Factor XI antigen and activity in human platelets

Washed platelets, contaminated with less than 0.20% plasma factor XI, were examined for the presence of factor XI antigen and activity. These platelets contained a factor-XI-like coagulant activity (0.67 +/- 0.11 U/10(11) platelets) that remained constant after successive washes. By means of indirect immunofluorescence, a monospecific antibody to factor XI showed specific staining of both normal platelets and platelets from patients deficient in plasma factor XI. Radiolabeled Triton extracts of washed platelets and labeled purified factor XI solutions were analyzed for factor XI antigen by Staph A immunoprecipitation analysis using antibody to purified plasma factor XI followed by SDS gel electrophoresis. On unreduced gels, the platelet material ran as a single band having an apparent molecular weight of 220,000 daltons, whereas purified plasma factor XI gave a single band at 160,000 daltons. On reduced gels, the platelet material analyzed as a single band at 52,000 daltons, whereas purified factor XI gave a single band of 80,000 daltons. Analysis of a partially purified factor XI preparation from platelets by immunoelectrophoresis revealed that the platelet preparation displayed a slightly lower cathodal electrophoretic mobility at pH 8.6 than did plasma factor XI and yet appeared to possess complete antigenic identity with plasma factor XI. These results indicate that platelets possess a form of factor XI that exists as a disulfide-linked 52,000-dalton tetramer in contrast to the plasma form that circulates as a 80,000-dalton disulfide-linked dimer.     

递增负荷有氧运动14周影响不同衰老程度老年男性的生物学年龄

目的:观察有氧运动对不同衰老程度老年男性生物学年龄的影响。方法:于2002-09/12选择上海市杨浦区退休老年男性13名,年龄59～76岁,平均(64±5)岁,近期无系统健身运动经历。13名老年男性采用功率自行车进行14周递增负荷有氧运动。以最大心率的75%所对应的运动负荷为训练强度;在第4,8周末重新确定运动强度,第5～8周、9～14周以新负荷作为健身运动负荷。每周3次,起始2周每次持续20min,以后每隔2周每次增加5min。采用刘继武等推荐的生物学年龄成套测试方法测定生物学年龄。运动前和运动后测定生物学年龄以及身体形态、心血管、肺功能等生理指标。并根据生物学年龄与实际年龄的差距,分成提前衰老组(生物学年龄大于实际年龄)和延缓衰老组(生物学年龄小于实际年龄)进行对照分析。结果:①老年男性运动前生物学年龄大于实际年龄,差异无显著性意义(P=0.56),有氧运动后生物学年龄小于实际年龄,差异无显著性意义(P=0.066),有氧运动后生物学年龄小于运动前,差异有非常显著性意义[分别为(65.13±6.33),(67.15±7.13)岁,P<0.01]。②根据生物学年龄与实际年龄的差距,将老年男性分成提前衰老组7名和延缓衰老组6名。提前衰老组老年男性有氧运动前生物学年龄大于实际年龄,递增负荷有氧运动后生物学年龄接近实际年龄,低于运动前,差异有非常显著性意义[分别为(69.00±6.73),(71.90±7.55)岁,P<0.01]。延缓衰老组有氧运动前生物学年龄小于实际年龄,有氧运动后生物学年龄进一步减少,低于运动前,差异无显著性意义(P>0.05)。③提前衰老组老年男性有氧运动后腰围低于运动前,腰臀比高于运动前,差异有显著性意义[分别为(94.20±5.14),(99.58±6.48)cm;(0.95±0.03),(0.92±0.04)cm,P<0.05]。延缓衰老组老年男性上臂皮褶厚度低于运动前,差异有显著性意义[分别为(11.00±2.17),(14.42±2.33)mm,P<0.05]。其他身体形态指标变化差异无显著性意义。生理功能指标变化较明显,最大摄氧量、闭眼单脚站立时间均高于运动前,差异有显著性意义[分别为(36.08±5.40),(30.08±2.21)mL/(kg·min);(28.17±20.51),(12.4±14.78)s,P<0.05]。④两组老年男性有氧运动后心血管和肺功能指标中收缩压、舒张压均有下降,肺活量增加。其中延缓衰老组老年男性肺活量高于运动前,差异有显著性意义[分别为(3.98±0.69),(3.61±0.71)L,P<0.05]。结论:有氧运动对不同衰老程度老年男性生物学年龄、身体形态和生理功能均可产生良性影响,达到延缓衰老目的。     

