Study of the reactione + e −→K + K − in the energy range1350 \leqq \sqrt s \leqq 2400 MeV

Thee ⁺ e ^?→K ⁺ K ^? cross section has been measured from about 750 events in the energy interval \(1350 \leqq \sqrt s \leqq 2400 MeV\) with the DM2 detector at DCI. TheK ^± form factor |F _F ^±| cannot be explained by the ρ, ω, ? and ρ′(1600). An additional resonant amplitude at 1650 MeV has to be added as suggested by a previous experiment.     

Quantum mechanics in Dirac's front form

In 1949 Dirac published a paper in which he proposed various ways to combine special relativity with the Hamiltonian formulation of dynamics; these were referred toas forms and three differentforms, theinstant, thepoint, and thefront forms, were discussed. Dirac considered thefront form to be mathematically the most interesting. Despite this, thefront form appears to have been the least explored. This paper presents the results of a study of quantum mechanics in thefront form.     

An angle resolved electron-ion recoil vector correlation study of alternate ion dissociation channels in A CF3I+

Electron-ion recoil vector correlations are examined for the ionization and subsequent dissociation of A state CF3I+. The magnitude of the electron and fragment ion recoil vectors permits the energetics of two alternative decays to I+ and CF3+ to be compared, while differences between the angular correlations are interpreted as molecule-frame photoelectron angular distributions which, in the I+ channel, are smeared by molecular rotation between ionization and dissociation. Quantitative estimates of sub-ps I+ decay lifetimes are extracted, indicating very different decay rates for the alternative dissociation channels. Surprisingly, the ka1 and ke photoelectron continua exchange polarization dependence in the I+ channel correlations and vibronic interactions are postulated in explanation. This can also rationalize the non-adiabatic A CF3I+-->I+ decay mechanism and the branching competition between the CF3+ and I+ channels.     

High-performance liquid chromatographic assay for the antitumor glycoside phyllanthoside and its stability in plasma of several species

Phyllanthoside is a glycoside isolated from the roots of the Central American tree Phyllanthus acuminatus Vahl with antitumor activity against murine B-16 melanoma and P-388 leukemia. We report a reversed-phase high-performance liquid chromatographic assay for phyllanthoside in plasma using a 25-cm RP-18, 5-micron column with a linear 10-min gradient of 50% to 100% methanol in 0.3 M sodium acetate, pH 4.0, at a flow-rate of 1.5 ml/min. Eluting peaks were detected at 270 nm. The lower limit of sensitivity of the assay for phyllanthoside in 0.5 ml plasma following ethyl acetate extraction at pH 7.0 was 0.25 micrograms/ml and the coefficient of variation at 1 microgram/ml was +/- 7.4%. Phyllanthoside was very rapidly broken down by mouse and rat plasma in vitro to an unidentified less polar metabolite. Formation of this metabolite was completely inhibited by preheating mouse plasma to 100 degrees C for 10 min. When mouse plasma was diluted 1:50 with water the half-life of phyllanthoside disappearance at 37 degrees C was 2.0 min. Breakdown of phyllanthoside in plasma from other species was slower than in mouse and the initial half-life at 37 degrees C in dog plasma was 30 min, in monkey plasma 33 min and in human plasma 38 min. The same less polar metabolite as in mouse plasma was formed slowly by plasma of monkey and dog. Phyllanthoside did not accumulate in human red blood cells. Binding of phyllanthoside to human plasma protein determined by ultrafiltration at 4 degrees C was 70%.     

Gas chromatographic assay for the new antitumor agent sulfamic acid diester (NSC 329680) and its stability in buffer, blood and plasma

A sensitive gas chromatographic assay with electron-capture detection has been developed for sulfamic acid diester (sulfamic acid 1,7-heptanediyl ester, NSC 329680) based on its conversion to 1,7-diiodoheptane in the presence of excess sodium iodide. The assay is linear up to 1 microgram/ml sulfamic acid diester and has a lower limit of detection of 25 ng/ml from 0.5 ml plasma. The coefficient of variation of the assay is 6.4% at 1 microgram/ml and 8.0% at 100 ng/ml. Sulfamic acid diester is relatively stable in 0.9% sodium chloride and 0.1 M sodium phosphate buffers, pH 7.0-9.0, with half-lives greater than 38 h. The major breakdown product of sulfamic acid diester is sulfamic acid 1,7-heptane-monoyl ester. When added to whole blood sulfamic acid diester shows concentration-dependent breakdown. At 50 and 100 micrograms/ml sulfamic acid diester, the half-time in whole blood is 6.9 h and 65% of the drug is sequestered by the blood cells. At 10 micrograms/ml sulfamic acid diester in blood, there is no detectable breakdown of the drug over 24 h and all of the drug is sequestered by the blood cells. Protein binding of sulfamic acid diester in human plasma is 82% at 10 micrograms/ml and 68% at 100 micrograms/ml.     

Synthesis and biological activity of prodrug inhibitors of the thioredoxin-thioredoxin reductase system

A series of palmarumycin prodrugs and water-soluble analogs has been synthesized and assayed for inhibition of the thioredoxin-thioredoxin reductase system. Increased aqueous solubility led to an improved in vivo activity profile.     

Natural product based inhibitors of the thioredoxin-thioredoxin reductase system

Spiroketal naphthodecalins are readily assembled by Barton's base mediated Ullmann binaphthyl ether coupling, Dakin reactions and hypervalent iodine spirocyclization. The core structures can be further diversified by enone addition and Stille coupling reactions. Nanomolar inhibitors for the Trx/TrxR redox control system were prepared by this approach and compared to series of natural product isolates. Cytotoxicity in MCF-7 cell assays ranged from an IC50 of 1.6 to >100 microM.     

Radiative decay ofJ/ψ into γ π+ π−

The radiative decayJ/ψ → γ π⁺ π^? has been studied using the 8.6 millionJ/ψ produced in the DM2 experiment at the DCIe ⁺e^? storage rings at Orsay. The π⁺ π^? mass spectrum shows a cleanf ₂ (1270) signal, and the possible presence of two other states at thef ₂ (1720) andf ₄ (2030) masses. For thef ₂ (1270), the branching ratio BR(J/ψ →γf)xBR(f→π⁺ π^?) is measured to be (7.50±0.30±1.12)×10^?4, and the spin analysis prefers theJ=2 assignment, with helicity parametersx=0.83±0.06 andy=0.01±0.06. The existence of higher mass states is discussed.     

A photoelectron—photoion coincidence study of acetaldehyde and ethylene oxide molecular ions

The dissociations of energy-selected acetaldehyde and ethylene oxide molecular ions have been studied using the photoelectron—photoion coincidence te