Implantation of stimulated homologous macrophages results in partial recovery of paraplegic rats

Postinjury recovery in most tissues requires an effective dialog with macrophages; however, in the mammalian central nervous system, this dialog may be restricted (possibly due to its immune-privileged status), which probably contributes to its regeneration failure. We circumvented this by implanting macrophages, pre-exposed ex vivo to peripheral nerve segments, into transected rat spinal cord. This stimulated tissue repair and partial recovery of motor function, manifested behaviorally by movement of hind limbs, plantar placement of the paws and weight support, and electrophysiologically by cortically evoked hind-limb muscle response. We substantiated these findings immunohistochemically by demonstrating continuity of labeled nerve fibers across the transected site, and by tracing descending fibers distally to it by anterograde labeling. In recovered rats, retransection of the cord above the primary transection site led to loss of recovery, indicating the involvement of long descending spinal tracts. Injection of macrophages into the site of injury is relatively non-invasive and, as the cells are autologous, it may be developed into a clinical therapy.

Ex-vivo gene therapy of human vascular bypass grafts with E2F decoy: the PREVENT single-centre, randomised, controlled trial

BACKGROUND

Cell-cycle blockade by ex-vivo gene therapy of experimental vein grafts inhibits the neointimal hyperplasia and subsequent accelerated atherosclerosis that lead to human bypass-graft failure. In a prospective, randomised, controlled trial, we investigated the safety and biological efficacy of intraoperative gene therapy in patients receiving bypass vein grafts.

METHODS

We studied gene therapy that uses decoy oligodeoxynucleotide, which binds and inactivates the pivotal cell-cycle transcription factor E2F. 41 patients were randomly assigned untreated (16), E2F-decoy-treated (17), or scrambled-oligodeoxynucleotide-treated (eight) human infrainguinal vein grafts. Oligonucleotide was delivered to grafts intraoperatively by ex-vivo pressure-mediated transfection. The primary endpoints were safety and inhibition of target cell-cycle regulatory genes and of DNA synthesis in the grafts. Analysis was by intention to treat.

FINDINGS

Mean transfection efficiency was 89.0% (SD 1.9). Proliferating-cell nuclear antigen and c-myc mRNA concentrations and bromodeoxyuridine incorporation were decreased in the EF2-decoy group by medians of 73% [IQR 53-84], 70% [50-79], and 74% [56-83], respectively) but not in the scrambled-oligodeoxynucleotide group (p<0.0001). Groups did not differ for postoperative complication rates. At 12 months, fewer graft occlusions, revisions, or critical stenoses were seen in the E2F-decoy group than in the untreated group (hazard ratio 0.34 [95% CI 0.12-0.99]).

INTERPRETATION

Intraoperative transfection of human bypass vein grafts with E2F-decoy oligodeoxynucleotide is safe, feasible, and can achieve sequence-specific inhibition of cell-cycle gene expression and DNA replication. Application of this genetic-engineering strategy may lower failure rates of human primary bypass vein grafting.

The association between cigarette smoking and ocular diseases

Tobacco smoke is composed of as many as 4,000 active compounds, most of them toxic on either acute or long-term exposure. Many of them are also poisonous to ocular tissues, affecting the eye mainly through ischemic or oxidative mechanisms. The list of ophthalmologic disorders associated with cigarette smoking continues to grow. Most chronic ocular diseases, with the possible exception of diabetic retinopathy and primary open-angle glaucoma, appear to be associated with smoking. Both cataract development and age-related macular degeneration, the leading causes of severe visual impairment and blindness, are directly accelerated by smoking. Other common ocular disorders, such as retinal ischemia, anterior ischemic optic neuropathy, and Graves ophthalmopathy, are also significantly linked to this harmful habit. Tobacco smoking is the direct cause of tobacco-alcohol amblyopia, a once common but now rare disease characterized by severe visual loss, which is probably a result of toxic optic nerve damage. Cigarette smoking is highly irritating to the conjunctival mucosa, also affecting the eyes of nonsmokers by passive exposure (secondhand smoking). The dangerous effects of smoking are transmitted through the placenta, and offspring of smoking mothers are prone to develop strabismus. Efforts should be directed toward augmenting the campaign against tobacco smoking by adding the increased risk of blindness to the better-known arguments against smoking. We should urge our patients to quit smoking, and we must make them keenly aware of the afflictions that can develop when smoke gets in our eyes.

