Loss of epigenetic information as a cause of mammalian aging.

All living things experience an increase in entropy, manifested as a loss of genetic and epigenetic information. In yeast, epigenetic information is lost over time due to the relocalization of chromatin-modifying proteins to DNA breaks, causing cells to lose their identity, a hallmark of yeast aging. Using a system called "ICE" (inducible changes to the epigenome), we find that the act of faithful DNA repair advances aging at physiological, cognitive, and molecular levels, including erosion of the epigenetic landscape, cellular exdifferentiation, senescence, and advancement of the DNA methylation clock, which can be reversed by OSK-mediated rejuvenation. These data are consistent with the information theory of aging, which states that a loss of epigenetic information is a reversible cause of aging.

Luminal Delivery of Pectin-Modified Oxygen Microbubbles Mitigates Rodent Experimental Intestinal Ischemia.

INTRODUCTION: Ischemic gut injury is common in the intensive care unit, impairs gut barrier function, and contributes to multiorgan dysfunction. One novel intervention to mitigate ischemic gut injury is the direct luminal delivery of oxygen microbubbles (OMB). Formulations of OMB can be modified to control the rate of oxygen delivery. This project examined whether luminal delivery of pectin-modified OMB (OMBp5) can reduce ischemic gut injury in a rodent model. METHODS: The OMBp5 formulation was adapted to improve delivery of oxygen along the length of small intestine. Adult Sprague-Dawley rats (n = 24) were randomly allocated to three groups: sham-surgery (SS), intestinal ischemia (II), and intestinal ischemia plus luminal delivery of OMBp5 (II + O). Ischemia-reperfusion injury was induced by superior mesenteric artery occlusion for 45 min followed by reperfusion for 30 min. Outcome data included macroscopic score of mucosal injury, the histological score of gut injury, and plasma biomarkers of intestinal injury. RESULTS: Macroscopic, microscopic data, and intestinal injury biomarker results demonstrated minimal intestinal damage in the SS group and constant damage in the II group. II + O group had a significantly improved macroscopic score throughout the gut mucosa (P = 0.04) than the II. The mean histological score of gut injury for the II + O group was significantly improved on the II group (P ≤ 0.01) in the proximal intestine only, within 30 cm of delivery. No differences were observed in plasma biomarkers of intestinal injury following OMBp5 treatment. CONCLUSIONS: This proof-of-concept study has demonstrated that luminal OMBp5 decreases ischemic injury to the proximal small intestine. There is a need to improve oxygen delivery over the full length of the intestine. These findings support further studies with clinically relevant end points, such as systemic inflammation and vital organ dysfunction.

Broadband-excitation-based mechanical spectroscopy of highly viscous tissue-mimicking phantoms.

Standard rheometers assess mechanical properties of viscoelastic samples up to 100 Hz, which often hinders the assessment of the local-scale dynamics. We demonstrate that high-frequency analysis can be achieved by inducing broadband waves and monitoring their media-dependent propagation using optical coherence tomography. Here, we present a new broadband wave analysis based on two-dimensional Fourier transformation. We validated this method by comparing the mechanical parameters to monochromatic excitation and a standard oscillatory test data. Our method allows for high-frequency mechanical spectroscopy, which could be used to investigate the local-scale dynamics of different biological tissues and the influence of diseases on their microstructure.

The influence of hyperglycemia on the safety of ultrasound in retinal pigment epithelial cells.

Ultrasound (US) assisted drug delivery is receiving interest in treating posterior eye diseases, such as diabetic retinopathy due to its ability to maximize drug penetration into difficult to reach tissues. Despite its promise, the technique has only been investigated using healthy cell and tissue models, with no evidence to date about its safety in active disease. As a result, the aim of this study was to evaluate the safety of US administration in vitro in retinal pigment epithelial cells under normal and high glucose conditions. US protocols within the presently accepted safety threshold were applied and their influence on cell membrane and tight junction integrity as well as intracellular inflammation was evaluated using lactate dehydrogenase (LDH), zona occludens-1 (ZO-1), fluorescein isothiocyanate (FITC)-dextran dye leak and nuclear factor-kappaB (NF-κB) assays, respectively. Under high glucose conditions, US application increased LDH release and resulted in loss of ZO-1 labeling at 2 h; however, normal levels were restored within 24 h. US within its safety parameters did not induce any FITC-dextran dye leak or NF-κB nuclear translocation in normal or high glucose conditions. In conclusion, our results suggest that while high glucose conditions increase cell susceptibility to US-mediated stress, basal conditions can be restored within 24 h without long-lasting cell damage.

