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Biomedical subjects

J A Bean

Publications and source records attributed to J A Bean.

At least 37 records · Page 2Linked to original sources
PubMed1992

A pilot study of a new ELISA test for ciguatoxin in humans.

The major impediment to the thorough study of Ciguatera in human populations has been the lack of definitive diagnostic ability. However, recently an ELISA test was developed which can diagnose Ciguatera qualitatively and quantitatively in human fluids, as well as in contaminated fish tissue. This study proposes to evaluate this new ELISA test in human subjects with the clinical diagnoses of acute and chronic Ciguatera Poisoning. The contaminated fish from exposed subjects, and the blood and urine of exposed and controls, will be examined using the new ELISA. The ELISA performance will be compared to traditional bioassays for the fish testing. In addition, a distinct diagnostic profile will be developed using serial questionnaires, physical examinations, and nerve conduction tests. Ultimately this ELISA test can be used not only in establishing the correct diagnosis of Ciguatera Poisoning, but also in the treatment and clinical prognosis, and in epidemiologic studies of Ciguatera Poisoning in human populations. We hope that this protocol will serve as a model for the study of the effects of other marine toxins on human populations.

Adult↗
PubMed1991

Oncologists' reluctance to accrue patients onto clinical trials: an Illinois Cancer Center study.

Clinical trials are recognized as the standard of care for the cancer patient, and the randomized, controlled trial represents the most definitive method to determine the effectiveness or ineffectiveness of a cancer treatment. However, less than 3% of all eligible patients enter a clinical trial. Of the 437 physician members of the Illinois Cancer Center (ICC), 244 responded to a survey designed to determine factors that present a significant barrier to entering patients on clinical trials. Rigid protocol design was the primary deterrent to accrual, especially for medical oncologists. Surgeons, radiation oncologists, and medical oncologists differed with respect to several factors, including willingness to seek a clinical trial, tendency to treat patients off study, quality-of-life issues, and the belief that trials were too excessive in time commitment (P less than .05). Compared with hospital-based physicians, community oncologists had fewer patients on trial, were more likely to enter patients on the basis of age, and were more concerned about aspects of informed consent and the financial burden of a trial (P less than .01). One third of the physicians never pursued a clinical trial because of conflict with the priorities of individual care and excessive follow-up time. Fourteen percent indicated that they discouraged patients from participating in a clinical trial due to the risk of a patient receiving a placebo and patient follow-up requirements (P less than .05). Subgroups of physicians differ in their reluctance to accrue patients, and there are clusters of beliefs expressed by physicians concerning their clinical trial activity. Current conduct of clinical trials needs to be reassessed, and intervention studies are required to determine the best methodology to alter physician reluctance to pursue clinical trials.

Attitude of Health Personnel↗
PubMed1988

Epidemiology of premenstrual symptoms in a nonclinical sample. I. Prevalence, natural history and help-seeking behavior.

A stratified sample of 996 nursing school graduates from 1963 to 1984 was surveyed by mail regarding menstrual cycle characteristics. The 730 respondents reported an 87% overall lifetime prevalence of premenstrual symptoms. When the symptoms were categorized according to severity, only 3.2% of the respondents reported severe symptoms. Symptomatic women used diet change (24.6%), exercise (41.8%) and vitamins (18.9%) as self-help measures. Seventeen percent sought advice from a physician. Drug use was common; 22% were using a drug for symptoms at the time of the survey. Despite the common use of treatment, few women reported a significant work impairment. These findings support the conclusion that premenstrual symptoms are common but do not usually interfere with functioning.

Adult↗
PubMed1986

Ultrasound characterization of acute myocardial ischemia by quantitative texture analysis.

