PLIF surgery with titanium-coated PEEK or uncoated PEEK cages: a prospective randomised clinical and radiological study.

PURPOSE: This study aimed to compare clinical results and fusion rates of uncoated polyetheretherketone (PEEK) cages with titanium-coated PEEK cages in posterior lumbar interbody fusion (PLIF) surgery. METHODS: A prospective randomised study including 60 patients with one- or two-segment lumbar degenerative diseases. Patients received either titanium-coated PEEK cages (group A) or uncoated PEEK cages (group B). Fusion rates were evaluated on plain X-rays and CT scans after 6 and 12 months. Clinical follow-up (visual analogue scale, VAS; Oswestry Disability Index score, ODI; EQ-5D) was performed for 24 months. RESULTS: Fifty-five patients (92%) (36 female, 19 male) had a complete follow-up. There were no statistically significant differences in demographic, peri- or intraoperative data between groups A and B. ODI, VAS and EQ-5D improved significantly (p < 0.001) after surgery without statistically significant differences between the two groups. Overall, 65 operated segments could be evaluated for fusion (group A: 29 segments, group B: 36 segments, p = 0.6). Osseous integration of the cage surface improved significantly (p < 0.001) in both groups between 6 and 12 months after surgery. At 12-month follow-up, neither radiolucency nor signs of instability or dislocation were noted. Fusion was present in CT scans as follows: (a) bone growth through cage pores (A: 100%, B: 100%); (b) bone growth outside the cages (A: 48%, B: 61%; p = 0.3). CONCLUSIONS: PEEK and titanium-coated PEEK cages for PLIF produce equally favourable clinical and radiological results up to 24 months post-surgery. The fusion rate was not different.

Neovascularization of osteoporotic metaphyseal bone defects: A morphometric micro-CT study.

PURPOSE: Neovascularization is essential for bone regeneration in fractures. This study aimed to investigate the microvascular morphology and distribution in the non-injured femur and the neovascularization of the metaphyseal critical size defect in a small animal model of osteoporosis. MATERIALS AND METHODS: Female rats (n=7) were ovariectomized (OVX) and received a multideficiency diet. Three months after OVX, a 5mm wedge shaped critical size defect was cut at the distal femoral metaphysis and stabilized with a T-shaped mini-plate. After six weeks, the animals were euthanized, and femora were removed and decalcified for micro-CT measurement of fracture neovascularization. RESULTS: No fracture healing was observed along the critical size defects. In the non-injured bone, micro-vessel distribution showed a specific pattern, thereby enabling a differentiation between epi-, meta- and diaphysis. Micro-CT based morphometry revealed a significant reduction of the vascular volume fraction as well as the vascular thickness (p<0.001) in the critical size defect compared to the intact contralateral femur. Blood volume related vascular surface (vascular surface/volume) increased significantly (p<0.001). Connectivity density and tissue volume related vascular surface (vascular surface density) did not change significantly. CONCLUSIONS: Micro-CT based vascular morphometry demonstrated differences between epi-, meta- and diaphysis in the non-injured bone as well as differences between the critical size defect and the non-injured metaphysis. As angiogenesis is a crucial prerequisite that precedes osteogenesis, our results may influence further evaluation of osteoconductive or osteogenic biomaterials in this small animal model of osteoporosis.

Impaired extracellular matrix structure resulting from malnutrition in ovariectomized mature rats.

