Exact overlaps in the Kondo problem.

It is well known that the ground states of a Fermi liquid with and without a single Kondo impurity have an overlap that decays as a power law of the system size, expressing the Anderson orthogonality catastrophe. Ground states with two different values of the Kondo couplings have, however, a finite overlap in the thermodynamic limit. This overlap, which plays an important role in quantum quenches for impurity systems, is a universal function of the ratio of the corresponding Kondo temperatures, which is not accessible using perturbation theory or the Bethe ansatz. Using a strategy based on the integrable structure of the corresponding quantum field theory, we propose an exact formula for this overlap, which we check against extensive density matrix renormalization group calculations.

Soliton confinement in a quantum circuit.

Confinement of topological excitations into particle-like states - typically associated with theories of elementary particles - are known to occur in condensed matter systems, arising as domain-wall confinement in quantum spin chains. However, investigation of confinement in the condensed matter setting has rarely ventured beyond lattice spin systems. Here we analyze the confinement of sine-Gordon solitons into mesonic bound states in a perturbed quantum sine-Gordon model. The latter describes the scaling limit of a one-dimensional, quantum electronic circuit (QEC) array, constructed using experimentally-demonstrated QEC elements. The scaling limit is reached faster for the QEC array compared to spin chains, allowing investigation of the strong-coupling regime of this model. We compute the string tension of confinement of sine-Gordon solitons and the changes in the low-lying energy spectrum. These results, obtained using the density matrix renormalization group method, could be verified in a quench experiment using state-of-the-art QEC technologies.

New Opportunities for Preoperative Diagnosis of Medullary Thyroid Carcinoma.

The preoperative diagnostics of medullary thyroid carcinoma (MTC), including the measuring of the blood calcitonin level, has a number of limitations. Particular focus has recently been placed on the role of miRNAs in the development of various malignant tumors; a comparative analysis of accuracy of the existing methods for MTC diagnosis with a novel diagnosis method, evaluation of the miRNA-375 expression level, was performed in this study. The expression level of miRNA-375 in cytology samples from 555 patients with the known histological diagnosis, including 41 patients with confirmed postoperative diagnosis of MTC, was assessed. The diagnostic parameters of the basal calcitonin level, calcitonin in wash-out fluid from the FNAB needle, and miRNA-375 were compared. An assessment of the miRNA-375 expression level made it possible to detect all the MTC samples with a 100% accuracy among all the 555 cytology specimens, as well as in non-informative FNAB specimens, and specimens from the ipsilateral thyroid lobe. Parameters such as sensitivity, specificity, PPV, and NPV were 100%. The miRNA-375 level, unlike calcitonin, does not correlate with tumor volume, so it does not have the so-called "gray zone". An assessment of the miRNA-375 expression allows one to accurately distinguish MTC from other malignant and benign thyroid tumors.

Preoperative detection of malignancy in fine-needle aspiration cytology (FNAC) smears with indeterminate cytology (Bethesda III, IV) by a combined molecular classifier.

AIMS: Analysis of molecular markers in addition to cytological analysis of fine-needle aspiration (FNA) samples is a promising way to improve the preoperative diagnosis of thyroid nodules. Previously, we have developed an algorithm for the differential diagnosis of thyroid nodules by means of a small set of molecular markers. Here, we aimed to validate this approach using FNA cytology samples of Bethesda categories III and IV, in which preoperative detection of malignancy by cytological analysis is impossible. METHODS: A total of 122 FNA smears from patients with indeterminate cytology (Bethesda III: 13 patients, Bethesda IV: 109 patients) were analysed by real-time PCR regarding the preselected set of molecular markers (the BRAF V600E mutation, normalised concentrations of HMGA2 mRNA, 3 microRNAs, and the mitochondrial/nuclear DNA ratio). The decision tree-based classifier was used to discriminate between benign and malignant tumours. RESULTS: The molecular testing detected malignancy in FNA smears of indeterminate cytology with 89.2% sensitivity, 84.6% positive predictive value, 92.9% specificity and 95.2% negative predictive value; these characteristics are comparable with those of more complicated commercial tests. Residual risk of malignancy for the thyroid nodules that were shown to be benign by this molecular method did not exceed the reported risk of malignancy for Bethesda II histological diagnosis. Analytical-accuracy assessment revealed required nucleic-acid input of ≥5 ng. CONCLUSIONS: The study shows feasibility of preoperative differential diagnosis of thyroid nodules of indeterminate cytology using a small panel of molecular markers of different types by a simple PCR-based method using stained FNA smears.

