Search Results - (Author, Cooperation:E. Stevens)

2014-02-07

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

Amino Acid Motifs ; Animals ; Antibodies, Monoclonal/analysis/immunology ; Antibodies, Neutralizing/analysis/immunology ; Antibodies, Viral/analysis/immunology ; Antigens, Viral/chemistry/immunology ; Crystallography, X-Ray ; *Drug Design ; Enzyme-Linked Immunosorbent Assay ; Epitopes/*chemistry/*immunology ; Macaca mulatta/immunology ; Male ; Mice ; Mice, Inbred BALB C ; Models, Molecular ; Neutralization Tests ; Protein Conformation ; *Protein Stability ; Respiratory Syncytial Virus Vaccines/*chemistry/*immunology ; Respiratory Syncytial Viruses/chemistry/immunology

1089-7690

AIP Digital Archive

Physics

Chemistry and Pharmacology

We report the first measurements of rate constants for formation and reaction of the hydrated-hydride ion H3O−. We studied the Kleingeld–Nibbering reaction [Int. J. Mass Spectrom. Ion Phys. 49, 311 (1983)], namely, dehydrogenation of formaldehyde by hydroxide to form hydrated-hydride ion and carbon monoxide. The OD−+H2CO reaction is about 35% efficient at 298 K, with OD−/OH− exchange occurring in about half the reactions. H3O− was observed to undergo thermal dissociation in a helium carrier gas at room temperature with a rate constant of 1.6×10−12 cm3 s−1. We also studied a new reaction in which H3O− is formed: The association of OH− with H2 in a He carrier gas at low temperatures. The rate coefficient for this ternary reaction is 1×10−30 cm6 s−1 at 88 K. Rate coefficients and product branching fractions were determined for H3O− reactions with 19 neutral species at low temperatures (88–194 K) in an H2 carrier. The results of ion-beam studies, negative-ion photoelectron spectroscopy, and ion-molecule reaction data allow us to specify the hydride–water bond energy D0298(H−−H2O)=14.4±1.0 kcal mol−1 (0.62±0.04 eV). The heat of formation of H3O−, −37.5±1.0 kcal mol−1, and the proton affinity of H3O−, 386.0±1.0 kcal mol−1, are derived from these results. Dissociation of H3O− into OH− and H2 requires 4.5±1.0 kcal mol−1 energy.

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1089-7690

AIP Digital Archive

Physics

Chemistry and Pharmacology

The ion–molecule reaction OH−+H2CO→H3O−+CO has been studied at 300 K with isotopic labeling of reactants. The H3O− product is only observed in small abundance because the ion dissociates into OH−+H2 upon multiple collisions in a helium buffer gas. Without isotopic labeling, the pseudo-first-order kinetics plots for the reactions of OH− with H2CO and OD−+D2CO were found to be curved as a result of the regeneration of OH− or OD− reactant. A scavenger technique was used to remove the H3O− (or D3O−) produced prior to dissociation, to reveal the true first-order attenuation of OH− (or OD−) in reaction with H2CO (or D2CO). The rate constant for the OH−+H2CO reaction is 7.6×10−10 cm3 s−1, and for OD−+D2CO is 5.7×10−10 cm3 s−1. For the isotopically mixed cases OH−+D2CO and OD−+H2CO, the rate constants are equal to 1.3×10−9 cm3 s−1, about twice as large as those for the reactions involving only a single hydrogen isotope, indicating that isotopic exchange is an important process. The rate constants for the thermal dissociation of H3O− and D3O− in helium were found to be 1.6×10−12 and 1.1×10−12 cm3 s−1, respectively, within a factor of 2. The results are discussed in terms of other thermal dissociation reactions of ions.

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1089-7690

AIP Digital Archive

Physics

Chemistry and Pharmacology

Rate coefficients for electron attachment to SF4 and SF6 have been measured over the temperature range 300–550 K using a flowing-afterglow Langmuir-probe apparatus. The 300 K rate coefficient for SF4 is 2.5±0.6×10−8 cm3 s−1, a value 11 times smaller than the corresponding rate for SF6. The attachment rate coefficients for both SF4 and SF6 are nearly independent of temperature up to 500 K, and decline somewhat at still higher temperatures. SF−4 is the only ionic product of attachment to SF4 observed over the entire temperature range. SF−6 and SF−5 are products of attachment to SF6; an "activation energy'' of 0.42±0.02 eV is inferred for SF−5 production.

