Physiology of cold-stored platelets

Platelet transfusions are a life-saving medical intervention used for the treatment of thrombocytopenia or hemorrhage. Extensive research has gone into trying to understand how to store platelets prior to the transfusion event. Much has been learned about storage bag materials, synthetic solutions, and how temperature impacts platelet viability and function. While room temperature storage of platelets preserves 24-hour in vivo platelet recovery and survival there is a greater risk for bacterial growth. Therefore, cold storage of platelets has become attractive due to the reduction in potential bacterial proliferation and the maintenance of platelet function beyond 5 days of storage. Cold stored platelets, however, have their own set of challenges. Cold stored platelets become activated through several mechanisms. The morphological and molecular changes that occur due to cold exposure enhance their ability to participate in the hemostatic process at the cost of rapid clearance from circulation. This review focuses on the underlying mechanisms leading to cold platelet activation and the receptor modifications involved in platelet clearance.     

Protective Effects of Hyperpolarizing Cardioplegia with Pinacidil on Myocardium in Rats

Whether the ATP-sensitive potassium channel opener pinacidil can provide myocardial protective effects in prolonged isolated global ischemic rat heart was investigated. On modified isolated rat working heart model, 40 hearts were divided into four groups randomly: Hyperpolarized arrest H-K solution containing pinacidil (50 tmol/L) (P1 and P2) and depolarized arrest St. Thomas‘ solution (S1 and S2) subjected to 15 C hypothermia, 60 min (P1 and S1) or 120 min (P1 and S2) of ischemia and 30 min reperfusion. The experimental indices included cardioplegic efficiency, cardiac function, coronary blood flow, myocardial enzyme release, myocardial water and ATP content. Hyperpolarized arrest provided significantly better recovery of cardiac function than depolarized arrest.Postischemic coronary flow and myocardial ATP content were higher. The arrest time of electro-mechanical activities were longer than depolarized arrest. There were no differences among the groups in myocardial water contents. The hyperpolarized arrest solution containing pinacidil can provide a marked myocardial protective effect during prolonged hypothermic myocardial ischemia.     

Closed-Chest Cardiopulmonary Bypass and Cardioplegia: Basis for Less Invasive Cardiac Surgery

Background. We developed a method of closed-chest cardiopulmonary bypass to arrest and protect the heart with cardioplegic solution. This method was used in 54 dogs and the results were retrospectively analyzed.

Methods. Bypass cannulas were placed in the right femoral vessels. A balloon occlusion catheter was passed via the left femoral artery and positioned in the ascending aorta. A pulmonary artery vent was placed via the jugular vein. In 17 of the dogs retrograde cardioplegia was provided with a percutaneous coronary sinus catheter.

Results. Cardiopulmonary bypass time was 111 ± 27 minutes (mean ± standard deviation) and cardiac arrest time was 66 ± 21 minutes. Preoperative cardiac outputs were 2.9 ± 0.70 L/min and postoperative outputs were 2.9 ± 0.65 L/min (p = not significant). Twenty-one-French and 23F femoral arterial cannulas that allowed coaxial placement of the ascending aortic balloon catheter were tested in 3 male calves. Line pressures were higher, but not clinically limiting, with the balloon catheter placed coaxially.

Conclusions. Adequate cardiopulmonary bypass and cardioplegia can be achieved in the dog without opening the chest, facilitating less invasive cardiac operations. A human clinical trial is in progress.     

Ten-year stability of cardiovascular responses to laboratory stressors

In this study we examined test-retest stability of cardiovascular stress responses over a decade of the life span. Participants were 55 male college undergraduates. 19 years of age at initial testing, and 29 years of age at follow-up testing Stressors were a foot cold pressor and an aversive reaction time task. Cardiovascular measures included systolic and diastolic blood pressure, heart rate, and preejection period. For cold pressor, the magnitude and pattern of cardiovascular responses remained unchanged at the 10-year follow-up. For the reaction time task, the characteristic cardiovascular response patterns was preserved but with significant attenuation of magnitude. The present findings are consistent with previous observations of temporal stability but over a substantially longer test-retest interval. The long-term stability of stress responses is discussed in the context of stress test methodology, behavioral response demands, and maturation of the physiological systems involved in cardiovascular response expression.     

冷哮丸对动物祛痰作用的影响

目的：探讨冷哮丸对动物的祛痰作用及其作用机制。方法：采用酚红法和毛细玻管法测定排痰量，用家鸽活体气管法及兔离体气管法测其纤毛运动。结果：冷哮丸能显增加小鼠气管酚红排泌量，增加大鼠排痰作用，增强在体鸽及离体兔气管纤毛运动。结论：冷哮丸有显的祛痰作用，其机理可能是增加气管内浆液成分，痰液变稀，同时加快气管纤毛运动而达到祛痰目的。     