Relationship between rheological properties and transverse relaxation time (T2) of artificial and porcine vitreous humour.

Vitreous liquefactive processes play an integral role in ocular health. Knowledge of the degree of liquefaction would allow better monitoring of ocular disease progression and enable more informed therapeutic dosing for an individual patient. Presently this process cannot be monitored in a non-invasive manner. Here, we evaluated whether magnetic resonance imaging (MRI) could predict the viscoelasticity and in turn liquefactive state of artificial and biological vitreous humour. Gels comprising identical concentrations of hyaluronic acid and agar ranging from 0.125 to 2.25 mg/ml of each polymer were prepared and their T2 was measured using a turbo-spin echo sequence via 3T clinical MRI. The gels were subsequently subjected to rheological frequency and flow sweeps and trends between T2 and rheological parameters were assessed. The relationship between T2 and vitreous humour rheology was further assessed using ex vivo porcine eyes. An optimised imaging technique improved homogeneity of obtained artificial vitreous humour T2 maps. Strong correlations were observed between T2 and various rheological parameters of the gels. Translation to porcine vitreous humour demonstrated that the T2 of biological tissue was related to its viscoelastic properties. This study shows that T2 can be correlated with various rheological parameters within gels. Future investigations will assess the translatability of these findings to live models.

Evaluation of 2 ex vivo Bovine Cornea Storage Protocols for Drug Delivery Applications.

The use of corneal tissue for ex vivo therapeutic evaluations is limited due to its rapid loss of viability after excision. Optimization of storage conditions may allow prolonged retention of physical tissue properties. In this study, we evaluated how storage in optimized organ culture (OC) medium at 37°C or phosphate-buffered saline (PBS) at 2-8°C impacted physical properties of bovine corneas. Tissue hydration, permeability and histology were monitored at baseline and following 1, 4 and 7 days of storage. Corneas stored in OC demonstrated significantly higher hydration and permeability when compared to those stored in PBS. Histology revealed that storage in OC consistently caused detachment of the epithelial layer by day 4 of storage, whereas both storage conditions caused a significant increase in stromal thickness and tissue vacuolation. This study highlights the limitations of currently available corneal tissue storage approaches for ex vivo drug permeation studies.

Development and Evaluation of Lipid Nanoparticles Containing Natural Botanical Oil for Sun Protection: Characterization and in vitro and in vivo Human Skin Permeation and Toxicity.

The use of sunscreen products is widely promoted by schools, government agencies, and health-related organizations to minimize sunburn and skin damage. In this study, we developed stable solid lipid nanoparticles (SLNs) containing the chemical UV filter octyl methoxycinnamate (OMC). In parallel, we produced similar stable SLNs in which 20% of the OMC content was replaced by the botanical urucum oil. When these SLNs were applied to the skin of human volunteers, no changes in fluorescence lifetimes or redox ratios of the endogenous skin fluorophores were seen, suggesting that the formulations did not induce toxic responses in the skin. Ex vivo (skin diffusion) tests showed no significant penetration. In vitro studies showed that when 20% of the OMC was replaced by urucum oil, there was no reduction in skin protection factor (SPF), suggesting that a decrease in the amount of chemical filter may be a viable alternative for an effective sunscreen, in combination with an antioxidant-rich vegetable oil, such as urucum. There is a strong trend towards increasing safety of sun protection products through reduction in the use of chemical UV filters. This work supports this approach by producing formulations with lower concentrations of OMC, while maintaining the SPF. Further investigations of SPF in vivo are needed to assess the suitability of these formulations for human use.

Phase transition of a microemulsion upon addition of cyclodextrin - applications in drug delivery.

