Peptide hormones, levels detected

Trisulfide bonds, originally elucidated in human growth hormone," " were detected recently in mAbs at low levels.The linkage between light and heavy chain is the predominant location of trisulfide bonds in mAbs. Ironically, nonreducible thioether bonds were detected previously at this same disulfide bond linkage in mAbs via peptide map analysis." " ... 

The endogenous release of the potent vasoconstrictor neuropeptide Y (NPY) is increased during sepsis and the highest levels are detected in patients with shock (A8). NPY is a 36-amino-acid peptide belonging to the pancreatic polypeptide family of neuroendocrine peptides (T2). It is one of the most abundant peptides present in the brain and is widely expressed by neurons in the central and peripheral nervous systems as well as the adrenal medulla (A3). NPY coexists with norepinephrine in peripheral sympathetic nerves and is released together with norepinephrine (LI9, W14). NPY causes direct vasoconstriction of cerebral, coronary, and mesenteric arteries and also potentiates norepinephrine-induced vasoconstriction in these arterial beds (T8). It appears that vasoconstriction caused by NPY does not counterbalance the vasodilatator effects of substance P in patients with sepsis. The properties of vasodilatation and smooth muscle contraction of substance P are well known (14), but because of the morphological distribution and the neuroendocrine effects a possible stress hormone function for substance P was also advocated (J7). Substance P, which is a potent vasodilatator agent and has an innervation pathway similar to that of NPY, shows a low plasma concentration in septic patients with and without shock (A8). 

A large number of studies (33) support the thesis (59) that the function of GA may be that of a derepressor of gene activity. Giberellic acid has significant effect on the synthesis of all species of RNA s (63, 64), but the formation of < —amylase does not depend on new synthesis of ribosomal and transfer RNA s. Unequivocal proof for GA-induced formation of transcripts was provided by the in vitro synthesis of peptides that are immuno-logically similar to -amylase on poly A+RNA templates that were. isolated from hormone-treated aleurone cells (65, 66, 67). Of particular significance is the finding that detectable levels of -amylase mRNA s were formed within 2 hr of treatment with GA. 

Various methods were evaluated for the targeted proteomics of human growth hormone (hGH) in human plasma [111]. hGH was spiked in plasma 10-fold above natural level ( 16 pg/pl). Iiutially, the full plasma proteome was reduced, alkylated, and digested prior to LC-MS via DDA on an ion-trap instrument. hGH could be identified from its T, peptide. Next, the plasma proteome was fractionated by RPLC and GE prior to digestion and LC-MS analysis. hGH could be identified with higher confidence. Finally, an LCxLC-MS approach was apphed, which enabled hGH identification from five tryptic peptides. An important conclusion was that hGH could be detected in a complex sample at the low femtomole level among proteins that were 40,000 x more abundant. The results show that a multidimensional approach may be taken for targeted proteomics and quantitative protein bioanalysis. 

Of the thymic hormones currently undergoing clinical evaluation, the most detailed pharmacokinetic studies have been performed with TF5 and Tuj. The parenteral administration of TF5 has been associated with the generation of detectable serum thymic hormone bioactivity as detected in the Bach-Dardenne assay (Iwata et ah, 1981). A 10-year-old child with chronic mucocutaneous candidiasis treated with TF5 showed a prompt rise of serum FTS-like bioactivity that persisted within the normal range for several weeks following the discontinuation of treatment, but which eventually returned to low levels (Iwata et ah, 1981). These studies have clearly demonstrated that the parenteral administration of TF5 generates detectable serum bioactivity. However, it cannot be determined which of the peptides present in TF5 gave rise to the serum activity. 

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