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Bulgaria has a very high incidence of cardiometabolic diseases and air pollution-related mortality rate. This study investigated the relationship between daily air pollution levels and hospital admissions for ischaemic heart diseases (IHD), cerebral infarction (CI), and type 2 diabetes mellitus (T2DM) in Sofia, Bulgaria. We obtained daily data on hospitals admissions and daily average air pollution levels from 2009 to 2018. Pollutants of interest were particulate matter (PM2.5 and PM10), nitrogen dioxide (NO2), sulphur dioxide (SO2), ozone (O3), and carbon monoxide (CO). Negative binomial regressions were fitted to study the effects of air pollution on hospital admission over the course of seven days prior to that event, accounting for autocorrelations and time trend in the data, day of the week, temperature, and relative humidity. Our findings confirm that higher air pollution levels generally increase the risk of hospital admissions for IHD and CI. For T2DM the association is less clear. Admissions often lagged several days behind and were more common in specific demographic subgroups or when pollution crossed a particular threshold. However, we did not expect to find the risk of hospital admissions increased in warmer rather than colder months of the year. Our findings are to be taken with reservation but do provide an idea about how air pollution could trigger acute episodes of related cardiovascular diseases, and our model may serve to investigate similar associations across the country.

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The chemical interactions of two types of graphite and two types of carbon black (CB) with acetone, toluene, and phenol were studied in order to evaluate the influence of chemical treatment on the structure and morphology of the carbon phases. The experimental treatment of carbon phases was carried out at room temperature for 1 hour. The chemical and phase composition were studied by x-ray photoelectron (XP) and Raman spectroscopies, while the morphology and structure were determined by powder x-ray diffraction, as well as transmission electron microscopy techniques. To shed light on the most probable explanation of the observed results, we performed simulations and calculations of the binding energies of acetone, toluene, and phenol with model carbon phases: a perfect graphene sheet and a defective graphene sheet containing various structural defects (vacancies as well as zigzag and armchair edges). Simulations show that all non-covalent and most covalent coupling reactions are exothermic, with acetone coupling having the higher calorimetric effect. Based on the results of the simulations and the XP spectroscopy measurements, the probable reactions taking place during the respective treatments are outlined. The conducted studies (both theoretical and experimental) show that the treatment of graphite powders and CB with acetone, toluene, or phenol can be used as a preliminary stage of their modification and/or functionalization, including their conversion into graphene-like (defective graphene, reduced graphene oxide, and/or graphene oxide) phases. For example, the treatment of SPHERON 5000 with acetone significantly facilitates their subsequent modification with laser radiation to graphene-like phases.

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The interactions between Na+ or Mg2+ ions with different parts of single-stranded RNA molecules, namely, the oxygen atoms from the phosphate groups or the guanine base, in water solution have been studied using first-principles molecular dynamics. Sodium ions were found to be much more mobile than Mg2+ ions and readily underwent transitions between a state directly bonded to RNA oxygen atoms and a completely solvated state. The inner solvation shell of Na+ ions fluctuated stochastically at a femtosecond timescale coordinating on average 5 oxygen atoms for bonded Na+ ions and 5.5 oxygen atoms for solvated Na+ ions. In contrast, the inner solvation shell of Mg2+ ions was stable in both RNA-bonded and completely solvated states. In both cases, Mg2+ ions coordinated 6 oxygen atoms from the inner solvation shell. Consistent with their stable solvation shells, Mg2+ ions were more effective than Na+ ions in stabilizing the RNA backbone conformation. The exclusion zones between the first and second solvation shells, solvation shell widths, and angles for binding to carbonyl oxygen of guanine for solvated Na+ or Mg2+ ions exhibited a number of quantitative differences when compared with RNA crystallographic data. The presented results support the distinct capacity of Mg2+ ions to support the RNA structure not only in the crystal phase but also in the dynamic water environment both on the side of the phosphate moiety and on the side of the nucleobase.

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Alkaline and alkaline earth ions, namely Na+, K+, Mg2+ and Ca2+, are critical for the stability, proper folding and functioning of RNA. Moreover, those metal ions help to facilitate macromolecular interactions as well as the formation of supramolecular structures (e.g. the ribosome and the ribozymes). Therefore, identifying the interactions between ions and nucleic acids is a key to the better comprehension of the physical nature and biological functions of those biomolecules. The scope of this review is to highlight the preferential location and binding sites of alkaline and alkaline earth metal ions compensating the negatively charged backbone of nucleic acids and interacting with other electronegative centers, focusing on RNA. We summarize experimental studies from X-ray crystallography and spectroscopic analysis (infrared, Raman and NMR spectroscopies). Computational results obtained with classical and ab initio methods are presented afterwards.

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Chronic occupational exposure to benzene is associated with an increased risk of hematological malignancies such as acute myeloid leukemia (AML), but the underlying mechanisms are still unclear. The main objective of this study was to investigate the association between benzene exposure and DNA methylation, both in repeated elements and candidate genes, in a population of 158 Bulgarian petrochemical workers and 50 unexposed office workers. Exposure assessment included personal monitoring of airborne benzene at work and urinary biomarkers of benzene metabolism (S-phenylmercapturic acid [SPMA] and trans,trans-muconic acid [t,t-MA]) at the end of the work-shift. The median levels of airborne benzene, SPMA and t,t-MA in workers were 0.46 ppm, 15.5 µg/L and 711 µg/L respectively, and exposure levels were significantly lower in the controls. Repeated-element DNA methylation was measured in Alu and LINE-1, and gene-specific methylation in MAGE and p15. DNA methylation levels were not significantly different between exposed workers and controls (P>0.05). Both ordinary least squares (OLS) and beta-regression models were used to estimate benzene-methylation associations. Beta-regression showed better model specification, as reflected in improved coefficient of determination (pseudo R(2)) and Akaike's information criterion (AIC). In beta-regression, we found statistically significant reductions in LINE-1 (-0.15%, P<0.01) and p15 (-0.096%, P<0.01) mean methylation levels with each interquartile range (IQR) increase in SPMA. This study showed statistically significant but weak associations of LINE-1 and p15 hypomethylation with SPMA in Bulgarian petrochemical workers. We showed that beta-regression is more appropriate than OLS regression for fitting methylation data.

