NiO/MnFe2O4 Nanocomposite Photoluminescence, Structural, Morphological, Magnetic, and Optical Properties: Photocatalytic Removal of Cresol Red under Visible Light Irradiation.

In this study, pure nickel oxide (NiO), manganese ferrite (MnFe2O4 or MFO), and binary nickel oxide/manganese ferrite (NiO/MFO1-4) nanocomposites (NCs) were synthesized using the Sol-Gel method. A comprehensive investigation into their photoluminescence, structural, morphological, magnetic, optical, and photocatalytic properties was conducted. Raman analysis, UV-Vis spectroscopy, Fourier-transform infrared spectroscopy, scanning electron microscopy, and X-ray diffraction techniques were used to characterize the materials. The synthesized samples exhibited superparamagnetic behavior, as revealed by our analysis of their magnetic properties. A lower recombination rate was shown by the photoluminescence analysis, which is helpful for raising photocatalytic activity. The photocatalytic activity was evaluated for the degradation of Cresol Red (CR) dye. 91.6% of CR dye was degraded by NiO/MFO-4 nanocomposite, and the NC dosage as well as solution pH affected the photocatalytic performance significantly. In four sequential photocatalytic cycles, the magnetically separable NCs were stable and recyclable. The enhanced photocatalytic activity and magnetic separability revealed the potential application of NiO/MFO-4 as an efficient photocatalyst for the removal of dyes from industrial wastewater under solar light irradiation.

Antibacterial, Antibiofilm, and Anti-Quorum Sensing Potential of Novel Synthetic Compounds Against Pathogenic Bacteria Isolated From Chronic Sinusitis Patients.

Quorum sensing (QS) is a major controller of virulence and biofilm formation in pathogenic bacteria. The aim of the research was to screen novel synthetic compounds (18) from 2 series (Pyrazole and Diene dione) for quorum sensing and biofilm inhibitory potential against resistant pathogens isolated from patients with chronic sinusitis. Most of the compounds have documented zone of inhibition against Gram positive strains Staphylococcus aureus, Enterococcus faecalis and moderate activity against Gram negative Klebseilla pneumoniae and Proteus mirabilis in comparison with standard antibiotic. Compounds Q1 and Q7 have given the maximum zone of inhibition 18 and 20 mm with MICs 0.312 mg/mL and .156 mg/mL against S aureus and E faecalis, respectively. Some compounds were equally potent at inhibiting the formation of biofilm which later established by phase contrast microscopy. Regarding quorum sensing inhibition, the tested concentration of synthetic compound UA3 0.313 mg/mL inhibited violacein production without decreasing Chromobacterium pseudoviolaceum count which was significantly lower than determined MIC's. It was depicted from the results that selected compounds exhibited low level of cytotoxicity toward human red blood cells. Hence, these findings revealed that most novel compounds were effective antibacterial, whereas compound UA3 has shared significant anti-quorum sensing potential against Chromobacterium pseudoviolaceum.

Pathogenic role of cytokines in COVID-19, its association with contributing co-morbidities and possible therapeutic regimens.

The Covid-19, a threatening pandemic, was originated from China in December 2019 and spread quickly to all over the world. The pathogenesis of coronavirus is linked with the disproportionate response of the immune system. This involves the systemic inflammatory reaction which is characterized by marked pro-inflammatory cytokine release commonly known as cytokine release storm (CRS). The pro inflammatory cytokines are involved in cascade of pulmonary inflammation, hyper coagulation and thrombosis which may be lethal for the individual. That's why, it is very important to have understanding of pro inflammatory cytokines and their pathological role in SARS-CoV-2. The pathogenesis of Covid is not the same in every individual, it can vary due to the presence of pre-existing comorbidities like suffering from already an inflammatory disease such as rheumatoid arthritis (RA), inflammatory bowel disease (IBD), chronic obstructive pulmonary disease (COPD), an immune-compromised patients suffering from Diabetes Mellitus (DM) and Tuberculosis (TB) are more vulnerable morbidity and complications following COVID-19. This review is particularly related to COVID-19 patients having comorbidity of other inflammatory diseases. We have discussed the brief pathogenesis of COVID-19 and cytokines release storm with reference to other co-morbidities including RA, IBD, COPD, DM and TB. The available therapeutic regimens for COVID-19 including cytokine inhibitors, anti-viral, anti-biotic, bronchodilators, JAK- inhibitors, immunomodulators and anti-fibrotic agents have also been discussed briefly. Moreover, newly emerging medicines in the clinical trials have also been discussed which are found to be effective in treating Covid-19.

