Skull Tissue Research Articles

Role of p22phox and NOX5 in autophagy and apoptosis of osteoblasts induced by hypoxia

To investigate the role of p22phox and NOX5 in autophagy and apoptosis of osteoblasts induced by hypoxia. The skull tissue of newborn rats was cut into small pieces, and the osteoblasts were separated and purified by the tissue block adherent method and the differential adherent method. The first generation cells were harvested and identified by HE staining, Alizarin red staining, alkaline phosphatase (ALP) staining, and flow cytometry. A three-gas incubator was used to prepare a hypoxia model of osteoblasts. At 0, 3, 6, 12, and 24 hours of hypoxia, the expressions of p22phox, NOX5, and LC3Ⅱ/Ⅰ were detected by Western blot, and the level of reactive oxygen species (ROS) and cell apoptosis rate were detected by flow cytometry. And the time point of the highest level of ROS was selected as the hypoxia time point for subsequent experiments. The first generation osteoblasts were divided into normal group, si-p22phox hypoxia group, and si-NOX5 hypoxia group and subjected to corresponding transfection and hypoxia treatment. The inhibition efficiency of si-p22phox and si-NOX5 were detected by RT-PCR. Then the osteoblasts were divided into normal group, si-NC hypoxia group, si-p22phox hypoxia group, and si-NOX5 hypoxia group. After transfection and hypoxia treatment, Western blot was used to detect the expressions of p22phox, NOX5, autophagy-related proteins (LC3Ⅱ/Ⅰ, Beclin), and apoptosis-related proteins (Bcl-2, Bax), and flow cytometry was used to detect the cell apoptosis rate and level of ROS. The first generation osteoblasts were divided into a hypoxia group for 12 hours (hypoxia group) and a group that simultaneously inhibited si-p22phox and si-NOX5 and hypoxia for 12 hours (inhibition+hypoxia group). The expressions of Beclin and Bax were observed by immunofluorescence staining after the corresponding treatment. After identification, the isolated cells were osteoblasts. After hypoxia treatment, the relative expressions of p22phox, NOX5, and LC3Ⅱ/Ⅰ proteins and the apoptosis rate of osteoblasts gradually increased ( P<0.05), and the level of ROS also significantly increased ( P<0.05) and reached the peak value at 12 hours. The 12-hour hypoxia model was selected for subsequent experiments. Silencing the p22phox gene did not affect the expression of NOX5, and silencing the NOX5 gene did not affect the expression of p22phox. Compared with hypoxia treatment, the relative expressions of LC3Ⅱ/Ⅰ, Beclin, and Bax proteins after inhibiting the expression of p22phox or NOX5 gene significantly decreased ( P<0.05), the relative expression of Bcl-2 protein significantly increased ( P<0.05), the cell apoptosis rate and level of ROS also significantly decreased ( P<0.05). After silencing the expressions of p22phox and NOX5 genes at the same time, the immunofluorescence staining showed that the fluorescence of Beclin and Bax were weak. Inhibiting the expressions of p22phox and NOX5 genes can reduce the level of ROS in osteoblasts under hypoxia-induced conditions, and at the same time reduce autophagy and apoptosis, especially attenuate the excessive apoptosis of cells in the early to late stages, and strengthen the hypoxic osteoblasts proliferation.

RNA-sequence reveals differentially expressed genes affecting the crested trait of Wumeng crested chicken

Wumeng crested chicken has a cluster of slender feathers on its head, and the underlying skull region exhibits an obvious tumor-like protrusion. This is the typical skull structure of crested chickens. The associated regulatory genes are located on autosomes and are incompletely dominant. This trait is related to brain herniation, but the genetic mechanisms of its formation and development are unclear. In this study, RNA sequencing (RNA-Seq) analysis was conducted on 6 skull tissue samples from 3 Wumeng crested chickens with prominent skull protrusions and 3 without a prominent skull protrusion phenotype. A total of 46,376,934 to 43,729,046 clean reads were obtained, the percentage of uniquely mapped reads compared with the reference genome was between 89.73%–91.00%, and 39,795,458–41,836,502 unique reads were obtained. Among different genomic regions, the highest frequency of sequencing reads occurred in exon regions (85.44–88.28%). Additionally, a total of 423 new transcripts and 26,999 alternative splicings (AS) events were discovered in this sequencing analysis. This study identified 1,089 differentially expressed genes (DEGs), among which 485 were upregulated and 604 were downregulated. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses indicated that the DEGs were enriched in terms related to signal transduction, cell development, cell differentiation, the lysosome, serine, and threonine metabolism, and the interaction of cytokines with cytokine receptors. Based on the comprehensive analysis of DEGs combined with reported quantitative trait loci (QTLs), the expression of BMP2, EPHA3, EPHB1, HOXC6, SCN2B, BMP7, and HOXC10 was verified by real-time quantitative polymerase chain reaction (qRT-PCR). The qRT-PCR results were consistent with the RNA-Seq results, indicating that these 7 genes may be candidates genes regulating the crested trait.

