Vicia faba SV channel VfTPC1 is a hyperexcitable variant of plant vacuole Two Pore Channels

To fire action-potential-like electrical signals, the vacuole membrane requires the two-pore channel TPC1, formerly called SV channel. The TPC1/SV channel functions as a depolarization-stimulated, non-selective cation channel that is inhibited by luminal Ca2+. In our search for species-dependent functional TPC1 channel variants with different luminal Ca2+ sensitivity, we found in total three acidic residues present in Ca2+ sensor sites 2 and 3 of the Ca2+-sensitive AtTPC1 channel from Arabidopsis thaliana that were neutral in its Vicia faba ortholog and also in those of many other Fabaceae. When expressed in the Arabidopsis AtTPC1-loss-of-function background, wild-type VfTPC1 was hypersensitive to vacuole depolarization and only weakly sensitive to blocking luminal Ca2+. When AtTPC1 was mutated for these VfTPC1-homologous polymorphic residues, two neutral substitutions in Ca2+ sensor site 3 alone were already sufficient for the Arabidopsis At-VfTPC1 channel mutant to gain VfTPC1-like voltage and luminal Ca2+ sensitivity that together rendered vacuoles hyperexcitable. Thus, natural TPC1 channel variants exist in plant families which may fine-tune vacuole excitability and adapt it to environmental settings of the particular ecological niche.

Modified Rhodopsins From Aureobasidium pullulans Excel With Very High Proton-Transport Rates

Aureobasidium pullulans is a black fungus that can adapt to various stressful conditions like hypersaline, acidic, and alkaline environments. The genome of A. pullulans exhibits three genes coding for putative opsins ApOps1, ApOps2, and ApOps3. We heterologously expressed these genes in mammalian cells and Xenopus oocytes. Localization in the plasma membrane was greatly improved by introducing additional membrane trafficking signals at the N-terminus and the C-terminus. In patch-clamp and two-electrode-voltage clamp experiments, all three proteins showed proton pump activity with maximal activity in green light. Among them, ApOps2 exhibited the most pronounced proton pump activity with current amplitudes occasionally extending 10 pA/pF at 0 mV. Proton pump activity was further supported in the presence of extracellular weak organic acids. Furthermore, we used site-directed mutagenesis to reshape protein functions and thereby implemented light-gated proton channels. We discuss the difference to other well-known proton pumps and the potential of these rhodopsins for optogenetic applications.

Coregulation of gene expression by White collar 1 and phytochrome in Ustilago maydis

Ustilago maydis encodes ten predicted light-sensing proteins. The biological functions of only a few of them are elucidated. Among the characterized ones are two DNA-photolyases and two rhodopsins that act as DNA-repair enzymes or green light-driven proton pumps, respectively. Here we report on the role of two other photoreceptors in U. maydis, namely White collar 1 (Wco1) and Phytochrome 1 (Phy1). We show that they bind flavins or biliverdin as chromophores, respectively. Both photoreceptors undergo a photocycle in vitro. Wco1 is the dominant blue light receptor in the saprophytic phase, controlling all of the 324 differentially expressed genes in blue light. U. maydis also responds to red and far-red light. However, the number of red or far-red light-controlled genes is less compared to blue light-regulated ones. Moreover, most of the red and far-red light-controlled genes not only depend on Phy1 but also on Wco1, indicating partial coregulation of gene expression by both photoreceptors. GFP-fused Wco1 is preferentially located in the nucleus, Phy1 in the cytosol, thus providing no hint that these photoreceptors directly interact or operate within the same complex. This is the first report on a functional characterization and coaction of White collar 1 and phytochrome orthologs in basidiomycetes.

Cardiac remodeling in ambitious endurance-trained amateur athletes older than 50 years

Background

Data on cardiac remodeling in athletes are conflicting and rarely available in veteran athletes.

Purpose

Therefore, in this study we aimed to define echocardiographic features of healthy endurance athletes older than 50 years.

Methods

We included probands aged >50 years, who have performed endurance sports at 70% of their maximum heart rate for at least 1 hour 3 times per week over the previous 5 years.

Results

Between November 2018 and May 2019, 69 probands were recruited. Median age was 57 years (IQR 52–64) and 26% were female. Groups were formed according to the median training time of 6 hours per week: (A) 45 probands with ≥6 hours (IQR 6–10) and (B) 24 probands with <6 hours (IQR 3.5–5). Age, sex and body mass index were similar. Group A demonstrated slightly smaller right atrial and left atrial (LA) diameters when compared to probands in B (53mm (IQR 49–55) vs. 53mm (IQR 51–58), p=0.045, and 52mm (IQR 49–55) vs. 53mm (IQR 52–58), p=0.039, respectively) and showed preserved diastolic function (p=0.026) with lower E/E' ratio (7 (IQR 6–9) vs. 9 (IQR 7–10), p=0.039). Interventricular septal thickness and relative wall thickness ratio were similar.

