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At least 433 records · Page 24Linked to original sources

PubMed2004

Effect of laser photocoagulation on the retinal vessel diameter in branch and macular vein occlusion.

OBJECTIVE: To investigate the response of retinal vessel diameters to photocoagulation treatment and their role for the success of laser treatment in patients with retinal vein occlusion. METHODS: The study included 14 patients with branch vein occlusion or macular vein occlusion. The ophthalmologic examination included best-corrected visual acuity, biomicroscopy, fundus photography, and fluorescein angiography. Retinal vessel diameters were quantified before and after laser photocoagulation using a retinal vessel analyzer. MAIN OUTCOME MEASURE: Retinal vessel diameters. RESULTS: In cases manifesting macular vein occlusions, no significant change of the vessel diameter in any vessel was observed during the follow-up period. In the group with branch vein occlusion, all vessels tended to constrict after the laser photocoagulation. The effect of laser treatment on retinal vessel diameters was significant for superotemporal (P =.045, analysis of variance [ANOVA]) and inferotemporal branch veins (P =.03, ANOVA). Vasoconstriction was more pronounced in the occluded branch veins (P =.009, ANOVA) compared with the nonaffected veins (P =.12; ANOVA). The change of visual acuity after 3 months was correlated with the change of vessel diameter 3 months after laser treatment for occluded venular branches (r = 0.78, P =.02, linear regression). There was no correlation between the number of laser burns and the change of vessel diameters in the affected veins in this period (r = 0.12, P =.75, linear regression). CONCLUSIONS: Our results show that retinal photocoagulation in patients with branch vein occlusion has a vasoconstrictive effect on occluded veins. The correlation between the change in visual acuity and the change in vessel diameter indicates that branch vein constriction after photocoagulation may be an early indicator of the success of laser treatment.

Aged↗

PubMed2006

Distribution of lymphatic vessels in mouse thymus: immunofluorescence analysis.

Thymic blood and lymphatic vessels in humans and laboratory animals have been investigated in morphological studies. However, occasionally a clear distinction between blood vessels and lymphatic vessels cannot be made from morphological characteristics of the vasculature. To visualize thymic lymphatics in normal adult BALB/c mice, we used antibodies against specific markers of lymphatic endothelial cells. Expression of vascular endothelial growth factor receptor-3 (VEGFR-3) was detected throughout the thymus, i.e., the capsule, cortex, and medulla. Most thymic lymphatics were present in capillaries of ~20 mum in caliber. The plexuses of lymphatic capillaries were occasionally detectable. Lymphatic vessels were frequently adjacent to CD31-positive blood vessels, and some lymphatic vessels were seen in the immediate vicinity of or within the perivascular spaces around postcapillary venules. The identity of VEGFR-3-positive vessels as lymphatics was further confirmed by staining with additional markers: LYVE-1, Prox-1, neuropilin-2, and secondary lymphoid tissue chemokine (SLC). The distributions of LYVE-1 were similar to those of VEGFR-3. Most lymphatic vessels were also identified by Prox-1. Neuropilin-2 was restricted to lymphatic vessels in the thymus. The most abundant expression of SLC in the thymus was in medullar epithelial cells; SLC was also expressed in lymphatic vessels and blood vessels. Thus, lymphatic endothelium in mouse thymus was characterized by positive staining with antibodies to VEGFR-3, LYVE-1, Prox-1, neuropilin-2, or SLC, but not with an antibody to CD31. Our results suggest the presence of lymphatic capillary networks throughout the thymus.

Animals↗

PubMed1995

A wall-less vessel phantom for Doppler ultrasound studies.

