Improving auscultatory blood pressure measurement with electronic and computer technology: the visual auscultation method

BACKGROUND

The auscultatory method is used as the reference standard in all prevalent protocols for validation of noninvasive blood pressure measuring devices, and a validation study is essentially based on the comparison between the device and observer measurements. Thus, the objectivity and accuracy of observer measurements are crucial to the validation result.

METHODS

To provide observers with more objective information about an auscultatory measurement so that sufficient information to make measurements with greater potential objectivity and accuracy can be available, a computerized data acquisition and analysis system has been developed. It cannot only acquire and store Korotkoff sound, cuff pressure, and oscillometric pulse signals, as well as the sphygmomanometer image, but it also can display the waveforms of the three signals and the sphygmomanometer video while playing the synchronous Korotkoff sounds. With this system, observers can make their measurements via the visual auscultation method, that is to say, by watching those waveforms, instead of the sphygmomanometer, while listening for synchronized Korotkoff sounds. The system was validated according to the International Protocol (IP).

RESULTS

The result showed that all the differences between system measurements by the visual auscultation method and observer measurements by the conventional auscultatory method were within 4 mm Hg.

CONCLUSIONS

The visual auscultation method achieved a high degree of accuracy, and human observers can be replaced by the system in the validation study of blood pressure measuring devices.

Circulating cytokine and angiogenic factors as predictive biomarkers of glioblastoma response to aflibercept (VEGF Trap)

2029

Background: Aflibercept is a recombinant fusion protein that scavenges both vascular endothelial growth factor (VEGF) and placental growth factor (PlGF). In a single-arm phase II study (NABTC06–01; NCT00369590 ), a 22% response rate was seen in recurrent glioblastoma patients receiving aflibercept 4 mg/kg iv every 2 weeks. We performed detailed analyses of circulating and urinary cytokine and angiogenic factors to describe the modulation of markers in response to aflibercept and to identify potential predictive markers. Methods: Plasma samples were collected from 31 of 32 enrolled patients at baseline, 24 hours and every 2–4 weeks until progression. Urine samples were collected at baseline and every 4 weeks. Levels of 41 circulating factors were measured using suspension bead multiplex assays (BioRad) or ELISA. Free VEGF and PlGF levels were determined following sample immunodepletion. Baseline and changes in marker levels over time were correlated with response and progression using logistic regression and Cox proportion hazard models. Results: Treatment with aflibercept resulted in significant increases in total VEGF and PlGF at 24 hours and 28 days (p ≤ 0.001). Free VEGF was rapidly sequestered by 24 hours and remained significantly decreased at 28 days (p = 0.001). However, free PlGF levels rose over time and by 28 days were 45-fold higher than baseline (p < 0.001). Additional modulation of 4 factors at 24 hours included decreases in Groα and MIF (p = 0.001) and increases in urinary VEGF and MIP1β (p ≤ 0.001). At 28 days, levels of IL-18 were significantly decreased (p = 0.02) while SCGFβ and urinary VEGF levels increased (both p < 0.02). Comparing baseline biomarker levels between response groups (PD, SD, and PR), patients with lower levels of GROα, HGF, SCGFβ and higher levels of free VEGF were more likely to have a PR (all p < 0.05). Conclusions: In recurrent glioblastoma, aflibercept resulted in rapid and sustained decreases in free VEGF levels. Although greater than 95% of PlGF remained bound, free PlGF levels significantly increased over time. Treatment significantly modulated multiple cytokine and angiogenic factors with striking increases in MIF and SCGFβ. Potential biomarkers predictive of response to aflibercept include Groα, HGF and SCGFβ.

No significant financial relationships to disclose.

