Kontinuierliche, reagensfreie Glucosebestimmung

Die häufige Überwachung der Glucosekonzentration kann sowohl akute Risiken als auch Langzeitkomplikationen für Patienten mit Diabetes mellitus, einer Störung des Glucosemetabolismus, verringern. Der in dieser Arbeit vorgestellte Ansatz einer minimal-invasiven, kontinuierlichen Glucosebestimmung nutzt die Spektroskopie molekularer Schwingungen und macht dabei von der hohen Sensitivität und Selektivität der reagensfreien, fasergebundenen Transmissionsspektroskopie im mittleren infraroten Spektralbereich Gebrauch. Quantenchemische Simulationen konnten unter Verwendung von effektiven Fragmentpotentialen den Einfluss des Solvationsprozesses auf die Schwingungsspektren von Glucose beschreiben und für den Fall von 80 gemittelten Einzelspektren mit jeweils 18 umgebenden Wassermolekülen eine sehr gute Korrelation mit experimentellen Daten (R=0,941) erzielen. In Laborversuchen wurde bei Messreihen an wässrigen Testlösungen auf der Basis eines Quantenkaskadenlasers bei einer Emissionswellenlänge von 9,69µm und eines speziell entworfenen faseroptischen Sensors eine rauschäquivalente Vorhersagegenauigkeit von 0,6mg/dL bei einer Integrationszeit von 4s erreicht. Durch diese Ergebnisse konnte erstmals und sehr deutlich die in-vitro-Machbarkeit im Kern des Ansatzes belegt werden. Die Experimente wurden flankiert von Untersuchungen zu potenziellen Störsubstanzen und Maßnahmen zur Erhöhung der Biokompatibilität des Fasersensors. Die in-vivo-Tauglichkeit eines subkutan implantierten Sensors konnte schließlich in ersten Versuchsreihen demonstriert werden

The Selective Digital Integrator: A New Device for Modulated Polarization Spectroscopy.

A new device, a selective digital integrator (SDI), for the acquisition of modulated polarization spectroscopy (MPS) signals is described. Special attention is given to the accurate measurement of very small (AC component of interest $\u3c$10\sp{-3} x DC component), rapidly modulated ($\sim$50 kHz) signals at or below noise levels. Various data acquisition methods and problems associated with the collection of modulated signals are discussed. The SDI solves most of these problems and has the following advantages: it provides the average-time resolved profile of a modulated signal; it eliminates errors if the modulation is not sinusoidal; it enables separate measurements of the various phases of the signal modulation cycle; it permits simultaneous measurement of absorption, circular dichroism (CD) and linear dichroism (LD) spectra; it facilitates 3-D absorbance measurements; it has a wide gain-switching-free dynamic range (10 orders of magnitude or more); it offers a constant S/N ratio mode of operation; it eliminates the need for photomultiplier voltage feedback, and it has faster scanning speeds. The time-resolution, selectivity, wide dynamic range, and low-overhead on-the-fly data processing are useful for other modulated spectroscopy (MS) and non-MS experiments such as pulse height distribution and time-resolved pulse counting measurements. The advantages of the MPS-SDI method are tested on the first Rydberg electronic transitions of (+)-3-methylcyclopentanone. The experimental results validate the predicted SDI capabilities. However, they also point to two difficulties that had not been noted previously: the presence of LD in a gaseous sample and a pressure-dependence of the relative peak heights of the CD spectrum. Models for these anomalies are proposed. The presence of the oscillatory LD (but not an LD background) is explained with a sample cell model based on the observed polarization-dependent time-resolved profiles of transmitted light intensity. To obtain expressions for these intensities, a theoretical background, which provides a new approach to the treatment of light/matter interaction, is included as an Appendix. To explain the second anomaly, present only at high optical densities, a model based on the presence of scattered light is introduced and verified. The mode of correction for the scattering problem is outlined

