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A Olin

Publications and source records attributed to A Olin.

At least 19 recordsLinked to original sources
PubMed2006

Measurement of the Ec.m. = 184 keV resonance strength in the 26gAl (p, gamma)27 Si reaction.

The strength of the Ec.m. = 184 keV resonance in the 26gAl(p, gamma)27 reaction has been measured in inverse kinematics using the DRAGON recoil separator at TRIUMF's ISAC facility. We measure a value of omega gamma = 35 +/- 7 microeV and a resonance energy of Ec.m. = 184 +/- 1 keV, consistent with p-wave proton capture into the 7652(3) keV state in 27Si, and discuss the implications of these values for 26GAl nucleosynthesis in typical oxygen-neon white-dwarf novae.

Journal Article↗
PubMed2005

Evidence for a kaon-bound state K(-)pp produced in K(-) absorption reactions at rest.

We have searched for a deeply bound kaonic state by using the FINUDA spectrometer installed at the e(+)e(-) collider DAPhiNE. Almost monochromatic K(-)'s produced through the decay of phi(1020) mesons are used to observe K(-) absorption reactions stopped on very thin nuclear targets. Taking this unique advantage, we have succeeded to detect a kaon-bound state K(-)pp through its two-body decay into a Lambda hyperon and a proton. The binding energy and the decay width are determined from the invariant-mass distribution as 115(+6)(-5)(stat)(+3)(-4)(syst) MeV and 67(+14)(-11)(stat)(+2)(-3)(syst) MeV, respectively.

Journal Article↗
PubMed2005

Measurement of the Michel parameter rho in muon decay.

The TWIST Collaboration has measured the Michel parameter rho in normal muon decay, mu(+)--> e(+)nu(e)nu (mu). In the standard model, rho = 3/4. Deviations from this value imply mixing of left- and right-handed muon and electron couplings. We find rho=0.750 80+/-0.000 32(stat) +/- 0.000 97(syst) +/- 0.000 23, where the last uncertainty represents the dependence of rho on the Michel parameter eta. This result sets new limits on the W(L)-W(R) mixing angle in left-right symmetric models.

Journal Article↗
PubMed2003

21Na(p,gamma)22Mg reaction and oxygen-neon novae.

The 21Na(p,gamma)22Mg reaction is expected to play an important role in the nucleosynthesis of 22Na in oxygen-neon novae. The decay of 22Na leads to the emission of a characteristic 1.275 MeV gamma-ray line. This report provides the first direct measurement of the rate of this reaction using a radioactive 21Na beam, and discusses its astrophysical implications. The energy of the important state was measured to be E(c.m.)=205.7+/-0.5 keV with a resonance strength omegagamma=1.03+/-0.16(stat)+/-0.14(sys) meV.

Journal Article↗
PubMed2001

Measurement of the resonant d(mu)t molecular formation rate in solid HD.

Measurements of muon-catalyzed dt fusion ( d(mu)t-->4He + n + mu(-)) in solid HD have been performed. The theory describing the energy dependent resonant molecular formation rate for the reaction (mu)t + HD-->[(d(mu)t)pee](*) is compared to experimental results in a pure solid HD target. Constraints on the rates are inferred through the use of a Monte Carlo model developed specifically for the experiment. From the time-of-flight analysis of fusion events in 16 and 37 microg x cm(-2) targets, an average formation rate consistent with 0.897+/-(0.046)(stat)+/-(0.166)(syst) times the theoretical prediction was obtained.

Journal Article↗
PubMed2000

Resonant formation of d&mgr;t molecules in deuterium: An atomic beam measurement of muon catalyzed dt fusion

Resonant formation of d&mgr;t molecules in collisions of muonic tritium ( &mgr;t) on D2 was investigated using a beam of &mgr;t atoms, demonstrating a new direct approach in muon catalyzed fusion studies. Strong epithermal resonances in d&mgr;t formation were directly revealed for the first time. From the time-of-flight analysis of 2036+/-116 dt fusion events, a formation rate consistent with 0.73+/-(0.16)(meas)+/-(0.09)(model) times the theoretical prediction was obtained. For the largest peak at a resonance energy of 0.423+/-0.037 eV, this corresponds to a rate of (7.1+/-1.8)x10(9) s(-1), more than an order of magnitude larger than those at low energies.

Journal Article↗
PubMed1999

Purification of a 38-kDa protein from rabbit reticulocyte lysate which promotes protein renaturation by heat shock protein 70 and its identification as delta-aminolevulinic acid dehydratase and as a putative DnaJ protein.

