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At least 109 records · Page 6Linked to original sources
PubMed2004

A model based method for retinal blood vessel detection.

Retinal blood vessels are important structures in ophthalmological images. Many detection methods are available, but the results are not always satisfactory. In this paper, we present a novel model based method for blood vessel detection in retinal images. It is based on a Laplace and thresholding segmentation step, followed by a classification step to improve performance. The last step assures incorporation of the inner part of large vessels with specular reflection. The method gives a sensitivity of 92% with a specificity of 91%. The method can be optimized for the specific properties of the blood vessels in the image and it allows for detection of vessels that appear to be split due to specular reflection.

Algorithms↗
PubMed2006

Orientation of endothelial cell division is regulated by VEGF signaling during blood vessel formation.

New blood vessel formation requires the coordination of endothelial cell division and the morphogenetic movements of vessel expansion, but it is not known how this integration occurs. Here, we show that endothelial cells regulate division orientation during the earliest stages of blood vessel formation, in response to morphogenetic cues. In embryonic stem (ES) cell-derived vessels that do not experience flow, the plane of endothelial cytokinesis was oriented perpendicular to the vessel long axis. We also demonstrated regulated cleavage orientation in vivo, in flow-exposed forming retinal vessels. Daughter nuclei moved away from the cleavage plane after division, suggesting that regulation of endothelial division orientation effectively extends vessel length in these developing vascular beds. A gain-of-function mutation in VEGF signaling increased randomization of endothelial division orientation, and this effect was rescued by a transgene, indicating that regulation of division orientation is a novel mechanism whereby VEGF signaling affects vessel morphogenesis. Thus, our findings show that endothelial cell division and morphogenesis are integrated in developing vessels by flow-independent mechanisms that involve VEGF signaling, and this cross talk is likely to be critical to proper vessel morphogenesis.

Animals↗
PubMedDate not supplied

Cardiovascular tissue engineering: constructing living tissue cardiac valves and blood vessels using bone marrow, umbilical cord blood, and peripheral blood cells.

Although atherosclerosis and valvular heart disease are among the leading causes of morbidity and mortality in developed nations, the substitute blood vessels and heart valves currently available all have significant limitations. During the past 10 years, a new field called tissue engineering has emerged, and several research groups are focusing their efforts on constructing living tissue replacement blood vessels and heart valves. In 2001 several exciting developments occurred with the use of progenitor and stem cells. This article introduces the essential concepts of cardiovascular tissue engineering, reviews achievements in the field, discusses the basic developmental biology of heart valves and blood vessels, and summarizes the 2001 research on progenitor and stem cells.

Blood Vessels↗
PubMed2006

Autologous blood vessels engineered from peripheral blood sample.

OBJECTIVE: Although many efforts have been made to generate small-diameter (< or =5mm) vascular grafts by means of tissue engineering, improvement in patency and functionality still remains a great challenge. It is our hypothesis that to achieve long-term functionality and patency, not only the complete lining with endothelial cells but also full biocompatibility is essential. DESIGN: The aim was the development of a conduit from a scaffold and endothelial progenitor cells (EPC) separated from peripheral blood of a single donor. MATERIALS AND METHODS: EPC and a fibrin preparation were separated from porcine peripheral blood. Fibrin segments were generated seeded with EPC and were perfused in a bioreactor in vitro. RESULTS: From 100ml blood 12-15 cm long fibrin tubes were successfully generated lined with endothelial-like cells. Seeded tubes showed a remarkable elasticity and burst strength up to 90 mm mercury. CONCLUSIONS: Stable fibrin tubes were successfully generated completely lined with an endothelium-like monolayer from fibrin and EPC, both isolated from the same volume of blood. Although their stability is not those needed for arterial grafting, our results raise the hope, that with distinct improvements in future studies functional autologous vascular grafts could be engineered from the patient's own blood.

Animals↗
PubMed1996

[The individualization of activities of blood vessels].

