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1.
J Eur Acad Dermatol Venereol ; 38(1): 112-123, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-37669776

RESUMO

BACKGROUND: While most cutaneous squamous cell carcinomas (cSCCs) are treatable, certain high-risk cSCCs, such as those in recessive dystrophic epidermolysis bullosa (RDEB) patients, are particularly aggressive. Owing to repeated wounding, inflammation and unproductive healing, RDEB patients have a 68% cumulative risk of developing life-threatening cSCCs by the age of 35, and a 70% risk of death by the age of 45. Despite aggressive treatment, cSCC represents the leading cause of premature mortality in these patients, highlighting an unmet clinical need. Increasing evidence points to a role of altered metabolism in the initiation and maintenance of cSCC, making metabolism a potential therapeutic target. OBJECTIVES: We sought to determine the feasibility of targeting tumour cell energetics as a strategy to selectively hinder the growth advantage of aggressive cSCC. METHODS: We evaluated the cell energetics profiles of RDEB-SCC cells by analysing available gene expression data against multiple gene signatures and single-gene targets linked to metabolic reprogramming. Additionally, we employed real-time metabolic profiling to measure glycolysis and respiration in these cells. Furthermore, we investigated the anti-neoplastic properties of the metformin against human and murine high-risk cSCCs in vitro and in vivo. RESULTS: Gene expression analyses highlighted a divergence in cell energetics profiles between RDEB-SCC and non-malignant RDEB keratinocytes, with tumour cells demonstrating enhanced respiration and glycolysis scores. Real-time metabolic profiling supported these data and additionally highlighted a metabolic plasticity of RDEB-SCC cells. Against this background, metformin exerted an anti-neoplastic potential by hampering both respiration and glycolysis, and by inhibiting proliferation in vitro. Metformin treatment in an analogous model of fast-growing murine cSCC resulted in delayed tumour onset and slower tumour growth, translating to a 29% increase in median overall survival. CONCLUSIONS: Our data indicate that metformin exerts anti-neoplastic properties in aggressive cSCCs that exhibit high-risk features by interfering with respiration and glycolytic processes.


Assuntos
Carcinoma de Células Escamosas , Epidermólise Bolhosa Distrófica , Epidermólise Bolhosa , Neoplasias Cutâneas , Humanos , Animais , Camundongos , Carcinoma de Células Escamosas/metabolismo , Neoplasias Cutâneas/genética , Fosforilação Oxidativa , Epidermólise Bolhosa/complicações , Epidermólise Bolhosa Distrófica/tratamento farmacológico , Epidermólise Bolhosa Distrófica/genética
2.
Sci Rep ; 13(1): 11783, 2023 07 21.
Artigo em Inglês | MEDLINE | ID: mdl-37479788

RESUMO

In this work, we present DrugSolver CavitomiX, a novel computational pipeline for drug repurposing and identifying ligands and inhibitors of target enzymes. The pipeline is based on cavity point clouds representing physico-chemical properties of the cavity induced solely by the protein. To test the pipeline's ability to identify inhibitors, we chose enzymes essential for SARS-CoV-2 replication as a test system. The active-site cavities of the viral enzymes main protease (Mpro) and papain-like protease (Plpro), as well as of the human transmembrane serine protease 2 (TMPRSS2), were selected as target cavities. Using active-site point-cloud comparisons, it was possible to identify two compounds-flufenamic acid and fusidic acid-which show strong inhibition of viral replication. The complexes from which fusidic acid and flufenamic acid were derived would not have been identified using classical sequence- and structure-based methods as they show very little structural (TM-score: 0.1 and 0.09, respectively) and very low sequence (~ 5%) identity to Mpro and TMPRSS2, respectively. Furthermore, a cavity-based off-target screening was performed using acetylcholinesterase (AChE) as an example. Using cavity comparisons, the human carboxylesterase was successfully identified, which is a described off-target for AChE inhibitors.


