Immunochemical detection of oxidative DNA damage in cancer and aging using anti-reactive oxygen species modified DNA monoclonal antibody

The presence of osteocalcin, osteopontin and reactive oxygen species-positive cells in pulp tissue after dental bleaching

AIM

To analyse the influence of H₂ O₂ on pulp repair through osteocalcin and osteopontin immunolabelling and in cellular defence by using the antireactive oxygen species (ROS) antibody.

METHODOLOGY

The maxillary molars of 50 rats were treated with 35% H₂ O₂ (Ble groups) or placebo gel (control groups). At 0 h and 2, 7, 15 and 30 days (n = 10 hemimaxillae), the rats were killed and pulp tissue was evaluated using inflammation and immunolabelling scores (osteocalcin/osteopontin); ROS-positive cells were counted. Paired t-test and Wilcoxon signed-rank test were used (P < 0.05).

RESULTS

The Ble group had necrosis in the coronal pulp at 0 h and in the occlusal third of the coronal pulp at 2 days; at 7, 15 and 30 days, no inflammation was noted similar to the controls (P > 0.05). Osteocalcin was absent in the Ble at 0 h, moderate at 2 days and increased thereafter, differing from the controls at all two periods (P < 0.05). Osteopontin was higher principally at 7 and 15 days in Ble groups, but differing with control groups from 2 days after bleaching (P < 0.05). The Ble group had more ROS-positive cells in the pulp at 7 and 15 days (P < 0.05). Tertiary dentine was observed at 7 days, increasing thereafter (P < 0.05).

CONCLUSIONS

Post-bleaching pulp repair was associated with increased osteocalcin over time. Osteopontin also participated in this process, and anti-ROS was involved in cellular defence against H₂ O₂ .

The protective effect of Ginsenoside Rg1 on aging mouse pancreas damage induced by D-galactose

The protective effect and mechanism of Ginsenoside Rg1 on aging mouse pancreas damaged by D-galactose (D-gal)-induced was studied. Two-month-old male C57BL/6J mice were randomly divided into three groups of 10 mice per group. The D-gal group of mice received hypodermic injection of D-gal (120 mg/kg/day) for 42 days; the Rg1+D-gal group of mice receiving D-gal + intraperitoneal injection Rg1 (40 mg/kg/day) for 27 days from the 16th day of D-gal replication; and the naïve group that constituted the normal control mice receiving the same dose of saline instead of the drug. The related indicators were tested on the second day after modeling and administration. Fasting blood glucose (FBG), oral glucose tolerance test (OGTT) and fasting insulin level were measured by taking peripheral blood. Samples of pancreas were weighed and visceral index was calculated. Paraffin sections were prepared. H&E staining sections were produced to observe pancreatic tissue morphology. Immunohistochemical staining was used to observe advanced glycation end products (AGEs) and integral optical density (IOD) of stained positive tissue in pancreas. Ultrathin slices were used to observe ultrastructural change of pancreatic tissue. Frozen sections were prepared to test the relative optical density of positive cells that were stained by senescence-associated β-galactosidase (SA-β-gal) in pancreatic tissue. Superoxide dismutase (SOD), malonaldehyde (MDA) and total antioxidant capacity (T-AOC) were detected by preparing pancreas tissue homogenates. Compared with the control group, Rg1+D-gal mice had significantly decreased pancreatic wet weight and visceral index and significantly lower FBG; OGTT for 30 and 120 min. There was no significant difference of the blood sugar level between the groups. The area under the curve and the number and size of the nucleated cells within islet were markedly reduced. In addition, SA-β-gal-positive particles in pancreas tissue intracytoplasmic cells significantly decreased and relative optical density also reduced. The IOD of AGEs in pancreas tissue and MDA content decreased. SOD and T-AOC activity significantly increased. Ginsenoside Rg1 can be effective antagonistic structure and function of the pancreas injury induced by D-gal. The mechanism may be associated with reducing oxidative damage.

From cell senescence to age-related diseases: differential mechanisms of action of senescence-associated secretory phenotypes

Cellular senescence is a process by which cells enter a state of permanent cell cycle arrest. It is commonly believed to underlie organismal aging and age-associated diseases. However, the mechanism by which cellular senescence contributes to aging and age-associated pathologies remains unclear. Recent studies showed that senescent cells exert detrimental effects on the tissue microenvironment, generating pathological facilitators or aggravators. The most significant environmental effector resulting from senescent cells is the senescence-associated secretory phenotype (SASP), which is constituted by a strikingly increased expression and secretion of diverse pro-inflammatory cytokines. Careful investigation into the components of SASPs and their mechanism of action, may improve our understanding of the pathological backgrounds of age-associated diseases. In this review, we focus on the differential expression of SASP-related genes, in addition to SASP components, during the progress of senescence. We also provide a perspective on the possible action mechanisms of SASP components, and potential contributions of SASP-expressing senescent cells, to age-associated pathologies.

Fullerene-polyvinylpyrrolidone clathrate localizes in the cytoplasm to prevent Ultraviolet-A ray-induced DNA-fragmentation and activation of the transcriptional factor NF-kappaB

By Western blot and immunostaining we proved that polyvinylpyrrolidone (PVP)-wrapped fullerene molecules (PVP-fullerene) could combine the 8- and 53-kb proteins which localize in the membrane of human skin keratinocytes HaCaT. Only fullerene molecules are able to cross the lipid membrane and conjugate 53-kb proteins in the cytosol. There are no fullerene molecules detectable in the nucleus or cytoskeleton. Ultraviolet-A (UVA)-irradiation on HaCaT or normal human epidermal melanocytes (NHEM) caused nuclear fragmentations, lowering of intracellular DNA-contents below diploidy, concurrently with the repressed DNA synthesis and the increased DNA-3'OH cleavage terminals, all of which were repressed by PVP-fullerene, as shown by flow cytometry and PI- or TUNEL-stain fluorography. Translocation of the transcriptional factor NF-kappaB in the cytoplasm to the nucleus of the keratinocytes was caused with UVA and repressed by PVP-fullerene with cytoprotective effects. Thus, the PVP-fullerene may be developed as a UV-protective agent with DNA-preservative effects owing to its combinative ability to molecules in the cytoplasm and cytomembrane, and then represses cellular oxidative stress and blocks abnormal signal pathways.

Biological evaluation of layered double hydroxides as efficient drug vehicles

Recently there has been a rapid expansion of the development of bioinorganic hybrid systems for safe drug delivery. Layered double hydroxides (LDH), a variety of available inorganic matrix, possess great promise for this purpose. In this study, an oxidative stress biomarker system, including measurement of reactive oxygen species, glutathione content, endogenous nitric oxide, carbonyl content in proteins, DNA strand breaks and DNA-protein crosslinks, was designed to evaluate the biocompatibility of different concentrations of nano-Zn/Al-LDH with a Hela cell line. The drug delivery activity of the LDH-folic-acid complex was also assessed. The resulting data clearly demonstrated that nano-LDH could be applied as a relatively safe drug vehicle with good delivery activity, but with the caveat that the effects of high dosages observed here should not be ignored when attempting to maximize therapeutic activity by increasing LDH concentration.

Aging research in India

Research on aging in India has been well documented since ancient times. As way back as 3000-1500 BC, the Indian medical system of Ayurveda was used as a means for the prevention of the effects of aging and generation of disease in organs or the whole organism, respectively. In recent years, the focus has been demographic studies on different aspects of aging and has been in isolation. Molecular aspects of aging have been addressed only by a few groups of scientists which has focused on regulation of gene expression, DNA damage and repair, development of immunochemical reagents to detect oxidative DNA damage and assessing the levels of circulating antibodies to reactive oxygen species modified DNA (ROS-DNA), etc. This review aims to recapitulate various research studies on aging since 3000 BC to date.

Oxidative DNA damage: biological significance and methods of analysis

All forms of aerobic life are subjected constantly to oxidant pressure from molecular oxygen and also reactive oxygen species (ROS), produced during the biochemical utilization of O2 and prooxidant stimulation of O2 metabolism. ROS are thought to influence the development of human cancer and more than 50 other human diseases. To prevent oxidative DNA damage (protection) or to reverse damage, thereby preventing mutagenesis and cancer (repair), the aerobic cell possesses antioxidant defense systems and DNA repair mechanisms. During the last 20 years, many analytical techniques have been developed to monitor oxidative DNA base damage. High-performance liquid chromatography-electrochemical detection and gas chromatography-mass spectrometry are the two pioneering contributions to the field. Currently, the arsenal of methods available include the promising high-performance liquid chromatography-tandem mass spectrometry technique, capillary electrophoresis, 32P-postlabeling, fluorescence postlabeling, 3H-postlabeling, antibody-base immunoassays, and assays involving the use of DNA repair glycosylases such as the comet assay, the alkaline elution assay, and the alkaline unwinding method. Recently, the use of liquid chromatography-mass spectrometry has been introduced for the measurement of a number of modified nucleosides in oxidatively damaged DNA. The bulk of available chromatographic methods aimed at measuring individual DNA base lesions require either chemical hydrolysis or enzymatic digestion of oxidized DNA, following extraction from cells or tissues. The effect of experimental conditions (DNA isolation, hydrolysis, and/or derivatization) on the levels of oxidatively modified bases in DNA is enormous and has been studied intensively in the last 10 years.

Antigen binding characteristics of antibodies induced against nitric oxide modified plasmid DNA

Nitric oxide (NO) generated by the reduction of sodium nitrite with sodium dithionite caused damage to plasmid Bluescript DNA leading to strand breaks and base modifications. The NO-plasmid DNA was highly immunogenic in rabbits. The antibody activity was inhibited to the extent of 86% with the immunogen as inhibitor, indicating the induction of immunogen specific antibodies. However, delineating the antigenic specificity of anti-NO-plasmid DNA antibodies by competition ELISA, multiple cross-reactivity was observed. The antibodies recognised B-, A- and allied conformations. The visual detection of immune complex formation with native and NO-plasmid DNA reiterated preferential binding with modified plasmid DNA. DNA modified by nitric oxide presents unique epitopes which may be one of the factors in antigen-driven autoimmune response in systemic lupus erythematosus.