Bone Sections Research Articles

Poster 110: Depth of Tissue Necrosis Following Footprint Preparation with Arthroscopic Radiofrequency Ablation

Objectives:Successful rotator cuff repair depends upon both secure fixation and biologic integration at the bone-tendon interface. Viable osteocytes and sound bony architecture contribute to the mechanical stability of suture anchor repair constructs. Furthermore, because tendons are hypovascular, preserving the microvasculature of the underlying bone bed is important. To create the bone-tendon interface, shoulder surgeons typically employ three different techniques to clear soft tissue from the footprint prior to rotator cuff repair: mechanical debridement, radiofrequency coagulation, and radiofrequency ablation. Conventional radiofrequency devices use radiofrequency energy to vaporize tissue, often in the setting of tumor resection to kill cancerous tissue. In arthroscopy, bipolar radiofrequency wands capitalize on the saline environment, passing radiofrequency waves through the conductive saline medium creating high energy ions. The result is a plasma field that can gently dissolve tissue with limited heat penetration to the surrounding environment, which is referred to as “coblation.” However, the extent to which this energy penetrates the adjacent tissue, potentially damaging nearby vasculature and osteocytes, is unknown. This study aims to explore the histological depth of tissue necrosis caused by arthroscopic radiofrequency ablation wands in comparison to a mechanical shaver.Methods:6 bovine metacarpal bones were collected one hour after devascularization and submerged in normal saline. Footprints were created by a radiofrequency ablation wand, at both the coagulation and ablation settings, and a mechanical shaver. Preparation was performed at 5 and 15 seconds. After the specimens were processed and prepared as hematoxylin and eosin-stained microscopic slides, each footprint was evaluated microscopically by a fellowship-trained pathologist. Depth of tissue destruction, preservation of periosteum, and osteocyte necrosis were evaluated histologically compared to the control sections for each treatment method.Results:Both the coagulation and ablation settings on the radiofrequency ablation wand were compared to the sections debrided with the mechanical shaver and the control sections. The ablation setting removed significantly more tissue than the coagulation setting at 5 seconds and 15 seconds of energy exposure (0.67 mm vs. 2.3 mm; P = .001 and 1.5 mm vs. 3.58 mm; P = .012) (table 1). While the depth of soft tissue destruction increased with time, the difference between 5 and 15 seconds for either treatment was not significant (0.67 mm vs. 1.5 mm; P = ,088, 2.3 mm vs. 3.58 mm; P = .051). The periosteum was rarely breached by any treatment and was seen to be well preserved in most sections. Osteocytes remained viable in the central area of treatment, and the normal cortical bone architecture was maintained. Compared to the control bone sections (figure 1) there was one section treated with ablation for 15 seconds that showed complete loss of overlying soft tissue in the treatment area and necrotic osteocytes at a depth of 0.5 mm from the treatment area (figure 2, 3).Conclusions:When used appropriately, arthroscopic radiofrequency ablation techniques effectively debride soft tissue from the rotator cuff footprint while preserving the underlying periosteal vasculature and cortical osteocytes. However, our results do show that local tissue destruction increases with degree of radiofrequency energy and exposure time which can lead to necrosis of the underlying tissues including the periosteum, osteocytes, and microvasculature. This has the potential to impair the biologic tendon-to-bone healing as well as the integrity of the mechanical repair construct, which would ultimately lead to failure of the repair. Thus, it is important for surgeons to be cautious while using arthroscopic radiofrequency techniques while preparing tendon footprints.TABLE 1.Depth of Soft Tissue Destruction by Treatment in millimeters (mm)Figure 1.Control, 20X. Histologic section demonstrating normal- periosteum, bony architecture, and viable osteocytes. White arrow: intact periosteum. Black arrow: Viable osteocyte.Figure 2.Ablation 15 seconds, 10X. White arrow: intact periosteum. Black arrow: treatment area with complete loss of periosteumFigure 3.Ablation 15 seconds, 20X. Histologic section demonstrating necrotic osieocytes at a depth of 0.5 mm below the treatment area.j White arrow: zone of necrotic osteocytes. Black arrow: viable osteocyie

Sex Estimation From Histomorphometric Analysis of Cortical Bone: A Hospital-based Study

