Searchable abstracts of presentations at key conferences in endocrinology ISSN 1470-3947 (print) | ISSN 1479-6848 (online)

WSTEP. Stopniowe wyczerpywanie sie mo?liwo¶ci sekrecyjnych komorki b w cukrzycy typu 2 wi±?e sie z pogorszeniem kontroli metabolicznej oraz potrzeb± rozpoczecia insulinoterapii. Celem badania by³a ocena poprawy kontroli metabolicznej po w³±czeniu leczenia insulin±. MATERIA£ I METODY. Badaniem objeto 52 chorych na cukrzyce typu 2 — 30 kobiet i 22 me?czyzn w wieku 44–79 lat (¶rednio 63,1 ± 10,1 roku). Leczenie zintensyfikowano poprzez do³±czenie insuliny do dotychczas stosowanych lekow doustnych lub zastosowano monoterapie insulin±. Badanych poddano 8 ± 1,5-miesiecznej obserwacji. WYNIKI. Osi±gnieto istotn± redukcje ¶redniego ste?enia hemoglobiny glikowanej (HbA1c) z 7,9% do 7,5%, w zwi±zku z czym odsetek osob z HbA1c £ 7,0% wzros³ z 28,8% (n = 15) do 44,3% (n = 23). Odsetek osob z HbA1c £ 6,5% nie zmieni³ sie i wynosi³ 19,2% (n = 10). Zaobserwowano wzrost odsetka osob z ci¶nieniem skurczowym < 130 mm Hg z 19,2% (n = 10) do 30,8% (n = 16) oraz ci¶nieniem rozkurczowym < 80 mm Hg z 15,4% (n = 8) do 26,9% (n = 14). W zakresie kontroli gospodarki lipidowej zanotowano niewielki wzrost odsetka osob spe³niaj±cych kryteria wyrownania: ste?enie cholesterolu ca³kowitego < 175 mg/dl z 34,6% (n = 18) do 40,4% (n = 21), cholesterolu frakcji HDL > 40 mg/dl z 55,8% (n = 29) do 67,3% (n = 35), cholesterolu frakcji LDL < 100 mg/dl z 38,5% (n = 20) do 40,4% (n = 21) oraz triglicerydow < 150 mg/dl z 50% (n = 26) do 51,9% (n = 27). WNIOSKI. Uzyskane wyniki potwierdzaj± korzystny, widoczny ju? po kilku miesi±cach leczenia wp³yw insulinoterapii na poziom wyrownania metabolicznego u chorych na niewyrownan± cukrzyce typu 2. Powinny one stanowiae zachete do prze³amania oporow przed zastosowaniem leczenia insulin± zarowno u samych pacjentow, jak i w¶rod prowadz±cych ich lekarzy. (Diabet. Prakt. 2011; 12, 1: 21–27)

Natural enkephalins and their analogues are very important as potential therapeutic agents (analgetics). Herein we describe the influence of Dab and Pro chirality of cyclic [Leu]enkephalins (X-1-c[Dab(2)-Pro(3)-beta Nal(2)(4)-Leu(5)], where X = Tyr or Phe) on the binding constant with beta-cyclodextrin and spatial and mutual orientation of guest and host molecules. The formation of complexes is enthalpy driven for all cyclic [Leu]enkephalins studied as well as for Nal and AcNalNH(2). Moreover, change of Dab residue configuration has a greater influence on changes of the binding constant of cyclic enkephalin with beta-CD than change of Pro chirality has. Also, the replacement of Tyr(1) residue by Phe(1) substantially changes the peptide chain conformation. An analysis of 2D NMR spectra reveals that, apart from inclusion complex formed by penetration of cyclodextrin cavity from wider and narrow rims by Nal, Tyr or Phe or Leu residue, a side and/or bottom association complexes are formed.

Natural enkephalins and their analogues are very important as potential therapeutic agents (analgetics). Herein we describe the influence of Dab and Pro chirality of cyclic [Leu]enkephalins (X1-c[Dab2-Pro3-βNal(2)4-Leu5], where X = Tyr or Phe) on the binding constant with β-cyclodextrin and spatial and mutual orientation of guest and host molecules. The formation of complexes is enthalpy driven for all cyclic [Leu]enkephalins studied as well as for Nal and AcNalNH2. Moreover, change of Dab residue configuration has a greater influence on changes of the binding constant of cyclic enkephalin with β-CD than change of Pro chirality has. Also, the replacement of Tyr1 residue by Phe1 substantially changes the peptide chain conformation. An analysis of 2D NMR spectra reveals that, apart from inclusion complex formed by penetration of cyclodextrin cavity from wider and narrow rims by Nal, Tyr or Phe or Leu residue, a side and/or bottom association complexes are formed.

Natural enkephalins and their analogues are very important as potential therapeutic agents (analgetics). In this paper we describe the influence of Leu chirality of cyclic [Leu]enkephalins on the binding constant with β-cyclodextrin and spatial and mutual orientation of guest and host molecules. The formation of complexes is enthalpy driven for both cyclic [Leu]enkephalins. Moreover, d -configuration of Leu residue causes an increase of the binding constant of cyclic enkephalin compared to l -analogue. An analysis of 2D NMR spectra reveals that, apart from inclusion complex formed by penetration of cyclodextrin cavity from wider and narrow rims by Trp or Leu residue, a side and/or bottom association complexes are formed.

Surface plasmon-coupled emission (SPCE) phenomenon is the coupling of excited fluorophores near a silver film with surface plasmons, resulting in directional emission into the underlying glass substrates. We report a complex coupling of Nile Blue fluorophore with 50 nm silver mirror, resulting in emission at several angles in the glass substrate, with either s or p polarization. This complex pattern of directional and polarized emission appears to be due to optical waveguide effects occurring when the sample thickness becomes comparable to the emission wavelength. We expect waveguide-modulated SPCE to have applications to biophysics and sensing.

We studied one‐ and two‐photon induced fluorescence of Pacific Blue (PB)‐labeled human serum albumin (HSA) in the presence of different size silver colloids. The PB fluorescence emission intensity was observed with small (30–40 nm) and large (about 120 nm) colloids and compared with PB emission in absence of colloids. For the system with a small core size colloids we did not detect any fluorescence enhancement with one‐photon excitation and the enhancement observed with two‐photon excitation was about 2.5‐fold. In contrast, for large silver colloids we observed about a 2‐fold increase in PB fluorescence brightness for one‐photon excitation, and the enhancement with two‐photon excitation excided 13‐folds. Much stronger increases in brightness observed with two‐photon excitation, compared to one‐photon excitation, indicate a dominant role of enhanced local field in fluorescence enhancement on silver colloids in solutions. © 2005 Wiley Periodicals, Inc. Biopolymers 81: 249–255, 2006

Metal-enhanced fluorescence (MEF) appears to be most suitable to the fluorescence assays used in drug discovery and DNA analysis. The metal–fluorophore effects offer unique perspectives in fluorescence sensing, providing for improved background suppression, increased detection limits, and localized excitation near to silver nanostructures. This article describes the effects of different silver nanostructures on the emission intensity and photostability of fluorophores and the use of MEF in high-throughput screening and drug discovery. Keywords: metal-enhanced fluorescence (MEF); metal–fluorophore effects; fluorophores; photostability; silver nanostructures

High-sensitivity detection schemes are of great interest for a number of applications. Unfortunately, such schemes are usually high-cost. We demonstrate a low-cost approach to a high-sensitivity detection scheme based on surface plasmon-coupled emission (SPCE). The SPCE of a monomolecular layer of green fluorescent protein (GFP) is reported here. The protein was electrostatically attached to a thin, SiO(2)-protected silver film deposited on a quartz substrate. The visible, directional emission of GFP was observed at a sharp, well-defined angle of 47.5 degrees from the normal to the coupling prism, and the spectrum corresponded to that of GFP. The SPCE resulting from the reverse Kretschmann configuration showed a 12-fold enhancement over the free space fluorescence. The directional emission was 97% p-polarized. The directionality and high polarization can be coupled with the intrinsic spectral resolution of SPCE to be used in the design miniaturized spectrofluorometers. The observation of SPCE in the visible region of the spectrum from a monolayer of protein opens up new possibilities in protein-based sensing.

