Beta(3)-integrin-deficient mice but not P-selectin-deficient mice develop intimal hyperplasia after vascular injury: correlation with leukocyte recruitment to adherent platelets 1 hour after injury.

BACKGROUND: Intimal hyperplasia contributes to restenosis after percutaneous vascular interventions. Both beta(3)-integrins, alpha(V)beta(3) and alpha(IIb)beta(3) (glycoprotein IIb/IIIa), and leukocytes have been implicated in neointimal formation, based in part on the results obtained using antagonists to 1 or both receptors in animal models. METHODS AND RESULTS: The responses in wild-type mice, beta(3)-integrin-deficient mice, and P-selectin-deficient mice were studied in a model of transluminal endothelial injury of the femoral artery. At 4 weeks, beta(3)-integrin-deficient mice were not protected from developing intimal hyperplasia, whereas P-selectin-deficient mice were protected. Within 1 hour of injury, several layers of platelets deposited on the arteries of wild-type mice and a single layer of platelets deposited on the vessels of beta(3)-integrin-deficient mice; in both cases, leukocytes were recruited to the platelet layer. In P-selectin-deficient mice, the platelet layer was less compact and extended further into the lumen but did not recruit leukocytes. CONCLUSIONS: In a model of transluminal arterial injury, absence of early leukocyte recruitment and not deficiency of beta(3)-integrins correlated with a reduction in neointimal formation. Blockade of P-selectins may be an effective therapeutic strategy to decrease restenosis after percutaneous vascular interventions.

Elevating high-density lipoprotein cholesterol in apolipoprotein E-deficient mice remodels advanced atherosclerotic lesions by decreasing macrophage and increasing smooth muscle cell content.

BACKGROUND: HDL cholesterol levels are inversely correlated with coronary heart disease risk in humans, and in animal studies, HDL elevation decreases formation and progression of foam-cell lesions. The potential for HDL to affect preexisting advanced atherosclerotic lesions is not known. To approach this issue, we used a novel mouse aortic transplantation model. METHODS AND RESULTS: ApoE-deficient (EKO) mice were fed a Western-type diet for 6 months, and thoracic aortic segments containing advanced lesions replaced segments of the abdominal aorta of 4-month-old EKO syngeneic mice not expressing (plasma HDL cholesterol approximately 26 mg/dL) or expressing (HDL approximately 64 mg/dL) a human apoAI (hAI) transgene. Both types of recipients had comparable non-HDL cholesterol levels. Five months after transplantation, mice were killed and grafts analyzed. Compared with lesion area in pretransplant mice (0.14+/-0.04 mm(2), mean+/-SEM), there was progression in the EKO recipients (0.39+/-0.06 mm(2), P<0.01). Compared with EKO recipients, hAI/EKO recipients had retarded progression (0.24+/-0.04 mm(2), P<0.05). Immunostaining for CD68 and other macrophage-associated proteins, monocyte chemoattractant protein-1, acyl coenzyme A:cholesterol acyltransferase, and tissue factor, in lesions of pretransplant and EKO recipient mice showed abundant macrophages. In contrast, compared with any other group, lesional macrophage area in hAI/EKO mice decreased >80% (P<0.003), and smooth muscle cell content (alpha-actin staining) increased >300% (P<0.006). The decrease in macrophages and increase in smooth muscle cells was primarily in the superficial subendothelial layer. CONCLUSIONS: Increasing HDL cholesterol levels in EKO mice retards progression of advanced atherosclerotic lesions and remodels them to a more stable-appearing phenotype.

Inhibition of tissue factor reduces thrombus formation and intimal hyperplasia after porcine coronary angioplasty.

