Unexplained excess of electronlike events from a 1-GeV neutrino beam.

The MiniBooNE Collaboration observes unexplained electronlike events in the reconstructed neutrino energy range from 200 to 475 MeV. With 6.46x10;{20} protons on target, 544 electronlike events are observed in this energy range, compared to an expectation of 415.2+/-43.4 events, corresponding to an excess of 128.8+/-20.4+/-38.3 events. The shape of the excess in several kinematic variables is consistent with being due to either nu_{e} and nu[over ]_{e} charged-current scattering or nu_{mu} neutral-current scattering with a photon in the final state. No significant excess of events is observed in the reconstructed neutrino energy range from 475 to 1250 MeV, where 408 events are observed compared to an expectation of 385.9+/-35.7 events.

Measurement of muon neutrino quasielastic scattering on carbon.

The observation of neutrino oscillations is clear evidence for physics beyond the standard model. To make precise measurements of this phenomenon, neutrino oscillation experiments, including MiniBooNE, require an accurate description of neutrino charged current quasielastic (CCQE) cross sections to predict signal samples. Using a high-statistics sample of nu_(mu) CCQE events, MiniBooNE finds that a simple Fermi gas model, with appropriate adjustments, accurately characterizes the CCQE events observed in a carbon-based detector. The extracted parameters include an effective axial mass, M_(A)(eff)=1.23+/-0.20 GeV, that describes the four-momentum dependence of the axial-vector form factor of the nucleon, and a Pauli-suppression parameter, kappa=1.019+/-0.011. Such a modified Fermi gas model may also be used by future accelerator-based experiments measuring neutrino oscillations on nuclear targets.

Search for electron neutrino appearance at the Delta m2 approximately 1 eV2 scale.

The MiniBooNE Collaboration reports first results of a search for nu e appearance in a nu mu beam. With two largely independent analyses, we observe no significant excess of events above the background for reconstructed neutrino energies above 475 MeV. The data are consistent with no oscillations within a two-neutrino appearance-only oscillation model.

Oculopharyngeal muscular dystrophy complicating airway management.

Oculopharyngeal muscular dystrophy (OPMD) is an uncommon autosomal dominant disorder characterized by late onset and slow progression. Complications of OPMD include ptosis and progressive dysphagia leading to eventual malnutrition and aspiration. We report a rare case of OPMD complicating mechanical ventilator management following emergent surgery. OPMD and the resulting dysphagia contributed to multiple intubations, tracheostomy, aspiration pneumonia, and a prolonged hospital course. Awareness of the possibility of OPMD in intubated patients with a history of dysphagia is crucial for avoidance of complications.

Exact sampling from nonattractive distributions using summary states.

Propp and Wilson's method of coupling from the past allows one to efficiently generate exact samples from attractive statistical distributions (e.g., the ferromagnetic Ising model). This method may be generalized to nonattractive distributions by the use of summary states, as first described by Huber. Using this method, we present exact samples from a frustrated antiferromagnetic triangular Ising model and the antiferromagnetic q=3 Potts model. We discuss the advantages and limitations of the method of summary states for practical sampling, paying particular attention to the slowing down of the algorithm at low temperature. In particular, we show that such slowing down can occur in the absence of a physical phase transition.

Comparison of two progressive treadmill tests in patients with peripheral arterial disease.

In a vascular rehabilitation program, 28% of our frail elderly patients are unable to be tested with traditional progressive exercise protocols at program entry due to the high (2.0 miles/h or 3.2 km/h) initial treadmill speeds. The purpose of this investigation was to compare a new progressive treadmill protocol which has a reduced initial speed (1.0 mile/h or 1.6 km/h) to an established protocol performed at 2.0 miles/h (3.2 km/h) to determine the comparability and reproducibility of the new protocol. Eleven patients with arterial claudication performed three symptom-limited exercise tests in random order. Two tests used the new protocol while the remaining trial used the established protocol. Claudication pain was measured using a 5-point scale. Oxygen consumption, heart rate, minute ventilation, respiratory exchange ratio and blood pressure at peak exercise were similar among the three trials. There were strong intraclass correlations for peak oxygen consumption (r = 0.97), onset of claudication (r = 0.96) and maximum walking time (r = 0.98) between the two trials using the new protocol. There was also a significant correlation between the new protocol and the established protocol for peak oxygen consumption (r = 0.90) and maximum walking time (r = 0.89). The new progressive treadmill protocol represents a valid, reliable protocol for patients with arterial claudication. This protocol may be useful for testing patients with a low functional capacity so that clinically appropriate exercise prescriptions can be established and the efficacy of treatments can be determined.