We studied surface plasmon-coupled emission (SPCE) of semiconductor quantum dots (QDs). These QDs are water-soluble ZnS-capped CdSe nanoparticles stabilized using lysine cross-linked mercaptoundecanoic acid. The QDs were spin-coated from 0.75% PVA solution on a glass slide covered with 50 nm of silver and a 5-nm protective SiO(2) layer. Excited QDs induced surface plasmons in a thin silver layer. Surface plasmons emitted a hollow cone of radiation into an attached hemispherical glass prism at a narrow angle of 48.5 degrees. This directional radiation (SPCE) preserves the spectral properties of QD emission and is highly p-polarized irrespective of the excitation polarization. The SPCE spectrum depends on the observation angle because of the intrinsic dispersive properties of SPCE phenomenon. The remarkable photostability can make QDs superior to organic fluorophores when long exposure to the intense excitation is needed. The nanosize QDs also introduce a roughness near the metal layer, which results in a many-fold increase of the coupling of the incident light to the surface plasmons. This scattered incident illumination transformed into directional, polarized radiation can be used simultaneously with SPCE to develop devices based on both quantum dot emission and light scattered from surface plasmons on a rough surface.

At the Center for Fluorescence Spectroscopy, we have taken advantage of the favorable properties of surface plasmon-coupled emission (SPCE) to improve fluorescence-based immunoassays. SPCE occurs when excited fluorophores near conducting metallic structures efficiently couple to surface plasmons. These surface plasmons, appearing as free electron oscillations in the metallic layer, produce electromagnetic radiation that preserves the spectral properties of fluorophores but is highly polarized and directional. SPCE immunoassays provide several advantages over other fluorescence-based methods. This review explains new approaches to fluorescence immunoassays, including our own use of SPCE for simultaneous detection of more than one fluorescent marker and performance of immunoassays in the presence of an optically dense medium, such as whole blood.

Fluorescence experiments are typically performed in sample geometries that are large relative to the size of the fluorophores and relative to the absorption and emission wavelengths. In this arrangement the fluorophores radiate into free space. Most of our knowledge and intuition about fluorescence is derived from the spectral properties observed in these free-space conditions. However, the presence of nearby metallic surfaces or particles can alter the free-space condition, which can result in dramatic spectral changes which are distinct from those observable in the absence of metal surfaces. Remarkably, metal surfaces can increase or decrease the radiative decay rates of fluorophores and increase the extent of resonance energy transfer (RET) (Figure 1).These effects are due to interactions of the excited-state fluorophores with free electrons in the metal, the so-called surface plasmon electrons, which polarize the metal and produce favorable effects on the fluorophore. The effects of metallic surfaces are complex and include quenching at short distances, spatial variation of the incident light field, and changes in the radiative decay rates (Figure 2). We refer to the use of fluorophore-metal interactions as radiative decay engineering (RDE) or metal enhanced fluorescence (MEF).

We present a new method for multi-color fluoroimmunoassays based on directional surface plasmon-coupled emission (SPCE). SPCE is coupling of excited fluorophores with a nearby thin metal film (silver) resulting in strongly directional emission into the underlying glass substrate. The angle at which the radiation propagates through the prism depends on emission wavelength and makes possible measurement of multiple analytes using multiple emission wavelengths. We demonstrated this possibility using two antibodies labeled with different fluorophores, binding to an antigen protein immobilized on the silver surface. We observed independent emission at a different angle on the glass prism, resulting of the surface binding of each antibody. This methodology can be readily extended to 3 or more fluorophores. This technology presents opportunity to develop highly sensitive multiplex assay format for biological agents' detection.