Targeted delivery and improved therapeutic potential of catalase by chemical modification: combination with superoxide dismutase derivatives.
(49/5696)
Four types of bovine liver catalase (CAT) derivatives, succinylated (Suc-CAT), galactosylated (Gal-CAT), mannosylated (Man-CAT), and polyethylene glycol conjugate (PEG-CAT), were synthesized and their pharmacokinetics and therapeutic potential in a hepatic ischemia/reperfusion injury model were studied in mice. About 90% of the CAT enzymatic activity was retained after chemical modification. Biodistribution studies showed that 111indium (111In)-Gal-CAT accumulated selectively in the liver parenchymal cells as 111In-CAT, whereas an increased amount of 111In-Suc-CAT and 111In-Man-CAT was delivered to liver nonparenchymal cells. 111In-PEG-CAT exhibited prolonged retention in plasma. Pharmacokinetic analysis revealed that the hepatic uptake clearances of 111In-Suc-CAT, 111In-Gal-CAT, and 111In-Man-CAT were much greater than that of 111In-CAT, whereas that of 111In-PEG-CAT was very small. In the ischemia/reperfusion injury model, in which hepatic injury was induced by occlusion of the portal vein for 30 min followed by 1 h reperfusion, the elevation of plasma glutamic pyruvic transaminase and glutamic oxaloacetic transaminase levels was slightly inhibited by treatment with native CAT or Gal-CAT. PEG-CAT was less potent. In contrast, Suc-CAT and Man-CAT effectively suppressed the increase in plasma glutamic pyruvic transaminase and glutamic oxaloacetic transaminase. Coinjection of mannosylated superoxide dismutase marginally improved the inhibitory effects of CAT derivatives. These results demonstrate that targeted CAT delivery to liver nonparenchymal cells via chemical modification is a promising approach to prevent hepatic injuries caused by reactive oxygen species. The potential usefulness of combining of CAT and superoxide dismutase derivatives is also demonstrated. (+info)
Ischemia/reperfusion-induced IFN-gamma up-regulation: involvement of IL-12 and IL-18.
(50/5696)
Tissue injury as a consequence of ischemia followed by reperfusion is characterized by early as well as late signs of inflammation. The latter, among others, involves IFN-gamma-dependent up-regulation of MHC class I and II Ag expression. Employing a murine model of renal ischemia, we show that renal IL-18 mRNA up-regulation coincides with caspase-1 activation at day 1 following ischemia. IFN-gamma and IL-12 mRNA are subsequently up-regulated at day 6 following ischemia. Combined, but not separate, in vivo neutralization of the IFN-gamma inducing cytokines IL-12 and IL-18 reduces IFN-gamma-dependent MHC class I and II up-regulation to a similar extent as IFN-gamma neutralization, suggesting the involvement of functional IL-12, IL-18, and IFN-gamma protein. These results reveal a novel relationship between tissue injury of nonmicrobial origin and the induction of IL-12 as well as IL-18. The collaboration observed between endogenous IL-12 and IL-18 in the induction of IFN-gamma after renal ischemia/reperfusion, resembles the immune response to bacterial infections. (+info)
Combined arterial reconstruction and free tissue transfer for limb salvage.
(51/5696)
PURPOSE: Lower-extremity arterial anatomy that is insufficient for successful vein bypass grafting and major proximal foot wounds often lead to leg amputation in patients with severe ischemia. Free tissue transfer, which can provide limb salvage in these patients after arterial reconstruction, was studied. METHODS: During a 45-month period, 21 patients who otherwise would have undergone leg amputation were treated with arterial bypass by means of vein grafting and free tissue transfer. Ages of the patients ranged from 40 to 73 years (average, 59 years); 18 of the 21 patients had diabetes mellitus; and all patients except one were men. Arterial reconstruction was performed from the femoral (nine of 21 patients) or popliteal artery (12 of 21 patients) to the posterior tibial (eight patients), dorsalis pedis (five patients), peroneal (three patients), popliteal (one patient), or anterior tibial artery (one patient), or directly to the free flap (three patients). The tissue transferred included latissimus dorsi (five patients), rectus abdominus (five patients), omentum (five patients), gracilis (two patients), radial forearm flaps (three patients), and a scapular flap (one patient). Foot defects were debrided, including the appropriate toe or transmetatarsal amputation, covered with the transferred flap, and then split-thickness skin grafted. Arterial flow for all flaps was through the vein grafts, with direct arterial anastomosis and with venous outflow through adjacent tibial veins. RESULTS: All 21 procedures were successful initially, without operative mortality, but three failed within 4 weeks because of uncontrolled infection (two) or embolization from a remote site (one) and required below-knee amputation. Grafts remained patent in 18 procedures, and follow-up of this cohort ranged from 1 to 45 months (mean, 13.3 months). Two patients died, one after 4 months and one after 6 months, of unrelated illness; at the time of death, they had functioning grafts. The remaining 19 patients are alive. Of these, 15 have patent arterial grafts, all viable free flaps. Thus, limb salvage was accomplished in 18 of 21 (86%) patients who otherwise would have required below-knee amputation. CONCLUSION: Patients destined for leg amputation despite aggressive traditional arterial bypass grafting methods can achieve limb salvage with the additional technique of free tissue transfer. (+info)
Long-term results and outcomes of crossover axilloaxillary bypass grafting: A 24-year experience.