Components of an optimal exercise program for the treatment of patients with claudication.

Research in vascular exercise has demonstrated remarkable improvement in symptoms of claudication without more expensive and invasive interventions. During the past 5 years, 86 patients have graduated from The Brown University Supervised Vascular Exercise Program. Patients demonstrate a threefold improvement in maximum walking distance after 12 weeks of training. Information available on 22 patients at 1-year and 2-year follow-ups show walking distance is improved or maintained with continued training. Components of the program are presented in 3 phases. Phase 1 addresses the comprehensive nursing assessment, cardiac screening, and progressive treadmill testing. Phase II includes specific method of exercise prescription and educational needs of peripheral vascular disease patients. Phase III discusses the importance of maintenance and motivating patients to continue.

Critical pathways and cost-effective practice.

With increasing pressure by third-party payers and federal reimbursement systems to reduce health care expenditures, cost-effective means to care for the resource intensive vascular surgical population must be explored. The challenge of meeting these cost-saving priorities while maintaining or improving quality of care can result in conflicting demands on surgeons, particularly in academic practices. The adaptation of an industrial management tool-the critical pathway method-to health care delivery is an attempt to reduce length of stay and improve efficiency. Utilization of vascular nurse practitioners, concentration of vascular patients into a dedicated unit, reduction in angiography through more aggressive use of the vascular laboratory, and optimal use of rehabilitation units and skilled nursing facilities are important adjuncts to reduce length of stay without sacrificing quality of care. This report describes the critical pathway method as implemented in a university teaching hospital, and the integration of other modalities in the care of vascular patients that has reduced length of stay by as much as 40% for some vascular surgical procedures.

Value of a supervised exercise program for the therapy of arterial claudication.

PURPOSE: This study was performed to test the effectiveness of a formal supervised exercise program against a home-based exercise program for both walking ability and quality of life endpoints. METHODS: Patients with arterial claudication were randomized to either a 12-week supervised exercise program (SUPEX) with weekly lectures relating to peripheral vascular disease or to a home exercise group (HOMEX) who attended an identical lecture program and received weekly exercise instruction. The study population included 29 men and 26 women, with a mean age of 69.1 +/- 8.1 years. Forty-seven patients completed the 12-week program, 46 were available for testing at completion, and 38 for 6-month testing. Claudication pain time (CPT) and maximum walking time (MWT) on a progressive treadmill exercise test were assessed at baseline, program completion, and 6 months. The Medical Outcomes Study Short Form-36 (SF-36) was administered at these intervals to assess effects on quality of life. RESULTS: Each group improved (p < 0.001) in both CPT and MWT at the completion of the 12-week program, which was sustained at the 6-month follow-up. Increase in HOMEX CPT from baseline (3.6 +/- 2.73 minutes) to 6-month follow-up (6.6 +/- 3.17 minutes) was less than for the SUPEX group (3.8 +/- 2.74 to 11.2 +/- 4.02 minutes, respectively); similar results were obtained for MWT. At both completion and 6 months, there was a significant intergroup difference for CPT and MWT (p < 0.004) favoring SUPEX. For both groups, measures of health perception based on the SF-36 demonstrated improvement (p < 0.002) in Physical Function Subscale, Bodily Pain Subscale, and Physical Composite Score. There were no between-group differences on the subsets of the SF-36 at the three assessment intervals. CONCLUSIONS: Supervised exercise programs provide superior increased walking ability in the noninterventional therapy of arterial claudication, and both supervised and home based exercise therapy result in improved SF-36 functional measures. The lack of intergroup differences in these measures may be a result of the high degree of interaction with healthcare providers in the HOMEX group. Although a supervised program results in optimal walking benefits, a highly structured home-based program provides similar functional improvement and may be a satisfactory alternative for patients with lesser walking requirements.

