ISSN:0953-7104    

DOI:10.3109/09537109409006053

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

摘要:

Transfusion of platelets concentrated from donated blood is an established therapeutic modality in clinical medicine. Over the past 25 years much effort has gone into optimising the conditions for the collection, preparation and storage of platelets for transfusion. Despite significant advances, platelet production is still a costly process requiring a dedicated environment and the use of specially formulated plastic storage containers. A progressive lesion over storage limits the shelf life and the availability of donated platelets, while the need to store platelets in the donor's autologous plasma also results in a loss of valuable fresh plasma for fractionation. Recent studies have addressed the issues of platelet quality and plasma economy by examining the possibility of storing platelets in a synthetic medium. Platelets stored in a variety of crystalloid solutions have been shown to retain in vitro and in vivo properties equivalent or superior to platelets stored in autologous donor plasma. Some additional insight has been gained on the metabolic patterns of stored platelets. In particular, studies have shown that, under these conditions, platelets are unable to oxidise dextrose to any significant extent, and that dextrose is invariably broken down to lactate, irrespective of the oxygen tensions in the platelet's environment. This in turn leads to the metabolic lesion of platelet storage, whereby low pH results in loss of platelet viability. Platelets stored in synthetic dextrose-free media are capable of maintaining aerobic ATP generation, and acetate—a component of many media studied—has been shown to be metabolised by platelets. Similarly, platelets prepared from blood collected into a dextrose-free anticoagulant have satisfactory properties both when suspended in autologous plasma or in a dextrose-free synthetic medium. The requirements for storage in special, high gas-permeable, containers, and for constant agitation during storage, were both found to be unnecessary when dextrose was excluded from the platelet's environment. These developments suggest that manipulation of the platelet's metabolic pattern during blood bank storage may allow significant benefits in plasma economy as well as in decreasing the cost of platelet delivery to patients.

ISSN:0953-7104    

DOI:10.3109/09537109409006044

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

摘要:

Blood behaviour under shear-stress is assessed by a filter method in the Caerphilly Prospective Heart Study. Associations with haemostatic and lifestyle factors in 941 men aged 55 to 69 years are reported.The importance of platelets in filter blockage is confirmed, and roles for white cells and plasma viscosity in determining flow prior to blockage are identified. The aspect of platelet activity involved in blockage appears to be independent of mechanisms mediated by cyclo-oxygenase and adenosine diphosphate. von Willebrand factor however is associated with filter blockage, probably as an inter-platelet ligand. Fibrinogen is not required for blockage.Men regularly consuming alcohol or garlic supplements show reduced blockage, and biochemical mechanisms are suggested which might explain these associations. No effects of aspirin, smoking or consumption of fish oil supplements were noted.Shear-induced filter blockage is a simple method for measuring complex flow-dependent interactions of haemostatic factors. Its application in a wide range of investigations, including epidemiological studies, would appear to be appropriate.

ISSN:0953-7104    

DOI:10.3109/09537109409006045

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

摘要:

The purpose of this study was to investigate blood platelet function during exposure to the hydrophobic organic solvents toluene,p-xylene andn-hexane. Human blood platelets were exposed for 30 min at 37°C to a saturated atmosphere ofp-xylene, toluene orn-hexane. All three solvents, and the aromatics in particular, induced a decrease in the number of single platelets (61–88%) together with an increase in the extracellular levels of ATP plus ADP (45–65% of total) and serotonin (67–100% of total). Passive leakage of [14C] adenine-labelled nucleotides from the metabolic pool, due to platelet lysis, was minor or delayed. Electron microscopy of platelets exposed top-xylene revealed aggregation. The platelets were spherical without pseudopods. Our results indicate that the hydrophobic solventsn-hexane,p-xylene and toluene induce platelet aggregation and dense granule secretion.

