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At least 415 records · Page 23Linked to original sources

PubMed2000

Ultrastructural and three dimensional aspects of the lymphatic vessels of the absorbing peripheral lymphatic apparatus in Peyer's patches of the rabbit.

We studied the absorbing lymphatic peripheral vessels of the Peyer's patches of the small and large intestine of the rabbit by means of light microscopy after injection of Neoprene latex and transmission electron microscopy in order to highlight their topographical distributions to blood vessels as well as the morphologic mechanism of transendothelial passage of the lymphocytes to the lymph. The distribution of absorbing lymphatic vessels originates from the lacteal vessels and the subepithelial mucosal lymphatic network, which continue without interruptions and dilations into the vessels of the interfollicular area which are woven into basket-like networks entwining the medio-basal portion of each lymphoid follicle. The interfollicular area vessels then drain into the large vessels of the tunica submucosa, which in turn drain into the valved precollector vessels of the subserosa by way of intramuscular vessels. TEM revealed the absorbing lymphatic vessels to have a continuous endothelial wall without open junctions, fenestrations, and continuous basal lamina. We observed many lymphocytes wedged in the lymphatic endothelial wall. This underlines the different phases of their migration from the lymphoid tissue in the lumen of the lymphatic vessel. Results of ultrathin serial sections and three dimensional reconstruction of lymphatic vessel segments with included lymphocyte showed the transendothelial passage of lymphocyte, through the "intraendothelial channels."

Animals↗

PubMed1979

Measurements of the perivascular PO2 in the vicinity of the pial vessels of the cat.

PO2's in the environment of the pial micro-vessels of the cat were measured using recessed tip oxygen microelectrodes. Measurements were made on the surface of vessels with internal diameters ranging from 200 micrometers to 22 micrometers. Blood oxygen partial pressures were also measured inside these vessels by penetrating the vessels with sharpened electrodes. Both intravascular and extravascular PO2 values decreased progressively from the large arterial vessels down to the small arterioles. The observed values of intravascular PO2 showed a systematic longitudinal decrease from 98.5 +/- 10.7 (SEM) mm Hg in the largest vessels down to 72.6 +/- 3.6 mm Hg in the smallest vessels. In addition to the longitudinal gradient, a transmural gradient was observed across the walls of the microvessels. The difference between blood PO2 and vessel surface PO2 was 27.0 +/- 2.5 mm Hg in the largest vessels and 6.0 +/- 2.2 in the smallest. The mean wall thickness in these groups of vessels were 27.0 +/- 1.5 and 7.5 +/- 0.8 micrometers respectively. Measurements of the minimum tissue PO2 on the exposed surface of the cortex yielded a value of 25.4 +/- 6.6 mm Hg. Systemic arterial partial pressure of oxygen averaged 94.7 +/- 4.7 mm Hg. The data indicate that significant gradients for oxygen exist both longitudinally and radially in association with the pial vessels. The longitudinal gradients represent losses of oxygen from the precapillary vessels. The transmural gradients are apparently the result of both consumption by the microvessel wall and diffusional gradients due to oxygen flux into the extravascular space.

Animals↗

PubMed1997

[Acute coronary vessel occlusion after PTCA--possibility of risk stratification using quantitative coronary angiography, clinical determinants and laboratory chemistry parameters].