Bone loss is a symptom related to disease and age, which reflects on bone cells and ECM. Discrepant regulation affects cell proliferation and ECM localization. Rat model of osteoporosis (OVX) was investigated against control rats (Sham) at young and old ages. Biophysical, histological and molecular techniques were implemented to examine the underlying cellular and extracellular matrix changes and to assess the mechanisms contributing to bone loss in the context of aging and the widely used osteoporotic models in rats. Bone loss exhibited a compromised function of bone cells and infiltration of adipocytes into bone marrow. However, the expression of genes regulating collagen catabolic process and adipogenesis was chronologically shifted in diseased bone in comparison with aged bone. The data showed the involvement of Wnt signaling inhibition in adipogenesis and bone loss due to over-expression of SOST in both diseased and aged bone. Further, in the OVX animals, an integrin-mediated ERK activation indicated the role of MAPK in osteoblastogenesis and adipogenesis. The increased PTH levels due to calcium and estrogen deficiency activated osteoblastogenesis. Thusly, RANKL-mediated osteoclastogenesis was initiated. Interestingly, the data show the role of MEPE regulating osteoclast-mediated resorption at late stages in osteoporotic bone. The interplay between ECM and bone cells change tissue microstructure and properties. The involvement of Wnt and MAPK pathways in activating cell proliferation has intriguing similarities to oncogenesis and myeloma. The study indicates the importance of targeting both pathways simultaneously to remedy metabolic bone diseases and age-related bone loss.

Bone matrix, cellularity, and structural changes in a rat model with high-turnover osteoporosis induced by combined ovariectomy and a multiple-deficient diet.

In estrogen-deficient, postmenopausal women, vitamin D and calcium deficiency increase osteoporotic fracture risk. Therefore, a new rat model of combined ovariectomy and multiple-deficient diet was established to mimic human postmenopausal osteoporotic conditions under nutrient deficiency. Sprague-Dawley rats were untreated (control), laparatomized (sham), or ovariectomized and received a deficient diet (OVX-Diet). Multiple analyses involving structure (micro-computed tomography and biomechanics), cellularity (osteoblasts and osteoclasts), bone matrix (mRNA expression and IHC), and mineralization were investigated for a detailed characterization of osteoporosis. The study involved long-term observation up to 14 months (M14) after laparotomy or after OVX-Diet, with intermediate time points at M3 and M12. OVX-Diet rats showed enhanced osteoblastogenesis and osteoclastogenesis. Bone matrix markers (biglycan, COL1A1, tenascin C, and fibronectin) and low-density lipoprotein-5 (bone mass marker) were down-regulated at M12 in OVX-Diet rats. However, up-regulation of matrix markers and existence of unmineralized osteoid were seen at M3 and M14. Osteoclast markers (matrix metallopeptidase 9 and cathepsin K) were up-regulated at M14. Micro-computed tomography and biomechanics confirmed bone fragility of OVX-Diet rats, and quantitative RT-PCR revealed a higher turnover rate in the humerus than in lumbar vertebrae, suggesting enhanced bone formation and resorption in OVX-Diet rats. Such bone remodeling caused disturbed bone mineralization and severe bone loss, as reported in patients with high-turnover, postmenopausal osteoporosis. Therefore, this rat model may serve as a suitable tool to evaluate osteoporotic drugs and new biomaterials or fracture implants.

Systemic atherosclerosis causes detrusor overactivity: functional and morphological changes in hyperlipoproteinemic apoE-/-LDLR-/- mice.

PURPOSE: The prevalence of systemic atherosclerosis and overactive bladder/detrusor overactivity increases almost simultaneously with age but an association between these diseases has not yet been proved. We evaluated changes in bladder function and morphology, including vascularization, in apoE(-/-)LDLR(-/-) double knockout mice with systemic atherosclerosis but without central nervous system involvement. MATERIALS AND METHODS: Cystometry was performed in awake, freely moving 60-week-old apoE(-/-)LDLR(-/-) mice and C57BL/6N controls. The mice were sacrificed and perfused with Microfil® contrast medium. The bladder was excised, dissected and scanned by nano-computerized tomography, including 3-dimensional reconstruction. Samples then underwent histomorphological analysis. RESULTS: In apoE(-/-)LDLR(-/-) mice cystometry revealed a significant decrease in the peak-peak interval, micturition interval, functional bladder capacity and micturition volume. However, maximum bladder pressure increased. Nano-computerized tomography revealed a significant reduction in bladder wall thickness, segment volume, vascular volume and the vascular volume fraction. Histomorphologically bladder specimens showed a thickened media of intramural vessels, activated endothelial cells and intramural inflammatory cells. CONCLUSIONS: To our knowledge this study presents a new in vivo mouse model of nonneurogenic detrusor overactivity caused by systemic atherosclerosis. Decreased bladder wall vascularization seems to be a major factor for detrusor overactivity onset. Capillaries are rarified with reduced lumina due to thickened media. Activated endothelial cells and the infiltration of inflammatory cells in apoE(-/-)LDLR(-/-) mice underlines once more that atherosclerosis is an inflammatory process that may also be relevant to the onset of detrusor overactivity.

