIF2α) inhibitor salubrinal attenuates paraquat-induced human lung epithelial-like A549 cell apoptosis by regulating the PERK-eIF2α signaling pathway

Paraquat (PQ), as one of the most widely used herbicides in the world, can cause severe lung damage in humans and animals. This study investigated the underlying molecular mechanism of PQ-induced lung cell damage and the protective role of salubrinal. Human lung epithelial-like A549 cells were treated with PQ for 24h and were pre-incubated with salubrinal for 2h, followed by 500μM of PQ treatment. Silencing eIF2α gene of the A549 cells with siRNA interference method was conducted. Cell morphology, cell viability, apoptosis and caspase-3 activity were assessed by different assays accordingly thereafter. The expression of PERK, p-PERK, ATF6, c-ATF6, IRE1α, p-IRE1α, CHOP, GRP78, p-eIF2α and β-actin was assayed by western blot. The data showed that PQ significantly reduced A549 cell viability, changed cell morphology, induced cell apoptosis and significantly upregulated the levels of GRP78, CHOP, p-PERK, c-ATF6 and p-IRE1α. However, 30μM salubrinal could attenuate the effects of PQ on damages to A549 cells through upregulating p-eIF2α. In contrast, knocking down eIF2α gene inhabited the effects of salubrinal. These results suggest that PQ-induced A549 cell apoptosis involved endoplasmic reticulum (ER) stress, specially the PERK-eIF2α pathway. Salubrinal attenuated A549 cells from PQ-induced damages through regulation of the PERK-eIF2α signaling.

Selective Inactivation of Bacteriophage in the Presence of Bacteria by Use of Ground Rh-Doped SrTiO3 Photocatalyst and Visible Light

Bacteriophage (denoted as phage) infection in the bacterial fermentation industry is a major problem, leading to the loss of fermented products such as alcohol and lactic acid. Currently, the prevention of phage infection is limited to biological approaches, which are difficult to apply in an industrial setting. Herein, we report an alternative chemical approach using ground Rh-doped SrTiO₃ (denoted as g-STO:Rh) as a visible-light-driven photocatalyst. The g-STO:Rh showed selective inactivation of phage without bactericidal activity when irradiated with visible light (λ > 440 nm). After inactivation, the color of g-STO:Rh changed from gray to purple, suggesting that the Rh valence state partially changed from 3+ to 4+ induced by photocatalysis, as confirmed by diffuse reflectance spectroscopy. To study the effect of the Rh⁴⁺ ion on phage inactivation under visible-light irradiation, the survival rate of phage for g-STO:Rh was compared to that for ground Rh,Sb-codoped SrTiO₃ (denoted as g-STO:Rh,Sb), where the change of Rh valence state from 3+ to 4+ is almost suppressed under visible-light irradiation due to charge compensation by the Sb⁵⁺ ion. Only g-STO:Rh effectively inactivated phage, which indicated that Rh⁴⁺ ion induced by photocatalysis particularly contributed to phage inactivation under visible-light irradiation. These results suggested that g-STO:Rh has potential as an antiphage material in bacterial fermentation.

Amidinoquinoxaline N-oxides: spin trapping of O- and C-centered radicals

Amidinoquinoxaline N-oxides represent a novel family of heterocyclic spin traps. In this work, their ability to trap O- and C-centered radicals was tested using selected derivatives with different structural modifications. All the studied nitrones were able to trap radicals forming persistent spin adducts, also in the case of OH and OOH radicals which are of wide biological interest as examples of ROS. The stability of the adducts was mainly attributed to the wide delocalization of the unpaired electron over the whole quinoxaline moiety. The nitroxide spectral parameters (hfccs and g-factors) were analyzed and the results were supported by DFT calculations. The N-19 hfccs and g-factors were characteristic of each aminoxyl and could aid in the identification of the trapped radical. The enhanced stability of the OH adducts under the employed reaction conditions could be ascribed to their possible stabilization by IHBs with two different acceptors: the N-O˙ moiety or the amidine functionality. DFT calculations indicate that the preferred IHB is strongly conditioned by the amidine ring size. While five membered homologues show a clear preference for the IHB with the N-O˙ group, in six membered derivatives this stabilizing interaction is preferentially established with the amidine nitrogen as an IHB acceptor.