Doppler ultrasound flow measurement techniques are often validated using phantoms that simulate the vasculature, surrounding tissue and blood. Many researchers use rubber tubing to mimic blood vessels because of the realistic acoustic impedance, robust physical properties and wide range of available sizes. However, rubber tubing has a very high acoustic attenuation, which may introduce artefacts into the Doppler measurements. We describe the construction of a wall-less vessel phantom that eliminates the highly attenuating wall and reduces impedance mismatches between the vessel lumen and tissue mimic. An agar-based tissue mimic and a blood mimic are described and their acoustic attenuation coefficients and velocities are characterised. The high attenuation of the latex rubber tubing resulted in pronounced shadowing in B-mode images; however, an image of a wall-less vessel phantom did not show any shadowing. We show that the effects of the highly attenuating latex rubber vessels on Doppler amplitude spectra depend on the vessel diameter and ultrasound beam width. In this study, only small differences were observed in spectra obtained from 0.6 cm inside diameter thin-wall latex, thick-wall latex and wall-less vessel phantoms. However, a computer model predicted that the spectrum obtained from a 0.3-cm inside diameter latex-wall vessel would be significantly different than the spectrum obtained from a wall-less vessel phantom, thus resulting in an overestimation of the average fluid velocity. These results suggest that care must be taken to ensure that the Doppler measurements are not distorted by the highly attenuating wall material. In addition, the results show that a wall-less vessel phantom is preferable when measuring flow in small vessels.

Acoustics↗

PubMed2003

reg6 is required for branching morphogenesis during blood vessel regeneration in zebrafish caudal fins.

Postnatal neovascularization is essential for wound healing, cancer progression, and many other physiological functions. However, its genetic mechanism is largely unknown. In this report, we study neovascularization in regenerating adult zebrafish fins using transgenic fish that express EGFP in blood vessel endothelial cells. We first describe the morphogenesis of regenerating vessels in wild-type animals and then the phenotypic analysis of a genetic mutation that disrupts blood vessel regeneration. In wild-type zebrafish caudal fins, amputated blood vessels heal their ends by 24 h postamputation (hpa) and then reconnect arteries and veins via anastomosis, to resume blood flow at wound sites by 48 hpa. The truncated vessels regenerate by first growing excess vessels to form unstructured plexuses, resembling the primary capillary plexuses formed during embryonic vasculogenesis. Interestingly, this mode of vessel growth switches by 8 days postamputation (dpa) to growth without a plexus intermediate. During blood vessel regeneration, vessel remodeling begins during early plexus formation and continues until the original vasculature pattern is reestablished at approximately 35 dpa. Temperature-sensitive mutants for reg6 have profound defects in blood vessel regeneration. At the restrictive temperature, reg6 regenerating blood vessels first fail to make reconnections between severed arteries and veins, and then form enlarged vascular sinuses rather than branched vascular plexuses. Reciprocal temperature-shift experiments show that reg6 function is required throughout plexus formation, but not during later growth. Our results suggest that the reg6 mutation causes defects in branch formation and/or angiogenic sprouting.

Animals↗

PubMed2000

Openings between defective endothelial cells explain tumor vessel leakiness.

Leakiness of blood vessels in tumors may contribute to disease progression and is key to certain forms of cancer therapy, but the structural basis of the leakiness is unclear. We sought to determine whether endothelial gaps or transcellular holes, similar to those found in leaky vessels in inflammation, could explain the leakiness of tumor vessels. Blood vessels in MCa-IV mouse mammary carcinomas, which are known to be unusually leaky (functional pore size 1.2-2 microm), were compared to vessels in three less leaky tumors and normal mammary glands. Vessels were identified by their binding of intravascularly injected fluorescent cationic liposomes and Lycopersicon esculentum lectin and by CD31 (PECAM) immunoreactivity. The luminal surface of vessels in all four tumors had a defective endothelial monolayer as revealed by scanning electron microscopy. In MCa-IV tumors, 14% of the vessel surface was lined by poorly connected, overlapping cells. The most superficial lining cells, like endothelial cells, had CD31 immunoreactivity and fenestrae with diaphragms, but they had a branched phenotype with cytoplasmic projections as long as 50 microm. Some branched cells were separated by intercellular openings (mean diameter 1.7 microm; range, 0.3-4.7 microm). Transcellular holes (mean diameter 0.6 microm) were also present but were only 8% as numerous as intercellular openings. Some CD31-positive cells protruded into the vessel lumen; others sprouted into perivascular tumor tissue. Tumors in RIP-Tag2 mice had, in addition, tumor cell-lined lakes of extravasated erythrocytes. We conclude that some tumor vessels have a defective cellular lining composed of disorganized, loosely connected, branched, overlapping or sprouting endothelial cells. Openings between these cells contribute to tumor vessel leakiness and may permit access of macromolecular therapeutic agents to tumor cells.

