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Biomedical subjects

S Stern

Publications and source records attributed to S Stern.

At least 109 records · Page 6Linked to original sources
PubMed1991

Effect of exercise supplementation on dipyridamole thallium-201 image quality.

To determine the effect of different types of exercise supplementation on dipyridamole thallium image quality, 78 patients were prospectively randomized to one of three protocols: dipyridamole infusion alone, dipyridamole supplemented with isometric handgrip, and dipyridamole with low-level treadmill exercise. Heart-to-lung, heart-to-liver, and heart-to-adjacent infradiaphragmatic activity ratios were generated from anterior images acquired immediately following the test. Additionally, heart-to-total infradiaphragmatic activity was graded semiquantitatively. Results showed a significantly higher ratio of heart to subdiaphragmatic activity in the treadmill group as compared with dipyridamole alone (p less than 0.001) and dipyridamole supplemented with isometric handgrip exercise (p less than 0.001). No significant difference was observed between patients receiving the dipyridamole infusion, and dipyridamole supplemented with isometric handgrip exercise. We conclude that low-level treadmill exercise supplementation of dipyridamole infusion is an effective means of improving image quality. Supplementation with isometric handgrip does not improve image quality over dipyridamole alone.

Adult↗
PubMed1990

Changes in myocardial ischemic threshold during daily activities.

This study assesses the variations in myocardial ischemic threshold (heart rate at the onset of ischemia) during daily activities in patients with ischemic episodes on Holter monitoring. Eighty patients with known coronary artery disease, positive treadmill stress test results and greater than or equal to 2 ischemic episodes during a 24-hour period of Holter monitoring were studied. The lowest and the highest ischemic thresholds were determined for each patient. The mean lowest ischemic threshold was 85 beats/min, and the mean highest ischemic threshold was 109 beats/min. The highest ischemic threshold was identical to ischemic threshold values noted during exercise. Of the 895 ischemic episodes, 654 (74%) were preceded by a moderate (greater than 10%) increase in heart rate. The variability of ischemic threshold (difference in percentage between the highest and lowest ischemic thresholds) increased with the number of ischemic episodes (range 2 to 60%). However, in different patients with a similar number of ischemic episodes, different variability was observed. These differences in ischemic thresholds are probably indirect indicators of the vasomotor activity of the coronary arteries in different patients.

Activities of Daily Living↗
PubMed1990

Natural history of left ventricular thrombi: their appearance and resolution in the posthospitalization period of acute myocardial infarction.

A series of 198 consecutive patients with acute myocardial infarction were prospectively studied before hospital discharge and during 24.0 +/- 8.6 months of follow-up. A predischarge thrombus was found in 38 (31%) of 124 patients with anterior infarction but in none of 74 patients with inferior infarction (p less than 0.001). Early thrombolytic therapy in 34 patients did not decrease the rate of thrombus occurrence. Acute anterior infarction, ejection fraction less than or equal to 35% and apical dyskinesia or aneurysm (but not akinesia) were significantly related to the appearance of thrombus during hospitalization by stepwise logistic regression analysis. Echocardiographic follow-up of 159 patients for at least 6 months (mean 26.6 +/- 8.4) revealed that thrombus disappeared in 14 (48%) of 29. Disappearance of thrombus was related to predischarge apical akinesia (but not dyskinesia) and to warfarin therapy during the follow-up period. A new thrombus first appeared after hospital discharge in 13 of 130 patients, and in 7 of the 13 it resolved during further follow-up. Thus, 30% (13 of 42) of thrombi in these patients appeared after discharge from the hospital. Three factors were related to occurrence of new thrombi during the follow-up period: deterioration in left ventricular ejection fraction, predischarge ejection fraction less than or equal to 35% and ventricular aneurysm or dyskinesia. Systemic embolism occurred in six patients, all with a predischarge thrombus (p less than 0.001). Mobility of the thrombus was the only variable significantly related to subsequent embolic events (p = 0.001) by logistic regression analysis. Thus, the predischarge echocardiogram identifies patients with thrombus and those at highest risk of embolic events. It can indicate patients who are likely to have thrombus resolution and those at risk of developing a new thrombus after hospital discharge. Follow-up echocardiograms may help in guiding the length of long-term anticoagulant therapy. Four additional patients with a predischarge apical mobile thrombus (not part of the consecutive series) received thrombolytic therapy. In two of the four, lysis of thrombus was achieved without complications, but systemic embolism occurred in the other two, and proved fatal in one.

