Use of high-intensity focused ultrasound to control bleeding.
OBJECTIVE: High-intensity focused ultrasound (HIFU) has been shown to be effective in controlling hemorrhage from punctures in blood vessels. The objective of the current study was to investigate the capability of HIFU to stop bleeding after a more severe type of vascular injury, namely longitudinal incisions of arteries and veins. METHODS: The superficial femoral arteries, common femoral arteries, carotid arteries, and jugular veins of four anesthetized pigs were exposed surgically. A longitudinal incision, 2 to 8 mm in length, was produced in the vessel. HIFU treatment was applied within 5 seconds of the onset of the bleeding. The HIFU probe consisted of a high-power, 3.5-MHz, piezoelectric transducer with an ellipsoidal focal spot that was 1 mm in cross section and 9 mm in axial dimension. The entire incision area was scanned with the HIFU beam at a rate of 15 to 25 times/second and a linear displacement of 5 to 10 mm. A total of 76 incisions and HIFU treatments were performed. RESULTS: Control of bleeding (major hemosatsis) was achieved in all 76 treatments, with complete hemostasis achieved in 69 treatments (91%). The average treatment times of major and complete hemostasis were 17 and 25 seconds, respectively. After the treatment, 74% of the vessels in which complete hemostasis was achieved were patent with distal blood flow and 26% were occluded. The HIFU-treated vessels showed a consistent coagulation of the adventitia surrounding the vessels, with a remarkably localized injury to the vessel wall. Extensive fibrin deposition at the treatment site was observed. CONCLUSION: HIFU may provide a useful method of achieving hemostasis for arteries and veins in a variety of clinical applications. (+info)
Adventitial delivery minimizes the proinflammatory effects of adenoviral vectors.
PURPOSE: Adenovirus-mediated arterial gene transfer is a promising tool in the study of vascular biology and the development of vascular gene therapy. However, intraluminal delivery of adenoviral vectors causes vascular inflammation and neointimal formation. Whether these complications could be avoided and gene transfer efficiency maintained by means of delivering adenoviral vectors via the adventitia was studied. METHODS: Replication-defective adenoviral vectors encoding a beta-galactosidase (beta-gal) gene (AdRSVnLacZ) or without a recombinant gene (AdNull) were infused into the lumen or the adventitia of rabbit carotid arteries. Two days after infusion of either AdRSVnLacZ (n = 8 adventitial, n = 8 luminal) or AdNull (n = 4 luminal), recombinant gene expression was quantitated by histochemistry (performed on tissue sections) and with a beta-gal activity assay (performed on vessel extracts). Inflammation caused by adenovirus infusion was assessed 14 days after infusion of either AdNull (n = 6) or vehicle (n = 6) into the carotid adventitia. Inflammation was assessed by means of examination of histologic sections for the presence of neointimal formation and infiltrating T cells and for the expression of markers of vascular cell activation (ICAM-1 and VCAM-1). To measure the systemic immune response to adventitial infusion of adenovirus, plasma samples (n = 3) were drawn 14 days after infusion of AdNull and assayed for neutralizing antibodies. RESULTS: Two days after luminal infusion of AdRSVnLacZ, approximately 30% of luminal endothelial cells expressed beta-gal. Similarly, 2 days after infusion of AdRSVnLacZ to the adventitia, approximately 30% of adventitial cells expressed beta-gal. beta-gal expression was present in the carotid adventitia, the internal jugular vein adventitia, and the vagus nerve perineurium. Elevated beta-gal activity (50- to 80-fold more than background; P <.05) was detected in extracts made from all AdRSVnLacZ-transduced arteries. The amount of recombinant protein expression per vessel did not differ significantly between vessels transduced via the adventitia (17.1 mU/mg total protein [range, 8.1 to 71.5]) and those transduced via a luminal approach (10.0 mU/mg total protein [range, 3.9 to 42.6]). Notably, adventitial delivery of AdNull did not cause neointimal formation. In addition, vascular inflammation in arteries transduced via the adventitia (ie, T-cell infiltrates and ICAM-1 expression) was confined to the adventitia, sparing both the intima and media. Antiadenoviral neutralizing antibodies were present in all rabbits after adventitial delivery of AdNull. CONCLUSION: Infusion of adenoviral vectors into the carotid artery adventitia achieves recombinant gene expression at a level equivalent to that achieved by means of intraluminal vector infusion. Because adventitial gene transfer can be performed by means of direct application during open surgical procedures, this technically simple procedure may be more clinically applicable than intraluminal delivery. Moreover, despite the generation of a systemic immune response, adventitial infusion had no detectable pathologic effects on the vascular intima or media. For these reasons, adventitial gene delivery may be a particularly useful experimental and clinical tool. (+info)
Antithrombotic efficacy of thrombin inhibitor L-374,087: intravenous activity in a primate model of venous thrombus extension and oral activity in a canine model of primary venous and coronary artery thrombosis.
