A retrospective analysis of microbial contaminants in outdated random- donor platelets from multiple sites

BACKGROUND: Platelet components contaminated with bacteria are an important source of transfusion-associated bacterial sepsis. Estimates of contamination rates vary widely (0-10%) and are highly controversial. The present study, designed with stringent testing regimens, retrospectively determined the prevalence of microbial contaminants in platelets from four collection regions. STUDY DESIGN AND METHODS: During a 9-month period, outdated platelet units were assayed by spreading aliquots from the unit, and from thioglycollate broth medium inoculated with part of the unit, onto 5-percent sheep blood agar media. Cultures were examined after 72-hour incubation at 37 degrees C, and, if bacterial growth was present, the assay processes were repeated with fresh inocula. Units were considered contaminated only if repeatedly positive. RESULTS: Four (0.08%) of 4995 units sampled were contaminated, two with Corynebacterium sp. and one each with Propionibacterium acnes and Aspergillus terreus. Contaminants were present at low, subclinical levels and were detected only after amplification in thioglycollate. The contaminated units were cultured 1, 2, 3, and 7 days after expiration. CONCLUSION: Contamination rates were low and did not vary by region. The identification of A. terreus suggests the role that transfusion may play in transmitting fungal infections should be reassessed. The persistent detection of contaminated platelet units supports the need for a test to detect clinically relevant levels of microbial contaminants in blood components.     

煅烧与冻干制备去抗原异种骨支架材料的性能

背景：异种骨因其结构及生物特性与人体骨相似,经理化处理后抗原性降低,具有多孔结构,并且来源丰富、可以长期保存等特点,被认为是解决自体骨与异体骨来源不足的有效方法。目的：比较2种不同处理方法处理后去抗原异种松质骨支架材料的各项理化特性。方法：将经过化学方法处理的羊松质骨放入马弗炉中,在1 000℃高温下煅烧2 h制备成煅烧骨,将另一组经过化学处理的羊松质骨放入-80℃冰箱中冷冻4周,然后在真空仪器中干燥制备成冻干骨,将经过超纯水冲洗干净的羊松质骨当做对照组。结果与结论：3组样品均保留与人体骨组织类似的多孔三维结构,通过微观观察,它们的框架保存完整,有较小的孔隙（55-650μm）和较高的孔隙率（65%-80%）,煅烧后的支架材料韧性降低而脆性明显增加,冷冻干燥处理后力学性能则下降不大,经过衍射分析仪测定它们的主要成分为羟基磷灰石,但煅烧组中还含有少量的β-磷酸三钙,而能谱分析则证实3组的钙磷含量比均接近人体的钙磷比。结果提示经过这两种方法处理的松质骨与人体骨组织结构相似,其中各主要元素的含量比也与人体接近,而且具有足够小的孔隙和较高的孔隙率,但是煅烧处理对支架材料的力学性能影响比较大,而经过冷冻干燥处理力学性能下降不大但无法完全去除材料中的抗原成分,它们基本能达到骨组织工程支架材料的基本要求。     

Electrokinetic properties of human cryopreserved platelets

SUMMARY. A method for the cryopreservation of human platelets with glycerol/glucose is described which was a simplified modification of the method of Dayian and Pert (1979). The effect of cryoinjury of the platelet surface membrane was investigated by studying the surface electrokinetic properties of the platelet. A significant increase in platelet electrophoretic mobility was found after cryopreservation. The fresh platelets had a mean electrophoretic mobility of 1.04 ± 0.05 μm s^-1 V^-1 cm^-1 and cryopreserved platelets 1.18 ± 0.05 μm s^-1 V^-1 cm^-1, P < 0.05. However, the total platelet sialic acid of fresh platelets was 62.5 ± 5.6 nmol 10^-9 platelets compared to 47.2 ± 4.6 nmol 10^-9 platelets after cryopreservation, P < 0.001. Similarly, the neuraminidase-labile sialic acid was 26.4 ± 4.3 nmol 10^-9 platelets for fresh platelets and 17.6 ± 4.0 nmol 10^-9 platelets after cryopreservation, P < 0.001.
Using polyacrylamide gel electrophoresis with Western blotting, we showed a reduction in the platelet glycoprotein Gp Ib after cryopreservation, this was confirmed by using crossed immunoelectrophoresis. Electron microscopy revealed a significant change in platelet morphology after the cryopreservation procedure with disruption of the platelet membrane and also platelet shape change. These features may explain the changes in platelet electrokinetic properties.     

The swab rack--an outdated ritual.

