Closure of umbilical blood vessels.
Explore the source record for details and available documents.
Animals↗
SEARCH · Search PubMed
Results for “BLOOD VESSELS”
Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
[Experimental study on mechanical dilation of blood vessels].
Explore the source record for details and available documents.
Animals↗
Photothermal coagulation of blood vessels: a comparison of high-speed optical coherence tomography and numerical modelling.
Optical-thermal models that can accurately predict temperature rise and damage in blood vessels and surrounding tissue may be used to improve the treatment of vascular disorders. Verification of these models has been hampered by the lack of time- and depth-resolved experimental data. In this preliminary study, an optical coherence tomography system operating at 4-30 frames per second was used to visualize laser irradiation of cutaneous (hamster dorsal skin flap) blood vessels. An argon laser was utilized with the following parameters: pulse duration 0.1-2.0 s, spot size 0.1-1.0 mm, power 100-400 mW. Video microscopy images were obtained before and after irradiations, and optical-thermal modelling was performed on two irradiation cases. Time-resolved optical coherence tomography and still images were compared with predictions of temperature rise and damage using Monte Carlo and finite difference techniques. In general, predicted damage agreed with the actual blood vessel and surrounding tissue coagulation seen in images. However, limitations of current optical-thermal models were identified, such as the inability to model the dynamic changes in blood vessel diameter that were seen in the optical coherence tomography images.
Animals↗
Hypertensive breakdown of cerebral but not of retinal blood vessels in rhesus monkey.
Acute hypertension, induced either by intravenous injection of metaraminol bitartrate (Aramine), infusion of isotonic saline into the common carotid artery, or a combination of both procedures did not in the rhesus monkey lead to breakdown of the blood-retinal barrier. Whereas the cerebral vasculature was made permeable to blood-borne dye at carotid pressure above 160 mm Hg, the retinal blood vessels were intact even at pressures as high as 310 mm Hg. Hypertensive blood-brain barrier opening was associated with neurologic defects and brain edema. The results indicate that the retina is more resistant to acute hypertension than is the brain. The greater resistance in the retina may be due to the high number of contractile, perivascular mural cells counteracting increased intravascular hydrostatic pressure. An alternative or supplementary explanation is that choroidal and retinal blood vessels are better protected from surges in blood pressure than are brain blood vessels. Differences between the innervation of brain and ocular blood vessels could account for this.
Animals↗
[Association between the hemodynamic and rheological parameters in the micro blood vessels in vivo].
Considering the experimental data obtained earlier, regarding the shift velocity in the micro blood vessels in vivo, and general theses of liquid mechanics and rheology of the non-Newtonian liquids, a generalized ratio between the hemodynamic and rheological parameters in the micro blood vessels in vivo are overviewed. These are: pressure difference--DeltaP, volume of blood flow--Q, linear velocity of blood flow, viscosity of Newtonian liquid--k, effective viscosity of the blood in a vessel in vivo eta(effect), and index of rheological behavior--n, which was determined earlier in our laboratory. These parameters are observed in the live blood vessels of microcirculatory bed, in all regimes of the blood flow characteristic for the in-vivo vessels.
Blood Flow Velocity↗
The role of blood vessels and lungs in the dissemination of Naegleria fowleri following intranasal inoculation in mice.
Primary amoebic meningoencephalitis (PAM) was induced in mice by intranasal inoculation of Naegleria fowleri (Singh et Das, 1970) to study the role of the blood vessels and lungs in the early and later stages in this disease. Upon culturing blood and lung tissue obtained at 24-, 36-, 48-, 72-, 96-, and 120-hour time periods, it was found that amoebae grew only from blood and lung tissue obtained at the 96 and 120 hour time periods. Paraffin sections of the head revealed small foci of acute inflammation and amoebae within the olfactory bulb of the central nervous system (CNS) at 24 hours. Amoebae were not observed within blood vessels of the CNS until 96 and 120 hours. Also, amoebae were observed within the connective tissue surrounding blood vessels and sutures of the skull, bone marrow, and venous sinusoids between the skull bone tables at 96 and 120 hours. No amoebae or acute inflammatory reactions were observed in the lung sections from any time period and indirect immunofluorescence microscopy was negative for N. fowleri. This study provides evidence that neither blood vessels nor lungs provide routes for N. fowleri to the CNS during the early stages of PAM and that amoebae enter veins of the CNS and bone marrow during later stages of the disease.
