A novel missense variant in ATP11C is associated with reduced red blood cell phosphatidylserine flippase activity and mild hereditary hemolytic anemia

Adenosine Triphosphatase (ATPase) Phospholipid Transporting 11C gene (ATP11C) encodes the major phosphatidylserine (PS) flippase in human red blood cells (RBCs). Flippases actively transport phospholipids (e.g., PS) from the outer to the inner leaflet to establish and maintain phospholipid asymmetry of the lipid bilayer of cell membranes. This asymmetry is crucial for survival since externalized PS triggers phagocytosis by splenic macrophages. Here we report on pathophysiological consequences of decreased flippase activity, prompted by a patient with hemolytic anemia and hemizygosity for a novel c.2365C > T p.(Leu789Phe) missense variant in ATP11C. ATP11C protein expression was strongly reduced by 58% in patient-derived RBC ghosts. Furthermore, functional characterization showed only 26% PS flippase activity. These results were confirmed by recombinant mutant ATP11C protein expression in HEK293T cells, which was decreased to 27% compared to wild type, whereas PS-stimulated ATPase activity was decreased by 57%. Patient RBCs showed a mild increase in PS surface exposure when compared to control RBCs, which further increased in the most dense RBCs after RBC storage stress. The increase in PS was not due to higher global membrane content of PS or other phospholipids. In contrast, membrane lipid lateral distribution showed increased abundance of cholesterol-enriched domains in RBC low curvature areas. Finally, more dense RBCs and subtle changes in RBC morphology under flow hint toward alterations in flow behavior of ATP11C-deficient RBCs. Altogether, ATP11C deficiency is the likely cause of hemolytic anemia in our patient, thereby underlining the physiological role and relevance of this flippase in human RBCs.

End-of-life practices in 11 German intensive care units : Results from the ETHICUS-2 study

BACKGROUND

End-of-life care is common in German intensive care units (ICUs) but little is known about daily practice.

OBJECTIVES

To study the practice of end-of-life care.

METHODS

Prospectively planned, secondary analysis comprising the German subset of the worldwide Ethicus‑2 Study (2015-2016) including consecutive ICU patients with limitation of life-sustaining therapy or who died.

RESULTS

Among 1092 (13.7%) of 7966 patients from 11 multidisciplinary ICUs, 967 (88.6%) had treatment limitations, 92 (8.4%) died with failed CPR, and 33 (3%) with brain death. Among patients with treatment limitations, 22.3% (216/967) patients were discharged alive from the ICU. More patients had treatments withdrawn than withheld (556 [57.5%] vs. 411 [42.5%], p < 0.001). Patients with treatment limitations were older (median 73 years [interquartile range (IQR) 61-80] vs. 68 years [IQR 54-77]) and more had mental decision-making capacity (12.9 vs. 0.8%), advance directives (28.6 vs. 11.2%), and information about treatment wishes (82.7 vs 33.3%, all p < 0.001). Physicians reported discussing treatment limitations with patients with mental decision-making capacity and families (91.3 and 82.6%, respectively). Patient wishes were unknown in 41.3% of patients. The major reason for decision-making was unresponsiveness to maximal therapy (34.6%).

CONCLUSIONS

Treatment limitations are common, based on information about patients' wishes and discussion between stakeholders, patients and families. However, our findings suggest that treatment preferences of nearly half the patients remain unknown which affects guidance for treatment decisions.

Donor Age and Red Cell Age Contribute to the Variance in Lorrca Indices in Healthy Donors for Next Generation Ektacytometry: A Pilot Study

The ability of red blood cells (RBCs) to transport gases, their lifespan as well as their rheological properties invariably depend on the deformability, hydration, and membrane stability of these cells, which can be measured by Laser optical rotational red cell analyser (Lorrca® Maxsis, RR Mechatronics). The osmoscan mode of Lorrca is currently used in diagnosis of rare anemias in clinical laboratories. However, a broad range of normal values for healthy subjects reduces the sensitivity of this method for diagnosis of mild disease phenotype. In this pilot study, we explored the impact of age and gender of 45 healthy donors, as well as RBC age on the Lorrca indices. Whereas gender did not affect the Lorrca indices in our study, the age donors had a profound effect on the O_hyper parameter. To study the impact of RBC age on the osmoscan parameters, we have isolated low (L)-, medium (M)-, or high (H)- density fractions enriched with young, mature, and senescent RBCs, respectively, and evaluated the influence of RBC age-related properties, such as density, morphology, and redox state, on the osmoscan indices. As before, O_hyper was the most sensitive parameter, dropping markedly with an increase in RBC density and age. Senescence was associated with a decrease in deformability (EI_max) and tolerability to low and high osmolatites (Area). L-fraction was enriched with reticulocytes and cells with high projected area and EMA staining, but also contained a small number of cells small in projected area and most likely, terminally senescent. L-fraction was on average slightly less deformable than mature cells. The cells from the L-fraction produced more oxidants and NO than all other fractions. However, RBCs from the L-fraction contained maximal levels of reduced thiols compared to other fractions. Our study suggests that reference values for O_hyper should be age-stratified, and, most probably, corrected for the average RBC age. Further multi-center study is required to validate these suggestions before implementing them into clinical practice.