The risk of Theatre Staff becoming infected from blood borne viruses such as HIV and Hepatitis B is steadily increasing. Sir David Cox's report (1988) predicted that the number of people infected with HIV by the end of 1987 would be between 20,000 and 50,000. Although these predictions are now thought to be more accurately estimated between 12,000 and 26,000, the number of people developing Aids is still expected to rise at an alarming rate. The precautions taken within the Theatre Department to reduce this risk are becoming transparently inadequate. It is no longer sufficient--or acceptable practice--to only be vigilant in avoiding blood contamination if the patient falls within a certain 'high risk' category. A happily married, middle aged woman may also be a virus carrier, particularly considering the long dormancy the HIV virus can exhibit before being detectable. It must be assumed that everyone is a potential carrier and the same precautionary measures taken for every patient, regardless of their past history, or present appearance.     

In vitro properties of platelets stored in three different additive solutions

BACKGROUND: New platelet (PLT) additive solutions (PASs) contain compounds that might improve the storage conditions for PLTs. This study compares the in vitro function, including hemostatic properties (clot formation and elasticity), of PLTs in T‐Sol, Composol, or SSP+ during storage for 5 days. STUDY DESIGN AND METHODS: Fifteen buffy coats were pooled and divided into three parts. PLT concentrates (PCs) with 30% plasma and 70% PAS (T‐Sol, Composol, or SSP+) were prepared (n = 10). Swirling, PLT count, blood gases, metabolic variables, PLT activation markers, and coagulation by free oscillation rheometry (FOR) were analyzed on Days 1 and 5. RESULTS: Swirling was well preserved and pH acceptable (6.4‐7.4) during storage for all PASs. Storage of PLTs in T‐Sol led to a decrease in PLT count whereas the number of PLTs was unchanged in Composol or SSP+ PCs. PLTs in T‐Sol showed higher glucose metabolism than PLTs in Composol or in SSP+. At the end of storage PLTs in T‐Sol had higher spontaneous activation and lower ability to respond to an agonist than PLTs in Composol or SSP+. PLTs in all the PASs had a similar ability to promote clot formation and clot elasticity. CONCLUSION: Storage of PLTs in Composol or in SSP+ improved the quality of PCs in terms of better maintained PLT count, lower glucose metabolism, lower spontaneous activation, and improved response to a PLT agonist compared to PLTs in T‐Sol. PLTs stored in the various PASs had similar hemostatic properties. These findings make Composol and SSP+ interesting alternatives as PASs.     

贮存过期红细胞的生化功能及形态的恢复研究

目的研究如何使贮存过期红细胞的生化功能和形态恢复到正常水平。方法恢复前红细胞组为ACD保养液在(4±2)℃贮存3周过期3d洗涤2次的红细胞,将此红细胞分成等量的2组,1组加入由腺嘌呤、肌苷、丙酮酸钠、磷酸氢二钠混合组成的恢复液作为恢复组,另1组加入25ml0.9%NaCl作为盐水对照组,2组均37℃孵育1h,从上清液中离心分离获得囊泡;将采集献血者新鲜全血的同时分离的红细胞作为正常水平组。分别测定4组红细胞ATP、2,3DPG、MCV、形态学积分、渗透脆性程度及Hb浓度。结果ATP、2,3DPG及形态学积分:恢复组比恢复前组和盐水对照组均显著增加(P<0.001),与正常水平组无显著差异(P>0.05)。MCV:恢复组显著低于恢复前组及盐水对照组(P<0.001)。恢复组与盐水对照组红细胞在0.50%和0.55%NaCl处的低渗性溶血度比恢复前组显著减少(P<0.05),与正常水平组无显著差异(P>0.05)。恢复组囊泡内脱落的Hb比盐水对照组显著增多(P<0.05)。结论腺嘌呤、肌苷、丙酮酸钠、磷酸氢二钠组成的恢复液可使ACD(4±2)℃贮存过期3d的红细胞的生化功能和形态都恢复到正常水平;在恢复再生过程中,出胞的微小囊泡引起细胞膜部分脱落,导致红细胞的MCV变小。     

