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Biomedical subjects

A R Lucas

Publications and source records attributed to A R Lucas.

At least 19 recordsLinked to original sources
PubMed1991

Angiographic contrast media interference with laser-induced fluorescence excitation and detection in atherosclerotic human coronary arteries.

Laser-induced fluorescence has been used in conjunction with angiography for laser angioplasty guidance. The effect of radiopaque contrast media on the excitation and detection of arterial fluorescence has not been previously reported. Accordingly, fluorescence emission spectra from human coronary artery necropsy specimens (n = 7) during excitation with pulsed excimer laser excitation (308 nm) was examined before and after the addition of three different contrast media, sodium and meglumine diatrizoate, sodium and meglumine ioxaglate, and iopamidol. A decrease in overall fluorescence intensity was observed at all wavelengths for each contrast agent examined. The decrease in intensity of fluorescence emission was more marked at wavelengths less than 410 nm than at wavelengths above 425 nm. Similar effects were observed for contrast media diluted with whole blood. Absorption spectra for all three contrast media demonstrated absorption in the ultraviolet centered around 240 nm. We conclude that preferential absorption in the ultraviolet range by contrast media interferes with the excitation and detection of laser-induced fluorescence; use of visible light excitation may obviate interference with laser-induced fluorescence analysis of plaque.

Angioplasty, Laser↗
PubMed1991

50-year trends in the incidence of anorexia nervosa in Rochester, Minn.: a population-based study.

OBJECTIVE: The aim of the study was to determine incidence and prevalence rates and long-term trends in incidence of anorexia nervosa by identifying all persons residing in the community of Rochester, Minn., during the 50-year period 1935 through 1984 who had the disorder. METHOD: From a community-based epidemiologic resource, 13,559 medical records with diagnoses of amenorrhea, starvation, weight loss, anorexia nervosa, or other conditions were screened to identify true cases of anorexia nervosa determined by using standard diagnostic criteria. RESULTS: One hundred eighty-one residents (166 female and 15 male) fulfilled the diagnostic criteria for anorexia nervosa; these were the incidence cases. Due to a quadratic trend in the rates for girls 10-19 years old, the incidence rate among female residents fell from 16.6 per 100,000 person-years in the 1935-1939 period to a low of 7.0 in 1950-1954 and increased to 26.3 in 1980-1984. The incidence rates for women 20 years old and older and for males remained constant. For females 15-24 years old, there was a linear increase. The overall age-adjusted incidence rate per 100,000 person-years was 14.6 for females and 1.8 for males. The prevalence rate per 100,000 population was 269.9 for females and 22.5 for males. CONCLUSIONS: Anorexia nervosa is more common than previously recognized. Among girls 15-19 years old it is a very common chronic illness. Its incidence has increased among females 15-24 years old but not among older women or among males.

Adolescent↗
PubMed1990

Update and review of anorexia nervosa.

Anorexia nervosa is not a new disease but it has become increasingly recognized and occurs more frequently in adolescent girls and young women. Among older women, its incidence has remained constant. Scientific evidence suggests that dieting triggers a process of catastrophic weight loss in persons who are psychologically and physiologically vulnerable. Long-term studies are demonstrating diverse outcomes ranging from full recovery to chronicity and death. Treatment is often based on unproven theory and on short-term goals. Research studies comparing the effects of different treatment regimens are needed.

Anorexia Nervosa↗
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↗
PubMed1979

Anorexia nervosa.

Explore the source record for details and available documents.

Anorexia Nervosa↗
PubMed1979

Pseudoepileptic seizures in children and adolescents.

Eighteen patients ranging in age from 4 to 20 years who were seen at the Mayo Clinic from 1970 through 1976 for suspected epilepsy were studied. Seventeen of these patients had previously been treated with anticonvulsant medication, and the majority had been subjected to multiple diagnostic procedures. After careful analysis of their histories, clinical examinations, and appropriate laboratory studies, their seizures appeared to be nonepileptic in nature. Various psychogenic and other nonorganic causes were identified. These cases are presented to alert the physician to the not infrequent occurrence of pseudoepileptic seizures in children and adolescents who do not have epilepsy.

Adolescent↗
PubMed1976

The treatment of anorexia nervosa.

The authors report on their treatment of 32 young patients with severe anorexia nervosa who had lost an average of 37% of their original body weight. The therapeutic approach, conceived to meet both the physiological and the psychological needs of the patients, was carried out in a psychiatric unit for adolescents in a general hospital and involved separation of the patient from his or her family, treatment of the malnutrition, individually planned psychotherapy, and concurrent work with the family. The importance of accepting the patient's uniqueness, maintaining long-term contact, and encouraging the patient's striving toward constructive growth and autonomy is emphasized.

Adolescent↗
PubMedDate not supplied

[Enamel resistance to acid dissolution. Its relation to cariogenic activity].

Relationship existing between enamel resistance (by developed colorimetric technique) and previous experience of caries and with further incidence, at a term of a year, was studied in schoolchildren aged 6, 8, 10 and 12 years. The study comprised 336 children in 1985-1986 period and 385 children in 1985-1987 period. Non significant positive correlation was found between values of colorimetric test and previous experience of caries; but, certainly, positive correlation was found with further incidence on permanent dentition. It is concluded that colorimetric test is useful for the selection of children with a very susceptible enamel, as well as for the prognosis of cariogenic activity valued together with other parameters.

Child↗