Targeting mitochondrial calcium pathways as a potential treatment against Parkinson's disease

Parkinson's disease (PD) is a major health problem worldwide affecting millions of people and is a result of neurodegeneration in a small part of the brain known as substantia nigra pars compacta. Aberration in mitochondrial Ca²⁺ homeostasis plays, among several other factors, an important role for the neuronal loss in PD. Mitochondria are vital for cellular physiology, e.g. for ATP generation, and mitochondrial Ca²⁺ is a key player in cell functioning and survival. Mitochondrial Ca²⁺ homeostasis is maintained by a fine balance between the activities of proteins mediating the influx and efflux of Ca²⁺ across mitochondrial membranes. Malfunctioning of these proteins leading to Ca²⁺ overload promotes ROS generation, which induces cell death by triggering the opening of mitochondrial permeability transition pore. Till now PD remains incurable and the "gold standard" drug which can only delays the disease progression is l-Dopa from the 1960s and therefore, the situation warrants the search for novel targets for the treatment of the PD patients. In this review, we summarize the current views that suggest mitochondrial Ca²⁺ regulatory pathways are good candidates for the treatment of PD.

Unveiling spin-glass transition and antiferromagnetic order by μSR studies in spin-chain Sm2BaNiO5

We report the zero-field and longitudinal field muon spin relaxation studies in a spin-chain compound Sm₂BaNiO₅. Two magnetic transitions, that have not been previously detected by the heat capacity and magnetization measurements, are confirmed at 46 and 9 K. The antiferromagnetic order is suggested at 46 K. Analysis of the muon spin polarization unveils the spin-glass transition at 9 K. Time-field scaling relation of the muon spin polarization verifies the spin-spin autocorrelation function following the cut-off power law, which is approximated by the Ogielski form, as employed numerically for characterizing the spin-glasses.

[Non-beneficial therapy and emotional exhaustion in end-of-life care : Results of a survey among intensive care unit personnel]

BACKGROUND

End-of-life care (EOLC) in the intensive care unit (ICU) is becoming increasingly more common but ethical standards are compromised by growing economic pressure. It was previously found that perception of non-beneficial treatment (NBT) was independently associated with the core burnout dimension of emotional exhaustion. It is unknown whether factors of the work environment also play a role in the context of EOLC.

OBJECTIVE

Is the working environment associated with perception of NBT or clinician burnout?

MATERIAL AND METHODS

Physicians and nursing personnel from 11 German ICUs who took part in an international, longitudinal prospective observational study on EOLC in 2015-2016 were surveyed using validated instruments. Risk factors were obtained by multivariate multilevel analysis.

RESULTS

The participation rate was 49.8% of personnel working in the ICU at the time of the survey. Overall, 325 nursing personnel, 91 residents and 26 consulting physicians participated. Nurses perceived NBT more frequently than physicians. Predictors for the perception of NBT were profession, collaboration in the EOLC context, excessively high workload (each p ≤ 0.001) and the numbers of weekend working days per month (p = 0.012). Protective factors against burnout included intensive care specialization (p = 0.001) and emotional support within the team (p ≤ 0.001), while emotional exhaustion through contact with relatives at the end of life and a high workload were both increased (each p ≤ 0.001).

DISCUSSION

Using the example of EOLC, deficits in the work environment and stress factors were uncovered. Factors of the work environment are associated with perceived NBT. To reduce NBT and burnout, the quality of the work environment should be improved and intensive care specialization and emotional support within the team enhanced. Interprofessional decision-making among the ICU team and interprofessional collaboration should be improved by regular joint rounds and interprofessional case discussions. Mitigating stressful factors such as communication with relatives and high workload require allocation of respective resources.

