Permanent and decidua dentition as chronological biomarkers of heavy metal contamination: A review of the forensic literature.

STATEMENT OF PROBLEM: Contamination with heavy metals (HM) has great environmental consequences in the environment due to lack of biodegradation, in addition, accumulation in living beings causes defects in tissues and organs, deteriorating their function and inducing a wide spectrum of diseases. Human biomonitoring consists of the periodic measurement of a certain chemical substance or metabolite in a particular population, using matrices that can be acute or chronic. Teeth are chronic matrices that have great characteristics of resistance and chronological storage of information. This review aims to identify the mechanisms, spatial location, and affinity of HM within teeth, along with understanding its applicability as a chronological record matrix in the face of HM contamination. MATERIAL AND METHODS: A systematic search review was performed using the PubMed/Medline, Web of Science, and Scopus metasearch engines, and the terms "teeth" OR "dental" OR "tooth" AND "heavy metals" were intersected. Complete articles are included in Spanish, English and Portuguese without time restrictions, involving studies in humans or in vitro; Letters to the editor, editorials and those that did not refer to information on the incorporation and relationship of HM with the teeth were excluded. RESULTS: 837 published articles were detected, 91 were adjusted to the search objective, and 6 were manually included. Teeth are structures with a great capacity for information retention in the face of HM contamination due to low physiological turnover and their long processes of marked formations by developmental biorhythm milestones such as the neonatal line (temporal reference indicator). The contamination mechanisms inside the tooth are linked to the affinity of hydroxyapatite for HM; this incorporation can be in the soft matrix during the apposition phase or as part of the chemical exchanges between hydroxyapatite and the elements of the environment. CONCLUSION: The teeth present unique characteristics of great resistance and affinity for HM, as well as a chronological biomarker for human biomonitoring, so they can be used as means of expertise or evidence to confirm or rule out a fact of environmental characteristics in the legal field.

Behavioral Study of 3- and 5-Halocytisine Derivatives in Zebrafish Using the Novel Tank Diving Test (NTT).

Anxiety is a serious mental disorder, and recent statistics have determined that 35.12% of the global population had an anxiety disorder during the COVID-19 pandemic. A mechanism associated with anxiolytic effects is related to nicotinic acetylcholine receptor (nAChR) agonists, principally acting on the α4ß2 nAChR subtype. nAChRs are present in different animal models, including murine and teleosteos ones. Zebrafish has become an ideal animal model due to its high human genetic similarities (70%), giving it high versatility in different areas of study, among them in behavioral studies related to anxiety. The novel tank diving test (NTT) is one of the many paradigms used for studies on new drugs related to their anxiolytic effect. In this work, an adult zebrafish was used to determine the behavioral effects of 3- and 5-halocytisine derivatives, using the NTT at different doses. Our results show that substitution at position 3 by chlorine or bromine decreases the time spent by the fish at the bottom compared to the control. However, the 3-chloro derivative at higher doses increases the bottom dwelling time. In contrast, substitution at the 5 position increases bottom dwelling at all concentrations showing no anxiolytic effects in this model. Unexpected results were observed with the 5-chlorocytisine derivative, which at a concentration of 10 mg/L produced a significant decrease in bottom dwelling and showed high times of freezing. In conclusion, the 3-chloro and 3-bromo derivatives show an anxiolytic effect, the 3-chlorocytisine derivative being more potent than the 3-bromo derivative, with the lowest time at the bottom of the tank at 1mg/L. On the other hand, chlorine, and bromine at position 5 produce an opposite effect.

Determinación morfométrica de áreas normales en 100 válvulas mitrales / Morphometric determination of normal areas in 100 mitral valves

Se analizaron morfométricamente 100 válvulas mitrales normales calculando las áreas de las valvas según el método de King y col. Se elaboró una tabla de valores normales con las medidas de 25 válvulas de corazones normales (grupo 1), que sirvieron de control para los valores restantes (n=75) reunidos en tres grupos (2,3,4) de corazones que presentaban diversos grados de cardiomegalia. Se comprobó que la media de las áreas de la valvula mitral era directamente proporcional al peso cardíaco y al aumento de la circunferencia del anillo valvular. Se recomendó tomar en cuenta el peso del corazón para evaluar los aumentos de las áreas valvulares sin patología. También se calculó el área valvular mitral utilizando el planímetro y se hizo comparación con el de King, de corazones (n=30), comprobando que no existen diferencias significativas entre ambos métodos. Se escogió el método de King para el cálculo de áreas valvulares por ser sencillo, confiable y más práctico que el de planimetría. Las medidas de las áreas mitrales son importantes para ser aplicadas en el diagnóstico macroscópico de enfermeades que cursan con áreas aumentadas como el prolapso mitral de I y II grado