Intracranial epidermoid cyst is a rare pseudotumor of the nervous system, accounting for 0.2%-1.8% of all intracranial tumors. It is usually located in the cerebellopontine Angle or parasellar area, with insipid onset, slow growth and usually less than 2 cm in diameter. Giant epidermoid cysts that invade the bone have rarely been reported in the literature. Herein, we report a case of giant ECs extradural to the parietal bone, penetrating the skull and continuing to expand outward. In addition, a systematic search of four authoritative databases was conducted to collect the relevant reports of giant epidermoid cyst with diameter > 5cm for the first time, and to discuss the clinical and radiographic features of patients with giant epidermoid cyst and the influence of treatment options.

Intracranial solitary fibrous tumor (SFT)/hemangiopericytoma (HPC) is rare. In this report, a case of epidural hematoma (EDH) that eventually evolved into SFT/HPC is presented. We describe the possible association between the 2 diseases, which has not been previously reported.
A 40-year-old man suffered from an EDH in the right parietal area 12 years ago and accepted conservative treatment. Follow-up computed tomography (CT) scan shows that the density of the right EDH gradually changed from uniform slightly lower density to mixed density. A new CT scan revealed an epidural mass extending to the subcutaneous with local bone destruction. An operation was performed via a large right parietal craniotomy, and the final diagnosis was World Health Organization grade III SFT/HPC after histopathologic examination and immunohistochemical verification. The patient died of deterioration of brain disease 3 months after the final diagnosis.
To our knowledge, this is the first report that HPC occurred in the epidural cavity. We are the first time to describe the possible association between EDH and HPC.

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The murine calvaria has several membrane bones with different tissue origins (e.g., neural crest-derived frontal bone vs. mesoderm-derived parietal bone). Neural crest-derived frontal bone exhibits superior osteogenic activities and bone regeneration. MicroRNA (miRNA) has been emerged as a crucial regulator during organogenesis and is involved in a range of developmental processes. However, the underlying roles of miRNA regulation in frontal bone and parietal bone is unknown.
Total of 83 significantly expressed known miRNAs were identified in frontal bones versus parietal bones. The significantly enriched gene ontology and KEGG pathway that were predicted by the enrichment miRNAs were involved in several biological processes (cell differentiation, cell adhesion, and transcription), and multiple osteogenic pathways (e.g., focal adhesion, MAPK, VEGF, Wnt, and insulin signaling pathway. Focal adhesion and insulin signaling pathway were selected for target verification and functional analysis, and several genes were predicted to be targets genes by the differentially expressed miRNAs, and these targets genes were tested with significant expressions.
Our results revealed a novel pattern of miRNAs in murine calvaria with dual tissue origins, and explorations of these miRNAs will be valuable for the translational studies to enhance osteogenic potential and bone regeneration in the clinic.

Calvarial bone healing remains difficult but may be improved by stimulating chondrogenesis of implanted stem cells. To simultaneously promote chondrogenesis and repress adipogenesis of stem cells, we built a CRISPRai system that comprised inactive Cas9 (dCas9), two fusion proteins as activation/repression complexes and two single guide RNA (sgRNA) as scaffolds for recruiting activator (sgRNAa) or inhibitor (sgRNAi). By plasmid transfection and co-expression in CHO cells, we validated that dCas9 coordinated with sgRNAa to recruit the activator for mCherry activation and also orchestrated with sgRNAi to recruit the repressor for d2EGFP inhibition, without cross interference. After changing the sgRNA sequence to target endogenous Sox9/PPAR-γ, we packaged the entire CRISPRai system into an all-in-one baculovirus for efficient delivery into rat bone marrow-derived mesenchymal stem cells (rBMSC) and verified simultaneous Sox9 activation and PPAR-γ repression. The activation/inhibition effects were further enhanced/prolonged by using the Cre/loxP-based hybrid baculovirus. The CRISPRai system delivered by the hybrid baculovirus stimulated chondrogenesis and repressed adipogenesis of rBMSC in 2D culture and promoted the formation of engineered cartilage in 3D culture. Importantly, implantation of the rBMSC engineered by the CRISPRai improved calvarial bone healing. This study paves a new avenue to translate the CRISPRai technology to regenerative medicine.

BACKGROUND: Polyetheretherketone (PEEK) exhibits stable chemical properties, excellent biocompatibility, and rational mechanical properties that are similar to those of human cortical bone, but the lack of bioactivity impedes its clinical application.
METHODS: In this study, hydroxyapatite (HA) was incorporated into PEEK to fabricate HA/PEEK biocomposite using a compounding and injection-molding technique. The tensile properties of the prepared HA/PEEK composites (HA content from 0 to 40 wt%) were tested to choose an optimal HA content. To evaluate the bioactivity of the composite, the cell attachment, proliferation, spreading and alkaline phosphatase (ALP) activity of MC3T3-E1 cells, and apatite formation after immersion in simulated body fluid (SBF), and osseointegration in a rabbit cranial defect model were investigated. The results were compared to those from ultra-high molecular weight polyethylene (UHMWPE) and pure PEEK.
RESULTS: By evaluating the tensile properties and elastic moduli of PEEK composite samples/PEEK composites with different HA contents, the 30 wt% HA/PEEK composite was chosen for use in the subsequent tests. The results of the cell tests demonstrated that PEEK composite samples/PEEK composite exhibited better cell attachment, proliferation, spreading, and higher ALP activity than those of UHMWPE and pure PEEK. Apatite islands formed on the HA/PEEK composite after immersion in SBF for 7 days and grew continuously with longer time periods. Animal tests indicated that bone contact and new bone formation around the HA/PEEK composite were more obvious than those around UHMWPE and pure PEEK.
CONCLUSIONS: The HA/PEEK biocomposite created by a compounding and injection-molding technique exhibited enhanced osteogenesis and could be used as a candidate of orthopedic implants.