On-line control using the particle swarm optimisation algorithm

In the last two decades, evolutionary based algorithms have proved to be an important tool in solving optimisation problems in many disciplinary areas, namely in control system design. However one of its limitations for some type of applications is the usually high computational load required, which restricts its use for on-line control. This paper proposes the use of a stochastic search algorithm, known as particle swarm, as an optimisation tool for an on-line model predictive control of a custom made laboratory thermodynamic system. Preliminary results are presented

Impact of preoperative clopidogrel in off pump coronary artery bypass surgery: A propensity score analysis

ObjectiveThe aim of our study was to evaluate the impact of recent clopidrogel use before off-pump coronary artery bypass grafting on the postoperative risk of bleeding.MethodsDuring the period January 2003 to December 2006, 1104 consecutive patients underwent off-pump coronary artery bypass grafting. Patients were divided into two groups according to the recent use of clopidrogel (within 7 days). We performed a propensity score to further adjust for differences between the patients with and without recent use of clopidrogel.ResultsMean age was 64 ± 14 years and 87% were male. The clopidrogel group had a greater incidence of patients in unstable condition, requiring emergency coronary bypass grafting, and with a high EuroSCORE. Propensity score analysis selected 88 patients with and 176 without recent use of clopidrogel. By propensity score, the clopidrogel group had higher requirements for fresh frozen plasma units (18.1% vs 8.5%; P = .02), reoperation owing to bleeding (5.6% vs 0.5%; P = .009), and higher need for postoperative mechanical ventilation (4% vs 10%; P = .04), whereas mortality and length of stay were similar between groups.ConclusionRecent use of clopidogrel before off-pump coronary artery bypass grafting is associated with greater risk for bleeding with similar mortality rate

Impacto del equipo multidisciplinario “ECMO Team” en el pronóstico de pacientes sometidos a membrana de oxigenación extracorpórea venoarterial por choque cardiogénico o paro cardiorrespiratorio refractario