In this study we tested the efficacy of quantitative texture analysis in the identification of acute myocardial ischemia using an ultrasound data acquisition system that digitizes and stores echocardiographic data in polar format. In nine closed-chest dogs, data were acquired before and after coronary occlusion using a 2.4 MHz echocardiographic system. Regions of interest were analyzed at end-diastole and end-systole from the ischemic area and normal area at the same depth of field. Ultrasound data were evaluated using previously reported quantitative gray level texture measures. After occlusion, texture changes indicative of ischemia were found in systolic images. The directional component of the data analysis was important; analysis in the azimuthal direction was more accurate than in the axial direction. Six texture measures exhibited significant changes in the ischemic region from control to occlusion when analyzing data in the azimuthal direction. One false positive result occurred (significant texture change in the normal region from control to occlusion) in the azimuthal direction. Several false positive alterations in the normal regions from control to occlusion were found when the texture was evaluated in the axial direction. For accurate assessment of ischemic changes, preocclusion image data were required. We conclude that quantitative echocardiographic texture analysis using polar format data can identify subtle changes in myocardial texture such as that due to acute ischemia, using data acquired through the chest wall.

Acute Disease↗
PubMed1986

Sample size for case-control studies using Cochran's statistic.

Sample size determination for case-control studies of chronic disease are often based on the simple 2 X 2 tabular cross-classification of exposure and disease, thereby ignoring stratification which may be considered in the analysis. One consequence of this approach is that the sample size may be inadequate to attain a specified power and size when performing a statistical analysis on J 2 X 2 tables using Cochran's (1954, Biometrics 10, 417-451) statistic or the Mantel-Haenszel (1959, Journal of the National Cancer Institute 22, 719-748) statistic. A sample size formula is derived from Cochran's statistic and it is compared with the corresponding one derived when the data are treated as unstratified, and also with two other formulas proposed for stratified data analysis. The formula developed yields values slightly higher than one recently proposed by Muñoz and Rosner (1984, Biometrics 40, 995-1004), which assumes that both margins of each 2 X 2 table are fixed, while the present study considers only the case-control margin to be fixed.

Biometry↗
PubMed1985

Clinical and biologic antecedents of the amenorrhea/hyperprolactinemia syndrome: a case-control study.

Clinical, reproductive, and biologic antecedents of women with the amenorrhea/hyperprolactinemia (A/H) syndrome, most with pituitary prolactinomas, and matched healthy subjects were examined in a case-control study. Women with A/H had more frequent irregularity in early menstrual cycle patterns and excess facial hair, had less frequent catamenial symptoms, and were heavier at the time of study when compared with control subjects. The patients reported a more frequent history of thyroid disease and chest trauma. There were no significant differences between the patients and control subjects with respect to prior use of oral contraceptives, estrogens, psychotropic drugs, alcohol, or other substances known to alter serum prolactin levels, nor were there significant differences in the family history of gynecologic conditions or malignancies or the syndromes of multiple endocrine neoplasia. The implications of these findings are discussed.

Adenoma↗
PubMed1985

Drinking water and cancer incidence in Iowa. III. Association of cancer with indices of contamination.

With data from the Iowa Cancer Registry, age-adjusted sex-specific cancer incidence rates for the years 1969-1981 were determined for towns with a population of 1,000-10,000 and a public water supply from a single stable ground source. These rates were related to levels of volatile organic compounds and metals found in the finished drinking water of these towns in the spring of 1979. Results showed association between 1,2 dichloroethane and cancers of the colon and rectum and between nickel and cancers of the bladder and lung. The effects were most clearly seen in males. These associations were independent of other water quality and treatment variables and were not explained by occupational or other sociodemographic features including smoking. Because of the low levels of the metals and organics, the authors suggest that they are not causal factors, but rather indicators of possible anthropogenic contamination of other types. The data suggest that water quality variables other than chlorination and trihalomethanes deserve further consideration as to their role in the development of human cancer.

Adolescent↗
PubMed1985

Two-dimensional echocardiographic image texture analysis: reduction of regional variability using polar coordinates.

Factors inherent to the ultrasound imaging system can influence quantitative ultrasound image texture and may produce changes that mask or mimic those due to alterations in tissue structure. In this study, we assessed the effect of the method of image data acquisition and analysis on the variations in quantitative texture measures that occurred solely due to the position of a region of interest (ROI) within the field of view. When ROI's, which varied in range and azimuth within the image of a tissue equivalent phantom (of uniform composition), were assessed by conventional analysis of scan-converted (rectangular coordinate) data, over 50 percent of all texture measures showed significant differences. Pseudo polar analysis reduced the number of texture measures showing regional variation by 80 percent (p less than 0.01) and true polar coordinate data analysis reduced the number by 74 percent (p less than 0.01). True polar analysis completely abolished differences in texture measures between ROI's separated in azimuth. Acquisition and analysis of tissue texture data using polar coordinates should allow a more definitive identification of abnormal tissue.

