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1.
Khirurgiia (Mosk) ; (5): 59-67, 2022.
Artigo em Russo | MEDLINE | ID: mdl-35593629

RESUMO

OBJECTIVE: To assess the early and long-term results after the Norwood procedure and to identify predictors of aortic recoarctation and arterial hypertension. MATERIAL AND METHODS: We have operated on 2789 infants in the department of congenital heart diseases of the Meshalkin National Medical Research Center between January 2015 and December 2018. The current single-center prospective cohort study included 39 (1.4%) patients with hypoplastic left heart syndrome who underwent the Norwood procedure. RESULTS: In-hospital mortality was 15.3% (n=6). An inter-stage mortality was 10.2% (n=4). Recoarctation of the aorta and Sano shunt stenosis in inter-stage period occurred in 8 (24.2%) and 4 patients (12.1%), respectively. Body mass <3 kg was the only risk factor of recoarctation (OR 7.08, 95% CI 1.17; 42.79, p=0.033). We found no risk factors of Sano shunt stenosis. There were no signs of recoarctation and Sano shunt dysfunction in the early postoperative period. Arterial hypertension developed in 14 (48.3%) patients. We found the correlation between systolic blood pressure and ventricular ejection fraction (ß coefficient -0.88, 95% CI -1.33; -0.44, p=0.001). The only risk factor of arterial hypertension was increased stiffness of the aorta. CONCLUSION: The early and inter-stage mortality are still the issues after the Norwood procedure. Postoperative reduced ejection fraction of single ventricle is one of the most common complications that could be related with residual arterial hypertension.


Assuntos
Hipertensão , Procedimentos de Norwood , Constrição Patológica/etiologia , Humanos , Hipertensão/etiologia , Lactente , Procedimentos de Norwood/efeitos adversos , Procedimentos de Norwood/métodos , Estudos Prospectivos , Estudos Retrospectivos , Resultado do Tratamento
2.
Khirurgiia (Mosk) ; (2): 5-12, 2019.
Artigo em Inglês, Russo | MEDLINE | ID: mdl-30855584

RESUMO

AIM: To describe single-center evolution of the procedure and to evaluate the results of thoracoscopic clipping of patent ductus arteriosus (PDA) with diameter over 3,0 mm in term infants weighting over 4,0 kg. MATERIAL AND METHODS: Thoracoscopic clipping of PDA has been performed in 140 patients for the period from March 2012 to March 2018 in Meshalkin National Medical Research Center. Mean age was 4.0 years (range 3 months - 13 years), mean body mass index - 15.4±2.2 kg/m2. INCLUSION CRITERIA: PDA size 3.5-10 mm, Qp/Qs >1,3/1,0, weight 4.0-40 kg. Mean PDA size was 4.6±0.9 mm (range 3.5-8.0 mm), mean pulmonary artery pressure - 34.3±5.8 mm Hg, mean systemic/pulmonary flow Qp/Qs - 1.6±0.3. All patients underwent successful PDA closure through four-port technique under endotracheal general anesthesia and no need for pleural drainage. RESULTS: Mean procedure time was 24.5±15.5 min. In 29 (20,7%) cases we used titanium clips, in 11 (79.3%) - polymer locking ligating clips. There was 1 conversion to mini-thoracotomy. There were no deaths, bleeding or any other life-threatening complications. 94 (67.1%) patients were weaned from ventilator within operating theatre, in other 46 (32.9%) patients mean ventilation time in ICU was 1.3±1.0 hours. In-hospital postoperative complications: pneumothorax - 2 (1.4%) cases, recurrent laryngeal nerve dysfunction - 1 (0.7%), false croup - 1 (0.7%). There were 2 residual leakages in 2 (1.4%) patients in 10 and 6 months after titanium clip deployment. Both of them underwent transcatheter closure using the coil. Considering these cases all following patients underwent PDA closure by polymer locking ligating clips with no cases of residual leakage. CONCLUSION: Thoracoscopic PDA closure by polymer locking ligating clip is safe and effective technique for surgical management of PDA with diameter over 3.0 mm in term infants weighting over 4.0 kg.


