Combined Delivery of Two Different Bioactive Factors Incorporated in Hydroxyapatite Microcarrier for Bone Regeneration

BACKGROUND@#The delivery of growth factors using a carrier system presents a promising and innovative tool in tissue engineering and dentistry today. Two of the foremost bioactive factors, bone morphogenetic protein-2 and vascular endothelial growth factor (VEGF), are widely applied using a ceramic scaffold. The aim of this study was to determine the use of hydroxyapatite microcarrier (MC) for dual delivery of osteogenic and angiogenic factors to accelerate hard tissue regeneration during the regenerative process. @*METHODS@#Two MCs of different sizes were fabricated by emulsification of gelatin and alpha-tricalcium phosphate (a-TCP).The experimental group was divided based on the combination of MC size and growth factors. For investigating the in vitro properties, rat mesenchymal stem cells (rMSCs) were harvested from bone marrow of the femur and tibia. For in vivo experiments, MC with/without growth factors was applied into the standardized, 5-mm diameter defects, which were made bilaterally on the parietal bone of the rat. The animals were allowed to heal for 8 weeks, and samples were harvested and analyzed by microcomputed tomography and histology. @*RESULTS@#Improved proliferation of rat mesenchymal stem cells was observed with VEGF loaded MC. For osteogenic differentiation, dual growth factors delivered by MC showed higher osteogenic gene expression, alkaline phosphatse production and calcium deposition. The in vivo results revealed statistically significant increase in new bone formationwhen dual growth factors were delivered by MC. Dual growth factors administered on a calcium phosphate matrix showed significantly enhanced osteogenic potential. @*CONCLUSION@#We propose this system has potential clinical utility in providing solutions for craniofacial bone defects, with the added benefit of early availability.

Preclinical Voxel-Based Dosimetry in Theranostics: a Review / 대한핵의학회잡지

Due to the increasing use of preclinical targeted radionuclide therapy (TRT) studies for the development of novel theranosticagents, several studies have been performed to accurately estimate absorbed doses to mice at the voxel level using referencemouse phantoms and Monte Carlo (MC) simulations. Accurate dosimetry is important in preclinical theranostics to interpretradiobiological dose-response relationships and to translate results for clinical use. Direct MC (DMC) simulation is believed toproduce more realistic voxel-level dose distribution with high precision because tissue heterogeneities and nonuniform sourcedistributions in patients or animals are considered. Although MC simulation is considered to be an accurate method for voxelbasedabsorbed dose calculations, it is time-consuming, computationally demanding, and often impractical in daily practice. Inthis review, we focus on the current status of voxel-based dosimetry methods applied in preclinical theranostics and discuss theneed for accurate and fast voxel-based dosimetry methods for pretherapy absorbed dose calculations to optimize the dosecomputation time in preclinical TRT.

Combined Delivery of Two Different Bioactive Factors Incorporated in Hydroxyapatite Microcarrier for Bone Regeneration

BACKGROUND@#The delivery of growth factors using a carrier system presents a promising and innovative tool in tissue engineering and dentistry today. Two of the foremost bioactive factors, bone morphogenetic protein-2 and vascular endothelial growth factor (VEGF), are widely applied using a ceramic scaffold. The aim of this study was to determine the use of hydroxyapatite microcarrier (MC) for dual delivery of osteogenic and angiogenic factors to accelerate hard tissue regeneration during the regenerative process. @*METHODS@#Two MCs of different sizes were fabricated by emulsification of gelatin and alpha-tricalcium phosphate (a-TCP).The experimental group was divided based on the combination of MC size and growth factors. For investigating the in vitro properties, rat mesenchymal stem cells (rMSCs) were harvested from bone marrow of the femur and tibia. For in vivo experiments, MC with/without growth factors was applied into the standardized, 5-mm diameter defects, which were made bilaterally on the parietal bone of the rat. The animals were allowed to heal for 8 weeks, and samples were harvested and analyzed by microcomputed tomography and histology. @*RESULTS@#Improved proliferation of rat mesenchymal stem cells was observed with VEGF loaded MC. For osteogenic differentiation, dual growth factors delivered by MC showed higher osteogenic gene expression, alkaline phosphatse production and calcium deposition. The in vivo results revealed statistically significant increase in new bone formationwhen dual growth factors were delivered by MC. Dual growth factors administered on a calcium phosphate matrix showed significantly enhanced osteogenic potential. @*CONCLUSION@#We propose this system has potential clinical utility in providing solutions for craniofacial bone defects, with the added benefit of early availability.