Midaortic pseudoaneurysm complicating extensive endovascular stenting of aortic disease.

We report a case of successful surgical management of a potentially life-threatening complication of aortoiliac stent placement. A 59-year-old man who had Leriche syndrome underwent bilateral iliac artery and infrarenal aortic stent placement at another institution. His history was significant for retroperitoneal lymph node dissection at 19 years of age for testicular cancer. One week after stent placement, the patient was readmitted with abdominal pain, poor oral intake, and diffuse intermittent tenderness. Evaluation with computed tomographic scanning and endoscopy was unremarkable, and the patient was discharged. He was admitted to our institution 1 week later with persistent abdominal pain. A computed tomographic scan of the abdomen revealed a large pseudoaneurysm of the abdominal aorta. The patient underwent urgent exploration, and exclusion of his infrarenal aorta was achieved with aortobifemoral bypass grafting. After the operation, the patient's course was complicated by a large paraduodenal hematoma, which resulted in a gastric outlet obstruction, which was managed without operation. This case illustrates a potential life-threatening complication of extensive stent placement for aortoiliac occlusive disease. Injury to the abdominal aorta must be considered in a symptomatic patient after the placement of stents in the aortoiliac region, beyond the immediate periprocedural period.

Effects of radiofrequency glow discharge and oligopeptides on the attachment of human endothelial cells to polyurethane.

Activation of the surface of small diameter polyurethane vascular grafts using radiofrequency glow discharge (RFGD) and covalent linkage of cell attachment oligopeptides may improve graft patency. The effects of RFGD treatment were investigated on a polyurethane-polydimethylsiloxane (PU-PDMS) copolymer (Cardiothane-51; Kontron Cardiovascular, Inc., Everett, MA) membrane fabricated using the spray, phase-inversion technique. RFGD using H2O vapor was used to functionalize the membrane surface, reacted with 1',1 carbonyldiimidazole and covalently bound with oligopeptides (RGDS, RGES). Membranes not subjected to RFGD, either unmodified or with adsorbed fibronectin (Fn), vitro-nectin (Vn), RGDS, RGDV, and RGES, were used as controls. RFGD treated membrane surfaces were evaluated using electron spectroscopy for chemical analysis, which demonstrated a qualitative increase in nitrogen and silicon compared to unmodified PU-PDMS. Indirect confirmation of surface hydroxylation was provided by metallization with palladium and nickel, demonstrating uniform metallization of RFGD treated PU-PDMS surfaces. Human umbilical vein endothelial cells (HUVEC) were seeded at a density of 10(4) cells/cm2 and cell attachment assessed at 3 hr, 24 hr, and 7 days. Untreated PU-PDMS and membrane with adsorbed oligopeptides demonstrated poor HUVEC attachment at all intervals. Adsorbed Fn and Vn had significantly better early cell attachment and growth (p < 0.01). RFGD improved initial attachment and growth over non-RFGD treated controls (p < 0.01) for RGDS bound membranes, which performed as well as Fn controls (N.S.). PU-PDMS membranes can be modified using RFGD to covalently link oligopeptides. RFGD treatment alone, or with covalent linkage of cell attachment oligopeptides, improves HUVEC attachment and growth in a static environment.

Prevalence of unsuspected abdominal aortic aneurysms in male veterans.

Abdominal aortic aneurysms (AAA) are potentially lethal arterial lesions that are best managed by elective surgical repair. However, asymptomatic AAAs may go undetected on routine physical examination or patients with such lesions may not consult a physician. To determine the prevalence of asymptomatic AAAs in a high-risk population, we retrospectively reviewed all abdominal CT scans on veterans > 50 years of age that had been ordered for indications other than aneurysmal disease during a recent 10-month period. Of the 111 patients studied, 15 (13.5%) had suprarenal and/or infrarenal AAAs (one patient had both). Patients with AAAs were significantly older (p = 0.0001) and were heavier tobacco users (p = 0.003). For patients > 60 years of age with peripheral vascular occlusive disease and a history of tobacco use, there was a 29.2% prevalence for AAA compared with 0% in those without any of these risk factors (p = 0.04). There was a very definite trend suggesting that patients with peripheral vascular disease (p = 0.06) were more likely to have an AAA. Because of the high prevalence of AAAs found in this population we then conducted a prospective study over a 24-month period during which patients > 60 years of age with known peripheral vascular disease and a history of smoking who presented to the vascular laboratory for evaluation of problems not related to AAA were asked to undergo an abdominal CT scan. Fifty-six volunteers agreed to participate in the study. Seven patients had AAAs and one patient had an isolated iliac aneurysm, for a 14.3% overall prevalence of aneurysms.2+ d

