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Results for “Capillary Fragility”

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PubMed1992

Microangiopathy in Ehlers-Danlos syndrome type IV.

In two patients with Ehlers-Danlos syndrome type IV, an autosomal dominant disorder characterized by fragility of large vessels, excessive bruising, and deficiency in type III collagen, capillary microscopy was performed at the nailfold. Indocyanine green and Na-fluorescein were used as fluorescent tracers. Both patients exhibited microangiopathy of the skin capillaries with microbleedings, presence of microaneurysms and increased transcapillary diffusion. Microvascular involvement appears to be an additional manifestation of the syndrome.

Adult↗
PubMed2006

Methylation-dependent fragment separation: direct detection of DNA methylation by capillary electrophoresis of PCR products from bisulfite-converted genomic DNA.

Fundamental to understanding the role of cytosine (C) methylation in genomic DNA (gDNA) is the need for robust analysis methods to determine the location and degree of this modification. We report a novel method for methylation detection by denaturing capillary electrophoresis (CE) using standard fragment analysis conditions. Bisulfite treatment of gDNA will selectively deaminate C but not 5-methylcytosine (5mC). Amplicons generated from bisulfite-converted gDNA are analyzed immediately after PCR using a 6-carboxy fluorescein (6-FAM) dye-labeled primer. The amplicons from methylated and unmethylated gDNA separate based solely on base composition due to the presence of multiple C versus thymine (T) differences. By direct detection of PCR amplicons following PCR using primers that anneal independent of methylation status, the overall workflow from gDNA sample input to data analysis is relatively simple. Furthermore, the same PCR product is suitable for additional analyses such as direct sequencing, cloning and sequencing, single-base extension, and post-PCR incorporation of a modified dCTP, the latter of which allows resolution of amplicons with as little as a single C/T difference. We show the utility of this novel CE detection assay by analyzing the hypermethylated region of the fragile-X FMR1 locus.

Base Sequence↗
PubMed1975

Junctions in the central nervous system of the cat. IV. Interendothelial junctions of cerebral blood vessels from selected areas of the brain.

Interendothelial membrane contacts in different segments of brain blood vessels were investigated by the freeze-etching technique. The study demonstrated that the endothelial cells of the pre- and postcapillary segments were coupled by elaborate zonulae occludentes. These tight junction formations encompassed gap junctions of different sizes and distribution. The globules of the pre- and postcapillary tight junctions revealed a great fragility which led to an atypical distribution of the sealing elements. In the "typical" brain capillaries the endothelial cells were connected by continuous tight junctions. In contrast to the structural continuity of these formations the fenestrated segments of capillaries in the choroid plexus and area postrema demonstrated discontinuous fasciae occludentes. They were composed of rows of individual particles which should be regarded primarily as focal in nature.

Blood-Brain Barrier↗
PubMedDate not supplied

Effects of turbulent stresses upon mechanical hemolysis: experimental and computational analysis.

Experimental and computational studies were performed to elucidate the role of turbulent stresses in mechanical blood damage (hemolysis). A suspension of bovine red blood cells (RBC) was driven through a closed circulating loop by a centrifugal pump. A small capillary tube (inner diameter 1 mm and length 70 mm) was incorporated into the circulating loop via tapered connectors. The suspension of RBCs was diluted with saline to achieve an asymptotic apparent viscosity of 2.0 +/- 0.1 cP at 23 degrees C to produce turbulent flow at nominal flow rate and pressure. To study laminar flow at the identical wall shear stresses in the same capillary tube, the apparent viscosity of the RBC suspension was increased to 6.3 +/- 0.1 cP (at 23 degrees C) by addition of Dextran-40. Using various combinations of driving pressure and Dextran mediated adjustments in dynamic viscosity Reynolds numbers ranging from 300-5,000 were generated, and rates of hemolysis were measured. Pilot studies were performed to verify that the suspension media did not affect mechanical fragility of the RBCs. The results of these bench studies demonstrated that, at the same wall shear stress in a capillary tube, the level of hemolysis was significantly greater (p < 0.05) for turbulent flow as compared with laminar flow. This confirmed that turbulent stresses contribute strongly to blood mechanical trauma. Numerical predictions of hemolysis obtained by computational fluid dynamic modeling were in good agreement with these experimental data.

Animals↗
PubMed1999

Silicate entrapped columns--new columns designed for capillary electrochromatography.