Susceptibility of head and neck cancer to an attenuated model of the oncolytic vesicular stomatitis virus expressing suicide genes

e14604

Background: The predominant loco-regional progression of head and neck squamous cell carcinoma (HNSCC) makes it suitable for testing oncolytic viruses. Recent work from several laboratories including ours has focused on developing vesicular stomatitis virus (VSV) as a replication-competent anticancer viral vector. Attenuated strains, such as M protein mutant VSV (M51R) are more likely to be promoted in clinical research. The major shortcoming of viral therapy is related to the large proportion of tumor cells remaining uninfected. We are addressing this limitation in two ways: the expression of the cytosine deaminase-uracil phosphoribosyltransferase (C:U) suicide gene by the rVSV vector, expected to produce a strong bystander effect and the exploitation of the radiosensitizing potential of the 5-FU chemo-drug produced intratumorally, as well as of the VSV virus itself. Methods: We determined the extent of defectiveness in interferon pathways and susceptibility to oncolytic VSV in a collection of HNSCC cell lines and in patient HN primary tumor cells. We employed gene array to screen for differences in gene expression in sensitive and resistant models. We have generated the rVSV-C:U and M51R-C:U viruses and we tested our collection of HNSCC cell models to infection with these viruses in the presence and absence of 5-FC. In vivo experiments were performed on a localized and on a metastatic SQ-20B model of HNSCC in nude mice. Results: 1) the primary patient HNC cells are more resistant than the HNC cell lines to the M51R-VSV; 2) the activation of IFN pathways and /or alterations of AKT pathway is contributing to resistance to VSVs. 3) Addition of the suicide gene to the attenuated VSV provided significantly more oncolytic effect in vitro and in vivo. The efficacy and the radiosensitizing potential of M51R- C:U on a nude mice model of HNSCC (SQ-20B) will be presented. Conclusions: M51R-VSV has increased efficiency and radiosensitizing effect on HNSCC models. We can define an optimal approach to testing VSV vectors for treatment of HNSCC, with a clinical trial in HNSCC patients as our next goal. Finally, we have important new information, both from cell lines and patient tissues, for proof-of-principle that cancers can down-regulate antiviral responses.

No significant financial relationships to disclose.

Phase IIb trial of fluorouracil, leucovorin, oxaliplatin, and paclitaxel (POF) compared with fluorouracil, feucovorin, and irinotecan (IF) as first-line treatment for advanced gastric cancer (AGC)

e15642

Background: Primary results of POF as 1st and 2nd line treatment for AGC have been presented at ASCO 2007 and 2008. We report here data on the feasibility and the toxicity of POF versus IF(Dank, et al, ASCO 2005) in 1st line treatment of AGC. Methods: Patients with previously untreated, advanced, unresectable, and histologically confirmed adenocarcinoma of the gastric or gastroesophageal junction were randomly assigned to POF or IF regiment. Treatment was continued until disease progressed, unacceptable toxicity, or patient choice. Results: 25 patients were entered in this study between March 2007 and July 2007: 13 in the POF group and 12 in the IF group. The median patient age was 55 years (range, 36 to 67 years), 18 were males and 7 were females. No complete response was observed. The response rate was 62.5% (POF) and 33.3% (IF) respectively. At a median follow-up of 285 days, 7(POF) versus 6(IF) patients were still alive. Hematological toxicity was the most frequent toxicity in both groups. Grade 3 to 4 neutropenia were 38.5% (POF) versus 8.3% (IF). Diarrhea was found 0% and 8.3% in POF and IF group respectively. No grade 3 peripheral neurotoxicity was observed. Conclusions: Compared with IF regiment, POF could also be used as first-line treatment for AGC with acceptable safety profile, good efficacy, and more encouraging results.

No significant financial relationships to disclose.

Elevated troponin and abnormalities of cardiac structure and function in AL cardiac amyloidosis

