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1.
Adv Mater ; : e2108637, 2022 Jan 19.
Artigo em Inglês | MEDLINE | ID: mdl-35048455

RESUMO

There is considerable interest in van der Waals (vdW) materials as potential hosts for chiral skyrmionic spin textures. Of particular interest is the ferromagnetic, metallic compound Fe3 GeTe2 (FGT), which has a comparatively high Curie temperature (150-220 K). Several recent studies have reported the observation of chiral Néel skyrmions in this compound, which is inconsistent with its presumed centrosymmetric structure. Here we report the observation of Néel type skyrmions in single crystals of FGT via Lorentz transmission electron microscopy (LTEM). We show from detailed X-ray diffraction structure analysis that FGT lacks an inversion symmetry as a result of an asymmetric distribution of Fe vacancies. This vacancy-induced breaking of the inversion symmetry of this compound is a surprising and novel observation and is a prerequisite for a Dzyaloshinskii-Moriya vector exchange interaction which accounts for the chiral Néel skyrmion phase. This phenomenon is likely to be common to many two-dimensional (2D) vdW materials and suggests a path to the preparation of many such acentric compounds. Furthermore, we find that the skyrmion size in FGT is strongly dependent on its thickness: the skyrmion size increases from ∼100 to ∼750 nm as the thickness of the lamella is increased from ∼90 nm to ∼2 µm. This extreme size tunability is a feature common to many low symmetry ferro- and ferri-magnetic compounds. This article is protected by copyright. All rights reserved.

2.
Exp Cell Res ; 410(2): 112970, 2022 01 15.
Artigo em Inglês | MEDLINE | ID: mdl-34896076

RESUMO

Islet integrity plays a major role in maintaining glucose homeostasis and thus replenishment of damaged islets by differentiation of resident endocrine progenitors into neo islets regulates the islet functionality. Islet differentiation is affected by many factors including crosstalk with various organs by secretome. Adipose derived stem cells (ADSC) secrete a large array of factors in the extracellular milieu that exhibit regulatory effects on other tissues including pancreatic islets. The microenvironment of metabolically compromised human ADSCs (hADSCs) has a detrimental impact on islet functionality. In the present study, the role of secretome was studied on the differentiation of islets. Expression of key transcription factors like HNF-3B, NGN-3, NeuroD, PDX- 1, Maf-A, and GLUT-2 involved in development were differentially regulated in obese hADSC secretome as compared to control hADSC secretome. Islet like cell clusters (ILCCs) functionality and viability were critically hampered under obese hADSC secretome with compromised yield, morphometry, lower expression of C-peptide and Glucagon as well as higher ROS activity and cell death parameters. This study provides considerable insights on two major findings which are (i) exploring the use of hADSC secretome in islet differentiation and (ii) understanding the regulating effect of altered hADSC secretome under a metabolically compromised condition.


Assuntos
Tecido Adiposo/citologia , Diferenciação Celular , Ilhotas Pancreáticas/citologia , Células-Tronco/metabolismo , Animais , Diferenciação Celular/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Meios de Cultivo Condicionados/farmacologia , Humanos , Camundongos , Obesidade/patologia , Fenótipo , Células-Tronco/citologia , Células-Tronco/efeitos dos fármacos , Fatores de Tempo
3.
Adv Mater ; 33(32): e2101323, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34218470