Echocardiography↗
PubMed1990

Ventricular ectopic activity during myocardial ischemic episodes in ambulatory patients.

The association between ventricular ectopic activity (VEA) and ischemic episodes during everyday activities was investigated in ambulatory patients with stable angina pectoris. Seventy-five consecutive patients with proven coronary artery disease, ischemic episodes on Holter monitoring and positive treadmill tests, but without known ventricular arrhythmias, were prospectively studied. In these 75 patients, a total of 719 ischemic episodes were recorded during 127 twenty-four-hour monitoring periods. Forty-three patients had either no or only very low baseline VEA (less than 14 ventricular premature complexes [VPCs]/24 hours); none of these patients had increased VEA during any ischemic episode. However, among 32 patients who had greater than or equal to 14 VPCs/24 hours (average 243 VPCs/24 hours), increased VEA during ischemic episodes was observed in 11 (31%). These 11 patients had a total of 174 ischemic episodes and the increased VEA appeared in 47 (27%) of the episodes. During 40 of the ischemic episodes the number of single VPCs increased significantly compared to the baseline background VEA: during 4 episodes trigeminy appeared and during another 3 bigeminy was observed. More complex VEA was not observed. Among the 11 patients with increased VEA, only 4 developed VPCs during treadmill testing. No correlation was found between the severity of the ischemic episodes (degree of ST depression and duration of ischemia) and the increased VEA. In 83% of these episodes the increased VEA appeared during the last (possibly reperfusion) phase. No correlation was found between the appearance of ventricular arrhythmias during ischemic episodes and the presence or absence of chest pain at the same time.(ABSTRACT TRUNCATED AT 250 WORDS)

Activities of Daily Living↗
PubMed1990

The effect of disopyramide on uterine contractions during pregnancy.

To evaluate the effect of disopyramide on uterine contractions during pregnancy, the drug was given for 48 hours to 10 women with indications for labor induction. Placebo was given to 10 other women with the same indications for induction. During the study period, regular uterine contractions occurred in 10 women in the study group, as compared with none in the control group (p less than 0.0001). Eight women in the study group were delivered of infants within 48 hours, as compared with none in the control group (p less than 0.0001). The mean time until the appearance of regular uterine contractions in the study group (4.15 +/- 1.76 hours) was significantly shorter (p less than 0.001) than that in the control group (56.13 +/- 5.28 hours). Patients who were not delivered of infants within 48 hours received other medications (prostaglandin E2, oxytocin). The mean maternal blood level of disopyramide at the time of appearance of uterine contractions was 1.52 +/- 0.9 mg/ml. The mean maternal level at delivery was 0.93 +/- 0.43 mg/ml and the cord blood level at the time of delivery was 0.33 mg/ml (cord blood/maternal level ratio = 0.36, r = 0.73, p less than 0.05). These results indicate that disopyramide should not be used in pregnancy for antiarrhythmic purposes because it may induce uterine contractions and delivery.

Adult↗
PubMed1990

Malignant melanoma associated with melanocytoma of the optic disc.

