RESUMO
An essential aspect of the work of the operating room is the provision of safety of both the patient and staff. The organization of the activity of the surgical service requires serious elaboration of each of its stage, as well as standardization in using various validated instruments. When speaking of a hybrid operating room with the use of intraoperative magnetic resonance tomography, such an approach becomes not merely a recommendation but rather forced and justified necessity. Simultaneous use of various technologies of imaging and treatment with the engagement of physicians of various specialties requires especially thorough control. A generally accepted international standard of the work of the operating block is the use of checklists, and since 2008 the initiative of the World Health Organization "Safe Surgery Saves Lives" has globally been working to promote implementation of the WHO Surgical Safety Checklists (SSCL) to the real clinical practice. The intraoperative MR-diagnostic stage dictates rigid requirements for proper inventory of ferromagnetic and nonmagnetic surgical tools, verified logistics, and routing of the patient in the conditions of high and extremely high (1.5-3.0 T) magnetic field. A separate and not less important problem is anaesthesiological support during MRT. In order to optimise the patient's movements and adequate monitoring of his/her safety inside the operating department, the authors have modified the standard WHO Surgical Safety Checklist. Implementation of the modified checklist for the MRT-equipped hybrid operating room should improve the control over the processes, as well as increase safety of both the patient and personnel.
Assuntos
Lista de Checagem/normas , Imageamento por Ressonância Magnética , Salas Cirúrgicas/organização & administração , Segurança do Paciente/normas , Gestão da Segurança , Humanos , Imageamento por Ressonância Magnética/efeitos adversos , Imageamento por Ressonância Magnética/instrumentação , Imageamento por Ressonância Magnética/métodos , Monitorização Intraoperatória/métodos , Melhoria de Qualidade , Gestão da Segurança/métodos , Gestão da Segurança/normas , Procedimentos Cirúrgicos Operatórios/métodosRESUMO
The performance of the placenta as a gas exchanger has a direct impact on the future health of the newborn. To provide accurate estimates of respiratory gas exchange rates, placenta models need to account for both the physiology of exchange and the organ morphology. While the former has been extensively studied, accounting for the latter is still a challenge. The geometrical complexity of placental structure requires use of carefully crafted approximations. We present here the state of the art of respiratory gas exchange placenta modeling and demonstrate the influence of the morphology description on model predictions. Advantages and shortcomings of various classes of models are discussed, and experimental techniques that may be used for model validation are summarized. Several directions for future development are suggested.
Assuntos
Gases/metabolismo , Placenta/anatomia & histologia , Placenta/metabolismo , Adulto , Animais , Difusão , Feminino , Humanos , Modelos Biológicos , Modelos Teóricos , Gravidez , Troca Gasosa Pulmonar/fisiologiaRESUMO
We propose an analytical approach to solving the diffusion-convection equations governing oxygen transport in the human placenta. We show that only two geometrical characteristics of a placental cross-section, villi density and the effective villi radius, are needed to predict fetal oxygen uptake. We also identify two combinations of physiological parameters that determine oxygen uptake in a given placenta: (i) the maximal oxygen inflow of a placentone if there were no tissue blocking the flow and (ii) the ratio of transit time of maternal blood through the intervillous space to oxygen extraction time. We derive analytical formulas for fast and simple calculation of oxygen uptake and provide two diagrams of efficiency of oxygen transport in an arbitrary placental cross-section. We finally show that artificial perfusion experiments with no-hemoglobin blood tend to give a two-orders-of-magnitude underestimation of the in vivo oxygen uptake and that the optimal geometry for such setup alters significantly. The theory allows one to adjust the results of artificial placenta perfusion experiments to account for oxygen-hemoglobin dissociation. Combined with image analysis techniques, the presented model can give an easy-to-use tool for prediction of the human placenta efficiency.
Assuntos
Modelos Biológicos , Consumo de Oxigênio/fisiologia , Placenta/metabolismo , Transporte Biológico/fisiologia , Difusão , Feminino , Humanos , Placenta/irrigação sanguínea , Circulação Placentária/fisiologia , GravidezRESUMO
We present a stream-tube model of oxygen exchange inside a human placenta functional unit (a placentone). The effect of villi density on oxygen transfer efficiency is assessed by numerically solving the diffusion-convection equation in a 2D+1D geometry for a wide range of villi densities. For each set of physiological parameters, we observe the existence of an optimal villi density providing a maximal oxygen uptake as a trade-off between the incoming oxygen flow and the absorbing villus surface. The predicted optimal villi density 0.47±0.06 is compatible to previous experimental measurements. Several other ways to experimentally validate the model are also proposed. The proposed stream-tube model can serve as a basis for analyzing the efficiency of human placentas, detecting possible pathologies and diagnosing placental health risks for newborns by using routine histology sections collected after birth.
