RNA binding motif (RBM) proteins: a novel family of apoptosis modulators?

RBM5 is a known modulator of apoptosis, an RNA binding protein, and a putative tumor suppressor. Originally identified as LUCA-15, and subsequently as H37, it was designated "RBM" (for RNA Binding Motif) due to the presence of two RRM (RNA Recognition Motif) domains within the protein coding sequence. Recently, a number of proteins have been attributed with this same RBM designation, based on the presence of one or more RRM consensus sequences. One such protein, RBM3, was also recently found to have apoptotic modulatory capabilities. The high sequence homology at the amino acid level between RBM5, RBM6, and particularly, RBM10 suggests that they, too, may play an important role in regulating apoptosis. It is the intent of this article to ammalgamate the data on the ten originally identified RBM proteins in order to question the existence of a novel family of RNA binding apoptosis regulators.

Isolated left ventricular apical hypoplasia: a new congenital anomaly described with cardiac tomography

OBJECTIVE

To describe cardiac tomography findings of an apparently new, presumably congenital, left ventricular (LV) abnormality noted consistently in three patients.

PATIENTS

Three patients presenting with non-specific symptoms including fatigue, shortness of breath, or chest discomfort were evaluated with cardiac tomography for cardiac structure and function.

RESULTS

Findings from the three patients were very similar: a truncated and spherical LV with abnormal diastolic and systolic function, invagination of fatty material into the myocardium of the defective LV apex, origin of a complex papillary network in the anteroapical LV, and an elongated right ventricle wrapping around the deficient apex.

CONCLUSIONS

Isolated LV apical hypoplasia is a unique, presumably congenital, cardiac anomaly that is an important condition to recognise.

Total Synthesis of (±)-Kalihinol C

The total synthesis of kalihinol C, a bis-isonitrile marine diterpenoid isolated from Acanthella sp., is reported. The decalin framework was established via an intramolecular Diels-Alder cycloaddition and subsequently functionalized through a series of substrate-controlled diastereoselective transformations to install the tertiary isonitrile, beta-hydroxy isonitrile, and pendant tetrahydrofuranyl ring.

[Imaging of coronary atherosclerotic plaque]

Selective coronary angiography allows the precise definition of highly stenotic coronary lesions and therefore remains the basis for catheter-based or surgical myocardial revascularization. However, the accumulation of atherosclerotic plaque in the coronary arterial wall begins much earlier than the development of luminal stenosis. In fact, most acute coronary syndromes are initiated by sudden disruption of atherosclerotic plaques that caused neither significant stenosis nor angina pectoris prior to the event. These early, but potentially vulnerable, lesions are therefore the topic of intensive research but their description with angiography alone is incomplete. Invasive, tomographic imaging modalities, in particular intravascular ultrasound, allow direct visualization of the atherosclerotic plaque and therefore supplement angiography. These techniques have advanced our understanding of coronary artery disease (CAD) progression and stability but are limited because of their invasive character. Current developments in particular of computed tomography already allow the non-invasive imaging of coronary arteries and may have an important role in the early identification of CAD and the prevention of its complications.

A retrospectively ECG-gated multislice spiral CT scan and reconstruction technique with suppression of heart pulsation artifacts for cardio-thoracic imaging with extended volume coverage

A method for cardio-thoracic multislice spiral CT imaging with ECG gating for suppression of heart pulsation artifacts is introduced. The proposed technique offers extended volume coverage compared with standard ECG-gated spiral scan and reconstruction approaches for cardiac applications: Thin-slice data of the entire thorax can be acquired within one breath-hold period using a four-slice CT system. The extended volume coverage is enabled by a modified approach for ECG-gated image reconstruction. For a CT system with 0.5-s gantry rotation time, images are reconstructed with 250-ms image temporal resolution. Instead of selecting scan data acquired in exactly the same phase of the cardiac cycle for each image as in standard ECG-gated reconstruction techniques, the patient's ECG signal is used to omit scan data acquired during the systolic phase of highest cardiac motion. With this approach cardiac pulsation artifacts in CT studies of the aorta, of paracardiac lung segments, and of coronary bypass grafts can be effectively reduced.

