Aflatoxins, hydroxylated metabolites, and aflatoxicol from breast muscle of laying hens.

Aflatoxins (AF) are toxic fungal secondary metabolites that are pathological to animals and humans. This study identified and quantified AF (AFB(1), AFB(2), AFG(1), AFG(2)) and their hydroxylated metabolites (AFM(1), AFM(2), AFP(1)) and aflatoxicol (AFL) from laying hen breast muscles. Aflatoxins pass from cereal feed to the laying hen tissues, causing economic losses, and from there to humans. To detect the passage of AF from feed to hen breast muscle tissues, an experiment that included 25 Hy-Line W36 121-wk-old hens was performed for 8 d. Hens in individual cages were distributed into 3 groups: a control group, with feed free of AFB(1), and 2 experimental groups, with feed spiked with 2 AFB(1) dosages: 30 µg·kg(-1) (low) or 500 µg·kg(-1) (high). The daily feed consumption per hen was recorded and afterward hens were euthanized and breast muscles were collected, weighed, and dried individually. Aflatoxins were extracted by 2 chemical methods and quantified by HPLC. Both methods were validated by lineality (calibration curves), recovery percentage (>80%), limit of detection, and limit of quantification. The AF (µg·kg(-1)) averages recovered in control breast muscles were as follows: AFB(1) (18); AFG(1), AFM(2), and AFL (0); AFG(2) (1.3); AFM(1) (52), and AFP1 (79). Hens fed with feed spiked with 30 µg·kg(-1) of AFB(1) had AFG(1) (16); AFG(2) (72); AFM(1) (0); AFM(2) (18); AFP(1) (145); and AFL (5 µg·kg(-1)). Hens with feed spiked with 500 µg·kg(-1) of AFB(1) had AFG(1) (512); AFG(2) (7); AFM(1) (4,775); AFM(2) (0); AFP(1) (661); and AFL (21 µg·kg(-1)). The best AF extraction method was Qian and Yang's method, modified by adding additional AF from both Supelclean LC18 SPE columns; its limit of detection (0.5 ng·mL(-1)) was lower compared with that of Koeltzow and Tanner, which was 1 ng·mL(-1).

Genetic susceptibility to lung cancer based on candidate genes in a sample from the Mexican Mestizo population: a case-control study.

BACKGROUND: Lung cancer (LC) is the leading cause of mortality caused by neoplasias worldwide. Although cigarette smoking is the primary cause, not all smokers develop LC. Polymorphic variations in genes associated with carcinogen metabolism, DNA repair, and cell-cycle dysregulation may alter an individual risk of developing LC. A polygenic cancer model was proposed, which considers genetic susceptibility to cancer is a global mechanism and suggests that it might be defined by the contributions of low-risk alleles in several candidate genes. This study focused on the analysis of 15 polymorphisms in 12 low-penetrance genes in a case-control study of a sample of Mexican Mestizo population. METHODS: A case-control study was performed with a total of 572 unrelated individuals, including 190 cases with a primary LC diagnosis and 382 healthy controls. The polymorphic status of the individuals was determined by TaqMan probe and RFLP techniques. The association between LC and genotype score (GS) was assessed by logistic regression. RESULTS: The results suggests a protective effect of the genotypes Arg/Lys of AhR rs2066853 (odds ratio [OR] 0.55, p = 0.03), Ile/Val of CYP1A1 rs1048943 (OR 0.49, p = 0.009), Tyr/His of EPHX1 rs1051740 (OR 0.53, p = 0.03), and A/A of CCND1 rs603965 (OR 0.44, p = 0.02). Analyses using the GS suggest that average cases have a larger number of risk alleles than controls (Student's t test -4.85, p = 0.001; OR 1.25, p < 0.001). CONCLUSIONS: Our results suggest significant differences between the GS for the cases and controls, which support the hypothesis underlying the additive and polygenic models for lung cancer risk depending on the polymorphisms in low-penetrance genes.

Effect of PM(10) and O(3) on infant mortality among residents in the Mexico City Metropolitan Area: a case-crossover analysis, 1997-2005.

INTRODUCTION: Consistent evidence has shown a positive association between air pollution and daily mortality among adults. Less is known about its effect on infant mortality and the modification of this association by socioeconomic status (SES). OBJECTIVE: To assess the association of particulate matter with an aerodynamic diameter of ≤10µm (PM(10)) and ozone (O(3)) on infant mortality and its modification by SES. METHODS: We evaluated the relationship of 24 h mean PM(10) and 1h daily maximum O(3) levels with 12 079 all-cause deaths (3903 respiratory deaths) among 1- to 11-month-old infants residing in the Mexico City Metropolitan Area between January 1997 and December 2005 using a case-crossover approach. The data were analysed using conditional logistic regression models, controlling for weather conditions and day of the week. RESULTS: Single-effect models showed, for all-cause mortality, increases of 5.5% (95% CI 1% to 10%) at lag1 and 6.6% (2% to 11.4%) at lag2; cumulative exposure models (0-2 days) showed an increase of 6.3% (0.01% to 32.7%). Respiratory mortality increased marginally at 5.3% (-0.02% to 13.2%) with a 1-day lag and 10% (2.1% to 18%) with a 2-day lag per increase of 38.7 µg/m(3) (IQR) in PM(10) levels. When data were stratified by SES (low, medium, and high), only infants with low and medium SES presented a significant increase in risk of all-cause mortality and respiratory mortality in relation to PM(10). O(3) was only significantly related to respiratory mortality in low SES. CONCLUSION: Our results suggest that in the Mexico City Metropolitan Area, infants with lower SES (low to medium) are at higher risk of mortality when exposed to ambient PM(10) and O(3).

