Lung diseases such as fibrosis, asthma, cystic fibrosis, infection and cancer are life-threatening conditions that slowly deteriorate quality of life and for which our diagnostic power is high, but ...our knowledge on etiology and/or effective treatment options still contains important gaps. In the context of day-to-day practice, clinical and preclinical studies, clinicians and basic researchers team up and continuously strive to increase insights into lung disease progression, diagnostic and treatment options. To unravel disease processes and to test novel therapeutic approaches, investigators typically rely on end-stage procedures such as serum analysis, cyto-/chemokine profiles and selective tissue histology from animal models. These techniques are useful but provide only a snapshot of disease processes that are essentially dynamic in time and space. Technology allowing evaluation of live animals repeatedly is indispensable to gain a better insight into the dynamics of lung disease progression and treatment effects. Computed tomography (CT) is a clinical diagnostic imaging technique that can have enormous benefits in a research context too. Yet, the implementation of imaging techniques in laboratories lags behind. In this review we want to showcase the integrated approaches and novel developments in imaging, lung functional testing and pathological techniques that are used to assess, diagnose, quantify and treat lung disease and that may be employed in research on patients and animals. Imaging approaches result in often novel anatomical and functional biomarkers, resulting in many advantages, such as better insight in disease progression and a reduction in the numbers of animals necessary. We here showcase integrated assessment of lung disease with imaging and histopathological technologies, applied to the example of lung fibrosis. Better integration of clinical and preclinical imaging technologies with pathology will ultimately result in improved clinical translation of (therapy) study results.
Ionizing radiation constitutes a health risk to imaging scientists and study animals. Both PET and CT produce ionizing radiation. CT doses in pre-clinical
imaging typically range from 50 to 1,000 mGy ...and biological effects in mice at this dose range have been previously described.
FFDG body doses in mice have been estimated to be in the range of 100 mGy for
FFDG. Yearly, the average whole body doses due to handling of activity by PET technologists are reported to be 3-8 mSv. A preclinical PET/CT system is presented with design features which make it suitable for small animal low-dose imaging. The CT subsystem uses a X-source power that is optimized for small animal imaging. The system design incorporates a spatial beam shaper coupled with a highly sensitive flat-panel detector and very fast acquisition (<10 s) which allows for whole body scans with doses as low as 3 mGy. The mouse total-body PET subsystem uses a detector architecture based on continuous crystals, coupled to SiPM arrays and a readout based in rows and columns. The PET field of view is 150 mm axial and 80 mm transaxial. The high solid-angle coverage of the sample and the use of continuous crystals achieve a sensitivity of 9% (NEMA) that can be leveraged for use of low tracer doses and/or performing rapid scans. The low-dose imaging capabilities of the total-body PET subsystem were tested with NEMA phantoms, in tumor models, a mouse bone metabolism scan and a rat heart dynamic scan. The CT imaging capabilities were tested in mice and in a low contrast phantom. The PET low-dose phantom and animal experiments provide evidence that image quality suitable for preclinical PET studies is achieved. Furthermore, CT image contrast using low dose scan settings was suitable as a reference for PET scans. Total-body mouse PET/CT studies could be completed with total doses of <10 mGy.
Complete mechanical preparation of the root canal system is rarely achieved. Therefore, the purpose of this study was to evaluate and compare the root canal shaping efficacy of ProTaper rotary files ...and standard stainless steel K-files using micro-computed tomography.
Sixty extracted upper second premolars were selected and divided into 2 groups of 30 teeth each. Before preparation, all samples were scanned by micro-computed tomography. Thirty teeth were prepared with the ProTaper system and the other 30 with stainless steel files. After preparation, the untouched surface and root canal straightening were evaluated with micro-computed tomography. The percentage of untouched root canal surface was calculated in the coronal, middle, and apical parts of the canal. We also calculated straightening of the canal after root canal preparation. Results from the 2 groups were statistically compared using the Minitab statistical package.
ProTaper rotary files left less untouched root canal surface compared with manual preparation in coronal, middle, and apical sector (p<0.001). Similarly, there was a statistically significant difference in root canal straightening after preparation between the techniques (p<0.001).
Neither manual nor rotary techniques completely prepared the root canal, and both techniques caused slight straightening of the root canal.
