Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “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.

At least 1,765 records · Page 98Linked to original sources
PubMed1991

Effects of pulsatile flow pattern and each stage of pressure increasing, constant and decreasing, respectively upon inelastic deformation of blood vessel.

The aim of this study is to elucidate the relation of the inelastic expansive deformation of natural blood vessel and the degradation of elasticity to the time pattern of circulating pulsatile pressure flow. When pulsatile pressure amplitude (delta P = Pmax - Pmin) becomes smaller due to Pmin increasing, the blood vessel is subject to creep deformation. In this sense, pulsating pressure will play a role in avoiding creep effect. Fluctuation of maximum pressure Pmax will induce the increase of inelastic deformation and the decrease of rigidity of the blood vessel. The inelastic deformation and the decrease of rigidity in blood vessel is induced at the stage of pressure amplitude rising from a lower one to a higher, but not during pressure amplitude (delta P) kept constant nor at the pressure amplitude decreasing stage. In order to reduce the degradation of mechanical properties of blood vessel, it may be effective to avoid the increase of Pmin and the variability of Pmax.

Biomechanical Phenomena↗
PubMed1990

Coronary angiography and thallium-201 single photon emission computed tomography in multiple vessel coronary artery disease.

Polar presentations of selective coronary angiography and myocardial 201Tl SPECT were compared in 141 patients with multiple vessel disease, 80 with 3-vessel disease, 34 with 2-vessel disease and 27 post-bypass patients. Perfusion defects were present in 125/141 patients (89%) and were located within the area supplied by 194/359 stenotic arteries (54%) and 9 non-stenotic arteries. The type and extent of disease was correctly indicated by 201Tl SPECT in 16/80 patients (20%) with 3-vessel disease, 5/34 patients (15%) with 2-vessel disease and 8/27 post-bypass patients (30%). Perfusion defects indicated the artery with the most severe lesion in 107/125 patients (86%). False negative isotope studies were present in 15 patients (11%).

Adult↗
PubMed1990

Embryonic and postnatal development of endolymphatic sac blood vessels.

The development of perisaccular blood vessels is described during embryology and the postnatal period of the mouse. Primitive sinusoidal vessels already appear at the early otocyst stage as the future endolymphatic sac is formed. Before birth the vasculature attains a more mature appearance with tubular, somewhat fully developed blood vessels. At this stage a primitive basement membrane is also formed. Soon after birth the blood vessels appear mature with developed fenestrations and micropores, giving them an appearance comparable to blood vessels in other fluid transporting organs.

Animals↗
PubMed1990

Microvascular network topology of the human retinal vessels.

A quantitative analysis of blood flow in the human retinal vessels requires a detailed picture of the microvascular network topology. In order to lay the foundation for a quantitative microcirculatory network analysis of the human retina, a novel technique for tissue preparation and network characterization was developed. After injection of hydrogen peroxide into the human bulb, the microvasculature was filled with oxygen produced by endothelial catalase and visualized after embedding in a mixture of cedar oil and gum damar. The vessel topology was documented in the form of photomicrographs, which permitted complete reconstruction of the microvasculature on transparent overlays. By considering the complete capillary system it was possible to divide the retinal network into dichotomous, asymmetric arteriolar and venular trees. The Strahler ordering method, which considers both dichotomous and side branching configurations, was selected and applied to analyze the retinal vascular trees, using the capillaries as the zero order reference vessels. The number of vessel segments was found to be an approximate logarithmic function of the order number, in accordance with Horton's law. Vessel lengths within each order were found to be log-normal distributed, and median lengths for different orders could be approximated by a 2nd degree polynomial curve. Diameters within each order could be approximated by a Gaussian distribution, and the mean values for different orders could be expressed by an exponential curve. These data provide the basis for conductance, pressure and flow computations within the retinal microvessels.

Arteriovenous Anastomosis↗
PubMed1986

Newly-formed subretinal vessels. Fine structure and fluorescein leakage.

The ultrastructure of experimentally induced newly formed subretinal vessels was correlated with the amount of fluorescein leakage demonstrated by the neovascular membranes during angiography. The membranes that demonstrated leakage contained subretinal vessels with a fenestrated endothelial wall and intermediate interendothelial cell junctions. As these subretinal plexi matured, they stopped demonstrating leakage. This involution process was accompanied by the formation of focal interendothelial tight junctions; however, loss of fenestrations was not observed. The membranes that never demonstrated fluorescein leakage also contained fenestrated subretinal vessels at both early and late stages of development; and their interendothelial junctions showed similar maturation from open to focal tight junctions. Thus all subretinal vessels had "leaky" morphology strongly resembling that of the normal choriocapillaris, whether they demonstrated fluorescein leakage or not. The authors conclude that newly formed subretinal vessels retain the characteristics of the choriocapillaris from which they are believed to proliferate; they have the potential to leak fluorescein at all stages of their development. The absence of fluorescein leakage during angiography cannot always be correlated with the absence of "leaky" morphology.