Abrupt vessel closure of the dilated vessel continues to represent a significant limitation of coronary angioplasty. Despite increasing operator experience and improved technology, abrupt vessel closure continues to represent the most important complication of balloon angioplasty. Intracoronary stent implantation and pharmaceutical blockade of the GPIIb/IIIa receptor serve as effective tools in the prevention of abrupt vessel closure without completely resolving this problem. About 50% of patients presenting with abrupt vessel closure exhibit additional complications including myocardial infarction, necessity of CABG or death occurring in up to 10% of acute occlusions. The purpose of this study is to evaluate if quantitative coronary angiography and assessment of clinical and laboratory data allows risk stratification concerning the probability of abrupt vessel closure. PTCA in the setting of acute coronary syndrome is associated with a markedly increased risk of abrupt vessel closure, indicating that different risk factors may contribute to the development of abrupt vessel closure in patients presenting with stable angina or acute coronary insufficiency syndromes. 798 uncomplicated PTCA procedures for stable angina pectoris were compared with 68 interventions that were complicated by abrupt vessel closure. Furthermore, 133 successful angioplasty procedures for acute coronary syndromes defined as acute myocardial infarction or unstable angina pectoris were matched with 31 procedures for acute coronary syndromes with consecutive abrupt vessel closure. In patients presenting with stable angina pectoris stenosis length, stenosis eccentricity, minimal lumen diameter, degree of the stenosis after angioplasty, female gender, and fibrinogen could be defined as independent predictors of abrupt vessel closure. In acute coronary syndromes, only minimal lumen diameter, recanalization of completely occluded coronary arteries and fibrinogen were associated with an increased risk of abrupt vessel closure.

Aged↗

PubMed1990

Endomyocardial biopsy diagnosis of small vessel disease: a clinicopathologic study.

We reviewed the clinical history of 191 patients undergoing endomyocardial biopsy and correlated signs and symptoms of heart disease with the presence or absence of small vessel disease. Idiopathic congestive heart failure (78%), arrhythmia (35%), and chest pain (25%) were the most frequent indications for biopsy. Small vessel disease was noted in 61% of the biopsies (67% female, 56% male): 10% severe, 36% moderate, and 15% mild small vessel disease. Patients with hypertension were twice as likely to have small vessel disease than those without hypertension. Of the 27 females with hypertension, 85% had small vessel disease, 67% with either severe or moderate small vessel disease. Small vessel disease was almost twice as frequent in patients with chest pain compared to patients without chest pain. Chest pain was significantly more common in patients with severe small vessel disease than in those with normal small vessels. Of all patients with chest pain, 18% had severe small vessel disease; however, of 20 patients with severe small vessel disease, 45% had chest pain. This analysis suggests that small vessel disease seen in endomyocardial biopsy is more common in women and is related to hypertension. When severe, it is likely to be associated with atypical chest pain.

Adult↗

PubMed2002

A three-dimensional study of brain string vessels using celloidin sections stained with anti-collagen antibodies.

The purpose of this study was to explain the morphology and significance of string vessels in human brains. Brain slices (1.5 cm thick) were embedded in celloidin, sections cut at 100 microm and stained with antibody to collagen IV. A second component of the study was a 3-D rotational study for which we used sections stained with propidium iodide for cell nuclei and anti-collagen stain for blood vessel basement membranes. The materials consisted of brain from two infants at 28 and 35 weeks gestation, two term infants at 20 days and 3 months, one 5 years old, and 3 adults aged 25, 57, and 84 years. String vessels were counted in at least six fields of deep white matter using a 10x objective and the counts averaged and expressed as string vessels per cubic mm. The 3-D rotational study using confocal microscopy was designed to find nuclei in string vessels. The least number of string vessels were present in the premature infant. All others had comparably similar numbers of string vessels except the two term-born infants in whom there was a 3-5-fold increase. However, the two brains had other pathologic lesions, which could affect the counts. In normal brains, string vessels appear as a singe line of stain and usually connect two arterioles or capillaries. They can form loops and occasionally a string vessel may continue into a normal capillary. String vessels have rare nuclei. Our study indicates that string vessels are present in utero, increase in number and are present throughout life. Their exact nature remains unexplained. They apparently do not represent age-related acquired atrophy of capillaries because they are present at all ages and do not progressively increase with normal aging. This technique appears suitable for the study of large number of string vessels.

Adult↗

PubMed1998

Immunohistochemical demonstration of lymphatic vessels in human dental pulp.