OBJECTIVE: This study aimed to (a) evaluate the stability of the parietal bone of 6-9 months old beagles and (b) examine whether parietal regional superimposition can provide an atraumatic and effective solution for further maxillary expansion study.
METHODS: Six prepubertal 6-month-old male beagles were included. Six miniscrew markers were inserted into the left and right sides of the parietal bone, and two of them were placed bilaterally near the palatal suture. The subjects were scanned with cone beam computed tomography (CBCT) at three time points of T0 (6 months old), T1 (7.5 months old) and T2 (9 months old), respectively. All skull models were analyzed by both the miniscrew superimposition and the parietal regional superimposition.
RESULTS: The two superimposition methods had no significant difference (p > 0.05) in displacements of miniscrew markers between left and right first premolars (PM1). The maxillary superimposition between T0 and T2 indicated that the length and width of the maxillary as well as the width of the zygoma root increased significantly (p < 0.05), while the height of maxillary had no significant difference (p > 0.05) over the 3 months.
CONCLUSIONS: The parietal bone is relatively stable for beagles from 6 months old to 9 months old and thus can be used as a reference region for 3D skull model superimposition of the beagle dog.

BACKGROUND: Penetrating brain injury (PBI) caused by a nail gun is an extremely rare neurosurgical emergency that poses a challenge for neurosurgeons because of its rarity and complexity.
METHODS: Here we present 3 cases of PBI caused by a nail gun. In the first case, the nail entered through the right parietal bone and lodged in the right parietal lobe and basal ganglia. In the second case, the nail entered through the right occipital bone and lodged in the right occipital lobe. In the third case, the nail entered through the right parietal bone and lodged in the right frontal and parietal lobes. All patients underwent surgical removal of the nail. The first patient presented with reduced left-side strength, whereas the second and third patients were neurologically intact on presentation.
CONCLUSIONS: PBI caused by a nail gun can present with differing clinical manifestations, and most cases require immediate surgery. A rational management strategy should provide a good postoperative prognosis with minimal neurologic deficits in these patients.

OBJECTIVE: The mammalian skull vault is a highly regulated structure and consists of several membrane bones of different tissue origins (e.g. neural crest derived frontal bone and mesoderm derived parietal bone). Although membrane bones form through intramembranous ossification, neural crest derived frontal bone has superior osteoblast activity and bone regeneration ability, triggering a novel conception for craniofacial reconstruction and bone regeneration called endogenous calvarial regeneration. However, a comprehensive landscape of the genes and signaling pathways involved in this process is not clear.
METHODS: Transcriptome analysis within the two bone elements is firstly performed to determine the physiological signatures of differential gene expressions in mouse skull vault.
RESULTS: Frontal bone tissues and parietal bone tissues maintain tissue origin through special gene expression similar to neural crest vs mesoderm tissue, and physiological functions between these two tissues are also found in differences related to proliferation, differentiation and extracellular matrix production and clustered signaling pathways.
CONCLUSIONS: Our data provide novel insights into the potential gene regulatory network in regulating the development of neural crest-derived frontal bone and mesoderm-derived parietal bone.

Hyaluronic acid (HA) filler injection is widely used for soft-tissue augmentation. Complications associated with HA filling are not uncommon; however, HA-induced alopecia is a rarely reported complication that could result in severe secondary psychological trauma. The etiology, clinical traits, treatment strategies, outcomes, and possible reversibility of HA-induced alopecia have not been characterized. Here, we report a case in which bilateral temple injections of 6.5 mL of HA led to persistent pain over the left scalp for several days. Although the pain was relieved at day 9 after 600 U of hyaluronidase were injected in the left temple, the patient developed localized alopecia at the left temporoparietal region with central skin necrosis at day 15. After topical applications of recombinant bovine basic fibroblast growth factor gel and 2% minoxidil spay, the necrotic skin wound was healed at day 42. Hair regrowth and normal hair density were restored at day 74. Analyses of Doppler ultrasound examinations and histopathology of the skin biopsy suggested that mild ischemia of the left temporoparietal region led to reversible alopecia, while the permanent hair loss in the left parietal area was associated with severe skin ischemia. Therefore, the key to treatment would be to focus on the effective correction of severe ischemia-induced skin necrosis to prevent permanent hair loss. Level of Evidence V This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .