No abstract

Nitric oxide (NO) is a short-life key bioregulatory active molecule in the cardiovascular, immune and nervous systems. NO is synthesized by converting L-arginine to L-citrulline by enzymes called NO synthase (NOS). The growing body of evidence strongly supports the theory that this molecule appears to be one of the key targets for the disruption of normal brain homeostasis, which causes the development of brain lesions and pathology such as in Alzheimer's disease (AD) or other related dementia. The vascular content of NO activity appears especially to be a main contributor to this pathology before the over-expression of other NOS isoforms activity in a different brain cellular compartment. We speculate that pharmacological intervention using NO donors and/or NO suppressors will be able to delay or minimize the development of brain pathology and further progression of mental retardation.

No abstract

Metallothionein affects the metabolism, transport and storage of micronutrients such as zinc, copper and iron, and the detoxification of heavy metals, especially cadmium. Cd is a common, highly toxic environmental pollutant that accumulates in human placenta, elevated concentrations of which are associated with impaired zinc transfer to the fetus. This prospective study investigated the effects of metallothionein 2A (MT2A) -5 A/G single nucleotide polymorphism on the accumulation of Cd in human placenta and micronutrient transfer to the fetus in 95 pregnant women and their newborns. Venous blood from the mother was collected to investigate Cd, Zn, Cu, Fe levels and MT2A polymorphism. Cord blood from the neonate and placenta was collected for metal levels. MT2A polymorphism was determined by the standard PCR-restriction fragment length polymorphism technique. Metal levels were analyzed by Atomic Absorption Spectrometry (AAS). Maternal blood Cd levels were statistically higher for mothers with a heterozygote genotype compared with a homozygote genotype (P<0.05). In contrast, placental Cd levels were significantly higher in mothers with a homozygote rather than a heterozygote genotype (P<0.05). No difference existed in cord blood Cd, Zn and Cu levels. However, cord blood Fe levels of newborns with heterozygote genotype mothers were higher than in others. Placental Cd levels of heterozygote genotype mothers were negatively associated with Zn in cord blood. Cd exposure at environmental levels may be associated with alteration of the umbilical cord micronutrient levels for newborns with mothers of a heterozygote genotype.

Preventive measures for protection from exposure to Hg are necessary for occupational health in dentistry and proper industrial hygiene rules should be emphasized to avoid contamination during work.