The effect of salicylates on the hemostatic properties of platelets in man

Ingestion of 1.5 g of aspirin, but not of sodium salicylate, produced a significant prolongation of the bleeding time in six normal male subjects when compared with the effects of a placebo. Similar differences in the effect of the two drugs on platelets was also observed. Aspirin ingestion resulted in impaired platelet aggregation by connective tissue and was associated with a decreased release of platelet adenosine diphosphate (ADP); sodium salicylate had no effect on these values. In vitro, incubation of platelet-rich plasma with an optimum aspirin concentration of 0.50 mmole/liter (0.045 mg/ml) inhibited both the adhesion of platelets to connective tissue and the release of ADP as well as the secondary wave of platelet aggregation produced with ADP or epinephrine; sodium salicylate had no effect on these reactions, which were also normal in patients with von Willebrand's disease. The inhibitory effect produced by ingesting a single 1.8 g dose of aspirin was detectable for 4-7 days at which time salicylate was no longer detectable in the blood, which suggested an irreversible effect on the platelet. Aspirin also inhibited the release of platelet adenosine triphosphate (ATP), but had no effect on the platelet surface charge, available platelet ATP or ADP, or the destruction of ADP by plasma ADPase. These studies lend further support to the hypothesis that ingestion of aspirin, in contrast to sodium salicylate, prolongs the bleeding time by inhibiting the release of platelet ADP, perhaps reflecting the findings in other cell systems which suggest that aspirin alters membrane permeability.     

Effects of X-ray radiation on the rheologic properties of platelets and lymphocytes

BACKGROUND: Blood is often irradiated before transfusion for severely immunocompromised patients to prevent a potentially fatal complication of transfusion-associated GVHD. STUDY DESIGN AND METHODS: This study evaluates the effects of X-ray radiation on platelet and lymphocyte rheology because the ability of these blood cells to deform is vital to their flow throughout the microvascular system. Micropipette aspiration experiments were conducted on platelets and lymphocytes exposed to X-ray radiation doses of 0 (control), 25, and 50 Gy. RESULTS: A significant increase in the Young modulus of elasticity was observed between control platelets and irradiated platelets at 25 Gy (p = 0.02) and 50 Gy (p = 0.03). Percent cell activation increased significantly in 25 Gy-irradiated platelets (p = 0.008). In addition, lymphocytes irradiated at 25 Gy have a higher viscosity than controls (p < 0.02). A significantly larger number of activated cells is found in the 50 Gy-irradiated lymphocyte population (p < 0.04). CONCLUSION: The changes in the deformability and activation of irradiated platelets and lymphocytes may reduce local blood flow and lead to intermittent blockage, which may cause a change of blood flow in microvasculatures.     

冻干同种异体带鞘管肌腱移植的免疫学研究．

目的确定经冻干处理带鞘管同种异体移植肌腱移植的免疫学特性。方法将成年双A鸡40只随机均分为4组：带全鞘肌腱移植组、带部分鞘（包括A2-A4滑车）肌腱移植组、不带鞘肌腱移植组及对照组,各10只。分别于手术后3d、1周、2周、4周、6周测血清免疫学指标（IL-2及sIL-2R）并进行比较。结果冻干处理的移植肌腱并未引起外周血中IL-2及sIL-2R的显著变化,提示移植肌腱很少表达组织相容性抗原,移植物最终能被受体良好接受。结论带鞘管异体肌腱有良好的组织相容性。     

Evaluation of the Wound-healing Activity of Ethanolic Extract of Morinda citrifolia L. Leaf

Morinda citrifolia L. (noni) is one of the most important traditional Polynesian medicinal plants. The primary indigenous use of this plant appears to be of the leaves, as a topical treatment for wound healing. The ethanol extract of noni leaves (150 mg kg⁻¹ day⁻¹) was used to evaluate the wound-healing activity on rats, using excision and dead space wound models. Animals were randomly divided into two groups of six for each model. Test group animals in each model were treated with the ethanol extract of noni orally by mixing in drinking water and the control group animals were maintained with plain drinking water. Healing was assessed by the rate of wound contraction, time until complete epithelialization, granulation tissue weight and hydoxyproline content. On day 11, the extract-treated animals exhibited 71% reduction in the wound area when compared with controls which exhibited 57%. The granulation tissue weight and hydroxyproline content in the dead space wounds were also increased significantly in noni-treated animals compared with controls (P < 0.002). Enhanced wound contraction, decreased epithelialization time, increased hydroxyproline content and histological characteristics suggest that noni leaf extract may have therapeutic benefits in wound healing.     

冻干辐照猪硬脑膜的抗原性

背景:抗原性是异种组织移植最主要的问题,是移植成功与否的关键.目的:观察经冻干辐照处理后的猪硬脑膜抗原性变化.方法:取新鲜猪硬脑膜,经冻干、辐照处理后分别制备成冻干猪硬脑膜、辐照猪硬脑膜和冻干辐照猪硬脑膜.分别移植于大白兔硬脑膜上,于术后3,8周行各组实验动物淋巴细胞毒实验.结果与结论:移植冻干组和辐照组淋巴细胞死亡率比较差异无显著性意义(P＞0.05),但均高于冻干辐照组(P＜0.05).结果提示经冻干辐照处理后的猪硬脑膜抗原性低.