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PubMed1985

Effects of papaverine on smooth muscle cell morphology and vein graft preparation.

Venous injury following mechanical distension and its late sequelae were studied in a canine model. Jugular vein segments distended without and with papaverine (60 mg/100 ml) were compared with nondistended vein segments after they had been placed into the arterial circulation for 1 to 12 months. Arteriography showed no significant statistical discrepancy in luminal diameter of the three vein segments. Complete reendothelialization had occurred in all vein grafts at the time of harvesting. Similar histocytologic features existed in the nondistended segments and in the portion distended with human plasma protein fraction (Plasmanate) plus papaverine (150 to 300 mm Hg). The intimal-medial hyperplasia was characterized by an increase in fibrocellular layers with an elaboration of vasa vasorum. Conversely, collagen and extracellular matrix replaced the myocyte, producing medial fibrosis in vein mechanically distended with Plasmanate alone. Papaverine prevented mechanical stimulation of smooth muscle cells to overproduce extracellular connective tissue elements. Mechanical stretching of intimal and medial myocytes induced fibrogenesis and fibroplasia. Papaverine is useful in vein preparation; it protects the endothelium and smooth muscle cells in the intima and media and prevents leukocyte infiltration and medial fibrosis.

Animals↗
PubMed2001

Expression of molecular mediators of apoptosis and their role in the pathogenesis of lower-extremity varicose veins.

PURPOSE: In an earlier study, we observed a significant decrease in apoptosis in varicose veins, as compared with healthy veins, indicating that deregulated apoptosis plays a role in the pathogenesis of varicosities. In addition, significant differences were noted in the expression and subcellular localization of the cell cycle regulatory protein, cyclin D1 in varix tissues, as compared with controls. Because cell cycle checkpoint controls are linked to the signaling and execution of apoptotic cascades, we examined the expression of bcl-2 family members bax and bcl-x, known molecular mediators of apoptosis, and that of poly (ADP-ribose) polymerase (PARP), a downstream substrate of DNA cleavage. METHODS: Twenty varicose vein specimens were retrieved from 20 patients (10 men, 10 women; mean age, 53.6 +/- 4.7 years) undergoing lower-extremity varicose vein excision. Healthy greater saphenous vein segments (n = 27) were obtained from 27 patients (14 men, 13 women; mean age, 59.5 +/- 2.4 years) undergoing infrainguinal arterial bypass grafting surgery. All tissues were distal portions. As per CEAP classification for chronic lower-extremity venous disease, most of the patients were in class 2 for clinical signs (n = 11); some patients were in class 3 (n = 4) or class 4 (n = 4), and only one patient was in class 5. Five 5-microm thick sections from formalin-fixed, paraffin-embedded specimens were used as a means of immunohistochemically localizing the expression of bax, bcl-x, and PARP, and 10 random high-power fields per section were evaluated by two independent reviewers blinded to the clinical findings. Statistical analyses were conducted by means of chi(2), analysis of variance, Student and Fisher exact t tests with StatView software. RESULTS: Immunoreactivity to pro-apoptotic bax was significantly higher in the normal veins (P <.001). Cytoplasmic expression of bcl-x was prominent in the cells of the vasa vasorum in both varicose and healthy veins. PARP expression was diminished in the varicose vein group, with 2.8 +/- 0.7 (P =.01) and 1.4 +/- 0.5 (P =.05) cells per high-power field in the intima and media, respectively. Neither bax nor PARP was noted in the adventitia of varicose veins, although their expression was detected in this layer of the control group (P <.001). CONCLUSION: The entry of smooth muscle cells into the apoptotic pathway may be regulated by the induction of bax in this model, because there is significant presence of this pro-apoptotic protein in healthy veins. Both bax and PARP are downregulated in varicose veins, as compared with healthy veins, and this may play a significant role in the pathogenesis of varicose veins.

Apoptosis↗
PubMed2001

Expression of the proto-oncogene c-myc in human stenotic aortocoronary bypass grafts.

