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1.
J Diabetes Sci Technol ; : 19322968241234055, 2024 Mar 08.
Artigo em Inglês | MEDLINE | ID: mdl-38456441

RESUMO

BACKGROUND: The aim of this study was to compare patient-reported outcomes (PROs) in people with type 1 diabetes using either continuous subcutaneous insulin infusion (CSII) with two different insulin patch pumps or multiple daily injections (MDIs). MATERIALS AND METHODS: In this randomized three-arm study, people with type 1 diabetes on MDI therapy were included and used either MDI, the Accu-Chek Solo micropump system (Solo) or Omnipod for 26 weeks. From weeks 26 to 39, all participants used CSII with Solo. Patient-reported outcomes were assessed using the diabetes technology questionnaire (DTQ); in addition, HbA1c values were measured. RESULTS: Overall, 181 participants were randomized (61 MDI arm, 62 Solo arm, 58 Omnipod arm) and 142 completed the study. After 26 weeks in the study, the DTQ "change" score in the Solo group (105.9 [100.6-111.2]; baseline-adjusted mean [95% confidence interval]) was significantly higher than in the MDI group (94.8 [89.6-100.0]) (P = .001). The comparison between the Solo group (105.1 [99.1-111.1]) and the Omnipod group (108.7 [103.1-114.4]) showed no significant differences (P = .382). HbA1c increased by 0.2% ± 0.7% in the MDI group and decreased in both pump groups (Solo group -0.2% ± 0.8% and Omnipod group -0.1% ± 0.8%). Differences in HbA1c between the Solo group and the MDI group were significant (P = .009), but not between the Solo group and the Omnipod group (P = .896). CONCLUSIONS: This study showed that switching from MDI to CSII improves both psychosocial well-being and physiological outcomes. Furthermore, there were no substantial differences between the established and the recently released patch pump. Trial registration at www.clinicaltrials.gov is NCT03478969.

2.
Exp Transl Stroke Med ; 6(1): 3, 2014 Feb 14.
Artigo em Inglês | MEDLINE | ID: mdl-24528872

RESUMO

BACKGROUND AND PURPOSE: Both the immobilization of the unaffected arm combined with physical therapy (forced arm use, FAU) and voluntary exercise (VE) as model for enriched environment are promising approaches to enhance recovery after stroke. The genomic mechanisms involved in long-term plasticity changes after different means of rehabilitative training post-stroke are largely unexplored. The present investigation explored the effects of these physical therapies on behavioral recovery and molecular markers of regeneration after experimental ischemia. METHODS: 42 Wistar rats were randomly treated with either forced arm use (FAU, 1-sleeve plaster cast onto unaffected limb at 8/10 days), voluntary exercise (VE, connection of a freely accessible running wheel to cage), or controls with no access to a running wheel for 10 days starting at 48 hours after photothrombotic stroke of the sensorimotor cortex. Functional outcome was measured using sensorimotor test before ischemia, after ischemia, after the training period of 10 days, at 3 and 4 weeks after ischemia. Global gene expression changes were assessed from the ipsi- and contralateral cortex and the hippocampus. RESULTS: FAU-treated animals demonstrated significantly improved functional recovery compared to the VE-treated group. Both were superior to cage control. A large number of genes are altered by both training paradigms in the ipsi- and contralateral cortex and the hippocampus. Overall, the extent of changes observed correlated well with the functional recovery obtained. One category of genes overrepresented in the gene set is linked to neuronal plasticity processes, containing marker genes such as the NMDA 2a receptor, PKC ζ, NTRK2, or MAP 1b. CONCLUSIONS: We show that physical training after photothrombotic stroke significantly and permanently improves functional recovery after stroke, and that forced arm training is clearly superior to voluntary running training. The behavioral outcomes seen correlate with patterns and extent of gene expression changes in all brain areas examined. We propose that physical training induces a fundamental change in plasticity-relevant gene expression in several brain regions that enables recovery processes. These results contribute to the debate on optimal rehabilitation strategies, and provide a valuable source of molecular entry points for future pharmacological enhancement of recovery.

