Spatially resolving light detectors allow, with proper calibration, quantitative analysis of the variations in two-dimensional intensity distributions over time. An ultra-sensitive microfluorometer ...was assembled by using as a detector a microchannel plate-intensified video camera. The camera was interfaced with a software-based digital video analysis system to digitize, average, and process images and to directly control the timing of the experiments to minimize exposure of the specimen to light. The detector system has been characterized to allow its use as a photometer. A major application has been to perform fluorescence recovery after photobleaching measurements by using the camera in place of a photomultiplier tube (video-FRAP) with the goal of detecting possible anisotropic diffusion or convective flow. Analysis of the data on macromolecular diffusion in homogenous aqueous glycol solutions yielded diffusion constants in agreement with previous measurements. Results on lipid probe diffusion in dimyristoyl-phosphatidylcholine multibilayers indicated that at temperatures above the gel-to-liquid crystalline phase transition diffusion is isotropic, and analysis of video-FRAP data yielded diffusion coefficients consistent with those measured previously by using spot photobleaching. However, lipid probes in these multibilayers held just below the main phase transition temperature exhibited markedly anisotropic diffusive fluxes when the bleaching beam was positioned proximate to domain boundaries in the P β ′ phase. Lipid probes and lectin receptor complexes diffused isotropically in fibroblast surface membranes with little evidence for diffusion channeled parallel to stress fibers. A second application was to trace the time evolution of cell surface reactions such as patching. The feasibility of following, on the optical scale, the growth of individual receptor clusters induced by the ligand wheat germ agglutinin was demonstrated.
The lateral mobility of the lipid analog N-4-nitrobenzo-2-oxa-1,3 diazole phosphatidylethanolamine and of the integral protein glycophorin in giant dimyristoylphosphatidylcholine vesicles was studied ...by the photobleaching technique. Above the temperature of the chain-melting transition (Tm = 23 degrees C), the diffusion coefficient, Dp, of the protein Dp = (4 +/- 2) X 10(-8) cm2/s at 30 degrees C was within the experimental errors equal to the corresponding values DL of the lipid analog. In the P beta 1 phase the diffusion of lipid and glycophorin was studied as a function of the probe and the protein concentration. (a) At low lipid-probe content (cL less than 5 mmol/mol of total lipid), approximately 20% of the probe diffuses fast (D approximately equal to 10(-8) - 10(-9) cm2/s), while the mobility of the rest is strongly reduced (D less than 10(-10) cm2/s). At a higher concentration (cp approximately 20 mmol), all probe is immobilized (D less than 10(-10) cm2/s). (b) Incorporation of glycophorin up to cp = 0.4 mmol/mol of total lipid leads to a gradual increase of the fraction of mobile lipid probe due to the lateral-phase separation into a pure P beta 1 phase and a fraction of lipid that is fluidized by strong hydrophilic lipid-protein interaction. (c) The diffusion of the glycophorin molecules is characterized by a slow and a fast fraction. The latter increases with increasing protein content, which is again due to the lateral-phase separation caused by the hydrophilic lipid-protein interaction. The results are interpreted in terms of a fast transport along linear defects in the P beta 1 phase, which form quasi-fluid paths for a nearly one dimensional and thus very effective transport. Evidence for this interpretation of the diffusion measurements is provided by freeze-fracture electron microscopy.
The lateral diffusion coefficients (D) of the molecular fluorescence probe 3,3'-dioctadecylindocarbocyanine iodide (DII) in the membrane of discoiderythrocyte ghosts has been measured with the ...photobleaching technique between 7 degrees C and 40 degrees C. A fluorescence microscope which allows bleaching experiments within small local fields (approx. 1 micron m2) at high magnification (X1600) has been used for these measurements. The diffusion coefficient increases from D = 9 - 10-10 cm2/s to D = 7.5 - 10-9 cm2/s from 7 to 40 degrees C. An increase in membrane fluidity between 12 degrees C and 17 degrees C indicates a conformational change of the lipid bilayer moiety in this temperature region. The diffusion coefficient measured in the regions between the spicules of echinocytes is appreciably smaller than in the untransformed discoid ghosts. In the myelin tubes originating from cells, the lateral diffusion is somewhat larger (about a factor of 2) than in the non-transformed ghosts. With the fluorescence probe technique the rate of growth of myelin tubes of 0.3 micronm diameter has been estimated.