Stimulation of Erythrocyte Membrane Blebbing by Bifenthrin Induced Oxidative Stress.

Background: Bifenthrin is an insecticide and anti-estrogenic compound primarily used to control residential pests by depolarizing sodium gated voltage channels in the nervous system. Eryptosis, the suicidal death of erythrocytes, featured by PS exposure, membrane blebbing and cell shrinkage. Anemia is an outcome of uncontrolled eryptosis. Research Design: In this study, erythrocytes were treated with different concentrations (.5-1-1.5 µM) of bifenthrin over a period of 48 hours. In order to investigate the oxidative stress induced by bifenthrin, catalase, superoxide dismutase, and glutathione peroxidase activities were investigated. Results: Obtained data indicated the decrease in the enzymes (superoxide dismutase, glutathione peroxidase, and catalase) activities in bifenthrin treated cells at 1 µM concentration. In addition, measurement of cell size and confirmation of the role of calcium in the stimulation of the eryptotic activity of bifenthrin were performed. A significant increase in mean cell volume was found in the presence of bifenthrin and a decrease in mean cell volume in the presence of calcium channel blocker was observed. Similarly, there was also a significant increase in the percentage of hemolysis indicating the necrotic activity of bifenthrin. Conclusions: It is concluded that the indicated doses of bifenthrin triggered oxidative stress which may lead to early cell death by eryptosis and hemolysis.

Induction of Erythrocyte Membrane Blebbing by Methotrexate-Induced Oxidative Stress.

Methotrexate (MTX) is a common chemotherapeutical agent and folate antagonist with reported apoptotic activity in nucleated cells. The presented research work was planned to investigate the eryptotic effects of methotrexate after the exposure of erythrocytes to therapeutical doses (10-15 µM) of methotrexate. Eryptosis and the role of calcium in the stimulation of membrane blebbing were evaluated through the determination of mean cell volume. Oxidative stress induced by methotrexate (10-15 µM) was determined by antioxidative enzyme activities. Cytotoxic activity against human erythrocytes was examined through hemolysis assay. Exposure of erythrocytes to methotrexate results in significant reduction of superoxide dismutase, catalase, and superoxide dismutase activities at 10 and 15 µM in comparison to the untreated cells. Erythrocytes mean cell volume (MCV) was increased after 48 hours exposure of erythrocytes to methotrexate (10 µM). Significantly increased hemolysis percentage was observed at 10 µM after 48 hours incubation of erythrocytes with methotrexate. The results of the study suggested that the therapeutical doses (10-15 µM) of methotrexate may lead to increase in eryptotic and hemolytic activity of erythrocytes through free radical generation and subsequent calcium entry.

The electrochemical, dielectric, and ferroelectric properties of Gd and Fe doped LaNiO3 with an efficient solar-light driven catalytic activity to oxidize malachite green dye.

This work investigates the effects of double ion substitution on the ferroelectric, electrochemical, dielectric and photocatalytic properties of Gd and Fe doped La1-yGdyNi1-xFexO3 nanoparticles (NPs). La1-yGdyNi1-xFexO3 was fabricated by facile micro-emulsion path and its properties were studied by thermogravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman scattering, Fourier Transform of Infrared (FTIR), energy dispersive x-rays (EDX) techniques. It has a distorted rhombohedral shape with crystallite size within the range of 17-23 nm. The doped material has a spherical heterogeneous morphology, and its surface area increased with increased doping. The electrochemical (CV, EIS, and I-V), conductivity and dielectric (dielectric constant and low dielectric & tangent loss) properties of La1-yGdyNi1-xFexO3 were dependent on the contents of the dopants (Gd and Fe). The doped material had improved specific capacitance compared to the undoped LaNiO3 due to the synergistic effect of Gd and Fe on the doped materials. The conductivity of Gd and Fe doped LaNiO3 5.16 × 104 Sm-1 was enhanced compared to the undoped LaNiO3 3.52 × 10-2 Sm1. Furthermore, hysteresis loop was used to investigate the coercivity (Hc), saturation magnetization (Ms) and remanence (Mr) of the material. The Ms and Mr values were enhanced with the content of the dopants. The photocatalytic activity (PCA) of the material in degrading malachite green (MG) dye was studied. La1-yGdyNi1-xFexO3 NPs was able to degrade up to 96.4% of the dye under visible light irradiation in 50 min. La1-yGdyNi1-xFexO3 has remarkable dielectric, electrochemical, ferroelectric and photo-catalytic properties and have potential applications in microwave, electrical, electronic, energy storage devices. It is also an active photo-catalyst material for the removal/oxidation of toxic pollutants from the environment.

