The pathogenic mechanism of a G44A nonsense mutation in the NDUFS4 gene and a C1564A mutation in the NDUFS1 gene of respiratory chain complex I was investigated in fibroblasts from human patients. As ...previously observed the NDUFS4 mutation prevented complete assembly of the complex and caused full suppression of the activity. The mutation (Q522K replacement) in NDUFS1 gene, coding for the 75-kDa Fe-S subunit of the complex, was associated with (a) reduced level of the mature complex, (b) marked, albeit not complete, inhibition of the activity, (c) accumulation of H2O2 and O2˙- in mitochondria, (d) decreased cellular content of glutathione, (e) enhanced expression and activity of glutathione peroxidase, and (f) decrease of the mitochondrial potential and enhanced mitochondrial susceptibility to reactive oxygen species (ROS) damage. No ROS increase was observed in the NDUFS4 mutation. Exposure of the NDUFS1 mutant fibroblasts to dibutyryl-cAMP stimulated the residual NADH-ubiquinone oxidoreductase activity, induced disappearance of ROS, and restored the mitochondrial potential. These are relevant observations for a possible therapeutical strategy in NDUFS1 mutant patients.
There is a strong interest in finding out which statistical model is the most appropriate for describing the envelope of the backscattered ultrasonic echoes from different types of tissues. The ...Rayleigh model is commonly employed, but this requires conditions, such as the presence of large number of randomly located scatterers with fairly uniform cross-sections, that are not always met. However, our research indicates that a model based on the K-distribution may provide a better fit to empirical data over a range of scattering conditions than the standard Rayleigh model. In this study, we looked at the K-distribution as a descriptor of the backscattered envelope of the breast and liver tissues (in vivo). By examining data from various tissue regions, a goodness-of-fit test (a least squares error method) was used to determine whether a Rayleigh or K-distribution model is more appropriate. From a large group of patients and volunteer scans (a total of 72 subjects), the fit between the K-distribution and the data is shown to have a much smaller error than the Rayleigh model.
To show that benign asymmetric breast tissue detected mammographically may increase over time.
Serial mammograms obtained in 21 women with negative physical examination results and mammographically ...detected developing asymmetric breast tissue were reviewed, and findings were correlated with results of biopsy (n = 16), ultrasonography (US) (n = 8), and contrast material-enhanced magnetic resonance (MR) imaging (n = 3). Five patients who did not undergo biopsy were followed up for 13-84 months. Thirteen of 16 biopsy specimens were reviewed.
At the time of mammographic change, 12 patients without baseline asymmetric tissue had a mean age of 41.7 years and a mean size of asymmetric tissue of 2.4 cm. The mean age of nine patients with baseline asymmetric tissue was 46.9 years. In eight patients, the mean size increase was 2.5 cm. One patient showed increased tissue density but stable size. All US and MR images were negative. Pseudoangiomatous stromal hyperplasia was present in all 13 biopsy specimens reviewed and extensive in 12. No malignancies have been reported in five of the followed-up patients, and two have had continued enlargement of asymmetric tissue.
Pseudoangiomatous stromal hyperplasia is a common histopathologic finding in developing asymmetric breast tissue. Follow-up, rather than biopsy, is a management option if benign imaging and clinical criteria are met.
Classification of breast masses in ultrasonic B-scan images is undertaken using a multiparameter approach. The parameters are generated on the basis of a non-Rayleigh statistic model of the ...backscattered envelope from the breast tissue. They can be computed automatically with minimal clinical intervention once the location of the mass is known. A new discriminant is developed that combines these parameters linearly. It is seen that this new discriminant performs classification of masses into benign or malignant better than the classification by any one of the individual parameters. The data set studied consisted of 99 cases (70 patients with benign masses and 29 patients with malignant masses). The areas under the receiver operating characteristic (ROC) curves (A/sub z/) and statistical attributes of the areas were studied to establish the enhancement in performance. The A/sub z/ value after combining all the parameters was found to be 0.8701. Upon combining this parameter with the level of suspicion (LOS) scores of a radiologist, the performance is further enhanced with an area under the (empirical) ROC of 0.94 having an operating point at a sensitivity of 0.965 and specificity of 0.87. It is suggested that this automated approach may hold promise as a means of classifying breast masses.
We propose a new model for the RF ultrasound echo, namely the power-law shot-noise process. Based on this model, the in-phase and quadrature components of the echo are shown to exhibit 1/f/sup /spl ...beta//-type spectral behavior, in a sense that is defined in the paper. The envelope also exhibits this type of spectral behavior, but with a different exponent. This result explains the experimental observations by other researchers of the power-law trend of the RF echo spectrum. Although the shot-noise model has been used in the past for modeling the RF echo, this is the first time that a power-law impulse response filter is used and that the resulting 1/f/sup /spl beta//-type spectral behavior of the RF echo has been investigated. The model parameters are linked to tissue characteristics, such as scatterer density and attenuation; thus, they have the potential to be used as tissue characterization features. The validity of the proposed model is tested based on a database of 100 clinical ultrasound images of the breast.
Many diseases are linked with uveitis, but few studies have specifically looked at the noninfectious triggers of childhood uveitis in Central Europe. The charts of 70 paediatric patients with ...non‐infectious uveitis admitted to the Department of Pediatrics, University of Bern, Switzerland, between 1983 and 1998 were therefore reviewed. In the patients the age at presentation with uveitis ranged between 0.3 and 16 y, median 8.5 y. Based on the localization, uveitis anterior was diagnosed in most cases (n= 40; 57%), followed by panuveitis (n= 20; 29%) and uveitis posterior (n= 10; 14%). Uveitis was chronic in 54 (77%) and acute in 16 (23%), bilateral in 38 (54%) and unilateral in 32 (46%) cases. An associated condition was noted in 32 (46%) cases: juvenile idiopathic arthritis in 24 cases, sarcoidosis and juvenile spondyloarthropathy in 3 cases, and Sjögren's syndrome and Behçet's disease in 1 case each. In the remaining 38 (54%) patients, no associated condition was diagnosed.
It is concluded that in Swiss children, uveitis can be due to a wide spectrum of non‐infectious diseases, juvenile idiopathic arthritis being the leading cause. In the majority of the children, no associated condition was recognized.
Frequency compounding was recently investigated for computer aided classification of masses in ultrasonic B-mode images as benign or malignant. The classification was performed using the normalized ...parameters of the Nakagami distribution at a single region of interest at the site of the mass. A combination of normalized Nakagami parameters from two different images of a mass was undertaken to improve the performance of classification. Receiver operating characteristic (ROC) analysis showed that such an approach resulted in an area of 0.83 under the ROC curve. The aim of the work described in this paper is to see whether a feature describing the characteristic of the boundary can be extracted and combined with the Nakagami parameter to further improve the performance of classification. The combination of the features has been performed using a weighted summation. Results indicate a 10% improvement in specificity at a sensitivity of 96% after combining the information at the site and at the boundary. Moreover, the technique requires minimal clinical intervention and has a performance that reaches that of the trained radiologist. It is hence suggested that this technique may be utilized in practice to characterize breast masses.
PDF
