Hydrodynamic gene delivery to the pig liver via an isolated segment of the inferior vena cava.

Hydrodynamic gene delivery is an attractive option for non-viral liver gene therapy, but requires evaluation of efficacy, safety and clinically applicable techniques in large animal models. We have evaluated retrograde delivery of DNA to the whole liver via the isolated segment of inferior vena cava (IVC) draining the hepatic veins. Pigs (18-20 kg weight) were given the pGL3 plasmid via two programmable syringe pumps in parallel. Volumes corresponding to 2% of body weight (360-400 ml) were delivered at 100 ml s(-1) via a Y connector. The IVC segment pressure, portal venous pressure, arterial pressure, electrocardiogram (ECG) and pulse were monitored. Concurrent studies were performed in rats for interspecies comparisons. The hydrodynamic procedure generated intrahepatic vascular pressures of 101-126 mm Hg, which is approximately 4 times higher than in rodents, but levels of gene delivery were approximately 200-fold lower. Suprahepatic IVC clamping caused a fall in arterial pressure, with the development of ECG signs of myocardial ischaemia, but these abnormalities resolved rapidly. The IVC segment approach is a clinically acceptable approach to liver gene therapy. However, it is less effective in pigs than in rodents, possibly because of larger liver size or a less compliant connective tissue framework.

Egg brooding by deep-sea octopuses in the North Pacific Ocean.

Videotapes made from the submersible Alvin on Baby Bare, a 2600-m-deep North Pacific basalt outcrop, and at two other deep-sea localities document that octopuses of the genera Graneledone and Benthoctopus attach their eggs to hard substrate and apparently brood them through development. The behavior of brooding females was generally similar to that of shallow-water octopuses, but the genera showed apparent differences. In addition to the high density of brooding females observed at Baby Bare, which may relate to the increased availability of exposed hard substrates for egg attachment and of prey, females are suggested to increasingly associate with hard substrates as they mature. The biology of Baby Bare may seem unduly unique because the outcrop is isolated on a sedimented plain and is among the few exposures of hard substrate other than hydrothermal vents that have been explored by submersible. On the sediment-covered ocean floor, the availability of hard substrate may strongly affect the distribution of brooding octopuses. The size and shape of boreholes in 19 of over 400 thyasirid clam shells collected from Baby Bare support the hypothesis that octopuses had preyed upon the clams.

Cardiovascular function following acute volume overload for hydrodynamic gene delivery to the liver.

Hydrodynamic gene delivery to the liver is a valuable experimental tool and an attractive option for nonviral gene therapy of liver disease. However, little attention has been paid to the major obstacle to clinical application: acute volume overload of the cardiovascular system. We delivered volumes of DNA solution (pGL3 plasmid) corresponding to 1, 2, 4, 6 and 8% of the body weight at 100 ml/min to the inferior vena cava (IVC) of DA strain rats. Central venous pressure (CVP), arterial pressure, pulse and electrocardiogram (ECG) were continuously recorded for subsequent analysis. Each volume produced a characteristic response, but all (including the 1% volume) caused severe falls in blood pressure and pulse within 1-2 s of the infusion, with ectopic beats and widening of the QRS complex in the ECG. The response to volumes of 4% and higher suggested that the liver acted as a volume sink, mitigating the immediate effects of volume overload. The 6 and 8% volumes caused profound and protracted falls in blood pressure and pulse, with a multitude of severe electrical abnormalities in the heart, including electromechanical dissociation. Vagal blockade with atropine, and the use of Ringer's solution to prevent electrolyte disturbances, did not ameliorate this picture.