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PubMed1983

Correlations and otherwise between blood pressure, cardiac mass and resistance vessel characteristics in hypertensive, normotensive and hypertensive/normotensive hybrid rats.

We have measured heart weight and properties of 150-200 microns mesenteric resistance vessels from spontaneously hypertensive (SHR), Wistar-Kyoto (WKY), two-kidney, one clip Goldblatt renal hypertensive (RHR) and outbred Wistar rats, as well as in SHR/WKY F2-hybrid rats. All rats were 14-weeks-old. In the SHRs, WKYs, RHRs and Wistars the mean blood pressures (measured intra-arterially) were, respectively: 136, 111, 164 and 100 mmHg. In the SHR/WKYs the systolic blood pressures (measured regularly over a two-week period by the tail cuff method) were normally distributed between the values obtained from control SHRs and WKYs. Relative heart weight and resistance vessel media thickness/lumen diameter ratio correlated (P less than 0.001) with blood pressure between SHRs, WKYs, RHRs and Wistars; however, no significant correlation was seen in SHR/WKYs. By contrast, the calcium sensitivity of the resistance vessel noradrenaline response did correlate (P less than 0.01) with blood pressure in the SHR/WKYs, but did not correlate between the pure strains (calcium sensitivity of the SHR and Wistar vessels was similar, but higher than that of the WKY vessels; induction of renal hypertension did not affect calcium sensitivity). The results suggest that although the cardiac enlargement and increased resistance vessel media/lumen ratio of 14-week SHRs may be advantageous for these animals, these structural abnormalities may not be primary causes of the hypertension. Furthermore, the results indicate that it is the WKYs which are abnormal in having a low calcium sensitivity of their resistance vessels, but suggest also that this reduced sensitivity may be associated with mechanisms which help to keep the WKYs normotensive.

Animals↗
PubMedDate not supplied

Effect of felodipine, a new dihydropyridine vasodilator, on contractile responses to potassium, noradrenaline, and calcium in mesenteric resistance vessels of the rat.

The effect of felodipine [4-(2,3-dichloro-phenyl)-1,4-dihydro-2,6-dimethyl-3-ethoxycarbonyl-5- methoxycarbonylpyridine on the contractile responses of mesenteric resistance vessels denervated in vitro was investigated. Sustained contractions of this vessel type were totally dependent on extracellular calcium. Felodipine (10-(15)-10-(9)M) had a concentration-dependent inhibitory action on contraction induced by maximal potassium (125 mM) and noradrenaline (10-(5)M) stimulation. Felodipine was more potent and more selective than D600 and nifedipine. Potassium and noradrenaline concentration-response characteristics were insurmountably antagonized by felodipine, the potassium sensitivity of vessels being unaffected while noradrenaline sensitivity was decreased. In calcium-depleted vessels, felodipine in all concentrations tested produced insurmountable antagonism of the potassium-activated calcium concentration-response characteristics, whereas the antagonism in low concentrations (10-(15)-10-(11)M) was surmountable in noradrenaline-activated vessels. Felodipine 10-(9) M blocked the response of potassium-activated vessels almost completely, whereas approximately 50% of the response of noradrenaline-activated vessels persisted. The results of this investigation indicate that the effect of felodipine may be caused primarily by selective inhibiton of responses evoked by membrane depolarization.

Animals↗
PubMed1998

The absence of crossing vessels in association with ureteropelvic junction obstruction detected by prenatal ultrasonography.