3.
J Clin Invest ; 124(3): 1114-29, 2014 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-24509078

RESUMO

Auditory prostheses can partially restore speech comprehension when hearing fails. Sound coding with current prostheses is based on electrical stimulation of auditory neurons and has limited frequency resolution due to broad current spread within the cochlea. In contrast, optical stimulation can be spatially confined, which may improve frequency resolution. Here, we used animal models to characterize optogenetic stimulation, which is the optical stimulation of neurons genetically engineered to express the light-gated ion channel channelrhodopsin-2 (ChR2). Optogenetic stimulation of spiral ganglion neurons (SGNs) activated the auditory pathway, as demonstrated by recordings of single neuron and neuronal population responses. Furthermore, optogenetic stimulation of SGNs restored auditory activity in deaf mice. Approximation of the spatial spread of cochlear excitation by recording local field potentials (LFPs) in the inferior colliculus in response to suprathreshold optical, acoustic, and electrical stimuli indicated that optogenetic stimulation achieves better frequency resolution than monopolar electrical stimulation. Virus-mediated expression of a ChR2 variant with greater light sensitivity in SGNs reduced the amount of light required for responses and allowed neuronal spiking following stimulation up to 60 Hz. Our study demonstrates a strategy for optogenetic stimulation of the auditory pathway in rodents and lays the groundwork for future applications of cochlear optogenetics in auditory research and prosthetics.


Assuntos
Estimulação Acústica , Surdez/cirurgia , Optogenética , Animais , Channelrhodopsins , Cóclea/fisiopatologia , Cóclea/cirurgia , Implante Coclear , Estimulação Elétrica , Potenciais Evocados Auditivos , Luz , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Estimulação Luminosa , Ratos , Ratos Transgênicos , Ratos Wistar , Gânglio Espiral da Cóclea/patologia , Gânglio Espiral da Cóclea/fisiopatologia
4.
J Neurochem ; 128(5): 686-700, 2014 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-24117625

RESUMO

The WWC1 gene has been genetically associated with human episodic memory performance, and its product KIdney/BRAin protein (KIBRA) has been shown to interact with the atypical protein kinase protein kinase M ζ (PKMζ). Although recently challenged, PKMζ remains a candidate postsynaptic regulator of memory maintenance. Here, we show that PKMζ is subject to rapid proteasomal degradation and that KIBRA is both necessary and sufficient to counteract this process, thus stabilizing the kinase and maintaining its function for a prolonged time. We define the binding sequence on KIBRA, a short amino acid motif near the C-terminus. Both hippocampal knock-down of KIBRA in rats and KIBRA knock-out in mice result in decreased learning and memory performance in spatial memory tasks supporting the notion that KIBRA is a player in episodic memory. Interestingly, decreased memory performance is accompanied by decreased PKMζ protein levels. We speculate that the stabilization of synaptic PKMζ protein levels by KIBRA may be one mechanism by which KIBRA acts in memory maintenance. KIBRA/WWC1 has been genetically associated with human episodic memory. KIBRA has been shown to be post-synaptically localized, but its function remained obscure. Here, we show that KIBRA shields PKMζ, a kinase previously linked to memory maintenance, from proteasomal degradation via direct interaction. KIBRA levels in the rodent hippocampus correlate closely both to spatial memory performance in rodents and to PKMζ levels. Our findings support a role for KIBRA in memory, and unveil a novel function for this protein.


Assuntos
Proteínas de Transporte/fisiologia , Proteínas Correpressoras/fisiologia , Aprendizagem/fisiologia , Memória/fisiologia , Proteína Quinase C/fisiologia , Sequência de Aminoácidos , Animais , Aprendizagem da Esquiva/fisiologia , Comportamento Animal/fisiologia , Western Blotting , Proteínas de Transporte/metabolismo , Proteínas Correpressoras/metabolismo , Dependovirus/genética , Teste de Complementação Genética , Hipocampo/metabolismo , Hipocampo/fisiologia , Imunoprecipitação , Peptídeos e Proteínas de Sinalização Intracelular , Masculino , Aprendizagem em Labirinto/fisiologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos DBA , Camundongos Knockout , Dados de Sequência Molecular , Fosfoproteínas , Reação em Cadeia da Polimerase , Ligação Proteica , Proteína Quinase C/metabolismo , Ratos , Ratos Wistar , Técnicas Estereotáxicas
5.
Stroke ; 44(10): 2681-7, 2013 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-23963331