This study reports on the impact of cyclodextrin addition on the phase behavior of microemulsion systems. Three distinct oil-in-water microemulsions were formulated and subjected to increasing concentrations of various cyclodextrins. The prepared formulations underwent visual, textural and microscopic characterization followed by the evaluation of their in vitro drug release and ex vivo tissue retention behavior. Combining microemulsions with cyclodextrins resulted in either phase separation or transition into a liquid crystalline state depending on the concentration and type of cyclodextrin utilized. Formulations combined with α-cyclodextrin consistently demonstrated transition into a liquid crystalline state as confirmed by polarized light and cryo-scanning electron microscopy. In these cases, cyclodextrin addition was also positively correlated with an increase in formulation hardness, adhesiveness and turbidity. Release and clearance studies revealed that drug diffusion from the microemulsions could be slowed and tissue retention prolonged by increasing the cyclodextrin content. These findings pave the way for the development of novel cyclodextrin-microemulsion-based liquid crystalline formulations in a variety of sustained drug delivery applications.

IGF-1 receptor haploinsufficiency leads to age-dependent development of metabolic syndrome.

Individuals born small for gestational age (SGA) are at a higher risk of developing the metabolic syndrome later in life. IGF-1 resistance has been reported in placentae from SGA births and mutations in the Igf1 receptor gene have been reported in several cohorts of SGA subjects. We have used the Igf1r heterozygous (Igf1r+/-) male mouse as a model to investigate the mechanisms by which Igf1r haploinsufficiency leads to insulin resistance. Despite exhibiting IGF-1 resistance, insulin signaling is enhanced in young Igf1r+/- mice but is attenuated in the muscle of old Igf1r+/- mice. Although smaller than WT (wild type) mice, old-aged Igf1r+/- had increased adiposity and exhibit increased lipogenesis. We hypothesize that IGF-1 resistance initially causes a transient increase in insulin signaling thereby promoting a lipogenic phenotype, which subsequently leads to insulin resistance.

Activation of AMP-activated protein kinase prevents TGF-ß1-induced epithelial-mesenchymal transition and myofibroblast activation.

Transforming growth factor (TGF)-ß contributes to tubulointerstitial fibrosis. We investigated the mechanism by which TGF-ß exerts its profibrotic effects and specifically the role of AMP-activated protein kinase (AMPK) in kidney tubular epithelial cells and interstitial fibroblasts. In proximal tubular epithelial cells, TGF-ß1 treatment causes a decrease in AMPK phosphorylation and activation together with increased fibronectin and α-smooth muscle actin expression and decreased in E-cadherin. TGF-ß1 causes similar changes in interstitial fibroblasts. Activation of AMPK with 5-aminoimidazole-4-carboxamide 1-ß-d-ribofuranoside, metformin, or overexpression of constitutively active AMPK markedly attenuated TGF-ß1 functions. Conversely, inhibition of AMPK with adenine 9-ß-d-arabinofuranoside or siRNA-mediated knockdown of AMPK (official name PRKAA1) mimicked the effect of TGF-ß1 and enhanced basal and TGF-ß1-induced phenotypic changes. Importantly, we found that tuberin contributed to the protective effects of AMPK and that TGF-ß1 promoted cell injury by blocking AMPK-mediated tuberin phosphorylation and activation. In the kidney cortex of TGF-ß transgenic mice, the significant decrease in AMPK phosphorylation and tuberin phosphorylation on its AMPK-dependent activating site was associated with an increase in mesenchymal markers and a decrease in E-cadherin. Collectively, the data indicate that TGF-ß exerts its profibrotic action in vitro and in vivo via inactivation of AMPK. AMPK and tuberin activation prevent tubulointerstitial injury induced by TGF-ß. Activators of AMPK provide potential therapeutic strategy to prevent kidney fibrosis and progressive kidney disease.

Targeting NADPH oxidase with a novel dual Nox1/Nox4 inhibitor attenuates renal pathology in type 1 diabetes.

Reactive oxygen species (ROS) generated by Nox NADPH oxidases may play a critical role in the pathogenesis of diabetic nephropathy (DN). The efficacy of the Nox1/Nox4 inhibitor GKT137831 on the manifestations of DN was studied in OVE26 mice, a model of type 1 diabetes. Starting at 4-5 mo of age, OVE26 mice were treated with GKT137831 at 10 or 40 mg/kg, once-a-day for 4 wk. At both doses, GKT137831 inhibited NADPH oxidase activity, superoxide generation, and hydrogen peroxide production in the renal cortex from diabetic mice without affecting Nox1 or Nox4 protein expression. The increased expression of fibronectin and type IV collagen was reduced in the renal cortex, including glomeruli, of diabetic mice treated with GKT137831. GKT137831 significantly reduced glomerular hypertrophy, mesangial matrix expansion, urinary albumin excretion, and podocyte loss in OVE26 mice. GKT137831 also attenuated macrophage infiltration in glomeruli and tubulointerstitium. Collectively, our data indicate that pharmacological inhibition of Nox1/4 affords broad renoprotection in mice with preexisting diabetes and established kidney disease. This study validates the relevance of targeting Nox4 and identifies GKT137831 as a promising compound for the treatment of DN in type 1 diabetes.

