Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

The first Covid-19 case was identified in Mexico in February 2020. Health authorities promoted non-pharmacological pre­vention measures to counteract the progress of the epidemic and, at the end of the year, they announced the application of the first vaccines in the country. Globally and locally, vaccines marked a milestone, positioning themselves as “magic bullets”; nevertheless, they faced several difficulties such as mass pro­duction, distribution logistics, variable effectiveness, phased implementation that prioritized vulnerable groups, rejection and low risk perception by certain groups in the population. The emphasis on population-based preventive measures or “social shields” was eventually diluted with the arrival of new vaccines. This essay highlights the importance of maintaining “social shields” as key preventive measures complementary to vaccines, since “magic bullets”, on their own, present chal­lenges that could compromise their effectiveness.  

Objective. To estimate the neuropsychological performance and its association with exposure to organic solvents (OS) among petrochemical workers in Mexico. Materials and methods. Cross-sectional study including 203 workers: 102 exposed to OS and 101 non-exposed. Neuropsychological performance was evaluated with Neurobehavioral Core Test Battery. Exposure to OS was evaluated with the metabolites from exposure to toluene, xylenes and benzene. Results. Exposed workers presented with a worse performance in all tests (p<0.05), except for Santa Ana test. This was corro­borated with regression models; workers exposed to OS had a higher number of mistakes and performed the tests in longer time (p<0.05), together with having greater odds of neurotoxicity symptoms (OR: 2.93; 95%CI: 0.96, 8.96). Con­clusions. Occupational exposure to organic solvents, even at levels allowed by current Mexican standards, was related to an impaired neuropsychological performance.

Objective. To estimate energy contribution (EC) of food groups in 2016, to compare consumption against Mexican Dietary Guidelines, and to examine changes in EC from 2012 to 2016. Materials and methods. We analyzed 24-hour dietary recalls from the 2012 and 2016 National Health and Nutrition Surveys (Ensanut). Foods and beverages were clas­sified into eight food groups: cereals, legumes, dairy, meats, fruit and vegetables, fats and oils, sugar-sweetened beverages, and high in saturated fat and added sugar (HSFAS) products. Results. Cereals had the highest EC (30.1%), followed by meats (15.9%), HSFAS products (15.5%), and SSBs (10.5%). Fruits and vegetables, and legumes had the lowest contribu­tion with 6.4 and 3.8%, respectively. SSBs, meats, and HSFAS products were 250, 59 and 55% above the recommended intake, respectively. Conclusions. This analysis confirms the need to generate a food environment conducive to a healthier diet.  

Objective. To describe the humoral response in a cohort with mild and asymptomatic SARS-CoV-2 infection previ­ously identified in a community-based serological survey. Materials and methods. This study was an observational follow up of 193 subjects previously identified with positive anti-SARS-CoV-2 antibodies invited for a second test 112 days after the first sampling. All completed a standardized electronic questionnaire. IgM/IgG antibodies were determined using a qualitative IgM/IgG chemiluminescent immunoassay. Results. Among the 193 eligible subjects, a total of 174 (90%) attended the follow-up visit, and their serum samples were tested. Of the samples, 171 (98.3%) were still positive, and 3 (1.7%) were negative. Also, the cut-off index (COI) value of the immunoassay significantly increased from the first to the second test (P <0.001). Conclusions. Our findings support a sustained humoral response in individuals with mild and asymptomatic SARS-CoV-2 infection up to 112 days after a positive serologic baseline test, accompanied by increasing antibody titers.