RESUMO

BACKGROUND AND PURPOSE: Granulocyte colony-stimulating factor (G-CSF; AX200; Filgrastim) is a stroke drug candidate with excellent preclinical evidence for efficacy. A previous phase IIa dose-escalation study suggested potential efficacy in humans. The present large phase IIb trial was powered to detect clinical efficacy in acute ischemic stroke patients. METHODS: G-CSF (135 µg/kg body weight intravenous over 72 hours) was tested against placebo in 328 patients in a multinational, multicenter, randomized, and placebo-controlled trial (NCT00927836; www.clinicaltrial.gov). Main inclusion criteria were ≤9-hour time window after stroke onset, infarct localization in the middle cerebral artery territory, baseline National Institutes of Health Stroke Scale score range of 6 to 22, and baseline diffusion-weighted imaging lesion size ≥15 mL. Primary and secondary end points were the modified Rankin scale score and the National Institutes of Health Stroke Scale score at day 90, respectively. Data were analyzed using a prespecified model that adjusted for age, National Institutes of Health Stroke Scale score at baseline, and initial infarct volume (diffusion-weighted imaging). RESULTS: G-CSF treatment failed to meet the primary and secondary end points of the trial. For additional end points such as mortality, Barthel index, or infarct size at day 30, G-CSF did not show efficacy either. There was, however, a trend for reduced infarct growth in the G-CSF group. G-CSF showed the expected peripheral pharmacokinetic and pharmacodynamic profiles, with a strong increase in leukocytes and monocytes. In parallel, the cytokine profile showed a significant decrease of interleukin-1. CONCLUSIONS: G-CSF, a novel and promising drug candidate with a comprehensive preclinical and clinical package, did not provide any significant benefit with respect to either clinical outcome or imaging biomarkers. CLINICAL TRIAL REGISTRATION URL: http://www.clinicaltrials.gov. Unique identifier: NCT00927836.


Assuntos
Infarto Encefálico , Fator Estimulador de Colônias de Granulócitos , Acidente Vascular Cerebral , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Infarto Encefálico/diagnóstico por imagem , Infarto Encefálico/tratamento farmacológico , Infarto Encefálico/metabolismo , Imagem de Difusão por Ressonância Magnética/métodos , Feminino , Filgrastim , Fator Estimulador de Colônias de Granulócitos/administração & dosagem , Fator Estimulador de Colônias de Granulócitos/efeitos adversos , Fator Estimulador de Colônias de Granulócitos/farmacocinética , Humanos , Masculino , Pessoa de Meia-Idade , Radiografia , Proteínas Recombinantes/administração & dosagem , Proteínas Recombinantes/efeitos adversos , Proteínas Recombinantes/farmacocinética , Acidente Vascular Cerebral/diagnóstico por imagem , Acidente Vascular Cerebral/tratamento farmacológico , Acidente Vascular Cerebral/metabolismo , Fatores de Tempo
6.
Sci Rep ; 2: 697, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-23019518

RESUMO

We recently reported expression of hematopoietic growth factor GM-CSF and its receptor (GM-CSFR) in CNS neurons. Here we evaluated this system in learning and memory formation using GM-CSF deficient mice. In complementation, GM-CSF signalling was manipulated specifically in adult murine hippocampus by adeno-associated virus (AAV)-mediated GM-CSFR alpha overexpression or knock-down. GM-CSF ablation caused various hippocampus and amygdala-dependent deficits in spatial and fear memory while rendering intact basic parameters like motor function, inherent anxiety, and pain threshold levels. Corroborating these data, spatial memory of AAV-injected mice was positively correlated with GM-CSFRα expression levels. Hippocampal neurons of knock-out mice showed markedly pruned dendritic trees, reduced spine densities, and lower percentages of mature spines. Despite such morphological alterations, long-term potentiation (LTP) was unimpaired in the knock-out hippocampus. Collectively, these results suggest that GM-CSF signalling plays a major role in structural plasticity relevant to learning and memory.


