Background: Mass spectrometry (MS) is being introduced into a large number of clinical laboratories. It provides specificity because of its ability to monitor selected mass ions, sensitivity because of the enhanced signal-to-noise ratio, and speed because it can help avoid the need for intensive sample cleanup and long analysis times. However, MS is not without problems related to interference, especially through ion suppression effects. Ion suppression results from the presence of less volatile compounds that can change the efficiency of droplet formation or droplet evaporation, which in turn affects the amount of charged ion in the gas phase that ultimately reaches the detector. Content: This review discusses materials shown to cause ion suppression, including salts, ion-pairing agents, endogenous compounds, drugs, metabolites, and proteins. Experimental protocols for examining ion suppression, which should include, at a minimum, signal recovery studies using specimen extracts with added analyte, are also discussed, and a more comprehensive approach is presented that uses postcolumn infusion of the analyte to evaluate protracted ionization effects. Finally, this review presents options for minimizing or correcting ion suppression, which include enhanced specimen cleanup, chromatographic changes, reagent modifications, and effective internal standardization. Summary: Whenever mass spectrometric assays are developed, ion suppression studies should be performed using expected physiologic concentrations of the analyte under investigation.

IntroductionPreviously we have demonstrated that systemic activation of the complement system after intravenous injection of cobra venom factor (CVF)

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Magnesium has been used empirically for several decades in the treatment of atrial and ventricular arrhythmias in patients with normal and decreased serum magnesium levels. However, a systematic evaluation of the effects of magnesium on cardiac conduction and refractoriness in humans has not been described. In this study, the electrocardiographic and electrophysiologic effects of magnesium were determined in 10 patients with normal baseline serum magnesium and other electrolyte levels. Six grams of magnesium sulfate was administered intravenously over 6 minutes followed by a continuous infusion of 1 additional gram over 1 hour. Serum magnesium levels rose significantly from a baseline of 2.0 +/- 0.2 to 5.4 +/- 0.4 mg/dl (p less than 0.001). No significant change occurred in heart rate at rest, or in duration of the QRS complex or QT or QTc intervals during sinus rhythm. There were significant increases in sinus node recovery time (1,000 +/- 211 to 1,106 +/- 223 ms, p less than 0.01) and corrected sinus node recovery time (279 +/- 87 to 336 +/- 104 ms, p less than 0.05). Significant increases occurred in atrioventricular (AV) node conduction time during sinus rhythm (82 +/- 22 to 97 +/- 17 ms, p less than 0.02), in the atrial paced cycle length at which AV node Wenckebach block occurred (350 +/- 46 to 419 +/- 65 ms, p less than 0.01) and in the AV node relative refractory period (397 +/- 27 to 422 +/- 18 ms, p less than 0.05), functional refractory period (395 +/- 41 to 415 +/- 33 ms, p less than 0.05) and effective refractory period (306 +/- 67 to 338 +/- 38 ms, p less than 0.05).

In the judicial system in many countries, a jury decides the final outcome in a court case. The proceedings begin with a lawyer providing an opening statement telling the jury what he or she plans to present. Through a variety of chosen tactics and methods, the lawyer then presents the various pieces of evidence, all of which lead up to the closing argument. A poor closing argument can hurt even the best case. A great closing argument can convince the jury that the evidence is sound and the lawyer's interpretation of it has merit. In the original Law & Order TV show, which incorporated both the investigation of a crime and the courtroom proceedings, the closing arguments were often the most compelling and defining moments in the show.The Discussion section in a scientific paper and the closing argument in a courtroom have similarities. For many readers, the most important information is not what your results show but what your results mean. The purpose of the Discussion section is to explain what your results mean and what contribution your paper makes to the field of study. The Discussion section is your closing argument. Numerous scientists have told me that when reading a paper they first look at the Abstract to get an overview of the topic and the purported findings. If the topic appears to be of interest, they then skip to the Discussion section. If the Discussion is neither stimulating nor convincing about the meaning and importance of the findings, it does not really matter how the experiments were performed or what results were reported. A poor Discussion detracts from a scientific paper. A good Discussion adds a strong finish to a scientific paper. It brings meaning to your study. My goal with this article is to help you understand the characteristics of a good Discussion section.