Assuntos
Permeabilidade do Canal Arterial/cirurgia , Toracoscopia/métodos , Adolescente , Cateterismo Cardíaco , Criança , Pré-Escolar , Humanos , Lactente , Ligadura , Instrumentos Cirúrgicos , Grampeamento Cirúrgico , Toracoscopia/instrumentação , Resultado do Tratamento
3.
Khirurgiia (Mosk) ; (2): 4-20, 2018.
Artigo em Russo | MEDLINE | ID: mdl-29460874

RESUMO

AIM: To analyze immediate results of minimally invasive robot-assisted atrial septal defect (ASD) closure in adults. MATERIAL AND METHODS: For the period from March 2012 to November 2016 sixty patients with contraindications to endovascular procedure have undergone robot-assisted atrial septal defect closure at Meshalkin Siberian Federal Biomedical Research Center. Mean age was 34.5±11.3 years, body mass index - 24.6±4.0 kg/m2. 48 (80%) patients had NYHA class II before surgery. In 37 (61.7%) patients isolated ASD with deficiency or absence of one edge was diagnosed, isolated ASD with primary septum aneurysm - in 16 (26.7%) cases, 7 (11.6%) patients had reticulate ASD. 5 (8.3%) patients had concomitant tricuspid valve insufficiency required surgical repair (suture annuloplasty). All operations were performed under cardiopulmonary bypass with peripheral cannulation. Right-sided anterolateral mini-thoracotomy was used in the first 43 patients. Following 17 patients underwent completely endoscopic procedure. Depending on the shape, size and anatomical features of the defect we performed suturing (14 patients, 23.3%) or repair with xenopericardial patch (46%, 76.6%). RESULTS: Mean CPB and aortic cross-clamping time was 89.1±28.7 and 24.8±9.5 min, respectively. Postoperative variables: mechanical ventilation 3.3±1.5 hours, ICU-stay - 18.2±3.7 hours, postoperative hospital-stay - 13.4±5.7 days. There were no mortality and any life-threatening intra- and postoperative complications. Cases of conversion to thoraco-/sternotomy and postoperative bleeding followed by redo surgery were also absent. 23 patients were followed-up within 1 year, 6 patients - within 2 years, 3 patients - within 3 years. All patients were in NYHA class I-II with 100% freedom from ASD recanalization and redo surgery. According to echocardiography data there were decreased right heart, pulmonary artery pressure and preserved left ventricular function in early postoperative period and 1 year after surgery. CONCLUSION: In view of favorable course of postoperative period, no significant specific complications and encouraging immediate results we can talk about endoscopic robot-assisted ASD closure in adults as a safe and effective alternative to surgical treatment.


Assuntos
Procedimentos Cirúrgicos Cardíacos , Procedimentos Endovasculares , Comunicação Interatrial , Complicações Pós-Operatórias/diagnóstico , Procedimentos Cirúrgicos Robóticos , Adulto , Procedimentos Cirúrgicos Cardíacos/efeitos adversos , Procedimentos Cirúrgicos Cardíacos/métodos , Ponte Cardiopulmonar/métodos , Ecocardiografia/métodos , Procedimentos Endovasculares/efeitos adversos , Procedimentos Endovasculares/métodos , Feminino , Comunicação Interatrial/diagnóstico , Comunicação Interatrial/cirurgia , Humanos , Masculino , Pessoa de Meia-Idade , Procedimentos Cirúrgicos Minimamente Invasivos/efeitos adversos , Procedimentos Cirúrgicos Minimamente Invasivos/métodos , Avaliação de Processos e Resultados em Cuidados de Saúde , Procedimentos Cirúrgicos Robóticos/efeitos adversos , Procedimentos Cirúrgicos Robóticos/métodos , Federação Russa
4.
Mol Biol (Mosk) ; 51(1): 126-130, 2017.
Artigo em Russo | MEDLINE | ID: mdl-28251975

RESUMO

Shallot virus X is a typical representative of Allexiviruses. The transcription levels of principal genes involved in the RNA silencing in healthy and shallot virus X-infected plants have been quantified by real-time polymerase chain reaction. There is a negative correlation between the reproduction rates of RNA virus and the levels of RNA-dependent RNA polymerase and DCL proteins in roots and leaves of infected plants. These observations indicate that Shallot X virus employs noncanonical ways of overcoming the antiviral defense of the plant by systemic RNA silencing.