Assuntos
Cognição/fisiologia , Fator Estimulador de Colônias de Granulócitos e Macrófagos/genética , Fator Estimulador de Colônias de Granulócitos e Macrófagos/metabolismo , Animais , Ansiedade/genética , Ansiedade/metabolismo , Comportamento Animal , Dependovirus/genética , Vetores Genéticos/genética , Hipocampo/metabolismo , Hipocampo/patologia , Potenciação de Longa Duração , Masculino , Aprendizagem em Labirinto , Memória , Camundongos , Camundongos Knockout , Destreza Motora , Neurônios/citologia , Neurônios/metabolismo , Receptores de Fator Estimulador das Colônias de Granulócitos e Macrófagos/genética , Receptores de Fator Estimulador das Colônias de Granulócitos e Macrófagos/metabolismo , Transdução Genética
7.
Stroke ; 43(5): 1266-72, 2012 May.
Artigo em Inglês | MEDLINE | ID: mdl-22403046

RESUMO

BACKGROUND AND PURPOSE: Age and National Institutes of Health Stroke Scale early after stroke onset have been identified as important determinants of final stroke outcome. We analyzed the Virtual International Stroke Trials Archive (VISTA) database to define the influence of infarct or hemorrhagic volume on clinical outcome after stroke. METHODS: All patients were extracted from VISTA where infarct or hemorrhage volume information was available (n=2538; most images obtained by CT within 72 hours after stroke onset with a subset of MRI data included, volumes calculated by the ABC/2 approximation method). We used multivariate regression models to study the influence of age, National Institutes of Health Stroke Scale at baseline, and initial infarct/hemorrhage volume on clinical outcome (modified Rankin Scale, National Institutes of Health Stroke Scale, mortality) at day 90. RESULTS: We find that in a large cohort of >1800 patients with ischemic stroke, initial lesion size is a strong and independent predictor of stroke outcome in a statistical regression model that also accounts for age and National Institutes of Health Stroke Scale at baseline (P<0.0001). The use of infarct/hemorrhage volume as an additional predictive factor further reduces the fraction of unexplained variance in outcome by approximately 15% (R(2) of 0.41 versus 0.26 in a model without lesion volume). The predictive strength of initial lesion size is only marginally influenced by image modality or time point of image acquisition within the first 72 hours. The model was equally valid for both ischemic and hemorrhagic strokes. CONCLUSIONS: Infarct/hemorrhage volume at baseline together with age and National Institutes of Health Stroke Scale at baseline should be used in the effect analysis of future therapeutic stroke trials to improve power.


Assuntos
Infarto Encefálico/patologia , Bases de Dados Factuais , Saúde Global , Hemorragias Intracranianas/patologia , Acidente Vascular Cerebral/diagnóstico , Acidente Vascular Cerebral/patologia , Fatores Etários , Idoso , Estudos de Coortes , Feminino , Humanos , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Valor Preditivo dos Testes , Prognóstico , Análise de Regressão , Estudos Retrospectivos , Fatores de Tempo
8.
PLoS One ; 7(1): e29880, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22253813

RESUMO

Granulocyte-colony stimulating factor (G-CSF) improves outcome after experimental SCI by counteracting apoptosis, and enhancing connectivity in the injured spinal cord. Previously we have employed the mouse hemisection SCI model and studied motor function after subcutaneous or transgenic delivery of the protein. To further broaden confidence in animal efficacy data we sought to determine efficacy in a different model and a different species. Here we investigated the effects of G-CSF in Wistar rats using the New York University Impactor. In this model, corroborating our previous data, rats treated subcutaneously with G-CSF over 2 weeks show significant improvement of motor function.