The ischemic window: a method for the objective quantitation of the training effect in exercise therapy for intermittent claudication.

Twenty-two patients with intermittent claudication were prospectively enrolled in a 12-week program of supervised, graded treadmill exercise therapy. Severity and distribution of arterial occlusive disease were ascertained by noninvasive determination of segmental lower extremity blood pressures and waveforms. No attempt was made to modify risk factors for atherosclerotic occlusive disease. The exercise-induced reduction of the ankle pressure and its recovery were recorded over time, and the area under this curve, the "ischemic window," represents the severity of the ischemic deficit. Absolute systolic ankle pressure, ankle-brachial index, maximum walking time, claudication pain time, and the ischemic window were measured before and after exercise training in all subjects. Maximum walking time and claudication pain time increased 659% and 846%, respectively, among the 19 patients completing the 12-week program (p = 0.001; p = 0.0002). These patients underwent a mean reduction of 58.7% in the ischemic window after a standardized workload (p less than 0.05), and this correlated with the degree of symptomatic improvement. Absolute ankle pressure and ankle-brachial index were unchanged after exercise training. This study confirms the utility of supervised exercise therapy in the treatment of intermittent claudication. The ischemic window is a useful method for quantifying the ischemic deficit produced by exercise and provides a reproducible means of documenting functional improvement in patients undergoing exercise training.

Prevalence of hemodynamically significant stenosis of the carotid artery in an asymptomatic veteran population.

The results of previous studies have suggested that significant stenosis of the carotid artery occurs in less than 6 per cent of asymptomatic patients. However, some populations studied were not representative of those seen by most vascular surgeons. Accordingly, we examined two cohorts of patients at the Veterans Administration Medical Center using Duplex scanning. There were 153 volunteers in group 1, all more than 50 years of age, who were being treated at our outpatient department for nonvascular problems. There were 116 patients of similar age in group 2 but who were known to have significant arterial occlusive disease of the lower extremity. The majority of patients were men with a mean age of 64.4 years. Risk factors in the total population included hypertension, diabetes mellitus, coronary arterial disease, peripheral vascular disease and smoking. Over-all, significant (greater than 50 per cent diameter) stenosis of the carotid artery was discovered in 25 of 269 patients. The prevalence for those in group 1 was 6.5 per cent versus 12.9 per cent for those in group 2 (p = 0.058). The prevalence in patients with cardiac disease was 15.2 per cent compared with 6.8 per cent in those without cardiac disease (p = 0.032). Smoking was associated with a 10.6 per cent rate of significant disease compared with a 2.3 per cent rate in nonsmokers (p = 0.065). Hypertension and diabetes were not significant risk factors. Significant stenosis of the carotid artery was found in seven of 40 patients in whom coronary arterial disease, peripheral vascular disease and smoking were all present.(ABSTRACT TRUNCATED AT 250 WORDS)

Repositioning of partially dislodged Greenfield filters from the right atrium by use of a tip deflection wire.

Dislodgement of a Greenfield filter in the right atrium is one of the most serious complications of this procedure. Retrieval of such a misplaced filter may require surgical intervention by means of cardiopulmonary bypass surgery, which is very hazardous in these often severely ill patients. We describe two cases in which the filter became partially dislodged from its carrier in the right atrium. We were able to successfully reposition the filter by using a tip deflection wire, thereby obviating the need for an open cardiac procedure.

Preferential use of EPTFE for above-knee femoropopliteal bypass grafts.

