Cystic fibrosis heterozygotes do not have increased platelet activation

INTRODUCTION: We have previously demonstrated platelet hyperreactivity in cystic fibrosis (CF) patients. Carriers of one CF mutation (heterozygotes) have been shown to have abnormalities related to the presence of only one-half the normal amount of CF transmembrane conductance regulator protein. Platelet hyperreactivity in CF heterozygotes would be an important cardiovascular risk factor, since approximately 1 in 25 Caucasians is a CF carrier. MATERIALS AND METHODS: We used highly sensitive assays of platelet activation to assess the difference between 16 CF heterozygotes and 16 age- and sex-matched healthy controls without CF mutations. RESULTS: We found no difference in platelet activation between CF heterozygotes and controls. CONCLUSIONS: The 50% reduction in the CF transmembrane conductance regulator protein in heterozygotes is insufficient to cause platelet activation.     

Ex vivo microvesicle formation after prolonged ischemia in renal transplantation

INTRODUCTION: Patients with chronic renal failure suffer from dysfunction in coagulation. Kidney transplantation induces inflammatory reactions and thus activation of platelets. Activated platelets, in turn, form microvesicles by shedding. These microvesicles have been shown to have coagulant activities. Activated platelets in prolonged cold ischemia were associated with delayed graft function and inferior survival. We investigated ex vivo formation of microvesicles in kidney transplantation and the influence of cold graft storage on microvesicles. METHODS: 20 patients (47.4+/-10.6 years (mean+/-SD)) undergoing transplantation were included in the study after written informed consent. Dependent on cold preservation time of transplanted kidneys, recipients were allocated into two groups with 10.4+/-6.1 h (group 1) and 23.7+/-3.8 h (group 2) preservation time, respectively. Blood samples were drawn before anesthesia, 12 h, 2, 7 and 14 days after transplantation. To evaluate microvesicle release, samples were activated with thrombin-receptor-activating-peptide-6 (TRAP) or adenosine-di-phosphate. Microvesicles were counted as percentage of platelets smaller than a predetermined size in flow cytometry. RESULTS: Platelet derived ex vivo microvesicle formation was significantly higher up to 48 h after transplantation when stimulated with TRAP in group 1. Platelet count was significantly higher compared to baseline values in the short-term ischemia group but not with long-term ischemia. Creatinine was significantly lower at study end compared to baseline with no differences between both groups. CONCLUSIONS: Lower platelet microvesicle formation after ex vivo stimulation with TRAP was associated with longer graft ischemia time. This may be a sign of former activation of platelets which could influence graft function and survival.     

Transdermal 17-beta estradiol replacement therapy reduces megakaryocyte GPVI expression

The platelet-collagen interaction is a critical early event in arterial thrombus formation, and platelet GPVI is the major activating receptor for collagen. We have previously used a mouse model to demonstrate that the estrogen effects on platelets depend upon the agonist, estrogen formulation and route of administration. In the current study we used a model of transdermal estradiol (E2) administration to ovariectomized mice to address the potential inhibitory effects of E2 on platelet GPVI. Platelet GPVI expression was reduced after transdermal E2 replacement therapy (p ≤ 0.001) but no evidence of GPVI shedding was found when platelets were directly incubated with E2. In addition, significantly reduced GPVI-mediated fibrinogen binding and aggregation were observed in platelets from mice subjected to 9 days or longer of in vivo E2 treatment, but not in platelets from mice treated for 3 days or shorter, suggesting an indirect pathway. Studies with mouse bone marrow revealed that E2 replacement in ovariectomized mice reduces megakaryocyte GPVI expression. This data suggest that transdermal E2 is able to affect centrally on megakaryocyte GPVI to regulate platelet GPVI and function.     

mTOR负调控miR-27a并通过靶向降低GP73抑制人肝癌细胞侵袭

目的探索m TOR促进肝癌细胞侵袭能力机理。方法使用q-PCR方法检测miR-27a和GP73表达;将miR-27a的mimic转染GP73高表达的M97H细胞中,并将miR-27a inhibitor转入GP73低表达Hep G2细胞中,q-PCR和Western blot观察GP73的表达;使用荧光素酶报告基因系统验证miR-27a在GP73的3UTR区的结合位点;将miR-27a mimic转染GP73高表达的M97H细胞和GP73低表达的Hep G2细胞,Transwell实验观察细胞的侵袭。结果m TOR下调miR-27a,并上调GP73的表达;miR-27a下调GP73的表达,抑制miR-27a则上调GP73;GP73是miR-27a的靶基因;miR-27a显著抑制M97H细胞的侵袭,但对Hep G2细胞无抑制效果。结论 m TOR负调控的miR-27a靶向GP73抑制肝癌细胞的侵袭。     

