Synthesis and biological evaluation of novel structure-related hGHRH agonistic analogs.

Activity and half-life play key roles in the application of GHRH analogues. The GHRH monomers produced in a solid synthesizer were incubated, respectively, in NH4OH solution and lyophilized to obtain their dimers. The activities, specificities, and receptor affinities of the GHRH dimers were evaluated in rGH release/inhibition, rACTH/LH/PRL release, pituitary homogenate binding, and fluorescent staining. Compared to hGHRH(1-44)NH2 (S), PP-hGHRH(1-44)-GGC-CGG-hGHRH(44-1)-PP (2D), P-hGHRH(1-44)-GGC-CGG-hGHRH(44-1)-P (2E), (1)P-hGHRH(2-44)-GGC-CGG-hGHRH(44-2)-(1)P (2F), or hGHRH(1-44)-GGC-CGG-hGHRH(44-1) (2Y) had potency of 104 ± 16.7%, 94 ± 32.6%, 114 ± 16.6%, or 122 ± 14.5% and similar specificities. The inhibition effect of GHIH on rGH stimulated by GHRH dimer was in dose-/time-dependent manner. The staining of FITC-labeled dimer showed cytomembrane distribution and the binding ranking was 2F>2D>2Y>2E>S. 2F presents the strongest activity and the highest affinity to pituitary cells. The dimer with (1)Pro-GHRH stimulates stronger rGH release than that with (1)Tyr-GHRH and the N-terminal single cyclic amino acid is required for the stimulation.

[Study on the mechanism of energy transfer between fluorescein sodium and tetrabromofluorescein sodium in micelles of cationic surface active agent].

In the present paper, the fluorescence reaction of cationic surface-active agents (CSAA) with Tetrabromofluorescein sodium (TBF) in aqueous solution was investigated. It was found that the fluorescence quenching of TBF appears when it reacts with the cation monomer of a CSAA and a new stronger fluorescence is obtained when the ion-associates react with the micellate of CSAA. The authors investigated the condition of energy transfer between acidic fluorescent dyes in micelles of cetyl trimethyl ammonium bromide or hexadecyl pyridinium bromide. It was indicated that in the micelles formed by cationic surface active agent with dyes embedded (cationic surface active agent and dyes are charge opposite), the effective energy transfer between anionic dyes could occur. When the concentration of cationic surface active agent reached certain value, the energy transfer could occur. With the value of two thirds of critical micelle concentration, the efficiency of energy transfer reached the maximum; when the concentration of cationic surface active agent increased, the efficiency of energy transfer would be decreased. The authors also deduced the model of energy transfer between dyes in micelles and laws of it.

[Study on mechanism of lanthanide sensitized fluorescence energy transfer between terbium(III)-ciprofloxacin and rhodamine B].

A complex composed of ciprofloxacin and terbium (Tb3+) in the solution of acetic acid-sodium acetate buffer (pH 6.2) was studied by fluorescence spectroscopy and ultra-violet absorption spectroscopy. The emission peak of Tb3+ appeared at 490, 545, 590 nm, (the sensitized fluorescence was enforced mightily) and the intensity of 545 nm emission peak was increased obviously. In its acute emission spectrum, the strongest emission peak of Tb3+ was at 545 nm, which was close to the wavelength of the biggest absorption peak of RB, 552 nm. Therefore, as the basic dye rhodamine B(RB) was added, the fluorescence intensity of 545 nm emission peak decreased regularly, indicating that there was a great quenching process. The result showed that the course was statistic. Based on the mechanism of the Förster energy transfer, the efficiency of energy transfer and the distance between the acceptor RB and the complex were found. Thereby, it was indicated that the course of action was single static quenching and the mechanism of quenching was based on energy transfer.

Investigation of mtDNA control region sequences in a Tibetan population sample from China.

Mitochondrial hypervariable region sequences including HVI and HVII (15,751-520) were investigated from 174 unrelated Tibetan individuals living in Tibet Autonomous Region in People's Republic of China. The resulted sequences were aligned and compared with revised Cambridge sequence (rCRS). This sequence variability rendered a high gene diversity value (0.9940 ± 0.0021) and a high random match probability (0.0118) was determined with PIC of 0.9882. Among a total of 174 samples, 217 polymorphic sites were identified, which defined 135 haplotypes. A total of 135 different haplotypes were detected, 113 of them were unique and 22 were shared. The most common haplogroup was M9a1a1c1b1 (16.09%), followed by A11 (6.32%), A (5.17%), R (4.60%), A15 (4.60%), and G3a1 (3.45). The proportions of macro-haplogroups M, N, and L were 54.60%, 42.53%, and 2.87%, respectively. By principal component analysis (PCA), there was no special cluster between Tibetans and other populations except that the structure of Tibetans closely resembled that of Uygur in component 2.