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1.
Bull Exp Biol Med ; 176(3): 359-362, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38342810

RESUMO

Ion channels activity is regulated through soluble guanylate cyclase (sGC) and adenylate cyclase (AC) pathways, while phosphodiesterases (PDE) control the intracellular levels of cAMP and cGMP. Here we applied RNA transcriptome sequencing to study changes in the gene expression of the sGC, AC, and PDE isoforms in isolated rat ventricular cardiomyocytes under conditions of microgravity and hypergravity. Our results demonstrate that microgravity reduces the expression of sGC isoform genes, while hypergravity increases their expression. For a subset of AC isoforms, gene expression either increased or decreased under both microgravity and hypergravity conditions. The expression of genes encoding 10 PDE isoforms decreased under microgravity, but increased under hypergravity. However, under both microgravity and hypergravity, the gene expression increased for 7 PDE isoforms and decreased for 3 PDE isoforms. Overall, our findings indicate specific gravity-dependent changes in the expression of genes of isoforms associated with the studied enzymes.


Assuntos
Hipergravidade , Ausência de Peso , Ratos , Animais , Diester Fosfórico Hidrolases/metabolismo , Guanilil Ciclase Solúvel , Adenilil Ciclases/genética , Miócitos Cardíacos/metabolismo , Isoformas de Proteínas/genética , Guanilato Ciclase/genética , Guanilato Ciclase/metabolismo , GMP Cíclico/metabolismo
2.
Dokl Biochem Biophys ; 512(1): 251-255, 2023 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-38093125

RESUMO

The mechanoelectrical feedback in the heart is based on the work of mechanically gated (MGCs) and mechanosensitive (MSCs) channels. Since microgravity alters the heart's morphological and physiological properties, we hypothesized that the expression of both MGCs and MSCs would be affected. We employed RNA transcriptome sequencing to investigate changes in the gene transcript levels of MGCs and MSCs in isolated rat ventricular cardiomyocytes under control conditions and in a simulated microgravity environment. For the first time, our findings demonstrated that simulated microgravity induces alterations in the gene transcript levels of specific MGCs, such as TRPM7, TRPV2, TRPP1, TRPP2, Piezo1, TMEM63A, TMEM36B, and known MSCs, including K2P2.1, K2P3.1, Kir6.1, Kir6.2, NaV1.5, CaV1.2, KV7.1. However, other voltage-gated channels and channels lacking a voltage sensor remained unaffected. These findings suggest that the altered expression of MGCs and MSCs could lead to changes in the net currents across the membrane, ultimately impacting the heart's function.


Assuntos
Miócitos Cardíacos , Ausência de Peso , Ratos , Animais , Canais Iônicos/genética , Canais Iônicos/metabolismo
3.
Bull Exp Biol Med ; 175(6): 730-733, 2023 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-37979024

RESUMO

Since hypergravity changes the morphological and physiological properties of the heart, it was assumed that the expression of ion channels that respond to cell stretching or compressing, mechanically gated channels (MGC) and mechanosensitive channels (MSC), would be affected. Using RNA transcriptome sequencing, the change in the number of transcripts for MGC and MSC genes was studied in isolated rat ventricular cardiomyocytes under 4g hypergravity for 5 days. It was shown for the first time that hypergravity induces changes in the number of transcripts of MGC genes: an increase for TRPC1, TRPC3, TRPM7, TRPP1 (PKD1), TRPP2 (PKD2), TMEM63A, TMEM63B, but a decrease for TRPV2, Piezo1, Piezo2. The number of MSC gene transcripts increases: TREK-1, Kir6.2, Nav1.5, Cav1.2, Cav1.3, Kv7.1, and Kv1.2. This potentially leads to an increase in the expression of MGC and MSC proteins leading to an increase in the net current and, as a result, pathological changes in the heart function.


