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1.
Proc Natl Acad Sci U S A ; 117(3): 1753-1761, 2020 Jan 21.
Artigo em Inglês | MEDLINE | ID: mdl-31896584

RESUMO

Carbon dioxide (CO2), the major product of metabolism, has a strong impact on cerebral blood vessels, a phenomenon known as cerebrovascular reactivity. Several vascular risk factors such as hypertension or diabetes dampen this response, making cerebrovascular reactivity a useful diagnostic marker for incipient vascular pathology, but its functional relevance, if any, is still unclear. Here, we found that GPR4, an endothelial H+ receptor, and endothelial Gαq/11 proteins mediate the CO2/H+ effect on cerebrovascular reactivity in mice. CO2/H+ leads to constriction of vessels in the brainstem area that controls respiration. The consequential washout of CO2, if cerebrovascular reactivity is impaired, reduces respiration. In contrast, CO2 dilates vessels in other brain areas such as the amygdala. Hence, an impaired cerebrovascular reactivity amplifies the CO2 effect on anxiety. Even at atmospheric CO2 concentrations, impaired cerebrovascular reactivity caused longer apneic episodes and more anxiety, indicating that cerebrovascular reactivity is essential for normal brain function. The site-specific reactivity of vessels to CO2 is reflected by regional differences in their gene expression and the release of vasoactive factors from endothelial cells. Our data suggest the central nervous system (CNS) endothelium as a target to treat respiratory and affective disorders associated with vascular diseases.

2.
Cell Stress ; 3(11): 330-347, 2019 Sep 25.
Artigo em Inglês | MEDLINE | ID: mdl-31799500

RESUMO

The supply of oxygen and nutrients to the brain is vital for its function and requires a complex vascular network that, when disturbed, results in profound neurological dysfunction. As part of the pathology in stroke, endothelial cells die. As endothelial cell death affects the surrounding cellular environment and is a potential target for the treatment and prevention of neurological disorders, we have systematically reviewed important aspects of endothelial cell death with a particular focus on stroke. After screening 2876 publications published between January 1, 2010 and August 7, 2019, we identified 154 records to be included. We found that endothelial cell death occurs rapidly as well as later after the onset of stroke conditions. Among the different cell death mechanisms, apoptosis was the most widely investigated (92 records), followed by autophagy (20 records), while other, more recently defined mechanisms received less attention, such as lysosome-dependent cell death (2 records) and necroptosis (2 records). We also discuss the differential vulnerability of brain cells to injury after stroke and the role of endothelial cell death in the no-reflow phenomenon with a special focus on the microvasculature. Further investigation of the different cell death mechanisms using novel tools and biomarkers will greatly enhance our understanding of endothelial cell death. For this task, at least two markers/criteria are desirable to determine cell death subroutines according to the recommendations of the Nomenclature Committee on Cell Death.

3.
Chem Res Toxicol ; 32(11): 2338-2352, 2019 Nov 18.
Artigo em Inglês | MEDLINE | ID: mdl-31625387

RESUMO

One of the most appreciated capabilities of computational toxicology is to support the design of pharmaceuticals with reduced toxicological hazard. To this end, we have strengthened our drug photosafety assessments by applying novel computer models for the anticipation of in vitro phototoxicity and human photosensitization. These models are typically used in pharmaceutical discovery projects as part of the compound toxicity assessments and compound optimization methods. To ensure good data quality and aiming at models with global applicability we separately compiled and curated highly chemically diverse data sets from 3T3 NRU phototoxicity reports (450 compounds) and clinical photosensitization alerts (1419 compounds) which are provided as supplements. The latter data gives rise to a comprehensive list of explanatory fragments for visual guidance, termed phototoxophores, by application of a Bayesian statistics approach. To extend beyond the domain of well sampled fragments we applied machine learning techniques based on explanatory descriptors such as pharmacophoric fingerprints or, more important, accurate electronic energy descriptors. Electronic descriptors were extracted from quantum chemical computations at the density functional theory (DFT) level. Accurate UV/vis spectral absorption descriptors and pharmacophoric fingerprints turned out to be necessary for predictive computer models, which were both derived from Deep Neural Networks but also the simpler Random Decision Forests approach. Model accuracies of 83-85% could typically be reached for diverse test data sets and other company in-house data, while model sensitivity (the capability of correctly detecting toxicants) was even better, reaching 86%-90%. Importantly, a computer model-triggered response-map allowed for graphical/chemical interpretability also in the case of previously unknown phototoxophores. The photosafety models described here are currently applied in a prospective manner for the hazard identification, prioritization, and optimization of newly designed molecules.

