Stephen M. Roper

Targeted glycoprotein enrichment and identification in stromal cell secretomes using azido sugar metabolic labeling

Effectively identifying the proteins present in the cellular secretome is complicated due to the presence of cellular protein leakage and serum protein supplements in culture media. A metabolic labeling and click chemistry capture method is described that facilitates the detection of lower abundance glycoproteins in the secretome, even in the presence of serum.

Current Status of Biomarker Discovery in Human clear Cell Renal Cell Carcinoma

The incidence of clear cell renal cell carcinoma (ccRCC) continues to increase while very few treatment options are available for therapy. Development of metastatic disease dramatically decreases patient survival; therefore detection at an early stage while still localized to the renal capsule is imperative for a favorable prognosis. With recent advances in molecular technologies and subsequent understanding of the underlying pathology of disease, molecular markers have been defined that are predicative of tumor stage, metastatic potential and patient prognosis. Analysis of these biomarkers along with current staging techniques already used in the clinic may allow for implementation of personalized post-surgical treatment plans as well provide further molecular pathways for targeted therapeutic interventions. In this review we will highlight the potential ccRCC biomarkers that have been identified through a variety of molecular techniques to date, and provide insight into research models for biomarker discovery.

To Fast or Not to Fast?: Comments on the Consensus Statement From the European Atherosclerosis Society/European Federation of Clinical Chemistry and Laboratory Medicine

The European Atherosclerosis Society/European Federation of Clinical Chemistry and Laboratory Medicine recently published a consensus statement promoting the routine use of nonfasting blood samples for the assessment of plasma lipid profiles. That statement follows the consensus recommendation that has been implemented in Denmark since 2009 and in the United Kingdom since 2014, whereas in the United States, the most recent 2013 American College of Cardiology/American Heart Association guideline does not require fasting blood samples for estimation of atherosclerotic cardiovascular disease (ASCVD) risk, but the guideline recommends a fasting lipid panel to calculate low-density lipoprotein cholesterol (LDLC) before initiating statin treatment, and for individuals with non–high-density lipoprotein cholesterol levels (non–HDLC) of 220 mg/dL or greater (to convert to millimoles per liter, multiply by 0.0259) or triglyceride (TG) levels of 500 mg/dL or greater (to convert to millimoles per liter, multiply by 0.0113). The rationale for the European Atherosclerosis Society/European Federation of Clinical Chemistry and Laboratory Medicine stance is ease of collection and greater compliance in patient preparation for lipid testing. Nonfasting cholesterol levels (total cholesterol, non–HDL-C, and LDL-C) are comparable to fasting cholesterol levels in predicting ASCVD, whereas nonfasting TG levels showed even stronger associations with ASCVD compared with fasting results. This statement addresses the perceived limitations of testing nonfasting samples by referencing data from studies that evaluated lipid variation in postprandial versus fasting states, showing that there is no change in HDL-C, apolipoprotein A1, apolipoprotein B, or lipoprotein(a) levels and minimal changes in TG, total cholesterol, calculated remnant cholesterol, non–HDL-C, and LDL-C values. In addition, this article addresses the influence of the postprandial state on the assessment of cardiovascular disease risk by citing studies in which various nonfasting lipid parameters were monitored relative to clinical outcomes. The conclusion here was that nonfasting lipid testing may actually be superior to fasting lipid profiles for predicting cardiovascular disease. Finally, the consensus statement recommends that the abnormal lipid values obtained from nonfasting samples should be flagged based on desirable lipid cutoffs published by accepted guidelines and consensus statements.

Performance of Calculated and Directly Measured Low-Density Lipoprotein Cholesterol in a Pediatric Population

Objectives An assessment of methods for the accurate measurement of low-density lipoprotein cholesterol (LDL-C) at decreased concentrations has not yet been carried out. We evaluated the performance of the Friedewald equation, a direct enzymatic assay, and a novel equation for determining LDL-C levels in a pediatric population with elevated triglycerides and reduced LDL-C levels. Methods LDL-C concentrations of 127 pediatric patients were determined by the Friedewald equation, a direct enzymatic assay, and a novel equation. The bias of each approach was assessed at selected LDL-C cutoffs and after stratifying samples by triglyceride content. The concordance of each approach, relative to the reference method, was determined at LDL-C cut-points of less than 70, 70 to 99, and 100 to 129 mg/dL. Results The Friedewald equation substantially underestimated pediatric LDL-C concentrations below 100 mg/dL in the presence of elevated triglycerides. The Ortho Clinical Diagnostics (Raritan, NJ) direct LDL assay was positively biased at low LDL-C levels. The novel equation most effectively reduced the bias of the Friedewald equation at all LDL-C concentrations and increased the concordance of sample classification to the reference method. Conclusions The novel equation should be used for accurate measurement of pediatric LDL-C when the concentration is below 100 mg/dL in the presence of elevated triglycerides (150-399 mg/dL).