Carlos Valverde | PubMed Health

PubMed2004

Halometabolites and cellular dehalogenase systems: an evolutionary perspective.

We review the role of iodothyronine deiodinases (IDs) in the evolution of vertebrate thyroidal systems within the larger context of biological metabolism of halogens. Since the beginning of life, the ubiquity of organohalogens in the biosphere has provided a major selective pressure for the evolution and conservation of cellular mechanisms specialized in halogen metabolism. Among naturally available halogens, iodine emerged as a critical component of unique developmental and metabolic messengers. Metabolism of iodinated compounds occurs in the three major domains of life, and invertebrate deuterostomes possess several biochemical traits and molecular homologs of vertebrate thyroidal systems, including ancestral homologs of IDs identified in urochordates. The finely tuned cellular regulation of iodometabolite uptake and disposal is a remarkable event in evolution and might have been decisive for the explosive diversification of ontogenetic strategies in vertebrates.

Animals↗

PubMedDate not supplied

[Neonatal hypothyroidism. pathophysiogenic, molecular and clinical aspects].

This review provides an updated summary on both the clinical and diagnostic aspects of neonatal hypothyroidism (NeH); as well as on the molecular and pathophysiologic processes known to be involved in the installment of this important hormonal deficiency. Current information regarding its etiology and pathogenesis has allowed classigying NeH in three major groups: endemic, transient, and sporadic hypothyroidism. The later corresponds to congenital hypothyroidism and encompasses a broad spectrum of hereditary disorders causing hypothyroidism in newborns and young children. These congenital disorders include hypothalamic-pituitary or thyroid dysgenesis and/or dyshormonogenesis, as well as hyporesponsiveness or resistance to either TRH, TSH or to thyroid hormones. The introduction of national screening programs for NeH have overcome the difficulties in the early diagnosis thus helping to prevent its serious and irreversible consequences on intellectual and physical development. Concomitantly, an increase in the need for complementary etiologic and molecular diagnosis has risen. The current capability to perform a fine and precise diagnose is crucial both for treatment of the affected infant and for genetic counseling of the family. Although incomplete, available epidemiological information in Mexico indicates that NeH prevalence can be as high as twice that in other developed world countries. On these bases, national public health policies and epidemiological surveyance must be strengthen not only to identify. diagnose and timely treat, but to prevent and eradicate endemic NeH.

Congenital Hypothyroidism↗