Induction of Erythrocyte Shrinkage by Omeprazole.

Omeprazole, a proton pump inhibitor blocks the H+/K+-ATPase channels of gastric parietal cells. It is used for the treatment of peptic ulcer. Prolonged use of omeprazole may involve in inducing anemia. The key marker of eryptosis includes membrane blebbing, cell shrinkage and phosphatidylserine (PS) exposure at the cell surface. In current study, the eryptotic, oxidative as well as hemolytic effects of therapeutical doses (0.5, 1 and 1.5 µM) of omeprazole were investigated after exposing erythrocytes for 48 hours. Investigation of eryptosis was done by cell size measurement, PS exposure determination and calcium channel inhibition. As a possible mechanism of omeprazole induced eryptosis, oxidative stress was investigated by determining the catalase, glutathione peroxidase and superoxide dismutase activities. Similarly, necrotic effect of omeprazole on erythrocytes was also evaluated through hemolysis measurement. Results of our study illustrated that 1.5 µM of omeprazole may induce significant decrease in superoxide dismutase, glutathione peroxidase and catalase activities as well as triggered the erythrocytes shrinkage, PS exposure and hemolysis. Role of calcium was also confirmed in inducing erythrocyte shrinkage. It is concluded that the exposure of erythrocytes with 1.5 µM omeprazole may enhance the rate of eryptosis and hemolysis by inducing oxidative stress.

Stimulation of Erythrocyte Membrane Blebbing by Naproxen Sodium.

Naproxen sodium is a nonsteroidal anti-inflammatory drug (NSAID) having antipyretic and analgesic properties, mainly used for the treatment of rheumatoid arthritis and osteoarthritis. Eryptosis is an alternative term used for suicidal erythrocyte death. In the current study, eryptotic effect of naproxen sodium characterized by membrane blebbing was investigated in erythrocytes after 48 hours of treatment with different concentrations (1-25 µM). The experimental work related to investigation of eryptosis was done by cell size measurement and confirmation of calcium role in the induction of membrane blebbing. As a possible mechanism of eryptosis, oxidative stress induced by naproxen sodium was determined by catalase, glutathione peroxidase, and superoxide dismutase activities. Similarly, hemolytic effect of naproxen sodium was also determined by hemolysis measurement. Results of our study illustrated that the therapeutic doses (10-25 µM) of naproxen sodium induce oxidative stress, confirmed by significant decrease in superoxide dismutase, catalase, and glutathione peroxidase activities that lead to the triggering of cell death by eryptosis and hemolysis.

Atorvastatin Induced Erythrocytes Membrane Blebbing.

Atorvastatin, an inhibitor of 3-hydroxy-3-methylglutaryl-coenzymeA reductase, is usually used for the treatment of hypercholesterolemia. Besides its pharmacological and side actions, its toxic effects on human nucleus devoid of erythrocytes are still unknown. Eryptosis is an alternative term used for suicidal erythrocyte death. Membrane blebbing is among the common markers of eryptosis. In this study, eryptotic effect of atorvastatin was investigated by exposing the erythrocytes for 48 hours to different concentrations (1-10 µM) of atorvastatin. The experimental work related to investigation of eryptosis was done by cell size measurement and calcium channel inhibition. As a possible mechanism of eryptosis, atorvastatin-induced oxidative stress was evaluated by determining catalase, glutathione peroxidase, and superoxide dismutase activities. Similarly, necrotic effect of atorvastatin was also determined by hemolytic assay. Results of our study illustrated that the tested doses of atorvastatin may induce oxidative stress as observed by significant reduction in superoxide dismutase, glutathione peroxidase, and catalase activities as well as induce eryptosis, featured by erythrocytes membrane blebbing. The study concluded that induction of oxidative stress by atorvastatin may lead to eryptosis.

