Seasonal variations in the levels of PAH-DNA adducts in young adults living in Mexico City.

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous components of polluted air. The Mexico City Metropolitan Area (MCMA), one of the most densely populated areas in the world, is 2240 m above sea level. At this altitude, less oxygen is available, making combustion less efficient and therefore producing more PAH pollutants. According to the Automatic Monitoring Network in Mexico City (RAMA, for its Spanish initials; http://www.sma.df.gob.mx/simat2/informaciontecnica/index.php?opcion=5&opciondifusion_bd=90), which performs environmental monitoring, the critical air pollutants in Mexico City are ozone and particulate matter (PM). PM emissions increase during the dry season (winter to spring) and decrease during the rainy season (summer to autumn). The bioactivation of some PAHs produces reactive metabolites that bind to DNA, and the presence of elevated levels of PAH-DNA adducts in tissues such as blood lymphocytes represents an elevated risk for the development of cancer. We have compared the levels of PAH-DNA adducts and the percentage of cells with chromosomal aberrations (CWAs) using a matched set of peripheral blood lymphocytes obtained on two separate occasions from young non-smoking inhabitants of the MCMA (n = 92) during the 2006 dry season and the following rainy season. PAH-DNA adducts were analysed using the r7, t8-dihydroxy-t-9, 10-oxy-7,8,9,10-tetrahydrobenzo[a]pyrene (BPDE)-DNA chemiluminescence immunoassay (CIA). The percentages of CWA were determined in cultured lymphocytes from the same individuals. Both DNA adduct levels and chromosomal aberrations were tested for correlation with lifestyle and the polymorphisms of cytochromes P450 CYP1A1 and CYP1B1 as well as glutathione-S-transferases GSTM1 and GSTT1. The levels of PAH-DNA adducts were significantly higher (P < 0.001) in the dry season (10.66 ± 3.05 per 10(9) nt, n = 92) than during the rainy season (9.50 ± 2.85 per 10(9) nt, n = 92) and correlated with the seasonal levels of particulate matter with a diameter of ≤ 10 µm (PM(10)). The percentage of CWA was not seasonally related; however, significant associations between the number of risk alleles and adduct levels in the dry (R = 0.298, P = 0.048) and in the wet seasons (R = 0.473, P = 0.001) were observed.

Assessment of SCAR markers to design real-time PCR primers for rhizosphere quantification of Azospirillum brasilense phytostimulatory inoculants of maize.

AIMS: To assess the applicability of sequence characterized amplified region (SCAR) markers obtained from BOX, ERIC and RAPD fragments to design primers for real-time PCR quantification of the phytostimulatory maize inoculants Azospirillum brasilense UAP-154 and CFN-535 in the rhizosphere. METHODS AND RESULTS: Primers were designed based on strain-specific SCAR markers and were screened for successful amplification of target strain and absence of cross-reaction with other Azospirillum strains. The specificity of primers thus selected was verified under real-time PCR conditions using genomic DNA from strain collection and DNA from rhizosphere samples. The detection limit was 60 fg DNA with pure cultures and 4 x 10(3) (for UAP-154) and 4 x 10(4) CFU g(-1) (for CFN-535) in the maize rhizosphere. Inoculant quantification was effective from 10(4) to 10(8) CFU g(-1) soil. CONCLUSION: BOX-based SCAR markers were useful to find primers for strain-specific real-time PCR quantification of each A. brasilense inoculant in the maize rhizosphere. SIGNIFICANCE AND IMPACT OF THE STUDY: Effective root colonization is a prerequisite for successful Azospirillum phytostimulation, but cultivation-independent monitoring methods were lacking. The real-time PCR methods developed here will help understand the effect of environmental conditions on root colonization and phytostimulation by A. brasilense UAP-154 and CFN-535.

(AAT)n repeat in the cannabinoid receptor gene (CNR1): association with cocaine addiction in an African-Caribbean population.

Owing to their agonist action on dopaminergic systems, cannabinoids may play a major role in substance dependency and schizophrenia. We examined the (AAT)n triplet repeat polymorphism nearby the CNR1 gene, which encodes human cannabinoid (CB1) receptor, in a male Afro-Caribbean population. The allelic and genotypic distributions were significantly different in non-schizophrenic cocaine dependents (n = 97), schizophrenic cocaine dependents (n = 45) and matched controls (n = 88) (P < 10(-4)). The frequency of the (AAT)12 repeat allele was increased in non-schizophrenic cocaine dependents and schizophrenic cocaine dependents vs controls (25.3 and 26.7 vs 5.7%) (P < 10(-4)). Our results support that the (AAT)n polymorphism nearby the CNR1 gene could be associated with predisposition to cocaine dependency.

Comparative efficacy of oral dexamethasone versus oral prednisone in acute pediatric asthma.

OBJECTIVE: The objective was to determine whether 2 days of oral dexamethasone (DEX) is more effective than 5 days of oral prednisone/prednisolone (PRED) in improving symptoms and preventing relapse in children with acute asthma. STUDY DESIGN: This was a prospective randomized trial of children (2 to 18 years old) who presented to the emergency department with acute asthma. PRED 2 mg/kg, maximum 60 mg (odd days) or DEX 0.6 mg/kg, maximum 16 mg (even days) was used. At discharge children in the PRED group were prescribed 4 daily doses (1 mg/kg/d, maximum 60 mg); children in the DEX group received a prepackaged dose (0.6 mg/kg, maximum 16 mg) to take the next day. The primary outcome was relapse within 10 days. RESULTS: When DEX was compared with PRED, relapse rates (7.4% of 272 vs 6.9% of 261), hospitalization rates from the emergency department (11% vs 12%) or after relapse (20% vs 17%), and symptom persistence at 10 days (22% vs 21%) were similar. In the PRED group more children were excluded for vomiting in the emergency department (3% vs 0.3%; P =.008), more parents were noncompliant (4% vs. 0.4%; P =.004), and more children missed > or =2 days of school (19.5% vs. 13.2%; P =.05). CONCLUSION: In children with acute asthma, 2 doses of dexamethasone provide similar efficacy with improved compliance and fewer side effects than 5 doses of prednisone.

DNA adduct formation during continuous feeding of 2-acetylaminofluorene at multiple concentrations.

A linear relationship was observed between the administered dose and DNA adduct levels in the livers and bladders of BALB/c mice fed the carcinogen, 2-acetylaminofluorene (2-AAF), continuously for one month. A similar linear correlation was found between the probit of the liver tumour incidence and the log of the liver DNA adduct levels; however, because there is a no-observable-effect level for bladder tumour induction, the relationship between the probit of the bladder tumour incidence and bladder DNA adduct levels was not linear. These data suggest that the relationship between DNA adduct formation and tumour incidence may be tissue specific.