(52/5696)
OBJECTIVE: The outcome of crossover axilloaxillary bypass grafting in patients with stenosis or occlusion of the innominate or subclavian arteries was investigated. METHODS: The study was designed as a retrospective clinical study in a university hospital setting with 61 patients as the basis of the study. Fifty-eight patients (95.1%) had at least two risk factors or associated medical illnesses for atherosclerosis, and 35 patients (57.4%) had concomitant carotid artery stenosis that necessitated a staged procedure in 12 patients (19.7%). The patients underwent a total of 63 crossover axilloaxillary bypass grafting procedures. Demographics, risk factors and associated medical illnesses, preoperative symptoms and angiographic data, blood flow inversion in the vertebral artery, concomitant carotid artery disease, graft shape, caliber and material, and intraoperative and postoperative complications were studied to assess the specific influence in determining the outcome. RESULTS: One postoperative death (1.6%), four early graft thromboses (6.2%), and six minor complications (9. 8%) occurred. The overall mortality and morbidity rates were 1.6% and 16.1%, respectively. During the follow-up period (mean, 97.3 +/- 7.9 months), we observed five graft thromboses (8.3%). Primary and secondary patency rates at 5 and 10 years were 86.5% and 82.8% and 88.1% and 84.3%, respectively. Overall, two patients (3.3%) had recurrence of upper limb symptoms and none had recurrence of symptoms in the carotid or vertebrobasilar territory. The 5-year and 10-year symptom-free interval rates were 97.7% and 93.5%, respectively. Nine patients (15%) died of unrelated causes. The 5-year and 10-year survival rates were 93.2% and 67.3%, respectively. Multivariate analysis showed that no specific variables exerted an influence in the short-term and long-term results and the outcome. CONCLUSION: The optimal outcome of axilloaxillary bypass grafting supports its use as the most valuable surgical alternative to transthoracic anatomic reconstructions for innominate lesion, long stenosis of the subclavian artery, and short subclavian artery stenosis associated with ispilateral carotid artery lesions. (+info)
Implantable spinal cord stimulator to treat the ischemic manifestations of thromboangiitis obliterans (Buerger's disease).
(53/5696)
Thromboangiitis obliterans (Buerger's disease) is a segmental inflammatory vasculitis that involves the small-sized and medium-sized arteries, veins, and nerves. It is causally related to tobacco use. The diagnosis is usually made on the basis of the presence of distal arterial disease in individuals who smoke and in whom other disease entities have been excluded. The most effective treatment for Buerger's disease is smoking cessation. Without strict adherence to tobacco avoidance, disease progression is likely. Methods to control ischemic pain include medications, sympathectomy, or surgical revascularization. The effect of sympathectomy is unpredictable, and the chances of a successful revascularization procedure are rare because distal target vessels often are extensively diseased. Herein, we describe a patient whose condition did not respond to the usual conservative therapy but did respond dramatically to the implantation of a permanent spinal cord stimulator. Although these devices have been used for more than 20 years in various other peripheral arterial diseases, their use in Buerger's disease has been limited. (+info)
Neuroprotective effects of eliprodil in retinal excitotoxicity and ischemia.
