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Biomedical subjects

S L Stevens

Publications and source records attributed to S L Stevens.

At least 19 recordsLinked to original sources
PubMed2006

Toll-like receptors and tolerance to ischaemic injury in the brain.

Ischaemic tolerance in the brain is a powerful adaptive defence that involves an endogenous programme of neuroprotection culminating in marked protection against brain injury from ischaemia. A range of preconditioning stimuli exist that differ in ligand and target characteristics but share the common feature of causing mild stress or insult without inducing overt injury. The protective phenotype that emerges confers tolerance to subsequent exposure to injurious insults. Tolerance to injury is the result of genomic reprogramming, an adaptation comprising regulatory processes that countermand injurious effectors and invoke novel neuroprotective pathways. TLRs (Toll-like receptors) play important roles in sensing potential danger/insult in the form of pathogens as well as endogenous stress molecules that occur in response to mild injury (e.g. heat-shock proteins). Recent studies suggest that TLRs are novel and potent preconditioning targets that offer substantial promise to protect the brain from ischaemic injury.

Brain Injuries↗
PubMed2004

The performance of various rear facing child restraint systems in a frontal crash.

Current forward facing (FF) child restraint designs use LATCH and ISOFIX systems to couple the restraint to the vehicle. Rear facing (RF) child restraints, however, have multiple coupling methods that vary by manufacturer and country of origin. Sled tests were performed with the CRABI 12 month dummy in six different RF attachment conditions. The performance of the rear facing child restraints (restraint kinematics, head accelerations, and neck loads) was highly dependent on the coupling method used. The results were also compared to a FF LATCH restraint.

Acceleration↗
PubMed2003

Erectile function after open or endovascular abdominal aortic aneurysm repair.

Open abdominal aortic aneurysm repair has been reported to be associated with impairment of sexual function in men, most likely because of autonomic nerve injury and pelvic blood flow changes. Endovascular aneurysm repair does not involve dissection in the area of the iliac bifurcation and therefore may be associated with lower incidence of sexual dysfunction as compared to open repair. We conducted a retrospective study of males after open and endovascular abdominal aortic aneurysm repair to determine if there is a significant difference in the incidence of sexual dysfunction between the two procedures. A modified International Index of Erectile Function Questionnaire was used to access sexual function before and after aneurysm repair. The questionnaire was mailed to all male patients who underwent abdominal aortic aneurysm repair from January 1, 1999 to July 15, 2002. The questionnaire asked patients questions regarding their sexual function before and 3 months after the repair. Questionnaire scores for domains of sexual function (erectile function, orgasmic function, intercourse satisfaction, and overall satisfaction) as well as the total questionnaire score were analyzed. The chi-square and Wilcoxon's signed ranks test were used for statistical comparisons, with p < 0.05 considered significant. Logistic regression was used to examine association. Two hundred ninety-three questionnaires were mailed and 90 were returned completed. There was no difference for the total questionnaire score or the erectile function score before the procedure. Based on the questionnaire score, erectile function worsened after open AAA repair ( p = 0.002). Orgasmic function also deteriorated after open AAA repair ( p = 0.001). Endovascular repair was not accompanied by decreased erectile or orgasmic function ( p = 0.057 and p = 0.068, respectively). Impairment of erectile function was not associated with age, diabetes, or the number of patent hypogastric arteries after aneurysm repair, but there was a significant association between impaired erectile function and open aneurysm repair ( p = 0.036). Endovascular repair of abdominal aortic aneurysms is associated with significantly less impairment of erectile and orgasmic function than that with open repair. Preservation of sexual function after endovascular as compared to open repair should be among the factors considered when weighing treatment options for an abdominal aortic aneurysm in a sexually active male.

Aged↗
PubMed2001

Effect of harvesting and sorting on beta-1 integrin in canine microvascular cells.

