Night Shift Work and Risk of Breast Cancer in Women.

BACKGROUND: Night shift work involving circadian disruption has been associated with increased breast cancer rates in some epidemiological studies, but the evidence is still on debate. AIM OF THE STUDY: The objective of this study is to assess the association between night shift work and breast cancer in Mexican women. METHODS: A Case-control study was conducted with incident cases of breast cancer at the Instituto de Seguridad Social del Estado de México y Municipios. Cases were interviewed about past exposures prior to the final diagnosis. Controls were women without breast cancer matched on multiple sociodemographic characteristics. RESULTS: 101 cases and 101 matched controls were interviewed; this small sample size provided consistent, but wide estimates of the assessed associations. The multivariate conditional logistic regression showed that breast-feeding was associated with reduced risk for breast cancer (OR 0.12; 95% CI: 0.02-0.60); women who experienced early menarche (12 years) were more likely to develop breast cancer (OR 18.58; 95% CI 18: 2.19-148). Women who worked at night were more likely to develop breast cancer compared to women who never did (OR = 8.58; 95% CI: 2.19-33.8). CONCLUSIONS: Our results are consistent with studies from other countries, which positively associated night shift work with breast cancer.

[Prevalencia de complicaciones de la diabetes y comorbilidades asociadas en medicina familiar del Instituto Mexicano del Seguro Social].

Introduction: The prevalence of chronic complications and comorbidities in patients with type 2 diabetes (T2D) has increased worldwide. Objective: To compare the prevalence of complications and chronic comorbidities in patients with T2D at 36 family medicine units of five chapters of the Mexican Institute of Social Security (IMSS). Method: Complications (hypoglycemia, diabetic foot, kidney disease, retinopathy, ischemic heart disease, cerebrovascular disease and heart failure) and comorbidities (liver disease, cancer and anemia) were identified according to codes of the International Classification of Diseases, 10th Revision. Comparisons were made by chapter, age, gender and evolution time. Results: Complications and comorbidities were more common in subjects aged ≥ 62 years. Out of 297 100 patients, 34.9 % had any complication; microvascular complications (32 %) prevailed in the industrial North, whereas macrovascular complications (12.3 %) did in the rural East, and comorbidities (5 %) in southern Mexico City. Complications predominated in men (any complication, 30.2 %). Heart failure and comorbidities were more common in women (5.6 % and 4.9 %, respectively). Conclusions: T2D complications and comorbidities showed geographic and gender differences, and were greater with older age and longer evolution time. It is urgent for strategies for the prevention of complications and comorbidities to be reinforced in patients with T2D.

Introducción: La prevalencia de complicaciones crónicas y comorbilidades en pacientes con diabetes tipo 2 (DT2) se han incrementado en el mundo. Objetivo: Comparar la prevalencia de complicaciones y comorbilidades crónicas en pacientes con DT2 en 36 unidades de medicina familiar de cinco delegaciones del Instituto Mexicano del Seguro Social (IMSS). Métodos: Conforme los códigos de la Décima Revisión de la Clasificación Internacional de Enfermedades se identificaron las complicaciones (hipoglucemia, pie diabético, enfermedad renal, retinopatía, enfermedad cardiaca isquémica, enfermedad cerebrovascular y falla cardiaca) y comorbilidades (enfermedad hepática, cáncer, anemia) de DT2. Se compararon por delegación, edad, sexo y tiempo de evolución. Resultados: Las complicaciones y comorbilidades fueron más comunes en personas ≥ 62 años. De 297 100 pacientes, 34.9 % presentó cualquier complicación; microvasculares en el norte industrial (32 %), macrovasculares en el este rural (12.3 %) y comorbilidades (5 %) en el sur de la Ciudad de México; estas complicaciones predominaron en los hombres (cualquier complicación 30.2 %). La falla cardiaca y las comorbilidades fueron más comunes en mujeres (5.6 y 4.9 %). Conclusiones: Las complicaciones y comorbilidades de DT2 mostraron diferencias geográficas y de sexo y fueron mayores con la edad y el tiempo de evolución. Urge reforzar estrategias para la prevención de las complicaciones y comorbilidades en los pacientes con DT2.