Animals↗
PubMed1989

Parapapillary retinal vessel diameter in normal and glaucoma eyes. II. Correlations.

The juxtapapillary diameters of the superior temporal and inferior temporal retinal artery and vein have been shown to be significantly smaller in glaucomatous eyes than in normal eyes. They had been measured in 473 eyes of 281 patients with chronic primary open-angle glaucoma and in 275 eyes of 173 normal subjects. In the current study the vessel diameters were correlated with intra- and parapapillary morphometric data and visual field indices. Only one eye per patient and subject was taken for statistical analysis. The retinal vessel calibers were significantly (P less than 0.001) correlated with: (1) the area of the neuroretinal rim as a whole and in four different optic disc sectors; (2) the rim width determined every 30 degrees; (3) the optic cup area and diameters; (4) the horizontal and vertical cup/disc ratios and (5) the quotient of them; (6) the retinal nerve fiber layer score; (7) the area of the parapapillary chorioretinal atrophy; and (8) the visual field indices. In the same eye the vessel caliber was smaller in that sector where the neuroretinal rim loss was highest and the retinal fiber layer score lowest. In intraindividual comparison the vessels were smaller in that eye with less neuroretinal rim tissue and lower nerve fiber layer score. No significant correlations were found with the form of the optic disc, the area of the peripapillary scleral ring, side, sex and refraction. The correlation coefficients were not significantly different when the control group was matched for age. The parapapillary retinal vessel diameter decreases with advancing glaucomatous optic nerve damage. It is correlated with morphometric intra- and parapapillary glaucomatous changes and perimetric defects.

Adult↗
PubMed1987

The blood vessel wall as an insulin target tissue.

Study of the effects of insulin and insulin-like growth factors on blood vessel walls has been expedited by the ability to isolate and grow components of large and small blood vessels in pure culture. This paper summarizes current knowledge about the effects of insulin and related molecules on blood vessel derived cells, with an emphasis on: (1) peptide receptors, their regulation, and transport and processing of molecules through the endothelium; (2) metabolic and (3) mitogenic effects of insulin and related peptides on the blood vessel wall, with a discussion of major differences between large and small vessel endothelia; and (4) interactions of insulin with barrier endothelia, for example cerebral microvascular endothelium, site of the blood-brain barrier.

Aminoisobutyric Acids↗
PubMed1986

[Development of the paravascular bed of the vessels of the human heart during the prenatal period of ontogenesis].

The paravascular bed of the cardiac vessels has been studied in 128 human fetuses at the age of 3-9 lunar months. Anatomical and histological techniques have been used, morphometrical analysis has been carried out. The paravascular bed of the cardiac wall vessels begins to form from the vascular epicardial network and from the paraneural vessels in 5-month-old fetuses. The paravasal longitudinal tracts are the first to form (the venous ones preceed the arterial). During the seventh month the nutritive vessels and the intramural networks of the main cardiac arteries and veins develop. The formation of the paraarterial bed is connected with the vascular diameter and with thickness of the arterial walls. Certain regularities in development of the venous paravascular bed are defined. By the beginning of the 8th month there are all main components of the paravascular bed of the cardiac vessels.

Coronary Vessels↗
PubMedDate not supplied

Results of treatment of 500 patients with civilian blood vessel trauma.

Results of treatment of 500 patients with blood vessel trauma are analyzed depending on trauma nature, shock severity, regional ischemia, technique of restorative surgery. Biochemical and ultrastructural changes in muscles are described in experimental conditions in ischemia of different degrees of severity to prognosis the reversibility of disorders. Restoration of blood circulation has been achieved in 82% of patients (5.1% mortality). Beside open and closed vessel trauma, it is expedient to distinguish between penetrating and non-penetrating injuries. Results of treatment of blood vessel trauma should be differentiated depending on the degree of regional ischemia, severity of traumatic shock and blood loss, combination of trauma and injury localization. Mechanical suture improves anastomosis quality, simplifies technique and reduces time of intervention. Introduction of microsurgery principles widens possibilities of vessel restorative surgery. The authors suggest classification of iatrogenic injuries of vessels, which promotes accurate diagnosis and choice of optimal surgical technique.

Adult↗
PubMed1985

Blood velocity and volumetric flow rate in human retinal vessels.

