The Role of Oxidative Stress in the Clinical Manifestations of Childhood Asthma.

INTRODUCTION: The significance of oxidative stress in pathogenesis of childhood asthma was recognized, but its role in the clinical manifestations of disease is still unclear. MATERIALS AND METHODS: The study was conducted in 96 asthmatic children. The urinary biomarker of oxidative stress, 8-oxo-7,8-dihydro-2-deoxyguanosine (8-oxodG/creatinine) was determined by using HPLC-MS/MS. ELISA was performed to measure myeloperoxidase (MPO) and Cu,Zn- superoxide dismutase (Cu,Zn-SOD) in serum. RESULTS: Logistic regression analysis revealed that female gender, tobacco smoke exposure, and increased 8-oxodG/creatinine were associated with risk for intermittent asthma, while the positive allergy test and increased Cu,Zn-SOD were associated with eczema in asthmatic children. Higher MPO (p = 0.033), and percent of granulocytes (p = 0.030) were found in severe persistent asthma in comparison to intermittent or mild persistent asthma. CONCLUSION: The main findings that TSE-induced oxidative stress is a risk for intermittent asthma and eczema may be clinically significant for the disease prevention and therapeutic improvements.

Oxidative Stress and Genetic Variants of Xenobiotic-Metabolising Enzymes Associated with COPD Development and Severity in Serbian Adults.

The genetic and non-genetic factors that contribute to the development of chronic obstructive pulmonary disease (COPD) are still poorly understood. We investigated the potential role of genetic variants of xenobiotic-metabolising enzymes (glutathione-S-transferase M1, GSTM1; glutathione-S-transferase T1, GSTT1; microsomal epoxide hydrolase, mEH), oxidative stress (assessed by urinary 8-oxo-7,8-dihydro-2'-deoxyguanosine, 8-oxodG/creatinine), sex, ageing and smoking habits on susceptibility to development of COPD and its severity in Serbian population. The investigated population consisted of 153 healthy subjects (85 males and 68 females) and 71 patients with COPD (33 males and 38 females). Detection of GSTM1*null, GSTT1*null, mEH Tyr113His and mEH His139Arg gene variants was performed by PCR/RFLP method. Urinary 8-oxodG was determined using HPLC-MS/MS, and expressed as 8-oxodG/creatinine. We revealed that increased urinary 8-oxodG/creatinine and leucocytosis are the strongest independent predictors for COPD development. Increased level of oxidative stress increased the risk for COPD in males [odds ratio (OR), 95% confidence interval (CI): 8.42, 2.26-31.28], more than in females (OR, 95% CI: 3.60, 1.37-9.45). Additionally, independent predictors for COPD were ageing in males (OR, 95% CI: 1.29, 1.12-1.48), while in females they were at least one GSTM1 or GSTT1 gene deletion in combination (OR, 95% CI: 23.67, 2.62-213.46), and increased cumulative cigarette consumption (OR, 95% CI: 1.09, 1.01-1.16). Severity of COPD was associated with the combined effect of low mEH activity phenotype, high level of oxidative stress and heavy smoking. In conclusion, early identification of GSTM1*null or GSTT1*null genotypes in females, low mEH activity phenotype in heavy smokers and monitoring of oxidative stress level can be useful diagnostic and prognostic biomarkers.

Oxidative Stress and Polymorphism of Xenobiotic-Metabolizing Enzymes in Two Patients with Severe Alpha-1-Antitrypsin Deficiency.

Alpha-1-antitrypsin deficiency (AATD) and tobacco smoke play a key role in the pathogenesis of early-onset emphysema. Differences in AATD-related chronic obstructive pulmonary disease stages imply the existence of modifying factors associated with disease severity. We present two male patients with emphysema caused by severe AATD (PiZZ genotype). Both are former smokers and have epoxide hydrolase low-activity phenotype. Extremely high level of oxidative stress (high urinary 8-oxo-7,8-dihydro-2'-deoxyguanosine), increased inflammation (high serum CRP), and GSTP1 105Val mutation were found in patient with a worse lung function and prognosis. These data provide more evidence that oxidative stress-related gene variants and inflammation are associated with worse symptoms of AATD-related emphysema. Therefore, prevention against severe stage of AATD-related emphysema would include early identification of the risk gene variants, cessation or never smoking, and treatment with anti-inflammatory and anti-oxidant drugs. Additionally, urinary 8-oxodG could be a candidate for predictive biomarker for routine assessment of the oxidative stress level in AATD patients.

Gender-related differences in susceptibility to oxidative stress in healthy middle-aged Serbian adults.

