Delivery Of Horseradish Peroxidase Research Articles

Intramural delivery of agent via a novel drug-delivery sleeve. Histological and functional evaluation.

The infusion sleeve is a novel drug-delivery catheter system designed to deliver an agent under controlled conditions into the arterial wall at the site of angioplasty. The purpose of the present study was to characterize the delivery agent via the infusion sleeve in ex vivo and in vivo models. The delivery of horseradish peroxidase via the infusion sleeve was studied in a porcine explanted heart model. Under physiological conditions, arteries underwent balloon injury (approximately 10% overstretch), after which horseradish peroxidase (2.5 mL) was delivered at specific pressures. Cross-sectional analysis demonstrated greater staining when the agent was delivered at increasing pressures. The infusion sleeve was evaluated in an in vivo canine coronary model. With an infusion sleeve loaded over a standard dilatation catheter through a 9F guide, overstretch balloon injury was performed, after which fluoresceinated heparin was delivered. Animals were killed 2 hours after delivery. Fluoresceinated heparin-treated segments demonstrated high fluorescence signals, localizing with smooth muscle cell nuclei with less activity in the interstitium. The functional significance of intramural heparin delivery was studied in a porcine carotid model. In the presence of 111In-labeled platelets, arteries underwent overstretch injury followed by delivery of heparin (50 or 100 units/kg) or vehicle. Platelet deposition was reduced at 30 minutes (57%, P < .01) and 12 hours (39%, P = .06) compared with saline controls. Agent delivery via the infusion sleeve is pressure dependent; transmural delivery is possible with minimal disruption of arterial wall architecture; the infusion sleeve is compatible with standard angioplasty equipment; and heparin delivery at the site of balloon injury significantly reduces platelet deposition in a porcine model for a minimum of 12 hours.

Periaqueductal grey projection to the ventrobasal complex in the cat: An horseradish peroxidase study

Horseradish peroxidase (HRP) was injected within the thalamic ventrobasal complex of 14 cats. The aim was to ascertain whether the periaqueductal grey matter (PAG) sends fibres to this complex. Retrogradely labelled cells were found within the PAG following HRP delivery either in the nucleus ventralis posterolateralis (VPL) or ventralis posteromedialis (VPM). PAG-VPL projection is only ipsilateral and arises mainly from lateral PAG. PAG-VPM projection is bilateral and originates from latero-ventral regions of the central grey. The hypothesis that PAG might control the activity of ventrobasal nociceptive neurones is proposed.