The functional activities of blood vessels in various organs have their own characteristics, named individuality of blood vessel. One of the most outstanding characteristics is that the responses of blood vessels in various organs to the same stimulation are different, even contradictory. This physiological characteristic of the blood vessel guarantees that the blood vessel can make adjustable responses in varying parts and under different conditions to fulfil the functional tasks of circulatory system and to meet the demands of blood supply of recipient organs. The study of vascular individualization would benefit to explain the mechanism of blood vessel activities and is also important in the study of pathogenesis of vascular diseases. This paper gives a brief description on the vascular mechanisms contributing to the individualization of blood vessel.

Animals↗
PubMed1997

Distribution of amyloid deposits in the cerebral white matter of the Alzheimer's disease brain: relationship to blood vessels.

The relationship between blood vessels and amyloid beta (A beta)-protein deposits in the cortex of the Alzheimer's disease (AD) brain is still controversial. It is difficult to distinguish whether the A beta deposits are associated with blood vessels or neurons because of their widespread and complicated distribution. In this study, we investigated the distribution of A beta deposits in the cerebral white matter of the AD brain as a means of removing the bias of neuronal distribution. An immunohistochemical study of 100 serial sections, after pretreatment with formic acid for 24 h, revealed the presence of A beta deposits in the cerebral white matter of the AD brain. There are various morphological types of plaques containing A beta deposits in the white matter, the same as in the gray matter. While the majority of A beta deposits was of a circumscribed type such as "classic" and "primitive" plaques, "compact" and "diffuse" plaques were also observed in the white matter. The location of the A beta deposits was, for the most part, immediately beneath the gray matter. The distribution of A beta deposits in the white matter was found to correspond to the orientation of the blood vessels. Serial sections also revealed that these A beta deposits were distributed along a single blood vessel. These findings suggest that the deposition of A beta in the cerebral white matter is primarily related to the blood vessels.

Aged↗
PubMed1976

Evidence for central innervation of intracerebral blood vessels: local cerebral blood flow measurements and histofluorescence analysis by the sucrose-phosphate-glyoxylic acid (SPG) method.

Local cerebral blood flow using a hydrogen clearance technique and a histofluorescent modification of the glyoxylic acid method (SPG method) were used in rats to study the influence of brain stem centers on intracerebral flood flow. Recording of local cerebral blood flow following stimulation of the locus coeruleus but not of the ventrocaudal nucleus of the lateral lemniscus showed a significant blood flow decrease in anterior brain regions where innervation of ascending adrenergic pathways are known to occur. Adrenergic innervation using the SPG method (sucrose-potassium phosphate-glyoxylic acid) histofluorescence could not be verified in the rat but was evident in the dog and rhesus monkey brain sections examined. The results provide additional evidence suggestive of a role for the locus coeruleus in modulating or controlling intracerebral blood flow in these animals. In addition, histofluorescent visualization of intracerebral vessels in dog and monkey show an association between adrenergic varicosities and arterioles in bilaterally ganglion-ectomized animals. This adrenergic-vascular association was not seen in the rat. The results provide further evidence that central adrenergic innervation from the brain stem may control intracerebral blood flow independent of sympathetic influence.

Adrenergic Fibers↗
PubMed1990

Organization of the lymphatic vessels and their relationships to blood vessels in rabbit Peyer's patches.

The three-dimensional organization of the lymphatic vessels and their relationship to blood vessels in rabbit Peyer's patches were demonstrated by scanning electron microscopy (SEM) of corrosion casts and of tissues. The interconnected central lacteals in the villi overlying the interfollicular area were connected with the lymphatic plexus in the area. There were many blind-ending lymphatic vessels in the upper part of the interfollicular area. These lymphatics gradually fused and formed perifollicular lymphatic sinuses which surrounded the lateral surfaces and bottoms of the follicles. There were no lymphatic vessels within the dome and the follicle. The perifollicular lymphatic network surrounded the capillary network of the follicle. Between the perifollicular lymphatic networks in the interfollicular area were many high endothelial venules (HEVs) which collected the capillaries in the dome and the follicle. The voluminous perifollicular lymphatic sinuses seemed to have a great potential capacity as both reservoirs and as drainage routes for fluid and lymphocytes. The close association of HEVs with the perifollicular lymphatic vessels seemed to facilitate the prompt drainage of fluid and macromolecules leaking out of HEVs during lymphocyte migration into the lymphatics. That the HEVs are downstream of the capillaries in both the dome and the follicle suggests that substances such as cytokines may be involved in the induction of the post capillary venules into HEVs.

