Impact of avalanche type of transport on internal transport barrier formation in tokamak plasmas.

In magnetic fusion plasmas, a transport barrier is essential to improve the plasma confinement. The key physics behind the formation of a transport barrier is the suppression of the micro-scale turbulent transport. On the other hand, long-range transport events, such as avalanches, has been recognized to play significant roles for global profile formations. In this study, we observed the impact of the avalanche-type of transport on the formation of a transport barrier for the first time. The avalanches are found to inhibit the formation of the internal transport barrier (ITB) observed in JT-60U tokamak. We found that (1) ITBs do not form in the presence of avalanches but form under the disappearance of avalanches, (2) the surface integral of avalanche-driven heat fluxe is comparable to the time rate change of stored energy retained at the ITB onset, (3) the mean E × B flow shear is accelerated via the ion temperature gradient that is not sustained under the existence of avalanches, and (4) after the ITB formation, avalanches are damped inside the ITB, while they remain outside the ITB.

Energy-selective confinement of fusion-born alpha particles during internal relaxations in a tokamak plasma.

Long-pulse operation of a self-sustained fusion reactor using toroidal magnetic containment requires control over the content of alpha particles produced by D-T fusion reactions. On the one hand, MeV-class alpha particles must stay confined to heat the plasma. On the other hand, decelerated helium ash must be expelled before diluting the fusion fuel. Here, we report results of kinetic-magnetohydrodynamic hybrid simulations of a large tokamak plasma that confirm the existence of a parameter window where such energy-selective confinement can be accomplished by exploiting internal relaxation events known as sawtooth crashes. The physical picture - a synergy between magnetic geometry, optimal crash duration and rapid particle motion - is completed by clarifying the role of magnetic drifts. Besides causing asymmetry between co- and counter-going particle populations, magnetic drifts determine the size of the confinement window by dictating where and how much reconnection occurs in particle orbit topology.

Conceptual design of a collimator for the neutron emission profile monitor in JT-60SA using Monte Carlo simulations.

Materials and structures of a collimator for a new neutron emission profile monitor in JT-60SA are examined through Monte Carlo simulations using the Monte Carlo N-Particle transport code. First, the shielding properties of various material combinations are compared in order to determine a combination with high shielding performances against both neutrons and gamma-rays. It is found that a collimator consisting of borated polyethylene and lead has a high shielding performance against neutrons. Moreover, a high shielding performance against gamma-rays is obtained when a lead pipe with a radial thickness of 0.01 m is inserted into a collimation tube. Second, we demonstrate that it is possible to improve the spatial resolution to a desired level by installing a thin tubular extension structure that fits into the limited space available between the main collimator block and the tokamak device. Finally, the collimator structures that meet both the targeted spatial resolutions (<10% of the plasma minor radius) and the targeted counting rate (105 cps order) are discussed.

Multi-point measurement using two-channel reflectometer with antenna switching for study of high-frequency fluctuations in GAMMA 10.

A two-channel microwave reflectometer system with fast microwave antenna switching capability was developed and applied to the GAMMA 10 tandem mirror device to study high-frequency small-amplitude fluctuations in a hot mirror plasma. The fast switching of the antennas is controlled using PIN diode switches, which offers the significant advantage of reducing the number of high-cost microwave components and digitizers with high bandwidths and large memory that are required to measure the spatiotemporal behavior of the high-frequency fluctuations. The use of two channels rather than one adds the important function of a simultaneous two-point measurement in either the radial direction or the direction of the antenna array to measure the phase profile of the fluctuations along with the normal amplitude profile. The density fluctuations measured using this system clearly showed the high-frequency coherent fluctuations that are associated with Alfvén-ion-cyclotron (AIC) waves in GAMMA 10. A correlation analysis applied to simultaneously measured density fluctuations showed that the phase component that was included in a reflected microwave provided both high coherence and a clear phase difference for the AIC waves, while the amplitude component showed neither significant coherence nor clear phase difference. The axial phase differences of the AIC waves measured inside the hot plasma confirmed the formation of a standing wave structure. The axial variation of the radial profiles was evaluated and a clear difference was found among the AIC waves for the first time, which would be a key to clarify the unknown boundary conditions of the AIC waves.

Thioredoxin induction of peripheral blood mononuclear cells in mice in response to a single bout of swimming exercise.