OBJECTIVES: We investigated the in vivo effects of tissue factor (TF) inhibition with recombinant tissue factor pathway inhibitor (rTFPI) on acute thrombus formation and intimal hyperplasia and the in vitro effects on smooth muscle cell migration and proliferation. BACKGROUND: Inhibition of TF with TFPI has been shown to reduce intimal hyperplasia in experimental models. However, its effects after coronary angioplasty and the cellular mechanisms involved have not been investigated. METHODS: Twenty-three swine underwent multivessel coronary angioplasty. Fifteen (n = 25 arteries) were euthanized at 72 h to assess thrombus formation and eight (n = 24 arteries) at 28 days to assess intimal hyperplasia. Animals in the 72-h time point received: 1) human rTFPI (0.5 mg bolus plus 25 microg/kg/min continuous infusion for 3 days) plus heparin (150 IU/kg intravenous bolus) plus acetyl salicylic acid (ASA) (325 mg/day); 2) rTFPI regimen plus ASA and 3) heparin (150 IU/kg intravenous bolus) plus ASA. RESULTS: On histology the control group had evidence of mural thrombus (area 0.8+/-0.4 mm2). Treatment with TFPI plus heparin abolished thrombus formation (mean area: 0.0+/-0.0 mm2, p < 0.05) but was associated with prolonged activated partial thromboplastin time and extravascular hemorrhage. Recombinant TFPI alone inhibited thrombosis without bleeding complications (mean area: 0.03+/-0.02 mm2, p < 0.05 vs. control). Animals in the 28-day time point received continuous intravenous infusion of rTFPI or control solution for 14 days. Tissue factor pathway inhibitor reduced neointimal formation with mean intimal area of 1.2+/-0.3 mm2 versus 3.2+/-0.4 mm2 in the control group; p < 0.01. Recombinant TFPI had no effect on human aortic smooth muscle cell growth but inhibited platelet-derived growth factor BB-induced migration. CONCLUSIONS: Inhibition of TF with rTFPI can prevent acute thrombosis and intimal hyperplasia after injury. Tissue factor plasma inhibitor may prove useful as an adjunct to intracoronary interventions.

Modulation of apoptosis, proliferation, and p27 expression in a porcine coronary angioplasty model.

Smooth muscle cell (SMC) proliferation is a prominent feature of intimal hyperplasia after percutaneous coronary interventions. p27 is a critical regulator of cell proliferation. Our aims were to analyze the time course of p27 expression, Ki67 proliferative index, and apoptosis after angioplasty in the porcine coronary artery. We also investigated the effects of rapamycin--an antiproliferative drug--on these events. The expression of p27 and Ki67, and apoptosis were determined in porcine coronary arteries harvested at timed intervals from 1 h to 28 days after angioplasty. A gradual increase in p27 expression was observed from 7 to 28 days. Ki67 expression peaked by 7-14 days after angioplasty. By 21-28 days, Ki67 expression decreased, while p27 reached maximal levels. An early apoptotic response was found by 6 h, followed by a gradual return to baseline. Rapamycin induced a reduction in Ki67 proliferative index (2 +/- 0.5%) and an increase in apoptosis (7 +/- 1%) versus untreated animals at the 28-day time point (5 +/- 1 and 1 +/- 0.5%, respectively; P < 0.05). In summary, coronary angioplasty induced a rapid apoptotic response, followed by a progressive increase in proliferation. Later on, as p27 expression increased in the vessel wall, cell proliferation decreased. Modulation of cell cycle progression may be a useful therapeutic approach in the treatment of intimal hyperplasia after angioplasty.

Comparative study of antithrombotic effect of a low molecular weight heparin and unfractionated heparin in an ex vivo model of deep arterial injury.

Thrombosis after plaque rupture triggers the onset of acute coronary events. The treatment of choice for patients with acute coronary syndromes is conventional unfractionated heparin. Low molecular weight heparin has recently been reported to be as effective and even safer than unfractionated heparin. In this study, the effects of the low molecular weight heparin reviparin and unfractionated heparin on thrombus formation were examined under dynamic conditions using an extracorporeal perfusion chamber in a porcine model. Thrombus formation was assessed by the deposition of porcine 123I-fibrin(ogen) and autologous 111In-platelets on porcine tunica media at high and low shear rates. Reviparin reduced the fibrinogen molecules deposited on injured vessels at high shear rates (252+/-80 molecules x 10(12)/cm2 for reviparine (200 U/kg/hour) vs. 624+/-70 x 10(12)/cm for unfractionated heparin (200 U/kg/hour) (p<0.05). At low shear rates, fibrinogen deposition was also significantly reduced by reviparin (130+/-15 molecules x 10(12)/cm2) compared to unfractionated heparin (192+/-40 x 10(12)/cm2 at 200 U/kg/hour; p<0.05). No change in platelet deposition was detected after heparin administration in either treatment group. In conclusion, the low molecular weight heparin reviparin has a higher antithrombotic potential than unfractionated heparin. Reviparin may have advantages over unfractionated heparin in treatment and prevention of acute coronary syndromes.

Encapsulation of packaging cell line results in successful retroviral-mediated transfer of a suicide gene in vivo in an experimental model of glioblastoma.