The existence of lymphatic vessels in dental pulp has been a matter of continuing controversy because of the difficulty of discriminating them in ordinary stained tissue sections. Recently, we have succeeded in establishing a new identification method for lymphatic vessels in human frozen sections by using a commercial monoclonal antibody specific for the human thoracic duct and anti-human laminin antiserum. The present study aimed to examine the lymphatic vessels in human dental pulp using the new immunostaining method, and compared the results with those in human small intestine. The study clearly demonstrated the distribution of lymphatic vessels in human dental pulp. Large lymphatic vessels are located in the central part of the pulp and there are small lymphatic vessels in the periphery of the pulp. This suggests that lymphatic drainage of the human dental pulp starts from the periphery of the pulp and collects in the central part of the pulp. A notable difference between the small intestine and dental pulp was found in the immunoreactivity of lymphatic vessels to anti-human laminin anti-serum. In small intestine, immunoreactivity was significantly weaker than that of the blood vessels, whereas in dental pulp, that of lymphatic vessels was almost the same as blood vessels, except for some lymphatic vessels showing very weak reactivity. These findings suggest that the development of the basement membrane in both the lymphatic and blood vessels of human dental pulp is not as marked as in other tissue.

Adolescent↗

PubMed1999

Magnetic resonance imaging of the abdominal aorta and iliac vessels using combined 3-D gadolinium-enhanced MRA and gadolinium-enhanced fat-suppressed spoiled gradient echo sequences.

This study evaluates a combined protocol consisting of breath hold immediate post gadolinium 3-D gradient echo MR angiography and blood pool phase gadolinium-enhanced breath hold 2-D fat-suppressed spoiled gradient echo (SGE) sequences in the examination of diseases of the abdominal aorta and iliac vessels. Thirty-two patients with suspected disease of the abdominal aorta, major aortic branches, or iliac vessels underwent MR angiographic study from January 1996 to January 1997. Examinations were performed on a 1.5 T MR imager using 2-D axial SGE, coronal 3-D fast imaging in steady state precession (3-D FISP) following bolus administration of 40 mL of gadolinium, and axial and coronal blood pool phase gadolinium-enhanced fat-suppressed SGE. Post-processed data, including 3-D reconstructions using maximum intensity projection (MIP), targeted MIP, and multiplanar reconstruction (MPR) were evaluated. MR findings in all patients were correlated as follows: surgery (13 patients), angiography (11 patients), contrast enhanced CT (3 patients), non-contrast enhanced CT (1 patient), color doppler US (2 patients), and previous MR study (2 patients). MR findings correlated closely with findings at surgery or other imaging studies in 31 of 32 patients. One patient had renal artery occlusion that was misinterpreted as mild stenosis. The following vascular diseases were present: aneurysm disease [10 patients: aortic aneurysm (8 patients), inflammatory aneurysm (2 patients)], thoracoabdominal aortic dissection (2 patients), arteriovenous fistula (1 patient), stenoses and/or occlusion of the abdominal aorta, major aortic branches and iliac vessels [12 patients: stenoses and/or occlusion of the abdominal aorta with stenoses of the iliac vessels (9 patients), renal artery stenosis (2 patients), occlusion of the abdominal aorta (1 patient)], and occluded artery to pancreatic transplant artery (1 patient). Five patients had normal studies. The 3-D FISP technique accurately defined the luminal contours of vessels, allowing precise depiction of vessel stenosis (i.e., renal artery stenosis or common iliac artery stenosis) and clear demonstration of relationship of aortic branch vessels (i.e., renal arteries) to underlying aortic pathology (i.e., aortic aneurysm or dissection). Blood pool phase gadolinium-enhanced fat-suppressed SGE images were useful in the evaluation of the external surface of vessel walls, and providing accurate measurement of aneurysm diameter and other associated vascular entities (i.e., inflammatory aneurysm, left-sided IVC). Targeted MIP or MPR reconstruction were important for assessing stenoses of medium sized vessels such as renal arteries and branches of the iliac arteries, and for identifying accessory arteries. The combination of immediate post gadolinium 3-D FISP and blood pool phase gadolinium-enhanced fat-suppressed SGE is useful in the evaluation of the abdominal aorta, major aortic branches and iliac vessels. Immediate post gadolinium 3-D FISP images provides diagnostically useful information regarding vessel luminal contour, while blood pool phase gadolinium-enhanced fat-suppressed SGE provides ancillary information on the vessel wall and surrounding tissue.

