A cryogenic radio-frequency ion trap for quantum logic spectroscopy of highly charged ions.

A cryogenic radio-frequency ion trap system designed for quantum logic spectroscopy of highly charged ions (HCI) is presented. It includes a segmented linear Paul trap, an in-vacuum imaging lens, and a helical resonator. We demonstrate ground state cooling of all three modes of motion of a single 9Be+ ion and determine their heating rates as well as excess axial micromotion. The trap shows one of the lowest levels of electric field noise published to date. We investigate the magnetic-field noise suppression in cryogenic shields made from segmented copper, the resulting magnetic field stability at the ion position and the resulting coherence time. Using this trap in conjunction with an electron beam ion trap and a deceleration beamline, we have been able to trap single highly charged Ar13+ (Ar XIV) ions concurrently with single Be+ ions, a key prerequisite for the first quantum logic spectroscopy of a HCI. This major stepping stone allows us to push highly-charged-ion spectroscopic precision from the gigahertz to the hertz level and below.

Heterophyle antibodies causing false positive radio-immunoassay results. A case report.

A case report of falsely elevated serum hormone values measured by radio-immunoassay (RIA) is described. The radio-immunoassays concerned have a first antibody raised in rabbits and mostly a separation technique based on a second antibody-solid phase system. The presence of heterophyle (anti-rabbit) antibodies in patients' serum is proved.

Evaluation of radioimmunoassays using mono- and polyclonal antibodies for the quantitation of human chorionic gonadotropin in early pregnancy.

Five commercial kits for the quantitative determination of human chorionic gonadotropin (hCG) were evaluated for use in an In Vitro Fertilization program. We focused on practicability, precision, sensitivity and the early detection of pregnancy. The IRE method uses purified antiserum against complete hCG and requires overnight incubation. Precision is poor but hCG results agree closely with the other assays. Three other kits use a beta-subunit specific antiserum (Amersham, Becton-Dickinson, Clinical Assays). All these assays have acceptable precision especially in their mid-range. The Amersham assay has the shortest assay time, while the Clinical Assays method requires the least manipulation. The Becton Dickinson assay is precise, less sensitive and has the highest frequency of slightly elevated hCG levels in males and non pregnant females. The Hybritech kit is an immunoradiometric assay based on two monoclonal antibodies. It was tested with a two-step incubation procedure needing a longer assay time than the beta-subunit specific assays but it has the best precision at low hCG levels and is the most sensitive test with the least interference in samples obtained from males and non-pregnant females. For the early detection of pregnancy all assays performed equally well.

Evaluation of commercially available radioimmunoassays for the determination of luteinizing hormone in serum and urine. Application for the detection of endogenous rise of luteinizing hormone in a in vitro fertilization program.

Three commercially available RIA kits for serum and urinary LH were assessed for their usefulness to detect endogenous LH rise in patients receiving ovarian stimulation as part of an in vitro fertilization treatment for infertility. Prerequisites included a turn-around time of 5 hours for an assay of 100 tubes. The following parameters were evaluated: reproducibility of standard curve, sensitivity, precision profile, within- and between-assay precision, analytical drift, recovery and linearity. The Amerlex LH RIA kit was selected because of superior precision profiles, higher precision and better recovery tests.

Preferential stimulation by aurintricarboxylic acid of DNA-dependent RNA polymerase II activity in isolated larval nuclei of Artemia salina.

Aurintricarboxylic acid was found to stimulate preferentially RNA polymerase II activity in isolated nuclei of Artemia salina larvae. Studies on the in vitro transcription of a homologous chromatin indicate that this dye induces changes in the chromatin so as to enhance its template capacity for free RNA polymerase. Both free RNA polymerases I and II are equally sensitive to this dye in the absence of chromatin template. RNA polymerase II, however, becomes highly resistant to aurintricarboxylic acid when it is actively transcribing the chromatin template, whereas RNA polymerase I remains extremely sensitive even in the transcription complex. Therefore, in isolated nuclei, a preferential stimulation of alpha-amanitin-sensitive, but not-resistant RNA synthesis by aurintricarboxylic acid can be observed.

