No description available.

No description available.

One major barrier that prevents cartilage integration following mosaic arthroplasty is the presence of a zone of chondrocyte death (ZCD) that is generated upon osteochondral graft harvest, which can extend up to 400 μm into the cartilaginous portion of the graft. In order for cartilage integration to occur, chondrocytes must be present at the graft periphery; however chondrocyte migration through the ZCD to the graft periphery is inhibited by the dense extracellular matrix (ECM) of cartilage. The purpose of this study was to develop a method for increasing the number of chondrocytes within the ZCD and at the periphery of a cartilage graft. This method used a combination of collagenase treatment (as a means of degrading the ECM within the ZCD) and chondrocyte chemotaxis (as a means of improving chondrocyte migration into the ZCD and to the cartilage periphery). Results indicate that treating bovine articular cartilage with 0.6 % collagenase for 10 min decreased with extent of the ZCD by approximately 35% (collagenase: 109 ± 13 μm; control: 175 ± 13 μm). Each of the chemotactic agents tested (PDGF-bb, bFGF, and IGF-I) were found to induce bovine chondrocyte chemotaxis at concentrations of 25 ng/mL in modified Boyden chamber experiments. However, in bovine articular cartilage samples that were pre-treated with collagenase (0.6% for 10 min), supplementation with 25 ng/mL of either PDGF-bb or bFGF had no apparent effect on the ZCD relative to samples treated only with collagenase (PDGF-bb: 85 ± 10 μm; bFGF: 88 ± 10 μm). Alternatively, bovine articular cartilage samples pre-treated with collagenase (0.6% for 10 min) and supplementation with 25 ng/mL IGF-I resulted in an approximately 65% reduction in the ZCD relative to samples treated only with collagenase (IGF-1: 38 ± 5 μm). Thus, treating osteochondral grafts with collagenase and IGF-1 induces chondrocyte repopulation of the zone of chondrocyte death generated by osteochondral graft harvesting, and could enhance cartilage integration after implantation. / Thesis (Master, Chemical Engineering) -- Queen's University, 2009-12-21 20:16:05.815

No description available.

No description available.

Biological, serological, and molecular characteristics of the P4 pathotype of pea seedborne mosaic potyvirus (PSbMV) were investigated. The characterization allowed P4 to be differentiated from other pathotypes of the same virus. P4 was distinguished from P1 on the basis of host symptomatology. It induced varied, but often distinctive symptoms in systemically-infected pea (Pisum sativum) cultivars. P4 inoculation of indicator hosts, notably Chenopodium album, resulted in the formation of local lesions. Pathotype P4 was seed transmitted at low frequencies relative to P1. In ten selected pea cultivars, seed transmission of P4 never exceeded 0.7%, while P1 was transmitted at frequencies as high as 33%. In mixed infections with P1, pathotype P4 was seed transmitted at 0- 2% as determined by P4-specific indirect ELISA. However, limited polymerase chain reaction (PCR) data suggest that P4 may be transmitted with P1 at higher rates than indicated by ELISA data. P4 was also aphid transmitted at relatively low rates. Pea aphids (Acyrthosiphon pisum) allowed 3 or 5 min acquisition access periods (AAP's) transmitted P4 at a maximum rate of 16% (3 aphids/plant). P4 transmission required short (1-7 min) AAP's and exhibited no bimodal character within tested parameters. P4 could be serologically distinguished from the other pathotypes using monoclonal and polyclonal antibodies. Tests with cross-reactive P4 antiserum suggest that P4 is more closely related to P2 than P1. P4-specific antiserum was derived by cross-absorbing diluted antiserum with P1- infected pea sap to eliminate P1- reactive antibodies. P1 and P4 RNA was detected and differentiated using pathotype-specific oligonucleotide primers in conjunction with PCR. Viral RNA sequences were amplified in pure preparations as well as crude pea tissue (leaf, root, pollen, and seed) extracts. / Graduation date: 1993

Graduation date: 1993

xv, 153 leaves : photos., graphs, tables ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Biochemistry, 1980

xii, 115 leaves : ill., tables ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Biochemistry, 1978

Thesis (Ph. D.)--University of Adelaide, 1984. / Includes bibliographical references (10 unnumbered leaves ).