Translating ultrasound-mediated drug delivery technologies for CNS applications.

Ultrasound enhances drug delivery into the central nervous system (CNS) by opening barriers between the blood and CNS and by triggering release of drugs from carriers. A key challenge in translating setups from in vitro to in vivo settings is achieving equivalent acoustic energy delivery. Multiple devices have now been demonstrated to focus ultrasound to the brain, with concepts emerging to also target the spinal cord. Clinical trials to date have used ultrasound to facilitate the opening of the blood-brain barrier. While most have focused on feasibility and safety considerations, therapeutic benefits are beginning to emerge. To advance translation of these technologies for CNS applications, researchers should standardise exposure protocol and fine-tune ultrasound parameters. Computational modelling should be increasingly used as a core component to develop both in vitro and in vivo setups for delivering accurate and reproducible ultrasound to the CNS. This field holds promise for transformative advancements in the management and pharmacological treatment of complex and challenging CNS disorders.

Design and evaluation of curcumin-loaded poloxamer hydrogels as injectable depot formulations.

Poloxamer hydrogels are of interest as injectable depot delivery systems. However, their use for delivering hydrophobic drugs, such as curcumin, is limited due to poor loading capacity. Here, we evaluated the influence of incorporating hydrophobic medium chain triglycerides (MCT] or amphiphilic polyethylene glycol 400 (PEG400) on the physicochemical properties, drug loading, and in-vitro compatibility of a curcumin-loaded poloxamer hydrogel. Poloxamer 407 and 188 hydrogel formulations (16:6 w/w) were prepared and MCT and PEG400 (saturated with curcumin) were added to these systems, either alone or in combination, up to 10 % w/w. Formulation viscoelasticity, gelation behaviour, injectability, morphology and release profiles were assessed. The cytocompatibility of the formulations was also assessed on dermal fibroblasts (HDFn). Both additives increased curcumin loading into the formulation. Addition of MCT to the hydrogel lowered its gelation temperature, while PEG400 had no notable impact. Both additives increased the force required to inject the formulation. PEG400 containing systems were single phase whereas MCT addition created emulsion systems. All formulations released ∼20-30 % of their loaded curcumin in sustained fashion over 24 h. The modified hydrogel systems showed great biocompatibility on cells when administering up to 100-150 µM curcumin into the culture. This study addresses a key limitation in loading hydrophobic drugs into hydrogels and provides a strategy to enhance drug loading into and performance of hydrogels by integrating additives, such as MCT and PEG400 into the systems.

Investigating the influence of ultrasound parameters on ibuprofen drug release from hydrogels.

Hydrogels are promising ultrasound-responsive drug delivery systems. In this study, we investigated how different ultrasound parameters affected drug release and structural integrity of self-healing hydrogels composed of alginate or poloxamers. The effects of amplitude and duty cycle at low frequency (24 kHz) ultrasound stimulation were first investigated using alginate hydrogels at 2% w/v and 2.5% w/v. Increasing ultrasound amplitude increased drug release from these gels, although high amplitudes caused large variations in release and damaged the gel structure. Increasing duty cycle also increased drug release, although a threshold was observed with the lower pulsed 50% duty cycle achieving similar levels of drug release to a continuous 100% duty cycle. Poloxamer-based hydrogels were also responsive to the optimised parameters at low frequency (24 kHz, 20% amplitude, 50% duty cycle for 30 s) and showed similar drug release results to a 2.5% w/v alginate hydrogel. Weight loss studies demonstrated that the 2% w/v alginate hydrogel underwent significant erosion following ultrasound application, whereas the 2.5% w/v alginate and the poloxamer gels were unaffected by application of the same parameters (24 kHz, 20% amplitude, 50% duty cycle for 30 s). The rheological properties of the hydrogels were also unaffected and the FTIR spectra remained unchanged after low frequency ultrasound stimulation (24 kHz, 20% amplitude, 50% duty cycle for 30 s). Finally, high-frequency ultrasound stimulation (1 MHz, 3 W.cm-2, 50% duty cycle) was also trialled; the alginate gels were less responsive to this frequency, while no statistically significant impact on drug release was observed from the poloxamer gels. This study demonstrates the importance of ultrasound parameters and polymer selection in designing ultrasound-responsive hydrogels.

