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Background: Demyelinating diseases (DD) are a group of chronic neurological diseases associated with loss and injury of brain or spinal cord regions. These conditions could trigger impairment of neurological functions and disability from earlier stages of life. Epidemiological data on DD remains insufficient for decision-making in the Mexican healthcare system. This study aims to describe the epidemiology of DD based on data from Mexico's National Registry of Demyelinating Diseases., Methods: A cross-sectional, registry-based, observational study was performed. We analyzed 408 reports of multiple sclerosis (331, 81%), neuromyelitis optica spectrum disorder (67, 16%), chronic recurrent inflammatory optic neuropathy (5, 1%), clinically isolated syndrome (4, 0.9%), and autoimmune encephalitis (1, 0.2%) reported across 2021., Results: The time from first symptoms to diagnosis of any DD was about 3 years. A treatment failure history was detected in 40% of patients. It was estimated that NMOSD accounts for 20% of all disorders. There was evidence that the use of brand-name and generic IFN drug products lead to increased therapeutic failures., Conclusion: Our research team suggests reinforcing educational programs and activities based on diagnosis and clinical management improvement to first-contact physicians and specialty doctors and promoting awareness in the whole population., Competing Interests: Declaration of Competing Interest All authors wish to declare that have nothing to disclose. There are no competing interest(s) or conflict of interest that may be perceived to influence the results and discussion reported in this paper. All authors or their institutions did not receive payment or services from a third party (government, commercial, or private foundation) for any aspect of the submitted work at any time. The funding for the writing and editing process was carried out and supported by Unidad de Investigación en Salud (UIS). Each author filled and signed an electronic ICMJE form for disclosure of potential conflicts of interest and was responsible for the accuracy and completeness of the submitted information. If editors need to confirm this asseveration, the corresponding author may share this information separately. This document was designed to improve delivering of this information since all electronic ICMJE forms have the statement as “nothing to disclose”., (Copyright © 2023 Elsevier B.V. All rights reserved.)

The aim of this study was to determine the prevalence of musculoskeletal pain and rheumatic diseases in subjects over 18 years of age from the canton of Cuenca, Ecuador. Cross-sectional analytical community-based study was conducted in subjects over 18 years of age using the validated Community-Oriented Program for the Control of Rheumatic Diseases (COPCORD) questionnaire. Random sampling was used. The questionnaire was administered by standardized health workers. Subjects were visited house by house. Subjects positive for musculoskeletal (MSK) pain in the last 7 days and at some point in life were assessed by rheumatologists to confirm the diagnosis. A total of 4877 subjects participated, with an average age of 42.8 (SD 18.8) years of age; 59.7 % were women; 69.7 % lived in urban areas. 32.5 % reported MSK pain in the last 7 days and 45.7 % at some point in life. The prevalence of knee osteoarthritis was 7.4 %, hand osteoarthritis 5.3 %, low back pain 9.3 %, rheumatoid arthritis 0.8 %, fibromyalgia 2 %, gout 0.4 %, and lupus 0.06 %. Subjects from rural areas reported experiencing more MSK pain in the last 7 days and at some point in life, lower income, poorer health-care coverage, and increased physical activity involving repetitive tasks such as lifting weights or cooking with firewood. MSK pain prevalence was high. Osteoarthritis and low back pain were the most common diseases. Age, sex, physical activity, repetitive tasks, living in a rural area, and lack of health-care coverage were found to be associated with MSK pain.

Exposure among dentistry students has not been assessed or regulated in Mexico. This work assessed the average exposure of 35 dentistry students during their training with the aid of LiF:Mg,Cu,P+PTFE thermoluminescent dosimeters. For the students in the roles of dentist and observers, maximum accumulated equivalent dose obtained was 2.59±0.11 and 4.64±0.39 mSv, respectively. Students in the role as patients received a maximum accumulated effective dose of 28.41±0.31 mSv. If compared to occupational dose limits, this latter value is 56% of the recommended value of 50 mSv in any year. It was found that in all cases, values of equivalent dose to the women breasts were equal to the background dose. Results are discussed and compared to previous published work. Suggested recommendations were given to authorities in order to minimize exposure of the students in the role as patients., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

This study correlated lung cancer (LC) mortality with statistical data obtained from government public databases. In order to asses a relationship between LC deaths and radon accumulation in dwellings, indoor radon concentrations were measured with passive detectors randomly distributed in Chihuahua City. Kriging (K) and Inverse-Distance Weighting (IDW) spatial interpolations were carried out. Deaths were georeferenced and Moran's I correlation coefficients were calculated. The mean values (over n = 171) of the interpolation of radon concentrations of deceased's dwellings were 247.8 and 217.1 Bq/m(3), for K and IDW, respectively. Through the Moran's I values obtained, correspondingly equal to 0.56 and 0.61, it was evident that LC mortality was directly associated with locations with high levels of radon, considering a stable population for more than 25 years, suggesting spatial clustering of LC deaths due to indoor radon concentrations.