Animals↗

PubMed2003

Gender differences in quality of distal vessels: effect on results of coronary artery bypass grafting.

OBJECTIVE: The quality of target vessels may affect gender differences in outcome after coronary artery bypass grafting. This prospective study compares preoperative angiographic assessment of vessel quality with intraoperative visual assessment of size and presence or absence of diffuse disease. The effect of vessel quality on operative mortality and late survival is examined. METHODS: Data were prospectively collected on 1939 consecutive patients undergoing isolated coronary artery bypass grafting by a single surgeon. Quality of target vessels was assessed preoperatively (angiogram) and intraoperatively by inspection and probe calibration. RESULTS: Vessels were poorly visualized in 29% of female patients and 37% of male patients (P =.004), although all but 1.6% of target vessels were grafted. Women were no more likely than men to have small vessels (<1.5 mm) (57% vs 59%, P =.449) and were less likely to have distal disease (45% vs 53%, P =.005). Operative mortality was low, not statistically different in women versus men (1.3% vs 0.7%, P =.237), and increased in patients with distal disease (1.3% vs.03%, P =.021). Late survival was decreased in patients with poor left ventricle function, congestive heart failure, and peripheral vascular disease. Late survival was decreased in men with increased age, class IV symptoms, small size, and no left internal thoracic artery graft, and in women with recent myocardial infarction and preoperative cerebrovascular accident. CONCLUSION: We conclude that in most patients with poorly visualized vessels in the preoperative angiogram, complete revascularization can be achieved if one is willing to graft small or diffusely diseased vessels. Women are no more likely than men to have vessels less than 1.5 mm in size and are less likely to have diffuse disease. Such an approach is associated with a low operative mortality and good long-term survival. Predictors of late survival were different for men and women. Neither small vessel size nor diffuse disease was an independent predictors of poor late outcome.

Age Factors↗

PubMed1985

Prognostic significance of peritumoral vessel invasion in clinical trials of adjuvant therapy for breast cancer with axillary lymph node metastasis.

To assess the prognostic significance of peritumoral vessel invasion, data were examined for 1,510 women entered into the Ludwig Breast Cancer Group Trials I to IV evaluating adjuvant therapy for operable breast cancer with axillary nodal metastasis. Vessel invasion by tumor cells was identified by routine light microscopy in 59 per cent (889 of 1,510) of the patients and was equally distributed between premenopausal/perimenopausal (60 per cent, 468 of 778) and postmenopausal (58 per cent, 421 of 732) women. In logrank analyses stratified by nodal status (one to three or four or more positive nodes), the four-year disease-free survival (DFS) rate was significantly lower in patients with vessel invasion than in women without vessel invasion (50 per cent versus 65 per cent, P less than 0.0001). This DFS difference was seen for both premenopausal/perimenopausal (P = 0.0004) and postmenopausal (P = 0.0002) patients. The four-year overall survival rate was also lower in patients with vessel invasion (71 per cent versus 82 per cent, P = 0.0006), both for premenopausal/perimenopausal (P = 0.002) and postmenopausal (P = 0.04) women. The presence of vessel invasion was significantly associated with increasing numbers of positive axillary lymph nodes, rising tumor grade, nonstellate tumor border growth pattern, and higher steroid hormone receptor content of the primary tumor. The assessment of peritumoral vessel invasion continued to have prognostic significance for DFS (P less than 0.0001) and overall survival (P = 0.003) when evaluated in multivariate models controlling for treatment assigned, nodal status, tumor size, estrogen receptor status, menopausal status, and age. Depending on the subpopulation, patients with vessel invasion had a 41 per cent to 54 per cent greater risk of treatment failure than those without vessel invasion and a 29 per cent to 64 per cent greater risk of death. The percentage of treatment failures at distant sites was higher for women with than for those without vessel invasion (27 per cent versus 18 per cent, P = 0.003). In patients with axillary lymph node metastases, peritumoral vessel invasion may be a sign of increased systemic disease burden.