Assuntos
Hipergravidade , Miócitos Cardíacos , Ratos , Animais , RNA , Sequência de Bases
4.
Bull Exp Biol Med ; 175(5): 633-637, 2023 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-37870659

RESUMO

Parameters of non-spatial and spatial memory were evaluated in sexually mature offspring of outbred rats (females and males F0) consuming a 10% ethanol solution for 30 weeks before mating. We found a significant increase in the recognition index in F1 males and its decrease in F1 females in the novel object recognition test. During the first days of the experiment in T-maze, a decrease in spatial memory was revealed in F1 males, which remained at the trend level until the end of testing; no significant deviations were detected in F1 females. Memory impairment in F1 females was accompanied by a decrease in BDNF level in the hippocampus, but not in the prefrontal cortex. Thus, ethanol consumption by F0 rats before mating led to impairment of long-term working memory only in female F1 offspring.


Assuntos
Memória de Curto Prazo , Reprodução , Masculino , Ratos , Feminino , Animais , Comunicação Celular , Transtornos da Memória/induzido quimicamente , Etanol/toxicidade , Hipocampo
5.
Bull Exp Biol Med ; 172(4): 410-414, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-35175469

RESUMO

Acute-on-chronic liver failure (ACLF) of varying grades was assessed in 110 patients with alcoholic liver cirrhosis using the on-line CLIF-C ACLF Calculator ( www.efclif.com/scientific-activity/score-calculators/clif-c-aclf ); fragments of cytokeratin-18, TNFα, IL-1ß, IL-4, IL-6, and IL-8 were also assayed. As ACLF progressed from grade 0 to grade 3, the levels of cytokeratin-18 fragments, IL-6, and IL-8 significantly increased, while IL-4 decreased. TNFα peaked in ACLF grade 1, but decreased in grades 2 and 3. IL-1ß did not depend on the ACLF grade. Thus, hepatic damage and immune dysfunction are implicated in the progression of ACLF.


Assuntos
Insuficiência Hepática Crônica Agudizada , Apoptose , Humanos , Cirrose Hepática , Cirrose Hepática Alcoólica
6.
Bull Exp Biol Med ; 171(3): 322-326, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-34297284

RESUMO

We examined 74 patients with acute decompensation of alcoholic liver cirrhosis: 34 (45.9%) with bacterial infection (group 1) and 40 (54.1%) without bacterial infection (group 2). The degree and index of acute-on-chronic liver failure (ACLF) were determined using an on-line CLIF-C ACLF Calculator and the levels of cytokeratin-18 fragments, TNFα, IL-1ß, IL-4, IL-6, and IL-8. In group 1, AST, cytokeratin-18, TNFα, IL-1ß, IL-6, degree and score of ACLF were significantly higher than in group 2. ACLF developed in 18 (52.9%) patients in group 1 and in 11 (27.5%) (p<0.05) patients in group 2. Within 1 month, 10 (29.4%) patients of group 1 and 2 (5%) patients of group 2 died (p<0.05). Patients with bacterial infection showed a more severe course of alcoholic liver cirrhosis and ACLF than those without bacterial infection.


Assuntos
Insuficiência Hepática Crônica Agudizada/microbiologia , Infecções Bacterianas/microbiologia , Cirrose Hepática Alcoólica/microbiologia , Insuficiência Hepática Crônica Agudizada/sangue , Insuficiência Hepática Crônica Agudizada/mortalidade , Insuficiência Hepática Crônica Agudizada/patologia , Adulto , Aspartato Aminotransferases/sangue , Infecções Bacterianas/sangue , Infecções Bacterianas/mortalidade , Infecções Bacterianas/patologia , Biomarcadores/sangue , Estudos de Casos e Controles , Feminino , Humanos , Interleucina-1beta/sangue , Interleucina-4/sangue , Interleucina-6/sangue , Interleucina-8/sangue , Queratina-18/sangue , Fígado/metabolismo , Fígado/patologia , Cirrose Hepática Alcoólica/sangue , Cirrose Hepática Alcoólica/mortalidade , Cirrose Hepática Alcoólica/patologia , Masculino , Pessoa de Meia-Idade , Prognóstico , Índice de Gravidade de Doença , Análise de Sobrevida , Fator de Necrose Tumoral alfa/sangue
7.
Bull Exp Biol Med ; 171(1): 141-149, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-34050834