Assuntos
Fator Estimulador de Colônias de Granulócitos/farmacologia , Fator Estimulador de Colônias de Granulócitos/uso terapêutico , Atividade Motora/efeitos dos fármacos , Recuperação de Função Fisiológica/efeitos dos fármacos , Traumatismos da Medula Espinal/tratamento farmacológico , Traumatismos da Medula Espinal/fisiopatologia , Animais , Modelos Animais de Doenças , Feminino , Camundongos , Ratos , Ratos Wistar , Resultado do Tratamento
9.
PLoS One ; 6(5): e19767, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-21625426

RESUMO

BACKGROUND: G-CSF has been shown in animal models of stroke to promote functional and structural regeneration of the central nervous system. It thus might present a therapy to promote recovery in the chronic stage after stroke. METHODS: Here, we assessed the safety and tolerability of G-CSF in chronic stroke patients with concomitant vascular disease, and explored efficacy data. 41 patients were studied in a double-blind, randomized approach to either receive 10 days of G-CSF (10 µg/kg body weight/day), or placebo. Main inclusion criteria were an ischemic infarct >4 months prior to inclusion, and white matter hyperintensities on MRI. Primary endpoint was number of adverse events. We also explored changes in hand motor function for activities of daily living, motor and verbal learning, and finger tapping speed, over the course of the study. RESULTS: Adverse events (AEs) were more frequent in the G-CSF group, but were generally graded mild or moderate and from the known side-effect spectrum of G-CSF. Leukocyte count rose after day 2 of G-CSF dosing, reached a maximum on day 8 (mean 42/nl), and returned to baseline 1 week after treatment cessation. No significant effect of treatment was detected for the primary efficacy endpoint, the test of hand motor function. CONCLUSIONS: These results demonstrate the feasibility, safety and reasonable tolerability of subcutaneous G-CSF in chronic stroke patients. This study thus provides the basis to explore the efficacy of G-CSF in improving chronic stroke-related deficits. TRIAL REGISTRATION: ClinicalTrials.gov NCT00298597.


Assuntos
Fator Estimulador de Colônias de Granulócitos/uso terapêutico , Acidente Vascular Cerebral/tratamento farmacológico , Doenças Vasculares/tratamento farmacológico , Idoso , Idoso de 80 Anos ou mais , Cognição/efeitos dos fármacos , Estudos de Coortes , Método Duplo-Cego , Estudos de Viabilidade , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Atividade Motora/efeitos dos fármacos , Acidente Vascular Cerebral/complicações , Doenças Vasculares/etiologia
10.
Stroke ; 41(11): 2545-51, 2010 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-20947859

RESUMO

BACKGROUND AND PURPOSE: Granulocyte colony-stimulating factor (G-CSF) is a promising stroke drug candidate. The present phase IIa study assessed safety and tolerability over a broad dose range of G-CSF doses in acute ischemic stroke patients and explored outcome data. METHODS: Four intravenous dose regimens (total cumulative doses of 30-180 µg/kg over the course of 3 days) of G-CSF were tested in 44 patients in a national, multicenter, randomized, placebo-controlled dose escalation study (NCT00132470; www.clinicaltrial.gov). Main inclusion criteria were a 12-hour time window after stroke onset, infarct localization to the middle cerebral artery territory, a baseline National Institutes of Health Stroke Scale range of 4 to 22, and presence of diffusion-weighted imaging/perfusion-weighted imaging mismatch. RESULTS: Concerning the primary safety end points, we observed no increase of thromboembolic events in the active treatment groups, and no increase in related serious adverse events. G-CSF led to expected increases in neutrophils and monocytes that resolved rapidly after end of treatment. We observed a clinically insignificant drug-related decrease of platelets. As expected from the low number of patients, we did not observe significant differences in clinical outcome in treatment vs. placebo. In exploratory analyses, we observed an interesting dose-dependent beneficial effect of treatment in patients with DWI lesions > 14-17 cm³. CONCLUSIONS: We conclude that G-CSF was well-tolerated even at high dosages in patients with acute ischemic stroke, and that a substantial increase in leukocytes appears not problematic in stroke patients. In addition, exploratory analyses suggest treatment effects in patients with larger baseline diffusion-weighted imaging lesions. The obtained data provide the basis for a second trial aimed to demonstrate safety and efficacy of G-CSF on clinical end points.