A cost analysis comparing erythropoietin and red cell transfusions in the treatment of anemia of prematurity

BACKGROUND: Anemia of prematurity is invariably observed in very low birth weight infants and may become symptomatic enough to be treated with packed red cell transfusions. Recently, treatment of this condition with recombinant human erythropoietin has been advocated. STUDY DESIGN AND METHODS: To compare the costs of training symptomatic anemia in hospitalized premature infants with transfusions alone or with erythropoietin plus red cell transfusions as needed, cost estimates were derived from local hospital and published cost data. Decision analysis and sensitivity analysis were applied to a "base case." The base case was derived from results of a multicenter erythropoietin trial in the United States in which premature infants received 500 U of erythropoietin per kg of body weight each week. Because erythropoietin treatment began on average at 3 weeks of life, when infants were clinically stable, they had already received 3.5 red cell transfusions. During the 6-week treatment period, erythropoietin- treated infants received significantly fewer additional transfusions: a mean of 1.6 versus 1.1. RESULTS: The base-case cost in 1993 dollars for treating anemia in hospitalized premature infants with erythropoietin and transfusions was $1,326. This was nearly twice the cost of conventional treatment with transfusions alone ($721). If the 6-week treatment period alone is considered, erythropoietin is 3.6 times more costly: $840 versus $235. CONCLUSION: The largest available US study using erythropoietin to treat anemia in premature infants has demonstrated a small, but significant, reduction in transfusion needs. However, this study's cost data alone do not justify the widespread use of erythropoietin in premature infants. When this issue is probed in great depth, sensitivity analyses demonstrate that major reductions in erythropoietin's cost and/or improvements in its effectiveness quite possibly will make its use economically more attractive.     

Über das Vorkommen von dickwandigen Arterien in der Lunge bei gleichzeitiger Hypertrophie der Lungenmuskulatur

Virchows Archiv - Bei zwei, im Rahmen einer Untersuchungsreihe genau untersuchten Lungen fanden sich vorwiegend peripher gelegene, auffallend dickwandige, kleine Arterienäste mit einer...     

Contribution of hospital characteristics to the volume–outcome relationship: Dislocation and infection following total hip replacement surgery

Objective

Mortality and complication rates after total hip replacement (THR) are inversely associated with the volume of THRs performed at hospitals and by individual surgeons. It is not clear, however, why a higher volume of such procedures is associated with better outcomes. We evaluated the contribution of hospital structural characteristics to the volume–outcome relationship in THR by examining the rates and predictors of postoperative complications.

Methods

We analyzed data pertaining to 5,211 Medicare patients who underwent primary THR in 1995 or 1996 at 167 hospitals in Colorado, Pennsylvania, and Ohio. Data were derived from several sources, including Medicare Part A and Part B claims, the American Board of Medical Specialties, a hospital survey regarding institution‐specific characteristics and structural aspects of the care setting, and the American Hospital Association 1995 Annual Survey. Multivariate models were constructed to determine whether hospital structure or surgeon‐associated factors may underlie the relationship between volume of THRs and the occurrence of perioperative orthopedic adverse events, defined as deep wound infection or hip dislocation within 90 days of surgery.

Results

Of the patients studied, 2.6% experienced an orthopedic adverse event after THR. Sixty‐nine percent fewer events occurred in hospitals where >100 THRs in Medicare patients were performed annually, compared with hospitals where ≤25 THRs were performed. In univariate analyses, several hospital‐level factors were associated with a reduced (∼50%) risk of adverse events, including private (versus public) ownership, membership in the Council of Teaching Hospitals, presence of any residency training program, availability of a dedicated orthopedic nursing unit, and existence of operating rooms with laminar flow exhaust systems. However, the only hospital‐level factor associated with adverse events in multivariate models was the use of laminar flow exhaust systems. When surgeon volume was added to the models, it was the strongest predictor of adverse events, with hospital volume and hospital‐level factors having no appreciable association with adverse events.

Conclusion

Hospital‐level factors were not independent predictors of the association between hospital volume and orthopedic adverse events. The volume of THRs performed by individual surgeons is the most important determinant of orthopedic complications and should be considered in efforts to improve THR outcomes.