e19524

Background: Patients with systemic amyloidosis involving the heart have generally a poor prognosis. Elevated cardiac troponin (cTn) has been shown to predict poor survival in patients with AL cardiac amyloidosis (CA). However, cardiac structure and function associated with an elevated cTn in patients with CA remains uncertain. Methods: Eighty patients with CA who had an echocardiogram and cTnI measured at the time of diagnosis between March 1997 May 2008 were included in the study. The patients were divided into 2 groups: normal cTnI ( <0.06 ng/ml, n = 28) or elevated cTnI (≥0.06 ng/ml; n = 52). Results: The elevated cTnI group was slightly older with higher brain natriuretic peptide (BNP) level and creatinine clearance than the normal cTnI group. There was a trend towards higher prevalence of congestive heart failure (CHF) in the elevated cTnI group than the normal group at time of diagnosis. The elevated cTnIgroup had thicker interventricular septum and higher left atrial (LA) volume than the normal group. LV ejection fraction, left atrial systolic force (LASF) and stroke volume were lower in the elevated cTnI group than the normal group. Mean survival was significantly shorter in the elevated cTnI group than the normal group (10 vs. 47 months). Conclusions: Elevated troponin in patients with AL cardiac amyloidosis is associated with worse left atrial and ventricular structure and function. The raised troponin level reflects myocardial injury due to the amyloid deposition and correlates with more abnormal alteration of cardiac structure and function. Routine measurement of troponin is useful in identifying high risk patients with CA.

[Table: see text]

No significant financial relationships to disclose.

Cytokines and angiogenic factors in metastatic renal cell cancer: Association of pretreatment serum levels with survival

e16036

Background: To correlate serum cytokine and angiogenic factor (CAF) levels and overall survival (OS) in metastatic renal cell cancer (mRCC) treated with interferon-alpha (IFN-α). Methods: Serum CAF levels were measured in 103 patients treated on a randomized trial with IFN-α 0.5 million units (MU) twice daily or 5 MU daily. Concentrations of 17 analytes including vascular endothelial growth factor (VEGFA) and several cytokines were determined by multiplex bead immunoassays or ELISA (basic fibroblast growth factor). We used proportional hazards models to evaluate the effect of CAF levels and clinical factors on OS. Results: Pretreatment serum interleukin (IL)-5, IL-12p40, VEGFA, and IL-6 levels, and Memorial Sloan-Kettering Cancer Center risk grouping were independently correlated with OS, with hazard ratios of 2.33, 2.00, 2.07, 1.82 and 0.39, respectively (concordance index = 0.69 for the combined model versus 0.60 for the CAF model versus 0.52 for the clinical model). Based on an index derived from these five risk factors (RF), patients with 0–2 RF had a median OS time of 32 months, versus 9 months for patients with 3–5 RF (p < 0.0001). Conclusions: Serum CAF profiling contributes to prognostic evaluation in mRCC and helps to identify a subset of patients with 20% 5-year OS.

No significant financial relationships to disclose.

The patterns of care studies for operable breast cancer in China

e11607

Background: To present the results of clinical practices for operable breast cancer (BC) in the developed areas of China during the past decade. Methods: Four academic levels of radiotherapy (RT) departments, located in the Southeast coast of China, were selected. A pattern of care study, about women with operated BC and post-operative RT during 1999 and 2006, was conducted. The recruited samples were evaluated for their medical files completeness at first. For qualified documentations, data collected included patient characteristics, clinical and pathologic features, and treatment course received. Frequencies and corresponding percentages were calculated and analyzed for comparisons between 1999 and 2006. Results: 97 in 1999 and 271 in 2006 were identified as qualified files. Patient's diagnosis median age were 48 (1996) and 46 (2006) years. The clinical staging with I, II, and III (UICC 1997) were in 11%, 69%, 13% of 1999 patients and 15%, 74%, 7% of the 2006. The pathological characteristics were clearly defined in 78% (1999) and 84% (2006), but hormonal receptors and Her2neu were performed in 59% and 0% in the 1999 vs. 73% (p < 0.05) and 1% in 2006 survey. As type and extent of surgery and RT, the percentage of conservative treatment was increased from 4% in 1999 to 12% in 2006 (p< 0.05), postmastectomy RT was done for all the others. The time interval from operation to initiation of RT were longer in 2006, the mean was delayed from 23.8 to 43.4 days. The axillary operation pattern including lymph node dissection, level I/II dissection, and sentinel lymph node biopsy (SLNB), were documented in 61%, 24%, and 8% of patients in 2006. For patients of 1999, no SLNB was performed and 16% with level I/II operation (p< 0.05). Systemic chemotherapy (CT) and/or hormonal therapy were used in 74% (1999) and 98% (2006) of patients respectively (p< 0.05). Anthracyclines and paclitaxel-based CT regimens use significantly increased between 1999 and 2006 (31% vs. 52% and 12% vs. 36%). Conclusions: The practice patterns established in this study provide a baseline data. The present results demonstrate a low level of compliance with Western guidelines of clinical practices with current BC standards and continued improvement in many categories. Establishment and widespread use of international guidelines in China are desirable.