Assuntos
Flexiviridae/patogenicidade , Doenças das Plantas/virologia , Raízes de Plantas/virologia , RNA Polimerase Dependente de RNA/genética , Células Vegetais/virologia , Doenças das Plantas/genética , Raízes de Plantas/genética , Interferência de RNA , RNA de Plantas
5.
Bull Exp Biol Med ; 163(1): 57-60, 2017 May.
Artigo em Inglês | MEDLINE | ID: mdl-28577102

RESUMO

The effects of dihydroquercetin (50 mg/kg intragastrically daily for 6 weeks) on the density of capillary network (mean number of capillaries per mm2), mean capillary diameter, structure of capillary network, capillary diameter distribution (<3, 3-5, 5-7, and 7-9 µ), and local cerebral blood flow (by laser Doppler) in the visual cortex were studied in SHR rats during the development of arterial hypertension (from the 6th to the 12th week of life). Normally, the systolic and diastolic BP progressively increased in SHR rats during this period. Dihydroquercetin did not affect the development of arterial hypertension. At the same time, the drug significantly increased the mean diameter of capillaries (by 11%), capillary network density (by 23%), and in the percentage of capillaries with a diameter of 3-9 µ (passable for erythrocytes; by 42%). Positive effects of dihydroquercetin on the structure of microcirculatory bed improved microcirculation: local cerebral blood flow in the visual cortex of SHR rats was significantly higher (by 36%) than in rats receiving no flavonoid and close to the value in Wistar-Kyoto rats. Dihydroquercetin improved microvascularization and microcirculation in the cerebral cortex of SHR rats during the formation of arterial hypertension.


Assuntos
Pressão Sanguínea/efeitos dos fármacos , Microcirculação/efeitos dos fármacos , Quercetina/análogos & derivados , Animais , Encéfalo/irrigação sanguínea , Córtex Cerebral/efeitos dos fármacos , Córtex Cerebral/fisiologia , Circulação Cerebrovascular/efeitos dos fármacos , Hipertensão/tratamento farmacológico , Hipertensão/fisiopatologia , Quercetina/uso terapêutico , Ratos , Ratos Endogâmicos WKY
6.
Urologiia ; (6): 132-135, 2016 Dec.
Artigo em Russo | MEDLINE | ID: mdl-28248058

RESUMO

The article reports a case of a robot-assisted cystprostatectomy in a 36 y.o. patient with a malignant bladder neoplasm (highly differentiated infiltrative urothelial bladder cancer, Gr 2, invading the bladder wall mucosa, the multicentric growth type, with the focal tumor growth in the urethral mucosa and prostate). The ileal neobladder was constructed using intracorporeal access. Operating time was 6 hours, intraoperative blood loss was 150 ml. There was no intra - or postoperative complications. Voiding function was restored at day 10 postoperatively.


Assuntos
Cistectomia/métodos , Próstata/cirurgia , Prostatectomia/métodos , Procedimentos Cirúrgicos Robóticos , Neoplasias da Bexiga Urinária/cirurgia , Adulto , Perda Sanguínea Cirúrgica , Humanos , Masculino , Gradação de Tumores , Invasividade Neoplásica , Procedimentos de Cirurgia Plástica , Resultado do Tratamento , Bexiga Urinária/cirurgia , Neoplasias da Bexiga Urinária/patologia
7.
Fiziol Cheloveka ; 41(5): 66-73, 2015.
Artigo em Russo | MEDLINE | ID: mdl-26601410

