Mechanism for Collective Energy Transfer from Neutral Beam-Injected Ions to Fusion-Born Alpha Particles on Cyclotron Timescales in a Plasma.

Helium ash alpha particles at ∼100 keV in magnetically confined fusion plasmas may have the same Larmor radius, as well as cyclotron frequency, as the energetic beam-injected deuterons that heat the plasma. While the velocity-space distribution of the helium ash is monotonically decreasing, that of the energetic deuterons is a delta function in the edge plasma. Here we identify, by means of first principles particle-in-cell computations, a new physical process by which Larmor radius matching enables collective gyroresonant energy transfer between these two colocated minority energetic ion populations, embedded in majority thermal plasma. This newly identified nonlinear phenomenon rests on similar underlying physics to widely observed ion cyclotron emission from suprathermal minority ion populations.

Stimulated Emission of Fast Alfvén Waves within Magnetically Confined Fusion Plasmas.

A fast Alfvén wave with a finite amplitude is shown to grow by a stimulated emission process that we propose for exploitation in toroidal magnetically confined fusion plasmas. Stimulated emission occurs while the wave propagates inward through the outer midplane plasma, where a population inversion of the energy distribution of fusion-born ions is observed to arise naturally. Fully nonlinear first-principles simulations, which self-consistently evolve particles and fields under the Maxwell-Lorentz system, demonstrate this novel "α-particle channeling" scenario for the first time.

Quantifying Fusion Born Ion Populations in Magnetically Confined Plasmas using Ion Cyclotron Emission.

Ion cyclotron emission (ICE) offers a unique promise as a diagnostic of the fusion born alpha-particle population in magnetically confined plasmas. Pioneering observations from JET and TFTR found that ICE intensity P_{ICE} scales approximately linearly with the measured neutron flux from fusion reactions, and with the inferred concentration, n_{α}/n_{i}, of fusion born alpha particles confined within the plasma. We present fully nonlinear self-consistent kinetic simulations that reproduce this scaling for the first time. This resolves a long-standing question in the physics of fusion alpha-particle confinement and stability in magnetic confinement fusion plasmas. It confirms the magnetoacoustic cyclotron instability as the likely emission mechanism and greatly strengthens the basis for diagnostic exploitation of ICE in future burning plasmas.

Electron current drive by fusion-product-excited lower hybrid drift instability.

We present first principles simulations of the direct collisionless coupling of the free energy of fusion-born ions into electron current in a magnetically confined fusion plasma. These simulations demonstrate, for the first time, a key building block of some "alpha channeling" scenarios for tokamak experiments. Spontaneously excited obliquely propagating waves in the lower hybrid frequency range undergo Landau damping on resonant electrons, drawing out an asymmetric tail in the electron parallel velocity distribution, which carries a current.

From Hippocrates to Palmaz-Schatz, the history of carotid surgery.

The extracranial carotid artery is the most common site for peripheral vascular procedures. Although the association of carotid disease and neurologic dysfunction was understood by the ancient Greeks, over 1700 years would pass before the relevant anatomy was described. In the 16th and 17th centuries, attempts at treatment of carotid injury and aneurysm by ligation were met with extremely high rates of stroke and death. It is not until the mid 20th century, with the introduction of carotid angiography and improved vascular surgical techniques, that the era of reconstructive carotid surgery begins. We present a synopsis of the history of carotid surgery from ancient times to present day.

Life-threatening cytomegalovirus colitis in the immunocompetent patient: report of a case and review of the literature.

Cytomegalovirus colitis in the immunocompetent patient is an unusual clinical entity. We describe a patient with life-threatening cytomegalovirus colitis in the absence of immune deficiency and review the medical literature available on this topic.

The influence of patient strength, aerobic capacity and body composition upon outcomes after coronary artery bypass grafting.

