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151.
The relation of platelet density to platelet age: survival of low- and high-density 111indium-labeled platelets in baboons 总被引:5,自引:0,他引:5
The relationship between platelet density and platelet age has been studied using continuous linear Percoll density gradients and 111In- labeling of autologous platelets in baboons. To investigate changes in platelet density during senescence in the circulation, baboons were infused with 111In-labeled autologous platelets, and blood was collected at one hour postinfusion and twice daily thereafter for six days. Platelets were isolated from these samples in high yield (greater than 95%) and separated in continuous linear Percoll density gradients following density equilibrium centrifugation. Although at one hour postinfusion the density distribution of radiolabeled platelets coincided closely with the distribution of the total platelet population, a detectable symmetrical shift toward higher densities was observed after five days. The relative specific radioactivity (RSR) of high-density platelets (1.064 to 1.067 g/mL) decreased at a slower rate than that of the total platelet population (platelets of all densities), whereas the RSR of low-density platelets (1.053 to 1.056 g/mL) showed a more immediate and rapid decrease. These results give rise to one of two interpretations: (1) low-density platelets have a shorter survival time than more dense platelets and are therefore cleared from the circulation at a faster rate, or (2) platelets of all densities increase in density upon aging in the circulation. To determine the explanation for changing RSR of different density fractions we studied the in vivo disappearance characteristics of low- and high-density 111In-labeled platelets. There were no significant differences between the mean survival times of low-density platelets (5.0 +/- 0.49 days, +/- 1 SD, n = 6), high-density platelets (4.9 +/- 0.56 days, n = 6), or control platelets representing platelets of all densities (4.9 +/- 0.38 days, n = 6). Although a slight increase in the density of all platelets during platelet senescence is indicated by these studies, we conclude that platelet density heterogeneity is not primarily a consequence of age-related changes in platelet density. 相似文献
152.
Endoscopic management of acute calculous cholangitis 总被引:16,自引:0,他引:16
BC SHARMA DK AGARWAL SS BAIJAL VA SARASWAT G CHOUDHURI SR NAIK 《Journal of gastroenterology and hepatology》1997,12(12):874-876
Acute cholangitis is associated with significant morbidity and mortality. Endoscopic drainage procedures have been shown to be a safe and effective mode of treatment in acute cholangitis. As there is paucity of large series on endoscopic management of acute cholangitis, a study was performed to evaluate safety and efficiency of endoscopic biliary decompression in acute cholangitis. The study included 89 consecutive patients (mean age 55 ± 15 years; range 35–70 years; 50 males) with acute cholangitis requiring biliary drainage. Main presenting features were upper abdominal pain (84%), fever with chills (90%) and jaundice (74%). Altered sensorium, hypotension, features of peritonitis and acute renal failure were present in 15, 11, 18 and 5%, respectively. Endoscopic procedures performed were endoscopic sphincterotomy (ES) with stone extraction (n= 40); ES with endoscopic nasobiliary drainage (ENBD; n= 30); ENBD without ES (n= 8); and ES with stent placement (n= 11). Of the 89 patients, 85 (95%) responded within 48–72 h. Endoscopic common duct clearance could be achieved in 58 of 78 (74%) patients, whereas in 11 patients undergoing stent placement, stone extraction was not attempted. Complications included post-sphincterotomy bleed (n= 2), retroduodenal perforation (n= 1) and acute pancreatitis (n= 1) with an overall complication rate of 4.4%. All the complications were seen in patients undergoing ES with stone extraction. Mortality was 3.3%. In conclusion, endoscopic biliary drainage is a safe and effective mode of treatment for acute cholangitis. Endoscopic nasobiliary drainage or stent placement is safer than ES in acute cholangitis as an initial step. 相似文献
153.
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155.
Platelets are heterogeneous in the content of membrane glycoprotein (GP)IIb/IIIa complex. To determine whether this heterogeneity is related to changes associated with platelet aging in the circulation, newly released platelets, obtained during recovery from nonimmune- mediated acute experimental thrombocytopenia in baboons, were studied. Monoclonal antibody (MoAb) binding to epitopes expressed on GPIIb/IIIa complex (LJ-CP8), GMP-140 (S12), and GPIa/IIa (12F1) was measured on control platelets (comprising platelets with a normal age distribution; mean age 60 to 72 hours) and newly formed platelets (mean age 12 hours), both in the resting state and after thrombin stimulation. Whereas LJ-CP8 binding to resting control platelets increased by 34% upon stimulation by gamma-thrombin from 30,885 +/- 1,171 to 41,458 +/- 1,311 molecules/platelet at saturating concentrations of antibody, LJ- CP8 binding to resting young platelets did not increase significantly upon thrombin stimulation (31,878 +/- 3,330 and 33,791 +/- 3,486 molecules/platelet, respectively). Similarly, binding of antibody S12 in response to maximal thrombin stimulation was reduced by 42% from 10,246 +/- 834 molecules/platelet at saturating concentrations of S12 for control platelets to 5,971 +/- 665 molecules/platelet for young platelets (P = .001). S12 binding to unstimulated platelets was less than 10% of the binding observed after thrombin stimulation at all concentrations of S12 for both control and young platelets. However, maximal binding of antibody 12F1 to resting control platelets did not differ significantly from that observed with resting young platelets (2,926 +/- 167 and 2,857 +/- 208 molecules/platelet, respectively), and 12F1 binding was unchanged after thrombin stimulation for both control and young platelets. We conclude that the thrombin-induced increase in the expression of epitopes on platelet membrane GPIIb/IIIa complex and GMP-140 is a function of platelet age. 相似文献
156.
157.
Inhibition of platelet-dependent thrombus formation by human activated protein C in a primate model 总被引:9,自引:1,他引:9
The in vivo antithrombotic properties of human plasma activated protein C (APC), a natural anticoagulant enzyme, were investigated in a baboon model of thrombus formation on prosthetic vascular grafts. Infusion of 0.25 to 1.1 mg/kg/h purified, human, APC inhibited blood clotting, as measured by the activated partial thromboplastin time (APTT), and reduced vascular graft platelet deposition by 40% to 70%, as determined by the real-time scintillation camera imaging of 111In-labeled platelet deposition. APC infusion also preserved graft patency. Hemostatic plug formation remained normal, as measured by the template bleeding times. These results suggest that APC administration may produce immediate antithrombotic effects under arterial flow conditions. 相似文献
158.
Robert A Stone Brian DW Harrison Derek Lowe Rhona J Buckingham Nancy A Pursey Harold SR Hosker Jonathan M Potter C Michael Roberts 《BMC health services research》2009,9(1):173-7
Background
We report baseline data on the organisation of COPD care in UK NHS hospitals participating in the National COPD Resources and Outcomes Project (NCROP). 相似文献159.
MH Prins I Guillemin H Gilet S Gabriel B Essers G Raskob SR Kahn 《Health and quality of life outcomes》2009,7(1):30
Background
The 'Perception of Anti-Coagulant Treatment Questionnaire' (PACT-Q) was developed to assess patients' expectations of, and satisfaction with their anticoagulant treatment. This questionnaire needs to be finalised and psychometrically validated. 相似文献160.
J Audsley N Arrifin LKW Yuen A Ayres SM Crowe A Bartholomeusz SA Locarnini A Mijch SR Lewin J Sasadeusz 《HIV medicine》2009,10(4):229-235