Elevation of plasma high-density lipoprotein concentration reduces interleukin-1-induced expression of E-selectin in an in vivo model of acute inflammation.

BACKGROUND: Although there is strong evidence that plasma HDL levels correlate inversely with the incidence of coronary artery disease, the precise mechanism(s) for the protective effect of HDLs remains unclear. We recently showed that HDLs inhibit endothelial cell expression of cytokine-induced leukocyte adhesion molecules in vitro. Our study therefore sought to test the hypothesis that elevating the level of circulating HDLs would inhibit endothelial cell activation in vivo. METHODS AND RESULTS: We used a porcine model of inflammation previously established in our laboratory, in which the level of vascular endothelial cell expression of E-selectin in interleukin (IL)-1alpha-induced skin lesions was measured by the uptake of a radiolabeled anti-E-selectin antibody (1.2B6). Porcine plasma HDL levels were elevated by use of a bolus injection of reconstituted discoidal HDL (recHDL). These particles resemble nascent HDL particles in shape and contain apolipoprotein A-I as the sole protein and soybean phosphatidylcholine as the sole phospholipid. We found that recHDLs inhibited the expression of IL-1alpha-induced E-selectin by porcine aortic endothelial cells in vitro, confirming that the inhibitory effect is conserved with synthetic HDLs and demonstrating that the phenomenon is not restricted to human endothelial cells. In vivo, elevating the circulating level of HDLs approximately 2-fold led to significant inhibition of basal and IL-1alpha-induced E-selectin expression by porcine microvascular endothelial cells. CONCLUSIONS: These observations demonstrate the potential anti-inflammatory action of HDLs and provide support for the further investigation of the mechanisms underlying the inhibitory effects of HDLs on endothelial cell activation.

Repetitive myocardial stunning in pigs is associated with the increased expression of inducible and constitutive nitric oxide synthases.

OBJECTIVES: Nitric oxide (NO) has complex effects on myocardial function particularly following ischaemia-reperfusion. The goal of this study was to examine the result of repetitive myocardial stunning on myocardial NO release and expression of inducible (iNOS) and constitutive (eNOS) NO synthases. METHODS AND RESULTS: Propofol anaesthetised pigs underwent ten, 2-min episodes of circumflex artery occlusion (n = 6) or acted as sham operated controls (n = 4). Measurements of segment shortening demonstrated a fall in function in the ischaemic territory to 52.5 +/- 7.3% (mean +/- S.E.M.) of baseline shortening 30 min after the stunning stimulus, recovering to 92 +/- 8.7% 5.5 h later. Function remained stable in sham controls. The change in venous-arterial [NO] between baseline and 6 h reperfusion was found to be significantly different between the two groups (0.2 +/- 0.7 in stunned vs. -4.3 +/- 1.6 microM in shams; P < 0.02). Western blotting and band optical density used to compare tissue from stunned territory (S), non-stunned territory (IC) and sham control animals (SC) demonstrated this was associated with an increase in the expression of both iNOS (S: 93 +/- 13.4, IC: 37 +/- 2.4 and SC: 25 +/- 4 [arbitrary units], P < 0.01 and P = 0.031) and eNOS (S: 104 +/- 7.4, IC; 62.5 +/- 7.4 and SC; 75.7 +/- 0.6, P < 0.03 and P < 0.01) in stunned myocardium. Immunocytochemistry localised iNOS reactivity to vascular smooth muscle cells and cardiomyocytes in stunned tissue and eNOS reactivity to endothelial cells. CONCLUSION: Recovery from repetitive myocardial stunning is associated with the increased expression of both iNOS and eNOS and would be compatible with a protective role for both these enzymes. This finding has possible relevance for both the late window of ischaemic preconditioning and myocardial hibernation.

Restenosis in human vein bypass grafts.

The restenosis rate in vein bypass grafts is higher than in native coronary arteries, and both the cascade of regulatory factors and the vessel reaction may be altered. In this study, vein bypass atherectomy specimens were classified as primary (n = 10) or restenotic (n = 12). Immunohistochemistry with 11 primary antibodies showed low levels of proliferation in both tissues and similar amounts of extracellular matrix components in both primary and restenotic specimens at the time points at which tissue was removed for clinical reasons. Inflammation appeared increased in restenotic specimens. Using in situ hybridization, transforming growth factor-beta1 messenger RNA was detected in both primary and restenotic tissue, with a trend to higher expression in restenosis (8.4 +/- 5.3 vs. 9.4 +/- 7.4 grains/nucleus) and further increased expression in multiple compared with single restenoses (15.1 +/- 6.1 vs. 5.6 +/- 5.1 grains/nucleus, P < 0.05). Hence, there were no great differences in cell proliferation or extracellular matrix formation between primary and restenosis vein graft tissue, in contrast to previously described findings in arterial tissue. This suggests that primary vein graft tissue is already in a chronic 'restenosis-like' state and subsequent injury creates minimal additional upregulation.

