Height and heart disease.

Height has a relationship with a number of medical conditions, including heart disease. Atrial fibrillation has been observed to be more common in taller individuals. Marfan syndrome, with its high prevalence of mitral valve disease and abnormalities of the aorta, is associated with increased height. Mitral valve prolapse in patients without Marfan syndrome may be more common in taller people. Conversely, congestive heart failure, coronary artery disease, and possibly aortic valve calcification are less prevalent with increasing height. The relationship between height and health will be of increasing importance as the population grows taller.

Safety of ultrasound contrast agents in patients with known or suspected cardiac shunts.

Contrast-enhanced ultrasound imaging is a radiation-free diagnostic tool that uses biocompatible ultrasound contrast agents (UCAs) to improve image clarity. UCAs, which do not contain dye, often salvage "technically difficult" ultrasound scans, increasing the accuracy and reliability of a front-line ultrasound diagnosis, reducing unnecessary downstream testing, lowering overall health care costs, changing therapy, and improving patient care. Two UCAs currently are approved and regulated by the US Food and Drug Administration. They have favorable safety profiles and risk/benefit ratios in adult and pediatric populations, including compromised patients with severe cardiovascular diseases. Nevertheless, these UCAs are contraindicated in patients with known or suspected right-to-left, bidirectional, or transient right-to-left cardiac shunts. These patients, who constitute 10% to 35% of the general population, typically receive no UCAs when they undergo echocardiography. If their echocardiographic images are suboptimal, they may receive inappropriate diagnosis and treatment, or they may be referred for additional diagnostic testing, including radiation-based procedures that increase their lifetime risk for cancer or procedures that use contrast agents containing dye, which may increase the risk for kidney damage. An exhaustive review of current peer-reviewed research demonstrated no scientific basis for the UCA contraindication in patients with known or suspected cardiac shunts. Initial safety concerns were based on limited rodent data and speculation related to macroaggregated albumin microspheres, a radioactive nuclear imaging agent with different physical and chemical properties and no relation to UCAs. Radioactive macroaggregated albumin is not contraindicated in adult or pediatric patients with cardiac shunts and is routinely used in these populations. In conclusion, the International Contrast Ultrasound Society Board recommends removal of the contraindication to further the public interest in safe, reliable, radiation-free diagnostic imaging options for patients with known or suspected cardiac shunts and to reduce their need for unnecessary downstream testing.

Recurrent, severe, and rapidly reversible apical ballooning syndrome in status asthmaticus.

Apical ballooning syndrome, or Tako-tsubo cardiomyopathy, is a peculiar form of transient left-ventricular dysfunction originally described as triggered by emotional stress. Subsequent reports indicated that physical stressors can also induce this clinical syndrome. We describe for the first time, to the best of our knowledge, a case of recurrent, severe, and quickly reversible apical ballooning syndrome provoked by the use of high-dose inhaled ß-adrenergic agonists in status asthmaticus.

Significance of respiratory artifact in the electrocardiogram.

Electrocardiographic artifact is generally considered to be a nuisance. Respiratory artifact, however, is a physiologic signal that may carry useful diagnostic information. Our goal was to evaluate the characteristics, prevalence, and clinical significance of respiratory artifact observed in electrocardiograms (ECGs). ECGs exhibiting repetitive microoscillations were systematically collected. The morphologic characteristics of the microoscillations were analyzed and their association with the respiratory cycle was evaluated using simultaneous respiratory waveform tracings. The presence and rate of respiratory artifact were correlated with the patient's clinical status, including medical diagnoses and the need for ventilatory support. During a 30-month period, respiratory artifact was detected in 320 12-lead ECGs. It was best seen in leads II, III, aVF, and V5. Respiratory artifact occurred during the inspiratory phase and its rate correlated precisely with objective measures of the respiratory rate. The majority of patients with respiratory artifact revealed diseases of the respiratory (26.6%) and circulatory systems (24.0%) and, of note, respiratory artifact was never detected in patients with normal cardiorespiratory function; 43.5% of patients with respiratory artifact required ventilatory support, including 28.2% requiring continuous mechanical ventilation. Successful treatment of the underlying condition resulted in a decrease in the rate or in complete disappearance of the respiratory artifact. In conclusion, respiratory artifact is commonly seen in routine 12-lead ECGs of hospitalized patients. It is associated with a high-risk state of increased work of breathing due to either compromised cardiac or pulmonary function. Additionally, the presence of respiratory artifact enables precise evaluation of the respiratory rate-a commonly miscalculated vital sign.

Effects of deletion and site-directed mutations on ligation steps of NAD+-dependent DNA ligase: a biochemical analysis of BRCA1 C-terminal domain.

DNA strand joining entails three consecutive steps: enzyme adenylation to form AMP-ligase, substrate adenylation to form AMP-DNA, and nick closure. In this study, we investigate the effects on ligation steps by deletion and site-directed mutagenesis of the BRCA1 C-terminal (BRCT) domain using NAD(+)-dependent DNA ligase from Thermus species AK16D. Deletion of the BRCT domain resulted in substantial loss of ligation activity, but the mutant was still able to form an AMP-ligase intermediate, suggesting that the defects caused by deletion of the entire BRCT domain occur primarily at steps after enzyme adenylation. The lack of AMP-DNA accumulation by the domain deletion mutant as compared to the wild-type ligase indicates that the BRCT domain plays a role in the substrate adenylation step. Gel mobility shift analysis suggests that the BRCT domain and helix-hairpin-helix subdomain play a role in DNA binding. Similar to the BRCT domain deletion mutant, the G617I mutant showed a low ligation activity and lack of accumulation of AMP-DNA intermediate. However, the G617I mutant was only weakly adenylated, suggesting that a point mutation in the BRCT domain could also affect the enzyme adenylation step. The significant reduction of ligation activity by G634I appears to be attributable to a defect at the substrate adenylation step. The greater ligation of mismatched substrates by G638I is accountable by accelerated conversion of the AMP-DNA intermediate to a ligation product at the final nick closure step. The mutational effects of the BRCT domain on ligation steps in relation to protein-DNA and potential protein-protein interactions are discussed.