Prevalencia de complicaciones de la diabetes y comorbilidades asociadas en medicina familiar del Instituto Mexicano del Seguro Social / Prevalence of complications of diabetes and associated comorbidities in family medicine of the Mexican Institute

Resumen Introducción: La prevalencia de complicaciones crónicas y comorbilidades en pacientes con diabetes tipo 2 (DT2) se han incrementado en el mundo. Objetivo: Comparar la prevalencia de complicaciones y comorbilidades crónicas en pacientes con DT2 en 36 unidades de medicina familiar de cinco delegaciones del Instituto Mexicano del Seguro Social (IMSS). Métodos: Conforme los códigos de la Décima Revisión de la Clasificación Internacional de Enfermedades se identificaron las complicaciones (hipoglucemia, pie diabético, enfermedad renal, retinopatía, enfermedad cardiaca isquémica, enfermedad cerebrovascular y falla cardiaca) y comorbilidades (enfermedad hepática, cáncer, anemia) de DT2. Se compararon por delegación, edad, sexo y tiempo de evolución. Resultados: Las complicaciones y comorbilidades fueron más comunes en personas ≥ 62 años. De 297 100 pacientes, 34.9 % presentó cualquier complicación; microvasculares en el norte industrial (32 %), macrovasculares en el este rural (12.3 %) y comorbilidades (5 %) en el sur de la Ciudad de México; estas complicaciones predominaron en los hombres (cualquier complicación 30.2 %). La falla cardiaca y las comorbilidades fueron más comunes en mujeres (5.6 y 4.9 %). Conclusiones: Las complicaciones y comorbilidades de DT2 mostraron diferencias geográficas y de sexo y fueron mayores con la edad y el tiempo de evolución. Urge reforzar estrategias para la prevención de las complicaciones y comorbilidades en los pacientes con DT2.

Abstract Introduction: The prevalence of chronic complications and comorbidities in patients with type 2 diabetes (T2D) has increased worldwide. Objective: To compare the prevalence of complications and chronic comorbidities in patients with T2D at 36 family medicine units of five chapters of the Mexican Institute of Social Security (IMSS). Method: Complications (hypoglycemia, diabetic foot, kidney disease, retinopathy, ischemic heart disease, cerebrovascular disease and heart failure) and comorbidities (liver disease, cancer and anemia) were identified according to codes of the International Classification of Diseases, 10th Revision. Comparisons were made by chapter, age, gender and evolution time. Results: Complications and comorbidities were more common in subjects aged ≥ 62 years. Out of 297 100 patients, 34.9 % had any complication; microvascular complications (32 %) prevailed in the industrial North, whereas macrovascular complications (12.3 %) did in the rural East, and comorbidities (5 %) in southern Mexico City. Complications predominated in men (any complication, 30.2 %). Heart failure and comorbidities were more common in women (5.6 % and 4.9 %, respectively). Conclusions: T2D complications and comorbidities showed geographic and gender differences, and were greater with older age and longer evolution time. It is urgent for strategies for the prevention of complications and comorbidities to be reinforced in patients with T2D.

Evaluation of the impact on non-communicable chronic diseases of a major integrated primary health care program in Mexico.

