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Biomedical subjects

E Foster

Publications and source records attributed to E Foster.

At least 91 records · Page 5Linked to original sources
PubMed1992

Regression of left ventricular hypertrophy in "previously untreated" hypertensive blacks after 6 months of blood pressure reduction with alpha- and beta-adrenergic blockade and thiazide therapy.

In 10 hypertensive black patients who were "previously untreated" (defined as no antihypertensive therapy for a minimum of 12 months prior to enrollment) and who had LVH (defined by an increase in both wall thickness and echocardiographically determined LV mass), we studied the effects of treatment with either labetalol, an alpha- and beta-adrenergic blocker (three patients), or labetalol plus hydrochlorothiazide (seven patients). After 6 months of effective antihypertensive therapy, there was a 12% decrease in LV mass for the entire group. However, the extent of LVH regression was highly variable among individual patients.

Adult↗
PubMed1992

Ventricular thrombi and thromboembolism in dilated cardiomyopathy: a prospective follow-up study.

To determine the prevalence and natural history of left ventricular thrombus in dilated cardiomyopathy, we prospectively performed two-dimensional echocardiograms in 25 patients with nonischemic dilated cardiomyopathy who were not receiving anticoagulation. Eighty-five echocardiograms were performed serially over a 9- to 30-month period (mean follow-up 21.5 months). A left ventricular thrombus was present on initial echocardiogram in 11 (44%) patients, became present during follow-up in an additional four, and disappeared in two. Thrombus was significantly more common in patients with fractional shortening of less than or equal to 10% (12 of 15) than in those with a fractional shortening 11% to 25% (3 of 10) (p less than 0.02). Five embolic events (four cerebral) occurred over the follow-up period, four of which were associated with a previously visualized left ventricular thrombus. Three of five thrombi that protruded into the left ventricular cavity subsequently embolized. We conclude that in nonanticoagulated patients with dilated cardiomyopathy left ventricular thrombus and thromboembolism are common. Echocardiography may be helpful in predicting which patients are at risk of thromboembolism.

Adult↗
PubMed1992

Pulmonary hypertension: pulmonary flow quantification and flow profile analysis with velocity-encoded cine MR imaging.

Velocity-encoded cine magnetic resonance (MR) imaging provides two-dimensional velocity maps of a cross-sectional area of a vessel. Pulmonary flow and flow patterns in the main pulmonary artery were analyzed with velocity-encoded cine MR imaging and Doppler echocardiography in 10 patients with pulmonary hypertension (PH), one patient with a dilated main pulmonary artery, and 10 healthy subjects, and these findings were compared. Peak systolic velocity measured with velocity-encoded cine MR imaging was similar to that measured with Doppler echocardiography in healthy subjects and in patients with PH. Velocity-encoded cine MR imaging demonstrated substantial differences in velocity across the vascular lumen in PH. The flow pattern in healthy subjects was different than that in patients with PH; the latter had lower peak systolic velocity and greater retrograde flow after middle to late systole. The retrograde flow observed in patients with PH reflected hemodynamic events, since it was inversely proportional to pulmonary flow volume and directly proportional to pulmonary resistance and cross-sectional area of the vessel. Velocity-encoded cine MR imaging demonstrates an inhomogeneous flow profile in PH and may serve as a noninvasive method to estimate pulmonary vascular resistance.

Adult↗
PubMed1992

Two-dimensional echocardiographic phase analysis. Its potential for noninvasive localization of accessory pathways in patients with Wolff-Parkinson-White syndrome.

BACKGROUND: In patients with the preexcitation syndrome who are undergoing transcatheter or surgical ablation, accurate localization of accessory pathways is critical. Because preexcitation is known to alter ventricular activation sequence and result in focal areas with presystolic contraction, we investigated whether phase analysis applied to two-dimensional echocardiographic cine loops objectively identifies these focal areas and can be used to localize ventricular insertion sites of accessory pathways. METHODS AND RESULTS: We prospectively obtained phase images in 17 patients (11 males; age range, 11-35 years) during minimal preexcitation in normal sinus rhythm and during maximal preexcitation induced by right atrial pacing. A group of 11 normal subjects (six men; age range, 26-37 years) served as controls. Pathway locations predicted from phase imaging were compared with those predicted from routine 12-lead ECGs, from visual inspection of cine loop images, and from catheter-mounted electrode endocardial mapping. Cross-sectional views in a digital cine loop format were mathematically transformed using a first harmonic Fourier algorithm to obtain the corresponding phase images. Phase angle histograms were derived in eight wall segments. Mean and earliest phase angles were derived by computer analysis to quantitate contraction sequence. We found that during right atrial pacing, phase angles in focal areas markedly deviated from normal--mean phase angles from 33 degrees to 164 degrees, and earliest phase angles from 50 degrees to 180 degrees. Accessory pathways could be precisely localized in 53% of the patients by 12-lead ECG, in 59% by visual inspection of cine loop images, in 82% by phase imaging, and in 94% by a combination of the three methods. CONCLUSIONS: Our results suggest that phase imaging, especially when used in combination with cine loop and 12-lead ECG, can be used to localize ventricular insertion sites of accessory pathways and may be clinically useful as a noninvasive adjunct to endocardial mapping in patients with Wolff-Parkinson-White syndrome.

