Epiphyseal Research Articles

Growth deficiency in a mouse model of Kabuki syndrome 2 bears mechanistic similarities to Kabuki syndrome 1.

Growth deficiency is a characteristic feature of both Kabuki syndrome 1 (KS1) and Kabuki syndrome 2 (KS2), Mendelian disorders of the epigenetic machinery with similar phenotypes but distinct genetic etiologies. We previously described skeletal growth deficiency in a mouse model of KS1 and further established that a Kmt2d-/- chondrocyte model of KS1 exhibits precocious differentiation. Here we characterized growth deficiency in a mouse model of KS2, Kdm6atm1d/+. We show that Kdm6atm1d/+ mice have decreased femur and tibia length compared to controls and exhibit abnormalities in cortical and trabecular bone structure. Kdm6atm1d/+ growth plates are also shorter, due to decreases in hypertrophic chondrocyte size and hypertrophic zone height. Given these disturbances in the growth plate, we generated Kdm6a-/- chondrogenic cell lines. Similar to our prior in vitro model of KS1, we found that Kdm6a-/- cells undergo premature, enhanced differentiation towards chondrocytes compared to Kdm6a+/+ controls. RNA-seq showed that Kdm6a-/- cells have a distinct transcriptomic profile that indicates dysregulation of cartilage development. Finally, we performed RNA-seq simultaneously on Kmt2d-/-, Kdm6a-/-, and control lines at Days 7 and 14 of differentiation. This revealed surprising resemblance in gene expression between Kmt2d-/- and Kdm6a-/- at both time points and indicates that the similarity in phenotype between KS1 and KS2 also exists at the transcriptional level.

Zinc-alkaline phosphatase at sites of aortic calcification

Zinc (Zn) is a normal trace element in mineralizing tissues, but it is unclear whether it is primarily bound to the mineral phase or to organic molecules involved in the mineralization process, or both. Tissue-nonspecific alkaline phosphatase (TNAP) is a Zn metalloenzyme with two Zn ions bound to the M1 and M2 catalytic sites that functions to control the phosphate/pyrophosphate ratio during biomineralization. Here, we studied aortas from Tagln-Cre +/−; HprtALP/Y TNAP overexpressor (TNAP-OE) mice that develop severe calcification. Zn histochemistry was performed using the sulfide-silver staining method in combination with a Zn partial extraction procedure to localize mineral-bound (mineral Zn) and TNAP-bound Zn (tenacious Zn), since soluble Zn (loose Zn) is extracted during fixation of the specimens. Two synthetic bone mineral composites with different Zn content, bone ash, and rat epiphyseal growth plate cartilage were used as controls for Zn staining. In order to correlate the distribution of mineral and tenacious Zn with the presence of mineral deposits, the aortas were examined histologically in unstained and stained thin sections using various light microscopy techniques. Our results show that 14 and 30 dpn, TNAP is concentrated in the calcifying matrix and loses Zn as Ca2+ progressively displaces Zn2+ at the M1 and M2 metal sites. Thus, in addition to its catalytic role TNAP has an additional function at calcifying sites as a Ca-binding protein.Graphical

Histological Observations of the Developing Human Fetal Humerus at Different Trimesters of Pregnancy

Background: Although femur length is the preferred method for fetal age assessment, the humerus is sometimes the right choice, especially in the second half of pregnancy. Fetal bone development significantly impacts adult bone quality and senescent bone disorders, including osteoporosis. Purpose of the study: The present study aimed to ascertain the histological changes in the human fetal humerus across the three trimesters. After the institutional ethical committee clearance and parent consent, the study was carried out on stillborn or medically terminated human fetuses from the 10th to the 32nd week of intrauterine life. Results: First trimester: The primary bone collar appeared with the primary ossification center, marked by more vascular invasion and a pool of mesenchymal cells. Trabeculations begin from the bony collar and insignificant periosteum. Second trimester: The changes showed longitudinal growth of periosteal bone towards the proximal and distal ends of the growing bone. Growth plate with distinguished zones and gradual fusion of epiphysis with growth plate were observed. Third trimester: Trabeculation number and thickness increase with calcification. Towards the third trimester, the marrow cavity with increased and prominent trabeculations is consistent. Conclusion: Understanding normal microstructural and cellular events chronologically is an ideal platform for future studies to develop cell-based or cell-targeted therapies for adult bone disorders, traumatic bone injuries, or bone engineering. KEYWORDS: Histology, Developing Bone, Humerus, Fetuses, Embryology.

