Attenuation of acute lung injury in transgenic mice expressing human transforming growth factor-alpha.
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Transforming growth factor-alpha (TGF-alpha) is produced in the lung in experimental and human lung diseases; however, its physiological actions after lung injury are not understood. To determine the influence of TGF-alpha on acute lung injury, transgenic mouse lines expressing differing levels of human TGF-alpha in distal pulmonary epithelial cells under control of the surfactant protein C gene promoter were generated. TGF-alpha transgenic and nontransgenic control mice were exposed to polytetrafluoroethylene (PTFE; Teflon) fumes to induce acute lung injury. Length of survival of four separate TGF-alpha transgenic mouse lines was significantly longer than that of nontransgenic control mice, and survival correlated with the levels of TGF-alpha expression in the lung. The transgenic line expressing the highest level of TGF-alpha (line 28) and nontransgenic control mice were then compared at time intervals of 2, 4, and 6 h of PTFE exposure for differences in pulmonary function, lung histology, bronchoalveolar lavage fluid protein and cell differential, and lung homogenate proinflammatory cytokines. Line 28 TGF-alpha transgenic mice demonstrated reduced histological changes, decreased bronchoalveolar lavage fluid total protein and neutrophils, and delayed alterations in pulmonary function measures of airway obstruction compared with those in nontransgenic control mice. Both line 28 and nontransgenic control mice had similar increases in interleukin-1beta protein levels in lung homogenates. In contrast, interleukin-6 and macrophage inflammatory protein-2 levels were significantly reduced in line 28 transgenic mice compared with those in nontransgenic control mice. In the transgenic mouse model, TGF-alpha protects against PTFE-induced acute lung injury, at least in part, by attenuating the inflammatory response. (+info)
Comparative evaluation of externally supported Dacron and polytetrafluoroethylene prosthetic bypasses for femorofemoral and axillofemoral arterial reconstructions. Veterans Affairs Cooperative Study #141.
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PURPOSE: Currently, the choice of a vascular prosthesis for an extra-anatomic arterial bypass graft is left to the surgeon's preference because well-designed comparative evaluations have not been performed. The Department of Veterans Affairs Cooperative Study 141 was organized to identify whether there is improved patency with different prosthetic grafts for patients with femorofemoral or axillofemoral bypass grafts. METHODS: Between June 1983 and June 1988, patients at 20 Veterans Affairs Medical Centers who had aortoiliac occlusive disease but were not considered suitable candidates for aortic bypass surgery were randomized to receive either an externally supported polytetrafluoroethylene or Dacron bypass graft for an extra anatomic bypass. Doppler-derived ankle brachial indices (ABIs) were determined before the operation and serially after the operation. Patients were seen in follow-up every 3 months for the first year and every 6 months thereafter. All patients were instructed to take 650 mg of aspirin each day for the duration of the study. A bypass graft was considered to be patent if the Doppler-derived postoperative ABI remained significantly improved (0.15 units above the preoperative value), and additional clinical information (such as subsequent ABIs, angiograms, or operations) did not contradict these observations. RESULTS: Three hundred forty patients with femorofemoral bypass grafts and 79 patients with axillofemoral or axillofemorofemoral bypass grafts were randomized. The indication for the bypass operation was limb salvage in 72% of the patients. The assisted primary patency rate for a Dacron bypass grafting was 79% at 1 year, 63% at 3 years, and 50% at 5 years; for polytetrafluoroethylene bypass grafting, the patency was 77% at 1 year, 62% at 3 years, and 47% at 5 years. CONCLUSION: The overall results of this prospective randomized study suggest that the current choices of prosthetic bypass grafting have similar long-term patency in patients who undergo femorofemoral or axillofemoral vascular reconstruction. (+info)
Rapid extraction of clenbuterol from human and calf urine using empore C8 extraction disks.
