Lipocalin-2 as a fundamental protein in type 2 diabetes and periodontitis in mice.

BACKGROUND: Lipocalin-2 (LCN-2) is an osteokine that suppresses appetite, stimulates insulin secretion, regulates bone remodeling, and is induced by proinflammatory cytokines. The aim of this work was to investigate the participation of LCN-2 in periodontitis associated with type 2 diabetes (T2D) by evaluating alveolar bone loss, glycemic control, inflammation, and femur fragility. METHODS: A murine model of periodontitis with T2D and elevated LCN-2 concentration was used. Functional LCN-2 inhibition was achieved using an anti-LCN-2 polyclonal antibody, and isotype immunoglobulin G was used as a control. The alveolar bone and femur were evaluated by micro-CT. Glucose metabolism was determined. Tumor necrosis factor (TNF-α) and receptor activator of nuclear factor kappa-B ligand (RANKL) levels in alveolar bone lysates were quantified using ELISA, and serum cytokines were quantified using flow cytometry. A three-point bending test was performed in the femur, and RANKL levels were measured in femur lysates using ELISA. RESULTS: Functional inhibition of LCN-2 in T2D-periodontitis mice decreased alveolar bone loss in buccal and palatal surfaces and preserved the microarchitecture of the remaining bone, decreased TNF-α and RANKL in alveolar bone, reduced hyperglycemia, glucose intolerance, and insulin resistance, and increased insulin production through improving the functionality of pancreatic ß cells. Furthermore, this inhibition increased serum free-glycerol levels, decreased serum interleukin (IL)-6, increased serum IL-4, and reduced femur fragility and RANKL expression in the femur. CONCLUSIONS: LCN-2 participates in periodontitis associated with T2D. Inhibiting its function in mice with T2D and periodontitis improves pancreatic ß-cell function, and glucose metabolism and decreases inflammatory cytokines and bone-RANKL levels, which results in the preservation of femoral and alveolar bone microarchitecture. PLAIN LANGUAGE SUMMARY: In this study, we explored the role of a bone protein known as lipocalin-2 (LCN-2) in the connection between periodontitis and type 2 diabetes (T2D). Periodontitis is a destructive gum and alveolar bone disease. LCN-2 levels are increased in both T2D and periodontitis. Using a mouse model of T2D with periodontitis, we examined how blocking LCN-2 function affected various aspects of these two diseases. We found that this inhibition led to significant improvements. First, it reduced alveolar bone loss and preserved bone structure by decreasing local inflammation and bone resorption. Second, it improved glucose and lipid metabolism, leading to better blood-sugar control and decreased insulin resistance. Blocking the functions of LCN-2 also decreased systemic inflammation throughout the body and strengthened bone integrity. Overall, our results suggest that LCN-2 plays a crucial role in the periodontitis associated with T2D. By inhibiting LCN-2 function, we were able to improve pancreatic function, improve glucose metabolism, reduce inflammation, and enhance bone health. Targeting LCN-2 could be a promising strategy for the harmful effects of T2D and periodontitis.

Crystal scatter effects in a large-area dual-panel Positron Emission Mammography system.

Positron Emission Mammography (PEM) is a valuable molecular imaging technique for breast studies using pharmaceuticals labeled with positron emitters and dual-panel detectors. PEM scanners normally use large scintillation crystals coupled to sensitive photodetectors. Multiple interactions of the 511 keV annihilation photons in the crystals can result in event mispositioning leading to a negative impact in radiopharmaceutical uptake quantification. In this work, we report the study of crystal scatter effects of a large-area dual-panel PEM system designed with either monolithic or pixelated lutetium yttrium orthosilicate (LYSO) crystals using the Monte Carlo simulation platform GATE. The results show that only a relatively small fraction of coincidences (~20%) arise from events where both coincidence photons undergo single interactions (mostly through photoelectric absorption) in the crystals. Most of the coincidences are events where at least one of the annihilation photons undergoes a chain of Compton scatterings: approximately 79% end up in photoelectric absorption while the rest (<1%) escape the detector. Mean positioning errors, calculated as the distance between first hit and energy weighted (assigned) positions of interaction, were 1.70 mm and 1.92 mm for the monolithic and pixelated crystals, respectively. Reconstructed spatial resolution quantification with a miniDerenzo phantom and a list mode iterative reconstruction algorithm shows that, for both crystal types, 2 mm diameter hot rods were resolved, indicating a relatively small effect in spatial resolution. A drastic reduction in peak-to-valley ratios for the same hot-rod diameters was observed, up to a factor of 14 for the monolithic crystals and 7.5 for the pixelated ones.

