Background: Depression is one of the most prevalent mental health disorders worldwide, affecting a significant proportion of the global population. Its etiology is complex and influenced by the interaction of environmental factors and genetic variations. In Mexico, it has been reported that 41.3% of the population exhibits depressive symptoms. Previous studies have suggested that susceptibility to depression may be associated with the C-1019G (rs6295) polymorphism in the serotonin 1A (5-HT1A) receptor gene. Objective: In this study, we aimed to evaluate the association between the C-1019G polymorphism and depressive symptoms in a rural Mexican population. Methods: Using polymerase chain reaction–restriction fragment length polymorphism (PCR-RFLP), we examined the effect of C-1019G on depression symptoms, as evaluated by the Beck Depression Inventory. Data were obtained from 83 volunteers; individuals with depressive symptoms and those with a healthy mood were compared. Results: The results showed that the homozygous C/C genotype was found significantly more frequently in the control group than in individuals with depressive symptoms, particularly among men, and is thus associated with a decreased risk of depressive symptomatology. Conclusions: The C/C genotype could protect against susceptibility to developing depressive symptoms in a rural population in Mexico.

In this study, 104 purified water samples were collected from vending machines in the three main cities of Michoacan, Mexico, to assess microbiological quality and the occurrence of diarrheagenic Escherichia coli pathotypes (DEP) and nontuberculous mycobacteria (NTM). Aerobic mesophilic bacteria were detected in all samples, with concentrations ranging from 0.95 to 3.71 log₁₀ CFU/mL. A total of 62, 34, and 25 samples tested positive for total coliforms, fecal coliforms, and E. coli, respectively. Sixty-two samples exceeded Mexico’s official guideline. None of the 58 E. coli strains isolated from the 25 E. coli-positive samples belonged to DEP. NTM species were recovered from 47 samples, including M. mucogenicum (n = 18), M. abscessus (n = 11), M. chelonae (n = 7), M. porcinum (n = 3), M. fortuitum (n = 2), M. septicum (n = 1), M. phocaicum (n = 1), and M. brisbanense (n = 1). Three additional isolates could not be identified. All NTM strains produced biofilm and exhibited sliding motility. These findings highlight significant microbiological risks associated with vending machine water and underscore the need for manufacturers to ensure regular maintenance to provide safe and reliable purified water to consumers.

Humans are continuously exposed to toxic substances from both natural and anthropogenic sources, including environmental contaminants such as arsenic (As), lead (Pb), and fluoride (F). Arsenic occurs naturally in groundwater and frequently coexists with fluoride, although anthropogenic activities such as mining, smelting, and industrial processes also contribute to environmental contamination. Lead exposure remains a significant public health concern, particularly in regions where lead-glazed earthenware is widely used for cooking and food storage. The adverse health effects associated with these toxicants range from non-carcinogenic outcomes to carcinogenic processes; however, a common mechanism underlying their toxicity is the induction of oxidative stress. Among these contaminants, arsenic is unique because it undergoes extensive biotransformation, generating intermediate metabolites, particularly trivalent methylated species, that may exhibit greater toxicity than inorganic arsenic itself and contribute substantially to oxidative damage. Oxidative stress is characterized by an imbalance between the production of reactive oxygen and nitrogen species and the capacity of antioxidant defense systems to neutralize them. This imbalance promotes alterations in gene expression through impaired DNA repair mechanisms, protein oxidation, lipid peroxidation, and disruption of endogenous antioxidant pathways. This chapter discusses the mechanisms by which arsenic, lead, and fluoride induce oxidative stress, emphasizing their adverse health effects and current strategies for reducing exposure and preventing toxicity.

La resistencia antimicrobiana (RAM) es una amenaza creciente para la salud pública y el medio ambiente. La eliminación inadecuada de antimicrobianos en aguas residuales hospitalarias contribuye a su presencia en cuerpos de agua, favoreciendo microorganismos resis-tentes. Este artículo examina la asociación entre la contaminación ambiental y la diseminación de la RAM, así como las limitaciones del marco normativo vigente en México. Se ofrece un análisis crítico de este vacío normativo y se plantean recomendaciones de acción frente a la resistencia antimicrobiana ambiental, desde una perspec-tiva conjunta de salud pública y sostenibilidad ambiental.

Background/Objectives: Depression ranks among the most prevalent mental health disorders worldwide. Numerous studies have linked the C-1019G (rs6295) polymorphism in the serotonin 1A (5-HT1A) receptor gene to increased susceptibility to depression. In this study, sociodemographic variables and clinical characteristics were integrated with targeted genotyping of the C-1019G polymorphism to identify risk factors associated with depressive symptoms in a Mexican cohort. Methods: Sociodemographic and clinical data were collected from 257 volunteers (202 healthy controls, 55 with depressive symptoms). Genotyping for C-1019G was performed using polymerase chain reaction–restriction fragment length polymorphism (PCR-RFLP). Sociodemographic variables, clinical characteristics, and genotype frequencies were analyzed relative to Beck Depression Inventory II (BDI-II) scores. Results: BDI scores were significantly lower among males, participants aged < 40 years, unmarried individuals, and those with a high school education (p < 0.05). Females were three times more likely to exhibit depressive symptoms than males (p = 0.004; OR = 3.08). Compared with participants aged < 40 years, those aged 40–65 and >65 years were two (p = 0.026; OR = 2.19) and five times (p < 0.001; OR = 5.71) more likely to report depressive symptoms, respectively. Participants with type 2 diabetes mellitus had twice the odds of depressive symptoms (p = 0.025; OR = 2.38). Odds increased twelvefold among those with diabetes plus arterial hypertension (p < 0.001; OR = 12.25). Among males, the C/C genotype was observed exclusively in controls (p = 0.010). Furthermore, the genotypic distribution of this study population differed from that of European and Asian populations. Conclusions: These findings advance the understanding of depressive symptoms’ multifactorial etiology and may inform targeted screening and prevention strategies.