Objectives. Veno-arterial Extracorporeal membrane oxygenation (VA ECMO) is a salvage intervention in patients with cardiogenic shock (CS), and cardiac arrest  (CA) refractory to standard therapies. The design of ECMO Teams has achieved the standardization of processes, although its impact on survival and prognosis is unknown. Objective: We aimed to analyze whether the creation of an ECMO Team has modified the prognosis of patients undergoing VA ECMO for refractory CS or CA. Materials and methods. We conducted a single-center retrospective cohort study. Patients with refractory CS or CA who underwent VA ECMO were divided in two consecutive periods: from 2014 to April 2019 (pre-ECMO T) and from May 2019 to December 2022 (Post ECMO T). The main outcomes were survival on ECMO, in-hospital survival, complications, and annual ECMO volume. Results. Eighty-three patients were included (36 pre-ECMO T and 47 post-ECMO T). The mean age was 53 +/-13 years. The most common reason for  device indication was different:  postcardiotomy shock (47.2%) pre-ECMO T and refractory cardiogenic shock (29.7%) post-ECMO T. The rate of extracorporeal  cardiopulmonary resuscitation was 14.5%.  The median duration of VA ECMO was longer after ECMO team implementation: 8 days (IQR 5-12.5) vs. five days (IQR 2-9, p=0.04). Global in-hospital survival was 45.8% (38.9% pre-ECMO T vs. 51.1% post-ECMO T; p=0.37),  and the survival rate from VA ECMO was 60.2% (55.6% pre-ECMO T vs 63.8% post-ECMO T; p= 0.50). The volume of VA ECMO implantation was significantly higher in the post-ECMO team period (13.2  +/3.5 per year vs. 6.5 +/-3.5 per year, p: 0.02). The rate of complications was similar in both groups. Conclusions. After the implementation of an ECMO team, there was no statistical difference in the survival rate of patients treated with VA ECMO. However, a significant increase in the number of patients supported per year was observed after the implementation of this multidisciplinary team. Post-ECMO T, the most common reason for device indication was cardiogenic shock, with longer run times and a higher rate of extracorporeal cardiopulmonary resuscitation.Introducción. La oxigenación por membrana extracorpórea venoarterial (ECMO VA) es una intervención de rescate utilizada en choque cardiogénico (CC) o paro cardiorrespiratorio (PCR) refractario. La creación de equipos multidisciplinarios ECMO Teams (ECMO T), ha permitido la estandarización de procesos, aunque se desconoce su impacto en  sobrevida y pronóstico. Objetivo: El propósito es analizar si la creación del ECMO Team ha modificado el pronóstico de los pacientes sometidos a ECMO VA por CC o PCR refractario. Materiales y métodos. Estudio observacional, unicéntrico, retrospectivo, que comparó los resultados del implante de ECMO VA por CC o PCR refractario en dos períodos consecutivos: entre 2014 y abril de 2019 (pre-ECMO T), y entre mayo de 2019 y diciembre de 2022 (pos-ECMO T). Como puntos finales, se evaluó la sobrevida intrahospitalaria y en ECMO, complicaciones, y volumen de ECMO anual. Resultados. Se analizaron 83 pacientes (36 pre-ECMO T, y 47 pos-ECMO T), con edad de 53 +/-13 años. La causa más frecuente de asistencia fue: poscardiotomía pre-ECMO T (47,2%) y CC refractario pos-ECMO T (29,7%). En el 14,5% se realizó ECMO en PCR. La mediana de asistencia fue mayor pos-ECMO T (8 días, RIC 5-12,5 vs. 5 días, RIC 2-9 pre-ECMO T; p:0,04). La supervivencia al alta fue del 45,8% (38,9% pre-ECMO T vs. 51,1% pos-ECMO T;p:0,37) y en ECMO VA del 60,2% (55,6% pre-ECMO T y 63,8% pos-ECMO T; p:0,50). El volumen de ECMO VA fue significativamente mayor pos-ECMO T (13,2+/3,5 por año vs. 6,5+/-3,5 por año, p: 0,02). La tasa de complicaciones fue similar en ambos períodos. Conclusiones.Luego de la implementación del ECMO Team no se observó una diferencia significativa en la sobrevida en pacientes asistidoscon ECMO VA. Sin embargo, luego de su creación se evidenció un aumento significativo del volumen de pacientes asistidos por año. Pos-ECMO T se asistió mayor número de pacientes por choque cardiogénico, en PCR y con más días de asistencia

Encapsulation of a Concanavalin A/dendrimer glucose sensing assay within microporated poly (ethylene glycol) microspheres

Proper management of diabetes requires the frequent measurement of a patient’s blood glucose level. To create a long-term, minimally-invasive sensor that is sensitive to physiological concentrations of glucose a fluorescent glucose sensing assay using a competitive binding approach between fluorescently tagged Concanavalin-A (Con-A) and glycodendrimer is being developed. Until now, the essential step of effectively encapsulating this aggregative sensing assay while allowing a reversible response has yet to be reported. In this paper, a microporation technique is described in which microspheres are synthesized in a manner that creates fluid-filled pores within a poly (ethylene glycol) hydrogel. This dual-nature technique creates hydrophilic, biocompatible microcapsules in which the aggregative binding kinetics of the sensing assay within the pores are not constrained by spatial fixation in the hydrogel matrix. Confocal images displaying the localization of pockets filled with the assay within the polymeric matrix are presented in this paper. In addition, fluorescent responses to varying glucose concentrations, leaching studies, and long-term functionality of the encapsulated assay are demonstrated. To our knowledge, this is the first time that the Con-A/glycodendrimer assay has been shown to be reversible and repeatable within hydrogel spheres, including the display of functionality up to fourteen days under ambient conditions

Response to Justine Schneider’s article ‘Music therapy and dementia care practice in the United Kingdom: A British Association for Music Therapy membership survey’

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