Aged↗

PubMed2002

Characterization of changes in blood vessel width and tortuosity in retinopathy of prematurity using image analysis.

Many retinal diseases are characterised by changes to retinal vessels. For example, a common condition associated with retinopathy of prematurity (ROP) is so-called plus disease, characterised by increased vascular dilation and tortuosity. This paper presents a general technique for segmenting out vascular structures in retinal images, and characterising the segmented blood vessels. The segmentation technique consists of several steps. Morphological preprocessing is used to emphasise linear structures such as vessels. A second derivative operator is used to further emphasise thin vascular structures, and is followed by a final morphological filtering stage. Thresholding of this image is used to provide a segmented vascular mask. Skeletonisation of this mask allows identification of points in the image where vessels cross (bifurcations and crossing points) and allows the width and tortuosity of vessel segments to be calculated. The accuracy of the segmentation stage is quite dependent on the parameters used, particularly at the thresholding stage. However, reliable measurements of vessel width and tortuosity were shown using test images. Using these tools, a set of images drawn from 23 subjects being screened for the presence of threshold ROP disease is considered. Of these subjects, 11 subsequently required treatment for ROP, 9 had no evidence of ROP, and 3 had spontaneously regressed ROP. The average vessel width and tortuosity for the treated subjects was 96.8 microm and 1.125. The corresponding figures for the non-treated cohort were 86.4 microm and 1.097. These differences were statistically significant at the 99% and 95% significance level, respectively. Subjects who progressed to threshold disease during the course of screening showed an average increase in vessel width of 9.6 microm and in tortuosity of +0.008. Only the change in width was statistically significant. Applying a simple retrospective screening paradigm based solely on vessel width and tortuosity yields a screening test with a sensitivity and specificity of 82% and 75%. Factors confounding a more accurate test include poor image quality, inaccuracies in vessel segmentation, inaccuracies in measurement of vessel width and tortuosity, and limitations inherent in screening based solely on examination of the posterior pole.

Algorithms↗

PubMed1996

Direct vasomotor effects of isoflurane in subepicardial resistance vessels from collateral-dependent and normal coronary circulation of pigs.

BACKGROUND: The purpose of the current investigation was to determine and compare the direct effect of isoflurane on normal resistance coronary arteries and similarly sized coronary arteries in collateral-dependent (CD) circulation. A differential vasomotor effect of isoflurane might contribute to flow redistribution, either adverse or favorable, between normal and CD regions. METHODS: The authors used a swine model of chronic coronary occlusion. Six weeks after ameroid occluder placement around the left circumflex artery, the heart was removed. Myocardial blood flow, measured in vivo before the removal, was lower during rapid atrial pacing in the CD region than in the normally perfused region. These in vivo studies established the existence and location of CD circulation. Subepicardial microvessels, measuring approximately 100 microns, were dissected from both the CD region and the normal region. Either with or without preconstriction of the vessels with the thromboxane analogue U46619 1 microM, direct vasomotor effect of isoflurane was examined in vitro by video microscopy. In addition, vasomotor responses to endothelin-1, the endothelium-dependent dilator adenosine 5' diphosphate, and the endothelium-independent dilator sodium nitroprusside were compared between CD and normal resistance vessels. RESULTS: Isoflurane caused greater concentration-dependent constriction of the normal vessels than of the CD vessels (P < 0.05); this constrictive effect was masked by preconstriction of the vessels. Vasodilation of ADP was less in CD vessels than in normal vessels (P < 0.001), but vasodilation to sodium nitroprusside was not significantly different (P = 0.45). Vasoconstriction to endothelin-1 was greater in CD vessels than in normal vessels (P < 0.01). CONCLUSIONS: The vasoconstrictive effect of isoflurane normally observed in coronary resistance vessels is impaired in resistance vessels that supply a CD area. The basis of this may be related to endothelial dysfunction.