BACKGROUND: Physical activity, physical fitness and body habitus of patients may be important predictors of outcomes after cardiac surgery. This study sought to quantify physical fitness and determine whether components of fitness enhance the prediction of outcomes in a group of patients undergoing coronary artery bypass grafting. METHODS: A group of 200 patients were evaluated prior to coronary artery bypass surgery. A Veterans Specific Activity Questionnaire (VSAQ) measured aerobic capacity. A grip dynamometer assessed strength. Skin-fold thickness was used to calculate percent body fat and lean body mass index. Patients were divided into low risk (0-2.5%) and high risk (>2.5%) groups based on the STS National Cardiac Surgery Database prediction of operative mortality. RESULTS: Patients with both a high percent body fat and a low VSAQ were at higher risk for at least one serious complication (p<0.05) and a longer postoperative length of stay (p<0.05). CONCLUSION: This study suggests: 1) An index of physical fitness can be obtained preoperatively in cardiac surgical patients; 2) This information aids in the prediction of operative risk.

Effects of combined aerobic and resistance training versus aerobic training alone in cardiac rehabilitation.

PURPOSE: This study examined the effects of performing combined resistance and aerobic training, versus aerobic training alone, in patients with coronary artery disease. METHODS: Thirty-six patients with coronary artery disease were randomized to either an aerobic-only training group (AE) or a combined aerobic and resistance training group (AE + R). Both groups performed 30 minutes of aerobic exercise 3 days/week for 6 months. In addition, AE + R group performed two sets of resistance exercise on seven different Nautilus machines after completion of aerobic training each day. Twenty patients (AE: n = 10; AE + R: n = 10) completed the training protocol with > 70% attendance. RESULTS: Strength gains for AE + R group were greater than for AE group on six of seven resistance machines (P < 0.05). VO2peak increased after training for both AE and AE + R (P < 0.01) with no difference in improvement between the groups. Resting and submaximal exercise heart rates and rate-pressure product were lower after training in the AE + R group (P < 0.01), but not in the AE group. AE + R increased lean mass in arm, trunk, and total body regions (P < 0.01), while AE increased lean mass in trunk region only (P < 0.01). Percent body fat was reduced for AE + R after training (P < 0.05) with a between group trend toward reduced body fat (P = 0.09). Lean mass gain significantly correlated with strength increase in five of seven resistance exercises for AE + R. CONCLUSIONS: Resistance training adds to the effects of aerobic training in cardiac rehabilitation patients by improving muscular strength, increasing lean body mass, and reducing body fat.

Interleukin-10 attenuates proinflammatory cytokine production and improves survival in lethal pancreatitis.

Given that interleukin (IL)-10 (IL-10) serves as a potent down-regulator of specific proinflammatory cytokines we reasoned that its administration should improve outcome in situations in which the biological response to a severe inflammatory challenge is the critical determinant of survival. To test our hypothesis we administered IL-10 in the setting of lethal pancreatitis to determine its effect on proinflammatory cytokine production and survival. We divided Sprague-Dawley rats into three groups. Controls (Group 1, n = 5) received a sham laparotomy. We induced pancreatitis in Group 2 (n = 9) and Group 3 (n = 9) via laparotomy and intrapancreatic infiltration of one mL of 5 per cent sodium taurocholate. Group 2 was treated only with saline, whereas Group 3 was treated with 10,000 units of IL-10 (in saline) at 30 minutes, 3.5 hours, and 6.5 hours after induction of pancreatitis. Serial blood samples were obtained at 6.5 hours for measurement of amylase, IL-1, and IL-6. The Kaplan-Meier method, Wilcoxon test, and Student's t test were used for analysis. Seven-day survival was 100, 0, and 45 per cent in Groups 1, 2, and 3, respectively. Production of amylase, IL-1, and IL-6 was lower in the IL-10-treated group (Group 3) compared with the group treated with saline alone (Group 2, P < 0.05). We conclude that administration of IL-10 in the setting of otherwise 100 per cent lethal experimental pancreatitis significantly reduces production of amylase, IL-1, and IL-6 and improves survival.

Patency and flow characteristics using stapled vascular anastomoses in dialysis grafts.

