Tear propagation in isolated, pressurized porcine thoracic aortas.

Objective: To determine the pressure required for the initial medial tear, and for propagtion of dissections, within the media of isolated pressurized porcine thoracic aorta, and to determine whether these vary with tear depth.

Design: India ink-stained saline was injected into the media of 48 fresh porcine descending thoracic aorta that were distended with 130 mmHg pressure. The fluid was infused into the media through a 25 gauge needle connected to a constant infusion pump, and the pressure at the entrance to the needle was monitored with a Cobe pressure transducer.

Local changes in collagen content in rabbit aortic atherosclerotic lesions with time.

A video-microdensitometry method was used to quantify collagen on a pixel by pixel basis at specific locations within atherosclerotic lesions, induced by feeding New Zealand White rabbits a declining cholesterol diet. Probability mapping (done previously) showed the lesions occurred in predictable locations so the age of any one area of a lesion could be estimated. The oldest part of the lesion was on the lateral lip of the flow divider as lesions always developed there first.

Collagen quantitation by video-microdensitometry in rabbit atherosclerosis.

A video-microdensitometry method was developed to measure the mass fraction of collagen in portions of tissue sections. A frame grabber and computer are used to capture micrographs and calculate the collagen fraction at each pixel. The method is based on the stoichiometric staining of collagen by picrosirius red stain, and was calibrated for glutaraldehyde fixed tissue; a detailed map of collagen distribution throughout a six-month rabbit atherosclerotic lesion was made.

A new probability mapping method to describe the development of atherosclerotic lesions in cholesterol-fed rabbits.

A new probability mapping method was developed to quantify the size and location of lesions near aortic orifices. The precise location of any part of the lesion could be compared between rabbits. Colour photographs of lesions were projected onto a digitizing tablet, and coded as lesion or non-lesion.

The distribution of fibro-fatty atherosclerotic lesions in the aortae of casein- and cholesterol-fed rabbits.

Atherosclerotic lesions were induced in the aortas of 50 rabbits by feeding a semi-purified cholesterol-free casein diet or normal rabbit chow with a low level of added cholesterol for 6 or 10 months. Following perfusion fixation, the aortae from these animals were opened along their length, stained with oil red O and photographed en face. Orifice associated lesions were mapped by measuring radial lesion length at 10 degrees intervals circumferentially around ostia.

Morphological evidence of pulmonary vascular leakage through gaps observed with casting methods and S.E.M.

We have used selective casting methods to separate pulmonary elastin from vascular elastin in the lungs of rabbits, dogs and pigs. The lungs are digested with 0.1 N NaOH at 75 degrees C for 24 approximately 48 hours with frequent turning as the lungs are filled with air to about 80% of the vital capacity prior to the casting which is done at pressure of 20 approximately 50 mmHg.

Taper: an important feature of Y-bifurcations in porcine renal arteries and human cerebral arteries.

The geometry of arterial bifurcations has been shown to alter fluid flow and the propagation of both pressure and flow waves. Here we provide a more complete description of the renal artery bifurcation geometry and show that the geometry of the bifurcation is more complex than was believed previously. The objective of this study was to quantify changes in cross-sectional luminal area in systemic arterial bifurcations using the method developed by Macfarlane [Ph.

Quantitative measurement of fixation rate and dimension changes in the aldehyde/pressure-fixed canine carotid artery.

Excised canine carotid arteries held at constant physiologic length were cycled from -13 to +27 kPa with a constant-flow infusion pump, and the pressure-volume curves were recorded. The change in diameter on reducing the pressure from 16 to 0 kPa was determined and the strain of recoil [(diameter16--diameter0)/diameter16] calculated. Diameter recoil was reduced from 51% (fresh tissue) to 5% after 3 h pressure fixation in 4% formaldehyde and to 9% after 15 min in 2% glutaraldehyde with little further change.

[Surgical treatment of chronic pain in the area of the Achilles tendon].

In 109 patients with painful Achilles tendons 139 primary operations were made. Peritenonectomy and scarification of the tendon were performed. As a criterium of success the ability to pursue the original sports activities was used.

Quantitative measurement from vascular casts.

A review of quantitative measurements show casting materials shrink from 0.2 - 20% and have viscosities ranging from 1.4 - 100,000 centipoise.

Quantitative measurements of early atherosclerotic lesions on rabbit aortae from vascular casts.

We have measured the size and location of fatty atherosclerotic lesions in the cholesterol fed rabbit by scanning electron microscopic analysis of vascular casts. The aortic periorificial lesions examined in this study have been divided into proximal (upstream), distal (downstream) and lateral (to the sides of the branch). Lateral lesions developed after 1 week on diet, followed by distal lesions at 2 weeks, and occasional proximal lesions at 4 weeks.

Scanning electron microscopy of early atherosclerosis in rabbits using aortic casts.

Our research involves measuring the size and location of atherosclerotic lesions on the intimal surface of arteries. To this end we have developed a new method in which scanning electron micrographs of vascular casts with impressions of these lesions on their surface are used. This method is compared with light microscopy and scanning electron microscopy of tissue with lesions.

Endothelial cell morphometry near branch junctions of rabbit aortae.

Endothelial cell morphometric data were gathered from corrosion casts of the aorta and its branches of six New Zealand white rabbits weighing 2-3 kg. The endothelial cell outlines were ditigized to provide cell orientation index (COI) from the equation COI = 2Ms/2M1-1, where 2Ms and 2M1 are the second moments of area about short and long axes of the cell. The COI varies from zero to infinity.

Scanning electron microscopic studies of the vasa vasorum of thoracic aortas.

Using hot alkaline solution, the elastic laminae were extracted from aortas and observed with scanning electron microscopy. Vascular structures were found in the elastin layers of the tunica media in descending thoracic aortas of sheep, dogs, and pigs, and these tube-like structures were filled with elastomer which was injected through the heart of the animal in vivo. Sub-intimal microvessels were also found to be filled with the elastomer and it is concluded that vasa vasorum can exist close to the internal elastic lamina in these animals.

Steady flow visualization in a rigid canine aortic cast.

Steady flow studies were conducted in a transparent canine aortic cast. The cast segment stretched from the aortic valve to beyond the renal arteries and included all major branches. Flow was visualized by analysis of dye streaklines.

Relationship between aortic endothelial cell morphology and atherosclerosis in rabbits.

Previous studies on cholesterol-induced sudanophilic lesions in rabbit aortas showed that the earliest lesions were periorificial with the greatest involvement distal to branch sites. In order to determine if there is a relationship between endothelial cell morphology and the regional differences in susceptibility to atherosclerosis we compared cell morphology distal to several aortic ostia and away from ostia. We examined the en face morphology of the intimal surface.