Biomedical subjects

M D Colburn

Publications and source records attributed to M D Colburn.

24 records · Page 2Linked to original sources

PubMed1992

Heparin, urokinase, and ancrod alter neutrophil function.

Neutrophils (polymorphonuclear neutrophils [PMNs]) have been implicated as mediators of reperfusion injury. Heparin, urokinase, and ancrod are agents used routinely to prevent and treat thrombosis, yet their effects on PMN function are unknown. Therefore human PMNs were obtained and incubated for 30 minutes with either saline solution or one of the following pharmacologic agents, each tested at three different concentrations: group 1, saline solution (control, n = 14); groups 2 through 4, heparin (5000 units/ml, n = 8; 2500 units/ml, n = 6; and 1250 units/ml, n = 6, respectively); groups 5 through 7, urokinase (50,000 units/ml, n = 8; 25,000 units/ml, n = 6; and 12,500 units/ml, n = 6, respectively), and groups 8 through 10, ancrod (70 units/ml, n = 8; 35 units/ml, n = 6; and 17.5 units/ml, n = 6). Superoxide anion production was measured by the reduction of cytochrome c in a spectrophotometric assay. Chemotaxis was evaluated by the number of PMNs migrating across a filter with a Neuro Probe chamber (Neuro Probe, Cabin John, Md.). Phagocytosis was determined by the ingestion of opsonized zymosan particles by PMNs. Serum obtained from each PMN donor was used both to opsonize the zymosan and as a chemoattractant in the chemotaxis assay. Statistical comparison was evaluated by analysis of variance, and post hoc comparisons for each agent with control were performed with the unpaired Student t test. No agent, at any dose, significantly changed superoxide anion production compared with control cells. All three agents significantly inhibited PMN chemotaxis (p < 0.01). In the control group the number of PMNs counted was 27.6 +/- 4.9.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗

PubMed1992

Use of an antibiotic-bonded graft for in situ reconstruction after prosthetic graft infections.

We have developed an infection resistant vascular prosthesis by bonding rifampin to Dacron grafts with the use of a collagen matrix release system. The purpose of this study was to determine the efficacy of this antibiotic-bonded graft in resisting infection after an in situ reconstruction of a previously infected prosthetic bypass. Eighty-three adult mongrel dogs underwent implantation of a 3 cm untreated Dacron graft into the infrarenal aorta. This initial graft was deliberately infected, at the time of operation, with 10(2) organisms of Staphylococcus aureus by direct inoculation. One week later, the dogs were reexplored, the retroperitoneum debrided, and the animals randomized to undergo an end-to-end in situ graft replacement with either one of two types of prosthetic grafts: group I (collagen, n = 36) received control collagen-impregnated knitted Dacron grafts; group II (rifampin, n = 47) received experimental collagen-rifampin-bonded Dacron grafts. Each group of animals was then subdivided to receive one of four treatment protocols: (a) no antibiotic therapy, (b) cephalosporin peritoneal irrigation solution (cefazolin 500 mg/1000 ml) during operation and two doses of cephalosporin (cefazolin, 500 mg intramuscularly) postoperatively, (c) treatment as in protocol group b plus 1 week of cephalosporin (cefazolin, 500 mg intramuscularly, twice daily), and (d) treatment as in protocol group b plus 2 weeks of cephalosporin (cefazolin, 500 mg intramuscularly, twice daily). All grafts were sterilely removed between 3 and 4 weeks after implantation. There were no anastomotic disruptions and all grafts were patent at the time of removal.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1992

Neonatal aortic thrombosis.

Thrombosis of the aorta in the neonate is a potentially catastrophic event. The incidence of this problem has increased concomitantly with the widespread use of umbilical artery catheters in the management of infants who are critically ill. The natural history and appropriate management of this complication has not been well established. This is due in part to the wide spectrum of presentations and lack of consensus regarding its classification. Aortic thrombosis may vary from deposition of a fibrin sheath surrounding the length of an umbilical artery catheter to aggregates of nonocclusive thrombus within the aorta or to complete occlusion of the aorta and concomitant occlusion of its main branches. The reported treatments recommended for this problem have ranged from supportive care only to mandatory surgical intervention in all cases. This spectrum of advocated therapies has resulted in considerable confusion regarding the proper management of this problem. This paper presents two cases of neonatal aortic thrombosis: one case was treated medically and the other case was treated with surgical intervention. We review these cases and the current literature, with specific attention directed towards highlighting the critical elements involved in formulating a reasonable approach to the management of neonatal aortic thrombosis. In addition, we offer an algorithm for management of these patients according to the degree of aortic thrombosis, severity of systemic manifestations, and the general condition of each individual patient.

Aortic Diseases↗

PubMed1991

Prevention of graft infection by use of prostheses bonded with a rifampin/collagen release system.

The objective of this study was to test the efficacy of bonding rifampin to double-velour Dacron grafts with collagen to prevent graft sepsis. Fifty 6.0 mm Dacron grafts (length 5.0 cm) impregnated with either collagen (control) or collagen plus rifampin (experimental) were implanted in dogs end-to-end into the infrarenal aorta. The dogs were divided into four groups (each with an experimental and control subdivision) as a function of time between grafting and bacterial challenge. At 2, 7, 10, or 12 days after graft implantation, sequential groups were challenged with 1.2 x 10(8) colony forming units of Staphylococcus aureus (clinical isolate) intravenously suspended in 250 ml normal saline. Three weeks after hematogenous seeding, the grafts were sterilely harvested. One-tailed Fisher's exact test was used to compare the patency and culture-proven infection of control and antibiotic coated grafts as a function of implantation time before bacteremic challenge. In the 2-day group, four of six control grafts were infected compared with zero of six experimental grafts (p less than 0.030). In the 7-day group, five of six control grafts were infected with S. aureus versus zero of six in the experimental group (p less than 0.008). In the 10-day group, one of six experimental grafts was infected, but the control group had only two of six graft infections. In the 12-day group two of six experimental grafts and one of five control grafts were infected. These results indicate that rifampin bonded with collagen to knitted Dacron grafts will protect the graft from bacteremic infection for 7 days after implantation in a highly challenging model.(ABSTRACT TRUNCATED AT 250 WORDS)

Anastomosis, Surgical↗

PubMedDate not supplied

Endovascular repair of abdominal aortic aneurysms using the EGS tube and bifurcated graft systems.

Left untreated, aneurysmal disease of the abdominal aorta is a highly lethal condition. Standard transabdominal repair of aortic aneurysm, although successful and durable, continues to be plagued by significant morbidity, mortality, and cost. Placement of an endovascular graft through a femoral arteriotomy is a new technique that could potentially reduced this morbidity and cost without sacrificing efficacy. This report details the development of a U.S. Food and Drug Administration (FDA)-approved endovascular grafting device. In addition, we describe our experience screening patients and summarize our clinical experience with the placement of both tube and bifurcated endovascular graft systems. To date, 16 patients have undergone endovascular repair with a tube graft at UCLA, and three bifurcated grafts have been placed. Two patients required conversion to conventional open aneurysm repair. All the remaining procedures were successful, and there were no perioperative deaths or major complications. We conclude that endovascular grafting of aortic aneurysms is both feasible and safe. Long-term patency and the ability of this technique to prevent the known complications of aortic aneurysmal disease remain unanswered questions at this time.

Angioplasty, Balloon↗

PubMedDate not supplied

Buerger's disease.

Explore the source record for details and available documents.

Adult↗