RESUMO

Magnetic nano-objects, namely antiskyrmions and Bloch skyrmions, have been found to coexist in single-crystalline lamellae formed from bulk crystals of inverse tetragonal Heusler compounds with D2d symmetry. Here evidence is shown for magnetic nano-objects in epitaxial thin films of Mn2 RhSn formed by magnetron sputtering. These nano-objects exhibit a wide range of sizes with stability with respect to magnetic field and temperature that is similar to single-crystalline lamellae. However, the nano-objects do not form well-defined arrays, nor is any evidence found for helical spin textures. This is speculated to likely be a consequence of the poorer homogeneity of chemical ordering in the thin films. However, evidence is found for elliptically distorted nano-objects along perpendicular crystallographic directions within the epitaxial films, which is consistent with elliptical Bloch skyrmions observed in single-crystalline lamellae. Thus, these measurements provide strong evidence for the formation of noncollinear spin textures in thin films of Mn2 RhSn. Using these films, it is shown that individual nano-objects can be deleted using a local magnetic field from a magnetic tip and collections of nano-objects can be similarly written. These observations suggest a path toward the use of these objects in thin films with D2d symmetry as magnetic memory elements.

4.
Arch Biochem Biophys ; 710: 108995, 2021 10 15.
Artigo em Inglês | MEDLINE | ID: mdl-34289381

RESUMO

Failing pancreas and subsequent loss of pancreatic ß cells worsen diabetic conditions which are further alleviated by the mounting up of glucose levels. Inhibition of sodium glucose cotransporter 2 (SGLT2) in the kidney responsible for glucose reabsorption strikingly reduces blood glucose levels. Bioactive swertisin showed a promising glucose-lowering effect. Hence, we aimed to mechanistically dissect the glucose lowering property of swertisin. A systematic in silico, in vitro, and in vivo approach was directed for target analysis of swertisin. Molecular docking was performed with Swertisn-hSGLT2 complex. Glucose uptake assay and protein expression for SGLT2 and regulatory proteins were performed under swertisin effect. Various physiological and metabolic parameters were evaluated in STZ induced BALB/c mice using swertisin treatment. SGLT2 expression was evaluated in the kidney tissue of mice. Swertisn-hSGLT2 molecularly docked complex showed similar binding energy compared to the Canagliflozin-hSGLT2 complex. Swertisin inhibited glucose uptake and decreased expression of SGLT2 in HEK293 cells. Swertisin does not affect GLUT mediated glucose transport. Swertisin treated diabetic mice demonstrated remarkable improvement in overall glucose homeostasis. Reduced expression of SGLT2 was found in kidney tissue along with reduced PKC expression which is one of the key regulators of SGLT2. Our study explored SGLT2 as a selective target of swertisin for its swift glucose-lowering action which not only inhibits SGLT2 but also reduces its expression in diabetic condition. Thus, the potential property of swertisin as a glucose-lowering agent is remarkable which points towards the likelihood of a wider avenue of diabetes therapy.


Assuntos
Apigenina/farmacologia , Diabetes Mellitus Tipo 2/tratamento farmacológico , Diabetes Mellitus Tipo 2/metabolismo , Hipoglicemiantes/farmacologia , Inibidores do Transportador 2 de Sódio-Glicose/farmacologia , Animais , Células CACO-2 , Simulação por Computador , Diabetes Mellitus Experimental/tratamento farmacológico , Diabetes Mellitus Experimental/metabolismo , Glucose/metabolismo , Células HEK293 , Homeostase/efeitos dos fármacos , Humanos , Células Secretoras de Insulina/efeitos dos fármacos , Células Secretoras de Insulina/metabolismo , Rim/efeitos dos fármacos , Rim/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Modelos Moleculares , Fitoterapia , Transportador 2 de Glucose-Sódio/química , Transportador 2 de Glucose-Sódio/efeitos dos fármacos , Transportador 2 de Glucose-Sódio/metabolismo
5.
Cells ; 10(3)2021 03 05.
Artigo em Inglês | MEDLINE | ID: mdl-33807701