Embolism from vertebral artery origin occlusive disease

We report 10 patients with severe occlusive disease of the vertebral artery (VA) origin in the neck with intra-arterial embolism to the posterior circulation. The VA lesions in seven patients were complete occlusions, and three patients had severe atherostenosis. All patients had strokes in the vertebrobasilar territory. The most frequent recipient sites of intra-arterial embolism were the intracranial VA-posterior inferior cerebellar artery region (8), and the distal basilar artery (BA) and its superior cerebellar and posterior cerebral artery branches (7). Two patients had pontine infarction due to BA embolism. The most common clinical signs were due to cerebellar infarction. Atherosclerotic disease of the VA origin has features in common with disease of the internal carotid artery origin. Both have similar risk factors and demography, and each can cause strokes by intracranial intra-arterial embolism.

Laser eye injuries

Laser instruments are used in many spheres of human activity, including medicine, industry, laboratory research, entertainment, and, notably, the military. This widespread use of lasers has resulted in many accidental injuries. Injuries are almost always retinal, because of the concentration of visible and near-infrared radiation on the retina. The retina is therefore the body tissue most vulnerable to laser radiation. The nature and severity of this type of retinal injury is determined by multiple laser-related and eye-related factors, the most important being the duration and amount of energy delivered and the retinal location of the lesion. The clinical course of significant retinal laser injuries is characterized by sudden loss of vision, often followed by marked improvement over a few weeks, and occasionally severe late complications. Medical and surgical treatment is limited. Laser devices hazardous to the human eye are currently in widespread use by armed forces. Furthermore, lasers may be employed specifically for visual incapacitation on future battlefields. Adherence to safety practices effectively prevents accidental laser-induced ocular injuries. However, there is no practical way to prevent injuries that are maliciously inflicted, as expected from laser weapons.

Effects of low-level energy lasers on the healing of full-thickness skin defects

Effects of low-level helium-neon laser radiation were compared on (1) wounds that closed primarily by contraction and (2) the breaking strength of straight-line incisions. Circular full-thickness skin defects in rabbits received dosages of 1.1 J/cm2 during a 30-min exposure every third day, and 2.2 J/cm2 during a 3-min exposure twice daily until wound closure. No significant differences in healing were observed between laser-treated wounds and untreated control wounds. Conversely, rat skin incisions exposed to 2.2 J/cm2 for 3 min twice daily for 14 days demonstrated a 55% increase in breaking strength over control rats (p less than 0.01); 28 days postoperatively, this difference in breaking strength diminished to a nonsignificant 16% increase over the control rats. Increasing the dosage to 4.5 J/cm2 yielded a nonsignificant 17% increase over the control rats 14 days postoperatively. HeNe laser irradiation of wounds increases certain aspects of healing in the early stages, but not to such a degree as to be clinically applicable. More detailed research is indicated to obtain optimal exposure levels necessary to accelerate wound healing significantly.

Inflammation after axonal injury has conflicting consequences for recovery of function: rescue of spared axons is impaired but regeneration is supported

Neural injury leads to tissue damage beyond that caused by the initial lesion, mainly as a result of a chain of autodestructive events triggered by the trauma. These events apparently include the activation of immune-derived cells and their products, as treatment with anti-inflammatory agents, such as corticosteroids, limits the damage and thus improves recovery. On the other hand, immune-derived substances, such as cytokines, are thought to play an important role in post-traumatic axonal regeneration. Thus, the need to reduce inflammation to limit the spread of damage appears to be in conflict with the need to permit inflammation to promote regeneration. Comprehension and resolution of this apparent conflict may lead to the development of treatment protocols aimed at rescuing axons spared by the initial injury, without hampering the potential regeneration of directly and indirectly injured axons. In this study, carried out on rats with crushed optic nerves, daily intraperitoneal injections of dexamethasone commencing prior to the injury significantly attenuated the injury-induced decrease in electrophysiological activity and reduced the area of tissue damage. On the other hand, dexamethasone treatment reduced the permissiveness of the injured nerves to neural adhesion and regrowth in vitro. This latter phenomenon was also observed in injured peripheral nerves. Results are discussed with respect to the possible establishment of an appropriate protocol for corticosteroid treatment of nerve injuries aimed at promoting neuronal rescue without compromising neuronal regeneration.