PURPOSE: The widespread use of prenatal ultrasonography has led to a marked increase in the incidence of ureteropelvic junction obstruction presenting in infancy. Which of these prenatally detected lesions requires repair has yet to be fully determined. Attempts to characterize prenatally detected ureteropelvic junction obstruction in regard to symptomatic obstruction detected later in life may provide useful insights into the management of these incidentally discovered lesions. We evaluated the presence of crossing vessels in ureteropelvic junction obstruction identified by prenatal ultrasonography. MATERIALS AND METHODS: We reviewed the records of patients who underwent dismembered pyeloplasty for primary ureteropelvic junction obstruction with specific attention to the mode of presentation and presence of crossing vessels associated with obstruction. RESULTS: In 30 patients with a mean age of 6 months ureteropelvic junction obstruction detected prenatally was not associated with a crossing vessel. Ureteropelvic junction obstruction was identified postnatally in 125 patients who underwent open pyeloplasty. It was detected incidentally in 8, of whom crossing vessels were present in 1 (12%). There were signs or symptoms related to ureteropelvic junction obstruction in 117 patients. In contrast to the group with prenatally detected ureteropelvic junction obstruction in which crossing vessels were never noted, crossing vessels were associated with 36 (30%) of the 120 kidneys operated on in this postnatally discovered group. CONCLUSIONS: No crossing vessels were present in patients with prenatally detected ureteropelvic junction obstruction compared with 30% in symptomatic patients. This finding may reflect the natural history of the disorder, or it may suggest that prenatally identified ureteropelvic junction obstruction is an entity largely different from obstruction presenting later in life.

Adolescent↗
PubMed2000

Management of residual dysplastic vessels after cerebral arteriovenous malformation resection: implications for postoperative angiography.

OBJECTIVE: The verification of surgical resection of cerebral arteriovenous malformations (AVMs) relies on angiography. Abnormal vasculature often is identified after removal of the AVM. Differentiation of dysplastic feeding vessels that resemble the neovascularity of moyamoya disease, as distinct from residual AVM, is crucial for preserving critical brain areas. We review a large experience with immediate postoperative angiography after AVM resection and discuss the implications for management of abnormal dysplastic vessels discovered after AVM resection. METHODS: Beginning in 1992, 86 consecutive patients with AVMs underwent operations by standard protocol for immediate postoperative angiography under the same general anesthetic. Angiographic interpretation dictated admission to the intensive care unit or return to the operating room for further resection. RESULTS: In 78 patients, the angiogram revealed complete resection. Two patients were returned to the operating room, one for residual malformation with an early draining vein, and one for resection of residual dysplastic vessels. There was one postoperative hemorrhage in a patient whose postoperative angiogram was falsely negative for AVM. Six patients with residual dysplastic vessels mimicking residual AVM, but without an early draining vein, were managed conservatively. Delayed follow-up angiography demonstrated spontaneous involution of these abnormal vessels in all of these patients. CONCLUSION: Residual dysplastic feeding vessels resembling the neovascularity of moyamoya disease but not associated with an early draining vein do not necessarily represent residual malformation after AVM resection. The abnormal vessels will proceed to complete spontaneous resolution. Given the difficulty of interpreting intraoperative angiography, immediate postoperative angiography may be a viable alternative after AVM resection.

Adult↗
PubMed1984

Scanning electron microscopy of irradiated recipient blood vessels in head and neck free flaps.

Irradiated and control recipient blood vessels in a similar patient population were studied with scanning electron microscopy. The vessels that were biopsied were then anastomosed to a free flap. Irradiated arteries display a significantly greater wall thickness and higher incidence of intimal dehiscence compared with control arteries. Fibrin deposition, microthrombi, and endothelium cell dehiscence are present more frequently in irradiated vessels than in control vessels. Details of the preparation and anastomotic technique for irradiated blood vessels are discussed. Microvascular surgery in irradiated human blood vessels carries with it a higher risk of thrombosis due to preexisting vessel wall damage. This risk can be minimized by experience and attention to detail.

Arteries↗
PubMed1985

An anatomic study of the septocutaneous vessels of the leg.