Biophysical characterization of Artemia salina (L.) extracellular haemoglobins.

Sedimentation coefficients (s0 20,w) of 11.57 +/- 0.10 S and 11.52 +/- 0.09 S were assigned for Artemia salina (L.) extracellular haemoglobins II and III respectively. These values are not significantly different. The molecular weights, M0w and M0z, of the native haemoglobins as determined by the high-speed sedimentation-equilibrium method were for haemoglobin II 239 400 +/- 7200 and 240 400 +/- 2600 respectively, and for haemoglobin III 216 300 +/- 6500 and 219 300 +/- 4500 respectively. The observed increase of Mapp. with concentration suggested that association was occurring over the concentration range investigated. Exposure of haemoglobin II to either 6 M-guanidinium chloride or to low pH (pH 4) resulted in dissociation to units of approximately half the size of the native protein, with molecular weights approx. 115 000. Electron-microscopic observations indicated a molecular structure composed of two stacked lobed discs. These results strongly support the dimeric model for Artemia haemoglobins proposed by Moens & Kondo [(1978) Eur. J. Biochem. 82, 65-72].

Oxygen-binding characteristics of three extracellular haemoglobins of Artemia salina.

The oxygen-binding characteristics of the three extracellular haemoglobins of brine shrimp (Artemia salina) were studied in vitro by using highly purified preparations. Haemoglobin I is induced last in the development of brine shrimps when functional gills are formed. It has the lowest oxygen affinity (p(50) 5.34mmHg), an intermediate Bohr effect (ø -0.09 at 20 degrees C) above pH8 and a temperature-sensitivity (DeltaH -44.8 to -45.6kJ/mol at pH8-9) comparable with those observed with other invertebrate haemoglobins [Weber & Heidemann (1977) Comp. Biochem. Physiol. A57, 151-155]. Haemoglobin II, which is the first to be induced, soon after hatching of nauplius larvae, persists generally throughout the whole adult life. It has an intermediate oxygen affinity (p(50) 3.7mmHg), the highest Bohr effect (ø -0.21 at 20 degrees C) above pH8 and a similar temperature-sensitivity (DeltaH -46.0 to -54.8kJ/mol at pH8-9) as haemoglobin I. However, haemoglobin III, which is induced second several hours after the induction of haemoglobin II but disappearing from the haemolymph in the middle of adult life, has the highest oxygen affinity (p(50) 1.8mmHg), the lowest Bohr effect (ø -0.03 at 20 degrees C) above pH8.5 and a high resistance against temperature variation between 10 and 25 degrees C at pH8.5-9 (DeltaH -22.6 to -23.0kJ/mol). At pH7.5-8, haemoglobin III exhibits a similar temperature-sensitivity under 30 degrees C as do other haemoglobins. All three haemoglobins have a rather low co-operativity, with Hill coefficients (h 1.6-1.9 at pH8.5), which are dependent on both pH and temperature. The highest co-operativity was observed at 20 degrees C and pH9 for haemoglobins I and II, whereas it was at 27 degrees C and pH8.5 for haemoglobin III. Thus the oxygen-binding behaviour of haemoglobin III in vitro is significantly different from those of haemoglobins I and II and indicates possibly its specific physiological role in vivo in the adaptive process in the natural environment.

The structure of Artemia sp. haemoglobins-I. Isolation and characterization of oxygen binding domains obtained by limited tryptic digestion.

Limited tryptic digestion of the extracellular haemoglobins of the crustacea Artemia sp. result in series of discrete fragments which are multiples of 16,000 d. 2. These 16,000 d fragments, together with 50,000 d and 80,000 d fragments have similar amino acid composition and tryptic peptide maps as the intact globin chains. 3. The haem content of the 16,000 d fragments is the same as this of the intact pigment and they can bind oxygen in a non cooperative way. 4. These results strongly support that the 16,000 d fragments represent structural and functional units or domains from which the globin chains are built up.