Assuntos
Vilosidades Coriônicas/fisiologia , Oxigênio/metabolismo , Placenta/fisiologia , Difusão , Eritrócitos/metabolismo , Feminino , Hemoglobinas/metabolismo , Humanos , Recém-Nascido , Troca Materno-Fetal , Modelos Anatômicos , Modelos Biológicos , Porosidade , GravidezRESUMO
Workshops are an important part of the IFPA annual meeting as they allow for discussion of specialized topics. At IFPA meeting 2013 there were twelve themed workshops, four of which are summarized in this report. These workshops related to various aspects of placental biology but collectively covered areas of pregnancy pathologies and placental metabolism: 1) diabetes in pregnancy; 2) lipids, fatty acids and the placenta; 3) oxygen in placental development and pathologies; 4) stem cells and pathologies.
Assuntos
Diabetes Gestacional/metabolismo , Dislipidemias/fisiopatologia , Oxigênio/fisiologia , Placentação , Animais , Feminino , Desenvolvimento Fetal , Humanos , Gravidez , Transdução de Sinais , Células-Tronco/fisiologiaRESUMO
With the aim of prosthetic treatment efficacy increase study of edge parodontium tissue reaction upon different types of artificial crowns was done and methods of chronic localized parodontitis prevention were developed. Changes of the main gingival fluid characteristics (amount, acidity, interleukine-1beta concentration) and indicators of microcirculation in edge parodontium of the teeth under the artificial crowns influence were disclosed. There were developed methods of chronic localized parodontitis prevention produced by artificial crowns edge.
Assuntos
Periodontite Crônica/etiologia , Periodontite Crônica/prevenção & controle , Coroas/efeitos adversos , Periodonto/irrigação sanguínea , Adulto , Periodontite Crônica/diagnóstico , Feminino , Humanos , Interleucina-1beta/análise , Masculino , MicrocirculaçãoRESUMO
We present a comprehensive study of the magnetization switching of a uniaxial nanoparticle driven by a circularly polarized magnetic field rotated in the plane perpendicular to the easy axis. The conditions for the existence of the uniform and non-uniform precessions of the nanoparticle magnetic moment are derived. In addition, the differences between switchings via uniform and non-uniform precession are determined, and the essential role of field polarization is demonstrated. The dependence of the switching time on the field amplitude and frequency are calculated numerically. We show that a permanent magnetic field can reduce the amplitude and frequency of the switching rotating field, and that the combined action of these fields is characterized by an extremely strong dependence of the switching time on the field parameters. We also demonstrate that the transition process caused by an external magnetic field pulse can decrease the switching amplitude in comparison with the value predicted from analysis of the stability criterion. We discuss the advantages of switching the magnetization by means of the action of a rotating field over the magnetization switching using a steady field applied perpendicular to the easy axis.
RESUMO
A comparative study of the thermostability of NAD+-dependent formate dehydrogenases (FDHs; EC 1.2.1.2) from both methylotrophic bacteria Pseudomonas sp. 101 and Moraxella sp. Cl, the methane-utilizing yeast Candida boidinii, and plants Arabidopsis thaliana and Glycine max (soybean) was performed. All the enzymes studied were produced by expression in E. coli cells. The enzymes were irreversibly inactivated in one stage according to first-order reaction kinetics. The FDH from Pseudomonas sp. 101 appeared as the most thermostable enzyme; its counterpart from G. max exhibited the lowest stability. The enzymes from Moraxella sp. Cl, C. boidinii, and A. thaliana showed similar thermostability profiles. The temperature dependence of the inactivation rate constant of A. thaliana FDH was studied. The data of differential scanning calorimetry was complied with the experimental results on the inactivation kinetics of these enzymes. Values of the melting heat were determined for all the enzymes studied.
Assuntos
Arabidopsis/enzimologia , Candida/enzimologia , Formiato Desidrogenases/química , Glycine max/enzimologia , Moraxella/enzimologia , Pseudomonas/enzimologia , Arabidopsis/genética , Candida/genética , Formiato Desidrogenases/genética , Temperatura Alta , Cinética , Moraxella/genética , Pseudomonas/genética , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Glycine max/genética , Especificidade da EspécieRESUMO
From analysis of Ramachandran plot for NAD+-dependent formate dehydrogenase from the methylotrophic bacterium Pseudomonas sp. 101 (FDH, EC 1.2.1.2), five amino acid residues with non-optimal values phi and psi have been located in beta- and pi-turns of the FDH polypeptide chain, e.g., Asn136, Ala191, Tyr144, Asn234, and His263. To clarify their role in the enzyme stability, the residues were replaced with Gly by means of site-directed mutagenesis. The His263Gly mutation caused FDH destabilization and a 1.3-fold increase in the monomolecular inactivation rate constant. The replacements Ala191Gly and Asn234Gly had no significant effect on the stability. The mutations Asn136Gly and Tyr144Gly resulted in higher thermal stability and decreased the inactivation rate by 1.2- and 1.4-fold, respectively. The stabilizing effect of the Tyr144Gly mutation was shown to be additive when introduced into the previously obtained mutant FDH with enhanced thermal stability.