Management of zygomatico maxillary complex fractures.

Zygomatic bone fractures should be effectively diagnosed and treated because they affect how the face is shaped for both aesthetically and functional reasons. It is possible to compare different surgical techniques and their comorbidities objectively through using outcome quantitative assessments, which call for a treatment programme and long-term follow-up. The purpose of this study was to compare the outcomes of two procedures and the effectiveness of the zygomatic bone following open reduction internal fixation (ORIF) employing two-point fixation and ORIF employing three-point fixation. Two groups of twenty patients each were randomly assigned to. Twenty patients in Group A had ORIF treatment using two-point miniplate fixation technique, and twenty patients in Group B received three-point miniplate fixation treatment. Differences between the two categories were ascertained after they had been evaluated in terms of their advantages and disadvantages. We discovered that the two-point fixation group had the fewest facial complications and neurological side effects. At 1 month follow up, Group B's average radiological evaluation score was 2.47± 0.30, and then at 6 months follow up, it was found out to be 1.87±0.47. A significant statistical distinction between the average radiological evaluations was observed in study participants of Group A at follow up done after one month and six months of procedure. Student's paired t- statistical test was utilized from this statistical analysis. (t = 6.54, P < 0.01). On carrying out follow up after one month of surgery, average neurological assessment score in study participants of group A was found out to be 0.22± 0.42, and then at 6 months follow up, it was 0.61±0.63. The average neurological evaluation score in study participants of Group A on carrying out follow up after one month of surgical procedure and and after six months of surgical procedure months showed a significant statistical distinction when utilizing Student's paired t- statistical test (t = 2.51, P = 0.021).It was determined that the best available rehabilitation for the treatment of zygomaticomaxillary complex fractures is open reduction and internal fixation employing two-point fixation by miniplates.

A comprehensive update of micro- and nanobubbles as theranostics in oncology.

Advances in diagnostic and imaging capabilities have allowed cancers to be detected earlier and characterized more robustly. These strategies have recently branched into theranostics whereby contrast agents traditionally used for imaging have been co-loaded with therapeutics to simultaneously diagnose and treat cancers in a patient-specific manner. Microbubbles (MBs) and nanobubbles (NBs) are contrast agents which can be modulated to meet theranostic needs particularly in the realm of oncology. The current review focuses on ultrasound-responsive MB/NB platforms used as a theranostic tool in oncology. We discuss in detail the key parameters that influence the utility of MB/NB formulations and implications of such treatment modalities. Recent advances in composition strategies, latest works in the pre-clinical stages and multiple paradigm-shifting innovations in the field of MB/NB are discussed in-depth in this review. The clinical application of MB/NB is currently limited to diagnostic imaging. Surface chemistry modification strategies will help tune the formulations toward therapeutic applications. It is also anticipated that MB/NB will see increased use to deliver gas therapeutics. Scalability and stability considerations will be at the forefront as these particles get introduced into the clinical theranostic toolbox.

High fat diet induced insulin resistance and glucose intolerance are gender-specific in IGF-1R heterozygous mice.

Interactions between genes and environment play a critical role in the pathogenesis of type 2 diabetes. Low birth weight, due to genetic and environmental variables affecting fetal growth, is associated with increased susceptibility to the development of type 2 diabetes and metabolic disorders in adulthood. Clinical studies have shown that polymorphisms in the Insulin-like growth factor 1 (IGF-1) gene or heterozygous mutations in IGF-1 and IGF-1 receptor (IGF-1R) genes, resulting in reduced IGF-1 action, are associated with low birth weight and post-natal growth. Mice lacking one of the IGF-1R alleles (Igf1r(+/-)) exhibit a 10% reduction in post-natal growth, and develop glucose intolerance (males) and insulin resistance (males and females) as they age. To investigate whether adverse environmental factors could accelerate the onset of the metabolic syndrome, we conducted a short duration intervention of high fat diet (HFD) feeding in male and female Igf1r(+/-) and wild-type (WT) control mice. The HFD resulted in insulin resistance, hyperglycemia, and impaired glucose tolerance in males of both genotypes whereas in females exacerbated diabetes was observed only in the Igf1r(+/-) genotype, thus suggesting a sexual dimorphism in the influence of obesity on the genetic predisposition to diabetes caused by reduced IGF-1 action.