BACKGROUND: Improving patency of hemodialysis grafts is challenging. Vascular stapling creates nonpenetrating anastomoses, possibly decreasing intimal hyperplasia. We investigated patency and flow characteristics of stapled hemodialysis grafts. METHODS: Eighty-six grafts (41 stapled, 45 sewn) were placed in 84 patients (prospective, randomized). The groups had comparable demographics. RESULTS: Thirty-six grafts were functioning at the study endpoint. Complications in both groups were similar. The primary patency (stapled, 342 days versus sewn, 382 days; P = 0.67) and secondary patency (stapled, 513 days versus sewn, 507 days; P = 0.76) had no significant differences. Flow characteristics were similar between the groups. Thrombectomies per patient-year were 1.01 for stapled grafts and 1.12 for sewn grafts (not significant). Stapling decreased the average operating time by 4.5 minutes. CONCLUSIONS: Stapled and sewn anastomoses have similar primary and secondary patency and flow characteristics, with minimal operative time differences. Stapled anastomoses are safe but had no advantage over sewn anastomoses in this study.

Management of inflammatory aneurysm of the infrarenal aorta using retroperitoneal exposure, open aneurysmorrhaphy and descending aorta-to-femoral artery bypass.

The authors present a technique consisting of retroperitoneal exposure, but not dissection of the inflammatory aneurysm, anastomosis of a bypass graft through a short thoracotomy to the lowermost thoracic aorta, carrying it down retroperitoneally to both femoral arteries and under brief occlusion of the descending thoracic aorta, opening of the aneurysm and intra-aneurysmal occlusion of the inflow and outflow to the aneurysm. An illustrative case is presented.

Inhibition of needlestick-induced simulated viremia by local measures.

BACKGROUND: The possibility of confinement of simulated retrovirus to the inoculation site after needlestick injuries to enhance chances of local intervention and function of lymphaticovenous communications was investigated. METHODS: Using the canine model, technetium-99 m sulfur colloid particles were injected subcutaneously and into the vein and lymphatics. Blood and lymph were collected at a higher level from the femoral vein and the major lymphatic. Flow rates, particle arrival times, concentrations, and other variables were evaluated for 45 minutes by gamma counting. A tourniquet was used to slow dissemination after subcutaneous injection. RESULTS: After subcutaneous inoculation, particles arrived in the blood at 2.81 +/- 0.54 minutes and in the lymph at 6.0 +/- 1.47 minutes. Application of a tourniquet delayed appearance in the blood to 7.11 +/- 1.5 minutes and in the lymph to 40.0 +/- 5.1 minutes. Concentration of particles in lymph was 1,000 times higher than in the blood. Flux values were comparable in both pathways, but accumulation patterns were different. After intravenous injection, particles arrived in lymph at 25.4 +/- 6.44 minutes. After intralymphatic injection particles arrived in the blood within 4 seconds. CONCLUSIONS: There are functional lymphaticovenous communications at the peripheral level. The period between virus inoculation and blood and lymph invasion may be extended by application of a tourniquet; therefore, time could be gained for local intervention.

The effects of interleukin-10 in hemorrhagic shock.

BACKGROUND: Interleukin-10 (IL-10) counteracts the effects of the proinflammatory cytokines interleukin-1 (IL-1), interleukin-6 (IL-6), and tumor necrosis factor (TNF). Experimental data suggest that inhibition of these proinflammatory cytokines improves outcome in sepsis, endotoxemia, necrotizing pancreatitis, and other severe inflammatory states. We hypothesized that the administration of IL-10 would attenuate the release of proinflammatory cytokines after severe hemorrhagic shock. METHODS: To test our hypothesis, male Sprague-Dawley rats (N = 20) were divided into control and experimental groups. We induced hemorrhagic shock by removing a sufficient quantity of blood to maintain a mean arterial pressure of 50 mm Hg or less for 120 min. The animals were then resuscitated with shed blood and an equal volume of 0.9% saline. The experimental group received 10,000 units of IL-10 at the initiation of shock. Serum IL-1, IL-6, TNF, and lactate were measured at baseline, after 120 min of shock, and 60 min after resuscitation. The rats were followed for 72 h to calculate survival. RESULTS: Similar levels of hypoperfusion were obtained in both groups as demonstrated by lactate levels and amount of shed blood. The survival rate (70%) was the same in both groups. Serum levels of IL-1 and IL-6 were not significantly different between the two groups, although there was a trend toward IL-6 suppression. TNF, however, was significantly lower in the IL-10-treated group at the end of shock (Wilcoxon test, P < 0. 025). CONCLUSION: Administration of IL-10 suppresses the TNF surge observed after severe hemorrhagic shock.