Assuntos
Formiato Desidrogenases/química , Pseudomonas/enzimologia , Sequência de Aminoácidos , Substituição de Aminoácidos , Estabilidade Enzimática , Formiato Desidrogenases/genética , Dados de Sequência Molecular , Mutagênese Sítio-Dirigida , Estrutura Secundária de Proteína , Alinhamento de Sequência , Termodinâmica , Fatores de TempoRESUMO
A fast decay emission peaking at 645 nm with a decay lifetime within the experimental resolution of 0.14 micros is observed in ZnS:Mn2+ nanoparticles. This short-lived signal is also observed in pure ZnS and MgS: Eu3+ nanoparticles, which has nothing to do with Mn(2+)-doped ions but is from the deep trap states of the host materials. The short-lived component decreases in intensity relative to the Mn2+ emission at higher excitation powers, while it increases in intensity at low temperatures and shifts to longer wavelengths at longer time delays. Our observations demonstrated further that the emission of Mn2+ in ZnS: Mn2+ nanoparticles behaves basically the same as in bulk ZnS: Mn2+; the fast decay component is actually from the intrinsic and defect-related emission in sulfide compounds.
Assuntos
Físico-Química/métodos , Manganês/química , Nanopartículas/química , Nanotecnologia/métodos , Sulfetos/química , Compostos de Zinco/química , Zinco/química , Európio/química , Íons , Luminescência , Nanoestruturas , Espectrometria de Fluorescência , Fatores de Tempo , Difração de Raios XRESUMO
In this paper we present recent single molecule detection experiment using a solid immersion lens (SIL) for fluorescent correlation spectroscopy measurements. We compared the performance of the SIL in combination with an air objective (40x, numerical aperture (NA)=1.15) with a water immersion objective (40x, NA=0.6) in a confocal microscope system (ConfoCorr 1). Important parameters for single molecule experiments such as collection efficiency and excitation field confinement were investigated. Although the two set-ups have similar numerical aperture the measurements demonstrated higher field confinement and better collection efficiency for the SIL system in comparison to the conventional confocal set-up. Adding spherical aberrations shifts the sample volume up to 4 microm away from the plane surface of the SIL and conserves a diffraction limited focal volume. In this case the FCS autocorrelation demonstrates a free 3D diffusion of dye molecules in a highly confined light field.
Assuntos
Aumento da Imagem/instrumentação , Lentes , Microscopia Confocal/instrumentação , Microscopia de Fluorescência/instrumentação , Espectrometria de Fluorescência/instrumentação , Desenho de Equipamento , Análise de Falha de Equipamento , Microscopia Confocal/métodos , Microscopia de Fluorescência/métodos , Sensibilidade e Especificidade , Espectrometria de Fluorescência/métodosRESUMO
Combined injuries of the forearm occupy an important place in modern structure of functionally severe traumas. Discussions concerning the best time for nerve reconstructions and unsolved questions of a necessity to restore one of the arteries if the other is safe confirms the importance of the problem. An analysis of the domestic and foreign literature data on diagnosing and treatment of the traumas in question is given. Main specific features of treatment depending on the time, character of injuries and functional role of the injured structures are described.
Assuntos
Artérias/lesões , Traumatismos do Antebraço , Traumatismos dos Nervos Periféricos , Ombro/irrigação sanguínea , Ombro/fisiopatologia , Traumatismos dos Tendões , Artérias/cirurgia , Traumatismos do Antebraço/cirurgia , Humanos , Traumatismo Múltiplo/cirurgia , Nervos Periféricos/cirurgia , Traumatismos dos Tendões/cirurgiaRESUMO
The authors made an analysis of surgical methods of treatment of 63 patients and long-term results in the period from 1 to 6 years in 23 of them. The restoration of all the injured anatomical structures of the forearm and, in particular, the restoration (suture, autovenous plasty) of the major arteries and primary suture of the injured nerves are thought to be necessary for good results.
