抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

Jeffrey L. Anderson, MD, FACC, FAHA, Chair 

Jonathan L. Halperin, MD, FACC, FAHA, Chair-Elect 

Nancy M. Albert, PhD, RN, FAHA

Biykem Bozkurt, MD, PhD, FACC, FAHA

Ralph G. Brindis, MD, MPH, MACC

Mark A. Creager, MD, FACC, FAHA[#][1]

Lesley H. Curtis, PhD, FAHA

David DeMets, PhD[#][1]

Robert A

/pdf/2014-aha-acc-hrs-guideline-for-the-management-of-patients-1v8ficsqox.pdf

2014 AHA/ACC/HRS Guideline for the Management of Patients With Atrial Fibrillation: A Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and the Heart Rhythm Society

Sidney C. Smith, Jr, MD, FACC, FAHA, FESC, Chair; Alice K. Jacobs, MD, FACC, FAHA, Vice-Chair; Cynthia D. Adams, MSN, APRN-BC, FAHA; Jeffery L. Anderson, MD, FACC, FAHA; Elliott M. Antman, MD, FACC, FAHA[‡][1]; Jonathan L. Halperin, MD, FACC, FAHA; Sharon Ann Hunt, MD, FACC, FAHA; Rick Nishimura,

/pdf/acc-aha-esc-2006-guidelines-for-the-management-of-patients-5fc8py53ut.pdf

ACC/AHA/ESC 2006 Guidelines for the Management of Patients With Atrial Fibrillation A Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and the European Society of Cardiology Committee for Practice Guidelines (Writing Committee to Revise the 2001 Guidelines for the Management of Patients With Atrial Fibrillation): Developed in Collaboration With the European Heart Rhythm Association and the Heart Rhythm Society

THE slowly activating delayed-rectifier K+ current, IKS, modulates the repolarization of cardiac action potentials. The molecular structure of the IKS channel is not known, but physiological data indicate that one component of theIKSchannel is minK (refs 1–6), a 130-amino-acid protein with a single putative transmembrane domain7. The size and structure of this protein is such that it is unlikely that minK alone forms functional channels8,9. We have previously used positional cloning techniques to define a new putative K+-channel gene, KVLQT110. Mutations in this gene cause long-QT syndrome, an inherited disorder that increases the risk of sudden death from cardiac arrhythmias. Here we show that KVLQT1 encodes a K+ channel with biophysical properties unlike other known cardiac currents. We considered that KVLQT1 might coassemble with another subunit to form func-tional channels in cardiac myocytes. Coexpression of KVLQT1 with minK induced a current that was almost identical to cardiac IKS. Therefore, KVLQT1 is the subunit that coassembles with minK to form IKS channels and IKS dysfunction is a cause of cardiac arrhythmia.

Coassembly of K(V)LQT1 and minK (IsK) proteins to form cardiac I(Ks) potassium channel.

Atrial fibrillation (AF), the most common sustained cardiac rhythm disturbance, is increasing in prevalence as the population ages. Although it is often associated with heart disease, AF occurs in many patients with no detectable disease. Hemodynamic impairment and thromboembolic events result in significant morbidity, mortality, and cost. Accordingly, the American College of Cardiology (ACC), the American Heart Association (AHA), and the European Society of Cardiology (ESC) created a committee of experts to establish guidelines for management of this arrhythmia.

The committee was composed of 8 members representing the ACC and AHA, 4 representing the ESC, 1 from the North American Society of Pacing and Electrophysiology (NASPE), and a representative of the Johns Hopkins University Evidence-Based Practice Center representing the Agency for Healthcare Research and Quality’s report on Atrial Fibrillation in the Elderly. This document was reviewed by 3 official reviewers nominated by the ACC, 3 nominated by the AHA, and 3 nominated by the ESC, as well as by the ACC Clinical Electrophysiology Committee, the AHA ECG and Arrhythmia Committee, NASPE, and 25 reviewers nominated by the writing committee. The document was approved for publication by the governing bodies of the ACC, AHA, and ESC and officially endorsed by NASPE. These guidelines will be reviewed annually by the task force and will be considered current unless the task force revises or withdraws them from distribution.

The committee conducted a comprehensive review of the literature from 1980 to June 2000 relevant to AF using the following databases: PubMed/Medline, EMBASE, the Cochrane Library (including the Cochrane Database of Systematic Reviews and the Cochrane Controlled Trials Registry), and Best Evidence. Searches were limited to English language sources and to human subjects.