TGF-β signaling in liver and gastrointestinal cancers

Transforming Growth Factor-β (TGF-β) plays crucial and complex roles in liver and gastrointestinal cancers. These include a multitude of distinct functions, such as maintaining stem cell homeostasis, promoting fibrosis, immune modulating, as a tumor suppressor and paradoxically, as a tumor progressor. However, key mechanisms for the switches responsible for these distinct actions are poorly understood, and remain a challenge. The Cancer Genome Atlas (TCGA) analyses and genetically engineered mouse models now provide an integrated approach to dissect these multifaceted and context-dependent driving roles of the TGF-β pathway. In this review, we will discuss the molecular mechanisms of TGF-β signaling, focusing on colorectal, gastric, pancreatic, and liver cancers. Novel drugs targeting the TGF-β pathway have been developed over the last decade, and some have been proven effective in clinical trials. A better understanding of the TGF-β pathway may improve our ability to target it, thus providing more tools to the armamentarium against these deadly cancers.

Ocular injury by mustard gas

Sulfur mustard is a chemical warfare agent which was widely used during World War I and more recently in conflicts in the Middle East. This highly toxic compound causes severe dermal, gastrointestinal, respiratory and ocular injuries. It acts as an alkylating agent that induces structural changes and, hence, destruction of nucleic acids and proteins, impairing the cell's normal homeostasis and eventually causing its death. Sulfur mustard reacts rapidly with ocular tissues, and after a latent period of a few hours the patient starts suffering from severe eye pain, photophobia, excessive lacrimation and blindness. The injury, which is restricted to the anterior segment of the eye, may cause long-lasting incapacity in large numbers of casualties. Approximately 0.5% of the severely wounded victims may develop late complications which require prolonged ophthalmologic observation and therapy. In light of the ever-present threat of mustard chemical warfare against military and civilians, physicians worldwide should be aware of its grave effects and know how to care for its victims.

Intra-arterial fibrinolytic therapy. Efficacy of streptokinase vs urokinase

This study is a retrospective comparison of the results in 25 low-dose, intra-arterial streptokinase and 12 low-dose intra-arterial urokinase infusions for thromboembolic disease. Intra-arterial streptokinase was successful in 50% of infusions and was marked by significant abnormalities in the coagulation criteria. There was a high incidence of major and minor bleeding (48% overall), which could be attributed to systemic effects of the drug. Urokinase was successful in 100% of infusions, and showed no significant effects on systemic coagulation criteria. There were also fewer complications during urokinase infusion. The average pharmacy cost for a course of intra-arterial streptokinase was $165, while urokinase cost $1142. Despite the significant difference in expense, the increased efficacy and safety of urokinase make it the preferred agent for intra-arterial infusion. Theoretical reasons for the increased effectiveness of urokinase are discussed.

Infrainguinal arterial reconstruction with nonreversed greater saphenous vein

PURPOSE

This study was undertaken to examine the effectiveness and the possible advantages of infrainguinal arterial reconstruction with nonreversed greater saphenous vein (NRGSV) grafts. We reviewed the results achieved with 189 consecutive NRGSV bypass procedures from July 1, 1985, to August 31, 1995, and compared them with 568 consecutive in situ greater saphenous vein (INGSV) bypass procedures completed over the same interval.

METHODS

NRGSV bypass procedures were performed by selecting the optimum inflow and outflow vessels and then excising the best available appropriate-length segment of greater saphenous vein. The valves were lysed with a Mills valvulotome using gentle antegrade distention with an isotonic electrolyte solution containing heparin (1000 U/500 ml) and papaverine (60 mg/500 ml). The graft was then translocated to the inflow site, where the proximal and distal anastomoses were sequentially completed, followed by a completion arteriography.