No significant financial relationships to disclose.

Stent-assisted embolization of wide-neck anterior communicating artery aneurysms: review of 21 consecutive cases

BACKGROUND AND PURPOSE

Anterior communicating artery (AcomA) aneurysm is the most frequent form of aneurysm. Stent placement is particularly difficult and of limited use for AcomA aneurysms. We report our experience with stent-assisted embolization for wide-neck AcomA aneurysms in 21 patients. Particular attention is given to the morphologic characteristics and strategy of stent deployment.

MATERIALS AND METHODS

Between January 2005 and February 2008, stent-assisted coiling was performed in 21 patients with wide-neck AcomA aneurysms. Patient demographics, aneurysm morphology, procedures, and clinical and angiographic outcomes were retrospectively reviewed.

RESULTS

Successful deployment of the stent in the targeted artery was achieved in all patients. Nineteen Neuroform 2 or Neuroform 3 stents and 2 LEO stents were used. The distal segment of the stent was positioned in the ipsilateral A2 in 12 patients, in the contralateral A2 across the AcomA in 5 patients, and into the aneurysm sac in 4 patients. Complete occlusion was achieved in 18 patients; near-complete occlusion, in 2 patients; and partial occlusion, in 1 patient. Intraoperative perforation of the aneurysm developed in 1 patient, which was secured by subsequent coiling. Angiographic follow-up in 12 patients for 6.9 months showed 1 recanalization and no in-stent stenosis.

CONCLUSIONS

Our preliminary results suggest that stent-assisted embolization for wide-neck AcomA aneurysms is technically feasible and safe. Further follow-up is needed for long-term efficacy of stent placement.

The firing activity of pyramidal neurons in medial prefrontal cortex and their response to 5-hydroxytryptamine-1A receptor stimulation in a rat model of Parkinson's disease

The changes in the firing rate and firing pattern of pyramidal neurons in medial prefrontal cortex (mPFC) and the effects of selective 5-hydroxytryptamine-(1A) (5-HT(1A)) receptor agonist (R)-(+)-8-hydroxy-2-(dipropylamino)tetralin hydrobromide (8-OH-DPAT) and antagonist N-(2-(4-(2-methoxyphenyl)-1-piperazinyl)ethyl)-N-2-pyridylcyclohexane carboxamide maleate salt (WAY-100635) on the firing activity of the neurons were studied in sham-lesioned rats and rats with 6-hydroxydopamine lesions of the substantia nigra pars compacta (SNc). The lesion of the SNc increased the firing rate of pyramidal neurons significantly compared to sham-lesioned rats, and the firing pattern of these neurons also changed significantly towards a more burst-firing. The systemic administration of 8-OH-DPAT at doses in the range of 0.5-128 microg/kg showed an excitatory-inhibitory effect on the firing rate of pyramidal neurons in mPFC of sham-lesioned rats. At lower doses, 0.5-32 microg/kg, it evoked excitation of the neurons, and at a high dose, i.e. 128 microg/kg, inhibited the activity of the neurons. In contrast to sham-lesioned rats, 8-OH-DPAT, at the same doses, showed no excitatory effect in the lesioned rats although the inhibitory phase of the effect of 8-OH-DPAT on the firing rate of pyramidal neurons in mPFC was still present. Furthermore, the local application of 8-OH-DPAT, 5 microg, in mPFC inhibited the firing rate of pyramidal neurons in sham-lesioned rats, while having no effect on firing rate in the lesioned rats. The excitatory or inhibitory effects of 8-OH-DPAT were reversed by WAY-100635, indicating that these effects are mediated by 5-HT(1A) receptor. Altogether, these results indicate that the lesion of the SNc leads to hyperactivity of pyramidal neurons in mPFC and the abnormality of response of these neurons to 5-HT(1A) receptor stimulation, suggesting that mPFC may be involved in the pathophysiology of the psychiatric disturbance of Parkinson's disease.