RESUMO

Kearns Sayre syndrome (KSS) is mitochondrial multisystem disorder with no proven effective treatment. The underlying cause for multisystem involvement is the energy deficit resulting from the load of mutant mitochondrial DNA (mtDNA), which manifests as loss of cells and tissue dysfunction. Therefore, functional organ or cellular replacement provides a promising avenue as a therapeutic option. Patient-specific induced pluripotent stem cells (iPSC) have become a handy tool to create personalized cell -based therapies. iPSC are capable of self-renewal, differentiation into all types of body cells including cardiomyocytes (CM) and neural progenitor cells (NPC). In KSS patients, mutations in mtDNA are largely found in the muscle tissue and are predominantly absent in the blood cells. Therefore, we conceptualized that peripheral blood mononuclear cells (PBMNC) from KSS patients can be reprogrammed to generate mutation free, patient specific iPSC lines that can be used as isogenic source of cell replacement therapies to treat affected organs. In the current study we generated iPSC lines from two female patients with clinical diagnosis of classic KSS. Our data demonstrate that iPSC from these KSS patients showed normal differentiation potential toward CM, NPC and fibroblasts without any mtDNA deletions over passages. Next, we also found that functional studies including ATP production, reactive oxygen species generation, lactate accumulation and mitochondrial membrane potential in iPSC, CM, NPC and fibroblasts of these KSS patients were not different from respective cells from healthy controls. PBMNCs from these KSS patients in the current study did not reproduce mtDNA mutations which were present in muscle biopsies. Furthermore, we demonstrate for the first time that this phenomenon provides opportunities to create isogenic mutation free iPSC with absent or very low level of expression of mtDNA deletion which can be banked for future cell replacement therapies in these patients as the disease progresses.


Assuntos
DNA Mitocondrial/genética , Células-Tronco Pluripotentes Induzidas/metabolismo , Síndrome de Kearns-Sayre/fisiopatologia , Feminino , Humanos
6.
Stem Cell Res ; 53: 102355, 2021 05.
Artigo em Inglês | MEDLINE | ID: mdl-33901817

RESUMO

Induced pluripotent stem cell (iPSC) line was derived from peripheral blood mononuclear cells (PBMCs) of a Kearns-Sayre syndrome (KSS) patient with mtDNA deletion of 4.8 kilobase fragment. KSS is an ultrarare multi-organ disorder and is characterized with (1.1 to 10 kilobase) deletion of mitochondrial DNA (mtDNA) with a frequency of ~1 in 100,000 individuals. Heteroplasmy in PBMCs allowed us to generate an iPSC line with normal mitochondrial DNA that can be used to study therapeutic prospective of iPSC and their derivatives and design future cell replacement therapies.


Assuntos
Células-Tronco Pluripotentes Induzidas , Síndrome de Kearns-Sayre , DNA Mitocondrial/genética , Humanos , Síndrome de Kearns-Sayre/genética , Leucócitos Mononucleares , Estudos Prospectivos
7.
Stem Cell Res ; 53: 102283, 2021 05.
Artigo em Inglês | MEDLINE | ID: mdl-33756177

RESUMO

Kearns-Sayre syndrome (KSS) is an ultrarare multi-organ disorder, with a frequency of ~1 in 100,000 individuals. KSS is characterized with (1.1-10 kilobase) deletion of a mitochondrial DNA (mtDNA). We created an induced pluripotent stem cell (iPSC) line from peripheral blood mononuclear cells (PBMCs) of a patient with mtDNA deletion of 7.3 kilobase fragment. Heteroplasmy in PBMCs provides a novel opportunity to generate iPSC with normal mitochondrial DNA that can be used to develop patient specific cell replacement therapies in future. Hence, this unique line was created to study phenotype and therapeutic prospective of iPSC and their derivatives.


