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1.
Z Gastroenterol ; 2024 Apr 24.
Artículo en Alemán | MEDLINE | ID: mdl-38657618

RESUMEN

Iron deficiency is the predominant cause of anemia. Iron deficiency anemia plays a major role, especially in patients with inflammatory bowel disease (IBD), and is the most common extraintestinal manifestation and IBD-associated systemic complication. The presence of anemia leads to a reduction in quality of life in patients with IBD associated with limitations in physical, emotional, and cognitive function. In addition, it is associated with an increased hospitalization rate. For this reason, iron supplementation is of particular importance. Oral and intravenous iron supplements are used to treat iron deficiency. Due to the lack of absorption and gastrointestinal side effects of oral substitution, intravenous supplementation is becoming increasingly important. However, there are still certain concerns about intravenous administration.With the help of this review, we want to address the topic of iron substitution in patients with IBD, summarize current guideline recommendations, and provide a practical approach.

2.
Z Gastroenterol ; 61(6): 690-700, 2023 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-36257329

RESUMEN

Although the management of patients with ulcerative colitis (UC) is well defined by national and international guidelines, there are many debates and open questions related to daily care of UC patients. Here, we aimed to review topics with high clinical relevance including therapy algorithms, potential biomarkers for disease prognosis and response to therapy, the role of interventions targeting the gut microbiota, insights from head-to-head trials, novel UC medications, exit strategies, the impact of COVID19 on UC, care of patients with acute severe disease, cancer screening, and the role of surgery.


Asunto(s)
COVID-19 , Colitis Ulcerosa , Microbioma Gastrointestinal , Humanos , Colitis Ulcerosa/terapia , Colitis Ulcerosa/tratamiento farmacológico , Atención al Paciente
3.
J Med Internet Res ; 24(10): e37497, 2022 10 05.
Artículo en Inglés | MEDLINE | ID: mdl-36197717

RESUMEN

BACKGROUND: Gastrointestinal diseases are associated with substantial cost in health care. In times of the COVID-19 pandemic and further digitalization of gastrointestinal tract health care, mobile health apps could complement routine health care. Many gastrointestinal health care apps are already available in the app stores, but the quality, data protection, and reliability often remain unclear. OBJECTIVE: This systematic review aimed to evaluate the quality characteristics as well as the privacy and security measures of mobile health apps for the management of gastrointestinal diseases. METHODS: A web crawler systematically searched for mobile health apps with a focus on gastrointestinal diseases. The identified mobile health apps were evaluated using the Mobile Application Rating Scale (MARS). Furthermore, app characteristics, data protection, and security measures were collected. Classic user star rating was correlated with overall mobile health app quality. RESULTS: The overall quality of the mobile health apps (N=109) was moderate (mean 2.90, SD 0.52; on a scale ranging from 1 to 5). The quality of the subscales ranged from low (mean 1.89, SD 0.66) to good (mean 4.08, SD 0.57). The security of data transfer was ensured only by 11 (10.1%) mobile health apps. None of the mobile health apps had an evidence base. The user star rating did not correlate with the MARS overall score or with the individual subdimensions of the MARS (all P>.05). CONCLUSIONS: Mobile health apps might have a positive impact on diagnosis, therapy, and patient guidance in gastroenterology in the future. We conclude that, to date, data security and proof of efficacy are not yet given in currently available mobile health apps.