RESUMO

We studied schizophrenic patients with the dominance of pseudohallucinations. As is well known, pseudohallucinations are the main syndrome of schizophrenia, the so-called first rank syndrome. Pseudohallucinations are defined as a disorder of sense (affective) perception. This disorder is mainly diagnosed from the clinical picture or by pathopsychologichal observations. We investigated the evoked potentials (EP) of brain after neutral and emotionally meaningful (threatening) visual stimuli in order to specify the neurophysiological disorders of affective perception in schizophrenic patients with severe paranoid-hallucinatory syndrome who did not receive neuroleptic therapy. The analysis of P200 component in healthy subjects showed an increase in the amplitude and shortening of the latency of this wave in response to thretaning stimuli, as compared to neutral stimuli. In the group of patients with schizophrenia, the analysis showed the same increase in the level of excitation in response to emotionally threatening stimuli. However, in schizophrenic patients there were also found certain areas where the amplitude and latency decreased or increased at the same time. The results show that patients with schizophrenia have the pathological effect of having parameters typical of the processes of both excitation and inhibition.


Assuntos
Potenciais Evocados , Percepção , Esquizofrenia Paranoide/fisiopatologia , Esquizofrenia Paranoide/psicologia , Adolescente , Adulto , Feminino , Alucinações/diagnóstico , Alucinações/fisiopatologia , Alucinações/psicologia , Humanos , Masculino , Esquizofrenia Paranoide/diagnóstico
8.
Fiziol Cheloveka ; 41(4): 31-6, 2015.
Artigo em Russo | MEDLINE | ID: mdl-26485786

RESUMO

Cognitive and emotional disorders, as far as is known, are the main syndromes of schizophrenia. Disorders of these functions are mainly determined by the clinical picture, as well as by psychophysiological correlates. The purpose of our study was to identify some psychophysiological factors which cause perceptual and emotional disturbances in patients with schizophrenia. These disorders of mental functions form the first rank (top) syndrome in patients with schizophrenia [1]. The studied patients had acute psychosis with a predominance of paranoid hallucinatory syndrome and did not receive antipsychotic therapy; i.e., the disturbances of sensory perception were most pronounced. The analysis of early component P100 and intermediate one N170 of event related potentials (ERPs) in the control group showed an increased level of excitation in response to emotionally threatening stimuli; the amplitude increased and the latency decreased in all leads. In contrast the analysis of components P100 and N170 in the group of patients with schizophrenia showed the increased latency and decreased amplitude. The obtained data provide evidence of pathological inhibition in the passive perception of emotionally significant stimuli.


Assuntos
Encéfalo/fisiologia , Emoções/fisiologia , Potenciais Evocados Visuais/fisiologia , Reconhecimento Visual de Modelos/fisiologia , Tempo de Reação/fisiologia , Esquizofrenia Paranoide/psicologia , Adolescente , Adulto , Estudos de Casos e Controles , Eletroencefalografia , Feminino , Humanos , Masculino , Neurofisiologia , Estimulação Luminosa , Esquizofrenia Paranoide/fisiopatologia , Adulto Jovem
9.
Stomatologiia (Mosk) ; 92(1): 63-5, 2013.
Artigo em Russo | MEDLINE | ID: mdl-23528406

RESUMO

The article analyzes the features and clinical aspects of implant-retained restorations in the anterior maxilla important for achieving optimal functional and esthetic results.


Assuntos
Implantação Dentária , Implantes Dentários , Reparação de Restauração Dentária , Adulto , Estética Dentária , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Reabilitação Bucal , Adulto Jovem
10.
Stomatologiia (Mosk) ; 92(5): 4-8, 2013.
Artigo em Russo | MEDLINE | ID: mdl-24300698

RESUMO

Interrelations of biodegradable poliglicolic and polilactic acid polymers in various proportions implanted in standardized bone defects were evaluated in animal model with 40 Wister line rats. During 10 month follow-up period bone capsule surrounded all implants, but timing of bone formation and bone quality varied significantly being optimal in LactoSorb group. Destructive features of polymers were also seen in implant-bone contact area defined as inflammation, fibrous tissue formation and cell dystrophy.