(54/5696)
PURPOSE: To evaluate whether eliprodil (SL82.0715), a NR2B-selective N-methyl-D-aspartate (NMDA) antagonist, is protective of retina subjected to an excitotoxic or ischemic insult. METHODS: To evaluate protection against retinal excitotoxicity, eliprodil was administered intraperitoneally before and after the injection of NMDA (5 microl, 20 nmol) into the vitreous of rats. Integrity of the retina was assessed by counting cells in the retinal ganglion cell layer (GCL) and measuring choline acetyltransferase (ChAT) activity. In a subsequent experiment, total retinal ischemia, as measured by a cessation of electroretinographic (ERG) activity, was induced in anesthetized rabbits by elevating intraocular pressure above systolic blood pressure for 65 minutes. After ischemia, recovery of ERG activity was assessed at 24 and 48 hours in animals treated with vehicle or eliprodil (1.0-10.0 mg/kg). RESULTS: Intravitreal NMDA injection resulted in a dose-related decrease in cells of the GCL and in ChAT activity. Eliprodil administered intraperitoneally at 10 mg/kg completely prevented the loss of ChAT and the loss of cells in the GCL. Twenty-four hours after retinal ischemia, A and B waves of vehicle-treated animals were suppressed by 60% to 70%. Eliprodil administered intraperitoneally at 10 mg/kg ameliorated the A- and B-wave depression throughout the 48-hour experiment. CONCLUSIONS: Eliprodil is neuroprotective of retinae subjected to either an excitotoxic or ischemic challenge and may be useful for treating a variety of retinal and optic nerve head disorders. (+info)
Retinal ischemia-reperfusion injury attenuated by blocking of adhesion molecules of vascular endothelium.
(55/5696)
PURPOSE: To evaluate quantitatively the effects of blocking of adhesion molecules (P-selectin or intercellular adhesion molecule-1 [ICAM-1]) on leukocyte dynamics in the retinal microcirculation in vivo during ischemia-reperfusion injury and the therapeutic efficacy of the blocking of adhesion molecules on retinal ischemia-reperfusion injury. METHODS: Retinal ischemia was induced for 60 minutes in anesthetized pigmented rats by temporary ligation of the optic nerve. P-selectin or ICAM-1 monoclonal antibody (mAb) was administered at 5 minutes before reperfusion. At 4, 12, and 24 hours after onset of reperfusion, leukocyte behavior in the retinal microcirculation was evaluated in vivo with acridine orange digital fluorography. After 7 or 14 days of reperfusion, retinal damage was evaluated histologically. RESULTS: P-selectin mAb significantly inhibited leukocyte rolling along the major retinal veins after reperfusion. Subsequently, the number of accumulated leukocytes decreased in the P-selectin-inhibited rats. ICAM-1 mAb also inhibited leukocyte accumulation during the reperfusion period in a more substantial manner than P-selectin mAb. Histologic examination demonstrated the protective effect of the blocking of P-selectin or ICAM-1. In accordance with a reduction in leukocyte accumulation, the protective effect of mAb on retinal ischemia-reperfusion injury was more substantial in ICAM-1-inhibited rats. CONCLUSIONS: The present study demonstrates the inhibitory effect of P-selectin and ICAM-1 mAb on leukocyte accumulation and subsequent tissue injury during retinal ischemia-reperfusion injury. (+info)
Assessment of Thy-1 mRNA levels as an index of retinal ganglion cell damage.
(56/5696)
PURPOSE: Thy-1 is primarily, if not entirely, expressed by the ganglion cells within the retina. This knowledge was used to index ganglion cell death after ischemia and excitotoxicity by studying changes in Thy-1 mRNA levels. METHODS: Insults to the rat retina were delivered either by elevation of intraocular pressure for 60 minutes or by intravitreal injection of N-methyl-D-aspartate (NMDA). After a defined period, changes in Thy-1 immunoreactivity and mRNA levels of Thy-1 and NR1 (NMDA receptor subunit) were used to index ganglion cell sensitivity to damage. Opsin mRNA levels were used as an internal control because photoreceptors lack NMDA receptors. RESULTS: Retinal Thy-1 immunoreactivity, associated with the ganglion cell and inner plexiform layers, is reduced by ischemia or intravitreal injections of NMDA in a dose-dependent manner. Using a semi-quantitative polymerase chain reaction (reverse transcription-polymerase chain reaction) methodology, the levels of total retinal Thy-1 and NR1 mRNAs were shown to be dramatically reduced after both transient ischemia and intravitreal injection of NMDA. The effect of NMDA was found to be both time- and dose-dependent. In contrast, no change occurred in the levels of opsin mRNA unless high levels of NMDA (200 nmoles) were administered. CONCLUSIONS: Ischemia and NMDA-induced excitotoxicity caused retinal ganglion cell destruction, but the photoreceptors were unaffected. Measurement of total retinal Thy-1 mRNA levels provides a useful way of following ganglion cell death especially when combined with immunohistochemical localization of Thy-1. Additionally, the effect on other retinal cell types such as the photoreceptors can be followed in concert using this technique. (+info)