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Biomedical subjects

H C Smith

Publications and source records attributed to H C Smith.

At least 109 records · Page 6Linked to original sources
PubMed1986

Indications for coronary angiography: changes in laboratory practice over a decade.

The indications for coronary angiography have been changing in recent years. To characterize these changes, we examined the records of Mayo Clinic patients referred for 400 coronary angiography procedures in 1973 and 1983 (200 procedures in each study year). We retrospectively assigned patients to one of seven general indication categories to determine the changes in indications used for referral during that decade. We observed a relative increase in angiographic studies related to acute myocardial infarction and percutaneous transluminal coronary angioplasty and a relative decrease in studies for nonspecific chest pain. No change was noted in the relative frequencies of indications related to assessment of anginal chest pain, possible coronary artery disease but no chest pain, assessment after coronary artery bypass grafting procedures, major ventricular arrhythmias, and investigational protocols. We believe that the differences noted primarily reflect the accumulation of new knowledge and new technologic capabilities.

Adolescent↗
PubMed1986

Prognostic significance of regional wall motion abnormality in patients with prior myocardial infarction: a prospective correlative study of two-dimensional echocardiography and angiography.

In this pilot study of 50 consecutive patients with prior myocardial infarction, the results of two-dimensional echocardiographic and angiographic analysis of wall motion abnormalities were correlated, and their prognostic significance was determined. There was overall good agreement (88%) between the two methods. In general, the greater the left ventricular dysfunction, the worse was the prognosis. The 3-year survival was significantly reduced for patients with a left ventricular wall motion score index of 2.5 or greater (P = 0.024). These findings were essentially similar to the reduced survival rate associated with decreased angiographic ejection fractions (less than 40%). This study suggests that two-dimensional echocardiography, a noninvasive and relatively inexpensive technique, can provide prognostic information in patients with prior myocardial infarction.

Actuarial Analysis↗
PubMed1986

Coronary artery venous bypass graft aneurysm with symptomatic coronary artery emboli.

A 53 year old man, asymptomatic for 9 years after aorto-right coronary artery venous bypass surgery, developed two prolonged episodes of myocardial ischemia during a 7 month interval. Diagnostic exercise tests subsequent to each episode were normal. Coronary angiography demonstrated marked dilation with filling defects of the venous bypass graft. A large thrombus-filled venous bypass graft aneurysm was excised at surgery. Spontaneous coronary artery embolization related to a venous bypass graft aneurysm has not been described previously, but may become more frequent as survival and follow-up after coronary bypass surgery lengthen.

Aneurysm↗
PubMed1986

Coronary artery thrombus as a risk factor for acute vessel occlusion during percutaneous transluminal coronary angioplasty: improving results.

Early experience with percutaneous transluminal coronary angioplasty (from October 1979 to March 1983 inclusive) showed that pre-existing coronary artery thrombus was associated with a significant increase in the incidence of acute coronary occlusion during angioplasty. Acute occlusion occurred in 11 (73%) of 15 patients with pre-existing thrombus compared with 18 (8%) of 223 patients without thrombus. The effect of improved technology (steerable guiding systems) and altered dilatation strategy (full intravenous heparinisation for 24 hours after the procedure and more intensive use of antiplatelet medications) was studied by review of angiograms from 297 consecutive patients without evidence of acute myocardial infarction who underwent angioplasty from April 1983 to March 1985 inclusive. Coronary artery thrombus was present in 34 (11%) patients, eight (24%) of whom had complete occlusion during or immediately after the procedure compared with 34 (13%) of 263 patients without thrombus. Patients with pre-existing coronary artery thrombus continue to be at greater risk of complete occlusion than patients without thrombus, but this risk has declined significantly since the modification of the angioplasty procedure.

Acute Disease↗
PubMed1986

Diagnostic value of thyrotropin concentrations in serum as measured by a sensitive immunoradiometric assay.