Aerobic training improves bone fragility by reducing the inflammatory microenvironment in bone tissue in type 2 diabetes.

Aerobic training (AT) is indicated in type 2 diabetes mellitus (T2DM) to control hyperglycaemia and inflammation. AT improves bone microarchitecture and resistance to fracture. The intensity of AT and the mechanisms that lead to the improvement in bone quality are still unknown. Using a mouse model of T2DM, we evaluated the effects of two intensities of forced AT. We divided mice into: sedentary (SED), T2DM-SED, low runners (LOW), T2DM-LOW, high runners (HIGH) and T2DM-HIGH. The AT for low was 8 m/minute (m/min); 5° slope or high 18 m/min; 15° slope for 2 months. We measured metabolic parameters, the serum cytokines concentration, lipocalin-2 (LCN-2) and adiponectin; and the tibial concentrations of LCN-2, tumour necrosis factor alpha (TNF-α) and protein carbonylation (CO). We evaluated femur morphometry and biomechanical properties. We performed multiple correlation analysis. The T2DM-LOW versus T2DM-SED group, shown an increase of interleukin (IL)-10 (417 ± 90 vs 102 ± 25 pg/mL) and improved trabecular bone (BV/TV: 31.8 ± 2.3 vs 19.25 ± 1.4%; Tb.Sp.: 1.62 ± 0.02 vs 2.0 ± 0.07 mm), by a decrease bone CO (3.4 ± 0.1 vs 6.0 ± 0.5 nmol/mg), bone TNF-α (84 ± 4 vs 239 ± 13 pg/mL) and LCN-2 (2887 ± 23 vs 3418 ± 105 pg/mL). The T2DM-HIGH versus T2DM-SED group showed a greater hypoglycaemic effect (228 ± 10 vs 408 ± 5 mg/dL), with improved cortical bone density (0.26 ± 0.012 vs 0.21 ± 0.007 mm) and fracture resistance (102 ± 8 vs 78 ± 5 MPa), by a reduction of bone TNF-α (77 ± 34 vs 239 ± 13 pg/mL); LCN-2 (2768 ± 20 vs 3418 ± 105 pg/mL) and CO (4.8 ± 0.5 vs 6.0 ± 0.5 nmol/mg). In conclusion, AT improves bone morphometry and biomechanical properties by reducing the bone inflammatory microenvironment.

Moderate aerobic exercise on bone quality changes associated with aging and oxidative stress in BALB/c mice.

Exercise encourages active and healthy aging, maintaining functional and physical capabilities. This study aimed to assess the effects of a long-term moderate aerobic exercise protocol on bone microarchitecture and fragility associated with chronic inflammation and oxidative stress in aging. Male BALB/c mice (n = 10 per group) underwent a moderate exercise protocol from 13 weeks to 27 (adulthood age) or 108 weeks of age (elderly age) and were then sacrificed. Age-match sedentary mice were included as a control group. Serum cortisol concentrations were determined by chemiluminescent immunoassay, C-reactive protein (CRP) by a turbidimetric assay, advanced glycation end-products (AGEs) and malondialdehyde (MDA) by fluorescent spectroscopy, and total glutathione (GSH) by colorimetric method. The right femur was dissected formorphometric and densitometricanalysis bycomputerized microtomography (µCT),and biomechanical properties were assessed usinga three-point bending device. Musclefrom the same extremitywas obtained to determine relative mRNA expression ofpro-inflammatory cytokines (TNF-α and IL-6) by RT-qPCR.Statistical differences were evaluated by two-way ANOVA and Holm-Sidak method post hoc with P < 0.05. In elderly mice, moderate exercise increased glutathione levels and microarchitecture complexity but decreased bone fragility and oxidative stress markers, cortisol, and pro-inflammatory cytokines. In conclusion, these results suggest a strong link between a pro-inflammatory state and age-conditioned oxidative stress on bone quality. Thus, on a human scale, moderate aerobic exercise may improve bone quality during aging.

A dedicated phantom design for positron emission mammography performance evaluation.

