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Results for “Fluorescence Microscopy”

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At least 397 records · Page 22Linked to original sources
PubMed2001

Quantification of mucosal leucocyte endothelial cell interaction by in vivo fluorescence microscopy in experimental colitis in mice.

Leucocyte recruitment to sites of intestinal inflammation is a crucial, multi-step process that leads ultimately to the accumulation of cells in the inflamed tissue. We established a new in vivo model system of experimental colitis to quantify leucocyte-endothelial cell interaction and leucocyte extravasation in the inflamed mucosa of the colon. Furthermore, we investigated the pathophysiological role of ICAM-1 in the intestinal microcirculation in vivo. Using the model of dextran sodium sulphate (DSS)-induced acute and chronic colitis in mice, in vivo microscopy was performed in the colonic submucosal postcapillary venules and the submucosal collecting venules in normal or inflamed murine colonic segments. ICAM-1 expression was blocked by an anti-ICAM-1 monoclonal antibody or by suppressing NF-kappaB activation by gliotoxin. Significant increases in leucocyte adhesiveness (51-fold in postcapillary venules, 30-fold in collecting venules, P < 0.01) and extravasation (6.5-fold) could be demonstrated as early as day 2 of DSS-application in acute colitis (P < 0.01). This was paralleled by increases in both the histological damage scores and myeloperoxidase activities. In chronic dextran sodium sulphate-induced colitis significant increases in leucocyte-endothelium interactions and leucocyte extravasation were observed. Blocking ICAM-1 expression with a monoclonal antibody or gliotoxin, leucocyte sticking and extravasation were significantly down-regulated in vivo compared to controls (> 70%; P < 0.01). This new model system offers the possibility to specifically assess the role of adhesion molecules in the colonic mucosa in vivo as well as to investigate and quantify the effectiveness of experimental therapeutic approaches in acute or chronic intestinal inflammation.

Acute Disease↗
PubMed2002

Axial tomographic confocal fluorescence microscopy.

By physical rotation of the sample, axial tomography enables the acquisition of otherwise inaccessible spatial information from an object. In combination with confocal microscopy, the method can fundamentally improve the effective three-dimensional (3D) resolution. In this report we present a novel method for high resolution reconstruction of confocal axial tomographic data. The method automatically determines the relative angles of rotation, aligns the data from different rotational views and reconstructs a single high resolution 3D dataset. The reconstruction makes use of a known point spread function and is based on an unconstrained maximum likelihood deconvolution performed simultaneously from multiple (in our case three) angular views. It was applied to simulated as well as to experimental confocal datasets. The gain in resolution was quantified and the effect of choice of overrelaxation factors on the speed of convergence was investigated. A clearly improved 3D resolution was obtained by axial tomography together with reconstruction as compared with reconstruction of confocal data from only a single angular view.

Algorithms↗
PubMedDate not supplied

[Results of fluorescence microscopy studies of bone healing by direct stimulation with bipolar impulse currents and with the interference current procedure in the animal experiment].

42 cross-breed rabbit bastards of either sex were osteotomized on the left proximal third of the tibia. A teflonisolated stable plating was made by means of the polychromatically KF-AO-instrumentarium. The animals were fluorescentlabelled in weekly intervals. Tetraverinex, alizarin complexon, fluorexon, xylenol orange and calceine were used as colours. The animals were stimulated in the bipolar squaretopped pulse current procedure (1 Hz and 10 Hz, resp., +/- 25 and +/- 50 microA, resp., intensity, permanent stimulation) or in the interference current procedure (oscillation frequency 100 Hz, intensity 1 mA, 4 hours daily). An osteotomized group served as a control. The undecalcified bone sections were quantitatively measured in the area of the periosteal and endoosteal accummulation seams as well as in the area of the Haversians canals and compared by means of multiple variance analyses. A delay in the Haversian remodelling within the first 2 weeks was found in the animals only osteotomized. This delay could not be detected in all electrically stimulated groups. The electrical stimulation leads to a shortening of the fracture healing period by skipping the physiologically occurring delay of the Haversian remodelling in fractures and osteotomies. Further on there was derived a growth function of the osteones as a regression function r (t) = a + beta X e gamma t. For the rabbit the concrete formula expression r (t) = 50.9 X e-0.094 X t + 17.4 for the animals not treated and r (t) = 42.9 X e-0.067 X t + 8.5 for the electrical stimulated animals has been found.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Detecting plant silica fibres in animal tissue by confocal fluorescence microscopy.

Silica fibres from the inflorescence bracts of the grass Phalaris canariensis L. cause dermatitis, and have been implicated in the aetiology of oesophageal cancer in northeastern Iran. Here we describe a method for labelling these fibres so that they can be located in mammalian tissue. Fluorescein was covalently linked to isolated, purified fibres with the silane coupling agent 3-aminopropyl triethoxysilane. The labelled hairs were then rubbed into the backs of mice. These were later killed and their skin fixed, stained and sliced at a thickness of 250 microns. A confocal laser scanning microscope gave brilliant images of the fibres at any depth up to 100 microns or more beneath the surface of the slice. Fibres penetrated deeply into the dermis. Several cubic millimetres of tissue could be surveyed in 1 h. The number of fibres present was approximately 2 mm-3 initially, falling to 0.1 mm-3 after 7 days.

Animals↗
PubMed2002

Characterization of microcirculatory disturbance in a novel model of pancreatic ischemia-reperfusion using intravital fluorescence-microscopy.

INTRODUCTION: Microcirculatory disturbances caused by ischemia-reperfusion injury (IRI) are the crucial hallmarks of pancreatitis following pancreas transplantation. AIMS: To develop a novel rodent model of normothermic in situ ischemia of a pancreatic tail-segment that simulates the clinical situation of pancreas transplantation by flushing the organ via an inserted microcatheter and thus enables selective treatment of the organ via this access. METHODOLOGY: Four experimental groups were investigated (n = 7 Wistar rats/group): sham animals without ischemia and dissection of the pancreas; control animals with dissection of a pancreatic tail segment pedunculated on the splenic vessels and flushing od this segment with saline via a microcatheter; and two groups of animals treated like controls with a pancreatic ischemia time of 1 hour or 2 hours. With use of intravital epifluorescence microscopy, the microcirculatory damage was characterized by investigation of functional capillary density (FCD) and leukocyte adherence in postcapillary venules (LAV) before ischemia and during a reperfusion time of 2 hours. Dry:wet ratio determinations, light microscopy, and electron microscopic investigations were performed to characterize the histologic organ damage. RESULTS: FCD decreased significantly (p < 0.05) 2 hours after reperfusion in the groups of 1-hour (-29.21%) and 2-hour ischemia (-42.73%), in comparison with baseline values. LAV increased significantly (p < 0.05), 4.3- and 5.8-fold, after 1-hour and 2-hour ischemia during the observation time. The histologic damage was similar to posttransplantation pancreatitis in humans 1 hour after reperfusion. In sham and control animals these alterations were not significant. CONCLUSIONS: The rodent in situ model of pancreatic IRI showed standardized microcirculatory damage dependent on the ischemia time. Offering the possibility of selective treatment by the direct artery access to the ischemic pancreatic area, the model enables investigations of questions related to human pancreas transplantation.

Animals↗
PubMedDate not supplied

Screening for Trichomonas vaginalis infection by use of acridine orange fluorescent microscopy.

The acridine orange test for detection of Trichomonas vaginalis in smears has been adapted for delayed examination of specimens. Mailed-in slides stained by acridine orange were compared with on-site wet mounts; the acridine orange test detected 96% of all positives, whereas only 76% were detected by wet mounts. In a similar comparison with Papanicolaou smears, the acridine orange test detected 89% as compared with 67% detected by Papanicolaou smears.

Acridine Orange↗
PubMed2003

A new method for quantitative cellular imaging on 3-D scaffolds using fluorescence microscopy.

This paper presents a new image processing technique for estimating cell numbers and contours in three-dimensional (3-D) microfabricated scaffolds. The method is based on a statistical approach, and utilizes the extreme value theory, which assumes that cells in the image field are rare, high-intensity events. Confocal microscopy images of fibroblasts on 3-D structures were processed using the method, and the resulting data on cell numbers was compared with countings obtained using a Burker chamber. The results were identical to within a few percent.

3T3 Cells↗