A new, highly sensitive immunoradiometric thyrotropin (TSH) assay involving solid-phase-coupled monoclonal antibodies (Boots-Celltech Sucrosep IRMA-TSH) has been evaluated in a wide variety of patients with thyroidal and nonthyroidal illnesses and the results compared with those obtained by conventional diagnostic TSH RIAs. The sensitivity of the present assay ranged from 0.036 to 0.1 milli-int. unit/L (mean 0.056). TSH, measurable in serum of each of 128 euthyroid patients, ranged from 0.1 to 6.3 milli-int. units/L (mean 1.7, SD 1.1). Similar concentrations were found in 15 healthy pregnant women. TSH was undetectable in 27 hyperthyroid patients, of whom six were tested with thyroliberin stimulation and failed to respond. The mean TSH concentration measured in 62 seriously ill hospital patients of 2.7 (SD 2.5) milli-int. units/L was significantly higher (p less than 0.05) than in the euthyroid patients. Basal values and peak TSH responses to thyroliberin testing correlated well (r = 0.63, n = 48), irrespective of clinical diagnosis. We conclude that the present assay readily discriminates between euthyroid and hyperthyroid patients and should replace conventional TSH RIAs in diagnostic laboratories.

Adolescent↗
PubMed1986

Hemodynamic progression of adult valvular aortic stenosis.

Hemodynamic progression of valvular aortic stenosis was studied in 54 patients who had serial cardiac catheterizations. There were 47 men and 7 women with a mean age of 61.2 years. The time interval between studies was 4.4 years (range, 0.4-12.2). Associated coronary artery disease was present in 37 patients (69%). The initial mean aortic valve area (Hakki's formula) was 1.26 cm2 (range, 0.66-2.85), and the aortic valve area at last follow-up was 0.77 cm2 (range, 0.29-1.95), with mean reduction of 0.49 cm2. The mean peak systolic gradient increased from 23.3 +/- 15.1 mm Hg at initial study to 52.6 +/- 27.5 mm Hg at last study, a mean increase of 29.3 +/- 23.6 mm Hg. Patients with no or mild left ventricular impairment and no or mild coronary artery disease are more likely to have progression than patients with more severe left ventricular impairment or coronary artery disease (P less than 0.05). Aortic valve replacement for progressive aortic stenosis was required at a later date after coronary artery bypass grafting in a small group of nine patients. In this small group, there was high intraoperative mortality of 33%.

Adult↗
PubMed1985

The nuclear matrix continues DNA synthesis at in vivo replicational forks.

Alkaline cesium chloride gradient analysis of in vivo [3H]bromodeoxyuridine-labeled and in vitro [alpha-32P]dCTP-labeled DNA was used to determine whether in vitro DNA synthesis in regenerating rat liver nuclei and nuclear matrices continued from sites of replication initiated in vivo. At least 70 and 50% of the products of total nuclear and matrix-bound in vitro DNA synthesis, respectively, were continuations of in vivo initiated replicational forks. The relationship of the in vitro DNA synthetic sites in total nuclei versus the nuclear matrix was examined by using [3H]bromodeoxyuridine triphosphate to density label in vitro synthesized DNA in isolated nuclei and [alpha-32P]dCTP to label DNA synthesized in isolated nuclear matrix. A minimum of about 40% of matrix-bound DNA synthesis continued from sites being used in vitro by isolated nuclei. Furthermore, nuclear matrices prepared from in vitro labeled nuclei were 5-fold enriched in DNA synthesized by the nuclei and were several-fold enriched, compared to total nuclear DNA, in a particularly high density labeled population of DNA molecules.

Animals↗
PubMed1985

Properties of adenoviral DNA bound to the nuclear matrix.

The association of adenoviral DNA with the high salt (2 M NaCl) resistant nuclear fraction, termed the nuclear matrix, has been investigated in HeLa cells at different times after infection with adenovirus type 5. When nuclear matrices were prepared in the absence of exogenously added nucleases, Ad5 DNA was quantitively associated with the matrix throughout the infection period (0-24 h). Moreover, early in infection (0-10 h) Ad5 DNA was severalfold enriched in DNase I digested nuclear matrices (8-15% of total nuclear DNA) compared to the high salt soluble chromatin fraction (85-90% of total nuclear DNA). At later times after infection, progressively more Ad5 DNA appeared in the chromatin fraction until, at 24 h, the nuclear matrix was strikingly depleted in Ad5 DNA. A large proportion of the Ad5 DNA in nuclear matrices prepared early in infection, e.g., 4 h, was full length in size. At later times (12-24 h) most of the viral DNA was fragmented to a size equivalent to total matrix DNA (100-1000 base pairs). The apparent switch of the matrix-associated viral DNA from a relatively DNase I resistant to sensitive state was initiated approximately at the time when viral DNA replication began (12 h). Since no discrete portion of the Ad5 genome was significantly enriched at the sites of attachment to the nuclear matrix throughout the infection period, the switch in DNase I sensitivity is not mediated by a change in DNA sequence attachment to the matrix.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenoviruses, Human↗
PubMed1985

Estimation of the effects of angioplasty on coronary stenosis using quantitative video angiography.

