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Biomedical subjects

W C Roberts

Publications and source records attributed to W C Roberts.

At least 91 records · Page 5Linked to original sources
PubMed1994

One-year prospective replication study of an untreated sample of community dysthymia subjects.

This study replicates an earlier naturalistic-prospective investigation of nontreatment, community DSM-III-R dysthymia subjects. Major goals were to determine spontaneous remission rates and monitor the stability of psychosocial functioning levels over time. Twenty-four dysthymia subjects were followed for 1 year. Three remissions (13%) were diagnosed at the final interview. At a 4-year diagnostic follow-up contact with the remitters only, one remitter had relapsed and two remained in remission. Subjects were monitored for depressive symptom intensity, personality functioning, general medical distress, cognitive functioning, coping stylistics, interpersonal functioning, quality of their social support resources, and general family functioning. Stable levels of psychosocial functioning were maintained across all measures over the 1-year period. Current psychometric findings confirm the conclusions of the earlier nontreatment prospective study that dysthymia is a chronic mood disorder with stable psychosocial features and is unlikely to remit spontaneously over time.

Adaptation, Psychological↗
PubMed1994

Comparison of a community dysthymia sample at screening with a matched group of nondepressed community controls.

The primary goal of the study was to compare the psychosocial functioning of an untreated, community sample of DSM-III-R dysthymia subjects (N = 24) at screening to that of a matched sample of community nondepressed volunteers (N = 18) with no lifetime or current history of axis I disorders. Subjects were compared across a number of psychosocial indices. The dysthymics were found to be less sociable (introversion) and clinically high on neuroticism-instability, external in regard to their causal attributions, less stable for positive uncontrollable events and more stable and global for negative uncontrollable events, relying more on coping strategies such as wishful thinking and self-blame, more interpersonally submissive and hostile, and to have a poorer social support-resource network. In addition, the dysthymics reported more family dysfunction and a higher rate of negative major life events.

Adaptation, Psychological↗
PubMed1994

Coronary artery calcification: assessment with electron beam CT and histomorphometric correlation.

PURPOSE: To assess the reliability of electron beam computed tomography (CT) in the detection of calcific deposits in coronary arteries. MATERIALS AND METHODS: The authors quantitatively evaluated a total of 4,298 segments of coronary arteries with electron beam CT and histomorphometry. RESULTS: Regression analysis of the electron beam CT calcium score versus histomorphometric calcium area produced an r2 value of .92 (r = .96; P < .0001). Ninety-three percent (78 of 84) of all coronary arteries with stenosis of 76%-100% contained calcific deposits, and 20% (17 of 83) of all coronary arteries with stenosis of 0%-50% contained calcific deposits. CONCLUSION: The amount of calcific deposits detected with electron beam CT correlates highly with histomorphometric measurements. Also, the amount of calcific deposits correlates well with the degree of coronary artery stenosis. Electron beam CT, therefore, is a promising noninvasive technique that can help depict the presence and extent of atherosclerotic plaques.

Adult↗
PubMed1994

Coronary artery disease: prediction with in vitro electron beam CT.

PURPOSE: To investigate the potential to predict coronary artery disease with electron beam computed tomography (CT). MATERIALS AND METHODS: Fifty heart specimens were examined with electron beam CT and histomorphometric techniques to measure calcific deposits as a percentage of blockage. RESULTS: In group A specimens (from cadavers of patients with symptomatic coronary artery disease), calcific deposits were identified at electron beam CT in 41% (584 of 1,426) of all segments of coronary arteries; in group B specimens (with asymptomatic coronary artery disease), in 24% (369 of 1,535) of all segments; and in the normal control specimens, in 4% (47 of 1,337) of all segments; segments (group A vs control specimens, P < .0001; group B vs control specimens, P = .02). On the basis of logistic regression analysis, coronary artery disease would be predicted if the average electron beam CT calcium score exceeds 0.32. The sensitivity and specificity of electron beam CT in the detection of calcific deposits per coronary artery was 94% and 76%, respectively. CONCLUSION: The electron beam CT calcium score appears to be an effective predictor of coronary artery disease.

Adult↗
PubMed1994

Myocardial energy metabolism and morphology in a canine model of sepsis.