RESUMO

Mesenchymal stem cells from the adipose tissue (AT MSC) and the bone marrow (BM MSC) stimulated migration of melanoma B16 cells, while mammary adenocarcinoma Ca755 cells stimulated migration of mesenchymal stem cells. Mesenchymal stem cells retained these properties at late terms after γ-irradiation in vitro. Tumors that developed after injection of Ca755 cells alone and in combinations with BM MSC or AT MSC had similar histological structure corresponding to breast adenocarcinoma. Only AT MSC stimulated tumor growth, which was determined by more intensive secretion of factors stimulating proliferation of tumor cells, including chemokine CCL2. The use of AT MSC in regenerative medicine requires careful monitoring of the absence of tumors in patients.


Assuntos
Adenocarcinoma , Células-Tronco Mesenquimais , Animais , Células da Medula Óssea , Proliferação de Células , Células Cultivadas , Humanos , Camundongos
8.
Ter Arkh ; 93(1): 15-19, 2021 Jan 10.
Artigo em Russo | MEDLINE | ID: mdl-33720620

RESUMO

AIM: The aim of the study was to evaluate hepatocellular damage and immune inflammation in various forms of alcoholic liver disease (ALD). MATERIALS AND METHODS: 104 patients with ALD were examined: 15 (14.4%) with liver steatosis (LS), 19 (18.3%) with steatohepatitis and 70 (67.3%) with liver cirrhosis (LC); men 50 (48.1%), women 54 (51.9%); age 45.78.4 years. Traditional clinical, laboratory, instrumental studies were performed, the levels of fragments of cytokeratin-18 (FCK-18), cytokines IL-1, TNF-, IL-4, IL-6, IL-8 were determined by ELISA. The control group consisted of 39 healthy individuals: men 20 (51.2%), women 19 (48.7%), age 48.58.3 years. RESULTS: In LS, an increase in the level of FCK-18 was noted with normal aminotransferase activity, the content of TNF-, IL-6, IL-1, IL-8 increased and the level of IL-4 decreased compared to those in healthy individuals. In steatohepatitis, a triple increase in aminotransferases and FCK-18 was observed compared with LS, as well as an increase in the level of inflammatory mediators, to a greater extent IL-6, to a lesser extent IL-8, TNF-, a decrease in IL-4, IL-1 remained at the same level. In LC, there was a further increase in FCK-18, significantly more pronounced than an increase in AST, and the increase in cytokines continued to the same extent, the levels of IL-6 and IL-8, to a lesser extent IL-1 and TNF-, and the level of IL-4. CONCLUSION: With the progression of ALD from LS to steatohepatitis, hepatic cell damage was carried out by equally pronounced processes of hepatocyte necrosis and apoptosis, with the development of cirrhosis of the liver, parenchyma damage occurred mainly due to hepatocyte apoptosis. The immuno-inflammatory process progressively increased from the stage of LS to LC with IL-6 and IL-8 undergoing the greatest dynamics. FCK-18 can serve as a non-invasive marker of hepatic cell damage, and IL-6 and IL-8 markers of immune inflammation in ALD.


Assuntos
Carcinoma Hepatocelular , Hepatopatias Alcoólicas , Neoplasias Hepáticas , Hepatopatia Gordurosa não Alcoólica , Feminino , Humanos , Inflamação , Fígado/patologia , Cirrose Hepática/patologia , Hepatopatias Alcoólicas/patologia , Masculino , Pessoa de Meia-Idade , Hepatopatia Gordurosa não Alcoólica/patologia
9.
Bull Exp Biol Med ; 167(1): 145-149, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-31183649

RESUMO

We studied the effect of mesenchymal stem cells from the bone marrow and adipose tissue on the growth rate of melanoma B16 and mammary adenocarcinoma Ca755 tumors after their co-administration with tumor cells to syngeneic mice. Stimulation of tumor growth and formation of melanoma metastases in the lungs was found under the influence of adipose tissue-derived, but not bone marrow-derived stem cells. At delayed terms after irradiation in sublethal doses, the adipose tissue-derived mesenchymal stem cells also stimulated the tumor growth. Stimulation of the tumor growth by adipose tissue-derived mesenchymal stem cells was caused by factors secreted by these cells. Transplantation of mesenchymal stem cells to humans is possible only after accurate exclusion of malignant tumors.