Assuntos
Fator Estimulador de Colônias de Granulócitos/efeitos adversos , Fator Estimulador de Colônias de Granulócitos/uso terapêutico , Acidente Vascular Cerebral/tratamento farmacológico , Idoso , Idoso de 80 Anos ou mais , Contagem de Células , Relação Dose-Resposta a Droga , Método Duplo-Cego , Estudos de Viabilidade , Feminino , Alemanha , Fator Estimulador de Colônias de Granulócitos/administração & dosagem , Humanos , Injeções Intravenosas , Leucócitos/patologia , Masculino , Pessoa de Meia-Idade , Acidente Vascular Cerebral/patologia , Acidente Vascular Cerebral/fisiopatologia , Resultado do Tratamento
11.
BMC Genomics ; 8: 370, 2007 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-17937787

RESUMO

BACKGROUND: The different physiological repertoire of CA3 and CA1 neurons in the hippocampus, as well as their differing behaviour after noxious stimuli are ultimately based upon differences in the expressed genome. We have compared CA3 and CA1 gene expression in the uninjured brain, and after cerebral ischemia using laser microdissection (LMD), RNA amplification, and array hybridization. RESULTS: Profiling in CA1 vs. CA3 under normoxic conditions detected more than 1000 differentially expressed genes that belong to different, physiologically relevant gene ontology groups in both cell types. The comparison of each region under normoxic and ischemic conditions revealed more than 5000 ischemia-regulated genes for each individual cell type. Surprisingly, there was a high co-regulation in both regions. In the ischemic state, only about 100 genes were found to be differentially expressed in CA3 and CA1. The majority of these genes were also different in the native state. A minority of interesting genes (e.g. inhibinbetaA) displayed divergent expression preference under native and ischemic conditions with partially opposing directions of regulation in both cell types. CONCLUSION: The differences found in two morphologically very similar cell types situated next to each other in the CNS are large providing a rational basis for physiological differences. Unexpectedly, the genomic response to ischemia is highly similar in these two neuron types, leading to a substantial attenuation of functional genomic differences in these two cell types. Also, the majority of changes that exist in the ischemic state are not generated de novo by the ischemic stimulus, but are preexistant from the genomic repertoire in the native situation. This unexpected influence of a strong noxious stimulus on cell-specific gene expression differences can be explained by the activation of a cell-type independent conserved gene-expression program. Our data generate both novel insights into the relation of the quiescent and stimulus-induced transcriptome in different cells, and provide a large dataset to the research community, both for mapping purposes, as well as for physiological and pathophysiological research.


Assuntos
Isquemia Encefálica/genética , Genoma , Neurônios/metabolismo , Animais , Perfilação da Expressão Gênica , Imuno-Histoquímica , Ratos
12.
Nucleic Acids Res ; 35(14): 4640-8, 2007.
Artigo em Inglês | MEDLINE | ID: mdl-17591615

RESUMO

Development and refinement of methods to analyse differential gene expression has been essential in the progress of molecular biology. A novel approach called iGentifier is presented for profiling known and unknown transcriptomes, thus bypassing a major limitation in microarray analysis. The iGentifier technology combines elements of fragment display (e.g. Differential Display or RMDD) and tag sequencing (e.g. SAGE, MPSS) and allows for analysis of samples in high throughput using current capillary electrophoresis equipment. Application to epidermal tissue of wild-type and mlo5 barley (Hordeum vulgare) plants, infected with powdery mildew [Blumeria graminis (DC.) E.O. Speer f.sp.hordei], led to the identification of several 100 genes induced or repressed upon infection with many well known for their response to fungal pathogens or other stressors. Ten of these genes are suggested to be classified as marker genes for durable resistance mediated by the mlo5 resistance gene.