RESULTS

Demographic and risk factor characteristics did not differ between patients who underwent NRGSV and those who underwent INGSV bypass. Compared with INGSV bypasses, NRGSV bypasses were more commonly secondary procedures (26% vs 8%; p < 0.001) and were more often performed for limb salvage indications (89% vs 68%; p < 0.001). NRGSV bypasses also had more distal inflow vessels (23% superficial femoral artery [SFA] and 28% popliteal artery [POP] vs 10% SFA and 1% POP; p < 0.001) and more distal outflow vessels (52% tibial and 22% pedal artery vs 47% tibial and 3% pedal artery; p < 0.001) than did INGSV bypasses. Despite the higher incidence of secondary bypass procedures and more distal outflow vessels in the NRGSV group, the overall results achieved at 5 years did not differ between the two groups. The 5-year primary patency rates were 65% +/- 5% for NRGSV and 72% +/- 3% for INGSV (p < 0.12), and the 5-year secondary patency rates were 74% +/- 5% and 82% +/- 2% (p < 0.08), respectively. Similarly, the 5-year limb salvage rate among bypass procedures performed for limb salvage indications did not differ for NRGSV (82% +/- 5%) and INGSV (90% +/- 2%; p < 0.06).

CONCLUSIONS

The application of the NRGSV bypass graft preserves the INGSV's main advantage of optimal size match between artery and vein at each anastomosis, but facilitaties the tailoring of the procedure to the patients anatomy and the completion of the bypass with the shortest, best-quality conduit available. Our application of the NRGSV in a more challenging series of bypass procedures produced equivalent results to those achieved in a concurrent series of INGSV bypass procedures.

Preferred strategies for secondary infrainguinal bypass: lessons learned from 300 consecutive reoperations

PURPOSE

To determine the optimal surgical strategies in reoperative infrainguinal bypass, we reviewed our results in 300 consecutive secondary bypasses in 251 patients operated on between Jan. 1, 1975, and Nov. 1, 1993.

METHODS

There were 168 men (67%) and 83 women (33%), with a mean age of 64.8 years and a typical distribution of risk factors including smoking (76.4%), diabetes (33.7%), and coronary artery disease (47.1%). The indications for surgery were limb-threatening ischemia in 83.5% and severe claudication in 16.5% of patients. The majority of conduits (n = 213) were autogenous vein and were composed of a single segment of greater saphenous vein in 121 bypasses (57%) and various alternative veins including composite, arm, and lesser saphenous vein in 92 bypasses (43%). Prosthetic conduits included 69 polytetrafluoroethylene, 16 umbilical vein, and two Dacron grafts.

RESULTS

There was one perioperative death (0.3%) and a 25% total morbidity rate including a 1.7% myocardial infarction rate. There was a 28.6% early (< 30 days) graft failure and 10.7% early amputation rate for prosthetic bypass grafts compared with 13.6% early graft failure and 5.6% early amputation rates for vein grafts. Autogenous vein bypasses had higher 5-year secondary patency rates than had prosthetic grafts (51.5% +/- 4.6% vs 27.4% +/- 6.1%, p < 0.001). Results with autogenous vein bypass improved significantly from the 1975 to 1984 to the 1985 to 1993 interval with 5-year secondary patency rates increasing from 38.3% +/- 6.9% to 59.1% +/- 5.8% (p = 0.017) and 5-year limb-salvage rates increasing from 40.4% +/- 7.6% to 72.4% +/- 6.6% (p < 0.001). Vein grafts to the popliteal and tibial outflow levels had equivalent long-term results. Vein grafts completed for claudication demonstrated results superior to those for limb salvage, with a 5-year secondary patency rate of 75.8% +/- 8.1% versus 52.3% +/- 7.9% (p = 0.048). Secondary autogenous vein bypass grafting performed after early primary graft failure (< 3 months) did particularly poorly, with only a 27.2% +/- 7.7% 4-year secondary patency rate. Greater saphenous veins tended to perform better than alternative vein bypasses, with a 5-year secondary patency rate of 68.5% +/- 6.0% compared with 48.3% +/- 10.5% (p = 0.09) and a 5-year limb-salvage rate of 77.8% +/- 7.4% versus 54.2% +/- 11.8% (p = 0.046).