4.
J Chem Inf Model ; 59(3): 1253-1268, 2019 03 25.
Artigo em Inglês | MEDLINE | ID: mdl-30615828

RESUMO

Successful drug discovery projects require control and optimization of compound properties related to pharmacokinetics, pharmacodynamics, and safety. While volume and chemotype coverage of public and corporate ADME-Tox (absorption, distribution, excretion, metabolism, and toxicity) databases are constantly growing, deep neural nets (DNN) emerged as transformative artificial intelligence technology to analyze those challenging data. Relevant features are automatically identified, while appropriate data can also be combined to multitask networks to evaluate hidden trends among multiple ADME-Tox parameters for implicitly correlated data sets. Here we describe a novel, fully industrialized approach to parametrize and optimize the setup, training, application, and visual interpretation of DNNs to model ADME-Tox data. Investigated properties include microsomal lability in different species, passive permeability in Caco-2/TC7 cells, and logD. Statistical models are developed using up to 50 000 compounds from public or corporate databases. Both the choice of DNN hyperparameters and the type and quantity of molecular descriptors were found to be important for successful DNN modeling. Alternate learning of multiple ADME-Tox properties, resulting in a multitask approach, performs statistically superior on most studied data sets in comparison to DNN single-task models and also provides a scalable method to predict ADME-Tox properties from heterogeneous data. For example, predictive quality using external validation sets was improved from R2 of 0.6 to 0.7 comparing single-task and multitask DNN networks from human metabolic lability data. Besides statistical evaluation, a new visualization approach is introduced to interpret DNN models termed "response map", which is useful to detect local property gradients based on structure fragmentation and derivatization. This method is successfully applied to visualize fragmental contributions to guide further design in drug discovery programs, as illustrated by CRCX3 antagonists and renin inhibitors, respectively.

5.
J Phys Chem Lett ; 9(15): 4457-4462, 2018 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-30020787

RESUMO

X-ray absorption and Auger electron spectroscopies are demonstrated to be powerful tools to unravel the electronic structure of solvated ions. In this work for the first time, we use a combination of these methods in the tender X-ray regime. This allowed us to address electronic transitions from deep core levels, to probe environmental effects, specifically in the bulk of the solution since the created energetic Auger electrons possess large mean free paths, and moreover, to obtain dynamical information about the ultrafast delocalization of the core-excited electron. In the considered exemplary aqueous KCl solution, the solvated isoelectronic K+ and Cl- ions exhibit notably different Auger electron spectra as a function of the photon energy. Differences appear due to dipole-forbidden transitions in aqueous K+ whose occurrence, according to the performed ab initio calculations, becomes possible only in the presence of solvent water molecules.

6.
Nat Commun ; 8(1): 484, 2017 09 07.
Artigo em Inglês | MEDLINE | ID: mdl-28883467

RESUMO

The hypothalamic-pituitary-thyroid (HPT) axis maintains circulating thyroid hormone levels in a narrow physiological range. As axons containing thyrotropin-releasing hormone (TRH) terminate on hypothalamic tanycytes, these specialized glial cells have been suggested to influence the activity of the HPT axis, but their exact role remained enigmatic. Here, we demonstrate that stimulation of the TRH receptor 1 increases intracellular calcium in tanycytes of the median eminence via Gαq/11 proteins. Activation of Gαq/11 pathways increases the size of tanycyte endfeet that shield pituitary vessels and induces the activity of the TRH-degrading ectoenzyme. Both mechanisms may limit the TRH release to the pituitary. Indeed, blocking TRH signaling in tanycytes by deleting Gαq/11 proteins in vivo enhances the response of the HPT axis to the chemogenetic activation of TRH neurons. In conclusion, we identify new TRH- and Gαq/11-dependent mechanisms in the median eminence by which tanycytes control the activity of the HPT axis.The hypothalamic-pituitary-thyroid (HPT) axis regulates a wide range of physiological processes. Here the authors show that hypothalamic tanycytes play a role in the homeostatic regulation of the HPT axis; activation of TRH signaling in tanycytes elevates their intracellular Ca2+ via Gαq/11 pathway, ultimately resulting in reduced TRH release into the pituitary vessels.