Endochondral ossification, an important process in vertebrate bone formation, is highly dependent on correct functioning of growth plate chondrocytes
. Proliferation of these cells determines ...longitudinal bone growth and the matrix deposited provides a scaffold for future bone formation. However, these two energy-dependent anabolic processes occur in an avascular environment
. In addition, the centre of the expanding growth plate becomes hypoxic, and local activation of the hypoxia-inducible transcription factor HIF-1α is necessary for chondrocyte survival by unidentified cell-intrinsic mechanisms
. It is unknown whether there is a requirement for restriction of HIF-1α signalling in the other regions of the growth plate and whether chondrocyte metabolism controls cell function. Here we show that prolonged HIF-1α signalling in chondrocytes leads to skeletal dysplasia by interfering with cellular bioenergetics and biosynthesis. Decreased glucose oxidation results in an energy deficit, which limits proliferation, activates the unfolded protein response and reduces collagen synthesis. However, enhanced glutamine flux increases α-ketoglutarate levels, which in turn increases proline and lysine hydroxylation on collagen. This metabolically regulated collagen modification renders the cartilaginous matrix more resistant to protease-mediated degradation and thereby increases bone mass. Thus, inappropriate HIF-1α signalling results in skeletal dysplasia caused by collagen overmodification, an effect that may also contribute to other diseases involving the extracellular matrix such as cancer and fibrosis.
The aim of this study was to evaluate and compare the shaping ability of XP-endo Shaper (XP; FKG Dentaire, La Chaux-de-Fonds, Switzerland) and TRUShape (TS; Dentsply/Tulsa Dental Specialties, Tulsa, ...OK) during the preparation of moderated curved root canals using micro–computed tomographic imaging.
Twenty human maxillary premolars with 2 roots were randomly separated into 2 groups of 10 teeth, which were scanned before and after root canal preparation using the SkyScan 1275 X-ray microtomograph (Bruker micro-CT, Kontich, Belgium) at a nominal resolution of <4 μm. Premolars and irrigant were maintained at 37° before and during preparation; group 1 was treated using XP and group 2 with TS. After preparation, researchers measured the amount of dentin removed, untreated superficies of canal walls, root canal volume, degree of canal transportation, and centering ability. Values of central tendency and dispersion were calculated using Statgraphics Centurion XV software (StatPoint Technologies, Inc, Warrenton, VA); means and median were compared using the Mann-Whitney-Wilcoxon test. The level of significance was set at 5% (P < .05).
No significant statistical differences were observed between the 2 groups in shaping ability, untreated superficies of canal walls, degree of canal transportation, and centering ability (P > .05).
Instrumentation of moderately curved root canals using the XP single file and the TS file system were equally effective. XP and TS maintained the original anatomy of the root canals and showed a similar percentage of untreated canal walls, centered ability, and minimal apical transportation.
Purpose
To assess bone microarchitecture in maxillary sites grafted with autogenous or xenogenous grafts as well as to demonstrate the usefulness of microCT in dental implant research.
Materials and ...Methods
Samples (n = 12) consisting of titanium fixation screws covered by at least 0.5–1 mm of human bone were obtained from 17 sites grafted with autogenous or xenogenous materials and prepared for microCT scanning and conventional histology. Bone histomorphometric parameters were evaluated in three distinct regions (graft region, transitional region, and native bone region). Three‐dimensional (3D) bone‐to‐implant contact (BIC) calculation was performed using microCT data. Histological sections were used to calculate two‐dimensional (2D) BIC percentages, which were compared with values obtained from 2D microCT images.
Results
Histomorphometric parameters varied according to the type of graft used, but sites reconstructed with autogenous bone showed higher mean values in general. In autograft samples, indices for parameters such as Tb.Th and Tb.Sp were significantly different when the native bone region was compared to the graft region. While a higher mean 3D BIC was found in the native bone region for both graft materials, significant BIC differences were absent when graft types were compared. The 2D BIC percentages obtained from histological and microCT images were similar.
Conclusions
Autografts outperformed the xenogenous material used in this study concerning the histomorphometric parameters assessed. While graft type did not seem to influence 3D BIC, the native bone region showed the highest BIC percentages when compared to the other regions in both graft groups. In addition, 2D BIC ratios were similar regardless of graft material or image source (histological sections x microCT slices). Taken together, our findings suggest that microCT is an effective tool for 2D and 3D histomorphometric and BIC assessments in dental implant research.
Multimodal pore formation in calcium phosphate cements Lodoso‐Torrecilla, Irene; van Gestel, Nicole A. P.; Diaz‐Gomez, Luis ...