The aim of this study was to assess the performance of the Continuous Research Tool (CRT) in a multicentre clinical-experimental study.
Three patient groups totalling 28 subjects with diabetes group ...A 10 Type 1 (Ulm), group B 10 Type 1 (Neuss), group C eight Type 2 (Aarhus) participated in this trial. Two CRT microdialysis probes were inserted in parallel in the abdominal subcutaneous tissue for 120 h in each subject. In subjects in group A, glucose excursions were induced on one study day and those in group B underwent a glucose clamp (eu-, hypo- or hyperglycaemic) on one study day. CRT data were calibrated once with a retrospective calibration model based on a run-in time of 24 h and three blood glucose measurements per day.
All analysable experiments, covering a broad range of blood glucose values, yielded highly accurate data for the complete experimental time with a mean relative absolute difference of 12.8 +/- 6.0% and a predictive residual error sum of squares of 15.6 +/- 6.3 (mean +/- SD). Of all measurement results, 98.2% were in zones A and B of the error grid analysis. The average absolute differences were 1.14 mmol/l for Type 1 and 0.88 mmol/l for Type 2 diabetic patients. Relative absolute differences were 16.0% for Type 1 and 12.6% for Type 2 diabetic patients.
These results demonstrate that this microdialysis system allows reliable continuous glucose monitoring in patients with diabetes of either type.
Objectif Cette étude randomisée, ouverte, avec administration répétée pendant 4 semaines, a comparé la pharmacodynamie du lixisénatide (20 µg par jour) vs le liraglutide (1,8 mg par jour) chez des ...patients ayant un DT2 non équilibré sous metformine 1,5 g/jour NCT01175473. Matériels et méthodes Les patients ont reçu en sous-cutané, 30 min avant le petit-déjeuner, soit du lixisénatide (n = 77), soit du liraglutide (n = 71). La dose de lixisénatide était augmentée de 10 à 20 µg après 2 semaines; la dose de liraglutide était augmentée de façon hebdomadaire de 0,6 mg à 1,8 mg. Le critère principal était la différence, entre l’inclusion et la semaine 4, de l’aire sous la courbe (ASC) de GPP (ASC0h30-4h30) après un petit-déjeuner standardisé. Les critères secondaires étaient constitués par le pic maximal de GPP, le profil glycémique sur 24 h, l’HbA1c, le profil en 7 points et l’ASC pour l’insuline, le peptide C, le glucagon et la pro-insuline, ainsi que les effets secondaires/la tolérance. Résultats Le lixisenatide a diminué la GPP de façon significativement plus importante que le liraglutide, avec un ASC 0 h 30-4 h 30 moyen respectivement de-227,3 vs-72,8 h·mg/dl (différence :-154,4 h·mg/dl; p < 0,0001). La différence de pic maximal de GPP était de - 70,4 mg/dl avec le lixisénatide vs - 24,9 mg/dl avec le liraglutide (p < 0,0001). À 4 semaines, plus de patients sous lixisénatide (69%) que sous liraglutide (29%) avaient une GPP à 2 h < 140 mg/dl. Les profils glycémiques de 24 h ont montré une diminution globale de la glycémie dans les deux groupes. Le lixisenatide a induit une diminution significativement plus importante de la glucagonémie postprandiale après 4 semaines de traitement (p = 0,032 vs liraglutide). L’insulinémie et le peptide-C postprandiaux ont également été significativement diminués sous lixisénatide vs liraglutide (p < 0,0001 pour les deux paramètres) alors que la baisse de pro-insuline était comparable (p = 0,10). L’HbA1c moyenne a diminué dans deux groupes de traitement (de 7,2 à 6,9% sous lixisénatide vs 7,4 à 6,9% sous liraglutide), tout comme le poids (respectivement - 1,6 kg vs – 2,4 kg). La fréquence cardiaque en position couchée a diminué de - 3,6 battements/min (bpm) sous lixisénatide vs une augmentation de 5,3 bpm sous liraglutide. Il n’y a pas eu d’événements indésirables (EI) graves ni aucun cas d’hypoglycémie ou de pancréatite. Quatre patients ont arrêté le traitement en raison d’EI : 2 sous lixisénatide (2,6%) en raison de réactions allergiques et 2 sous liraglutide (2,8%) pour des problèmes gastro-intestinaux. L’incidence globale des EI était plus faible avec le lixisénatide (58%) qu’avec le liraglutide (73%) et c’étaient essentiellement des pertes d’appétit (18% vs 37%), des problèmes gastro-intestinaux (36% vs 46%) et des troubles d’ordre neurologique (principalement céphalées/vertiges; 16% vs 24%). Conclusion Chez des patients DT2, le lixisenatide en prise quotidienne a diminué de façon significative par rapport au liraglutide la GPP (-129% vs – 41%), l’insulinémie, le peptide-C et la glucagonémie, et ceci avec un meilleur profil de tolérance gastro-intestinale.