BACKGROUND: The goal of seeding prosthetic conduits with endothelial cells (ECs) has focused attention on the role of EC adhesion molecules. Cell preparation techniques may affect adhesion molecule expression and graft seeding. METHODS: Using fluorescent antibody labeling and flow cytometric analysis, this study examined the effectsof monolayer detachment (scraping vs trypsinization), timing of immunolabeling (pre- vs postdetachment), gene transfection (transfected vs nontransfected), and cell selection (antibiotic vs fluorescence sorting) techniques on beta-1 integrin expression in canine microvascular EC (K9MVEC). RESULTS: Cell scraping resulted in a significantly higher beta-1 integrin mean fluorescence intensity than did cell trypsinization (P < 0.05). No difference was observed with immunolabeling prior to versus following monolayer harvesting. Gene transfection had no significant effect on beta-1 integrin expression. No advantage was observed between cell selection methods (P > 0.05). CONCLUSION: This study suggests that the monolayer harvesting technique employed has a significant impact on beta-1 integrin quantification by flow cytometric analysis. Furthermore, microvascular EC expression of beta-1 integrin was not adversely affected by gene transfection.

Animals↗
PubMed2001

Effect of retroviral transduction of canine microvascular endothelial cells on beta(1) integrin subunit expression and cell retention to PTFE grafts.

This study evaluated the effect of retroviral transduction on canine microvascular endothelial cell (CMVEC) detachment from fibrin glue coated expanded polytetrafluoroethylene (ePTFE) graft material. CMVEC were isolated from adipose tissue by fluorescent activated cell sorting (FACS). Three treatment groups were evaluated: G-I, transduced CMVEC, selected in antibiotic G418 for 10 days (n=5); G-II, CMVEC selected in G418 and recovered from selection for 4 days (n=5); and G-III, control group of naive CMVEC (n=6). (3)H-thymidine labeled endothelial cells were seeded on fibrin glue coated four-mm diameter PTFE. Grafts were exposed to physiologic shear stresses of 16 dyn/cm(2). Cell detachment was determined by (3)H-thymidine counts in the circuit effluent. beta(1) integrin subunit expression was measured by flow cytometry. After 2 hours of flow exposure, G-I and G-II demonstrated significantly greater cell detachment rates compared with the control seeded grafts. Median peak channel beta(1) integrin subunit value for G-III CMVEC was 2311+/-481.7 vs. 31.5+/-4.51 and 26.3+/-2.0 in the transduced cell groups (p=0.00043). Low beta(1) integrin expression correlated with flow induced high detachment rates of retrovirally-transduced CMVEC.

Animals↗
PubMed2001

Influence of hormone replacement therapy on the outcome of iliac angioplasty and stenting.

OBJECTIVE: Thromboembolic events are more frequent in women with established cardiovascular disease taking hormone replacement therapy (HRT). The effect of HRT on the outcome of women with aortoiliac occlusive disease is unknown. The purpose of this study was to estimate the influence of risk factors, including HRT, on the outcome of women undergoing iliac artery angioplasty and stent placement. METHODS: During a 5-year period (between 1994 and 1999), 126 iliac angioplasties with stent placement (144 stents) were performed in 88 women. The criteria prepared by the Ad Hoc Committee on Reporting Standards (Society for Vascular Surgery/International Society for Cardiovascular Surgery) were followed to define the variables. Both univariate (Kaplan-Meier) and multivariate analyses (Cox proportional hazards model) were used to determine the association among preoperative variables, cumulative patency, limb salvage, and survival. RESULTS: The patients' average age was 63.2 years with 43% of the patients taking HRT. Indications for iliac angioplasty with stenting were disabling claudication (65%), limb salvage (32%), and blue toe syndrome (3%). The technical success rate was 95% (120 of 126 procedures). Primary stenting was performed in 28 patients (22%). Stents were placed selectively after iliac angioplasty for residual stenosis or pressure gradient (57%), iliac dissection (8%), long-segment occlusions (8%), or eccentric lesions (5%). There were no significant differences between HRT users and nonusers with regard to risk factors, except there was a higher frequency of diabetes in women taking HRT. Overall, the primary patency rate was 76% at 1 year, 67% at 3 years, and 62% at 5 years. Primary patency rates at 1, 3, and 5 years were 75%, 57%, and 49% for users of HRT and 77%, 74%, and 74%, respectively, for nonusers. Limb salvage rates were not statistically different between users and nonusers of HRT at 5 years (95% vs 96%). Univariate and Cox regression analyses identified HRT use (Kaplan-Meier, log-rank test, P = .02; relative risk, 2.4; 95% CI, 1.3-4.5; P = .006) and stent placement in the external iliac artery (relative risk, 4.3; 95% CI, 2.3-7.9; P < .001) as independent predictors of decreased primary patency. CONCLUSIONS: Women undergoing iliac angioplasty with stent placement who are taking HRT have significantly reduced primary patency rates. Despite initial technical success, HRT users are at increased risk of long-term failure and might require subsequent procedures to obtain clinical success. External iliac angioplasty and stenting are also associated with decreased primary stent patency in women.