Neuroglobin-overexpression alters hypoxic response gene expression in primary neuron culture following oxygen glucose deprivation

Neuroglobin (Ngb) is a tissue globin specifically expressed in neurons. Our laboratory and others have shown that Ngb overexpression protects neurons against hypoxia/ischemia, but the underlying mechanisms remain poorly understood. Recent studies demonstrate that hypoxia/ischemia induces a multitude of spatially and temporally regulated responses in gene expression, and initial evidence suggested that Ngb might function in altering biological processes of gene expression. In this study, we asked how Ngb may help regulate genes responsive to hypoxia. Expression of hypoxic response genes following oxygen-glucose deprivation (OGD) was examined using mRNA arrays in neuroglobin-overexpressing transgenic (Ngb-Tg) and wild type (WT) mouse neurons. From a total of 113 genes on the microarray, mRNA expression of 65 genes was detected. Under rest condition, 14 genes were downregulated in Ngb-Tg neurons compared to WT. In WT neurons, after 4-h OGD followed by 4-h reoxygenation (O4/R4), 20 genes were significantly downregulated, and only Fos mRNA was significantly increased. However, out of the 20 downregulated genes in WT neurons, 12 of them were no longer significantly changed in Ngb-Tg neurons: Add1, Arnt2, Camk2g, Cstb, Dr1, Epas1, Gna11, Hif1a, Il6st, Khsrp, Mars and Rara. Among these 12 genes, 8 (Add1, Camk2g, Cstb, Dr1, Epas1, Gna11, Hif1a, Khsrp) were already reduced in Ngb-Tg neurons compared to WT under rest conditions. Additionally, three genes that initially showed no changes in WT neurons (Ctgf, Egfr and Pea15) were downregulated after OGD in the Ngb-Tg neurons. These findings suggest that Ngb overexpression modulates mRNA expression of multiple hypoxic response genes in the early phase after OGD/reoxygenation. Further studies on these gene networks and interactions may lead to better understanding of Ngb in signaling pathways that contribute to neuroprotection.

Clonal integration supports the expansion from terrestrial to aquatic environments of the amphibious stoloniferous herb Alternanthera philoxeroides

Effects of clonal integration on land plants have been extensively studied, but little is known about the role in amphibious plants that expand from terrestrial to aquatic conditions. We simulated expansion from terrestrial to aquatic habitats in the amphibious stoloniferous alien invasive alligator weed (Alternanthera philoxeroides) by growing basal ramets of clonal fragments in soils connected (allowing integration) or disconnected (preventing integration) to the apical ramets of the same fragments submerged in water to a depth of 0, 5, 10 or 15 cm. Clonal integration significantly increased growth and clonal reproduction of the apical ramets, but decreased both of these characteristics in basal ramets. Consequently, integration did not affect the performance of whole clonal fragments. We propose that alligator weed possesses a double-edged mechanism during population expansion: apical ramets in aquatic habitats can increase growth through connected basal parts in terrestrial habitats; however, once stolon connections with apical ramets are lost by external disturbance, the basal ramets in terrestrial habitats increase stolon and ramet production for rapid spreading. This may contribute greatly to the invasiveness of alligator weed and also make it very adaptable to habitats with heavy disturbance and/or highly heterogeneous resource supply.