Echocardiography↗
PubMed1984

Prehospital defibrillation performed by emergency medical technicians in rural communities.

Survival after out-of-hospital cardiac arrest is poor in communities served only by basic ambulance services, but conventional advanced prehospital care is not an option for most rural communities. Ambulance technicians in 18 small communities (average population, 10,400) were trained to recognize and defibrillate ventricular fibrillation. Neither endotracheal intubation nor medication was used. Twelve additional communities of similar size where such early defibrillation was not attempted provided control data. In the communities where early defibrillation was available, 12 of 64 patients (19 per cent) who were found in ventricular fibrillation were resuscitated and discharged alive from the hospital; this was true of only 1 of 31 such patients (3 per cent) in the control communities, where only basic life support was available (P less than 0.05). Ten (83 per cent) of the long-term survivors received electrical shocks administered solely by the technicians. Early defibrillation by minimally trained ambulance technicians is an effective approach to emergency cardiac care in rural communities.

Adolescent↗
PubMed1983

Quantitative texture analysis in two-dimensional echocardiography: application to the diagnosis of experimental myocardial contusion.

We postulated that the analysis of regional image texture in two-dimensional (2D) echocardiograms would be an accurate method to differentiate normal from abnormal myocardial structure. We tested this hypothesis with quantitative texture measures to study the regional, spatial distribution of echo amplitudes in 2D echocardiograms performed before and immediately after blunt left chest trauma was induced in six anesthetized dogs. After trauma the contused region of myocardium appeared brighter and exhibited an altered myocardial texture. By use of a set quantitative texture measures, we found no significant differences in pretrauma images when normal regions were compared with regions to be contused. Also, we found no difference when we compared the normal regions in each animal in pretrauma vs posttrauma images. Twelve measures, however, differentiated normal from contused regions within the posttrauma images (p values ranged from .0057 to .0001 by multivariate analysis of variance). These texture measures were capable of differentiating normal from abnormal tissue only when texture along the azimuthal (lateral) direction was calculated. We conclude that regions of myocardial contusion exhibit visibly altered local echo-amplitude patterns (altered image texture) and that these image texture alterations may be quantified with digital image analysis techniques. These findings suggest that quantitative texture calculations may be a useful approach to ultrasound tissue characterization.

Animals↗
PubMed1983

Range- and azimuth-dependent variability of image texture in two-dimensional echocardiograms.

Regional two-dimensional (2D) echocardiographic amplitude patterns, or image texture, may be of diagnostic importance. Echocardiographic image texture is due in part to acoustic speckle, a complex pattern of interference of reflections from many small scatterers in tissue. The regional speckle pattern appears to be altered in several disorders associated with abnormalities in myocardial structure but also may be altered by a variety of characteristics of the scanning instrument. We hypothesized that quantitative measures of regional 2D echocardiographic image texture would vary as a function of position in range and azimuth within the field of view, even when imaging a uniform ensemble of scatterers. We tested this hypothesis by imaging a tissue-equivalent phantom with two phased-array scanners and two different methods of digitization. We analyzed the texture in several regions of interest separated in range and azimuth and found significant differences in quantitative texture measures as a function of position of the region of interest in the sector field of view (p values .006 to .0001 by multivariate analysis of variance). We found significant regional variability in texture with both scanners and both methods of digitization. We conclude that regional quantitative image texture in 2D echocardiograms varies as a function of range and azimuth, even when imaging a uniform ensemble of scatterers. This variability is related to several physical and instrument-related phenomena and precludes interpreting all regional texture alterations as indicating tissue structural abnormalities.

Echocardiography↗
PubMed1982

Drinking water and cancer incidence in Iowa. I. Trends and incidence by source of drinking water and size of municipality.

