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D R Jordan

Publications and source records attributed to D R Jordan.

At least 19 recordsLinked to original sources
PubMed2005

Resistance gene analogues in sugarcane and sorghum and their association with quantitative trait loci for rust resistance.

Fifty-four different sugarcane resistance gene analogue (RGA) sequences were isolated, characterized, and used to identify molecular markers linked to major disease-resistance loci in sugarcane. Ten RGAs were identified from a sugarcane stem expressed sequence tag (EST) library; the remaining 44 were isolated from sugarcane stem, leaf, and root tissue using primers designed to conserved RGA motifs. The map location of 31 of the RGAs was determined in sugarcane and compared with the location of quantitative trait loci (QTL) for brown rust resistance. After 2 years of phenotyping, 3 RGAs were shown to generate markers that were significantly associated with resistance to this disease. To assist in the understanding of the complex genetic structure of sugarcane, 17 of the 31 RGAs were also mapped in sorghum. Comparative mapping between sugarcane and sorghum revealed syntenic localization of several RGA clusters. The 3 brown rust associated RGAs were shown to map to the same linkage group (LG) in sorghum with 2 mapping to one region and the third to a region previously shown to contain a major rust-resistance QTL in sorghum. These results illustrate the value of using RGAs for the identification of markers linked to disease resistance loci and the value of simultaneous mapping in sugarcane and sorghum.

Chromosome Mapping↗
PubMed2004

Fibrovascularization of porous polyethylene (Medpor) orbital implant in a rabbit model.

PURPOSE: To evaluate the porous polyethylene (Medpor) orbital implant in a rabbit model and compare it with three other currently available porous implants: Bio-Eye coralline hydroxyapatite (HA), FCI(3) synthetic HA, and aluminum oxide (Bioceramic). METHODS: The porous polyethylene implant was examined macroscopically and microscopically (with scanning electron microscopy). Implantation was performed in 10 adult male New Zealand albino rabbits. Each animal underwent enucleation of the right globe under general halothane gas anesthesia, followed by placement of a 12-mm porous polyethylene implant. In 5 animals, the implant was encased in polyglactin 910 (Vicryl mesh); in the other 5, it was left unwrapped. The implants were moistened in saline before placement. Implant vascularization was evaluated by histopathology at 4, 8, 12, 16, and 24 weeks. RESULTS: The porous polyethylene implant was found to have a smoother exterior surface than the Bio-Eye, FCI(3) synthetic HA, and aluminum oxide implants. Rather than a uniform interconnected porous architecture, there was an extensive system of interconnected channels through the implant, ranging in size from 125 to 1000 microm. On high-power examination there was a more solid, woven appearance without any sign of the microcrystals seen in the other porous implants. One rabbit had a retrobulbar hemorrhage after surgery and was euthanized. All the other rabbits tolerated the implant well, and there were no complications. On histopathologic examination, fibrovascularization gradually increased over time. One implant was completely vascularized at 12 weeks, and both implants harvested at 16 weeks were completely vascularized. The implant harvested at 24 weeks showed only partial vascularization (14%). CONCLUSIONS: The porous polyethylene orbital implant represents an alternative implant for use after enucleation or evisceration or for secondary implantation. In our rabbit model, the porous polyethylene implant was well tolerated without complication. Complete fibrovascularization was first seen at 12 weeks. Porous polyethylene orbital implants appear to vascularize more slowly than Bio-Eye coralline HA, FCI(3) synthetic HA, and aluminum oxide implants.

Animals↗
PubMed2004

Markers associated with stalk number and suckering in sugarcane colocate with tillering and rhizomatousness QTLs in sorghum.

Two important factors influencing sugar yield, the primary focus of sugarcane plant breeding programs, are stalk number and suckering. Molecular markers linked to both of these traits are sought to assist in the identification of high sugar yield, high stalk number, low-suckering sugarcane clones. In this preliminary mapping study, 108 progeny from a biparental cross involving two elite Australian sugarcane clones were evaluated at two sites for two years for both stalk number and suckering. A total of 258 DNA markers, including both restriction fragment length polymorphisms (RFLPs) and radio-labelled amplified fragments (RAFs), were scored and evaluated using single-factor analysis. Sixteen (7 RFLPs and 9 RAFs) and 14 (6 RFLPs and 8 RAFs) markers were identified that were significantly associated (P < 0.01) with stalk number and suckering, respectively, across both years and sites. The seven and six RFLP markers associated with stalk number and suckering, respectively, were generated by eight different RFLP probes, of which seven had been mapped in sorghum and (or) sugarcane. Of significant interest was the observation that all seven RFLP probes could be shown to be located within or near QTLs associated with tillering and rhizomatousness in sorghum. This observation highlights the usefulness of comparative mapping between sorghum and sugarcane and suggests that the identification of useful markers for stalk number and suckering in sugarcane would be facilitated by focussing on sorghum QTLs associated with related traits.