Assessing the role of participants in evolution of topic lifecycles on social networks

Background

Topic lifecycle analysis on social networks aims to analyze and track how topics are born from user-generated content, and how they evolve. Twitter researchers have no agreed-upon definition of topics; topics on Twitter are typically derived in the form of (a) frequently used hashtags, or (b) keywords showing sudden trends of large occurrence in a short span of time (“bursty keywords”), or (c) concepts latent within the tweets that are grouped using variations of semantic clustering techniques.

Methods

In the current paper, we jointly model the hashtags present and the semantic concepts embedded in the content, which in turn helps us identify hashtag groups that define a “topic”—a concept space—that are used by a large number of tweets.

Results

We observe that different hashtags belonging to a given cluster are more prominent compared to the others, at different times. We further observe that the participation and influence levels of the different users play important roles in determining which hashtag would be more prominent than the others at given times. We thus observe topics to often morph from one to the other (via morphing of dominant hashtags representing the same semantic concept space), rather than becoming extinct outright, which is a novel insight about topic lifecycles. We further present novel observations about the role of users in determining the lifecycle of discussion topics on Twitter.

Conclusions

We infer that topic lifecycles are governed by user interests, and not by user influence, which is a key observation made by our work.

FXYD5 (dysadherin) may mediate metastatic progression through regulation of the β-Na+-K+-ATPase subunit in the 4T1 mouse breast cancer model

FXYD5 is a Na+-K+-ATPase regulator, expressed in a variety of normal epithelia. In parallel, it has been found to be associated with several types of cancer and effect lethal outcome by promoting metastasis. However, the molecular mechanism underlying FXYD5 mediated invasion has not yet been identified. In this study, using in vivo 4T1 murine breast cancer model, we found that FXYD5-specific shRNA significantly inhibited lung cancer metastasis, without having a substantial effect on primary tumor growth. Our study reveals that FXYD5 participates in multiple stages of metastatic development and exhibits more than one mode of E-cadherin regulation. We provide the first evidence that FXYD5-related morphological changes are mediated through its interaction with Na+-K+-ATPase. Experiments in cultured 4T1 cells have indicated that FXYD5 expression may downregulate the β1 isoform of the pump. This behavior could have implications on both transcellular interactions and intracellular events. Further studies suggest that differential localization of the adaptor protein Annexin A2 in FXYD5-expressing cells may correlate with matrix metalloproteinase 9 secretion and adhesion changes in 4T1 wild-type cells.

Identification of residues that control Li+ versus Na+ dependent Ca2+ exchange at the transport site of the mitochondrial NCLX

BACKGROUND

The Na⁺/Ca²⁺/Li⁺ exchanger (NCLX) is a member of the Na⁺/Ca²⁺ exchanger family. NCLX is unique in its capacity to transport both Na⁺ and Li⁺, unlike other members, which are Na⁺ selective. The major aim of this study was twofold, i.e., to identify NCLX residues that confer Li⁺ or Na⁺ selective Ca²⁺ transport and map their putative location on NCLX cation transport site.

METHOD

We combined molecular modeling to map transport site of NCLX with euryarchaeal H⁺/Ca²⁺ exchanger, CAX_Af, and fluorescence analysis to monitor Li⁺ versus Na⁺ dependent mitochondrial Ca²⁺ efflux of transport site mutants of NCLX in permeabilized cells.

RESULT

Mutation of Asn149, Pro152, Asp153, Gly176, Asn467, Ser468, Gly494 and Asn498 partially or strongly abolished mitochondrial Ca²⁺ exchange activity in intact cells. In permeabilized cells, N149A, P152A, D153A, N467Q, S468T and G494S demonstrated normal Li⁺/Ca²⁺ exchange activity but a reduced Na⁺/Ca²⁺ exchange activity. On the other hand, D471A showed dramatically reduced Li⁺/Ca²⁺ exchange, but Na⁺/Ca²⁺ exchange activity was unaffected. Finally, simultaneous mutation of four putative Ca²⁺ binding residues was required to completely abolish both Na⁺/Ca²⁺ and Li⁺/Ca²⁺ exchange activities.

CONCLUSIONS

We identified distinct Na⁺ and Li⁺ selective residues in the NCLX transport site. We propose that functional segregation in Li⁺ and Na⁺ sites reflects the functional properties of NCLX required for Ca²⁺ exchange under the unique membrane potential and ion gradient across the inner mitochondrial membrane.

