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At least 613 records · Page 34Linked to original sources
PubMed1999

Automated localisation of the optic disc, fovea, and retinal blood vessels from digital colour fundus images.

AIM: To recognise automatically the main components of the fundus on digital colour images. METHODS: The main features of a fundus retinal image were defined as the optic disc, fovea, and blood vessels. Methods are described for their automatic recognition and location. 112 retinal images were preprocessed via adaptive, local, contrast enhancement. The optic discs were located by identifying the area with the highest variation in intensity of adjacent pixels. Blood vessels were identified by means of a multilayer perceptron neural net, for which the inputs were derived from a principal component analysis (PCA) of the image and edge detection of the first component of PCA. The foveas were identified using matching correlation together with characteristics typical of a fovea-for example, darkest area in the neighbourhood of the optic disc. The main components of the image were identified by an experienced ophthalmologist for comparison with computerised methods. RESULTS: The sensitivity and specificity of the recognition of each retinal main component was as follows: 99.1% and 99.1% for the optic disc; 83.3% and 91.0% for blood vessels; 80.4% and 99.1% for the fovea. CONCLUSIONS: In this study the optic disc, blood vessels, and fovea were accurately detected. The identification of the normal components of the retinal image will aid the future detection of diseases in these regions. In diabetic retinopathy, for example, an image could be analysed for retinopathy with reference to sight threatening complications such as disc neovascularisation, vascular changes, or foveal exudation.

Algorithms↗
PubMed2005

Viscoelastic testing methodologies for tissue engineered blood vessels.

In order to function in vivo, tissue engineered blood vessels (TEBVs) must encumber pulsatile blood flow and withstand hemodynamic pressures for long periods of time. To date TEBV mechanical assessment has typically relied on single time point burst and/or uniaxial tensile testing to gauge the strengths of the constructs. This study extends this analysis to include creep and stepwise stress relaxation viscoelastic testing methodologies. TEBV models exhibiting diverse mechanical behaviors as a result of different architectures ranging from reconstituted collagen gels to hybrid constructs reinforced with either untreated or glutaraldhyde-crosslinked collagen supports were evaluated after 8 and 23 days of in vitro culturing. Data were modeled using three and four-parameter linear viscoelastic mathematical representations and compared to porcine carotid arteries. While glutaraldhyde-treated hybrid TEBVs exhibited the largest overall strengths and toughness, uncrosslinked hybrid samples exhibited time-dependent behaviors most similar to native arteries. These findings emphasize the importance of viscoelastic characterization when evaluating the mechanical performance of TEBVs. Limits of testing methods and modeling systems are presented and discussed.

Animals↗
PubMed2006

Remote non-invasive stereoscopic imaging of blood vessels: first in-vivo results of a new multispectral contrast enhancement technology.

We describe a contactless optical technique selectively enhancing superficial blood vessels below variously pigmented intact human skin by combining images in different spectral bands. Two CMOS-cameras, with apochromatic lenses and dual-band LED-arrays, simultaneously streamed Left (L) and Right (R) image data to a dual-processor PC. Both cameras captured color images within the visible range (VIS, 400-780 nm) and grey-scale images within the near infrared range (NIR, 910-920 nm) by sequentially switching between LED-array emission bands. Image-size-settings of 1280 x 1024 for VIS & 640 x 512 for NIR produced 12 cycles/s (1 cycle = 1 VIS L&R-pair + 1 NIR L&R-pair). Decreasing image-size-settings (640 x 512 for VIS and 320 x 256 for NIR) increased camera-speed to 25 cycles/s. Contrasts from below the tissue surface were algorithmically distinguished from surface shadows, reflections, etc. Thus blood vessels were selectively enhanced and back-projected into the stereoscopic VIS-color-image using either a 3D-display or conventional shutter glasses. As a first usability reconnaissance we applied this custom-built mobile stereoscopic camera for several clinical settings:* blood withdrawal;* vein inspection in dark skin;* vein detection through iodide;* varicose vein and nevi pigmentosum inspection. Our technique improves blood vessel visualization compared to the naked eye, and supports depth perception.