Cu nanoparticles synthesis using biological molecule of P. granatum seeds extract as reducing and capping agent: Growth mechanism and photo-catalytic activity.

In view of extended applications of nanoparticles, the nanoparticles synthesis is an extensive research field and green synthesis is one of the co-friendly methodologies. Plant extract mediated synthesis of nanoparticles has gained much attention in current decade. In current investigation, copper nanoparticles (CuNPs) were prepared using P. granatum seeds extract (biological molecules) from copper(II) chloride salt. The synthesized CuNPs were characterized by UV-vis spectroscopy, X-ray diffraction measurements (XRD), scanning electron microscopy (SEM), Energy Dispersive X- Ray Spectroscopy (EDX), Fourier transform infra-red spectroscopy (FTIR) and atomic force microscopy techniques. The CuNPs formation occurred through reduction of metal ions followed by nucleation. The size of the CuNPs was in the range of 40-80nm (average particle size was 43.9nm) with semi spherical shape and uniformly distribution. Photocatalytic activity was evaluated by degrading methylene blue dye (150mg/L) at various CuNPs doses (10mg/L-100mg/L). The synthesized CuNPs showed excellent PCA for the degradation of methylene blue (MB) under solar light irradiation and up to 87.11% degradation was achieved. The oxidative degradation mechanism for MB was proposed. In view of efficient PCA, the use of biological molecules of P. granatum seeds extracts for the synthesis of CuNPs.

Nickel nanoparticle synthesis using Camellia Sinensis as reducing and capping agent: Growth mechanism and photo-catalytic activity evaluation.

Recently, the biosynthesis of nanoparticle attracted the attention of scientific community due to its simplicity, ease and eco-friendly nature. In the present study, Camellia Sinensis (C. Sinensis) leaves extract was employed for the synthesis of nickel nanoparticles (NiNPs). The fabricated NiNPs were characterized by scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) and X-ray diffraction techniques. The photocatalytic activity (PCA) was evaluated by degrading crystal violet (CV) dye. The NiNPs size was in the range of 43.87-48.76nm, spherical in shape and uniformly distributed with magnetization saturation of 0.073 emu/g. The NiNPs showed promising PCA under solar light irradiation. At optimized conditions, up to 99.5% CV dye degradation was achieved. Results revealed that biosynthesis can be adopted for the synthesis of NiNPs in nano-size range since it is simple, cost effective and eco-friendly in nature versus physico-chemical methods.

Accelerated apoptotic death and in vivo turnover of erythrocytes in mice lacking functional mitogen- and stress-activated kinase MSK1/2.

The mitogen- and stress-activated kinase MSK1/2 plays a decisive role in apoptosis. In analogy to apoptosis of nucleated cells, suicidal erythrocyte death called eryptosis is characterized by cell shrinkage and cell membrane scrambling leading to phosphatidylserine (PS) externalization. Here, we explored whether MSK1/2 participates in the regulation of eryptosis. To this end, erythrocytes were isolated from mice lacking functional MSK1/2 (msk(-/-)) and corresponding wild-type mice (msk(+/+)). Blood count, hematocrit, hemoglobin concentration and mean erythrocyte volume were similar in both msk(-/-) and msk(+/+) mice, but reticulocyte count was significantly increased in msk(-/-) mice. Cell membrane PS exposure was similar in untreated msk(-/-) and msk(+/+) erythrocytes, but was enhanced by pathophysiological cell stressors ex vivo such as hyperosmotic shock or energy depletion to significantly higher levels in msk(-/-) erythrocytes than in msk(+/+) erythrocytes. Cell shrinkage following hyperosmotic shock and energy depletion, as well as hemolysis following decrease of extracellular osmolarity was more pronounced in msk(-/-) erythrocytes. The in vivo clearance of autologously-infused CFSE-labeled erythrocytes from circulating blood was faster in msk(-/-) mice. The spleens from msk(-/-) mice contained a significantly greater number of PS-exposing erythrocytes than spleens from msk(+/+) mice. The present observations point to accelerated eryptosis and subsequent clearance of erythrocytes leading to enhanced erythrocyte turnover in MSK1/2-deficient mice.

Vitamin D-Rich Diet in Mice Modulates Erythrocyte Survival.

