Localization of thrombospondin in clots formed in situ

Thrombospondin is a principal glycoprotein secreted by thrombin- stimulated platelets and has known affinities for fibrinogen and fibrin. We studied the distribution of thrombospondin in clots formed in situ on Formvar-coated coverslips at 37 degrees C for intervals up to 17 hours. The distributions of three other major platelet granular proteins--fibrinogen, fibronectin, and von Willebrand factor (vWF)-- were also determined. The portions of the clots adhering to the coverslips after stripping, washing, and fixation with formaldehyde were stained for the four proteins by the peroxidase-antiperoxidase technique. Monoclonal antibodies were used to localize thrombospondin, fibronectin, and vWF; affinity-purified polyclonal antibodies were used to localize fibrinogen. Platelets stained positively for all four proteins. Thrombospondin was maximally present in the fibrin meshwork from 1 1/2 to 2 hours, after which the intensity of staining decreased until only trace amounts of thrombospondin were detectable between four and 17 hours. Antifibrinogen and, to a lesser extent, antifibronectin stained the fibrin meshwork at all time points. The vWF was not detectable in the fibrin meshwork at any time point. Staining of polymorphonuclear leukocytes (PMNLs) in a fine granular pattern was found with antithrombospondin. The fraction of PMNLs staining positively was 6% to 14% at 1/2 to 4 hours and increased at eight hours to 27%. At 17 hours, 52% of the PMNLs stained for thrombospondin. More than 48% of the PMNLs stained with antifibrinogen at all time points. PMNLs did not stain for either fibronectin or vWF. These studies indicate that thrombospondin is a transient component of the temporary fibrin meshwork and has a unique spatial and temporal distribution in the hemostatic plug.     

Detection of submaximal effort by use of the rapid exchange grip

To assist in distinguishing patients with truly decreased hand grip strength from those deliberately not gripping the dynamometer at maximal capacity, a rapid exchange grip strength test was devised and tested under four conditions. Part I, 100 normal subjects undergoing static grip testing and the rapid exchange grip test. Part II, 45 patients chosen at random from physical therapy with various hand injuries tested using only the static grip test. Part III, a blind control study on 15 normal subjects instructed to fake an injury to either the right or left hand. This group was given both the static and rapid exchange grip test. Part IV, a retrospective evaluation of 45 patients seen in a private hand practice who had both the static and rapid exchange grip test. After the dynamometer had been set to the position at which the patient had previously achieved maximal grip strength, the patient was instructed to rapidly alternate hands while gripping the dynamometer. Uninjured subjects had consistently lower rapid exchange grip test scores than previous scores at the same setting (negative rapid exchange grip). Average rapid exchange grip test scores were higher than previous scores (positive rapid exchange grip) when subjects were instructed to fake an injury with one hand. We conclude that if maximal performance has not been achieved on the static test, the rapid exchange grip shows a significant increase in grip strength on the affected side. More patients claiming worker's compensation had positive rapid exchange grips and the average score was higher than that of patients not claiming worker's compensation.(ABSTRACT TRUNCATED AT 250 WORDS)     

Recovering heading for visually-guided navigation.

We present a model for recovering the direction of heading of an observer who is moving relative to a scene that may contain self-moving objects. The model builds upon an algorithm proposed by Rieger and Lawton, based on earlier work by Longuet-Higgins and Prazdny. The algorithm uses velocity differences computed in regions of high depth variation to locate the focus of expansion, which indicates the observer's heading direction. We relate the behavior of the model to psychophysical observations regarding the ability of human observers to judge heading direction, and show how the model copes with self-moving objects in the environment.     

Expression of the multidrug resistance-associated P-glycoprotein (P- 170) in 59 cases of de novo acute lymphoblastic leukemia: prognostic implications [see comments]

Immunocytochemical detection of the multidrug resistance (MDR)- associated membrane protein (P-170) was performed at time of diagnosis in a series of 36 children and 23 adults with acute lymphoblastic leukemia (ALL) using two monoclonal antibodies JSB1 and C219. Immunophenotypes were obtained in all cases and karyotypes were analyzed in 37 cases. Detection with JSB1 or with C219 led to similar results in terms of positive cells and cases, but the intensity of staining was higher with JSB1. In the populations studied, the rate of first complete remission differed between MDR-positive and MDR-negative in adult patients only (56% v 93%, respectively, P = .05). Of the 16 MDR-positive patients who had presented a first complete remission, 13 (81%) relapsed, compared with 13 of 35 (37%) MDR-negative (P = .008) patients. A higher rate of relapse among MDR-positive compared with MDR- negative patients was observed in adults and in children taken separately (adults 100% v 46%; children 73% v 32%, respectively). The survival rates (Kaplan-Meier method) were significantly higher in MDR- negative compared with MDR-positive populations as a whole (P = .002) and among children (P = .05) and adults (P = .03) taken separately. Event-free survival curves followed this trend. The percentage of second complete remission was very low in the MDR-positive group (15%) compared with 38% for the MDR-negative group. These results were shown by multivariate analysis to be independent of age, immunophenotypes, and karyotypes and clearly show the importance of MDR phenotype detection in ALL.     

吸收度线性组合法进一步探索

本文比较了线性组合法和正交函数法两种计算分光光度法对乳糖干扰下盐酸麻黄素的测定。实验结果表明,同样的数据,线性组合法的精度比正交函数法提高约十倍,从而在理论和实践上都证实了线性组合法在改善精度方面的优越性。同时也讨论了测试点数,以及个别测试点测定精度对组合法总体测定精度的影响,给出了最佳组合方式,反映了组合法简易的特点。     

Renal allograft accumulation of Tc-99m sulfur colloid: temporal quantitation and scintigraphic assessment

Renal allograft accumulation of Tc-99m sulfur colloid (TSC) was studied using visual assessment of scintigraphic displays and a quantitative temporal model in 210 examinations of 56 transplant recipients. The quantitative temporal model related the immediate pool of the radioagent in the transplant to the fixed allograft accumulation of TSC at 20 minutes after administration. Examinations performed less than 3 days after grafting or steroid pulse therapy were excluded. Rejection was established by clinical and biochemical evaluation in all 84 examinations that showed acute or chronic allograft rejection. Rejection was accurately diagnosed by visual scintigraphic assessment in 82% of the established cases; this improved to 99% with relative temporal quantitation analysis. Sensitivity improved from 78% by visual examination to 95% with temporal quantitation and specificity improved from 83% to 100%.     

Comparison of knee joint functional laxity after total knee replacement with posterior cruciate-retaining and cruciate-substituting prostheses

The objective of this study was to measure three-dimensional knee motion or functional laxity with implants which either retained the posterior cruciate ligament (PCL+) in ten patients, or substituted for excised PCL with a posterior stabilized articulating surface (PCL-S) in ten patients. The intent was to identify the specific influence and significance of the presence of the PCL under active flexion and extension. Internal-external rotation (screw home movement) and anterior-posterior translation (femoral rollback phenomena) with active extension and flexion were chosen to characterize knee joint functional laxity, and were measured using an instrumented spatial linkage. Knees with a PCL+ implant exhibited both screw home movement and femoral rollback, while knees with a PCL-S design exhibited only femoral rollback. A knee with a PCL+ implant was more able to reproduce the normal kinematics of the screw home movement and femoral rollback, compared to a PCL-S design.