The distributions of blood velocity and volumetric flow rate in individual vessels of the normal human retina were determined as a function of vessel diameter. The mean velocity of blood, Vmean, was calculated from the centerline velocity measured by bidirectional laser Doppler velocimetry (LDV). Volumetric flow rate was determined from Vmean and the vessel diameter, D, measured from monochromatic fundus photographs. Diameter of the arteries and veins at the site of the LDV measurements ranged from 39 to 134 microns and 64 to 177 microns, respectively. Flow velocity correlated with D (P less than 0.001 for both arteries and veins). Volumetric flow rate varied with D at a power of 2.76 +/- 0.16 for arteries and 2.84 +/- 0.12 for veins, in close agreement with Murray's law. Calculated from 12 eyes, the average total arterial and venous volumetric flow rates were 33 +/- 9.6 and 34 +/- 6.3 microliters/min, respectively. The good agreement between both flow rates suggests that the technique and the assumptions for calculating flow yield results that satisfy mass conservation. Total arterial and venous volumetric flow rates correlated with total arterial and venous vessel cross-section. Volumetric flow rate in the temporal retina was significantly greater than in the nasal retina, but the difference is likely to be due to the larger area of the temporal retina. No difference in flow rate was observed between the superior and inferior retinal hemispheres. Finally, blood velocity in the major retinal vessels measured under normal experimental conditions appears remarkably constant over short (hours) and long (months) periods of time.

Blood Flow Velocity↗
PubMed1984

Functional significance of coronary collateral vessels during exercise evaluated by radionuclide angiocardiography: the importance of supplying arteries.

To investigate the function of coronary collateral vessels, especially from view point of supplying arteries, radionuclide angiocardiography was performed before and during a symptom-limited ergometer exercise in 54 patients with effort angina. In single vessel disease, during exercise, left ventricular ejection fraction (EF) (%) increased in the cases with coronary collateral vessels (supplied from patent arteries) (72 +/- 7----77 +/- 8, p less than 0.025), but decreased in those without (66 +/- 10----61 +/- 10, P less than 0.001). In multivessel disease, EF decreased during exercise even in those with collaterals (supplied from stenosed arteries) (67 +/- 10----59 +/- 8, p less than 0.001). It is concluded that angiographic appearance of the coronary arteries supplying collateral vessels is a major predictive factor of the function of coronary collateral vessels and of left ventricle during exercise.

Adult↗
PubMed1981

[Blood vessel supply of the flexor sinews (microanatomy) (author's transl)].

Knowledge of the blood vessel supply of the flexor sinews has been considerably enlarged by micro-angiograms. Arrangement of the vessels in the non-tendinous area of the hollow hand is different from that of the osteofibrous channels. The digitalis propriae form arcades, of which the vincula longa and brevia are responsible for segmental supply of the two flexor sinews at the triphalangeal fingers. Tendinous areas without vessels and poor blood supply are most probably supplied by means of diffusion. The intratendinous arrangement of the vessels has led to a change in suturing technique. The long flexor sinew of the thumb is supplied by blood vessels in the thenar region and at the base of the end phalanx.

Blood Vessels↗
PubMed1981

Fluorescein angiography of optociliary shunt vessels.

Progressive loss of vision, optic disc pallor, and optociliary shunt vessels (the Hoyt-Spencer sign) constitute the clinical triad of optic nerve sheath meningiomas. However, optociliary shunt vessels may also follow central vein occlusions, and less commonly occur with a few other conditions. This report presents a comparative study of fluorescein angiograms performed on eight patients with optociliary shunt vessels. Four patients had optic nerve sheath meningiomas, and four patients had central retinal vein occlusions. The following differences in the fluorescein angiograms were noted in the two groups. In the optic nerve sheath meningioma group, the shunt vessels fill earlier (in the arteriovenous phase), the flow drains to central venous tributaries, and the late staining is hyperfluorescent to other veins. However, in the central vein occlusion group, the shunts fill later (in the venous phase), show a flow draining to the outer disc margin, and late staining is eufluorescent with other veins. Although optic nerve sheath meningiomas and old vein occlusions are usually rather easily differentiated by a complete examination, the fluorescein angiographic patterns are not only pertinent with regards to the pathogenesis of optociliary vessels, but in certain cases may be clinically helpful in making an important clinical differentiation.

Adult↗
PubMed1984

Blood vessel uptake and metabolism of organic nitrates in the rat.