A 61-year-old white man underwent enucleation because of progressive growth of a pigmented epipapillary tumor that was diagnosed 9 years earlier as an optic nerve and juxtapapillary melanocytoma. Histopathologic studies showed the tumor was a malignant melanoma of the optic disc and juxtapapillary retina and choroid. Foci of typical melanocytoma cells were within the tumor. The tumor produced segmental atrophy of the optic nerve. This is a rare example of a malignant melanoma developing in conjunction with a lesion that possessed typical clinical and histopathologic features of a melanocytoma of the optic disc.

Cell Transformation, Neoplastic↗
PubMed1990

HLA extended haplotypes in childhood and adult onset HLA-DR4-associated arthropathies.

Alpha HLA-DR4 extended haplotypes have been established by family studies in children and adults with chronic arthritis, the children having polyarticular juvenile rheumatoid arthritis and the adults rheumatoid arthritis. These diseases are probably the same disorder presenting at different ages. The results demonstrate age-related differences in the frequency of HLA-DR4 extended haplotypes between the two groups of patients. The childhood onset was associated with the presence of the HLA-B44, SC30, DR4 extended haplotype, whereas the adult form was more strongly associated with the HLA-Bw62, SC33, DR4 haplotype. These results suggest that differences in the age at onset are influenced by the MHC in addition to the presence of the HLA DR4 gene itself.

Adult↗
PubMed1990

Mildly dilated congestive cardiomyopathy. Use of prospective diagnostic criteria and description of the clinical course without heart transplantation.

Prognosis in classically described dilated congestive cardiomyopathy has been reported to be related to ventricular size. Mildly dilated congestive cardiomyopathy (MDCM) has been defined as end-stage heart failure of unknown etiology (New York Heart Association class IV, left ventricular ejection fraction less than 30%), occurring with neither typical hemodynamic signs of restrictive myopathy nor significant ventricular dilatation (less than 15% above normal range). The present study includes follow-up in 12 nontransplant patients. In the first 4 months after diagnosis, two patients improved and are living, and two showed cardiac dilation and clinical deterioration and died. Six of the remaining eight with persistent MDCM died (four with intractable heart failure and two, sudden deaths) without change in ventricular size before death, despite medical therapy over 20 +/- 8 months. Eight comparable transplanted patients with persistent MDCM demonstrated improved total survival by life table analysis (p less than 0.05). A family history of congestive cardiomyopathy was found in nine of 16 patients (56%) with persistent MDCM. Nontransplant patients were older (p less than 0.02), but other findings were similar in the two groups. Endomyocardial biopsies available in 14 of 16 cases showed little or no myofibrillar loss in spite of severe hemodynamic impairment. The degree of myofibrillar loss did not correlate with hemodynamic parameters but showed good correlation with left ventricular size, that is, five of six patients with no myofibrillar loss had normal ventricular size, whereas all eight patients with mild myofibrillar loss had mild cardiomegaly (p less than 0.002). Our current experience suggests a somewhat variable but negative prognosis after prospective diagnosis of MDCM, with poor survival in patients with persistence of the original diagnostic features during follow-up. Preservation of heart size in MDCM is probably related to lack of significant myofibrillar loss. Thus, irrespective of heart size or myofibrillar preservation on biopsy, heart transplantation should be strongly considered in MDCM if signs of severe cardiac dysfunction persist despite therapy.

Adult↗
PubMed1989

Natural course of atrial septal aneurysm in children and the potential for spontaneous closure of associated septal defect.

