Free-Space Quantum Signatures Using Heterodyne Measurements

Digital signatures guarantee the authorship of electronic communications. Currently used "classical" signature schemes rely on unproven computational assumptions for security, while quantum signatures rely only on the laws of quantum mechanics. Previous quantum signature schemes have used unambiguous quantum measurements. Such measurements, however, sometimes give no result, reducing the efficiency of the protocol. Here, we instead use heterodyne detection, which always gives a result, although there is always some uncertainty. We experimentally demonstrate feasibility in a real environment by distributing signature states through a noisy 1.6km free-space channel. Our results show that continuous-variable heterodyne detection improves the signature rate for this type of scheme and therefore represents an interesting direction in the search for practical quantum signature schemes

Trends in the composition of wet deposition: Effects of the atmospheric rehabilitation in East-Germany

The chemical components in precipitation largely depend on type and quantity of emissions on the course of the air masses at the sampling site. Beginning in 1982, the concentrations of major ions in precipitation at initially 3 sites are described in total as well as arrival sectors. For regions with specific geographical or emission features, 5 to 7 sectors for every sampling site are established, e.g., Scandinavia, or the centres of brown coal combustion in the former GDR. Particulary from the sectors of the former GDR, the precipitation was over-averaged contaminated anthropogenically in the years before the political change. Some components were significantly raised in comparison to other sectors. However, acidity remained on the level of the other sectors in the 80 s. In the early 90s, anthropogenic emissions were systematically reduced partly by substitution of brown coal of inferior quality, better flue gas cleaning and partly by closing down industries. The effect of such steps on the wet deposition is being studied in a national German SANA research project (SANA: scientific program of rehabilitation of the atmosphere). In this project, the sampling sites were extended to 7 while maintaining the sampling procedure and the recording of relevant meteorological input-data. As a result, there now exists a homogeneous long-term data base allowing us to study the effects of emissions on wet deposition by the rehabilitation of the atmosphere in the former GDR. The paper focusses on changes in sulphate, nitrate, calcium, acidity, chloride and potassium concentrations in precipitation at the 3 so-called long-term sites. There are conspicuous decreases of some ions on one hand, but there is also an increase of nitrate and acidity, especially in recent years

Trends of pollution in rain over East Germany caused by changing emissions

Large changes in emissions also cause a significant change in pollutant concentrations in rain water. The influence of these changes on pollutant concentrations in rain water and wet deposition were investigated in different regions and time periods from 1983 to 1999 in East Germany. Initially, this period is characterized by large emissions of SO2(about 5400 kt a−1), NOx(about 750 kt a−1), and dust (about 2000 kt a−1) at the end of the 1980s. After the reunification of Germany in 1990 and restructuring of industry and agriculture, emissions drastically decreased. For example, from 1990 to 1998 in Saxony emissions of SO2, NOx and dust decreased by 84, 44 and 97%, respectively. Alkaline components also strongly decreased through efficient dust removal, while no desulphurization was used in flue gases of power and heating plants. As a consequence, the mean acidity of precipitation strongly rose by a factor of three from before 1990 up to 1995 (the mean pH value in 1995 was about 3.9, with minimum values down to 3.6). In 1996 desulphurization techniques were established in power plants and resulted in an increase of pH values to the level in the period from 1983 to 1989/1990. The results for ionic composition (Cl−, NO3−, SO42−, Na+, NH4+, K+, Ca2+, and Mg2+, the pH value (acidity), and conductivity) are based on precipitation samples collected in periods > 4 h. The data were classified with backward trajectories and entry sectors which are characterized by similar emissions and/or geographical regions

Synthesis, enzymatic stability and in vitro cytostatic effect of Daunorubicin-GnRH-III derivative dimers

