The surgical importance of coronary sinus orifice atresia

Coronary sinus orifice atresia is rare. We describe two cases, one with an atrioventricular septal defect and another with supracardiac totally anomalous pulmonary venous drainage. The association with the latter has not been described previously. The importance of diagnosing the defect is emphasized and surgical treatment is discussed.     

Male-female performance on U.S. Air Force pilot selection tests

BACKGROUND: Recently, the U.S. Air Force conducted several studies to examine sex differences on pilot selection tests and training performance. METHODS: Research has focused on mean score performance, the structure of ability, the predictive utility of pilot selection tests, and the causal role of ability and prior flying knowledge in the acquisition of additional flying knowledge and flying skills. DISCUSSION: Despite male-female mean score differences on pilot selection tests, confirmatory factor analyses indicated that the same factors were being measured for both groups. In studies of predictive bias, no evidence of differential validity was found for male vs. female pilot trainees. An examination of causal models of ability and prior flying knowledge on the acquisition of additional flying knowledge and flying skills showed similar structure for men and women.     

Coronal fracture of the hamate body

Three patients presented with an acquired green discoloration of their scalp hair. History revealed that all of them swam regularly in private swimming pools. Examination of the hair by atomic emission spectroscopy showed that the green discoloration was caused by an excessively high copper content of the hair. This exogeneous discoloration is characteristically related to the uptake of copper from private swimming pools.     

Selective block in erythropoietin-induced differentiation of growth factor-independent retrovirally-infected TF-1 cells

The erythroleukaemic cell line TF-1, infected with either the pBabe neo retrovirus or the retrovirus bearing the human erythropoietin (hEpo) gene, developed three growth factor-independent clones. Erythropoietin (Epo), interleukin-3 (IL-3) and granulocyte-macrophage colony stimulating factor (GM-CSF) accelerated the proliferation of these clones. Autonomous growth of the clones was independent of Epo because it was not altered by Epo anti-sense oligonucleotides, nor was Epo detectable in culture supernatants. Cells from the mutant clones could not be induced by Epo to express glycophorin A and haemoglobin synthesis was markedly reduced. Haemin reversed the block in Epo-induced haemoglobin synthesis. Acquisition of growth factor-independence appears to be linked with the selective loss of differentiation capacity. These cells may provide a useful model for the study of the mechanisms involved in leukaemic transformation.     

Practical applications of chemical shift imaging

Methods of spectral localization are briefly reviewed and divided into two classes: those using phase encoding and those using frequency selective RF pulses in a constant gradient. A potentially troubling artifact in the latter case is the spatial misregistration of different compounds which causes serious errors in 31P spectra from smaller regions. Chemical shift imaging (CSI) is presented as a typical example of phase encoding techniques. An analytical expression for the relationship of the signal observed to the true signal (the point spread function) is derived. Examples of CSI in one, two, and three dimensions are used to illustrate the principles of this type of localization.     

A review of methodologies for assessing drug effectiveness and a new proposal: randomized database studies

The need to evaluate the effects of health technologies in clinical practice is increasingly important. In this article, we review the advantages and limitations of naturalistic randomized clinical trials (RCTs) and database analyses, the two primary methods for evaluating treatment effectiveness. Also, we comment on a newer research strategy, cross-design synthesis, which proposes the complementary use of both experimental RCTs and observational database methodologies to avoid the main weaknesses of each: respectively, the lack of external and internal validity. Finally, we propose a new strategy--randomized database studies--capable of generating results with an acceptable balance between internal and external validity. This strategy consists of the simultaneous use of both experimental and observational tools in the assessment of drugs' effectiveness. Randomization is essential to minimize comparison bias, and one possibility for such studies is that randomization modules could be included in computer-based patient records. Although we identify some of the difficulties in implementing the process, the progressive standardization of clinical practice and the development and widespread adoption of improved computer-based patient records could facilitate the use of randomized database studies as a new method of research.     

Optimizer convergence and local minima errors and their clinical importance

Two of the errors common in the inverse treatment planning optimization have been investigated. The first error is the optimizer convergence error, which appears because of non-perfect convergence to the global or local solution, usually caused by a non-zero stopping criterion. The second error is the local minima error, which occurs when the objective function is not convex and/or the feasible solution space is not convex. The magnitude of the errors, their relative importance in comparison to other errors as well as their clinical significance in terms of tumour control probability (TCP) and normal tissue complication probability (NTCP) were investigated. Two inherently different optimizers, a stochastic simulated annealing and deterministic gradient method were compared on a clinical example. It was found that for typical optimization the optimizer convergence errors are rather small, especially compared to other convergence errors, e.g., convergence errors due to inaccuracy of the current dose calculation algorithms. This indicates that stopping criteria could often be relaxed leading into optimization speed-ups. The local minima errors were also found to be relatively small and typically in the range of the dose calculation convergence errors. Even for the cases where significantly higher objective function scores were obtained the local minima errors were not significantly higher. Clinical evaluation of the optimizer convergence error showed good correlation between the convergence of the clinical TCP or NTCP measures and convergence of the physical dose distribution. On the other hand, the local minima errors resulted in significantly different TCP or NTCP values (up to a factor of 2) indicating clinical importance of the local minima produced by physical optimization.     

maspin suppresses the invasive phenotype of human breast carcinoma

The recently discovered tumor suppressor gene maspin has been shown to inhibit tumor cell motility, invasion, and metastasis in breast cancer by our laboratories. Nonetheless, the exploitation of maspin as a potential diagnostic and/or therapeutic tool has remained limited due to the lack of knowledge concerning its molecular and biological mechanism(s) of action. The work reported here demonstrates that recombinant maspin (rMaspin) has the ability to induce higher cell surface levels of alpha5- and alpha3-containing integrins and reduced levels of alpha2-, alpha4-, alpha6-, alpha(v)-, and some beta1-containing integrins in the metastatic human breast carcinoma cell line MDA-MB-435 concomitant with its ability to inhibit the invasive process in vitro. Furthermore, treatment of MDA-MB-435 cells with rMaspin results in the selective adhesion of the cell to a fibronectin matrix and conversion from a fibroblastic to a more epithelial-like phenotype. In addition, the ability of rMaspin to inhibit the invasive process can be abrogated with a blocking antibody to the alpha5beta1 integrin, which diminishes the ability of the cells to invade through a fibronectin matrix-containing barrier in vitro. Taken together, these data address the hypothesis that rMaspin reduces the invasive phenotype of MDA-MB-435 cells by altering their integrin profile, particularly alpha5, which in turn converts these cells to a more benign epithelial phenotype, with less invasive ability. These data provide new insights into the biological significance of this tumor suppressor gene found in normal mammary epithelium and may form the basis of novel therapeutic strategies in the management of breast carcinoma.