Estimation of the sex of unknown skeletal remains is a daunting challenge, when only fragmented bones are available. For this reason, there is a need to study population specific histomorphometric features of bones to provide useful data for the process of identification. The purpose of this study was to estimate sex from six histomorphometric parameters of cortical bones in a cohort of Nigerian patients. The samples comprised non-pathologic bones collected from 29 patients (12 females and 17 males) between the ages of 35 to 85 years during orthopaedic procedures. The modified Frost’s manual method was used to prepare the histological sections of the cortical bones. The parameters evaluated were number of primary osteons (Os-p), number of secondary osteons (Os-s), osteon fragments (Os-f), non-Haversian canal (N-Hc), area of Haversian canal (Area Hc), and Haversian canal diameter (HCD). The data obtained were analyzed using SPSS version 23.0. Tests for sex differences were done using student t-test and stepwise discriminant function was used to formulate a predictive model for sex estimation. The mean Os-p, Os-s, Os-f, N-hc, Area HC, and HCD were 2.85 ± 0.86,3.92 ± 1.26,6.08 ± 1.37, 2.23 ± 0.66, 53.43 ± 5.55, and 7.85 ± 0.41 for males and 1.11 ± 0.56, 0.33 ± 0.17, 2.44 ± 0.67, 54.37 ± 6.04 and 7.426 ± 0.35 for females, respectively. The mean value of Os-s was significantly different in males and females (p=0.04). Stepwise discriminant function analysis showed Os-s could be used to estimate sex. 71.4% of our samples were correctly predicted based on sex. Discriminant function values of 0.418 and -0.626 were predictive values for males and females, respectively, using the DFA predictive model. Our study shows that the number of secondary osteons (Os-s) could be used to estimate sex in Nigerian patients.

The Effect of Low-Energy Laser-Driven Ultrashort Pulsed Electron Beam Irradiation on Erythropoiesis and Oxidative Stress in Rats.

Anemia is a commonly observed consequence of whole-body exposure to a dose of X-ray or gamma irradiation of the order of the mean lethal dose in mammals, and it is an important factor for the determination of the survival of animals. The aim of this study was to unravel the effect of laser-driven ultrashort pulsed electron beam (UPEB) irradiation on the process of erythropoiesis and the redox state in the organism. Wistar rats were exposed to laser-driven UPEB irradiation, after which the level of oxidative stress and the activities of different antioxidant enzymes, as well as blood smears, bone marrow imprints and sections, erythroblastic islets, hemoglobin and hematocrit, hepatic iron, DNA, and erythropoietin levels, were assessed on the 1st, 3rd, 7th, 14th, and 28th days after irradiation. Despite the fact that laser-driven UPEB irradiation requires quite low doses and repetition rates to achieve the LD50 in rats, our findings suggest that whole-body exposure with this new type of irradiation causes relatively mild anemia in rats, with subsequent fast recovery up to the 28th day. Moreover, this novel type of irradiation causes highly intense processes of oxidative stress, which, despite being relatively extinguished, did not reach the physiologically stable level even at the 28th day after irradiation due to the violations in the antioxidant system of the organism.

Neuronal Sprouting and Reorganization in Bone Tissue Infiltrated by Human Breast Cancer Cells.

BackgroundPain is a common complication for patients with metastatic bone disease. Animal models suggest that the pain, in part, is driven by pathological sprouting and reorganization of the nerve fibers innervating the bone. Here, we investigate how these findings translate to humans.MethodsBone biopsies were collected from healthy volunteers (n = 7) and patients with breast cancer and metastatic bone disease (permissions H-15000679, S-20180057 and S-20110112). Cancer-infiltrated biopsies were from patients without recent anticancer treatment (n = 10), patients with recent anticancer treatment (n = 10), and patients with joint replacement surgery (n = 9). Adjacent bone sections were stained for (1) protein gene product 9.5 and CD34, and (2) cytokeratin 7 and 19. Histomorphometry was used to estimate the area of bone marrow and tumor burden. Nerve profiles were counted, and the nerve profile density calculated. The location of each nerve profile within 25 μm of a vascular structure and/or cancer cells was determined.ResultsCancer-infiltrated bone tissue demonstrated a significantly higher nerve profile density compared to healthy bone tissue. The percentage of nerve profiles found close to vascular structures was significantly lower in cancer-infiltrated bone tissue. No difference was found in the percentage of nerve profiles located close to cancer between the subgroups of cancer-infiltrated bone tissue. Interestingly, no correlation was found between nerve profile density and tumor burden.ConclusionsTogether, the increased nerve profile density and the decreased association of nerve profiles to vasculature strongly suggests that neuronal sprouting and reorganization occurs in human cancer-infiltrated bone tissue.