Anesthetics, Inhalation↗

PubMed1993

Theoretical analysis of the large blood vessel influence on the local tissue temperature decay after pulse heating.

The influence of a large blood vessel (larger than 500 microns in diameter) on the local tissue temperature decay following a point source heating pulse was determined numerically using a sink/source method. It was assumed that the vessel was large enough so that the temperature of blood flowing within it remained essentially constant and was unaffected by any local tissue temperature transients. After the insertion of a point source heating pulse, the vessel influence on the local tissue transient temperature field was estimated by representing the vessel as a set of negative fictitious instantaneous heat sources with strength just sufficient to maintain the vessel at a constant temperature. In the surrounding tissue, the Pennes' tissue heat transfer equation was used to describe the temperature field. Computations have been performed for a range of vessel sizes, probe-vessel spacings and local blood perfusion rates. It was found that the influence of a large vessel on the local tissue temperature decay is more sensitive to its size and location rather than to the local blood perfusion rate. For a heating pulse of 3s duration and 5mW of power, there is a critical probe-vessel center distance 7R (R, vessel radius) beyond which the larger vessel influence on tissue temperature at the probe can be neglected.

Blood Vessels↗

PubMed1972

Differences in direct effects of adrenergic stimuli on coronary, cutaneous, and muscular vessels.

Direct effects of adrenergic stimuli on coronary vessels in dogs were compared with effects on vessels to skin (hind paw) and skeletal muscle (gracilis muscle) after intravenous administration of practolol (2 mg/kg), a selective myocardial beta receptor blocker which minimized indirect effects of myocardial stimulation on coronary vascular resistance. The left circumflex coronary, cranial tibial, and gracilis arteries were perfused separately but simultaneously at constant flow. Perfusion pressures, left ventricular pressure and dP/dt. and heart rate were recorded. Changes in perfusion pressure to each bed reflected changes in vascular resistance. The direct constrictor effects of sympathetic nerve stimulation, norepinephrine and phenylephrine on coronary vessels were minimal compared with effects on cutaneous and muscular vessels. Subsequent blockade of vascular beta receptors did not augment the constrictor responses. Angiotensin, a nonadrenergic stimulus, produced striking coronary vasoconstriction which exceeded that in skin and approximated that in muscle. These results suggests that there is a paucity of alpha adrenergic receptors in coronary vessels compared to cutaneous and muscular vessels. Direct dilator responses to isoproterenol were similar in coronary and cutaneous vessels, but were greater in muscular vessels. Responses to glyceryl trinitrate, a nonadrenergic dilator, also were greater in skeletal muscle. Therefore, differences in effects of isoproterenol on the three beds may reflect differences in reactivity to dilator stimuli rather than differences in the density of beta receptors. In contrast to norepinephrine, the predominant direct effect of epinephrine on coronary vessels was dilatation mediated through activation of vascular beta receptors. A constrictor effect caused by stimulation of alpha receptors was unmasked by propranolol.Finally, the order of potency of agonists in stimulating coronary vascular beta receptors and the demonstration of selective beta receptor blockade with practolol suggest that beta receptors in coronary vessels resemble those in peripheral vessels more than those in myocardium.

Adrenergic beta-Antagonists↗

PubMedDate not supplied

Observer sensitivity to retinal vessel diameter and tortuosity in retinopathy of prematurity: a model system.

