Bacteria levels in components prepared from deliberately inoculated whole blood held for 8 or 24 hours at 20 to 24 degrees C

BACKGROUND : An increase from 8 to 24 hours in the time that units of whole blood can be held at room temperature after phlebotomy would give blood centers more flexibility in component manufacturing and might allow receipt of many infectious disease test results prior to component preparation. However, the potential for bacterial growth during prolonged holding periods requires further study. STUDY DESIGN AND METHODS : In the Phase I study, 2-unit pools of ABO-identical whole blood were deliberately inoculated on Day 0 with Staphylococcus aureus or Pseudomonas fluorescens. They were then divided in half and stored at 20 to 24 degrees C. Red cells (RBCs) with additive solution, platelet concentrates (PCs), and frozen plasma were prepared after 8 and 24 hours. Bacteria levels in PCs and RBCs were monitored on Day 1; bacteria levels were measured in plasma after thawing. In the Phase II study, the same basic design as in Phase I was used, except that 10 bacterial species were studied, lower inocula were used, and RBCs prepared after a 24-hour room-temperature whole-blood hold were white cell-reduced by filtration. Bacterial growth was monitored during 42- day storage of RBCs (1 – 6 degrees C) and 5-day storage of PCs (20 – 24 degrees C) and after thawing of frozen plasma. RESULTS : For Phase I, significantly higher bacteria levels were observed in RBCs prepared after a prolonged hold (p < 0.05); higher levels were not observed in PCs and thawed plasma units. In Phase II, prior to white cell reduction by filtration, 8 of 10 organisms had significantly higher levels in RBCs prepared after a 24-hour hold than in RBCs prepared after an 8- hour hold, when both were examined on Day 1 (p < 0.05). For seven of eight organisms examined on Days 1, 21, and 42, filtration (white cell reduction) reduced the bacteria in RBCs prepared from 24-hour whole blood units to those levels found in unfiltered RBCs prepared from whole blood units held at 8 hours. A prolongation of the holding time from 8 to 24 hours resulted in significantly lower bacteria levels (p < 0.05) in PCs early in storage (Days 1, 1 – 2, or 1 – 3) for seven organisms, with no significant difference for two organisms, and a small but significant increase for one organism (Day 3, p < 0.05). There was no difference in bacteria or endotoxin levels in thawed units of plasma prepared from whole blood after 8- or 24-hour holding times. CONCLUSION : The levels of bacteria present in components after deliberately inoculated whole blood units are held for 8 and 24 hours depended on the organisms tested, the whole-blood holding period, and the blood component assayed; for RBCs, they also depended on whether WBC reduction by filtration was performed.     

Candida albicans stimulates local expression of leukocyte adhesion molecules and cytokines in vivo

The host inflammatory response to the opportunistic pathogen Candida albicans determines susceptibility to disseminated infection. This study used immunohistochemical analysis to correlate microbiologic findings and pathologic changes with local expression of cytokines and leukocyte adhesion molecules in mice with disseminated candidiasis. After being inoculated intravenously as blastospores, the organisms filamented extensively in the kidneys while remaining predominantly as blastospores or short germ tubes in the lung, liver, and spleen. Very few leukocytes accumulated around the invading organisms until 24 h after inoculation. The leukocytes at the infection site appeared to amplify the inflammatory response. They expressed interleukin-1beta, tumor necrosis factor-alpha, intercellular adhesion molecule 1, and platelet-endothelial cell adhesion molecule 1. Therefore, the morphology of the organism varies with the infection site. Furthermore, leukocyte recruitment occurs relatively late in the infection, and this recruitment is likely amplified by proinflammatory mediators produced by the leukocytes themselves.     

Candida albicans stimulates endothelial cell eicosanoid production

The response of human umbilical vein endothelial cells to invasion by Candida species was examined in vitro. Live Candida albicans caused significant endothelial release of eicosanoids, mainly prostaglandins. Since prostaglandin I2 (PGI2) is an important prostaglandin produced by endothelial cells, factors influencing its release were studied. The ability of different strains and species of Candida to induce endothelial PGI2 release was closely related to their capacity to injure the endothelium (r = .99). C. albicans was the only species tested that either stimulated PGI2 release or damaged the endothelial cells; only this organism possessed detectable phospholipase activity. Candida glabrata and Candida tropicalis had no phospholipase activity and neither increased PGI2 release nor caused significant endothelial damage. Close proximity with germinated C. albicans was required for endothelial injury and PGI2 release. The ability of C. albicans to stimulate endothelial cells may have important implications in regulating neutrophil activities against organisms that interact with endothelial cells.     

