High syphilis seropositivity in European brown hares (Lepus europaeus), Lower Saxony,Germany

The lagomorph‐infecting Treponema paraluisleporidarum is a close relative of the human syphilis‐bacterium Treponema pallidum. There is a paucity of information on the epidemiology of hare syphilis and its relationship to the rabbit‐ and human‐infecting treponemes that cause syphilis. In our study, we tested 734 serum samples from European brown hares (Lepus europaeus) collected between 2007 and 2019 in the federal state of Lower Saxony, Germany, for the presence of antibodies against T. paraluisleporidarum. Since T. paraluisleporidarum cross‐reacts with T. pallidum antigen, we used a commercially available T. pallidum‐particle agglutination (TP‐PA) assay to test for the presence of antibodies. A high seropositivity (n = 405/734) was detected. An additional 233 serum samples were retested using a fluorescent treponemal antibody absorption test to confirm the results of the TP‐PA assay. Our results show that infection is widespread in Lower Saxony and suggest a horizontal (sexual) transmission mode since adult hares show significantly higher seropositivity than subadults (odds ratio: 0.03 [95% CI 0.02–0.05], p < .0001). No difference was detected based on gender (odds ratio: 0.79 [95% Cl 0.58–1.07], p = .1283). Further studies are warranted to genetically characterize the T. paraluisleporidarum strains that infect wild hares.     

The impact of SAMHD1 expression and mutation status in mantle cell lymphoma: An analysis of the MCL Younger and Elderly trial

The sterile alpha motif and histidine‐aspartic domain‐containing protein 1 (SAMHD1) has been demonstrated to predict the response to high‐dose cytarabine consolidation treatment in acute myeloid leukemia patients. Here, we evaluated SAMHD1 as potential biomarker for the response to high‐dose cytarabine in mantle cell lymphoma (MCL) patients. We quantified SAMHD1 protein expression and determined the mutation status in patients of the MCL Younger and Elderly trials (n = 189), who had received high‐dose cytarabine‐ or fludarabine‐based polychemotherapy. Additionally, we quantified SAMHD1 expression in B cell lymphoma cell lines and exposed them to cytarabine, fludarabine, and clinically relevant combinations. Across both trials investigated, SAMHD1 mutations had a frequency of 7.1% (n = 13) and did not significantly affect the failure‐free survival (FFS, P = .47). In patients treated with high‐dose cytarabine‐ or fludarabine‐containing regimes, SAMHD1 expression was not significantly associated with FFS or complete remission rate. SAMHD1 expression in B cell lymphoma cell lines, however, inversely correlated with their in vitro response to cytarabine as single agent (R = .65, P = .0065). This correlation could be reversed by combining cytarabine with other chemotherapeutics, such as oxaliplatin and vincristine, similar to the treatment regime of the MCL Younger trial. We conclude that this might explain why we did not observe a significant association between SAMHD1 protein expression and the outcome of MCL patients upon cytarabine‐based treatment.     

Interferon signature in patients with STAT1 gain‐of‐function mutation is epigenetically determined

STAT1 gain‐of‐function (GOF) variants lead to defective Th17 cell development and chronic mucocutaneous candidiasis (CMC), but frequently also to autoimmunity. Stimulation of cells with STAT1 inducing cytokines like interferons (IFN) result in hyperphosphorylation and delayed dephosphorylation of GOF STAT1. However, the mechanism how the delayed dephosphorylation exactly causes the increased expression of STAT1‐dependent genes, and how the intracellular signal transduction from cytokine receptors is affected, remains unknown. In this study we show that the circulating levels of IFN‐α were not persistently elevated in STAT1 GOF patients. Nevertheless, the expression of interferon signature genes was evident even in the patient with low or undetectable serum IFN‐α levels. Chromatin immunoprecipitation (ChIP) experiments revealed that the active chromatin mark trimethylation of lysine 4 of histone 3 (H3K4me3), was significantly enriched in areas associated with interferon‐stimulated genes in STAT1 GOF cells in comparison to cells from healthy donors. This suggests that the chromatin binding of GOF STAT1 variant promotes epigenetic changes compatible with higher gene expression and elevated reactivity to type I interferons, and possibly predisposes for interferon‐related autoimmunity. The results also suggest that epigenetic rewiring may be responsible for treatment failure of Janus kinase 1/2 (JAK1/2) inhibitors in certain patients.     