High-Speed Human Temporal Bone Sectioning for the Assessment of COVID-19-Associated Middle Ear Pathology.

Histopathologic analysis of human temporal bone sections is a fundamental technique for studying inner and middle ear pathology. Temporal bone sections are prepared by postmortem temporal bone harvest, fixation, decalcification, embedding, and staining. Due to the density of the temporal bone, decalcification is a time-consuming and resource-intensive process; complete tissue preparation may take 9-10 months on average. This slows otopathology research and hinders time-sensitive studies, such as those relevant to the COVID-19 pandemic. This paper describes a technique for the rapid preparation and decalcification of temporal bone sections to speed tissue processing. Temporal bones were harvested postmortem using standard techniques and fixed in 10% formalin. A precision microsaw with twin diamond blades was used to cut each section into three thick sections. Thick temporal bone sections were then decalcified in decalcifying solution for 7-10 days before being embedded in paraffin, sectioned into thin (10 µm) sections using a cryotome, and mounted on uncharged slides. Tissue samples were then deparaffinized and rehydrated for antibody staining (ACE2, TMPRSS2, Furin) and imaged. This technique reduced the time from harvest to tissue analysis from 9-10 months to 10-14 days. High-speed temporal bone sectioning may increase the speed of otopathology research and reduce the resources necessary for tissue preparation, while also facilitating time-sensitive studies such as those related to COVID-19.

High-Speed Human Temporal Bone Sectioning for the Assessment of COVID-19-Associated Middle Ear Pathology

High-Speed Human Temporal Bone Sectioning for the Assessment of COVID-19-Associated Middle Ear Pathology

Substantiating microCT for diagnosing bioerosion in archaeological bone using a new Virtual Histological Index (VHI)

Recent technological advances have broadened the application of palaeoradiology for non-destructive investigation of ancient remains. X-ray microtomography (microCT) in particular is increasingly used as an alternative to histological bone sections for interpreting pathological alterations, trauma, microstructure, and, more recently, bioerosion with direct or ancillary use of histological indices. However, no systematic attempt has been made to confirm the reliability of microCT for histotaphonomic analysis of archaeological bone. The objective of this study is therefore to compare thin sections of human femora rated with the Oxford Histological Index to microCT sections using the newly developed Virtual Histological Index in order to provide an accessible methodology for the evaluation of bioerosion in archaeological bone. We provide detailed descriptions of virtual sections and assess the efficacy of the method on cranial and postcranial elements, cremated long bones, and faunal samples. The traditional histological and virtual methods showed a strong correlation, providing the first systematic data substantiating lab-based microCT as a suitable alternative tool for reconstructing post-mortem history in the archaeological record, and for the reliable, non-destructive screening of samples for further analyses.

Finite element analysis of a hybrid corrugated hip implant for stability and loading during gait phases

Implants used in total hip replacements (THR) exhibit high failure rates and up to a decade of operational life. These surgical failures could be mainly attributed to the improper positioning, post-surgical stability and loading, of the implants during different phases of the gait. Typically, revised surgeries are suggested within a few years of hip implantation, which requires multiple femoral drilling operations to remove an existing implant, and to install a new implant. The pain and trauma associated with such procedures are also challenging with the existing hip implants. In this work, we designed a novel corrugated hip implant with innovative dimensioning as per ASTM standards, and grooves for directed insertion and removal (using a single femoral drilling and positioning operation). Biocompatible titanium alloy (Ti6Al4V) was chosen as the implant material, and the novel implant was placed into a femur model through a virtual surgery to study its stability and loading during a dynamic gait cycle. A detailed mesh convergence study was conducted to select a computationally accurate finite element (FE) mesh. Tight fit and frictional fit attachment conditions were simulated, and the gait induced displacements and stresses on the implant, cortical and cancellous bone sections were characterized. During walking, the implant encountered the maximum von-Mises stress of 254.97 MPa at the femoral head. The analyses indicated low micro-motions (i.e., approximately 7 μm) between the femur and implant, low stresses at the implant and bone within elastic limits, and uniform stress distribution, which unlike existing hip implants, would be indispensable for bone growth and implant stability enhancement, and also for reducing implant wear.

Life history and ossification patterns in Miguashaia bureaui reveal the early evolution of osteogenesis in coelacanths.