Health Effects of Dietary Oxidized Tyrosine and Dityrosine Administration in Mice with Nutrimetabolomic Strategies

This study aims to investigate the health effects of long-term dietary oxidized tyrosine (O-Tyr) and its main product (dityrosine) administration on mice metabolism. Mice received daily intragastric administration of either O-Tyr (320 μg/kg body weight), dityrosine (Dityr, 320 μg/kg body weight), or saline for consecutive 6 weeks. Urine and plasma samples were analyzed by NMR-based metabolomics strategies. Body weight, clinical chemistry, oxidative damage indexes, and histopathological data were obtained as complementary information. O-Tyr and Dityr exposure changed many systemic metabolic processes, including reduced choline bioavailability, led to fat accumulation in liver, induced hepatic injury, and renal dysfunction, resulted in changes in gut microbiota functions, elevated risk factor for cardiovascular disease, altered amino acid metabolism, induced oxidative stress responses, and inhibited energy metabolism. These findings implied that it is absolutely essential to reduce the generation of oxidation protein products in food system through improving modern food processing methods.

Functional characterization of KS-type dehydrin ZmDHN13 and its related conserved domains under oxidative stress

Dehydrins belong to the group 2 family LEA (Late Embryogenesis Abundant) proteins, which are up-regulated in most plants during cold and drought stress. According to the number and order of the Y-, S- and K-segments, dehydrins are classified into five subclasses: YnSKn, YnKn, SKn, Kn and KnS. Here, the maize (Zea mays L.) KS-type dehydrin gene, ZmDHN13, was identified and later characterized. Expression profiling demonstrated that ZmDHN13 was constitutively expressed, but its expression was also altered by high osmosis, low temperature, oxidative stress and abscisic acid (ABA). Furthermore, the roles of the three conserved segments in phosphorylation, localization, binding metal ions and physiological functions were explored. ZmDHN13 was mainly localized in the nucleus, depending on phosphorylation status. Additional studies indicated that ZmDHN13 could be phosphorylated by CKII (casein kinase II), when the NLS (nuclear localization signal) segment and the S-segment were core sequences. The overexpression of ZmDHN13 enhanced transgenic tobacco tolerance to oxidative stress, and the three conserved segments exhibited a cooperative effect in response to environmental stresses in vivo.

The effect of oxidation on the structure of G-actin and its binding ability with aroma compounds in carp grass skeletal muscle

To investigate the influence of oxidative modifications of G-actin on its binding ability with aroma compounds, the influence of H₂O₂ treatments on G-actin structure and the absorption for alcohols and aldehydes was investigated. Raman spectroscopy and scanning electron microscopy were used to evaluate structural changes of G-actin; GC-MS was used to analyze the binding with alcohols and aldehydes. Results showed that 0-5mM H₂O₂ enhanced the absorption of G-actin toward alcohols involved in the formation of hydrogen bonds by increasing α-helix and carbonyl values. 0-1mM H₂O₂ caused the release of aldehydes with decreased sulfhydryl sites. 1-20mM H₂O₂ increased the retention of aldehydes, due to the increased hydrophobic sites by G-actin rebuilding and aggregating. The aggregated G-actin favoured the hydrophobic interactions with aroma compounds, forming the protein-aroma compound complex, thus enhancing the resultant binding ability, as evidenced by scanning electron microscopy and GC/MS analysis.

Prothrombin and fibrinogen carbonylation: How that can affect the blood clotting

OBJECTIVES

The aim of the work was the development of a simple method for measuring the plasma prothrombin carbonylation and the study the impact of prothrombin and fibrinogen oxidation on the rate of plasma clotting.