Assuntos
Sistema Hipotálamo-Hipofisário/metabolismo , Hipotálamo/citologia , Glândula Tireoide/metabolismo , Animais , Sinalização do Cálcio , Subunidades alfa Gq-G11 de Proteínas de Ligação ao GTP/genética , Subunidades alfa Gq-G11 de Proteínas de Ligação ao GTP/metabolismo , Hipotálamo/metabolismo , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Transgênicos , Receptores do Hormônio Liberador da Tireotropina/agonistas , Receptores do Hormônio Liberador da Tireotropina/genética , Receptores do Hormônio Liberador da Tireotropina/metabolismo , Tireotropina/metabolismo
7.
Bio Protoc ; 7(10)2017 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-28603749

RESUMO

Brain endothelial cells are the major building block of the blood-brain barrier. To study the role of brain endothelial cells in vitro, the isolation of primary cells is of critical value. Here, we describe a protocol in which vessel fragments are isolated from adult mice. After density centrifugation and mild digestion of the fragments, outgrowing endothelial cells are selected by puromycin treatment and grown to confluence within one week.

8.
Ann Neurol ; 82(1): 93-104, 2017 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-28628231

RESUMO

OBJECTIVE: Incontinentia pigmenti (IP) is a genetic disease leading to severe neurological symptoms, such as epileptic seizures, but no specific treatment is available. IP is caused by pathogenic variants that inactivate the Nemo gene. Replacing Nemo through gene therapy might provide therapeutic benefits. METHODS: In a mouse model of IP, we administered a single intravenous dose of the adeno-associated virus (AAV) vector, AAV-BR1-CAG-NEMO, delivering the Nemo gene to the brain endothelium. Spontaneous epileptic seizures and the integrity of the blood-brain barrier (BBB) were monitored. RESULTS: The endothelium-targeted gene therapy improved the integrity of the BBB. In parallel, it reduced the incidence of seizures and delayed their occurrence. Neonate mice intravenously injected with the AAV-BR1-CAG-NEMO vector developed no hepatocellular carcinoma or other major adverse effects 11 months after vector injection, demonstrating that the vector has a favorable safety profile. INTERPRETATION: The data show that the BBB is a target of antiepileptic treatment and, more specifically, provide evidence for the therapeutic benefit of a brain endothelial-targeted gene therapy in IP. Ann Neurol 2017;82:93-104.


Assuntos
Terapia Genética , Incontinência Pigmentar/terapia , Peptídeos e Proteínas de Sinalização Intracelular/genética , Convulsões/terapia , Animais , Barreira Hematoencefálica/metabolismo , Células Cultivadas , Dependovirus , Feminino , Vetores Genéticos/efeitos adversos , Humanos , Incontinência Pigmentar/complicações , Masculino , Camundongos , Camundongos Knockout , Permeabilidade , Convulsões/complicações
9.
J Chem Phys ; 145(23): 234307, 2016 Dec 21.
Artigo em Inglês | MEDLINE | ID: mdl-28010107

RESUMO

High-resolution C 1s near-edge x-ray absorption fine structure (NEXAFS) spectra of naphthalene are investigated. By comparing the spectral signatures of condensed naphthalene molecules with those of naphthalene in the gas phase, we are able to unambiguously identify spectral features which are affected by the intermolecular interactions in the condensed phase. With the help of calculations using time-dependent density-functional theory and the second-order algebraic-diagrammatic construction scheme for the polarization propagator, resonances in the relevant energy range can be assigned to valence and Rydberg-like excitations. Thus, we obtain a more detailed identification of NEXAFS resonances beyond the present literature.

