Search Results - (Author, Cooperation:S. Reimann)

2012-03-01

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

1365-2133

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

A high incidence of severe pruritus had been observed after the administration of hydroxyethyl starch (HES) on account of plasma volume substitution and improvement of the microcirculation. The aim of this study was to elucidate the possible pathomechanisms of HES-induced itching. Sking biopsies were taken from 93 patients, half of them presenting with pruritus, who received HES of various preparations and cumulative dosages. The samples were subjected to immunoelectron microscopical investigation using an antibody highly specific for HES. After infusioin therapy with HES, formation of intracytoplasmic storage vacuoles in the skin could be demonstrated in all patients. A dose- dependent uptake of HES was first detectable in macrophages and, thereafter, in endothelial and epithelial cells. Consecutive control biopsies taken from single patients revealed a subsequent reduction of the vacuoles, in size and number, within 3 years, thus indicating a regular cutaneous metabolism of HES. Patients suffering from pruritus consistently showed additional deposition of HES in small peripheral nerves. HES-reactive vacuoles could be demonstrated in the Schwann cells of unmyelinated, as well as small myelinated, nerve fibres, and in endoneural and perineural cells. Neural devacuolization paralleled the clinical improvement in the symptoms. In conclusion, HES deposits in cutaneous nerves, as a consequence of a higher cumulative dosage, may account for the itching seen after HES infusion.

Electronic Resource

1089-7550

AIP Digital Archive

Physics

The electrical characteristics of shallow etched GaAs/GaAlAs quantum point contacts (QPCs) of various shapes have been studied as a function of temperature above 0.3 K. Quantized conductance was observed up to 36 K, and from the temperature dependence of the conductance staircase we find energy separations between the lowest one-dimensional subbands up to 20 meV. This value exceeds the highest values so far reported for laterel QPC constrictions in GaAs/GaAlAs heterostructures. In addition, very well behaved quantized conductance plateaus were observed at the lowest temperatures. © 1998 American Institute of Physics.

Electronic Resource

1365-2222

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Background Previous studies have shown a 10-fold discrepancy of self-reported food-induced symptoms and physician-diagnosed food hypersensitivity. Little information is available on the prevalence of food hypersensitivity in unselected paediatric populations. No data were available for German children.Objective To study the perception of food-induced symptoms in the paediatric population, to investigate the allergens accused, to objectify patients' reports, and to identify subgroups at risk of having food-induced allergy (FA) or non-allergic food hypersensitivity (NAFH) reactions.Methods This paper presents the data of the paediatric group (0–17 years) of a representative, randomly sampled, cross-sectional population-based survey studying 13 300 inhabitants of the German capital city Berlin regarding food-related symptoms. Instruments included mailed questionnaires, structured telephone interviews, physical examination, skin-prick tests, specific serum IgE and standardized, controlled and blinded oral food challenges.Results Two thousand three hundred and fifty-four individuals were contacted by mailed questionnaire, 739 (31.4%) responses could be fully evaluated. Four hundred and fifty-five (61.5%) participants reported symptoms related to food ingestion, 284 (38.4%) affirmed reproducible symptoms in the standardized telephone interview. One hundred and eighty-four (24.8%) individuals were fully examined. Reproducible symptoms to food were found in 31 (4.2%) children and adolescents: 26 (3.5%) showed symptoms of FA and five (0.7%) of NAFH. The oral allergy syndrome was most often observed. Foods most commonly identified by oral challenges were apple, hazelnut, soy, kiwi, carrot and wheat.Conclusion: The perception of food-related symptoms is common among children and adolescents from the general population. Self-reports could be confirmed in around one out of 10 individuals, still resulting in 4.2% of proven clinical symptoms. However, most reactions were mild and mainly because of pollen-associated FA, while NAFH reactions were less common. Severe IgE-mediated FA was observed in individuals with pre-existing atopic disease, who should be fully investigated for clinically relevant FA.