Amebiasis↗
Evaluation of observer performance in detecting blood vessels on simulated angiographic images.
This paper presents methods for evaluating the effects of technical factors on observers' detection of small blood vessels in angiographic images. A fixed set of physical parameters was used to generate computer-simulated angiographs that contained blood vessels of various diameters. Observers' judgments about each set of images permitted estimation of the receiver operating characteristic (ROC) curves for vessel detection and of the probability of correctly locating the vessels. Both parametric and nonparametric methods were used to characterize the ROC curves. Three different, but theoretically related, measures of vessel detectability varied systematically with changes in the blood vessel's diameter, reflecting changes in observer performance.
Angiography↗
Axon regeneration through blood vessel allografts after cyclosporine treatment.
The present study describes the usefulness of blood vessel allografts to repair gaps in rat peripheral nerve after immunosuppression with cyclosporine. Isogeneic strains of rats with known histoincompatibility were used for this study. A 10-mm gap was created in the peroneal nerve of host Fischer rats. The gap was bridged by a 12-mm section of internal carotid artery removed from a Buffalo strain of rat. The host rats were divided into two groups. One group received no immunosuppression, whereas the other group was treated with cyclosporine. Untreated control rats immunologically rejected the allografted vessels and were unable to support host axonal regeneration through them. On the other hand, in cyclosporine-treated rats the allografted vessels survived. The regenerating host axons reorganized to form a functional nerve within the vessel conduit. The regenerated axons persisted even after rejection of the allografted vessel caused by cessation of immunotherapy. These results show that blood vessel allografts can serve as an effective conduit for reorganization of regenerated nerves and can bridge gaps in peripheral nerves.
Animals↗
Designer blood vessels and therapeutic revascularization.
Inadequate vascular perfusion leads to fatal heart attacks, chronic ulcers, and other serious clinical conditions. The body's capacity to restore vascular perfusion through angiogenesis and arteriogenesis is often impaired by pre-existing disease, and availability of native replacements for nonfunctional arteries is limited in many patients. Thus, recreating blood vessels of various calibres through novel engineering technologies has emerged as a radical option among therapeutic strategies for revascularization. Ranging from artificial, recycled or reassembled natural conduits to sophisticated microdevices, we refer to these as 'designer blood vessels'. Our common efforts to continuously improve vascular replacement design have provided many clues about our own blood vessels, but nature's ability to create nonthrombogenic, immunocompatible, strong, yet biologically responsive blood vessels remains unparalleled. Just as art reproductions never equal the original masterpiece, designer blood vessels may never attain nature's perfection. Nevertheless, they will provide a valuable option as long as they come close enough and are available to many.
Humans↗
The collagen of the gingiva and of its blood vessels.
The collagen of the gingiva and that of its blood vessels of several animal species and of man were studied with the scanning electron microscope following corrosion with pancreatin at 0.3%. The gingival collagen forms fundamental cells or fasciculi that are distributed throughout the entire territory. In the interior of the cells there are small balls either detached or in clusters. Because of the contact and the fusion of these balls with the collagenic fasciculi, and due to their resistance to the pancreatin corrosion procedure, we believe them to be condensations of collagen. The approximate size of these balls was 2 micrometer. The fasciculi that surround these cells have either the form of bundles or are united in bands. There is an abundance of blood vessels in the gingiva and they are surrounded by collagen. This collagen can assume any of varied positions. The relations that exist between the vascular collagen and that of the gingiva are different in every case.
Animals↗
Analysis of the appearance of fenestrations in the blood vessels of the fetal sheep pituitary.
Using electron microscopy, the appearance of fenestrations within blood vessels of the fetal sheep pituitary gland was studied at 40, 80 and 122 days of gestation (term = 150 days). While fenestrations were extremely rare at 40 days of gestation, blood vessels contained characteristic regions of narrow endothelium, termed attenuations. There was an increase in the frequency of fenestrations with increasing gestational age, while there was a decrease in the number of attenuations, to the extent that the latter were not observed at 122 days of gestation. In order to examine the 'leakiness' of vessels with relatively few fenestrations, the fate of intracardially injected horseradish peroxidase (HRP) was studied in 50- and 51-day fetuses. Flocculant HRP reaction product was observed in the lumen of pituitary blood vessels, within endothelial cells, as well as within perivascular spaces and intercellular spaces between pituitary glandular cells. HRP was also observed in internalised vesicles within pituitary cells. These results indicate that even though fenestrations are scarce at early gestational ages, blood-borne substances can leave the portal network to interact with pituitary cells. The previously reported patency of the portal vascular system in the immature fetus is supported by our observations.