Assuntos
Tecido Adiposo/citologia , Células da Medula Óssea/citologia , Neoplasias da Mama/patologia , Melanoma/patologia , Células-Tronco Mesenquimais/citologia , Animais , Proliferação de Células/fisiologia , Células Cultivadas , Feminino , Masculino , Melanoma Experimental , Transplante de Células-Tronco Mesenquimais , Células-Tronco Mesenquimais/fisiologia , Camundongos , Camundongos Endogâmicos C57BL
10.
Bull Exp Biol Med ; 162(4): 488-495, 2017 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-28243915

RESUMO

Biocompatibility of film and fibrous scaffolds from polylactide-based polymers and the relationship between their architecture and the functional characteristics of mesenchymal stem cells were studied. Cell culturing on polylactide-based film and fibrous matrixes did not deteriorate cell morphology and their proliferation and differentiation capacities. The rate of cell proliferation and penetration in microporous 3D matrices with the same porosity parameters and pore size depended on their spatial organization. The above materials can be used as scaffolds for mesenchymal stem cells for creation of tissue engineering implants. The scaffold size and structure should be determined by the defects in the organs in which the regeneration processes have to be stimulated.


Assuntos
Materiais Biocompatíveis/farmacologia , Células da Medula Óssea/efeitos dos fármacos , Células-Tronco Mesenquimais/efeitos dos fármacos , Poliésteres/farmacologia , Alicerces Teciduais , Adipócitos/citologia , Adipócitos/efeitos dos fármacos , Adipócitos/fisiologia , Animais , Materiais Biocompatíveis/química , Células da Medula Óssea/citologia , Células da Medula Óssea/fisiologia , Diferenciação Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Condrócitos/citologia , Condrócitos/efeitos dos fármacos , Condrócitos/fisiologia , Humanos , Teste de Materiais , Células-Tronco Mesenquimais/citologia , Células-Tronco Mesenquimais/fisiologia , Camundongos , Camundongos Endogâmicos C57BL , Osteoblastos/citologia , Osteoblastos/efeitos dos fármacos , Osteoblastos/fisiologia , Poliésteres/química , Porosidade , Cultura Primária de Células , Medicina Regenerativa , Engenharia Tecidual
11.
Tsitologiia ; 59(4): 271-8, 2017.
Artigo em Inglês, Russo | MEDLINE | ID: mdl-30188090

RESUMO

Mesenchymal stem cells (MSCs) are present in almost all organs and tissues of the organism. It is believed, that MSCs could be transformed into cancer stem cells spontaneously or under influence of genotoxic factors and trigger the growth of tumors. The aim of this work was to study the possibility of malignant transformation of cultured MSCs from murine bone marrow (MSCs-BM) after g-irradiation in vitro and characterize of biochemical and histological features of the tumors that developed after transplantation of MSCs-BM into syngeneic mice. Tumors were observed in 3­4 months after MSCs-BM transplantation. After administration of MSCs-BM irradiated at a dose of 1 Gy, tumors were seen in 2 of 5 mice. After transplantation of MSCs-BM irradiated at a dose of 6 Gy, tumors were found in all 5 of 5 mice. In the case of control MSCs-BM, only one tumor appeared in 6 months after transplantation. The telomerase activity was two times higher in the tumor developed from 6 Gy irradiated MSCs-BM than from 1 Gy irradiated MSCs-BM. The tumors developed from control and irradiated MSCs-BM were classified as multicomponent mesenchymomas («mixture of sarcomas¼). Histological examination showed that tumors contained tissue areas of different histogenesis. Thus, MSCs-BM g-irradiated at doses of 1 and 6 Gy and, much less frequently, control MSCs-BM can transform into tumor cells and induce development of multicomponent mesenchymomas.