Adult↗
PubMed2001

External iliac and common iliac artery angioplasty and stenting in men and women.

OBJECTIVE: The effect of anatomic location of stent placement on the outcome of iliac artery angioplasty and stenting is not defined. Analyses of patency rates of external iliac artery (EIA) and common iliac artery (CIA) stents have provided conflicting results and have not considered men and women independently. The purpose of this study was to estimate the influence of the anatomic location of stenting on the outcome of iliac angioplasty and stent placement in both men and women. METHODS: From 1995 to 1999, 247 iliac angioplasty and stent placement procedures (303 stents) were performed in 67 women and 122 men, and all were included in a retrospective cohort study. The criteria prepared by the Ad Hoc Committee on Reporting Standards (Society for Vascular Surgery/International Society for Cardiovascular Surgery) were followed. The TransAtlantic Inter-Society Consensus classification was used to characterize the type of iliac lesions. Both univariate (Kaplan-Meier [KM]) and multivariate analyses (Cox proportional hazards model) were used to determine the association among the variables, cumulative patency, limb salvage, and survival. RESULTS: Indications for iliac angioplasty with stenting were disabling claudication (65%), limb salvage (33%), and blue toe syndrome (2%). Primary stenting was performed in 103 procedures (42%). Stents were placed selectively after iliac angioplasty mainly for residual stenosis or pressure gradient (43%). Patients with EIA stents, as compared with those who had CIA stents, had more extensive lesions (TransAtlantic Inter-Society Consensus type C lesions), poorer runoff, smaller vessel size, and less frequency of hyperlipidemia (P <.05). Primary patency rates at 1, 3, and 5 years were 76%, 56%, and 56%, respectively, for patients with EIA stents and 92%, 85%, and 76%, respectively, for those with CIA stents. Although overall primary patency rates were significantly decreased in patients with EIA lesions (KM, log-rank test, P =.001), stratified analyses revealed that women with EIA stents had the poorest outcome, with 61%, 47%, and 23% primary patency rates at 1, 3, and 5 years, respectively, (KM, log-rank test, P <.001). Cox regression analysis identified EIA stenting (relative risk, 4.3; 95% CI, 2.3-7.9; P <.001) as an independent predictor of decreased primary patency in women but not in men. CONCLUSIONS: Women undergoing EIA angioplasty with stent placement have significantly reduced primary patency rates. Despite initial technical success, these patients are at increased risk of long-term failure and might require subsequent procedures to obtain clinical success. Conversely, men undergoing EIA stenting have a more favorable outcome than women.

Adult↗
PubMed2001

Infrainguinal arterial reconstructions in patients with aortoiliac occlusive disease: the influence of iliac stenting.

