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Cyclotides are an abundant and diverse group of ribosomally synthesized plant peptides containing a cyclic cystine-knotted structure that confers them with remarkable stability. They are explored for their distribution in plants, although little is known about the individual peptide content of a single species. Therefore, we chemically analyzed the crude extract of the coffee-family plant Oldenlandia affinis using a rapid peptidomics workflow utilizing nano-LC-MS, peptide reconstruct with database identification, and MS/MS automated sequence analysis to determine its cyclotide content. Biologically, cyclotides are mainly explored for applications in agriculture and drug design; here we report their growth-inhibiting effects on primary cells of the human immune system using biological and immunological end points in cell-based tes...
We have developed a fast, yet highly reproducible method to fabricate metallic electrodes with nanometer separation using electromigration (EM). We employ four-terminal instead of two-terminal devices in combination with an analog feedback to maintain the voltage $U$ over the junction constant. After the initialization phase ($U < 0.2V), during which the temperature $T$ increases by 80-150 degs C, EM sets in shrinking the wire locally. This quickly leads to a transition from the diffusive to a quasi-ballistic regime ($0.2V < U < 0.6V). At the end of this second regime, a gap forms (U > 0.6V). Remarkably, controlled electromigration is still possible in the quasi-ballistic regime.
Ethnopharmacological relevance: Heartsease (Viola tricolor L), a member of the Violaceae family, has a long history as a medicinal plant and has been documented in the Pharmacopoeia of Europe. Due to its anti-inflammatory properties it is regarded as a traditional remedy against skin diseases, for example for the treatment of scabs, itching, ulcers, eczema or psoriasis, and it is also used in the treatment of inflammation of the lungs and chest such as bronchitis or asthma. Because T-cells play an important role in the pathological process of inflammatory diseases we investigated the effect of an aqueous Viola extract on lymphocyte functions and explored the 'active' principle of the extract using bioactivity-guided fractionation.
Ethnopharmacological relevance: Leaf extracts of Betula pendula have been traditionally used for the treatment of patients with rheumatoid arthritis (RA) or osteoarthritis.
Cyclotides are a diverse and abundant group of ribosomally synthesized plant peptides containing a unique cyclic cystine-knotted topology that confers them with remarkable stability. Kalata B1, a representative member of this family of mini-proteins, has been found to inhibit the proliferation of human peripheral blood mononuclear cells. Analysis of T-cell proliferation upon treatment with chemically synthesized kalata B1 mutants revealed a region comprising inter-cysteine loops 1 and 2 of the cyclotide framework to be important for biological activity. Cytokine signaling analysis using an 'active' kalata B1 mutant [T20K], and the reference drug cyclosporin A (CsA) demonstrated that treatment of activated T-lymphocytes with these compounds decreased the expression of the interleukin-2 (IL-2) surface receptor as well as IL-2 cytok...
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