Role of cGMP-dependent protein kinase in regulation of pulmonary vascular smooth muscle cell adhesion and migration: effect of hypoxia

Exposure to prolonged hypoxia can result in pulmonary vascular remodeling and pulmonary hypertension. Hypoxia induces pulmonary vascular smooth muscle cell (PVSMC) proliferation and vascular remodeling by affecting cell adhesion and migration and secretion of extracellular matrix proteins. We previously showed that acute hypoxia decreases cGMP-dependent protein kinase (PKG) activity in PVSMC and that PKG plays a role in maintaining the differentiated contractile phenotype in normoxia. In this study, we investigated the effect of hypoxia on PVSMC adhesion and migration and the role of PKG in these functions. Ovine fetal pulmonary artery SMC were incubated in normoxia (Po(2) approximately 100 Torr) or hypoxia (Po(2) approximately 30-40 Torr) or treated with the PKG inhibitor DT-3 for 24 h in normoxia. To further study the role of PKG in the modulation of adhesion and migration, PVSMC were transiently transfected with a full-length PKG1alpha [PKG-green fluorescent protein (GFP)] or a dominant-negative construct (G1alphaR-GFP). Cell adhesion to extracellular matrix proteins was determined, and integrin-mediated adhesion was assessed by alpha/beta-integrin-mediated cell adhesion array. Exposure to hypoxia (24 h) and pharmacological inhibition of PKG1 by DT-3 significantly promoted adhesion mediated by alpha(4)-, beta(1)-, and alpha(5)beta(1)-integrins to fibronectin, laminin, and tenacin and also resulted in increased cell migration. Likewise, inhibition of PKG by expression of a dominant-negative PKG1alpha construct increased cell adhesion and migration, comparable to that induced by hypoxia. Dynamic actin reorganization associated with integrin-mediated cell adhesion is partly regulated by the actin-binding protein cofilin, the (Ser3) phosphorylation of which inhibits its actin-severing activity. We found that increased PKG expression and activity is associated with decreased cofilin (Ser3) phosphorylation, implying a role for PKG in the modulation of cofilin activity and actin dynamics. Together, these findings identify cGMP/PKG1 signaling as central to the functional differences between PVSMC exposed to normoxia versus hypoxia.

Neck injury is critical to elastase-induced aneurysm model

We modified the elastase-induced aneurysm model by use of a simple surgical technique in rabbits. A temporary arcuated aneurysm clip was placed at the origin of the right common carotid artery (RCCA), ascertaining the inner edge of the clip blade on the juncture of the RCCA and right subclavian artery (RSCA), and the elastase-induced aneurysm procedure was undertaken. We found elastase and location of the temporary arcuated aneurysm clip are critical to the success of this aneurysm model.

MicroRNA expression pattern in different stages of nonalcoholic fatty liver disease

BACKGROUND/AIMS

To explore the unique microRNA expression pattern of nonalcoholic fatty liver disease in a rat model, and search for targets of certain dysregulated microRNAs.

METHODS

Microarray and stem-loop RT-PCR were utilized to detect dysregulated microRNAs in a rat model. Significance Analysis of Microarray, Prediction Analysis of Microarray and clustering analysis were implemented to calculate significantly aberrantly expressed microRNAs. TargetScan, miRanda and PicTar were jointly used to predict targets of microRNAs.

RESULTS

Confirmed by Significance Analysis of Microarray and predicted by Prediction Analysis of Microarray, portfolios of 27 and 21 microRNAs were selected as an accurate molecular signature in distinguishing steatosis and steatohepatitis from normal rat liver. Besides, a panel of microRNA-target pairs that may be involved in lipid and glucose metabolism and inflammation process was delineated.

CONCLUSION

This is by far the first report on the dysregulated microRNAs expression pattern in nonalcoholic fatty liver disease. The successful differentiation of steatosis and steatohepatitis from normal liver hints to the potential of using lists of dysregulated microRNAs for diagnosis, though many problems need to be solved. Besides, these data will guide further studies of the contribution of microRNAs to the pathogenesis of nonalcoholic fatty liver disease while disease-specific microRNAs might become potential targets for therapeutic intervention.

MicroRNA expression pattern in different stages of nonalcoholic fatty liver disease

BACKGROUND/AIMS

To explore the unique microRNA expression pattern of nonalcoholic fatty liver disease in a rat model, and search for targets of certain dysregulated microRNAs.

METHODS

Microarray and stem-loop RT-PCR were utilized to detect dysregulated microRNAs in a rat model. Significance Analysis of Microarray, Prediction Analysis of Microarray and clustering analysis were implemented to calculate significantly aberrantly expressed microRNAs. TargetScan, miRanda and PicTar were jointly used to predict targets of microRNAs.