The mechanism responsible for sepsis-induced myocardial depression is not known. To determine if sepsis-induced myocardial depression is caused by inadequate free energy available for work, we studied myocardial energy metabolism in a canine model of sepsis. Escherichia coli-infected (n = 18) or sterile (n = 16) fibrin clots were implanted intraperitoneally into beagles. Myocardial function and structure was assessed using radionuclide ventriculograms, echocardiograms, and light and electron microscopy. The adequacy of energy metabolism was evaluated by comparing catecholamine-induced work increases [myocardial O2 consumption (MVO2) and rate pressure product (RPP)] with a simultaneously obtained estimate of intracellular free energy [phosphocreatine-to-adenosine triphosphate ratio (PCr:ATP)] determined by 31P-magnetic resonance spectroscopy. When compared with control animals, septic animals had a decrease in left ventricular ejection fraction (EF, P < 0.0001) on day 1 and fractional shortening (FS, P < 0.0003) on day 2 after clot implantation. On day 2, neither septic nor control animals had statistically significant decreases in PCr:ATP, despite catecholamine-induced increases in MVO2 and RPP (mean maximal increases in septic animals 135 +/- 31 and 51 +/- 10%, respectively). Light and electron microscopic findings showed that hearts of septic animals, compared with control animals, had a greater degree of morphological abnormalities. Thus, in a canine model of sepsis with alterations in myocyte ultrastructure and documented myocardial depression (decreased EF and FS), intracellular free energy levels (PCr:ATP) were maintained despite catecholamine-induced increases in myocardial work (increased MVO2 and RPP), suggesting high-energy synthetic capabilities are not limiting cardiac function.

Adenosine Triphosphate↗
PubMed1994

Specific factor Xa inhibition reduces restenosis after balloon angioplasty of atherosclerotic femoral arteries in rabbits.

BACKGROUND: Balloon angioplasty of atherosclerotic arteries results in activation of the coagulation cascade. Several coagulation factors, including factor Xa and thrombin, are mitogenic for vascular smooth muscle cells in vitro and thus may play a role in restenosis after balloon angioplasty. Specific inhibition of factor Xa can be achieved with recombinant antistasin (rATS) or tick anticoagulant peptide (rTAP). We hypothesized that inhibition of Xa would limit restenosis after balloon angioplasty in an atherosclerotic rabbit model. METHODS AND RESULTS: Focal femoral atherosclerosis was induced by air desiccation injury and a high-cholesterol diet in 38 New Zealand White rabbits. Recombinant antistasin (n = 20 arteries) or rTAP (n = 14 arteries) was administered by intravenous bolus at the time of balloon angioplasty and followed by a 2-hour infusion; controls (n = 21 arteries) received bolus heparin alone (150 U/kg). Therapeutic prolongation of the activated partial thromboplastin time occurred, and antithrombotic drug levels were achieved in all animals. Luminal diameter in millimeters by quantitative angiography did not differ between treatment groups before (1.1 +/- 0.2 for controls, 1.1 +/- 0.2 for rATS, and 1.1 +/- 0.3 for rTAP) or after balloon angioplasty (1.5 +/- 0.3 for controls, 1.4 +/- 0.2 for rATS, and 1.4 +/- 0.2 for rTAP). At 28 days, treatment with factor Xa inhibitors tended to result in arteries with larger luminal diameter than controls (1.2 +/- 0.3 for rATS, 1.2 +/- 0.3 for rTAP versus 1.0 +/- 0.3 for control, P = .09 by one-way ANOVA). Restenosis, defined as reduction in angiographic luminal diameter (in mm) from 2 hours after angioplasty to 28 days after angioplasty was less in the rATS group than in controls (-0.2 +/- 0.1 versus -0.5 +/- 0.4, P < .001) and tended to be less in the rTAP group (-0.3 +/- 0.2 versus -0.5 +/- 0.4, P = .07). Quantitative histopathological analysis showed less percent cross-sectional area narrowing by plaque in both rATS- and rTAP-treated arteries compared with controls (42 +/- 21%, 47 +/- 18%, and 63 +/- 14%, respectively; P < .01 by one-way ANOVA). CONCLUSIONS: We conclude that a 2-hour infusion of rATS or rTAP reduced angiographic restenosis and resulted in less luminal cross-sectional narrowing by plaque compared with controls.

Angioplasty, Balloon↗
PubMed1994

Geometric remodeling is not the principal pathogenetic process in restenosis after balloon angioplasty. Evidence from correlative angiographic-histomorphometric studies of atherosclerotic arteries in rabbits.