Small changes in bone structure of female α7 nicotinic acetylcholine receptor knockout mice.

BACKGROUND: Recently, analysis of bone from knockout mice identified muscarinic acetylcholine receptor subtype M3 (mAChR M3) and nicotinic acetylcholine receptor (nAChR) subunit α2 as positive regulator of bone mass accrual whereas of male mice deficient for α7-nAChR (α7KO) did not reveal impact in regulation of bone remodeling. Since female sex hormones are involved in fair coordination of osteoblast bone formation and osteoclast bone degradation we assigned the current study to analyze bone strength, composition and microarchitecture of female α7KO compared to their corresponding wild-type mice (α7WT). METHODS: Vertebrae and long bones of female 16-week-old α7KO (n = 10) and α7WT (n = 8) were extracted and analyzed by means of histological, radiological, biomechanical, cell- and molecular methods as well as time of flight secondary ion mass spectrometry (ToF-SIMS) and transmission electron microscopy (TEM). RESULTS: Bone of female α7KO revealed a significant increase in bending stiffness (p < 0.05) and cortical thickness (p < 0.05) compared to α7WT, whereas gene expression of osteoclast marker cathepsin K was declined. ToF-SIMS analysis detected a decrease in trabecular calcium content and an increase in C4H6N(+) (p < 0.05) and C4H8N(+) (p < 0.001) collagen fragments whereas a loss of osteoid was found by means of TEM. CONCLUSIONS: Our results on female α7KO bone identified differences in bone strength and composition. In addition, we could demonstrate that α7-nAChRs are involved in regulation of bone remodelling. In contrast to mAChR M3 and nAChR subunit α2 the α7-nAChR favours reduction of bone strength thereby showing similar effects as α7ß2-nAChR in male mice. nAChR are able to form heteropentameric receptors containing α- and ß-subunits as well as the subunits α7 can be arranged as homopentameric cation channel. The different effects of homopentameric and heteropentameric α7-nAChR on bone need to be analysed in future studies as well as gender effects of cholinergic receptors on bone homeostasis.

Western diet in ApoE-LDLR double-deficient mouse model of atherosclerosis leads to hepatic steatosis, fibrosis, and tumorigenesis.

Nonalcoholic fatty liver disease has been linked to cardiovascular diseases and atherosclerosis. The aim of the current study was to characterize the hepatic pathology leading to fibrosis and tumors in a murine model of atherosclerosis. Male apolipoprotein E/low-density lipoprotein receptor double-knockout mice (AL) mice were fed with a high fat and high cholesterol western diet for 35 weeks (AL mice on WD). Protein and mRNA analysis as well as micro-computed tomography (micro-CT) were performed to assess oxidative stress, liver damage, inflammation, fibrosis, signaling pathways, vascularization, and tumorigenesis. Controls were chosen to distinguish between genetically and dietary effects in steatohepatitis and associated tumorigenesis. Hepatic inflammation and dyslipidemia were increased in AL mice on WD compared with wild-type mice on WD. Uniquely, AL mice on WD showed a spontaneous development of tumors (30% of cases) and thickening of intrahepatic vessel walls. Functionally relevant underlying signaling pathways such as NF-κB, Stat3, JNK, and AKT were differentially regulated between AL and wild-type mice on WD. Micro-CT was capable of visualizing and quantitatively distinguishing tumor neovascularization from vascularization in non-neoplastic liver tissue. AL mice on WD diet represent a novel model combining atherosclerosis and nonalcoholic fatty liver disease. Signaling pathways of liver cell damage and compensatory liver regeneration in combination with enhanced inflammation appear to be crucial for the spontaneous development of tumors in AL mice on WD. Micro-CT represents a new and powerful technique for the ultrastructural and three-dimensional assessment of the vascular architecture of liver tumors.

