[Structural organization of the human genome: distribution of nucleotides, Alu-repeats and exons in chromosomes 21 and 22]

Analysis of DNA sequences of the human chromosomes 21 and 22 performed using a specially designed MegaGene software allowed us to obtain the following results. Purine and pyrimidine nucleotide residues are unevenly distributed along both chromosomes, displaying maxima and minima (Y waves phi) with a period of about 3 Mbp. Distribution of G + C along both chromosomes has no distinct maxima and minima, however, chromosome 21 contains considerably less G + C than chromosome 22. Both exons and Alu repeats are unevenly distributed along chromosome 21: they are scarce in its left part and abundant in the right part, while MIR elements are quite monotonously spread along this chromosome. The Alu repeats show a wave-like distribution pattern similar for both repeat orientations. The number of the Alu repeats of opposite orientations was equal for both studied chromosomes, and this may be considered a new property of the human genome. The positive correlation between the exon and Alu distribution patterns along the chromosome, the concurrent distribution of Alu repeats in both orientations along the chromosome, and the equal copy numbers for Alu in direct and inverted orientations within an individual chromosome point to their important role in the human genome, and do not fit the notion that Alu repeats belong to parasitic (junk) DNA.

Evaluation of the greater omentum in the treatment of experimental lymphedema

Despite advances in microsurgery, the most suitable operation for primary lymphedema remains unclear. A variety of tissue transplants and artificial substances have been used to facilitate drainage of peripheral lymph. The greater omentum, for example, has absorptive lymph draining capability, fights infection, and is expendable for the abdomen. Previous attempts to use the omentum in treatment of clinical lymphedema have, however, been disappointing. This discrepancy between theory and outcome prompted us to reevaluate the role of the omentum in the treatment of chronic lymphedema. In rabbits, mobilization of omentum was carefully examined by three separate techniques and the presence of natural lymph nodal-venous (L-V) shunts determined by an injection of Evans blue into the omentum with sampling later of plasma from the gastroepiploic venous blood. In dogs after promotion of unilateral chronic hindlimb lymphedema by soft tissue excision and sclerosis, the results of four methods of omental transplantation with or without L-V shunt for relief of lymphedema were compared. The results in rabbits suggest that although the greater omentum can be lengthened without jeopardizing its blood supply, it is inappropriate to lengthen it based on blood vascular arcades alone because the omental lymphatics do not strictly follow these arcades in the more distal portion, and with elongation, may be interrupted even though the blood supply remains intact. Moreover, because there is no natural L-V shunt within the greater omentum, the addition of a L-V shunt in dogs in addition to omental transplantation seems to increase effectiveness of the omentum for draining hindlimb lymph after its autotransplantation.