The objective of this study was to determine the 10th, 50th and 90th percentiles of birthweight, by gestational age and sex, for newborns covered by the Mexican Institute of Social Security (IMSS) in the State of Chihuahua. To generate the database, we used IMSS hospitals' records in the State of Chihuahua, covering the period between 1 January 2000 and 31 December 2004. We included singleton live births only, and excluded babies with congenital malformations. The birthweights of 88,368 children born at 21-44 weeks of gestation comprised our data. From these data, we calculated the 10th, 50th and 90th percentiles for each sex, at 32-44 weeks of gestation. The observed cutoffs for the 10th percentile in our population were 40-250 g higher than those reported in other references with Mexican populations. These results constitute an updated birthweight reference that will allow the identification of newborns in the North region of the country with low birthweight-for-gestational age. Such information can be a useful instrument for preventing or diminishing associated risks.

Introduction: Workers in floriculture are exposed to pesticides and other risk factors. Work in these occupational environments is suspected to be associated with adverse reproductive outcomes. However, epidemiological studies in Colombia, a country that has a long tradition with this occupation, have not been consistent or conclusive., Objective: To quantify the effect of womens work in Colombian floriculture in the occurrence of spontaneous abortion, prematurity, and birth defects, using the results of two previous studies., Material and Methods: The results of two previous studies among Colombian floriculture worker populations were summarized with metaanalysis techniques. A critical evaluation of each of the studies identified potential biases and methodological limitations., Results: The pooled estimator of spontaneous abortion was 2.24 (95CI: 1.87-2.68); that of premature infant birth was 1.49 (95%CI: 0.91-2.43), and of birth defects 1.31 (95%CI: 1.95-1.64)., Conclusions: The analyses suggested that work in floriculture is associated with a higher occurrence of spontaneous abortion and birth defects. However, these effects are not necessarily associated with pesticide exposure. Other risk factors requiring further study are levels of physical activity and high temperature in greenhouses. Data from countries which have initiated occupations in floriculture more recently will add valuable evidence for this controversial association.

Background: Studies suggest an association between obesity and asthma. This may be modified by the physiological changes of puberty. We aim to explore the relation between overweight and current asthma among Mexican adolescent females and young women and evaluate how puberty may modify this association., Methods: Adolescent females (n=6944) and young women aged 11-24 years provided data. Current asthma was defined as wheezing in the last 12 months and obesity by body mass index (BMI). Puberty was defined by age at menarche. The association of obesity and current wheezing was evaluated by using logistic regression adjusting for confounders. The impact of puberty was studied by using stratified analysis by age at menarche., Results: The prevalence of current wheezing was 16.2% (95% CI 15-17). Compared with girls of normal weight (BMI 15 to >or=85 percentile), obese girls (BMI>or=95 percentile) had an increased risk of current wheezing of 19% (OR=1.19; 95% CI 0.97-1.46). After stratifying by age at menarche, we observed that this increased risk was only present in girls with menarche at 11 years old or younger (1.31%; 95% CI 1.01-1.73)., Conclusions: The association between obesity and asthma seems to be greater among girls with early puberty, suggesting the role of female hormones.

Since the late 80's, time to pregnancy has been used in environmental epidemiology to explore adverse effects of different exposures. The advantages of this measure and additional elements to be considered in the performance of this type of studies are reviewed. Study design includes the following steps: population selection, sample size, outcome measurement, statistical analyses and sources of bias. Guidelines were suggested for the properly development of this type of study.

Objective: Lead poisoning can, in some cases, be traced to a specific route or source of exposure on the basis of the individual's blood lead isotope ratio. To assess the major source of lead exposure among women residing in Mexico City, we compared blood, ceramic, and gasoline lead isotope ratios., Material and Methods: The study population, randomly selected from participants of a large trial, (1/1996-12/1996) comprised of 16 women whose lead levels exceeded 10 micrograms/dl and who reported using lead-glazed ceramics. Lead isotope ratios were performed on a Perkin Elmer 5000 Inductively Coupled Plasma Mass Spectrometer (ICP-MS) interfaced with a Perkin Elmer HGA-600MS Electrothermal Vaporization System (ETV)., Results: The isotope ratios (206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb) of both the blood specimens and their corresponding ceramic specimens were highly correlated, with r = 0.9979, r2 = 0.9958, r = 0.9957, r2 = 0.9915 and r = 0.9945, r2 = 0.9890 values for the three isotope ratios, respectively, suggesting that the lead exposure most likely resulted from the use of these ceramic. Measurements of lead isotope ratios from leaded gasoline in use at the time of blood sampling, differed from those in blood and ceramics., Conclusions: Determining lead isotope ratios can be an efficient tool to identify a major source of lead exposure and to support the implementation of public health prevention and control measures. This paper is available too at: http://www.insp.mx/salud/index.html.