Imaging of Intracellular Hydrogen Peroxide Production with HyPer upon Stimulation of HeLa Cells with EGF.

Reactive oxygen species (ROS) regulate both normal cell functions by activating a number of enzymatic cascades and pathological processes in many diseases by inducing oxidative stress. For many years since the discovery of ROS in biological systems there were no adequate methods of detection and quantification of these molecules inside the living cells. We developed the first genetically encoded fluorescent indicator for intracellular detection of hydrogen peroxide, HyPer, that can be used for imaging of H2O2 production by cells under various physiological and pathological conditions. Unlike most known ROS indicators, HyPer allows for the generation of real-time image series that give precise information about the time course and intensity of H2O2 changes in any compartment of interest. In this chapter we describe the method of confocal imaging of hydrogen peroxide production in HeLa cells upon stimulation with epidermal growth factor. The technique described may be accepted with minimal variations for the use in other cell lines upon various conditions leading to H2O2 production.

Imaging of intracellular hydrogen peroxide production with HyPer upon stimulation of HeLa cells with epidermal growth factor.

Reactive oxygen species (ROS) regulate both normal cell functions by activating a number of enzymatic cascades and pathological processes in many diseases by inducing oxidative stress. For many years since the discovery of ROS in biological systems, there were no adequate methods of detection and quantification of these molecules inside the living cells. We developed the first genetically encoded fluorescent indicator for the intracellular detection of hydrogen peroxide, HyPer, that can be used for imaging of H2O2 production by cells under various physiological and pathological conditions. Unlike most known ROS indicators, HyPer allows the generation of a real-time image series that give precise information about the time course and intensity of H2O2 changes in any compartment of interest. In this chapter, we describe the method of confocal imaging of hydrogen peroxide production in HeLa cells upon stimulation with epidermal growth factor. The technique described may be accepted with minimal variations for the use in other cell lines upon various conditions leading to H2O2, production.

Hydroxyproline-based DNA mimics provide an efficient gene silencing in vitro and in vivo.

To be effective, antisense molecules should be stable in biological fluids, non-toxic, form stable and specific duplexes with target RNAs and readily penetrate through cell membranes without non-specific effects on cell function. We report herein that negatively charged DNA mimics representing chiral analogues of peptide nucleic acids with a constrained trans-4-hydroxy-N-acetylpyrrolidine-2-phosphonate backbone (pHypNAs) meet these criteria. To demonstrate this, we compared silencing potency of these compounds with that of previously evaluated as efficient gene knockdown molecules hetero-oligomers consisting of alternating phosphono-PNA monomers and PNA-like monomers based on trans-4-hydroxy-L-proline (HypNA-pPNAs). Antisense potential of pHypNA mimics was confirmed in a cell-free translation assay with firefly luciferase as well as in a living cell assay with green fluorescent protein. In both cases, the pHypNA antisense oligomers provided a specific knockdown of a target protein production. Confocal microscopy showed that pHypNAs, when transfected into living cells, demonstrated efficient cellular uptake with distribution in the cytosol and nucleus. Also, the high potency of pHypNAs for down-regulation of Ras-like GTPase Ras-dva in Xenopus embryos was demonstrated in comparison with phosphorodiamidate morpholino oligomers. Therefore, our data suggest that pHypNAs are novel antisense agents with potential widespread in vitro and in vivo applications in basic research involving live cells and intact organisms.

Antirrhinum majus microspore maturation and transient transformation in vitro.

The male gametophyte of higher plants represents an excellent system to study gene regulation, cell fate determination and cellular differentiation in plants because of its relative simplicity compared to the sporophyte and its accessibility for cytological and molecular analysis. Unicellular plant microspores are single haploid cells, which can be isolated in large amounts at a defined developmental stage. Microspores cultured in vitro in a rich medium develop into mature pollen grains, which are fertile upon pollination in vivo. It is reported here that isolated Antirrhinum majus microspores when cultured in an optimal medium develop to form mature, fertile pollen. Their development closely resembled that of pollen formed in vivo. Isolated microspores were bombarded with Aquorea victoria Green Fluorescent Protein (GFP), Discosoma Red Fluorescent Protein (dsRFP) and beta-glucuronidase (GUS) reporter genes under the control of various promoters and transient expression was observed throughout pollen development in vitro. Bombarded and not bombarded in vitro-matured pollen grains were able to germinate both in vitro and on receptive stigmas and to set seed. The protocol of maturation, transient transformation and germination of Antirrhinum majus pollen in vitro described here provides a valuable tool for basic and applied research.