Neointimal growth can be influenced by local adventitial gene manipulation via a needle injection catheter.

Revascularization by percutaneous transluminal coronary angioplasty is limited in the long-term by restenosis, which is luminal renarrowing in the first 6 months after the procedure. Smooth muscle cell proliferation is thought to be an important factor in restenosis; this leads to neointima formation and arterial lumen narrowing. Local therapy delivered perivascularly may have an effect on events in the neointima and reduce restenosis. The effect of delivering expression vector plasmids for senescent cell-derived inhibitor SDI-1, which regulates cell proliferation, and its antisense, into the perivascular tissue of injured arteries was investigated in a porcine arterial injury model using a needle injection catheter. Transfection efficiency, biological effect and plasmid dissemination were evaluated in arterial and organ tissue sections between 2 days and 4 months. A limited number of adventitial, medial and neointimal cells were transfected up to 4 months. sdi gene transfer did not result in a change in neointima. Transfer of antisense sdi resulted in an increase in neointima after 3 weeks. No DNA plasmid was detected in control tissues. Liposomally-mediated adventitial local gene delivery is feasible and safe using the needle injection catheter in a porcine model. A limited number of cells was transfected, with expression of transfected genes up to 4 months after delivery. A transient biological effect with increased neointima was observed after delivery of the antisense sdi gene.

Accuracy of spiral computed tomography for identifying arterial and venous coronary graft patency.

Late outcome after coronary artery bypass grafting (CABG) mainly depends on the status of graft patency. The recent generation of spiral computed tomography (SCT) scanners may have potential in the long-term follow-up of CABG. In this study, graft patency in patients with internal mammary (IMA) and venous CABG was investigated using SCT and angiography. Forty-nine consecutive patients (age 61 +/- 8 years, 45 men) who had undergone CABG were examined by SCT and angiography 22 +/- 6 months after CABG. In total, 134 bypass grafts (42 IMA and 92 venous grafts) were analyzed. The angiographically determined patency rate of grafts was 86% for IMA (n = 36 of 42) and 74% for venous grafts (n = 68 of 92). By SCT, 32 IMA and 64 venous grafts were diagnosed correctly as patent. Sensitivity was 89% (IMA) and 94% (venous); overall sensitivity was 92%. None of the truly occluded venous grafts was diagnosed falsely patent by SCT (specificity 100%), whereas the specificity of IMA graft visualization was somewhat lower (88%, p = NS [overall 97%]). The accuracy for a patent graft was 88% (IMA) and 96% (venous CABG, p = NS). Compared with previous studies, these data suggest that SCT using one of the recent generation scanners (single scan time 0.75 second) is a highly accurate and relatively noninvasive approach for assessing not only saphenous vein graft patency, but also IMA graft patency. To date, this technique has only limited use in visualizing graft stenosis or distal anastomosis site patency.

Current biotechnological approaches to the prevention of restenosis.

No systemic pharmacological treatment has been convincingly shown to reduce the incidence of restenosis after angioplasty in patients. The lack of success of many pharmaceutical agents in reducing restenosis rates post-angioplasty and following stent implantation, as documented in dozens of clinical trials, has encouraged the development of new biotechnological approaches to the treatment of restenosis. Gene therapy and other agents, including antibodies, fusion toxins and ribozymes, have the potential to prevent some of the sequelae after arterial injury, particularly cell proliferation. Mechanical methods of preventing restenosis, for example sophisticated local drug delivery strategies and biodegradable stents using new materials, in combination with novel therapeutic agents or radiation, may also be of use.

Local photodynamic therapy reduces tissue hyperplasia in an experimental restenosis model.

Local photodynamic therapy may have potential in preventing myointimal hyperplasia after angioplasty. In this study, the effect of photodynamic therapy was evaluated in an experimental model of restenosis. Standardized unidirectional arterial injury with a directional atherectomy catheter was performed in porcine arteries. Animals were randomly allocated to four groups: group 1, unidirectional injury only; group 2, injury followed by local delivery of photosensitizer; group 3, injury followed by local exposure to monochromatic light; and group 4, where injury was followed by local drug delivery of photosensitizer and subsequent exposure to light (photodynamic therapy). Seven, 14 or 21 days after treatment, all experimental vessels were excised, fixed and processed for histology. An inflammatory and myoproliferative response was observed after injury in vessels from groups 1, 2 and 3. In group 4, after injury followed by photodynamic therapy, the myoproliferative response was significantly reduced. Thus, in this study, tissue hyperplasia after unidirectional injury was effectively suppressed by photodynamic therapy.

A new catheter for prolonged local drug application.