Asunto(s)
COVID-19 , Enfermedades Gastrointestinales , Aplicaciones Móviles , Telemedicina , Enfermedades Gastrointestinales/terapia , Humanos , Pandemias , Reproducibilidad de los Resultados
4.
BMC Geriatr ; 21(1): 646, 2021 11 16.
Artículo en Inglés | MEDLINE | ID: mdl-34784883

RESUMEN

BACKGROUND: Among potentially modifiable risk factors for delirium, transfers between wards, hospitals and other facilities have been mentioned with low evidence. TRADE (TRAnsport and DElirium in older people) was set up to investigate i) the impact of transfer and/or discharge on the onset of delirium in older adults and ii) feasibility and acceptance of a developed complex intervention targeting caregiver's participation during and after hospital discharge or transfer on cognition and the onset of delirium in older adults. METHODS: The study is designed according to the guidelines of the UK Medical Research Council (MRC) for development and evaluation of complex interventions and comprises two steps: development and feasibility/piloting. The development phase includes i) a multicenter observational prospective cohort study to assess delirium incidence and cognitive decline associated with transfer and discharge, ii) a systematic review of the literature, iii) stakeholder focus group interviews and iv) an expert workshop followed by a Delphi survey. Based on this information, a complex intervention to better and systematically involve family caregivers in discharge and transport was developed. The intervention will be tested in a pilot study using a stepped wedge design with a detailed process and health economic evaluation. The study is conducted at four acute care hospitals in southwest Germany. Primary endpoints are the delirium incidence and cognitive function. Secondary endpoints include prevalence of caregiver companionship, functional decline, cost and cost effectiveness, quality of discharge management and quality of admission management in admitting hospitals or nursing homes. Data will be collected prior to discharge as well as after 3, 7 and 90 days. DISCUSSION: TRADE will help to evaluate transfer and discharge as a possible risk factor for delirium. In addition, TRADE evaluates the impact and modifiability of caregiver's participation during patient's transfer or discharge on delirium incidence and cognitive decline providing the foundation for a confirmatory implementation study. TRIAL REGISTRATION: DRKS (Deutsches Register für klinische Studien) DRKS00017828 . Registered on 17th September 2019. Retrospectively registered.


Asunto(s)
Delirio , Alta del Paciente , Anciano , Cuidadores , Delirio/diagnóstico , Delirio/epidemiología , Delirio/prevención & control , Hospitales , Humanos , Estudios Multicéntricos como Asunto , Proyectos Piloto , Estudios Prospectivos , Revisiones Sistemáticas como Asunto
5.
Z Gastroenterol ; 59(5): 438-445, 2021 May.
Artículo en Inglés | MEDLINE | ID: mdl-33752244

RESUMEN

OBJECTIVES: This study aimed to compare spleen sizes in a hospital and a population sample using ultrasound and define normal values and factors influencing spleen size. METHODS: Both samples' spleen sizes (n = 1520) were measured using ultrasound under the same conditions. Blood counts and other laboratory parameters were determined under the same conditions in both samples. RESULTS: In the hospital sample (n = 760), the mean spleen size was 114.7 mm, and in the population sample (n = 760), it was 99.1 mm. In both, spleen size in men was significantly higher than in women (p < 0.0001) and influenced by body height, weight, and BMI (body mass index) (p < 0.0001). In the hospital sample, there was a correlation with higher values for ALT (p = 0.0160), AST (p = 0.0394), AP (p = 0.0482), and ferritin (p = 0.0008) and lower values for HDL (p = 0.0091) and thrombocytes (p < 0.0001). In the multivariate analysis, higher values for AP (p = 0.0059) and lower values for hemoglobin (p = 0.0014) and thrombocytes (p = 0.0001) were found. Stratified for sex (men, women), spleen size increased with higher values for ALT (p = 0.0116, p = 0.0113), AST (p = 0.0014, p = 0.0113), and AP (p = 0.0001, p = 0.0012), and with lower values of hemoglobin (p = 0.0057, p = 0.0016), thrombocytes (p < 0.0001, p = 0.0003), and albumin (p = 0.0029, p = 0.0432). In women, there was a discordant correlation with red blood cells (p = 0.0005) and a concordant correlation with GGT (p = 0.0241), and in men discordant correlations with cholesterol (p = 0.0010) and HDL (p = 0.0404). CONCLUSIONS: The already proven impact of anthropometric data on spleen size was confirmed. The role of laboratory values should be further analyzed.