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1089-7690

AIP Digital Archive

Physics

Chemistry and Pharmacology

Hydroxide ion (HO−) reacts with nitric oxide by slow reactive electron detachment with a rate coefficient ∼4×10−12 cm3 s−1 at 298 K. The detachment process is presumably associative detachment forming nitrous acid and an electron. Observations, data analysis, and alternative explanations for these observations are discussed. The associative detachment reaction was also investigated theoretically through calculations of the geometries, relative energies, and normal-mode vibrational frequencies of the relevant species HO−, HO, NO, cis- and trans-HONO, and cis- and trans-HONO−. These calculations indicate that in the ion HONO−, the cis conformer is more stable, while in the neutral HONO, the trans conformer is more stable. The HO–NO bond in HONO, which is formed in this reaction, is much stronger than the HO−–NO bond in HONO− with an energy of 198.7±1.8 kJ mol−1 for cis-HONO [J. Phys. Chem. Ref. Data 14, 1 (1985)] and 52.2±5 kJ mol−1 for cis-HONO− at 0 K. HONO− is bound with respect to HONO. The adiabatic electron detachment energy resulting from detachment from cis-HONO− forming the same conformer of the neutral molecule cis-HONO is 0.29±0.05 eV. The HO–NO equilibrium bond distance in HONO− is considerably longer than that in HONO, with values of 1.750 and 1.640 A(ring) for trans- and cis-HONO−, respectively, and 1.429 and 1.392 A(ring) for trans- and cis-HONO, respectively. These geometric and energetic characteristics of HONO− and HONO are combined with calculations of relative energies of these species at nonequilibrium/distorted HO–NO bond lengths to give a qualitative picture of the potential energy curves for these species along the reaction coordinate. While no significant energy barrier to autodetachment of HONO− is present, the Franck–Condon wave function overlap for autodetachment is small and is likely the reason for the observed inefficiency. The maximum calculated rate constant for associative detachment is 4×10−12 cm3 s−1, in good agreement with the observed value.

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1089-7690

AIP Digital Archive

Physics

Chemistry and Pharmacology

Photoelectron spectra are reported for the CH2(X˜ 3B1)+e−←CH−2 (X˜ 2B1) and CH2(a˜ 1A1)+e−←CH−2 (X˜ 2B1) transitions of the methylene and perdeuterated methylene anions, using a new flowing afterglow photoelectron spectrometer with improved energy resolution (11 meV). Rotational relaxation of the ions to ∼300 K and partial vibrational relaxation to 〈1000 K in the flowing afterglow negative ion source reveal richly structured photoelectron spectra. Detailed rotational band contour analyses yield an electron affinity of 0.652±0.006 eV and a singlet–triplet splitting of 9.00±0.09 kcal/mol for CH2. (See also the following paper by Bunker and Sears.) For CD2, results give an electron affinity of 0.645±0.006 eV and a singlet–triplet splitting of 8.98±0.09 kcal/mol. Deuterium shifts suggest a zero point vibrational contribution of 0.27±0.40 kcal/mol to the observed singlet–triplet splitting, implying a Te value of 8.7±0.5 kcal/mol. Vibrational and partially resolved rotational structure is observed up to ∼9000 cm−1 above the zero point vibrational level of the 3B1 states, revealing a previously unexplored region of the quasilinear potential surface of triplet methylene. Approximately 20 new vibration-rotation energy levels for CH2 and CD2 are measured to a precision of ∼30 cm−1 in the v2=2–7 region (bent molecule numbering). Bending vibrational frequencies in the methylene anions are determined to be 1230±30 cm−1 for CH− and 940±30 cm−1 for CD−2, and the ion equilibrium geometries are bracketed. The measured electron affinity also provides values for the bond strength and heat of formation of CH−2, and the gas phase acidity of CH3. A detailed description of the new flowing afterglow photoelectron spectrometer is given.

Electronic Resource

0002-9106

Life and Medical Sciences ; Cell & Developmental Biology

Wiley InterScience Backfile Collection 1832-2000

Medicine

1 Ill.

Electronic Resource

1077-3118

AIP Digital Archive

Physics

We report for the first time, the performance of a GaAs/GaAlAs distributed Bragg reflector (DBR) laser using a focused ion beam implanted grating (FIB-DBR). Stripes of Si++ with a period of 2300 A(ring) and a dose ∼1014 cm−2 are directly implanted into the passive large optical cavity layer to provide the distributed feedback. Surface-emitting light from the second-order grating is observed. Threshold current of 110 mA and single DBR mode operation from 20 to 40 °C are obtained. The wavelength tuning rate with temperature is 0.8 A(ring)/°C. The coupling coefficient is estimated to be 15 cm−1. The results show that FIB technology is practical for distributed feedback and DBR lasers and optoelectronic integrated circuits.