Assuntos
COVID-19 , Ácido Fusídico , Humanos , Ácido Fusídico/farmacologia , Acetilcolinesterase , Ácido Flufenâmico/farmacologia , SARS-CoV-2 , Peptídeo Hidrolases , Papaína
3.
Orthopadie (Heidelb) ; 51(11): 920-928, 2022 Nov.
Artigo em Alemão | MEDLINE | ID: mdl-36227361

RESUMO

In winter sports, skiers, snowboarders and ice hockey players have the highest risk of traumatic brain injuries (TBI). In skiing/snowboarding severe TBIs are of concern; in ice hockey, repetitive minor TBIs are frequent. The main causes of TBI in recreational skiing are collisions with trees; in professionals falls due to technical or tactical mistakes are the main causes. In ice hockey 10-15% of all injuries are due to a sports-related concussion (SRC), mostly caused by player-opponent contact. The pathomechanism in TBI is a combination of rotational and linear acceleration during head impact, which causes a diffuse axonal injury. Long-term complications such as neurodegenerative diseases and functional deficits are of relevance. Prevention by wearing helmets is effective, but less effective in TBI/SRC than in focal injuries.


Assuntos
Concussão Encefálica , Hóquei , Esqui , Humanos , Esqui/lesões , Dispositivos de Proteção da Cabeça , Concussão Encefálica/epidemiologia , Aceleração
4.
Sci Rep ; 12(1): 17783, 2022 10 22.
Artigo em Inglês | MEDLINE | ID: mdl-36273235

RESUMO

Covid-19 is the first digitally documented pandemic in history, presenting a unique opportunity to learn how to best deal with similar crises in the future. In this study we have carried out a model-based evaluation of the effectiveness of social distancing, using Austria and Slovenia as examples. Whereas the majority of comparable studies have postulated a negative relationship between the stringency of social distancing (reduction in social contacts) and the scale of the epidemic, our model has suggested a varying relationship, with turning points at which the system changes its predominant regime from 'less social distancing-more cumulative deaths and infections' to 'less social distancing-fewer cumulative deaths and infections'. This relationship was found to persist in scenarios with distinct seasonal variation in transmission and limited national intensive care capabilities. In such situations, relaxing social distancing during low transmission seasons (spring and summer) was found to relieve pressure from high transmission seasons (fall and winter) thus reducing the total number of infections and fatalities. Strategies that take into account this relationship could be particularly beneficial in situations where long-term containment is not feasible.


Assuntos
COVID-19 , Distanciamento Físico , Humanos , COVID-19/epidemiologia , COVID-19/prevenção & controle , Pandemias/prevenção & controle , Áustria/epidemiologia , Eslovênia/epidemiologia
7.
Sci Rep ; 10(1): 20042, 2020 11 18.
Artigo em Inglês | MEDLINE | ID: mdl-33208759

RESUMO

The exponential character of the recent Covid-19 outbreak requires a change in strategy from containment to mitigation. Meanwhile, most countries apply social distancing with the objective to keep the number of critical cases below the capabilities of the health care system. Due to the novelty and rapid spread of the virus, an a priori assessment of this strategy was not possible. In this study, we present a model-based systems analysis to assess the effectiveness of social distancing measures in terms of intensity and duration of application. Results show a super-linear scaling between intensity (percent contact reduction) and required duration of application to have an added value (a lower number of fatalities). This holds true for an effective reproduction of [Formula: see text] and is reverted for [Formula: see text]. If R is not reduced below 1, secondary effects of required long-term isolation are likely to unravel the added value of disease mitigation. If an extinction is not feasible, we recommend moderate social-distancing that is well balanced against capability limits of national health-care systems.


Assuntos
Número Básico de Reprodução/estatística & dados numéricos , COVID-19/epidemiologia , Modelos Estatísticos , Pandemias/estatística & dados numéricos , Distanciamento Físico , COVID-19/prevenção & controle , Demografia/estatística & dados numéricos , Humanos , Pandemias/prevenção & controle , Fatores de Tempo
9.
Ann Surg Oncol ; 27(5): 1700-1707, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-31873929

RESUMO

BACKGROUND: While "no tumour on ink" is an accepted margin width for R0 resection in primary surgery, it's unclear if it's oncologically safe after neoadjuvant chemotherapy (NAC). Only limited data demonstrate that surgery within new margins in cases of a pathological complete response (pCR) is safe. We therefore investigated the influence of different margins and pCR on local recurrence and survival rates after NAC. METHODS: We retrospectively analysed data of 406 women with invasive breast cancer, treated with NAC and breast-conserving therapy between 1994 and 2014 in two certified Austrian breast health centres. We compared R ≤ 1 mm, R > 1 mm and RX (pCR) for local recurrence-free survival (LRFS), disease-free survival (DFS) and overall survival (OS). RESULTS: After a median follow-up of 84.3 months, the 5-year LRFS (R ≤ 1 mm: 94.2%, R > 1 mm: 90.6%, RX: 95.0%; p = 0.940), the 5-year DFS (R ≤ 1 mm: 71.9%, R > 1 mm: 74.1%, RX: 87.2%; p = 0.245) and the 5-year OS (R ≤ 1 mm: 85.1%, R > 1 mm: 88.0%, RX: 96.4%; p = 0.236) did not differ significantly between narrow, wide, nor RX resections. Regarding DFS and OS, a negative nodal status reduced the hazard ratio significantly. CONCLUSION: There is no significant difference in LRFS, DFS and OS comparing close, wide or unknown margins after pCR. We suggest that resection in new margins after NAC is safe according to "no tumour on ink". Resection of the clipped area in cases of pCR is emphasized.


Assuntos
Neoplasias da Mama/terapia , Quimioterapia Adjuvante , Margens de Excisão , Mastectomia Segmentar , Recidiva Local de Neoplasia/diagnóstico , Adulto , Idoso , Idoso de 80 Anos ou mais , Áustria/epidemiologia , Neoplasias da Mama/mortalidade , Neoplasias da Mama/patologia , Terapia Combinada , Feminino , Humanos , Pessoa de Meia-Idade , Recidiva Local de Neoplasia/mortalidade , Estadiamento de Neoplasias , Cuidados Pré-Operatórios , Prognóstico , Estudos Retrospectivos , Análise de Sobrevida , Adulto Jovem
10.
Clin Hemorheol Microcirc ; 73(1): 195-201, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31561347

RESUMO

BACKGROUND: In cardiovascular research small pigs breeds like Göttingen® minipigs (GM) are established animal models, but systematic data about the micromorphology of the GM vasculature at different ages are scarce. OBJECTIVE: The study was aimed at gaining knowledge about the micromorphology of the femoral artery (FA) from German Landrace pigs (DL) and GM during the period of growth over a body weight range of 10-40 kg. METHODS: FA samples from DL aged two or three months were compared to GM ones, aged 18 or 40 months using transmitted light microscopy. RESULTS: All FA samples showed typical characteristics of muscular arteries. Growth was associated with increased vessel wall thickness. In the GM this resulted in a slight decrease of the luminal diameter (LD), while in the DL pigs, an increase of the LD and smooth muscle cell content (10%) with decreased elastic fiber content (10%) has been detected. In contrast, within the 22 months lasting growth period of the GM, the tunica media content of smooth muscle cells and elastic fibers remained stable. CONCLUSIONS: FA maturation strongly depends on the pig breed and age. It can be different from what is described in humans.