Assuntos
Raios gama/efeitos adversos , Transplante de Células-Tronco Mesenquimais , Células-Tronco Mesenquimais , Neoplasias Experimentais , Neoplasias Induzidas por Radiação , Animais , Células-Tronco Mesenquimais/metabolismo , Células-Tronco Mesenquimais/patologia , Camundongos , Neoplasias Experimentais/metabolismo , Neoplasias Experimentais/patologia , Neoplasias Induzidas por Radiação/metabolismo , Neoplasias Induzidas por Radiação/patologia , Transplante Isogênico
12.
J Phys Chem A ; 120(45): 8983-8997, 2016 Nov 17.
Artigo em Inglês | MEDLINE | ID: mdl-27762556

RESUMO

Nine-dimensional potential energy surface (PES) and dipole moment surface (DMS) of the germane molecule are constructed using extended ab initio CCSD(T) calculations at 19 882 points. PES analytical representation is determined as an expansion in nonlinear symmetry adapted products of orthogonal and internal coordinates involving 340 parameters up to eighth order. Minor empirical refinement of the equilibrium geometry and of four quadratic parameters of the PES computed at the CCSD(T)/aug-cc-pVQZ-DK level of the theory yielded the accuracy below 1 cm-1 for all experimentally known vibrational band centers of five stable isotopologues of 70GeH4, 72GeH4, 73GeH4, 74GeH4, and 76GeH4 up to 8300 cm-1. The optimized equilibrium bond re = 1.517 594 Šis very close to best ab initio values. Rotational energies up to J = 15 are calculated using potential expansion in normal coordinate tensors with maximum errors of 0.004 and 0.0006 cm-1 for 74GeH4 and 76GeH4. The DMS analytical representation is determined through an expansion in symmetry-adapted products of internal nonlinear coordinates involving 967 parameters up to the sixth order. Vibration-rotation line intensities of five stable germane isotopologues were calculated from purely ab initio DMS using nuclear motion variational calculations with a full account of the tetrahedral symmetry of the molecules. For the first time a good overall agreement of main absorption features with experimental rotationally resolved Pacific Northwest National Laboratory spectra was achieved in the entire range of 700-5300 cm-1. It was found that very accurate description of state-dependent isotopic shifts is mandatory to correctly describe complex patterns of observed spectra at natural isotopic abundance resulting from the superposition of five stable isotopologues. The data obtained in this work will be made available through the TheoReTS information system.

13.
Bull Exp Biol Med ; 162(1): 120-126, 2016 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-27882461

RESUMO

We analyzed viability of mesenchymal stem cells seeded by static and dynamic methods to highly porous fibrous 3D poly-L-lactide scaffolds with similar physical and chemical properties, but different spatial organization modified with collagen. Standard collagen coating promoted protein adsorption on the scaffold surface and improved adhesive properties of 100 µ-thick scaffolds. Modification of 600-µ scaffolds with collagen under pressure increased proliferative activity of mesenchymal stem cells seeded under static and dynamic (delivery of 100,000 cells in 10 ml medium in a perfusion system at a rate of 1 ml/min) conditions by 47 and 648%, respectively (measured after 120-h culturing by MTT test). Dynamic conditions provide more uniform distribution of collagen on scaffold fibers and promote cell penetration into 3D poly-L-lactide scaffolds with thickness >600 µ.