Proliferation and differentiation of vascular smooth muscle cells (VSMC) are central events in vascular pathobiology and play a major role in the development of stenotic and restenotic lesions. The proto-oncogene c-myc and other early cell cycle-regulating genes have been implicated in the induction of cell proliferation and differentiation under diverse pathophysiological conditions. In the present study we analyzed c-myc mRNA expression by indirect nonradioactive in situ hybridization technique (NISH) in human stenotic venous bypass grafts (n = 32) retrieved during re-do operations of coronary artery disease and compared the results with 28 native veins (vena saphena magna) from the same patients. Stenotic bypass grafts showed enhanced c-myc expression located predominantly in VSMC in the media and neointima (severity score: ++-+++, 32/32 stenotic veins). In native veins we observed only low levels of c-myc mRNA (severity score: +, 28/28 native veins), all signals were restricted to endothelial cells of either the innermost intimal layer or of the vasa vasorum. Our in situ hybridization studies demonstrate enhanced mRNA expression of the proto-oncogene c-myc in stenotic venous bypass grafts. These results suggest that--in analogy to other pathophysiological conditions--c-myc exerts essential regulatory functions in cellular events operative during the initiation and progression of venous bypass graft disease.

Adult↗
PubMed1995

Aortitis with dissection complicating systemic lupus erythematosus.

A 31 yr old female under treatment for systemic lupus erythematosus complained of episodes of atypical chest pain radiating to the back. Subsequently she suddenly collapsed and died. Post mortem revealed a well-defined, localized area of non-giant cell aortitis extending from the supra-aortic ridge of the aortic valve to the ligamentum arteriosum. Active arteritis with fibrinoid necrosis and obliterative endarteritis of vasa vasorum had resulted in multiple infarcts of differing ages with associated inflammation and disruption of the aortic wall, culminating in aortic dissection and cardiac tamponade.

Adult↗
PubMed2004

Thrombogenesis, atherogenesis and angiogenesis in vascular disease: a new 'vascular triad'.

Amongst the components of the pathophysiology of atherosclerosis are the tendency to thrombus formation (i.e., thrombogenesis) and the loss of endothelial cell integrity. The endothelium is also implicated in atherogenesis, as vasa vasorum are present in the adventitia and media at a higher density in atherosclerotic tissue, and that neovascularisation leading to collateral growth bypassing obstruction and/or stenoses provides important alternative routes to feeding distal tissues. The development of these new blood vessels is the process of angiogenesis. The present 'viewpoint' article will explore the relationships between the three processes. There is considerable evidence that atherogenesis and thrombogenesis are intimately linked, but angiogenesis in cardiovascular disease is a recently developed concept. We propose a new 'vascular triad' of these abnormal pathophysiological processes, leading to an alternative view of the pathogenesis of vascular disease. Indeed, we suggest that angiogenesis is an important aspect of the pathophysiology of cardiovascular disease, impacting with both thrombogenesis and atherogenesis, in a new vascular triad (the 'Birmingham vascular triad').

Arteriosclerosis↗
PubMed1990

Localization of anticoagulantly active heparan sulfate proteoglycans in vascular endothelium: antithrombin binding on cultured endothelial cells and perfused rat aorta.

We have studied the interaction of 125I-antithrombin (125I-AT) with microvascular endothelial cells (RFPEC) to localize the cellular site of anticoagulantly active heparan sulfate proteoglycans (HSPG). The radiolabeled protease inhibitor bound specifically to the above HSPG with a Kd of approximately 50 nM. Confluent monolayer RFPEC cultures exhibited a linear increase in the amount of AT bound per cell for up to 16 d, whereas suspension RFPEC cultures possessed a constant number of protease inhibitor binding sites per cell for up to 5 d. These results suggest that monolayer RFPEC cultures secrete anticoagulantly active HSPG, which then accumulate in the extracellular matrix. This hypothesis was confirmed by quantitative light and EM level autoradiography which demonstrated that the AT binding sites are predominantly located in the extracellular matrix with only small quantities of protease inhibitor complexed to the cell surface. We have also pinpointed the in vivo position of anticoagulantly active HSPG within the blood vessel wall. Rat aortas were perfused, in situ, with 125I-AT, and bound labeled protease inhibitor was localized by light and EM autoradiography. The anticoagulantly active HSPG were concentrated immediately beneath the aortic and vasa vasorum endothelium with only a very small extent of labeling noted on the luminal surface of the endothelial cells. Based upon the above data, we propose a model whereby luminal and abluminal anticoagulantly active HSPG regulate coagulation mechanism activity.