Induction of osteoporosis with its influence on osteoporotic determinants and their interrelationships in rats by DEXA.

BACKGROUND: As women are the population most affected by multifactorial osteoporosis, research is focused on unraveling the underlying mechanism of osteoporosis induction in rats by combining ovariectomy (OVX) either with calcium, phosphorus, vitamin C and vitamin D2/D3 deficiency, or by administration of glucocorticoid (dexamethasone). MATERIAL/METHODS: Different skeletal sites of sham, OVX-Diet and OVX-Steroid rats were analyzed by Dual Energy X-ray Absorptiometry (DEXA) at varied time points of 0, 4 and 12 weeks to determine and compare the osteoporotic factors such as bone mineral density (BMD), bone mineral content (BMC), area, body weight and percent fat among different groups and time points. Comparative analysis and interrelationships among osteoporotic determinants by regression analysis were also determined. RESULTS: T scores were below-2.5 in OVX-Diet rats at 4 and 12 weeks post-OVX. OVX-diet rats revealed pronounced osteoporotic status with reduced BMD and BMC than the steroid counterparts, with the spine and pelvis as the most affected skeletal sites. Increase in percent fat was observed irrespective of the osteoporosis inducers applied. Comparative analysis and interrelationships between osteoporotic determinants that are rarely studied in animals indicate the necessity to analyze BMC and area along with BMD in obtaining meaningful information leading to proper prediction of probability of osteoporotic fractures. CONCLUSIONS: Enhanced osteoporotic effect observed in OVX-Diet rats indicates that estrogen dysregulation combined with diet treatment induces and enhances osteoporosis with time when compared to the steroid group. Comparative and regression analysis indicates the need to determine BMC along with BMD and area in osteoporotic determination.

Angioarchitectural changes in subacute cerebral venous thrombosis. A synchrotron-based micro- and nano-CT study.

It is well known that recanalization of thrombosed cerebral sinuses occurs early but without marked influence on the long-term outcome and on final venous infarct volume on magnetic resonance imaging. To better understand the possible microvascular mechanisms behind these clinical observations, we evaluated the sequels of subacute superior sagittal sinus (SSS) thrombosis in rats using micro- and nano-CT imaging of the same specimen to provide large volume and high resolution CT image data respectively. SSS thrombosis was induced in 11 animals which were euthanized after 6h (n=4) or 6 weeks (n=7). Eight sham-operated rats served as controls. After infusion of contrast into the vasculature of the brains, these were isolated and scanned using micro-, nano-, and synchrotron-based micro-CT ((8 µm³), (900 nm)³, and (1.9 µm³) voxel sizes). The cross-sectional area of the superior sagittal sinus, microvessels and cortical veins were quantified. Tissue sections were stained against VEGF antigen. Immunohistochemistry was confirmed using quantitative rtPCR. SSS thrombosis led to a congestion of the bridging veins after 6h. After 6 weeks, a network of small vessels surrounding the occluded SSS was present with concurrent return towards the diameter of the draining bridging veins of controls. This microvascular network connected to cortical veins as demonstrated by nano- and synchrotron-based micro-CT. Also the volume fraction and number of cortical veins increased significantly. Immunohistochemistry in the region of the microsvascular network demonstrated a strong immunoreactivity against VEGF, confirmed by rtPCR. The sequel of subacute SSS thrombosis induced a network of microvessels ("venogenesis") draining the bridging veins. Also the volume fraction of cortical veins increased significantly.

3-Deazaadenosine prevents smooth muscle cell proliferation and neointima formation by interfering with Ras signaling.