10.
EMBO Mol Med ; 8(6): 609-25, 2016 06.
Artigo em Inglês | MEDLINE | ID: mdl-27137490

RESUMO

Gene therapy critically relies on vectors that combine high transduction efficiency with a high degree of target specificity and that can be administered through a safe intravenous route. The lack of suitable vectors, especially for gene therapy of brain disorders, represents a major obstacle. Therefore, we applied an in vivo screening system of random ligand libraries displayed on adeno-associated viral capsids to select brain-targeted vectors for the treatment of neurovascular diseases. We identified a capsid variant showing an unprecedented degree of specificity and long-lasting transduction efficiency for brain microvasculature endothelial cells as the primary target of selection. A therapeutic vector based on this selected viral capsid was used to markedly attenuate the severe cerebrovascular pathology of mice with incontinentia pigmenti after a single intravenous injection. Furthermore, the versatility of this selection system will make it possible to select ligands for additional in vivo targets without requiring previous identification of potential target-specific receptors.


Assuntos
Encéfalo/patologia , Dependovirus/genética , Células Endoteliais/patologia , Terapia Genética/métodos , Vetores Genéticos , Incontinência Pigmentar/terapia , Microvasos/patologia , Animais , Modelos Animais de Doenças , Injeções Intravenosas , Camundongos , Transdução Genética , Resultado do Tratamento
11.
J Chem Theory Comput ; 12(3): 1314-30, 2016 Mar 08.
Artigo em Inglês | MEDLINE | ID: mdl-26845396

RESUMO

The theoretical simulation of X-ray absorption spectra is in general a challenging task. However, for small and medium-sized organic molecules, the algebraic diagrammatic construction scheme (ADC) for the polarization operator in combination with the core-valence separation approximation (CVS) has proven to yield core-excitation energies and transition moments with almost quantitative accuracy allowing for reliable construction of X-ray absorption spectra. Still, to understand core-excitation processes in detail, it is not sufficient to only compute energies, but also properties like static dipole moments and state densities are important as they provide deeper insight into the nature of core-excited states. Here, we present for the first time an implementation of the intermediate state representation (ISR) approach in combination with the CVS approximation (CVS-ISR), which gives, in combination with the CVS-ADC method, direct access to core-excited state properties. The performance of the CVS-ADC/CVS-ISR approach is demonstrated by means of small- and medium-sized organic molecules. Besides the calculation of core-excited state dipole moments, advanced analyses of core-excited state densities are performed using descriptors like exciton sizes and distances. Plotting electron and hole densities helps to determine the character of the state, and in particular, the investigation of detachment/attachment densities provides information about orbital relaxation effects that are crucial for understanding core excitations.

12.
J Exp Med ; 212(10): 1529-49, 2015 Sep 21.
Artigo em Inglês | MEDLINE | ID: mdl-26347470

RESUMO

Inactivating mutations of the NF-κB essential modulator (NEMO), a key component of NF-κB signaling, cause the genetic disease incontinentia pigmenti (IP). This leads to severe neurological symptoms, but the mechanisms underlying brain involvement were unclear. Here, we show that selectively deleting Nemo or the upstream kinase Tak1 in brain endothelial cells resulted in death of endothelial cells, a rarefaction of brain microvessels, cerebral hypoperfusion, a disrupted blood-brain barrier (BBB), and epileptic seizures. TAK1 and NEMO protected the BBB by activating the transcription factor NF-κB and stabilizing the tight junction protein occludin. They also prevented brain endothelial cell death in a NF-κB-independent manner by reducing oxidative damage. Our data identify crucial functions of inflammatory TAK1-NEMO signaling in protecting the brain endothelium and maintaining normal brain function, thus explaining the neurological symptoms associated with IP.