Assuntos
Artéria Femoral/crescimento & desenvolvimento , Túnica Média/crescimento & desenvolvimento , Animais , Suínos
11.
Sci Total Environ ; 689: 469-480, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31279194

RESUMO

Deep geological repository is considered the internationally accepted method for spent fuel (SF) disposal. In countries where salt, clay, tuff and granite are unavailable at geologically suitable area, other rock types may come into consideration. In Israel, carbonate rocks make up a significant portion of the surface and subsurface lithologies, thus, low permeability carbonates were evaluated as possible host rocks for a repository, and for an interim storage facility. Sorption and retardation capacity of SF components to low permeability carbonate rocks were evaluated using their chemical simulants. Strontium and Cs represent components that may leach during interim storage, while U and Ce (as a simulant for redox-active actinides) represent components that may leach under repository conditions. Rocks from the Upper Cretaceous Mount Scopus Group were sampled from boreholes at the Yamin Plateau, Israel. Single point batch experiments were conducted with synthetic rainwater spiked with tracers and interacted with five rock types of various particle sizes at 25 °C. Results were evaluated using the LeachXS™-ORCHESTRA geochemical speciation and data management program. Cerium removal was found to be related to the HCO3- concentration in solution, where Ce precipitated as Ce2(CO3)3·XH2O and as an amorphous carbonate phase. Removal of Cs and Sr was controlled by clays. No Sr co-precipitation as carbonate species was observed. Uranium was removed mainly by sorption onto solid organic matter, whereas clays had no significant role in U sorption. Iron-(hydr) oxides may have also played a role in U removal. Calculated partition coefficients for U, Cs, and Sr were in the order of 101-102 mL/g. Grain size had no significant effect on the retention capacity of the studied rocks due to similar effective surface area. The current study indicates that a repository or an interim storage facility within carbonate rocks, would provide only partial isolation of radionuclides from the environment, hence, additional engineered barriers may be required.

12.
Osteoporos Int ; 30(7): 1455-1464, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31011760

RESUMO

Persistence rates over 36 months with denosumab in patients diagnosed with osteoporosis in a real-world setting were examined, along with baseline patient characteristics predictive of persistence. This study represents the longest observational period with denosumab persistence and shows higher persistence rates when compared to bisphosphonates. INTRODUCTION: The study objective was to describe long-term persistence with denosumab among patients treated for osteoporosis in a real-world setting. We also sought to examine patient characteristics predictive of persistence. Lastly, this study attempted to place the results in context by conducting a literature review of published persistence data for denosumab. METHODS: This retrospective, non-interventional study analyzed 1158 patients from a specialty community private practice to assess patient persistence with denosumab in routine care. Persistence was defined as receiving seven denosumab injections, using an 8-week permissible gap, over 36 months. Non-persistent patients were further investigated retrospectively to identify reasons for discontinuation, when available. RESULTS: Demographic analysis showed a population of 1158 patients with mean age 68.4 years old and baseline T-score - 2.7; nearly half of which experienced a prior osteoporosis-related fracture. In a Kaplan-Meier survival analysis, 36-month persistence overall was 50.7%. Net persistence, as defined by receiving seven injections in the allowable time frame, was 64.2% of the cohort. In a multivariate analysis, prior vertebral fractures and recent osteoporosis therapy were associated with higher persistence; age greater than 75 years was associated with non-persistence. Reasons for discontinuation were available in 91.6% of non-persistent patients and categorized to include the ten most common explanations. CONCLUSION: This study to our knowledge represents the longest continuous observational period providing data on denosumab persistence in a real-world setting. The total persistence noted is quite robust when compared to bisphosphonates and is within the upper range of prior published studies of denosumab with shorter observation periods.