We reported recently that a rabbit reticulocyte 66-kDa protein (termed RF-hsp 70 by our laboratory and p60 and hop by others) functions as a hsp 70 recycling protein and markedly enhances the renaturation of luciferase by hsp 70 (Gross, M., and Hessefort, S. (1996) J. Biol. Chem. 271, 16833-16841). In this report, we confirm that the ability of RF-hsp 70 to promote the conversion of hsp 70. ADP to hsp 70.ATP, thus enhancing the protein folding activity of hsp 70, is caused by the purified 66-kDa protein and not by a trace DnaJ/hsp 40 protein contaminant. To determine the relationship between RF-hsp 70 and the DnaJ/hsp 40 heat shock protein family, which also enhances protein renaturation by hsp 70, we purified a 38-kDa protein from rabbit reticulocyte lysate based upon its ability to stimulate renaturation of luciferase by hsp 70. Partial amino acid sequencing of this 38-kDa protein has indicated, unexpectedly, that it is the enzyme delta-aminolevulinic acid dehydratase (ALA-D) and that it does not contain detectable sequences corresponding to the DnaJ/hsp 40 protein family. In addition, immunoblot analysis with a polyclonal antibody made to HeLa cell hsp 40 (from StressGen) confirms that our purified ALA-D contains no hsp 40, although hsp 40 is present in relatively crude rabbit reticulocyte protein fractions. Rabbit reticulocyte ALA-D is about as active in converting delta-aminolevulinic acid to porphobilinogen and as Zn2+-dependent as ALA-D purified from other sources. Rabbit reticulocyte ALA-D stimulates the renaturation of luciferase by hsp 70 up to 10-fold at concentrations that are the same as or less than that of hsp 70, and it has no renaturation activity in the absence of hsp 70. The renaturation effect of ALA-D is additive with that of RF-hsp 70 at limiting or saturating concentrations of each, and, unlike RF-hsp 70, ALA-D does not promote the dissociation of hsp 70.ADP in the presence of ATP. The renaturation-enhancing effect of ALA-D may be caused by a region near its carboxyl terminus which has sequence homology to the highly conserved domain of the DnaJ protein family, which is similar to the sequence homology between this domain and a carboxyl-terminal region in auxilin, a DnaJ-like protein that requires this region for its hsp 70-dependent function (Ungewickell, E., Ungewickell, H., Holstein, S. E. H., Lindner, R., Prasad, K., Barouch, W., Martin, B., Greene, L. E., and Eisenberg, E. (1995) Nature 378, 632-635).

Amino Acid Sequence↗
PubMed1996

Extensive sequencing of tryptic peptides of a rabbit reticulocyte 66-kDa protein that promotes recycling of Hsp 70. Homology To stress-related proteins.

Trypsinization and sequence analysis of the 66-kDa rabbit reticulocyte protein (RF-hsp 70), shown in the preceding article to function as a recycling protein for hsp 70, demonstrates striking similarity to the transformation-sensitive human protein IEF SSP 3521 (Honoré, B., Leffers, H., Madsen, P., Rasmussen, H. H., Vandekerckhove, J., and Celis, J. E.(1992) J. Biol. Chem. 267, 8485-8491) and mouse extendin (Blatch, G. L., Lassle, M., Takatori, T., Gandhi, T., Kundra, V., and Zetter, B. R.(1995) Proc. Am. Assoc. Cancer Res. 36, 68). The human and mouse proteins share 97% sequence identity, and sequencing of 20 polypeptides (225 residues) from RF-hsp 70 reveals only 10 differences between the rabbit and human proteins and 13 differences between the rabbit and mouse proteins (96 and 94% identity, respectively). In addition, all three proteins are of similar size, and each contains 11 cysteines. These findings strongly suggest that these three proteins are homologs of the same activity. All differences (but one) between the human and mouse proteins occur within the amino-terminal half of the protein, and there is only one difference among 121 sequenced residues between RF-hsp 70 and the human or mouse protein which occurs within the carboxyl-terminal 70% of the molecule. In addition, where partial sequences of RF-hsp 70 and p60, a chick oviduct protein that shows 70% identity to the human protein (Smith, D. F., Sullivan, W. P., Marion, T. N., Zaitsu, K., Madden, B., McCormick, D. J., and Toft, D. O. (1993) Mol. Cell. Biol. 13, 869-876), overlap (a total of 54 residues), RF-hsp 70 and chick p60 show 78% sequence identity. Studies of the initial digestion of RF-hsp 70 by trypsin indicate that it is first converted to 58- and 54-kDa components, each of which is then converted to a 43-kDa polypeptide. This 43-kDa component is located in the human and mouse proteins at position 124 to about 470. It is converted subsequently to a 31-kDa polypeptide by trypsin hydrolysis at position 207. This 31-kDa component is finally split into 17- and 14-kDa polypeptides that are located at positions 208 to approximately 351 and 352 to approximately 470, respectively. The 14-kDa polypeptide is relatively resistant to further digestion with trypsin, and seven tryptic peptides from other parts of RF-hsp 70 contain internal lysine and/or arginine residues (as do several tryptic peptides produced from IEF SSP 3521 and chick p60). Both features may be due to interference with trypsin action by secondary structure in the protein, since trypsinization of reduced and carboxymethylated RF-hsp 70 results in hydrolysis of the 14-kDa polypeptide and reduces the level of peptides that contain internal lysine and/or arginine, although it does not eliminate them.