BACKGROUND: Abnormally increased diameter and tortuosity of retinal blood vessels in the posterior pole, or "plus disease," is recognized as a powerful predictor of poor outcome in eyes with retinopathy of prematurity (ROP). Although the diagnosis of plus disease depends upon the examiner's ability to examine retinal blood vessels, the ability of the human observer to identify changes in retinal blood vessel diameter and tortuosity accurately has not been studied. METHODS: Using computer-aided analysis of fundus photographs from eyes with a wide range of ROP severity, we generated tracings of posterior pole blood vessels which varied by quintiles of mean vessel diameter and tortuosity. Subjects (23 naive and 12 expert observers) ranked groups of tracings in order of increasing mean vessel diameter and tortuosity. These ranking tests were performed on tracings derived from the same fundus and tracings derived from distinct fundi. In a similar fashion, subjects also compared one designated standard fundus tracing with 25 distinct fundus tracings. RESULTS: Vessel diameter was assessed correctly more often than vessel tortuosity, both among similar (> 99% vs 92% of the time, respectively, P < 0.001), or among distinct (88% vs 78% of the time, respectively, P < 0.001) fundus images. The mean vessel diameter and tortuosity of 25 distinct fundus images were correctly ranked versus a standard image in 89% of attempts. Assessments of increments in vessel diameter and tortuosity were independent. Naive and expert subjects performed indistinguishably on all tests. CONCLUSIONS: Intelligent human observers have considerable ability to discern clinically relevant increments in blood vessel diameter and tortuosity. This ability may facilitate standardization in the diagnosis of plus disease in ROP.

Computer Simulation↗

PubMed2001

Expression of vascular endothelial growth factor receptor 3 in blood and lymphatic vessels of lung adenocarcinoma.

Vascular endothelial growth factor receptor 3 (VEGFR-3) has been proposed as a marker for lymphatic endothelial cells. This study investigated the expression of VEGFR-3 in the tumour vessels of lung adenocarcinoma and evaluated whether VEGFR-3 staining was useful for identifying lymphatic vessels within the tumour stroma. It also explored whether active growth of lymphatic vessels occurred in lung adenocarcinoma. Formalin-fixed, paraffin-embedded specimens obtained from 60 cases of lung adenocarcinoma, including five cases of pure bronchiolo-alveolar carcinoma (BAC) without stromal, vascular, and pleural invasion, were examined. No VEGFR-3-positive vessels were observed in pure BAC, but varying numbers of VEGFR-3-positive vessels were found in 39 of 55 (70.9%) invasive adenocarcinomas. A comparison of serial sections stained for VEGFR-3, CD31, and laminin-1 showed that most of the VEGFR-3-positive vessels appeared to be blood vessels (CD31-positive, laminin-1-positive), but some had the characteristics of lymphatic vessels (variable staining for CD31, little or no staining for laminin-1). VEGFR-3 staining highlighted lymphatic invasion by cancer cells; this invasion could not be detected by CD31 or haematoxylin and eosin (H&E) staining. Active growth of lymphatic vessels (as indicated by nuclear Ki-67 labelling of the endothelium) was observed in five tumours, four of which showed a high level of lymphatic invasion by cancer cells. It was concluded that VEGFR-3 immunostaining did not discriminate clearly between vascular and lymphatic endothelial cells, since expression of VEGFR-3 can be up-regulated in tumour blood vessels. However, VEGFR-3 staining combined with laminin-1 and CD31 staining would be useful for identifying lymphatic vessels and their invasion by tumour cells in a more objective way. Finally, proliferation of lymphatic endothelial cells may occur in association with lymphatic invasion by cancer cells.

Adenocarcinoma↗

PubMed2001

Desmoplakin as a specific marker of lymphatic vessels.