Adolescent↗

PubMed2002

5-HT1B-receptors and vascular reactivity in human isolated blood vessels: assessment of the potential craniovascular selectivity of sumatriptan.

AIMS: 5-HT1B-receptor mediated vasoconstriction of cranial arteries is a potential mechanism by which 5-HT1B/1D-receptor agonists such as sumatriptan produce their antimigraine effects. 5-HT1B-receptors exist in other blood vessels which may give rise to unwanted vascular effects. Therefore we examined the distribution of 5-HT1B-receptor immunoreactivity (i.r.) in human blood vessels (including target and nontarget vessels) and confirmed the functionality of this receptor protein, by comparing the vasoconstrictor effects of sumatriptan and 5-HT (the endogenous ligand) in isolated vessels. METHODS: Blood vessels (middle meningeal, pial, temporal and uterine arteries and saphenous veins) were obtained from surgical patients (with consent). Sections of the vessels were prepared for routine immunohistochemical studies using specific 5-HT1B- and 5-HT1D-receptor antibodies. For functional studies, ring segments of the vessels were mounted in organ baths for isometric tension recording. RESULTS: 5-HT1B-receptor i.r. was detected on the smooth muscle layer in middle meningeal, pial and uterine arteries and in saphenous vein and sumatriptan produced contractions in these vessels with potency values (mean pEC50) of 7.00, 7.08, 6.44 and 6.61, respectively, the magnitude of contraction was greatest in the cranial arteries with Emax values of 100.7, 60.3, 23.0 and 35.9%, respectively (expressed as a percentage of the reference agonist 45 mm KCl). 5-HT1B-receptor i.r. was not detected in temporal artery and sumatriptan had no effect in this artery. 5-HT1D-receptor i.r. was not detected in any of the vessels studied. CONCLUSIONS: Sumatriptan can evoke vasoconstriction in antimigraine target vessels and also in nontarget vessels through an action at 5-HT1B-rcceptors. Sumatriptan acts preferentially to cause contraction in human cranial arteries compared with the other blood vessels we examined and this effect is likely to be shared by other drugs of this class.

Cerebral Veins↗

PubMed2003

Refilling of a hydraulically isolated embolized xylem vessel: model calculations.

When they are hydraulically isolated, embolized xylem vessels can be refilled, while adjacent vessels remain under tension. This implies that the pressure of water in the refilling vessel must be equal to the bubble gas pressure, which sets physical constraints for recovery. A model of water exudation into the cylindrical vessel and of bubble dissolution based on the assumption of hydraulic isolation is developed. Refilling is made possible by the turgor of the living cells adjacent to the refilling vessel, and by a reflection coefficient below 1 for the exchange of solutes across the interface between the vessel and the adjacent cells. No active transport of solutes is assumed. Living cells are also capable of importing water from the water-conducting vessels. The most limiting factors were found to be the osmotic potential of living cells and the ratio of the volume of the adjacent living cells to that of the embolized vessel. With values for these of 1.5 MPa and 1, respectively, refilling times were in the order of hours for a broad range of possible values of water conductivity coefficients and effective diffusion distances for dissolved air, when the xylem water tension was below 0.6 MPa and constant. Inclusion of the daily pattern for xylem tension improved the simulations. The simulated gas pressure within the refilling vessel was in accordance with recent experimental results. The study shows that the refilling process is physically possible under hydraulic isolation, while water in surrounding vessels is under negative pressure. However, the osmotic potentials in the refilling vessel tend to be large (in the order of 1 MPa). Only if the xylem water tension is, at most, twice atmospheric pressure, the reflection coefficient remains close to 1 (0.95) and the ratio of the volume of the adjacent living cells to that of the embolized vessel is about 2, does the osmotic potential stay below 0.4 MPa.

Air↗

PubMed2003

Tympanic membrane vessel revisited: a study in an animal model.

HYPOTHESIS: The present study aimed at elucidating whether there are blood vessels in the semitransparent portion of the tympanic membrane. BACKGROUND: The normal semitransparent portions of pars tensa show strikingly few, small-caliber vessels under the otomicroscope. The major portion of a pars tensa seems to be devoid of blood vessels. In inflammatory conditions of the middle ear, the vascular pattern of the tympanic membrane is dramatically altered, and blood vessels traversing the pars tensa can be discernable. METHODS: The study was performed in rats with healthy tympanic membranes and in tympanic membranes obtained from animals with purulent otitis media evoked by inoculation of Str. pneumoniae. The tympanic membrane vessels were dilated by injection of adenosin, and directly afterwards the animal was perfused with china ink. Vessels were also revealed by immunohistochemistry with antibodies for Thy-1 and the von Willebrand factor as well as by detection of carbon particles at an ultrastructural level. RESULTS: Adenosin caused a marked dilation of the mallear and annular vessels. However, no preexisting vasculature was revealed in the normally transparent portions of the pars tensa except single vessels in the posterior quadrant and in the lower quadrants. In Str. pneumoniae-induced acute otitis media, the tympanic membrane thickened, bulged, and discolored. Even then, at 12 hours after inoculation, no vessels could be distinguished in the normally transparent portions of the tympanic membrane. However, at 4 and 7 days of acute purulent otitis media, vessels developed in those areas, most probably through ingrowth of newly formed vessels. CONCLUSION: The results support the view that the semitransparent portions of the pars tensa lack vascularity. In inflammation, new vessels are formed in pars tensa to meet the demand for an increased blood supply.

Acute Disease↗

PubMed2005

The relationship of glands to thick-wall blood vessels as a marker of invasion in endocervical adenocarcinoma.

The recognition of early invasion in endocervical adenocarcinomas can be difficult. We evaluated the proximity of endocervical glands and their pattern of infiltration in relation to thick-wall blood vessels as potential markers of invasion in a series of invasive endocervical adenocarcinomas removed by cone biopsy or hysterectomy. Routinely stained slides were examined from 50 invasive endocervical adenocarcinomas (37 of usual type and 13 of minimal deviation type), 26 noninvasive lesions (14 cases of adenocarcinoma in situ, 7 cases of hyperplasia, 4 cases of tunnel clusters, 1 adenomyoma), and 20 normal cervices, including 7 with deep nabothian cysts. The range of vessel wall thickness using an ocular micrometer was recorded in each specimen. A blood vessel with a wall > or =36-microm thick was defined as thick-walled. Both the blood vessel wall thickness and distance to the closest gland was recorded for each case. The median distance from a thick-wall blood vessel to a gland in the invasive tumors was 30 microm compared with 168 microm in the noninvasive group. In both groups, the measured blood vessel wall had a median thickness of 42 microm. The pattern of infiltration of glands around the thick-wall vessels was classified as "circumferential," in which multiple glands circumferentially enveloped the vessel, or "molded," in which single or multiple distorted glands were molded around the vessel. The circumferential and molded patterns were identified in 35 (70%) and 10 (20%) of 50 invasive adenocarcinomas, respectively. Of the 26 lesions in the noninvasive group, only 3 (6%) had a circumferential pattern and none had a molded pattern. Importantly, none of the cases in the noninvasive group showed either pattern in the presence of glandular atypia. In conclusion, close proximity of glands to thick-wall blood vessels (distance from the closest gland to a thick-wall vessel less than or equal to the thickness of the vessel wall) seems to be a useful feature in the diagnosis of invasive endocervical adenocarcinoma. This feature, in combination with certain glandular growth patterns and cytologic atypia, can be highly suggestive, if not diagnostic, of invasive carcinoma.

