Evaluation of endothelium-protective effects of drugs in experimental models of endothelial damage.
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Endothelium-protective properties of pharmacological agents may be assessed by using different experimental models of endothelial dysfunction or injury. The model of endothelial dysfunction induced by vessel perfusion with polymorphonuclear leukocytes (PMN) was used for evaluation of pentoxifylline (PTX) effects on vasoconstrictor responses to noradrenaline (NA) in the rabbit renal artery. Addition of PMN into the perfusion solution significantly increased the responses to NA at all doses. PTX administration (10(-5) mol x l(-1)) significantly diminished the constrictor responses to NA in vessels perfused with PMN+PTX when compared to the responses in PMN-perfused vessels (at dose 0.1 microg: 32.25 vs. 14.25, at dose 1 microg: 51 vs. 27.75 (p<0.01), at dose 10 microg 74.25 vs. 39.75 (p<0.05), all values expressed as median of perfusion pressure in mm Hg). The model of endothelial damage induced by repeated NA administration in 5 doses (10-50 microg of NA) was used for evaluation of the endothelium-protective effect of sulodexide (SLX). It was found that SLX (120 U/l) significantly decreased the number of desquamated endothelial cells (EC) compared to the control group (controls: 131.4+/-20.1 EC, +SLX: 83.3+/-13.8 EC, p<0.01). These results confirmed the favorable endothelium-protective effects of pentoxifylline and sulodexide in the two experimental models. (+info)
Bone marrow transplantation from alternative donors for thalassemia: HLA-phenotypically identical relative and HLA-nonidentical sibling or parent transplants.
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Twenty-nine patients with thalassemia and a median age of 6 years (range 1.1-33 years) were given a BMT from an alternative donor. Six of the 29 donors were HLA-phenotypically identical and two were mismatched relatives, 13 were mismatched siblings and eight were mismatched parents. Six patients received no antigen (relatives), 15 patients one antigen, five patients two antigen and three patients three antigen disparate grafts. Twenty-three patients were in class 2 or class 3, whereas six patients were in class 1. Thirteen patients were given BUCY, nine patients BUCY plus ALG, six patients BUCY plus TBI or TLI and one patient BUCY with prior cytoreductive-immunosuppressive treatment as conditioning. As GVHD prophylaxis four patients received MTX, 22 CsA + MTX + methylprednisolone (MP) and three patients CsA + MP. Thirteen of 29 patients (44.8%) had sustained engraftment. The probability of graft failure or rejection was 55%. There were no significant differences between antigen disparities and graft failure. The incidence of grade II-IV acute GVHD was 47.3% and chronic GVHD was 37.5%. The incidence of acute GVHD was higher in patients receiving one or two antigen disparate in the GVHD direction grafts (vs no antigen) (P EQ 0.04; odds ratio 10.8; 95% CI 1.5-115). The probability of overall and event-free survival was 65% and 21%, respectively, with median follow-up of 7.5 years (range 0.6-17 years) for surviving patients. The degree of HLA disparity between patient and donor did not have a significant effect on survival. The incidence of nonhematologic toxicity was low. Transplant-related mortality was 34%. GVHD (acute or chronic) was a major contributing cause of death (50%) followed by infections (30%). We conclude that at present, due to high graft failure and GVHD rates, BMT from alternative donors should be restricted to patients who have poor life expectancies because they cannot receive adequate conventional treatment or because of alloimmunization to minor blood antigens. (+info)
The role of inflammation in vascular diseases.
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When the body responds to an infectious insult, it initiates an immune response to eliminate the pathogen. The hallmark of the immune response is an inflammatory cascade that can also do extensive damage to host tissues. Inflammation is a major contributing factor to many vascular events, including atherosclerotic plaque development and rupture, aortic aneurysm formation, angiogenesis, and ischemia/reperfusion damage. The immune response is mediated by both circulating and resident leukocytes and the cells with which they interact (e.g., vascular endothelium and smooth muscle cells). The process is orchestrated by the activity of a changing series of released and displayed mediators. These include the expression of adhesion molecules on leukocytes and underlying vascular endothelium and the release of cytokines, chemokines, and tissue-destructive metalloproteases and reactive oxygen species. This review focuses on the causes, the inflammatory processes involved, and possible strategies for decreasing vascular disease through regulation of the inflammatory response. (+info)
Assessment of patient waiting times for vascular surgery.