Asunto(s)
Hospitales , Bazo , Índice de Masa Corporal , Femenino , Humanos , Masculino , Valores de Referencia , Bazo/diagnóstico por imagen , Ultrasonografía
6.
Z Gerontol Geriatr ; 54(2): 106-112, 2021 Mar.
Artículo en Alemán | MEDLINE | ID: mdl-32112273

RESUMEN

BACKGROUND: The geriatric check was developed for identification of geriatric patients in emergency departments (ED) as part of the concept for geriatric care in Baden-Württemberg. AIM: Determination of convergent and predictive validity of the geriatric check with respect to identification and outcome prediction of geriatric patients in the ED. MATERIAL AND METHODS: A prospective cohort study between November 2015 and April 2016 including 146 patients older than 70 years in the internal medicine ED of Ulm University Hospital. Separate assessment by physicians and nursing staff of the following: identification of seniors at risk (ISAR), geriatric check, additional cognitive and functional assessments and for outcome: change in care index, Barthel index, living arrangements. RESULTS: The ISAR classified 117 patients as geriatric patients and the geriatric check 107. The correlation was 78.1%. With ISAR as the gold standard the geriatric check showed a sensitivity of 82.0% and a specificity of 62.1%. The positive and negative predictive values were 89.7% and 46.1%, respectively. The identification by simple estimation was better for nurses than for doctors (sensitivity 70.5% vs. 58%, specificity 88.9% vs. 83.3%). The predictive validity 5 months after admission with respect to the abovementioned outcome parameters was best for nurses and doctors (especially regarding specificity). Both tests were very sensitive but not very specific. DISCUSSION: The geriatric check is comparable to the ISAR. The convergent validity showed little difference. Both the ISAR and geriatric check were slightly more sensitive than doctors and nurses. Regarding predictive validity, doctors and nurses were superior to both scores. An algorithm starting with ISAR or geriatric check and followed by an estimation by doctors or nurses could be most suitable for optimal resource allocation.


Asunto(s)
Servicio de Urgencia en Hospital , Evaluación Geriátrica , Anciano , Hospitalización , Humanos , Estudios Prospectivos , Medición de Riesgo
7.
Z Gerontol Geriatr ; 54(7): 708-716, 2021 Nov.
Artículo en Alemán | MEDLINE | ID: mdl-34351485

RESUMEN

The term frailty describes a complex syndrome of reduced resistance to stress factors as a consequence of age-related degeneration in various organ systems.In the general population frailty is associated with poor clinical outcomes, including an increased risk of falls, hospitalization, functional impairment and mortality. Frailty occurs earlier and its prevalence is higher in patients with chronic kidney disease (CKD) compared to the general population. Frail patients with CKD, on dialysis or not, have reduced quality of life and increased hospitalization and mortality rates, regardless of age, sex or comorbidities.The identification of frailty in patients with CKD can lead to the detection of important and potentially modifiable risk factors. Early nephrological evaluation coupled with an interdisciplinary approach including primary care physicians, geriatricians, physiotherapists, occupational therapists and nutritionists, is fundamental in the prevention of frailty as well as in the management of frail patients with CKD.Several instruments have been developed to screen for and assess the degree of frailty; however, there is currently no recommendation as to which should be used in nephrology and how to manage frail patients with CKD. In this article we suggest an approach based on a multidimensional, interdisciplinary evaluation aimed at the early identification and management of frail CKD patients independent of the clinical setting of admission; however, more important than the method used is the need to identify and follow-up on frail CKD patients.