Adenocarcinoma↗

PubMed2007

Effects of 532 nm pulsed-KTP laser parameters on vessel ablation in the avian chorioallantoic membrane: implications for vocal fold mucosa.

OBJECTIVES: Selective vascular ablation (photoangiolysis) using pulsed lasers that target hemoglobin is an effective treatment strategy for many vocal fold lesions. However, vessel rupture with extravasation of blood reduces selectivity for vessels, which is frequently observed with the 0.45-ms, 585-nm pulsed dye laser. Previous studies have shown that vessel rupture is the result of vaporization of blood, an event that varies with laser pulse width and pulse fluence (energy per unit area). Clinical observations using a 532-nm wavelength pulsed potassium-titanyl-phosphate (KTP) laser revealed less laser-induced hemorrhage than the pulsed dye laser. This study investigated settings for the pulsed KTP laser to achieve selective vessel destruction without rupture using the avian chorioallantoic membrane under conditions similar to flexible laryngoscopic delivery of the laser in clinical practice. STUDY DESIGN: The chick chorioallantoic membrane offers convenient access to many small blood vessels similar in size to those targeted in human vocal fold. Using a 532-nm pulsed KTP laser, pulse width, pulse energy, and working distance from the optical delivery fiber were varied to assess influence on the ability to achieve vessel coagulation without vessel wall rupture. METHODS: Third-order vessels (n = 135) were irradiated: Energy (471-550 mJ), pulse width (10, 15, 30 ms), and fiber-to-tissue distance (1 mm, 3 mm) were varied systematically. RESULTS: Selective vessel destruction without vessel wall rupture was more often achieved by increasing pulse width, increasing the fiber-to-tissue distance, and decreasing energy. Vessel destruction without rupture was consistently achieved using 15- or 30-ms pulses with a fiber-to-tissue distance of 3 mm (pulse fluence of 13-16 J/cm). CONCLUSIONS: This study substantiates our clinical observation that a 532-nm pulsed KTP laser was effective for ablating microcirculation while minimizing vessel wall rupture and hemorrhage.

Animals↗

PubMed1995

Recurrent stroke after transient ischaemic attack or minor ischaemic stroke: does the distinction between small and large vessel disease remain true to type? Dutch TIA Trial Study Group.

The incidence and vascular type of recurrent ischaemic stroke was studied in patients with supratentorial transient ischaemic attacks or non-disabling ischaemic strokes, who were treated with aspirin (30 or 283 mg). Patients were divided into groups with small vessel disease (SVD) (n = 1216) or large vessel disease (LVD) (n = 1221) on the grounds of their clinical features and CT at baseline. Patients with evidence of both SVD and LVD (n = 180) were excluded from further analyses. During follow up (mean 2.6 years) annual stroke rate was 3.6% in both groups. Of the 107 patients with SVD at baseline who had recurrent strokes, 83 proved to have an identifiable infarct: 30 (28%) again had a small vessel infarct, 39 (36%) had a large vessel ischaemic stroke and in 14 (13%) the recurrent ischaemic stroke was in the posterior fossa. Of the 110 patients with LVD at baseline and recurrent stroke, 91 had an identifiable infarct: 67 (61%) again had a large vessel ischaemic stroke, 16 (15%) had a small vessel ischaemic stroke, and eight (7%) had the recurrent ischaemic stroke in the posterior fossa. Thus patients with a transient ischaemic attack or non-disabling ischaemic stroke caused by LVD were more likely to have an ischaemic stroke of the same vessel type during follow up than patients with SVD (relative risk 2.2; 95% confidence interval 1.5-3.4). Possible explanations for this difference are: (1) patients with a small vessel ischaemic stroke at baseline had both SVD and LVD or were misdiagnosed; (2) recurrent small vessel ischaemic stroke may have occurred more often than reported, because they were silent or only minimally disabling; (3) recurring large vessel ischaemic strokes occurring in patients initially diagnosed as having SVD might have been related to potential cardiac sources of emboli that had not been previously recognized; (4) the antiplatelet drug aspirin (30 or 283 mg) prescribed in this patient group may have prevented thrombosis in small vessels better than in large vessels.