### A. Atrial Fibrillation

AF is a supraventricular tachyarrhythmia characterized by uncoordinated atrial activation with consequent deterioration of atrial mechanical function. On the electrocardiogram (ECG), AF …

/pdf/acc-aha-esc-guidelines-for-the-management-of-patients-with-4281694a2b.pdf

ACC/AHA/ESC Guidelines for the Management of Patients With Atrial Fibrillation: Executive Summary A Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and the European Society of Cardiology Committee for Practice Guidelines and Policy Conferences (Committee to Develop Guidelines for the Management of Patients With Atrial Fibrillation) Developed in Collaboration With the North American Society of Pacing and Electrophysiology

Rapid electrical activation, as occurs during atrial fibrillation (AF), is known to cause reductions in atrial refractoriness and in adaptation to heart rate of the atrial refractory period, which promote the maintenance of AF, but the underlying ionic mechanisms are unknown. In order to determine the cellular and ionic changes caused by chronic atrial tachycardia, we studied right atrial myocytes from dogs subjected to 1, 7, or 42 days of atrial pacing at 400/min and compared them with myocytes from sham-operated dogs (pacemaker inserted but not activated). Rapid pacing led to progressive increases in the duration of AF induced by bursts of 10-Hz stimuli (from 3 +/- 2 seconds in sham-operated dogs to 3060 +/- 707 seconds in dogs after 42 days of pacing, P < .001) and reduced atrial refractoriness and adaptation to rate of the atrial refractory period. Voltage-clamp studies showed that chronic rapid pacing did not alter inward rectifier K+ current, rapid or slow components of the delayed rectifier current, the ultrarapid delayed rectifier current, T-type Ca2+ current, or Ca(2+)-dependent Cl- current. In contrast, the densities of transient outward current (Ito) and L-type Ca2+ current (ICa) were progressively reduced as the duration of rapid pacing increased, without concomitant changes in kinetics or voltage dependence. In keeping with in vivo changes in refractoriness, action potential duration (APD) and APD adaptation to rate were decreased by rapid pacing. The response of the action potential and ionic currents flowing during the action potential (as exposed by action-potential voltage clamp) to nifedipine in normal canine cells and in cells from rapidly paced dogs suggested that the APD changes in paced dogs were largely due to reductions in ICa. We conclude that sustained atrial tachycardia reduces Ito and ICa, that the reduced ICa decreases APD and APD adaptation to rate, and that these cellular changes likely account for the alterations in atrial refractoriness associated with enhanced ability to maintain AF in the model.

Ionic Remodeling Underlying Action Potential Changes in a Canine Model of Atrial Fibrillation

Previous voltage-clamp studies have suggested that the delayed rectifier current (IK) is small or absent in the human ventricle and, when present, consists only of the rapid component (IKr); however, molecular studies suggest the presence of functionally important IK in the human heart, specific IKr blockers are known to delay ventricular repolarization and cause the long QT syndrome in humans, and we have shown that the expression of IK is strongly influenced by cell isolation techniques. The present experiments were designed to assess the expression of IK in myocytes obtained by arterial perfusion of right ventricular tissue from explanted human hearts. Of 35 cells from three hearts, 33 (94%) showed time-dependent currents typical of IK. The envelope-of-tails test was not satisfied under control conditions but became satisfied in the presence of the benzenesulfonamide E-4031 (5 μmol/L). E-4031 suppressed a portion of IK in 32 of 33 cells, with properties of the drug-sensitive and -resistant components consistent with previous descriptions of IKr and the slow component (IKs), respectively. Action potential duration to 95% repolarization at 1 Hz was prolonged by E-4031 from 336±16 (mean±SEM) to 421±19 ms (n=5, P <.01), indicating a functional role for IK. Indapamide, a diuretic agent previously shown to inhibit IKs selectively, suppressed E-4031–resistant current. The presence of a third type of delayed rectifier, the ultrarapid delayed rectifier current (IKur), was evaluated with the use of depolarizing prepulses and low concentrations (50 μmol/L) of 4-aminopyridine. Although these techniques revealed clear IKur in five of five human atrial cells, no corresponding component was observed in any of five human ventricular myocytes. We conclude that a functionally significant IK, with components corresponding to IKr and IKs, is present in human ventricular cells, whereas IKur appears to be absent. These findings are important for understanding the molecular, physiological, and pharmacological determinants of human ventricular repolarization and arrhythmias.

Evidence for Two Components of Delayed Rectifier K+ Current in Human Ventricular Myocytes

Several cloned K+ channel subunits are candidates to underlie macroscopic currents in the human heart, but direct evidence bearing on their role is lacking. The Kv1.5 K+ channel subunit ha...

Antisense Oligodeoxynucleotides Directed Against Kv1.5 mRNA Specifically Inhibit Ultrarapid Delayed Rectifier K+ Current in Cultured Adult Human Atrial Myocytes

Heart failure (HF) produces important alterations in currents underlying cardiac repolarization, but the transmural distribution of such changes is unknown. We therefore recorded action potentials ...

Transmural action potential and ionic current remodeling in ventricles of failing canine hearts.

Limited information is available about transmural heterogeneity in cardiac electrophysiology in man. The present study was designed to evaluate heterogeneity of cardiac action potential (AP), trans...

Gui-Rong Li

Papers

Ionic Remodeling Underlying Action Potential Changes in a Canine Model of Atrial Fibrillation

Evidence for Two Components of Delayed Rectifier K+ Current in Human Ventricular Myocytes

Antisense Oligodeoxynucleotides Directed Against Kv1.5 mRNA Specifically Inhibit Ultrarapid Delayed Rectifier K+ Current in Cultured Adult Human Atrial Myocytes

Transmural action potential and ionic current remodeling in ventricles of failing canine hearts.

Transmural heterogeneity of action potentials and Ito1 in myocytes isolated from the human right ventricle.