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In the present paper, disk extraction was evaluated for the rapid isolation of clenbuterol from human and calf urine, followed by high-performance liquid chromatography analysis with UV detection. A method was developed for the extraction with standard density C8 disks. The disks could be washed with 25% methanol in 0.01M sodium hydroxide without significant losses of clenbuterol. The recovery of denbuterol was about 85%, and the extracts were clean. The detection limit was about 10 ng/mL. The main advantages of these disks were the saving of time and the reduced amounts of organic solvents needed. (+info)
Late aneurysm of the distal aortic arch after repair of aortic interruption. A case report.
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Aneurysm formation after aortic coarctation repair is not a rare complication of post-coarctation of aorta repair. We describe the case of a 43-year-old woman who had undergone repair of an isolated interruption of the aortic arch 30 years earlier, who came to our hospital with progressive chest pain, cough and dyspnea. A giant aortic aneurysm was revealed in the distal aortic arch by CT study. The patient underwent aneurysmectomy with total aortic arch replacement using a Dacron graft through redo median sternotomy. An embryologic explanation of this patient's anomaly and the previous surgical procedure are discussed for defining this rare clinical condition. (+info)
Enhanced endothelialization and microvessel formation in polyester grafts seeded with CD34(+) bone marrow cells.
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The authors have shown accelerated endothelialization on polyethylene terephthalate (PET) grafts preclotted with autologous bone marrow. Bone marrow cells have a subset of early progenitor cells that express the CD34 antigen on their surfaces. A recent in vitro study has shown that CD34(+) cells can differentiate into endothelial cells. The current study was designed to determine whether CD34(+) progenitor cells would enhance vascular graft healing in a canine model. The authors used composite grafts implanted in the dog's descending thoracic aorta (DTA) for 4 weeks. The 8-mm x 12-cm composite grafts had a 4-cm PET graft in the center and 4-cm standard ePTFE grafts at each end. The entire composite was coated with silicone rubber to make it impervious; thus, the PET segment was shielded from perigraft and pannus ingrowth. There were 5 study grafts and 5 control grafts. On the day before surgery, 120 mL bone marrow was aspirated, and CD34(+) cells were enriched using an immunomagnetic bead technique, yielding an average of 11.4 +/- 5. 3 x 10(6). During surgery, these cells were mixed with venous blood and seeded onto the PET segment of composite study grafts; the control grafts were treated with venous blood only. Hematoxylin and eosin, immunocytochemical, and AgNO(3 )staining demonstrated significant increases of surface endothelialization on the seeded grafts (92% +/- 3.4% vs 26.6% +/- 7.6%; P =.0001) with markedly increased microvessels in the neointima, graft wall, and external area compared with controls. In dogs, CD34(+) cell seeding enhances vascular graft endothelialization; this suggests practical therapeutic applications. (Blood. 2000;95:581-585) (+info)
Vein interposition cuffs decrease the intimal hyperplastic response of polytetrafluoroethylene bypass grafts.
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PURPOSE: The modification of the distal anastomosis of polytetrafluoroethylene (PTFE) bypass grafts with vein interposition cuffs (VCs) has been reported to increase graft patency. However, the mechanisms that are responsible for this improved patency are unclear. Because intimal hyperplasia (IH) is a primary cause of prosthetic graft failure, we hypothesized that VCs affect the distal anastomosis by decreasing the IH response of the outflow artery. METHODS: Twenty-three female domestic Yorkshire pigs (mean weight, 35 kg) underwent 42 femoral PTFE bypass grafting procedures. The PTFE bypass grafts were separated into the following three groups according to distal anastomotic configuration: end-to-side anastomoses (ES), VCs, and cuffs constructed with PTFE (PCs). Four femoral arteries from two pigs served as healthy controls. At sacrifice, the grafts were perfusion fixed, and the distal anastomoses harvested at 1 and 4 weeks. The specimens were hemisected and serially sectioned to identify the heel, toe, and mid-anastomotic regions. The sections were cut into 5-microm segments and analyzed for intima and media thickness and area, intima/media area ratio, and the distribution of IH in the vein cuff. The roles of transforming growth factor-beta1 and platelet-derived growth factor-BB in IH development were assessed with immunohistochemistry. RESULTS: IH development was significantly lower at all areas of the anastomosis, with VCs compared with ES and PCs at 4 weeks (P +info)
Mechanism of dacron-activated monocytic cell oxidation of low density lipoprotein.