GENERAL SIGNIFICANCE

The results of this study provide functional insights into the unique Li⁺ and Na⁺ selectivity of the mitochondrial exchanger. This article is part of a Special Issue entitled: ECS Meeting edited by Claus Heizmann, Joachim Krebs and Jacques Haiech.

Magnetoelectric Coupling, Ferroelectricity, and Magnetic Memory Effect in Double Perovskite La3Ni2NbO9

We observe ferroelectricity in an almost unexplored double perovskite La3Ni2NbO9. Ferroelectricity appears below ∼60 K, which is found to be correlated with the significant magnetostriction. A reasonably large value of spontaneous electric polarization is recorded to be ∼260 μC/m(2) at 10 K for E = 5 kV/cm, which decreases signifi- cantly upon application of a magnetic field (H), suggesting considerable magnetoelectric coupling. The dielectric permittivity is also influenced by H below the ferroelectric transition. The magnetodielectric response scales linearly to the squared magnetization, as described by the Ginzburg-Landau theory. Meticulous studies of static and dynamic features of dc magnetization and frequency dependent ac susceptibility results suggest spin-glass state below 29 K. Intrinsic magnetic memory effect is observed from zero-field cooled magnetization and isothermal remanent magnetization studies, also pointing spin-glass state below 29 K. Appearance of ferroelectricity together with a significant magnetoelectric coupling in absence of conventional long-range magnetic order is promising for searching new magnetoelectric materials.

Magnetoelectric coupling and exchange bias effects in multiferroic NdCrO3

We report ferroelectricity around  ∼88 K that appears well below T N (∼25 K), unlike other members of RCrO3 series. A synchrotron diffraction study suggests that the occurrence of ferroelectricity in NdCrO3 is coupled to the structural transformation from centrosymmetric Pnma to a non-centrosymmetric Pna21 space group. A strong magnetoelectric coupling is observed in the electric polarization [P(T)]. This coupling is significantly influenced by the magnetic field cooling effect, suggesting an exchange bias effect in P(T). This exchange bias effect is also revealed by the systematic shift of the magnetic hysteresis loops below T(N). The rare occurrence of an exchange bias effect in both the magnetic and electric polarizations associated with a strong magnetoelectric coupling is of fundamental interest, as well as being attractive for technological applications close to liquid nitrogen temperature.

Angiotensin II inhibits Na+/K+ATPase activity in pulmonary artery smooth muscle cells via glutathionylation and with the involvement of a 15.6 kDa inhibitor protein

The role of angiotensin II in regulating Na+/K(+)-ATPase activity has been investigated in bovine pulmonary artery smooth muscle cells (BPASMCs). Our study reveals that angiotensin II inhibits the Na+/K+ATPase activity via glutathionylation of the pump with the involvement of an increase in NADPH oxidase-derived O2*-. Additionally, angiotensin II treatment to the cells increases the inhibitory potency of the 15.6 kDa inhibitor towards the Na+/K+ATPase activity.

Magnetic memory in nanocrystalline α-Fe2O3 embedded in reduced graphene oxide

Single phase iron oxide (α-Fe₂O₃) of nearly regular ellipsoidal shape, embedded in reduced graphene oxide (RGO) has been prepared by the chemical route. Memory effect is observed in magnetization study.

Identification, purification and partial characterization of low molecular weight protein inhibitor of Na⁺/K⁺-ATPase from pulmonary artery smooth muscle cells

We have identified a novel endogenous low mol wt. (15.6 kDa) protein inhibitor of Na(+)/K(+)-ATPase in cytosolic fraction of bovine pulmonary artery smooth muscle cells. The inhibitor showed different affinities toward the α₂β₁ and α₁β₁ isozymes of Na(+)/K(+)-ATPase, where α₂ is more sensitive than α₁. The inhibitor interacted reversibly to the E1 site of the enzyme and blocked the phosphorylated intermediate formation. Circular dichroism study suggests that the inhibitor causes an alteration in the confirmation of the enzyme.

Role of PKCα-p(38)MAPK-G(i)α axis in NADPH oxidase derived O(2)(·-)-mediated activation of cPLA(2) under U46619 stimulation in pulmonary artery smooth muscle cells

We have recently reported that treatment of bovine pulmonary artery smooth muscle cells with the thromboxane A(2) mimetic, U46619 stimulated NADPH oxidase derived O(2)(·-) level, which subsequently caused marked increase in [Ca(2+)](i)[17]. Herein, we demonstrated that O(2)(·-)-mediated increase in [Ca(2+)](i) stimulates an aprotinin sensitive proteinase activity, which proteolytically activates PKC-α under U46619 treatment to the cells. The activated PKC-α then phosphorylates p(38)MAPK and that subsequently caused G(i)α phosphorylation leading to stimulation of cPLA(2) activity in the cell membrane.