Mass effects of light ion swarms in ac electric fields

Transport properties of light ions in gases in ac electric fields are investigated by solving the time-dependent Boltzmann's equation. We focus on the way in which transport properties including diffusion are influenced by the ion-neutral mass ratio as well as the field frequency. Calculations of transient relaxation phenomena in step-function fields are performed as an aid to understanding the complex temporal profiles of ion transport coefficients in ac electric fields.

Clinical validation of an automated boundary tracking algorithm on cardiac MR images

The goal of this research was to develop an automated algorithm for tracking the borders of the left ventricle (LV) in a cine-MRI gradient-echo temporal data set. The algorithm was validated on four patient populations: healthy volunteers and patients with dilated cardiomyopathy (DCM), left ventricular hypertrophy (LVH), or left ventricular aneurysm (LVA). A full tomographic set (approximately 11 slices/case) of short-axis images through systole was obtained for each patient. Initial endocardial and epicardial contours for the end-diastolic (ED) and end-systolic (ES) frames were manually traced on the computer by an experienced radiologist. The ED tracings were used as the starting point for the algorithm. The borders were tracked through each phase of the temporal data set, until the ES frame was reached (approximately 7 phases/slice). Peak gradients along equally spaced chords calculated perpendicular to a centerline determined midway between the endocardial and epicardial borders were used for border detection. This approach was tested by comparing the LV epicardial and endocardial volumes calculated at ES to those based on the manual tracings. The results of the algorithm compared favorably with both the endocardial (r2 = 0.72 - 0.98) and epicardial (r2 = 0.96 - 0.99) volumes of the tracer.

Get the data

Numerous studies affirm the benefit of rapid defibrillation with AEDs. Most of the data have been acquired in emergency medical response systems with EMTs or firefighters providing defibrillation. Yet interest is growing in the provision of rapid defibrillation by other responders, including security officers, flight attendants and laypersons trained as targeted responders. This expansion is embraced in community early defibrillation. A multicenter, prospective, randomized, controlled trial was recently launched to define the benefit of community early defibrillation. Data from this trial will likely identify the most effective deployment of AEDs, frequency and appropriateness of use, time of defibrillation before EMS arrival, device maintenance issues and--most importantly--survival benefit when compared with control groups without AEDs.

Heart-to-heart talk. Roundtable discussion

This past August the American Heart Association (AHA) released a major revision of its recommendations for emergency cardiovascular care (ECC). The 2000 guidelines simplify CPR techniques for the layperson and strongly promote the use of community early defibrillation. What repercussions can we expect from these changes? We asked five experts to join a roundtable discussion of the BLS aspects of these new guidelines. Their conversation follows.

Progress toward the total synthesis of kalihinane diterpenoids

[see structure]. Studies toward the total synthesis of marine diterpenoids isolated from Acanthella sp., e.g., kalihinol A, are described. Efficient construction of the functionalized trans-decalin core (11) is achieved through intramolecular Diels-Alder cyclization followed by diastereoselective epoxidation and aziridination.

Viable myocardium in reperfused acute myocardial infarction: rest and stress first-pass mr imaging

Feasibility of identifying viable myocardium in rest and stress magnetic resonance imaging (MRI) was evaluated using 3 hr occlusion and 30 min reperfusion model of left anterior descending (LAD) coronary artery in 12 felines. At rest MRI, viable myocardium confirmed by 2,3,5-triphenyl tetrazolium chloride (TTC)-staining showed rapid signal intensity (SI) rise followed by gradual decline not significantly different from normal myocardium that the two hyperperfused regions were distinguishable only from the hypoperfused nonviable myocardium. At stress MRI, hyperemia induced perfusion change was most pronounced in normal myocardium with earlier and greater peak enhancement followed by brisk 'washout' phase while minimally augmented enhancement in viable myocardium was still in 'washin' phase. From these findings, it was concluded that viable myocardium is identified in rest and stress MRI as redistributing hypo- perfusion compared to persistent hyper-perfusion of the normal myocardium and the persistent hypo-perfusion of the nonviable myocardium.