3-Deazaadenosine (c3Ado) is a potent inhibitor of S-adenosylhomocysteine hydrolase, which regulates cellular methyltransferase activity. In the present study, we sought to determine the effect of c3Ado on vascular smooth muscle cell (VSMC) function and neointima formation in vivo. c3Ado dose-dependently prevented the proliferation and migration of human coronary VSMCs in vitro. This was accompanied by an increased expression of the cyclin-dependent kinase inhibitors p21(WAF1/Cip1), p27(Kip1), a decreased expression of G(1)/S phase cyclins, and a lack of retinoblastoma protein hyperphosphorylation. In accordance with these findings, fluorescence-activated cell-sorting analysis of propidium iodide-stained cells indicated a cell cycle arrest in the G(0)/G(1) phase. Importantly, c3Ado did not affect the number of viable (trypan blue exclusion) or apoptotic cells (TUNEL). Mechanistically, c3Ado prevented FCS-induced Ras carboxyl methylation and membrane translocation and activity by inhibiting isoprenylcysteine carboxyl methyltransferase and reduced FCS-induced extracellular signal-regulated kinase (ERK)1/2 and Akt phosphorylation in a dose-dependent manner. Conversely, rescuing signal transduction by overexpression of a constitutive active Ras mutant abrogated c3Ado's effect on proliferation. For in vivo studies, the femoral artery of C57BL/6 mice was dilated and mice were fed a diet containing 150 microg of c3Ado per day. c3Ado prevented dilation-induced Ras activation, as well as ERK1/2 and Akt phosphorylation in vivo. At day 21, VSMC proliferation (proliferating-cell nuclear antigen [PCNA]-positive cells), as well as the neointima/media ratio (0.7+/-0.2 versus 1.6+/-0.4; P<0.05) were significantly reduced, without any changes in the number of apoptotic cells. Our data indicate that c3Ado interferes with Ras methylation and function and thereby with mitogenic activation of ERK1/2 and Akt, preventing VSMC cell cycle entry and proliferation and neointima formation in vivo. Thus, therapeutic inhibition of S-adenosylhomocysteine hydrolase by c3Ado may represent a save and effective novel approach to prevent vascular proliferative disease.

Inhibition of the p38 MAP kinase in vivo improves number and functional activity of vasculogenic cells and reduces atherosclerotic disease progression.

Initial trials suggest that bone marrow-derived vasculogenic cells augment neovascularization in patients after myocardial infarction. Moreover, in some experimental settings, they also provide an anti-atherosclerotic effect by maintaining the integrity of the endothelium. Risk factors for coronary artery disease were shown to reduce the number and functional activity of vasculogenic cells and increased cellular p38 MAP kinase activity. Inhibition of p38 MAP kinase increases the number and functional activity of proangiogenic cells in vitro and clinical trials are under way to examine the effect of p38 inhibition in patients with CAD. Here, we examined the effect of systemic p38 MAP kinase inhibition on vasculogenic cells and atherosclerotic disease progression in vivo. Treatment of ApoE(-/-) mice with the p38 inhibitor SB203580 significantly increased the number of pro-angiogenic cells such as Sca-1(+)Flk-1(+) as well as CD11b(low)Flk-1(+) cells and reduced the number of the inflammatory Gr1(+)CD45(+) cells. Moreover, invasion capacity of bone marrow-derived mononuclear cells under basal conditions as well as towards a gradient of SDF-1 was significantly augmented in ApoE-/- mice after p38 inhibition. Finally, treatment of ApoE(-/-) mice with SB203580 for 4 months reduced atheromatous lesion size by 51 +/- 3% (p < 0.05) without affecting the density of vasa vasorum in the plaques. In conclusion, this study demonstrates that systemic p38 MAP kinase inhibition with SB203580 improves the number and function of vasculogenic cells in an animal model of hypercholesterolemia, and reduces atherosclerotic disease progression in ApoE(-/-) mice.

Evaluation of the middle cerebral artery occlusion techniques in the rat by in-vitro 3-dimensional micro- and nano computed tomography.

