Platelet aggregation studies in acute experimental canine ehrlichiosis

BACKGROUND: Thrombocytopenia is the most common and consistent hematologic finding in patients with canine monocytic ehrlichiosis. Dogs that recover from the severe thrombocytopenia still show bleeding tendencies, which suggest that platelet dysfunction is present. OBJECTIVES: The purpose of this study was to determine the occurrence and duration of platelet dysfunction in dogs with ehrlichiosis and to assess whether dysfunction is related to thrombocytopenia. METHODS: Ten adult male and female mongrel dogs were used in the study; 7 were inoculated intravenously with whole blood containing Ehrlichia canis, and 3 were used as controls. Platelet aggregation (with collagen/epinephrine and adenosine diphosphate (ADP)/epinephrine) and platelet counts were evaluated weekly for 112 days. RESULTS: The infected group showed a decrease in platelet aggregation response to collagen/epinephrine and ADP/epinephrine on days 7, 14, 21, 28, and 35 (P <.05). Thrombocytopenia was observed in all infected animals from day 7 to 35 postinfection (P <.05). CONCLUSIONS: The tendency of dogs infected with E canis to bleed may be related not only to thrombocytopenia but also to platelet dysfunction associated with the disease.     

The Effect of Intravenous Administration of Web 2086 on PAF-Induced Platelet Aggregation in Healthy Friesian Calves

The in vivo ability of the specific PAF-antagonist WEB 2086, a thienotriazolodiazepine, to inhibit platelet-activating factor (PAF) in cattle was investigated by in vitro determination of platelet aggregation curves. WEB 2086 was infused intravenously into a group of 5 healthy male Friesian calves in a dose of 3 mg/kg over 1 min. The resultant inhibition peaked between 30 min and 1 h after administration of WEB 2086. The inhibition was significantly reduced after 3 h and became non-significant after 6 h, but maximal pre-treatment aggregation had not been restored by 24 h after the injection of WEB 2086. These results confirm previous results obtained in vitro and suggest that WEB 2086 is a potent antagonist of PAF activity in calves. They also suggest that further clinical studies with WEB 2086 in cattle are desirable.     

高效液相色谱法测定猪血浆、全血和血小板中五羟色胺水平及其相关性分析

本试验采集43头苏淮猪的血液样本,探究利用高效液相色谱法(HPLC)测定血浆和全血五羟色胺(5-HT)的色谱条件,测定了血浆、全血和血小板中5-HT的水平,并对它们进行了相关性分析。结果:猪血浆中5-HT浓度为(45.35±2.23)μg/mL,血小板中5-HT含量为(131.31±7.86)pg/10^9,全血中5-HT浓度为(296.87±12.81)μg/mL;相关性分析显示,血小板5-HT浓度与全血5-HT浓度存在极显著正相关性(r=0.849,P<0.01),血小板5-HT浓度与血小板数量存在极显著负相关性(r=-0.549,P<0.01),但血浆5-HT浓度与全血5-HT浓度、血小板5-HT浓度无显著相关性(P>0.05)。综上,高效液相色谱法可用于测定猪血浆、全血、血小板中5-HT的水平,血小板5-HT含量与全血5-HT浓度和血小板数量之间均存在极显著相关性。     

兔胚胎释放物对去脾小鼠血小板数量的影响

兔2细胞期或8～16细胞期胚胎培养液立即或经冷冻、鲜冻后注入去脾小鼠体内,能异源性引起去脾小鼠血小板数量显著减少(P<0.050)。血小板激活因子受体竞争性拮抗剂海风藤酮能抑制这种作用。试验说明兔胚胎释放血小板激活因子,并引起去脾小鼠血小板的聚集。     