Introduction: Transfer of lead from bone to the bloodstream increases during lactation. However, the effect of maternal lead burden on growth in breastfed newborns is still unknown. This study examined early postnatal growth in a cohort of healthy breastfed newborns in relation to maternal bone lead burden., Methods: Lead levels were measured among 329 mother-infant pairs in umbilical cord blood at birth and in maternal and infant venous blood at 1 month postpartum. Maternal evaluations at 1 month postpartum included lead measures in blood and bone (measured in the tibia and the patella). Blood lead was determined by graphite furnace atomic absorption spectrophotometry. Bone lead was measured by (109)Cd Kx-radiograph fluorescence instrument. The primary endpoints were attained weight 1 month of age, and weight gain from birth to 1 month of age, which were analyzed in relation to lead biomarkers and relevant covariates by linear regression models., Results: Infants studied had an average weight gain of 33.1 g/day (standard deviation [SD] = 11.6). Mean infant (at 1 month of age) and maternal blood lead levels were 5.6 microg/dL (SD = 3.0) and 9.7 microg/dL (SD = 4.1), respectively. Mean maternal bone lead levels were 10.1 microg of lead/g (SD = 10.3) and 15.29 microg of lead/g (SD = 15.2) of bone mineral for tibia and patella, respectively. Infant blood lead levels were inversely associated with weight gain, with an estimated decline of 15.1 g per microg/dL of blood lead. Children who were exclusively breastfed had significantly higher weight gains; however, this gain decreased significantly with increasing levels of patella lead. The multivariate regression analysis predicted a 3.6-g decrease in weight at 1 month of age per microg of lead per gram bone mineral increase in maternal patella lead levels., Conclusions: Maternal lead burden is negatively associated to infant attained weight at 1 month of age and to postnatal weight gain from birth to 1 month of age. Additional studies are needed to better understand this source of exposure and to develop interventions to minimize its impact.

The adverse effects of lead have been known for long since the metal affects practically all organs and systems of the human body. Recently, toxic effects have been reported in the cardiovascular and nervous systems at lead levels previously considered to be secure. The main lead storage site in the body is bone. The toxicologic significance of this fact has been clarified only recently. The present study analyzes the role of lead as an endogenous source of exposure, as a chronic exposure biomarker and as a target organ. Recent advances to measure bone lead through fluorescent X-Rays are discussed. Additionally, the importance of bone lead from a public health perspective in places with a chronic history of exposure such as Mexico City, and in some occupational environments is reviewed with particular attention placed on reproductive age women, who are potential lead sources for the fetus and lactating infant.

Objective: To identify determinants of weight (BW) and length at birth (BL)., Material and Methods: We studied 481 mother-newborn pairs in three Mexico City hospitals. Multiple regression models were developed to identify statistically significant predictors of BW and BL with respect to a predetermined biological model. Independent variables included were: maternal anthropometry, age, smoking habits, and civil status, parental education, obstetric history, hypertension, and neonatal characteristics., Results: In the group with calf circumference (CC), height and head circumference below the median BW was 133, 92 and 96 g lower (+/- 35 standard error -SE-, p < 0.01) than the group above the median, adjusting for socioeconomic, obstetric history, and neonatal characteristics (NC). In the group below the median CC or height, BL was 5.8 or 6.2 mm (+/- 1.9 mm SE, p < 0.01) respectively, adjusting for obstetric history and NC., Conclusions: Results suggest that maternal anthropometry is the most important predictor of birth size and that predictors for BW and BL differ.

Objectives: Birth weight predicts infant survival, growth, and development. Previous research suggests that low levels of fetal lead exposure, as estimated by umbilical cord blood-lead levels at birth, may have an adverse effect on birth weight. This report examines the relationship of lead levels in cord blood and maternal bone to birth weight., Methods: Umbilical cord and maternal venous blood samples and anthropometric and sociodemographic data were obtained at delivery and 1-month postpartum. Blood-lead levels were analyzed by atomic absorption spectrophotometry. Maternal tibia and patella lead levels were determined at 1-month postpartum with use of a spot-source 109Cd K-X-ray fluorescence instrument. The relationship between birth weight and lead burden was evaluated by multiple regression with control of known determinants of size at birth., Results: Data on all variables of interest were obtained for 272 mother-infant pairs. After adjustment for other determinants of birth weight, tibia lead was the only lead biomarker clearly related to birth weight. The decline in birth weight associated to increments in tibia lead was nonlinear and accelerated at the highest tibia lead quartile. In the upper quartile, neonates were on average, 156 grams lighter than those in the lowest quartile. Other significant birth weight predictors included maternal nutritional status, parity, education, gestational age, and smoking during pregnancy., Conclusions: Our results indicate that bone-lead burden is inversely related to birth weight. Taken together with other research indicating that lead can mobilize from bone into plasma without detectable changes in whole blood lead, these findings suggest that bone lead might be a better biomarker than blood lead. Because lead remains in bone for years to decades, mobilization of bone lead during pregnancy may pose a significant fetal exposure with health consequences, long after maternal external lead exposure has declined.