Skeletal malformation in growing milk sheep.

Two six-month old female Lacaune lambs with severe skeletal malformations of both front limbs were presented to the Department of Farm Animals, University of Zurich. The clinical examination showed alert animals with a high body weight and body condition score as well as a valgus deformation without pain or swelling. Radiographic examination showed severe irregularities in the epiphysial plate of the metacarpal bones in both lambs. Delayed growth in the lateral aspects of the physis was evident and resulted in valgus deformation. Nutritional causes were considered as the main reason for this presentation and a nutritional consultation was performed by the Institute of Animal Nutrition and Dietetics, University of Zurich. The estimated energy intake of these lambs was 65 % higher than the recommended maximum for growing sheep and the estimated vitamin D content of the diet was 71 % below the recommended allowance. Both animals were euthanized, and peripheral quantitative computed tomography (pQCT) was performed postmortem to measure total bone mineral density (BMD), trabecular bone mineral density (tBMD) and cortical bone mineral density (cBMD) of the left and right metatarsal bone of both animals. The BMD and the tBMD at 10 % of bone length were below the reference values and the BMD at 50 % was above the reference values. In addition, postmortem examination revealed a Salter-Harris-Typ-1 facture in the right caput humeri of one lamb. Histological evaluation showed defects in the articular cartilage with an eburnation in the metacarpal region and a disrupted area of columnar cartilage. This case report supports the fact that a high dietary energy intake leads to damage to the cartilage and the epiphyseal zone in sheep. In addition, insufficient dietary vitamin D intake contributed to the incomplete bone mineralization, as well as delayed growth and skeletal malformation.

Single-cell transcriptomic analyses of mouse idh1 mutant growth plate chondrocytes reveal distinct cell populations responsible for longitudinal growth and enchondroma formation.

Enchondromas are a common tumor in bone that can occur as multiple lesions in enchondromatosis, which is associated with deformity of the effected bone. These lesions harbor mutations in IDH and driving expression of a mutant Idh1 in Col2 expressing cells in mice causes an enchondromatosis phenotype. In this study we compared growth plates from E18.5 mice expressing a mutant Idh1 with control littermates using single cell RNA sequencing. Data from Col2 expressing cells were analyzed using UMAP and RNA pseudo-time analyses. A unique cluster of cells was identified in the mutant growth plates that expressed genes known to be upregulated in enchondromas. There was also a cluster of cells that was underrepresented in the mutant growth plates that expressed genes known to be important in longitudinal bone growth. Immunofluorescence showed that the genes from the unique cluster identified in the mutant growth plates were expressed in multiple growth plate anatomic zones, and pseudo-time analysis also suggested these cells could arise from multiple growth plate chondrocyte subpopulations. This data identifies subpopulations of cells in control and mutant growth plates, and supports the notion that a mutant Idh1 alters the subpopulations of growth plate chondrocytes, resulting a subpopulation of cells that become enchondromas at the expense of other populations that contribute to longitudinal growth.

Sclerostin modulates mineralization degree and stiffness profile in the fibrocartilaginous enthesis for mechanical tissue integrity.