ISSN:0953-7104    

DOI:10.3109/09537109409006046

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

摘要:

The distribution of some proteoglycan anionic sites and carbohydrate moieties on the diabetic platelet surface has been investigated by cytochemical methods. Human blood platelets obtained from either diabetic patients (serum glycaemia 9.6–19.2 mmol/L) or normal donors were labeled with specific stains (Ruthenium Red, Safranin O) or with biotinylated lectins (WGA, RCA120)/Straptavidin-gold. All the probes were processed in a standardised manner for transmission electron microscopy. Results showed a modified pattern of diabetic platelet surface labeling as compared to normals. The anionic sites in the glycocalyx (particularly proteoglycans), evenly distributed all over the normal platelet plasma membrane, suffered a marked redistribution, with cluster formation, on the surface of diabetic platelets. The sugar moieties were also differently exposed: as compared to normal, diabetic platelets expressed a 1.5-fold lower number of WGA-binding sites (sialic acid) and a 2.5-fold higher number of RCA120-binding sites (galactose residues). We conclude that the distribution of some platelet surface components, potentially implicated in the adhesion and aggregation processes, is significantly modified on platelets from diabetic patients.

ISSN:0953-7104    

DOI:10.3109/09537109409006047

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

摘要:

The effect of nitrogen (N2)-microbubbles on human platelets resembles that of common agonists in terms of aggregation, but displays one unusual feature in that cyclooxygenase-inhibitors (e.g. aspirin) poorly inhibit the reaction. In the present study, we have investigated the cyclooxygenase-dependence of microbubble-induced platelet secretion ofβ-thromboglobulin (β-TG) and14C-serotonin. The effect of microbubbles in stirred platelet-rich plasma (PRP) was compared with that of collagen and of polystyrene microspheres. The reduction in the number of single platelets induced by microbubbles was continuous with time and reached 60% after 30 min and was accompanied by secretion of14C-serotonin andβ-TG. While 50% of the secretion ofβ-TG persisted in spite of aspirin treatment, secretion of14C-serotonin was completely abolished. The enhancing effect of epinephrine on microbubble-induced platelet secretion appeared to be prostanoid dependent. Platelet secretion ofβ-TG and14C-serotonin induced by a high dose of collagen was significantly reduced by aspirin, while a low dose of collagen induced a cyclooxygenase-independent secretion ofβ-TG and14C-serotonin. The reduction in single platelets when PRP was stirred with microspheres reached a mean value of 27% after 10 min but did not increase further with time. Microspheres caused a small but significant secretion ofβ-TG but no secretion of14C-serotonin. Aspirin did not reduce the loss in single platelets nor the secretion ofβ-TG. The present study suggests that cyclooxygenase independentα-granule secretion may facilitate and, at least in part, sustain the reaction between microbubbles and platelets. The difference in agonistic effect of polystyrene microspheres on platelets shows that polystyrene spheres are not suitable substitutes for microbubbles in in vitro or in vivo experiments.

ISSN:0953-7104    

DOI:10.3109/09537109409006048

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

摘要:

We have developed a model whereby the femoral artery in an experimental animal can be occluded by a photochemical reaction between rose bengal and green light which causes endothelial injury followed by platelet adhesion, aggregation and formation of a platelet rich thrombus at the site of the reaction. Using this model, we investigated the effect of dietary docosahexaenoic acid (DHA) supplementation on platelet aggregation and on serum cholesterol and lipids. Male Wistar rats (iweeks-old) received dietary DHA supplementation (300 mg/kg/d) for 8 weeks. This regimen produced a significant (p<0.05) decrease in serum free-cholesterol and phospholipids levels, inhibited platelet aggregation ex vivo induced by collagen in whole blood (p<0.05) but not in platelet rich plasma, reduced thromboxane B2formation (p<0.01) induced by collagen in washed platelets and prolonged the time for thrombotic arterial occlusion (p<0.01) as compared with values obtained in animals on standard diet. In conclusion, dietary DHA produces antithrombotic effects such as reduction in platelet aggregability and lowering of plasma cholesterol. Whole blood where red and white blood cells can exert their influences on platelet function is a more sensitive and physiological medium than platelet rich plasma for studying the effects of antithrombotic treatments on platelet aggregability ex vivo.

ISSN:0953-7104    

DOI:10.3109/09537109409006049

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

ISSN:0953-7104    

DOI:10.3109/09537109409006050

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

ISSN:0953-7104    

DOI:10.3109/09537109409006051

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

ISSN:0953-7104    

DOI:10.3109/09537109409006052

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor