Experimental Demonstration of Hadron Beam Cooling Using Radio-Frequency Accelerated Electron Bunches

Cooling of beams of gold ions using electron bunches accelerated with radio-frequency systems was recently experimentally demonstrated in the Relativistic Heavy Ion Collider at Brookhaven National Laboratory. Such an approach is new and opens the possibility of using this technique at higher energies than possible with electrostatic acceleration of electron beams. The challenges of this approach include generation of electron beams suitable for cooling, delivery of electron bunches of the required quality to the cooling sections without degradation of beam angular divergence and energy spread, achieving the required small angles between electron and ion trajectories in the cooling sections, precise velocity matching between the two beams, high-current operation of the electron accelerator, as well as several physics effects related to bunched-beam cooling. Here we report on the first demonstration of cooling hadron beams using this new approach.

Fast readout algorithm for cylindrical beam position monitors providing good accuracy for particle bunches with large offsets

A simple, analytically correct algorithm is developed for calculating "pencil" relativistic beam coordinates using the signals from an ideal cylindrical particle beam position monitor (BPM) with four pickup electrodes (PUEs) of infinitesimal widths. The algorithm is then applied to simulations of realistic BPMs with finite width PUEs. Surprisingly small deviations are found. Simple empirically determined correction terms reduce the deviations even further. The algorithm is then tested with simulations for non-relativistic beams. As an example of the data acquisition speed advantage, a Field Programmable Gate Array-based BPM readout implementation of the new algorithm has been developed and characterized. Finally, the algorithm is tested with BPM data from the Cornell Preinjector.

Optical beam profile monitor and residual gas fluorescence at the relativistic heavy ion collider polarized hydrogen jet

A gas fluorescence beam profile monitor has been implemented at the relativistic heavy ion collider (RHIC) using the polarized atomic hydrogen gas jet, which is part of the polarized proton polarimeter. RHIC proton beam profiles in the vertical plane of the accelerator are obtained as well as measurements of the width of the gas jet in the beam direction. For gold ion beams, the fluorescence cross section is sufficiently large so that profiles can be obtained from the residual gas alone, albeit with long light integration times. We estimate the fluorescence cross sections that were not known in this ultrarelativistic regime and calculate the beam emittance to provide an independent measurement of the RHIC beam. This optical beam diagnostic technique, utilizing the beam induced fluorescence from injected or residual gas, offers a noninvasive particle beam characterization and provides visual observation of proton and heavy ion beams.

Comparison of PCR and other diagnostic techniques for detection of Helicobacter pylori infection in dyspeptic patients

A sensitive and specific PCR-based assay to detect the Helicobacter pylori 16S rRNA gene present in formalin-fixed paraffin-embedded gastric biopsy specimens has been developed. A total of 95 patients with dyspepsia were evaluated for the presence of chronic active gastritis and an infection with H. pylori through the use of diagnostic assays based on biopsy specimens and serology. The "gold standard" for the presence of the bacteria was direct detection in histological sections of biopsy specimens by Giemsa stain. The results obtained with the PCR assay performed on the biopsy specimens (94% sensitivity and 100% specificity) were equivalent to the detection of H. pylori immunoglobulin G antibodies by the commercially available second-generation Cobas Core anti-H. pylori immunoglobulin G enzyme immunoassay (94% sensitivity and 98% specificity) for the diagnosis of H. pylori infection. Urease testing and bacterial culture of the biopsy specimens were inferior (88 and 70% sensitivity and 96% and 98% specificity, respectively). A Western blot (immunoblot) analysis had slightly greater sensitivity (96%), although specificity was reduced to 93%. This research prototype PCR assay was shown to be highly reliable for the detection of infection with H. pylori and the presence of chronic active gastritis in the population studied.

Urinary detected renal antigens in the early diagnosis of kidney graft rejection

The determination of renal antigens in the urine with an immunoassay, based on monoclonal antibodies (moabs), is a noninvasive test system for the analysis and monitoring of renal injury. New moabs allowing an immunohistologic dissection of the human nephron were generated by a direct intrasplenic immunization of mice with pathologic urine samples. A sandwich enzyme immunoassay was developed to quantitate renal cell membrane antigens in the urine samples. A sandwich enzyme immunoassay was developed to quantitate renal cell membrane antigens in the urine. While antigen excretion in healthy individuals is low, preliminary data of a clinical investigation suggest the usefulness of these assay systems in diagnosis of tubular injury in human kidney transplant recipients. The immunoassay can provide very early hints of renal graft rejection prior to the appearance of clinical symptoms or the detection by routine clinical laboratory investigations.