In this study, we compared stenosis severity by quantitative coronary angiography from video and cine images with visual estimation in 14 patients who underwent PTCA. Both cine and video analysis demonstrated a change from 65.2 +/- 2.5 to 36.5 +/- 3.1% diameter stenosis following PTCA, whereas visual estimation (average of three observers) showed improvement from 89.9 +/- 1.7 to 36.0 +/- 3.2%. Percent area stenosis from quantitative angiography showed improvement from 87.9 +/- 1.8 to 56.4 +/- 5.8. These data indicate that visual assessment overestimated percent diameter of severe lesions. To determine if video analysis could provide rapid quantitative assessment of PTCA results, we compared percent diameter and percent area stenosis by video with cine (diameter: correlation coefficient, 0.82; slope, 0.79; area: correlation coefficient, 0.86; slope, 0.83). These results indicate that video-based measurements are not different from cine-derived measurements. Quantitative coronary angiography provides an accurate estimate of changes produced by PTCA and can be performed rapidly and accurately on video images, thus making results available during the PTCA procedure.

Angiography↗
PubMed1985

Three-dimensional cardiac anatomy and function in heart disease in adults: initial results with the dynamic spatial reconstructor.

The dynamic spatial reconstructor, or DSR, is a unique high-speed volume-imaging x-ray scanner based on computed tomographic principles. In this report, we present data obtained from the first feasibility DSR studies of adult patients with heart disease. Information from three patients--one with hypertrophic obstructive cardiomyopathy, one with calcific aortic valvular disease, and one with a left ventricular aneurysm--is described in detail. The mean DSR scanning time for each patient was 20 seconds, and the mean total irradiation to the sternum was 15.3 R. Transverse cross sections were reconstructed and then retrospectively reformatted to provide operator-selected oblique sections in space (for example, long-axis and short-axis sections of the left ventricle), to follow these sections through time (such as from end-diastole through end-systole), and to create three-dimensional displays (for instance, of the left ventricular chamber). Unique quantitative measurements of structure and function were made by using these images. For generation of most imaging data, only one injection of contrast material into the right side of the heart is necessary. Clinically useful three-dimensional dynamic imaging data can be acquired from adult patients with heart disease by using the DSR. Compared with conventional angiocardiography, DSR studies can provide information with less x-ray exposure and fewer angiographic injections.

Adult↗
PubMed1985

Percutaneous transluminal coronary angioplasty, alone or in combination with streptokinase therapy, during acute myocardial infarction.

The treatment strategy in 66 consecutive patients who underwent invasive therapy for acute myocardial infarction was analyzed, and specific attention was focused on the role of percutaneous transluminal coronary angioplasty. The following four treatment regimens were used: angioplasty alone (11 patients), angioplasty followed immediately by administration of streptokinase (15), streptokinase therapy alone (11), and streptokinase therapy followed by angioplasty (29). Reperfusion was achieved in 91%, 80%, 82%, and 72% of these subgroups, respectively. Angioplasty was particularly helpful in patients with severe residual stenoses after intracoronary administration of streptokinase and in patients in whom streptokinase therapy failed to reopen the occluded artery. Angioplasty further reduced the residual stenosis in 11 of 15 patients (73%) with successful thrombolysis, and it restored blood flow in 10 of 14 patients (71%) in whom thrombolysis had failed to do so. The incidence of reinfarction after therapy was similar in all four treatment groups. Patients in whom angioplasty was used either alone or in combination with streptokinase therapy had a significantly decreased incidence of subsequent revascularization (less than 30% compared with 82%). Angioplasty is of considerable value in patients undergoing invasive therapy for acute infarction. In some patients, it may be used as the only treatment; in others, it may be used to treat severe residual stenosis after initial streptokinase therapy. Finally, angioplasty achieves reperfusion in most patients in whom streptokinase therapy has failed.

Adult↗
PubMed1985

Intracoronary thrombus: role in coronary occlusion complicating percutaneous transluminal coronary angioplasty.