Recent reports have suggested that the unusual pharmacokinetics observed for nitroglycerin (NTG) and isosorbide dinitrate (ISDN) may be partially explained by extensive uptake and/or metabolism of these drugs by vascular and other extrahepatic tissues. Using the rat as an animal model, this hypothesis was examined by in vivo intravessel NTG and [14C]ISDN infusion and injection into various vessel segments, viz. the femoral vein, inferior vena cava [IVC: lower, middle and upper) and the aorta. NTG and [14C]ISDN concentrations were determined in these blood vessels and in plasma. Blood vessel segments nearest the input site had the greatest amounts of nitrate, whereas segments further away from the input site had progressively less nitrate, with the exception of aorta, which appeared to take up NTG less extensively, on a per weight of vessel basis, than the IVC. Blood vessel NTG concentrations (nanogram per gram) were generally higher (10-fold) and declined about twice as slowly as NTG plasma concentrations (nanograms per milliliter). [14C]NTG and [14C]ISDN were also incubated with cofactors in IVC, aorta, abdominal muscle, lung and liver. The amounts of nitrate metabolites formed from parent drug were larger in each extrahepatic tissue incubation than in the controls (P less than .05). The results are consistent with the hypothesis that vascular and other extrahepatic tissues can take up and/or metabolize organic nitrates. The data appear to provide a partial explanation for the large systemic clearance seen with nitrates and appear consistent with existing mechanistic hypotheses for the vascular action of these compounds.

Animals↗
PubMed1978

[Relationship between central and peripheral mechanisms in regulating capacitance vessels].

In acute experiments on cats, responses of the resistance and capacitance vessels of the spleen and hindlimbs to local electric stimulation of the medulla oblongata, of the sympathetic nerves, and pressor reflexes during different pressure of the venous outflow, were studied. No structures were revealed which could selectively affect the capacitance vessels. The bulbar structures affected both the resistance and the capacitance vessels. The reflex responses aof the pre- and post-capillary portions of the vascular bed could be different, the transmural pressure being one of the factors for dilatory responses of the capacitance vessels. The different responses of the capacitance vessels could occur on account of both local and central mechanisms, their participation, however, being unequal.

Animals↗
PubMed1982

[Thrombogenic properties of the vessel and their inhibition].

Vascular thrombosis is the response to injury of blood and the vessel wall. Normal endothelium is a non thrombogenic surface and is transformed into a thrombogenic surface by endothelial injury, the first step in thrombosis and in the development of atherosclerosis and its thrombotic complications. Many agents may injure the endothelial cells leading to at least three types of lesions: endothelial desquamation, local increase in endothelial turnover without de-endothelialization, endothelial dysfunction. The study of the factors controlling the functions of normal endothelial cells, their proliferation and their pathological modifications is possible with the use of human endothelial cell culture. Local generation of thrombin increases the thrombogenicity of the subendothelium and the accumulation of platelets, an effect inhibited by heparin. Thrombin binds specifically to the endothelium, but in a conformation preventing platelet interaction. PGI2 production by the vessel wall is not the main factor preventing adhesion of platelets to the endothelium or the subendothelium. PGI2 limits thrombus formation at the injury site. In the event of stasis, the inhibition of PGI2 formation by aspirin increases the size of the thrombus containing platelets and fibrin. The thrombogenic response of the vessel wall varies according to the nature of endothelial injury: a lesion causing removal of the endothelium and followed by adhesion of a single layer of platelets; chronic or repeated injury giving rise to a platelet-fibrin thrombus. Initiation and development of the thrombogenic properties of the vessel wall can be inhibited by dietary manipulations or pharmacologic interventions acting at the level of the endothelium, the interactions of platelets and the vessel wall or the coagulation system.

Aspirin↗
PubMed1983

Electron microscopic studies of pipestem sheathed vessel in human retina.

Histopathology of a clinically observed pipestem sheathed vessel in the retina was studied by electron microscopy. This vessel was characterized by a marked increase and disarrangement of collagen fibrils in the media and adventitia, and invasion of the cytoplasmic processes of Müller cells into the adventitia. The lumen of the vessel was extremely narrow but was preserved with healthy endothelial cells. It is suggested that increased and disarranged collagen fibrils in the vessel wall is related mainly to the ophthalmoscopic appearance of the pipestem sheathing. The infiltration of glial cells in the vessel wall may be of less significance to the pipestem sheathing.

Adult↗
PubMed1980

Control of blood vessel development.

Metabolic demands of the ocular tissues are determinants for the presence, morphology, and permeability of the ocular blood vessels. Changes in those metabolic requirements, such as those which occur during tissue maturation or a disease process, can lead to an alteration of the unique permeability and morphology of each nutrient vessel system. Those alterations during the course of a disease are the basis for the well-known visually destructive complications associated with vascular retinopathies. In order to prevent or circumvent those complications, we must come to understand both normal and abnormal tissue environmental factors which are determinants of vessel morphology and permeability. Investigations of those determinants in animals having fully, partially, or non-vascularized retinae and in animals with experimental retinopathies are necessary to the understanding of tissue/blood vessel inter-relationships. It is also necessary to evaluate those same relationships as fully as possible in human eyes with and without vascular abnormalities. Then we can begin to understand and to control blood vessel development.

Animals↗