Blood Vessels↗
PubMedDate not supplied

The noradrenergic innervation of spinal cord blood vessels in old rats.

The density and pattern of the sympathetic noradrenergic innervation of the extramedullary and intramedullary blood vessels of the spinal cord was studied in 3-, 12- and 25-month-old male Wistar rats using combined catecholamine histofluorescence and quantitative image analysis techniques. The study of innervation of intramedullary vessels was accomplished in spinal cord-transected rats to avoid the interference of descending spinal monoamine fibres in the observations. No age-related changes in the density of noradrenergic innervation of the anterior spinal artery or of sympathetic fibres associated with spinal cord blood vessels occurred. These results suggest that unlike perivascular noradrenergic nerves supplying the cerebrovascular tree, the sympathetic innervation of spinal cord blood vessels does not undergo age-dependent changes. It cannot be excluded that the lesser vulnerability of the spinal compared to the cerebral vascular tree to certain kinds of age-related diseases, may depend on the unchanged sympathetic trophic regulation of spinal vessels with age.

Adrenergic Fibers↗
PubMed1987

[Possible participation of vessel wall kinins in regulating blood vessel tonus].

Extracts of mammalian arterial walls revealed a kinin-like biological activity resistant against proteolytic inactivation with trypsin but not chymotrypsin. Bradykinin was chromatographically determined as kinin existing in extracts from the rat aorta. Kallidin was found as well as bradykinin in human vessels. Metabolism of vasoactive kinins in the vascular wall seems to take part in control of circulation and blood pressure.

Animals↗
PubMed2004

[Clinical application of fistulation of artery and vein with self-blood vessel transplantation].

OBJECTIVE: To investigate the clinical application of fistulation of artery and vein with self-blood vessel transplantation. METHODS: Seven patients with renal failure were given antebrachial fistulation of artery and vein with great saphenous veins of themselves. The ortho- and pachy-great saphenous vein was chosed after it was cut. The great saphenous vein was passed bridge inside forearm in straight line or morpha-U. The method was anastomosis of the radial artery or brachial artery and cephalic vein, basilic vein or median cubital vein. RESULTS: The fistulations of artery and vein were successful and all patients were in hemodialysis regularly. CONCLUSION: The fistulation of artery and vein with self-blood vessel transplantation is a convenient, easy, cheap operation. It can coincide with the clinical demand and be used to make up the failure of fistulation or the fistulation that there is no blood vessel in the forearm.

Aged↗
PubMed1991

[A case of neoplastic angioendotheliosis--possible mechanism of JC virus infection for the selective growth of tumor cells in the blood vessel].

A case of 55-year-old man pathologically proven as neoplastic angioendotheliosis was reported. He initially developed sensory disturbance and motor weakness in the lower extremities. After admission, he showed progressive deterioration of higher brain functions with moderate fever. Routine laboratory examinations revealed elevated serum LDH level and erythrocyte sedimentation rate without leukocytosis or increased serum globulin level. Immunological tests were normal, except positive RA. Immunocytochemical investigation of tumor cells in the blood vessel gave the results that these cells appeared to be derived from B cells. Southern blot analyses of the brain samples revealed clear positive bands corresponding to JC virus DNA in the blot. JC virus has been known to infect the endothelial cells of the blood vessel as well as urethral epithelial cells. We discussed the possible mechanism of the selective growth of tumor cells in the blood vessel in terms of possible JC virus infection to the endothelial cells of the blood vessel and abnormal recognition between tumor cells and endothelial cells.

B-Lymphocytes↗
PubMed1988

Peptide-containing nerves around blood vessels of stroke-prone spontaneously hypertensive rats.