Assuntos
Células da Medula Óssea/efeitos dos fármacos , Materiais Revestidos Biocompatíveis/farmacologia , Células-Tronco Mesenquimais/efeitos dos fármacos , Poliésteres/farmacologia , Alicerces Teciduais , Animais , Células da Medula Óssea/citologia , Células da Medula Óssea/fisiologia , Adesão Celular/efeitos dos fármacos , Técnicas de Cultura de Células , Movimento Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Materiais Revestidos Biocompatíveis/química , Colágeno/química , Colágeno/farmacologia , Fluoresceínas , Corantes Fluorescentes , Células-Tronco Mesenquimais/citologia , Células-Tronco Mesenquimais/fisiologia , Camundongos , Camundongos Endogâmicos C57BL , Poliésteres/química , Porosidade , Cultura Primária de Células , Propídio , Reologia , Engenharia Tecidual
14.
Radiats Biol Radioecol ; 56(1): 35-43, 2016.
Artigo em Russo | MEDLINE | ID: mdl-27245003

RESUMO

Mesenchymal stem cells (MSC) exist in the brain in addition to the neural stem cells (NSC). The aim of this work was to investigate the sensitivity of mouse brain MSC (MSC(BR)) to sublethal doses of γ-radiation in comparison with the sensitivity of bone marrow MSC (MSC(BM)) and NSC and to study the effects of γ-irradiation at low doses on these cells. Cells were exposed to γ-radiation (137Cs) at the doses of 10 to 200 mGy at a dose rate of 10 mGy/min; higher doses were achieved at the dose rates of 200 and 500 mGy/min (60Co). The survival of cells was assessed by counting living cells after staining with trypan blue in the Goryaev's chamber or using the MTT test for NSC growing as neurospheres. SP fraction was measured using flow cytometry after incubation with rhodamine-123. Exposure to the doses in the range of 10 to 500 mGy stimulated cell proliferation. The maximum decrease in the cells number was seen on the seventh day after irradiation and it was practically the same for the MSC(BR) and MSC(BM). NCS were more radiosensitive than MSC. Exposure to the doses of 100 to 500 mGy stimulated cells proliferation of all SCs except of MSC(BM). It was shown that the size of SP fraction of MSC(BR) was diminished after γ-irradiation at low doses. Thus, the stimulation of cell proliferation after γ-irradiation at low doses is accompanied by the redistribution of distinct cell subpopulations: the decrease in the SP fraction and the increase in the general population of cells were observed.


Assuntos
Proliferação de Células/efeitos da radiação , Raios gama/efeitos adversos , Células-Tronco Mesenquimais/efeitos da radiação , Células-Tronco Neurais/efeitos da radiação , Animais , Encéfalo/efeitos da radiação , Diferenciação Celular/efeitos da radiação , Citometria de Fluxo , Camundongos , Doses de Radiação
15.
Eksp Klin Gastroenterol ; (11): 34-7, 2015.
Artigo em Russo | MEDLINE | ID: mdl-27214985

RESUMO

UNLABELLED: The aim of the study was to determine the incidence of cirrhotic cardiomyopathy (CCMP), features of its recognition and clinical manifestations. MATERIALS AND METHODS: The study included 102 patients with alcoholic and viral liver cirrhosis (LC) without cardiovascular history, without viremia and signs of acute alcoholic hepatitis. Echocardiography, electrocardiography (ECG) and brain natriuretic hormone (proBNP) level were investigated in all patients. RESULTS: CCMP signs were detected in 65 (63.7%) of the 102 patients examined. All patients showed signs of electrophysiological myocardial abnormalities in ECG, signs of myocardial injury and the presence of heart failure in echocardiography, increase in proBNP. Interval QT length (0.4689 ± 0.012 s.) was significantly (p = 0.0461) higher than that of the control group. Violation of diastolic relaxation of the left ventricle was detected in 36 (55.6%) patients. The average level of proBNP was 540.85 ± 236.43 pg/ml, significantly different from the level of proBNP in healthy individuals--89.45 ± 26.43 pg/ml. The incidence of CCMP increased progressively with the severity of the Child-Pugh class and was 42.4% in patients of A class, 84.6% (p = 0.0132) in patients of B Class and 100% in patients of C class (p = 0.0219). The length of the QT interval, the proBNP level and frequency of diastolic dysfunction increased with increasing of liver cirrhosis severity. CONCLUSION: The frequency of detection of cirrhotic cardiomyopathy was 63.7%. More pronounced CCMP signs were observed in alcoholic liver cirrhosis than in viral. The frequency of detection and severity of cirrhotic cardiomyopathy progres sively increased with the severity of liver cirrhosis. Brain natriuretic peptide was the most sensitive indicator of myocardial damage in liver cirrhosis irrespective of its etiology.