The usefulness of immunostaining with anti-desmoplakin antibody for light microscopic identification of lymphatic vessels was examined in cryostat sections of the human tongue. The results were compared with laminin, 5'-nucleotidase (5'-Nase), and factor VIII staining. Immunoelectron microscopic observation was also performed to confirm that the vessels reacting with anti-desmoplakin were lymphatic vessels. Under the immunoelectron microscopic, the vessels reacting with anti-desmoplakin showed ultrastructural features characteristic of lymphatic vessels: thin endothelial walls, no or incomplete basal lamina, open junctions, and overlapping endothelium. In general, lymphatic vessels identified by anti-desmoplakin reacted strongly with 5'-Nase, but showed weak or no reactivity with anti-laminin and anti-factor VIII. Blood vessels showed no reactivity with anti-desmoplakin, but reacted strongly with anti-laminin and anti-factor VIII. However, some blood and lymphatic vessels showed intermediate reactivity with anti-laminin, anti-factor VIII, and 5'-Nase. It was difficult to identify these as blood or lymphatic vessels only by the reactivity differences. The results indicate that anti-desmoplakin antibody specifically distinguishes lymphatic vessels and is useful for studying the fine distribution of lymphatic vessels under light microscopy.

Biomarkers↗

PubMed2002

Ultrastructure of absorbing peripheral lymphatic vessel (ALPA) in guinea pig Peyer's patches.

Corrosion casts from neoprene direct injection of lymphatic and blood vessels in guinea pig gut-associated lymphoid tissue, that is, solitary lymphoid follicles and Peyer's patches, have shown both their numerical density and their topographical arrangement in physiological conditions, after starvation and lymphatic stasis. The absorbing peripheral lymphatic vessel (ALPA) begins with the lacteal vessel, which continues in the mucosal lymphatic network. The latter is formed by subepithelial and interfollicular vessels wrapping single lymphoid follicles like a basket. Interfollicular vessels drain in the submucosal network, which flows into muscular tunica vessels with nonsegmentary bicuspid valves. They in turn drain lymph in subserosal precollectors and then in prelymphonodal collectors with conduction function. The follicles' germinal center and dome are completely devoid of ALPA vessels, while they are rich in blood vessels. Ultrastructurally, the ALPA vessel wall consists of a monolayer of endothelial cells devoid of pores, fenestrations, and open junctions and lacking a continuous basal lamina. Endothelial cells are joined by overlapping and interdigitating intercellular contacts, while end-to-end contacts are rare. They have a sizeable cell body, containing the nucleus and the common endocytoplasmic organelles, and a peripheral cytoplasm with actin-like filament bundles, free microvesicles or forming channels and a few rough-surfaced encloplasmic reticulum (RER) canaliculi. The presence of intraendothelial channels crossed by lymphocytes can often be detected within the endothelial wall during the different phases of cell transendothelial migration from lymphoid tissue to lymphatic vessel lumen. These channels undergo a numerical increase during starvation, while they are scarce during lymphatic stasis. We have quantitatively evaluated the prevalence of T lymphocytes in the lymph of interfollicular ALPA vessels and of prelymphonodal collectors draining the small intestine tract with or without Peyer's patches, under physiological and experimental conditions (starvation, lymphatic stasis).

Animals↗

PubMed1984

Mechanical behavior of pressurized in vitro prearteriolar vessels determined with a video system.

The muscular resistance arteries of the mesentery and brain serve two different control functions in the cardiovascular system. The former are representative vessels of vascular beds that influence total peripheral resistance and blood pressure; the latter are a good model of vessels in beds that demonstrate blood flow autoregulation. Our purpose was to develop a versatile myographic system appropriate for the in vitro study of 75-250 micron diameter vessels and to explore different physiological properties of cerebral and mesenteric arteries. In this paper the system is described in detail, examples of its use in determining the dynamic responses of the vessels to electrical stimulation are provided, and certain measures indicative of the extent of myogenic behavior are characterized. Cylindrical artery segments about 3-mm long were dissected from Wistar-Kyoto rats and mounted in a chamber filled with physiological saline solution maintained at 37 degrees C. The same solution was perfused via a syringe into one end of the vessel through a microcannula. The other end was then occluded so that experiments could be made over a wide range of transmural pressures without flow. The vessel was viewed through a microscope coupled with a TV camera, and the video output signal of a selected scan line was processed by an electronic dimension analyzing system. This permitted simultaneous digital presentation and analog voltage outputs of the vessel wall thicknesses and lumen diameter. We further incorporated servo control of the syringe using a motor drive. In this way, vessel tests could be carried out at constant pressure or constant diameter, and vessel responses could be obtained following either pressure or diameter command signals. Using the methods presented in this study, small vessels can be maintained under conditions that approximate their in vivo state more closely than other in vitro techniques using ring segments on wires. We also find that the opto-electronic instrumentation is ideally suited for studying the dynamic vessel properties that underlie the control of vascular smooth muscle.

