Three contaminated sites in southern Italy. The Neonatal Environment and Health Outcomes cohort: protocol for a longitudinal birth cohort study.

Introduction: Exposure to environmental contaminants during pregnancy is one of the determinants of child's future health outcomes. The effect of environmental pollution on pregnant women living in heavily polluted areas is of special interest and, in this context, the Neonatal Environment and Health Outcomes (NEHO) cohort will focus on the investigation of (1) toxicants transferred from the environment to the mother and from the mother to the developing fetus and (2) the influence of toxicants on pregnancy outcomes, fetal development and health status during infancy. Because the human placenta is positioned at the interface between the maternal/external environment and the embryo, it can be considered a highly informative matrix regarding many key pregnancy events that can shape infant's future health.

Maximal dinucleotide and trinucleotide circular codes.

We determine here the number and the list of maximal dinucleotide and trinucleotide circular codes. We prove that there is no maximal dinucleotide circular code having strictly less than 6 elements (maximum size of dinucleotide circular codes). On the other hand, a computer calculus shows that there are maximal trinucleotide circular codes with less than 20 elements (maximum size of trinucleotide circular codes).

On the dinucleotide circular codes of maximum cardinality.

In a recent paper, Michel and Pirillo prove that there are 24 dinucleotide circular codes of maximum cardinality over an alphabet of cardinality 4. In this paper we find the exact number of dinucleotide circular codes of maximum cardinality for any given (finite) cardinality of the alphabet. Moreover, we describe the structure of these codes.

A permuted set of a trinucleotide circular code coding the 20 amino acids in variant nuclear codes.

We identify here a combinatorial property between circular code and genetic code. A circular code of 20 trinucleotides which allows to retrieve the reading frame has a permuted set of 20 trinucleotides which is a code, but not circular, coding the 20 amino acids in variant nuclear codes. This result is a contribution to the research field analysing the mathematical properties of genetic codes.

Identification of all trinucleotide circular codes.

A new trinucleotide proposition is proved here and allows all the trinucleotide circular codes on the genetic alphabet to be identified (their numbers and their sets of words). This new class of genetic motifs, i.e.

Growth function of self-complementary circular codes.

In several papers Arquès and Michel studied the maximal circular codes consisting of words of length 3 (or trinucleotides) on the genetic alphabet {A, C, G, T}. We present here some additional information on these codes. In particular, we study the growth function of the self-complementary circular codes and we prove that among them exactly 528 are maximal.