CONCLUSIONS

When patients suffer a recurrence of limb-threatening ischemia at the time of infrainguinal graft failure, aggressive attempts at secondary revascularization with autogenous vein are warranted based on the low surgical morbidity and mortality rates and the improved patency and limb salvage rates that are currently attainable.

Tumor necrosis factor facilitates regeneration of injured central nervous system axons

The results of this study attribute to tumor necrosis factor (TNF) a role in regeneration of injured mammalian central nervous system (CNS) axons which grow into their own degenerating environment. This is the first time that a specific factor involved in axonal regeneration has been identified. The axonal environment is occupied mostly by glia cells, i.e., astrocytes and oligodendrocytes. Previous studies have shown that mature oligodendrocytes are inhibitory to axonal growth. Therefore, it seemed likely that application of a factor such as TNF, which has been shown to be cytotoxic to oligodendrocytes, would contribute to the creation of permissive conditions for axonal regeneration. In the present work, injured adult rabbit optic nerves were treated with human recombinant TNF (rhTNF). As a result, abundant newly growing axons (circa 9000, about 4% of the total estimated number of axons in an intact adult rabbit) were observed traversing the site of injury.

Recovery of visual response of injured adult rat optic nerves treated with transglutaminase

Failure of axons of the central nervous system in adult mammals to regenerate spontaneously after injury is attributed in part to inhibitory molecules associated with oligodendrocytes. Regeneration of central nervous system axons in fish is correlated with the presence of a transglutaminase. This enzyme dimerizes interleukin-2, and the product is cytotoxic to oligodendrocytes in vitro. Application of this nerve-derived transglutaminase to rat optic nerves, in which the injury had caused the loss of visual evoked potential response to light, promoted the recovery of that response within 6 weeks after injury. Transmission electron microscopy analysis revealed the concomitant appearance of axons in the distal stump of the optic nerve.

Intelligence, education, and myopia in males

We conducted a nationwide study of the relationship among refractive error, intelligence scores, and years of schooling in 157,748 males aged 17 to 19 years. We found a strong association of myopia with both intelligence and years of school attendance. The prevalence of myopia was found to be significantly higher in the more intelligent and more educated groups. By fitting models of logistic regressions, we worked out a formula expressing the relationship among the rate of myopia, years of schooling, and intelligence level. We found that years of schooling and intelligence weigh equally in the relationship with myopia.

Early operative intervention after thrombolytic therapy for primary subclavian vein thrombosis: an effective treatment approach

PURPOSE

Effective treatment of primary subclavian vein thrombosis focuses on restoration of venous patency, relief of intrinsic stenosis, and decompression of the thoracic inlet. The appropriate method and timing for surgery, however, have not been not well defined. We conducted a study to determine an acceptable treatment approach.

METHODS

A retrospective review evaluated 11 patients seen at our institution in an 8-year period. Seven patients were male and four were female, with an average age of 30 years (range 15 to 54 years). Two patients who had symptomatic stenosis without occlusion were omitted from the study. All patients with occlusion received urokinase therapy and underwent surgical decompression within 5 days of thrombolytic therapy. Five percutaneous transluminal angioplasties were attempted before operative intervention. Eleven decompressions were performed, including nine first-rib resections and two scalenectomies. Five operative venous procedures, consisting of thrombectomy with patch closure (n = 3) and bypass (n = 2), and seven venolysis procedures were performed. All patients received coumadin for 3 to 6 months after the operation.

RESULTS

Urokinase therapy established wide venous patency in nine of the 11 extremities treated, with the remaining two requiring thrombectomy for residual thrombus at the time of operation. One patient who underwent transluminal angioplasty before the operation had rethrombosis, and the remaining four showed no improvement in venous stenosis after the intervention. Eight of nine extremities treated by first-rib resection and one of two treated by scalenectomy were free of residual symptoms at follow-up.

CONCLUSIONS

Preoperative use of percutaneous balloon angioplasty is ineffective and should be avoided in this setting. Surgical intervention within days of thrombolysis obviates the need for interim oral anticoagulation and enables patients to return to normal activity sooner.

