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The universal definition of myocardial infarction requires both an increase in cardiac troponin concentrations and changes in values over serial measurements. However, exact criteria regarding the magnitude of change in troponin remain elusive. In the June 2014 issue of Clinical Chemistry, two studies on biological variation of serum troponins helped shed further light on the kinetics of this important cardiac marker.!

On the cover this month: "Chicago" Neon Sign. Each year the July cover highlights the location of the AACC's Annual Meeting and Clinical Lab Expo. It does not take much effort to identify this year's host city. The Chicago Theatre, built in 1921, was originally known as the Balaban and Katz Chicago Theatre. The preeminent theatre for nearly 50 years, this ornate but obsolete movie house closed in 1985. But it did not die. After a meticulous renovation, this 3600-seat, 7-story high icon with its 29-rank Wurlitzer theatre pipe organ regained prominence and is as popular today as it was nearly 100 years ago. Of course, there is more to Chicago than this one theatre. There are dozens of art galleries, 26 miles of lakefront, and the Magnificent Mile. But most importantly, this year Chicago is the home of cutting-edge science and the world's largest Clinical Lab Expo, which will provide you with all you need to make informed decisions about the future of your laboratory. See you in Chicago!

Laboratory test results are used to aid decisions in the diagnosis and treatment of disease. Consistent and comparable results from different measurement procedures are important for developing clinical practice guidelines, and for those guidelines to be applied to decisions about patient care. Yet results for many analytes are neither consistent nor comparable when measured using different clinical laboratory procedures.

One of the largest direct consumer genetic testing facilities, 23andMe, was ordered by the US Food and Drug Administration to cease marketing its Personal Genome Service test in late 2013. This occurred after 23andMe failed to respond to questions that the FDA had about the analytical and clinical validity of this test. While some support the FDA's actions because of the test potential for harm to consumers, some advocates of the technology fault the FDA for being overly paternalistic and impeding medical advances.

The clinical utility of molecular genetic testing relies on an accurate and comprehensive knowledge about the relationships between genes and variants, and diseases. Correctly interpreting the clinical significance of variants that may be detected continues to be a constant challenge for molecular diagnostic practice. This challenge has become substantially enlarged as next generation sequencing-based testing becomes rapidly integrated into routine clinical practice.

In the May issue of Clinical Chemistry, researchers involved in the Copenhagen City Heart Study found that lower nonfasting, circulating triglyceride concentrations are associated with lower all-cause mortality.

This is the June 2014 issue of Clinical Chemistry, Volume 60, Issue 6.

Increased nonfasting plasma triglycerides indicating increase amounts of cholesterol in remnant liver proteins and are important risk factors for cardiovascular disease. In the May issue of Clinical Chemistry, researchers involved in the Copenhagen City Heart Study found that lower circulating triglyceride concentrations are associated with lower all-cause mortality.

This is a podcast from Clinical Chemistry, sponsored by the Department of Laboratory Medicine at Boston Children's Hospital.

In well-resourced countries with a low incidence of tuberculosis, a major focus of TB control efforts is the detection and treatment of latent TB infection to prevent reactivation to active TB disease. This approach is particularly relevant for healthcare workers. Interferon Gamma Release Assays are used to detect the release of interferon from T cells stimulated by tuberculosis specific antigens. However, these tests differ in cost and complexity than the conventional tuberculin skin test.

Recent studies have demonstrated that a variety of cells release exosomes or microvesicles into nearby biological fluids such as blood and saliva. During the exocytic process various proteins' messenger RNA and micro RNA are included in these exosomes.

This is the May 2014 issue of Clinical Chemistry, Volume 60, Issue 5

Tacrolimus or FK506 is a macrocyclic lactone that is commonly used along with other immunosuppressant drugs to reduce graft rejection in organ transplantation by suppressing the immune system. Because of its narrow therapeutic window, it is critical to accurately monitor blood concentrations of this drug for optimal efficacy.

Platelet function testing has traditionally been used to diagnose inherited qualitative and quantitative defects in platelet function, such as Von Willebrand disease, but with the increased use of anti-platelet agents to prevent arterial thrombosis and the interest in identifying patients at risk for thrombosis despite anti-platelet therapy, the use of platelet function testing to monitory response to anti-platelet therapy, for example, aspirin, has become a hot topic.

Over the past several years, investigations have shown that many clinical studies remain unpublished and even among published studies the results are often presented selectively.

Pregnancy tests such as the ones used to test urine in hospitals have been shown to give false-negative results in certain patients.

In the February 2014 issue of Clinical Chemistry, the influence of PCR reagents on DNA polymerase extension rates were studied by examining nucleotide incorporation with DNA dyes. We are joined by one of the authors of that study, Dr. Carl Wittwer. He is Professor of Pathology at the University of Utah Health Sciences Center and is also affiliated with ARUP Laboratories, BioFire Diagnostics, and is an Associate Editor of Clinical Chemistry.

This is the April 2014 issue of Clinical Chemistry, Volume 60, Issue 4.

Type 1 diabetes is a chronic progressive autoimmune disorder with complex, polygenic susceptibility. Environmental factors which are poorly defined also contribute to the pathogenesis. This disease is characterized by lymphocyte infiltration into the islets of Langerhans in the pancreas, leading to inflammation and selective destruction of the insulin-producing beta cells resulting in hyperglycemia.

The latest incarnation of polymerase chain reaction, Digital PCR, takes three decades of development in enzyme chemistry and assay design and applies them with formidable precision and sensitivity.