Pawan Kumar Maurya

Markers of Oxidative Stress in Erythrocytes during Aging in Humans

Abstract:  The correlation between antioxidant capacity and oxidative damage during aging has been reported in several tissues in different species; however, data on changes of oxidative stress markers in plasma and erythrocytes of healthy populations during aging are few and sometimes contradictory. Since antioxidant capacity of the plasma is related to dietary intake of antioxidants, it is important to study the correlation between antioxidant capacity of the plasma and markers of oxidative stress in different populations. In the present study we report the age‐dependent alteration in erythrocyte malondialdehyde (MDA), intracellular‐reduced glutathione (GSH), and membrane sulphydryl (SH) groups in the Indian population and also correlate these parameters with total plasma antioxidant potential. We show an age‐dependent increase in erythrocyte MDA level and a decrease in GSH and membrane −SH group concentration. The alterations in these parameters correlated significantly with total antioxidant capacity of the plasma. We observe a higher oxidative stress in the Indian population compared to values reported for European subjects emphasizing the need to establish age‐dependent reference values for oxidative stress markers in different populations and in studies involving their role in different disease conditions.

The role of oxidative and nitrosative stress in accelerated aging and major depressive disorder

Major depressive disorder (MDD) affects millions of individuals and is highly comorbid with many age associated diseases such as diabetes mellitus, immune-inflammatory dysregulation and cardiovascular diseases. Oxidative/nitrosative stress plays a fundamental role in aging, as well as in the pathogenesis of neurodegenerative/neuropsychiatric disorders including MDD. In this review, we critically review the evidence for an involvement of oxidative/nitrosative stress in acceleration of aging process in MDD. There are evidence of the association between MDD and changes in molecular mechanisms involved in aging. There is a significant association between telomere length, enzymatic antioxidant activities (SOD, CAT, GPx), glutathione (GSH), lipid peroxidation (MDA), nuclear factor κB, inflammatory cytokines with MDD. Major depression also is characterized by significantly lower concentration of antioxidants (zinc, coenzyme Q10, PON1). Since, aging and MDD share a common biological base in their pathophysiology, the potential therapeutic use of antioxidants and anti-aging molecules in MDD could be promising.

Protective role of tea catechins on erythrocytes subjected to oxidative stress during human aging

Antioxidant effect of tea catechins has been shown in many epidemiological studies. In the present study we report the protective mechanism of tea catechins (EGCG, ECG, EGC, EC) on various oxidative stress parameters, which are elevated during aging in humans. We hereby report the in vitro effect of tea catechins on erythrocyte malondialdehyde (MDA), reduced glutathione (GSH), and on membrane sulphydryl (–SH) group in humans. Results show an age-dependent increase in erythrocyte MDA level and a decrease in GSH and membrane–SH group concentration. We report that tea catechins show significant protection to erythrocyte against oxidative stress induced by tert-butyl hydroperoxide (t-BHP). The effect was more pronounced in older age group compared to lower age group. The findings suggest a possible role of tea catechins as anti-aging compounds.

Plasma protein oxidation and its correlation with antioxidant potential during human aging

Previous studies have indicated that the main molecular characteristic of aging is the progressive accumulation of oxidative damages in cellular macromolecules. Proteins are one of the main molecular targets of age-related oxidative stress, which have been observed during aging process in cellular systems. Reactive oxygen species (ROS) can lead to oxidation of amino acid side chains, formation of protein-protein cross-linkages, and oxidation of the peptide backbones. In the present study, we report the age-dependent oxidative alterations in biomarkers of plasma protein oxidation: protein carbonyls (PCO), advanced oxidation protein products (AOPPs) and plasma total thiol groups (T-SH) in the Indian population and also correlate these parameters with total plasma antioxidant potential. We show an age dependent decrease in T-SH levels and increase in PCO and AOPPs level. The alterations in the levels of these parameters correlated significantly with the total antioxidant capacity of the plasma. The levels of oxidized proteins in plasma provide an excellent biomarker of oxidative stress due to the relative long half-life of such oxidized proteins.

Ascorbate recycling by erythrocytes during aging in humans.

Erythrocytes play a crucial role in recycling ascorbate in blood plasma. The erythrocyte ascorbate free radical (AFR) reductase is involved in the reduction of AFR to ascorbic acid (ASC) in the plasma. In the present study, we report an age-dependent increase in the activity of erythrocyte AFR reductase in humans that shows a significant positive correlation with the activity of plasma membrane redox system (PMRS). We explain the age-dependent increase in erythrocyte ASC recycling on the basis of a compensatory/protective mechanism that operates to maintain the ASC level in plasma and thereby minimize oxidative stress during aging.

l-Cysteine Efflux in Erythrocytes As A Function of Human Age: Correlation with Reduced Glutathione and Total Anti-Oxidant Potential