The vascular anatomy of the skin and fascia of the leg were studied in 20 cadaver legs that were injected and dissected under magnification to identify the origin, course, and distribution of vessels from the subfascial level to the skin. In addition to the longitudinally oriented fasciocutaneous arteries and the musculocutaneous perforators, the study demonstrated a third and important system of blood supply: the septocutaneous vessels. These vessels arise directly from the posterior tibial, anterior tibial, and peroneal arteries, run along the intermuscular septum, pierce the crural fascia, and ramify radially in the subcutaneous tissue superficial to the fascia. Longitudinally oriented anastomotic arcades are formed along the leg between branches of adjacent septocutaneous vessels. Each septocutaneous vessel has one or two venae comitantes. Selected methylene blue injections of the septocutaneous vessels revealed rich staining of the superficial surface of the fascia, the subcutaneous tissue, and distinct longitudinally oriented skin territories. There was no injection of dye in the deep surface of the fascia. It is felt that the septocutaneous vessels constitute an important source of skin circulation in the leg and form the basis for various fasciocutaneous flaps that have useful clinical applications.

Adult↗
PubMed1993

The histology of lumbar intervertebral disc herniation. The significance of small blood vessels in the extruded tissue.

Six hundred surgical cases of lumbar intervertebral disc herniation were evaluated histologically for the presence of blood vessels. These patients ranged in age from 12 to 77 years. Blood vessels were observed in 57 of 101 cases of complete prolapse type of herniated disc (56.4%), 12 of 32 cases of incomplete prolapse type of herniated disc (37.5%), and 53 of 467 cases of protrusion type of intervertebral disc herniation (11.3%). The presence of blood vessels in intervertebral discs was also investigated in postmortem specimens. Blood vessels were observed in 293 of 616 intervertebral discs (T10-L5), in individuals older than 40 years of age from 100 postmortem spines. The specimen age range was 16-89 years. Most of the blood vessels seen in the extruded tissue, exposed to the epidural space in cases of complete and incomplete prolapse type of herniation, are thought to have been newly formed after herniation occurred. As invasion of the intervertebral disc by blood vessels was found to occur with the advance of age, it is possible that such blood vessels become extruded with the intervertebral disc tissue. The intervertebral disc may herniate posteriorly in three basic patterns. The first pattern is "protrusion type of herniated disc." In protrusion hernia type there is abnormal posterior bulging of the anulus fibrosus. The disc pathology is predominantly nucleus pulposus, and the peripheral layer of the anulus fibrosus remains attached to the vertebral body bony rim, however.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed2006

Distribution of lymphatic vessels in the neural plexuses surrounding the superior mesenteric artery.

OBJECTIVES: To investigate whether lymphatic vessels exist in the neural plexuses surrounding the superior mesenteric artery (SMA) and the ultrastructural relationship between neural plexuses and lymphatic vessels. METHODS: A total of 970 serial sections including the structure surrounding the SMA were obtained from 9 cadavers. They were subjected to conventional hematoxylin/eosin staining and immunostaining for the lymphatic marker D2-40. Epithelial membrane antigen and S100 were also immunostained to identify the perineurium and nerve bundles, respectively. RESULTS: Thin-walled, erythrocyte-free vessels staining with lymphatic markers (D2-40) were found in the neural plexuses surrounding the SMA along a full circumference. There seemed to be a distribution correlation between lymphatic vessels and neural plexuses. Lymphatic vessels were not identified within the nerve bundles. The plexuses contained no lymph nodes in any sections. CONCLUSIONS: To our knowledge we report the immunohistochemical visualization of lymphatic vessels in peri-SMA neural plexuses for the first time. Therefore, particular attention should be paid to the lymphatic vessels within neural plexuses as a possible route of invasion and the source of pancreatic cancer recurrence.

Aged↗
PubMed2004

Importance of lateral row perforator vessels in deep inferior epigastric perforator flap harvesting.