Assuntos
Conservadores da Densidade Óssea/administração & dosagem , Denosumab/administração & dosagem , Adesão à Medicação/estatística & dados numéricos , Osteoporose/tratamento farmacológico , Idoso , Conservadores da Densidade Óssea/uso terapêutico , Denosumab/uso terapêutico , Esquema de Medicação , Feminino , Humanos , Injeções Subcutâneas , Estimativa de Kaplan-Meier , Masculino , Pessoa de Meia-Idade , Osteoporose Pós-Menopausa/tratamento farmacológico , Fraturas por Osteoporose/prevenção & controle , Estudos Retrospectivos , Estados Unidos
13.
Phys Rev E ; 99(2-1): 022108, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30934340

RESUMO

The statistical mechanics of a cloud of particles interacting via their gravitational potentials encounters some issues when the Boltzmann-Gibbs statistics is applied. In this work, we consider the alternative statistical framework of Tsallis and analyze the statistical and thermodynamical implications for a self-gravitating gas, obtaining analytical and convergent expressions for the equation of state and specific heat in the ensembles of constant temperature and constant energy. Although our results are comparable in both ensembles, it turns out that only in the ensemble of constant temperature do the thermodynamic quantities depend explicitly on the Tsallis parameter, indicating that the question of ensemble equivalence for Tsallis statistics must be further reviewed.

14.
Clin Hemorheol Microcirc ; 69(1-2): 317-326, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29630534

RESUMO

Laser tissue soldering (LTS) based on indocyanine green (ICG)-mediated heat-denaturation of proteins might be a promising alternative technique for micro-suturing, but up to now the problem of too weak shear strength of the solder welds in comparison to sutures is not solved. Earlier reports gave promising results showing that solder supported by carrier materials can enhance the cohesive strength of the liquid solder. In these studies, the solder was applied to the carriers by dip coating. Higher reliability of the connection between the solder and the carrier material is expected when the solder is bound covalently to the carrier material. In the present study a poly(ether imide) (PEI) membrane served as carrier material and ICG-supplemented albumin as solder substrate. The latter was covalently coupled to the carrier membrane under physiological conditions to prevent structural protein changes. As laser source a diode continuous-wave laser emitting at 808 nm with intensities between 250 mW and 1500 mW was utilized. The albumin functionalized carrier membrane was placed onto the tunica media of explanted pig thoracic aortae forming an overlapping area of approximately 0.5×0.5 cm2. All tests were performed in a dry state to prevent laser light absorption by water. Infrared spectroscopy, spectro-photometrical determination of the secondary and primary amine groups after acid orange II staining, contact angle measurements, and atomic force microscopy proved the successful functionalization of the PEI membrane with albumin. A laser power of 450 mW LTS could generate a membrane-blood vessel connection which was characterized by a shear strength of 0.08±0.002 MPa, corresponding to 15% of the tensile strength of the native blood vessel. Theoretically, an overlapping zone of 4.1 mm around the entire circumference of the blood vessel could have provided shear strength of the PEI membrane-blood vessel compound identical to the tensile strength of the native blood vessel. These in-vitro results confirmed the beneficial effects of solder reinforcement by carrier membranes, and suggest LTS with covalently bound solders on PEI substrates for further studies in animal models.


Assuntos
Albuminas/metabolismo , Vasos Sanguíneos/metabolismo , Terapia a Laser/métodos
15.
Ophthalmologe ; 115(6): 509-513, 2018 Jun.
Artigo em Alemão | MEDLINE | ID: mdl-28741163

RESUMO

A 23-year-old male patient presented with reduced visual acuity of the right eye, along with halos and starbursts in both eyes after a one-stage tissue-saving treatment, a combination of myopic photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK). After an extensive preliminary examination and analysis of the examination results, aberration-free LASIK retreatment for reducing astigmatism and enlargement of the optical zone with an excimer laser was performed on the right eye. The visual performance and the subjectively perceived optical quality improved postoperatively.