Animals↗

PubMed2005

Experience of treating gunshot wounds of large vessels in Afghanistan.

The problem of treating injuries of large vessels in times of peace has been sufficiently well developed both in theoretical and practical aspects. In times of war, however, due to the large numbers of the wounded, a shortage of expert angiosurgeons, and multiple gunshot wounds, many theoretical tenets lose their academic regularity. The present study is based on the experience of treating 302 patients wounded during the Afghanistan war (1981-1985). Most of the injuries were to the vessels of the extremities. The gunshot wounds were complex. They included extensive destruction of tissue in the damaged segments of the extremities with simultaneous damage of large veins (42.0% of the cases), nerves (45.5%), and bones (47.4%). Multiple-vessel injuries were encountered in 4% of the cases, with combined injuries comprising 17.5%. Most of the wounded (83.7%) were in a state of shock, with 6.4% in a terminal condition. The blood loss amounted to 15% to 65% of the total volume. Ninety percent of the wounded were admitted to hospitals in the first 6 hours. A two-stage method was used to treat 71 of the wounded. The method included temporary bypass of the injured arteries and veins while evacuating the wounded and during surgery. Two hundred ninety-five wounded underwent vessel surgery. Out of the total number of injuries of arteries and veins, vessel sutures were used in 36.9% and 35.9% of the cases, vessel plastics in 41.4% and 7.1% of the cases, and vessel ligation in 21.7% and 60.0% of the cases, respectively. Surgery was completed by fixing the bone fragments externally with the help of special devices using the Ilizarov method. Amputation was performed in 13.9% of the cases. In 7.3% of the cases amputation was performed according to primary indications (no reconstructive surgery attempted on the vessels). In 6.6% of the cases extremities were amputated during the early postoperative period as a result of vessel thrombosis and an increase of tissue ischemia. The mortality rate after vessel surgery was 5.3%. We believe that for patients with gunshot wounds involving vessel injuries, early one-time reconstruction of the destroyed anatomical structures should be performed.

Afghanistan↗

PubMed2001

Correlation between the number of epineurial and endoneurial blood vessels in diseased human sural nerves.

In a preceding study it was shown that changes in the number of epineurial blood vessels may be a prominent feature in angiopathic and other peripheral neuropathies, for instance in vasculitis, diabetes mellitus, or cerebral autosomal dominant angiopathy with multiple infarcts and leukoencephalopathy (CADASIL). Endoneurial blood vessels usually may also show significant structural alterations in a broad spectrum of neuropathic conditions, although these are not as prominent as in the epineurium. However, the relationship between changes in the number of epineurial and endoneurial blood vessels in diseased human sural nerves, and the impact of the loss of myelinated nerve fibers on the number of endoneurial blood vessels has thus far not been determined. Therefore, we investigated and compared the number of epineurial and endoneurial blood vessels in 50 human sural nerve biopsy specimens, representing a variety of peripheral neuropathies. We found that despite a significant increase of the number of epineurial blood vessels in cases with vasculitic neuropathy (P<0.05) and neuropathy with other types of microangiopathy (P<0.01), the number and density of the endoneurial blood vessels remained remarkably constant. In cases with an axonal type of neuropathy, severe neuropathic changes were associated with a decreased epineurial blood vessel number and a simultaneous, relative increase in the endoneurial blood vessel density. No significant correlation was found between (1) the number of epineurial and endoneurial blood vessels, and (2) the severity of the neuropathy and the number or density of epineurial and endoneurial blood vessels.

Adolescent↗