Environmental factors in the development and progression of late-onset Alzheimer's disease.

Late-onset Alzheimer's disease (LOAD) is an age-related neurodegenerative disorder characterized by gradual loss of synapses and neurons, but its pathogenesis remains to be clarified. Neurons live in an environment constituted by neurons themselves and glial cells. In this review, we propose that the neuronal degeneration in the AD brain is partially caused by diverse environmental factors. We first discuss various environmental stresses and the corresponding responses at different levels. Then we propose some mechanisms underlying the specific pathological changes, in particular, hypothalamic-pituitary adrenal axis dysfunction at the systemic level; cerebrovascular dysfunction, metal toxicity, glial activation, and Aß toxicity at the intercellular level; and kinase-phosphatase imbalance and epigenetic modification at the intracellular level. Finally, we discuss the possibility of developing new strategies for the prevention and treatment of LOAD from the perspective of environmental stress. We conclude that environmental factors play a significant role in the development of LOAD through multiple pathological mechanisms.

A manual sequence method of peptides and phosphopeptides using 4-(1'-cyanoisoindolyl)phenylisothiocyanate.

A method for sequence analysis and identification of phosphoamino acids in peptides based on high performance liquid chromatography (HPLC) is described. The peptides were derivatized with an Edman type reagent, 4-(1'-cyanoisoindolyl)phenylisothiocyanate (CIPIC) and subsequently cleaved to generate stable and fluorescent 4-(1'-cyanoisoindolyl)phenylthiazolinone (CIP-TZ)-amino acids. Several experimental factors that affected derivatization on membranes were examined. Under the optimized conditions, the CIP-TZ derivatives of Try(p), Thr(p) and Ser(p) were obtained and separated from their parent amino acids with baseline resolution using an isocratic elution system. Up to the 4th residue of phosphorylated pentapeptides was successfully identified, whereas phosphoamino acid residues could not be detected by the conventional procedure using phenylisothiocyanate (PITC). The results demonstrated the potential of CIPIC as a derivatization reagent for peptide sequencing and the applicability of the method for the study and identification of phosphoamino acids in peptides.

Fluorescence detection of amino acids in the postcleavage conversions for manual sequencing of a peptide.

A modified Edman degradation method where fluorescent derivatives of amino acids were generated from the postcleavage products of a peptide is described. In the method, the target peptide was applied onto double glass fiber membranes in a small filter disk (4 mm i.d.) and then treated with small amounts of reagents for the manual sequencing of the peptide. The anilinothiazolinone (ATZ) of N-terminus amino acid residue after the isolation from the solid-phase membranes was reacted with a primary amine, 4-(1'-cyanoisoindolyl)aniline (CIA), to form a more stable and sensitive fluorescent derivative, phenylthiocarbamoyl-CIA. An average yield of 85% was obtained in neutral pH conditions for the CIA reaction. The ATZ-CIA-amino acids were separated by reversed-phase liquid chromatography and detected by fluorometry. The lower limits of the detection for amino acids after the Edman degradation were 0.16 to 0.52 pmol (signal/noise ratio=3) on the column. The sensitivity was approximately 10 times higher than ultraviolet absorbance detection of phenylthiohydantoin products in the conventional Edman degradation. The suitability of the method was demonstrated by the sensitive manual sequencing of insulin chain B composed of 30 amino acids.