AIMS: Retroviral-mediated gene therapy has been proposed as a primary or adjuvant treatment for advanced cancer, because retroviruses selectively infect dividing cells. Efficacy of retroviral-mediated gene transfer, however, is limited in vivo. Although packaging cell lines can produce viral vectors continuously, such allo- or xenogeneic cells are normally rejected when used in vivo. Encapsulation using microporous membranes can protect the packaging cells from rejection. In this study, we used an encapsulated murine packaging cell line to test the effects of in situ delivery of a retrovirus bearing the herpes simplex virus thymidine kinase suicide gene in a rat model of orthotopic glioblastoma. MATERIALS AND METHODS: To test gene transfer in vitro, encapsulated murine psi2-VIK packaging cells were co-cultured with baby hamster kidney (BHK) cells, and the percentage of transfected BHK cells was determined. For in vivo experiments, orthotopic C6 glioblastomas were established in Wistar rats. Capsules containing psi2-VIK cells were stereotaxically implanted into these tumours and the animals were treated with ganciclovir (GCV). Tumours were harvested 14 days after initiation of GCV therapy for morphometric analysis. RESULTS: Encapsulation of psi2-VIK cells increased transfection rates of BHK target cells significantly in vitro compared to psi2-VIK conditioned medium (3 x 10(6) vs 2.3 x 10(4) cells; P<0.001). In vivo treatment with encapsulated packaging cells resulted in 3% to 5% of C6 tumour cells transduced and 45% of tumour volume replaced by necrosis after GCV (P<0.01 compared to controls). CONCLUSION: In this experimental model of glioblastoma, encapsulation of a xenogeneic packaging cell line increased half-life and transduction efficacy of retrovirus-mediated gene transfer and caused significant tumour necrosis.

Esophageal cancer as second primary tumor after breast cancer radiotherapy.

BACKGROUND: An increased risk of esophageal cancer has been reported in survivors of breast cancer treated with radiotherapy. This study further characterizes this association. METHODS: Through hospital databases, 118 patients (109 men, 9 women) treated for esophageal cancer between 1985 and 1993 were identified, of whom 37 had 60 synchronous or metachronous cancers. 5 women had primary esophageal cancer after having breast cancer, and are the subjects of this case-control study. RESULTS: All 5 women had been treated with radical mastectomy and adjuvant radiotherapy; none received chemotherapy. Their ages at the time of breast cancer ranged from 36 to 82 years; at esophageal cancer, 61 to 95 years. Time between radiotherapy and esophageal cancer varied from 13 to 31 years. All esophageal cancers were squamous cell carcinomas. Mean survival after esophageal cancer was 14.2 months. CONCLUSIONS: Radio-induced esophageal cancer can occur as a second primary cancer in women who survive at least 1 decade after mastectomy and adjuvant radiotherapy.

Current controversies in shock and resuscitation.

Many controversies and uncertainties surround resuscitation of hemorrhagic shock caused by vascular trauma. Whereas the basic pathophysiology is better understood, much remains to be learned about the many immunologic cascades that lead to problems beyond those of initial fluid resuscitation or operative hemostasis. Fluid therapy is on the verge of significant advances with substitute oxygen carriers, yet surgeons are still beset with questions of how much and what type of initial fluid to provide. Finally, the parameters chosen to guide therapy and the methods used to monitor patients present other interesting issues.

Radiation damage to the rectum and anus: pathophysiology, clinical features and surgical implications.

Radiation kills cancer cells by inducing various degrees of deoxyribonucleic acid fragmentation and disruption of intracellular membranes that lead to either immediate or delayed cell death. Although radiation can be effective in destroying cancer, its usefulness is limited by damage to normal tissues that surround the target tumour or those in the path of the radiation beam. The rectum and anus are damaged frequently during radiotherapy for abdominopelvic malignancy, including preresection therapy for rectal cancer. Such damage is often associated with lesions in the perineal skin, genitourinary tract, colon, and small intestine. Surgical intervention often is required for the most severe forms of these complications.

Visceral artery aneurysms: experience in a tertiary-care center.