Thioredoxin (TRX) is a stress-inducible protein with diverse intracellular functions, which is expressed under conditions of oxidative stress. Exercise is known to cause oxidative stress by the generation of oxygen radicals from various biological pathways. The purpose of this study was to determine the level of TRX induction of cellular extracts prepared from peripheral blood mononuclear cells after a 30-min swimming exercise in mice. Plasma corticosterone concentration, considered to be a marker for exercise-induced various stress, rose significantly (p < 0.05) 0.5 h after exercise and rapidly dropped down following recovery. The carbonyl proteins as a marker of oxidative stress were significantly (p < 0.05) higher after 6 and 12 h of recovery in cytosolic extracts. The cytoplasm and nucleus TRX expressions were slightly higher to resting values after 12 and 24 h of recovery. The nucleus TRX expression was significantly (p < 0.05) higher after 24 h of recovery. These findings demonstrate that exercise-induced oxidative stress may be associated with increased intracellular TRX expression after 12 and/or 24 h after exercise in peripheral blood mononuclear cells. It is implied that this delayed and prolonged over-expression of TRX may play some roles in response to exercise-induced oxidative stress.

Osteosarcoma as a second malignancy after treatment for neuroblastoma.

A 4-month old girl was diagnosed as having stage IV neuroblastoma of the right adrenal gland. Preoperative chemotherapy was given, followed by local surgical excision. Postoperatively, irradiation of the tumor bed and adjuvant chemotherapy was given for 11 months. Nine years after cessation of chemotherapy, the patient developed left hip-joint pain. Biopsy of the ischium showed chondroblastic osteosarcoma. Limb salvage surgery was performed after preoperative chemotherapy. Postoperatively, adjuvant chemotherapy was given for 14 months. Twenty-two months after treatment for the secondary osteosarcoma, the patient has been remained in disease-free condition without any evidence of relapse. A second osteosarcoma occurring outside the radiation field after treatment for neuroblastoma is quite rare. This unusual case emphasized the need for close monitoring for development of second malignant neoplasms in survivors of neuroblastoma even in the absence of a known predisposing factor, such as radiation therapy.

Identification of a receptor type guanylyl cyclase in the antennal lobe and antennal sensory neurons of the silkmoth, Bombyx mori.

Sensory neuron-specific guanylyl cyclases (GC), which were recently identified in rodents and nematodes, are thought to be a new family of odorant/pheromone receptors. In the antennae of the male silkmoth Bombyx mori, receptor type GC are supposed to mediate signaling of pheromone. Structure of receptor type GC expressed in insect sensory neurons has remained unidentified. Here we report the isolation of cDNA of the receptor type GC, designated BmGC-I, from the male silkmoth antennae. The deduced amino acid sequence indicates that BmGC-I appears to consist of four domains: an extracellular, single transmembrane, kinase-like and a guanylyl cyclase domain. BmGC-I is most closely related to the mammalian natriuretic peptide hormone receptor A (GC-A) and retains all the cysteine residues that are conserved within the extracellular domain of the mammalian GC-As. Transcripts of the BmGC-I gene were detected in various tissues; the flight muscles, midgut, legs, ganglion, Malpighian tubules, testis and the head. Immunohistochemical study revealed that the BmGC-I protein localizes in the antennal-lobe glomerulus and in the soma and axon of sensory neurons. We thus suggest that BmGC-I plays functional roles in the odorant information processing and the modulation of excitability in the antennal sensory neurons.

In vitro study and in vivo application of a reusable double-channel sphincterotome.

BACKGROUND AND STUDY AIMS: Therapeutic endoscopic retrograde cholangiopancreatography (ERCP) has been deemed to be a "cost-prohibitive" procedure, based upon the cumulative costs of one-time-use accessories and current reimbursement plans. One-time-use sphincterotomes comprise a significant component of that cost and, accordingly, we evaluated the disability and clinical usefulness of a recently introduced reusable double-channel sphincterotome. MATERIALS AND METHODS: We studied a reusable 6-Fr sphincterotome at baseline and following contamination with 10(6) Bacillus stearothermophilus. Reprocessing included a unique 30-minute ultrasonic cleaning step in lieu of manual cleaning, followed by steam sterilization. Parameters evaluated included sphincterotome function, electrical integrity, and our ability to sterilize the devices for three in vitro trials. In vivo studies included patient demographics and outcomes, procedural findings, and success rates, and the mean number of times the sphincterotome was used, functional grading at time of use, and reasons for sphincterotome malfunction. RESULTS: Ten out of ten sphincterotomes maintained form, function, and electrical integrity in vitro, and all cultures were negative after sterilization. In the initial in vivo study, ten sphincterotomes were used in 50 patients (mean, 5 uses) with a 94% success rate. Reasons for sphincterotome failure included leak or breakage of the accessory port in 70%, wire fracture in 10%, incorrect wire bow in 10%, and clogged injection port in 10%. Following reconfiguration of the insertion-port polymer, an additional ten sphincterotomes were used in 110 patients (mean, 11 uses). Mechanical failure occurred primarily at the wire-insertion port, resulting in progressive friction with reuse. There were neither electrical nor infectious complications associated with reuse. CONCLUSIONS: A reusable double-channel sphincterotome is available which can theoretically be reprocessed and sterilized without the manual cleaning step of the reprocessing process. Contingent upon both provider and patient, multiple reuse can be anticipated, and contingent upon purchase price and reprocessing costs, the potential for procedural cost savings is significant.