RESULTS

Confirmed by Significance Analysis of Microarray and predicted by Prediction Analysis of Microarray, portfolios of 27 and 21 microRNAs were selected as an accurate molecular signature in distinguishing steatosis and steatohepatitis from normal rat liver. Besides, a panel of microRNA-target pairs that may be involved in lipid and glucose metabolism and inflammation process was delineated.

CONCLUSION

This is by far the first report on the dysregulated microRNAs expression pattern in nonalcoholic fatty liver disease. The successful differentiation of steatosis and steatohepatitis from normal liver hints to the potential of using lists of dysregulated microRNAs for diagnosis, though many problems need to be solved. Besides, these data will guide further studies of the contribution of microRNAs to the pathogenesis of nonalcoholic fatty liver disease while disease-specific microRNAs might become potential targets for therapeutic intervention.

Rap1b is critical for glycoprotein VI-mediated but not ADP receptor-mediated alpha2beta1 activation

BACKGROUND

The platelet alpha2beta1 integrin functions as both an adhesion and signaling receptor upon exposure to collagen. Recent studies have indicated that alpha2beta1 function can be activated via inside-out signaling, similar to the prototypical platelet integrin alphaIIbbeta3. However, signaling molecules that regulate alpha2beta1 activation in platelets are not well defined. A strong candidate molecule is the small GTPase Rap1b, the dominant platelet isoform of Rap1, which regulates alphaIIbbeta3 activation.

OBJECTIVES

We hypothesized that Rap1b positively regulates alpha2beta1 during agonist-induced platelet activation.

METHODS

To test whether Rap1b activates alpha2beta1 downstream of glycoprotein (GP)VI or other platelet receptors, we stimulated platelets purified from Rap1b-/- or wild-type mice with diverse agonists and measured alpha2beta1 activation using fluorescein isothiocyanate-labeled monomeric collagen. We also examined the role of Rap1b in outside-in signaling pathways by analyzing adhesion and spreading of Rap1b-/- or wild-type platelets on monomeric, immobilized collagen. Finally, we monitored the activation status of related Rap GTPases to detect changes in signaling pathways potentially associated with Rap1b-mediated events.

RESULTS

Rap1b-/- platelets displayed comparable ADP-induced or thrombin-induced alpha2beta1 activation as wild-type platelets, but reduced convulxin-dependent alpha2beta1 activation. Rap1b-/- platelets exhibited increased spreading on immobilized collagen but similar adhesion to immobilized collagen compared to wild-type platelets. Rap1b-/- platelets also showed Rap1a and Rap2 activation upon agonist stimulation, possibly revealing functional compensation among Rap family members.

CONCLUSIONS

Rap1b is required for maximal GPVI-induced but not ADP-induced activation of alpha2beta1 in murine platelets.

Molecular characterisation of outbreak-related strains of vancomycin-resistant Enterococcus faecium from an intensive care unit in Beijing, China

We investigated an outbreak of vancomycin-resistant Enterococcus faecium affecting 14 patients in a 20-bed intensive care unit (ICU) between September 2006 and August 2007 (incidence: 3.56 cases per 1000 ICU patient days). Eighteen isolates of vanA type E. faecium were analysed by pulsed field gel electrophoresis, which showed 14 types overall. Multilocus sequence typing (MLST) identified eight different sequence types (STs) (ST78, ST117, ST203, ST316, ST362, ST363, ST364 and ST365), including four new types (ST362, ST363, ST364 and ST365) and 17 strains belonged to clonal complexes CC17. Sixteen of these carried the esp gene. Eighteen Tn1546-like elements encoding vanA-type VRE were classified into three types (types I to III) and all of them contained both IS1216V and IS1542 insertions. Vancomycin resistance of 14 vanA type E. faecium isolates was transferred at a frequency of 1.3 x 10(-6) to 6.4 x 10(-5) between E. faecium strains during filter mating. Our findings indicate that conjugative dissemination of Tn1546-like elements among CC17 E. faecium occurred during the outbreak in this ICU.