Assuntos
Células-Tronco Pluripotentes Induzidas , Síndrome de Kearns-Sayre , DNA Mitocondrial/genética , Humanos , Síndrome de Kearns-Sayre/genética , Leucócitos Mononucleares , Estudos Prospectivos
8.
J Eng Math ; 127(1): 1, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33642613

RESUMO

In this work, an eco-epidemic predator-prey model with media-induced response function for the interaction of humans with adulterated food is developed and studied. The human population is divided into two main compartments, namely, susceptible and infected. This system has three equilibria; trivial, disease-free and endemic. The trivial equilibrium is forever an unstable saddle position, while the disease-free state is locally asymptotically stable under a threshold of delay parameter τ as well as R 0 < 1 . The sufficient conditions for the local stability of the endemic equilibrium point are further explored when min { R 0 , R 0 ∗ } > 1 . The conditions for the occurrence of the stability switching are also determined by taking infection delay time as a critical parameter, which concludes that the delay can produce instability and small amplitude oscillations of population masses via Hopf bifurcations. Further, we study the stability and direction of the Hopf bifurcations using the center manifold argument. Furthermore, some numerical simulations are conducted to validate our analytical findings and discuss their biological inferences. Finally, the normalized forward sensitivity index is used to perform the sensitivity analysis of R 0 and R 0 ∗ .

9.
Can J Physiol Pharmacol ; 99(2): 140-150, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33559528

RESUMO

Ischemic heart disease is among the primary causes of cardiovascular-related deaths worldwide. Conventional treatments including surgical interventions and medical therapies aid in preventing further damage to heart muscle but are unable to provide a permanent solution. In recent years, stem cell therapy has emerged as an attractive alternative to restore damaged myocardium after myocardial injury. Allogeneic (donor-derived) mesenchymal stem cells (MSCs) have shown great promise in preclinical and clinical studies, making them the most widely accepted candidates for cardiac cell therapy. MSCs promote cardiac repair by modulating host immune system and secreting various soluble factors, of which prostaglandin E2 (PGE2) is an important one. PGE2 plays a significant role in regulating cardiac remodeling following myocardial injury. In this review, we provide an overview of allogeneic MSCs as candidates for myocardial regeneration with a focus on the role of the PGE2/cyclooxygenase-2 (COX2) pathway in mediating these effects.


Assuntos
Procedimentos Cirúrgicos Cardíacos , Dinoprostona/metabolismo , Transplante de Células-Tronco Mesenquimais , Animais , Humanos , Transplante Homólogo
10.
Am J Physiol Heart Circ Physiol ; 320(4): H1290-H1302, 2021 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-33513084

RESUMO

Bone marrow-derived mesenchymal stem cells (BM-MSCs) have demonstrated potential in treating diabetic cardiomyopathy. However, patients with diabetes are on multiple drugs and there is a lack of understanding of how transplanted stem cells would respond in presence of such drugs. Metformin is an AMP kinase (AMPK) activator, the widest used antidiabetic drug. In this study, we investigated the effect of metformin on the efficacy of stem cell therapy in a diabetic cardiomyopathy animal model using streptozotocin (STZ) in male Wistar rats. To comprehend the effect of metformin on the efficacy of BM-MSCs, we transplanted BM-MSCs (1 million cells/rat) with or without metformin. Our data demonstrate that transplantation of BM-MSCs prevented cardiac fibrosis and promoted angiogenesis in diabetic hearts. However, metformin supplementation downregulated BM-MSC-mediated cardioprotection. Interestingly, both BM-MSCs and metformin treatment individually improved cardiac function with no synergistic effect of metformin supplementation along with BM-MSCs. Investigating the mechanisms of loss of efficacy of BM-MSCs in the presence of metformin, we found that metformin treatment impairs homing of implanted BM-MSCs in the heart and leads to poor survival of transplanted cells. Furthermore, our data demonstrate that metformin-mediated activation of AMPK is responsible for poor homing and survival of BM-MSCs in the diabetic heart. Hence, the current study confirms that a conflict arises between metformin and BM-MSCs for treating diabetic cardiomyopathy. Approximately 10% of the world population is diabetic to which metformin is prescribed very commonly. Hence, future cell replacement therapies in combination with AMPK inhibitors may be more effective for patients with diabetes.NEW & NOTEWORTHY Metformin treatment reduces the efficacy of mesenchymal stem cell therapy for cardiac repair during diabetic cardiomyopathy. Stem cell therapy in diabetics may be more effective in combination with AMPK inhibitors.