Reusable biopsy forceps: a prospective evaluation of cleaning, function, adequacy of tissue specimen, and durability.

BACKGROUND: Recent studies have indicated that reusable biopsy forceps remain contaminated after reprocessing and can only be used a mean of 12 to 25 times without malfunction. Because this contradicts traditional endoscopic practice, our study investigated the ability to sterilize a type of commercially available biopsy forceps and prospectively evaluated their function in vivo until malfunction and/or breakage. METHODS: Thirty reusable biopsy forceps were studied, 15 of which were contaminated for 5 trials each with 10(6) Bacillus stearothermophilus, and 15 of which were prospectively evaluated clinically over an 18-month period (9/98-3/00). Contaminated forceps were reprocessed by using a standard protocol and placed in a sterile bag containing soy broth. The latter was passed through a 0.2 micron filter and was subsequently cultured. In vivo data included biopsy site, size, adequacy, problems obtaining a biopsy specimen, and reasons for ultimate forceps failure. RESULTS: After contamination, all biopsy forceps yielded a heavy growth of B stearothermophilus. No forceps, including 5 that were piecemeal dismantled with a wire cutter, had residual bacteria after reprocessing. In the in vivo study, 1507 biopsy sessions were undertaken in 1339 procedures. Forceps were categorized as new or like-new in 1259 of 1339 (94%) procedures, some loss of function but usable in 72 of 1339 (5.4%), and inadequate function or broken at use in 8 of 1339 (0.6%). Histologically, 1501 specimen sets were adequate (99.6%) and mean specimen size was 2.7 +/- 0.1 mm. Mechanical problems were noted in only 38 of 1507 (3%) sessions to include such things as sticky forceps, and the mean number of uses to malfunction or breakage was 91 +/- 15 (SEM) (range 19-132). CONCLUSIONS: This reusable biopsy forceps can be sterilized and used a mean of 91 times with adequate tissue sampling. Mechanical problems were minor to time of breakage. Contingent on acquisition and reprocessing costs as well as the number of procedures performed, this reusable forceps has the potential for significant cost savings.

Recombinant human erythropoietin therapy for autologous blood donation in rheumatoid arthritis patients undergoing total hip or knee arthroplasty.

The effect of recombinant human erythropoietin on autologous blood donation was investigated in 73 rheumatoid arthritis patients who underwent hip or knee arthroplasty. Autologous blood donation of 400 mL was successful with recombinant human erythropoietin (12,000 U per week), and no homologous blood was required. The mean period of blood collection was 33.8 days. Mean hemoglobin levels were 9.7 g/dL before treatment, 10.7 g/dL before surgery, and 10.2 g/dL after surgery. This study confirmed recombinant human erythropoietin is effective for enabling preoperative blood donation in rheumatoid arthritis patients.

Early Permian bipedal reptile.

A 290-million-year-old reptilian skeleton from the Lower Permian (Asselian) of Germany provides evidence of abilities for cursorial bipedal locomotion, employing a parasagittal digitigrade posture. The skeleton is of a small bolosaurid, Eudibamus cursoris, gen. et sp. nov. and confirms the widespread distribution of Bolosauridae across Laurasia during this early stage of amniote evolution. E. cursoris is the oldest known representative of Parareptilia, a major clade of reptiles.

New route to alpha-adducts of homoallylic alcohols by an acid-catalyzed stereospecific allyl-transfer reaction from gamma-adducts

Allylation of aldehydes by an allyl-transfer reaction from the gamma-adducts of homoallylic alcohols has been successfully carried out to give the corresponding alpha-adducts regiospecifically. The reaction proceeds via a hemiacetal (11), derived from an aldehyde and the homoallylic alcohol, followed by a six-membered cyclic transition state (2-oxonia[3.3]-sigmatropic rearrangement) in the presence of a Lewis acid. Moreover, the gamma-adducts are restructured into the corresponding alpha-adducts via a similar transition state by an acid catalyst, in which chirality in both anti- and syn-gamma-adducts is stereospecifically transferred to the corresponding E- and Z-alpha-adducts, respectively, with > 98% ee.

