Citations

Abstract Three-dimensional imaging of the intact lung and its vasculature is essential if the hierarchical and volumetric aspects of its structures and functions are to be quantitated. Although this is possible with clinical multislice helical CT scanners, the spatial resolution does not scale down adequately for small rodents for which cubic voxel dimensions of 50–100 μm are required. Micro-computed tomography (micro-CT) provides the necessary spatial resolution of 3D images of the intact thoracic contents. Micro-CT can provide higher resolution so that basic micro-architectural structures, such as alveoli, can be individually visualized and quantitated. Dynamic events, such as the respiratory and cardiac cycles, can be imaged at multiple time points throughout a representative cycle by coordinating the scan sequence (i.e., gating) to the cycle phase of a sequence of cycles. Fusion of the micro-CT image data with other image data, such as micro-SPECT or histology, can enhance the information content beyond the mainly structural information provided by micro-CT. Conventional attenuation-based X-ray imaging can involve significant X-ray exposures at high spatial resolutions, and this could affect the phenotype (e.g., via interstitial fibrosis) and genotype (e.g., via mutation), so its use in longitudinal studies using micro-CT may be limited in some cases. However, because of recent developments in which the phase shift or refraction of X-rays rather than attenuation is used, the X-ray exposure may be significantly reduced.

ABSTRACT The human immunodeficiency virus type 1 (HIV-1) protein Vpr (viral protein R) arrests cells in the G 2 phase of the cell cycle, a process that requires activation of the ATR (ataxia-telangiectasia and Rad3-related) pathway. In this study we demonstrate that the expression of Vpr does not cause DNA double-strand breaks but rather induces ATR activation, as indicated by induction of Chk1 phosphorylation and the formation of γ-H2AX and 53BP1 nuclear foci. We define a C-terminal domain containing repeated H(F/S)RIG sequences required for Vpr-induced activation of ATR. Further investigation of the mechanism by which Vpr activates the ATR pathway reveals an increase in chromatin binding of replication protein A (RPA) upon Vpr expression. Immunostaining shows that RPA localizes to nuclear foci in Vpr-expressing cells. Furthermore, we demonstrate direct binding of Vpr to chromatin in vivo, whereas Vpr C-terminal domain mutants lose this chromatin-binding activity. These data support a mechanism whereby HIV-1 Vpr induces ATR activation by targeting the host cell DNA and probably interfering with normal DNA replication.

Objective— We hypothesized that apolipoprotein E (apoE) −/− /low-density lipoprotein (LDL) −/− double knockout mice might develop vasa vasorum (VV) in association with advanced lesion formation. Methods and Results— Aortas from apoE −/− /LDL −/− mice aged 16, 18, 20, or 80 weeks were infused in situ with Microfil, harvested, and scanned with micro-computed tomography (CT). We characterized plaque volume and CT “density” as well as VV luminal volume along the aorta using Analyze 6.0 software. Results were complemented by a detailed histological plaque classification according to American Heart Association guidelines. From 16 to 80 weeks, plaque volume and VV opacified lumen volume increased with age ( P <0.001). The 3-dimensional micro-CT images of arterial and venous VV trees allowed perfusion territories to be delineated. The spatial location and magnitude of VV density and adventitial inflammation were strongly correlated in advanced atherosclerotic lesions ( r =0.91) and identified as an independent correlate to advanced lesions. At age 80 weeks, VV luminal volume was increased 20-fold compared with animals at age 16 weeks ( P <0.001). Micro-CT showed that adventitial VV communicate with intraplaque microvessels. Conclusion— Our results show that apoE −/− /LDL −/− double knockout mice develop VV and advanced atheromas along the aorta. Lesion volume was closely associated with amount of neovascularization in advanced atheromas.

