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Biomedical subjects

A R Lucas

Publications and source records attributed to A R Lucas.

At least 37 records · Page 2Linked to original sources
PubMed1989

Correlation of fluorescence emission with the plaque content and intimal thickness of atherosclerotic coronary arteries.

The use of fluorescence emission for guidance during laser angioplasty may be limited by the complexity of the emission from the broad range of atherosclerotic plaques normally encountered in disease coronary arteries. Fatty, fibrous, and calcific plaque content as well as maximal intimal thickness were measured and correlated with fluorescence intensity ratios from the emission spectra for a broad cross-section of atherosclerotic plaques from human necropsy specimens. Multiple and stepwise regression analysis was used to analyze intensity ratios of 13 wavelengths between 390 and 600 nm corresponding to regions of observed spectral structure. The level of correlation of the intensity ratios with fatty and calcific plaque content was found to be dependent on the complexity of the atherosclerotic lesion. The fluorescence emission was found to correlate well with both fibrous plaque content and intimal thickness, allowing the differentiation between normal and atherosclerotic samples. In conclusion, plaque characteristics can be assessed by fluorescence emission, although the successful implementation of spectroscopic guidance is dependent on the level of prediction error which may vary with tissue type.

Arteries↗
PubMed1988

Clinical and noninvasive hemodynamic results after aortic balloon valvuloplasty for aortic stenosis.

Balloon valvuloplasty has been shown to be an effective treatment for adults with aortic stenosis, typically providing a 50 to 80% increase in aortic valve area and marked improvement in exertional dyspnea, angina and syncope. However, the duration of this hemodynamic and clinical improvement is uncertain. Forty-two patients were followed for 10.2 +/- 0.5 months. Balloon valvuloplasty caused dramatic immediate reduction in the number of patients with moderate or severe dyspnea (80 to 14%), moderate or severe angina (39 to 2%) and syncope (30 to 2%). Furthermore, this improvement in symptoms continued for the duration of the follow-up period in most patients. Echocardiographic aortic valve mean gradient and area determined at 3-month intervals, however, showed a trend toward or return to prevalvuloplasty levels by 9 months' follow-up in 13 of 25 patients (52%), whereas 12 of 25 patients showed no deterioration in their hemodynamic parameters. This trend toward restenosis was accompanied by symptomatic deterioration in 5 of 13 patients (38%). This tendency toward restenosis in greater than 50% of patients by 9 months underscores the need for further technical improvements if balloon valvuloplasty is to be widely applied. Even with these limitations, however, balloon valvuloplasty seems to provide a significant improvement in actuarial survival compared with the natural history of elderly patients with severe aortic stenosis.

Actuarial Analysis↗
PubMed1988

Anorexia nervosa in Rochester, Minnesota: a 45-year study.

The incidence of anorexia nervosa during a 45-year period (1935 through 1979) was determined for the population of Rochester, Minnesota, from the epidemiology archives at the Mayo Clinic. The medical records of local residents with the diagnosis of anorexia nervosa were the primary source for case ascertainment, although records of those whose diagnoses might have been shielding anorexia nervosa were also screened. Standard criteria for diagnosis were applied. We identified 140 (128 female and 12 male) residents of the community who fulfilled the diagnostic criteria for anorexia nervosa. No significant long-term trend in rates was ascertained. The overall age- and sex-adjusted incidence rate was 7.3 per 100,000 person-years. The highest age-specific incidence rate (56.7 per 100,000 person-years) occurred in female residents 15 to 19 years old. The prevalence rate on Jan. 1, 1980, for Rochester residents with a history of the disease, age- and sex-adjusted to the 1970 US white population, was 113.1 per 100,000 (203.9 for female and 16.9 for male residents).

Adolescent↗
PubMed1988

Laser therapy in the treatment of cardiovascular disease.

Percutaneous laser angioplasty has now become a clinical reality, consisting chiefly of applications of thermal angioplasty in conjunction with balloon angioplasty for the recanalization of peripheral vascular obstructions. In conjunction with this development, various aspects of laser-tissue interactions, fibreoptic transmission and delivery catheter design pertinent to the cardiovascular system have come under closer scrutiny, resulting in the emergence of both noteworthy concepts and clinical achievements.

Angiography↗
PubMed1987

Gastric electromechanical and neurohormonal function in anorexia nervosa.

The gastrointestinal motor function in patients with anorexia nervosa is poorly understood, although it may be relevant to the pathophysiology of the disorder. We have undertaken a multidisciplinary study of 8 patients with anorexia nervosa and 8 age- and sex-matched controls. We have characterized their gastrointestinal and neurohormonal function by measuring (a) gastric electrical activity, (b) antral phasic pressure activity, (c) gastric emptying of solids and liquids, and (d) hormonal and autonomic function. Patients with anorexia nervosa at the time of the initiation of therapy presented with (a) increased episodes of gastric dysrhythmia (mean percentage of dysrhythmic time: 9.75 patients vs. 0.48 controls during fasting, p less than 0.02; 7.21 patients vs. 0.18 controls postcibally, p less than 0.001), (b) impaired antral contractility (mean motility index, 12.8 patients vs. 14.2 controls, p less than 0.002), (c) delayed emptying of solids, (d) decreased postcibal blood levels of norepinephrine and neurotensin (levels of beta-endorphin, insulin, glucagon, gastric inhibitory polypeptide, gastrin, cholecystokinin, and human pancreatic polypeptide were normal), and (e) impaired autonomic function (resting diastolic blood pressure and skin conductance were decreased and the response to the cold pressor test was dampened). Differences between patient and control groups were statistically significant. We conclude that patients with anorexia nervosa present multiple gastrointestinal abnormalities involving control mechanisms as well as target organs.

Adolescent↗
PubMed1986

Effect of anorexia nervosa on linear growth.

To study the effect of severe undernutrition on linear growth during adolescence, a report was obtained on the ultimate adult height of 71 patients who had had anorexia nervosa at or before age 16 years. At time of diagnosis (ages 9-16 years) median height percentile was 49; at adult follow-up (ages 18-29 years) the median height percentile was 55. This change favoring growth was statistically significant (p less than 0.01). Height percentile was maintained or increased in 45 patients and decreased in 26 patients. In only four patients did it change by more than 20 percentile points downward; in 12 patients height percentile increased by more than 20 points. We conclude that, despite weight loss of up to 45 percent at or before age 16 years, most patients with anorexia nervosa continue to grow in stature according to expected norms.

Adolescent↗
PubMed1985

Sutureless intraluminal graft for repair of abdominal aortic aneurysm.

A series of seven patients undergoing elective repair of abdominal aortic aneurysms using sutureless intraluminal aortic prostheses for infrarenal tube grafts was reviewed. Follow-up was five to seven months. There was no morbidity related to the graft and one late mortality. In the uncomplicated cases, the average total operative time was two hours 14 minutes with no bank blood transfusions. The overall average operative time was two hours 41 minutes with an average operative transfusion of 0.28 units and total transfusions of 1.70 units of bank blood per case. Based on this experience and the observation that operative time and blood loss are major determinants of mortality with emergency abdominal aortic aneurysm repairs, we believe that use of sutureless intraluminal prostheses in suitable cases of leaking or ruptured abdominal aortic aneurysms has the potential to markedly improve survival.

Aorta, Abdominal↗
PubMed1985

Sexual, body-image, and personality attitudes in anorexia nervosa.

Assessment of adolescent females with anorexia nervosa was carried out at the time of hospitalization and again at discharge. Findings were compared to those from a normal weight control group. The anorexic subjects at the start of treatment indicated significantly negative attitudes about sexual issues. They also reported a significantly poorer self-evaluation of their body, personality, and social skills than was evident in the comparison group. An improvement in attitude regarding these issues was demonstrated by the end of treatment. The function of weight loss in dealing with these problem areas was discussed.

Adolescent↗
PubMed1984

Dietary patterns in anorexia nervosa.

This study characterized the dietary patterns of 96 patients with anorexia nervosa who were seen for diet history. The mean age of the patients was 16.6 yr, and mean loss from preillness weight was 28%. Twenty-five patients ate high-quality meals regularly but simply restricted calories. Eleven maintained a high-quality diet but ate at irregular intervals; of these, six had episodes of binge-eating and vomiting or fasting. Among patients whose diets were qualitatively poor, 19 consumed regular meals and 41 ate irregularly; 31 of the latter had episodes of binge-eating and vomiting or fasting. No typical profile of dietary manipulations by these patients was found. Beyond the generalization that there was caloric restriction that resulted in weight loss, there was great variability in the diet patterns.

Adolescent↗
PubMed1982

'Pigging out'.

Explore the source record for details and available documents.

Body Image↗
PubMed1981

An immunological assessment of patients with anorexia nervosa.

Patients with most forms of protein-calorie malnutrition are typically more susceptible to infection. We studied the immunological consequences of a subgroup of malnourished subjects--nine patients with anorexia nervosa, who typically have a lower incidence of infection. The profiles of the patients with anorexia nervosa deviated from the reported typical profile of significantly depressed cell-mediated immunity in subjects with more common forms of protein-calorie malnutrition, demonstrating normal T-lymphocyte populations and unimpaired proliferative lymphocyte responsiveness to mitogenic stimulation with phytohemagglutinin and concanavalin A. In fact, mitogen responsiveness was significantly elevated above that of controls, and with nutritional repletion, this enhanced responsiveness regressed toward control values. Since impaired cell-mediated immunity has been consistently documented in other malnourished populations, and presumably contributes to their increased propensity toward infection, the maintenance of a relatively intact cell-mediated immune system may be an important factor separating the malnourished anorexia nervosa patient from other protein-calorie malnourished patients.

Adolescent↗