BACKGROUND: Primary health care is the best framework for implementing actions for the prevention and control of non-communicable diseases at an appropriate scale. In 2002, the Mexican Institute for Social Security (IMSS), which provides health care to half of the Mexican population, implemented a primary care-based integrated program that included the improvement of the family health care practice and a preventive strategy called PREVENIMSS, to reduce the burden of disease. OBJECTIVE: To asess the impact of this program on selected non-communicable chronic diseases. METHODS: Morbidity and mortality were compared before and after implementation of the program and time trends in IMSS affiliates and non-affiliates using the difference-in-differences (DD) method. RESULTS: Incidence rates of diabetes and hypertension increased whereas those of cervical cancer, breast cancer and other cerebrovascular diseases decreased from 2000 to 2013. The DD in mortality rates, expressed per 100000 persons, showed a decrease of 49.4 for diabetes mellitus, 9.1 for hypertensive disease, 42.9 for ischemic heart disease, 17.4 for cerebrovascular disease, 7.5 for cervical cancer and 5.8 for breast cancer. CONCLUSIONS: The reductions in mortality rates could be explained by both changes in incidence rates and changes in case fatality rates associated with early detection and treatment. These initial findings can be interpreted as the potential impact of integrated programs based on primary health care in a developing country.

Association of AS3MT polymorphisms and the risk of premalignant arsenic skin lesions.

Exposure to naturally occurring inorganic arsenic (iAs), primarily from contaminated drinking water, is considered one of the top environmental health threats worldwide. Arsenic (+3 oxidation state) methyltransferase (AS3MT) is the key enzyme in the biotransformation pathway of iAs. AS3MT catalyzes the transfer of a methyl group from S-adenosyl-L-methionine to trivalent arsenicals, resulting in the production of methylated (MAs) and dimethylated arsenicals (DMAs). MAs is a susceptibility factor for iAs-induced toxicity. In this study, we evaluated the association of the polymorphism in AS3MT gene with iAs metabolism and with the presence of arsenic (As) premalignant skin lesions. This is a case-control study of 71 cases with skin lesions and 51 controls without skin lesions recruited from a iAs endemic area in Mexico. We measured urinary As metabolites, differentiating the trivalent and pentavalent arsenical species, using the hydride generation atomic absorption spectrometry. In addition, the study subjects were genotyped to analyze three single nucleotide polymorphisms (SNPs), A-477G, T14458C (nonsynonymus SNP; Met287Thr), and T35587C, in the AS3MT gene. We compared the frequencies of the AS3MT alleles, genotypes, and haplotypes in individuals with and without skin lesions. Marginal differences in the frequencies of the Met287Thr genotype were identified between individuals with and without premalignant skin lesions (p=0.055): individuals carrying the C (TC+CC) allele (Thr) were at risk [odds ratio=4.28; 95% confidence interval (1.0-18.5)]. Also, individuals with C allele of Met287Thr displayed greater percentage of MAs in urine and decrease in the percentage of DMAs. These findings indicate that Met287Thr influences the susceptibility to premalignant As skin lesions and might be at increased risk for other adverse health effects of iAs exposure.

Chronic arsenic exposure increases TGFalpha concentration in bladder urothelial cells of Mexican populations environmentally exposed to inorganic arsenic.

Inorganic arsenic (iAs) is a well-established carcinogen and human exposure has been associated with a variety of cancers including those of skin, lung, and bladder. High expression of transforming growth factor alpha (TGF-alpha) has associated with local relapses in early stages of urinary bladder cancer. iAs exposures are at least in part determined by the rate of formation and composition of iAs metabolites (MAs(III), MAs(V), DMAs(III), DMAs(V)). This study examines the relationship between TGF-alpha concentration in exfoliated bladder urothelial cells (BUC) separated from urine and urinary arsenic species in 72 resident women (18-51 years old) from areas exposed to different concentrations of iAs in drinking water (2-378 ppb) in central Mexico. Urinary arsenic species, including trivalent methylated metabolites were measured by hydride generation atomic absorption spectrometry method. The concentration of TGF-alpha in BUC was measured using an ELISA assay. Results show a statistically significant positive correlation between TGF-alpha concentration in BUC and each of the six arsenic species present in urine. The multivariate linear regression analyses show that the increment of TGF-alpha levels in BUC was importantly associated with the presence of arsenic species after adjusting by age, and presence of urinary infection. People from areas with high arsenic exposure had a significantly higher TGF-alpha concentration in BUC than people from areas of low arsenic exposure (128.8 vs. 64.4 pg/mg protein; p<0.05). Notably, exfoliated cells isolated from individuals with skin lesions contained significantly greater amount of TGF-alpha than cells from individuals without skin lesions: 157.7 vs. 64.9 pg/mg protein (p=0.003). These results suggest that TGF-alpha in exfoliated BUC may serve as a susceptibility marker of adverse health effects on epithelial tissue in arsenic-endemic areas.