Animals↗
PubMed1994

Adenoviral vector-mediated gene transfer into sheep arteries using a double-balloon catheter.

The potential for catheter-based in vivo delivery of genetic material to the arterial wall is incompletely explored. We evaluated the level of recombinant protein production as well as the anatomic distribution and duration of gene expression following adenoviral vector-mediated gene transfer into sheep arteries via a double balloon catheter. Catheters were positioned in the carotid or femoral arteries of 20 sheep via a combined percutaneous and surgical approach, and virions infused over a 30-min period. Three days later, recombinant gene expression was identified in approximately 30% (range 0-80%) of the luminal endothelial cells within the targeted area of the artery. Persistent recombinant protein expression was identified histochemically for up to 4 weeks, although the number of positive cells decreased steadily. High levels of both beta-galactosidase (beta-Gal) activity and protein (mean 20 mU and 44 ng per vessel) were measured in vessel extracts 3 days after gene transfer, again decreasing significantly over a 4-week period. Transgene expression was limited almost entirely to the intima and adventitia; adventitial gene transfer occurred virtually exclusively along the vasa vasorum. In comparison to previous studies of catheter-based gene transfer, adenoviral vectors delivered by double balloon catheter resulted in a particularly high efficiency of endothelial cell gene transfer. The efficiency and amount of recombinant gene expression achieved in this study suggest that catheter-based gene delivery may eventually be applicable to the treatment of focal human arterial disease.

Adenoviridae↗
PubMed1991

Neuropeptide Y (NPY) co-exists with tyrosine hydroxylase and potentiates the adrenergic contractile response of vascular smooth muscle in the human uterine artery.

The human uterine artery was studied by immunocytochemistry and in vitro pharmacology. Nerve fibres containing immunoreactivity for neuropeptide Y (NPY) were encountered in the media, adventitia, smooth muscle layers and surrounding the vasa vasorum. Approximately 50% of the nerve fibres containing NPY also stored immunoreactivity for tyrosine hydroxylase (TH) and TH activity was found in no other fibres. Noradrenaline (NA) contracted the isolated uterine artery in a concentration dependent manner. The presence of increasing doses of NPY shifted the concentration-response curve for NA to the left. Consequently the pD2-values were increased indicating a potentiation of the adrenergic effects induced by NPY. The results demonstrate the existence of NPY in adrenergic nerve fibres surrounding the human uterine artery. A close co-operation between NPY and NA in the neuronal control of smooth muscle is suggested.

Adult↗
PubMed1975

Localization of tissue plasminogen activator in relation to morphologic changes in human saphenous veins used as coronary artery bypass autografts.

Employing the histochemical fibrin slide technique, we studied the localization of fibrinolytically active sites in relation to morphologic changes in saphenous veins used as coronary artery bypass autografts. Of veins from 100 patients undergoing surgery for coronary heart disease, 63 samples revealed well-demarcated intimal fibrinolytic activity. Distinct foci of lysis were present in the media and adventitia of all vein samples corresponding to the distribution of the vasa vasorum. Graft specimens obtained by autopsy from 13 patients surviving from 30 minutes to 13 days revealed considerable intimal damage with loss of fibrinolytic activity. Medial fibrinolytic activity disappeared early concomitant with disorganization of the medial muscle fibers, followed by necrosis, atrophy and fibrous transformation of the muscular structures. Adventitial activity disappeared later. One reoperation sample obtained after 8 weeks in situ showed moderate proliferative intimal fibrosis without an apparent neo-intima and without fibrinolytic activity, and one section showed evidence of valve cusp fibrosis, while most of the media had been replaced by fibrous tissue. Numerous foci of "medial" -adventitial fibrinolytic activity indicated presence of vascular structures in the venous wall. The fibrin slide technique is a convenient tool for studying the process of revascularization.