Biocompatibility of a new cell separator studied by flow cytometry: analyses of platelet antigens during apheresis and storage

BACKGROUND: Alterations of platelet antigens are known to occur during cytapheresis and storage. These changes have been shown to be dependent on the biomaterials, techniques, and devices used. In this study, the influence of a new cell separator (AMICUS) and storage container (PL-2410) on platelet glycoproteins was analyzed. STUDY DESIGN AND METHODS: During plateletpheresis and storage, the levels of platelet glycoproteins and binding of fibrinogen were determined by flow cytometry. RESULTS: During apheresis, mean channel fluorescence intensity of CD41 a did not change significantly (p = 0.06). A small increase was evident in CD42b mean channel fluorescence intensity, which rose from a baseline level of 178.6 +/- 68.3 to 231.5 +/- 97.9 at the end of the procedure (p<0.05); in CD62p-positive platelets, which increased from 2.0 +/- 0.9 percent to 9.9 +/- 3.9 percent (p<0.05); in CD63-positive platelets, which increased from 1.7 +/- 0.7 percent to 7.9 +/- 2.6 percent (p<0.05); and in the binding of fibrinogen, which increased from 1.9 +/- 0.8 percent positive platelets to 10.5 +/- 2.6 percent (p<0.05). During storage, the mean channel fluorescence intensity of CD41a and CD42b, the percentage of CD62p- and CD63-positive platelets, and the binding of fibrinogen to platelets showed no significant change. CONCLUSION: These studies show that alterations in platelet antigens and platelet activation occur to a small degree during apheresis and storage. These findings demonstrate generally good biocompatibility of this new cell separator.     

A single amino acid substitution modulates low-pH-triggered membrane fusion of GP64 protein in Autographa californica and Bombyx mori nucleopolyhedroviruses

We have previously shown that budded viruses of Bombyx mori nucleopolyhedrovirus (BmNPV) enter the cell cytoplasm but do not migrate into the nuclei of non-permissive Sf9 cells that support a high titer of Autographa californica multicapsid nucleopolyhedrovirus (AcMNPV) multiplication. Here we show, using the syncytium formation assay, that low-pH-triggered membrane fusion of BmNPV GP64 protein (Bm-GP64) is significantly lower than that of AcMNPV GP64 protein (Ac-GP64). Mutational analyses of GP64 proteins revealed that a single amino acid substitution between Ac-GP64 H155 and Bm-GP64 Y153 can have significant positive or negative effects on membrane fusion activity. Studies using bacmid-based GP64 recombinant AcMNPV harboring point-mutated ac-gp64 and bm-gp64 genes showed that Ac-GP64 H155Y and Bm-GP64 Y153H substitutions decreased and increased, respectively, the multiplication and cell-to-cell spread of progeny viruses. These results indicate that Ac-GP64 H155 facilitates the low-pH-triggered membrane fusion reaction between virus envelopes and endosomal membranes.     

Western European best practice in primary healthcare

Objective: To establish how general practitioners (GPs) in the Netherlands diagnose and treat vaginal candidiasis. Methods: Questionnaires were sent to 1160 Dutch GPs. The GPs were asked to make an inventory of the annual number of consultations for vulvovaginal candidiasis. Furthermore, information was requested with regard to diagnostic examinations performed and preferred treatment when dealing with vulvovaginal candidiasis. Results: 380 (32.87%) GPs returned the questionnaire, of which 189 GPs worked in single-person practices (n=189). The group of 380 GPs consisted of 269 (70.8%) males and 111 (29.2%) females. On average, GPs reported 105.6 consultations concerning vaginal candidiasis per practice per year. Only 61 (16.1%) Dutch GPs always or often performed microscopy when diagnosing candidiasis, while 143 (37.6%) GPs never used a microscope to confirm their diagnosis. Furthermore, only 30 (7.9%) GPs regularly took Candida cultures, whereas 154 GPs (40.5%) never took a vaginal swab to diagnose acute candidiasis. Treatment of choice was mostly miconazole (50%) or clotrimazole (24%).

Conclusion: GPs often diagnose “vulvovaginal candidiasis” in their practices, but often do not perform the laboratory examinations required to confirm their putative diagnosis. This may lead to wrong diagnoses and maltreatment with antimycotics, without cure of the patients’ vaginal complaints.