Search PubMed⌕ Search

Biomedical subjects

J A Stein

Publications and source records attributed to J A Stein.

At least 19 recordsLinked to original sources
PubMed1992

Structural equation models in medical research.

Structural equation modelling (SEM) is a modern statistical method that allows one to evaluate causal hypotheses on a set of intercorrelated nonexperimental data. The sample variances and covariances, and possibly the means, are compared to those predicted by a theory-based hypothetical model after optimal estimation of the parameters of the model. The goodness-of-fit of the empirical data to the hypothesized model is evaluated statistically. This review describes the underlying statistical theory and rationale of SEM. Both confirmatory factor analysis and latent variable path models are discussed. The applicability of SEM to assessment of reliability and validity is noted. A detailed example is provided, and several examples from the medical literature are briefly reviewed. Cautions regarding the possible misuse or misinterpretation of the technique are also mentioned. Possible future directions for the use of SEM in medical research are suggested. Two appendices provide more technical details.

Factor Analysis, Statistical↗
PubMed1992

Mammography usage and the health belief model.

Regular screening mammograms for asymptomatic women are the most effective method for early detection of breast cancer. This study assessed the relative influence of Health Belief Model (HBM) constructs on prior mammography usage and the intention to obtain mammograms with data from a sample of 1,057 women over the age of 35 years residing in an urban community in the United States. Covariance structure analysis with latent variables was used initially to perform a confirmatory factor analysis of indicators of Socioeconomic Status (SES), Perceived Susceptibility, Perceived Barriers, Perceived Benefits, Cues to Action, Prior Mammography, and Future Intentions. Once a plausible factor structure was confirmed, a predictive path model was tested with Future Intentions and Prior Mammography as the outcome variables. Cues to Action, operationalized as a physician influence variable, particularly impacted Prior Mammography, and Perceived Susceptibility was the most powerful predictor of Future Intentions. SES only related significantly to Perceived Barriers, and Cues to Action, and did not directly influence Prior Mammography and Future Intentions. HBM predictor variables alone accounted for the relationship between previous mammography experience and intentions to obtain mammograms in the future. Health education implications and an applied outreach program are discussed.

Adult↗
PubMed1991

Operational aspects of terminating randomization in the Multicenter Trial of Cryotherapy for Retinopathy of Prematurity. Cryotherapy for Retinopathy of Prematurity Cooperative Group.

The Multicenter Trial of Cryotherapy for Retinopathy of Prematurity (CRYO-ROP) is a randomized clinical trial sponsored by the National Eye Institute (NEI) designed to test whether cryotherapy applied to eyes of premature infants with a specified extent of stage 3+ ROP significantly decreases the incidence of an unfavorable outcome. An unfavorable outcome is defined as either retinal detachment or a retinal fold and was determined at 3 months posttreatment by the use of a masked photographic system. Enrollment into the trial was terminated on recommendation of the Data and Safety Monitoring Committee 9 months before the scheduled closing date for enrollment because of demonstrated treatment benefit. The purpose of this article is to discuss the operations involved in the orderly termination of enrollment and dissemination of results from this trial. These activities included preparation of trial participants and staff, release of trial information, continuing patient care, data collection and coding, and publication of trial results.

Blindness↗
PubMed1991

The effect of physician-patient communication on mammography utilization by different ethnic groups.

The differential utilization of screening mammography by racial/ethnic groups was examined through 35-minute bilingual, random digit dialed telephone interviews with 1,057 women over age 35 years. Results showed that 71% of hispanic women had never had a mammogram and that only 27% over age 50 years had had one in the year before the survey. White and black women over the age of 50 years were being screened more frequently with 34% of white women and 36% of black women having had a mammogram in the prior year. More than half of the hispanic women over age 50 years had never had a mammogram. Analyses showed that the most important variable that predicted whether women of all racial groups had a mammogram, at any time or within the last year, was whether their doctors had discussed mammography with them. The discussion did not need to be lengthy or complex. Hispanic women, however, were less likely to have physicians who discussed screening with them even though these women reported that they were just as motivated as other women to get a mammogram if their doctor referred them. Suggestions for what primary care physicians can do to increase mammography rates, especially among hispanic women, are discussed.

