Roaming through methodology. X. The testing of diagnostic procedures

In this era of evidence-based medicine, diagnostic tests cannot escape close scrutiny of their effectiveness. Sensitivity and specificity have up till now played a central role in the evaluation of diagnostic tests. These terms are not without their shortcomings when it comes to the characterisation of a test's true worth for patients. Randomised clinical trials are increasingly used for evaluation of medical tests and outlining of strategy. The indirect relationship between test results and health outcome creates additional challenges for designers of such trials.     

Understanding the needs of children following large-scale disasters and the role of government

No one who experiences a disaster is untouched by it. Children and their families are often among the most affected. This article explains how mental health and medical professionals can assist families and communities in dealing with common disaster-related stress reactions in children. An overview of disaster research and examples of special concerns about children are given. In addition, an overview of the role of local, state, and federal governments, as well as other organizations, is provided.     

Stromal progesterone receptors mediate the inhibitory effects of progesterone on estrogen-induced uterine epithelial cell deoxyribonucleic acid synthesis

The role of epithelial and stromal progesterone (P) receptors (PR) in the regulation of uterine epithelial DNA synthesis by P was investigated by analyzing the four types of tissue recombinants prepared with uterine stroma (S) and epithelium (E) from wild-type (wt) and PR knockout (PRKO) mice: wt-S + wt-E, PRKO-S + PRKO-E, wt-S + PRKO-E, and PRKO-S + wt-E. 17-Beta estradiol (E2) stimulated DNA synthesis in all four types of tissue recombinants. On the other hand, P inhibited E2-induced DNA synthesis only in tissue recombinants prepared with wild-type (PR-positive) stroma (wt-S + wt-E or wt-S + PRKO-E) but not knockout (PR-negative) stroma (PRKO-S + wt-E or PRKO-S + PRKO-E). These results clearly demonstrate that the inhibitory effect of P on uterine epithelial DNA synthesis is mediated by stromal PR. Epithelial PR is neither necessary nor sufficient for P inhibition of E2-induced epithelial DNA synthesis.     

Stability of posterior spinal instrumentation and its effects on adjacent motion segments in the lumbosacral spine

STUDY DESIGN: An in vitro biomechanical analysis of three anterior instability patterns was performed using calf lumbosacral spines. Stiffness of the constructs was compared, and segmental motion analyses were performed. OBJECTIVES: To clarify the factors that alter the stability of the spinal instrumentation and to evaluate the influence of instrumentation on the residual intact motion segments. SUMMARY OF BACKGROUND DATA: Recently, many adverse effects have been reported in fusion augmented with rigid instrumentation. Only few reports are available regarding biomechanical effects of stability provided by spinal instrumentation and its effects on residual adjacent motion segments in the lumbar-lumbosacral spine. METHODS: Eighteen calf lumbosacral spine specimens were divided into three groups according to instability patterns--one-level, two-level, and three-level disc dissections. Six constructs were cyclically tested in rotation, flexion-extension, and lateral bending of intact spines, of destabilized spine, and of spines with four segmental posterior instrumentation systems used to extend the levels of instability (Cotrel-Dubousset compression hook and three transpedicular screw fixation systems). During each test, stiffness values and segmental displacements were measured. RESULTS: The rigidity of the instrumented construct increased as the fixation range became more extensive. Although application of the instrumentation effectively reduced the segmental motion of the destabilized vertebral level, the motion at the destabilized level tended to increase as the number of unstable vertebral levels increased, and the fixation range of the instrumentation became more extensive. Instrumented constructs produced higher segmental displacement values at the upper residual intact motion segment when compared with those of the intact spine. In contrast, the instrumented constructs decreased their segmental displacement values at the lower residual intact motion segment with higher magnitude of the translational (shear) motion taking place compared with the intact spine in flexion-extension and lateral bending. These changes in the motion pattern became more distinct as the fixation range became more extensive. CONCLUSIONS: As segmental spinal instrumentation progresses from one level to three levels, the overall torsional and flexural rigidity of the system increases. However, segmental displacement at the site of simulated instability becomes more obvious. Application of segmental instrumentation changes the motion pattern of the residual intact motion segments, and the changes in the motion pattern become more distinct as the fixation range becomes more extensive and as the rigidity of the construct increases.     