The mechanical and microstructural properties of the pediatric skull

The pediatric skull differs drastically from the adult skull in terms of composition, rigidity, and structure. However, there is limited data which quantifies the mechanical properties of the pediatric skull. The lack of mechanical data may inhibit desired pediatric craniofacial surgical outcomes as current methodologies and materials employed for the pediatric population are adapted from those used for adults. In this study, normally discarded parietal bone tissue from eight pediatric craniosynostosis surgery patients (aged 4 to 10 months) was collected during reconstructive surgery and prepared for microstructural analysis and mechanical testing. Up to 12 individual coupon samples of fresh, never frozen tissue were harvested from each specimen and prepared for four-point bending testing to failure. The microstructure of each sample was analyzed using micro-computed tomography before and after each mechanical test. From this analysis, effective geometric and mechanical properties were determined for each sample (n = 68). Test results demonstrated that the pediatric parietal skull was 2.0 mm (±0.4) thick, with a porosity of 36% (±14). The effective modulus of the tissue samples, determined from the initial slope of the sample stress-strain response using Euler beam theory and a nonlinear Ramberg-Osgood stress-strain relationship, was 4.2 GPa (±2.1), which was approximately three times less stiff than adult skull tissue reported in the literature. Furthermore, the pediatric skull was able to bend up to flexural failure strains of 6.7% (±2.0), which was approximately five times larger than failure strains measured in adult skull. The disparity between the measured mechanical properties of pediatric skull tissue and adult skull tissue points towards the need to reevaluate current surgical technologies, such as pediatric cranial surgical hardware, so that they are more compatible with pediatric tissue.

Ecotoxicology of alpine streams in the West Carpathians-Alpine Bullhead (Cottus poecilopus) and high mountain flash flood effects.

Flash floods represent a serious threat to wildlife, water biota, and human life in pre-alpine regions, particularly in recent historical memory. The alpine bullhead is an established bioindicator of water quality in mountain streams, which can be adversely affected by an increased propensity for flash flooding. The aim of this study was to examine the effect of flash flooding on the variation of chemical elements found in the skull of alpine bullheads, with a focus on inter-annual effects. Their bone tissue reflects an increased concentration of K and Cl and a decreased concentration of biogenic Cr, Zn, and Mo, absorbed mainly through the gills, for up to 2 years following a flood. During autumn, following a summer flash flood, the amount of Mn and Fe present in skull tissues of fish was found to have increased, tapering off again over the following year. These metals are predominantly ingested by bullheads while feeding. The lack of specific types of biogenic concentration in the water may be critical to the definition of presence/absence patterns, as populations were shown to decline 2 to 3 years post-flood. Pre-alpine streams are particularly susceptible to this type of flooding. The decreases in biogenic elements and increase of K and Cl exhibited in bullhead tissues indicate that a negative ecological footprint due to flash floods can still be observed several years following the event.

Preliminary Investigation of Magnetic Resonance Imaging Guided Beamforming in Flexible Type Ultrasonic Array Transducers