BACKGROUND/AIMS: Epidemiological evidence suggests that vitamin D deficiency is associated with anemia. The potent metabolite 1,25(OH)2 vitamin D3 [1,25(OH)2D3] activates various signaling cascades regulating a myriad of cellular functions including suicidal cell death or apoptosis. Suicidal death of erythrocytes or eryptosis is characterized by cell shrinkage and cell membrane scrambling leading to phosphatidylserine (PS) externalization. Stimulation of eryptosis may limit lifespan of circulating erythrocytes and thus cause anemia. In the present study, we explored the effect of a high vitamin D diet (10,000 I.U. vitamin D for 14 days) in mice on eryptosis. METHODS: Plasma concentrations of erythropoietin were estimated using an immunoassay kit, blood count using an electronic hematology particle counter, relative reticulocyte numbers using Retic-COUNT® reagent, PS exposure at the cell surface from annexin V binding, cell volume from forward scatter, and cytosolic Ca(2+) ([Ca(2+)]i) from Fluo3-fluorescence in FACS analysis. RESULTS: Vitamin D treatment decreased mean corpuscular volume, reticulocyte count, and plasma erythropoietin levels. Vitamin D treatment slightly but significantly decreased forward scatter but did not significantly modify spontaneous PS exposure and [Ca(2+)]i of freshly drawn erythrocytes. Vitamin D treatment augmented the stimulation of PS exposure and cell shrinkage following exposure to hyperosmotic shock (addition of 550 mM sucrose) or energy depletion (glucose removal) without significantly modifying [Ca(2+)]i. CONCLUSIONS: The present observations point to a subtle effect of exogenous vitamin D supplementation on erythrocyte survival.

Therapeutic potential of manipulating suicidal erythrocyte death.

INTRODUCTION: Eryptosis, the suicidal erythrocyte death, is characterized by erythrocyte shrinkage and phosphatidylserine translocation to the erythrocyte surface. Eryptosis is triggered by cell stress such as energy depletion and oxidative stress, by Ca(2+)-entry, ceramide, caspases, calpain and/or altered activity of several kinases. Phosphatidylserine-exposing erythrocytes adhere to the vascular wall and may thus impede microcirculation. Eryptotic cells are further engulfed by phagocytes and thus rapidly cleared from circulation. AREAS COVERED: Stimulation of eryptosis contributes to anemia of several clinical conditions such as metabolic syndrome, diabetes, malignancy, hepatic failure, heart failure, uremia, hemolytic uremic syndrome, sepsis, fever, dehydration, mycoplasma infection, malaria, iron deficiency, sickle cell anemia, thalassemia, glucose-6-phosphate dehydrogenase deficiency and Wilson's disease. On the other hand, eryptosis with subsequent clearance of infected erythrocytes in malaria may counteract parasitemia. EXPERT OPINION: In theory, anemia due to excessive eryptosis could be alleviated by treatment with small molecules inhibiting eryptosis. In malaria, stimulators of eryptosis may accelerate death of infected erythrocytes and thus favorably influence the clinical course of the disease. Many small molecules inhibit or stimulate eryptosis. Several stimulators favorably influence murine malaria. Further preclinical and subsequent clinical studies are required to elucidate the therapeutic potential of stimulators or inhibitors of eryptosis.

The Role of Janus Kinase 3 in the Regulation of Na⁺/K⁺ ATPase under Energy Depletion.