Adult↗
PubMed1991

Repeated sexual victimization.

Patterns of repeated victimization were investigated in a large community-based survey about sexual assault. Multiple victimization was common: of the 433 sexually assaulted respondents, two-thirds reported more than one incident; the average number of incidents per person was 3.2. Single- and multiple-incident victims of sexual assault did not differ on a wide range of variables including demographics, mental disorders, and general functioning (e.g., suicide attempts, family violence). Thus, once an initial victimization occurred, personal characteristics of the victim were not related to risk for subsequent sexual assault. Additional research which obtains more specific information on each event is needed to strengthen confidence in these findings. Considerations for research on multiple victimization are discussed. Further research may benefit from exploring contextual factors and using longitudinal research methods.

Adaptation, Psychological↗
PubMed1991

The influence of ethnicity, socioeconomic status, and psychological barriers on use of mammography.

This study assessed the relative influence of psychological barriers, SES, and ethnic differences in mammography use for a community sample of 586 White, 227 Black, and 150 Hispanic women. Confirmatory factor analyses with latent variables indicated plausible factor structures for all groups on items related to barriers to mammography. Summed indicators of SES, fear of radiation, embarrassment, pain, anxiety, and cost concerns were correlated significantly with mammography use for the pooled group. Separate analyses by ethnicity indicated a substantial relationship between mammography use and cost concerns by White and Black women, and fear of pain by Black and Hispanic women. Use of mammography was associated more highly with SES among Hispanic women. Pooled logistic regression analyses controlling for SES and ethnicity showed that the psychological barriers, especially concern about cost, remained important independent predictors of mammography use. We explore sociocultural explanations for less mammography use by Hispanic women, especially those less acculturated.

Black or African American↗
PubMed1991

Evaluation of a new bladder tumor marker.

Two monoclonal antibodies have been developed that bind to a shed bladder tumor-associated antigen. Preliminary data have demonstrated that antigen-positive tumors shed detectable amounts of antigen in the urine while antigen-negative tumors do not. This antigen may be differentially metabolized by normal and malignant urothelial cells. Further characterization of this antigen and its evaluation as a urinary marker for antigen positive bladder cancers is continuing.

Antibodies, Monoclonal↗
PubMed1991

The impact of physician compliance on screening mammography for older women.

Screening mammography is underutilized, even for women older than 50 years for whom there is a general consensus that regular annual screening is appropriate and necessary. To evaluate reasons for this underutilization, we studied a random sample of 517 women in Los Angeles, Calif who were older than 50 years. All women were found to be underscreened, especially women older than 65 years. For example, approximately 35% of women 50 to 64 years old and 47% of women aged 65 years and older never had had even one mammogram. Analyses revealed that the most important factor that predicted whether a women ever had had a mammogram was whether her physician had talked to her about mammography. Women were between four and 12 times more likely, depending on their age group, to have had a mammogram at some time if their physicians discussed it with them. The discussions did not need to be lengthy or complex. These results indicate that physicians need to know that discussing screening mammography with their patients has a major impact on breast cancer screening behaviors.

Breast Neoplasms↗
PubMed1990

Comparison of antigen expression on normal urothelial cells in tissue section and tissue culture.

Antigenic characterization of urothelial cells cultured from normal adult ureter was performed. These cells were cultured using a simplified isolation and culture technique and a commercially available serum-free medium. The cells growing in these cultures had epithelioid morphology and normal quantities of DNA. The antigen expression on these cultured normal urothelial cells was evaluated using a panel of monoclonal antibodies: 5G6.4, AN43, URO-5, anti-keratin and anti-blood group antibodies, and 425 (anti-epidermal growth factor receptor). Lower levels of anti-A and AN43 binding on cultured cells were observed than are seen on urothelial cells in sections of normal ureter, while the binding of anti-blood group H, 5G6.4, and URO-5 was unchanged. Binding of anti-epidermal growth factor receptor antibody 425 was improved if the cells were grown in medium lacking epidermal growth factor. These results confirm the urothelial origin of these cultured urothelial cells but indicate that some antigenic differences between cultured normal urothelial cells and urothelial cells in situ in the normal ureter exist.

ABO Blood-Group System↗
PubMed1990

Dual-energy radiographic absorptiometry of the lumbar spine: clinical experience with two different systems.