OBJECTIVE: Iliac artery angioplasty (IAA) is an effective adjunct when combined with infrainguinal arterial reconstructions (IARs) in appropriate patients with multilevel occlusive disease. However, the effect of iliac artery stenting (IAS) on the outcome of patients undergoing distal bypass procedures is not defined. The purpose of this study was to estimate the influence of previous IAS for iliac occlusive disease on the outcome of IARs, compared with those after IAA alone or aortofemoral bypass grafting procedures (AFBs). METHODS: During a 5-year period (1995-2000), 105 patients with previous intervention for iliac occlusive disease underwent 120 IARs. The criteria prepared by the Ad Hoc Committee on Reporting Standards (Society for Vascular Surgery/International Society for Cardiovascular Surgery) were followed to define the variables. The TransAtlantic Inter-Society Consensus classification was used to characterize the type of iliac lesions. Univariate (Kaplan-Meier) and multivariate analyses (Cox proportional hazards model) were used to determine the association between preoperative variables and cumulative primary patency. RESULTS: Forty-five IARs were performed in patients with an earlier IAS repair, 33 in patients with an earlier IAA repair, and 42 in patients with an earlier AFB repair. There were not significant differences between patients in the IAS and IAA groups, except for a more frequent use of polytetrafluoroethylene grafts for IARs in the IAS group (40% vs 15%; chi(2) test, P = .03). The 5-year primary patency rate for IARs was 68% in the IAS group, 46% in the IAA group, and 61% in the AFB group. Univariate analyses revealed that primary patency rates for IARs in patients with previous IAS were significantly higher than those in the IAA group (Kaplan-Meier, log-rank test, P = .02). Previous IAA repair was associated with a two-fold increased risk of IAR graft failure (relative risk, 2.2; 95% CI, 1.1-4.8; P = .04). CONCLUSIONS: IARs in patients with previous IAS have significantly improved graft patency, compared with those in patients with previous IAA alone. Such graft patency for IAR after IAS is similar to that obtained after AFB repair.

Adult↗
PubMed2001

IL-1alpha and TNFalpha down-regulate CRH receptor-2 mRNA expression in the mouse heart.

Two receptors (CRH receptor type 1 and CRH receptor type 2) have been identified for the stress-induced neuropeptide, CRH and related peptides, urocortin, and urocortin II. We previously found marked down-regulation of cardiac CRH receptor type 2 expression following administration of bacterial endotoxin, lipopolysaccharide, a model of systemic immune activation, and inflammation. We postulated that inflammatory cytokines may regulate CRH receptor type 2. We show that systemic IL-1alpha administration significantly down-regulates CRH receptor type 2 mRNA in mouse heart. In addition, TNFalpha treatment also reduces CRH receptor type 2 mRNA expression, although the effect was not as marked as with IL-1alpha. However, CRH receptor type 2 mRNA expression is not altered in adult mouse ventricular cardiomyocytes stimulated in vitro with TNFalpha or IL-1alpha. Thus, cytokine regulation may be indirect. Exogenous administration of corticosterone in vivo or acute restraint stress also reduces cardiac CRH receptor type 2 mRNA expression, but like cytokines, in vitro corticosterone treatment does not modulate expression in cardiomyocytes. Interestingly, treatment with urocortin significantly decreases CRH receptor type 2 mRNA in cultured cardiomyocytes. We speculate that in vivo, inflammatory mediators such as lipopolysaccharide and/or cytokines may increase urocortin, which in turn down-regulates CRH receptor type 2 expression in the heart. Because CRH and urocortin increase cardiac contractility and coronary blood flow, impaired CRH receptor type 2 function during systemic inflammation may ultimately diminish the adaptive cardiac response to adverse conditions.

Animals↗
PubMed2000

Heparin-induced thrombocytopenia.

Heparin-induced thrombocytopenia is a rare but complex adverse drug reaction that can produce devastating results. Treatment and clinical management of the patient requires close observation and education of the pathophysiology occurring at the cellular level. Documented cases of heparin-induced thrombocytopenia have been reported in the literature for years. This case presentation details a multiple trauma patient in whom heparin-induced thrombocytopenia developed and the effect this syndrome had on her treatment and eventual recovery.

