Protein denaturation: a small-angle X-ray scattering study of the ensemble of unfolded states of cytochrome c

Solution X-ray scattering was used to study the equilibrium unfolding of cytochrome c as a function of guanidine hydrochloride concentration at neutral pH. The radius of gyration (Rg) shows a cooperative transition with increasing denaturant with a similar Cm to that observed with circular dichroism. However, the lack of an isoscattering point in the X-ray scattering patterns suggests the equilibrium unfolding is not simply a two-state process. Singular value decomposition (SVD) analysis was applied to the scattering patterns to determine the number of distinct scattering species. SVD analysis reveals the existence of three components, suggesting that at least three equilibrium states of the protein exist. A model was employed to determine the thermodynamic parameters and the scattering profiles of the three equilibrium states. These scattering profiles show that one state is native (N). The other two states (U1, U2) are unfolded, with U2 being fully unfolded and U1 having some residual structure. Using the thermodynamic parameters to calculate fractional populations, U1 is maximally populated at intermediate denaturant concentrations while U2 is maximally populated at high denaturant concentrations. It is likely that there is a multiplicity of denatured states with U1 and U2 representing an average of the denatured states populated at intermediate and high denaturant concentrations, respectively.     

Legal grounds for patient information in orthopedics

Neuroimaging is playing an increasing role in research of affective disorders, with investigators examining both volumetric changes of specific brain structures and vascular changes within white and gray matter. Recent studies have attempted to make clinical correlations between neuroimaging changes in unipolar and bipolar mood disorders. In this review, we focus particularly on those changes that are clinically meaningful. We conclude that there is enough evidence to begin to evaluate inclusion of neuroimaging findings in our mood disorder classification system. To this end, we propose two new mood disorder subtypes, vascular depression and vascular mania. Directions for future research in neuroimaging are then discussed.     

The limit of tactile spatial resolution in humans: grating orientation discrimination at the lip, tongue, and finger

The sensory neural pathways serving the lip, tongue, and finger are specialized for spatial information processing; thus, damage to these pathways is likely to be manifested most prominently as a loss of spatial acuity. For that reason, accurate measurement of spatial resolution at these regions is particularly important. The conventional test, the two-point discrimination task, does not measure the limit of spatial resolution and it yields variable results because it does not control nonspatial cues. The aim of this study was to quantify the limits of spatial resolution at the lip, tongue, and finger and to study the repeatability of those measurements using a stimulus that does not introduce nonspatial cues. We employed a grating orientation discrimination test, which has been studied extensively in relation to the underlying neural mechanisms. We obtained psychophysical thresholds for tactile spatial resolution from 15 normal, young adult subjects over seven test sessions. The finest gratings whose orientations were discriminated reliably had groove widths (gratings had equal groove and bar widths) that averaged 0.51 mm at the lip, 0.58 mm at the tongue, and 0.94 mm at the finger. These threshold measurements were highly reproducible between sessions with an overall improvement of 2% per session. These data suggest that the grating orientation discrimination task provides a stable, reliable measure of the human capacity for spatial resolution.     

Electron microscopy and immunolabeling of Yersinia antigens in human synovial fluid cells

Recent findings have emphasized the involvement of bacterial antigens in synovitis in reactive arthritis. It is still unclear, however, in what form the microbial material exists in the joint. Both antigen-containing cells and intact bacteria have been proposed as candidates on the basis of immunohistochemical studies of the synovial membrane. This study addresses that question by electron microscopy and peroxidase immunolabeling of synovial fluid cells from three patients with reactive arthritis triggered by Yersinia enterocolitica O:3. For all three patients a diffuse reaction in the cytoplasm of phagocytes was interpreted as bacterial material in a degraded form. These results are consistent with our proposal that intact bacteria rarely, if ever, enter the joints of Yersinia-triggered reactive arthritis patients.     

Intermittent edema of the upper and lower extremities and the abdominal wall caused by membranous stenosis of the superior vena cava and membranous obstruction of the inferior vena cava

We report on a 38-year-old patient with intermittent edema of the lower legs, arms and abdominal wall. The cause for his tendency to develop edema was a membranous obstruction of the inferior vena cava and a membranous stenosis of the superior vena cava. The etiology of these anomalies of the vena cava suggests a congenital malformation. In consideration of the cases of inferior and/or superior vena cava-anomalies published to date the patient received an anticoagulant therapy (coumarin) and treatment with graduated compression stockings. He now complains from time to time of a sensation tension in the lower legs after prolonged standing or sitting. Edema of the upper and lower extremities and the abdominal wall have disappeared.     

Recommendations for the reporting of resected neoplasms of the kidney. Association of Directors of Anatomical and Surgical Pathology

Expression of c-erbB-2 oncogene and mutant p53 protein were detected immunohistochemically in 14 cases of myoepithelioma and 6 cases of myoepithelial carcinoma of the salivary gland. Five of the 6 myoepithelial carcinomas and nine of the 14 myoepitheliomas were overexpression of c-erbB-2 oncoprotein. The salivary ductal epithelial cells near tumors were overexpression of c-erbB-2 oncoprotein. These results indicate that c-erbB-2 may be an initial oncogene during the histogenesis of myoepithelial tumors. The p53 protein was positive in five cases of the 6 myoepithelial carcinoma, whereas all myoepitheliomas were negative. The results indicate that the mutant p53 gene may play an important role in the carcinogenesis of myoepithelial carcinoma.