METHODS

A new method was based on the ability of prothrombin to be adsorbed by the barium sulfate. It consists of four steps: prothrombin mixing with the water suspension of BaSO4; reaction of 2,4-dinitrophenylhydrazine with the BaSO4-bound prothrombin; desorption of prothrombin-2,4-dinitrophenylhydrazone complex from BaSO4 in an alkaline medium; neutralization and reading of the optical absorbance of the complex (λ = 370 nm). The prothrombin/fibrinogen carbonylation and plasma clotting rate in vitro in the presence of reactive oxygen species (ROS)-generating agents (0.05-0.8 mM Fe2+/H2O2) were monitored.

RESULTS

The plasma volume required for measurement of carbonylated prothrombin was 0.4 ml. High level of linearity and reproducibility was observed (r = 0.9995, P = 0.0005 - for the protein; r = 0.9971, P = 0.0029 - for carbonyls). In the intact rats, the concentration of blood plasma prothrombin was 0.355 ± 0.009 mg/ml, and that of carbonyls was 4.94 ± 0.09 nmol/mg.

DISCUSSION

Prothrombin and plasma clotting rate was not affected by low concentrations of ROS (0.05-0.2 mM Fe2+/H2O2). The fibrinogen was susceptible to ROS-related effect over all the used range of concentration (0.05-0.8 mM Fe2+/H2O2). Carbonylation of fibrinogen did not affect the plasma clotting activity at low ROS concentration (0.05-0.2 mM Fe2+/H2O2), however it retarded the clotting at higher ROS (0.2-0.8 mM Fe2+/H2O2).

Oxidative Stress Evaluation in Patients Treated with Orthodontic Self-ligating Multibracket Appliances: An in Vivo Case-Control Study

OBJECTIVE

Oxidative stress is a pathologic event induced by a prevalence of oxidant agents on the antioxidant ones, with a consequent alteration of oxide-reducing balance.

INTRODUCTION

Freeradicals produce damages both in cellular and extra-cellular components; phospholipid membranes, proteins, mitochondrial and nuclear DNA, are the target of the oxidative stress, that can finally cause cellular death due to apoptosis.

MATERIALS & METHODS

Orthodontic appliances such as brackets, wires, resins and soldering have some components that can be considered as potential allergen, carcinogenic, cytotoxic and gene mutation factors. The primary aim of this research is to evaluate oxidative stress in the saliva of patients treated with multibracket self-ligating vestibular orthodontic appliances; the secondary purpose is to investigate the influence of orthodontic multibracket therapy on oral hygiene and the consequent effect on oxidative stress. Salivary specimens has been collected in a sample of 23 patients were enrolled (12 Female, 11 Male) between 12 and 16 years of age (mean age 14.2). For each patient has been collected a salivary specimen at the following time points; before orthodontic bonding (T1), five weeks (T2) and ten weeks (T3) after orthodontic appliance bonding.

RESULTS

Samples has been analysed with a photometer due to SAT Test (Salivary Antioxidant Test). Data obtained show a mean of 2971 mEq/l of anti-oxidant agents before orthodontic treatment, and after five weeks from the bonding the mean was decreased to 2909 mEq/l, instead at ten weeks was increased to 3332 mEq/l. Repeated measures ANOVA did not reveal statistically significant differences between the time points (P = 0.1697). The study did not reveal any correlation between the level of dental hygiene and that of oxidative stress (Pearson Correlation Coefficient R = 0).

CONCLUSION

Orthodontic treatment with multibrackets vestibular metallic appliance seems to be not able to affect oxidative stress during the first ten weeks of therapy.

Uranyl Photocleavage of Phosphopeptides Yields Truncated C-Terminally Amidated Peptide Products

The uranyl ion (UO₂²⁺) binds phosphopeptides with high affinity, and when irradiated with UV‐light, it can cleave the peptide backbone. In this study, high‐accuracy tandem mass spectrometry and enzymatic assays were used to characterise the photocleavage products resulting from the uranyl photocleavage reaction of a tetraphosphorylated β‐casein model peptide. We show that the primary photocleavage products of the uranyl‐catalysed reaction are C‐terminally amidated. This could be of great interest to the pharmaceutical industry, as efficient peptide amidation reactions are one of the top challenges in green pharmaceutical chemistry.