Investigating bacteroidetes gliding motility

Bacteroidetes gliding motility is a type of surface motility in which rod-shaped bacteria move up to 2 µm s in a corkscrewing motion. Flavobacterium johnsoniae is the primary model organism for the study of Bacteroidetes gliding. SprB is the main adhesin in this organism and moves in a helix along the cell surface. This movement is guided by an underlying track that is anchored to the inner leaflet of the outer membrane. The essential gliding lipoprotein GldJ, which is helically arranged when visualised in fixed cells, is suggested to form this track. However, direct in vivo imaging of GldJ is yet to be achieved. Two currently outstanding questions about Bacteroidetes gliding motility are 1) how adhesion of SprB to the substratum is controlled so that binding only occurs when moving from the leading to the lagging cell pole and 2) how/if the cell discriminate between the poles. In this thesis, a fusion of the HaloTag domain to SprB enabled labelling of SprB with stable and bright dyes. The movement of SprB could then be visualised using single-particle tracking to reveal the underlying track topology. These tracking data suggest that the underlying track is not a single closed loop currently proposed, but rather a complex and potentially dynamic structure that can form multiple loops and cover most of the cell surface. SprB is encoded by the sprB operon that further encodes RemFG, Fjoh_0982, and SprCDF. In this thesis I show that all these components, except fjoh_0982, are required for gliding motility but only sprF are required for SprB helical movement. All the sprB operon components required for gliding are also required for SprB-mediated attachment to glass, indicating that they regulate adhesion of SprB. RemG and SprCD move in a helix reminiscent of the SprB movement pattern. The helical movement does not depend on SprF or SprB, but rather on the SprFhomologous N-terminal domain of SprD. Observations of gliding cells with fluorescently labelled SprC revealed accumulation of SprC near the leading cell pole. This polar accumulation correlated with the direction of movement and was not observed in cells that did not move. Furthermore, a mutant lacking the C-terminal 50 residues of SprD was unable to accumulate SprC at the leading pole. SprB did not show a similar asymmetric distribution in gliding cells. Fluorescence microscopy shows that helically moving sprB operon proteins accumulate at midcell in dividing cells in a GldJ dependent manner. Cross-linking mass spectrometry indicates that GldJ interacts with the sprB operon proteins as well as GldKNO, essential outer membrane components of the type 9 secretion system which is a pre-requisite for Bacteroidetes gliding motility

Diagnostics receives first impact factor

It is with great pleasure we can announce that Diagnostics has received its first official impact factor, which has just been published in the 2018 edition of the Journal Citation Reports® [...

PET imaging of urokinase-type plasminogen activator receptor (uPAR) in prostate cancer:current status and future perspectives

Overexpression of urokinase-type plasminogen activator receptors (uPAR) represents an important biomarker for aggressiveness in most common malignant diseases, including prostate cancer (PC). Accordingly, uPAR expression either assessed directly in malignant PC tissue or assessed directly in plasma (intact/cleaved forms)—provides independent additional clinical information to that contributed by PSA, Gleason score, and other relevant pathological and clinical parameters. In this respect, non-invasive molecular imaging by positron emission tomography (PET) offers a very attractive technology platform, which can provide the required quantitative information on the uPAR expression profile, without the need for invasive procedures and the risk of missing the target due to tumor heterogeneity. These observations support non-invasive PET imaging of uPAR in PC as a clinically relevant diagnostic and prognostic imaging method. In this review, we will focus on the recent development of uPAR PET and the relevance within prostate cancer imaging. Novel antibody and small-molecule radiotracers-targeting uPAR, including a series of uPAR-targeting PET ligands, based on the high affinity peptide ligand AE105, have been synthesized and tested in vitro and in vivo in preclinical murine xenograft models and, recently, in a first-ever clinical uPAR PET study in cancer patients, including patients with PC. In this phase I study, a high and specific uptake of the tracer (64)Cu-DOTA-AE105 was found in both primary tumors and lymph node metastases. The results are encouraging and support large-scale clinical trials to determine the utility of uPAR PET in the management of patients with PC with the goal of improving outcome

Non-Invasive Imaging for Subclinical Coronary Atherosclerosis in Patients with Peripheral Artery Disease

Patients with peripheral artery disease are at high risk of coronary artery disease. An increasing number of studies show that a large proportion of patients with peripheral artery disease have significant coronary atherosclerosis, even in the absence of symptoms. Although the reported prevalence of subclinical coronary artery disease varies widely in patients with peripheral artery disease, it could include more than half of patients. No consensus exists to date on either the rationale for screening patients with peripheral artery disease for coronary atherosclerosis or the optimal algorithm and method for screening. An increasing number of imaging modalities are emerging that allow improved in vivo non-invasive characterization of atherosclerotic plaques. These novel imaging methods may lead to early detection of high-risk vulnerable plaques, enabling clinicians to improve risk stratification of patients with peripheral artery disease, and thus paving the way for individualized therapy