Assuntos
Movimento Celular/efeitos dos fármacos , Diabetes Mellitus Experimental/tratamento farmacológico , Cardiomiopatias Diabéticas/cirurgia , Hipoglicemiantes/toxicidade , Transplante de Células-Tronco Mesenquimais , Células-Tronco Mesenquimais/efeitos dos fármacos , Metformina/toxicidade , Miocárdio/patologia , Proteínas Quinases Ativadas por AMP/metabolismo , Animais , Glicemia/efeitos dos fármacos , Glicemia/metabolismo , Sobrevivência Celular/efeitos dos fármacos , Células Cultivadas , Diabetes Mellitus Experimental/sangue , Diabetes Mellitus Experimental/induzido quimicamente , Diabetes Mellitus Experimental/metabolismo , Cardiomiopatias Diabéticas/sangue , Cardiomiopatias Diabéticas/etiologia , Cardiomiopatias Diabéticas/patologia , Modelos Animais de Doenças , Fibrose , Hemoglobina A Glicada/metabolismo , Insulina/sangue , Masculino , Células-Tronco Mesenquimais/metabolismo , Miocárdio/metabolismo , Neovascularização Fisiológica/efeitos dos fármacos , Ratos Wistar , Recuperação de Função Fisiológica , Estreptozocina
11.
Stem Cell Res Ther ; 11(1): 327, 2020 07 30.
Artigo em Inglês | MEDLINE | ID: mdl-32731883

RESUMO

BACKGROUND: Despite the potential, bone marrow-derived mesenchymal stem cells (BMSCs) show limitations for beta (ß)-cell replacement therapy due to inefficient methods to deliver BMSCs into pancreatic lineage. In this study, we report TGF-ß family member protein, Activin-a potential to stimulate efficient pancreatic migration, enhanced homing and accelerated ß-cell differentiation. METHODS: Lineage tracing of permanent green fluorescent protein (GFP)- tagged donor murine BMSCs transplanted either alone or in combination with Activin-a in diabetic mice displayed potential ß-cell regeneration and reversed diabetes. RESULTS: Pancreatic histology of Activin-a treated recipient mice reflected high GFP+BMSC infiltration into damaged pancreas with normalized fasting blood glucose and elevated serum insulin. Whole pancreas FACS profiling of GFP+ cells displayed significant homing of GFP+BMSC with Activin-a treatment (6%) compared to BMSCs alone transplanted controls (0.5%). Within islets, approximately 5% GFP+ cells attain ß-cell signature (GFP+ Ins+) with Activin-a treatment versus controls. Further, double immunostaining for mesenchymal stem cell markers CD44+/GFP+ in infiltrated GFP+BMSC deciphers substantial endocrine reprogramming and ß-cell differentiation (6.4% Ins+/GFP+) within 15 days. CONCLUSION: Our investigation thus presents a novel pharmacological approach for stimulating direct migration and homing of therapeutic BMSCs that re-validates BMSC potential for autologous stem cell transplantation therapy in diabetes.


Assuntos
Diabetes Mellitus Experimental , Transplante de Células-Tronco Hematopoéticas , Transplante de Células-Tronco Mesenquimais , Células-Tronco Mesenquimais , Ativinas , Animais , Células da Medula Óssea , Camundongos , Pâncreas , Transplante Autólogo
12.
Adv Mater ; 32(28): e2002043, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32484269

