Selective cleavage of an azaGly peptide bond by copper(II). Long‐range effect of histidine residue

Several reports have highlighted the interest of replacing Gly, a frequent amino acid within bioactive peptides, by azaGly (Agly) to improve their stability, activity or for the design of prodrugs. Because metal catalysis is increasingly used for tailoring peptide molecules, we have studied the stability of Agly peptides in the presence of metal ions. In this study, we show that Cu(II), unlike other metal ions such as Fe(II), Fe(III), Pd(II), or Pt(II), induces the cleavage of Agly peptides at room temperature and pH 7.3. The cleavage occurred in the absence of an anchoring His residue within the peptide but it was accelerated when this amino acid was present in the sequence. The influence of His residue on the cleavage rate was minimal when His and Agly were adjacent, whereas large effects were observed for distant His residues. The reaction between Cu(II) and Agly peptides induced the formation of Cu(I) species, which could be detected using bicinchoninic acid as a probe. The nature of products formed in this reaction allowed suggesting a mechanism for the Cu(II)‐induced cleavage of Agly peptides. Copyright © 2010 European Peptide Society and John Wiley & Sons, Ltd.     

C-terminal glyoxylyl peptides for sensitive enzyme-linked immunosorbent assays

Summary A model peptide antigen derived from HCV Core protein was modified by a hydrophilic glyoxylamide arm using a tartaramide-based linker and used in an enzyme-linked immunosorbent assay (ELISA) on hydrazide plates. A comparative study with the standard non-covalent adsorption procedures demonstrated a large gain in sensitivity for the detection of antibodies in HCV-positive sera.     

Karyotype analysis by computer and its application to mutagenicity testing of environmental chemicals

Large scale population monitoring by cytogenetics would require vast amounts of effort for meaningful results. Computer techniques promise to assume some of this burden and thus render large scale monitoriong a more practical alternative than it is now. A system recently developed at the California Institute of Technology, Jet Propulsion Laboratory and the City of Hope Medical Center, contains many of the features required by a large scale population monitoring system. One part of the system is a semi-automated slide preparation assembly which can process up to 576 specimens per day with uniform treatment. The second part of the system consists of a computer-controlled microscope which performss automatic slide search, metaphase location, and karyotype analysis under the interactive supervision of an operator. While the system was developed primarily for clinical cytogenetics, some aspects of our operating experience suggest promising approaches for population cytogenetics.     

Dermatoglyphics of the XYY Syndrome

The presence of an extra Y chromosome in Man results in a condition termed the XYY Syndrome. Such individuals are tall, exhibit aggressive behavior, and may be mentally retarded. XYY patients are usually discovered after they have committed a crime. Even though relatively few XYY patients have been recorded so far in the literature the incidence of this condition in US males has been estimated at 1 in 300. Thus the majority of XYY's lead normal lives, directing their excess aggression into legal channels. For those who do not do so, the earlier corrective educational therapy is constituted the better the result. Since dermatoglyphics are affected by chromosomal aberrations there is a need to examine the dermatoglyphics of XYY patients in order to establish specific dermatoglyphic features that can be used for diagnosis at birth.     

Moderate increases in peripheral blood estradiol concentration in the adult ram do not directly inhibit testosterone secretion.

Two experiments were conducted in July with adult Dorset x Leicester x Suffolk rams to determine whether increases of 150 or 300% in estradiol (E2) concentration in peripheral blood (from 6.3 +/- 0.8 pg/mL in control rams) would affect testosterone secretion directly as well as indirectly via the hypothalamic-pituitary axis. After 4 days of estradiol treatment (experiment 1) provided with subcutaneous polydimethylsiloxane implants filled with crystalline estradiol, luteinizing hormone (LH) and testosterone secretions were reduced by 50% (p < 0.05) in both groups of rams because of subtle decreases in pulse frequencies and amplitudes. Estradiol treatments were also associated with decreases in mean follicle-stimulating hormone (FSH) concentration (30-50% in both groups, p < 0.05) and increases in mean prolactin concentration (35% in low-E2 group; 105% in high-E2 group, p < 0.05), but testicular responsiveness to an LH challenge (single intravenous dose, 10 micrograms NIH-LH-S25) remained normal. When along with estradiol treatment, 10-micrograms doses LH were given every 80 min (experiment 2), testosterone secretion increased by 265% (p < 0.05) in both treated and control rams. Relative to day -1, secretion on day 4 was characterized by higher (p < 0.05) pulse frequencies and baseline concentrations and lower (p < 0.05) pulse amplitudes; values for all characteristics were similar to those for Dorset x Leicester x Suffolk rams in the breeding season. Interestingly, the decreases in mean FSH concentration brought about by estradiol and (or) LH treatments were not any greater than in experiment 1, and estradiol's ability to elevate mean prolactin concentration was blocked completely.(ABSTRACT TRUNCATED AT 250 WORDS)