Assuntos
Encéfalo/irrigação sanguínea , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , MAP Quinase Quinase Quinases/metabolismo , Animais , Barreira Hematoencefálica/metabolismo , Encéfalo/metabolismo , Circulação Cerebrovascular/genética , Células Endoteliais/metabolismo , Células Endoteliais/patologia , Epilepsia/genética , Feminino , Quinase I-kappa B/metabolismo , Incontinência Pigmentar/metabolismo , Incontinência Pigmentar/patologia , Peptídeos e Proteínas de Sinalização Intracelular/genética , MAP Quinase Quinase Quinases/genética , Masculino , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Transgênicos , Ocludina/metabolismo , Fator 6 Associado a Receptor de TNF/metabolismo , Fator de Transcrição RelA/metabolismo
13.
J Comput Chem ; 36(21): 1609-20, 2015 Aug 05.
Artigo em Inglês | MEDLINE | ID: mdl-26119286

RESUMO

We report the development of a set of excited-state analysis tools that are based on the construction of an effective exciton wavefunction and its statistical analysis in terms of spatial multipole moments. This construction does not only enable the quantification of the spatial location and compactness of the individual hole and electron densities but also correlation phenomena can be analyzed, which makes this procedure particularly useful when excitonic or charge-resonance effects are of interest. The methods are first applied to bianthryl with a focus on elucidating charge-resonance interactions. It is shown how these derive from anticorrelations between the electron and hole quasiparticles, and it is discussed how the resulting variations in state characters affect the excited-state absorption spectrum. As a second example, cytosine is chosen. It is illustrated how the various descriptors vary for valence, Rydberg, and core-excited states, and the possibility of using this information for an automatic characterization of state characters is discussed.

14.
J Chem Phys ; 142(21): 214104, 2015 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-26049476

RESUMO

The extended second order algebraic-diagrammatic construction (ADC(2)-x) scheme for the polarization operator in combination with core-valence separation (CVS) approximation is well known to be a powerful quantum chemical method for the calculation of core-excited states and the description of X-ray absorption spectra. For the first time, the implementation and results of the third order approach CVS-ADC(3) are reported. Therefore, the CVS approximation has been applied to the ADC(3) working equations and the resulting terms have been implemented efficiently in the adcman program. By treating the α and ß spins separately from each other, the unrestricted variant CVS-UADC(3) for the treatment of open-shell systems has been implemented as well. The performance and accuracy of the CVS-ADC(3) method are demonstrated with respect to a set of small and middle-sized organic molecules. Therefore, the results obtained at the CVS-ADC(3) level are compared with CVS-ADC(2)-x values as well as experimental data by calculating complete basis set limits. The influence of basis sets is further investigated by employing a large set of different basis sets. Besides the accuracy of core-excitation energies and oscillator strengths, the importance of cartesian basis functions and the treatment of orbital relaxation effects are analyzed in this work as well as computational timings. It turns out that at the CVS-ADC(3) level, the results are not further improved compared to CVS-ADC(2)-x and experimental data, because the fortuitous error compensation inherent in the CVS-ADC(2)-x approach is broken. While CVS-ADC(3) overestimates the core excitation energies on average by 0.61% ± 0.31%, CVS-ADC(2)-x provides an averaged underestimation of -0.22% ± 0.12%. Eventually, the best agreement with experiments can be achieved using the CVS-ADC(2)-x method in combination with a diffuse cartesian basis set at least at the triple-ζ level.

15.
Am J Reprod Immunol ; 74(1): 12-25, 2015 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-25598450

RESUMO

PROBLEM: Previous studies demonstrated a strong association between low androgen levels and reduced capacity to mount an inflammatory response. However, the mechanisms underlying these observations are largely not understood. METHODS OF STUDY: Generation of CD4+CD25+Foxp3+ regulatory T cells in Leydig cell-conditioned media was determined by flow cytometry and ELISA. Influence of testosterone on cytokine response was measured in LPS-stimulated testicular macrophages, Sertoli and peritubular cells. RESULTS: Leydig cell-conditioned media dose-dependently stimulated expression of transcription factor Foxp3 and secretion of IL-10 in splenic CD4+ T cells, an effect abolished by addition of the anti-androgen flutamide. In isolated Sertoli and peritubular cells, testosterone pre-treatment suppressed the LPS-induced inflammatory response on TNF-α mRNA expression, while no effect was evident in testicular macrophages (TM). CONCLUSIONS: Androgens can influence the immune system under normal conditions by the generation and functional differentiation of regulatory T cells and in testicular inflammation by direct effect on Sertoli and peritubular cells.