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UNLABELLED: The aim of this study was to elaborate a method for detection of specific IgG antibodies (Abs) to the haptenes p-benzoquinone (p-BQ) and hydroquinone (HQ) for assessment of specific humoral immune responses. Plasma and urine, collected from petrochemical plant workers have been analyzed. The workers were divided into three professional groups in ascending order of benzene exposure. The concentration of benzene in the air was determined by gas chromatography with mass-spectrometry and trans,trans-muconic acid (biomarker of benzene exposure) in urine-by liquid chromatography with UV-detection. Specific IgG Abs to haptenes p-BQ and HQ in plasma were determined with newly developed ELISA. The relationships "exposure-effect," revealed increased levels of specific IgG to haptens correlating with the benzene exposure. The "exposure-response" relationships demonstrated that workers with value of OD over X+2SD were 62% low exposure group, 68% in group with level of exposure on Threshold Limit Value (TLV) and 91% in the highest exposure group. The data obtained show that there is a good correlation between antibody production and the biomarker of exposure t,t-muconic acid. CONCLUSION: The newly developed method is applicable for assessment of specific humoral immune responses in workers exposed to benzene. There was a good correlation between benzene exposure and formation of antibodies against benzene metabolites.

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Antibodies against Mycobacterium tuberculosis antigenic glycolipids were determined by enzyme-linked immunosorbent assay (ELISA). The 720 sera were collected from adult patients under investigation, suspected with extrapulmonary tuberculosis. The test performance was estimated according to definitive diagnosis in terms of specificity, sensitivity, positive predictive value and negative predictive value. These parameters calculated on 142 sera from patients with extrapulmonary tuberculosis and on 578 sera from patients with different nontuberculosis diseases were 92%, 81.6%, 70.9% and 95.1%, respectively. The specificity decreased to 85% when tuberculosis was associated with cancer or hepatic cirrhosis. In reactivated tuberculosis the sensitivity and the positive predictive value were 86.9% and 83.3%, respectively. Our results showed that ELISA was conclusive for patients with active tuberculosis, before the initiation of the treatment. The sensitivity decreased to 30% in inactive forms. It was demonstrated that ELISA was positive in cases with negative microscopy genitourinary tuberculosis. ELISA could be used as a supporting test in the laboratory diagnosis of active extrapulmonary tuberculosis in adults, disregarding the site involved.

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During the past years, new diagnostic technologies based on DNA methods including PCR, were developed in the aid of tuberculosis control. Among several DNA sequences, an insertion sequence IS6110, found to be specific to mycobacteria belonging to M. tuberculosis complex were used. However, recent studies showed the absence of this IS6110 in 3-4% of M. tuberculosis strains isolated from patients of Vietnamese origin. In order to evaluate the frequency of IS6110 among a series of strains isolated in Romania, we have performed the PCR technique for amplification of 2 DNA specific regions of M. tuberculosis complex. The sequences of primers were as shown before (Guesdon et al., 1990). For this study, 219 strains have been isolated from tuberculous patients, in "Marius Nasta" Institute of Bucharest, Romania. We have shown that genomic DNA from 3.6% of 219 strains evaluated in our study do not contain the IS6110 sequence and could determine some identification problems when this molecular sequence is targeted.

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IgG antibodies against glycolipids and proteins isolated from M. tuberculosis and BCG suspension were determined by ELISA in sera, in CSFs and in serum and CSF paired samples, from patients with tuberculous meningitis and from healthy control subjects. With specificities between 90 and 94% for the antigens used, we obtained senitivities of 75% for Pr-ELISA, 60% for G1-ELISA and 35% for BCG-ELISA. As specific antibodies were detected in serum and CSFs, only one sample is enough to perform the test. We concluded that Pr-ELISA and G1-ELISA could be used as a supporting test in TBM diagnosis, especially when repeated bacteriological methods failed to prove the presence of tubercle bacilli and in cases without evidence of pulmonary tuberculosis.

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Antibodies against Mycobacterium tuberculosis glycolipids and whole BCG suspension were determined by ELISA on 58 sera from hospitalized patients with presumptive pulmonary tuberculosis and on 127 sera from control subjects. The experimental results demonstrated that the glycolipids are more adequate to be used as antigens than whole BCG suspension, as high sensitivity of the test was obtained. By using only one antigen, ELISA becomes more efficient in rapid diagnosis. ELISA with glycolipidic antigens should be used as a supporting test for direct smear examination in the diagnosis of pulmonary tuberculosis, especially in cases when repeated bacterial methods failed to prove the presence of M. tuberculosis.

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Red cell and leukocyte morphology and function have been examined in donor blood UV irradiated in a flow closed circulation. The studies have revealed that a single UV irradiation enhances red cell resistance to chemical hemolysis, helps them acquire normal shape; besides, it improves leukocytic functional activity, that manifests by enhanced phosphatase activity and augmentation of the granulocyte phagocytic activity.

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