Assuntos
Implantes Absorvíveis/efeitos adversos , Materiais Biocompatíveis/efeitos adversos , Substitutos Ósseos/efeitos adversos , Ácido Láctico/efeitos adversos , Poliésteres/efeitos adversos , Ácido Poliglicólico/efeitos adversos , Polímeros/efeitos adversos , Animais , Materiais Biocompatíveis/química , Substitutos Ósseos/química , Osso e Ossos/efeitos dos fármacos , Osso e Ossos/patologia , Tecido Conjuntivo/efeitos dos fármacos , Tecido Conjuntivo/patologia , Fibrose , Inflamação/induzido quimicamente , Inflamação/patologia , Ácido Láctico/química , Teste de Materiais , Poliésteres/química , Ácido Poliglicólico/química , Copolímero de Ácido Poliláctico e Ácido Poliglicólico , Polímeros/química , Ratos , Ratos Wistar
11.
Stomatologiia (Mosk) ; 92(1): 4-8, 2013.
Artigo em Russo | MEDLINE | ID: mdl-23528392

RESUMO

The paper summarizes the results of in vitro and in vivo studies that have proved biocompatibility and medical safety of Ta and Ti-Nb-Ta-bases alloys. According to some in vitro data Ti-Nb-Ta-based alloy possesses certain advantages when comparing to Ta-based. In particular, it contributes to elevation of viability of cellular elements and to definite increase of their adhesive potential.


Assuntos
Ligas/uso terapêutico , Ligas Dentárias/uso terapêutico , Implantação Dentária , Nióbio , Tantálio , Titânio , Ligas/efeitos adversos , Animais , Células Cultivadas , Ligas Dentárias/efeitos adversos , Fibroblastos , Teste de Materiais , Coelhos
12.
Voen Med Zh ; 334(2): 84-8, 2013 Feb.
Artigo em Russo | MEDLINE | ID: mdl-23808207

RESUMO

The article is devoted to the 80th anniversary of the formation of the naval medical science subunit, which is the part of the 1st Central Research Institute of the Defense Ministry of Russian Federation. In the 30th years of XX century, a group of naval doctors formulated the main directions of preventive naval medicine. For eight decades, several generations of medical scientists have developed and ensured implementation of regulatory requirements for habitability and ergonomics of Navy ships. At the present stage, this work focuses on promising directions of the development of the domestic military shipbuilding and the use of advanced and innovative biomedical technologies.


Assuntos
Pesquisa Biomédica/história , Medicina Militar/história , Medicina Naval/história , Aniversários e Eventos Especiais , História do Século XX , História do Século XXI , Humanos , Federação Russa
13.
Stomatologiia (Mosk) ; 91(6): 45-7, 2012.
Artigo em Russo | MEDLINE | ID: mdl-23268218

RESUMO

The paper describes the sinus-lifting technique useful in patients with alveolar bone deficiency. The technique allows significantly lowering the risk of maxillary sinus mucosa perforation and improves bone tissue regeneration.


Assuntos
Perda do Osso Alveolar/cirurgia , Aumento do Rebordo Alveolar , Remoção/efeitos adversos , Seio Maxilar/lesões , Mucosa Nasal/lesões , Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade
14.
Stomatologiia (Mosk) ; 91(5): 31-3, 2012.
Artigo em Russo | MEDLINE | ID: mdl-23268182

RESUMO

The paper analyzes modern approaches to bone density evaluation by planning of dental implantation procedure. Implantation technique in patients with low-density bone creating favorable conditions for osseous integration is described.


Assuntos
Densidade Óssea , Implantação Dentária Endóssea/métodos , Arcada Osseodentária/diagnóstico por imagem , Procedimentos Cirúrgicos Ortognáticos , Adulto , Idoso , Tomografia Computadorizada de Feixe Cônico , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Adulto Jovem
15.
Stomatologiia (Mosk) ; 91(6): 4-7, 2012.
Artigo em Russo | MEDLINE | ID: mdl-23268208

RESUMO

The perspectives of use of porous polytetrafluorethilen (PTPE) with modified surface combined with mesenchymal stem cells for tissue-engineering constructions were studied. The paper also describes the mode of PTPE surface modification consisting in nanostructured metallic or ceramic layer application resulting in biocompatibility and surface adhesion rates increase. The magnetic atomizing of Ti and Ti-Ca-P-C-O-N nanolayers enhances the material integration potential as well as adhesion rates thus making it perspective when combined with mesenchymal stem cells for bone defects plasty.


