Fat mass obesity-associated (FTO) (rs9939609) and melanocortin 4 receptor (MC4R) (rs17782313) SNP are positively associated with obesity and blood pressure in Mexican school-aged children.

Childhood overweight and obesity are worldwide public health problems and risk factors for chronic diseases. The presence of SNP in several genes has been associated with the presence of obesity. A total of 580 children (8-13 years old) from Queretaro, Mexico, participated in this cross-sectional study, which evaluated the associations of rs9939609 (fat mass obesity-associated (FTO)), rs17782313 (melanocortin 4 receptor (MC4R)) and rs6548238 (transmembrane protein 18 (TMEM18)) SNP with obesity and metabolic risk factors. Overweight and obesity prevalence was 19·8 and 19·1 %, respectively. FTO, MC4R and TMEM18 risk allele frequency was 17, 9·8 and 89·5 %, respectively. A significant association between FTO homozygous and MC4R heterozygous risk alleles and obesity was found (OR 3·9; 95 % CI 1·46, 10·22, and OR 2·1; 95 % CI 1·22, 3·71; respectively). The FTO heterozygous subjects showed higher systolic and diastolic blood pressures, compared with the homozygous for the ancestral allele subjects. These results remain significant after considering adiposity as a covariate. The FTO and MC4R genotypes were not significantly associated with total cholesterol, HDL-cholesterol and insulin concentration. No association was found between TMEM18 risk allele and obesity and/or metabolic alterations. Our results show that, in addition to a higher BMI, there is also an association of the risk genotype with blood pressure in the presence of the FTO risk genotype. The possible presence of a risk genotype in obese children must be considered to offer a more comprehensive therapeutic approach in order to delay and/or prevent the development of chronic diseases.

3,5-Diiodothyronine (T2) is on a role. A new hormone in search of recognition.

Thyroid hormone (TH) actions are mediated by triiodothyronine (T3), which acts by binding to the TH receptors (TRs). Since TH exert pleiotropic effects, interest has grown in identifying other possible bioactive thyronines that could explain their diversity of functions. Accordingly, 3,5-diiodothyronine (T2) has been shown to be bioactive. In mammals, T2 regulates mRNA expression of several T3-regulated genes, but doses up to 100-fold greater than those of T3 were required to generate comparable effects. In teleosts, T2 and T3 regulate gene expression in vivo with equivalent potency. Furthermore, in vivo and in vitro studies support the notion that T2 binds to and activates a specific, long TRß1 isoform that contains a nine amino acid insert at the beginning of the ligand binding domain, whereas T3 can interact also with a different TRß1 isoform that lacks this insert. Similarly, T2 and T3 differentially regulate long- and short-TRß1 expression, respectively, strongly suggesting a different signaling pathway for each hormone, at least in the species that express both receptors. In vivo, T2 effectively triggers a burst of body growth in tilapia by interacting with the long TRß1 isoform, supporting the notion that T2 is physiologically relevant in this species. Current knowledge of T2 effects and action mechanisms lead us to propose that there is an extra level in the thyroid hormone signaling cascade, and that T2 is produced and regulated specifically for this purpose.

Iodine nutrition and thyroid function assessment in childbearing age women from Queretaro, Mexico.

OBJECTIVE: To assess iodine nutrition and thyroid function in Mexican childbearing age women. METHODS: 101 childbearing age women (21.7 ± 3.5 years) randomly selected from the university student population participated in this cross-sectional study. TSH, thyroid hormones, anti-thyroid antibodies, thyroid volume, iodine intake, and urinary iodine concentration (UIC) were assessed. The knowledge about the importance of iodine in nutrition was also evaluated by using questionnaires. RESULTS: TSH median (interquartile range) value was 1.9 (1.4-2.5) mIU/L, while FT4 median value was 9.0 (8.3- 9.6) µg/dL. The median FT3 and total rT3 values were 3.3 pg/mL and 40.1 ng/dL, respectively. The prevalence of subclinical hypothyroidism (serum TSH >4.5 mIU/L) and of positive anti-thyroid antibodies were 2.9% and <5.9%, respectively. Median thyroid volume was 5.6 mL and none of the subjects were diagnosed with goiter. Median urinary iodine concentration was 146 (104-180) µg/L. As for the knowledge of iodine nutrition, only 37.6% considered that a pregnant woman needs more dietary iodine than a non pregnant woman, while 43.6% recognized that the lack of iodine can cause mental retardation in children. CONCLUSIONS: Prevalence of thyroid test function abnormalities was low in this population and the median UIC indicates adequate iodine intake. We also found a poor knowledge about the importance iodine nutrition in the studied population.