RESUMO

Skyrmions and antiskyrmions are magnetic nano-objects with distinct chiral, noncollinear spin textures that are found in various magnetic systems with crystal symmetries that give rise to specific Dzyaloshinskii-Moriya exchange vectors. These magnetic nano-objects are associated with closely related helical spin textures that can form in the same material. The skyrmion size and the period of the helix are generally considered as being determined, in large part, by the ratio of the magnitude of the Heisenberg to that of the Dzyaloshinskii-Moriya exchange interaction. In this work, it is shown by real-space magnetic imaging that the helix period λ and the size of the antiskyrmion daSk in the D2d compound Mn1.4 PtSn can be systematically tuned by more than an order of magnitude from ≈100 nm to more than 1.1 µm by varying the thickness of the lamella in which they are observed. The chiral spin texture is verified to be preserved even up to micrometer-thick layers. This extreme size tunability is shown to arise from long-range magnetodipolar interactions, which typically play a much less important role for B20 skyrmions. This tunability in size makes antiskyrmions very attractive for technological applications.

13.
Cell Death Dis ; 11(6): 419, 2020 06 04.
Artigo em Inglês | MEDLINE | ID: mdl-32499535

RESUMO

Allogeneic mesenchymal stem cells (MSCs) are immunoprivileged and are being investigated in phase I and phase II clinical trials to treat different degenerative and autoimmune diseases. In spite of encouraging outcome of initial trials, the long-term poor survival of transplanted cells in the host tissue has declined the overall enthusiasm. Recent analyses of allogeneic MSCs based studies confirm that after transplantation in the hypoxic or ischemic microenvironment of diseased tissues, MSCs become immunogenic and are rejected by recipient immune system. The immunoprivilege of MSCs is preserved by absence or negligible expression of cell surface antigen, human leukocyte antigen (HLA)-DRα. We found that in normoxic MSCs, 26S proteasome degrades HLA-DRα and maintains immunoprivilege of MSCs. The exposure to hypoxia leads to inactivation of 26S proteasome and formation of immunoproteasome in MSCs, which is associated with upregulation and activation of HLA-DRα, and as a result, MSCs become immunogenic. Furthermore, inhibition of immunoproteasome formation in hypoxic MSCs preserves the immunoprivilege. Therefore, hypoxia-induced shift in the phenotype of proteasome from 26S toward immunoproteasome triggers loss of immunoprivilege of allogeneic MSCs. The outcome of the current study may provide molecular targets to plan interventions to preserve immunoprivilege of allogeneic MSCs in the hypoxic or ischemic environment.


Assuntos
Células-Tronco Mesenquimais/imunologia , Células-Tronco Mesenquimais/patologia , Complexo de Endopeptidases do Proteassoma/imunologia , Hipóxia Celular/imunologia , Regulação para Baixo , Cadeias alfa de HLA-DR/metabolismo , Humanos , Fenótipo , Subunidades Proteicas/metabolismo , Proteólise , Regulação para Cima
14.
Research (Wash D C) ; 2020: 4643507, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32318686

RESUMO

Highly conductive topological semimetals with exotic electronic structures offer fertile ground for the investigation of the electrical and thermal transport behavior of quasiparticles. Here, we find that the layer-structured Dirac semimetal PtSn4 exhibits a largely suppressed thermal conductivity under a magnetic field. At low temperatures, a dramatic decrease in the thermal conductivity of PtSn4 by more than two orders of magnitude is obtained at 9 T. Moreover, PtSn4 shows both strong longitudinal and transverse thermoelectric responses under a magnetic field. Large power factor and Nernst power factor of approximately 80-100 µW·cm-1·K-2 are obtained around 15 K in various magnetic fields. As a result, the thermoelectric figure of merit zT is strongly enhanced by more than 30 times, compared to that without a magnetic field. This work provides a paradigm for the decoupling of the electron and hole transport behavior of highly conductive topological semimetals and is helpful for developing topological semimetals for thermoelectric energy conversion.