Electronic Resource

1398-9995

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Objective:  A population study was performed to identify the prevalence of all kinds of adverse reactions to food.Methods:  In a representative cross-sectional survey performed in 1999 and 2000 in Berlin, 13 300 inhabitants of all ages were addressed by questionnaire. This questionnaire was answered by 4093 persons. All respondents mentioning any sign of food intolerance or the existence of allergic diseases (n = 2298) were followed up by telephone and, in case food intolerance could not be ruled out by patient history, were invited to attend to the clinic for personal investigation including double-blind, placebo-controlled food challenge tests (DBPCFC).Results:  The self-reported lifetime prevalence of any adverse reaction to food in the Berlin population (mean age 41 years) was 34.9%. Eight hundred and fourteen individuals were personally investigated according to the guidelines. The point prevalence of adverse reactions to food confirmed by DBPCFC tests in the Berlin population as a mean of all age groups was 3.6% (95% confidence interval [3.0–4.2%]) and 3.7% in the adult population (18–79 years, 95% confidence interval [3.1–4.4.%]). Two and a half percent were IgE-mediated and 1.1% non-IgE-mediated, females were more frequently affected (60.6%). Based on a statistical comparison with available data of adults from the nationwide German Health Survey from 1998, adverse reactions to food in the adult population of Germany (age 18–79) were calculated with 2.6% [2.1–3.2%]).Conclusions:  The study gives for the first time information about the point prevalence of both immunological and nonimmunological adverse reactions to food and underlines the relevance of this issue in public health. The data also show that an individualized stepwise approach including provocation tests is mandatory to confirm the diagnosis.

Electronic Resource

1435-1536

Silicasuspensions ; polyelectrolytes ; adsorption ; flocculation ; peptization

Springer Online Journal Archives 1860-2000

Chemistry and Pharmacology

Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Abstract The possibility to concentrate, then redisperse colloidal suspensions is not only of great theoretical interest, but is also relevant to the industrial process of solid-liquid separation, which must often be followed by a redispersion stage. Up to now, these consecutive operations were unrealizable in the presence of polymers, since flocculation and adsorption were generally considered irreversible in this case. Previous studies have pointed out the occurrence of two main flocculation mechanisms: charge neutralization and interparticle bridging. The use of copolymers makes it possible to take into account these two different mechanisms together. Using this fact we prepared new copolymers of acrylamide with N-vinylimidazole via radical polymerization and characterized them by light scattering, viscometry, potentiometric titrations, and UV studies. One peculiarity of the chosen system is its dependence on pH: actually the degree of neutralization of such cationic polyelectrolytes does vary with pH, especially near the pK value. This paper shows that these copolymers may induce reversible flocculation of negatively charged suspensions, e.g., silica suspensions, by simple pH adjustment. Performances of the system were followed by various physico-chemical methods. The observed results are explained in terms of flocculation mechanisms as a function of pH.

Electronic Resource

1572-9486

Springer Online Journal Archives 1860-2000

Physics

Abstract Using the density functional Kohn-Sham method we show that the internal shapes of fermion clusters are nearly independent of the interparticle interactions. The odd-even staggering of the total energy of small nuclei and of sodium clusters are shown to be of the same origin. Tetrahedral deformations are predicted for 40, 70 and 112 atom sodium clusters. An alternative model for linear nuclei is suggested.

Electronic Resource

1434-6079

36.40 ; 35.20.Wg ; 71.45.Nt

Springer Online Journal Archives 1860-2000

Physics

Abstract A modified Nilsson-Clemenger model is combined with Strutinsky's shell correction method. For spherical clusters, the model potential is fitted to the single-particle spectra obtained from selfconsistent Kohn-Sham calculations. The deformation energy surfaces of sodium clusters with sizes of up toN=270 atoms are calculated for a combination of triaxial, quadrupole and hexadecapole deformations. The ground state shapes and energies are determined by simultaneous minimization with respect to the three shape parameters. A significant fraction of the clusters is predicted to be triaxial. The deviations from the axial shape do not generate any systematic odd-even staggering of the binding energies.

Electronic Resource

1434-6079

36.40 ; 35.20.Wg ; 71.45.Nt

Springer Online Journal Archives 1860-2000

Physics

Abstract We propose a modified Nilsson model for spheroidal sodium clusters and investigate the modification of shell structure by deformation for sizes up toN=850. For spherical clusters, our potential is fitted to the single-particle spectra obtained from microscopically selfconsistent Kohn-Sham calculations using the jellium model and the local density approximation. Employing Strutinsky's shell-correction method, the surface energy of the jellium model is renormalized to its experimental value. We find good agreement between our theoretically predicted deformed magic numbers and the experimentally observed ones extracted from recent sodium mass abundance spectra.

Electronic Resource