Animals↗
Platelets and blood vessels: the adhesion event.
Circulating blood platelets attach to damaged blood vessels by specific adhesion molecules. In the human arterial circulation, a unique 'shear-dependent' mechanism governs adhesion by a single receptor-ligand (glycoprotein Ib-von Willebrand factor) pair. Here, Gerald Roth reviews recent data that provide insights into the functions of these molecules.
Amino Acid Sequence↗
Development and remodeling of cerebral blood vessels and their flow in postnatal mice observed with in vivo videomicroscopy.
Changes of blood vessels in the mouse somatosensory (barrel) cortex were assessed from birth (P0) to adulthood. Surface vessel anatomy and flow were observed directly with videomicroscopy through closed cranial windows and with intravascular fluorescent tracers. Histology was used to determine the internal capillary density. At birth, arterioles had numerous anastomoses with each other, pial capillaries formed a dense surface plexus, and pial venules and veins were relatively small and irregular. Morphological changes over the next 2 weeks included (a) fewer arteriolar anastomoses, (b) formation and growth of venules, (c) more uniform diameters of all types of vascular segments, (d) increase in intraparenchymal capillary length density (Lv), and (e) decreases in superficial capillary density and diameters. A simple morphological test showed that wall shear rates at arteriolar branch points were matched on average in neonates and adults. Flow characteristics in single vessels were evaluated. In arterioles of like diameters, (a) Vmax, (b) peak wall shear rates, and (c) peak flows were similar at all ages; (d) velocity was very high in occasional arteriovenous (AV) shunts in newborns; and (e) flow in arteriolar anastomoses was slow and variable. Although flow was heterogeneous in all types of vessel, the marked similarities in newborn and adult mice of average peak velocities and calculated wall shear rates in arterioles of the same size suggest that blood flow regulates in part the remodeling of blood vessels during development (Rovainen et al., 1992). The rodent barrel cortex undergoes major neuronal and vascular development, functional differentiation, and remodeling during the first weeks after birth. It provides special opportunities for testing how blood vessels grow and adapt to supply the local metabolic requirements of neural modules in the brain.
Animals↗
Thermal role of a blood vessel running through a temperature gradient.
A mathematical model of a blood vessel running through a linearly varying temperature field suggests that if the Graetz number of the flow is between 1 and 10, small variations in the flow rate result in large differences in blood temperature drop. Single separate blood vessels of the right Graetz number may have substantial thermoregulatory capabilities.
Blood Vessels↗
Development of glia and blood vessels in the internal capsule of rats.
We have explored two aspects of internal capsule development that have not been described previously, namely, the development of glia and of blood vessels. To these ends, we used antibodies to glial fibrillary acidic protein (GFAP) and to vimentin (to identify astrocytes and to radial glia) and Griffonia simplicifolia (lectin; to identify microglia and blood vessels). Further, we made intracardiac injections of Evans Blue to examine the permeability of this dye in the vessels of the internal capsule during neonatal development. Our results show that large numbers of radial glia, astrocytes and microglia are not labelled with these markers in the white matter of the internal capsule until about birth; very few are labelled earlier, during the critical stages of corticofugal and corticopetal axonal ingrowth (E15-E20). The large glial labelling in the internal capsule at birth is accompanied by a dense vascular innervation of the capsule; as with the glia, very few labelled patent vessels are seen earlier. After intracardiac injections of Evans Blue, we find that the blood vessels of the internal capsule are not particularly permeable to Evans Blue. At each age examined (P0, P5, P15), blood vessels are outlined very clearly and there is no diffuse haze of fluorescence within the extracellular space, which is indicative of a leaky vessel. There are three striking differences between the glial environment of the internal capsule and that of the adjacent thalamus. First, the internal capsule is never rich with radial glial fibres (vimentin- and GFAP-immunoreactive) during development (except at P0), whereas the thalamus has many radial fibres from very early development (E15-E17). Second, astrocytes (vimentin- and GFAP-immunoreactive) first become apparent in the internal capsule (E20-P0) well before they do in the thalamus (P15). Third, the internal capsule houses a large transient population of amoeboid microglia (P0-P22), whereas the thalamus does not; only ramified microglia are seen in the thalamus. In summary, our results indicate that all three types of glia in the internal capsule are associated closely with the vasculature, suggesting they may play a role in the development of the blood-brain barrier among the vessels in this white matter region of the forebrain.