Assuntos
Cardiomiopatias , Cirrose Hepática , Peptídeo Natriurético Encefálico/sangue , Adulto , Cardiomiopatias/sangue , Cardiomiopatias/etiologia , Cardiomiopatias/patologia , Cardiomiopatias/fisiopatologia , Feminino , Humanos , Cirrose Hepática/sangue , Cirrose Hepática/complicações , Cirrose Hepática/patologia , Cirrose Hepática/fisiopatologia , Masculino , Pessoa de Meia-Idade
16.
Phys Rev Lett ; 112(14): 147402, 2014 Apr 11.
Artigo em Inglês | MEDLINE | ID: mdl-24766011

RESUMO

The excitations of a two-dimensional electron gas in quantum wells with intermediate carrier density (ne∼1011 cm-2), i.e., between the exciton-trion and the Fermi-sea range, are so far poorly understood. We report on an approach to bridge this gap by a magnetophotoluminescence study of modulation-doped (Cd,Mn)Te quantum well structures. Employing their enhanced spin splitting, we analyzed the characteristic magnetic-field behavior of the individual photoluminescence features. Based on these results and earlier findings by other authors, we present a new approach for understanding the optical transitions at intermediate densities in terms of four-particle excitations, the Suris tetrons, which were up to now only predicted theoretically. All characteristic photoluminescence features are attributed to emission from these quasiparticles when attaining different final states.

17.
Patol Fiziol Eksp Ter ; (1): 15-26, 2013.
Artigo em Russo | MEDLINE | ID: mdl-23805709

RESUMO

In this adiponectin-focused review, the pathophysiological role and the potential therapeutic benefits of adiponectin in metabolic syndrome (MetS) are analysed. MetS is recognized as clusters several metabolic abnormalities and the leading cause of cardiovascular diseases. Insulin resistance (IR) is a key factor in the pathogenesis MetS. Adiponectin is the most abundant and adipose-specific adipokine. Adiponectin acts through the activation of AMP-activated protein kinase and peroxisome proliferator-activated receptor-alpha (PPARalpha) pathways. The wide distribution of adiponectin receptors in various organs and tissues suggests that adiponectin has pleiotropic effects on numerous physiological processes. Its well-known insulin-sensitizing, anti-inflammatory and antiatherosclerotic properties, accumulating evidence suggests that adiponectin may have cardioprotective properties. There is an evidence that adiponectin decreases systematic IR and generally predicts cardiovascular diseases. Recent therapeutic strategies have focused on the indirect upregulation of adiponectin through the administration of various therapeutic agents and/or lifestyle modifications. Weight loss, diet, lifestyle changes and/or medications including orlistat, sibutramine, rimonabant, increase level of adiponectin. Also insulin sensitizers, including thiazolidinediones, and lipid-lowering agents, including statins and fibrates, upregulate adiponectin and may improve IR. The wider use of new treatment approaches appears to signal of a new era in the management of cardiovascular diseases, diabetes mellitus and MetS.


Assuntos
Adiponectina/metabolismo , Síndrome Metabólica/metabolismo , Animais , Depressores do Apetite/uso terapêutico , Humanos , Insulina/metabolismo , Resistência à Insulina , Reguladores do Metabolismo de Lipídeos/uso terapêutico , Síndrome Metabólica/tratamento farmacológico , Síndrome Metabólica/etiologia , PPAR alfa/metabolismo
18.
Nat Nanotechnol ; 8(3): 206-12, 2013 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-23396313