Urinary trivalent methylated arsenic species in a population chronically exposed to inorganic arsenic.

Chronic exposure to inorganic arsenic (iAs) has been associated with increased risk of various forms of cancer and of noncancerous diseases. Metabolic conversions of iAs that yield highly toxic and genotoxic methylarsonite (MAsIII) and dimethylarsinite (DMAsIII) may play a significant role in determining the extent and character of toxic and cancer-promoting effects of iAs exposure. In this study we examined the relationship between urinary profiles of MAsIII and DMAsIII and skin lesion markers of iAs toxicity in individuals exposed to iAs in drinking water. The study subjects were recruited among the residents of an endemic region of central Mexico. Drinking-water reservoirs in this region are heavily contaminated with iAs. Previous studies carried out in the local populations have found an increased incidence of pathologies, primarily skin lesions, that are characteristic of arseniasis. The goal of this study was to investigate the urinary profiles for the trivalent and pentavalent As metabolites in both high- and low-iAs-exposed subjects. Notably, methylated trivalent arsenicals were detected in 98% of analyzed urine samples. On average, the major metabolite, DMAsIII, represented 49% of total urinary As, followed by DMAsV (23.7%), iAsV (8.6%), iAsIII (8.5%), MAsIII (7.4%), and MAsV (2.8%). More important, the average MAsIII concentration was significantly higher in the urine of exposed individuals with skin lesions compared with those who drank iAs-contaminated water but had no skin lesions. These data suggest that urinary levels of MAsIII, the most toxic species among identified metabolites of iAs, may serve as an indicator to identify individuals with increased susceptibility to toxic and cancer-promoting effects of arseniasis.

Arsenic exposure and human papillomavirus response in non-melanoma skin cancer Mexican patients: a pilot study.

We assessed the relationships between chronic arsenic (As) exposure, human papilloma virus (HPV) contact and non-melanoma skin cancer (NMSC) by means of a dermatology clinic-based case-control study (42 cases and 48 controls) in Region Lagunera, Mexico, where chronic As poisoning is endemic. Exposure was determined through detailed history of residence in the As-contaminated area and measurement of As levels in drinking water and urine. We used a consensus epitope from the central region of L1 protein of the HPV family to determine antibodies against HPV. A history of As exposure and HPV seropositivity were associated with increased NMSC risks. A history of exposure to high levels of As increased the risk for NMSC (OR = 4.53; P = 0.11) in the group of seronegative HPV patients. A positive response to HPV significantly increased the OR for NMSC to 9.04 (P = 0.01) when history showed exposure to low levels of As. Interestingly, the OR was significantly increased to 16.5 (P = 0.001) when both exposure to high levels of As and HPV seropositivity were present. In addition, the presence of NMSC increased the OR (5.45; P = 0.03) for a positive response to HPV when history showed exposure to low levels of As, but the OR was increased to 8.0 (P = 0.005) in the cases with high exposure levels. Thus, HPV infection could constitute an additional risk factor for NMSC development in humans chronically exposed to As. However, further studies with additional populations are needed to determine the interaction between HPV and As exposure in NMSC.

Reproductive effects of occupational DDT exposure among male malaria control workers.

To assess potential effects of human DDT [1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane] exposure, we evaluated the reproductive history of 2,033 workers in the antimalaria campaign of Mexico. Data on occupational exposure to DDT and reproductive outcomes were gathered through a questionnaire, and workers provided information about 9,187 pregnancies. We estimated paternal exposure to DDT before each pregnancy using three approaches: a) a dichotomous indicator for pregnancies before and after exposure began, b) a qualitative index of four exposure categories, and c) an estimation of the DDT metabolite DDE [1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene] accumulated in fat. To assess associations, we used logistic regression models that accounted for correlated observations and adjusted for parents' age at each child's birth, exposure to other pesticides, exposure to chemical substances in other employment, smoking, and alcohol consumption. The odds ratio for birth defects comparing pregnancies after and before the first exposure was 3.77 [95% confidence interval (95% CI), 1.19-9.52]. Compared with the lowest quartile of estimated DDE in fat, the ORs were 2.48 (95% CI, 0.75-8.11), 4.15 (95% CI, 1.38-12.46), and 3.76 (95% CI, 1.23-11.44) for quartiles 2, 3, and 4, equivalent to p,p -DDE in fat of 50, 82, and 298 microg/g fat, respectively. No significant association was found for spontaneous abortion or sex ratio. We found an increased risk of birth defects associated with high occupational exposure to DDT in this group of workers. The significance of this association at lower exposure levels found in the general population remains uncertain.

DDT induces DNA damage in blood cells. Studies in vitro and in women chronically exposed to this insecticide.

In this study, DDT-induced DNA damage on blood cells was analyzed both in vitro and in vivo. Peripheral blood mononuclear cells (PBMC) were isolated from healthy donors and incubated in the presence of three different concentrations (40, 80, and 100 microg/mL) of p,p'-DDT, p,p'-DDE, and p,p'-DDD at three different treatment times (24, 48, and 72 h). Then, DNA damage was assessed by the single-cell electrophoresis assay (comet assay) as well as by flow cytometry detection of hypodiploid cells (DNA content assay). All compounds induced significant DNA damage as shown by the comet assay. Accordingly, cells exposed to DDT, DDE, and DDD showed a significant increase in the percentage of hypodiploid cells compared with untreated PBMC. In agreement with the in vitro data, a significant correlation between blood levels of DDT, DDD, and DDE and DNA damage (comet assay) was found in women with different amounts of environmental exposure. This association remained significant after controlling for nutritional status, smoking habits, alcohol ingestion, and reported exposure to other pesticides. Although the precise biological importance remains to be explained, our results strongly suggest that DDT and its metabolites are able to induce DNA damage in PBMC both in vitro and in vivo.

Fluoride-induced disruption of reproductive hormones in men.

Fluoride-induced reproductive effects have been reported in experimental models and in humans. However, these effects were found in heavily exposed scenarios. Therefore, in this work our objective was to study reproductive parameters in a population exposed to fluoride at doses of 3-27 mg/day (high-fluoride-exposed group-HFEG). Urinary fluoride levels, semen parameters, and reproductive hormones in serum (LH, FSH, estradiol, prolactin, inhibin-B, free and total testosterone) were measured. Results were compared with a group of individuals exposed to fluoride at lower doses: 2-13 mg/day (low-fluoride-exposed group-LFEG). A significant increase in FSH (P<0.05) and a reduction of inhibin-B, free testosterone, and prolactin in serum (P<0.05) were noticed in the HFEG. When HFEG was compared to LFEG, a decreased sensitivity was found in the FSH response to inhibin-B (P<0.05). A significant negative partial correlation was observed between urinary fluoride and serum levels of inhibin-B (r=-0.333, P=0.028) in LFEG. Furthermore, a significant partial correlation was observed between a chronic exposure index for fluoride and the serum concentrations of inhibin-B (r=-0.163, P=0.037) in HFEG. No abnormalities were found in the semen parameters studied in the present work, neither in the HFEG, nor in the LFEG. The results obtained indicate that a fluoride exposure of 3-27 mg/day induces a subclinical reproductive effect that can be explained by a fluoride-induced toxic effect in both Sertoli cells and gonadotrophs.