Gender-related differences in the association between polymorphism of xenobiotic-metabolising enzymes or non-genetic biomarkers and susceptibility to oxidative stress was assessed in healthy middle-aged Serbian adults, by urinary 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG/creatinine) and total antioxidant status in serum (TAOS). Females were more susceptible to oxidative stress. In both genders, positive predictor of the antioxidative protection was serum triglyceride, while BMI <25 kg/m(2) was associated with oxidative stress. Susceptibility to oxidative stress in males was associated with GSTT1*null allele and increased serum iron, but in females, it was decreased serum bilirubin. Early identification of the risk factors could be important in the prevention of oxidative stress-related diseases.

Charge-density distribution and electrostatic flexibility of ZIF-8 based on high-resolution X-ray diffraction data and periodic calculations.

The electron-density distribution in a prototypical porous coordination polymer ZIF-8 has been obtained in an approach combining high-resolution X-ray diffraction data and Invariom refinement. In addition, the periodic quantum-chemical calculation has been used to describe the theoretical density features of ZIF-8 in the same geometry (m1) and also in a "high-pressure" form of ZIF-8 (m2) characterized by conformational change with respect to the methylimidazolate linker. A thorough comparison of the electronic and electrostatic properties in two limiting structural forms of ZIF-8 proposes additional aspects on diffusion and adsorption processes occurring within the framework. The dimensions of the four-membered (FM) and six-membered (SM) apertures of the ß cage are reliably determined from the total electron-density distribution. The analysis shows that FM in m2 becomes competitive in size to the SM aperture and should be considered for the diffusion of small molecules and cations. Bader's topological analysis (quantum theory of atoms in molecules) shows similar properties of both ZIF-8 forms. On the other hand, analysis of their electrostatic properties reveals tremendous differences. The study suggests exceptional electrostatic flexibility of the ZIF-8 framework, where small conformational changes lead to a significantly different electrostatic potential (EP) distribution, a feature that could be important for the function and dynamics of the ZIF-8 framework. The cavity surface in m1 contains 38 distinct regions with moderately positive, negative, or neutral EP and weakly positive EP in the cavity volume. In contrast to m1, the m2 form displays only two regions of different EP, with the positive one taking the whole cavity surface and the strong negative one localized entirely in the FM apertures. The EP in the cavity volume is also more positive than that in m1. A pronounced influence of the linker reorientation on the EP of the ZIF-8 forms is related to the high symmetry of the system and to an amplification of the electrostatic properties by cooperative effects of the proximally arranged structural fragments.

Highly efficient Michael-type addition of acetaldehyde to ß-nitrostyrenes by whole resting cells of Escherichia coli expressing 4-oxalocrotonate tautomerase.

A novel whole cell system based on recombinantly expressed 4-oxalocrotonate tautomerase (4-OT) was developed and shown to be an effective biocatalyst for the asymmetric Michael addition of acetaldehyde to ß-nitrostyrenes. Optimal ratio of substrates (2mM ß-nitrostyrenes and 20mM acetaldehyde) and biocatalyst of 5 g of cell dry weight of biocatalyst per liter was determined. Through further bioprocess improvement by sequential addition of substrate 10mM nitrostyrene biotransformation was achieved within 150 min. Excellent enantioselectivity (>99% ee) and product yields of up to 60% were obtained with ß-nitrostyrene substrate. The biotransformation product, 4-nitro-3-phenyl-butanal, was isolated from aqueous media and further transformed into the corresponding amino alcohol. The biocatalyst exhibited lower reaction rates with p-Cl-, o-Cl- and p-F-ß-nitrostyrenes with product yields of 38%, 51%, 31% and ee values of 84%, 88% and 94% respectively. The importance of the terminal proline of 4-OT was confirmed by two proline enriched variants and homology modeling.

Gender-related reference intervals of urinary 8-oxo-7,8-dihydro-2'-deoxyguanosine determined by liquid chromatography-tandem mass spectrometry in Serbian population.