Technologic advances and program initiatives in public access defibrillation using automated external defibrillators

Widespread provision of early defibrillation following cardiac arrest holds major promise for improved survival from ventricular fibrillation. The critical element in predicting a successful outcome is the rapidity with which defibrillation is achieved. A worldwide awareness of this potential and its advocacy by such organizations as the American Heart Association have been pivotal in the evolution of initiatives to make defibrillation more widely and more rapidly available. The feasibility of this initiative, known as public access defibrillation, is in large measure a direct consequence of major technologic advances in automated external defibrillators (AEDs). New low-energy waveforms with biphasic morphology have been shown to be more effective in terminating ventricular fibrillation and may do so with less myocardial injury. Placement of AEDs in a variety of nontraditional settings such as police cars, aircraft and airport terminals, and gambling casinos has been shown to yield an impressive number of survivors of cardiac arrest in ventricular fibrillation. Questions yet to be answered center on the appropriate disposition of AEDs in public access defibrillation settings, training and retraining issues, device maintenance, and collection of accurate data to document benefit and to identify areas of needed improvement or expansion of AED availability.

Efficient syntheses of novel C2'-alkylated (+/-)-K252a analogues

Recent efforts in our laboratories have resulted in a synthetic approach toward C2'-alkylated K252a analogues via extension of a K252a cyclofuranosylation strategy. The bis-indole-N-glycosidic coupling of 6-N-(3,4-dimethoxybenzyl)-staurosporinone (21) with a number of highly functionalized carbohydrates has given access to previously unattainable, biologically relevant analogues.

Patient outcomes following defibrillation with a low energy biphasic truncated exponential waveform in out-of-hospital cardiac arrest

PRIMARY OBJECTIVE

To determine the outcome of patients with out-of-hospital cardiac arrest and ventricular fibrillation as the presenting rhythm while using automated external defibrillators (AEDs) that delivered non-escalating, impedance-compensated low-energy (150 J) shocks.

MATERIALS AND METHODS

AEDs delivering low-energy biphasic truncated exponential (BTE) shocks were employed in an emergency medical services (EMS) system in which first-arriving personnel - police, firefighters or paramedics - delivered the initial shocks. Patients were classified according to their response to shocks: restoration of sustained spontaneous circulation (ROSC) without need for epinephrine and other advanced life support (ALS) interventions; and ALS, those requiring epinephrine in all instances. The primary end-point was neurologically-intact discharge survival. Secondary end-points were ROSC with shocks only and the call-to-shock time interval.

RESULTS

Of 42 patients with VF arrest treated with BTE shocks, 35 were bystander-witnessed. Of these 35, 14 (38%) regained a sustained ROSC on-scene with shocks only, needing no epinephrine for ROSC. All 14 survived to discharge home. Of the remaining 21 patients needing ALS intervention, only two (9.5%) survived to discharge. Overall, 16/35 patients (46%) survived to discharge home, an outcome comparable to our experience with patients treated with escalating high-energy monophasic waveform shocks.

CONCLUSIONS

Low-energy (150 J) non-escalating biphasic truncated exponential waveform shocks terminate VF in out-of-hospital cardiac arrest with high efficacy; patient outcome is comparable with that observed with escalating high-energy monophasic shocks. Low-energy shocks, in addition to high efficacy, may confer the advantage of less shock-induced myocardial dysfunction, though this will be difficult to define in the clinical circumstance of long-duration VF provoked by a pre-existing diseased myocardial substrate.

Exercise testing in special populations: athletes, women, and the elderly

Exercise testing in special populations such as athletes, women, and the elderly requires additional considerations from the clinician. Different protocols, as well as special accommodations, may be necessary for performing the test. Symptomatic athletes may have a number of cardiac conditions that lead to ischemic changes on the exercise test. Asymptomatic athletes often use serial exercise testing to evaluate the efficacy of training programs. For women and the elderly, assessment of risk factors and evaluation of symptoms are important considerations before performing the exercise test. Negative exercise test findings suggest a low risk for future cardiovascular events. Positive exercise test findings must be interpreted in light of the individual's pre-test probability. Assessment of the needs of these patients allows the clinician to tailor the exercise test to produce useful information.

Performing the exercise test

Exercise testing is useful in assessing physical fitness, determining functional capacity, diagnosing ischemic heart disease, defining the prognosis of ischemic heart disease, developing an exercise prescription, and guiding cardiac rehabilitation. This article outlines the current indications, contraindications, and special considerations for exercise testing. Specific protocols are discussed along with physician responsibilities for performing this procedure. A summary of current testing equipment is included.

Regional heterogeneity of function in nonischemic dilated cardiomyopathy

OBJECTIVE

To quantify regional three-dimensional (3D) motion and myocardial strain using magnetic resonance (MR) tissue tagging in patients with non-ischemic dilated cardiomyopathy (DCM).