Assuntos
Ceratomileuse Assistida por Excimer Laser In Situ , Lasers de Excimer , Ceratectomia Fotorrefrativa , Córnea , Humanos , Masculino , Refração Ocular , Retratamento , Resultado do Tratamento , Acuidade Visual , Adulto Jovem
16.
Mol Biol Rep ; 43(4): 253-68, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-26896938

RESUMO

Chianina and Maremmana breeds play an important role in the Italian cattle meat market. The Chianina breed is an ancient breed principally raised for draught. Now this breed is the worldwide recognized producer of top quality beef, tasteful and tender, specifically the famous "Florentine steak". The Maremmana characterized by a massive skeletal structure, is a rustic cattle breed selected for adaptability to the marshy land of the Maremma region. We used a high throughput mRNA sequencing to analyze gene expression in muscle tissues of two Italian cattle breeds, Maremmana (MM) and Chianina (CN) with different selection history. We aim to examine the specific genetic contribution of each breed to meat production and quality, comparing the skeletal muscle tissue from Maremmana and Chianina. Most of the differentially expressed genes were grouped in the Glycolysis/Gluconeogenesis pathways. The rate and the extent of post-mortem energy metabolism have a critical effect on the conversion of muscle to meat. Furthermore, we aim at discovering the differences in nucleotide variation between the two breeds which might be attributable to the different history of selection/divergence. In this work we could emphasize the involvement of pathways of post-mortem energy metabolism. Moreover, we detected a collection of coding SNPs which could offer new genomic resources to improve phenotypic selection in livestock breeding program.


Assuntos
Gluconeogênese/genética , Glicólise/genética , Músculo Esquelético/metabolismo , Polimorfismo de Nucleotídeo Único , Transcriptoma , Animais , Cruzamento , Bovinos , Itália , Masculino , Carne Vermelha
17.
Anim Genet ; 47(3): 273-87, 2016 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-26857751

RESUMO

Our objectives for this study were to understand the biological basis of meat tenderness and to provide an overview of the gene expression profiles related to meat quality as a tool for selection. Through deep mRNA sequencing, we analyzed gene expression in muscle tissues of two Italian cattle breeds: Maremmana and Chianina. We uncovered several differentially expressed genes that encode for proteins belonging to a family of tripartite motif proteins, which are involved in growth, cell differentiation and apoptosis, such as TRIM45, or play an essential role in regulating skeletal muscle differentiation and the regeneration of adult skeletal muscle, such as TRIM32. Other differentially expressed genes (SCN2B, SLC9A7 and KCNK3) emphasize the involvement of potassium-sodium pumps in tender meat. By mapping splice junctions in RNA-Seq reads, we found significant differences in gene isoform expression levels. The PRKAG3 gene, which is involved in the regulation of energy metabolism, showed four isoforms that were differentially expressed. This distinct pattern of PRKAG3 gene expression could indicate impaired glycogen storage in skeletal muscle, and consequently, this gene very likely has a role in the tenderization process. Furthermore, with this deep RNA-sequencing, we captured a high number of expressed SNPs, for example, we found 1462 homozygous SNPs showing the alternative allele with a 100% frequency when comparing tender and tough meat. SNPs were then classified into categories by their position and also by their effect on gene coding (174 non-synonymous polymorphisms) based on the available UMD_3.1 annotations.


Assuntos
Cruzamento , Bovinos/genética , Carne/análise , Proteínas Musculares/genética , Transcriptoma , Proteínas Quinases Ativadas por AMP/genética , Alelos , Processamento Alternativo , Animais , Sequenciamento de Nucleotídeos em Larga Escala , Itália , Músculo Esquelético/fisiologia , Polimorfismo de Nucleotídeo Único , Regiões Promotoras Genéticas , Análise de Sequência de RNA
18.
Mol Oral Microbiol ; 30(6): 451-73, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-25953484