Myofibrillar interaction of blot immunoaffinity-purified antibodies against native titin as studied by direct immunofluorescence and immunogold staining

Titin (also called connectin), a major but so far highly elusive myofibrillar component in striated muscle was purified from glycerinated chicken breast muscle in its native state by use of a similar purification procedure as recently introduced for purification of native titin from rabbit psoas muscle. Low-angle rotary shadowing reveals highly convoluted, long and slender strands, sometimes more extended and with nodules, but also an aggregation into filamentous bundles and reticular networks. Antisera were raised against the purified native molecule and monospecific titin antibodies prepared by a rapid nitrocellulose blot immunoaffinity-purification procedure. Titin antibodies bound to the nitrocellulose immobilized native antigen were directly conjugated with fluorescein isothiocyanate. Titin specifity of purified antibodies was checked by immunoblotting. Direct immunofluorescence of glycerinated myofibrils revealed a uniform doublet staining pattern within the sarcomeres by labelling the region of the A-I junctions and some diffuse staining in the region of the myosin filaments. The same myofibrils examined by indirect immunoelectron microscopy revealed the gold particles highly concentrated at the A-I junctions with considerable labelling within the A-bands, except in their centers. Residual I-bands and Z-lines are free of label. In overstretched myofibrils immunogold staining labelled the gap filaments in the space between I- and A-bands. Isolated native thick filaments showed gold labelling of coiled superthin filaments at the ends of the thick filaments (end-filaments) and at their sides, respectively. The colloidal gold technique in combination with an affinity-purified titin antibody raised against the native molecule adds further evidence for the existence and distribution of an endosarcomeric superthin cytoskeletal filament lattice with titin as a major component.

An extraction resistant tensile protein in the protoplasmic matrix of Physarum

A thorough extraction of plasmodia of Physarum polycephalum by sequential treatment with 1% Triton x-100, 0.6 M KI, 4% SDS plus 7 M urea leaves behind an elastic cell ghost, which represents a cytoplasmic matrix protein arranged as a continuous network in all cell regions. The protein is present in the ectoplasm as well as in the endoplasm. The extraction-resistant ghosts reveal filaments 2-3 nm in diameter, perform a conspicuous volume condensation upon the addition of mM-concentrations of di- and trivalent cations and can be partially solubilized in 4.5 M guanidinium chloride plus 25% 2-mercaptoethanol at 70 degrees C. SDS-gel electrophoresis shows a distinct band at 43,000 daltons and a faint high molecular weight component suggesting a similarity to muscle connection.

Activation and inhibition of Na/K-ATPase by filipin-cholesterol complexation. A correlative biochemical and ultrastructural study on the microsomal and purified enzyme of the avian salt gland

The Na/K-ATPase-rich microsomal fraction and purified Na/K-ATPase membranes of the salt-stressed avian salt gland were studied at defined filipin/cholesterol molar ratios (F/C) using enzyme assay and electron microscopy including negative staining, thin sectioning and freeze fracturing. Comparative examinations of detergent-treated microsomal fractions and the use of electron microscopic tracers revealed that F/C up to 2 activated latent Na/K-ATPase in sealed right-side-out vesicles by increasing membrane permeability without disrupting the vesicular membrane. Therefore, filipin offers an alternative to the detergents for the activation of latent vectorial membrane enzymes and a possible tool to examine their subcellular localization and sidedness in the membrane. The same F/C had no stimulatory effect on the microsomal anion-ATPase suggesting that the 2 ATPases are not located in the same membrane. Increasing F/C applied to the unfixed Na/K-ATPase membranes caused an increase in the number of structural F-C-complexes and a progressive lateral displacement of the enzyme particles which finally led to a separation of the areal distribution of these structures at F/C = 10. Such displacements did not occur in unfixed microsomes and were prevented by glutaraldehyde fixation of the purified membranes. F/C exceeding 2 progressively and temperature-dependently inhibited the Na/K-ATPase in its membrane-bound states, whereas the solubilized enzyme was rather insensitive. The structural and biochemical data suggest that inhibition results from the perturbation of the lipidic microenvironment of the enzyme caused by filipin-cholesterol complexation.

Ultrastructure of the purified and reconstituted Na/K-ATPase of the avian salt gland

Na/K-ATPase of salt-stressed salt glands of the domestic duck (Anas platyrhynchos) was purified in membrane-bound form by incubation of the microsomal fraction with sodium dodecylsulphate and ATP followed by discontinuous sucrose gradient centrifugation. Gel electrophoresis of the purified plasma membrane preparation substantially showed the two polypeptide subunits of the Na/K-ATPase both of which stained with the periodic acid-Schiff reagent. About 99% of the total ATPase activity was ouabain-inhibitable amounting to 1300 mumol Pi/(mg protein X h) of specific activity. The anion-stimulated, ouabain-insensitive ATPase increased parallel to the Na/K-ATPase up to the microsomal fraction until it totally vanished during SDS incubation. Electron microscopy of thin sections revealed that the purified fraction consisted of flat and cup-shaped triple-layered membrane fragments. Particles arranged into clusters and strands were visible as 3 to 5 nm surface particles in negatively stained suspensions and as 8 to 10 nm intramembraneous particles in freeze fracture replicas. The differential distribution of the intramembraneous particles on the fracture faces reflected the structural membrane asymmetry. Solubilization of Na/K-ATPase led to the disappearance of intramembraneous particles. Incorporation of the solubilized enzyme into phosphatidylcholine vesicles again showed 8 to 10 nm particles apparently orientated at random in the artificial membrane. Control liposomes prepared in the absence of solubilized enzyme were devoid of intramembraneous particles. These results clearly demonstrate that the avian salt gland Na/K-ATPase exists as 8 to 10 nm particles in both the purified plasma membrane and the artificial phospholipid membrane.