Thiol compounds such as cysteine (Cys) and reduced glutathione (GSH) play an important role in human aging and age-related diseases. In erythrocytes, GSH is synthesized by glutamic acid, cysteine, and glycine, but the rate of GSH synthesis is determined only by the availability of L-cysteine. Cysteine supplementation has been shown to ameliorate several parameters that are known to degenerate during human aging. We have studied L-cysteine efflux in vitro in human erythrocytes as a function of age by suspending cells in solution containing 10 mM L-cysteine for uptake; later cells were re-suspended in phosphate-buffered saline (PBS)-glucose to allow efflux. Change in the free sulfhydryl (-SH) concentration was then measured to calculate the rate of efflux. The GSH/oxidized glutathione (GSSG) ratio was taken as a control to study the oxidation/reduction state of the erythrocyte. The total anti-oxidant potential of plasma was measured in terms of ferric reducing ability of plasma (FRAP) values. We have shown a significant (p<0.0001) decline in the efflux of L-cysteine in erythrocytes during human aging, and the GSH/GSSG ratio decreases as a function of human age. The decline in L-cysteine efflux during aging correlates with the decrease in GSH and the FRAP value. This finding may help to explain the shift in the redox status and low GSH concentration that might determine the rate of L-cysteine efflux observed in erythrocytes and an important factor in the development of oxidative stress in erythrocytes during aging.

L-Cysteine Influx in Erythrocytes as a Function of Human Age

In erythrocytes, although three amino acids are required for the synthesis of reduced glutathione (GSH), the rate of GSH synthesis is determined only by the availability of L-cysteine. Cysteine supplementation has been shown to ameliorate several parameters that are known to degenerate during human aging; this has led to an interesting hypothesis that aging could be a cysteine deficiency syndrome. In the present study, we measured L-cysteine influx in human erythrocytes by suspending cells in solution containing 10 mM L-cysteine. We show a significant decline in the influx of L-cysteine in erythrocytes during aging in humans. The decrease in cysteine influx correlates with the decrease in antioxidant potential of plasma measured in terms of FRAP (ferric-reducing ability of plasma) during aging. We conclude that a decreased influx of L-cysteine may be an important factor contributing to the development of oxidative stress in human erythrocytes during aging.

Decreased Activity of Ca++-ATPase and Na+/K+-ATPase during Aging in Humans

Aging is a biological process characterized by a progressive functional impairment which is associated with increased susceptibility to a variety of diseases. The main purpose of this study is to understand the gender-based relationship between human aging and activities of two erythrocyte membranes bound enzymes, Ca++-ATPase and Na+/K+-ATPase. Ca++-ATPase and Na+/K+-ATPase activities were determined as per the previous reports. Statistical differences were analyzed with Student’s t test. Our results show a significant (p < 0.0001) decrease in the Ca++-ATPase and Na+/K+-ATPase activities in males and females as a function of age. We also correlate the activities of ATPases with total antioxidant capacity of the plasma in term of ferric reducing ability of plasma values. The Ca++-ATPase and Na+/K+-ATPase activities positively correlated with ferric reducing ability of plasma value. No significant differences in the ATPase activity between males and females were observed. Decreased activity of Ca++-ATPase and Na+/K+-ATPase during human aging may be due to increased free radical generation which leads to oxidative stress and alter the erythrocyte membrane transport function and other activities. Our results emphasize the need to establish age-dependent reference values for membrane bound enzymes in studies involving its role in different disease conditions.

Intracellular uptake of (-)epicatechin by human erythrocytes as a function of human age

The present studies were carried out to determine the intracellular uptake of (‐)epicatechin by erythrocytes during aging in humans. (‐)Epicatechin uptake was estimated by performing ethyl acetate extraction while the total antioxidant potential of the (‐)epicatechin was estimated in terms of FRAP (ferric reducing ability of plasma) values. A significant (p < 0.001) decrease in (‐)epicatechin uptake by human erythrocytes was observed as a function of age. It is hypothesized that the uptake of (‐)epicatechin in human erythrocytes has an important role in the regulation of PMRS (plasma membrane redox system) activity during normal human aging. Copyright

Shifting paradigm of cancer diagnoses in clinically relevant samples based on miniaturized electrochemical nanobiosensors and microfluidic devices

Cancer is one of leading causes of death in the world and occurs in more than two hundred types according to the National Cancer Institute. Its early diagnosis has been remained a prime focus amongst scientists and clinicians since long, not only to understand the complications but also to mitigate its chance of further proliferation. Nowadays, tremendous advances in nanotechnology-empowered diagnostics are serving a substantial input to identify biomarkers associated with various cancers. These biomarkers are found in different forms including overexpressed proteins/surface antigens, metabolites, miRNA, and the entire cell as well. Several approaches have been adopted to detect such cancer biomarkers, where electrochemical sensors have widely been appreciated due to its high sensitivity, selectivity, robustness, and miniaturized point-of-care cancer diagnostics. Due to its immense importance, the present review has been formulated describing classical concepts of cancer biomarker discovery followed by the recent status of electrochemical biosensors for cancer diagnoses. Particularly, we have summarized the state-of-the-art technologies based on potentiometric, impedimetric, amperometric, voltammetric biosensors for the detection of different biomarkers viz. protein, miRNA, whole cell and biomarkers generated by metabolic shift in response to carcinoma population. Apart from these, we have also highlighted different deliverable microfluidics-based approaches and recent prototypes for cancer detection. To put various perceptive insights on the recent advancements in cancer diagnostics, an extended table is incorporated, which includes sensor fabrication strategies, type of biomarkers, detection strategies, and analytical performance of the cancer biosensor since last five years (2013-2017).