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OBJECTIVES: To assess patient waiting times for vascular surgery and to determine if complications of the disease develop while the patients are awaiting surgery. DESIGN: Prospective cohort study. SETTING: A university-affiliated tertiary care institution. PATIENTS: All 554 patients who underwent scheduled vascular surgical procedures between April 1995 and October 1996. OUTCOME MEASURES: A literature review carried out to develop guidelines for acceptable waiting times for surgery associated with various vascular disorders based on their natural history (benchmark target); actual waiting times, defined as the interval from the date each patient was booked for surgery to the date of admission to hospital for the procedure; the proportion of patients admitted within the benchmark targets; and whether prolonged waiting time placed patients at risk for complications of their disease. RESULTS: Of the 554 patients, 382 (69%) were admitted within the benchmark waiting times. Of 84 patients having an abdominal aortic aneurysm, the aneurysm ruptured during the waiting period in 6, and 4 of them died, for a complication rate of 7% and a death rate of 5%. Two of the 6 aneurysms ruptured after the patient had waited longer than the target time. Three of 100 patients with symptomatic carotid artery stenosis awaiting admission for carotid endarterectomy suffered ischemic stroke, for a 3% complication rate; all had waited longer than the target period. One patient suffered occlusion of a femoropopliteal bypass graft while awaiting revision of a stenosed bypass graft. CONCLUSIONS: This study suggests that although most patients are admitted for operation within the benchmark time, one-third are admitted late and may suffer serious complications of their disease while awaiting admission for the procedure. (+info)
Enhanced uptake by guinea-pig macrophages of radio-iodinated human aggregated immunoglobulin G in the presence of sera from rheumatoid patients with cutaneous vasculitis.
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A competitive radiobioassay method for soluble immune complexes in sera has been used to study sera from patients with rheumatoid arthritis. Twenty-eight out of sixty-two sera from selected seropositive rheumatoid patients were found to produce enhanced uptake of radio-iodinated human aggregated IgG by guinea-pig macrophages in contrast with the inhibition of uptake seen with SLE sera. Twenty-two out of the twenty-eight enhancing sera belonged to patients with cutaneous vasculitis. None of the twenty-two sera from seronegative rheumatoid patients possessed enhancing properties and none of these patients had clinical evidence of vasculitis. Three patients with seropositive SLE had sera with enhancing properties and had cutaneous vasculitis. We have shown that the enhancement is probably due to the presence in sera of immune complexes or altered IgG bound to rheumatoid factor. The possible mechanism has been investigated and it appears that there is increased binding of radio-iodinated aggregated IgG to free valencies on rheumatoid factor already bound to immune complexes. (+info)
Clearance of inhaled technetium-99m-DTPA as a clinical index of pulmonary vascular disease in systemic sclerosis.
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This study evaluated the utility of the clearance time of inhaled diethylenetriamine pentaacetate (DTPA) to distinguish pulmonary vascular disease from early fibrosing alveolitis (FA) in patients with systemic sclerosis (SSc). It was hypothesized that this would be preserved in patients with vascular disease compared with FA, despite similar gas-transfer deficits and matching lung volumes, because of the preservation of alveolar epithelial integrity. All patients had SSc and were categorized into a control group (C; n=9), pulmonary vascular group (VAS; n=14) or FA group (n=14) dependent on the appearance on a computed tomography (CT) scan and the transfer factor of the lung for carbon monoxide (T(L,CO)) (VAS and FA < or =70%, C > or =80%). All patients had a forced vital capacity (FVC) of >80%. The T(L,CO) (median) was similar in the VAS (57.5%) and FA (60%) groups. There was a significant difference in median DTPA clearance half-times between FA (21.25 min) and VAS (46.5 min) (p=0.014) and between FA and C (84.5 min) (p=0.0004). No difference was found between VAS and C (p=0.0778). Follow-up data from the VAS group showed no subsequent development of FA on the CT scan and no decrease in FVC (n=13, mean 42 months). These results suggest that clearance of diethylenetriamine pentaacetate is preserved in patients likely to have pulmonary vascular disease and may be useful in distinguishing fibrosing alveolitis from vascular disease in systemic sclerosis. (+info)
An imbalance in plasma prostanoids in patients with Raynaud's phenomenon and pulmonary vasospasm.