Brain edema after carotid surgery

The postoperative hyperperfusion syndrome describes an abrupt increase in blood flow with loss of autoregulation in surgically reperfused brain. Reports described a spectrum of findings, including severe headache, transient ischemia, seizures, and intracerebral hemorrhage. Hypertension is common after carotid artery surgery and often plays a role in the pathophysiology. We now report five patients with severe white matter edema after carotid surgery, a finding not previously included in the hyperperfusion syndrome. Five to 8 days after carotid surgery and after hospital discharge, each patient developed hypertension, headache, hemiparesis, seizures, and aphasia or neglect due to severe white matter edema ipsilateral to the carotid surgery. One patient had a small hemorrhage within the edematous area. Hypertension was severe in four patients and moderate in one. The carotid artery was patent by ultrasound or angiography in each patient after surgery. Transcranial Doppler showed increased velocities ipsilateral to surgery in two patients and bilaterally in one. Computed tomographic abnormalities and neurologic signs resolved within 3 weeks in four of the five patients treated with antihypertensives and anticonvulsants. The fifth patient died from herniation secondary to massive edema. Brain edema with focal neurologic signs should be included as a serious but potentially reversible component of the postoperative hyperperfusion syndrome.

Long term effect on IOP of a stainless steel glaucoma drainage implant (Ex-PRESS) in combined surgery with phacoemulsification

AIM

To evaluate the efficacy and safety of a stainless steel miniature glaucoma drainage device (Ex-PRESS R50) for the surgical treatment of primary open angle glaucoma (POAG) and cataract when combined with phacoemulsification.

METHODS

Clinical, prospective, multicentre, single treatment arm, non-randomised, non-masked study. The Ex-PRESS device was implanted at the limbus under a conjunctival flap. Phacoemulsification cataract extraction and in the bag IOL implantation were performed through clear cornea temporally.

PRIMARY OUTCOME

IOP change; secondary outcomes: side effects and VA changes.

RESULTS

26 eyes of 25 patients were implanted with the device. The mean (SD) follow up was 23.9 (10.4) months and the mean age was 75.1 (7.1) years. 17/26 eyes have more than 3 years of follow up. One case was discontinued because of device removal, one because of death, and three were lost to follow up.

EFFICACY

preoperative IOP was 21 (4) mm Hg; at 1, 2, and 3 years IOP was 15.3 (3.1) mm Hg (35% reduction), 16.6 (2.7) mm Hg (29% reduction), and 16 (2.6) mm Hg (22% reduction) respectively. Kaplan-Meyer determined overall success rate (IOP < or = 21 mm Hg at the last visit with or without medications) as 76.9%. The number of antiglaucoma medications was reduced by 95% at year 1. Only six patients (23%) were taking IOP lowering treatment at their last visit, five with one medication and one with two medications. Side effects: early postoperative complications were clinically mild and included six cases of hypotony (IOP <5 mm Hg), three cases of hyphaema (<2 mm) with no clinically significant further effects. Long term complications were two cases (7.7%) of device rotation (one treated by reposition) and three cases (11.5%) of conjunctival erosion at 2 and 3 years.

CONCLUSIONS

The Ex-PRESS implant, combined with phacoemulsification cataract extraction, is clinically safe and effective, maintaining in the long term a large reduction in IOP and in the number of antiglaucoma medications.

Impact of increasing comorbidity on infrainguinal reconstruction: a 20-year perspective

OBJECTIVE

To examine trends in patient and procedural variables and outcomes associated with autogenous lower extremity arterial reconstruction (LER) in a single center during a period of two decades.

SUMMARY BACKGROUND DATA

Surgical arterial reconstruction is of proven value in the therapy of patients with critical ischemia of the lower extremities. Changing demographics and increasing comorbidity are resulting in an increasing prevalence and associated complexity of peripheral vascular disease. The effect of these variables on the types and outcomes of surgical reconstructions is not known.

METHODS

The authors performed a retrospective analysis of all autogenous LER procedures performed at their institution from 1978 to 1997. Procedures were divided into 5-year intervals: group 1, 1978 to 1982; group 2, 1983 to 1987; group 3, 1988 to 1992; group 4, 1993 to 1997. Categorical parameters were compared using chi-square analysis; rates were computed by the life-table method and compared using Mantel-Cox log-rank analysis.