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The objective was to evaluate the carcass characteristics and fatty acid (FA) profile of the meat of Creole lambs supplemented with cottonseed (CS) and ground corn (GC). Twenty-four (24) males of 90 d and 16 ± 2 kg of initial weight were used. The lambs were assigned to four treatments, T0: grazing; T1: grazing + 25%-CS + 75%-GC; T2: grazing + 50%-CS + 50%-GC and T3: grazing + 75%-CS + 25%-GC, under a complete randomized design. After 127 d of supplementation, the animals were slaughtered, and the hot and cold carcass was weighed. Two hundred grams of the Longissimus dorsi muscle were taken to evaluate the proportion of FAs in each animal using gas chromatography. An analysis of variance was developed to determine the effect of diet. The supplemented animals had an average weight of 32.15 kg, being higher (P<0.05) than that registered by the lambs of the T0 (23.3 kg). Similarly, a higher average yield of the carcasses of lambs that received supplementation (48.2 vs 39.5 %) was observed. Palmitic and stearic FAs increased in the meat of supplemented animals (P≤0.05), especially in those fed the T2 diet. Supplementation with CS and GC positively altered (P≤0.05) the ratio of monounsaturated acids (MFAs) and polyunsaturated acids (PFAs). The treatments did not influence (P>0.05) the MFA:SFA ratio and the atherogenicity index. However, the diet affected (P<0.05) the desirable PFA:SFA and FA ratio. Supplementation with CS and GC positively influenced slaughter weight, carcass yield and fatty acid profile in lambs.

El objetivo fue determinar el efecto de la edad al primer parto sobre la longevidad, el número de días productivos y la producción de leche durante toda la vida de las vacas Holstein y Pardo Suizo en la sabana tropical de Honduras. La información se recolectó de tres granjas lecheras con vacas Holstein (n= 1,391) y cuatro granjas con vacas Pardo Suizo (n= 480), nacidas entre 1993 y 2013, manejadas bajo sistemas intensivos. El modelo estadístico que describió las variables de interés incluyó el efecto de la granja, el grupo de edad al primer parto, el período de nacimiento, la estación de nacimiento y la interacción granja x período y el error residual. Se encontraron efectos de la granja, período, el grupo de edad al primer parto y la interacción granja x período en las variables de respuesta. Un efecto favorable de las vacas que tuvieron su primer parto a una edad más temprana en el número de días de producción y la producción de leche durante toda la vida, y un aumento en la longevidad, tanto en vacas Holstein como en vacas Pardo Suizo (P<0.05). En conclusión, las vacas que parieron a una edad temprana tuvieron más días productivos en la granja y produjeron más leche durante su vida productiva. Por lo tanto, hacer que las novillas paran a una edad temprana podría ser una estrategia de manejo para aumentar la productividad en la granja. Sin embargo, se debe tener en cuenta el peso al primer parto y los aspectos fisiológicos del animal.

Salmonella is a pathogenic bacterium considered a threat to the food industry, its timely detection being relevant. The objective of the study was to evaluate the real-time polymerase chain reaction coupled to immunomagnetic separation (rtPCR-IMS) as an alternative method to the Official Mexican Standard (NOM-114-SSA1-1994) for the detection of Salmonella in beef. The parameters evaluated were limit of detection, sensitivity, specificity, selectivity (inclusivity and exclusivity) and degree of agreement between both methods for the detection of Salmonella in presumptive and artificially contaminated beef samples. The incidence of Salmonella in presumptive beef samples (n= 60) ranged from 20.0 to 21.6 % by both methods. In the inoculated samples (n= 60), the detection rate of Salmonella by rtPCR-IMS (93.3 %) and NOM-114-SSA1-1994 (98.3 %) showed a match of 56 occasions with a negative deviation. The comparison of rtPCR-IMS and NOM-114-SSA1-1994 in beef reported an accuracy of 98.3 %, sensitivity of 98.2 %, specificity of 100 % and selectivity of 100 %. The limit of detection for both methods was 1-5 CFU·25 g-1 of beef. The statistical analysis indicates that the rtPCR-IMS is equivalent to the reference method for the detection of Salmonella in beef. These results warn of the high incidence of Salmonella in beef and propose rtPCR-IMS as an ideal and fast method for the control of Salmonella in the meat industry.