We have used polytetrafluoroethylene preferentially for bypasses to the above-knee popliteal artery since 1979. Since this approach has recently been challenged, we reviewed our experience with 138 grafts in 128 patients. The majority (74%) of patients were male with a mean age of 63.2 years. Risk factors included: smoking (85%), hypertension (55%), diabetes mellitus (45%), and coronary artery disease (41%). The indications for operation were disabling claudication (18%), rest pain (42%), gangrene/tissue loss (33%), and miscellaneous (7%). Perioperative (30 day) mortality was 3% and morbidity (excluding amputation or graft failure) was 5%. Patients were followed for up to eight years with a mean follow-up of 22.1 months. Grafts which remained patent, but did not prevent major amputation, were classified as "failed". Primary patency was 75% at one year and 54% at five years. Limb salvage was 88% at one year and 70% at five years. Risk factors, indication for operation and arteriographic runoff had no statistically significant impact on short- or long-term patency. However, bypass grafts to isolated popliteal segments had a significantly (p = 0.025) increased perioperative failure rate compared to all other grafts. Our data support the continued use of polytetrafluoroethylene for above-knee femoropopliteal bypass except perhaps in patients who require grafting to an isolated popliteal segment where higher early failure rates were seen.

Protection against postischemic spinal cord injury using a new 21-aminosteroid.

Ischemic spinal cord injury following repair of the thoracoabdominal aorta is an unpredictable and devastating complication. Recently, a new class of agents has been developed, the 21-aminosteroids, which have been demonstrated to reduce ischemic neurologic injury in several animal models. We performed this study to determine if the 21-aminosteroid U-74006F exerted a protective effect in a rabbit model of spinal cord ischemia. Nineteen New Zealand rabbits were anesthetized and then subjected to 25 min of temporary infrarenal aortic occlusion. Nine rabbits were given 3.0 mg/kg U-74006F iv 10 min prior to clamping the aorta, followed by 0.75 mg/kg every hour for 6 hr beginning 1 hr after the clamp was removed. Ten rabbits received equivalent doses of an aqueous buffered vehicle. The rabbits were neurologically graded upon awakening and then daily using the following scale: grade 0 = complete paralysis, grade 1 = partial deficit, grade 2 = normal. In the U-74006F-treated group, five animals were normal, one had a partial deficit, and three were paraplegic. In the vehicle group, only one animal was normal and nine were paraplegic. The difference between the mean neurologic grading scores of the two groups was statistically significant (P = 0.013). It is believed that U-74006F acts at the cell membrane level during reperfusion by inhibiting lipid peroxidation and lipid hydrolysis. Our data suggest that this agent may significantly reduce the incidence of postischemic spinal cord injury following temporary aortic occlusion.

Is the continued use of ocular pneumoplethysmography necessary for the diagnosis of cerebrovascular disease?

The combination of duplex scanning and ocular pneumoplethysmography (OPG) has been used by many vascular laboratories for noninvasive evaluation of the carotid arteries. This study was undertaken to determine if OPG significantly improved the accuracy of duplex scanning alone. Three hundred eighty-five carotid arteries were studied in 190 patients with angiograms, duplex scans, or OPG. A total of 329 carotid arteries were examined with all three modalities. Three different criteria were used to interpret the OPG results, one each intended to deliver a high sensitivity, specificity, and overall accuracy. Depending on the criteria used, sensitivity of OPG alone for detecting hemodynamically significant (greater than 50%) stenosis ranged from 53% to 83%, with a specificity of 59% to 94%. Duplex scanning alone had a sensitivity of 87% and a specificity of 90% for similar lesions. If patients with only intracranial arterial stenosis were excluded, the sensitivity of the duplex scan rose to 91%. The addition of OPG to the duplex scan slightly increased sensitivity (range 91% to 95%; difference not significant) but significantly decreased specificity (range 56% to 84%; p less than 0.005). For detecting stenoses greater than 80%, the duplex scan alone had a sensitivity of 90% and a specificity of 88%. The addition of OPG to duplex scanning slightly increased sensitivity for these high-grade lesions but significantly decreased specificity (p less than 0.001) and overall accuracy. These results were unaffected by the presence or absence of intracranial disease. Because the addition of OPG to duplex scanning reduces specificity and accuracy without any significant increase in sensitivity, we no longer use it as part of our routine noninvasive cerebrovascular examination.