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Raynaud's phenomenon has been suggested as a predisposing factor for pulmonary vasospasm which may lead to pulmonary hypertension, but the occurrence of cold stimulus-induced pulmonary vasospasm has been inconsistent. Such inconsistent pulmonary vascular responses may be caused by differences in the production of endogenous vasodilators and vasoconstrictors among patients. Fourteen patients with Raynaud's phenomenon associated with mixed connective tissue disease (n=10) or systemic sclerosis (n=4) participated in the study. Right heart catheterization was performed before and after a cold pressor test, immersing a hand in cold water (15 degrees C) for 5 min. Plasma levels of 6-keto prostaglandin (PG)F1alpha, thromboxane (TX)B2 and endothelin (ET)-1 in the mixed venous blood were measured. Mean pulmonary artery pressure increased after the cold pressor test in five of 14 patients, and the patients were divided into those with pulmonary vasospasm (responders) and those without vasospasm (nonresponders). After the cold pressor test, levels of 6-keto PGF1alpha increased significantly in nonresponders (p<0.01) and decreased significantly in responders (p<0.05). The ratios of 6-keto PGF1alpha to TXB2 significantly increased in nonresponders (p<0.01) but not in responders and the difference between responders and nonresponders after the cold pressor test was also statistically significant (p<0.05). No significant change in plasma ET-1 levels occurred in either responders or nonresponders. The results suggest that an impaired production of prostaglandin I2 and an imbalance between prostaglandin I2 and thromboxane A2 are associated with the occurrence of pulmonary vasospasm induced by Raynaud's phenomenon. (+info)
Local paclitaxel delivery for the prevention of restenosis: biological effects and efficacy in vivo.
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OBJECTIVE: The aim of this study was to evaluate the potential of paclitaxel to prevent restenosis in vivo. BACKGROUND: Paclitaxel (Taxol) is a microtubule-stabilizing compound with potent antitumor activity. It influences the cytoskeleton equilibrium by increasing the assembly of altered microtubules, thereby inducing cellular modifications that result in reduced proliferation, migration and signal transduction. METHODS: Before the in vivo study, delivery efficiency was determined with radiolabeled paclitaxel in porcine hearts. After induction of a defined plaque in the right carotid arteries of 76 New Zealand rabbits by electrical stimulation, 27 animals underwent balloon dilation and subsequent local paclitaxel delivery (10 ml, 10 micromol/liter) with a double-balloon catheter. Twenty-nine animals served as control with angioplasty only, 10 animals underwent local delivery of vehicle only (0.9% NaCl solution) and 10 animals were solely electrostimulated. Vessels were excised one, four, and eight weeks after intervention. RESULTS: The extent of stenosis in paclitaxel-treated animals was significantly reduced compared with balloon-dilated control animals (p = 0.0012, one, four and eight weeks after intervention: 14.6%, 24.6% and 20.5%, vs. 24.9%, 33.8% and 43.1%, respectively). Marked vessel enlargement compared with balloon-dilated control animals could be observed (p = 0.0001, total vessel area after one, four and eight weeks: paclitaxel group: 1.983, 1.700 and 1.602 mm2, control: 1.071, 1.338 and 1.206 mm2, respectively). Tubulin staining and electron microscopy revealed changes in microtubule assembly, which were limited to the intimal area. Vasocontractile function after paclitaxel treatment showed major impairment. CONCLUSIONS: Local delivery of paclitaxel resulted in reduced neointimal stenosis and enlargement in vessel size. Both these effects contribute to a preservation of vessel shape and are likely to be caused by a structural alteration of the cytoskeleton. (+info)