Assuntos
Fatores de Transcrição Forkhead/biossíntese , Interleucina-10/biossíntese , Células Intersticiais do Testículo/imunologia , Linfócitos T Reguladores/citologia , Testosterona/metabolismo , Antagonistas de Androgênios/farmacologia , Animais , Diferenciação Celular/efeitos dos fármacos , Diferenciação Celular/imunologia , Células Cultivadas , Quimiocina CCL2/biossíntese , Meios de Cultivo Condicionados/farmacologia , Flutamida/farmacologia , Inflamação/imunologia , Interleucina-10/metabolismo , Macrófagos/imunologia , Masculino , RNA Mensageiro/biossíntese , Ratos , Ratos Wistar , Células de Sertoli/imunologia , Linfócitos T Reguladores/imunologia , Testosterona/antagonistas & inibidores , Fator de Crescimento Transformador beta/biossíntese , Fator de Necrose Tumoral alfa/genética
16.
J Comput Chem ; 35(26): 1900-15, 2014 Oct 05.
Artigo em Inglês | MEDLINE | ID: mdl-25130619

RESUMO

Core-level excitations are generated by absorption of high-energy radiation such as X-rays. To describe these energetically high-lying excited states theoretically, we have implemented a variant of the algebraic-diagrammatic construction scheme of second-order ADC(2) by applying the core-valence separation (CVS) approximation to the ADC(2) working equations. Besides excitation energies, the CVS-ADC(2) method also provides access to properties of core-excited states, thereby allowing for the calculation of X-ray absorption spectra. To demonstrate the potential of our implementation of CVS-ADC(2), we have chosen medium-sized molecules as examples that have either biological importance or find application in organic electronics. The calculated results of CVS-ADC(2) are compared with standard TD-DFT/B3LYP values and experimental data. In particular, the extended variant, CVS-ADC(2)-x, provides the most accurate results, and the agreement between the calculated values and experiment is remarkable.

17.
J Chem Theory Comput ; 10(10): 4583-98, 2014 Oct 14.
Artigo em Inglês | MEDLINE | ID: mdl-26588152

RESUMO

X-ray absorption spectroscopy (XAS) is a powerful tool that provides information about the electronic structure of molecules via excitation of electrons from the K-shell core region to the unoccupied molecular levels. These high-lying electronic core-excited states can be accurately calculated using the algebraic-diagrammatic construction scheme of second order ADC(2) by applying the core-valence separation (CVS) approximation to the ADC(2) working equations. For the first time, an efficient implementation of an unrestricted CVS-ADC(2) variant CVS-UADC(2) is presented for the calculation of open-shell molecules by treating α and ß spins separately from each other. The potential of the CVS-UADC(2) method is demonstrated with a set of small organic radicals by comparison with standard TD-DFT/B3LYP values and experimental data. It turns out that the extended variant CVS-UADC(2)-x, in particular, provides the most accurate results with errors of only 0.1% compared to experimental values. This remarkable agreement justifies the prediction of yet nonrecorded experimental XAS spectra like the one of the anthracene cation. The cation exhibits additional peaks due to the half-filled single-occupied molecular orbital, which may help to distinguish cation from the neutral species.

18.
Phys Chem Chem Phys ; 15(28): 11704-16, 2013 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-23753008

RESUMO

The elementary charge and excitation energy transfer steps in a novel symmetric donor-acceptor-donor triad first described in Roland et al. Phys. Chem. Chem. Phys., 2012, 14, 273, consisting of a central perylenediimide moiety as a potential electron acceptor and two identical electron rich bithiophene compounds, have been investigated using quantum chemical methodology. These elementary processes determine the applicability of such systems in photovoltaic devices. The molecular structure, excited states and the photo-physical properties are investigated using smaller model systems and including solvation effects. The donor and acceptor π-systems are separated by an ethyl bridge such that the molecular orbitals are either located on the donor or acceptor moiety making the identification of locally excited versus charge transfer states straightforward. Using excited state geometry optimizations, the mechanism of photo-initiated charge separation could be identified. Geometry relaxation in the excited donor state leads to a near-degeneracy with the locally excited acceptor state, entailing strong excitonic coupling and resonance energy transfer. This energy transfer process is driven by planarization and bond length alternation of the donor molecule. Geometry relaxation of the locally excited acceptor state in turn reveals a crossing with the energetically lowest charge transfer excited state. The energetic position of the latter depends in a sensitive fashion on the solvent. This provides an explanation of the sequential process observed in the experiment, favoring ultrafast (∼130 fs) formation of the excited acceptor state followed by slower (∼3 ps scale) formation of the charge separated state.