Adult↗
PubMed1991

Long-term follow-up of patients operated on for recurrent carotid stenosis.

We reviewed our experience with 29 operations for recurrent carotid stenosis in 27 patients who underwent both their primary carotid endarterectomy and their reoperations at our institution. These 27 patients represent 4% of the 667 patients who underwent primary carotid endarterectomies at our institution and who are included in our carotid follow-up registry. Reoperation was prompted by recurrent symptoms in 19/29 (65.5%) cases. Comparison of long-term stroke prevention in those patients who did (84% at 5 years, 78.6% at 10 years) and did not (90.3% at 5 years, 83.6% at 10 years) develop recurrent stenosis requiring reoperation revealed no statistically significant difference (p = 0.48) when measured from the time of primary operation. The perioperative stroke and death rates for reoperation (3.4% and 0%) were acceptable. We conclude that with our acceptably low perioperative stroke morbidity (3.4%), surgery for recurrent carotid stenosis in symptomatic patients or in asymptomatic patients with high-grade (greater than or equal to 75%) stenosis maintains the durable stroke prevention offered by primary carotid endarterectomy.

Carotid Arteries↗
PubMed1991

Antibacterial activity and inhibition of protein synthesis in Escherichia coli by antisense DNA analogs.

Protein synthesis, which takes place within ribosomes, is essential for the survival of any living organism. Ribosomes are composed of both proteins and RNA. Specific interaction between the 3' end CCUCC sequence of prokaryotic 16S rRNA and a partially complementary sequence preceding the initiating codon of mRNA is believed to be a prerequisite for initiation of protein synthesis. Here we report the use of short (three to six nucleotides) synthetic DNA analogs complementary to this sequence to block protein synthesis in vitro and in vivo in Escherichia coli. In the DNA analogs the normal phosphodiester bond in the antisense DNA was replaced by methylcarbamate internucleoside linkages to enhance transport across plasma membranes. Of the analogs tested, those with the sequence AGG and GGA inhibit protein synthesis and colony formation by E. coli strains lacking an outer cell wall. Polyethylene glycol 1000 (PEG 1000) was attached to the 5' end of some of the test methylcarbamate DNAs to enhance solubility. Analogs of AGG and GGAG with PEG 1000 attached inhibited colony formation in normal E. coli. These analogs may be useful food additives to control bacterial spoilage and biomedically as antibiotics.

3T3 Cells↗
PubMed1991

Pacemaker syndrome in a patient with DDD pacemaker for long QT syndrome.

A patient with long QT syndrome was treated with beta blockers and had a permanent DDD pacemaker implanted. The lower rate was set to 85 beats/min because this provided the best shortening of QT interval at the lowest paced heart rate. The atrioventricular (AV) delay was programmed to 250 msec to allow native AV conduction. Patient returned complaining of symptoms suggestive of pacemaker syndrome. ECG during one of these episodes showed AV sequential pacing. Doppler echocardiography of hepatic vein flow suggested atrial contraction against a closed tricuspid valve. Endocardial electrogram telemetry demonstrated ventriculoatrial (VA) conduction with the retrograde atrial electrogram falling within the atrial refractory period and thus was not sensed. The following atrial stimulus did not capture because of the atrial refractoriness. Ventricular pacing proceeded after the programmed AV delay. Reprogramming the AV delay to 200 msec restored AV synchrony by allowing the atrial stimulus to capture by placing it outside of the refractory period of the atrium. No further symptoms reported during six months of follow-up.

Atenolol↗
PubMed1991

Right and left lung perfusion: in vitro and in vivo validation with oblique-angle, velocity-encoded cine MR imaging.

Quantification of pulmonary flow is clinically important in the evaluation of both congenital and acquired heart disease. Velocity-encoded cine magnetic resonance (MR) is a promising technique for measuring velocity and volume of blood flow. The authors report validation of the accuracy of velocity-encoded cine MR for measurement of oblique-angle flow in vitro, with use of a constant-flow phantom, and in vivo, with nine healthy volunteers in whom velocities were measured separately in the main, right, and left pulmonary arteries. Findings at MR were compared with findings at Doppler echocardiography. Velocity measurements in a flow phantom with cine MR correlated well with direct measurements at Doppler echocardiography. Velocity-encoded cine MR enabled accurate and reproducible measurement of absolute blood flow in healthy subjects. Oblique-gradient flow encoding (ie, flow-encoding direction coinciding with the true direction of flow) was the method of choice for velocity measurements in the right and left pulmonary arteries.