RESULTS

A total of 1,642 autogenous LER procedures were performed in 1,274 patients. A significant increase in age, female gender, diabetes mellitus, renal failure, and prior coronary artery bypass grafting was noted in group 4. Increased technical complexity in this group was reflected by a greater incidence of tissue necrosis as the indication for LER, the use of ectopic or composite vein, and more distal levels of outflow. The surgical death rate remained unchanged (2%) throughout. Patient survival, primary and secondary graft patency, and limb salvage at 5 years for the entire cohort were 70 +/- 2%, 63 +/- 2%, 73 +/- 1%, and 85 +/- 1%, respectively. Hospital length of stay was reduced 25% from a mean of 15.7 +/- 0.8 days in group 3 to 11.7 +/- 0.4 days in group 4.

CONCLUSION

In a tertiary practice setting, patients requiring LER present an increasingly complex medical and surgical challenge compared with the previous decade. Excellent outcomes may still be achieved by an aggressive approach relying on autogenous vein conduit.

Temporal parameters of low energy laser irradiation for optimal delay of post-traumatic degeneration of rat optic nerve

Compression injury of a central nerve results in its degeneration with irreversible loss of function due to the inability of the mammalian central nervous system (CNS) to regenerate. In contrast, the CNS of lower vertebrates has a high capacity to regenerate. Recently, low energy laser irradiation was shown to attenuate degeneration in injured CNS nerves. The optic nerves of rats were subjected to moderate crush, calibrated so that some electrophysiological activity was preserved. The nerves were then subjected to low energy laser irradiation (10.5 mW, 2 min daily) for various periods. The electrical activity of the nerves, distal to the site of injury, was determined by measuring the compound action potential at the termination of the experiment. Two weeks of irradiation begun immediately after injury and continued daily thereafter, resulted in a compound action potential which was significantly higher (mean +/- S.E.M. 1856 +/- 535 microV) than that of non-irradiated injured nerves (351 +/- 120 microV). The effect was temporary and subsided within a week. This two-week irradiation was slightly more effective than a treatment lasting one week (1406 +/- 225 microV) and was significantly more effective than 4 days of irradiation (960 +/- 133 microV). The number of treatments is therefore important. The time at which the treatment commences relative to the injury is also critical. Irradiation initiated two hours after the crush was about half as effective as immediate irradiation (810 +/- 42 microV). No apparent effect was evident when the laser was applied for the first time 5 h, or longer, after the crush.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of suprarenal cross-clamping on abdominal aortic aneurysm repair

Two hundred five patients who underwent elective abdominal aortic aneurysm repair were divided into two groups: those who underwent infrarenal cross-clamping alone (n = 166) and those who underwent suprarenal cross-clamping alone or combined with infrarenal cross-clamping (n = 39). Mortality was comparable between groups (1.2% for infrarenal cross-clamping vs 2.6% for suprarenal cross-clamping). Transient renal insufficiency was more frequent in the suprarenal group than in the infrarenal group (28% vs 10%), but dialysis rates (3% for suprarenal vs 2% for infrarenal) were similar. Cardiac morbidity was comparable between groups as well. Operating room data reflected the technical challenge of complex aneurysm repairs. The retroperitoneal approach was the preferred exposure in the suprarenal group since better access to the suprarenal aorta may be achieved with this technique. While abdominal aortic aneurysm repairs requiring suprarenal cross-clamping remain a technical challenge, the risks are not formidable and suprarenal cross-clamping should be considered when confronted with difficult periaortic dissection.

An assessment of the positive predictive value and cost-effectiveness of dipyridamole myocardial scintigraphy in patients undergoing vascular surgery

PURPOSE

The approach to cardiac risk stratification of patients undergoing vascular surgery continues to be controversial. The success of algorithms that use clinical risk factors to determine cardiac risk have been inconsistent. Dipyridamole myocardial scintigraphy (DMS) has been accepted as a sensitive, noninvasive approach to risk stratification with excellent negative predictive value. Low positive predictive value (PPV) of abnormal DMS scans is a shortcoming that contributes to extensive preoperative cardiac evaluation and intervention with associated morbidity, mortality, and cost in most patients who undergo uncomplicated vascular procedures, regardless of DMS results.