冷保存对大鼠部分移植肝再生的影响

目的探讨冷保存对大鼠部分肝移植术后肝再生的影响。方法健康SD大鼠分为Ⅰ组（肝切除组）、Ⅱ组（冷保存1h部分肝移植组）和Ⅲ组（冷保存8h部分肝移植组）。观察各实验组生存率，比较各组术后1、6、12、24、48、72、168h肝质量／体质量比率、肝再生率、有丝分裂指数及增殖细胞核抗原表达。结果Ⅰ、Ⅱ、Ⅲ组7d存活率分别为100％、90％、40％；Ⅲ组术后2～3d大鼠肝质量／体质量比率、肝再生率、有丝分裂指数较Ⅰ、Ⅱ组明显偏低（P〈0．05）；Ⅲ组术后12h内增殖细胞核抗原表达较其余两组明显偏低（P〈0．05），48h才达高峰，至第7天阳性表达仍处高水平。结论长时间冷保存降低了部分肝移植术后的肝再生能力和大鼠术后生存率。     

Prevalence of vibration-induced white finger and assessment of vibration exposure among travertine workers in Italy

Summary Among 76 stonedrillers and stonecutters/chippers working in the Rapolano travertine quarries (Tuscany, Italy), 27 subjects (35.5%) were affected with vibration-induced white finger (VWF). The median latent period for VWF was ten years (range 0.1–26 years). A VWF prevalence of 8% was found among 60 comparable controls (P < 0.0001). Vibration measurements showed that the frequency-weighted accelerations for two rock-drills and two small chipping hammers ranged from 19.7 to 36.4 m/s². Weighted accelerations between 2.4 and 4.1 m/s². were measured on the handles of a vertical grinder and a hand cutter. Vibration data, daily exposure time and total duration of exposure period were used to calculate two indicators of vibration dose such as the four-hour, energy-equivalent, frequency-weighted acceleration (m/s²) and the vibration exposure level (dB). A significant association between the vibration exposure level and the severity of VWF stages was observed among the travertine operators. The dose-effect relationship proposed by ISO 5349 was not suitable for the data of the present study because it overestimates the risk due to hand-transmitted vibration in the travertine workers. Finally, the results of a cold test indicated that the rewarming time of fingertips to room temperature was more prolonged in the operators with VAT than in those without VWF and in the controls.     

山西省计划免疫冷链设备现状调查

为了解山西省计划免疫冷链设备现状,于2001年5月对全省各级卫生防疫站进行了调查.结果显示截止调查时全省装备的6种主要冷链设备共4419台(件,下同),其中前10年(1986～1995年)装备2489台,占56.3%;后6年(1996～2001年)装备1930台,占43.7%.在4419台中,当前正常运转的1930台(43.7%),尚可使用的1057台(23.9%),损坏报废的1432台(32.4%).为满足当前需要,全省尚需增补1888台,其中县、乡两级需增补普通冰箱1011台,低温冰箱805台,疫苗运输车35辆;省、市两级需增补普通冷库4台,低温冷库10台,冷藏车9辆,疫苗运输车14辆.说明需增补的重点在基层.     

地塞米松对冷藏离体肺表面活性物质和顺应性的影响

目的:观察地塞米松对冷藏离体肺表面活性物质和顺应性的影响.方法:32只家兔肺随机均分为对照组、地塞米松冷藏(4℃)保存24h、72h、120h3个组.对照组:测定室温条件下的肺表面活性物质及顺应性.冷藏组:肺离体后立即置于含有地塞米松台式液中冷藏,在相应时间取出肺,室温条件下复温后,置入生理盐水中,测定肺表面活性物质,并测定注气(生理盐水)和抽气(生理盐水)过程中,肺容积在10ml、20ml、30ml时的肺顺应性.结果:冷藏24h组注水、抽水;72h组肺容积在10ml、20ml抽气、冷藏120h组在肺容积为10ml、20ml抽气的肺顺应性同对照组比较,差异无显著性(P>0.05).其余各组、项与对照组比较差异具有显著性(P<0.05),伴有表面活性物质的减少.结论:地塞米松冷藏离体肺顺应性增大,其影响程度随冷藏时间的延长而增加,同时伴有肺表面活性物质的减少.     

温血诱导及终未再灌注对未成熟心肌保护的实验研究

为研究温血停搏液（谷氨酸加天门冬氨酸强化）诱导停跳和主动脉开放前再灌注的未成熟心肌保护的效果。用12只新西兰幼免（3～4周），体重450～550g，随机分成2组：冷血停搏液（谷氨酸加天门冬氨酸强化）组（Ⅰ组，n＝6）；温血停搏浪诱导及再灌注血组（Ⅱ组，n＝6）。结果：1．心功能；CO±dp0／dt恢复百分率Ⅱ组明显优于Ⅰ组（P＜0．01）；LVSP恢复百分率Ⅱ组优于Ⅰ组（P＜0．05）。2．LDH和CK漏出量（U／l）Ⅱ组明显优于Ⅰ组（P＜0．01）；3。心肌含水量（％）Ⅱ组优于Ⅰ组（P＜0．01）；4．心肌结构保护Ⅱ组明显优于Ⅰ组。本实验提示：温血诱导停跳与主动脉开放前温血再灌注对于未成熟心肌有良好的心肌保护效果。