Assuntos
Materiais Revestidos Biocompatíveis , Implante de Prótese Maxilofacial , Nanoestruturas , Politetrafluoretileno , Engenharia Tecidual , Alicerces Teciduais , Adesão Celular , Células Cultivadas , Humanos , Células-Tronco Mesenquimais/citologia , Células-Tronco Mesenquimais/fisiologia , Ligas Metalo-Cerâmicas
16.
Sovrem Tekhnologii Med ; 14(5): 53-75, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-37181835

RESUMO

Schizophrenia is a socially significant mental disorder resulting frequently in severe forms of disability. Diagnosis, choice of treatment tactics, and rehabilitation in clinical psychiatry are mainly based on the assessment of behavioral patterns, socio-demographic data, and other investigations such as clinical observations and neuropsychological testing including examination of patients by the psychiatrist, self-reports, and questionnaires. In many respects, these data are subjective and therefore a large number of works have appeared in recent years devoted to the search for objective characteristics (indices, biomarkers) of the processes going on in the human body and reflected in the behavioral and psychoneurological patterns of patients. Such biomarkers are based on the results of instrumental and laboratory studies (neuroimaging, electro-physiological, biochemical, immunological, genetic, and others) and are successfully being used in neurosciences for understanding the mechanisms of the emergence and development of nervous system pathologies. Presently, with the advent of new effective neuroimaging, laboratory, and other methods of investigation and also with the development of modern methods of data analysis, machine learning, and artificial intelligence, a great number of scientific and clinical studies is being conducted devoted to the search for the markers which have diagnostic and prognostic value and may be used in clinical practice to objectivize the processes of establishing and clarifying the diagnosis, choosing and optimizing treatment and rehabilitation tactics, predicting the course and outcome of the disease. This review presents the analysis of the works which describe the correlates between the diagnosis of schizophrenia, established by health professionals, various manifestations of the psychiatric disorder (its subtype, variant of the course, severity degree, observed symptoms, etc.), and objectively measured characteristics/quantitative indicators (anatomical, functional, immunological, genetic, and others) obtained during instrumental and laboratory examinations of patients. A considerable part of these works has been devoted to correlates/biomarkers of schizophrenia based on the data of structural and functional (at rest and under cognitive load) MRI, EEG, tractography, and immunological data. The found correlates/biomarkers reflect anatomic disorders in the specific brain regions, impairment of functional activity of brain regions and their interconnections, specific microstructure of the brain white matter and the levels of connectivity between the tracts of various structures, alterations of electrical activity in various parts of the brain in different EEG spectral ranges, as well as changes in the innate and adaptive links of immunity. Current methods of data analysis and machine learning to search for schizophrenia biomarkers using the data of diverse modalities and their application during building and interpretation of predictive diagnostic models of schizophrenia have been considered in the present review.


Assuntos
Esquizofrenia , Humanos , Esquizofrenia/diagnóstico , Esquizofrenia/patologia , Inteligência Artificial , Encéfalo , Aprendizado de Máquina , Biomarcadores
17.
Ontogenez ; 42(3): 165-71, 2011.
Artigo em Russo | MEDLINE | ID: mdl-21786648

RESUMO

Changes in the quantitative composition of mass fish species at early stages of ontogenesis in different areas of the Central-Eastern Atlantic (CEA) in warm and cold seasons in 1994-2008 were analyzed in the paper. The most widespread representatives of ichthyocenosis of CEA were: European pilchard (Sardina pilchardus), common scad (Trachurus trachurus), round sardinella (Sardinella aurita), and West-African scad (Trachrus trecae). The data obtained indicate that, within the economic zone of Morocco, fluctuations of numbers at early stages of development in European pilchard and common scad are close over the entire water area under consideration (36 degrees-21 degrees N). The regularities of fluctuations of the numbers of ichthyoplankton are similar to the interannual changes in the biomass of fish in the area of Morocco. In the area of Mauritania (21 degrees-16 degrees N), fluctuations of numbers of the early stages of development of commercial fish cannot be unambiguously correlated with changes in the biomass of adult fish. It is known that, in the economic zone of Mauritania, there are Senegal-Mauritanian populations of round sardinella and West-African scad that inhabit waters of different states and are not completely assessed by our surveys. Therefore, no obvious relation was observed between the considered data.