Age-adjusted, sex-specific cancer incidence rates for the years 1969-1978 were determined for municipalities in Iowa having a population of 1000 or over and public water supply that had remained stable for a minimum of 14 years. The incidence rates for the municipalities were examined according to major source of water supply (surface or ground) and depth of well. As municipality size increased, incidence rates increased for cancer of the lung among males and females. A slight gradient of increasing cancer incidence was seen for cancer of the bladder among males and females. When stratified for population size, incidence rates for cancers of the lung and rectum among males and females were higher for municipalities on surface water compared with those on ground sources. Incidence rates for cancer of the prostate rose as well depth increased, while a trend was seen toward decreasing incidence rates for cancer of the colon among females as well depth increased. When time trends were examined, an increase in cancer rates over time was seen for several cancer sites, with the increase most noticeable in municipalities supplied by surface water or shallow wells. These results are not always consistent with the hypothesis of an association between cancer and chlorinated water.

Epidemiologic Methods↗
PubMed1982

Drinking water and cancer incidence in Iowa. II. Radioactivity in drinking water.

Iowa towns of 1000-10,000 population, whose water came solely from wells of over 500 feet (152 meters) in depth and was not treated by a process that would remove radioactivity, were identified. Age-adjusted, sex-specific, cancer incidence rates were determined for these towns for the years 1969-1978 (excluding 1972) and related to the mean level of radium-226 in the municipal water supply. Incidence rates of cancers of the lung and bladder among males and of cancers of the breast and lung among females were higher in towns with a radium-226 level in the water supply exceeding 5.0 pCi/l. A gradient of increasing cancer incidence associated with rising radioactivity level for three time periods was also seen for lung cancer among males. The associations between cancer incidence and radioactivity of water supply could not be explained by smoking patterns, water treatment factors, other water quality measurements, or known socio-demographic features.

Aged↗
PubMed1982

A case-control study of breast cancer and psychotropic drug use.

The relative risk of breast cancer incidence and tumor promotion associated with psychotropic drug consumption was evaluated in 151 patients with newly diagnosed neoplasms and 151 hospital controls. No significantly altered risk of breast cancer was found in association with the use of diazepam, chlordiazepoxide, antidepressants, major tranquillizers, sedatives or hypnotics, even after adjustment for known menstrual and reproductive risk factors. No substantial evidence of tumor promotion effects was found, as measured by altered age-at-onset of disease or altered clinical stage at presentation. Psychotropic drug use was inversely related to subject ponderosity (measured by the Quetelet Index) and while this did not confound risk estimates, it may be important in exploring biologic hypotheses of psychotropic drug use and breast cancer.

Aged↗
PubMed1982

Cyclic ovarian function and breast cancer.

We postulated previously that systematic differences in menstrual cycle length and/or variability might be used as indicators of underlying hormonal abnormalities that could help explain the endocrine biology of some breast cancer risk factors. In the present study, we prospectively and retrospectively analyzed menstrual cycle patterns in breast cancer cases and controls in two populations. No significant differences were found. This and previous studies emphasize that contemporary women have a long reproductive experience characterized by uninterrupted, regular menses, which is a condition of maximum ovulation potential and which contributes to estrogen stimulation over time.

Adolescent↗
PubMed1981

The relationship of menopausal hot flushes to medical and reproductive experience.

Information regarding the relationship of menopausal hot flushes to menstrual, reproductive and clinical events were obtained from women participating in a case-control study of breast cancer risk. Naturally menopausal women who reported the occurrence of menopausal hot flushes were compared with those without such complaints in an attempt to identify factors that might predict the occurrence of menopausal symptoms. Two-thirds of the women reported such symptoms. The symptomatic and asymptomatic groups did not differ in body weight, suggesting that extraglandular estrogen production in obese women does not protect against occurrence of menopausal symptoms. Neither past medical nor reproductive history were predictive of the occurrence of hot flushes. Women with hot flushes more commonly reported the occurrence of menstrual cycle variability and of long menstrual cycles during the 5 years before menopause. Since perimenopausal cycle variability probably reflects the irregular maturation of residual ovarian follicles accompanied by elevated gonadotropin concentrations, symptomatic women may have earlier activation of the neuroendocrine mechanism that has been associated with both pulsatile gonadotropin release and the hot flush.

Adolescent↗