Free flaps based on perforator vessels, and in particular the deep inferior epigastric perforator (DIEP) flap, are currently being applied in abdominal reconstruction. However, one of the main disadvantages is the operative complexity. Through anatomical study and clinical experience with the DIEP flap in breast reconstruction, the intramuscular path of the perforator vessels was comparatively studied, to establish the main anatomical parameters that favor procedure planning. Thirty DIEP flaps from 15 fresh cadavers were used. The number, location, and intramuscular course of the perforator vessels were determined. In addition, an initial clinical study was performed in 31 patients using 35 DIEP flaps in breast reconstruction. The number, location, and the intramuscular course of the perforators were assessed. In the cadaver study, 191 perforator vessels were detected (6.4 vessels per flap). Thirty-four percent were located in the lateral row, and the rectilinear course was observed in 79.2 percent of these vessels. In the medial row, only 18.2 percent of the perforator vessels presented this configuration (p = 0.001). Thirty-one patients underwent DIEP flap breast reconstruction, with 26 immediate and four bilateral reconstructions. In 22 of 35 flaps (62.9 percent), two perforators were used. In 25 flaps (71.4 percent), the lateral row perforators with a rectilinear course were observed. Mean operative time was 7 hours and 37 minutes. Two total flap losses and two partial necroses were observed. The majority of the lateral row perforators presented a rectilinear intramuscular course, which was shorter than that of the medial row perforators. This anatomical characteristic favors dissection with reduced operative time and vascular lesion morbidity, resulting in an important anatomical parameter for DIEP flap harvesting.

Female↗
PubMed2003

Improving recipient vessel exposure during microvascular breast reconstruction.

Microvascular tissue transfer has become the gold standard for breast reconstruction. The primary drawback to these procedures is the technical expertise required for microsurgical anastomosis. This problem is compounded by the difficulties in the exposure of recipient vessels deep within the axilla. Previous techniques used for exposure of these vessels are difficult to setup, provide less than optimal exposure, and have been associated with brachial plexus injuries. The authors retrospectively review their experience using the pediatric OMNI retractor for exposure of recipient vessels during microvascular breast reconstruction. Patient demographics, flap choice, recipient vessels, the incidence of neuropraxia/brachial plexopathy, and microvascular complications were analyzed. Patients in whom more traditional methods of vessel exposure were used (ie, Gelpi retractors, arm positioning, fish hooks; 517 reconstructions in 392 patients) were compared with patients in whom vessel exposure was performed using the pediatric OMNI retractor (699 reconstructions in 571 patients). No differences were noted in comorbid conditions or the incidence of microvascular complications. However, the use of the pediatric OMNI was associated with a significant reduction in operative time in unilateral reconstructions (6:23 +/- 0.05 h vs 7:48 +/- 0.05 h; P <0.01) and decreased incidence of brachial plexus injury (0.17% vs 3.3%; P <0.01). The authors think the decreased neuropraxia rate is the result of better exposure afforded by the pediatric OMNI retractor, which improves exposure and eliminates the need for excessive arm abduction or awkward positioning during the dissection and anastomosis of axillary recipient vessels.

Adolescent↗
PubMed1999

Refilling of embolized vessels in young stems of laurel. Do We need a new paradigm?

Recovery of hydraulic conductivity after the induction of embolisms was studied in woody stems of laurel (Laurus nobilis). Previous experiments confirming the recovery of hydraulic conductivity when xylem pressure potential was less than -1 MPa were repeated, and new experiments were done to investigate the changes in solute composition in xylem vessels during refilling. Xylem sap collected by perfusion of excised stem segments showed elevated levels of several ions during refilling. Stem segments were frozen in liquid N2 to view refilling vessels using cryoscanning electron microscopy. Vessels could be found in all three states of presumed refilling: (a) mostly water with a little air, (b) mostly air with a little water, or (c) water droplets extruding from vessel pits adjacent to living cells. Radiographic probe microanalysis of refilling vessels revealed nondetectable levels of dissolved solutes. Results are discussed in terms of proposed mechanisms of refilling in vessels while surrounding vessels were at a xylem pressure potential of less than -1 MPa. We have concluded that none of the existing paradigms explains the results.

Journal Article↗
PubMed1987

Spring filling of xylem vessels in wild grapevine.