Asunto(s)
Fragilidad , Insuficiencia Renal Crónica , Anciano , Anciano Frágil , Fragilidad/diagnóstico , Fragilidad/epidemiología , Evaluación Geriátrica , Humanos , Calidad de Vida , Diálisis Renal , Insuficiencia Renal Crónica/diagnóstico , Insuficiencia Renal Crónica/epidemiología , Insuficiencia Renal Crónica/terapia
8.
Langmuir ; 36(29): 8485-8493, 2020 07 28.
Artículo en Inglés | MEDLINE | ID: mdl-32506911

RESUMEN

Polymer brushes not only represent emerging surface platforms for numerous bioanalytical and biological applications but also create advanced surface-tethered systems to mimic real-life biological processes. In particular, zwitterionic and nonionic polymer brushes have been intensively studied because of their extraordinary resistance to nonspecific adsorption of biomolecules (antifouling characteristics) as well as the ability to be functionalized with bioactive molecules. However, the relation between antifouling behavior in real-world biological media and structural changes of polymer brushes induced by surface preconditioning in different environments remains unexplored. In this work, we use multiple methods to study the structural properties of numerous brushes under variable ionic concentrations and determine the impact of these changes on resistance to fouling from undiluted blood plasma. We describe different mechanisms of swelling, depending on both the polymer brush coating properties and the environmental conditions that affect changes in both hydration levels and thickness. Using both fluorescent and surface plasmon resonance methods, we found that the antifouling behavior of these brushes is strongly dependent on the aforementioned structural changes. Moreover, preconditioning of the brush coatings (incubation at a variable salt concentration or drying) prior to biomolecule interaction may significantly improve the antifouling performance. These results suggest a new simple approach to improve the antifouling behavior of polymer brushes. In addition, the results herein enhance the understanding for improved design of antifouling and bioresponsive brushes employed in biosensor and biomimetic applications.

9.
Philos Trans A Math Phys Eng Sci ; 378(2185): 20190615, 2020 Nov 27.
Artículo en Inglés | MEDLINE | ID: mdl-33070751

RESUMEN

In this paper, we introduce a general framework to study linear first-order evolution equations on a Banach space X with dynamic boundary conditions, that is with boundary conditions containing time derivatives. Our method is based on the existence of an abstract Dirichlet operator and yields finally to equivalent systems of two simpler independent equations. In particular, we are led to an abstract Cauchy problem governed by an abstract Dirichlet-to-Neumann operator on the boundary space ∂X. Our approach is illustrated by several examples and various generalizations are indicated. This article is part of the theme issue 'Semigroup applications everywhere'.

10.
Z Gastroenterol ; 58(5): 439-444, 2020 May.
Artículo en Inglés | MEDLINE | ID: mdl-32045954

RESUMEN

BACKGROUND AND AIM: The role of therapeutic drug monitoring (TDM) in ustekinumab (UST) therapy for Crohn's disease (CD) has not been established, as only few studies have analyzed the relationship between UST serum concentrations and clinical outcome. In this pilot study, we retrospectively examined the potential of UST-concentrations (cUST) 8 weeks after induction (cUSTw8) to predict clinical response at week 16. METHODS: Serum samples and clinical data from patients (n = 72) with moderate to severely active CD who received intravenous induction with UST were retrospectively analyzed. cUST were quantitated using liquid chromatography-tandem mass spectrometry (LC-MSMS). A receiver-operating characteristic (ROC) curve and area under ROC curve (AUROC) was computed to analyze the predictive potential of cUSTw8 for clinical response at week 16 and to determine the minimal therapeutic UST trough concentration. RESULTS: Forty-four patients (61 %) achieved clinical response to UST therapy at week 16. cUSTw8 was moderately effective to predict clinical response with a minimal therapeutic cUSTw8 of 2.0 mg/l (AUC 0.72, p = 0.001). CONCLUSION: Trough concentrations of UST 8 weeks after induction predict clinical response to therapy in week 16 with moderate sensitivity and specificity. TDM using LC-MSMS could prove beneficial in personalized UST therapy of patients with CD by identifying individuals with subtherapeutic concentrations who might benefit from dose escalation.