Chromosome Mapping↗
PubMed2003

Identifications of two different mechanisms for sorghum midge resistance through QTL mapping.

Sorghum midge is the one of the most damaging insect pests of grain sorghum production worldwide. At least three different mechanisms are involved in midge resistance. The genetic bases of these mechanisms, however, are poorly understood. In this study, for the first time, quantitative trait loci associated with two of the mechanisms of midge resistance, antixenosis and antibiosis, were identified in an RI (recombinant inbred) population from the cross of sorghum lines ICSV745 x 90562. Two genetic regions located on separate linkage groups were found to be associated with antixenosis and explained 12% and 15%, respectively, of the total variation in egg numbers/spikelet laid in a cage experiment. One region was significantly associated with antibiosis and explained 34.5% of the variation of the difference of egg and pupal counts in the RI population. The identification of genes for different mechanisms of midge resistance will be particularly useful for exploring new sources of midge resistance and for gene pyramiding of different mechanisms for increased security in sorghum breeding through marker-assisted selection.

Animals↗
PubMed2002

Prediction of hybrid performance in grain sorghum using RFLP markers.

Heterosis is an important component of hybrid yield performance. Identifying high yielding hybrids is expensive and involves testing large numbers of hybrid combinations in multi-environment trials. Molecular marker diversity has been proposed as a more efficient method of selecting superior combinations. The aim of this study was to investigate the value of molecular marker-based distance information to identify high yielding grain sorghum hybrids in Australia. Data from 48 trials were used to produce hybrid performance-estimates for four traits (yield, height, maturity and stay green) for 162 hybrid combinations derived from 70 inbred parent lines. Each line was screened with 113 mapped RFLP markers. The Rogers distances between the parents of each hybrid were calculated from the marker information on a genome basis and individually for each of the ten linkage groups of sorghum. Some of the inbred parents were related so the hybrids were classified into 75 groups with each group containing individual hybrids that showed similar patterns of Rogers distances across linkage groups. Correlations between hybrid-group performance and hybrid-group Rogers distances were calculated. A significant correlation was observed between whole genome-based Rogers distance and yield ( r = 0.42). This association is too weak to be of value for identifying superior hybrid combinations. One reason for the generally poor association between parental genetic diversity and yield may be that important QTLs influencing heterosis are located in particular chromosome regions and not distributed evenly over the genome. Variation in the sign and magnitude of correlations between Rogers distance and hybrid-group performance for particular linkage groups observed in this study support this hypothesis. The concept of using diversity on individual linkage groups to predict performance was explored. Using data from just two linkage groups 38% of the variation in hybrid performance for grain yield could be explained. A model combining phenotypic trait data and parental diversity on particular linkage groups explained 71% of the variation in grain yield and has potential for use in the selection of heterotic hybrids.

Australia↗
PubMed2001

Proliferation of human fibroblasts in vitro after exposure to orbital implants.

BACKGROUND: Porous orbital implants allow fibrovascular ingrowth and integration with the extraocular muscles. The available implants have different structural characteristics, which may influence orbital response. We studied the proliferation of orbital fibroblasts in vitro after exposure to four different orbital implants. METHODS: Four orbital implant biomaterials were studied: hydroxyapatite (Bio-Eye), synthetic hydroxyapatite, porous polyethylene (Medpor) (pore sizes 150 microm and 400 microm) and aluminium oxide (Bioceramic implant). Human fibroblasts obtained from orbital fat at the time of elective blepharoplasty were cultured and then exposed to the individual implants. Cell growth was assessed with immunocytochemical analysis using bromodeoxyuridine, a thymidine analogue. After DNA denaturation, the cells were washed, incubated with secondary antibody and visualized. RESULTS: The fibroblasts growing on the Bio-Eye, synthetic hydroxyapatite, and 150-microm and 400-microm Medpor implants all had debris associated with them. The Bioceramic implant was free of this debris. The Bioceramic implant and the 150-microm Medpor implant had the greatest number of fibroblasts on the coverslips. INTERPRETATION: The proliferation of fibroblasts, as determined by visualization of actively dividing cells with bromodeoxyuridine, differed on the various implants studied. The lack of debris associated with the Bioceramic implant may be related to the crystalline structure of the implant.