Animals↗
Alteration in alpha- and beta-adrenoceptor profile of rabbit knee joint blood vessels due to acute inflammation.
Experiments were performed to investigate the nature of - and -adrenoceptors in blood vessels supplying the posterior capsule of the acutely inflamed rabbit knee joint, and results were compared to findings from previous experiments on the normal joint, to assess any alteration which may occur in the adrenoceptor profile due to the inflammation process. Electrical stimulation of the posterior articular nerve resulted in vasoconstriction which was reversed to vasodilatation by phentolamine and yohimbine. The dose-response curves to close intra-arterial injection of -adrenoceptor agonists showed a rank-order potency of: adrenaline = phenylephrine = clonidine. The adrenaline dose-response curve was shifted to the right by administration of antagonists with a rank-order potency of: phentolamine = yohimbine = prazosin. At this stage of the experiments there was an equal response of 1- and 2-adrenoceptors in blood vessels of the acutely inflamed rabbit knee joint. In another group of animals the neurally mediated vasodilatation, which appeared after administration of phentolamine, was completely blocked by propranolol, and was reduced by about 50 % by atenolol. The dose-response curves to close intra-arterial injection of -adrenoceptor agonists showed a rank-order potency of: isoprenaline > salbutamol = dobutamine. The isoprenaline dose-response curve was shifted to the right by administration of antagonists with a rank-order potency of: propranolol > atenolol. These experiments also showed an almost equal response of 1- and 2-adrenoceptors in blood vessels of the acutely inflamed rabbit knee joint. Overall, compared to previous experiments on the normal joint in which 2- and 1-adrenoceptor responses predominated, acute inflammation resulted in a shift from 2- towards 1- and from 1- towards 2-adrenoceptor responses.
Acute Disease↗
Retinoblastoma. The relationship of proliferating cells to blood vessels.
In 150 retinoblastomas the authors found a uniform thickness of the cuff of viable retinoblastoma cells that surrounds blood vessels. The mean thickness was 98.7 microns with a standard deviation of 11.9 microns. The cross-sectional area of the cuff was negatively correlated with the mitotic activity in the cuff and positively correlated with the diameter of the central vessel. The mitotic activity in the cuff of cells was inversely related to the distance from the central blood vessel. When the cuff was divided into three concentric rings, the inner ring contained a mean of 6.2 mitotic figures, the middle ring contained a mean of 2.9 mitotic figures, and the outer ring contained a mean of 0.6 mitotic figures. This pattern of growth is similar to that observed in other rapidly growing neoplasms in humans and experimental animals. In these tumors this pattern results from reduction in oxygen tension with increased distance from the central blood vessel.
Blood Vessels↗
Clinical evaluation of scanning laser polarimetry: I. Intraoperator reproducibility and design of a blood vessel removal algorithm.
AIMS: To evaluate the reproducibility of the retardation values (change in polarisation) obtained with the scanning-laser polarimeter in a series of normal subjects and glaucoma patients. To improve the analysis of the raw data by devising and evaluating a blood vessel removal algorithm. METHODS: Scanning laser polarimetry was performed on 10 normal subjects and 10 glaucoma patients. A series of six images was obtained from each eye. The normal subjects were re-imaged 3 months after their initial assessment. The retardation values obtained from each eye were analysed using the authors' own methods, including the use of an algorithm to remove blood vessels from the polar profiles. The reproducibility of these measurements and the performance of the blood vessel removal algorithm were assessed. RESULTS: The "individual point" coefficient of variation was approximately 12.5% for normal subjects and 17.0% for glaucoma patients. The "integral" coefficient of variation for these groups was approximately 5.5% and 9.5% respectively. The reproducibility of the measurements did not improve with an increased number of measurements. There was no difference in the reproducibility of the measurements in normal subjects over time. The blood vessel removal algorithm improved the reproducibility of the measurements when the shape of the profile was assessed. CONCLUSION: The intraoperator reproducibility of retardation values obtained with the scanning laser polarimeter is satisfactory for its use as a clinical tool. The use of a blood vessel removal algorithm improves the reproducibility of the measurements and also assists the clinician in the interpretation of the polar profiles. Furthermore, it allows the construction of normal database polar profiles, thereby enabling the identification, location and quantification of retinal nerve fibre layer damage in an "at risk" individual's polar profile.
Algorithms↗