The probable structure of the protamine-DNA complex.

A detailed molecular structure is proposed for the human protamine-DNA complex, which has hitherto been largely a mystery. The structure was created with virtual modeling software (AmiraMol), employing logical deduction as the primary investigative tool. A beta-sheet structure for the protein component is essentially mandated, as the alternatives can be decisively excluded.

Topologically non-linked circular duplex DNA.

The discovery of circular DNA, over 30 years ago, introduced an element of uneasiness in what had been, up to that point, the almost picture-perfect story of the elucidation of the molecular biology of heredity. If DNA indeed has the Watson-Crick right-handed helical secondary structure, then in circular DNA, thousands, or perhaps even millions of twists must be removed in each generation, and re-wound in the next generation. Although enzyme systems adequate for this task have long since been found and characterized, there have nevertheless arisen a number of proposals for alternative DNA structures in which the strands are topologically non-linked, so that they might separate during replication without having to be unwound.

Sequential injection of 3% sodium tetradecyl sulfate and 20% sodium chloride in the treatment of refractory varicosity of the greater saphenous vein.

Background: American practitioners of sclerotherapy are limited by United States Food and Drug Administration (FDA) restrictions. The strongest FDA-approved sclerosant is sodium tetradecyl sulfate. In the United States, when a varicose vein is refractory to treatment with this drug, there are no effective FDA-approved pharmaceutical alternatives.

Inadvertent intra-arterial injection complicating ordinary and ultrasound-guided sclerotherapy.

Background: Intra-arterial injection is the most dreaded complication of sclerotherapy of varicose veins. The medical literature does not contain enough data to enable one to formulate a definitive strategy for either the prevention or treatment of this complication.

Objective: Seven cases of intra-arterial injection are presented.