Recombinant human platelet-activating factor acetylhydrolase for treatment of severe sepsis: results of a phase III, multicenter, randomized, double-blind, placebo-controlled, clinical trial

OBJECTIVE: Platelet-activating factor (PAF) and structurally-related oxidized phospholipids are proinflammatory mediators in systemic inflammatory states such as severe sepsis. The enzyme platelet-activating factor acetylhydrolase (PAF-AH) rapidly degrades PAF and oxidized phospholipids into inactive metabolites. Reduced PAF-AH activity has been observed in patients with severe sepsis and may contribute to their systemic inflammatory response and organ dysfunction. A previous clinical trial with recombinant human PAF-AH (rPAF-AH, Pafase) suggested that this treatment may decrease 28-day all-cause mortality in patients with severe sepsis. The current study was undertaken to confirm this result. DESIGN: A prospective, randomized, double-blind, placebo-controlled, multicenter, international trial. SETTING: One hundred forty-six intensive care units from nine countries. PATIENTS: Approximately 2,522 patients were planned to be enrolled < or =12 hrs after the onset of severe sepsis. Eligible patients were randomized to receive either rPAF-AH 1.0 mg/kg or placebo administered intravenously once daily for five consecutive days. MEASUREMENTS AND MAIN RESULTS: The study was terminated based on the recommendation of an independent data and safety monitoring committee after the second of three planned interim analyses, and the enrollment of 1,425 patients. rPAF-AH treatment was well tolerated among the 1,261 patients included in the interim analysis (643 rPAF-AH and 618 placebo), but did not decrease 28-day all-cause mortality compared with placebo (25% for rPAF-AH vs. 24% for placebo; relative risk, 1.03; 95% confidence interval, 0.85-1.25; p =.80). There were no statistically significant differences between treatment groups in any of the secondary efficacy end points. The overall incidence of adverse events was similar among rPAF-AH and placebo-treated patients, and no rPAF-AH-treated patients developed antibodies to PAF-AH. CONCLUSIONS: rPAF-AH was well tolerated and not antigenic, but did not decrease 28-day all-cause mortality in patients with severe sepsis.     

Proportionate Reversible Decreases in Systolic Function and Myocardial Oxygen Consumption After Modest Reductions in Coronary Flow: Hibernation Versus Stunning

Objectives. This study sought to determine whether modest short-term reductions in coronary flow can produce subsequent proportionate reductions in myocardial function and O₂ consumption compatible with myocardial hibernation.

Background. Acute studies indicate that myocardial energy utilization can be downregulated during moderate flow reduction. Whether this apparently beneficial adjustment persists into the reperfusion period is unsettled because most postischemic contractile dysfunction has been presumed to represent stunned or irreversibly injured myocardium.

Methods. Responses of regional myocardial function and O₂ consumption were assessed in chronically instrumented dogs after 50% reductions in flow for 2 h (n = 8) or repeated 2-min total coronary occlusions (n = 6).

Results. When unrestricted perfusion was restored after sustained partial occlusions, regional function and O₂ consumption stabilized at proportionate, systematically decreased levels ([mean ± SEM] 80 ± 3.1% and 81 ± 5.1% of control values, both p < 0.05) and then returned to control values within 24 h. Similar proportionate reductions occurred after as few as five cycles of brief total occlusion (79 ± 5.1% and 83 ± 1.6% of control values, both again p < 0.05); these persisted with additional occlusions and then returned to baseline values within 3 h. The absence of irreversible injury was documented histologically in both series. Sham animals (n = 5) showed no changes in regional function or O₂ consumption throughout similar experimental periods.

Conclusions. Moderate decreases in coronary flow or repeated brief coronary occlusions can be followed by proportionate reversible reductions in regional systolic function and O₂ consumption compatible with the traditional definition of myocardial hibernation. These findings emphasize the complexity of myocardial responses to flow restriction and call attention to limitations in characterizing reversibly hypocontractile myocardium as simply hibernating or stunned.