Global right and left ventricular (LV) strain were similar, but LA reservoir strain was higher in group A than in B (27% (IQR 22–34) vs. 20% (IQR 15–29), p=0.016).

Conclusion

Endurance training in healthy athletes older than 50 years does not result in relevant chamber dilatation or LV hypertrophy and a weekly training duration of ≥6 hours seems beneficial to preserve diastolic function associated with an increased LA reservoir function.

Funding Acknowledgement

Type of funding source: None

Expansion Microscopy for Cell Biology Analysis in Fungi

Super-resolution microscopy has evolved as a powerful method for subdiffraction-resolution fluorescence imaging of cells and cellular organelles, but requires sophisticated and expensive installations. Expansion microscopy (ExM), which is based on the physical expansion of the cellular structure of interest, provides a cheap alternative to bypass the diffraction limit and enable super-resolution imaging on a conventional fluorescence microscope. While ExM has shown impressive results for the magnified visualization of proteins and RNAs in cells and tissues, it has not yet been applied in fungi, mainly due to their complex cell wall. Here we developed a method that enables reliable isotropic expansion of ascomycetes and basidiomycetes upon treatment with cell wall degrading enzymes. Confocal laser scanning microscopy (CLSM) and structured illumination microscopy (SIM) images of 4.5-fold expanded sporidia of Ustilago maydis expressing fluorescent fungal rhodopsins and hyphae of Fusarium oxysporum or Aspergillus fumigatus expressing either histone H1-mCherry together with Lifeact-sGFP or mRFP targeted to mitochondria, revealed details of subcellular structures with an estimated spatial resolution of around 30 nm. ExM is thus well suited for cell biology studies in fungi on conventional fluorescence microscopes.

Opsin 1 and Opsin 2 of the Corn Smut Fungus Ustilago maydis Are Green Light-Driven Proton Pumps

In fungi, green light is absorbed by rhodopsins, opsin proteins carrying a retinal molecule as chromophore. The basidiomycete Ustilago maydis, a fungal pathogen that infects corn plants, encodes three putative photoactive opsins, called ops1 (UMAG_02629), ops2 (UMAG_00371), and ops3 (UMAG_04125). UmOps1 and UmOps2 are expressed during the whole life cycle, in axenic cultures as well as in planta, whereas UmOps3 was recently shown to be absent in axenic cultures but highly expressed during plant infection. Here we show that expression of UmOps1 and UmOps2 is induced by blue light under control of white collar 1 (Wco1). UmOps1 is mainly localized in the plasma membrane, both when expressed in HEK cells and U. maydis sporidia. In contrast, UmOps2 was mostly found intracellularly in the membranes of vacuoles. Patch-clamp studies demonstrated that both rhodopsins are green light-driven outward rectifying proton pumps. UmOps1 revealed an extraordinary pH dependency with increased activity in more acidic environment. Also, UmOps1 showed a pronounced, concentration-dependent enhancement of pump current caused by weak organic acids (WOAs), especially by acetic acid and indole-3-acetic acid (IAA). In contrast, UmOps2 showed the typical behavior of light-driven, outwardly directed proton pumps, whereas UmOps3 did not exhibit any electrogenity. With this work, insights were gained into the localization and molecular function of two U. maydis rhodopsins, paving the way for further studies on the biological role of these rhodopsins in the life cycle of U. maydis.

Monitoring anticoagulation of primary haemostasis

This article provides an overview on current commercially available methods to determine primary haemostasis as a target of drug-mediated anticoagulation. It focuses on whole blood methods only, and references the currently major achievements that have been reported with each method in respect to its clinical use. Advantages and disadvantages of the various methods are presented, based on considerations of platelet physiology, and on feasibility of the procedures.

High proportion of patients with bleeding of unknown cause in persons with a mild-to-moderate bleeding tendency: Results from the Vienna Bleeding Biobank (VIBB)

INTRODUCTION

Data on clinical characteristics and the prevalence of underlying coagulopathies in patients with mild-to-moderate bleeding disorders (MBDs) are scarce.

AIM

We established the Vienna Bleeding Biobank (VIBB) to characterize and thoroughly investigate Austrian patients with MBDs.