Anticoagulants↗
PubMed2000

Abnormal adaptations to stress and impaired cardiovascular function in mice lacking corticotropin-releasing hormone receptor-2.

The actions of corticotropin-releasing hormone (Crh), a mediator of endocrine and behavioural responses to stress, and the related hormone urocortin (Ucn) are coordinated by two receptors, Crhr1 (encoded by Crhr) and Crhr2. These receptors may exhibit distinct functions due to unique tissue distribution and pharmacology. Crhr-null mice have defined central functions for Crhr1 in anxiety and neuroendocrine stress responses. Here we generate Crhr2-/- mice and show that Crhr2 supplies regulatory features to the hypothalamic-pituitary-adrenal axis (HPA) stress response. Although initiation of the stress response appears to be normal, Crhr2-/- mice show early termination of adrenocorticotropic hormone (Acth) release, suggesting that Crhr2 is involved in maintaining HPA drive. Crhr2 also appears to modify the recovery phase of the HPA response, as corticosterone levels remain elevated 90 minutes after stress in Crhr2-/- mice. In addition, stress-coping behaviours associated with dearousal are reduced in Crhr2-/- mice. We also demonstrate that Crhr2 is essential for sustained feeding suppression (hypophagia) induced by Ucn. Feeding is initially suppressed in Crhr2-/- mice following Ucn, but Crhr2-/- mice recover more rapidly and completely than do wild-type mice. In addition to central nervous system effects, we found that, in contrast to wild-type mice, Crhr2-/- mice fail to show the enhanced cardiac performance or reduced blood pressure associated with systemic Ucn, suggesting that Crhr2 mediates these peripheral haemodynamic effects. Moreover, Crhr2-/- mice have elevated basal blood pressure, demonstrating that Crhr2 participates in cardiovascular homeostasis. Our results identify specific responses in the brain and periphery that involve Crhr2.

Adaptation, Physiological↗
PubMed2000

Influence of hormone replacement therapy on graft patency after femoropopliteal bypass grafting.

OBJECTIVE: Thromboembolic events are more frequent in women with established cardiovascular disease who are receiving hormone replacement therapy (HRT). The effect of HRT on the outcome of women undergoing infrainguinal bypass grafting is unknown. The purpose of this study was to estimate the influence of risk factors, in particular HRT, on the outcome of women undergoing femoropopliteal bypass grafting. METHODS: During a 5-year period (between 1993 and 1998), 131 femoropopliteal bypass graft procedures were performed in 106 women. The criteria prepared by the Ad Hoc Committee on Reporting Standards (Society for Vascular Surgery/North American Chapter of the International Society for Cardiovascular Surgery) were followed. Both univariate (Kaplan-Meier method) and multivariate analyses (Cox proportional hazards model) were used to determine the association among preoperative variables, graft patency, limb salvage, and survival. RESULTS: The average age of the patients was 66.4 years; 26% of the patients were receiving HRT. Indications for femoropopliteal bypass grafting were limb salvage (80%) and disabling claudication (20%). Autogenous vein was used in 48% of procedures, polytetrafluoroethylene (PTFE) in 49%, and PTFE-vein composite grafts in 3%. Distal popliteal anastomosis was above the knee in 52% and below the knee in 48%. Overall primary patency rate was 81% at 1 year, 65% at 3 years, and 56% at 5 years. Primary patency rates at 1, 3, and 5 years were 75%, 45%, and 23%, respectively, for HRT users and 84%, 72%, and 65%, respectively, for nonusers of HRT. Overall, cumulative 1- and 5-year limb salvage results were 96% and 92%, respectively, and long-term survival at 1, 3, and 5 years was 96%, 86% and 74%, respectively. With univariate and Cox regression analyses, HRT was identified as the only independent predictor of reduced primary graft patency (Kaplan-Meier method, log-rank test, P =.004; relative risk, 2.5; 95% CI, 1.3-4.8). Women receiving HRT who underwent a procedure with PTFE had the lowest primary graft patency rates (relative risk, 3.4; 95% CI, 1. 5-7.8; P =.006). CONCLUSIONS: Women undergoing femoropopliteal bypass graft procedures who are receiving HRT have significantly reduced primary graft patency rates. The risk of graft failure increases when prosthetic materials are used.