The small molecule direct thrombin inhibitor L-374,087 was characterized across species in an in vitro activated partial thromboplastin clotting time (aPTT) assay and in vivo in rhesus monkey and dog thrombosis models. In vitro in rhesus, dog, and human plasma, L-374,087 concentrations eliciting 2-fold increases in aPTT were 0.25, 1.9, and 0.28 microM, respectively. In anesthetized rhesus monkeys, 300 microgram/kg bolus plus 12 microgram/kg/min and 300 microgram/kg bolus plus 30 microgram/kg/min L-374,087 i.v. infusions significantly reduced jugular vein thrombus extension, with both regimens limiting venous thrombus extension to 2-fold that of baseline thrombus mass compared with a 5-fold extension observed in the vehicle control group. Antithrombotic efficacy in the rhesus with the lower-dose regimen was achieved with 2.3- to 2.4-fold increases in aPTT and prothrombin time. In a conscious instrumented dog model of electrolytic vessel injury, the oral administration of two 10 mg/kg L-374,087 doses 12 h apart significantly reduced jugular vein thrombus mass, reduced the incidence of and delayed time to occlusive coronary artery thrombosis, and significantly reduced coronary artery thrombus mass and ensuing posterolateral myocardial infarct size. Antithrombotic efficacy in the dog was achieved with 1.6- to 2.0-fold increases in aPTT at 1 to 6 h after oral dosing with L-374,087. These results indicate significant antithrombotic efficacy against both venous and coronary arterial thrombosis with L-374,087 with only moderate elevations in aPTT or prothrombin time. The oral efficacy of L-374,087 characterizes this compound as a prototype for the further development of orally active direct thrombin inhibitors. (+info)
Pulmonary clearance of adrenomedullin is reduced during the late stage of sepsis.
Polymicrobial sepsis is characterized by an early, hyperdynamic phase followed by a late, hypodynamic phase. Although upregulation of adrenomedullin (ADM), a novel potent vasodilatory peptide, plays an important role in producing cardiovascular responses during the progression of sepsis, it remains unknown whether the clearance of this peptide is altered under such conditions. To determine this, male adult rats were subjected to sepsis by cecal ligation and puncture (CLP) followed by fluid resuscitation. At 5 h (i.e., the hyperdynamic phase of sepsis) or 20 h (the hypodynamic phase) after CLP, the animals were injected with 125I-labeled ADM through the jugular vein. Blood and tissue samples (including the lungs, kidneys, gastrointestinal tract, pancreas, spleen, mesentery, liver, brain, skeletal muscle, heart, and skin) were harvested 30 min after the injection and the radioactivity was determined. The results indicate that there were no significant alterations in tissue [125I]ADM distribution at 5 h after CLP compared to shams. At 20 h after CLP, however, there was a significant decrease in radioactivity in the lungs. In contrast, a significant increase of radioactivity was observed in all other organs except the liver and kidneys. The pulmonary distribution of [125I]ADM was found to be far greater than in any other organs tested, irrespective of the effect of sepsis. In separate groups of animals, injection of [125I]ADM into the left ventricle resulted in a significant decrease in radioactivity in the lungs of both sham and septic animals at 20 h after surgery. These results suggest that the lungs are the primary site of ADM clearance, which is significantly diminished during the late stage of sepsis. The decreased clearance of ADM by the lungs may play an important role in maintaining the sustained levels of plasma ADM under such conditions. (+info)
Effects of repeated jugular puncture on plasma cortisol concentrations in loose-housed dairy cows.
In three experiments, the effects of venipuncture on plasma cortisol concentrations were studied in loose-housed dairy cows. In Exp. 1, two blood samples were collected 18 min apart on three alternate days from 20 dairy cows for studying their adrenocortical response to a single venipuncture. To further evaluate the effect of cows anticipating venipuncture, in Exp. 2, 15 dairy cows were sequentially venipunctured once daily on 12 successive days in a randomized order in groups of five, starting 15 min apart. In Exp. 3, 10 primiparous cows were used on three alternate days to study habituation to serial sampling (i.e., collection of five blood samples by venipuncture, 15 min apart). In cows accustomed to handling, jugular puncture did not affect cortisol concentrations in plasma collected 18 min later. Average daily cortisol concentrations varied between 2.07 +/- .38 and 3.81 +/- .56 ng/mL in the first (t = 0) and between 1.43 +/- .15 and 2.61 +/- .72 ng/mL in the second (t = 18) blood samples. Likewise, when cows were sampled sequentially once a day, the order of sampling between and within groups did not influence (P > .05) plasma cortisol concentrations. In contrast, primiparous dairy cows that were less used to being handled showed an average increase in cortisol concentrations when five samples were collected by venipuncture 15 min apart. During successive sampling sessions, however, the cows did not decrease or increase plasma cortisol concentrations in response to repeated serial sampling at the group level (P > .05). Between individuals, the maximum effect of repeated venipuncture on cortisol concentrations (4.5 to 22.6 ng/mL), the time at which the effect reached its maximum (30 to 60 min), and the consistency of the response pattern over successive series varied largely. The results of this study show that in cows that were accustomed to handling and to being restrained, baseline cortisol concentrations can be measured in single blood samples that are collected by jugular puncture within 1 min after first approaching the cow. When successive blood samples need to be collected within 15 to 20 min, jugular puncture may induce an increase in cortisol concentration, which seems to depend on the handling experience of the animals and on individual differences. (+info)
Transjugular liver biopsy in the 1990s: a 2-year audit.