Bioconjugates containing chemotherapeutic agents attached to peptide hormones, such as gonadotropin-releasing hormone (GnRH), are developed as drug delivery systems for targeted cancer chemotherapy. We report here the synthesis and biochemical characterization of disulfide bond-linked dimeric biocon-jugates in which daunorubicin was coupled via an oxime linkage to aminooxyacetylated GnRH-III ([Glp-His-Trp-Ser-His-Asp-Trp-Lys(Dau@Aoa-Cys)-Pro-Gly-NH2]2; where Glp is pyroglutamic acid and Aoa is aminooxyacetyl) and its derivatives modified in position four byN-Me-Ser and Lys(Ac). The in vitro sta-bility/degradation of the bioconjugates was determined in human serum, as well as in the presence of rat liver lysosomal homogenate and digestive enzymes. All compounds were stable at least for 24 h in human serum and in the presence of pepsin and trypsin, while they were degraded by lysosomal enzymes. The daunorubicin-GnRH-III derivative dimers were partly digested bya-chymotrypsin; how-ever, they had increased stability compared to the corresponding monomers, making them potential can-didates for oral administration. The in vitro cytostatic effect of the compounds was determined on MCF-7 human breast cancer cells by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. All daunorubicin-GnRH-III derivative dimers exerted slightly increased in vitro cytostatic effect (IC50values in low lM range) than the corresponding monomeric bioconjugates

Mass spectrometric approaches for elucidation of antigen antibody recognition structures in molecular immunology

Mass spectrometric approaches have recently gained increasing access to molecular immunology and several methods have been developed that enable detailed chemical structure identification of antigen-antibody interactions. Selective proteolytic digestion and MS-peptide mapping (epitope excision) has been successfully employed for epitope identification of protein antigens. In addition, affinity proteomics using partial epitope excision has been developed as an approach with unprecedented selectivity for direct protein identification from biological material. The potential of these methods is illustrated by the elucidation of a β- amyloid plaque-specific epitope recognized by therapeutic antibodies from transgenic mouse models of Alzheimer s disease. Using an immobilized antigen and antibody- proteolytic digestion and analysis by high resolution Fourier transform ion cyclotron resonance mass spectrometry has lead to a new approach for the identification of antibody paratope structures (paratope-excision; parexprot ). In this method, high resolution MS-peptide data at the low ppm level are required for direct identification of paratopes using protein databases. Mass spectrometric epitope mapping and determination of molecular antibody-recognition signatures offer high potential, especially for the development of new molecular diagnostics and the evaluation of new vaccine lead structures

Protein Expression Profile of HT-29 Human Colon Cancer Cells after Treatment with a Cytotoxic Daunorubicin-GnRH-III Derivative Bioconjugate

<div><p>Targeted delivery of chemotherapeutic agents is a new approach for the treatment of cancer, which provides increased selectivity and decreased systemic toxicity. We have recently developed a promising drug delivery system, in which the anticancer drug daunorubicin (Dau) was attached <i>via</i> oxime bond to a gonadotropin-releasing hormone-III (GnRH-III) derivative used as a targeting moiety (Glp-His-Trp-Lys(Ac)-His-Asp-Trp-Lys(Dau = Aoa)-Pro-Gly-NH₂; Glp = pyroglutamic acid, Ac = acetyl; Aoa = aminooxyacetyl). This bioconjugate exerted <i>in vitro</i> cytostatic/cytotoxic effect on human breast, prostate and colon cancer cells, as well as significant <i>in vivo</i> tumor growth inhibitory effect on colon carcinoma bearing mice. In our previous studies, H-Lys(Dau = Aoa)-OH was identified as the smallest metabolite produced in the presence of rat liver lysosomal homogenate, which was able to bind to DNA <i>in vitro</i>. To get a deeper insight into the mechanism of action of the bioconjugate, changes in the protein expression profile of HT-29 human colon cancer cells after treatment with the bioconjugate or free daunorubicin were investigated by mass spectrometry-based proteomics. Our results indicate that several metabolism-related proteins, molecular chaperons and proteins involved in signaling are differently expressed after targeted chemotherapeutic treatment, leading to the conclusion that the bioconjugate exerts its cytotoxic action by interfering with multiple intracellular processes.</p></div

Identified proteins with altered expression due to the chemotherapeutic treatment of HT-29 human colon cancer cells.

<p>Identified proteins with altered expression due to the chemotherapeutic treatment of HT-29 human colon cancer cells.</p

Structure representation of cytotoxic agents.

<p>(A) daunorubicin and (B) oxime bond-linked daunorubicin-GnRH-III derivative bioconjugate, GnRH-III[⁴Lys(Ac), ⁸Lys(Dau = Aoa)].</p

Protein expression profile of HT-29 human colon cancer cells.

<p>(A) untreated, (B) bioconjugate-treated and (C) daunorubicin-treated cancer cells. Shown only on the control gel, arrows and spot numbers indicate the significantly different protein spots.</p