Workplace violence experienced by emergency department workers and its association with stress and depression assessment

OBJECTIVE: This study examined the incidence of workplace violence (WPV) in an emergency department (ED), and its influence on ED workers' mental health. METHODS: A cross-sectional, anonymous survey was conducted on ED workers employed in a local emergency medical center during August 2018. The survey respondents' data on the demographic characteristics, WPV episode, Korean-translated Brief Encounter Psychosocial Instrument (BEPSI-K), stress questionnaire for Korean National Health and Nutrition Examination Survey (KNHANES), and Patient Health Questionnaire-9 (PHQ-9) were obtained. The results of the stress (BEPSI-K, KNHANES) and depression (PHQ-9) score were compared with the WPV experience of ED workers. RESULTS: A total of 104 of 120 ED workers (86.7%) were exposed to WPV. ED workers that experienced physical violence within the past year had higher KNHANES, BEPSI-K, and PHQ-9 than the workers, who did not experience such violence (P≤0.001). In addition, this survey demonstrated that a physical violence episode within the past year was associated with above moderate depression (P≤0.001; odds ratio, 19.597). CONCLUSION: Recent physical violence can cause psychiatric disorders in ED workers, such as depression or stress disorder. Therefore, policies are needed to prevent WPV in ED and support ED workers who have experienced WPV.

Evaluation of the periodontal regenerative properties of patterned human periodontal ligament stem cell sheets

PURPOSE: The aim of this study was to determine the effects of patterned human periodontal ligament stem cell (hPDLSC) sheets fabricated using a thermoresponsive substratum. METHODS: In this study, we fabricated patterned hPDLSC sheets using nanotopographical cues to modulate the alignment of the cell sheet. RESULTS: The hPDLSCs showed rapid monolayer formation on various surface pattern widths. Compared to cell sheets grown on flat surfaces, there were no significant differences in cell attachment and growth on the nanopatterned substratum. However, the patterned hPDLSC sheets showed higher periodontal ligamentogenesis-related gene expression in early stages than the unpatterned cell sheets. CONCLUSIONS: This experiment confirmed that patterned cell sheets provide flexibility in designing hPDLSC sheets, and that these stem cell sheets may be candidates for application in periodontal regenerative therapy.

Surveyor assay to diagnose persistent Müllerian duct syndrome in Miniature Schnauzers

Persistent Müllerian duct syndrome (PMDS) is a pseudohermaphroditism in males characterized by the presence of Müllerian duct derivatives. As PMDS dogs often lack clinical symptoms, a molecular diagnosis is essential to identify the syndrome in these animals. In this study, a new molecular method using DNA mismatch-specific Surveyor nuclease was developed. The Surveyor nuclease assay identified the AMHR2 mutation that produced PMDS in a Miniature Schnauzer as accurately as that obtained by using the conventional method based on restriction digestion. As an alternative to the current molecular diagnostic method, the new method may result in increased accuracy when detecting PMDS.