Electronic Resource

1398-9995

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Extracts from birch (Betula verrucosa) pollen were prepared at different pH, with constant pH monitoring and adjustment to preset values in the range 5.5-8.5. The total protein content of these extracts was directly correlated with the pH. Coomassie brilliant blue-stained isoelectric focusing and SDS-PAGE gels and immunoblot analysis demonstrated qualitative differences: some proteins were lost while others appeared when pH was changed. At pH 8.5, formerly unknown birch pollen allergens were detected with pi 9, 9.10, and 9.30 by about 30% of birch pollen-sensitive sera. Birch pollen extracts prepared at a pH close to neutrality, namely, 6.5 and 7.5, showed the greatest protein and different allergen diversity. Thus, extraction pH values are necessary to analyze the whole pattern of allergenic components in an extract.

Electronic Resource

1365-3083

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Haptoglobin (Hp) is an acute phase reactant produced by hepatocytes. There is evidence for an immunomodulatory potential of Hp, though there is no clear evidence yet about the mechanisms of this action. We have previously shown that Hp interacts with the β2-integrin CD11b/CD18. In addition, other investigators reported the binding of Hp to B lymphocytes through the CD22 receptor, and to neutrophils through two different receptors.In the present study, we investigated the interaction of haptoglobin with the human mast cell line HMC-1. We report that fluorescein isothiocyanate (FITC)-labelled haptoglobin binds to this cell line and that binding is increased by calcium in a dose- and time-dependent manner. Hp binding sites on HMC-1 were upregulated upon stimulation with phorbol myristate acetate (PMA)/A23187 and after treatment with anti-CD43 and anti-CD44 monoclonal antibodies (MoAbs). HMC-1 cells do not express either CD11b/CD18 or CD22 receptors, indicating that the haptoglobin-binding receptor on this cell line is different from the known receptors. Assessment of cell function showed that Hp inhibits the spontaneous growth of HMC-1 up till 40% at higher Hp concentrations, but it did not exhibit any effect on the expression of CD54 on the release of either tryptase or IL-1ra.In conclusion, haptoglobin binds specifically to human mast cells via a receptor different from CD11b/CD18 and CD22, and may play a role in the modulation of mast cell functions. Exploration of Hp effects in mast cell-dependent diseases such as allergic rhinitis and urticaria seems warranted.

Electronic Resource

1460-9568

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Adult dorsal root ganglia (DRG) have been shown to express a wide range of voltage-gated sodium channel α-subunits. However, of the auxiliary subunits, β1 is expressed preferentially in only large- and medium-diameter neurons of the DRG while β2 is absent in all DRG cells. In view of this, we have compared the distribution of β1 in rat DRG and spinal cord with a novel, recently cloned β1-like subunit, β3. In situ hybridization studies demonstrated high levels of β3 mRNA in small-diameter c-fibres, while β1 mRNA was virtually absent in these cell types but was expressed in 100% of large-diameter neurons. In the spinal cord, β3 transcript was present specifically in layers I/II (substantia gelatinosa) and layer X, while β1 mRNA was expressed in all laminae throughout the grey matter. Since the pattern of β3 expression in DRG appears to correlate with the TTX-resistant voltage-gated sodium channel subunit PN3, we co-expressed the two subunits in Xenopus oocytes. In this system, β3 caused a 5-mV hyperpolarizing shift in the threshold of activation of PN3, and a threefold increase in the peak current amplitude when compared with PN3 expressed alone. On the basis of these results, we examined the expression of β-subunits in the chronic constriction injury model of neuropathic pain. Results revealed a significant increase in β3 mRNA expression in small-diameter sensory neurons of the ipsilateral DRG. These results show that β3 is the dominant auxiliary sodium channel subunit in small-diameter neurons of the rat DRG and that it is significantly upregulated in a model of neuropathic pain.