大黄素对大鼠原位肝移植术后急性排斥反应的干预

目的:目前国外已有少量报道证实中药大黄素具有极强的免疫抑制效应。实验拟进一步验证大黄素对同种异体大鼠肝移植术后早期急性排斥反应的干预效果。方法:实验于2004-01/2005-02在西安交通大学第一附属医院肝胆外科实验室完成。制备SD→Wistar大鼠全血供肝移植模型(n=80),按随机数字表法分为4组,每组20只。模型对照组、大黄素组、环孢素A组及环孢素A 大黄素组分别腹腔注射给予9g/L生理盐水、1.5mg/(kg·d)大黄素、3mg/(kg·d)环孢素A及3mg/(kg·d)环孢素 1.5mg/(kg·d)大黄素。术后观察大鼠一般情况,并于第7天各组分别处死10只大鼠,取肝脏标本及血清,观察移植肝组织排斥反应强度、Fractalkine(Fkn)阳性表达情况及大鼠血清中白蛋白含量及谷丙转氨酶活性,余受体继续应用药物干预直至死亡,记录其生存时间。结果:各组受体手术成功数量分别为模型对照组17只、大黄素组18只、环孢素A组18只、环孢素A 大黄素组18只。①与模型对照组相比,各用药组大鼠术后存活时间明显延长(P<0.05),以环孢素A 大黄素组存活时间最长。②与模型对照组相比,各用药组大鼠术后第7天移植肝排斥反应强度明显降低(P<0.05),血清中白蛋白含量明显升高,而谷丙转氨酶活性明显降低(P均<0.05),肝组织中Fkn表达阳性率明显降低(P<0.05),以环孢素A 大黄素组表现最为显著。结论:大黄素具有抑制同种异体大鼠肝移植急性排斥反应发生、发展的作用,与环孢素A联用具有协同作用。     

胰腺干细胞在糖尿病治疗中的应用

目的:本文就分离克隆胰腺干细胞,并将其定向诱导分化为功能性胰岛移植治疗糖尿病的研究作一综述。资料来源:应用计算机检索CBM和PubMed数据库1978-01/2006-12胰腺干细胞或胰岛干细胞移植治疗糖尿病的文章,检索词为"islet stem cell,pancreatic stem cell,diabetes mellitus,胰腺干细胞,胰岛干细胞,糖尿病"。资料选择:选择胰腺干细胞或胰岛干细胞移植治疗糖尿病的文章,排除重复研究。资料提炼:检索到CBM数据库中胰腺干细胞移植治疗糖尿病文章19篇,胰岛干细胞移植治疗糖尿病文章20篇;PubMed数据库中胰腺干细胞移植治疗糖尿病文章305篇。共纳入41篇。资料综合:糖尿病的治疗方法主要包括药物治疗、胰岛素注射、胰腺器官移植和胰岛细胞移植。胰腺器官移植和胰岛移植是治疗糖尿病的有效方法。由于缺乏完全合适的供体,胰腺器官移植的临床应用受到限制。与胰腺器官移植相比,胰岛细胞移植无需麻醉和剖腹,减小了对移植受体的损伤,降低了风险性。结论:体外分离、克隆人类胰腺干细胞,并定向诱导其分化为功能性胰岛移植治疗糖尿病,是解决胰岛供体短缺的有效途径,但是还没有人胰腺干细胞体外诱导胰岛移植治疗人类糖尿病的报道。     

Predicting survival in AIDS: refining the model

We tested the validity of a previously-published AIDS staging system by examining AIDS-defining diseases (ADDs) and CD4 counts as prognostic factors for survival of the 248 AIDS patients in the Edinburgh City Hospital Cohort, of whom 56% were injecting drug-users (IDUs). Cox regression was used to model the proportionality of risk of death as the CD4 count declined and more ADDs were experienced, and dependence upon post-AIDS treatment. Using the system of Mocroft et al. (Lancet 1995; 346:12-17) to grade severity, our data were well enough modelled, but we suggest: (i) regrading of HIV dementia (RR 3.9, 95% CI 2.5-6.0), mainly attributed to the drug users, to a very severe ADD; (ii) reduction in risk from zidovudine (RR 0.7, 95% CI 0.5-1.0) during AIDS follow-up for patients starting treatment at or after AIDS diagnosis; (iii) improved management of first mild ADDs (from 1987-89 to 1994-95: 40% reduction in IDUs appearing with mild index diseases, and an approximate three-fold reduction in risk associated with a mild ADD). This study supports previous findings on the significance of ADDs and lowest CD4 count in predicting the lifetime of AIDS patients.      

