The influence of purification of carp collagen used in a novel composite graft with sandwich construction of the wall on its biological properties and graft patency rates.

We compared graft outcome between two types of a novel composite three-layer carp-collagen-coated vascular graft in low-flow conditions in a sheep model. Collagen in group A underwent more cycles of purification than in group B in order to increase the ratio between collagen and residual fat. The grafts were implanted end-to-side in both carotid arteries in sheep (14 grafts in 7 sheep in group A, 18 grafts in 9 sheep in group B) and artificially stenosed on the right side. The flow in the grafts in group A decreased from 297±118 ml/min to 158±159 ml/min (p=0.041) after placement of the artificial stenosis in group A, and from 330±164ml/min to 97±29 ml/min (p=0.0052) in group B (p=0.27 between the groups). From the five surviving animals in group A, both grafts occluded in one animal 3 and 14 days after implantation. In group B, from the six surviving animals, only one graft on the left side remained patent (p=0.0017). Histology showed degradation of the intimal layer in the center with endothelization from the periphery in group A and formation of thick fibrous intimal layer in group B. We conclude that the ratio between collagen and lipid content in the novel three-layer graft plays a critical role in its patency and structural changes in vivo.

Microcolumn high-performance liquid chromatographic assay for doxycycline in isolated alveolar macrophages.

A procedure for the isolation of doxycycline from the alveolar macrophages is described. Due to the minimal amount of the sample, it was necessary to employ microcolumn HPLC. A great advantage of the methodology developed in the present paper consists in the direct injection of an aqueous supernatant over disintegrated macrophages without the use of liquid-liquid or solid-liquid extraction. Another advantage of the method is the fact that the injection of an aqueous solution on a microcolumn with a lipophilic stationary phase makes the analyzed substances concentrate, which increases the sensitivity of assay. Separation was performed on a Separon SGX C18 microcolumn, 150 x 1 mm, detection at 254 nm by UV, 1 microliter flow cell. Rabbits were treated intravenously with Vibramycin inj. sic. in a dose of 13 mg/kg body weight doxycycline. A procedure for washing macrophages from rabbit lungs was developed. Dry matter of macrophages ranged from 5.9 to 11.4 mg. In the samples of three rabbits the levels of doxycycline ranged from 110 to 270 ng per 1 mg of macrophages dry matter.