METHODS

MR grid tagged images were obtained in multiple short- and long-axis planes in thirteen DCM patients. Regional 3D displacements and strains were calculated with the aid of a finite element model. Five of the patients were also imaged after LV volume reduction by partial left ventriculectomy (PLV), combined with mitral and tricuspid valve repair.

RESULTS

DCM patients showed consistent, marked regional heterogeneity. Systolic lengthening occurred in the septum in both circumferential (%S(C) -5+/-7%) and longitudinal (%S(L) -2+/-5%) shortening components (negative values indicating lengthening). In contrast, the lateral wall showed relatively normal systolic shortening (%S(C) 12+/-6% and %S(L) 6+/-5%, P<0.001 lateral vs. septal walls). A geometric estimate of regional stress was correlated with shortening on a regional basis, but could not account for the differences in shortening between regions. In the five patients imaged post-PLV, septal function recovered (%S(C) 9+/-5%,%S(L) 6+/-5%, P<0.02 pre vs. post) with normalization of wall stress, whereas lateral wall shortening was reduced (%S(C) 7+/-6%,%S(L) 3+/-3%, P<0.02 pre vs. post) around the site of surgical resection.

CONCLUSIONS

A consistent pattern of regional heterogeneity of myocardial strain was seen in all patients. Reduced function may be related to increased wall stress, since recovery of septal function is possible after PLV. However, simple geometric stress determinants are not sufficient to explain the functional heterogeneity observed.

[Measurement of left atrial and ventricular volumes in real-time 3D echocardiography. Validation by nuclear magnetic resonance]

The measurement of the left ventricular ejection fraction is important for the evaluation of cardiomyopathy and depends on the measurement of left ventricular volumes. There are no existing conventional echocardiographic means of measuring the true left atrial and ventricular volumes without mathematical approximations. The aim of this study was to test anew real time 3-dimensional echocardiographic system of calculating left atrial and ventricular volumes in 40 patients after in vitro validation. The volumes of the left atrium and ventricle acquired from real time 3-D echocardiography in the apical view, were calculated in 7 sections parallel to the surface of the probe and compared with atrial (10 patients) and ventricular (30 patients) volumes calculated by nuclear magnetic resonance with the simpson method and with volumes of water in balloons placed in a cistern. Linear regression analysis showed an excellent correlation between the real volume of water in the balloons and volumes given in real time 3-dimensional echocardiography (y = 0.94x + 5.5, r = 0.99, p < 0.001, D = -10 +/- 4.5 ml). A good correlation was observed between real time 3-dimensional echocardiography and nuclear magnetic resonance for the measurement of left atrial and ventricular volumes (y = 0.95x - 10, r = 0.91, p < 0.001, D = -14.8 +/- 19.5 ml and y = 0.87x + 10, r = 0.98, P < 0.001, D = -8.3 +/- 18.7 ml, respectively. The authors conclude that real time three-dimensional echocardiography allows accurate measurement of left heart volumes underlying the clinical potential of this new 3-D method.

Estimation of current leakage in left and right ventricular conductance volumetry using a dynamic finite element model

Leakage of electric current through cardiac structures surrounding the ventricle is a primary source of error during ventricular volume measurements using a conductance catheter. This error can be represented as a leakage volume, VL. VL is generally estimated by a saline-bolus method, and is assumed constant throughout the cardiac cycle. However, dynamic changes in ventricular volume and cardiac wall thickness could change VL. To estimate VL, a dynamic finite element model of the heart was developed based on MR images. Conductance measurements were simulated using a modeled conductance catheter, and true VL was calculated. VL varied from 22.7 ml (end-systole) to 26.4 ml (end-diastole) in the left ventricle and from 19.9 ml (end-systole) to 26.9 ml (end-diastole) in the right ventricle. The saline-bolus method underestimated VL in both the left (VL = 19.4 ml) and the right (VL = 4.1 ml) ventricular volume measurements. VL increased linearly with the ratio of blood to tissue resistivity, and changed minimally with catheter position. These results indicate that VL has to be estimated dynamically throughout the cardiac cycle to obtain accurate cardiac volume measurements. The results also show that the saline bolus method does not estimate current leakage accurately, especially in the right ventricular volume measurement.