Angiograms from 238 consecutive patients who underwent percutaneous transluminal coronary angioplasty at the Mayo Clinic were reviewed to determine the presence of intracoronary thrombus before dilation. Patients with previously occluded vessels and those receiving streptokinase therapy were excluded. Intracoronary thrombus before dilation was present in 15 patients (6%); complete occlusion occurred in 11 (73%) of these during or immediately after dilation. None of these patients had angiographic evidence of major intimal dissection. In contrast, among the 223 patients in whom no intracoronary thrombus was present before dilation, complete occlusion occurred in 18 (8%) and in 12 was associated with major intimal dissection. The difference between the complete occlusion rates for patients with and without prior intracoronary thrombus was highly significant (73 versus 8%, respectively, p less than 0.001). Therefore, the presence of intracoronary thrombus identifies a group of patients who are at increased risk of developing complete occlusion during or after attempted coronary artery dilation.

Acute Disease↗
PubMed1985

Angiographic occurrence and clinical correlates of intraluminal coronary artery thrombus: role of unstable angina.

The importance of intraluminal coronary artery thrombus in acute myocardial infarction is now recognized. Coronary thrombi, however, may be important in ischemic syndromes other than infarction. The coronary angiograms of 268 consecutive patients undergoing diagnostic angiography were prospectively examined for intracoronary thrombus and form the basis of this study. Of these patients, 29 (11%) (25 men and 4 women) met the criteria for coronary artery thrombus. Of the 29 patients with thrombus, 24 (83%) had unstable angina before angiography. The five remaining patients with thrombus had had a transmural myocardial infarction 3 to 18 months before cardiac catheterization. In 21 patients, the thrombus was distal to a significant stenosis; in 8 it was proximal to or at the site of a significant stenosis. Coronary artery thrombus was identified in 24 (35%) of 67 patients with unstable angina compared with only 5 (2.5%) of 201 patients with stable angina (p less than 0.0001).

Angina Pectoris↗
PubMed1985

Distribution of initial and persistent 2-acetylaminofluorene-induced DNA adducts within DNA loops.

The intranuclear distribution of initial and persistent DNA adducts induced in vivo after four weekly injections of the hepatocarcinogen 2-acetylaminofluorene was examined in rat liver by using a protocol that fractionates chromatin from various regions of each of the multiple nuclear DNA loops. Ten hours after the initial dose, two acetylated [(N-acetyl-N-(deoxyguanosin-8-yl)-2-aminofluorene and 3-(deoxyguanosin-N2-yl)-2-acetylaminofluorene] and one deacetylated [N-(deoxyguanosin-8-yl)-2-aminofluorene] adduct were detected by a 32P-labeling assay and were found to have a random genomic distribution, as evident by their relative concentrations in various chromatin fractions. These data suggest that all regions of the DNA loops are equally susceptible to adduct formation. A nonrandom persistence of the deacetylated adduct in the regions where the DNA loops are constrained by the nuclear matrix was evident by 6 days after the last dose and was markedly apparent by 60 days. In contrast, all chromatin fractions had equally inefficient removal of the N2-acetylated adduct by 6 days as well as 60 days but had complete removal of the C8-acetylated adduct. These findings suggest that pronounced regional differences in adduct repair along the DNA loops may play a role in chemically induced hepatocarcinogenesis.

2-Acetylaminofluorene↗
PubMed1985

Alterations in chromatin conformation are accompanied by reorganization of nonchromatin domains that contain U-snRNP protein p28 and nuclear protein p107.

The intranuclear distribution of nuclear matrix-associated protein p107 and the 28-kD Sm antigen of U-snRNPs have been studied using double-label immunofluorescence and immunoperoxidase electron microscopy. In interphase nuclei of HeLa cells, Novikoff hepatoma cells, and rat kangaroo kidney cells, p107 was confined to discrete interchromatin domains. The domains had an irregular contour, with an average diameter of 1-1.5 micron. Each domain appeared to be composed of interconnected granules. The Sm antigen colocalized and appeared concentrated in these domains but also showed some general nucleoplasmic distribution. During mitosis, the interchromatin domains disassembled such that the Sm portion redistributed to the perichromosomal and spindle regions and the p107 component redistributed throughout the mitotic cytoplasm. During anaphase, p107 assembled into discrete clusters throughout the mitotic cytoplasm. The Sm antigen was not a component of these clusters. Double-label immunofluorescence with anti-p107 and the anti-DNA tight-binding protein, AhNa1, showed that the extranuclear p107 domains assumed an interchromatin localization only after the chromosomes had decondensed. The correlation between chromosome decondensation and the occurrence of p107 within interchromatin domains was also observed during chicken erythrocyte nuclear reactivation. We propose that the discrete interchromatin domains that contain p107 and p28 may be important for processing and splicing of RNA and that their structural assembly within nuclei is sensitive to the presence of the transcriptionally active conformation of chromatin.

Animals↗