BACKGROUND: Animal models of focal cerebral ischemia are widely used in stroke research. The purpose of our study was to evaluate and compare the cerebral macro- and microvascular architecture of rats in two different models of permanent middle cerebral artery occlusion using an innovative quantitative micro- and nano-CT imaging technique. METHODS: 4h of middle cerebral artery occlusion was performed in rats using the macrosphere method or the suture technique. After contrast perfusion, brains were isolated and scanned en-bloc using micro-CT (8 mum)3 or nano-CT at 500 nm3 voxel size to generate 3D images of the cerebral vasculature. The arterial vascular volume fraction and gray scale attenuation was determined and the significance of differences in measurements was tested with analysis of variance [ANOVA]. RESULTS: Micro-CT provided quantitative information on vascular morphology. Micro- and nano-CT proved to visualize and differentiate vascular occlusion territories performed in both models of cerebral ischemia. The suture technique leads to a remarkable decrease in the intravascular volume fraction of the middle cerebral artery perfusion territory. Blocking the medial cerebral artery with macrospheres, the vascular volume fraction of the involved hemisphere decreased significantly (p < 0.001), independently of the number of macrospheres, and was comparable to the suture method. We established gray scale measurements by which focal cerebral ischemia could be radiographically categorized (p < 0.001). Nano-CT imaging demonstrates collateral perfusion related to different occluded vessel territories after macrosphere perfusion. CONCLUSION: Micro- and Nano-CT imaging is feasible for analysis and differentiation of different models of focal cerebral ischemia in rats.

In vitro evaluation of the sinus sagittalis superior thrombosis model in the rat using 3D micro- and nanocomputed tomography.

INTRODUCTION: Thrombosis of the cerebral veins and sinus are common causes of stroke. Animal models help us to understand the underlying pathophysiology of this condition. Therefore, the purpose of our study was to evaluate a well-established model for sinus sagittalis (SSS) thrombosis using micro- and nanocomputed tomography (CT) imaging. METHODS: SSS thrombosis was performed in four rats. After contrast perfusion, brains were isolated and scanned using micro-CT at (8 microm)(3) voxel size to generate 3D images of the cerebral vasculature. For more detailed information on vascular perfusion territories, nano-CT imaging was performed to investigate the boundary layer of contrast-enhanced vessels and the occluded veins. The venous and arterial vascular volume fraction and gray scale measurements were obtained in the SSS thrombosis group and compared to controls. The significance of differences in vascular volume fraction and gray scale measurements was tested with analysis of variance. Results were complemented with histology. RESULTS: Micro-CT proved to accurately visualize and differentiate vascular occlusion territories performed in the SSS thrombosis model. Moreover, 3D micro-CT provided quantitative information on arterial and venous vascular volume fraction. Micro-CT imaging enables a total 3D visualization of complications (ventricle rupture) in the SSS thrombosis model. We established gray scale measurements by which focal cerebral ischemia could be radiographically categorized (p < 0.001). CONCLUSIONS: Using nano-CT, the interface of contrast-perfused and occluded veins can be visualized. Micro-CT is feasible for analysis and differentiation of perfusion territories in an animal model of focal cerebral ischemia.

Quantification of vasa vasorum density in multi-slice computed tomographic coronary angiograms: role of computed tomographic image voxel size.

OBJECTIVE: This study is motivated by the possibility of using computed tomography (CT) to detect early coronary atherosclerosis by the increased CT values within the arterial wall resulting from vasa vasorum proliferation. METHODS: Coronary arteries (n = 5) with early atherosclerotic changes were injected with Microfil and scanned (micro-CT). Noise was added to the CT projection data sets (to represent the radiation exposure of current clinical CT scanners) and then reconstructed to generate 3-dimensional images at different voxel sizes. RESULTS: Higher CT values were detected because of contrast agent in vasa vasorum if voxel size was less than (150 microm)(3). Contrast in the main lumen increased the CT values dramatically at voxels greater than (100 microm)(3), whereas CT values of the same specimen without contrast in the main lumen remained constant. CONCLUSIONS: Voxel sizes less than (200 microm)(3) are needed to quantitate arterial wall opacification due to vasa vasorum proliferation.