A flexible-shaped ultrasonic array probe that can be used in a high magnetic field environment in an MRI gantry has been developed. Given that this probe can be fixed according to the shape of the skull’s surface, it is particularly applicable for imaging in the brain. To perform ultrasonic beamforming using a bent probe, it is necessary to measure the bent shape. Therefore, in this research, the curvature of the probe was estimated using MRI. A phantom with ellipse surface close to the shape of a skull was created using a 3D printer. The probe was arranged along the phantom surface to perform MRI and ultrasonic beamforming. The ultrasonic array transducer had 192 elements made from 1-3 composite piezoelectric materials with an element spacing of 0.3 mm. Eight MR position markers were attached to the probe in parallel in two rows of four each, with the array transducer in between. The delay time of each element in dynamic focusing for reception was calculated from its position estimated by the curvature of the probe. To evaluate the feasibility of this method, a B-mode image of 0.98 mm-diameter-thread targets placed in water was generated. The beam width at half maximum of the echo peak in the lateral direction from the thread target set up near the transmission focal point was calculated based on the B-mode image. It was found that the beam width of 1.32 mm in the proposed method, which was close to the thread diameter, whereas that was 4.38 mm in the conventional method that did not consider the bending of the probe. Consequently, the proposed beamforming technique is feasible for ultrasonic imaging through an arbitrary curved surface. Practical applications with a head phantom mimicking skull and cerebral tissue are expected.

The crest phenotype in domestic chicken is caused by a 195 bp duplication in the intron of HOXC10

The Crest mutation in chicken shows incomplete dominance and causes a spectacular phenotype in which the small feathers normally present on the head are replaced by much larger feathers normally present only in dorsal skin. Using whole-genome sequencing, we show that the crest phenotype is caused by a 197 bp duplication of an evolutionarily conserved sequence located in the intron of HOXC10 on chromosome 33. A diagnostic test showed that the duplication was present in all 54 crested chickens representing eight breeds and absent from all 433 non-crested chickens representing 214 populations. The mutation causes ectopic expression of at least five closely linked HOXC genes, including HOXC10, in cranial skin of crested chickens. The result is consistent with the interpretation that the crest feathers are caused by an altered body region identity. The upregulated HOXC gene expression is expanded to skull tissue of Polish chickens showing a large crest often associated with cerebral hernia, but not in Silkie chickens characterized by a small crest, both homozygous for the duplication. Thus, the 197 bp duplication is required for the development of a large crest and susceptibility to cerebral hernia because only crested chicken show this malformation. However, this mutation is not sufficient to cause herniation because this malformation is not present in breeds with a small crest, like Silkie chickens.

Role and mechanism of endoplasmic reticulum stress response induced by wear particles in osteolysis

To analyze the role of endoplasmic reticulum stress response in the development of osteoblast apoptosis and osteolysis in osteolytic bone tissue, and to explore the causes of artificial joint loosening, so as to provide new ideas and theoretical basis for the prevention and treatment of artificial joint loosening. The animal model of osteolysis induced by wear particles was established by mouse skull, and randomly divided into 4 groups, 7 rats in each group:group 1, blank control group;group 2, wear particles tial6v4 nano alloy powder (TiNPs) group;group 3, endoplasmic reticulum stress response positive control (TiNPs+Tg) group; group 4, endoplasmic reticulum stress response inhibitor (TiNPs+4-PBA) group. The pathological changes of osteolysis were observed by toluidine blue staining, HE staining and ALP staining;the expression of endoplasmic reticulum stress response marker protein was detected by Western Blotting;the apoptosis of osteoblasts in osteolytic skull tissue was detected by TUNEL and Caspase-3 immunohistochemistry. Wear particles TiNPs can induce osteolysis in vitro, aggravate the infiltration of inflammatory cells and inhibit the differentiation and maturation of osteoblasts. At the same time, wear particles can also up regulate the markers of endoplasmic reticulum stress response and promote the apoptosis of osteoblasts in osteolytic bone tissue. After adding 4-PBA, an inhibitor of endoplasmic reticulum stress (4-PBA), on the basis of wear particles TiNPs, the symptoms of osteolysis were significantly relieved, bone erosion and inflammatory infiltration were significantly reduced, the differentiation and maturation of osteoblasts were improved, the number of apoptotic osteoblasts decreased sharply, and the expression of endoplasmic reticulum stress marker protein gradually decreased. Endoplasmic reticulum stress is involved in the formation of osteolysis and plays an important role in the occurrence and development of osteolysis. At the same time, endoplasmic reticulum stress can be used as a new therapeutic target to provide new ideas and methods for clinical reversal or treatment of osteolysis and aseptic loosening.