Asunto(s)
Enfermedad de Crohn/tratamiento farmacológico , Fármacos Dermatológicos/uso terapéutico , Factores Inmunológicos/farmacología , Ustekinumab/uso terapéutico , Biomarcadores/análisis , Cromatografía Liquida , Enfermedad de Crohn/sangre , Fármacos Dermatológicos/sangre , Humanos , Factores Inmunológicos/administración & dosificación , Proyectos Piloto , Curva ROC , Estudios Retrospectivos , Espectrometría de Masas en Tándem , Resultado del Tratamiento , Ustekinumab/sangre
11.
Langmuir ; 35(9): 3479-3489, 2019 03 05.
Artículo en Inglés | MEDLINE | ID: mdl-30742441

RESUMEN

Catalysis by enzymes on surfaces has many applications. However, strategies for efficient enzyme immobilization with preserved activity are still in need of further development. In this work, we investigate polyelectrolyte brushes prepared by both grafting-to and grafting-from with the aim to achieve high catalytic activity. For comparison, self-assembled monolayers that bind enzymes with the same chemical interactions are included. We use the model enzyme glucose oxidase and two kinds of polymers: anionic poly(acrylic acid) and cationic poly(diethylamino)methyl methacrylate. Surface plasmon resonance and spectroscopic ellipsometry are used for accurate quantification of surface coverage. Besides binding more enzymes, the "3D-like" brush environment enhances the specific activity compared to immobilization on self-assembled monolayers. For grafting-from brushes, multilayers of enzymes were spontaneously and irreversibly immobilized without conjugation chemistry. When the pH was between the pI of the enzyme and the p Ka of the polymer, binding was considerable (thousands of ng/cm2 or up to 50% of the polymer mass), even at physiological ionic strength. However, binding was observed also when the brushes were neutrally charged. For acidic brushes (both grafting-to and grafting-from), the activity was higher for covalent immobilization compared to noncovalent. For grafting-from brushes, a fully preserved specific activity compared to enzymes in the liquid bulk was achieved, both with covalent (acidic brush) and noncovalent (basic brush) immobilization. Catalytic activity of hundreds of pmol cm-2 s-1 was easily obtained for polybasic brushes only tens of nanometers in dry thickness. This study provides new insights for designing functional interfaces based on enzymatic catalysis.


Asunto(s)
Enzimas Inmovilizadas/metabolismo , Glucosa Oxidasa/metabolismo , Polielectrolitos/metabolismo , Resinas Acrílicas/química , Resinas Acrílicas/metabolismo , Adsorción , Enzimas Inmovilizadas/química , Glucosa Oxidasa/química , Concentración de Iones de Hidrógeno , Interacciones Hidrofóbicas e Hidrofílicas , Metacrilatos/química , Metacrilatos/metabolismo , Nylons/química , Nylons/metabolismo , Polielectrolitos/química , Unión Proteica , Resonancia por Plasmón de Superficie
12.
Z Gastroenterol ; 57(11): 1291-1297, 2019 Nov.
Artículo en Alemán | MEDLINE | ID: mdl-31739374

RESUMEN

Recently, research in the treatment of inflammatory bowel diseases has become increasingly focused on fecal microbiota transfer (FMT) due to increasing evidence of its possible benefits. Still, there are doubts about this method, because there is contradicting evidence regarding its effectiveness and the possible side effects are not well known. Furthermore, the majority of patients are not open to this procedure. We performed a questionnaire-based survey amongst 302 patients with an inflammatory bowel disease that received treatment in our specialized outpatient clinic to determine the factors relevant for acceptance or rejection of fecal microbiota transfer as a possible treatment for Crohn's disease or ulcerative colitis. Our data supports the hypothesis that a lack of information about FMT is a key factor for hypothetical acceptance of this method (68 % of pre-informed participants vs. 30 % of not pre-informed participants would accept FMT as treatment, p < 0.001), and, therefore, it highlights patient education as a possible intervention to improve acceptance. The main concern regarding FMT was possible transmission of infections (ranked first by 98 participants). The most accepted method to perform FMT was application via oral capsule (44 % of participants).


