ABSTRACT
Results are presented on Omega production in central Pb+Pb collisions at 40 and 158A GeV beam energy. For the first time in heavy ion reactions, rapidity distributions and total yields were measured for the sum Omega(-) + Omega(+) at 40A GeV and for Omega(-) and Omega(+) separately at 158A GeV. The yields are strongly underpredicted by the string-hadronic UrQMD model but agree better with predictions from hadron gas models.
ABSTRACT
Emission of pi+/-, K+/-, phi, and Lambda was measured in near-central C+C and Si+Si collisions at 158 AGeV beam energy. Together with earlier data for p+p, S+S, and Pb+Pb, the system-size dependence of relative strangeness production in nucleus-nucleus collisions is obtained. Its fast rise and the saturation observed at about 60 participating nucleons can be understood as the onset of the formation of coherent systems of increasing size.
ABSTRACT
Production of Lambda and Antilambda hyperons was measured in central Pb-Pb collisions at 40, 80, and 158A GeV beam energy on a fixed target. Transverse mass spectra and rapidity distributions are given for all three energies. The Lambda/pi ratio at midrapidity and in full phase space shows a pronounced maximum between the highest BNL Alternating Gradient Synchrotron and 40A GeV CERN Super Proton Synchrotron energies, whereas the Lambda/pi ratio exhibits a monotonic increase.
ABSTRACT
Results of resonance searches in the Xi(-)pi(-), Xi(-)pi(+), Xi;(+)pi(-), and Xi;(+)pi(+) invariant mass spectra in proton-proton collisions at sqrt[s]=17.2 GeV are presented. Evidence is shown for the existence of a narrow Xi(-)pi(-) baryon resonance with mass of 1.862+/-0.002 GeV/c(2) and width below the detector resolution of about 0.018 GeV/c(2). The significance is estimated to be above 4.2sigma. This state is a candidate for the hypothetical exotic Xi(--)(3/2) baryon with S=-2, I=3 / 2, and a quark content of (dsdsu). At the same mass, a peak is observed in the Xi(-)pi(+) spectrum which is a candidate for the Xi(0)(3/2) member of this isospin quartet with a quark content of (dsus[-]d). The corresponding antibaryon spectra also show enhancements at the same invariant mass.
ABSTRACT
We present the first measurement of fluctuations from event to event in the production of strange particles in collisions of heavy nuclei. The ratio of charged kaons to charged pions is determined for individual central Pb+Pb collisions. After accounting for the fluctuations due to detector resolution and finite number statistics we derive an upper limit on genuine nonstatistical fluctuations, which could be related to a first- or second-order QCD phase transition. Such fluctuations are shown to be very small.
ABSTRACT
In a recent study, administration of the free radical scavenger superoxide dismutase (SOD) improved survival in rats with sepsis when administered two hours before induction of sepsis. The present study was designed to determine whether free radical-induced membrane damage is involved in the pathogenesis of decreased muscle amino acid uptake, noted in sepsis. Additionally, the effect on survival rate of SOD given after the onset of sepsis was studied. Sepsis was induced by cecal ligation and puncture in rats. Amino acid transport in incubated soleus muscles was studied using tritiated alpha-aminoisobutyric acid. Amino acid uptake was significantly reduced in muscle from rats with sepsis. Administration of SOD before induction of sepsis or added in vitro to incubated muscles with sepsis had no effect on alpha-aminoisobutyric acid uptake. Survival rate was not increased when SOD was given two hours after cecal ligation and puncture. The results suggest that free radical-induced membrane damage is not the mechanism of inhibited muscle amino acid transport in sepsis. Since survival was not improved by SOD administered after induction of sepsis, the role of the enzyme in the treatment of sepsis may be questioned.
Subject(s)
Amino Acids/metabolism , Infections/drug therapy , Superoxide Dismutase/therapeutic use , Aminoisobutyric Acids/metabolism , Animals , Biological Transport, Active/drug effects , Blood Glucose/analysis , Drug Evaluation , In Vitro Techniques , Infections/blood , Infections/mortality , Lactates/blood , Male , Muscles/metabolism , Platelet Count , Rats , Rats, Inbred StrainsSubject(s)
Muscle Proteins , Terbium , Troponin , Animals , Binding Sites , Calcium , Circular Dichroism , Kinetics , Magnesium , Muscle Proteins/metabolism , Muscles/metabolism , Protein Binding , Protein Conformation , Rabbits , Spectrometry, Fluorescence , Troponin/metabolismABSTRACT
The interaction of rabbit non-specific IgG and human erythrocyte glycoprotein was investigated using the solvent perturbation difference spectroscopy method. This interaction manifested itself by decreasing accessibility of chromophores to perturbants. Masking of the chromophores was abolished by low detergent concentrations and by changes of native IgG structure by 3 M urea. The sialic acid residues of the glycoprotein were necessary for this effect but probably not due to simple electrostatic interactions. It seems that the IgG-glycoprotein interaction requires intact both--the IgG molecule structure and the structure of the glycoprotein micelle. Interaction of this kind was not observed between glycoprotein and some other proteins as bovine serum albumin, alpha-chymotrypsynogen and human IgA.
Subject(s)
Glycoproteins/blood , Isoantibodies , MNSs Blood-Group System , Animals , Antigen-Antibody Reactions/drug effects , Dimethyl Sulfoxide/pharmacology , Dose-Response Relationship, Immunologic , Ethylene Glycols/pharmacology , Glycoproteins/immunology , Humans , Polysorbates/pharmacology , Protein Conformation/drug effects , Rabbits , Tyrosine , Urea/pharmacologyABSTRACT
Non-ionic detergent, Tween-20, was used in solvent perturbation studies of accessibility of aromatic amino acid residues in rabbit IgG molecules. It has been found that surface aromatic residues are localized in cervices inaccessible to perturbant molecules larger than ca. 10 A in diameter.
Subject(s)
Immunoglobulin G , Animals , Polysorbates/pharmacology , Protein Conformation/drug effects , Rabbits , Spectrophotometry, Ultraviolet , Tryptophan , TyrosineABSTRACT
Human secretory IgA was prepared from colostrum. Different elution diagrams from CM-cellulose were obtained depending on the time of collection of colostrum. In case of early colostrum, collected within 6 hours post partum, two IgA fractions were obtained after chromatography on CM-cellulose. Both fractions have different molecular weights and different amino acid compositions. The results obtained suggest that the first fraction is a dimer of IgA monomers containing J chain with a molecular weight of 330,000 whereas the second fraction having the molecular weight 395,000 daltons is composed of IgA dimer, J chain and SC. When colostrum collected 48 or more hours was used as a source of IgA, only the second IgA fraction was obtained. The problem of SC-free IgA immunoglobulins is discussed.