BACKGROUND: Local drug delivery using a new 5F catheter with six small needles is described. The needles can be extended laterally into vascular tissue for drug deposition. METHODS: A fluorescent indicator (Photofrin) was injected with a new local drug delivery device into porcine carotid arteries. The vessels were explanted 15, 30, 60 min and 14 days after local drug delivery. Vascular segments were analyzed using semi-quantitative measurement of fluorescence (calculated in relation to a standard, 100% representing the maximum fluorescence achieved by systemic intravenous application of Photofrin). RESULTS: Maximum fluorescence was found in adventitia (15 min: 374%; 30 min: 388%; 60 min: 251%). In intimal tissue, the detected fluorescence was 107% after 15 min, 294% after 30 min, and 25% after 60 min. Media fluorescence was lower (15 min: 151%, 30 min: 102%, 60 min: 55%). No systemic drug content was measured. Fourteen days after local drug delivery, 15% of maximal fluorescence was still found in media but no adverse tissue hyperplasia was observed. CONCLUSIONS: These experiments demonstrate that high-dose perivascular local drug delivery is feasible and allows prolonged and selective application of drugs in a vessel segment without side effects.

Doppler determined aortic acceleration after dipyridamole in the prediction of coronary artery disease.

Change in the acceleration of aortic blood flow with stress testing is reported to reflect the presence of myocardial ischaemia. We studied its clinical usefulness when compared with dipyridamole thallium scintigraphy in 101 patients, of whom 64 had coronary angiography. Maximum aortic acceleration increased after dipyridamole (P < 0.0001), although no correlation existed between the aortic acceleration and evidence of thallium perfusion abnormalities. For the patients who had angiography, the increase in aortic acceleration was similar for those with no significant coronary stenoses, single vessel or multi-vessel disease. Compared with coronary angiography, Doppler measurement of maximum aortic acceleration had a sensitivity of 92% and a specificity of 37% for the detection of coronary artery disease. When patients with previous myocardial infarction or left ventricular dysfunction were excluded, there was still no relationship between the maximum aortic acceleration and the presence of coronary artery disease. We conclude that changes in the acceleration of aortic blood flow after dipyridamole stressing do not predict the presence or severity of coronary artery disease as measured from perfusion defects at thallium scintigraphy or by coronary angiography. We have observed a wide variability of aortic maximum acceleration in the evaluation of myocardial ischaemia, which we feel introduces serious limitations to its use in routine clinical practice.

Non-invasive coronary bypass graft imaging after multivessel revascularisation.

Non-invasive imaging techniques for the detection of graft patency after multivessel coronary revascularisation may be useful for follow-up after surgery. Forty consecutive asymptomatic patients (38 men, age 59.9+/-1.3 years) who had undergone coronary bypass surgery with at least three grafts were examined by spiral computed tomography or magnetic resonance angiography 24.9+/-0.3 months after surgery, using conventional angiography as reference. In total, 133 grafts (37 internal mammary artery, 96 venous grafts) were analysed. Spiral computed tomography studies were performed with a subsecond scanner; for magnetic resonance angiography, a three-dimensional contrast-enhanced gradient echo technique with ultrashort echo time during breath holding was used. For spiral computed tomography, sensitivities were 76% (internal mammary artery) and 100% (venous graft). This was compared with 100% (internal mammary artery) and 92% (venous graft) assessed by magnetic resonance angiography (P=ns). The positive predictive values were 100% for internal mammary artery and venous graft (spiral computed tomography) and 100% (internal mammary artery), 92% for venous grafts studied by magnetic resonance angiography (P=ns). Both subsecond spiral computed tomography and contrast-enhanced magnetic resonance angiography are highly accurate and relatively non-invasive approaches of assessing coronary graft patency after multivessel revascularisation and have potential for follow-up assessment in the long term.

Preclinical and clinical experience in vascular gene therapy: advantages over conservative/standard therapy.

No systemic pharmacological treatment has been shown to convincingly reduce the incidence of restenosis after angioplasty or increase the formation of collaterals in ischemic tissue in patients. The lack of success of many pharmaceutical agents in reducing restenosis rates or in inducing angiogenesis post-angioplasty and following stent implantation has encouraged the development of new technological treatment approaches. Gene therapy is a novel strategy with the potential to prevent some of the sequelae after arterial injury, particularly cell proliferation, and to induce growth of new vessels or remodeling of pre-existing vessel branches, which may help patients with critical ischemia. Gene therapy strategies have the advantage of minimizing systemic side effects and may have a long-term effect as the encoded protein is released. Most clinical trials investigating gene therapy for vascular disease have been uncontrolled phase I and IIa trials. Gene therapy into vessels with the genes for growth factors has been demonstrated to be feasible and efficient. Local drug delivery devices have been used in combination with gene therapy in several trials to maximize safety and efficiency. Data from experimental animal work indicates that gene therapy may modify intimal hyperplasia after arterial injury, but there are few clinical trials on restenosis in patients. Preliminary clinical results show only limited success in altering restenosis rates. In vitro and experimental in vivo investigations into gene therapy for angiogenesis demonstrate increased formation of collaterals and functional improvement of limb ischemia. There is some evidence of increased collateral formation and clinical improvement in patients with critical limb ischemia. Results of placebo-controlled and double-blind trials of gene therapy for vascular disease are awaited.