BACKGROUND: In view of the changing nature of transjugular liver biopsy, we performed an audit of the safety, adequacy and clinical impact of such biopsies in our centre over a 2-year period from 1995 to 1997. METHODS: One hundred and fifty-seven transjugular biopsies were carried out in 145 patients, with prothrombin time >5 s over control and/or platelet count <50 x 10(9)/L and/or gross ascites. RESULTS: Major complications were two (1.3%) capsular perforations, which were easily plugged with coils without sequelae. Biopsy sample was adequate for histological diagnosis in 90%, inadequate in 6% and technically unsuccessful in 4% of cases. Mean biopsy size was 14.8+/-7.7 (1-51) mm. Adequacy did not differ between cases with and without cirrhosis. Transjugular biopsy had a clinical impact (specific diagnosis or influence on patient's management) in 50% of acute liver disease, 62% of chronic liver disease and 87% of transplant patients (P<0.001). In chronic liver disease, it had a significantly greater clinical impact in cases trying to establish the stage rather than diagnosis (84% vs. 35%, P<0.001). CONCLUSIONS: Transjugular liver biopsy is a safe procedure for high-risk patients providing an adequate liver sample even in cirrhosis. It has a clinical impact in more than 80% of transplant patients and for staging chronic liver disease, but in only 50% (acute) or 35% (chronic) of liver disease when a diagnosis is sought. (+info)
Pharmacokinetic advantage of intra-arterial cyclosporin A delivery to vascularly isolated rabbit forelimb. I. Model development.
Effective antirejection therapy with minimal systemic morbidity is required if limb transplantation is to become a clinical reality. We investigated whether i.a. infusion of cyclosporin A (CSA) into the vascularly isolated rabbit forelimb will distribute drug homogeneously to the tissues and produce higher local drug levels than same-dose i.v. treatment, thereby improving the therapeutic index. CSA 4.0 mg/kg/day was infused continuously via osmotic minipump into either the right brachial artery (i.a. group) or jugular vein (i.v. group) of New Zealand rabbits. Ligation of all muscles at the right mid-arm level was performed in the i.a. group to eliminate collateral circulation and simulate allografting, while leaving bone and neurovasculature intact. On day 6, CSA concentrations were measured in skin, muscle, bone, and bone marrow samples taken from different compartments of the right and left forearms in the i.a. group and right forearm only in the i.v. group. There were no significant differences between compartmental CSA levels in all tissues examined on the locally treated, right side during i.a. infusion, indicating that drug streaming from the catheter tip is not occurring in our model. During i.a. infusion, mean CSA concentrations were 4- to 7-fold higher in the right limb than in the left limb in all four tissues examined. Tissue CSA levels in the left limb were equivalent to those achieved during i.v. infusion, but CSA concentrations in blood, kidney, and liver were higher during i.a. infusion. These favorable, preliminary, single-dose pharmacokinetic results warrant further investigation in our novel rabbit model. (+info)
Intimal thickening and hyperlipidemia in experimental primate vascular autografts.
Intimal thickening is a significant cause of late failure of aorto-coronary vein grafts. The microscopic appearance of this thickening has some similarities to the microscopic appearance of arterial atherosclerosis, and it has been suggested that hyperlipidemia may play a role in its pathogenesis. This study examines the morphology and lipid composition of autologous vein and artery grafts in normal and hyperlipidemic rhesus monkeys. Grafts were examined six months after insertion by light and electron microscopy and tissue lipids were determined quantitatively. Intimal thickening occurred in all grafts. Specific morphological and lipid compositional features of the grafts were influenced by the type of tissue used for grafting and the presence or absence of hyperlipidemia. However, the degree of intimal thickening per se could not be related to either of these two factors. It is concluded that surgical transplantation in this model provides the most powerful stimulus for intimal thickening and any additional effect on this process by hyperlipidemia is small. (+info)