Aged↗
PubMed2000

Vascular smooth muscle cell apoptosis in aneurysmal, occlusive, and normal human aortas.

PURPOSE: Apoptosis is a physiologic mechanism of cell death that regulates mass and architecture in many tissues. Apoptosis has been described as a feature in human vascular atherosclerosis and large vessel structural integrity. We examined the extent of vascular smooth muscle cell (VSMC) apoptosis in aneurysmal, occlusive, and normal human aortic tissue. METHODS: Tissue samples of aneurysmal, occlusive, and normal human infrarenal aorta were evaluated. DNA fragmentation detection methods, immunohistochemistry, and DNA electrophoresis determined VSMC density, VSMC apoptosis, and apoptosis markers. Apoptotic cells and VSMC nuclei were counted with the use of computer-generated image analysis. Aortic subtypes were compared statistically by analysis of variance. RESULTS: Seventeen aneurysmal, ten occlusive, and five normal human aortas were evaluated. By alpha(1)-actin immunostaining, VSMC density was least in aneurysmal aortas (271.8 +/- 13.5 cells/high-power field [HPF]) compared with occlusive aorta (278.2 +/- 39.4 cells/HPF) and normal aortas (291.0 +/- 25.4 cells/HPF; P = not significant). Presence of apoptotic VSMCs was demonstrated by terminal deoxynucleotidyl transferase fragment end labeling and propidium iodide nuclear staining. VSMC apoptosis was greatest within aneurysmal aortas with 11.7 +/- 1.5 cells/HPF compared with occlusive aortas with 3.3 +/- 0. 8 cells/HPF (P <.05) and normal aortas with 3.75 +/- 4.6 cells/HPF (P <.05). Significant differences in apoptosis markers, p53 or bcl-2, could not be demonstrated by immunohistochemistry or DNA electrophoresis in aortic subtypes. CONCLUSION: Apoptosis of VSMCs is increased and VSMC density is decreased within the medial layer of aneurysmal aortic tissue. Structural degeneration of aortic tissue at the cellular level contributes to aneurysmal formation.

Aged↗
PubMed1999

Factors affecting the surgical management of infective endocarditis.

Congestive heart failure and septic embolism complicate the clinical course of patients with infective endocarditis (IE). This study reviews the clinical records of patients with systemic disease secondary to IE and stratifies their disease severity according to individual risk factors and medical, and surgical interventions. The hospital records of all patients presenting to our institution from 1992 through 1997 with heart valve destruction secondary to IE were reviewed. Ten patients with hemodynamically significant valve lesions were included in this study: seven with aortic valve disease and two with mitral valve disease, and one with combined aortic and mitral valve lesions. All were diagnosed by echocardiogram. All ten patients experienced systemic septic arterial emboli: four intracranial lesions, four visceral lesions, and three extremity arterial occlusive events. Two patients required peripheral arterial repair. Cultures revealed infection secondary to Staphylococcus aureus in five, Streptococcus species in three, Coxiella species in one, and an unidentified organism in one patient. Seven patients underwent valve replacement. Three patients died from their disease processes. Statistical significance was established by Wilcoxon rank analysis with a two-tailed P < 0.05. Patients with IE secondary to staphylococcal infections suffered a more acute and virulent disease process (P = 0.04), with a 40 per cent mortality rate in the first 48 hours. There was no increased incidence of embolization associated with longer duration of symptoms (P = 0.32). Surgical repair conferred improved clinical outcome as compared with no surgical intervention (P = 0.03). Improved patient outcome was associated with nonstaphylococcal infection (P = 0.02), and a successful initial antibiotic regimen (P = 0.03). Peripheral arterial repair was successful in both cases.