Xylem vessels in grapevines Vitis labrusca L. and Vitis riparia Michx. growing in New England contained air over winter and yet filled with xylem sap and recovered their maximum hydraulic conductance during the month before leaf expansion in late May. During this period root pressures between 10 and 100 kilopascals were measured. Although some air in vessels apparently dissolved in ascending xylem sap, results indicated that some is pushed out of vessels and then out of the vine. Air in the vessel network distal to advancing xylem sap was compressed at about 3 kilopascals; independent measurements indicated this was sufficient to push air across vessel ends, and from vessels to the exterior through dead vine tips, inflorescence scars, and points on the bark. Once wetted, vessel ends previously air-permeable at 3 kilopascals remained sealed against air at pressures up to 2 and 3 megapascals. Permeability at 3 kilopascals was restored by dehydrating vines below -2.4 megapascals. We suggest that the decrease in permeability with hydration is due to formation of water films across pores in intervascular pit membranes; this water seal can maintain a pressure difference of roughly 2 megapascals, and prevents cavitation by aspirated air at xylem pressures less negative than -2.4 megapascals.

Journal Article↗
PubMed1991

A fast and simple algorithm for the calculation of convective heat transfer by large vessels in three-dimensional inhomogeneous tissues.

A fast and simple algorithm has been presented for the calculation of time-dependent temperature distributions in inhomogeneous vascularized tissue. Three-dimensional anatomical data of tissues and vessel structures are decomposed into elementary cubic nodes by a special digitizing routine with vessels represented by connected strings of vessel nodes. Vessel cross sections may be irregular shaped and/or tapered. Conductive and convective heat transfer was calculated through use of the heat balance technique on each cubic node resulting in an explicit finite difference computational scheme. Employing a three time level scheme, the Fourier stability criterion is circumvented allowing arbitrary time steps to be defined in the algorithm. Time steps as large as 100 times the Fourier restricted one still result in stable and convergent calculations of the stationary temperature distribution. Vessels with different flows and diameters are incorporated by performing a vessel specific second discretization step in time. Using the new algorithm as a mathematical tool the thermal equilibration length of vessel segments have been established under a broad range of geometrical and flow conditions. Validation followed from comparing transient and stationary temperature distributions derived by the proposed algorithm to those from an accurate cylindrical numerical model. Predicted values for the thermal equilibration lengths are compared to an analytical expression and phantom experiments. The algorithm is incorporated in a thermal model being the main part of our hyperthermia treatment planning system.

Algorithms↗
PubMed2005

Selective photothermolysis of blood vessels following flashlamp-pumped pulsed dye laser irradiation: in vivo results and mathematical modelling are in agreement.

Laser therapy using the pulsed dye laser is the standard treatment for port-wine stains (PWS). But the mechanism of action has not been elucidated completely, yet. The dorsal skin-fold chamber model in hamsters was used to investigate the effects of laser treatment (lambda(em)=585 nm; pulse duration: 0.45 ms; fluence: 6 J per cm2) on blood vessels. Vessels (n=3394) were marked with FITC dextran (MW 150 kDa) and diameters (2-186 microm) were measured using intravital fluorescence microscopy up to 24 h following irradiation. Histology (H&E, TUNEL, CD31) was taken 1 or 24 h after irradiation. The experimental results were compared with the predictions of a mathematical model based on the finite-element method. Following irradiation treatment the number of unperfused vessels decreases with decreasing vessel diameter in vivo. Histology indicated a restriction of tissue injury to the irradiated area after 1 h. Blood vessels contained aggregated red blood cells. After 24 h tissue damage occurred also outside the irradiated area and thrombus formation was visible. These results were in agreement with the mathematical calculations. In addition to initial physical effects after pulsed dye laser treatment delayed biological processes contribute significantly to the reduction of perfused blood vessels. Because of incomplete photocoagulation of smaller blood vessels (diameter 2-16 microm) a complete bleaching of PWS seems to be unlikely.

Animals↗
PubMed1995

Nerve growth factor, vessel innervation and hypertensive progression in the inbred Dahl SS/Jr and SR/Jr rats.