Paraoxonase-1 genetic polymorphisms and susceptibility to DNA damage in workers occupationally exposed to organophosphate pesticides.

Human paraoxonase 1 (PON1) is a lipoprotein-associated enzyme involved in the detoxification of organophosphate pesticides (OPs) by hydrolyzing the bioactive oxons. Polymorphisms of the PON1 gene are responsible for variation in the expression and catalytic activity of PON1 enzyme. In the present study, we have determined (a) the prevalence of two common PON1 polymorphisms, (b) the activity of PON1 and acetylcholinesterase enzymes, and (c) the influence of PON1 genotypes and phenotypes variation on DNA damage in workers exposed to OPs. We examined 230 subjects including 115 workers exposed to OPs and an equal number of normal healthy controls. The results revealed that PON1 activity toward paraoxon (179.19±39.36 vs. 241.52±42.32nmol/min/ml in controls) and phenylacetate (112.74±17.37 vs. 134.28±25.49µmol/min/ml in controls) was significantly lower in workers than in control subjects (p<0.001). No significant difference was observed in the distribution of genotypes and allelic frequencies of PON1(192)QR (Gln/Arg) and PON1(55)LM (Leu/Met) in workers and control subjects (p>0.05). The PON1 activity toward paraoxonase was found to be significantly higher in the R/R (Arg/Arg) genotypes than Q/R (Gln/Arg) and lowest in Q/Q (Gln/Gln) genotypes in both workers and control subjects (p<0.001). For PON1(55)LM (Leu/Met), PON1 activity toward paraoxonase was observed to be higher in individuals with L/L (Leu/Leu) genotypes and lowest in individuals with M/M (Met/Met) genotypes in both groups (p<0.001). No influence of PON1 genotypes and phenotypes was seen on the activity of acetylcholinesterase and arylesterase. The DNA damage was observed to be significantly higher in workers than in control subjects (p<0.05). Further, the individuals who showed least paraoxonase activity i.e., those with (Q/Q [Gln/Gln] and M/M [Met/Met]) genotypes showed significantly higher DNA damage compared to other isoforms in workers exposed to OPs (p<0.05). The results indicate that the individuals with PON1 Q/Q and M/M genotypes are more susceptible toward genotoxicity. In conclusion, the study suggests wide variation in enzyme activities and DNA damage due to polymorphisms in PON1 gene, which might have an important role in the identification of individual risk factors in workers occupationally exposed to OPs.

Genetic polymorphisms of GSTM1, GSTT1 and GSTP1 and susceptibility to DNA damage in workers occupationally exposed to organophosphate pesticides.

GSTM1, T1 and P1 are important enzymes of glutathione S-transferases (GSTs), involved in the metabolism of many endogenous and exogenous compounds. Individual genetic variation in these metabolizing enzymes may influence the metabolism of their substrates. The present study was designed to determine the genotoxic effects using DNA damage and its association with GSTM1, GSTT1, and GSTP1 (Ile105Val) genetic polymorphisms in workers occupationally exposed to organophosphate pesticides (OPs). We examined 230 subjects including 115 workers occupationally exposed to OPs and an equal number of normal healthy controls. The DNA damage was evaluated using the alkaline comet assay and genotyping was done using individual PCR or PCR-RFLP. Significantly higher DNA tail moment (TM) was observed in workers as compared to control subjects (14.41 ± 2.25 vs. 6.36 ± 1.41 tail % DNA, p<0.001). The results revealed significantly higher DNA TM in workers with GSTM1 null genotype than those with GSTM1 positive (15.18 vs. 14.15 tail % DNA, p=0.03). A significantly higher DNA TM was also observed in workers with homozygous Ile-Ile GSTP1 genotype than heterozygous (Ile-Val) and mutant (Val-Val) GSTP1 genotype (p=0.02). In conclusion, the results show that null deletion of GSTM1 and homozygote wild GSTP1 genotype could be related to inter-individual differences in DNA damage arises from the gene-environment interactions in workers occupationally exposed to OPs.