BACKGROUND/AIMS: Janus kinase-3 (JAK3) is activated during energy depletion. Energy-consuming pumps include the Na(+)/K(+)-ATPase. The present study explored whether JAK3 regulates Na(+)/K(+)-ATPase in dendritic cells (DCs). METHODS: Ouabain (100 µM)-sensitive (Iouabain) and K(+)-induced (Ipump) outward currents were determined by utilizing whole cell patch-clamp, Na(+)/K(+)-ATPase α1-subunit mRNA levels by RT-PCR, Na(+)/K(+)-ATPase protein abundance by flow cytometry or immunofluorescence, and cellular ATP by luciferase-assay in DCs from bone marrow of JAK3-knockout (jak3(-/-)) or wild-type mice (jak3(+/+)). Ipump was further determined by voltage clamp in Xenopus oocytes expressing JAK3, active (A568V)JAK3 or inactive (K851A)JAK3. RESULTS: Na(+)/K(+)-ATPase α1-subunit mRNA and protein levels, as well as Ipump and Iouabain were significantly higher in jak3(-/-)DCs than in jak3(+/+)DCs. Energy depletion by 4h pre-treatment with 2,4-dinitro-phenol significantly decreased Ipump in jak3(+/+) DCs but not in jak3(-/-)DCs. Cellular ATP was significantly lower in jak3(-/-)DCs than in jak3(+/+)DCs and decreased in both genotypes by 2,4-dinitro-phenol, an effect significantly more pronounced in jak3(-/-)DCs than in jak3(+/+)DCs and strongly blunted by ouabain in both jak3(+/+) and jak3(-/-)DCs. Ipump and Iouabain in oocytes were decreased by expression of JAK3 and of (A568V)JAK3 but not of (K851A)JAK3. JAK3 inhibitor WHI-P154 (4-[(3'-bromo-4'-hydroxyphenyl)amino]-6,7-dimethoxyquinazoline, 22 µM) enhanced Ipump and Iouabain in JAK3 expressing oocytes. The difference between (A568V)JAK3 and (K851A)JAK3 expressing oocytes was virtually abrogated by actinomycin D (50 nM). CONCLUSIONS: JAK3 down-regulates Na(+)/K(+)-ATPase activity, an effect involving gene expression and profoundly curtailing ATP consumption.

Enhanced eryptosis following juglone exposure.

Juglone, a quinone isolated from Juglans mandshurica Maxim, has previously been shown to be effective against malignancy. The effect is at least partially due to stimulation of suicidal death or apoptosis of tumour cells. On the other hand, juglone has been shown to counteract apoptosis, for example, of neurons. In analogy to apoptosis of nucleated cells, erythrocytes may enter eryptosis, a suicidal death characterized by cell shrinkage and breakdown of phosphatidylserine asymmetry of the cell membrane with phosphatidylserine exposure at the erythrocyte surface. Stimulators of eryptosis include increase in cytosolic Ca(2+) activity [(Ca(2+) )i]. This study explored whether juglone stimulates eryptosis. To this end, erythrocyte volume was estimated from forward scatter, phosphatidylserine exposure at the erythrocyte surface from FITC annexin V binding, ceramide abundance from binding of fluorescent antibodies in flow cytometry and cytosolic ATP with a luciferin-luciferase-based assay. As a result, a 24-hr exposure of human erythrocytes to juglone (5 µM) significantly decreased erythrocyte forward scatter. Juglone (1-5 µM) significantly increased the percentage of annexin V binding cells. Juglone (5 µM) significantly increased ceramide abundance at the erythrocyte surface and decreased erythrocyte ATP concentration. The effect of juglone (10 µM) on annexin V binding was slightly but significantly blunted by removal of extracellular Ca(2+) and by addition of protein kinase C (PKC) inhibitor staurosporine (1 µM). In conclusion, juglone stimulates suicidal erythrocyte death or eryptosis at least in part by upregulation of ceramide abundance, energy depletion and activation of PKC.

Stimulation of erythrocyte cell membrane scrambling by nystatin.

The antifungal ionophore nystatin dissipates the Na(+) and K(+) gradients across the cell membrane, leading to cellular gain of Na(+) and cellular loss of K(+) . The increase of cellular Na(+) concentration may result in Ca(2+) accumulation in exchange for Na(+) . Increase of cytosolic Ca(2+) activity ([Ca(2+) ]i ) and loss of cellular K(+) foster apoptosis-like suicidal erythrocyte death or eryptosis, which is characterised by cell shrinkage and cell membrane scrambling leading to phosphatidylserine exposure at the erythrocyte surface. The present study explored whether nystatin stimulates eryptosis. Cell volume was estimated from forward scatter (FSC), phosphatidylserine exposure from annexin V binding and [Ca(2+) ]i from Fluo3-fluorescence in flow cytometry. A 48-hr exposure to nystatin (15 µg/ml) was followed by a significant increase of [Ca(2+) ]i , a significant increase of annexin V binding and a significant decrease of FSC. The annexin V binding after nystatin treatment was significantly blunted in the nominal absence of extracellular Ca(2+) . Partial replacement of extracellular Na(+) with extracellular K(+) blunted the nystatin-induced erythrocyte shrinkage but increased [Ca(2+) ]i and annexin V binding. Nystatin triggers cell membrane scrambling, an effect at least partially due to entry of extracellular Ca(2+) .

Aristolochic acid induced suicidal erythrocyte death.