15.
Artigo em Inglês | MEDLINE | ID: mdl-32154300

RESUMO

INTRODUCTION: Disaster can occur at any time any place. Disaster preparedness plays an important role to reduce the loss of a community/country. The aim of this interventional study was to ascertain the impact of a video-based educational intervention program on improvement in knowledge and attitude of paramedical students in a hospital. MATERIALS AND METHODS: A pre-post study (interventional study design) was conducted on paramedic students. Our study period was 6 months which was divided into Phases I, II, and III. For administrative purpose, we included all paramedical students, and our sample size was 119. The baseline assessment of knowledge and attitude of paramedic students was done by a pretested questionnaire (Observation 1) with having a baseline scoring. After that, intervention Phase 1 was implemented, and later, end line observation (Observation 2) was made. Changes in knowledge and attitude were observed by the score difference (Observation 2-Observation 1). Descriptive statistics were calculated, and the mean of cumulative score was compared using the Wilcoxon signed-rank test. We applied Mann-Whitney U-test for finding associations between dependent variables with an independent variable using SPSS version 22 (IBM, Chicago, USA) software. RESULTS: Our baseline results showed that most of our participants had average knowledge (54.6%), followed by poor knowledge (24.4%). Approximately one-fifth (21.0%) of the participants had good knowledge regarding disaster preparedness. A significant improvement was observed in cumulative score (P < 0.005). A significant difference was observed in knowledge and attitude with respect to age and courses (P < 0.05). Forty percent of the students responded that they would like to get trained by that mock drill, and 26.1% were interested in disaster preparedness workshops in the future. CONCLUSION: Our present study results indicate that the overall knowledge and attitude level of the students was average and required improvement. A similar result was reported in some studies conducted globally for the same purpose. All of our students perceived that training for disaster preparedness is necessary for all health facilities, and it is important to have an emergency plan and disaster management committee. Regarding training methods, most of our students liked our interactive audiovisual method. However, their preferred methods were mock drill and workshops. It can be arranged in the future for them.

16.
J Family Med Prim Care ; 9(1): 16-19, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32110558

RESUMO

Preserving health requires a holistic approach involving the component of physical, mental, social, and spiritual well-being as stated by World Health Organisation. Salutogenesis concept focuses on the factors responsible for well-being rather than the disease pathogenesis in contrary to pathogenesis concept. This evidence-based summary tries to shed a light on existing concept called salutogenesis which is much required in the current scenario.

17.
Heliyon ; 6(1): e03041, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31909246

RESUMO

Introduction: The purpose of this research work was to evaluate Piper betle ethyl acetate extract (PBEA) for its free radical scavenging, antioxidant, anti-apoptotic activities and its role in protecting against oxidative cardiac cell injury. Methods: The Free radical scavenging activity and antioxidant potential of PBEA were evaluated using various non-cellular methods (1,1-Diphenyl-2-picrylhydrazyl, ß-carotene bleaching, superoxide anion, hydroxyl radical, hydrogen peroxide, Reducing power, Total phenolics and Total flavonoids). PBEA was standardized with Eugenol by GC-FID analysis. Furthermore, PBEA was also assessed for its cytotoprotective effect against 100µM H2O2 in H9c2 cells using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay. Intracellular reactive oxygen species scavenging and anti-apoptoic activity of PBEA was assessed by using 2', 7'-Dichlorofluorescein diacetate and Annexin- Propidium Iodide, respectively. Results: PBEA exhibited radical scavenging and antioxidant defense response at different magnitudes of potency. Eugenol, a cardiac protective bioactive molecule in PBEA was found to be 43.43 ± 1.46 mg/g of PBEA extract. Further, pre-incubation of H9c2 cells with 10 µg/ml PBEA for 24 h exhibited remarkable cytoprotective effect against H2O2 induced oxidative stress. PBEA at 10 µg/ml dose with 24 h contact with H9c2 cells significantly enhanced the activity of cellular defense system and significantly decreased intracellular ROS (P < 0.001) and apoptosis (P < 0.01) thereby protecting against the cytotoxic effects of H2O2. Conclusion: These outcomes indicated that PBEA could shield against oxidative and apoptotic cardiac cell injury in invitro studies. Thus, PBEA might be a desirable antioxidant of natural origin that has future clinical implications in both health care and food industry.