Assuntos
Traumatismos do Antebraço/cirurgia , Antebraço/irrigação sanguínea , Traumatismo Múltiplo/cirurgia , Lesões dos Tecidos Moles/cirurgia , Ferimentos Penetrantes/cirurgia , Adulto , Artérias/lesões , Artérias/cirurgia , Feminino , Seguimentos , Antebraço/inervação , Antebraço/cirurgia , Humanos , Masculino , Técnicas de Sutura , Fatores de Tempo , Resultado do TratamentoRESUMO
Results of experimental investigation of different biomechanical parameters of the system "bone-fixative" and bony fixatives are analyzed in relation to different types of fractures of the femur neck. The data obtained are compared with clinical results of osteosynthesis. On this basis an index system is recommended for choosing the method of treatment of fractures and the particular type of the fixative.
Assuntos
Fraturas do Colo Femoral/fisiopatologia , Fixação de Fratura/estatística & dados numéricos , Fenômenos Biomecânicos , Fraturas do Colo Femoral/cirurgia , Colo do Fêmur/fisiopatologia , Colo do Fêmur/cirurgia , Fixação de Fratura/instrumentação , Humanos , Técnicas In Vitro , Dispositivos de Fixação Ortopédica/estatística & dados numéricos , Pseudoartrose/fisiopatologia , Pseudoartrose/cirurgia , Análise de Regressão , RotaçãoRESUMO
NAD+-dependent formate dehydrogenase (EC 1.2.1.2, FDH) from methylotrophic bacterium Pseudomonas sp.101 exhibits the highest stability among the similar type enzymes studied. To obtain further increase in the thermal stability of FDH we used one of general approaches based on hydrophobization of protein alpha-helices. Five serine residues in positions 131, 160, 168, 184 and 228 were selected for mutagenesis on the basis of (i) comparative studies of nine FDH amino acid sequences from different sources and (ii) with the analysis of the ternary structure of the enzyme from Pseudomonas sp.101. Residues Ser-131 and Ser-160 were replaced by Ala, Val and Leu. Residues Ser-168, Ser-184 and Ser-228 were changed into Ala. Only Ser/Ala mutations in positions 131, 160, 184 and 228 resulted in an increase of the FDH stability. Mutant S168A was 1.7 times less stable than the wild-type FDH. Double mutants S(131,160)A and S(184,228)A and the four-point mutant S(131,160,184,228)A were also prepared and studied. All FDH mutants with a positive stabilization effect had the same kinetic parameters as wild-type enzyme. Depending on the position of the replaced residue, the single point mutation Ser/Ala increased the FDH stability by 5-24%. Combination of mutations shows near additive effect of each mutation to the total FDH stabilization. Four-point mutant S(131,160,184,228)A FDH had 1.5 times higher thermal stability compared to the wild-type enzyme.
Assuntos
Formiato Desidrogenases/metabolismo , Pseudomonas/enzimologia , Sequência de Aminoácidos , Estabilidade Enzimática , Formiato Desidrogenases/química , Formiato Desidrogenases/genética , Calefação , Dados de Sequência Molecular , Mutagênese , Conformação Proteica , Pseudomonas/genética , Homologia de Sequência de Aminoácidos , Serina/genéticaRESUMO
It was established that the ulceration zones showed hyperemia which increases the volume density of venous vessels, disturbs the permeability of their walls, causes trophic disorders with subsequent phlebosclerosis, limitation of capacitance, appearance of venous hypertension and further changes of the vessel wall structures and neighbouring tissues. Compensatory reaction of the arterial intraorganic bed (vascular spasm) deteriorates trophic disorders. Simultaneous increase of the volume density of arterial vessels in the "intact" zone favours reparative and compensatory capacities of the latter. Repeat ulcer formation and chronic course of the disease furthers development of hemo- and microcirculatory disorders, progressing of angio- and perivascular sclerosis, reorganization of the intramural gastric and duodenal vascular bed.
Assuntos
Duodeno/irrigação sanguínea , Úlcera Péptica/patologia , Estômago/irrigação sanguínea , Doença Aguda , Transtornos Cerebrovasculares/patologia , Doença Crônica , Duodeno/patologia , Mucosa Gástrica/irrigação sanguínea , Mucosa Gástrica/patologia , Humanos , Microcirculação/patologia , Pessoa de Meia-Idade , Necrose/patologia , Úlcera Péptica/etiologia , Estômago/patologiaRESUMO
A new operation for neovascular glaucoma, filtrating vitrectomy, is described. The operation is based on creation of a permanent microfistula in the posterior chamber of the eye and simultaneous replacement of the viscous vitreous body with the isotonic saline. Filtrating vitrectomy was performed in 46 eyes with neovascular diabetic glaucoma. The intraocular pressure was normalized completely without medication in 70 per cent cases in the early postoperative period and in 66 per cent cases in the long term (12-39 months) period.