Design and Preparation of Lifetime-Based Dual Fluorescent/Phosphorescent Sensor of pH and Oxygen and its Exploration in Model Physiological Solutions and Cells.

In the present report, a novel dual pH-O2 sensor based on covalent conjugate of rhodamine 6G and cyclometalated iridium complex with poly(vinylpyrrolidone-block-vinyltetrazole) copolymer is reported. In model physiological solutions the sensor chromophores display independent phosphorescent and fluorescent lifetime responses onto variations in oxygen concentration and pH, respectively. Colocalization studies on Chinese hamster ovary cells demonstrate the preferential localization in endosomes and lysosomes. The fluorescent lifetime imaging microscopy-phosphorescent lifetime imaging microscopy (FLIM-PLIM) experiments show that the phosphorescent O2 sensor provides unambiguous information onto hypoxia versus normoxia cell status as well as semi-quantitative data on the oxygen concentration in cells in between these two states. However, the results of FLIM measurements indicate that dynamic lifetime interval of the sensor (≈0.5 ns between pH values 5.0 and 8.0) is insufficient even for qualitative estimation of pH in living cells because half-width of lifetime distribution in the studied samples is higher than the sensor dynamic interval. Nevertheless, the variations in rhodamine emission intensity are much higher and allow rough discrimination of acidic and neutral cell conditions. Thus, the results of this study indicate that the suggested approach to the design of dual pH-O2 sensors makes possible to prepare the biocompatible and water-soluble conjugate with fast cellular uptake.

Synthesis of γ-Sultam-Annelated δ-Lactams via the Castagnoli-Cushman Reaction of Sultam-Based Dicarboxylic Acids.

An unusual type of highly reactive sultam-based dicarboxylic acids and correscponding anhydrides was employed in the Castagnoli-Cushman reaction delivering diastereomerically pure adducts at room temperature. Due to steric congestion, the initial adducts were prone to decarboxylation affording diastereomeric mixtures of bicyclic sultam lactams, separable by HPLC. The choice of a protecting group on the sultam nitrogen atom allows liberation of the NH-sultam, which is not only suitable for further modification but represents a known pharmacophore for carbonic anhydrase inhibition.

Comparison of pharmacokinetics and the exposure-response relationship of dapagliflozin between adolescent/young adult and adult patients with type 1 diabetes mellitus.

AIMS: To quantitatively compare pharmacokinetics (PK) and the exposure-response (ER) relationship of the sodium-glucose cotransporter-2 inhibitor, dapagliflozin, between adolescents/young adults and adults with type 1 diabetes mellitus (T1DM). METHODS: Data from 2 clinical studies for dapagliflozin were analysed using a non-linear mixed-effects approach. The PK and the relationship between dapagliflozin exposure and response (24-hour urinary glucose excretion) were characterized. PK was evaluated using a 2-compartment model with first-order absorption while the exposure response-relationship was analysed using a sigmoidal maximal-effect model. The 24-hour median blood glucose, estimated glomerular filtration rate (eGFR), sex, age and body weight were evaluated as covariates. RESULTS: A 2-compartment model with first order absorption provided a reasonable fit to the dapagliflozin PK data. Body weight was found to be a significant covariate on dapagliflozin exposure. The ER relationship was best described by a sigmoidal maximal effect model with 24-hour median blood glucose and eGFR as significant covariates on maximal effect. In accordance with the observed data, model-predicted urinary glucose excretion response following 10 mg dapagliflozin dose was higher in the study in adolescents/young adults (138.0 g/24 h) compared to adults (70.5 g/24 h) with T1DM. This is linked to higher eGFR and 24-hour median blood glucose in this trial. CONCLUSIONS: Dapagliflozin PK and ER relationship were similar in the 2 analysed studies after accounting for covariate effects. These results suggest that no dose adjustment is required for adolescent patients with T1DM.

Hydroxylated Fluorescent Dyes for Live-Cell Labeling: Synthesis, Spectra and Super-Resolution STED.