Comparison of the Peripheral Reactive Hyperemia Index with Myocardial Perfusion Reserve by ⁸²Rb PET/CT in HIV-Infected Patients

After the introduction of antiretroviral therapy (ART) the life expectancy of patients infected with human immunodeficiency virus (HIV) is now approaching that of the general population and the importance of non-AIDS co-morbidities is increasing. Specifically, the risk of coronary artery disease (CAD) seems to be higher in HIV-infected patients and an accurate risk prediction of CAD is of high importance for optimal long term treatment. In this study, we assessed the correlation of the endoPAT, which is an office-based CVD screening tool with the myocardial perfusion reserve by 82-rubidium PET/CT. We measured the reactive hyperemia index, which is a measure of the endothelial responsiveness, by the use of an endoPAT device (Itamar Medical, Caesarea, Israel) in 48 ART treated HIV-infected patients with high CD 4 cell counts and viral suppression (HIV-RNA < 20 copies/mL), who had previously undergone measurement of the myocardial perfusion reserve by 82-rubidium PET/CT for study purposes. We found an inverse correlation between the reactive hyperemia index and the myocardial perfusion reserve which most likely indicates different vascular physiology. This study did not find evidence to suggest the immediate implementation of the reactive hyperemia index as a screening tool for early coronary artery disease in well-treated HIV-infected patients pending further validation in larger prospective studies

111Indium Labelling of Recombinant Activated Coagulation Factor VII: In Vitro and Preliminary In Vivo Studies in Healthy Rats

The aim of this study is to investigate whether 111Indium-labelled recombinant FVIIa (rFVIIa) could be a potential radiopharmaceutical for localization of bleeding sources. DTPA-conjugated rFVIIa was radiolabelled with 111In chloride. In vitro binding efficiency of 111In-DTPA-rFVIIa to F1A2-Mab-sepharose was 99% in buffer, while it was 88–82% in serum. The binding efficiency of 111In-DTPA-rFVIIa to TF (1–209)-sepharose was 48% in buffer whereas 39%–36% in serum, respectively. In vivo experiment was conducted in healthy rats, and gamma camera images were taken immediately after iv. administration of 1.6–1.8 MBq 111In-DTPA-rFVIIa up to 120–130 min. Five min after administration of 111In-DTPA-rFVIIa, percentage of 111In activity was 6.0% in the cardiac region and 24.5% in the liver region. After 2 hours activity was decreased to 3.3% in heart while it had increased to 42.0% in the liver. The 111In-DTPA-rFVIIa might be a potential radiopharmaceutical for visualisation of tissues with significant TF expression such as acute bleeding lesions in the gastrointestinal tract

Cross-calibration of the Siemens mMR:easily acquired accurate PET phantom measurements, long-term stability and reproducibility

BACKGROUND: We present a quick and easy method to perform quantitatively accurate PET scans of typical water-filled PET plastic shell phantoms on the Siemens Biograph mMR PET/MR system. We perform regular cross-calibrations (Xcal) of our PET systems, including the PET/MR, using a Siemens mCT water phantom. LONG-TERM STABILITY: The mMR calibration stability was evaluated over a 3-year period where 54 cross-calibrations were acquired, showing that the mMR on average underestimated the concentration by 16 %, consistently due to the use of MR-based μ-maps. The mMR produced the narrowest calibration ratio range with the lowest standard deviation, implying it is the most stable of the six systems in the study over a 3-year period. MMR ACCURACY WITH PREDEFINED μ-MAPS: With the latest mMR software version, VB20P, it is possible to utilize predefined phantom μ-maps. We evaluated both the system-integrated, predefined μ-map of the long mMR water phantom and our own user-defined CT-based μ-map of the mCT water phantom, which is used for cross-calibration. For seven scans, which were reconstructed with correctly segmented μ-maps, the mMR produced cross-calibration ratios of 1.00–1.02, well within the acceptance range [0.95–1.05], showing high accuracy. CONCLUSIONS: The mMR is the most stable PET system in this study, and the mean underestimation is no longer an issue with the easily accessible μ-map, which resulted in correct cross-calibration ratios in all seven tests. We will share the user-defined μ-map of the mCT phantom and the protocol with interested mMR users