Visceral artery aneurysms (VAAs) often rupture and cause serious morbidity or death. The purpose of this study was to identify conditions associated with VAA in a series of 30 patients treated at our institution from 1988 through 1998. Demographics, types of aneurysms, associated conditions, diagnoses, treatments, and outcomes were recorded and analyzed. Thirty patients (16 men and 14 women) with VAA were identified. The arteries involved were splenic (eight), renal (ten), hepatic (nine), hypogastric (one), celiac (one), and pancreaticoduodenal (one). Five of eight (63%) splenic artery aneurysms occurred in women; however, gender was not a factor in other aneurysmal groups. Splenic artery aneurysm also was associated with cirrhosis in four of the eight (50%) patients. Five of the nine (56%) hepatic artery aneurysms were associated with cirrhosis; two of these were pseudoaneurysms that occurred after liver transplantation. Five of ten (50%) renal artery aneurysms were associated with juxtarenal abdominal aortic aneurysms. Celiac and pancreaticoduodenal aneurysms were associated with gastrointestinal bleeding. Treatments included surgery (19), embolization (eight), and observation alone (three). These data demonstrate that association with other conditions varies according to subgroups of VAA. Despite advances in diagnosis and therapy the heterogeneity of VAA suggests that management must remain individualized.

Nontropical pyomyositis: analysis of eight patients in an urban center.

Nontropical pyomyositis is rare and usually associated with immunodeficiency virus (HIV) infection. This study assessed manifestations and response to treatment of nontropical pyomyositis in an area with a high prevalence of HIV seropositivity. We undertook a chart review of eight consecutive patients treated for pyomyositis - primary infection of skeletal muscles - from 1988 through 1998. All patients complained of myalgia; four (50%) had fever and six (75%) had leukocytosis. Muscles involved were deltoid, quadriceps, gluteus, and psoas. Six (75%) patients had identifiable risk factors for pyomyositis: HIV seropositivity (two), history of intravenous drug abuse (one), chronic paraplegia and malnutrition (one), diabetes and chronic renal failure (one), and leukemia (one). One patient had had streptococcal pharyngitis previously but was otherwise healthy; another, a 2-year-old, had no evidence of underlying disease. Staphylococcus aureus was the most common organism isolated (50%). Four patients were treated with incision and drainage plus antibiotics; the remaining four patients were treated with intravenous antibiotics only; all recovered. Nontropical pyomyositis, which is often associated with HIV seropositivity or chronic illness, has a favorable outcome. Treatment can be effective even without surgical intervention.

[Microvascular denudation of the femoral artery of the mouse as a model for restenosis]. / Mikrovaskuläre Denudation der Arteria femoralis der Maus--ein Restenosemodell für die Experimentelle Radiologie.

OBJECTIVE: To present technique and results of a microvascular denudation of the common femoral artery of the mouse as a model for inducing intimal hyperplasia in interventional radiology. MATERIALS AND METHODS: Under general anesthesia introduced by intraperitoneal injection, 14 B6129F1 hybrid mice (7 females and 7 males) at a mean age of 12.1 +/- 1.8 weeks and a mean weight of 28 +/- 2.8 grams had a groin incision of the vascular bundle directly distal to the inguinal ligament in preparation of placing a vascular clamp. Thereafter, the femoral artery was dissected distal to the origin of the epigastric artery and a loop prepared for a ligation proximal to the planned arteriotomy. Through an arteriotomy performed free-hand with a pair of micro scissors, a 0.010" (= 0.25 mm) guidewire was introduced into the vessel and advanced to the aortic bifurcation. The guide-wire was moved back and forth three times. The same procedure was performed on the other side as sham-operation, i.e., without introduction and passage of a guidewire. The resulting changes of the vessel wall were evaluated by histology and morphometry. RESULTS: Four weeks after intervention, the mean intima-to-media-ratio (IMR) was 1.80 +/- 0.28. A significant difference was observed between the sexes, with an IMR of 1.41 +/- 0.29 in females and an IMR of 2.24 +/- 0.45 in males (p = 0.0173). The neointima led to an overall luminal loss of 50.2% +/- 8.3% without significant sex difference (p = 0.09), but the average luminal loss was still more severe in females, amounting to 43.9% in comparison to 56.1% in males. This technique induces a significant neointima formation in a reproducible manner. The internal elastic membrane was preserved in all vessels. CONCLUSION: This technique is an excellent model to examine the differences between genetically modified mice to clarify the role of putative key molecules in the pathophysiology of restenosis.

Intra-abdominal pulmonary sequestration exhibiting congenital cystic adenomatoid malformation. Report of a case and review of the literature.