(J Am Coll Cardiol 1997;29:1623–31)     

DNA self-organization controls valence in programmable colloid design

Just like atoms combine into molecules, colloids can self-organize into predetermined structures according to a set of design principles. Controlling valence—the number of interparticle bonds—is a prerequisite for the assembly of complex architectures. The assembly can be directed via solid “patchy” particles with prescribed geometries to make, for example, a colloidal diamond. We demonstrate here that the nanoscale ordering of individual molecular linkers can combine to program the structure of microscale assemblies. Specifically, we experimentally show that covering initially isotropic microdroplets with N mobile DNA linkers results in spontaneous and reversible self-organization of the DNA into Z(N) binding patches, selecting a predictable valence. We understand this valence thermodynamically, deriving a free energy functional for droplet–droplet adhesion that accurately predicts the equilibrium size of and molecular organization within patches, as well as the observed valence transitions with N. Thus, microscopic self-organization can be programmed by choosing the molecular properties and concentration of binders. These results are widely applicable to the assembly of any particle with mobile linkers, such as functionalized liposomes or protein interactions in cell–cell adhesion.

Building blocks encoded with assembly rules harness thermal energy to put themselves together in a process called self-assembly (1, 2). These elements can be proteins (3, 4), DNA (5–8), or colloids (8–12). Akin to atoms and molecules, colloidal particles with well-defined shapes and interactions self-organize into bulk crystalline phases that minimize the free energy (13–19). More-complex objects with nonrepeating structures, such as protein folds or aperiodic crystals, require a prescribed limit to particle valence (20, 21). A fundamental goal is to fabricate structures with important technological applications (22). For example, colloidal self-assembly into a diamond lattice (10) or a quasicrystal (23, 24) is expected to exhibit photonic band gaps due to the materials’ interaction with light (25, 26). At its most complex, self-assembly of biological cells is a crucial part of the development of a living organism (27).Experimentally, valence control can be achieved by designing anisotropic sticky particles with patches to create colloidal clusters (28–30) or DNA origami that specifies the bond orientation (31, 32). Mixing particles with a given size and number ratio can result in steric valence control (33). Other proposed methods include the self-organization of nematic shells on spheres (34, 35) or the arrested phase separation of lipids on droplet surfaces (36). These processes are complex to experimentally realize, feature slow assembly kinetics due to the necessity of patch-to-patch binding, and require extensive purification (28).Unlike solid particles, droplets (37–40), lipid vesicles (41–46), and biological cells (47–50) allow any sticky binders to freely diffuse at the interface and segregate into adhesions with their neighbors. If the particles are Brownian or mobile, they can rearrange even after binding to reach the most favorable valence and geometry, avoiding kinetic bottlenecks. Angioletti-Uberti et al. (51) theoretically proposed that mobile ligands coupled with an additional repulsive potential—such as a steric brush—could yield colloidal valence selection in the bulk. More generally, the mobility and reversibility of linker binding between particles allows the system to optimize its equilibrium structure according to the laws of statistical mechanics. Not only is this strategy more robust than directed irreversible assembly, but it enables colloidal design based on the properties of molecular binders.Here, we derive and experimentally validate the free energy functional for droplet–droplet adhesion and predict the consequent thermodynamically stable valence for given control parameters. Moreover, we show that droplets recover their equilibrium valence in a matter of minutes after their bonds are broken. Our results are applicable to any functionalized particles with mobile binders, showing that molecular properties and concentration are sufficient to predetermine valence. Emulsions serve as a template for programmable solid materials because the droplets can be readily polymerized at any stage of the self-assembly process (52, 53).     

Novel imaging methods reveal positive impact of topical negative pressure application on tissue perfusion in an in vivo skin model

The influence of topical negative pressure application (TNPA) on tissue perfusion still remains controversial. TNPA was applied for 30 minutes on intact skin of 21 healthy participants. Measurements of tissue oxygen saturation and tissue temperature as signs of tissue perfusion were performed before application of the TNPA, directly after removal of the TNPA and 5, 10, 15, 20, and 30 minutes after removal of the dressing using the near infrared imaging (NIRI) and a thermal imaging camera. Tissue oxygen saturation showed an increase from 67.7% before applying the TNPA to 76.1% directly after removal of TNPA, followed by a decrease of oxygen saturation 30 minutes after removal of TNPA. The measured temperature of the treated skin area increased from 32.1°C to 36.1°C after removal of TNPA with a consecutive decrease of the temperature 30 minutes after removal. TNPA resulted in both a higher tissue oxygen saturation and a higher skin temperature after 30 minutes compared to the beginning. TNPA increases both tissue oxygen saturation and skin temperature as sign of an increase of tissue perfusion. NIRI and thermal imaging proved to be useful for measuring changes in tissue perfusion.