Intrusion phenomenon of natural tooth bounded by implant-prostheses: a clinical report / 대한치과보철학회지

In case of implant-tooth connected prosthesis, a natural tooth tends to intrude. There are several mechanisms that explain an intrusion phenomenon. So it is reco mmended not to connect an implant with a natural tooth. A 68-year-old female had upper left 2nd premolar and 2nd molar extracted and underwent implant surgery on the missing area. We made an implant prosthesis and treated upper left 1st molar with a gold crown. 2.5 year later, the patient complained about loose proximal contact and food impaction between upper left 1st molar and 2nd molar. Mesial side of upper left 2nd molar implant prosthesis was soldered so that proximal contact became tight again. But after 7 months, about 2 mm intrusion of upper left 1st molar occurred, and the patient felt periodontally originated pain on intruded upper left 1st molar. After the gold crown on upper left 1st molar was removed, extrusion occurred and pain was relived.

Small Animal PET Imaging Study of 68Ga-BAPEN / 의학물리

The purpose of this study was to analyze 68Ga-BAPEN dynamic PET image in rat myocardium to evaluate potential of this radiotracer as a perfusion imaging agent. Animal PET/CT scan was done in 9 rats during 120 minutes. Especially we synthesized 68Ga-BAPEN with kit which is simple and low cost method. PET images showed the in vivo dynamic distribution of 68Ga-BAPEN in the chest region of rats. Initially 68Ga-BAPEN PET images showed aorta and liver activities and a few minutes later, 68Ga-BAPEN moved to myocardium. Regions of interest were drawn on myocardium, liver, lung and blood pool. Time-activity curves showed significant uptake of 68Ga-BAPEN in myocardium. The contrast ratios of myocardial to blood pool, lung and liver at 60 minutes after injection were 1.66, 2.82 and 0.60. To estimate accurate kinetic parameters, 60 minutes after injection was required to PET scan as myocardium image contrast ratios reached to constant values. As a result, 68Ga-BAPEN would be suitable radiotracer for PET which can applied to diagnosis of myocardial perfusion diseases after further preclinical and clinical investigations.

Development of Geometric Calibration Method for Triple Head Pinhole SPECT System / 핵의학분자영상

PURPOSE: Micro-pinhole SPECT system with conventional multiple-head gamma cameras has the advantage of high magnification factor for imaging of rodents. However, several geometric factors should be calibrated to obtain the SPECT image with good image quality. We developed a simplified geometric calibration method for rotating triple-head pinhole SPECT system and assessed the effects of the calibration using several phantom and rodent imaging studies. MATERIAL AND METHODS: Trionix Triad XLT9 triple-head SPECT scanner with 1.0 mm pinhole apertures were used for the experiments. Approximately centered point source was scanned to track the angle-dependent positioning errors. The centroid of point source was determined by the center of mass calculation. Axially departed two point sources were scanned to calibrate radius of rotation from pinhole to center of rotation. To verify the improvements by the geometric calibration, we compared the spatial resolution of the reconstructed image of Tc-99m point source with and without the calibration. SPECT image of micro performance phantom with hot rod inserts was acquired and several animal imaging studies were performed. RESULTS: Exact sphere shape of the point source was obtained by applying the calibration and axial resolution was improved. Lesion detectibility and image quality was also much improved by the calibration in the phantom and animal studies. CONCLUSION: Serious degradation of micro-pinhole SPECT images due to the geometric errors could be corrected using a simplified calibration method using only one or two point sources.

A Comparative Study of Subset Construction Methods in OSEM Algorithms using Simulated Projection Data of Compton Camera / 핵의학분자영상