Aluminum Oxide↗
PubMed2001

Pyogenic granuloma following oculoplastic procedures: an imbalance in angiogenesis regulation?

BACKGROUND: Pyogenic granuloma is a vasoproliferative inflammatory response composed of granulation tissue. The pathogenesis is not entirely clear. We describe a series of patients with pyogenic granulomas occurring following common oculoplastic procedures and propose a common etiology. METHODS: Sixteen cases of pyogenic granuloma that occurred after various oculoplastic procedures from 1991 to 2000 were collected from the files of two oculoplastic surgeons. RESULTS: Pyogenic granulomas were found to occur at surgical and nonsurgical sites associated with tissue irritation or inflammation or both. INTERPRETATION: Capillaries are a predominant component of wound healing and pyogenic granulomas. The growth and development of new capillaries follows an orderly sequence of events that is highly regulated by a variety of angiogenic factors. We postulate an imbalance in angiogenesis regulation as the common pathway for pyogenic granuloma development.

Adolescent↗
PubMed2001

Spontaneous loosening of hydroxyapatite peg sleeves.

OBJECTIVE: To report a new complication associated with pegging hydroxyapatite orbital implants: spontaneous loosening of the sleeve. DESIGN: Retrospective noncomparative case series. PARTICIPANTS: Four patients ranging in age from 38 to 60 years participated. METHODS: Four patients are described who successfully received hydroxyapatite orbital implants with motility peg and sleeve systems. In each case spontaneous loosening of the sleeve developed. MAIN OUTCOME MEASURE: Clinical and surgical outcomes were assessed. RESULTS: Three patients had the peg and sleeve removed followed by repair of the peg hole, and one patient had placement of a larger diameter peg and sleeve system. All patients did well. CONCLUSIONS: Problems have been reported when motility coupling pegs are used with hydroxyapatite orbital implants. Spontaneous loosening of the sleeve is another potential complication to discuss with the patient considering an implant peg.

Adult↗
PubMed2001

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Anterior Eye Segment↗
PubMed2001

Experience with 120 synthetic hydroxyapatite implants (FCI3).

PURPOSE: To assess the problems and/or complications associated with the use of a synthetic hydroxyapatite implant (FCI, Cedex, France). METHODS: The authors analyzed all of the problems and/or complications associated with the use of a third-generation synthetic hydroxyapatite implant (FCI3) in 120 patients by one surgeon over 4 years. The following data were recorded: age, type of surgery performed, size of implant used, peg system used, follow-up duration, time of pegging, problems and/or complications encountered, and treatment. RESULTS: Thirteen patients were lost to follow-up after 3 months, leaving 107 patients who were followed up from 4 to 48 months (average, 29 months). Discharge occurred in 21 (19.6%) patients, implant exposure in 3 (2.8%), socket discomfort in 2 (1.9%), trochleitis in 2 (1.9%), conjunctival thinning in 1 (0.93%), and pyogenic granuloma in 1 (0.93%). Peg problems occurred in 24 (35.2%) of 68 patients. Problems encountered with the peg were discharge in 10 (14.7%) patients, pyogenic granuloma in 9 (13.2%), conjunctiva overgrowing the peg in 4 (5.8%), hydroxyapatite exposure around the sleeve in 3 (4.4%), loose sleeve in 3 (4.4%), peg drilled on an angle in 1 (1.5%), implant infection in 1 (1.5%), and peg falling out in 1 (1.5%). CONCLUSIONS: The FCI3 synthetic hydroxyapatite is a less costly alternative form of hydroxyapatite currently in use in many parts of the world. Problems and complications encountered with its use are similar to those seen with the Bio-Eye Integrated Orbital Implants, Inc., San Diego, CA, U.S.A. The incidence of exposure associated with the synthetic hydroxyapatite implant is lower than several other reports on the Bio-Eye. The synthetic hydroxyapatite implant is slightly softer than the Bio-Eye and fractured under extreme pressure in one case.

Adult↗