18.
Adv Mater ; 32(7): e1904327, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31880023

RESUMO

Over the past decade the family of chiral noncollinear spin textures has continued to expand with the observation in metallic compounds of Bloch-like skyrmions in several B20 compounds, and antiskyrmions in a tetragonal inverse Heusler. Néel like skyrmions in bulk crystals with broken inversion symmetry have recently been seen in two distinct nonmetallic compounds, GaV4 S8 and VOSe2 O5 at low temperatures (below ≈13 K) only. Here, the first observation of bulk Néel skyrmions in a metallic compound PtMnGa and, moreover, at high temperatures up to ≈220 K is reported. Lorentz transmission electron microscopy reveals the chiral Néel character of the skyrmions. A strong variation is reported of the size of the skyrmions on the thickness of the lamella in which they are confined, varying by a factor of 7 as the thickness is varied from ≈90 nm to ≈4 µm. Moreover, the skyrmions are highly robust to in-plane magnetic fields and can be stabilized in a zero magnetic field using suitable field-cooling protocols over a very broad temperature range to as low as 5 K. These properties, together with the possibility of manipulating skyrmions in metallic PtMnGa via current induced spin-orbit torques, make them extremely exciting for future spintronic applications.

19.
Nano Lett ; 20(1): 59-65, 2020 Jan 08.
Artigo em Inglês | MEDLINE | ID: mdl-31809059

RESUMO

Recently, magnetic antiskyrmions were discovered in Mn1.4Pt0.9Pd0.1Sn, an inverse tetragonal Heusler compound that is nominally a ferrimagnet, but which can only be formed with substantial Mn vacancies. The vacancies reduce considerably the compensation of the moments between the two expected antiferromagnetically coupled Mn sub-lattices so that the overall magnetization is very high and the compound is almost a "ferromagnet". Here, we report the observation of antiskyrmions in a second inverse tetragonal Heusler compound, Mn2Rh0.95Ir0.05Sn, which can be formed stoichiometrically without any Mn vacancies and which thus exhibits a much smaller magnetization. Individual and lattices of antiskyrmions can be stabilized over a wide range of temperature from near room temperature to 100 K, the base temperature of the Lorentz transmission electron microscope used to image them. In low magnetic fields helical spin textures are found which evolve into antiskyrmion structures in the presence of small magnetic fields. A weaker Dzyaloshinskii-Moriya interaction (DMI), that stabilizes the antiskyrmions, is expected for the 4d element Rh as compared to the 5d element Pt, so that the observation of antiskyrmions in Mn2Rh0.95Ir0.05Sn establishes the intrinsic stability of antiskyrmions in these Heusler compounds. Moreover, the finding of antiskyrmions with substantially lower magnetization promises, via chemical tuning, even zero moment antiskyrmions with important technological import.

20.
Nat Commun ; 10(1): 5305, 2019 11 22.
Artigo em Inglês | MEDLINE | ID: mdl-31757968

RESUMO

Magnetic anti-skyrmions are one of several chiral spin textures that are of great current interest both for their topological characteristics and potential spintronic applications. Anti-skyrmions were recently observed in the inverse tetragonal Heusler material Mn1.4Pt0.9Pd0.1Sn. Here we show, using Lorentz transmission electron microscopy, that anti-skyrmions are found over a wide range of temperature and magnetic fields in wedged lamellae formed from single crystals of Mn1.4Pt0.9Pd0.1Sn for thicknesses ranging up to ~250 nm. The temperature-field stability window of the anti-skyrmions varies little with thickness. Using micromagnetic simulations we show that this intrinsic stability of anti-skyrmions can be accounted for by the symmetry of the crystal lattice which is imposed on that of the Dzyaloshinskii-Moriya exchange interaction. These distinctive behaviors of anti-skyrmions makes them particularly attractive for spintronic applications.

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