METHODS

Over 6 years, 237 patients underwent DMS before surgical management of infrarenal aortic aneurysm, aortoiliac, or infrainguinal occlusive disease. The value of multiple clinical factors and DMS were assessed retrospectively for the prediction of perioperative myocardial infarction (MI), heart-related death, or preoperative selection for myocardial revascularization. Only congestive heart failure and two or more reversible defects on DMS were statistically significant on logistic regression analysis.

RESULTS

The PPV of DMS was 19% for all patients with reversible defects, 12% for patients with one reversible defect, and 36.7% for patients with two or more reversible defects. The rates of cardiac death and MI were 1.3% and 5.9%, respectively. Perioperative echocardiography revealed unchanged postinfarction ejection fraction in most patients who experienced MI. Cost-effectiveness of DMS screening was evaluated.

CONCLUSIONS

The costs per MI and cardiac death averted suggest a decline in cost-effectiveness of screening with DMS over time, assuming improving cardioprotective strategies of patient care. Clinical risk factors were minimally useful in the prediction of perioperative MI, heart-related death, or need for myocardial revascularization. The PPV of DMS is low, and the majority of MIs may be clinically insignificant. The cost-effectiveness of cardiac screening with DMS may not be justifiable given current trends of health care reform.

Infrainguinal bypass grafting in patients with end-stage renal disease: improving outcomes?

OBJECTIVE

This study was undertaken to examine recent trends in the outcomes of patients with end-stage renal disease (ESRD) undergoing infrainguinal bypass grafting (IBG) with autogenous vein.

METHODS

A retrospective analysis of all IBGs performed on patients with ESRD at a single tertiary care institution during the interval 1993 to 1999 was undertaken. The comparison groups consisted of concurrent series of patients with elevated creatinine (creatinine level > 1.2 mg/dL) and patients with normal renal function undergoing IBG. Procedural variables, angiographic runoff scores, and extent of tissue necrosis at presentation were correlated with outcome. Categoric parameters were compared with chi(2) analysis; rates were computed with life-table analysis.

RESULTS

Of an overall cohort of 622 IBGs performed during this interval, 78 IBGs (12.5%) were performed on 60 patients with ESRD, with a perioperative mortality rate of 1.3% that was comparable to controls. All reconstructions in the ESRD cohort were for limb salvage indications. Four-year survival, primary, assisted primary, and secondary patency rates for the ESRD group were 51% +/- 9%, 60% +/- 11%, 86% +/- 5%, and 86% +/- 5%, respectively; these were not statistically different from the control groups. Limb salvage in the ESRD group was 77% +/- 6% at 4 years and was significantly less then either the elevated creatinine (92% +/- 4%; P <.02) or the normal renal function group (90% +/- 2%: P <.02). Of 16 amputations in the ESRD group, nine were performed in limbs with patent grafts. The only absolute predictor of limb loss despite a patent graft was the presence of a heel ulcer more than 4 cm in diameter. Age, runoff score of the International Society for Cardiovascular Surgery/Society for Vascular Surgery, isolated tibial bypass graft, and location of distal anastomosis were not predictive of hemodynamic failure.

CONCLUSIONS

Patients with ESRD constitute an increasing proportion of patients undergoing IBG in a tertiary care setting. Four-year survival, perioperative mortality, and graft patency rates are similar to patients with normal renal function and support an aggressive approach to this population. Major limb amputation despite a patent graft remains a problem of unique frequency in patients with ESRD. Adequate predictors of hemodynamic failure of IBG in this group do not exist, although a heel ulcer more than 4 cm may indicate an unsalvageable foot.

Regenerating fish optic nerves and a regeneration-like response in injured optic nerves of adult rabbits

Regeneration of fish optic nerve (representing regenerative central nervous system) was accompanied by increased activity of regeneration-triggering factors produced by nonneuronal cells. A graft of regenerating fish optic nerve, or a "wrap-around" implant containing medium conditioned by it, induced a response associated with regeneration in injured optic nerves of adult rabbits (representing a nonregenerative central nervous system). This response was manifested by an increase of general protein synthesis and of selective polypeptides in the retinas and by the ability of the retina to sprout in culture.