Structural variation of the mouse natural killer gene complex.

The natural killer gene complex (NKC) on chromosome 6 contains clusters of genes that encode both activation and inhibitory receptors expressed on mouse natural killer (NK) cells. NKC genes, particularly belonging to the Nkrp1 and Ly49 gene families, display haplotype differences between different mouse strains and allelic polymorphisms of individual genes, as previously revealed by conventional analysis in a small number of inbred mouse strains. Herein we used array-based comparative genomic hybridization (aCGH) to efficiently compare the NKC in 21 mouse strains to the reference C57BL/6 strain. By using unsupervised clustering methods, we could sort these variations into the same groups as determined by previous RFLP analyses of Nkrp1 and Ly49 genes. Prospective analyses of aCGH and RFLP data validated these relationships. Moreover, aCGH data predicted monoclonal antibody reactivity with an allospecific determinant on molecules expressed by NK cells. Taken together, these data demonstrate the structural variation in the NKC between mouse strains as well as the usefulness of aCGH in analysis of complex, polymorphic gene clusters.

Randomized comparison of hemostasis techniques after invasive cardiovascular procedures.

BACKGROUND: The arterial access required during most invasive vascular procedures provides a common source of complications and morbidity. This problem has been made worse by recent trends in earlier ambulation and more aggressive antihemostatic drug regimens. Despite these trends, no randomized trials have been reported comparing the 3 most commonly used techniques in achieving hemostasis at the arterial puncture site. METHODS: A cohort of 400 patients undergoing catheterization laboratory procedures were randomly assigned to 1 of 3 groups of arterial compression: manual compression, mechanical clamp, and pneumatic compression device. Standard requirements of the trial included uniformity in initial compression times, patient instructions, nursing follow-up, and timing of ambulation as well as a structured interview and physical examination at 24 hours. RESULTS: Prolonged compression was required in 13% of the manual group, 20% of the clamp group, and 35% of the pneumatic group (P <.0001). In-lab bleeding was more common in the pneumatic group (3%, 4%, and 16%, respectively, P <.0001), as was the need for an alternate compression technique (1%, 1%, and 27%, P <.0001). The groups also differed in respect to mean hematoma size (3.9 cm(2), 7.8 cm(2), and 19.8 cm(2), P =.036) and level of discomfort during compression (1.9, 2.2, and 3.1 on a 1- to 10-point scale, P <.0001). Comparable findings were observed in the subgroup of patients eligible for outpatient procedures. CONCLUSIONS: Use of the pneumatic compression device leads to longer compression times, greater discomfort, more bleeding, and larger hematomas. Differences between manual compression and the mechanical clamp were more subtle but tend to favor use of the manual technique.

Maintenance of hemostasis after invasive cardiac procedures: implications for outpatient catheterization.

OBJECTIVES: This study investigated the efficacy of four different methods of arterial puncture site management during recovery from invasive cardiac procedures. The primary goals were less patient discomfort and improved clinical outcome. BACKGROUND: The increasing use of outpatient catheterization, large interventional devices and potent periprocedural anticoagulation regimens has made the reduction of groin complications a high priority. Despite these trends, there are no randomized trials comparing commonly used techniques in treating the catheter entry site for the first few hours after the procedure. METHODS: Four-hundred consecutive patients undergoing catheterization laboratory procedures were randomly assigned to one of four dressing techniques applied after achieving hemostasis: a sandbag placed over the site; a pressure dressing constructed from surgical gauze and elastic tape; a commercially available compression device; and no use of compressive dressing. Of these 400 patients, 171 would have been eligible for outpatient procedures in the absence of geographic constraints. The dressings were removed, and ambulation was encouraged 5 h after sheath removal. Uniform initial compression times, patient instructions, nursing follow-up and a structured interview and physical examination at 24 h were used. RESULTS: The level of patient discomfort before and after dressing removal, as well as site tenderness at 24-h follow-up, was statistically similar in all four groups. Hematomas (typically small) and areas of ecchymosis were observed in 58 and 122 patients, respectively, but both their frequency and size were equally represented in each group. Important adverse events were confined to bleeding, rated as mild in 5.8%, moderate in 0.8% and severe in 0.6% of patients. Again, all four groups were statistically similar. Comparable findings were observed in the subgroup of patients eligible for outpatient procedures. CONCLUSIONS: Despite an increase in inconvenience and expense, none of the three compression techniques that were investigated improved patient satisfaction or outcome. Therefore, the routine use of compression dressings after invasive cardiac procedures cannot be recommended.

Long-term reproducibility of respiratory gas exchange measurements during exercise in patients with stable cardiac failure.

Present-day technology has greatly facilitated the monitoring of respiratory gas exchange in the clinical exercise laboratory. Despite the growing use of these techniques to assess the severity and progression of disease or therapeutic response in patients with heart failure, the long-term reproducibility of oxygen uptake (VO2), carbon dioxide production, minute ventilation, heart rate (HR), and blood pressure at rest and during incremental exercise in such patients, to our knowledge, has not been evaluated. Therefore, the purpose of this study was to quantify the reproducibility of these variables along with exercise duration, maximum VO2 (VO2max) and anaerobic threshold in a group of 16 patients (61 +/- 7 years, 14 male) with chronic, stable cardiac failure of varying severity and etiology who had five or more incremental treadmill exercise tests over a period of time that ranged from 3 to 22 months. For each variable, reproducibility was represented by the coefficient of variation (CVAR). Except for exercise duration, CVAR was not a function of the severity of heart failure and, for all variables, patient-to-patient variation in CVAR was approximately 9 percent. The maximum CVAR for HR, systolic blood pressure, VO2, and VO2max was generally below 10.5 percent and for exercise duration and anaerobic threshold it was less than 12.5 percent. Based on this retrospective analysis, it is concluded that reproducible respiratory gas exchange and HR exercise responses are obtainable over extended periods of time in patients with stable, chronic cardiac failure. Exercise duration, however, is less reproducible in patients with moderate to severe failure.