Genetic basis for differential activities of fluconazole and voriconazole against Candida krusei

Invasive infections caused by Candida krusei are a significant concern because this organism is intrinsically resistant to fluconazole. Voriconazole is more active than fluconazole against C. krusei in vitro. One mechanism of fluconazole resistance in C. krusei is diminished sensitivity of the target enzyme, cytochrome P450 sterol 14alpha-demethylase (CYP51), to inhibition by this drug. We investigated the interactions of fluconazole and voriconazole with the CYP51s of C. krusei (ckCYP51) and fluconazole-susceptible Candida albicans (caCYP51). We found that voriconazole was a more potent inhibitor of both ckCYP51 and caCYP51 in cell extracts than was fluconazole. Also, the ckCYP51 was less sensitive to inhibition by both drugs than was caCYP51. These results were confirmed by expressing the CYP51 genes from C. krusei and C. albicans in Saccharomyces cerevisiae and determining the susceptibility of the transformants to voriconazole and fluconazole. We constructed homology models of the CYP51s of C. albicans and C. krusei based on the crystal structure of CYP51 from Mycobacterium tuberculosis. These models predicted that voriconazole is a more potent inhibitor of both caCYP51 and ckCYP51 than is fluconazole, because the extra methyl group of voriconazole results in a stronger hydrophobic interaction with the aromatic amino acids in the substrate binding site and more extensive filling of this site. Although there are multiple differences in the predicted amino acid sequence of caCYP51 and ckCYP51, the models of the two enzymes were quite similar and the mechanism for the relative resistance of ckCYP51 to the azoles was not apparent.     

Recruiting blood donors into a local bone marrow donor registry

To date, most persons joining bone marrow donor registries have been recruited from platelet-pheresis panels. The potential of recruiting regular blood donors into bone marrow donor registry (BMDR) was explored. It was found that, with minimal effort, 6.2 percent of the age-eligible blood donors were recruited. A distinguishing feature of those who joined the BMDR was a history of frequent blood donations. Although local media attention had a major impact on recruitment, even those joining as a result of the publicity usually were regular blood donors. This program has the potential to recruit nearly 8000 volunteers from 120,000 regular blood donors over an 18-month period.     

CYCLICAL ETIDRONATE INCREASES LUMBAR SPINE BONE DENSITY IN PATIENTS ON LONG-TERM GLUCOCORTICOSTEROID THERAPY

To determine whether cyclical etidronate modifies bone density in patients on chronic glucocorticosteroid therapy, annual bone density measurements were performed on 55 patients receiving glucocorticosteroids who were randomised to either continuous calcium supplementation or cyclical etidronate plus calcium supplementation in this secondary prevention study. Median L1-L4 lumbar spine bone density decreased by 0.7% in the calcium treated group after one year but increased by 3.1% in the group treated by calcium and etidronate (p=0.00116). Median L1-L4 bone density decreased by 2.8% from baseline after two years in the calcium treated group but increased by 4.7% from baseline In the group treated by calcium and etidronate (p=0.04). There were no significant effects of treatment on femoral neck density. Cyclical etidronate and calcium increased lumbar spine bone density in patients established on prednisolone treatment over a two-year period but had no effect on femoral density.     

Survival of Borrelia burgdorferi in blood products

The incidence of Lyme disease is rapidly increasing in the United States. To assess the potential of transmission of the disease through blood transfusion, we studied the survival of Borrelia burgdorferi in blood products under blood bank storage conditions. Two units of whole blood, separated into red cells (RBCs), fresh-frozen plasma (FFP), and platelet concentrates (PCs), were inoculated with B. burgdorferi (strain B31) in concentrations of approximately 3000 organisms per mL of RBCs and FFP and 200 organisms per mL of PCs. Products were then stored under blood banking conditions and sampled at several storage times. The viability of the spirochete in blood components was determined by darkfield microscopic examination of cultures in modified Kelly's medium. The organism was shown to survive in RBCs (4 degrees C) and FFP (below -18 degrees C) for 45 days and in PCs (20-24 degrees C) for 6 days. The results of this study do not exclude the possibility of transmission of Lyme disease through blood transfusion.