Designed especially for capillary electrochromatography (CEC), silicate-entrapped columns are made by trapping particles of chromatographic packing material in a network of silica. Once entrapped, the capillary no longer requires frits. This renders a more homogeneous and stable packed bed. Accidental breakage of the fragile frits is not an issue with these robust columns. Columns packed with reverse-phase material subjected to silicate entrapment demonstrated faster separations of retained analytes and increased efficiencies compared with nonentrapped columns. The method was also used to prepare chiral CEC columns by entrapping a molecular imprinted polymeric (MIP) packing having minimal surface charge density, thus being unable alone to support sufficient electroosmotic flow for CEC.

Chromatography, Liquid↗
PubMed1990

Rupture of coronary vasa vasorum as a trigger of acute myocardial infarction.

Some controversy has always existed regarding the presence and extent of the vasa vasorum--the nutrient vessels in the wall of the human aorta--in the coronary arteries. Now, cinemicrographic studies using silicone polymer injections in cleared human hearts have identified the vasa vasorum of coronary arteries, revealing evidence of neovascularization in the region of atherosclerotic plaques. These studies suggest an important role for the vasa vasorum in the pathogenesis of coronary atherosclerosis and its sequelae, especially intramural hemorrhage and vascular spasm. The wall of the human coronary artery in regions of atherosclerotic injury may be particularly rich in capillary vessels of the vasa vasorum. From this, the evidence suggests that with the morning increase in blood pressure, fragile neovascular structures of the vasa vasorum may be more prone to rupture and may be responsible, in part, for the circadian variation in myocardial infarction.

Adult↗
PubMed1989

Age-related changes in regional patterns of blood-brain barrier breakdown during epileptiform seizures induced by pentylenetetrazol.

Age related changes in blood-brain barrier (BBB) permeability to macromolecules were investigated during seizures induced by pentylenetetrazol in rats aged from 6 to 120 days. Evans blue was used as a visual indicator of BBB integrity. BBB leakage due to seizures was present only in animals in which the mean arterial blood pressure (BP) rose with the seizure onset. Although considerable BBB damage was found partly in similar areas in young and adult rat brains, in adults the leakage of Evans blue was most intense in preoptic area, colliculus inferior, hypothalamus and cerebellum whereas the BBB opening was comparatively rare, in the same areas of young brains. In 6- and 15-day-old rats which did not differ in BP changes from the adults, the leakage was extremely intense in hypothalamus and hippocampus and in contrast to 30- or 120-day-old rats there was no leakage of Evans blue in preoptic area and cerebral cortex. From the results obtained, the conclusion may be drawn that the brain regions which are vulnerable to seizures induced by pentylenetetrazol differ markedly in developing and adult rats. On the other hand, in adult animals, either certain brain areas are more vulnerable to pentylenetetrazol or the BBB has an increased fragility particular to seizure activity. These results indicate that the sensitivity of BBB mechanisms may depend on proliferation of capillaries and changes in their internal structure and may emphasize it.

Aging↗
PubMed2005

Hemihyperplasia with Ehlers-Danlos syndrome like skin changes.

Hemihyperplasia is a condition characterized by asymmetric overgrowth of one or more body parts. It may be an isolated finding or may be associated with various syndromes like Beckwith-Weidemann syndrome, Klippel-Trenaunay-Weber syndrome, Proteus syndrome etc. Pigmentary skin lesions and capillary malformations are commonly seen in cases of hemihyperplasia. We report a case of hemihyperplasia with associated skin hyperextensibility, varicose veins, skin fragility, easy bruising and papery scars, on the side of hyperplasia. This is the first report of association of isolated hemihyperplasia with skin changes similar to Ehlers-Danlos syndrome.

Abnormalities, Multiple↗
PubMed2002

Morphological changes in the sciatic nerve of diabetic rats treated with low molecular weight heparin OP 2123/parnaparin.

This study points out the early alterations that affect the sciatic nerve of rats with experimentally induced diabetes. It emphasizes the advantages deriving from treatment with low molecular weight heparin (LMWH) OP 2123/parnaparin and correlates these findings with observations emerging from a review of the relevant literature. In fact, the number and diameter of the capillaries within the sciatic nerve of diabetic rats appear to be increased consistent with a microangiopathy (the main characteristic of which is the fragility of new vessels), that is related to the evolution of diabetes in humans and animals. Our results suggest a possible therapeutic role for OP 2123/parnaparin in both diabetic neuropathy and microangiopathy, frequent complications of diabetes.

Animals↗