We describe the fifth case, to our knowledge, of an intra-abdominal pulmonary sequestration that histologically displayed the features of congenital cystic adenomatoid malformation (CCAM) type 2. This mass was found during routine prenatal ultrasound in an infant with no other congenital malformations. A literature search found 13 previously reported cases of CCAM in extralobar pulmonary sequestration (EPS), nine of which were thoracic and only four were intra-abdominal. An analysis of our case and the 13 previously reported cases shows that the clinical features of EPS containing CCAM type 2 do not differ significantly from those of EPS occurring alone. The presence of CCAM type 2 in our patient is consistent with previously reported cases. Extralobar pulmonary sequestrations located in the abdomen are rarely diagnosed prior to excision, and the presence of CCAM type 2 in this situation may further compound diagnostic difficulties. The morphologic features separating CCAM into three distinct types and the exclusive association of CCAM type 2 occurring in EPS are also discussed.

Peripheral arterial disease. Medical management in primary care practice.

Peripheral arterial disease (PAD) is caused by atherosclerosis, the leading cause of death and disability in patients age 50 and older. PAD progresses gradually and silently over many years, occluding the lumen of arteries that supply blood to the extremities. Symptoms of peripheral arterial insufficiency include intermittent claudication, rest pain, and impotence. Nonoperative management--including the control of risk factors such as hypertension, diabetes, hyperlipidemia, and smoking--is the most effective method to lower the risk of morbidity from PAD. Diagnostic technologies such as color duplex imaging, MRI, and MRA complement the clinical assessment of PAD and provide a stronger foundation for treatment decisions in the primary care setting.

Rapid oral endotracheal intubation with a fibre-optic scope in rabbits: a simple and reliable technique.

The orotracheal intubation of rabbits is complicated by their oropharyngeal anatomy. Numerous techniques to intubate rabbits have been described; however, these methods require specialized devices, tracheostomy, or are performed in a blind fashion. We describe a technique for the intubation of the rabbit under direct visualization with a standard, small-bore, fibre-optic laparoscope, which is both rapid and simple to perform.

Update on gene therapy for intimal hyperplasia.

Trauma to the vessel wall leads to smooth muscle cell (SMC) activation and eventual intimal hyperplasia. This process occurs in restenosis following balloon angioplasty, particularly with stent placement, occlusion of vascular bypasses, and arteriopathy of chronic allograft rejection. Genetic interventions affecting the cell cycle or early postinjury events have been successful in limiting SMC proliferation in vitro and in animal models. Gene therapy strategies have included the use of antisense oligonucleotides to block protein synthesis, transduced genes to cause cytotoxicity, and genetically engineered cells to decrease the response to injury. The clinical application of gene therapy in vascular diseases should follow the evolution of delivery systems that enable efficient local gene transfer to the arterial wall. (Tab. 1, Fig. 1, Ref. 30.)

Serial magnetic resonance imaging correlates with neurological outcome in an experimental model of spinal cord ischemia.

BACKGROUND: Paraplegia complicating surgical thoracoabdominal aneurysm (TAA) repair remains an unpredictable and poorly understood phenomenon. The ability to identify patients at increased risk of delayed paraplegia before the process becomes irreversible could allow early interventions to attenuate this risk. METHODS: In a rabbit model of infra-renal spinal cord ischemia, serial T2 weighted (T2W) magnetic resonance (MR) imaging was performed 2- and 8 h after the ischemic insult with changes correlated with clinical outcome. Using the axial T2W images, signal intensity measurements of the lateral horns of the spinal cord were acquired, both above (that is, thoracolumbar cord) and below (that is, lumbar cord) the renal arteries. This ratio (lumbar/thoracolumbar cord signal intensity) was evaluated and compared between groups. RESULTS: No changes were seen in the signal intensity of rabbits that remained neurologically intact. Rabbits with delayed paralysis showed a significant (P<0.01) decrease in signal intensity ratio at 2 h (1.13+/-0.03), while a significant (P<0.01) increase was noted in those rabbits with immediate persistent paralysis (1.43+/-0.04). There was a significant (P<0.01) increase in the signal intensity ratios at 2 h in the delayed paralysis group (1.55+/-0.14), with a further significant (P<0.01) increase at 8 h in the immediate persistent paralysis group (1.76+/-0.07). CONCLUSIONS: Findings on MR imaging can differentiate clinical outcomes in this experimental model of spinal cord ischemia. While further studies are required, MR could be useful in predicting which patients are at risk for delayed paraplegia after TAA repair.