The distribution and density of nerves containing vasoactive intestinal polypeptide, substance P, and neuropeptide Y around the cerebral and peripheral blood vessels of stroke-prone spontaneously hypertensive rats (SHRSP) and normotensive Wistar-Kyoto rats (WKY) were studied using an indirect immunofluorescence technique. Neonatal sympathectomy of SHRSP with anti-nerve growth factor and guanethidine was also carried out to study the effect of sympathectomy on the distribution of these nerves. Vasoactive intestinal polypeptide nerve density was higher in the veins and superior mesenteric artery of SHRSP than of WKY and lower in the cerebral arteries of SHRSP than of WKY, but no difference was found in the muscular mesenteric arteries. Sympathectomy reduced the density of these nerves in all the peripheral vessels but had little effect on the cerebral arteries. Density of substance P nerves was similar between SHRSP and WKY in the peripheral vessels but higher in the cerebral arteries of WKY than of SHRSP. Sympathectomy reduced the density of these nerves in the peripheral vessels but increased the density in some cerebral arteries of SHRSP. Neuropeptide Y nerve density was higher in the peripheral blood vessels of SHRSP than of WKY, and no difference was found in the cerebral arteries. Sympathectomy almost completely removed these nerves in the peripheral vessels but had no effect on the cerebral arteries. We suggest that some of the differences in nerve density between SHRSP and WKY, especially those in the peripheral blood vessels, may be related to the development of hypertension in the SHRSP.

Animals↗
PubMed1976

Effect of nitroprusside on smooth muscle and adrenergic nerve terminals in isolated blood vessels.

Experiments were designed to assess the mode of action of nitroprusside on isolated blood vessels and its relative potency on venous and arterial smooth muscle. Strips from dog blood vessels were mounted in an organ bath for isometric tension recording. Sodium nitroprusside (10(-5) M) depressed the contraction of saphenous vein strips caused by electric stimulation, tyramine, K+, Ba++, norepinephrine and acetylcholine. The depression of the norepinephrine-induced contractions also occurred in a Ca++- free medium and when Ca++ influx was inhibited by verapamil. Nitroprusside reduced the frequency of the spontaneous contractions of strips of portal-mesenteric veins. It depressed the contraction caused by norepinephrine in tibial artery strips more than in saphenous vein strips. Saphenous vein strips were incubated with (3H)norepinephrine and mounted for superfusion and isometric tension recording. Sodium nitroprusside (10(-5) M) had no effect on the basal efflux of 3H compounds. During electric stimulation, it did not change the output of (3H)norepinephrine but increased the outflow of deaminated and O-methylated metabolites. Thus sodium nitroprusside 1) has a direct effect on the smooth muscle cells which is independent of Ca++ influx, 2) depresses contractions of different types of vascular smooth muscle and 3) does not inhibit the release of norepinephrine from the nerve endings.

Animals↗
PubMedDate not supplied

[Effect of high-amplitude electrical impulses on the strength of the coagulative adhesion of the blood vessels].

Strength of coagulative commisure of the blood vessel tissues in their coagulation with high-frequency current can be increased after additional action of high-amplitude electrical pulses. A comparative test of commisures tensile strength confirmed its possible increase by 1.6--1.7 times when vascular tissues were preliminarily subjected to the action of short high-amplitude electrical pulses.

Animals↗
PubMed1976

Tunica propria in chronic allergic rhinitis. Electron-microscopic study. I. The nasal blood vessels.

The fine structure of human nasal blood vessels was studied in 15 chronic allergic patients. The venules showed gaping of the interendothelial junctions and lamination of the basal lamina. The capillaries displayed numerous endothelial cytoplasmic processes. The arteriolar walls showed thinning and destructive changes. A reciprocal relation between the vascular endothelium and its basal lamina was deduced.

Adolescent↗
PubMed1985

Optical properties of human blood vessel wall and plaque.

Optical properties of blood vessel wall and plaque from human cadaver material are presented for the argon laser (514.5 nm), He-Ne laser (633 nm), and the Nd-YAG laser (1,060 nm) wavelengths. Measurements were performed with an integrating sphere arrangement and analyzed in terms of Kubelka-Munk absorption and scattering coefficients.