1. To test whether the inbred Dahl salt-sensitive hypertensive rat strain shares disturbed vessel innervation with the spontaneously hypertensive rat (SHR) model, highly innervated and sparsely innervated tissues from the SR/Jr and SS/Jr strains at several ages were assayed for tissue norepinephrine (NE) content and nerve growth factor (NGF). 2. Only two significant differences were found: (i) 1 week old SS/Jr rat kidneys had more NGF than SR/Jr kidneys; and (ii) six week old mesenteric arteries from SS/Jr contained significantly more NE than those in the SR/Jr animals. 3. The differences are in the expected direction for vessel hyperinnervation as a consequence of high vessel NGF, but the data do not support the hypothesis of a central role for vessel NGF and innervation in the hypertensive progression of the Dahl strain. The vessels of young Dahl inbred rat strains do not display the same degree of vessel hyperinnervation associated with hypertension as found in the young SHR compared to WKY strains. 4. The Dahl strain may lack the disturbed NGF metabolism of the SHR. This might suggest that the Dahl inbred strains and the SHR represent two distinct genetic mechanisms that predispose to hypertension via essentially independent processes and that all forms will evidence at least mildly altered vessel innervation.

Animals↗
PubMed2005

High-resolution time series of vessel density in Kenyan mangrove trees reveal a link with climate.

Tropical trees are often excluded from dendrochronological investigations because of a lack of distinct growth ring boundaries, causing a gap in paleoclimate reconstructions from tropical regions. The potential use of time series of vessel features (density, diameter, surface area and hydraulic conductivity) combined with spectral analysis as a proxy for environmental conditions in the mangrove Rhizophora mucronata was investigated. Intra-annual differences in the vessel features revealed a trade-off between hydraulic efficiency (large vessels) during the rainy season and hydraulic safety (small, more numerous vessels) during the dry season. In addition to the earlywood-latewood variations, a semiannual signal was discovered in the vessel density and diameters after Fourier transformation. The similarity in the Fourier spectra of the vessel features and the climate data, in particular mean relative humidity and precipitation, provides strong evidence for a climatic driving force for the intra-annual variability of the vessel features. The high-resolution approach used in this study, in combination with spectral analysis, may have great potential for the study of climate variability in tropical regions.

Chronobiology Phenomena↗
PubMed1995

Elaboration of stem villous vessels in growth restricted pregnancies with abnormal umbilical artery Doppler waveforms.

OBJECTIVE: To assess the elaboration of placental stem villous vessels from pregnancies complicated by intrauterine growth restriction (IUGR) with absent end-diastolic flow velocity detected prior to delivery in the umbilical artery. DESIGN: Comparison between IUGR and control groups of the distribution, in 15 microns increments of 600 randomly chosen stem vessel profiles (post-fixation diameter 10-160 microns) identified by immunohistochemical localisation of alpha-smooth muscle actin in the vessel media. SETTING: Clinical teaching hospital and university anatomy department. SUBJECTS: Paraffin-fixed blocks obtained from placentas of eight pregnancies complicated by IUGR and eight gestational age-matched controls. RESULTS: The distribution of the stem villous vessels in the IUGR placentas, as assessed by the mean vessel diameter in each case, did not differ from the controls (mean vessel diameter 31.8 microns [SD 2.4] vs 29.6 microns [2.3]; P = 0.13). In five IUGR cases alpha-smooth muscle actin positive cells (myofibroblasts) were identified within the stroma of nonmuscularised peripheral (mature intermediate and terminal) villi, but in none of the controls. CONCLUSIONS: Our data do not support the theory that IUGR with absent end-diastolic flow velocity in the umbilical artery is due to a selective loss of small stem villous vessels. The increased impedance in this condition may be conferred more distally within the nonmuscularised capillaries of the peripheral villi.

Actins↗
PubMed1978

Binding of Trypanosoma congolense to the walls of small blood vessels.

The mesenteric microvasculature was studied in rats and rabbits infected with Trypanosoma congolense. By examining vessels in the living animals, trypanosomes were observed to adhere to vessel walls by their anterior ends. It was evident from stained preparations of the vessels that the microcirculation contained 4-1400 times as many trypanosomes as were free in the cardiac blood. Parasites were more numerous in very small vessels than in larger vessels, and they were clustered in groups within the small vessels. The localization of T. congolense in the microvasculature is demonstrated and it is shown that this localization is established by attachment of the organism to the vessel wall.

Animals↗