Asunto(s)
Trasplante de Microbiota Fecal/métodos , Enfermedades Inflamatorias del Intestino/terapia , Aceptación de la Atención de Salud , Trasplante de Microbiota Fecal/efectos adversos , Heces , Humanos , Microbiota , Percepción , Encuestas y Cuestionarios
13.
Gut ; 67(10): 1824-1835, 2018 10.
Artículo en Inglés | MEDLINE | ID: mdl-28982740

RESUMEN

OBJECTIVE: This phase II, randomised, double-blind, placebo-controlled clinical trial was designed to evaluate the efficacy and safety of PF-00547659, a fully human monoclonal antibody that binds to human mucosal addressin cell adhesion molecule (MAdCAM) to selectively reduce lymphocyte homing to the intestinal tract, in patients with moderate-to-severe Crohn's disease (CD). DESIGN: Eligible adults were aged 18-75 years, with active moderate-to-severe CD (Crohn's Disease Activity Index (CDAI) 220-450), a history of failure or intolerance to antitumour necrosis factor and/or immunosuppressive agents, high-sensitivity C reactive protein >3.0 mg/L and ulcers on colonoscopy. Patients were randomised to PF-00547659 22.5 mg, 75 mg or 225 mg or placebo. The primary endpoint was CDAI 70-point decrease from baseline (CDAI-70) at week 8 or 12. RESULTS: In all, 265 patients were eligible for study entry. Although CDAI-70 response was not significantly different with placebo versus PF-00547659 treatment at weeks 8 or 12, remission rate was greater in patients with higher baseline C reactive protein (>5 mg/L vs >18.8 mg/L, respectively). Soluble MAdCAM decreased significantly from baseline to week 2 in a dose-related manner and remained low during the study in PF-00547659-treated patients. Circulating ß7+ CD4+ central memory T-lymphocytes increased at weeks 8 and 12 with PF-00547659 treatment. No safety signal was seen. CONCLUSIONS: Clinical endpoint differences between PF-00547659 and placebo did not reach statistical significance in patients with moderate-to-severe CD. PF-00547659 was pharmacologically active, as shown by a sustained dose-related decrease in soluble MAdCAM and a dose-related increase in circulating ß7+ central memory T cells. TRIAL REGISTRATION NUMBER: NCT01276509; Results.


Asunto(s)
Anticuerpos Monoclonales Humanizados , Enfermedad de Crohn , Adulto , Anciano , Anticuerpos Monoclonales Humanizados/administración & dosificación , Anticuerpos Monoclonales Humanizados/efectos adversos , Proteína C-Reactiva/análisis , Colonoscopía/métodos , Enfermedad de Crohn/diagnóstico , Enfermedad de Crohn/tratamiento farmacológico , Enfermedad de Crohn/metabolismo , Relación Dosis-Respuesta a Droga , Método Doble Ciego , Monitoreo de Drogas/métodos , Femenino , Fármacos Gastrointestinales/administración & dosificación , Fármacos Gastrointestinales/efectos adversos , Humanos , Masculino , Persona de Mediana Edad , Gravedad del Paciente , Índice de Severidad de la Enfermedad , Resultado del Tratamiento
14.
Langmuir ; 34(7): 2448-2454, 2018 02 20.
Artículo en Inglés | MEDLINE | ID: mdl-29356537

RESUMEN

We report investigations on the salt sensitivity of the thermoresponsive behavior of PNIPAAm brushes applying the quartz crystal microbalance coupled with spectroscopic ellipsometry technique. This approach enables a detailed study of the optical and mechanical behavior of the polymer coatings. Additional conclusions can be drawn from the difference between both techniques due to a difference in the contrast mechanism of both methods. A linear shift of the phase-transition temperature to lower temperatures with the addition of sodium chloride was found, similar to the behavior of free polymer chains in solution. The thermal hysteresis was found to be decreased by the addition of sodium chloride to the solution, hinting to the interaction of the ions with the amide groups of the polymer, whereby the formation of hydrogen bonds is hindered. The results of this study are of relevance to the application of PNIPAAm brushes in biological fluids and demonstrate the additional potential of the ion sensitivity besides the better known thermosensitivity.