Chloride- and bicarbonate-stimulated ATPase activity in bovine lens epithelium

An anion-stimulated, ouabain-insensitive Mg2+ATPase activity has been found in fresh homogenates prepared from capsules and epithelia of bovine lenses. Approximately equal activity was observed in the presence of HCO3- or of Cl-. The stimulation of each anion obeys saturation kinetics, with an optimum at approximately 20 mM Cl- or HCO3-. Whereas SCN- inhibits anion-activated ATPase in most other tissues, it failed to inhibit Cl- - or HCO3--stimulated ATPase activity in the bovine lens. On the contrary, SCN- proved a potent activator of the enzyme. However, in keeping with other tissues, OCN- and the diuretic drugs, furosemide and ethacrynic acid are inhibitory. ATP is the primary substrate for the enzyme, which also shows some activity on GTP, ITP, and even ADP. Little Na+/K+-dependent ATPase activity was observed in the fresh homogenate, but it increased in lyophilized preparations. In contrast, the lyophilized preparations showed no anion-dependent ATPase activity. It is postulated that active bicarbonate ion transport in the lens may be mediated by this anion-dependent ATPase.

The loop diuretic furosemide as non-competitive inhibitor of C1-/HCO3-ATPases of vertebrate kidneys and insect rectum

1. The effect of the diuretic drug furosemide was studied in detail on ouabain-insensitive, SCN- and OCN- -sensitive C1-/HCO-3-ATPase in homogenates from larval dragonfly rectum (Aeshna cyanea), frog (Rana temporaria) and mouse (Mus musculus) kidney. 2. The in vitro inhibition by the drug studied on the HCO-3-activated enzyme is non-competitive with an inhibitor constant of Ki=4.3 mM furosemide in the case of insect rectum and Ki=0.9 mM furosemide in the case of frog and mouse kidney. 3. Furosemide even at 10 mM concentration which completely inhibits the anion-dependent ATPase has only a little inhibitory effect on the Na+/K+-ATPase of the 3 tissues. 4. The data suggest that furosemide may affect an active chloride transport system involving a C1-/HCO-3-ATPase.

[Demonstration and properties of a Cl-/HCO3--ATPase in the avian salt gland (author's transl)]

An anion-stimulated, Mg2+-dependent, ouabain-insensitive ATPase is present in salt gland homogenates of domestic ducks (Anas platyrhynchos). The enzyme is unspecifically stimulated by various inorganic and organic anions including amino and sulfonic acids which are often used as buffer components (e. g. histidine, Bicin, PIPES, MES and HEPES). Therefore, the demonstration of ATPase stimulation by chloride strongly depends on the type and concentration of the buffer used and may also largely interfere with the stimulation caused by other anions present in the incubation medium. Of the inorganic anions tested chloride and bicarbonate appear to be the favorite physiological activators, but the possible role of carbonic acids in the stimulation of the anion-dependent ATPase should not be neglected. Km values are approximately 5.8 mM for Cl- and approximately 8.7 mM for HCO-3-activation. Maximal ATPase stimulation is obtained at 25 mM Cl- and approximately 30 mM HCO-3, respectively. The simultaneous presence of bicarbonate decreases chloride affinity and Vmax, and shifts the chloride optimum to lower concentrations. ATP is the most preferred substrate. Maximal activation by Cl- and HCO-3 occurs at ATP concentrations between 0.5 and 1 mM. ATP affinity increases in the presence of Cl- and HCO-3, respectively. Both chloride and bicarbonate require a Mg2+ to ATP ratio of approximately 0.5 and a pH value of 8.0 to 8.5 for optimal stimulation. Stimulation by Cl- and HCO-3 is inhibited by thiocyanate, cyanate and by the diuretic drugs furosemide, ethacrynic acid and mersalyl. Incubation media adapted for the simultaneous demonstration of both chloride and bicarbonate activation contained 10 to 20 mM histidine-Tris buffer at pH 8.0 to 8.5, 150 mM sucrose, 0.2 mM ouabain, 0.5 mM magnesium acetate, 1 mM ATP, (pH adjusted to 8.0-8.5 with Tris or NaOH), with and without 25 mM sodium chloride or 25 mM sodium bicarbonate.

Inhibition of a Cl-/HCO3(-)ATPase in the avian salt gland by furosemide and ethacrynic acid

An ouabain-insensitive, Mg2+-dependent, chloride- and bicarbonate-stimulated ATPase is present in salt gland homogenates of domestic ducks (Anas platyrhynchos). Furosemide and ethacrynic acid are non-competitive inhibitors of this enzyme in vitro. The inhibitor constant of furosemide is Ki = 2.5 mM and of ethacrynic acid Ki = 1.9 mM. In contrast, under the same conditions the salt gland Na+/K+-ATPase activity is not inhibited by furosemide, whereas ethacrynic acid becomes inhibitory only at higher concentrations (10 mM).