OBJECTIVES: Although there are many nucleobase modifications, 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) is one of the dominant form of oxidative modifications of DNA. Urinary 8-oxodG is potentially the best non-invasive biomarker of oxidative stress. Defining reference interval for urinary 8-oxodG is a prerequisite for its clinical use as biomarker. DESIGN AND METHODS: Reference population included 229 healthy Serbian adults (130 males and 99 females). The spot urinary 8-oxodG was determined using high performance liquid chromatography and tandem mass spectrometry (HPLC-MS/MS). Urinary creatinine was measured by the kinetic Jaffé method. RESULTS: Analytical performances of the HPLC-MS/MS: CVs within and between-run variations were 5.6% and 2.6%; LOD and LOQ were 1.65 nmol/L and 3.30 nmol/L; mean recovery and relative accuracy were 96% and 97%. Creatinine level was higher in males than in females, but no gender difference in 8-oxodG level was observed. Upon the adjustment of 8-oxodG to creatinine (8-oxodG/creatinine), higher values were obtained in females (1.38 ± 0.65 nmol/mmol) than in males (1.05 ± 0.48 nmol/mmol). Distribution of 8-oxodG/creatinine in spot urine sample was log-normal and gender-related reference intervals (estimated as the 2.5th-97.5th percentiles) were 0.45-2.22 nmol/mmol for males, and 0.54-3.11 nmol/mmol for females. Body mass index (BMI) affects excretion of the 8-oxodG in males, independently of urinary creatinine, while in females it does not. Therefore, BMI might contribute to the gender-related differences of 8-oxodG/creatinine in spot urine samples. CONCLUSIONS: This is the first established gender-related reference intervals of spot urinary 8-oxodG/creatinine. Our results contribute to the full validation of 8-oxodG as biomarker of oxidative stress.

The oxidation of alkylaryl sulfides and benzo[b]thiophenes by Escherichia coli cells expressing wild-type and engineered styrene monooxygenase from Pseudomonas putida CA-3.

Nine different sulfur-containing compounds were biotransformed to the corresponding sulfoxides by Escherichia coli Bl21(DE3) cells expressing styrene monooxygenase (SMO) from Pseudomonas putida CA-3. Thioanisole was consumed at 83.3 µmoles min(-1) g cell dry weight(-1) resulting mainly in the formation of R-thioanisole sulfoxide with an enantiomeric excess (ee) value of 45 %. The rate of 2-methyl-, 2-chloro- and 2-bromo-thioanisole consumption was 2-fold lower than that of thioanisole. Surprisingly, the 2-methylthioanisole sulfoxide product had the opposite (S) configuration to that of the other 2-substituted thioanisole derivatives and had a higher ee value (84 %). The rate of oxidation of 4-substituted thioanisoles was higher than the corresponding 2-substituted substrates but the ee values of the products were consistently lower (10-23 %). The rate of benzo[b]thiophene and 2-methylbenzo[b]thiophene sulfoxidation was approximately 10-fold lower than that of thioanisole. The ee value of the benzo[b]thiophene sulfoxide could not be determined as the product racemized rapidly. E. coli cells expressing an engineered SMO (SMOeng R3-11) oxidised 2-substituted thioanisoles between 1.8- and 2.8-fold faster compared to cells expressing the wild-type enzyme. SMOeng R3-11 oxidised benzo[b]thiophene and 2-methylbenzo[b]thiophene 10.1 and 5.6 times faster that the wild-type enzyme. The stereospecificity of the reaction catalysed by SMOeng was unchanged from that of the wild type. Using the X-ray crystal structure of the P. putida S12 SMO, it was evident that the entrance of substrates into the SMO active site is limited by the binding pocket bottleneck formed by the side chains of Val-211 and Asn-46 carboxyamide group.

2-[2-(Trifluoro-meth-yl)phen-yl]-2H-1-benzopyran-4(3H)-one.

In the title compound, C(16)H(11)F(3)O(2), the γ-pyran-one ring adopts an envelope conformation with the chiral C atom standing out of the ring plane. In the crystal, molecules are linked by C-H⋯O and C-H⋯F inter-actions.

Crystal structure of the antitoxin-toxin protein complex RelB-RelE from Methanococcus jannaschii.

Here we present the crystal structure of the Methanococcus jannaschii RelE-RelB (RelBE) toxin-antitoxin (TA) protein complex determined by the MIRAS (multiple isomorphous replacement with anomalous signal) method. The genes encoding this TA system are located in the chromosome of this archaeon and involved in stress response. RelE acts as an endoribonuclease that cleaves mRNA on the ribosome, and we compare the RelBE complex to the known structures of other TA systems belonging to this group and to endoribonucleases. M. jannaschii RelBE forms a heterotetramer with the antitoxin in the centre of the complex, a configuration that differs vastly from the heterotetramer structure of the previously published RelBE from another archaeon, Pyrococcus horikoshii. The long N-terminal alpha-helix of the tightly bound M. jannaschii antitoxin RelB covers the presumed active site of the toxin RelE that is formed by a central beta-sheet, a loop on one side and a C-terminal alpha-helix on the other side. The active site of the M. jannaschii toxin RelE harbours positive charges that are thought to neutralize the negative charges of the substrate mRNA, including Arg62 that was changed to Ser62 by the Escherichia coli expression system, thereby leading to inactive toxin RelE. Comparative studies suggest that Asp43 and His79 are also involved in the activity of the toxin.