Electronic Resource

1365-2222

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

It is currently recommended to administer a maintenance dose of 100 μg of venom at 4–6 week intervals for Hymenoptera venom immunotherapy (VIT), Because the optimal duration of therapy is not known, we decided to progressively prolong the interval between maintenance injections instead of accepting the risk of anaphylactic reactions when VIT is discontinued after a predetermined period. We report here on the results of a first phase of this interval extension programme, covering the gradual increase of the interval from 1-12 weeks over 19 months in 178 patients. A 12-week interval maintenance VIT could be achieved in 117/128 (91%) of yellow jacket venom (YJV) and in 35/50(70%) of honeybee venom (HBV) allergic patients. At the lime of the interview these 152 patients had been treated with 12-weekly 100 μg venom injections for an average period of 2 years without any untoward reaction to VIT. During this period of 48 YJV allergy sufferers experienced 77 field re-stings without systemic reaction (SR), and 17 HBV allergic subjects were restung at least 213 times in total, with one patient developing a very large local reaction and one a mild systemic reaction. In 26 of the 17S patients the interval of 12 weeks was not reached for various reasons, with a higher failure rate among the HBV allergic patients. Most Hymenoptera venom allergic patients can thus be safely and effectively treated with 12-weekly injections of 100 μg venom.

Electronic Resource

1365-2222

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

As unusually high frequency of decreased haptoglobin levels in patients with asthma and/or rhinitis is described. The condition is significantly associated with haptoglobin 2-2 phenotype. Decreased haptoglobin levels are more frequently associated with young age, atopic antecedents, positive skin tests for pollens, higher IgE and higher RAST activity for pollens and housedust mite.Whether the association of decreased haptoglobin levels and IgE-mediated. respiratory disease has a physiopathological significance or is solely the expression of a common genetic determinate remains to be investigated.

Electronic Resource

1365-2222

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Background Hymenoptera stings can induce specific IgE (sIgE) to carbohydrate determinants (CD) on venom glycoproteins that cross-react with CD in pollen. sIgE to such cross-reacting CD (CCD) are believed to have little or no biological activity and thus may cause misdiagnosis of pollen sensitization after a sting.Objective To determine the prevalence of multiple false positive CAP results to pollen because of sting induced anti-CCD sIgE in Hymenoptera venom (HV) allergic patients and to investigate the association of such anti-CCD sIgE with features of ‘atopy’.Methods Skin prick tests (SPT) and CAP tests with grass, tree and weed pollen and with house dust mite (HDM) were carried out prospectively in 259 HV allergic patients and CAP tests with honeybee (HBV) and yellow jacket (YJV) venom were performed. Patients with negative pollen SPT associated with positive CAP tests to all three pollen groups were operationally defined as ‘CCD positive’. We investigated in selected ‘CCD positive’ patients the presence of anti-CCD sIgE by CAP tests with bromelain and studied the identity of CD in HVs and pollen by mutual sIgE inhibition tests with CD from proteinase treated HBV (HBV-CD) and Lolium perenne (Lol-CD) extracts.Results sIgE to all three pollen groups without positive SPT or history was found in 16% of 259 patients. The presence of anti-CCD sIgE was substantiated by positive CAP tests with bromelain in 14/14 and by inhibition of all pollen CAP tests with HBV-CD in 8/9 and with Lol-CD in 2/2 patients. Double venom (DV) positive CAP tests were present in 93% of ‘CCD positive’ patients and were in some associated with DV skin test positivity and allergy. The prevalence of ‘CCD positivity’ was significantly higher among HBV (23%) than among YJV (11%) allergic patients, but was also unexpectedly high among those with DV allergy (47%). ‘CCD positive’ patients were younger, had a higher total IgE and more sIgE to HDM than ‘CCD negative’ patients.Conclusion We have shown that the risk in HV allergic patients for misdiagnosis of multivalent pollen sensitization is 16%, and we have confirmed that sting induced anti-pollen sIgE are directed to similar CD in venoms and pollen. We found evidence that the recognition of CCD might be related to the ‘atopic’ trait. Importantly, a positive bromelain CAP test does not exclude clinical reactivity to both venoms in ‘CCD positive’ HV allergic patients.

Electronic Resource

1365-2222

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

We report a first case of occupational allergy to chicory (Cichorium intybus) in a vegetable wholesaler. Symptoms occurred after oral, cutaneous or inhalatory exposure. The patient also reported reactions after ingestion of botanically related endive (Cichorium endivia) and lettuce (Lactuca sativa.) We identified the responsible allergen by SDS-PAGE and immunoblot to be a 48-kDa protein, confined to the non-illuminated parts of the plants. No cross-reactivity was found with mugwort (Artemisia vulgaris) ryegrass (Lolium perenne) and birch (Betula verrucosa) pollen, which suggests that the vegetable is the primary allergenic material.

