Biomedical subjects

A Caragheorgheopol

Publications and source records attributed to A Caragheorgheopol.

4 recordsLinked to original sources

PubMed2001

Aggregation numbers and microstructure characterization of self-assembled aggregates of poly(ethylene oxide) surfactants and related block-copolymers, studied by spectroscopic methods.

This review presents typical examples of micellar size measurements and structural characterization of self-assembled systems as determined with spectroscopic methods, selected from our representative results accumulated in recent years of systematic studies. The choice of examples has aimed at emphasizing the potentiality of the methods used in the study of poly(ethylene oxide) (PEO) surfactants. By using the time-resolved fluorescence quenching method aggregation numbers have been determined for direct and reverse micelles as well as for micelle-like clusters formed in (bio)polymer-surfactant solutions. By using specific spectral parameters of a variety of properly chosen molecular probes [fluorescence, UV-VIS and electron spin resonance (ESR) spin probes], problems such as hydration degree and profile of the PEO chains, local viscosity, ordering and packing of surfactant chains have been addressed. The intention was to correlate results obtained from different spectroscopic methods and to refer all polarity data to a common scale, such as Kosower's polarity factor.

Journal Article↗

PubMed1996

New amino-nitroxide spin labels.

Stable free mono- and diradicals containing reactive primary or secondary amino groups in the side-chain have been synthesized by transesterification of amino-substituted esters with paramagnetic alcohols or from spin-labeled acid derivatives and amines. In the second approach the new radical 18 (1-oxyl-3-(2-bromoethoxycarbonyl)-2,2,5,5-tetramethylpyrroline) is proposed as an efficient alkylating species. The nitroxides described are pH-sensitive spin probes and spin labels potentially useful for a diversity of ESR applications in chemistry and biology. New spin-labeled tyramine 16 (N-(1-oxyl-3-carbonyl-2,2,5,5-tetramethyl-pyrroline)tyramine) was successfully employed in a novel assay of protein oxidative damage.

Cyclic N-Oxides↗

PubMedDate not supplied

The development of a radioimmunoassay system for testosterone (T) and dihydrotestosterone (DHT). Part 2. The preparation of antisera to T.

Testosterone-3-O-carboxymethyl-oxime derivative was synthetized and coupled to bovine serum albumin (BSA). The T-3-CMO-BSA conjugate homogenized with Freund's adjuvant used as immunogen was injected multiple sites in rabbits. The antisera collected were characterized in a radioimmunological system, separation with dextran-charcoal using 125I-Testosterone as tracer. The antibody titres varied from one animal to another. The titre of anti-T serum selected for RIA was 1: 10(4)-1: 2 X 10(4) (initial dilution). All anti-T sera 100 percent crossreacted with 5 alpha-dihydrotestosterone but nonsignificant interference was observed with other C19, C21 and C18 steroids. The affinity constant of the selected anti-T serum was in the range 1.4-1.9 X 10(9) litres/mole. The data so far published on the antisera toward testosterone are reviewed. We conclude that the selected anti-T-3-CMO-BSA serum may provide assays for testosterone with potential for clinical applications.

Animals↗

PubMedDate not supplied

The development of a radioimmunoassay system for testosterone (T) and dihydrotestosterone (DHT). Part 3. The preparation of radioiodinated testosterone.

A two step-method was applied for the preparation of a tracer adequate for a radioimmunoassay (RIA) system for testosterone. Histamine was radioiodinated by the Chloramine-T method and then coupled to testosterone-3-carboxymethyl-oxime (T-3-CMO) derivative. After purification by TLC, the steroid tracer was stable in ethanol for at least four months. Using an anti-T-3-CMO-BSA serum, a (bridge) homologous RIA system for testosterone was developed. The reagents (antiserum, tracer and standard) were incubated 2 hrs at 37 degrees C and then the free radioactivity was removed by a dextran-charcoal suspension. The testosterone RIA system, with the sensitivity of 30 pg/tube, is suitable for the measurement of the steroid hormone in biological fluids and tissues.

Animals↗