Atrophy↗
PubMed1984

Vein to artery grafts. An experimental study of reinnervation of the graft wall.

Iliolumbar vein to iliac artery grafts were placed in 21 rats by microsurgical techniques. Graft innervation was examined at five time intervals between 1 and 32 weeks after surgery. Nerve fibers were demonstrated microscopically by formaldehyde-induced fluorescence of catecholamines. The morphology and degree of graft innervation were assessed, semiquantitatively, relative to the contralateral iliac artery (control) within each animal. Nerves were seen in the graft region as early as 2 weeks, but it was not until 4 weeks that they were present along its length (5 mm). The formation of a nerve plexus in the adventitia surrounding the graft was evident at 8 weeks. By 16 weeks the degree of innervation in the graft had increased to a level that was greater than the control iliac artery in three of four animals examined. Grafts at 32 weeks were also hyperinnervated. However, the morphology of this innervation was different from the control arteries; nerve fibers were finer, not varicosed, and were located at a greater distance from the outer layer of smooth muscle cells. The origin of the nerves appeared to be collateral sprouts from nerves supplying the adjacent iliac vein and also from invading vasa vasorum. The host iliac artery nerve plexus did not contribute to graft innervation.

Animals↗
PubMed2001

Behçet disease.

Central nervous system involvement in Behçet disease (BD) may be either parenchymal or nonparenchymal. Abnormal cerebrospinal fluid findings and parenchymal involvement are associated with a poorer prognosis. A self-antigenic role for HLA B51 has been postulated in the pathogenesis of BD. The sibling occurrence rate is 3.6%. Familial aggregation may be more pronounced among pediatric cases compared with adult cases. The importance of inherited coagulation abnormalities in the pathogenesis of BD is not clear. Vasculitis of the vasa vasorum seems to be the major site of pathology in large vessel disease. Even among experts, no consensus exists regarding the optimal approach to treatment. Low-dose thalidomide is effective for the mucocutaneous lesions, but polyneuropathy complicates its prolonged use. Neurologic side effects of cyclosporine A should preclude its use in patients with central nervous system involvement except in unusual circumstances. The heightened inflammatory response of BD patients to simple trauma may lead to postoperative complications, but should not be regarded as a contraindication to surgery.

Behcet Syndrome↗
PubMedDate not supplied

Long-term results of a new antithrombogenic cardiac wall substitute.

We evaluated the long-term results of a new antithrombogenic cardiac wall substitute which is composed of collagen-coated ultrafine polyester mesh cross-linked by a hydrophilic polyepoxy compound (CUFP), and compared it with glutaraldehyde-treated equine pericardium (GA graft). In an animal study, 20 CUFPs and 18 GA control grafts were implanted as patches in the right ventricular outflow tract in 38 dogs. In the CUFP at 28 days after implantation, a thin neointima, which was almost endothelialized, had been formed. Fibroblasts and vasa vasorum were seen inside both the neointima and the graft wall. At 168 days, transmission electron microscopy revealed smooth muscle-like cells in the neointima, with endothelialization. The CUFP at 486 days had maintained a white, shiny, smooth, thin, and uniform neointima with endothelialization. Neither ulcer nor thrombus formation was seen on the surface, while in the GA graft at 353 days, no endothelialization was noticed in the center and almost no fibroblasts had infiltrated into the graft wall. From these results, the CUFP should be an ideal candidate for cardiac wall substitution.

Animals↗
PubMed1987

Effect of a renin-system inhibitor on blood-vessel adaptation in spontaneously hypertensive rats.