Aged↗

PubMed1987

Effects of atriopeptin III on isolated mesenteric resistance vessels from SHR and WKY.

The effects of atriopeptin III (AP III) were determined on agonist-induced [i.e., 10(-4) M norepinephrine (NE)] and depolarization-induced (80 mM K+) contractions of isolated mesenteric resistance vessels (ID approximately 100 microns) from spontaneously hypertensive rats (SHR) and from normotensive control Wistar-Kyoto (WKY) rats. The vessels from both groups, when activated by 80 mM K+, were unaffected by AP III. However, activation of WKY vessels by 10(-4) M NE (both phasic and tonic contraction) was inhibited quite effectively and potently by AP III, whereas that in SHR vessels was much less inhibited. In the WKY rat vessels, the concentration of AP III that inhibited contraction by 50% for NE-induced phasic tension was 3.1 +/- 1.3 nM, whereas in SHR vessels it was nearly 1 microM. Comparison of AP III inhibition of NE-induced phasic tension to that at 5 min of activation (tonic tension) indicated that the tonic contractions were less sensitive to AP III than the phasic contractions in the vessels from both strains. A similar experiment indicated that AP III was a potent inhibitor of agonist-induced activation in a human renal resistance vessel (ID 125 microns) and that this vessel depended virtually completely on extracellular Ca2+ for NE-induced contraction. These studies contrast with earlier reports (1, 30) that similar peptides inhibited tension only in rat renal resistance vessels and not in resistance vessels from other vascular beds. The decreased sensitivity and efficacy of AP III in inhibiting tension in SHR compared with WKY mesenteric resistance vessels is discussed in the context of the etiology of spontaneous hypertension.

Animals↗

PubMed1983

Morphometric study of structural changes in the mesenteric blood vessels of spontaneously hypertensive rats.

Structural changes of three categories of mesenteric arteries (representing elastic, muscular and arteriolar vessels) from 10- to 12-week-old and 28-week-old spontaneously hypertensive rats (SHR) were studied morphometrically at the light microscope level, and the results compared with age-matched Wistar-Kyoto normotensive rats. In 10- to 12-week-old SHR, hypertrophy of the vessel wall occurred only in the muscular and arteriolar vessels. At 28 weeks, further thickening of the vessel wall occurred in the muscular and arteriolar vessels, and the superior mesenteric artery (elastic vessel) was also thickened in the SHR. There was no evidence that the wall of the relaxed hypertrophied vessels encroached upon the lumen of the vessel. The structural basis for the increase in the vessel wall thickness varied with vessel type. In the superior mesenteric artery, increase in the media at 28 weeks of age would be consistent with hypertrophy of the smooth muscle cells. In the large muscular arteries, at 10-12 weeks of age, increase in medial mass occurred with increase in the number of the smooth muscle cell layers whereas at 28 weeks further increase in media could be due to hypertrophy of the smooth muscle cells. In the small arteriolar vessels, medial enlargement was due at all ages to an increase in the number of smooth muscle layers. Our results show that in the SHR hypertrophy of the media occurs not only in the small arteriolar vessels, but also in large elastic and muscular arteries.

Animals↗

PubMed1983

Dopamine in plasma of lateral and medial hypophysial portal vessels: evidence for regional variation in the release of hypothalamic dopamine into hypophysial portal blood.