RESUMO

Tannerella forsythia is the only 'red-complex' bacterium covered by an S-layer, which has been shown to affect virulence. Here, outer membrane vesicles (OMVs) enriched with putative glycoproteins are described as a new addition to the virulence repertoire of T. forsythia. Investigations of this bacterium are hampered by its fastidious growth requirements and the recently discovered mismatch of the available genome sequence (92A2 = ATCC BAA-2717) and the widely used T. forsythia strain (ATCC 43037). T. forsythia was grown anaerobically in serum-free medium and biogenesis of OMVs was analyzed by electron and atomic force microscopy. This revealed OMVs with a mean diameter of ~100 nm budding off from the outer membrane while retaining the S-layer. An LC-ESI-TOF/TOF proteomic analysis of OMVs from three independent biological replicates identified 175 proteins. Of these, 14 exhibited a C-terminal outer membrane translocation signal that directs them to the cell/vesicle surface, 61 and 53 were localized to the outer membrane and periplasm, respectively, 22 were predicted to be extracellular, and 39 to originate from the cytoplasm. Eighty proteins contained the Bacteroidales O-glycosylation motif, 18 of which were confirmed as glycoproteins. Release of pro-inflammatory mediators from the human monocytic cell line U937 and periodontal ligament fibroblasts upon stimulation with OMVs followed a concentration-dependent increase that was more pronounced in the presence of soluble CD14 in conditioned media. The inflammatory response was significantly higher than that caused by whole T. forsythia cells. Our study represents the first characterization of T. forsythia OMVs, their proteomic composition and immunogenic potential.


Assuntos
Proteínas da Membrana Bacteriana Externa/análise , Bacteroidetes/patogenicidade , Bacteroidetes/ultraestrutura , Estruturas da Membrana Celular/química , Estruturas da Membrana Celular/fisiologia , Glicoproteínas/análise , Proteínas da Membrana Bacteriana Externa/química , Proteínas da Membrana Bacteriana Externa/genética , Bacteroidetes/crescimento & desenvolvimento , Bacteroidetes/imunologia , Estruturas da Membrana Celular/ultraestrutura , Células Cultivadas , Meios de Cultivo Condicionados/química , Glicosilação , Humanos , Receptores de Lipopolissacarídeos/biossíntese , Glicoproteínas de Membrana/análise , Biogênese de Organelas , Periplasma/química , Proteômica , Células U937 , Virulência
19.
J Phys Condens Matter ; 25(43): 436002, 2013 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-24097342

RESUMO

We present a theoretical investigation of the entropy changes upon the application of an external field leading to the magneto-caloric effect (MCE). The case of localized magnetic moments is treated within the Weiss molecular field model, but special emphasis is given to cases of itinerant electron magnetism. These are described within the Landau theory of phase transitions and the temperature dependence is included via spin fluctuations. Since the parameters of the Landau expansion can be calculated from first-principles calculations of the electronic and magnetic structure, an immediate connection to the electronic band structure and its properties becomes possible. We study ordinary ferromagnets, including magneto-volume coupling and itinerant electron metamagnets, where in a small external field range large changes of the magnetic moments occur. We find that such metamagnetic systems are the most promising candidates for a large MCE in itinerant electron systems. We apply our expressions to several transition metals and their alloys, as well as to the metamagnets YCo2 and Fe2P, and find reasonable agreement with available experimental data.

20.
J Phys Condens Matter ; 25(18): 186002, 2013 May 08.
Artigo em Inglês | MEDLINE | ID: mdl-23587739

RESUMO

We use the model of covalent magnetism and its application to magnetic insulators applied to the case of insulating carbon doped BaTiO3. Since the usual Stoner mechanism is not applicable we study the possibility of the formation of magnetic order based on a mechanism favoring singly occupied orbitals. On the basis of our model parameters we formulate a criterion similar to the Stoner criterion but also valid for insulators. We describe the model of covalent magnetism using a molecular orbital picture and determine the occupation numbers for spin-up and spin-down states. Our model allows a simulation of the results of our ab initio calculations for E(ℳ) which are found to be in very good agreement.


Assuntos
Compostos de Bário/química , Carbono/química , Elétrons , Magnetismo , Marcadores de Spin , Titânio/química , Elementos Isolantes , Modelos Teóricos , Teoria Quântica
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