We tested the hypothesis that a metabolic error may be the triggering mechanism which leads to blood-vessel hypertrophy and hypertension. Young spontaneously hypertensive rats (SHR) were fed a moderately high salt diet to exacerbate the purported metabolic error. Haematocrit values and rubidium transport were measured as evidence of renal ATP deficiency and blood-vessel adaptation. The renin system was inhibited in two groups of SHR by giving them enalapril to determine whether angiotensin II was involved in blood-vessel adaptation. Spontaneously hypertensive rats fed the moderately high salt diet had higher haematocrit values than normotensive rats fed the same diet or SHR fed Purina rat food, suggesting a renal ATP deficiency. Spontaneously hypertensive rats had higher Na+,K+-ATPase activity in thoracic aorta after 60 min incubation than a similar group given enalapril (P less than 0.001), suggesting blood-vessel adaptation. Possibly, angiotensin II within the vasa vasorum stimulates hypertrophy which, according to the Folkow hypothesis, leads to higher blood pressure, but may concomitantly increase the respiratory chain units which provide ATP for renal function and ion transport.

Angiotensin II↗
PubMed1992

Vascular compromise prior to intestinal manifestations of Crohn's disease in a 14-year-old girl.

Vascular manifestations as extraintestinal symptoms of Crohn's disease are rare and only occasionally reported in children. A 14-year-old girl with vascular compromise prior to intestinal manifestations of Crohn's disease is described. The vascular symptoms were due to segmental narrowing of several major arteries as shown by angiography. This kind of vascular involvement in our patient is different from the pattern described in Crohn's disease and resembles Takayasu's disease. Recently, it has been suggested that Crohn's disease could be mediated by multifocal gastrointestinal infarction due to chronic focal mesenteric arteritis at the level of the muscularis propria of the gut. In Takayasu's disease, a granulomatous inflammation of the vasa vasorum of affected vessels is frequently found. An intramural arteritis, granulomatous in nature, could be the common pathway in both Crohn's and Takayasu's diseases. Until the etiologies of both diseases are uncovered, the interrelation between them will remain subject to speculation.

Adolescent↗
PubMed1997

Heme oxygenase activity and immunohistochemical localization in bovine pulmonary artery and vein.

Recent studies suggest that carbon monoxide (CO) derived from heme oxygenase (HO)-catalyzed metabolism of heme plays a role in the regulation of cell function and communication. In blood vessels, CO may regulate vascular smooth-muscle tone through the activation of soluble guanylyl cyclase, in a manner similar to that of nitric oxide. The objective of this study was to determine the relation between HO enzymatic activity and localization of HO protein in bovine pulmonary blood vessels. HO enzymatic activity was determined by quantitating the rate of CO formation in the microsomal fraction of homogenates of bovine pulmonary artery (BPA) and vein (BPV). HO protein was localized by immunohistochemical analysis of paraformaldehyde-fixed tissue by using polyclonal antibodies to inducible HO (HO-1) and noninducible HO (HO-2). HO enzymatic activity was measured in BPA and BPV, which correlated with the presence of HO protein. In BPA, HO enzymatic activity was found in the adventitia and medial layer; HO protein was localized in the nerves and vasa vasorum of the adventitia and was found throughout the smooth-muscle cells in the medial layer. The data clearly demonstrate the presence of HO enzymatic activity for the formation of CO in blood vessels that contain HO protein.

Animals↗
PubMed2000

Cellular allograft rejection affecting the donor aorta after combined heart-lung transplantation.

BACKGROUND: Infectious pseudoaneurysms of the ascending aorta are a recognized major complication after heart-lung transplantation. METHOD: This report describes an unusual and previously unreported complication, that of cellular allograft rejection, which caused a pseudoaneurysm of the donor's ascending aorta in a patient who underwent combined heart-lung transplantation. Repair was performed by primary suture after mobilization of the aortic segments. RESULT: On histological examination the resected aneurysm showed evidence of proliferative vasculitis with perivascular infiltration of the vasa vasorum by mononuclear cells. The mononuclear cells were identified as CD4+ and CD8+ by immunohistological staining. CONCLUSIONS: This report shows that cellular allograft rejection may affect the donor aorta after heart-lung transplantation and may result in pseudoaneurysm formation, even under triple-drug immunosuppression after ABO-compatible allograft transplantation.

