Installation and commissioning of the ion source systems for the new spallation neutron source 2.5 MeV injector.

The U.S. Spallation Neutron Source (SNS) is a state-of-the-art neutron scattering facility delivering the world's most intense pulsed neutron beams to a wide array of instruments, which are used to conduct investigations in many fields of engineering, physics, chemistry, material science, and biology. Neutrons are produced by spallation of liquid Hg by the bombardment of short (∼1 µs), intense (∼35 A) pulses of protons delivered at 60 Hz by an accumulator ring which is fed by a high-intensity, 1 GeV, H- LINAC (linear accelerator). This facility has operated nearly continuously since 2006 but has recently undergone a 4-month maintenance period, which featured a complete replacement of the 2.5 MeV injector feeding the LINAC. The new injector was developed at ORNL in an off-line beam test facility and consists of an ion source, low energy beam transport, and a Radio Frequency Quadrupole (RFQ). This report first describes the installed configuration of the new injector detailing the ion source system. The first beam current, RFQ transmission, emittance, and energy measurements from the injector installed on the SNS are reported. These data not only show a significant performance improvement for our existing facility but will also make accessible the higher beam current requirements for future SNS upgrade projects: the proton power upgrade and second target station.

rf improvements for Spallation Neutron Source H- ion source.

The Spallation Neutron Source at Oak Ridge National Laboratory is ramping up the accelerated proton beam power to 1.4 MW and just reached 1 MW. The rf-driven multicusp ion source that originates from the Lawrence Berkeley National Laboratory has been delivering approximately 38 mA H(-) beam in the linac at 60 Hz, 0.9 ms. To improve availability, a rf-driven external antenna multicusp ion source with a water-cooled ceramic aluminum nitride (AlN) plasma chamber is developed. Computer modeling and simulations have been made to analyze and optimize the rf performance of the new ion source. Operational statistics and test runs with up to 56 mA medium energy beam transport beam current identify the 2 MHz rf system as a limiting factor in the system availability and beam production. Plasma ignition system is under development by using a separate 13 MHz system. To improve the availability of the rf power system with easier maintenance, we tested a 70 kV isolation transformer for the 80 kW, 6% duty cycle 2 MHz amplifier to power the ion source from a grounded solid-state amplifier.

Stimulation of pepsinogen release from chief cells by Helicobacter pylori: evidence for a role of calcium and calmodulin.

To define the mechanisms by which Helicobacter pylori stimulates pepsinogen secretion, the in vitro release of pepsinogen was studied using a preparation of pig chief cell monolayers. Helicobacter pylori induced a time- and concentration-dependent release of pepsinogen into the medium, with about a three-fold increase in pepsinogen secretion over controls found after 45 min of incubation. 3x10(7) H. pylori produced 50% of the maximal response found at a H. pylori count of 2x10(8). The action of H. pylori did not depend on the presence of the vacuolating toxin (vacA) and the cytotoxin-associated protein (cagA). Dibutyryl-cAMP and the phorbol ester 12-O-tetradecanoylphorbol-13-acetate also markedly stimulated pepsinogen secretion and enhanced the stimulatory effect of H. pylori. Helicobacter pylori-stimulated pepsinogen release was inhibited by lanthanum and the calmodulin antagonist W-7, but not by the L-type Ca2+ channel blocker nifedipine, TMB-8, an agent that blocks the release of Ca2+ from intracellular stores, the protein kinase C inhibitor staurosporine and the protein kinase A inhibitor H-8. It is suggested that H. pylori directly stimulates pepsinogen release from gastric chief cells and that this effect is mediated via the calcium/calmodulin messenger branch.

Pepsinogen synthesis during long-term culture of porcine chief cells.

The purpose of this study was to characterize time-dependent changes in pepsinogen (PG) synthesis of porcine gastric chief cells during long-term monolayer culture. Porcine chief cells were isolated by pronase/collagenase treatment of fundic mucosa and enriched by density gradient and counterflow centrifugation. PG isoenzymes were identified in [L-35S]methionine-labelled cultured chief cells by native polyacrylamide gel electrophoresis followed by phosphor imager analysis, protease detection and immunoblots with specific PG A and C antibodies. The obtained results suggest that porcine chief cell cultures, after an initial settling period, reached an approximate steady state in total protein content and synthesis as well as in PG content and isoenzyme pattern from days 3 to 9 of culture. The latter was characterized by the presence of at least two PG A and two PG C isoenzymes. During the supposed steady-state total PG synthesis averaged out at 34 +/- 2% of total protein synthesis, as detected by [L-35S]methionine incorporation, due to the synthesis of, mainly, PG A2 and, to a much lesser extent, PG C and A1. In line with an active secretion, PG A2 proportion was on average significantly higher in released (44 +/- 3%) than in intracellular labelled proteins (19 +/- 2%). In addition, PG release from chief cells cultured for 6 and 9 days could be stimulated by cholecystokinin-octapeptide. These data suggest that porcine chief cells in monolayer culture are a model well suited for the quantitative and qualitative characterization of PG isoenzyme synthesis and release during long-term investigations, for which an establishment of a culture steady state appears to be a useful prerequisite.