Amino Acid Sequence↗
PubMed1994

Control of protein synthesis by hemin. Purification of a rabbit reticulocyte hsp 70 and characterization of its regulation of the activation of the hemin-controlled eIF-2(alpha) kinase.

We have purified a soluble rabbit reticulocyte protein, previously termed the supernatant factor, that reverses the inhibition of protein synthesis in hemin-deficient lysate by promoting the inactivation of the hemin-controlled eIF-2 alpha kinase (HCR) mediating the effect of hemin deficiency. We have identified the supernatant factor as a member of the heat shock protein 70 family, denoted hsp 70(R), based upon its size (72 kDa), specific reaction to a monoclonal antibody against eukaryotic hsp 70, strong binding affinity for ATP, and endogenous ATPase activity. We have investigated the role of hsp 70(R) and hemin in the regulation of the activation of HCR from its latent precursor (ProHCR) and the translational control of protein synthesis in rabbit reticulocyte lysate. We find that autophosphorylation of Pro-HCR is reduced by about 75% by adding saturating hsp 70(R) and almost completely reduced by adding either saturating hemin or limiting hemin plus limiting hsp 70(R). In contrast, autophosphorylation of HCR, which is similar in magnitude to that of ProHCR, is unaffected by adding either saturating hsp 70(R), saturating hemin, or limiting amounts of both. The activation of HCR (measured by inhibition of protein synthesis) from isolated ProHCR is completely prevented by hsp 70(R) in the presence, but not absence, of dithiothreitol. This suppression appears to be due to the association of hsp 70(R) with ProHCR, since hsp 70(R) action is prevented by ATP/Mg2+ and because activation of HCR from less purified ProHCR, that has associated hsp 70(R), is suppressed by dithiothreitol alone. This association is confirmed by sucrose gradient centrifugation, which shows co-sedimentation of some hsp 70(R) with ProHCR following preincubation together that is prevented by ATP/Mg2+ and does not occur after conversion of ProHCR to HCR. Limiting hsp 70(R) reduces the concentration of hemin required to prevent activation of HCR from isolated ProHCR from 0.75 to 0.15 microM and the optimal hemin concentration needed to maintain protein synthesis in reticulocyte lysate from 25 to 10 microM. Limiting hsp 70(R) also allows the delayed addition of hemin to suppress activation of HCR from ProHCR and to reverse inhibition of protein synthesis in hemin deficient lysate. The association of hsp 70(R) with ProHCR also underlies the observation that much more protein is synthesized in reticulocyte lysate in the absence of hemin at 25 degrees C than at temperatures of 30 degrees C or greater. These observed effects may be specific to hsp 70(R), since they are not observed with rabbit reticulocyte eIF-2 or eIF-2B, and since the comparable hsp 70 from bovine brain is incapable of maintaining or restoring protein synthesis in hemin-deficient lysate.

Animals↗
PubMed1994

New carborane-based compounds for boron neutron capture therapy: binding and toxicity of ANC-1, DAC-1 and B-Et-11-OMe in cultured human glioma and mouse melanoma cells.

The toxicity and binding of the three new carborane based compounds: 2 (1,2-dicarba-closo-dodecaborane (12)-1(-yl-methoxy)-2-(3-amino-propyl))-1,3-propanediol, called DAC-1; 7-(3-amino-propyl)-7,8-dicarba-nido-undecarborate (-1) called ANC-1; and rac-1-(9-o-carboranyl)-nonyl-2-methyl-glycero-3- phosphocholine, called B-Et-11-OMe, were analyzed with cultured human glioma cells, U-343MGa, and mouse melanoma cells, B16, as biological models. The previously developed compound di-sodium undecahydro-mercapto-closo-dodecarborate (BSH), which is tested for therapy of malignant gliomas, was analyzed for comparison. In the toxicity tests the cells were exposed to the substances at cell culture medium concentrations in the range 0-50 ppm boron for 1 or 20 h and thereafter analyzed regarding growth. Growth-disturbing effects were seen for the two compounds DAC-1 and B-Et-11-OMe at the concentrations corresponding to 15 and 50 ppm boron, respectively. The compounds ANC-1 and BSH showed no growth-disturbing effects at the tested concentrations. In the binding tests, the cells were incubated for 20 h at about the highest compound concentrations that did not cause growth disturbances. The boron content in the cells was then determined by inductively coupled plasma-atomic emission spectrometry (ICP-AES) and in some cases ICP-mass spectrometry (ICP-MS). The most extensive binding was seen for DAC-1 and B-Et-11-OMe, which accumulated boron to about 100 and 60 times, respectively, compared with the concentration in the culture medium. The compound ANC-1 also accumulated boron in the cells but the boron could be easily washed out indicating no or only a weak binding. BSH did not accumulate. Further analysis should be made regarding biological properties such as intracellular compartmentalization, metabolic interference and tumor specificity of the compounds DAC-1 and B-Et-11-OMe.

Animals↗