The translational diffusion of the integral membrane sialoglycoprotein from erythrocyte membranes, glycophorin, incorporated into bilayer membranes of dimyristoyl-phosphatidylcholine at a ...protein/lipid molar ratio of 1:4500 was examined by using the fluorescence redistribution after photobleaching technique. A plot of the diffusion coefficient vs. temperature shows a sharp decrease in the rate of diffusion at about 15 degrees C. This sharp diffusion transition is at a temperature some 9 degrees C lower than the calorimetrically measured lipid gel-liquid crystalline phase transition temperature of the system. The difference between the diffusion transition temperature and the lipid phase transition temperature is attributed toi a localized fluidizing effect of the protein upon the gel phase lipid. The value of the diffusion coefficient above 15 degrees C was found to be (1-2) x 10(-8) cm(2)s(-1), and below 15 degrees C it was lower than about 5 x 10(-11)cm(2)s(-1). The fluorescence recovery in the bleached area as a consequence of diffusional redistribution appeared to be due to a single diffusing species at temperatures above 15 degrees C and due to more than one diffusing species below this temperature.
Development of a feasible and reliable method for determining abdominal fat using breath-hold T1-weighted magnetic resonance imaging.
The high image contrast of T1-weighted gradient echo MR sequences ...makes it possible to differentiate between abdominal fat and non-fat tissue. To obtain a high signal-to-noise ratio, the measurements are usually performed using phased array surface coils. Inhomogeneity of the coil sensitivity leads to inhomogeneity of the image intensities. Therefore, to examine the volume of abdominal fat, an automatic algorithm for intensity correction must be implemented. The analysis of the image histogram results in a threshold to separate fat from other tissue. Automatic segmentation using this threshold results directly in the fat volumes. The separation of intraabdominal and subcutaneous fat is performed by interactive selection in a last step.
The described correction of inhomogeneity allows for the segmentation of the images using a global threshold. The use of semiautomatic interactive volumetry makes the analysis more subjective. The variance of volumetry between observers was 4.6 %. The mean time for image analysis of a T1-weighted investigation lasted less than 6 minutes.
The described method facilitates reliable determination of abdominal fat within a reasonable period of time. Using breath-hold MR sequences, the time of examination is less than 5 minutes per patient.
In this paper we describe the operation and performance of the HERA-B Outer Tracker, a 112
674 channel system of planar drift tube layers. The performance of the HERA-B Outer Tracker system ...fullfilled all requirements for stable and efficient operation in a hadronic environment, thus confirming the adequacy of the honeycomb drift tube technology and of the front-end readout system. The detector was stably operated with a gas gain of
3
×
10
4
in an
Ar
/
CF
4
/
CO
2
(65:35:5) gas mixture, yielding a good efficiency for triggering and track reconstruction, larger than 95% for tracks with momenta above
5
GeV
/
c
. The hit resolution of the drift cells was 300–
320
μ
m
and the relative momentum resolution can be described as:
σ
(
p
)
/
p
%
=
(
1.61
±
0.02
)
+
(
0.0051
±
0.0006
)
·
p
GeV
/
c
. At the end of the HERA-B running no aging effects in the Outer Tracker cells were observed.
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