Hydroxylated rhodamines, carbopyronines, silico- and germanorhodamines with absorption maxima in the range of 530-640 nm were prepared and applied in specific labeling of living cells. The direct and high-yielding entry to germa- and silaxanthones tolerates the presence of protected heteroatoms and may be considered for the syntheses of various sila- and germafluoresceins, as well as -rhodols. Application in stimulated emission depletion (STED) fluorescence microscopy revealed a resolution of 50-75 nm in one- and two-color imaging of vimentin-HaloTag fused protein and native tubulin. The established structure-property relationships allow for prediction of the spectral properties and the positions of spirolactone/zwitterion equilibria for the new analogues of rhodamines, carbo-, silico-, and germanorhodamines using simple additive schemes.

Feasibility study of the optical imaging of a breast cancer lesion labeled with upconversion nanoparticle biocomplexes.

Innovative luminescent nanomaterials, termed upconversion nanoparticles (UCNPs), have demonstrated considerable promise as molecular probes for high-contrast optical imaging in cells and small animals. The feasibility study of optical diagnostics in humans is reported here based on experimental and theoretical modeling of optical imaging of an UCNP-labeled breast cancer lesion. UCNPs synthesized in-house were surface-capped with an amphiphilic polymer to achieve good colloidal stability in aqueous buffer solutions. The scFv4D5 mini-antibodies were grafted onto the UCNPs via a high-affinity molecular linker barstar:barnase (Bs:Bn) to allow their specific binding to the human epidermal growth factor receptor HER2/neu, which is overexpressed in human breast adenocarcinoma cells SK-BR-3. UCNP-Bs:Bn-scFv4D5 biocomplexes exhibited high-specific immobilization on the SK-BR-3 cells with the optical contrast as high as 10:1 benchmarked against a negative control cell line. Breast cancer optical diagnostics was experimentally modeled by means of epi-luminescence imaging of a monolayer of the UCNP-labeled SK-BR-3 cells buried under a breast tissue mimicking optical phantom. The experimental results were analyzed theoretically and projected to in vivo detection of early-stage breast cancer. The model predicts that the UCNP-assisted cancer detection is feasible up to 4 mm in tissue depth, showing considerable potential for diagnostic and image-guided surgery applications.

Synthesis and biological activity of simplified belactosin C analogues.

Successful biochemical studies of the natural products belactosin A and C and their acylated congeners have shown a ß-lactonecarboxamide moiety to be a possible core structure of powerful proteasome inhibitors. As a part of further investigations, variously decorated simplified ß-lactonecarboxamides have been synthesized in order to understand structure-biological activity relations in detail, to find ways of improving their biological activity and stability and to reduce the complexity of their preparation. Biological tests showed that the best compounds possess a high potential against phytopathogenic fungi in the greenhouse.

Slow light on a printed circuit board.

Slow-light effects induced by stimulated Raman scattering in polymer waveguides on a printed circuit board are shown to enable a widely tunable delay of broadband optical signals, suggesting an advantageous platform for optical information processing and ultrafast optical waveform transformation.

Vibrational spectra and ab initio analysis of tert-butyl, trimethylsilyl, trimethylgermyl, trimethylstannyl and trimethylplumbyl derivatives of 3,3-dimethylcyclopropene. XII. 1,2-Di-tert-butyl-3,3-dimethylcyclopropene.

The synthesis of 1,2-di-tert-butyl-3,3-dimethylcyclopropene (I) is performed and its IR and Raman spectra are measured. Optimized geometries of I are obtained at the HF/6-31G* and CCSD/cc-pVDZ levels. The ab initio calculated spectra are used for the assignments of the experimental spectral data. The results obtained are compared with the corresponding data for 3,3-dimethylbut-1-ene and 3,3-dimethylcyclopropene. These experimental data and the total vibrational analysis of I supplement the information obtained in the series of investigations of tert-butyl, trimethylsilyl, trimethylgermyl, trimethylstannyl, and trimethylplumbyl derivatives of 3,3-dimethylcyclopropene.

Novel antibiotics for the treatment of gram-positive bacterial infections.

The natural dipeptide antibiotic TAN 1057 A,B displays excellent antibacterial activity against staphylococci including methicillin resistant Staphylococcus aureus. However, the in vitro activity against additional Gram-positive strains, in particular pneumococci and Enterococcus faecalis, proved to be considerably lower. We report the synthesis and pharmacological evaluation of new derivatives of this natural product that displayed increased antibacterial potency against staphylococci and were also active against pneumococci. In particular, the analogues bearing modified beta-homoarginine side chains with methylated guanidine moieties were shown to be significantly more potent than the natural product TAN 1057 A,B.