Adult↗
PubMed1998

Local delivery of antithrombin inhibits platelet deposition after balloon injury in a porcine coronary model.

BACKGROUND: Thrombin activation and initiation of the coagulation process can lead to thrombotic complications after coronary angioplasty. A therapeutic approach may be effectively to inhibit thrombin activity at the site of the vessel wall injury. OBJECTIVE: The aim of the present study was to investigate the short-term effects of local delivery of antithrombin on coronary vessel wall injury in pigs. METHODS: A coronary balloon angioplasty was performed in the left anterior descending artery. Twenty-four hours before the procedure, platelets were marked with Indium 111 and infused into the pig. Before catheterisation 100 U/kg of heparin was administered. Eight pigs received 250 U (5 ml) of antithrombin and, as a control, eight received 10 mg of albumin (5 ml) delivered using a local drug delivery balloon catheter. Microscopic preparation of the injured part of the vessel was performed, and the amount of radioactivity was measured, giving the number of platelets per cm2. Plasma antithrombin level was measured before and after local delivery. The amount of antithrombin in the vessel wall was measured using a semi-quantitative method involving anti-antithrombin antibodies. RESULTS: The number of platelets per cm2 was significantly lower in the antithrombin group (mean 2.3 x 10(6)) than in the control group (6.3 x 10(6), P= 0.02 ). No macroscopic thrombus was detected in the antithrombin group, whereas three out of eight pigs in the control group had visible thrombus formation (NS). There was an increase in the plasma concentration of antithrombin after local delivery. In the antithrombin group, antithrombin was detected in the intima, the lumen part of the media and in the vasa vasorum. CONCLUSION: Antithrombin can be administered and deposited locally in the coronary vessel wall thereby reducing platelet deposition after balloon injury.

Angioplasty, Balloon, Coronary↗
PubMed2001

Time course of vascular remodeling, formation of neointima and formation of neoadventitia after angioplasty in a porcine model.

BACKGROUND: Vascular remodeling is the major cause of restenosis after coronary balloon angioplasty but the pathophysiology of this process is not known. OBJECTIVE: To examine the time courses of vascular remodeling, formation of neointima and adventitial changes after coronary angioplasty. DESIGN: An experimental study on pigs using coronary angiography, intravascular ultrasound (IVUS), and histology. METHODS: Deep vessel-wall injury was induced by conventional balloon angioplasty in the circumflex and right coronary arteries, and by retraction of a chain-encircled balloon in the left anterior descending artery. Angiography in all three arteries and IVUS measurements in circumflex and left anterior descending arteries were performed before and after angioplasty, and at follow-up on days 0, 1, 4, 7, 14, 28, and 56 (n = 5 in each group). Serial IVUS measurements were used to determine vascular remodeling. Formation of neointima and neoadventitia was measured by histomorphometry. RESULTS: Angiographically evident loss of lumen and ultrasonographically detectable constrictive remodeling occurred between day 7 and day 28. IVUS measurements showed that late loss of lumen (days 28 and 56) was correlated to vascular remodeling but not to the increase in wall area (neointima plus media). Histomorphometry revealed that neointima was present from day 7 and that amount of neointima increased up to day 28. Area of adventitia increased during the first 4 days and remained unchanged thereafter. Adventitial neovascularization by vasa vasorum was observed from day 4 onward. CONCLUSIONS: Formation of neoadventitia precedes late loss of lumen, constrictive remodeling, and formation of neointima. The time course of vascular remodeling coincides with growth of neointima rather than with changes in the adventitia.

Angioplasty, Balloon, Coronary↗