RESUMO

Applications of semiconductor nanocrystals such as biomarkers and light-emitting optoelectronic devices require that their fluorescence quantum yield be close to 100%. However, such quantum yields have not been obtained yet, in part, because non-radiative Auger recombination in charged nanocrystals could not be suppressed completely. Here, we synthesize colloidal core/thick-shell CdSe/CdS nanocrystals with 100% quantum yield and completely quenched Auger processes at low temperatures, although the nanocrystals are negatively photocharged. Single particle and ensemble spectroscopy in the temperature range 30-300 K shows that the non-radiative Auger recombination is thermally activated around 200 K. Experimental results are well described by a model suggesting a temperature-dependent delocalization of one of the trion electrons from the CdSe core and enhanced Auger recombination at the abrupt CdS outer surface. These results point to a route for the design of core/shell structures with 100% quantum yield at room temperature.


Assuntos
Coloides/química , Elétrons , Pontos Quânticos , Compostos de Cádmio/química , Coloides/síntese química , Fluorescência , Tamanho da Partícula , Compostos de Selênio/química , Sulfetos/química , Propriedades de Superfície
19.
Phys Rev Lett ; 110(11): 116402, 2013 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-25166558

RESUMO

The magneto-Stark effect of excitons is demonstrated to be an efficient source of optical nonlinearity in hexagonal ZnO. Strong resonant second harmonic generation signals induced by an external magnetic field are observed in the spectral range of 2s and 2p excitons. The microscopic theoretical analysis shows that for excitons with a finite wave vector, exciton states of opposite parity are mixed by an effective odd parity electric field induced by the magnetic field despite its even parity. The field, spectral, and polarization dependencies of the second harmonic generation intensity validate the proposed mechanism. The observed phenomenon is not limited to a certain symmetry class and therefore must be effective in other semiconductors.

20.
Ter Arkh ; 84(6): 15-20, 2012.
Artigo em Russo | MEDLINE | ID: mdl-22997912

RESUMO

AIM: To study clinicopathogenetic characteristics of cardiorenal syndrome (CRS) in non-alcoholic fatty disease of the liver (nAFDL). MATERIAL AND METHODS: Insulin resistance markers, plasma leptin and serum adiponectin concentrations. albuminuria, intima-media thickness (IMT) of the common carotid artery (CCA) were assessed in 80 patients with metabolic syndrome (60 males and 20 females, mean age 44+-11 years) and NAFDL. RESULTS: With increasing signs of affection of target organs in NAFDL there was a trend to a significant rise in detection of chronic kidney disease (CKD) and carotid artery atherosclerosis, aggravation of albuminuria and CCA IMT, lowering of glomerular filtration rate. Leptinemia was maximal in CKD patients and directly correlated with albuminuria. Patients with CCA atherosclerosis had a significant fall of serum adiponectin which negatively correlated with CCA IMT. The latter positively correlated with insulinemia, a C-peptide plasma level and HOMA index. Serum concentration of adiponectin positively correlated with DeRitis index. CONCLUSION: CRS in NAFDL is characterized with frequent development of CKD and CCA atherosclerosis defined also by unbalance of adiponectin and leptin production.


Assuntos
Síndrome Cardiorrenal/diagnóstico , Síndrome Cardiorrenal/etiologia , Fígado Gorduroso/complicações , Fígado Gorduroso/diagnóstico , Adiposidade , Adulto , Biomarcadores/sangue , Síndrome Cardiorrenal/epidemiologia , Artéria Carótida Primitiva/diagnóstico por imagem , Artéria Carótida Primitiva/patologia , Interpretação Estatística de Dados , Ecocardiografia , Fígado Gorduroso/epidemiologia , Feminino , Humanos , Hipertrofia Ventricular Esquerda/diagnóstico por imagem , Hipertrofia Ventricular Esquerda/etiologia , Resistência à Insulina , Masculino , Pessoa de Meia-Idade , Hepatopatia Gordurosa não Alcoólica , Fatores Sexuais , Túnica Íntima/diagnóstico por imagem , Túnica Íntima/patologia , Ultrassonografia Doppler Dupla , Adulto Jovem
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