Adult↗
PubMed1991

Right and left ventricular stroke volume measurements with velocity-encoded cine MR imaging: in vitro and in vivo validation.

The accuracy of measurements of flow velocity determined by using cine MR phase velocity mapping--velocity-encoded cine (VEC) MR--was assessed by comparing VEC MR data with independent measurements in a flow phantom and in human subjects. Constant flow velocities generated in a phantom (range, 20-408 cm/sec) were determined correctly by VEC MR (r = .997, standard error of the estimate [SEE] = 7.9 cm/sec). Peak systolic velocities in the main pulmonary artery determined by VEC MR correlated well with the measurements obtained by using continuous-wave Doppler echocardiography (r = .91). Stroke volumes measured at the aorta by VEC MR and continuous-wave Doppler imaging also correlated well with each other (r = .80). VEC MR measurements of aortic and pulmonary flow provided left and right ventricular stroke volumes that correlated well with left ventricular stroke volumes determined by short-axis cine MR images (r = .98, SEE = 3.7 ml, and r = .95, SEE = 4.8 ml, respectively). Intra- and interobserver variabilities were small for both left and right ventricular stroke volumes as measured with VEC MR. These results indicate that VEC MR accurately and reproducibly measures aortic and pulmonary flow velocities and volumes in the physiologic range of humans, and can be used to measure right and left ventricular stroke volumes under normal flow conditions.

Adult↗
PubMed1988

Pericardial pseudotumor. Echocardiographic observation of juxtacardiac pulmonary collapse.

Despite its value in the diagnosis of pericardial disease, two-dimensional echocardiography also is known to produce confounding results. Ten patients had juxtacardiac masses simulating pericardial tumor implants on echocardiographic examination ("pericardial pseudotumor") caused by juxtacardiac pulmonary atelectasis or lobar collapse. The atelectatic nature of these masses was based on echocardiographic delineation of pericardial and pleural anatomy, combined with ancillary radiographic and CT studies. Drainage of pleural fluid also led to disappearance of the masses on echocardiographic examination, suggesting that the masses were an ultrasonic manifestation of pulmonary atelectasis resulting from surrounding compressive effusive fluid. Finally, clinical follow-up failed to show development of malignant disease in any patient. The possibility of pericardial pseudotumor should be considered when ultrasound studies show juxtacardiac masses within large collections of pleural fluid, especially in the clinical absence of malignant disease.

Adult↗
PubMed1988

Medical and economic consequences of a blinded oral anticoagulant brand change at a municipal hospital.

In 1980, the Boston City Hospital pharmacy made a bulk purchase of a brand of warfarin sodium that was different from the brand previously stocked. The physician and nurse in charge of the anticoagulation clinic and responsible for regulating patient dosage of warfarin were not aware of the change in warfarin brand. During the period of brand substitution, we observed an increase in the number of patients whose anticoagulation was poorly controlled. There was a concomitant increase in the number of clinic visits and an increased frequency of prothrombin time testing to regulate the dosage in such patients. We performed a retrospective analysis of the medical and economic consequences of the change in brand of warfarin. Our results show that a significant increase in morbidity and overall health care costs resulted from this attempt to economize by changing brands of medication in our municipal hospital setting.

Blood Coagulation Disorders↗
PubMed1987

Rodent fibroblast tumours expressing human myc and ras genes: growth, metastasis and endogenous oncogene expression.

The effects of expression of human c-myc and both mutated (T24) and normal forms of human Ha-ras-1 were studied in an aneuploid rat fibroblast line (208F). Mutated T24 Ha-ras was also studied in a near-diploid cell derived from early passage Chinese hamster lung fibroblasts (CHL). In contrast to the parental fibroblasts, cells expressing any of the human oncogenes engendered rapidly growing tumours in immune-suppressed animals. Blood- and lymph-borne metastases were observed from both ras- and myc-expressing cells. In general ras-expressing cells were more aggressive than those expressing myc. In the 208F background, expression of c-myc was associated with an incidence of mitosis similar to that in tumours expressing T24 Ha-ras, but incidence of single cell death by apoptosis was higher. Quantitatively, expression of human oncogene mRNA was constant during growth in vivo, and similar to that sometimes observed in human neoplasms. Of 9 endogenous proto-oncogenes, 7 showed no change in expression from the parental fibroblasts, but c-abl and c-fos were strongly expressed in all cells expressing human ras or myc. Thus these tumorigenic cells, although transfected with single human oncogenes, all expressed oncogenes with both nuclear- and membrane-associated products.