Assuntos
Peixes , Zooplâncton/crescimento & desenvolvimento , Migração Animal , Animais , Oceano Atlântico , Pesqueiros , Peixes/embriologia , Peixes/crescimento & desenvolvimento , Mauritânia , Marrocos , Dinâmica Populacional
18.
Biophys J ; 99(4): 1175-81, 2010 Aug 09.
Artigo em Inglês | MEDLINE | ID: mdl-20713001

RESUMO

The current rapid growth in the use of nanosized particles is fueled in part by our increased understanding of their physical properties and ability to manipulate them, which is essential for achieving optimal functionality. Here we report detailed quantitative measurements of the mechanical response of nanosized protein shells (viral capsids) to large-scale physical deformations and compare them with theoretical descriptions from continuum elastic modeling and molecular dynamics (MD). Specifically, we used nanoindentation by atomic force microscopy to investigate the complex elastic behavior of Hepatitis B virus capsids. These capsids are hollow, approximately 30 nm in diameter, and conform to icosahedral (5-3-2) symmetry. First we show that their indentation behavior, which is symmetry-axis-dependent, cannot be reproduced by a simple model based on Föppl-von Kármán thin-shell elasticity with the fivefold vertices acting as prestressed disclinations. However, we can properly describe the measured nonlinear elastic and orientation-dependent force response with a three-dimensional, topographically detailed, finite-element model. Next, we show that coarse-grained MD simulations also yield good agreement with our nanoindentation measurements, even without any fitting of force-field parameters in the MD model. This study demonstrates that the material properties of viral nanoparticles can be correctly described by both modeling approaches. At the same time, we show that even for large deformations, it suffices to approximate the mechanical behavior of nanosized viral shells with a continuum approach, and ignore specific molecular interactions. This experimental validation of continuum elastic theory provides an example of a situation in which rules of macroscopic physics can apply to nanoscale molecular assemblies.


Assuntos
Elasticidade , Simulação de Dinâmica Molecular , Nanoestruturas/química , Tamanho da Partícula , Proteínas/química , Capsídeo/química , Capsídeo/ultraestrutura , Análise de Elementos Finitos , Vírus da Hepatite B/química , Microscopia de Força Atômica
19.
Stomatologiia (Mosk) ; 89(5): 4-8, 2010.
Artigo em Russo | MEDLINE | ID: mdl-21191328

RESUMO

It was analyzed the status of dental implants integration into bone tissue problem. The concept of stages and mechanisms of development of integration process in the implant-bone interface based on literature data and own study was presented.


Assuntos
Implantação Dentária Endóssea , Implantes Dentários , Adaptação Fisiológica , Homeostase , Humanos
20.
Appl Radiat Isot ; 66(11): 1741-4, 2008 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-18513982

RESUMO

The Urban Remediation Working Group of the International Atomic Energy Agency's Environmental Modelling for Radiation Safety (EMRAS) programme was established to improve modelling and assessment capabilities for radioactively contaminated urban situations, including the effects of countermeasures. An example of the Working Group's activities is an exercise based on Chernobyl fallout data in Ukraine, which has provided an opportunity to compare predictions among several models and with available measurements, to discuss reasons for discrepancies, and to identify areas where additional information would be helpful.


Assuntos
Cidades , Exposição Ambiental/análise , Exposição Ambiental/prevenção & controle , Modelos Biológicos , Monitoramento de Radiação/métodos , Proteção Radiológica/métodos , Carga Corporal (Radioterapia) , Simulação por Computador , Humanos , Agências Internacionais/organização & administração , Doses de Radiação , Reprodutibilidade dos Testes , Sensibilidade e Especificidade
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