Arteriosclerosis↗
PubMed1983

Adenosine causes dilatation and constriction of hypothalamic blood vessels.

The effect of adenosine on intraparenchymal cerebral blood flow was examined in conscious rabbits with the 133Xe clearance technique. Perivascular application of 10(-3) and 10(-4) M adenosine to hypothalamic blood vessels increased hypothalamic blood flow by approximately 50% (p less than 0.005). This vasodilatation was attenuated by the intrahypothalamic injection of the beta-adrenergic receptor antagonist propranolol, but was unaffected by alpha-adrenoreceptor blockade with phenoxybenzamine, or depression of neuronal activity with barbiturate. 2-Chloroadenosine, a stable analogue of adenosine, also increased hypothalamic blood flow by 50% (p less than 0.005), but this dilatation was unaffected by propranolol. These results suggest that adenosine increased hypothalamic blood flow at high concentrations by vascular receptor systems dependent on adenosine receptors and adrenergic receptors. Adenosine (10(-6) M) reduced hypothalamic blood flow by approximately 25% (p less than 0.005). This vasoconstriction was unaffected by adrenergic blockade with propranolol or phenoxybenzamine, or by inhibition of neuronal activity with barbiturate. The results suggest that adenosine decreases hypothalamic blood flow at low concentrations by stimulation of adenosine receptors associated with vascular smooth muscle.

Adenosine↗
PubMed2003

Nitric oxide synthase activity in blood vessels of spontaneously hypertensive rats: antioxidant protection by gamma-tocotrienol.

Involvement of free radicals and nitric oxide (NO) has long been implicated to the pathogenesis of essential hypertension. Several studies using antioxidants as the radical scavenger have shown to confer protection against free radical mediated diseases. This study is designed to investigate the role of antioxidant gamma-tocotrienol on endothelial nitric oxide synthase (NOS) activity in spontaneously hypertensive rats (SHR). SHR's were divided into four groups namely untreated SHR (HC), treatment with 15 mg gamma-tocotrienol/kg diet (gammal), 30 mg gamma-tocotrienol/kg diet (gamma2) and 150 mg gamma-tocotrienol/kg diet (gamma3) and studied for three months. Wister Kyoto (WKY) rats were used as the control (C). Blood pressure was recorded every fortnightly by tail plethysmography. Animals were sacrificed and NOS activity in blood vessels was measured by [3H]arginine radioactive assay. Nitrite concentration in plasma was determined by Greis assay and lipid peroxides in the blood vessels by spectrofluorometry. This study showed that gamma-tocotrienol significantly reduced systolic blood pressure (SBP) in SHRs with a maximum reduction in group treated with gamma-tocotrienol 15 mg/kg diet (HC: 210 +/- 9 mmHg, gammal:123 +/- 19 mmHg). Blood vessels from untreated SHR showed a reduced NOS activity compare to that of WKY rats (C: 1.54 +/- 0.26 pmol/mg protein, HC: 0.87 +/- 0.23 pmol/mg protein; p<0.001). Gamma-tocotrienol improves NOS activity in all the groups with more significance in group gamma2 (p<0.001) and gamma3 (p<0.05). Plasma level of nitrite was reduced in SHR from 55 +/- 3 microM/ml in WKY to 26+/-2 muM/ml (p<0.001). Plasma nitrite level was reversed by treatment with gamma-tocotrienol. (gammal: p<0.001, gamma2: p<0.005, gamma3: p<0.001, respectively). In all the treatment groups, NOS activity showed significant negative correlation with blood pressure (gammal: r=-0.716, p<0.05; gamma2: r=-0.709, p<0.05; gamma3: r=-0.789, p<0.05). For plasma nitrite, although it shows a negative correlation with blood pressure it was significant only in gammal (r=-0.676, p<0.05) and gamma2 (r=-0.721, p<0.05). From this study we found that compared to WKY rats, SHR has lower NOS activity in blood vessels, which upon treatment with antioxidant gamma-tocotrienol increased the NO activity and concomitantly reduced the blood pressure. These findings further strengthen the hypothesis that free radicals and NO play critical role in pathogenesis of essential hypertension.

