A comparison of four stent designs on arterial injury, cellular proliferation, neointima formation, and arterial dimensions in an experimental porcine model.

The stent-artery interactions of different stent designs have implications for their clinical effects. We studied four different stent designs to compare their effects on arterial injury, cellular proliferation, neointima formation, and arterial dimensions. Eighteen nonatherosclerotic miniswine underwent random placement of 52 coronary stents (3.0 mm), including self-expanding nitinol stents (no postdilation; Radius, n = 13) and balloon-expandable stents (8 atm x 45 sec; Palmaz-Schatz, n = 13; BX, n = 12; and Multilink, n = 14). Cellular proliferation was determined by S-phase labeling with BrdU at 7, 14, and 28 days. Proliferation, injury scores, and arterial morphometry were blindly evaluated. All four stent designs had similar injury scores, cellular proliferation indexes (neointimal and medial), and adventitial areas. Nitinol stents resulted in a twofold increase in neointimal area and thickness in 28-day vessels (P = 0.002). However, lumen area was similar for all stent designs because of an offsetting expansion in vessel area in nitinol stents (20% greater than balloon-expandable stents) occurring between 7 and 14 days after stent deployment (P = 0.03). Reduced neointimal cell density in nitinol stents (20% less than balloon-expandable stents, P = 0.012) suggests that extracellular matrix expansion accounts for the larger neointima in nitinol stents. Self-expansion of nitinol stents within normal porcine arteries results in a similar degree of arterial injury compared to balloon-expandable stent designs. Progressive enlargement of nitinol stents between 7 and 14 days after deployment is associated with the development of a larger, matrix-rich neointima, with a preserved lumen area. Cathet Cardiovasc Intervent 2001;53:420-425. Published 2001 Wiley-Liss, Inc.

The 90-day coronary vascular response to (90)Y-beta particle-emitting stents in the canine model.

PURPOSE: Long-term preclinical studies using continuous, low-dose-rate vascular brachytherapy with (32)P beta-emitting stents have yielded largely disappointing results. In contrast, a shorter half-life, higher dose-rate (90)Y beta-emitting stent more closely mimics the delivery dose rate characteristics of clinically effective beta- and gamma-wire and balloon brachytherapy devices. We evaluated the dose response characteristics of a (90)Y beta-emitting stent in the canine coronary injury model and hypothesized that this device would reduce neointimal formation. METHODS: Seventy-seven (90)Y beta-emitting coronary stents (15 mm BXTM, 3.0- and 3.5-mm diameter) were implanted in 26 normal dogs (20-25 kg) using a randomized, blinded study design. Stent activity included nonradioactive controls (n = 24), 4.5 microCi (n = 15), 8 microCi (n = 12), 16 microCi (n = 18), and 32 microCi (n = 8). Histologic endpoints were assessed at 3 months. RESULTS: Luminal stenosis and neointimal area were similar in control stents and low-activity (4.5 and 8 microCi) (90)Y stents. Higher activity stents (16 and 32 microCi) were associated with significant adverse effects. Frequent total occlusions (5 of 18 stents, 28%; p = 0.008) and a 40% increase in neointimal area (p = 0.024 vs. control) occurred in the 16 microCi group. Incomplete neointimal healing and a trend for reduced neointimal cell density were evident only in the 16- and 32-microCi group. CONCLUSION: Despite unique characteristics (2.7 day half-life and a higher dose rate) of (90)Y beta-emitting coronary stents, they have an adverse effect on neointimal formation, including frequent total occlusions at high activity levels. Incomplete healing, present 90 days (33 half-lives) after stent placement, indicates prolonged recovery from radiation injury.

Summative evaluation of a baccalaureate nursing informatics curriculum.

This paper describes the fifth stage in the process of designing, implementing and evaluating the nursing informatics courses incorporated into a baccalaureate nursing program. The challenge is to construct an evolving nursing informatics curriculum so as to provide nursing professionals with the foundations for affecting health care delivery. The basic components of the curriculum framework are information, technology, and clinical care process. Information on the two groups of graduates who have completed the four course sequence and the one group of graduates who have been in practice will be discussed.

Fluorescein-labeled beta-glucosidase as a bacterial stain.

Fluorescein isothiocyanate-labeled beta-glucosidase was used as a simple staining reagent with selected gram-positive and gram-negative organisms. Staining in situ appeared to be dependent on the presence of accessible glycosidic-type linkages in the bacterial cell wall. Extensive wall damage or lysis did not occur when stained cells were suspended in washing and mounting solutions. The apparent specificity of labeled enzyme for wall substance was tested by blocking reactions, staining of isolated cell walls, and failure to stain substances lacking appropriate glycosidic linkages. Severe cell wall lesions were produced after prolonged contact with labeled enzyme, and this phenomenon may also be related to staining specificity. Gram-negative organisms and spores were poorly stained unless protected glycopeptide substrate was previously exposed by treatment of cells with thioglycolic acid or dilute alkaline sodium hypochlorite solution. A potential for staining tissues and cell lines may also exist. Some possible applications of labeled enzymes are briefly discussed.

Direct fluorescent labeling of microorganisms as a possible life-detection technique.

Microorganisms and selected proteinaceous substances were directly tagged with fluorescein isothiocyanate. This approach suggested a possible application for detection of extraterrestrial life. A stable and apparently specific linkage was formed with protein, and nonprotein substances were readily destained. Soil and atmospheric debris did not exhibit any significant affinity for the dye.