Fibrocartilaginous entheses consist of tendons, unmineralized and mineralized fibrocartilage, and subchondral bone, each exhibiting varying stiffness. Here we examined the functional role of sclerostin, expressed in mature mineralized fibrochondrocytes. Following rapid mineralization of unmineralized fibrocartilage and concurrent replacement of epiphyseal hyaline cartilage by bone, unmineralized fibrocartilage reexpanded after a decline in alkaline phosphatase activity at the mineralization front. Sclerostin was co-expressed with osteocalcin at the base of mineralized fibrocartilage adjacent to subchondral bone. In Scx-deficient mice with less mechanical loading due to defects of the Achilles tendon, sclerostin+ fibrochondrocyte count significantly decreased in the defective enthesis where chondrocyte maturation was markedly impaired in both fibrocartilage and hyaline cartilage. Loss of the Sost gene, encoding sclerostin, elevated mineral density in mineralized zones of fibrocartilaginous entheses. Atomic force microscopy analysis revealed increased fibrocartilage stiffness. These lines of evidence suggest that sclerostin in mature mineralized fibrochondrocytes acts as a modulator for mechanical tissue integrity of fibrocartilaginous entheses.

Effectiveness of the garlic (Allium sativum) juice on removing the Pacific abalone postlarvae (Haliotis discus hannai) and subsequent growth evaluation

The Pacific abalone (Haliotis discus hannai) is widely cultivated in East Asian countries. Aquaculture of this species has become a thriving industry in China, with adequate seed production being a key contributing factor. However, maintaining sufficient diatom abundance during the nursery phase remains challenging. In this study, we assessed a transfer nursery culture method that involves prolonged cultivation with a sufficient diatom supply. This method involved treating postlarvae on diatom-depleted plates with a garlic juice (GJ) solution to facilitate detachment, followed by transfer to newly diatom-precoated plates for further growth in the nursery. We investigated the effects of garlic juice concentration (GJC) and animal size on detachment and mortality rates using a two-factor design. Our negative binomial regression analysis uncovered significant impacts of both factors and their interactions on the target traits. We noticed that the optimal GJC for smaller groups of abalone postlarvae (2.2 ± 1.0 mm) was 0.7 %, while for larger groups (3.8 ± 2.2 mm), it increased to 1.0 %. Notably, suitable GJC concentrations during post-treatment recovery resulted in no apparent mortality in Pacific abalone postlarvae. Our study demonstrated the effectiveness of the transfer nursery method, showing an improvement of over ∼1.1 mm in shell length and a 43.1 % increase in survival during a 30-day experiment. Our study presents a significant advancement, as it likely introduces the first reported method of large-scale postlarval removal of H. discus hannai for prolonged nursery periods with sufficient diatom provision. The integration of GJ treatment and the transfer nursery method exhibited promising results, highlighting the benefits of its application for enhancing husbandry procedures, nursery management, and the overall industrial productivity of Pacific abalone.

Type II RAF inhibitor tovorafenib in relapsed/refractory pediatric low-grade glioma (pLGG): Reversible decreases in growth velocity in the phase 2 FIREFLY-1 trial.