Excessive arterial thrombus in spherocytosis. A case report.

Spherocytosis is the most common of the hereditary hemolytic anemias, with characteristically shaped erythrocytes. An unusually large amount of arterial thrombus was documented in a dissected artery after angioplasty in a patient with spherocytosis. It is hypothesized that the excessive arterial thrombus may have been linked to the spherocytosis.

Immune-complex allergic vasculitis in association with the development of transverse myelitis. A case report.

A severe vasculitis, probably therapy related, in a sixty-four-year-old man being treated for possible subacute bacterial endocarditis, was associated with the development of transverse myelitis. It is hypothesized that the vasculitis affected the small vessels to the spinal cord in the same way that systemic vasculitis can also cause a transverse myelitis.

Use of nuclear magnetic resonance imaging angiography to follow-up arterial remodeling in an animal model.

Appropriately sized arteries in small animals may be possible models for studying the remodeling process as occurs after arterial balloon injury in humans. Magnetic resonance imaging (MRI) is able to noninvasively image tissue in vivo. To date, small animal angiography models have mostly used research-dedicated instruments and resolution, which are not universally available. Experiments were carried out on a rat aorta model of remodeling in vivo (n=40). Arteries were injured by oversized balloon dilation; control arteries were uninjured. Angiography imaging was performed immediately before sacrifice with an unmodified clinical MRI unit, a 1.5 Tesla MR tomograph with a 20-cm-diameter coil. Longitudinal MRI pictures of the aorta and morphometry of tissue sections to measure luminal and arterial wall areas were analyzed with use of computer-assisted techniques. Comparison of dimensions demonstrated correlation between MRI and histology measurements of the lumen. MRI and morphometry showed a gradual increase in mean luminal area over 6 weeks following injury. The lumen increase correlated with total arterial area and thickness. In this rat aorta model, remodeling documented at histology was followed-up in vivo. The use of such clinical MRI scanners has potential to reduce animal numbers needed to follow-up the remodeling process after therapeutic intervention.

[Drug and instrumental therapeutic approaches for prevention of restenosis]. / Medikamentöse und instrumentelle Therapieansätze zur Restenoseprophylaxe.

In recent years, several of the shortcomings of coronary angioplasty have been successfully countered. With more effective measures of treating acute complications, better equipment and more experienced operators, there has been a subsequent expansion of the indications and the type of lesions suitable for angioplasty. In the long-term, however, the restenosis rate remains the limiting factor for the success of the procedure. To date, clinical studies using systemic therapy or alternative instrumental devices have not convincingly demonstrated a benefit in preventing restenosis. New devices have mostly been used to manage complications at angioplasty or to increase the type of lesions that can be tackled transluminally. This article will describe recent findings relating to the pathology of restenosis and then discuss a new therapeutic concept, local drug delivery to suppress restenosis. The aim of this method of drug application is to achieve a high local concentration of agents that inhibit restenosis, while avoiding systemic side-effects. Possible substances which could be utilized in this manner include conventional therapies such as platelet or calcium antagonists, or anti-thrombotic, anti-inflammatory or anti-proliferative treatments, and also novel agents such as gene therapy. The latter strategy might include inhibition of certain stimulatory factors that control restenosis, for example, through antisense oligonucleotides, or alternatively, augmentation of naturally occurring inhibitory factors, perhaps with expression vector plasmids and virus-mediated gene integration. The various ways in which these substances can be locally delivered to the arterial wall, together with results from initial experimental studies will be summarized. It is possible that eventually the combination of effective treatments with local drug delivery (LDD) may at last resolve the restenosis problem in patients.

Defrosting insulin: a case report.

We report a case where a patient used microwave radiation to thaw his frozen insulin resulting in marked deterioration in his diabetic control. The consequences of this action were examined using high-performance liquid chromatography.

Apparent massive tongue swelling. A complication of orotracheal intubation on the Intensive Care Unit.

The trachea of an 81-year-old woman was intubated with an orotracheal tube for emergency abdominal surgery and the tube was left in place for postoperative management on the Intensive Care Unit. After 36 h, she developed apparent massive tongue swelling. On closer examination, a normal sized tongue was found to be displayed by oedema of the floor of the mouth and submandibular space, secondary to purulent sialadenitis from right submandibular duct obstruction by the tracheal tube.