Electronic Resource

1365-2222

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

The clinical profile of anaphylactic reactions to bumble bees is described and successful immunotherapy with honey bee venom in seven bumble bee allergic patients is reported. The cause of the high frequency of sensitization to pollen in these patients is discussed.

Electronic Resource

1365-2222

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Background Development of allergy to natural rubber latex in spina bifida patients is determined by several risk factors, such as age, number of interventions and atopic disease that are, however, interdependent. Furthermore, several diagnostic procedures have been analysed, but a comprehensive analysis of their diagnostic significance is lacking.Objective To determine the independent major risk factor(s) for development of natural rubber latex allergy and the most valuable diagnostic procedure.Methods In aselectively collected spina bifida patients, we correlated existing natural rubber latex allergy with age, sex, atopy and the number of hospitalizations and of surgical interventions in appropriately matched subgroups. Allergy to natural rubber latex was established by application of a latex glove fragment on the skin. Skin-prick tests with glove eluate, a natural latex extract and a commercial latex extract were carried out as were specific IgE measurements by radioimmuno assay (RAST-CAP). The results of the latex application test are compared with the other diagnostic methods.Results Out of 74 fully evaluated patients, 17 had a positive application test. The number of surgical interventions correlates strongly with the presence of natural rubber latex allergy (P 〈 0.0002), independent of age, sex and presence of atopy. Skin-prick tests with unstandardized allergens made from known high allergenic latex gloves represent the most sensitive diagnostic method, with the highest negative predictive value and a specificity of 0.95. RAST-CAP was the next best method with a specificity of 0.93, a sensitivity of 0.89 and a negative predictive value of 0.97.Conclusion The number of surgical interventions is the major independent determining factor for allergy to natural rubber latex in spina bifida patients. Unstandardized skin-prick tests are the most sensitive and specific diagnostic tool, but RAST-CAP is almost equally performant and therefore a valid alternative.

Electronic Resource

1095-8649

Blackwell Publishing Journal Backfiles 1879-2005

Biology

Rainbow trout were sprint-trained (30 s duration) once or twice on alternate days for a period of 6 weeks. Swim speed for the first 10 s of a training bout averaged 11.4 bls for group 2 (trained once) and 10.2 bl s −1 for group 3 (trained twice). Food consumption, growth rate and conversion efficiency were measured over 2-week periods. Food consumption was 31-38% less for the trained groups than for the control group (group 1). The growth rates of control and trained fish increased gradually over the training period. The growth rate of trained fish was always significantly less (48-81%) than that of control fish. Although conversion efficiency was significantly less for group 3 at the beginning of training, no other significant differences in conversion efficiency were recorded. Maintenance rations were high in the initial period for all groups, but were lower than the initial values in the second and third periods. While condition factor was significantly lower for the trained groups, there were no differences in percent tissue protein, lipid, or moisture.

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1095-8649

Blackwell Publishing Journal Backfiles 1879-2005

Biology

Growth hormone transgenic Atlantic salmon Salmo salar reared at 12–13°C were F2 generation derived, using eggs from a transgenic F1 female and fertilized with milt from a non-transgenic male. At the time of tissue sampling the transgenic salmon were growing 1·6 times faster than control salmon. Transgenic salmon tended to have more intestinal folds that were longer than those of control salmon. Consequently, the transgenic salmon had a larger digestive surface area both in the anterior intestine (surface area 1·5 times control) and in the pyloric caeca (surface area 1·2 times control). Most morphological features of the intestine and of the pyloric caeca of transgenic salmon were larger than those of control salmon; in particular, the surface area of the anterior intestine was concordant with the growth rate difference.

Electronic Resource

1095-8649

Blackwell Publishing Journal Backfiles 1879-2005

Biology

Growth was measured in dechorionated and chorionated embryos of rainbow trout Oncorhynchus mykiss exposed to three oxygen treatments: hypoxia, normoxia and hyperoxia (nominally 5, 10 and 15 mg l−1). Dechorionated embryos grew faster than chorionated ones in all three oxygen treatments. Similar patterns, however, were found in both dechorionated and chorionated groups; embryos exposed to hypoxia grew less than normoxic and hyperoxic exposed embryos. Moreover, there was no significant interaction between the effect of oxygen levels and presence or absence of the chorion on growth after hatching. These results suggest that the effect of oxygen on growth was not affected by the presence of the chorion.

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