Journal of biomedical materials research. Part A,
February 2018, Letnik:
106, Številka:
2
Journal Article
Abstract Root canal morphology can be changed after root canal preparation depending on the technique used. ...the object of this study was to use micro-CT to investigate the shaping ability of the ...ProTaper rotary system and stainless steel manual files in permanent premolars. Micro-CT imaging was initially used for evaluating tooth morphology, surface area and volume changes,10,11 but more recently it has been used to study canal curvature,12 the percentage of instrumented canal wall,6,13,14 and volume changes within the tooth.15 Although micro-CT is not available for clinical dental use, it is an important technique in 3D dental research.16 From 3D color coded images, researchers can determine morphological changes in the root canal system after instrumentation.17 Therefore, the object of this study was to use micro-CT to investigate the shaping ability of the ProTaper rotary system and stainless steel manual files in permanent premolars. By adapting the shaping of the root canal to its anatomy, procedural errors can be overcome to achieve correct mechanical cleaning and disinfection.18-21 The clinical importance of a correctly-shaped root canal is well described in the guideline published by the European Society of Endodontics, which states that instrumentation should extend to the entire wall of the canal, so that it is completely cleaned and shaped.22 Investigators have demonstrated that the dentin in the root canal wall is infected with microorganisms and their endotoxins, extending to a depth of 1-2 mm.23,24 The results of the current study showed significant differences in the diameter, surface area and volume after root canal preparation with the ProTaper technique. Similar results were reported by Al Jabbari et al.,who observed significant differences in the geometrical characteristics between endodontic files with different ISO sizes.25 A gradual increase in the diameter along the length of the canal was noted by Li et al., who showed that canal volume and surface area of all teeth increased by 5-146% after instrumentation, depending on the root canal type.17 The instrumentation of root canals to retain their anatomy and ensure the least amount of dentin removal is a challenge, depending on the system used.26 As reported by Yang et al., root canal instrumentation with ProTaper universal and Mtwo, both Ni-Ti instrument systems, resulted in significantly increased root canal volume and surfaces area.27 Uýanik et al. reported that the ProTaper system removed more dentin than the Hero Shaper and RaCe systems.28 The effect of root canal instrumentation is also related to the preoperative canal geometry.
Abstract
Purpose
To assess bone microarchitecture in maxillary sites grafted with autogenous or xenogenous grafts as well as to demonstrate the usefulness of micro
CT
in dental implant research.
...Materials and Methods
Samples (
n
= 12) consisting of titanium fixation screws covered by at least 0.5–1 mm of human bone were obtained from 17 sites grafted with autogenous or xenogenous materials and prepared for micro
CT
scanning and conventional histology. Bone histomorphometric parameters were evaluated in three distinct regions (graft region, transitional region, and native bone region). Three‐dimensional (3D) bone‐to‐implant contact (
BIC
) calculation was performed using micro
CT
data. Histological sections were used to calculate two‐dimensional (2D) BIC percentages, which were compared with values obtained from 2D micro
CT
images.
Results
Histomorphometric parameters varied according to the type of graft used, but sites reconstructed with autogenous bone showed higher mean values in general. In autograft samples, indices for parameters such as Tb.Th and Tb.Sp were significantly different when the native bone region was compared to the graft region. While a higher mean 3D
BIC
was found in the native bone region for both graft materials, significant
BIC
differences were absent when graft types were compared. The 2D
BIC
percentages obtained from histological and micro
CT
images were similar.
Conclusions
Autografts outperformed the xenogenous material used in this study concerning the histomorphometric parameters assessed. While graft type did not seem to influence 3D
BIC
, the native bone region showed the highest
BIC
percentages when compared to the other regions in both graft groups. In addition, 2D
BIC
ratios were similar regardless of graft material or image source (histological sections x micro
CT
slices). Taken together, our findings suggest that micro
CT
is an effective tool for 2D and 3D histomorphometric and
BIC
assessments in dental implant research.
Smads are intracellular signaling proteins that transduce signals elicited by members of the transforming growth factor (TGF)-β superfamily. Smad5 and Smad1 are highly homologous, and they mediate ...primarily bone morphogenetic protein (Bmp) signals. We used the Cre-loxP system and Sm22-Cre and Tie-1-Cre mice to study the function of Smad5 in the developing blood vessel wall. Analysis of embryos demonstrated that deletion of Smad5 in endothelial or smooth muscle cells resulted in a normal organization of embryonic and extra-embryonic vasculature. Angiogenic assays performed in adult mice revealed that mutant mice display a comparable angiogenic and vascular remodeling response to control mice. In Sm22-Cre;Smad5 fl/ − mice, Smad5 is also deleted in cardiomyocytes. Echocardiographic analysis on those 9-month-old female mice demonstrated larger left ventricle internal diameters and decreased fractional shortening compared with control littermates without signs of cardiac hypertrophy. The decreased cardiac contractility was associated with a decreased performance in a treadmill experiment. In isolated cardiomyocytes, fractional shortening was significantly reduced compared with control cells. These data demonstrate that restricted deletion of Smad5 in the blood vessel wall results in viable mice. However, loss of Smad5 in cardiomyocytes leads to a mild heart defect.
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