PURPOSE: In this study we propose a block-iterative method for reconstructing Compton scattered data. This study shows that the well-known expectation maximization (EM) approach along with its accelerated version based on the ordered subsets principle can be applied to the problem of image reconstruction for Compton camera. This study also compares several methods of constructing subsets for optimal performance of our algorithms. MATERIALS AND METHODS: Three reconstruction algorithms were implemented; simple backprojection (SBP), EM, and ordered subset EM (OSEM). For OSEM, the projection data were grouped into subsets in a predefined order. Three different schemes for choosing nonoverlapping subsets were considered; scatter angle-based subsets, detector position-based subsets, and both scatter angle- and detector position-based subsets. EM and OSEM with 16 subsets were performed with 64 and 4 iterations, respectively. The performance of each algorithm was evaluated in terms of computation time and normalized mean-squared error. RESULTS: Both EM and OSEM clearly outperformed SBP in all aspects of accuracy. The OSEM with 16 subsets and 4 iterations, which is equivalent to the standard EM with 64 iterations, was approximately 14 times faster in computation time than the standard EM. In OSEM, all of the three schemes for choosing subsets yielded similar results in computation time as well as normalized mean-squared error. CONCLUSION: Our results show that the OSEM algorithm, which have proven useful in emission tomography, can also be applied to the problem of image reconstruction for Compton camera. With properly chosen subset construction methods and moderate numbers of subsets, our OSEM algorithm significantly improves the computational efficiency while keeping the original quality of the standard EM reconstruction. The OSEM algorithm with scatter angle- and detector position-based subsets is most available.

A case of maloccluded incisor teeth in a beaver: Castor canadensis

A three-year-old female beaver (Castor canadensis) was referred to the Veterinary Teaching Hospital of Chungbuk National University. It had been raised in the Cheong-ju zoo and had a history of malocclusion caused by improper feeding. General anesthesia was induced, and preoperative intraoral dental radiographs of the rostal maxillary and mandibular dentition were taken and lateral and ventrodorsal extraoral radiographs of the cheek teeth were also taken. The radiographs were negative for apical pathology and revealed a normal appearance of the cheek teeth. The lesion was likely to be related to the excessive length of the maxillary and mandibular incisors. Odontoplasty was performed to reduce overgrowth of the crowns of the incisors. Sequential transverse sections were removed until the crown was reduced by approximately its original length. The pulp chamber was not approached during the operation, as confirmed by postoperative intraoral radiographic evaluation of the incisors. Recovery from anesthesia was uneventful and the beaver returned to normal masticatory activities immediately after the operation.

Development and Performance Evaluation of an Animal SPECT System Using Philips ARGUS Gamma Camera and Pinhole Collimator / 대한핵의학회잡지

PURPOSE: We developed an animal SPECT system using clinical Philips ARGUS scintillation camera and pinhole collimator with specially manufactured small apertures. In this study, we evaluated the physical characteristics of this system and biological feasibility for animal experiments. MATERIALS AND METHODS: Rotating station for small animals using a step motor and operating software were developed. Pinhole inserts with small apertures (diameter of 0.5, 1.0, and 2.0 mm) were manufactured and physical parameters including planar spatial resolution and sensitivity and reconstructed resolution were measured for some apertures. In order to measure the size of the usable field of view according to the distance from the focal point, manufactured multiple line sources separated with the same distance were scanned and numbers of lines within the field of view were counted. Using a Tc-99m line source with 0.5 mm diameter and 12 mm length placed in the exact center of field of view, planar spatial resolution according to the distance was measured. Calibration factor to obtain FWHM values in 'mm' unit was calculated from the planar image of two separated line sources. Tc-99m point source with 1 mm diameter was used for the measurement of system sensitivity. In addition, SPECT data of micro phantom with cold and hot line inserts and rat brain after intravenous injection of [I-123]FP-CIT were acquired and reconstructed using filtered back projection reconstruction algorithm for pinhole collimator. RESULTS: Size of usable field of view was proportional to the distance from the focal point and their relationship could be fitted into a linear equation (y=1.4x+0.5, x: distance). System sensitivity and planar spatial resolution at 3 cm measured using 1.0 mm aperture was 71 cps/MBq and 1.24 mm, respectively. In the SPECT image of rat brain with [I-123]FP-CIT acquired using 1.0 mm aperture, the distribution of dopamine transporter in the striatum was well identified in each hemisphere. CONCLUSION: We verified that this new animal SPECT system with the Philips ARGUS scanner and small apertures had sufficient performance for small animal imaging.