Los efectos agudos de la contaminación del aire en la salud de la población: evidencias de estudios epidemiológicos / Acute effect of air pollution on health: Evidence from epidemiological studies

Objetivo. Sintetizar las evidencias de los efectos en la salud de la población por la exposición a contaminación del aire por ozono y partículas suspendidas. Material y métodos. A partir de las principales publicaciones internacionales y mexicanas, publicadas y referidas hasta junio del año 2000, se realizó un metanálisis para resumir los efectos reportados a través del empleo de modelos de efectos aleatorios. Resultados. Los resultados se expresaron como porcentajes de incremento por 10 unidades de concentración de PM10 (µg/m3) y ozono (ppb). Entre los efectos de PM10 cabe destacar el efecto agudo en la mortalidad (0.96 por ciento), hospitalizaciones (1.39 por ciento), visitas a salas de urgencias (3.11 por ciento), síntomas respiratorios (7.72 por ciento), parámetros de función pulmonar (1.42 por ciento), para capacidad vital forzada (CVF) y días de actividad restringida (7.74 por ciento). Los efectos de la exposición a ozono son igualmente significativos. Conclusiones. Estos resultados muestran el gran impacto que las concentraciones de contaminantes del aire podrían tener en la salud de las poblaciones urbanas de las grandes metrópolis. El texto completo en inglés de este artículo está disponible en: http://www.insp.mx/salud/index.html

Efectos de la aplicación del indicador de años de vida productivos perdidos (modelo inversion producción consumo) en el ordenamiento de las causas de muerte en México, 1990 / The effects of the application of the investment-production-consumption model of the years of productive life host index on the sequence of causes of death in Mexico

Com a intençäo de apoiar a tomada de decisöes e melhorar o benefício, ao priorizar necessidades, discute o modelo de inversäo-produçäo-consumo (IPC), o qual tenta medir o impacto socioeconômico da mortalidade. Esse tipo de avaliaçäo toma em conta a idade ao morrer e a futura produtividade potencial, gerando perdas ou ganhos à sociedade, dependendo da etapa da vida quando ocorreu a morte. Ilustra para o México o impacto das diferentes causas de morte e compara com a importância relativa, partindo da ordenaçäo com as taxas da mortalidade e o indicador de anos de vida perdidos (IVAPP). Ao ordenar por taxas, observa que as doenças do coraçäo, acidentes e tumores säo as primeiras causas. Entretanto, o tradicional indicador de anos de vida potencialmente perdidos demonstra que estäo em primeiro lugar as causas de morte em idades menores. O IAVPPipc entretanto, dá maior importância às infecçöes, aos acidentes e aos homicídios, partindo do ponto de vista da produçäo e consumo

El análisis de la desnutrición como causa múltiple de muerte / Malnutrition as a cause of death

Con el objeto de describir la frecuencia de la desnutricón como causa múltiple de muerte, se realizó un análisis de los certificados de defunción de los niños menores de cinco años que fallecieron en los meses de abril y mayo de 1985 en el Distrito Federal, México. Mediante un diseño de mortalidad proporcional e incluyendo todas las causas listadas en el certificado de defunción, se estudió la asociación entre desnutrición e infección. Se encontró que la frecuencia de la enfermedad infecciosa como causa básica de muerte fue casi ocho veces mayor cuando coexistió la desnutrición como causa múltiple que cuando no se reportó como tal, resultando estadísticamente significativa la diferencia (RM = 7.9, IC 95 por ciento 5.0 - 12.7, p = 0.00000). Se discute la relevancia de estudiar otras causas consignadas en el certificado de defunción, principalmente aquellas que son frecuentes entre la población pero que no se registran comúnmente como causa básica de muerte

With the purpose of describing the role of malnutrition at death time, an analysis of multiple causes of death in children under five years-old was performed on deaths which ocurred during April and May 1985 in Mexico City. A proportional mortality analysis was done taking in consideration all the causes listed on the death certificate, not only the underlying causes. The number of deaths associated to malnutrition was greater by multiple cause than by underlying cause (OR = 7.9, 95% CI 5.0 - 12.7, p = 0.00000). The importance of considering multiple causes of death, mainly when there are frequent diseases which are some times recorded as underlying cause of death, is also discussed.