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PURPOSE: Oxidized lipids are believed to contribute to atherogenesis and may play a role in the development of anastomotic intimal hyperplasia in prosthetic vascular grafts. This study examines the hypothesis that clinically relevant graft material activates monocytes to oxidize low density lipoprotein (LDL). METHODS: LDL and Dacron or expanded polytetrafluoroethylene (ePTFE) graft material were incubated in the presence of U937 cells, a monocytic cell line. LDL oxidation was measured by conjugated dienes, lipid peroxides, thiobarbituric acid-reacting substances, and electrophoretic mobility. Cell production of superoxide was measured by ferricytochrome c reduction. Metal ion requirement was assessed with the metal chelators, ethylenediaminetetra-acidic acid, deferoxamine, and bathocuproinedisulfonic acid. To determine whether human monocytes were capable of being activated by Dacron graft material to oxidize LDL, freshly isolated peripheral blood monocytes were also studied. RESULTS: Incubation of LDL with U937 cells and Dacron increased LDL oxidation by 5- to 20-fold. LDL incubated with ePTFE or U937 cells alone resulted in minimal oxidation. Dacron graft increased U937 cell production of superoxide by 4-fold, whereas ePTFE had no effect. Superoxide dismutase inhibited Dacron-activated U937 cell oxidation of LDL by greater than 50%, which indicates a role for superoxide. Ethylenediaminetetra-acidic acid, deferoxamine, and bathocuproinedisulfonic acid each inhibited Dacron-activated U937 cell oxidation of LDL. Human peripheral blood monocytes were activated by Dacron graft material to oxidize LDL; superoxide dismutase inhibited Dacron-activated human monocytic oxidation of LDL, which suggests a role for superoxide. CONCLUSION: These results suggest that Dacron graft material activates monocytes to oxidize LDL by a mechanism that involves superoxide and requires iron and copper ions. Our work suggests a mechanism by which lipids that have been deposited within implanted vascular grafts may become oxidized. Oxidized lipids may contribute to the cellular dysfunction that results in anastomotic intimal hyperplasia and graft failure. (+info)
Isolation of endothelial cells and their progenitor cells from human peripheral blood.
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PURPOSE: We have developed techniques to isolate endothelial cell (EC) progenitors from human peripheral and umbilical cord blood. METHODS: Human adult peripheral and umbilical cord blood monocytes were isolated by centrifugation, and progenitor cells were separated with the use of magnetic polystyrene beads that were coated with a monoclonal antibody specific for the CD34 cell-membrane antigen. Cells were propagated in selective media, and developing cultures were immunostained for CD31, CD34, factor VIII, and vascular endothelial growth factor cell receptors. ECs that developed were transfected with a gene for prourokinase and used to line ePTFE grafts, which were evaluated in vitro in a pulsatile flow system. RESULTS: Umbilical cord monocyte cultures demonstrated colonies that resembled ECs at approximately 2 weeks, with growth being best supported by EC growth media plus 20% calf serum with iron. Immunostaining of colonies was positive for CD31 and factor VIII. After 18 days in culture, CD34(+) cells from adult peripheral blood were noted, which had the typical cobblestone appearance of ECs and immunostained positively for CD31 and factor VIII-related antigens. Cultures of umbilical cord-derived cells and adult peripheral blood-derived cells developed complex line formations within 1 week in culture that stained positively for vascular endothelial growth factor receptor-2. Urokinase-transfected ECs were shown to overexpress urokinase. Prosthetic grafts lined with transfected cells showed 87.33% +/- 4.97% cell adherence after 2 hours in a pulsatile flow system at clinically relevant shear stress. CONCLUSION: We conclude that endothelial progenitor cells can be isolated from human adult peripheral and umbilical cord blood and developed into EC cultures as a source of cells for vascular graft seeding and gene therapy. (+info)