The plasma concentrations of dopamine in blood from hypophysial portal vessels in various locations on the pituitary stalk were evaluated in diestrous rats. It was found that the mean concentration of dopamine in blood from lateral hypophysial portal vessels, which contain the venous effluent of the lateral median eminence, was significantly less (P less than 0.005) than that in blood from medial portal vessels, which contain the venous effluent of the medial median eminence [1.59 +/- (SE) 0.23 ng/ml vs. 3.12 +/- 0.48 ng/ml]. The mean plasma concentration of dopamine in blood of lateral portal vessels and of medial portal vessels was at least 20-40 times greater than that in arterial blood of these animals. It was calculated that the rate of release of hypothalamic dopamine was 174 +/- 38 pg/h into a medial portal vessel and 73 +/- 15 pg/h into a lateral portal vessel. The mean plasma concentration of norepinephrine or epinephrine in blood from a medial portal vessel was not different from that from a lateral portal vessel. To address the issue of whether the rate of release of dopamine into a medial portal vessel and into a lateral portal vessel was correlated with the rate of synthesis of dopamine in discrete regions of the median eminence, the concentration of L-dihydroxyphenylalanine (DOPA), the precursor of dopamine, was evaluated in lateral and medial segments of the median eminence of diestrous rats treated with 3-hydroxybenzylhydrazine, an inhibitor of DOPA decarboxylase activity. The concentration of DOPA was similar in the medial and lateral segments of the median eminence, suggesting that the rate of synthesis of dopamine did not account for the difference in the rate of release of dopamine into portal blood. The finding of different concentrations of dopamine in blood from various hypophysial portal vessels may be important in view of the heterogenous perfusion of the pars distalis with hypophysial portal blood. We suggest that topographic differences may exist in the release of PRL by cells of the pituitary gland as a consequence of uneven concentrations of dopamine in portal blood perfusing the lactotropes.

Animals↗

PubMed2000

[The superficial vein, cutaneous nerve and its nutrient vessels in the forearm: anatomic study and the clinical implication].

OBJECTIVE: To provide an anatomic basis for designing the flap pedicled with neurocutaneous nutrient vessels, and for further understanding of this flap and its relations with other local venous flaps. METHODS: Microanatomy and red-and-blue latex injection transparency method were applied to study 1. The medial antebrachial cutaneous nerve (MACN), the lateral antebrachial cutaneous nerve (LACN) and their nutrient vessels; 2. The relationship between the basilic vein and MACN and its nutrient vessels; and 3. The relationship between the cephalic vein and LACN and its nutrient vessels. RESULTS: MACN is vascularized by paraneural vessels and LACN is by both paraneural vessels and the long artery. MACN is accompanied by its paraneural vessels and the basilic vein, so do LACN by its nutrient vessels and the cephalic vein. The distance range from the cutaneous nerve to its accompanying superficial vein is less than 1 cm, to its paraneural vessels is less than 0.4 cm; and the distance range from the paraneural vessel to the superficial vein is about 0.3-1.2 cm. CONCLUSIONS: A flap pedicled with cutaneous nutrient vessels could be designed along a superficial vein. The type of flap might be different because of the different neurocutaneous blood supply. Some locally transferred venous flap might be a flap pedicled with neurocutaneous nutrient vessels.

Adult↗

PubMed2002

Significance of blood vessel leakiness in cancer.

Despite major advances in the field of tumor angiogenesis, relatively little attention has been paid to the permeability of blood vessels in tumors. The leakiness of tumor vessels is well documented in experimental tumor models and in human cancer, but the mechanism is poorly understood, as are the implications to the rate of cancer growth, predisposition to metastasis, and delivery of macromolecular therapeutics to tumor cells. Sixteen experts in the fields of cancer biology and vascular biology gathered at the William Guy Forbeck "Focus on the Future" Conference to discuss this topic. The meeting was the first of its kind focused on the significance of blood vessel leakiness in tumors. The participants discussed the cellular basis of tumor vessel leakiness, endothelial barrier function of blood vessels, monitoring tumor vessel leakiness, mediators of endothelial leakiness, consequences of tumor vessel leakiness, genomic analysis of vascular targets, targeting drugs to tumor vessels, and therapeutic manipulation of tumor vessels. The group concluded that a more complete understanding of the basic biology of tumor vessels will be necessary to fully appreciate the consequences of vessel leakiness in cancer. New research tools such as intravital measurements of tumor blood flow and vessel leakiness, in vivo phage display, magnetic resonance imaging, and use of selective angiogenesis inhibitors will contribute to this understanding.

Animals↗