Assuntos
Perfilação da Expressão Gênica/métodos , Regulação da Expressão Gênica de Plantas , Hordeum/genética , Hordeum/metabolismo , Hordeum/microbiologia , RNA de Plantas/metabolismo , Reprodutibilidade dos Testes , Sitios de Sequências Rotuladas
13.
Phys Chem Chem Phys ; 9(20): 2470-97, 2007 May 28.
Artigo em Inglês | MEDLINE | ID: mdl-17508081

RESUMO

We review the progress in controlling quantum dynamical processes in the condensed phase with femtosecond laser pulses. Due to its high particle density the condensed phase has both high relevance and appeal for chemical synthesis. Thus, in recent years different methods have been developed to manipulate the dynamics of condensed-phase systems by changing one or multiple laser pulse parameters. Single-parameter control is often achieved by variation of the excitation pulse's wavelength, its linear chirp or its temporal subpulse separation in case of pulse sequences. Multiparameter control schemes are more flexible and provide a much larger parameter space for an optimal solution. This is realized in adaptive femtosecond quantum control, in which the optimal solution is iteratively obtained through the combination of an experimental feedback signal and an automated learning algorithm. Several experiments are presented that illustrate the different control concepts and highlight their broad applicability. These fascinating achievements show the continuous progress on the way towards the control of complex quantum reactions in the condensed phase.


Assuntos
Teoria Quântica , Animais , Drosophila/citologia , Drosophila/embriologia , Cinética , Lasers , Modelos Moleculares , Fatores de Tempo
14.
J Chem Phys ; 125(4): 44512, 2006 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-16942161

RESUMO

Recently, optimal control of a photoisomerization reaction in the liquid phase was demonstrated for the first time on the system 3,3(')-diethyl-2,2(')-thiacyanine (NK88). Additionally, the class of cyanines to which the molecule NK88 belongs draws a lot of attention in different recent theoretical publications. Therefore, a better understanding of the molecular dynamics of this molecular system is of special interest. Experiments using the femtosecond pump-supercontinuum probe technique with an excitation wavelength of 400 nm and a spectral range from 370 to 620 nm for the probe beam have been performed. In order to analyze the dynamics properly the time window has been chosen to comprise the characteristic times of the contributing processes, additionally we have employed two solvents, methanol and ethylene glycol, and have conducted anisotropy measurements. The spectroscopic data have been assigned to different molecular states with the help of density functional theory and second-order Moller-Plesset perturbation theory calculations. The analysis of the data has revealed in the most likely model that three different isomers exist with different lifetimes. On the basis of experimental and theoretical data, a conclusive scheme of the isomerization reaction is presented.


Assuntos
Carbocianinas/química , Citosina/análogos & derivados , Luz , Fotoquímica/métodos , Anisotropia , Citosina/química , Etilenoglicol/química , Lasers , Metanol/química , Modelos Moleculares , Modelos Estatísticos , Conformação Molecular , Software , Espectrofotometria , Temperatura , Termodinâmica , Fatores de Tempo
15.
J Chem Phys ; 125(4): 44513, 2006 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-16942162

RESUMO

The molecule 3,3(')-diethyl-2,2(')-thiacyanine isomerizes after irradiation with light of the proper wavelength. After excitation, it undergoes a transition, in which one or more conical intersections are involved, back to the ground state to form different product photoisomers. The dynamics before and directly after the transition back to the ground state is investigated by transient absorption spectroscopy in a wavelength region of 360-950 nm, as well as by fluorescence upconversion. It is shown that the excited-state dynamics are governed by two time scales: a short one with a decay time of less than 2 ps and a long one with about 9 ps. A thorough comparison of the experimental results with those of configuration interaction singles and time-dependent density functional theory calculations suggests that these dynamics are related to two competing pathways differing in the molecular twisting on the excited surface after photoexcitation. From the experimental point of view this picture arises taking into account the time scales for ground-state bleach, excited-state absorption, stimulated emission, fluorescence, and assumed hot ground-state absorption both in the solvent methanol and ethylene glycol.


Assuntos
Citosina/análogos & derivados , Luz , Fotoquímica/métodos , Absorção , Anisotropia , Carbocianinas , Citosina/química , Etilenoglicol/química , Lasers , Metanol/química , Modelos Moleculares , Conformação Molecular , Software , Espectrofotometria , Temperatura , Termodinâmica , Fatores de Tempo
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