In vitro and in vivo evaluation of a reusable double-channel sphincterotome.

BACKGROUND: To date, one reusable, double-channel sphincterotome has been approved by the Food and Drug Administration in the United States. Whether this device can be reprocessed easily and whether it is more durable than currently manufactured disposable sphincterotomes are uncertain. METHODS: Thirty double-channel, 20 mm, braided-wire sphincterotomes approved for multiple uses were studied in vitro/in vivo with regard to durability and sterilization. A cost analysis of reusable, disposable, and reprocessed disposable sphincterotomes was also carried out. RESULTS: Three of 10 sphincterotomes evaluated in vitro broke after 3, 4, and 8 uses. Electrical integrity was preserved after 10 uses in the remaining sphincterotomes. Nine sphincterotomes remained functional for at least 3 uses, five for 6 uses, and one for 10 uses. Culture results after inoculation demonstrated contamination with surviving organisms after manual cleaning and no growth after ethylene oxide sterilization. Sixty-one procedures were performed in vivo using 20 sphincterotomes (mean number of uses 3.1). No evidence of procedurally related infection occurred with reuse. Cost per use of this reusable sphincterotome was calculated to be $62.98; it became cost effective after 2.2 and 7.9 uses when compared with disposable and reprocessed, disposable sphincterotomes, respectively. CONCLUSIONS: This reusable sphincterotome proved to be safe, easily sterilized, and electrically intact after repeated use. In vivo, however, a progressive loss of function limited the mean number of uses to 3.1. In settings that preclude reuse of reprocessed disposable accessories, this reusable sphincterotome may provide a means to decrease costs associated with endoscopic retrograde cholangiopancreatography.

In vitro evaluation of integrity and sterilization of single-use argon beam plasma coagulation probes.

OBJECTIVE: Argon plasma coagulation probes (APC) are currently marketed in the United States as single-use items, and may constitute a significant per-procedure expense. It is unknown whether these probes can be sterilized after endoscopic use and if electrical integrity can be maintained after reprocessing. METHODS: Ten probes (2.3 mm diameter, 220 cm length) manufactured by ERBE Inc., (Marietta, GA) were studied using the ERBE APC 300 at 60 watts. Baseline coagulation depth was measured by coagulating a piece of beefsteak for 60 s. Probes were contaminated with 10(6) Bacillus subtilis spores, cultured, and manually cleaned. Culturing involved introducing 10 cc sterile water through the probes; water was filtered, plated onto blood agar, and incubated for 48 h. After ethylene oxide (ETO), the probes were cultured to determine sterilization. Finally, the per-procedure cost of each probe was assessed. RESULTS: Ten of 10 probes completed 10 testing sessions. One probe split at the proximal end but remained functionally intact. Electrical integrity remained intact for all 10 sessions. All probes grew too numerous to count colonies of B. subtilis after inoculation and no B. subtilis was detected after ETO sterilization. Assuming 10 uses clinically, a total per-procedure equipment cost would approximate $24.00, whereas per-procedure probe cost would equal $42.66 if only five uses were obtained in vivo. CONCLUSIONS: The combination of manual cleaning and ETO sterilization consistently sterilized APC probes. Ninety percent of the probes showed no sign of physical deterioration and 100% maintained their electrical activity after 10 uses. APC probes can potentially be safely and effectively reused up to 10 times, and a significant procedural savings is possible with reuse.

Risk of contamination of sterile biopsy forceps in disinfected endoscopes.

BACKGROUND: Previous studies have shown that pathogens may persist within bacterial biofilms in endoscope accessory channels despite high-level disinfection. Breaching the gastrointestinal mucosa with biopsy forceps contaminated at time of passage has the potential to cause cross-infection between patients. METHODS: We studied contamination risk of sterilized biopsy forceps passed through endoscopes after high-level disinfection. For each trial, five video colonoscopes, duodenoscopes, and gastroscopes were used. All endoscopes had been previously processed and stored for 10 or more hours. Sterile biopsy forceps were inserted and retrieved followed by vortexing the tips in 15 mL of soy broth. Under a laminar flow hood, the broth was filtered through a 0.2 microm millipore membrane and plated. Because of minimal bacterial growth resulting from the above, soy broth (> 20 mL) was flushed through two video colonoscopes, duodenoscopes, and gastroscopes on two occasions and collected. The effluent was plated using a sample of 0.1 mL dilution. The remaining suspension was passed through a millipore filter, and the filter was cultured. All cultures were incubated more than 48 hours. RESULTS: Biopsy forceps underwent a total of 24 anaerobic and 75 aerobic cultures. Microbacterial growth occurred on 17 plates: 7 from gastroscopes, 5 from colonoscopes, and 5 from duodenoscopes. Fifteen plates grew staphylococcus for a total of 21 colonies, 1 plate grew 1 colony of propionibacter, 2 plates grew diphtheroids for a total of 4 colonies, and 1 plate grew a single colony of lactobacillus. Cultures from soy broth flushed through the various endoscopes grew on 5 plates: 3 from gastroscopes and 2 from duodenoscopes grew a total of 8 colonies of staphylococcus. CONCLUSIONS: With proper cleaning technique, a 20-minute soak in 2% glutaraldehyde is effective in disinfecting endoscopes. Although current procedures for endoscope disinfection remain imperfect, we found that in this clinical setting, infection of pathogenic gastrointestinal flora is unlikely when using sterile biopsy forceps.