Dual-energy radiographic absorptiometry (DRA) of the lumbar spine was performed in 222 subjects (aged 17-92 years) of both sexes with use of two different systems. In a sub-group of 21 patients, results were compared with those obtained by means of dual-photon absorptiometry (DPA) of the lumbar spine. There was a high correlation among the results obtained with three instruments (r = .9, P less than .0001), and interconversion factors were calculated. Data conversion based on these regression equations may be useful for comparing results from one laboratory to another.

Absorptiometry, Photon↗
PubMed1989

Identification by monoclonal antibodies of an antigen shed by human bladder cancer cells.

The reactivities of two anti-bladder cancer monoclonal antibodies, AN43 and BB369, were characterized. AN43 and BB369 reacted with a majority (greater than 50%) of bladder cancer tissue sections tested by immunoperoxidase staining. When tested against a panel of 27 normal human tissues, AN43 and BB369 reacted only with urothelium and stomach. AN43 and BB369 showed identical binding patterns and competed for binding on bladder cancer cells, suggesting that the two antibodies react with identical or spatially close epitopes. Bound BB369 antibody was rapidly shed from the surface of viable UM-UC-9 human bladder cancer cells. The antigen was found in spent tissue culture medium from the UM-UC-9 human bladder cancer cell line. AN43 and BB369 define a shed bladder tumor-associated antigen with limited distribution on normal tissues. The antigen is different from bladder tumor-associated antigens defined by other monoclonal antibodies and may be useful for the diagnosis and follow-up of patients with bladder cancer.

Antibodies, Monoclonal↗
PubMed1989

CO2 laser stapedotomy.

This clinical study was preceded by two laboratory experiments. The first experiment compared temperature changes in the vestibule while vaporizing a 0.6-mm stapedotomy with Argon, KTP-532, and CO2 lasers. Data demonstrated that the CO2 laser possesses superior tissue characteristics for stapedotomy. In the second experiment safe energy parameters were established for various Sharplan CO2 laser models. Using these safe power settings, 153 consecutive CO2 laser stapedotomies were performed under local anesthesia. No patient experienced intraoperative dizziness during or immediately following the application of the CO2 laser to the stapes footplate. Long-term postoperative hearing results demonstrated that 87% of the patients maintained an air/bone gap to within 10 dB and 94% maintained an air/bone gap to within 15 dB (mean follow-up 32 months). No patient incurred a significant sensorineural hearing loss (greater than 10 dB) in the speech range. Four patients developed a perilymph fistula (three immediate and one delayed) and fluctuating sensorineural hearing loss, but all were successfully repaired without significant permanent nerve deafness. At 4,000 Hz, five patients lost 20 dB and two patients dropped 40 dB compared with preoperative levels. Postoperative complications included four perilymph fistulas, two prostheses displaced from the stapedotomy opening, one fixed prosthesis, and one fixed incus. Seven of eight of these complications were successfully revised. At the time of this writing, 6/153 patients have a persistent conductive hearing loss greater than 20 dB and have not been revised. Using appropriate energy parameters, the CO2 laser provides a safe, efficient microsurgical tool for performing stapedotomy simply and with minimum inner ear trauma.

Carbon Dioxide↗
PubMed1978

Serum lysozyme, serum proteins, and immunoglobulin determinations in nonspecific inflammatory bowel disease.

The serum levels of lysozyme, serum electrophoresis, and serum immunoglobulins were determined prospectively in 101 patients with ulcerative colitis, ulcerative proctitis, Crohn's disease, or nonclassifiable nonspecific inflammatory bowel disease. Although the mean serum lysozyme concentration of patients with Crohn's disease (10.5 +/- 6.8 microgram/ml) and ulcerative colitis (9.6 +/- 4.1 microgram/ml) performed by a standardized lysoplate method was significantly greater than normal controls (6.0 +/- 1.5 microgram/ml), the results did not correlate with the diagnosis nor with the degree of disease activity. Individually separated protein fractions and serum immunoglobulins also did not correlate with the serum lysozyme levels. This study indicates that measurement of the level of serum lysozyme in individual patients is not helpful in determining the cause or degree of activity of nonspecific inflammatory bowel disease.

Adult↗