Visual Quality Adjustment for Volume Rendering in a Head-Tracked Virtual Environment.

To avoid simulator sickness and improve presence in immersive virtual environments (IVEs), high frame rates and low latency are required. In contrast, volume rendering applications typically strive for high visual quality that induces high computational load and, thus, leads to low frame rates. To evaluate this trade-off in IVEs, we conducted a controlled user study with 53 participants. Search and count tasks were performed in a CAVE with varying volume rendering conditions which are applied according to viewer position updates corresponding to head tracking. The results of our study indicate that participants preferred the rendering condition with continuous adjustment of the visual quality over an instantaneous adjustment which guaranteed for low latency and over no adjustment providing constant high visual quality but rather low frame rates. Within the continuous condition, the participants showed best task performance and felt less disturbed by effects of the visualization during movements. Our findings provide a good basis for further evaluations of how to accelerate volume rendering in IVEs according to user's preferences.

Interactive 3D visualization of structural changes in the brain of a person with corticobasal syndrome.

The visualization of the progression of brain tissue loss in neurodegenerative diseases like corticobasal syndrome (CBS) can provide not only information about the localization and distribution of the volume loss, but also helps to understand the course and the causes of this neurodegenerative disorder. The visualization of such medical imaging data is often based on 2D sections, because they show both internal and external structures in one image. Spatial information, however, is lost. 3D visualization of imaging data is capable to solve this problem, but it faces the difficulty that more internally located structures may be occluded by structures near the surface. Here, we present an application with two designs for the 3D visualization of the human brain to address these challenges. In the first design, brain anatomy is displayed semi-transparently; it is supplemented by an anatomical section and cortical areas for spatial orientation, and the volumetric data of volume loss. The second design is guided by the principle of importance-driven volume rendering: A direct line-of-sight to the relevant structures in the deeper parts of the brain is provided by cutting out a frustum-like piece of brain tissue. The application was developed to run in both, standard desktop environments and in immersive virtual reality environments with stereoscopic viewing for improving the depth perception. We conclude, that the presented application facilitates the perception of the extent of brain degeneration with respect to its localization and affected regions.

Mixed serous carcinoma of the endometrium with trophoblastic differentiation: analysis of the p53 tumor suppressor gene suggests stem cell origin.

The pathogenesis of mixed endometrial adenocarcinoma with trophoblastic differentiation is quite unclear at times. The present study examines a serous carcinoma with choriocarcinomatous differentiation. p53 staining was seen in the serous component and the cytotrophoblastic cells of the choriocarcinomatous component, but not in the syncytiotrophoblastic cells. p53 mutational analysis showed a heterozygotic mutation at exon 8 for the choriocarcinomatous component and a homozygote deletion at exon 7 for the serous component. These alterations suggest that the multidirectional tumor differentiation might occur from a common stem cell in these malignancies.

Serous carcinoma of the endometrium with choriocarcinomatous differentiation: a case report and review of the literature indicate the existence of 2 prognostically relevant tumor types.

Nongestational choriocarcinomas rarely occur outside the gonads or teratomas. We report a serous carcinoma of the endometrium with a choriocarcinomatous component and review of the literature. A 61-year-old woman underwent hysterectomy and bilateral salpingo-oophorectomy for a serous carcinoma with choriocarcinomatous component. Immunohistochemistry showed a strong p53 staining of the serous component and the cytotrophoblastic cells of the choriocarcinomatous component; the syncytiotrophoblast was negative. The initial serum human chorionic gonadotropin (hCG) was 225,000 IU/L. Postoperatively, the patient developed diffuse pulmonary metastatic disease. Despite chemotherapy, the patient died 2 months after initial diagnosis. Abstracting the data from the reported cases and from the literature, it can be assumed that 2 different tumor types exist. The first one is morphologically and clinically more related to the gestational choriocarcinoma with strongly elevated serum hCG levels, early onset of (distant) metastatic disease, and consecutively rapid and often fatal clinical course. The second type presents as an endometrial carcinoma with single syncytiotrophoblast-like cells, associated with low serum hCG, no distant metastatic disease, and, consequently, a better prognosis. The prognostically relevant component for long-time survival in the latter variant is the nontrophoblastic component.

High CXCR3 expression in synovial mast cells associated with CXCL9 and CXCL10 expression in inflammatory synovial tissues of patients with rheumatoid arthritis.

To improve our knowledge on the pathophysiology of rheumatoid arthritis (RA), we investigated gene expression patterns in synovial tissue from RA and osteoarthritis (OA) patients. DNA oligonucleotide microarray analysis was employed to identify differentially expressed genes in synovial tissue from pathologically classified tissue samples from RA (n = 20) and OA patients (n = 10). From 7131 gene sets displayed on the microarray chip, 101 genes were found to be upregulated and 300 genes to be downregulated in RA as compared with OA. Semiquantitative reverse-transcription polymerase chain reaction, Western blotting and immunohistochemistry were used to validate microarray expression levels. These experiments revealed that Cys-X-Cys receptor (CXCR)1, CXCR2 and CXCR3 mRNAs, as well as Cys-X-Cys ligand (CXCL)9 (monokine induced by IFN-gamma) and CXCL10 (IFN-gamma inducible protein 10) mRNAs, were significantly upregulated in RA as compared with OA disease. Elevated protein levels in RA synovial tissue were detected for CXCR1 and CXCR3 by Western blotting. Using immunohistochemistry, CXCR3 protein was found to be preferentially expressed on mast cells within synovial tissue from RA patients. These findings suggest that substantial expression of CXCR3 protein on mast cells within synovial tissue from RA patients plays a significant role in the pathophysiology of RA, accompanied by elevated levels of the chemokines CXCL9 and CXCL10. Mature mast cells are likely to contribute to and sustain the inflamed state in arthritic lesions (e.g. by production of inflammatory mediators such as histamine, proteinases, arachidonic acid metabolites and cytokines). Thus, the mast cell could become a potential target in therapeutic intervention.

Assessment of clonal stability of minimal residual disease targets between 1st and 2nd relapse of childhood precursor B-cell acute lymphoblastic leukemia.

BACKGROUND AND OBJECTIVES: Immunoglobulin (Ig) and T-cell receptor (TCR) gene rearrangements are excellent patient-specific targets for polymerase chain reaction (PCR)-based detection of minimal residual disease (MRD) in acute lymphoblastic leukemia (ALL). Nevertheless, instability of these targets during the course of the disease has important implications for PCR-based MRD monitoring and may lead to false negative results. DESIGN AND METHODS: Several studies have shown that Ig and TCR targets are reasonably stable in ALL between diagnosis and first relapse, but up to now, there are no data on the stability of these targets between first and second relapse. We, therefore, performed a PCR-study on bone marrow samples from 49 children with precursor B-ALL at first and second relapse. Homo-heteroduplex PCR analyses were used for identification of clonal IGH, IGK-Kde, TCRG and TCRD gene rearrangements. Clonal targets were studied by sequencing and/or comparative homo-heteroduplex analysis. RESULTS: In 52% (25/48) of the patients, all PCR targets identified at first relapse were preserved at second relapse; in 92% (44/48) of the patients at least one target and in 73% (35/48) at least two targets remained stable. Best stability was found for IGH and TCRG gene rearrangements. INTERPRETATION AND CONCLUSIONS: Based on these first data about clonal stability of Ig and TCR targets between first and second relapse of childhood precursor B-ALL, we developed a stepwise strategy for appropriate selection of stable PCR targets for MRD monitoring. This strategy was applicable in 84% of the relapsed patients and resulted in at least one stable MRD-PCR target per patient in 98% of these children.