Kates forefoot arthroplasty in rheumatoid arthritis. A 5-year followup study

The longterm results of Kates forefoot arthroplasty in 74 feet of 41 patients with rheumatoid arthritis (RA) after a mean followup of 5.2 years was considered to be good by 38 patients and poor by 3 patients. The average walking distance had doubled. The mean hallux valgus angle was reduced from 46 to 27 degrees. Surgical results proved to depend on the quality of the arc of the remaining stumps, and not on the severity or activity of RA. Reoperations were necessary in 16 feet of 10 patients because of too prominent distal metatarsal stumps. Despite the absence of pain, 28 patients were not satisfied with the function of the hallux. This might be improved by performing arthrodesis of the first metatarsophalangeal joint.

Antimicrobial, insect sterilizing and ovicidal activity of some oxo-vanadium(IV) and oxo-vanadium(V) complexes

Twenty-three newly synthesized mixed-ligand complexes of oxo-vanadium(IV) and oxo-vanadium(V) were studied for antimicrobial activity. Eight of these complexes were found to have microbicidal properties. The complexes [NH4][VO(gl)2]H2O (gl-H2 = glycolic acid) and [VO(ACOAP)(acac-H)]H20 (ACOAP-H2=Schiff base of acetylacetone and orthoaminophenol, acac-H=acetyl-acetone) show broad bactericidal spectra, while the complexes [VO(ACSAM)2]OH (ACSAM-H = Schiff base of acetylacetone and sulphanilamide) and [VO(CSSAM-H)2]H2O (CSSAM-H =Schiff base of 3-carboxy salicylaldehyde and sulphanilamide) possess pronounced antidermatophytic properties. The latter is inhibitory to plant pathogenic fungi as well. Plant tumour producing Agrobacterium tumefaciens is effectively inhibited in vitro by the complex [VO(ACTSC-Na)(acac)]H2O (ACTSC-H2 = condensation product of acetylacetone and thiosemicarbazide). Minimum inhibitory concentrations of all the active complexes are within the values of 0.125-2.00 mg/ml. Out of the 7 active complexes tested for 50% inhibition of conidial germination of Helminthosporium oryzae, a rice plant pathogen, only 1 complex, viz. [VO(acac) (ACACAACD)] (ACACAACD(H)NH4 equal Schiff base of acetylacetone and ammonium 2-amino-1-cyclopentene-1-dithiocarboxylate) shows a positive result. The effective concentration is 0.55 mg/ml. Three vanadium complexes were tested for insect sterilant and ovicidal properties on the red cotton bug, Dysdercus koenigi. The complex [VO(HASA-Na) (acac)]H2O (HASA-H2 = Schiff base of orthohydroxyacetophenone and anthr anilic acid) was found to be a suitable male sterilant.

Antimicrobial, insect sterilizing and ovicidal activity of some cobalt(II) and cobalt(III) complexes

Twenty-one mixed-ligand complexes of cobalt(II) and cobalt(III) have been screened for their antimicrobial, insect sterilizing and ovicidal activities. Three of these cobalt(III) complexes exhibit broad antimicrobial spectra, including against human bacterial pathogens, dermatophytes and plant pathogenic fungi, while one exhibits feeble activity against a human pathogenic bacterium. These results have been compared with the activity of the corresponding cobalt(II) complexes, which have been found to be inactive, while the free ligands show reduced activity compared with the cobalt(III) complexes. Change in biological activity induced by a particular complex appears to be dependent on the composition of the first co-ordination sphere. Two of these complexes showed 50% inhibition of the conidial germination of Helminthosporium oryzae and Alternaria triticina. These results indicate their potential for use against human and plant pathogenic microbes. Minimum inhibitory concentrations of the cobalt(III) complexes were determined. Three of these cobalt(III) complexes have been tested for insect sterilizing and ovicidal activities on Dysdercus koenigi F. Positive sterilizing and ovicidal actions of [Co(BSOP)(NH3)2]NO3 (where BSOP-H2 is the Schiff base derived from salicylaldehyde and orthophenylene-diamine) were obtained. Possible mechanism(s) of all these activities are discussed qualitatively.