Comparison of intermittent warm and cold blood perfusion during hypothermic myocardial preservation on functional and metabolic recovery.

Numerous techniques are used to maintain intraoperative heart viability. The studies presented here evaluated heart function and metabolism after various periods of preservation up to 4 hours with intermittent warm and cold blood perfusion. Using a heterotopic heart model cooled to 10 degrees C and maintained for 1, 2, 3, and 4 hours, various preservation techniques were compared. Changes in myocardial metabolism were determined from substrate uptakes and biopsy samples of the left ventricular muscle for high-energy phosphates. Preservation techniques included: (1) sustained hypothermia, (2) 1 or 2 hours of sustained warm blood perfusion with fibrillation, (3) intermittent cold blood perfusion during 2, 3, and 4 hours of preservation, (4) intermittent warm blood perfusion during 2, 3, and 4 hours of preservation and (5) a control group (no preservation). Normothermic fibrillation had no effect on postpreservation functional or metabolic parameters. Sustained hypothermia reduced functional recovery proportional to the length of ischemia. The cold intermittent procedures maintained function and metabolism better than sustained hypothermia, while warm intermittent preservation maintained function and metabolism at control levels throughout the recovery period for all preservation techniques. Changes in ATP mirrored the functional changes. Creatine phosphate (CP) was markedly reduced during heart isolation and preservation and exceeded the control by 100% during reperfusion. For operative procedures of 2 hours or less, functional and metabolic recovery was not affected by the various preservation methods applied. Warm intermittent perfusion during hypothermic preservation offered the best protection for the myocardium. The warming cycles during hypothermia may provide some degree of preconditioning and protect the myocardium during reperfusion.

Axillary artery aneurysms.

Aneurysms of the axillary artery are rare but potentially dangerous lesions that threaten the upper extremity with vascular and neurologic compromise. Most can be treated effectively with surgical excision and vascular grafting. An illustrative case is presented. These aneurysms may arise as pseudoaneurysms secondary to trauma or iatrogenic complications, or as degenerative lesions often secondary to the chronic use of crutches. They may also arise as postobstructive lesions in patients with thoracic outlet syndrome. Signs and symptoms vary with the cause of the aneurysm and may include mass effects with brachial plexus compression and thromboembolic events involving the hands and fingers. Arteriography is the mainstay of diagnosis, and treatment should be considered in most of these lesions as soon as they become apparent to prevent limb loss or dysfunction.

The effect of promoter strength in adenoviral vectors containing herpes simplex virus thymidine kinase on cancer gene therapy in vitro and in vivo.

The use of adenoviral vectors to deliver the herpes simplex virus thymidine kinase (HSVtk) gene followed by treatment with the prodrug ganciclovir (GCV) has promise for a variety of applications where excess cell proliferation is detrimental such as treatment of tumors and vascular restenosis. Optimizing this system is thus an important goal. The purpose of this study was to determine if the induction of higher levels of HSVtk expression would augment the sensitivity to GCV. This was accomplished by generating adenoviral vectors that expressed HSVtk from promoters of different efficiencies (the CMV versus RSV promoters). Despite higher levels of HSVtk expression per cell with the CMV promoter, there was no significant enhancement of antitumor effects between RSV- and CMV-driven adenovirus vectors in in vitro and in vivo studies indicating that simply increasing HSVtk enzyme levels per cell above a minimal threshold level will not be effective in augmenting the HSVtk/GCV system. These results suggest that other strategies, e.g., the use of higher doses of GCV, augmentation of the "bystander effect," the generation of mutant HSVtk genes with higher substrate affinities, the discovery of improved vectors with increased transduction efficiencies, or the development of new prodrugs with higher affinities for HSVtk will therefore be needed to enhance therapeutic responses.

Accurate adjustment of de Vega tricuspid annuloplasty using transesophageal echocardiography.

Intraoperative transesophageal echocardiography is used to adjust the tension of a de Vega tricuspid annuloplasty suture. Leading the suture outside the right atrium allows the annulus to be adjusted after cardiopulmonary bypass is discontinued when cardiac function has returned.