小剂量肝素对危重新生儿伴全身炎症反应综合征的早期干预作用

目的观察小剂量肝素对危重新生儿全身炎症反应综合征(SIRS)的治疗效果及预后的影响。方法对我科2005年6月至2007年6月间符合诊断标准的94例新生儿SIRS患儿随机分组进行前瞻性对照研究,对照组46例采用常规治疗,治疗组48例在常规治疗基础上每次加用小剂量肝素(5u/kg)皮下注射,每6h 1次,连用3d,观察两组C-反应蛋白(CRP)、血小板计数(PLT)、D-二聚体(D-D)治疗前后的变化。结果治疗组SIRS持续时间>3d者16例(33.3%),明显少于对照组的28例(60.9%),MODS发生率和病死率也明显低于对照组(10.4%、4.2%vs34.8%、17.4%)(P<0.01或0.05);两组治疗后的PLT、CRP及D-D水平均明显改善,且以治疗组更为明显(P<0.01)。治疗组使用肝素后凝血指标均恢复正常或趋于正常。结论早期应用小剂量肝素可有效缩短SIRS持续时间,MODS的发生率及病死率明显降低。     

Hen egg yolk lipid fractions with antiatherogenic properties

Three different types of hen egg yolk, cage‐free, organic and daily fresh, were tested for their antiatherogenic properties. Total lipids (TL) of all hen egg yolk samples were extracted by the method of Bligh and Dyer and further separated into total polar lipids (TPL) and total neutral lipids (TNL) by counter current distribution chromatography. TPL and TNL were further separated by preparative thin‐layer chromatography (TLC). TL, TPL, TNL and the obtained polar and neutral lipid fractions after TLC separation were tested to determine whether they induce platelet activation or inhibit platelet activating factor (PAF)‐induced platelet activation. All three hen egg yolk TL samples possessed strong inhibitory activity against PAF‐induced platelet activation that was mainly attributed to TPL, especially to PL fraction 4. Cage‐free hen egg yolk exhibited the most potent anti‐PAF activity in all lipid classes (TL, TPL and TNL). Thus hen egg yolk contains PAF inhibitors that reinforce their nutritional value in terms of protection against cardiovascular diseases, since PAF is a crucial inflammatory phospholipid mediator that is implicated in the mechanism of atherogenesis.     

Unique structure of the M loop region of β1-tubulin may contribute to size variability of platelets in the family Felidae

Background: Platelet size is relatively uniform in mammals except for domestic cats. Uniform platelet production by megakaryocytes can be disrupted if microtubule assembly or dynamics is impaired. Mutations in the gene encoding β1‐tubulin have been documented in dogs and people, and the resulting microtubule effects have been associated with production of large platelets. Objectives: The objectives of this study were to evaluate morphology of platelets on feline blood smears, determine the gene sequences encoding β1‐tubulin in members of the family Felidae, and compare the findings with those in other mammalian species to determine whether predicted structural differences in β1‐tubulin that might affect microtubule stability or assembly were present. Methods: At least 100 platelets/smear on blood smears from 15 domestic cats and 88 big cats were evaluated to assess platelet size variability. Platelet‐derived cDNA obtained from a domestic cat and genomic DNA isolated from blood samples of domestic cats and other members of the family Felidae were analyzed by PCR using primers specific for β1‐tubulin. Gene sequences obtained were compared with those of other common mammals. Results: Two differences in gene sequence were found in a highly conserved region encoding the M loop of β1‐tubulin in members of the family Felidae compared with sequences from other species. Platelet size variation was present in big cats and domestic cats. In addition, a rare amino acid change was documented in the C‐terminal region encoding the H11 helix in domestic cats. Conclusion: Members of the family Felidae have an altered M loop region in β1‐tubulin compared with other mammals. This variation may contribute to the observed platelet size variability.     

动态监测感染性休克患儿血小板计数及平均体积的临床意义

目的探讨动态监测感染性休克患儿血小板（PLT）计数及平均血小板体积（MPV）的临床意义。方法检测53例感染性休克患儿（代偿期38例,失代偿期15例）入院后1、24、72、120h的PLT计数、MPV,并与同期50例健康儿作对照。结果感染性休克患儿入院时PLT计数低于对照组,而MPV高于对照组（P〈0.01）,其中失代偿期组更明显。死亡组PLT计数在各时点均低于存活组,但MPV均高于存活组（P〈0.01）。结论感染性休克患儿PLT计数、MPV的动态变化有助于判断病情严重程度及预后。