10036 Background: Tovorafenib is an investigational, selective, CNS-penetrant, type II RAF inhibitor. Results from the ongoing FIREFLY-1 (NCT04775485) phase 2 study (1) in BRAF-altered pLGG showed clinically meaningful tumor responses and a manageable safety profile with tovorafenib monotherapy. Decreased growth velocity (GV) was observed; this is an update on changes in GV in skeletally immature children receiving tovorafenib. Methods: A planned safety analysis was completed on August 8, 2023 and included 137 patients (Arm 1: 77 & Arm 2: 60) treated with ≥1 dose of tovorafenib in FIREFLY-1. This report provides additional follow-up on all cases of decreased growth velocity (GV), an adverse event of special interest (AESI), reported to the Sponsor’s global safety database (GSDB) as of January 19, 2024. Results: Decreased GV was reported in 40 (29.2%) of 137 patients; 26 (19%) had GV reduction ≥50% from baseline (BL). Of those with decreased GV, 30 (75.0%) had pre-existing neuromuscular or endocrine comorbidities that may affect normal growth, including 6 (15%) with precocious puberty being treated with a gonadotropin-releasing hormone analogue, and 9 (22.5%) with BL heights 2 standard deviations above or below average for age and sex. Nineteen of the 40 patients with this AESI had on-treatment bone age assessments; none showed advancement of bone age from BL or premature closure of growth plates. No osteopenia or abnormal fractures were reported. Of the 35 patients with growth hormone (GH) testing, only 2 had signs of GH deficiency (both had optic pathway tumors; 1 had GH deficiency at BL, the other, a new tumor-associated GH deficiency). Post-treatment heights ≥3 months off treatment were reported for 10 of 40 patients who had interrupted or discontinued treatment for any reason (mean follow up: 5.8 months), including 2 (1.5%) permanent discontinuations and 3 (2.2%) interruptions due to decreased GV. All 10 showed post-treatment recovery in annualized GV (AGV) (average on-treatment AGV 1.1 cm/y vs. average post-treatment AGV 8 cm/y), in some cases exceeding expected average AGV for age. One additional 4-year-old boy with on-treatment AGV of 1.2 cm/y had an off-treatment AGV of 12.3 cm/y after 2 months of off-treatment follow-up. Decreased GV was reported to the GSDB for 5 (11.4%) of 44 patients who received above the maximum dose of tovorafenib used in FIREFLY-1 in an ongoing investigator-initiated study. Four of the 5 patients from this study had ≥3 months of off-treatment follow-up reported; all 4 showed evidence of GV recovery. Conclusions: Decreased GV has been observed in patients treated with tovorafenib. Early follow-up data from patients whose treatment was interrupted show consistent evidence for GV recovery and preservation of growth potential on bone age studies. 1. Kilburn LK, et al. Nat Med.2023. Clinical trial information: NCT04775485 .

Melatonin ameliorates Slc26a2-associated chondrodysplasias by attenuating endoplasmic reticulum stress and apoptosis of chondrocytes

Although the pathogenesis and mechanism of congenital skeletal dysplasia are better understood, progress in drug development and intervention research remains limited. Here we report that melatonin treatment elicits a mitigating effect on skeletal abnormalities caused by SLC26A2 deficiency. In addition to our previous finding of endoplasmic reticulum stress upon SLC26A2 deficiency, we found calcium (Ca2+) overload jointly contributed to SLC26A2-associated chondrodysplasias. Continuous endoplasmic reticulum stress and cytosolic Ca2+ overload in turn triggered apoptosis of growth plate chondrocytes. Melatonin, known for its anti-oxidant and anti-inflammatory properties, emerged as a promising therapeutic approach in our study, which enhanced survival, proliferation, and maturation of chondrocytes by attenuating endoplasmic reticulum stress and Ca2+ overload. Our findings not only demonstrated the efficacy of melatonin in ameliorating abnormal function and cell fate of SLC26A2-deficient chondrocytes in vitro but also underscored its role in partially alleviating the skeletal dysplasia seen in Col2a1-CreERT2; Slc26a2fl/fl mice. As revealed by histology and micro-CT analyses, melatonin significantly improved retarded cartilage growth, defective trabecular bone formation, and tibial genu varum in vivo. Collectively, these data shed translational insights for drug development and support melatonin as a potential treatment for SLC26A2-related chondrodysplasias.

Alcohol intake during pregnancy reduces offspring bone epiphyseal growth plate chondrocyte proliferation through transforming growth factor β-1 inhibition in the Sprague Dawley rat humerus.

Intrauterine alcohol exposure delays bone maturation and intensifies osteoporosis and fracture risk. As most studies emphasize the neurological aspects of intrauterine alcohol exposure, there is a lack of research on the implications pertaining to osseous tissue. Previous studies investigated these effects in fetuses, with limited studies on postnatal life. Postnatal studies are crucial since peak bone growth occurs during adolescence. This study aimed at assessing the effects of prenatal alcohol exposure on the humerus proximal and distal growth plate chondrocytes in 3-week-old rats. Sprague Dawley rats (n=9) were assigned to either the ethanol group (n=3), saline (n=3), and untreated (n=3) group and time-mated. Once pregnant, as confirmed by the presence of a copulation plug, the former 2 groups were treated with 0.015 ml/g of 25.2% ethanol and 0.9% saline. The untreated group received no treatment. The left humeri belonging to 6 pups per group were used. Serial sections were cut with a microtome at 5 μm thickness. These sections were stained with haematoxylin and eosin for assessment of normal morphology or immunolabeled with anti-Ki-67 and transforming growth factor β-1 (TGFβ-1) antibody. Prenatal alcohol exposure adversely effected the growth plate sizes and the number of cells in the proliferative zone. Fewer TGFβ-1 immunopositive and proliferative chondrocytes were found using the anti-Ki-67 antibody. This may explain the growth retardation in offspring exposed to gestational alcohol, showing that gestational alcohol exposure inhibits cell proliferation, aiding the diminished stature.

Synthesis of acylated derivatives of alginate oligosaccharides and evaluation of their potential antibacterial activities against Staphylococcus aureus

Alginate oligosaccharides (AOS) are crucial carbohydrate-based biomaterial used in the synthesis of potential drugs and biological agents, but their antibacterial activities are not significant. In this study, AOS acylated derivatives were synthesized by grafting maleic anhydride (MA) onto AOS at varying ratios. Additionally, their inhibitory effects against Staphylococcus aureus were thoroughly investigated. Characterization of the AOS acylated derivatives (AOS-MA-x, where x = 1, 5, 10, and 20) was conducted using Fourier-transformed infrared spectroscopy, 1H nuclear magnetic resonance spectroscopy, and X-ray diffraction, which confirmed the successful synthesis of these derivatives. The bacteriostatic activity of the AOS-MA derivatives was assessed using growth curves and plate coating method, demonstrating significant antibacterial effects against S. aureus, as compared with AOS. Among these derivatives, AOS-MA-20 exhibited the most potent bacteriostatic activity and was selected for further investigation of its inhibitory mechanism. Scanning electron microscopy analysis revealed that treatment with AOS-MA-20 led to the lysis and rupture of S. aureus cells, expelling their intracellular contents. Moreover, AOS-MA-20 disrupted the integrity of cell wall and cell membrane, impacted ATPase activity, and inhibited the formation of biofilm to some extent, ultimately resulting in bacterial death. These findings lay a foundational framework for the development of environmentally friendly antimicrobial agents.

Management of Chondroblastoma in Pediatric Patients: 21 Years of Single-Center Experience.

Chondroblastoma (CB), a rare benign bone tumor that produces chondrocytes, often develops in the epiphysis or apophysis of children and young adults. The treatment of these rare tumors is complex. The standard treatment protocol involves curettage with local adjuvants and bone graft or cement application. The authors examined 38 CBs to determine risk factors for local recurrence, complications, and functional outcomes following epiphyseal curettage. Twenty-two girls and sixteen boys aged 10 to 17 years with histologically confirmed chondroblastoma who arrived at our hospital between January 2000 and June 2021 were reviewed retrospectively. Clinical data, radiographic images, histological results, treatment, functional outcomes, and the local recurrence rate were examined-surgical treatment involved total tumor curettage, followed by bone grafting and adjuvant techniques. Local recurrences have also been reported. The most frequently affected site was the proximal femur. Sites of involvement included the proximal femur in 10 (26.3%) cases, the proximal tibia in 8 (20.8%), the humerus in 5 cases (13.2%), the distal tibia in 4 cases (10.5%), the distal femur in 3 cases (7.9%), the supracetabular region in 3 cases (7.9%), the talus in 1 case (2.6%), the calcaneus in 1 case (2.6%), the scapula in 1 case (2.6%), the lumbar spine in 1 case (2.6%), and the iliac bone in 1 (2.6%) patient. The mean follow-up was 144.2 months (24 to 276). The local recurrence rate was 7.9%. The mean Musculoskeletal Tumor Society (MSTS) score was 28.3 points (17 to 30). The mean duration of symptoms at presentation was 5.8 (range, 1 to 28) months. Aggressive curettage and bone grafting resulted in local control and good outcomes in most pediatric patients. In a relatively small proportion of cases, long-term complications and recurrence can occur due to growth plate damage and late diagnosis. In patients admitted to the pediatric clinic with pain, which is often accompanied by localized edema and joint effusion, early detection via advanced radiological scans (X-ray, CT, or MRI) may prevent delays in diagnosis.

Exploring height outcomes with adjuvant aromatase inhibition in growth hormone-deficient male survivors of childhood cancer.

Aromatase inhibitors (AI) may improve height in short stature conditions; however, the effect in childhood cancer survivors (CCS) is unknown. We assessed final adult height (FAH) in CCS treated with AI and GH compared with those treated with GH alone. Retrospective cohort study of GH-deficient male CCS treated between 2007 and 2023. FAH was noted as the height at the fusion of growth plates or 18 years of age. Multivariable linear regression was used to examine treatment association with FAH, adjusting for other risk factors. Ninety-two patients were included; 70 were treated with GH and 22 with combination AI/GH. The mean age at GH initiation did not differ between groups. The mean age at AI initiation was 13.7±1.9 years. A greater proportion of patients in the AI/GH group were treated with stem cell transplantation, abdominal radiation, total body irradiation, and cis-retinoic acid (p<.01). Multivariable linear regression demonstrated no significant treatment association with FAH Z-score (β=0.04, 95% CI: -0.9 to 0.9). History of spinal radiation (β=-0.93, 95% CI: -1.7 to -0.2), lower starting height Z-score (β=-0.8, 95% CI: -1.2 to -0.4), and greater difference between bone age and chronological age (β=-0.3, 95% CI: -0.5 to -0.07) were associated with lower FAH Z-score. Adjuvant AI was not associated with increased FAH in male CCS compared with GH monotherapy. Future work is needed to determine the optimal adjunctive treatment to maximize FAH for this population.

The “toxic window” of amoxicillin exposure during pregnancy on long bone development in fetal mice

AimsAmoxicillin is a broad-spectrum beta-lactam antibiotic used to treat infectious diseases in pregnant women. Studies have shown that prenatal amoxicillin exposure (PAmE) has developmental toxicity on fetal development. However, the effect of PAmE on long bone development has not been reported. This study aimed to investigate the “toxic window” of PAmE on long bone development and explore its possible mechanism in fetal mice. Materials and methodsPregnant mice were administered amoxicillin by gavage at different stages (gestational day (GD)10–12 and GD16–18), different doses (150 and 300 mg/kg·d) and different courses (single and multiple courses). Fetal femurs were collected at GD18 and bone development related indicators were detected. Key findingsThe results showed that PAmE significantly reduced the length of the femur and primary ossification center of fetal mice, and inhibited the development of fetal growth plate. Meanwhile, PAmE inhibited the development of bone marrow mesenchymal stem cells, osteoclasts and endothelial cells in fetal long bone. Further, we found the fetal long bone developmental toxicity induced by PAmE was most significant at late-pregnancy (GD16–18), high dose (300 mg/kg·d) and multiple-course group. Besides, PAmE inhibited the expression of Wnt/β-catenin signaling pathway in fetal long bone. The β-catenin mRNA expression was significantly positively correlated with the development indexes of fetal long bone. SignificancePAmE has toxic effects on long bone development, and there was an obvious “toxic window” of PAmE on the long bone development in fetal mice. The Wnt/β-catenin signaling pathway may mediate PAmE-induced fetal long bone development inhibition.

Case Report: Halting terminal osseous overgrowth post tibia amputation in children: a report of three cases

Terminal osseous overgrowth is a common complication after trans-diaphyseal amputation in children, leading to pain, soft tissue problems, and recurrent surgical procedures. We report three different cases with post-amputation issues of osseous overgrowth, ulceration, and deformity over the amputation site. The first case involves a 9-year-old boy with a right leg congenital amputation secondary to amniotic band syndrome. The right below-knee stump later experienced recurrent episodes of osseous overgrowth, leading to ulceration. After the prominent tibia was resected and capped with the ipsilateral proximal fibula, a positive outcome was achieved with no more recurrent overgrowth over the right leg stump. The second case involves a 9-year-old girl born with an amniotic constriction band over both legs. Her left leg remained functional after a circumferential Z-plasty, but the right leg was a congenital below-knee amputation. Multiple refashioning surgeries were performed on the right leg due to osseous overgrowth but the patient continued to experience recurrent overgrowth causing pain and difficulty fitting into a prosthesis. We performed osteocartilaginous transfer of the proximal part of the ipsilateral fibula to the right tibial end, successfully preventing the overgrowth of the tibia without any complications. The third case involves an 11-year-old boy with a history of meningococcal septicemia who underwent a right below-knee amputation and left ankle disarticulation due to complications of septic emboli. He experienced a prominent right distal tibia stump, which later developed into valgus deformity as a result of the previous insult to the proximal tibial growth plate. We performed a corrective osteotomy over the proximal right tibia and capped the entire tibia with the ipsilateral fibula as an intramedullary splint for the osteotomy site. Post-operatively, we achieved satisfactory deformity correction and successfully halted the recurrent overgrowth over the right tibia stump. The method of ipsilateral fibula capping is safe and effective in managing the osseous overgrowth complications in trans-diaphyseal amputations among children. Therefore, it is a reasonable option during primary below-knee amputations in children compared to multiple refashioning surgeries.

Approaches to embryonic neurodevelopment: from neural cell to neural tube formation through mathematical models.

The development of the human central nervous system initiates in the early embryonic period until long after delivery. It has been shown that several neurological and neuropsychiatric diseases originate from prenatal incidents. Mathematical models offer a direct way to understand neurodevelopmental processes better. Mathematical modelling of neurodevelopment during the embryonic period is challenging in terms of how to 'Approach', how to initiate modelling and how to propose the appropriate equations that fit the underlying dynamics of neurodevelopment during the embryonic period while including the variety of elements that are built-in naturally during the process of neurodevelopment. It is imperative to answer where and how to start modelling; in other words, what is the appropriate 'Approach'? Therefore, one objective of this study was to tackle the mathematical issue broadly from different aspects and approaches. The approaches were divided into three embryonic categories: cell division, neural tube growth and neural plate growth. We concluded that the neural plate growth approach provides a suitable platform for simulation of brain formation/neurodevelopment compared to cell division and neural tube growth. We devised a novel equation and designed algorithms that include geometrical and topological algorithms that could fit most of the necessary elements of the neurodevelopmental process during the embryonic period. Hence, the proposed equations and defined mathematical structure would be a platform to generate an artificial neural network that autonomously grows and develops.

#1496 High levels of sclerostin promote bone resorption and changes and mineral metabolism

Abstract Background and Aims The physiological function of sclerostin (SOST) remains unknown. It is known that SOST is produced in osteocytes and functions as an inhibitor of the Wnt/β-catenin pathway. Similarly, it is well-established that low levels of SOST lead to bone alterations affecting cortical bone, resulting in osteopetrosis and reduced calciuria. High levels of SOST are associated with osteoporosis. In this study, we aimed to investigate the impact of three elevated doses of SOST on cortical, trabecular, and subchondral bone, as well as its relationship with other parameters of mineral metabolism. Method Bone histomorphometry, mCT, immunohistochemistry, and analysis of mineral metabolism parameters revealed that high doses of SOST over a 14-day period led to a reduction in trabecular bone volume due to a significant increase in bone resorption through the direct activation of osteoclastogenesis. Results Bone resorption, as measured by TRAP activity, was higher in trabecular, cortical, and subchondral bone. Similarly, high doses of SOST increased the number of hypertrophic chondrocytes, consequently expanding the growth plate area. Cortically, positive TRAP staining was observed, suggesting osteocytic osteolysis and trabecularization of cortical bone. The increased bone resorption resulted in a substantial rise in urinary excretion of phosphorus and calcium, accompanied by elevated levels of FGF23 and a significant decrease in PTH. Conclusion The findings suggest that elevated levels of SOST promote bone resorption through the activation of osteoclasts and the generation of osteocytic osteolysis. The increase in calcium and phosphorus levels led to changes in mineral metabolism, indicating a close relationship between SOST and other mineral metabolism parameters.

Does spinopelvic alignment affect femoral head cartilage and the proximal femoral physis in slipped capital femoral epiphysis? A finite element analysis

BackgroundSlipped capital femoral epiphysis is a prevalent pediatric hip disorder. Recent studies suggest the spine's sagittal profile may influence the proximal femoral growth plate's slippage, an aspect not extensively explored. This study utilizes finite element analysis to investigate how various spinopelvic alignments affect shear stress and growth plate slip. MethodsA finite element model was developed from CT scans of a healthy adult male lumbar spine, pelvis, and femurs. The model was subjected to various sagittal alignments through reorientation. Simulations of two-leg stance, one-leg stance, walking heel strike, ascending stairs heel strike, and descending stairs heel strike were conducted. Parameters measured included hip joint contact area, stress, and maximum growth plate Tresca (shear) stress. FindingsPosterior pelvic tilt cases indicated larger shear stresses compared to the anterior pelvic tilt variants except in two leg stance. Two leg stance resulted in decreases in the posterior tilted pelvi variants hip contact and growth plate Tresca stress compared to anterior tilted pelvi, however a combination of posterior pelvic tilt and high pelvic incidence indicated larger shear stresses on the growth plate. One leg stance and heal strike resulted in higher shear stress on the growth plate in posterior pelvic tilt variants compared to anterior pelvic tilt, with a combination of posterior pelvic tilt and high pelvic incidence resulting in the largest shear. InterpretationOur findings suggest that posterior pelvic tilt and high pelvic incidence may lead to increased shear stress at the growth plate. Activities performed in patients with these alignments may predispose to biomechanical loading that shears the growth plate, potentially leading to slip.

Terminology of the growing bone: A historical study.

Division of the growing long bone into individual basic parts, that is, diaphysis, metaphysis, physes and epiphyses, has become generally accepted and used. However, the origin of these terms is almost unknown. Therefore, we have analyzed the literature in order to identify their sources. The terms epiphysis and apophysis have been used since the time of Hippokrates, although with different meanings. During the time of Galen, the term apophysis was used to describe all types of bone processes, and epiphyses denoted articular ends. The term diaphysis denoting the middle cylindrical part of the long bone was used for the first time by Heister in 1717. The first to use the term metaphysis was Theodor Kocher in his books on gunshot wounds and on bone inflammation of 1895. On the basis of Kocher's study, Lexer published a radiological study of the vascular supply to bones in which he defined metaphyseal blood vessels as a separate group supplying a particular part of the long bone. The epiphyseal growth plate had no particular name from the time of its first description in 1836. During the second half of 19th century, this structure acquired different names. The term "physis" was therefore introduced in 1964 by the American radiologist Rubin in order to label the growth structure between metaphysis and epiphysis clearly. One year later, the term physis also appeared in the radiological literature, and during the following decades it spread in the orthopedic literature.

A rare ACAN non-canonical splicing-site intron variant results in familial short stature

ObjectiveACAN gene variants, prevalent monogenic defects linked to short stature, are characterized by impaired cartilage generation in growth plates. We aimed to unravel the genetic basis of short stature in a specific pedigree by investigating the role of a novel non-canonical splicing-site variant, c.630-13G > A, within the ACAN gene. MethodSanger sequencing was used for pedigree verification, and the effects of this variant on mRNA splicing were analyzed through minigene assay. ResultsThe study revealed that this variant led to the creation of a previously unreported splice site in the fourth intron, resulting in the incorporation of an 11 bp sequence from the intron into the final transcript. This alteration led to a frameshift and formation of a premature termination codon, impacting the structure of the aggrecan protein. ConclusionsWe document the pathogenicity of an ACAN non-canonical splicing-site variant, emphasizing the significance of considering intronic variants during genetic testing.