Relationship between lead mining and blood lead levels in children

The authors studied blood lead levels of 226 randomly selected children, aged 6-92 mo, who lived in either a lead-mining area or a nonmining area, and 69 controls. The authors sought to determine to what extent mining activities contributed to blood lead levels in the children. The mean blood lead levels in the study and control groups were 6.52 microg/dl and 3.43 microg/dl, respectively. The corresponding proportions of children with elevated blood lead levels were 17% and 3%. Soil and dust lead levels were up to 10 times higher in the study than the control group. Elevated blood lead levels appeared to result from exposure to both lead-mining waste and lead-based paint. Mining waste was the cause of the higher prevalence of elevated blood lead levels in these children.     

Cardiovascular events and mortality in newly and chronically depressed persons > 70 years of age

The role of duration of depressed mood in the prediction of cardiovascular disease (CVD) requires further study, as it has been suggested that emerging depressive symptoms may be a better predictor than persistent depressive symptoms. This prospective cohort study of 3,701 men and women aged > 70 years uses 3 measurement occasions of depressive symptomatology (Center for Epidemiologic Studies-Depression Scale) during a 6-year period to distinguish persons who were newly (depressed at baseline but not at 3 and 6 years before baseline) and chronically depressed (depressed at baseline and at 3 or 6 years before baseline). Their risk of subsequent CVD events and all-cause mortality was compared with that of subjects who were never depressed during the 6-year period. Outcome events were based on death certificates and Medicare hospitalization records. During a median follow-up of 4.0 years, there were 732 deaths (46.2/1,000 person-years) and 933 new CVD events (64.7/1,000 person-years). In men, but not in women, newly depressed mood was associated with an increased risk of CVD mortality (relative risk 1.75, 95% confidence interval [CI] 1.00 to 3.05), new CVD events (relative risk 2.07, 95% CI 1.44 to 2.96), and new coronary heart disease events (relative risk 2.03, 95% CI 1.28 to 3.24) after adjustment for traditional CVD risk factors. The association between newly depressed mood and all-cause mortality was smaller (relative risk 1.40, 95% CI 0.95 to 2.07). Chronic depressed mood was not associated with new CVD events or all-cause mortality. Our findings suggest that newly depressed older men, but not women, were approximately twice as likely to have a CVD event than those who were never depressed. In men, recent onset of depressed mood is a better predictor of CVD than long-term depressed mood.     

Acute knee injuries: Part I. History and physical examination

A thorough history and physical examination are helpful in the diagnosis of meniscal damage, cruciate and collateral ligament sprains and patellar instability, the four major acute knee injuries. When performing a physical examination in a patient with a knee injury, the uninjured knee should always be assessed first and used for comparison. Examination includes passive and active range-of-motion testing, palpation of the joint line spaces, and a variety of maneuvers to evaluate knee stability. Valgus and varus testing provides assessment of the collateral ligaments. The Lachman and pivot shift tests are useful in the evaluation of the anterior cruciate ligament. The posterior drawer and tibial sag tests are used to evaluate the posterior cruciate ligament. The bounce test, McMurray's test and Apley's grind test can aid in the diagnosis of meniscal injury.     

Application of a mechanistic model of bovine milk protein synthesis to examine the use of isotope labeling methods

Two types of models of bovine milk protein synthesis were used to simulate collection and analysis of data from infusion experiments involving isotope-labeled amino acids (AA). Analytical solutions to a system of ordinary differential equations that describe isotope enrichment curves of each AA pool within the mammary gland were derived and are presented. Numerical solutions from a dynamic mechanistic model suggest that normal experimental procedures can affect the shape of enrichment curves and, therefore, results derived from them. Simulation results suggest that standard methods utilizing in vivo isotope kinetics may be of limited value to characterize the metabolism of the bovine mammary gland, especially AA metabolism and milk protein synthesis and secretion. The results clearly demonstrate the flexibility of such models for the testing of many hypotheses and possible experimental protocols.