RESULTS

Four hundred eighteen patients (female = 345, 82.5%) were included. A platelet function defect (PFD) was diagnosed in 26 (6.2%) and a possible PFD in 30 (7.2%) patients. Eight patients (1.9%) were diagnosed with von Willebrand disease (VWD) (type 1 n = 6; type 2 n = 2), and 29 patients had low VWF (30-50 IU/dL). Deficiencies in factor VIII, IX, XI or XIII were found in 11 (2.6%), 3 (0.7%), 3 (0.7%) and 1 patient(s), 2 patients had dysfibrinogenaemia, and further 2 had possible PFD and FXI deficiency. Probable causal mutations were detected in 8 of 11 patients with FVIII deficiency, 2 of 3 patients with FIX deficiency and 2 of 8 patients with VWD. Three hundred three patients (72.5%) had normal results in the coagulation assays and were categorized as patients with bleeding of unknown cause (BUC). The bleeding score did not differ between patients with and without established diagnosis. A diagnosis of a bleeding disorder was more frequently made in men than in women (49.3% vs 22.9%). Male sex (OR 3.55, 95% CI: 2.02-6.22; P < .001) and blood group 0 (OR 1.86, 95% CI: 1.17-2.94; P = .008) were independently associated with diagnosis of a bleeding disorder.

CONCLUSION

The high rate of patients with BUC despite in-depth haemostatic assessment underlines the incompleteness of available routine laboratory tests. Males with MBDs were more likely to be diagnosed with an established bleeding disorder than females.

Platelet activation in the presence of neutral protamine Hagedorn insulin: a new feature of antibodies against protamine/heparin complexes

Essentials Protamine (PRT) is used to stabilize insulin in neutral protamine Hagedorn (NPH) insulin. The interaction between NPH-insulin, anti-PRT/heparin antibodies and platelets was investigated. Anti-PRT/heparin antibodies activate platelets in presence of NPH-insulin dependent on heparin. Cross-reactivity seems to have no major effect on the clinical outcome of medical patients.

SUMMARY

Background Protamine (PRT) is used to stabilize insulin in neutral protamine Hagedorn (NPH) insulin, a commonly used therapeutic agent for diabetes mellitus. Immunization against PRT/heparin complexes is common in diabetic patients. Objectives To investigate the impact of NPH-insulin on the interaction between anti-PRT/heparin antibodies and platelets. Methods The interaction between NPH-insulin and anti-PRT/heparin antibodies was tested using in-house enzyme immunoassays. The ability of anti-PRT/heparin antibodies to activate platelets in the presence of NPH-insulin (and heparin) was investigated using flow cytometry. Results Twenty-one out of 80 sera containing anti-PRT/heparin IgG showed binding to NPH-insulin. Anti-PRT/heparin IgG from immunized patients bound to platelets in the presence of NPH-insulin, but not in the presence of native insulin. Anti-PRT/heparin antibodies induced P-selectin expression in the presence of NPH-insulin in a heparin-dependent way (median mean fluorescence intensity in the presence of NPH-insulin: 55, 95% confidence interval [CI] 18.7-100.5 vs. NPH-insulin and heparin: 204, 95% CI 106.5-372.8). The clinical relevance of platelet-activating anti-PRT/heparin antibodies was assessed by investigating a multicenter study cohort of 332 acutely ill medical patients who received heparin. None of the 21 patients with anti-PRT/heparin IgG developed thrombocytopenia or thromboembolic complications. Conclusions Anti-PRT/heparin antibodies activate platelets in the presence of NPH-insulin in a heparin-dependent way. However, results from our preliminary study indicate no major impact of these antibodies on the clinical outcome in medical patients receiving heparin, particularly on thromboembolic complications.

Specificities of Platelet Autoantibodies and Platelet Activation in Lupus Anticoagulant Patients: A Relation to their History of Thromboembolic Disease

Lupus anticoagulants (LA) prolong in vitro phospholipid-dependent coagulation tests, but are associated with thromboembolic disease (TE). However, a subgroup of individuals with LA has no TE, and it is therefore desirable to distinguish those at risk for TE from those without. Whether platelets have a primary role in the development of TE is not clear yet. We determined platelet autoantibodies to identify a specific platelet target which is associated with platelet activation in 97 patients with a long history of detectable LA, 65 patients with TE (LA/TE+), and 32 individuals without TE (LA/TE+). Thrombocytopenia was more common in the LA/TE- than in the LA/TE+ group ( P &lt; 0.05). Both groups had platelet antibodies, but the frequency of antibodies was lower in LA/TE+ than LA/TE- patients ( P &lt; 0.01), who had higher antibody titres against glycoprotein IIb/IIIa and glycoprotein Ib/IX ( P &lt; 0.05). Also, their platelets were more activated, as determined by PAC-1 binding ( P &lt; 0.01). These differences were also noted if patients with arterial thrombosis were evaluated separately. These findings in LA/TE- individuals were similar to those in patients with chronic autoimmune thrombocytopenia. However, there was no autoantibody target identifiable to distinguish between LA/TE- from LA-TE+ individuals. We therefore conclude that the presence of platelet antibodies, even if associated with platelet activation, is not sufficient to dispose LA patients to thromboembolic disease.