A standard protocol for performance evaluation of positron emission mammography (PEM) systems has not yet been established. In this work we propose a methodology based on the design of specific phantoms for this imaging modality with component dimensions in accordance with typical breast lesion sizes together with the adaptation of current international protocols designed for clinical and preclinical positron emission tomographs (PET) systems. This methodology was used to evaluate the performance of the Flex Solo II PEM scanner in terms of spatial resolution, uniformity and contrast lesion detectability, recovery coefficients and spill-over ratios. Positron range effects were studied with 18F and 68Ga, which have very different energy spectra. Our results indicate that in-plane spatial resolution of the system is around 3.0 mm and 4.4 mm for 18F and 68Ga, respectively. Lesion detectability tests with sphere diameters between 4 and 10 mm confirmed that the PEM system can resolve all the spheres (hot or cold). Percent contrast values for 18F lie between 6%-38% and 34%-51% for hot- and cold- spheres, respectively; the corresponding intervals for 68Ga are lower, 4%-25% and 32%-44%. Regarding uniformity quantification, the system shows percentage standard deviations within 4.9%-5.7%, while the percent background variability measurements ranged between 6.7% and 10.9% for both radionuclides. Recovery coefficients measured with hot rod diameters between 1.5 and 9 mm, have values between 0.2-1.05 and 0.17-0.69 for 18F and 68Ga, respectively. Spill-over ratios have large values (0.22 in average) for both radionuclides. Our results indicate that the phantoms and the methodology developed in this work can serve as the basis for establishing an image quality protocol for the systematic evaluation of PEM systems, with a potential extension for performance evaluation of dedicated breastPET scanners.

Small photon beam measurements using radiochromic film and Monte Carlo simulations in a water phantom.

This work reports the use of both GafChromic EBT film immersed in a water phantom and Monte Carlo (MC) simulations for small photon beam stereotactic radiosurgery dosimetry. Circularly collimated photon beams with diameters in the 4-20 mm range of a dedicated 6 MV linear accelerator (Novalis, BrainLAB, Germany) were used to perform off-axis ratios, tissue maximum ratios and total scatter factors measurements, and MC simulations. GafChromic EBT film data show an excellent agreement with MC results (<2.7%) for all measured quantities.

Radiation transmission, leakage and beam penumbra measurements of a micro-multileaf collimator using GafChromic EBT film.

Micro-multileaf collimator systems coupled to linear accelerators for radioneurosurgery treatments require a rigorous dosimetric characterization in order to be used in 3D conformal and intensity modulated stereotactic radiosurgery and radiotherapy applications. This characterization involves high precision measurements of leaf transmission, leakage and beam penumbra through the collimation system and requires the use of detectors with high spatial resolution, high sensitivity and practically no energy dependence. In this work the use of GafChromic EBT radiochromic film to measure the basic dosimetric properties of the m3-mMLC (BrainLAB, Germany) micro-multileaf collimator system integrated to a 6 MV linear accelerator, is reported. Results show that average values of transmission and leakage radiation are 0.93 +/- 0.05% and 1.08 +/- 0.08%, respectively. The 80-20% beam penumbra were found to be 2.26 +/- 0.11 mm along the leaf side (perpendicular to leaf motion) and 2.31 +/- 0.11 mm along the leaf end (parallel to leaf motion) using square field sizes ranging from 9.1 to 1.8 cm. These measurements are in agreement with values reported in the literature for the same type of mMLC using different radiation detectors.

Spatial dose distributions in solid tumors from 186Re transported by liposomes using HS radiochromic media.

PURPOSE: A procedure for the measurement of spatial dose rate distribution of beta particles emitted by 186Re-liposomes in tumoral tissue, using HS GafChromic films, is presented. METHODS: HNSCC xenografts were intratumorally injected with 3.7 or 11.1 MBq of 186Re-liposomes, and planar gamma camera images were acquired to determine the liposome retention in the tumor. After imaging, rats were sacrificed and tumors were excised and processed in slices; HS film sections were placed between slices and the tumor lobe was reassembled. Tumors and films were kept in the dark at 4 degrees C for 18 h. After irradiation, films were removed and response was read using a transmission scanner. Films were analyzed to determine two-dimensional spatial dose rate distributions and cumulative dose volume histograms. Dose rate distributions were quantified using a 60Co calibration curve, the 186Re physical half-life, and a perturbation factor that takes into account the effect of the film protective layer. RESULTS: Dose rate distributions are highly heterogeneous with maximal dose rates about 0.4 Gy h(-1) in tumors injected with 3.7 MBq and 1.3 Gy h(-1) in tumors injected with 11.1 MBq. Dose volume histograms showed dose distributed in more than 95% and 80% of the tumor when injected with the lower and the higher activity, respectively. CONCLUSION: The described procedures and techniques have shown the potential and utility of HS GafChromic film for determination of dose rate distributions in solid tumors injected intratumorally with 186Re-liposomes. The film's structure and the liposomes' biodistribution must be taken into account to obtain quantitative dose measurements.