Atherosclerosis, inflammation and lipoprotein glomerulopathy in kidneys of apoE-/-/LDL-/- double knockout mice.

BACKGROUND: The apoE-/-/LDL-/- double knockout mice are bearing considerable structural homology to human atherosclerosis. We hypothesized, that advanced lesion formation in the renal artery is associated with kidney alterations in these mice. METHODS: Kidneys from apoE-/-/LDL-/- double knockout mice at the age of 80 weeks (n = 6) and C57/BL control mice (n = 5) were infused with Microfil, harvested and scanned with micro-CT (12 mum cubic voxels) and Nano-CT (900 nm cubic voxels). We quantitated the total vascular volume using micro-CT. Number and cross-sectional area (microm2) of glomeruli were measured using histology. RESULTS: At the age of 80 weeks, the renal total vascular volume fraction decreased significantly (p < 0.001) compared to controls. Moreover, the renal artery showed advanced atherosclerotic lesions with adventitial Vasa vasorum neovascularization. Perivascular inflammation was present in kidneys of apoE-/-/LDL-/- double knockout mice, predominantly involved are plasma cells and leucocytes. Glomeruli cross-sectional area (9959 +/- 1083 microm2) and number (24.8 +/- 4.5) increased in apoE-/-/LDL-/- double knockout mice compared to controls (3533 +/- 398 microm2; 17.6 +/- 3, respectively), whereas 41% of the total number of glomeruli showed evidence for lipoprotein associated glomerulopathy (LPG). Moreover, immunohistochemistry demonstrated capillary aneurysms of the glomeruli filled with factor 8 containing emboli. CONCLUSION: The reduced intra-renal total vascular volume is associated with systemic atherosclerosis and glomeruli alterations in the apoE-/-/LDL-/- double knockout mouse model.

Advances in the Preoperative Planning of Revision Trauma Surgery Using 3D Printing Technology.

The management of complex fractures at the time of revision surgery remains one of the most challenging tasks for orthopaedic trauma surgeons. As the major principle of treatment remains to achieve an anatomic reduction and a stable fixation, precise preoperative diagnostics and treatment planning are of utmost importance. Thus, knowledge of the 3-dimensional anatomy of the fracture site and its surrounding tissue is indispensable. However, radiographic tools have thus far mostly been unable to recapitulate the complexity of the fracture site in toto. In recent years, the development of 3-dimensional (3D) printers has led to novel opportunities in preoperative planning of complex operative procedures. Although the application of 3D printers has become increasingly popular in orthopaedic surgery, its implementation in trauma surgery is so far mostly limited to the preoperative planning of surgery in patients with pelvic and acetabular fractures/defects. Moreover, reports describing the advantages using this sophisticated methodology in revision trauma surgery are sparse. In this article, we report our experience using novel 3D printing technologies for the management of revision surgery in orthopaedic trauma. In particular, we describe the benefit of using 3D printing technologies in the preoperative planning of complex revision surgery of the proximal tibia, the elbow joint, the distal femur, the ankle joint, and several others. With the advantage to preoperatively plan the optimal surgical approach, implant placement, and contouring as well as the possibility to anticipate intraoperative difficulties, we believe that this emerging technology is of significant value for revision surgery in orthopaedic trauma.

Role of computed tomography voxel size in detection and discrimination of calcium and iron deposits in atherosclerotic human coronary artery specimens.

OBJECTIVE: This study evaluated the influence of voxel size on its ability to discriminate calcium from iron deposits in ex vivo coronary arteries. METHODS: Postmortem human coronary arteries underwent multislice computed tomographic scan at (600-microm) voxel size to provide an index of computed tomography (CT) image noise and synchrotron-based micro-CT at (4-microm) voxel size to provide data for generating a range of voxel sizes 4 to (600-microm) after grayscale noise was added to the projection images before reconstruction so as to mimic the effect of retaining the same radiation exposure involved in the multislice computed tomographic scan. RESULTS: At voxel sizes of (20-microm) or smaller, iron deposits could be identified based on CT grayscale value. Voxels of (100-microm) or larger cannot resolve nor distinguish iron deposits from calcifications by virtue of CT grayscale value. CONCLUSIONS: Clinical CT scanners cannot be expected to discriminate iron deposits from calcifications by their CT value alone in the arterial wall.

Vasa vasorum neovascularization and lesion distribution among different vascular beds in ApoE-/-/LDL-/- double knockout mice.

OBJECTIVE: To increase understanding of the substantial variation in the incidence and distribution of atherosclerotic lesions among different vascular beds. In view of some evidence that there are different distributions of adventitial vasa vasorum (VV) in different vascular beds, and that this correlates with lesion formation, we explored this possible linkage in apoE-/-/LDL-/- double knockout mice, which develop VV at age beyond 16 weeks. METHODS AND RESULTS: Samples from the aorta, coronary, pulmonary, carotid, and cerebral arteries in apoE-/-/LDL-/- double knockout mice at the age of 16-80 weeks (n=24) were scanned by micro-CT. Using those 3D images, we characterized plaque volume, vessel luminal diameter and VV luminal volume along the vessels. Results were complemented by histology. Advanced atherosclerotic lesions were found in the aorta, pulmonary artery and carotid artery. Occluded intramyocardial vessels (vessel diameter approximately 0.1mm) with concomitant myocardial infarctions were found without any evidence of adventitial VV neovascularization. VV luminal volume follows the order: aorta>pulmonary arteries>carotid arteries. VV were only observed in atherosclerotic diseased vessels with a lumen diameter>0.4mm. No atherosclerotic lesions, and no VV, were observed in cerebral arteries. CONCLUSION: The spatial heterogeneity in the development of atherosclerotic lesions among different vascular beds is linked to appearance of VV and to vessel lumen diameter.

Vasa vasorum and atherosclerosis - Quid novi?

The role of vasa vasorum (VV) in atherosclerosis is hotly debated, and new experimental techniques have recently opened an opportunity to take a fresh look at this important topic. Although the proliferation of VV due to atherogenic stimuli is controversial, experimental and clinical evidence strongly suggest the potential of VV in vascular proliferative disorders. In the past, paradigms of atherosclerosis and restenosis have excluded the adventitia and VV in the artery wall due, in part, to a lack of i) appropriate animal models featuring adventitial VV neovascularization, ii) imaging technologies to quantitate adventitial VV and plaque neovascularization and iii) its consequences, concerning information on detectable plaque substrate in vulnerable lesions. VV proliferation is associated with increasing plaque burden and is linked to cellular processes which are critical during the development of atherosclerotic plaques such as inflammation, plaque perfusion and concomitant intraplaque hemorrhage - but the regulation and induction of VV based on pathological settings are poorly understood. This review discusses the current scientific status and its controversies and identifies open research questions.

Quantitative X-ray imaging of intraplaque hemorrhage in aortas of apoE(-/-)/LDL(-/-) double knockout mice.

OBJECTIVES: To determine if hemorrhage into an arterial wall can be detected in CT images by virtue of the iron content. MATERIALS AND METHODS: Aortas from male apoE(-/-)/LDL(-/-) mice (n = 31) were infused in situ with contrast agent, for micro-CT scanning and histology. Roentgen-opacities within the aortic walls were identified by histology and micro-x-ray fluorescence to be iron or calcium. Dual-energy scanning was performed at 2 energy levels using synchrotron-based micro-CT [(2 microm)(3) voxels, 16 and 20 keV] and 64-slice CT (0.4 x 0.4 x 0.6 mm voxels, 80 and 120 kVp). RESULTS: Opacities were identified as hemorrhage-related clusters of multiple punctate deposits, containing both Fe (0.48 x 10(-12) g/voxel) and Ca (3.18 x 10(-2) g/voxel), or as isolated confluent accumulations of exclusively calcium. Subtraction of the dual-energy CT scans discriminated iron from calcium deposits. CONCLUSION: Detection and quantification of iron deposits in hemorrhaged atherosclerotic lesions is feasible by dual-energy CT imaging.