PO-63 - Exhausted platelets in cancer patients with high risk of venous thromboembolism and poor prognosis

INTRODUCTION

Platelets play a crucial role in cancer development, progression and metastatic spread of malignancy. In vitro data show that cancer cells have the ability to activate platelets, and clinical studies found increased levels of platelet activation markers in cancer patients. Moreover, platelets are thought to be involved in the development of venous thromboembolism (VTE) in cancer patients, a frequent complication of malignant disease associated with high morbidity and mortality.

AIM

In this study, we aimed to examine the activation status of platelets in cancer patients and investigate the association with risk of future venous thromboembolism (VTE) and mortality.

MATERIALS AND METHODS

In a prospective observational cohort study of cancer patients we measured pre-chemotherapy platelet P-selectin and glycoprotein (GP) IIb/IIIa expression and monocyte-platelet aggregates (MPA) in vivo and in response to ex vivo stimulation of the platelet activation receptors protease-activated receptor (PAR) -1, -4, and GPVI by whole blood flow cytometry. Primary and secondary endpoints of the study were occurrence of objectively confirmed VTE and death during 2-year follow-up, respectively.

RESULTS

Out of 62 patients (median age [interquartile range, IQR]: 63 [54-70] years, 48% female) with cancers of the pancreas (n=19), lung (n=18), brain (n=14), colon (n=8) and stomach (n=3), 9 (14.5%) developed VTE and 32 (51.6%) died. P-selectin, activated GPIIb/IIIa expression and MPA formation did not significantly differ between tumor sites (Kruskal Wallis test). Reduced platelet responsiveness to PAR-1 and GPVI stimulation was associated with a higher risk of VTE (hazard ratio [HR] per decile increase in %P-selectin positive platelets: 0.73 [95% confidence interval: 0.56-0.92, p=0.007] and 0.77 [0.59-0.98, p=0.034], respectively; Table 1). Further, lower platelet P-selectin and activated GPIIb/IIIa expression in vivo and in response to PAR-1, -4 and GPVI stimulation, but not MPA formation, were associated with a higher risk of death (Table 1).

CONCLUSIONS

Cancer patients with a poor prognosis had degranulated platelets, presumably as a consequence of previous activation. Our data suggest that platelets' continuous activation and thus exhaustion is involved in cancer-associated VTE and cancer mortality.

Detection of granulocyte-reactive antibodies: a comparison of different methods

BACKGROUND AND OBJECTIVES

Granulocyte-reactive antibodies can cause autoimmune and neonatal immune neutropenias as well as transfusion-related acute lung injury. The classical antibody-detection methods granulocyte aggregation test (GAT), granulocyte immunofluorescence test (GIFT) and monoclonal antibody-specific immobilization of granulocyte antigens (MAIGA) are time-consuming and technically challenging. In recent years, flow cytometric white blood cell immunofluorescence test (Flow-WIFT) and the microbeads assay LabScreen® Multi have emerged and are still subject of evaluation. These serological tests were compared on a screening and specification level.

MATERIALS AND METHODS

For screening, the combination of GAT/GIFT was compared to Flow-WIFT testing 333 samples. Positive samples were further analysed with MAIGA and LabScreen® Multi.

RESULTS

Granulocyte aggregation test/GIFT detected 77 positive samples, Flow-WIFT found 108 granulocyte-reactive samples. Six Samples were only positive in GAT/GIFT, and 37 samples were only positive in Flow-WIFT (κ = 0.682). Antibody specification with MAIGA and the microbeads assay confirmed granulocyte-reactivity in 83 cases with 70 matching results (κ = 0.742). However, out of six detected human neutrophil antigen (HNA) reactivities only two specificities matched in both assays.

CONCLUSION

Flow-WIFT may be a valuable addition to GIFT for granulocyte-reactive antibody screening. MAIGA remains the most reliable laboratory method for antibody specification.