No influence of a single bout of exercise on urinary excretion of 8-hydroxy-deoxyguanosine in humans.

We investigated the effect of a single bout of intensive exercise on the excretion of 8-hydroxy-deoxyguanosine in the 24 h urine from healthy non-smokers. We studied three exercise tests in Experiment 1; which consisted of incremental exercise to exhaustion on a treadmill in eleven male long distance runners. Experiment 2; which comprised incremental exercise until reaching exhaustion on a bicycle ergometer in six male untrained subjects. Experiment 3; which consisted of a 20 km run by eleven male long distance runners. No differences in the urinary 8-hydroxy-deoxyguanosine excretion were observed from days 1 to 3 after each respective exercise regimen. However, significant increases in the plasma creatine kinase activity were observed at 24 h or 48 h after exercise, except for Experiment 2. Our results thus suggest that the oxidative stress during a single bout of intensive exercise does not result in an accumulation of oxidative DNA damage.

Effect of repeated exercise on urinary 8-hydroxy-deoxyguanosine excretion in humans.

The purpose of this study was to investigate the effect of repeated exercise on oxidative damage to DNA in 10 well trained long distance runners who participated in an 8-day training camp. The average running distance during the camp was 30 +/- 3 km/day. The amount of urinary 8-hydroxy-deoxyguanosine (8-OHdG) excretion was used to estimate the oxidative DNA damage. Urine samples were collected for both a 3-day control period as well as throughout the camp. Blood samples were drawn after overnight fasting both before and after the camp. Urinary 8-OHdG excretion was significantly increased during the camp compared to the control period (265.7 +/- 75.5 vs. 335.6 +/- 107.4 pmol/kg/day, P < 0.05). The content of 8-OHdG in the lymphocyte DNA on the day after finishing the camp did not differ from that before the camp. Plasma TBARS, LDH, CK, CK-MB, and myoglobin significantly rose after the camp (P < 0.05). The plasma beta-carotene levels tended to rise after the camp, while the plasma alpha-tocopherol levels increased significantly after the camp (P < 0.05). These results indicate that repeated exercise augments oxidative stress and the DNA is also injured by exercise-induced reactive oxygen species. However, the oxidative damage to DNA is not accumulated by consecutive exercise, although it is sustained as long as the exercise is repeated.

Effect of endurance exercise on the tissue 8-hydroxy-deoxyguanosine content in dogs.

The purpose of this study was to investigate the effect of endurance exercise on both the tissue and lymphocyte 8-hydroxy-deoxyguanosine (8-OHdG) content. Six dogs ran on a treadmill for 7 hours. Another six dogs were assigned to a sedentary control group. The exercised dogs were sacrificed immediately after exercise and the counterpart of the sedentary group was also sacrificed at the same time. The brain, lung, liver, spleen, kidney, jejunum, colon, diaphragm, heart, splenius muscle, and the medial and lateral portion of gastrocnemius muscle samples were then collected. Lymphocytes were sampled before and after exercise in the exercised dogs. The 8-OHdG content of lymphocyte DNA was found to significantly decrease after exercise (0.57 +/- 0.19 vs 0.33 +/- 0.10/deoxyguanosine (dG) x 10(5), P < 0.05). The colon was the only tissue which showed a significant decrease in the content (0.83 +/- 0.24 vs 0.54 +/- 0.15/dG x 10(5), P < 0.05). No tissue except for the colon showed any significant changes after exercise. These results therefore indicate that, immediately after endurance exercise, an augmented repair mechanism might thus play a role in the decrease of 8-OHdG in the lymphocytes and the colon, while the 8-OHdG generation might be counterbalanced by its repair in other tissues.