Animals↗
PubMed1985

The cytogenetics of human B lymphoid malignancy: studies in Burkitt's lymphoma and Epstein-Barr virus-transformed lymphoblastoid cell lines.

Cells from Burkitt's lymphoma (BL) and from the majority of human B-cell neoplasms show karyotypic changes that characteristically involve chromosomal breakage and recombination in addition to some chromosome gains. These aberrations increase as the tumours progress in vivo, and a similar tendency is seen in BL-derived lymphoid lines in vitro. Epstein-Barr virus (EBV)-transformed lymphoblastoid lines of non-malignant origin also develop karyotypic abnormalities on prolonged culture, but these are predominantly nonrandom gains of whole chromosomes (i.e., non-disjunction events). They have never been observed to acquire the 8;14 translocation, which is an almost constant feature of BL. Nevertheless, there is some concordance between the pattern of chromosome gains found in long-term cultured lymphoblastoid lines and that seen in direct preparations from B-cell neoplasms. Many of the lymphoblastoid lines that have become aneuploid are tumorigenic in immunosuppressed mice, indicating that EBV-transformed human B cells can acquire a malignant phenotype in the absence of specific chromosomal translocations. It is suggested that the predominance of chromosomal breakage and recombination events in the karyotypic evolution of BL and other lymphoid neoplasms comes about because chromosomal instability (which varies within a population) is a major risk factor for lymphoid malignancy, interacting with other risk factors, including impaired T-cell function and EBV to determine the clinical and epidemiological patterns of BI and related neoplasms.

B-Lymphocytes↗
PubMed1984

Failure of nifedipine and reperfusion to reduce infarct size relative to region at risk as measured by NADH fluorophotography.

In this report we describe a new technique for the measurement of region at risk after coronary artery ligation in the rabbit by NADH fluorophotography. We also describe the application of this technique to a study of nifedipine combined with reperfusion in experimental myocardial infarction. In 16 untreated rabbits the epicardial surface area of NADH fluorescence immediately after coronary ligation correlated with infarct size at 24 hr after coronary occlusion, as measured by nitro blue tetrazolium staining (r = .84, p less than .001). In 24 rabbits we studied the effect of nifedipine administered immediately after coronary ligation and combined with reperfusion at 1 hr after occlusion. Nifedipine had no significant effect on region at risk or infarct size.

Animals↗
PubMed1983

Right heart reconstruction following repair of tetralogy of fallot.

Ten patients in whom tetralogy of Fallot had been repaired underwent late reconstruction of the outflow tract of the right ventricle because of poor hemodynamic results. The major hemodynamic problems that necessitated right ventricular (RV) outflow tract reconstruction were severe pulmonary insufficiency in 9 patients and pulmonary stenosis in 1. Impaired RV contractility and RV aneurysm were the most important factors prompting valve replacement for severe pulmonary insufficiency. Seven patients received a Hancock prosthesis and 3, an aortic homograft. Among the 7 patients who underwent postoperative cardiac catheterization, the surgical results were hemodynamically excellent in 2, good in 3, and unsatisfactory in 2. The management of pulmonary insufficiency in such patients is discussed.

Adolescent↗
PubMed1982

Left ventricular function and compliance in pulmonary atresia with intact ventricular septum.

Left ventricular systolic function and compliance were assessed in 15 cases of pulmonary atresia with intact ventricular septum. The left ventricular ejection fraction measured from cineangiography was used for the evaluation of the systolic function. The end-diastolic pressure (EDP), left ventricular compliance index at end-diastole (dv/dp), and left ventricular stiffness constant K were used as compliance indices. The mean left ventricular ejection fraction was slightly diminished. The right ventricular end diastolic pressures (RVEDPs) correlated significantly (r = 0.90) with the left ventricular end diastolic pressure (LVEDP). On the basis of left ventricular compliance, two distinctive groups of patients could be identified: Group I consisted of Patients 1 to 7, all with impaired left ventricular compliance. A shunt operation was the basic palliation in this group. None of these patients survived infancy. Group II consisted of Patients 8 to 15, all with normal left ventricular compliance. Pulmonary valvotomy as well as aortopulmonary shunts were the basic palliative procedures in this group. Six of eight patients in this group are long-term survivors. No difference was found in right ventricular size, tricuspid valve size, presence of tricuspid insufficiency, presence of a patent ductus arteriosus, postoperative oxygen saturations, and atrial pressure gradients between the two groups. Evaluation of the left ventricular compliance in patients with pulmonary atresia and intact ventricular septum might be of significant prognostic valve for their early survival.

Blood Pressure↗