BACKGROUND/AIMS: Aristolochic Acid, a component of Aristolochia plants, has been shown to cause acute kidney injury, renal aristolochic acid nephropathy, Balkan endemic nephropathy, and urothelial carcinoma. Aristolochic acid nephropathy may be associated with severe anemia. The anemia could theoretically be due to stimulation of eryptosis, the suicidal death of erythrocytes characterized by cell shrinkage and cell membrane scrambling with translocation of phosphatidylserine to the erythrocyte cell membrane surface. Signalling involved in the stimulation of eryptosis include increase of cytosolic Ca(2+)-activity ([Ca(2+)]i) and formation of ceramide. METHODS: Cell volume was estimated from forward scatter, phosphatidylserine-exposure from annexin V binding, [Ca(2+)]i from Fluo3 fluorescence, and ceramide abundance from binding of fluorescent antibodies in flow cytometry. RESULTS: A 48 hours exposure to Aristolochic Acid (≥ 75 µg/ml) was followed by a significant decrease of forward scatter and increase of annexin-V-binding. The effects were paralleled by a significant increase of [Ca(2+)]i and significantly blunted, but not abrogated by removal of extracellular Ca(2+). Aristolochic Acid further significantly increased ceramide abundance. CONCLUSIONS: Aristolochic Acid triggers eryptosis, an effect at least in part due to entry of extracellular Ca(2+) and ceramide formation.

Piperlongumine-induced phosphatidylserine translocation in the erythrocyte membrane.

BACKGROUND: Piperlongumine, a component of Piper longum fruit, is considered as a treatment for malignancy. It is effective by inducing apoptosis. Mechanisms involved in the apoptotic action of piperlongumine include oxidative stress and activation of p38 kinase. In analogy to apoptosis of nucleated cells, erythrocytes may undergo eryptosis, the suicidal death of erythrocytes characterized by cell shrinkage and cell membrane scrambling with phosphatidylserine-exposure at the erythrocyte surface. Signaling involved in eryptosis include increase of cytosolic Ca²âº-activity ([Ca²âº]i), formation of ceramide, oxidative stress and activation of p38 kinase. METHODS: Cell volume was estimated from forward scatter, phosphatidylserine-exposure from annexin V binding, [Ca²âº]i from Fluo3 fluorescence, reactive oxygen species from 2',7'-dichlorodihydrofluorescein-diacetate fluorescence, and ceramide abundance from binding of fluorescent antibodies in flow cytometry. RESULTS: A 48 h exposure to piperlongumine (30 µM) was followed by significant decrease of forward scatter and increase of annexin-V-binding. Piperlongumine did not significantly modify [Ca²âº]i and the effect was not dependent on presence of extracellular Ca²âº. Piperlongumine significantly increased ROS formation and ceramide abundance. CONCLUSIONS: Piperlongumine triggers cell membrane scrambling, an effect independent from entry of extracellular Ca²âº but at least partially due to ROS and ceramide formation.

In vitro sensitization of erythrocytes to programmed cell death following baicalein treatment.

The polyphenolic flavonoid Baicalein has been shown to trigger suicidal death or apoptosis of tumor cells and is thus considered for the prevention and treatment of malignancy. Similar to apoptosis of nucleated cells, erythrocytes may enter eryptosis, the suicidal erythrocyte death characterized by cell shrinkage and cell membrane scrambling with phosphatidylserine translocation to the erythrocyte surface. Stimulators of eryptosis include increase of cytosolic Ca2+-activity ([Ca2+]i) and ceramide. The present study explored whether Baicalein stimulates eryptosis. To this end, forward scatter was taken for measurement of cell volume, annexin-V-binding for phosphatidylserine-exposure, Fluo3 fluorescence for [Ca2+]i and fluorescent antibodies for ceramide abundance. As a result, a 48 h exposure of human erythrocytes to Baicalein was followed by significant decrease of forward scatter (≥10 µM), significant increase of the percentage of annexin-V-binding cells (≥25 µM), significant increase of [Ca2+]i (50 µM) and significant increase of ceramide abundance (50 µM). The effect of Baicalein (50 µM) on annexin-V-binding was significantly blunted but not abrogated by removal of extracellular Ca2+. In conclusion, at the concentrations employed, Baicalein stimulates suicidal erythrocyte death or eryptosis, an effect at least in part due to the combined effects of Ca2+ entry and ceramide formation.