Administration, Oral↗
PubMedDate not supplied

[Mathematical models of nitric oxide transport in a blood vessel].

The appearance of this review concerning the nitric oxide transport in a blood vessel wall is connected with the authors' interest in vessel tone regulation. The introductory part contains basic equations for resistive vessels, an outline of processes occurring in smooth muscle and endothelial cells, and the simulation of these processes. As a rule, the description of nitric oxide diffusion and reactions in blood vessels is given in the order of increasing complication of the models. Primary attention is given to the consideration of systems with endothelial production of nitric oxide, but articles considering other sources of nitric oxide are also reviewed. The theoretical methods of evaluating the parameters that are important for modeling but hardly measurable are described.

Animals↗
PubMed1981

Assembly and processing of procollagen V (AB) in chick blood vessels and other tissues.

The biosynthesis and processing of type V procollagens was investigated in chick embryo blood vessels labeled with radioactive amino acids. Monomeric, pepsin-sensitive pro alpha 1 V and pro alpha 2 V chains are slowly assembled into triple helically folded molecules. A small proportion of these procollagen V molecules contain interchain disulfide bridges, and the disulfide-linked heterodimer and heterotrimer (pro alpha 1 V)2pro alpha 2 V were found. A relatively fast conversion of procollagen V to p-collagen V is followed by slow change to collagen V. This time course is similar to the processing of procollagen III and is much slower than the rate of appearance of type I collagen in blood vessels. A combination of sedimentation and electrophoretic analyses was used to measure the relative size of the type V chains and to demonstrate attachment of noncollagenous peptides (Mr = 33,000) to p alpha 2 V by disulfide linkage. Similar quantitative pulse-chase studies were made with calvaria and crop. As the same unusual features of assembly and processing of type V chains were seen in muscle, bone, and blood vessels, we conclude that these are characteristic of type V collagen biosynthesis.

Animals↗
PubMed2005

Nitric oxide control of lower vertebrate blood vessels by vasomotor nerves.

In mammals, much is understood about the endothelial and neural NO control mechanisms in the vasculature. In contrast, NO control of blood vessels in lower vertebrates is poorly understood, with the majority of research focusing on the presence of an endothelial NO system; however, its presence remains controversial. This study examined the mechanisms by which NO regulates the large blood vessels of non-mammalian vertebrates. In all species examined, the arteries and veins contained a plexus of NOS-positive perivascular nerves that included nerve bundles and fine, varicose nerve terminals. However, in the large arteries and veins of various species of fishes and amphibians, no anatomical evidence was found for endothelial NOS using both NADPH-diaphorase and eNOS immunohistochemistry. In contrast, perinuclear NOS staining was readily apparent in blue-tongue lizard, pigeon and rat, which suggested that eNOS first appeared in reptiles. Physiological analysis of NO signalling in the vascular smooth muscle of short-finned eel and cane toad could not find any evidence for endothelial NO signalling. In contrast, it appears that activation of the nitrergic vasomotor nerves is responsible for NO control of the blood vessels.

Animals↗
PubMed1986

[Effect of blood movement on the reactivity of blood vessels].

The influence of electrokinetic phenomena arising from blood movement on reactivity of blood vessels has been studied. The potential difference, as it has been established, occurs during blood movement along a vessel between its internal and external surfaces, being dependent upon the rate of blood movement, and the internal one becomes negatively charged. Blood movement facilitates penetration of molecules of dye with a positive charge into a vessel wall. The contractile response of a vessel to the stimulation of vasomotor nerves gradually increases with a start of blood movement and decreases after a blood stop. Artificially applied potential difference between the internal and external vessel surfaces results in the changes of contractile response and vessel tone. The role of electrokinetic phenomena in regulation of contractile ability and vessel tone is discussed.

Animals↗