Animals↗
PubMedDate not supplied

Structure and function of endometrial blood vessels.

The endometrial blood vessels form a vascular bed with a number of unusual properties. Unlike most adult vasculature these blood vessels undergo constant cycles of growth and regression during the reproductive life of the female. This short review covers a number of different aspects relating to endometrial vascular structure and function during endometrial growth, implantation, endometrial regression and menstruation. Video footage from in-vivo microscopy of the rat endometrial subepithelial capillary plexus on the morning of day 6 of pregnancy is included in the CD-ROM. This shows the dramatic changes that occur to the endometrial capillaries at the time of embryo implantation.

Animals↗
PubMed1990

[Studies of age-related changes in intracerebral small vessels of rat--do all cerebral blood vessels get aging concurrently?].

Age-related changes of intracerebral small blood vessels were studied with light and electron microscopes. In the first step of this investigation (Experiment 1), Wistar rats of 4-month-old were employed to determine the appropriate concentration of administrated HRP (horseradish peroxidase) for surveying the uptake capacity of HRP. Each rat was injected HRP intravenously under light anesthesia with ether. After 30 minutes, rat brains were excised and prepared for stretch specimen (Mato et al, 1979). Light microscopically, corresponding with decrease of the concentration of injected HRP, the reaction products of HRP in the cytoplasm of fluorescent granular perithelial (FGP) cells reduced linearly and the injection of 5 mg HRP revealed only FGP cells in the parietotemporal region of cerebral cortex. Referring to the results mentioned above, 10 mg of HRP was decided to be applicable dose for the following study. In the next experiment (Experiment 2), Wistar rats of 4-month-old, 1.7-year-old and 2.4-year-old were used for the study on the relation between morphological alteration of vascular cells and changes of uptake capacity of FGP cells in aging. At 30 minutes after the injection of 10 mg, rats were perfused and fixed with 2.5% glutaraldehyde and 2% paraformaldehyde under light anesthesia. Then, rat brains were removed and divided coronally into three parts. After slicing with Vibratome, number and distribution of FGP cells were studied under light microscope. The other specimens were dehydrated and embedded in Epon 812. The ultrastructure of vascular cells (endothelial and smooth muscle cells) and FGP cells at each age was examined with JEM 2000 EX electron microscope. Supplementary, ultrastructure of middle cerebral and retinal arteries of 2.4-year-old rats was also studied for comparison with that of the intracerebral (cortical)small vessels. The findings obtained from Experiment 2 could be summarized as follows; 1. Light microscopically, in 4-month-old and 1.7-year-old rats, FGP cells including positive granules of HRP were often recognizable along small blood vessels of cerebrum, especially in cerebral cortices. In 2.4-year-old rats, the numbers of FGP cells with positive granules of HRP decreased significantly (p less than 0.01). It was confirmed that the uptake capacity of FGP cells reduced with aging. But, exceptionally, regardless from aging of animals, FGP cells belonging to a few special vessels in the parietotemporal area of cerebral cortices included many and intense reaction products. 2. Electronmicroscopically, the vascular cells changed in appearance and contents with aging.(ABSTRACT TRUNCATED AT 400 WORDS)

Aging↗
PubMed1988

The activity of diagnostic enzymes and the concentration of lipids in the blood vessels of cattle.

Blood vessel walls are shown to contain creatine phosphokinase, lactate dehydrogenase, gamma glutamyl transpeptidase and aspartate transaminase activity. The activity of these enzymes in the serum may be enhanced by leakage from damaged blood vessels. The activity of the enzymes alanine transaminase and alkaline phosphatase as well as the content of triglycerides, cholesterol and lipoproteins are very low in the vascular tissue and are unlikely to be of diagnostic value in vascular tissue injury.

Animals↗