A Targeted Liquid Chromatography-Tandem Mass Spectrometry Method for Simultaneous Quantification of Peptides from the Carboxyl-terminal Region of Type III Procollagen, Biomarkers of Collagen Turnover

BACKGROUND

The development of analytical approaches to help reduce the risk of growth hormone (GH) doping is important to fair competition and the health of athletes. However, the reliable detection of GH use remains challenging. The identification of novel biomarkers of GH administration could lead to a better understanding of the physiological response to GH, more sensitive detection of the illicit use of GH in sport, and better management of patients treated for GH disorders.

METHODS

We developed a targeted liquid chromatography-tandem mass spectrometry method to simultaneously quantify the carboxyl-terminal propeptide of type III procollagen (P-III-CP) and type III collagen degradation products in human serum. Following proteolysis, we instituted a simple acid precipitation step to reduce digested sample complexity before peptide immunoenrichment, which improved the recovery of one target peptide from serum. We evaluated the concentration of each biomarker at different age ranges and after GH administration in healthy participants.

RESULTS

The assay was linear over an estimated concentration range of 0.3 to1.0 nM and 0.1 to 0.4 nM for each surrogate peptide of P-III-CP and collagen fragments, respectively. Intra-day and inter-day coefficients of variation were ≤15%. Biomarker concentrations appeared to vary with age and to reflect age-specific collagen turnover. Moreover, their concentrations changed after GH administration.

CONCLUSIONS

Our method quantifies the proteins belonging to the family of P-III-CP and type III collagen degradation products in human serum, which could be used to detect GH administration in athletes and better understand diseases involving GH therapy or altered type III collagen turnover.

Dermabrasive scar revision. Immunohistochemical and ultrastructural evaluation

BACKGROUND

Dermabrasion of facial scars 4-8 weeks after injury frequently completely eliminates visible evidence of scar formation. However, efforts to define the cellular and structural mechanisms by which this phenomenon occurs have been limited in their success.

OBJECTIVE

We investigated wound healing after dermabrasive scar revision.

METHODS

The surgical scars of seven patients were abraded 6-8 weeks after injury. Comparative electron microscopic and immunohistochemical studies were performed on punch biopsy specimens taken before and after the dermabrasion. Ultrastructural changes in the basement membrane components and dermal structures were evaluated. Monoclonal antibody staining techniques were used to observe the presence, location, and temporal expression of tenascin, epiligrin, cadherins, and integrin subunits.

RESULTS

We observed: 1) an increase in collagen bundle density and size with a tendency toward unidirectional orientation of fibers parallel to the epidermal surface, 2) an upregulation of tenascin expression throughout the papillary dermis, and 3) expression of alpha-6/beta-4 integrin subunit on the keratinocytes throughout the stratum spinosum.

CONCLUSIONS

The mechanisms by which dermabrasive scar revision alters the events of primary cicatrix formation include modification of extracellular ligand expression, thereby influencing epithelial cell-cell interaction, and reorganization of connective tissue.