Iodine nutrition and thyroid function assessment in child bearing age women from Queretaro, Mexico / Estado nutricio en yodo y función tiroidea en mujeres en edad reproductiva de Querétaro, México

Objective: To assess iodine nutrition and thyroid function in Mexican childbearing age women. Methods: 101 childbearing age women (21.7 ± 3.5 years) randomly selected from the university student population participated in this cross-sectional study. TSH, thyroid hormones, anti-thyroid antibodies, thyroid volume, iodine intake, and urinary iodine concentration (UIC) were assessed. The knowledge about the importance of iodine innutrition was also evaluated by using questionnaires. Results: TSH median (interquartile range) value was1.9 (1.4-2.5) mIU/L, while FT4 median value was 9.0 (8.3-9.6) μg/dL. The median FT3 and total rT3 values were 3.3pg/mL and 40.1 ng/dL, respectively. The prevalence of subclinical hypothyroidism (serum TSH >4.5 mIU/L) and of positive anti-thyroid antibodies were 2.9% and <5.9%,respectively. Median thyroid volume was 5.6 mL and none of the subjects were diagnosed with goiter. Median urinary iodine concentration was 146 (104-180) μg/L. As for the knowledge of iodine nutrition, only 37.6% considered that a pregnant woman needs more dietary iodine than a non pregnant woman, while 43.6% recognized that the lack of iodine can cause mental retardation in children. Conclusions: Prevalence of thyroid test function abnormalities was low in this population and the median UIC indicates adequate iodine intake. We also found a poor knowledge about the importance iodine nutrition in the studied population (AU)

Objetivo: Evaluar el estado nutricional en yodo y la función tiroidea en mujeres mexicanas en edad reproductiva. Métodos: 101 mujeres universitarias en edad reproductiva(21,7 ± 3,5 años) fueron seleccionadas al azar para participar en este estudio transversal. Se evaluaron los niveles séricos de tirotropina, hormonas tiroideas, anticuerpos anti-tiroideos, volumen tiroideo, consumo de yodo y yoduria. También se evaluó el conocimiento sobre la importancia del yodo en la nutrición. Resultados: La mediana (rango intercuartilar) de tirotropina fue de 1,9 (1,4-2,5) mIU/L, mientras que para T4libre fue de 9,0 (8,3-9,6) μg/dL. Los valores de la mediana de T3 libre y T3 reversa fueron de 3,3 pg/mL y 40,1 ng/dL, respectivamente. La prevalencia de hipotiroidismo subclínico fue 2,9% (tirotropina sérica >4,5 mUI/L). La prevalencia de anticuerpos antitiroideos positivos fue <5,9%.La mediana del volumen tiroideo fue de 5,6 mL y no se diagnosticaron mujeres con bocio. La mediana (rangointercuartilar) de la yoduria fue de 146 (104-180) μg/L. En cuanto al conocimiento de la importancia del yodo en la nutrición, el 37,6% consideró que las mujeres gestantes requieren más yodo en la dieta que las no gestantes, mientras que el 43,6% reconoció que la deficiencia de yodo puede causar retraso mental en los infantes. Conclusiones: Se encontró una baja prevalencia de alteraciones en las pruebas de función tiroidea, mientras que la mediana de la yoduria indicó un adecuado consumo de yodo. También se encontró un conocimiento bajo acerca de la importancia del yodo en la nutrición (AU)

Iodothyronine deiodinases: a functional and evolutionary perspective.

From an evolutionary perspective, deiodinases may be considered pivotal players in the emergence and functional diversification of both thyroidal systems (TS) and their iodinated messengers. To better understand the evolutionary pathway and the concomitant functional diversification of vertebrate deiodinases, in the present review we summarized the highlights of the available information regarding this ubiquitous enzymatic component that represents the final, common physiological link of TS. The information reviewed here suggests that deiodination of tyrosine metabolites is an ancient feature of all chordates studied to date and consequently, that it precedes the integration of the TS that characterize vertebrates. Phylogenetic analysis presented here points to D1 as the oldest vertebrate deiodinase and to D2 as the most recent deiodinase gene, a hypothesis that agrees with the notion that D2 is the most specialized and finely regulated member of the family and plays a key role in vertebrate neurogenesis. Thus, deiodinases seem to be major participants in the evolution and functional expansion of the complex regulatory network of TS found in vertebrates.

Effects of iodothyronines on the hepatic outer-ring deiodinating pathway in killifish.

Substrate availability has been thought to be a major regulator of the outer-ring deiodinating pathway (ORD) in fish. However, current information strongly suggests that while fish iodothyronine deiodinase type 2 (D2) responds to iodothyronines in the same manner as its mammalian counterpart, fish deiodinase type 1 (D1) exhibits a distinct response. Furthermore, 3,5-T2, generally considered to be an inactive product of iodothyronine metabolism, has recently been described as bioactive, but its effects upon D1 and D2 are not yet known. We examined the effect that short-term immersion in T4, T3, and 3,5-T2 (0.1 microM; 12 or 24 h) exerts on both D1 and D2 activities and on the levels of expression of D1 and D2 mRNAs in killifish liver. In agreement with previous reports in teleosts, no iodothyronine exerted a significant effect on D1 enzymatic activity. However, all three iodothyronines significantly decreased D2 activity. Furthermore, at 24 h post-immersion T4, T3, and 3,5-T2 inhibited both D1 and D2 transcription. Together, the present results confirm the differential effect of iodothyronines upon the hepatic ORD pathway in fish and show that this effect can occur at a transcriptional level. Furthermore, we provide the first evidence that 3,5-T2 can affect both activity and transcription of hepatic deiodinases in teleosts.