Röntgenstrukturanalyse von zwei Verbindungen des Kupfertyps BaMLn2O5 (M = Zn, Ln = Sm, Tm) und von BaSmAIZn3O7 / X-Ray Analysis of Two Compounds of the Copper Type BaMLn2O5 (M=Zn, Ln=Sm, Tm) and of BaSmAlZn3O7

Kupfertyps BaMLn2O5 (M=Zn, Ln=Sm, Tm) und von BaSmAIZn3O7 X-Ray Analysis of Two Compounds of the Copper Type BaMLn2O5 (M=Zn, Ln=Sm, Tm) and of BaSmAlZn3O7 The barium zinc lanthanoide oxides BaZnSm2O5 (I) and BaZnTm2O5 (II) crystallize in the BaCuLn2O3 copper type with orthorhombic symmetry, space group D16 2h,Pnma, (I)

a = 12.575(2), b = 5.804(1), c = 7.198(1) Å and (II):

a = 12.258(2), b = 5.684(1), c = 7.010(2) Å, Z = 4. Zinc shows square pyramidal oxygen coordina­ tion, but the strong elongation of the CuO5 pyramid in the copper type is missing. BaSmAlZn3O7 crystallizes in the space group C4 6V-P63mc, a = 6.346(1), c = 10.237(3) Å, Z = 2. The metal coordination of oxygen and the shifts of the ratio Al : Zn at the sites (6c) and (2a) depending on the size of the lanthanoid ions are discussed.

Granulocyte-reactive antibodies are associated with red blood cell alloimmunization

Granulocyte-reactive antibodies may cause transfusion-related acute lung injury (TRALI) and immune neutropenias. Risk factors for their acquisition other than previous alloexposition are largely unknown. In addition to the known association between human leucocyte antigen alloantibodies and red blood cell alloimmunization in selected cohorts of transfused patients, this study investigated a possible extension of this association to granulocyte-reactive antibodies in women with a history of pregnancy. The overall prevalence of granulocyte-reactive antibodies in 333 samples from women with a history of pregnancy (143 samples containing red cell alloantibodies) was 23·1%. The prevalence in the red cell-alloimmunized group (32·9%) was significantly higher than in controls (15·8%, P < 0·001). This could suggest that some individuals may be strong immunological responders, forming alloantibodies more readily than others.

Diagnosis of prostate cancer in patients with persistently elevated PSA and tumor-negative biopsy in ambulatory care: performance of MR imaging in a multi-reader environment

PURPOSE

False-negative results are obtained in approx. 20 % of prostate cancer (PCa) patients (pts) at initial systematic transrectal biopsy (Bx), in particular when digital rectal examination (DRE) or transrectal ultrasound (TRUS) is negative. The aim of this study was to assess whether MR endorectal imaging of the prostate in a multi-reader ambulatory care setting may assist in patient selection for re-biopsy.

MATERIALS AND METHODS

115 consecutive pts with persistent PSA elevation, negative Bx, DRE and TRUS were examined using T2w axial and coronal and T1w axial sequences for tumor diagnosis. MR images were prospectively read as tumor-suspicious or tumor-negative by the MR radiologist on duty. Additionally, a retrospective readout of a prostate MR expert and an abdominal imaging fellowship-trained radiologist was performed to evaluate the effect of the reader's experience on tumor detection. Imaging findings were compared to the results of the repeat Bx (61 pts) or the clinical course of at least two years.

RESULTS

For the prospective reading, the sensitivity of MRI was 83 %, the specificity was 69 %, the PPV was 33 % and the NPV was 96 %. ROC analysis revealed a significantly better performance of the prostate MR imaging expert compared to the abdominal imaging radiologist (area under ROC 0.88 vs. 0.66, p < 0.001). Based on the prospective reading, a pre-test probability for PCa of 17.4 % as in our study can be reduced to 5 % when obtaining a tumor-negative result in MRI.

CONCLUSION

MR imaging in a multi-reader ambulatory care setting assists in patient selection for re-biopsy. Reducing the post-test probability for PCa to 5 % allows for further follow-up instead of re-biopsy in MR tumor-negative patients. Specific training and experience improve tumor detection in prostate MR imaging.

The effect of plasma removal from apheresis platelet concentrates on platelet function

The effect of plasma removal on platelet function has scarcely been investigated. Plasma removal from apheresis platelet concentrates was achieved by centrifugation at 5000 g for 6 min or 2000 g for 10 min. After resting for 1 h, platelet concentrates were resuspended in 0·9% NaCl. Platelet function was tested before centrifugation and after resuspension by multiple electrode impedance aggregometry (MEA) and light transmission aggregometry (LTA). Plasma removal resulted in 10-14% lower response to TRAP-6 by MEA using both washing procedures, whereas TRAP-6-inducible aggregation by LTA increased slightly (2-5%). Neither plasma removal method affected collagen-induced aggregation. Thus, platelet function did not deteriorate significantly by either method.