BACKGROUND: Restenosis after balloon angioplasty of coronary arteries is thought to be a proliferative response of the arterial wall to injury. Recently, it has been suggested that geometric remodeling of the arterial wall, rather than intimal fibromuscular hyperplasia, may be the major pathophysiological mechanism underlying restenosis. In this study, we evaluated the relative contribution of a geometric decrease in arterial size versus neointimal growth to luminal narrowing associated with restenosis after balloon angioplasty of atherosclerotic femoral arteries in rabbits. METHODS AND RESULTS: Focal femoral atherosclerosis was induced by endothelial desiccation injury followed by a 2% cholesterol diet. After 1 month on the high cholesterol diet, the animals were subjected to one of four strategies: (1) balloon angioplasty, (2) balloon angioplasty followed by treatment with the factor Xa inhibitor antistasin, (3) combined laser and balloon angioplasty, or (4) no angioplasty. Animals were killed 2 hours or 28 days after angioplasty, and excised femoral artery segments were prepared for histomorphometric analysis. Angiography was performed serially before and immediately after angioplasty and before the animals were killed. An initial postprocedural gain in luminal diameter at sites of angioplasty was followed by a significant reduction in diameter by angiography and a significant increase in luminal cross-sectional area narrowing by plaque by histomorphometry 28 days after angioplasty compared to adjacent nonangioplastied segments of the same arteries, to nonangioplastied control arteries, or to angioplastied segments of animals treated with the factor Xa inhibitor antistasin. By contrast, the overall arterial size (cross-sectional area bounded by the external elastic lamina) at sites of restenosis was not significantly different from adjacent nonangioplastied segments in the majority of arteries excised at 28 days, and the mean overall arterial size at sites of restenosis was not significantly different from corresponding segments of nonangioplastied control arteries or from angioplastied segments of animals treated with antistasin. In the minority of angioplastied arteries in which the arterial size did change, most got larger. CONCLUSIONS: Geometric remodeling resulting in a decrease in overall cross-sectional arterial size does not appear to be the principal pathogenetic mechanism for restenosis after balloon angioplasty with or without laser in this experimental model.

Angiography↗
PubMed1993

Comparison of morphologic findings in spontaneously occurring hypertrophic cardiomyopathy in humans, cats and dogs.

Morphologic features of spontaneously occurring hypertrophic cardiomyopathy (HC) were compared in 38 humans, 51 cats and 10 dogs. Asymmetric hypertrophy of the ventricular septum, marked disorganization of cardiac muscle cells, abnormal intramural coronary arteries and myocardial fibrosis were each present in the ventricular septum of human, feline, and canine forms of HC; these abnormalities were generally more severe and most frequently identified in humans. Asymmetric left ventricular hypertrophy (based on the calculated septal-to-free wall thickness ratio) was most common in humans (31 of 38 [81%]) and dogs (8 of 10 [80%]), as compared with cats (16 of 51 [31%]; p < 0.001) with HC; in all 3 species, hypertrophy was often diffuse, involving substantial portions of the anterolateral and posterior free walls, and the ventricular septum. Marked septal disorganization (> or = 5% of the tissue section) was present in 35 patients (92%), but in only 14 cats (27%) and 2 dogs (20%) (p < 0.001). Abnormal intramural coronary arteries occurred with similar frequency in the ventricular septum of patients (n = 25; 66%), cats (n = 38; 74%) and dogs (n = 6; 60%) (p < NS). Moderate-to-severe septal fibrosis was identified more commonly in humans (15 of 38 [39%]) than in animals (13 of 61 [21%]; p < 0.001). In all 3 species, abnormal intramural coronary arteries were most commonly observed within or at the margins of areas of fibrous tissue. These morphologic findings describe spontaneously occurring models of HC in cats and dogs with substantial structural similarities to the well-recognized disease entity in humans.

Adolescent↗
PubMed1993

Gross and semiquantitative histologic findings in mononuclear cell myocarditis causing sudden death, and implications for endomyocardial biopsy.

The distribution of gross myocardial lesions and the relative density of the inflammatory cells in various myocardial locations (subepicardial and subendocardial halves of the left ventricular free wall, right ventricular and left ventricular halves of the ventricular septum, and the right ventricular free wall) were studied in 14 patients (11 male [79%], 8 black [57%], aged 7 months to 65 years [median 16 years]) who died suddenly of acute mononuclear-cell myocarditis. Grossly visible myocardial lesions were present in 8 patients, and preferentially involved the subepicardial regions of the left ventricular free wall. The highest mean number of mononuclear cells were seen in the subepicardial regions of the left ventricular free wall (193 cells per high-power field) and the lowest in the right ventricular one half of the ventricular septum (92 cells per high-power field, p < 0.001). Thus the predominant location of the gross myocardial lesions in acute mononuclear-cell myocarditis is the subepicardial region of the left ventricular free wall. A relatively low density of mononuclear cells are found in the right ventricular half of the ventricular septum, the main location of endomyocardial biopsies.