Atrial septum aneurysm (ASA), usually involving the region of the fossa ovalis, has rarely been described in children. In this study, the incidence and natural course of this anomaly were prospectively evaluated in 3,500 children referred for echocardiographic examination. ASA was found in 35 patients, 19 female and 16 male (1.0%). Patients were 6 years of age or younger at the time of diagnosis and 18 were neonates. None of the 750 children with normal echocardiograms had ASA. The most common associated lesion was atrial septal defect (ASD), which occurred in 24 of the 35 patients (69%). Other associated cardiac lesions were ventricular septal defect in 10, pulmonary stenosis in 5, patient ductus arteriosus in 4 and coarctation or interruption of the aorta with subaortic membrane in 2. No clinical complications were associated with ASA. Six patients with complex heart disease died. When associated with ASD, the direction of the ASA motion and that of the shunt found by Doppler echocardiography were similar. Fourteen patients with ASD were followed for 0.5 to 4 years. In 8 the ASD closed and in 6 the ASA disappeared. In 6 patients the ASD and ASA persisted until the end of the follow-up (p less than 0.01). Thus, the incidence of ASA in children in this series was higher than previously presumed and usually was associated with other cardiac anomalies, mainly ASD. In children, ASA tends to disappear with age and may have a role in spontaneous closure of associated ASD.

Abnormalities, Multiple↗
PubMed1989

The Oct-1 homoeodomain directs formation of a multiprotein-DNA complex with the HSV transactivator VP16.

The herpes simplex virus transactivator VP16 participates in the formation of a multiprotein-DNA complex with the ubiquitous octamer-motif-binding factor Oct-1. Complex formation is dependent on specific amino acids in the Oct-1 homoeodomain which are in positions analogous to positive control mutations in helix 2 of the lambda phage repressor helix-turn-helix motif, indicating that this structure is an ancient target for protein-protein interactions mediating transcriptional control.

Amino Acid Sequence↗
PubMed1989

RNA-protein interactions in 30S ribosomal subunits: folding and function of 16S rRNA.

Chemical probing methods have been used to "footprint" 16S ribosomal RNA (rRNA) at each step during the in vitro assembly of twenty 30S subunit ribosomal proteins. These experiments yield information about the location of each protein relative to the structure of 16S rRNA and provide the basis for derivation of a detailed model for the three-dimensional folding of 16S rRNA. Several lines of evidence suggest that protein-dependent conformational changes in 16S rRNA play an important part in the cooperativity of ribosome assembly and in fine-tuning of the conformation and dynamics of 16S rRNA in the 30S subunit.

Base Sequence↗
PubMed1989

Comparison of mortality and myocardial infarction rates in stable angina pectoris with and without ischemic episodes during daily activities.

The prognostic significance of ischemic changes during daily activities was assessed in 56 patients with stable angina pectoris. All patients had positive results on the treadmill stress test and angiographic evidence of significant coronary artery disease. Forty-three (77%) had ischemic episodes on Holter monitoring during everyday activities. During the follow-up period (mean 2 years), there were 6 deaths and 6 myocardial infarctions among the 43 patients with ischemic episodes, compared with none among the 13 patients without such changes (p less than 0.03). All 14 patients referred for coronary bypass surgery belonged to the group with ischemic episodes (p less than 0.02). The extent of coronary disease, the treadmill test parameters, and the duration and frequency of ischemia during daily activities were identical in the patients with and without subsequent cardiac events. Patients with only symptomatic ischemic episodes or those with both silent and symptomatic episodes had a frequency of cardiac events similar to that of patients with only silent episodes. Thus, it seems that patients with stable angina pectoris and ischemic episodes during daily activities have a worse prognosis than patients free from such episodes.

Activities of Daily Living↗
PubMed1989

[Ischemic episodes during daily activities and progression of ischemic heart disease].

In patients with coronary artery disease, ischemic episodes, the majority of which are silent, can be detected electrocardiographically during daily activities by Holter ambulatory monitoring. We here summarize our experience with the prognostic significance of such ischemic episodes, silent or symptomatic. In 356 patients the progression of ischemic heart disease was evaluated by clinical follow-up averaging 2 years. Death, infarction, unstable angina, referral for coronary bypass surgery or balloon angioplasty were significantly more common in those with ischemic episodes on Holter monitoring than in those without. Thus, in addition to the results of the treadmill exercise test and determinations of left ventricular ejection fraction, the appearance of ischemic episodes is also of prognostic significance.

Activities of Daily Living↗