15.
Anal Bioanal Chem ; 410(21): 5313-5327, 2018 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-29909455

RESUMEN

In recent years, many studies on the analysis of microplastics (MP) in environmental samples have been published. These studies are hardly comparable due to different sampling, sample preparation, as well as identification and quantification techniques. Here, MP identification is one of the crucial pitfalls. Visual identification approaches using morphological criteria alone often lead to significant errors, being especially true for MP fibers. Reliable, chemical structure-based identification methods are indispensable. In this context, the frequently used vibrational spectroscopic techniques but also thermoanalytical methods are established. However, no critical comparison of these fundamentally different approaches has ever been carried out with regard to analyzing MP in environmental samples. In this blind study, we investigated 27 single MP particles and fibers of unknown material isolated from river sediments. Successively micro-attenuated total reflection Fourier transform infrared spectroscopy (µ-ATR-FTIR) and pyrolysis gas chromatography-mass spectrometry (py-GCMS) in combination with thermochemolysis were applied. Both methods differentiated between plastic vs. non-plastic in the same way in 26 cases, with 19 particles and fibers (22 after re-evaluation) identified as the same polymer type. To illustrate the different approaches and emphasize the complementarity of their information content, we exemplarily provide a detailed comparison of four particles and three fibers and a critical discussion of advantages and disadvantages of both methods.

16.
J Chem Phys ; 148(20): 204110, 2018 May 28.
Artículo en Inglés | MEDLINE | ID: mdl-29865845

RESUMEN

The suppression of Raman scattering is of high interest for the achievement of sub-diffraction-limited resolution in Raman scattering spectroscopy and microscopy. We present density matrix calculations of the suppression of spontaneous Raman scattering via ground state depletion in a level system based on the molecule tris(bipyridine)ruthenium(ii). This particular molecule has been earlier used for an experimental demonstration of the suppression of spontaneous Raman scattering, allowing us to successfully verify the validity of our numerical calculations by a comparison to the experimental results. We investigate the required level of detail of the molecule model as well as the influence of certain molecule and pulse parameters on the Raman scattering suppression. It was found that pulses with a duration longer than the lifetime of the electronic states allow for a high suppression of the Raman scattering. Pulses shorter than the coherence lifetime between the ground state and electronic states lead to a similarly high suppression but also accomplish the suppression with more than one order of magnitude lower pulse energy fluence. Additionally, using a laser wavelength that is in resonance with one of the electronic transitions of the sample should allow suppressing the Raman scattering with four to six orders of magnitude lower pulse energy fluence.

17.
Anal Chem ; 89(6): 3240-3244, 2017 03 21.
Artículo en Inglés | MEDLINE | ID: mdl-28256133

RESUMEN

We significantly improve the infrared analysis of ultrathin films in aqueous environments by employing in situ infrared ellipsometry. Combining it with rigorous optical modeling avoids otherwise typical misinterpretations of spectral features and enables the simultaneous quantification of chemical composition, hydration states, structure, and molecular interactions. We apply this approach to study covalently end-grafted, nanometer-thin brushes of poly(N-isopropylacrylamide), a thermoresponsive model polymer for proteins at solid-liquid interfaces. Quantitative analyses are based on a dielectric layer model that accounts for film swelling and deswelling, hydration of hydrophilic amide and hydrophobic isopropyl side groups, as well as molecular interactions of the polymer's amide moieties. We thereby quantify the hydration and structure dependence of intra- and intermolecular C═O···H-N and C═O···H2O hydrogen bonds, elucidating their role in the brush's temperature-induced phase separation. The presented method is directly applicable to functional and biorelated films like polymer and polypeptide layers, which is of topical interest for interface studies, such as membrane processes and protein unfolding.