The study of development is critical for revealing the evolution of major vertebrate lineages. Coelacanths have one of the longest evolutionary histories among osteichthyans, but despite access to extant representatives, the onset of their weakly ossified endoskeleton is still poorly understood. Here we present the first palaeohistological and skeletochronological study of Miguashaia bureaui from the Upper Devonian of Canada, pivotal for exploring the palaeobiology and early evolution of osteogenesis in coelacanths. Cross sections of the caudal fin bones show that the cortex is made of layers of primary bone separated by lines of arrested growth, indicative of a cyclical growth. The medullary cavity displays remnants of calcified cartilage associated with bony trabeculae, characteristic of endochondral ossification. A skeletochronological analysis indicates that rapid growth during a short juvenile period was followed by slower growth in adulthood. Our new analysis highlights the life history and palaeoecology of Miguashaia bureaui and reveals that, despite differences in size and habitat, the poor endoskeletal ossification known in the extant Latimeria chalumnae can be traced back at least 375 million years ago.

Two Auloi from Megara

Abstract Two aulos pairs (Δ1965 and Δ1964), unearthed in 1980 and 2005 respectively at Megara (Attica), are exhibited in the city’s Archaeological Museum. Both are associated with metal sliding keys (resembling the keys on the well-known Pergamon aulos model), either mounted on the pipes (Δ1964) or displayed next to them (Δ1965). The present paper describes the parts, proposes a meaningful re-assemblage of the bone sections, and gives a detailed account of the sliding mechanism, which is here for the first time attested on finds of actual musical instruments, including an entirely new technology of speaker hole keys. A musical analysis, based on determining plausible reed configurations using software modelling, suggests that the finds represent a partially standardised design of professional modulating auloi, playing attested harmoníai while hovering between the enharmonic and chromatic.

High Spatial Resolution MALDI Imaging Mass Spectrometry of Fresh-Frozen Bone.

Bone and bone marrow are vital to mammalian structure, movement, and immunity. These tissues are also commonly subjected to molecular alterations giving rise to debilitating diseases like rheumatoid arthritis and osteomyelitis. Technologies such as matrix-assisted laser desorption/ionization (MALDI) imaging mass spectrometry (IMS) facilitate the discovery of spatially resolved chemical information in biological tissue samples to help elucidate the complex molecular processes underlying pathology. Traditionally, preparation of osseous tissue for MALDI IMS has been difficult due to its mineralized composition and heterogeneous morphology, and compensation for these challenges with decalcification and fixation protocols can remove or delocalize molecular species. Here, sample preparation methods were advanced to enable multimodal MALDI IMS of undecalcified, fresh-frozen murine femurs, allowing the distribution of endogenous lipids to be linked to tissue structures and cell types. Adhesive-bound bone sections were mounted onto conductive glass slides with microscopy-compatible glue and freeze-dried to minimize artificial bone marrow damage. High spatial resolution (10 μm) MALDI IMS was employed to characterize lipid distributions, and use of complementary microscopy modalities aided tissue and cell assignments. For example, various phosphatidylcholines localize to the bone marrow, adipose tissue, marrow adipose tissue, and muscle. Further, sphingomyelin(42:1) was abundant in megakaryocytes, whereas sphingomyelin(42:2) was diminished in this cell type. These data reflect the vast molecular and cellular heterogeneity indicative of the bone marrow and the soft tissue surrounding the femur. Multimodal MALDI IMS has the potential to advance bone-related biomedical research by offering deep molecular coverage with spatial relevance in a preserved native bone microenvironment.

A Review Into the Effects of Pamidronic Acid and Zoledronic Acid on the Oral Mucosa in Medication-Related Osteonecrosis of the Jaw.

Medication-related osteonecrosis of the jaw (MRONJ) is a growing problem without an effective treatment, presenting as necrotic bone sections exposed via lesions in the overlying soft tissue. There is currently a lack of clarity on how the factors involved in MRONJ development and progression contribute to disease prognosis and outcomes. Bisphosphonates (BPs), the most common cause of MRONJ, affect bone remodeling, angiogenesis, infection, inflammation and soft tissue toxicity, all of which contribute to MRONJ development. This article reviews the cellular mechanisms through which BPs contribute to MRONJ pathology, with a focus on the effects on cells of the oral mucosa. BPs have been shown to reduce cell viability, reduce proliferation, and increase apoptosis in oral keratinocytes and fibroblasts. BPs have also been demonstrated to reduce epithelial thickness and prevent epithelial formation in three-dimensional tissue engineered models of the oral mucosa. This combination of factors demonstrates how BPs lead to the reduced wound healing seen in MRONJ and begins to uncover the mechanisms through which these effects occur. The evidence presented here supports identification of targets which can be used to develop novel treatment strategies to promote soft tissue wound healing and restore mucosal coverage of exposed bone in MRONJ.

Cryptotanshinone Suppressed Postmenopausal Osteoporosis by Preventing RANKL-Mediated Osteoclastogenesis against Kidney Injury.

Background Cryptotanshinone (CPT), an active component extracted from the root of Salvia miltiorrhiza Bunge, exhibits extensive favorable bioactive properties including anti-inflammatory, antioxidative, antibacterial, and antitumor effects. This study aims to investigate the effects of CPT on osteogenesis and explore related mechanisms both in vivo and in vitro. Methods In the in vivo experiment, ovariectomized (OVX) female rats were intragastrically administered with CPT at doses of 10 mg/kg and 20 mg/kg for 13 consecutive weeks. Dual-energy X-ray absorptiometry was employed to detect bone mineral density (BMD). ELISA assay was leveraged to detect the biochemical parameters such as BUN and creatinine in the kidney samples. Bone and kidney sections were dyed by H&E and Masson staining kits. In the in vitro experiment, the RAW 264.7 cells were stimulated through the receptor activation of the nuclear factor kappa B ligand (RANKL) to establish an osteoclast differentiation model, and CPT's protective effect against bone loss was evaluated. Differentiated osteoclasts were determined by TRAP staining. While, osteoclast-marker proteins such as NFATc1, c-Fos, and cathepsin K were identified by Western blot. Results The results from in vivo experiments revealed that CPT could elevate bone mass and increase bone formation markers in OVX rats. Intriguingly, CPT administration noticeably ameliorated the kidney injury in OVX rats by suppressing BUN and restoring creatinine levels. Furthermore, the results from in vitro experiments suggested that CPT downregulated the protein expression of osteoclast-associated genes such as cathepsin K, c-Fos, and NFATc1 which hinted the related potential mechanisms. Conclusion The evidence from in vivo and in vitro experiments suggested that CPT exerted antiosteoclastogenic effects by inhibiting the activation of osteoclast differentiation followed by suppressing the protein expressions of cathepsin K, c-Fos, and NFATc1 in osteoclast precursors, and it exhibited protective effects against kidney damage, which highlighted its advantage in clinical application.

Segmentally Demineralized Cortical Bone With Stem Cell-Derived Matrix Promotes Proliferation, Migration and Differentiation of Stem Cells in vitro.

A recent study has shown that demineralized cortical bone (DCB) did not improve the healing of tendon-bone interface. Considering that there is a gradient of mineral content in the tendon-bone interface, we designed a segmentally demineralized cortical bone (sDCB) scaffold with two different regions: undemineralized cortical bone section within the scaffold (sDCB-B) and complete demineralized cortical bone section within the scaffold (sDCB-D), to mimic the natural structure of the tendon-bone interface. Furthermore, the extracellular matrix (ECM) from tendon-derived stem cells (TDSCs) was used to modify the sDCB-D region of sDCB to construct a novel scaffold (sDCB-ECM) for enhancing the bioactivity of the sDCB-D. The surface topography, elemental distribution, histological structure, and surface elastic modulus of the scaffold were observed using scanning electron microscopy, energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, histological staining and atomic force microscopy. Cell proliferation of bone marrow mesenchymal stem cells (BMSCs) and TDSCs cultured on scaffolds was evaluated using the Cell Counting kit-8, and cell viability was assessed by Live/Dead cell staining. Cell morphology was detected by fluorescent staining. The ability of the scaffolds to recruit stem cells was tested using transwell migration assay. The expression levels of bone-, cartilage- and tendon-related genes and proteins in stem cells were assessed by the polymerase chain reaction and western blotting. Our results demonstrated that there was a gradient of Ca and P elements in sDCB, and TDSC-derived ECM existed on the surface of the sDCB-D region of sDCB. The sDCB-ECM could promote stem cell proliferation and migration. Moreover, the sDCB-B region of sDCB-ECM could stimulate osteogenic and chondrogenic differentiation of BMSCs, and the sDCB-D-ECM region of sDCB-ECM could stimulate chondrogenic and tenogenic differentiation of TDSCs when compared to DCB. Our study indicated that sDCB-ECM might be a potential bioscaffold to enhance the tendon-bone interface regeneration.

Use of bioactive glass doped with magnesium or strontium for bone regeneration: A rabbit critical-size calvarial defects study.

Background:This study aimed to evaluate the amount of bone regeneration in critical defects of rabbit calvaria filled with magnesium- and strontium-doped bioactive glasses.Materials and Methods:In this rabbit critical-size calvarial defects study, 12 male New Zealand white rabbits were randomly divided into two groups. On the calvaria of each rabbit, four lesions (two lesions in the frontal bone and two lesions in the peritoneal bone) were created with a diameter of 8 mm spaced apart. Each lesion was filled in with (1) strontium-doped bioactive glass, (2) magnesium-doped bioactive glass, (3) 45S5 bioactive glass, and (4) empty lesion (control). Six rabbits were sacrificed at the end of 4 weeks, and six rabbits were randomly sacrificed at the end of 8 weeks. Bone sections with a 5-μ thickness of rabbit calvary bone were prepared, and the percentage of new bone, connective tissue, and residual material were calculated in microscopic images. Statistical analysis was performed by two-way ANOVA and Bonferroni additional tests, and the level of significance was set at P < 0.05 in all categories.Results:At 4 weeks, magnesium-doped bioactive glass showed the highest new bone formation with a mean of 11.66 ± 2.64, followed by the strontium-doped bioactive glass with the mean of 11.10 ± 1.69 (P = 0.0001). While at week 8, the highest amount of new bone observed in the strontium-doped group with a mean of 28.22 ± 3.19, and then, the magnesium-doped bioactive glass with a mean of 22.55 ± 3.43 (P = 0.0001).Conclusion:Doping strontium and magnesium in the structure of bioactive glasses increases new bone regeneration in comparison with 45S5 bioactive glass.

Characterisation of Sr2+ mobility in osteoporotic rat bone marrow by cryo-ToF-SIMS and cryo-OrbiSIMS.

Strontium (Sr2+) ions are an effective therapeutic agent for the healing of osteoporotic bone fractures and are therefore used, for example, in form of strontium-modified bone cements. In order to reduce animal testing in further implant materials development in the future, a simulation of the Sr2+ release and transport in bone would be helpful. For such a simulation, knowledge of the experimental parameters for Sr2+ mobility in different compartments of bone (mineralised bone, bone marrow) is essential. In a previous study, we developed an experimental protocol for transport studies in bovine bone marrow by time-of-flight secondary ion mass spectrometry (ToF-SIMS). In the current proof-of-concept study, we investigated Sr2+ diffusion for the first time in bone marrow of rat bone sections. Additionally, orbitrap secondary ion mass spectrometry (OrbiSIMS) was applied for unambiguous signal identification of lipids and fatty acid species in rat bone marrow. Detailed 2D and 3D mass spectrometric imaging analyses, depth profiling as well as OrbiSIMS spectrometric analysis revealed faster Sr2+ diffusion in rat bone marrow areas with low intensity of lipid and fatty acid signals than in areas with higher lipid/fatty acid content. These results could be confirmed by histological staining and additional analysis of Sr2+ diffusion into pure fat sections.

Clinical Use of Tailored Computed Tomography to Prevent Poststernotomy Dehiscence.

Morphological and tissue density analysis of the sternum can be performed in the preoperative computed tomography (CT). The purpose of this study was to analyze morphology and tissue density of sternum in CT and effect for comparison sternal instability. Patients with sternal instability (n = 61) and sternal stability (n = 66) were enrolled in this study. All of the patients were studied using same thorax CT procedure. All the measurements were performed by one specific cardiovascular radiologist. The Hounsfield units (HUs) were measured in axial sections of the sternum trabecular bone. Sternal instability group mean HU was 75.36 ± 13.19 and sternal stability group HU was 90.24 ± 12.16 (p < 0.000). HU is the statically significant predictor of sternal instability. Our study showed a significant correlation between the mean HU value of sternum and sternal instability. We think that it is important to evaluate the existing thorax CT while performing preoperative risk analysis for sternal dehiscence.

First osteohistological and histotaphonomic approach of Equus occidentalis Leidy, 1865 (Mammalia, Equidae) from the late Pleistocene of Rancho La Brea (California, USA).

Rancho La Brea (California, USA) is the most emblematic Quaternary fossiliferous locality in the world, since both the high number and diversity of the specimens recovered and their excellent preservational quality. In the last decades, paleobiological and paleoecological knowledge of the different groups of mammals from this site has increased notably; however, some aspects have not yet been inquired or there is little information. In this work we provide information on one of the most abundant mammals of this site, the equid Equus occidentalis, based on the study, from osteohistological and histotaphonomic perspectives, of thin sections of different limb bones. On the one hand, from an osteohistological viewpoint, we observe that the distribution and characterization of bone tissues in the different skeletal elements are, in general lines, similar to that mentioned for other extant and extinct equids. Cyclical growth marks allowed us to propose preliminary skeletochronological interpretations. On the other hand, from a taphonomic viewpoint, we note that all the samples reflect an excellent preservation of the bone microstructure, slightly altered by different pre- and post-burial processes. The variations recorded evidence different taphonomic history and preservation conditions among pits. This is the first study including fossil material from Rancho La Brea exclusively based on the analysis of the bone microstructure features.

Comparison of Bone Mineral Content of the Equine Third Metacarpal to Total Radiographic Bone Aluminum Equivalents From Unprocessed Digital Radiographs

Digital radiographs are common for estimating bone mineral content (BMC) in horses with radiographic bone aluminum equivalents (RBAE). Processing algorithms are used to produce clearer images of digital radiographs in clinical settings, but this distorts RBAE. This study compared RBAE from digital radiographs to BMC from bone ash, and physical and digital morphology measurements. Digital radiographs were taken of six third metacarpals (MCIII) from equine cadavers with an aluminum step wedge penetrometer. A 2-cm transverse section of bone was digitally analyzed and excised from each MCIII. For each image, a linear regression was created using the step wedge thicknesses (R2 > 0.99) and used to obtain total and individual RBAE. Outer and inner diameters of both dorsal-palmar (DP) and lateral-medial (LM) aspects, as well as cortical thicknesses, were measured physically and digitally. Bone samples were ether-extracted, oven-dried, and ashed. Statistics were analyzed as correlations between variables. Physical and digital measurements of dorsal, medial, and lateral cortices, as well as DP outer diameter, tended to be similar (r > 0.74, P < .09) but palmar cortex measurements did not (r = 0.41, P = .42). The LM outer and DP/LM inner diameters were similar between the two methods (r > 0.95, P < .05). Total RBAE was strongly correlated to BMC (r > 0.93, P < .01). These results suggest that using digital radiographs to make morphological measurements is accurate and confirm the strong relationship between total RBAE and bone ash. However, this study emphasizes the need to use unprocessed radiographs for analysis.

Carfilzomib alleviated osteoporosis by targeting PSME1/2 to activate Wnt/β-catenin signaling

Osteoporosis (OP) is characterized by decreased bone mineral density and impaired bone strength. Carfilzomib (CFZ) is a new-generation proteasome inhibitor and has been found to affect bone metabolism. However, the effect and mechanism of CFZ on OP has not been investigated systematically. In this study, we found that protein levels of proteasome activator subunit 1/2 (PSME1/2) increased in OP, and accumulated mostly in osteoblasts and osteoclasts. Treatment with PSME1/2 recombinant protein inhibited osteogenesis and promoted osteoclast formation in vitro. Also, PSME1/2 inhibited the expression of β-catenin protein, resulting in limitation of Wnt/β-catenin signaling. CFZ inhibited PSME1 and PSME2 proteasome activities and increased β-catenin protein level, resulting in the translocation of β-catenin to the nucleus and activation of canonical Wnt/β-catenin signaling, further promoting osteogenesis and inhibiting osteoclastic differentiation. In vivo, we conducted ovariectomy (OVX) to create a model of OVX-induced postmenopausal OP in mice. When analyzed by micro-CT scanning, enhancement of bone mineral density, bone volume, trabecular number, and thickness was seen in the CFZ-treated mice. Also, we noticed increased osteogenesis and decreased osteoclastogenesis, diminished expression of PSME1 and PSME2 and activated Wnt/β-catenin signaling in bone sections from OP mice treated with CFZ. Overall, our data indicated that PSME1/2 may serve as new targets for the treatment of OP, and targeting PSME1/2 with CFZ provides a candidate therapeutic molecule for postmenopausal OP.