19.
Cardiovasc Res ; 93(1): 50-9, 2012 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-21972180

RESUMO

AIMS: Cardiovascular research requires complex and functionally intact experimental models. Due to major differences in the cellular and subcellular composition of the myocardium between species, the use of human heart tissue is highly desirable. To enhance the experimental use of the human myocardium, we established methods for the preparation of vital tissue slices from the adult ventricular myocardium as well as conditions for their long-term preservation in organotypic culture. METHODS AND RESULTS: Human ventricular heart samples were derived from surgical specimens excised during a therapeutic Morrow myectomy and cut into 300 µm thick slices. Slices were either characterized in acute experiments or cultured at a liquid-air interface. Viability and functionality were proven by viability staining, enzyme activity tests, intracellular potential recordings, and force measurements. Precision-cut slices showed high viability throughout 28 days in culture and displayed typical cardiomyocyte action potential characteristics, which enabled pharmacological safety testing on the rapid component of the delayed rectifier potassium current (I(Kr)) and ATP-dependent potassium channels throughout the whole culture period. Constant expression of major ion channels was confirmed by quantitative PCR. Acute slices developed excitation-dependent contractions with a clear preload dependency and a ß-adrenergic response. Contractility and myosin light chain expression decreased during the first days in culture but reached a steady state with reactivity upon ß-adrenergic stimulation being preserved. CONCLUSION: Organotypic heart slices represent a multicellular model of the human myocardium and a novel platform for studies ranging from the investigation of molecular interactions to tissue engineering.


Assuntos
Ventrículos do Coração/anatomia & histologia , Modelos Cardiovasculares , Miocárdio/metabolismo , Técnicas de Cultura de Órgãos/métodos , Adulto , Fenômenos Fisiológicos Cardiovasculares , Fenômenos Eletrofisiológicos , Ventrículos do Coração/cirurgia , Humanos , Contração Miocárdica
20.
Cell Physiol Biochem ; 27(1): 1-12, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-21325816

RESUMO

BACKGROUND/AIMS: Cellular models are an interesting tool to study human heart diseases. To date, research groups mainly focus on mouse models, but important murine physiology is different from human characteristics. Recently, scientists found that the electrophysiology of fish cardiomyocytes largely resembles that of humans. So far, cardiomyocyte models were generated using differentiation medium, were stimulated electrically or, when contracting spontaneously, only did so over a short time period. We established an in vitro spontaneously, long-term beating heart model generated from rainbow trout, with the potential to be used as a new human heart model system because of its electrophysiology. METHODS: Spontaneously contracting 3D cell layers from rainbow trout were generated in vitro and analyzed using PCR and immunochemistry. Further, electrophysiology was measured via intra - and extracellular recordings. RESULTS: Contracting cardiomyogenic aggregates were generated without differentiation medium and were beating autonomously for more than one month. Electrophysiological measurements exhibit that the action potential properties of fish cardiomyocytes in part resemble the characteristics of human cardiomyocytes. The sensitivity of the beating cell aggregates to drugs could also be confirmed. CONCLUSION: Spontaneously contracting cardiomyogenic cell aggregates from rainbow trout generated in vitro are suitable for human heart research and pharmacology.


Assuntos
Miócitos Cardíacos/fisiologia , Agonistas Adrenérgicos beta/farmacologia , Animais , Antiarrítmicos/farmacologia , Biomarcadores/metabolismo , Células Cultivadas , Cromanos/farmacologia , Coração/fisiologia , Humanos , Isoproterenol/farmacologia , Modelos Biológicos , Contração Miocárdica/fisiologia , Miócitos Cardíacos/citologia , Miócitos Cardíacos/metabolismo , Oncorhynchus mykiss , Canais de Potássio/química , Canais de Potássio/metabolismo , Pirrolidinas/farmacologia , Receptores Adrenérgicos beta/química , Receptores Adrenérgicos beta/metabolismo
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