Recovery of cholecystokinin response of porcine gastric chief cells during monolayer culture.

Cell isolation may impair secretory chief cell functions. To evaluate whether a monolayer culture results in a recovery, we compared the effects of cholecystokinin (CCK) octapeptide (CCK-8) on pepsinogen release from freshly isolated and from cultured porcine chief cells. CCK-8 had no significant effect on freshly isolated porcine chief cells but stimulated pepsinogen release from 36- and 60-hour cultured cells with EC50 values of 180 and 130 nmol/l, respectively. Maximal stimulation, achieved at a concentration of 1 micromol/l, amounted to 289 +/- 63 (p <0.01) and 401 +/- 64% (p <0.01) of the respective control value. In addition, the CCK-8 concentration-response curve for 60-hour, but not for 36-hour cultured chief cells displayed a second stimulatory peak at a CCK-8 concentration of 100 pmol/l (266 +/- 55% of control value, p < 0.05) with an EC50 value of 16 pmol/l. The CCKA-receptor antagonist devazepide (10 nmol/l) prevented the stimulatory effect of 1 micromol/l CCK-8 on pepsinogen release of 60-hour cultured cells. The adenylate cyclase activator forskolin (10 micromol/l) potentiated the low concentration CCK-8 effect, shifting the peak stimulation to a CCK-8 concentration of 10 pmol/l, and inhibited the high concentration CCK-8 effect on 60-hour cultured cells. These results indicate a time-dependent recovery of the CCK response of porcine gastric chief cells in monolayer culture and suggest that this model has an advantage over freshly isolated chief cells with regard to the pharmacological characterization of CCK effects.

Synthesis and release of phosphatidylcholine by isolated porcine gastric mucous cells in primary culture.

Phosphatidylcholine (PC) is the major phospholipid of the hydrophobic gastric mucosal barrier and is chiefly released from mucous cells into the gastric mucus. Whereas the mucosa contains highly unsaturated PC, gastric mucus predominantly contains palmitoyl-oleoyl-PC and palmitoyl-linoleoyl-PC, indicating a selective release of these PC species into the gastric lumen. In order to understand gastric PC metabolism, we investigated synthesis and release of PC in cultivated porcine gastric mucous cells, using dual labelling with [methyl-3H]-choline and [1-14C]-palmitate, in the presence of 12-O-tetradecanoylphorbol-13-acetate (TPA), indomethacin and prostaglandin E2 (PGE2). Linear incorporation of [methyl-3H]-choline and [1-14C]-palmitate into PC was achieved for at least 8h. In contrast to type II pneumocytes TPA increased PC synthesis in gastric mucous cells but not its release. Indomethacin did not influence PC synthesis, but it decreased the release of newly synthesized PC. PGE2 antagonized the effect of indomethacin on PC release. We conclude that PC release by isolated porcine gastric mucous cells is regulated in a manner different from type II pneumocytes. PC release is impaired by indomethacin and this impairment is restored by PGE2.

Development of an enzyme-linked immunosorbent assay of thromboxane B2 using a monoclonal antibody.

An inhibition enzyme-linked immunosorbent assay (ELISA) was developed using a monoclonal antibody against thromboxane B2 (TXB2). As a specific antigen, the bovine serum albumin conjugate of TXB2 was adsorbed onto polystyrene microtiter plates. The sensitivity of the monoclonal antibody was compared by means of three different enzyme conjugates, all commercially available. The detection limit with immunoglobulin conjugates of alkaline phosphatase and horseradish peroxidase was 0.04 ng of TXB2 per sample. The use of horseradish peroxidase coupled with an avidin-biotin complex allowed a tenfold increase in sensitivity to 0.0045 ng of TXB2 per sample. The suitability of the assay was checked with TXB2-containing human serum and urine samples, which yielded unchanged standard curves. Recovery experiments had an accuracy of r = 0.960 and r = 0.987. Validity was confirmed by a good correlation between radioimmunoassay and ELISA (r = 0.949). Results of an inhibition experiment with platelet-rich plasma in the presence and absence of ibuprofen demonstrated the practical applicability of this method.

[Clinicohematologic effects of hemoglobin Altdorf (alpha 2 beta 2 135 Ala replaced by Pro)]. / Klinisch-hämatologische Auswirkungen von Hämoglobin Altdorf (alpha 2 beta 2 135 Ala ersetzt durch Pro).

Hb Altdorf alpha 2 beta 2 135 Ala leads to Pro is an unstable variant occurring near Lecce in Italy. The abnormal hemoglobin does not separate from Hb A in the electrophoresis. In vitro a marked Heinz body formation is produced with phenylhydrazin. In heterozygous individuals an almost compensated hemolysis and a slight splenomegaly are found. Hemolysis can be aggravated by exogenous factors. A rather severe hemolysis was induced by a viral infection in a 3 years old girl.