Acute Disease↗
PubMed1998

Mesenteric pseudoaneurysm resulting from septic embolism.

Symptomatic peripheral septic embolism is a rare systemic complication of infective endocarditis. This case report describes abdominal pain secondary to a septic pseudoaneurysm in the distal superior mesenteric artery. Presentation, imaging, surgical intervention, and histologic evaluation are described, and a review of recent literature relating to this phenomenon is outlined.

Abdominal Pain↗
PubMed1997

Retroviral mediated gene transduction alters integrin expression on vascular endothelial cells.

Genetically recombinant endothelial cells (rEC) may improve the patency of small diameter vascular grafts by preventing thrombosis or limiting neointimal hyperplasia. Previous work has shown that rEC have reduced adhesion to vascular bypass grafts in vivo. Poor adhesion may be due to altered adhesion (integrin) receptors. This study evaluated the expression of the alpha 5 beta 1 (fibronectin), alpha 2 beta 1 (collagen IV), and alpha v beta 3 (vitronectin) integrin subunits on rEC. Human umbilical vein EC or canine jugular vein EC were transduced with neoR, neoR and human tPA or hygromycin resistance genes using retroviral vectors. Naive EC and EC exposed to empty viral particles (mEC) were controls. Naive EC, mEC, and all rEC's were evaluated for alpha and beta subunits for each integrin receptor studied using immunoblotting. Blotting for alpha 2, alpha 5, and alpha v exhibited expression of the alpha integrin subunits in all cells. The beta 1 and beta 3 subunits were present in mEC and nEC but were absent or truncated in all rEC. The decreased adhesion of rEC's to synthetic vascular grafts may be accounted for by their altered beta 1 and beta 3 integrin subunit expression. The beta subunit is critical for organization of the cytoskeleton and cellular signal transduction. Diminished beta subunit expression in rEC is neither vector specific nor related to retroviral exposure alone. Alteration of beta integrin expression may be to associated with the over-expression of phosphotransferase genes such as neoR or hygromycin B used as selectable markers in gene transfer protocols.

Animals↗
PubMed1997

Healing characteristics of intraarterial stent grafts in an injured artery model.

Previous investigations reveal in the absence of endothelial cell (EC) injury, intraarterial polytetrafluoroethylene (PTFE) stent graft (SG) exhibit greater EC repaving than PTFE interposition grafts (CG). The investigation evaluated EC repaving of SG compared to CG after balloon injury. Twenty adult dogs underwent SG (n = 10) or CG (n = 10) placement in the infrarenal aorta after balloon injury with harvest at 1 and 6 weeks. Endothelial repaving, intima-to-media height ratios (IMHR), and inflammatory stains were performed. Endothelial repaving was greater in 6-week SG compared to CG (51% +/- 5.0 versus 10% +/- 5.0, p < or = 0.05). IMHR was less in 6-week SG compared to CG at the proximal (1.22 +/- 0.16 versus 1.82 +/- 0.16, p < or = 0.05) and distal anastomosis (0.81 +/- 0.25 versus 1.33 +/- 0.25, p < or = 0.05). Smooth muscle cell (SMC) alpha-actin was greater in 1-week SG compared to CG at the distal anastomosis (121.5 +/- 7.2 versus 94.0 +/- 7.2, p < or = 0.05). Proliferating cell nuclear antigen (PCNA) was less in 6-week SG compared to CG at the proximal (5.6 +/- 1.4 versus 9.4 +/- 1.1, p < or = 0.05) and distal anastomosis (3.8 +/- 0.6 versus 11.2 +/- 1.1, p < or = 0.05). Macrophage CD-44 was less in 6-week SG compared to CG at the proximal (10.4 +/- 1.6 versus 32.6 +/- 3.6, p < or = 0.05) and distal anastomosis (8.6 +/- 0.9 versus 35.6 +/- 3.6, p < or = 0.05). Intraarterial SG placed after balloon injury exhibited significantly greater endothelialization and less intimal hyperplasia when compared to CG.

Animals↗