Adolescent↗
PubMed1993

Clinicopathologic features of hypertrophic cardiomyopathy managed by cardiac transplantation.

Clinical records, electrocardiographic, echocardiographic, hemodynamic and radionuclide data, and the operatively excised hearts were reviewed in 10 patients (aged 19 to 46 years, mean 35) who had cardiac transplantation for hypertrophic cardiomyopathy. Severe congestive heart failure unassociated with outflow obstruction was the indication for transplantation in 9 patients. During a pretransplantation period ranging from 45 to 312 months (mean 137) in these 9 patients, pulmonary artery wedge pressure increased from 19 +/- 9 to 27 +/- 7 mm Hg, left ventricular ejection fraction decreased from 51 +/- 11% to 41 +/- 1%, left ventricular end-diastolic dimension increased from 42 +/- 6 to 48 +/- 4 mm, and total 12-lead QRS voltage decreased from 209 +/- 50 to 156 +/- 41 mm. In these 9 patients, the explanted hearts had dilated left ventricular cavities, and 8 had left ventricular scars without significant narrowing of the epicardial coronary arteries. The tenth patient had a nondilated left ventricular cavity and had transplantation because of recurrent, refractory syncope. Of the 10 patients, 3 died within the first month, and another died 8 months after transplantation. The remaining 6 patients have survived 20 to 54 months (mean 39) after transplantation and are in functional class I or II.

Adolescent↗
PubMed1993

Frequency of ring abscess and cuspal infection in active infective endocarditis involving bioprosthetic valves.

When active infective endocarditis (IE) involves a bioprosthetic valve, the infective process may involve only the cusps or sewing ring or both. We studied 34 patients with infected bioprostheses to determine whether the infection involved the cusps or ring, or both, because these locations could affect prognosis. In the 5 patients in whom active IE began < 60 days after operation, the infection involved the cusps only in 2, the ring only in 2, and both in 1. The 29 patients in whom signs and symptoms of active IE appeared > 60 days after valve replacement were subdivided into 3 categories based on the valve or valves replaced. In the 16 patients with isolated aortic valve replacement, the infection involved the cusps only in 6, the ring only in 4, and both in 6. In the 6 patients with isolated mitral valve replacement, the infection involved the cusps only in 2, the ring only in 1, and both in 3. In the remaining 7 patients, 15 native valves were replaced with bioprostheses, and 10 of them were infected. The infection involved the cusps only in 7, and both the cusps and ring in 3. Of all 34 patients, 13 had operative excision of the infected bioprosthesis: 1 died within 60 days of the bioprosthetic excision, and 1 was lost to follow-up; of the remaining 11 patients, 4 died late (1.5, 3, 5 and 14 years), and the other 7 are alive 5 to 10 years after bioprosthetic excision (all in New York Heart Association functional class I or II). Thus, although infection limited to the bioprosthetic cusps may reasonably allow a better outlook, reoperation with infection involving the annular ring (8 of 13 reoperation patients) does not prevent successful outcome.

Abscess↗
PubMed1993

Clinical factors useful in predicting aortic valve structure in patients > 40 years of age with isolated valvular aortic stenosis.

A number of reports have described the frequency of coronary arterial narrowing in patients with valvular aortic stenosis. No published reports have examined the structure of the stenotic aortic valve in adults and related the valve structure to variables, including coronary arterial narrowing, useful in predicting that structure. One hundred eighty-eight patients having aortic valve replacement for isolated valvular aortic stenosis were studied. All patients were > 40 years of age at the time of aortic valve replacement, all had coronary angiograms preoperatively, and of 182 patients (97%) measurements of serum total cholesterol had been obtained and 184 (98%) had body mass index calculated. The structure of the operatively excised valve was classified as unicuspid or bicuspid (congenitally malformed), or tricuspid aortic valve. A logistic regression model was developed that found 4 factors (age, serum total cholesterol, angiographic coronary artery disease and body mass index) to be predictive of aortic valve structure: (1) Patients with at least 3 or all 4 factors high or present (i.e., age > 65 years, serum total cholesterol > 200 mg/dl, body mass index > 29 kg/m2 and coronary artery disease) had a low probability (10 to 29%) of having a congenitally malformed valve; (2) patients with at least 3 or all 4 factors low or absent (i.e., age < or = 65 years, serum total cholesterol < or = 200 mg/dl, body mass index < or = 29 kg/m2, and no coronary artery disease) had a high probability (72 to 90%) of having a congenitally malformed valve.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