Background— The goal of this study was to determine whether the expression of vascular endothelial growth factor (VEGF) is critical for coronary collateral growth. Previous studies have provided an association between coronary collateral growth and VEGF, but none have allowed determination of a causal role. Methods and Results— We measured coronary collateral growth in rats subjected to repetitive episodes of myocardial ischemia (RI; one 40-second occlusion every 20 minutes for 2 hours 40 minutes, followed by 5 hours 20 minutes of rest, with this 8-hour cycle repeated 3 times per day for 10 days). Collateral growth was measured from blood flow (radioactive microspheres), visualization of arterial-arterial anastomoses (x-ray micro-CT), and maintenance of function during complete coronary occlusion in 3 groups of animals: sham (received instrumentation but no RI), experimental (subjected to RI), and anti–vascular endothelial growth factor (RI+anti-VEGF 0.6 mg/100 g per day) to block the endogenous actions of VEGF. In the 3 groups, native collateral flow (measurement for RI or sham protocol) averaged 0.2 to 0.3 mL · min −1 · g −1 of tissue. In the sham group, collateral flow did not increase during the protocol. Collateral flow in the control RI group increased by ≈6-fold to 1.63 mL · min −1 · g −1 tissue, but in the anti-VEGF group, collateral flow did not increase after the RI protocol (0.22 mL · min −1 · g −1 ). In acute experiments, collateral flow was unchanged during vasodilation with dipyridamole, indicating the increases in collateral flow are due to collateral growth and not vasodilation. X-ray micro-CT analysis revealed a 3-fold increase (versus sham group) in the number of arterial-arterial anastomoses per heart after RI, which was prevented by treatment with anti-VEGF. The growth of the collateral circulation was functional in the RI group because complete coronary occlusion did not induce any untoward effects on hemodynamics or arrhythmias. In the sham or anti-VEGF groups, coronary occlusion at the end of the protocol induced many arrhythmias and deterioration of function. Conclusions— From these results, we conclude that the expression of VEGF is critical to the growth of coronary collaterals.

AbstractThe latest World Health Organization International Classification defines papillary thyroid carcinoma by its “follicular cell differentiation. .. as well as characteristic nuclear changes”. However the oxyphilic (Hürthle cell) papillary carcinoma have nuclei which generally resemble the nuclei seen in oxyphilic follicular carcinomas, and such oxyphilic papillary tumors may behave more aggressively than typical papillary cancers. To further characterize these rare tumors, we identified during a 32‐year period 22 patients with oxyphilic papillary cancer and compared them with 1,084 patients with typical papillary cancers and 57 patients with oxyphilic follicular cancers treated by the Mayo surgical group during the same time period. Although typical papillary and oxyphilic papillary cancers were comparable with regards to patient age, tumor size and extent, TNM stage, and prognostic score (AGES), there were significant differences. Compared to typical papillary tumors, oxyphilic papillary cancers had fewer neck nodal metastases at primary diagnosis (5% vs 40%,p<0.0001), were more often DNA non‐diploid (71% vs 21%,p<0.001), and after 10 postoperative years had higher rates of both tumor recurrence (28% vs 11%,p<0.0001) and cause‐specific mortality (1.7% vs 4%,p<0.0005). In these four important respects the oxyphilic papillary cancers more resembled the oxyphilic follicular cancers. For oxyphilic follicular cancers, the frequency of initial neck nodal metastases was 7% (cf 5%); 83% of the oxyphilic follicular tumors were non‐diploid (cf 71%), and at 10 years postoperatively the tumor recurrence and cause‐specific mortality rates were 28% and 18%, insignificantly different from 28% and 17% seen with the oxyphilic papillary cancers. These results demonstrate that oxyphilic papillary tumors are more similar to oxyphilic follicular than typical papillary cancers, and suggest that in a differentiated follicular cell‐derived carcinoma a predominance of oxyphilic cells may be a prognostically more relevant feature than the individual tumor's predominant papillary or follicular morphologic pattern. Perhaps in future Histologic Classifications the World Health Organization should group the oxyphilic papillary cancers with the oxyphilic follicular rather than the typical papillary carcinomas.

AbstractWhereas excisional surgery and radiotherapy have resulted in a favorable outcome when non‐Hodgkin's lymphoma of the thyroid (NHLT) is confined to the thyroid gland, controversy persists over the potential advantage of aggressive debulking in favor of diagnostic biopsy alone when disease cannot be completely resected. Our aims in this study were to delineate the present role of surgery in NHLT in pre‐operative staging, the impact of the extent of resection on achieving complete remission and cause‐specific survival, and patterns of failure. All 62 patients who underwent primary surgery for NHLT at the Mayo Clinic between 1965 and 1989 were analyzed. By postoperative staging, 50 patients were stage IE or IIE. Overall survival was 53% and 46% at 5 and 10 years; 80% for stage IE confined to the thyroid, 58% for stage IE‐extrathyroid, 50% for stage IIE, and 36% for stages IIIE and IVE. Complete remission was achieved in 88% of patients who underwent diagnostic biopsy plus adjuvant therapy alone compared to 85% for patients in whom debulking plus adjuvant therapy was used. There was no difference in cause‐specific survival in these two groups or in cause‐specific survival in two subgroups who achieved complete remission. Relapse after complete remission occurred in 12 (26%) of 46 patients, only 2 of whom survived long‐term after salvage therapy. The role of surgery in NHLT is diminishing and advances that will increase complete remission and relapse‐free survival will not likely involve more aggressive surgical resections.