Decomposing Area of Residence Differences in Multiple Regression Studies: The Relative Contributions of Independent Variables and Model Coefficients

When rural/urban differences are found in health status or health care use, it is often desirable to identify those factors (such as age, social structure, income, etc.) that influence such differences. To this end, researchers often test rural/urban differences in age, social structure, income, etc., for statistical significance. Also, researchers commonly perform multivariate analyses (such as multiple regressions) to examine rural-urban differences in the influence of various independent variables on the dependent variable of interest. Frequently, researchers discover: (1) statistically significant rural/urban differences in the independent variables (such as age, social structure, income, etc.) and (2) statistically significant rural/urban differences in the effects of these independent variables (i.e., statistically significant rural/urban differences in regression coefficients). The analysis typically stops here, without addressing the relative contributions of (1) and (2) to the rural/urban differences in the dependent variable. This paper argues that the relative contributions of (1) and (2) have important implications for the way policy-makers address rural health problems. This paper presents a method for assessing the relative contributions of differences in the independent variables and differences in regression coefficients to observed differences in the dependent variable, and illustrates the application of the method by analyzing rural/urban differences in the risk of institutionalization.     

Trauma: a systematic approach to management

Initial care of the trauma victim begins at the scene of the accident, where the "load and go" principle is applied. A systematic approach to management of the trauma victim improves patient outcome. After insertion of an airway and stabilization of the spine, hemorrhage is treated and volume is replaced. At this point, invasive techniques, such as chest tube insertion, peritoneal lavage and pericardiocentesis, may be therapeutic as well as diagnostic.     

Improving the management of bladder cancer with fluorescence cystoscopy.

Endoscopic visualization (cystoscopy) and transurethral resection are effective, well-tolerated diagnostic and treatment techniques for bladder cancer. However, it is widely recognized that cystoscopy can miss biologically important lesions, such as carcinoma in situ. Attempts to improve the effectiveness of cystoscopy are not new, but initial methods were impractical and had limited efficacy. Fluorescence cystoscopy became feasible with the discovery that intravesical administration of aminolevulinic acid (ALA) made bladder cancers fluoresce when exposed to blue light. More recently, the creation of a hexyl ester of ALA (HAL) made this technique practical, because HAL significantly shortens the amount of time needed for drug exposure prior to cystoscopy. Not surprisingly, studies have shown that fluorescence cystoscopy can reveal carcinoma in situ that is visually occult under conventional (white-light) cystoscopy. An unexpected finding was that fluorescence cystoscopy also enhanced the detection of papillary tumors. Studies with ALA have shown that resection of bladder cancer with fluorescence results in improved disease-free survival compared to conventional resection under white light. This report summarizes some of the recent studies of fluorescence cystoscopy in bladder cancer.     

Effects of CD8 depletion on retinal soluble antigen induced experimental autoimmune uveoretinitis.

During the later stages of soluble-antigen (sAg)-induced experimental autoimmune uveoretinitis (EAU), an increase in the relative number of CD8+ lymphocytes has been observed at the site of inflammation in the retina. It has been suggested that these late-appearing CD8+ cells might down-regulate this acute disease process. To determine the role of the CD8+ cells in EAU, Lewis rats were depleted of CD8+ cells prior to and during disease and the enucleated eyes examined histologically. The spleen cells from CD8-depleted rats were also examined for their ability to respond to concanavalin A (Con A) and to allogeneic targets as determined by mixed lymphocyte reaction (MLR) and cytotoxicity assays. The results suggest that depleting CD8+ cells had no effect on the course of disease and that CD8+ cells do not play a crucial role in the immunoregulation of EAU.     

大鼠胸腺降黑素受体的鉴定及生物学特性

应用放射配体结合法证实大鼠胸腺内存在降黑素特异结合部位，该结合位点可以满足特异结合部位的基本条件：１．低结合容量；２．高亲和力；３．可饱和性；４．可逆性；５．对降黑素高度特异性。此外，该特异结合位点具昼夜节律；亚细胞分布的研究表明以细胞核含量最高，线粒体次之，并具有年龄依赖性降低，以出生时最高。     

Stainable hepatic iron in 341 African American adults at coroner/medical examiner autopsy

Background  

Results of previous autopsy studies indicate that increased hepatic iron stores or hepatic iron overload is common in African Americans dying in hospitals, but there are no reports of hepatic iron content in other cohorts of African Americans.     

Macrophage migration inhibitory factor (MIF) gene polymorphism is associated with susceptibility to but not severity of inflammatory polyarthritis

The aim of the study was to investigate whether polymorphisms of macrophage migration inhibitory factor (MIF) determine susceptibility to or severity of inflammatory polyarthritis (IP). Genotypes for a single-nucleotide polymorphism (MIF-173*G/C) and a tetranucleotide (CATT)(n) repeat mapping to the promoter region of the MIF gene were compared between UK Caucasian IP cases (n=438) and controls (n=343). Both polymorphisms were also investigated for association with features of disease activity and severity at baseline and by 5 years. The MIF-173*C allele (OR 1.7, 95% CI 1.3-2.4, P=1.8 x 10(-4)) and the CATT(7) allele (OR 1.5, 95% CI 1.0-2.1, P=0.02) were found to be associated with increased susceptibility to IP. Furthermore, presence of the haplotype containing both associated polymorphisms was associated with a three-fold increase risk of developing IP. No association with disease severity or activity either at baseline or by 5 years was detected for either of the promoter polymorphisms studied. In conclusion, MIF is a susceptibility gene for the development of IP. The same alleles previously reported to be associated with susceptibility to juvenile idiopathic arthritis account for the increased risk. The promoter polymorphisms of MIF, investigated in this study, do not influence the severity of disease outcome by 5 years.     

The use of Teflon-embedded calcium sulphate: dysprosium thermoluminescent dosimeters for chest radiography

As part of a U.S. multi-regional pilot study conducted by the six Centers for Radiological Physics, 12-mm-diameter by 0.4-mm-thick CaSO4:Dy Teflon-embedded discs were evaluated and used to measure patient entrance exposure on 60 "average" patients at 12 clinical centers. The discs were found to have adequate sensitivity, reproducibility and linearity up to 69.7 microC kg-1 (270 mR). The minimum measurable exposure was estimated as 0.4 microC kg-1 (1.5 mR). All responses were corrected for energy dependence, which varied +/- 20% from 1.7 to 6.5 mm Al half-value layer. Patient entrance exposure values ranged from 1.3 to 28 microC kg-1 (5 to 110 mR), with a median value of 5.2 microC kg-1 (20 mR). This value agreed with exposure measurements made on the chest radiography equipment using an ionization chamber and a phantom which simulated an "average" patient, and with published Nationwide Evaluation of X-Ray Trends (NEXT) data for the same period.     

Measuring severity of behavior: a revision of Part II of the Adaptive Behavior Scale

This study was designed to: (a) assess the degree to which rehabilitation staff rate the severity of maladaptive behaviors on Part II of the AAMD Adaptive Behavior Scale (ABS) and, on the basis of the obtained rating, (b) develop a socially validated revision of the scoring system to allow more accurate classification of mentally retarded individuals as having mild, moderate, or severe behavior problems. On the basis of the modal ratings obtained from various service agencies for "occasionally" and "frequently" on Part II of the ABS, we constructed a revised scoring system. Preliminary use of the scoring system suggests satisfactory agreement between "severity profile" scores and subjective ratings of individuals classified by service agencies as demonstrating mild, moderate, or severe behavior problems.