18.
Z Gastroenterol ; 55(11): 1119-1126, 2017 11.
Artículo en Alemán | MEDLINE | ID: mdl-29141267

RESUMEN

A uniform and comprehensive terminology is essential in the correct documentation of diagnostic or therapeutic endoscopic procedure. In the German-speaking world, the standard terminology available so far is based on a previous version published in 1999. Therefore, the German Society for Gastroenterology, Digestive and Metabolic Diseases (DGVS) has undergone a comprehensive revision and re-structuring of the terminology. This appeared mandatory due to various changes, new diagnoses and new endoscopic procedures. The suggestions drawn up by individual working groups were approved by consensus and are now available as an online document (https://doi.org/10.1055/s-0043-121167) for modifying current software systems. In order to ensure an up-to-date documentation in the future, it was decided that annual updates will be performed by the DGVS to check respective software packages for modifications and new contents.


Asunto(s)
Endoscopía , Gastroenterología , Terminología como Asunto , Humanos
19.
Planta ; 244(1): 145-54, 2016 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-27002970

RESUMEN

MAIN CONCLUSION: A mixture of resins based on aliphatic esters and carboxylic acids occurs in distantly related genera Peperomia and Roridula , serving different functions as adhesion in seed dispersal and prey capture. According to mechanical characteristics, adhesive secretions on both leaves of the carnivorous flypaper Roridula gorgonias and epizoochorous fruits of Peperomia polystachya were expected to be similar. The chemical analysis of these adhesives turned out to be challenging because of the limited available mass for analysis. Size exclusion chromatography and Fourier transform infrared spectroscopy were suitable methods for the identification of a mixture of compounds, most appropriately containing natural resins based on aliphatic esters and carboxylic acids. The IR spectra of the Peperomia and Roridula adhesive resemble each other; they correspond to that of a synthetic ethylene-vinyl acetate copolymer, but slightly differ from that of natural tree resins. Thus, the pressure sensitive adhesive properties of the plant adhesives are chemically proved. Such adhesives seem to appear independently in distantly related plant lineages, habitats, life forms, as well as plant organs, and serve different functions such as prey capture in Roridula and fruit dispersal in Peperomia. However, more detailed chemical analyses still remain challenging because of the small available volume of plant adhesive.


Asunto(s)
Adhesivos/química , Magnoliopsida/química , Peperomia/química , Polivinilos/química , Adhesivos/análisis , Animales , Cromatografía en Gel , Ecosistema , Frutas/química , Frutas/fisiología , Insectos/fisiología , Magnoliopsida/clasificación , Magnoliopsida/fisiología , Peperomia/fisiología , Hojas de la Planta/química , Hojas de la Planta/fisiología , Fenómenos Fisiológicos de las Plantas , Polivinilos/análisis , Dispersión de Semillas/fisiología , Especificidad de la Especie , Espectroscopía Infrarroja por Transformada de Fourier
20.
Opt Express ; 24(18): 20745-54, 2016 Sep 05.
Artículo en Inglés | MEDLINE | ID: mdl-27607677

RESUMEN

We report on the first experimental demonstration of the suppression of spontaneous Raman scattering via ground state depletion. The concept of Raman suppression can be used to achieve sub-diffraction-limited resolution in label-free microscopy by exploiting spatially selective signal suppression when imaging a sample with a combination of Gaussian- and donut-shaped beams and reconstructing a resolution-enhanced image from this data. Using a nanosecond pulsed laser source with an emission wavelength of 355 nm, the ground state of tris(bipyridine)ruthenium(II) molecules solved in acetonitrile was depleted and the spontaneous Raman scattering at 355 nm suppressed by nearly 50 %. Based on spectroscopic data retrieved from our experiment, we modeled the Raman image of a scattering center in order to demonstrate the applicability of this effect for superresolution Raman microscopy.

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