Identification and quantification of aflatoxins and aflatoxicol from poultry feed and their recovery in poultry litter.

Aflatoxins (AF) are toxic fungal secondary metabolites and are known mycotoxins pathological to animals and humans. Poultry litter is frequently used as a food supplement for ruminants, and when poultry feed contains AF, the litter becomes contaminated as well, thus having an effect on livestock health. This study identified and quantified AF (AFB(1), AFB(2), AFG(1), and AFG(2)) from poultry feed and their recovery, together with their metabolites (AFM(1), AFM(2), AFP(1), and aflatoxicol) in litter. An experiment with 25 Hy-Line W-36 hens, in their second production stage, 121 wk old, was carried out. Hens were distributed in 3 groups placed in individual cages and 1 ration of 250 g of feed was given to each hen daily. Nine hens of the control group were fed with clean feed, without AFB(1); the other 2 experimental groups, with 8 hens each, were fed with 2 AFB(1) concentrations: 30 and 500 microg.kg(-1). The feed was replaced and weighed daily throughout a 7-d period to register the amount of feed consumed by the hens. Litter from each hen was collected, weighed, and dried individually. The chemical analysis of 40 g of each one of the 200 feed and 200 litter samples was chemically extracted and concentrated with immunoaffinity columns for total AF. To quantify AF, calibration curves for each AF were done by HPLC. Feed samples of the 3 groups presented significant difference with AFB(2) and AFG(2), whereas in litter samples, there were significant differences for AFG(2) in the 500 microg.kg(-1) group. Poultry litter had traces of AFM(1), AFM(2), AFP(1), and AFL with no significant differences among treatments. Aflatoxin B(1) prevalence in litter samples can cause damages in livestock because this mycotoxin reduces the digestibility of ruminant feed up to 67%.

Impact of Planting Dates and Climatic Factors on the Incidence and Severity of Sorghum Grain Mold in Morelos, Mexico.

It is difficult to develop control strategies for grain mold of sorghum because of the limited information on the epidemiology of grain mold in Mexico. The objectives of this study were to identify the fungi associated with grain mold in Morelos, Mexico, and to explore the relationship among planting dates, disease development, and relative humidity and temperature. Fusarium thapsinum was isolated from 97% of the grains from field samples of infested sorghum grains in Morelos, Mexico. The influence of planting dates on the development of sorghum grain mold was determined at Tlayca, Morelos, Mexico, during the rainy seasons of 1998, 1999, and 2000. Incidence of grain mold varied annually, but disease incidence and severity were highest in 1998. Planting dates from 1 June to 13 July had the highest incidence of grain mold during the 3 years. Throughout the study, disease severity was generally low, and yield was not affected. The late planting dates in 1999 and 2000 had reduced yields due to terminal drought of the crop. Increase of disease was predicted by mean temperature, but not by mean relative humidity.

Risk indicator of dust exposure and health effects in cement plant workers.

A frequent practical problem of research in developing countries is the lack of reliable records on occupational hazards. To improve this situation, this article suggests and evaluates a two-phase method for estimating particle exposure. The first phase uses the focal group, or homogeneous group, technique to reconstruct the production process and estimate the level of dust exposure. The second phase applies the technique of individual history of exposure to hazards at work, an index that accumulates current and previous exposure. This method was introduced in a Portland cement plant to assess the dust-exposure levels of workers and to evaluate its usefulness in the association between estimated exposure levels and the frequency of health effects--particularly respiratory effects--that occurred as a result of such exposures. The results obtained from the analysis of the production process and of the exposure levels determined by the cement workers showed that it is possible to reconstruct the history of exposure to cement dust during each worker's occupational history. The results also showed that estimated exposure is related to respiratory damage; higher exposure resulted in more serious diseases. This supports the usefulness of the suggested methodology.

[The interaction of the medical researcher with other scientists]. / Interacción del investigador médico con otros científicos.

A brief review of nonmedical scientists contributions to medicine is done. Information on morphology, physiology, biochemistry obtained with high technology has been increasingly used in the clinical work. Therefore broad knowledge and skills have turned to be necessary, though almost impossible to get by one person alone. The answer to this problem is the interdisciplinary team work on basic problems: diagnosis, prognosis, treatment, epidemiology, public health, management of health services, etc. By these work the physician must use models and "black boxes". Both concepts are reviewed. Some proposals to improve the relationships among physicians and other scientist are made.