Serum nickel is associated with craniosynostosis risk: Evidence from humans and mice

BackgroundTo date, few studies have explored the effects of exposure to metal mixtures on adverse developmental outcomes, and no reported studies have linked metal exposure to craniosynostosis (CS). The purpose of this study is to investigate the association between metal exposure and the risk of CS by conducting epidemiological and experimental studies. MethodsInductively coupled plasma mass spectrometry (ICP-MS) was used to measure the concentrations of 6 metals (chromium [Cr], nickel [Ni], tin [Sn], arsenic [As], thallium [Tl], and lead [Pb]) in serum samples from 174 CS patients and 85 control individuals. Non-syndromic patients with isolated sagittal suture closure were selected as the case group, and healthy children matched by sex and age were selected as controls. Bayesian kernel machine regression (BKMR) models were used to account for joint metal effects. Multiple logistic regression analysis was used to explore the association between metal concentration and CS occurrence, with adjustment for potential confounders. During pregnancy, mice were exposed to Ni (0, 0.05, or 0.1 g/kg/day) until weaning, and the widths of the sutures and shapes of the skull were analysed by micro-CT 3D imaging and histological analysis. MC3T3-E1 cells were treated with Ni (0, 0.005, or 0.05 μg/mL) for 72 h. Alkaline phosphate (ALP) staining and Alizarin red staining were performed to observe the development of osteoblasts. The expression levels of osteoblast-related genes were also detected. ResultsA positive association between the metal mixture and CS risk was observed based on population data; the Ni group had the highest conditional posterior inclusion probability (PIP), at 0.8416, and in the fully adjusted model, the highest Ni exposure level had a more significant association with CS (coefficient = 2.65, 95% CI: 0.29, 5.02) than the lowest Ni exposure level. The mean widths of the sagittal sutures in mice were 8.8 ± 0.6 mm in the control group, 8.0 ± 0.8 mm in the 0.05 g/kg/day group and 6.8 ± 0.4 mm in the 0.1 g/kg/day group. After Ni exposure, ALP gene expression in skull tissue was increased, and ALP activity was increased in MC3T3-E1 cells. Moreover, increased collagen content in mouse skull sections and elevated osteocalcin (OCN) expression in MC3T3-E1 cells were observed in the Ni-treated groups compared to the control group. ConclusionsThis study is the first to provide evidence that increased serum Ni was associated with an increased risk of CS. Early life exposure to Ni promoted osteogenesis during skull growth, which may contribute to the development of CS.

OTA-based tunable fractional-order devices for biomedical engineering

This research realizes fractional-order devices or constant phase element (CPE) using continued fraction expansion (CFE) and rational function approximation methods. An RC ladder network prototype was realized using CFE based on the Cauer network principle. The RC ladder network and signal flow graph (SFG) were employed to realize the proposed CPE. Voltage gain circuits and voltage-mode integrators were realized by using operational transconductance amplifiers (OTA) and grounded capacitors. The proposed CPE was subsequently synthesized using voltage gain circuits and voltage-mode integrators based on SFG. The proposed CPE could function as fractional-order capacitor and fractional-order inductor. Besides, the CPE could be constructed in arbitrary fractional-orders. The impedance and operation frequency are independently tunable by manipulating OTA bias current. To validate, the proposed fractional-order device was applied to six types of electrical Cole models of skull tissues, and simulation results were compared with the approximation function and theory. The electrical characteristics of the Cole models based on the proposed CPE are comparable to the theoretical characteristics of the Cole model.

Repair of alveolar cleft bone defects by bone collagen particles combined with human umbilical cord mesenchymal stem cells in rabbit

BackgroundAlveolar cleft is a type of cleft lip and palate that seriously affects the physical and mental health of patients. In this study, a model of the alveolar cleft phenotype was established in rabbits to evaluate the effect of bone collagen particles combined with human umbilical cord mesenchymal stem cells (HUC-MSCs) on the repair of alveolar cleft bone defects.MethodsA model of alveolar clefts in rabbits was established by removing the incisors on the left side of the upper jaw bone collagen particles combined with HUC-MSCs that were then implanted in the defect area. Blood biochemical analysis was performed 3 months after surgery. Skull tissues were harvested for gross observation, and micro-focus computerised tomography (micro-CT) analysis. Tissues were harvested for histological and immunohistochemical staining. The experiments were repeated 6 months after surgery.ResultsBone collagen particles and HUC-MSCs showed good biocompatibility. Bone collagen particles combined with HUC-MSCs were markedly better at inducing bone repair and regeneration than bone collagen particles alone.ConclusionsCombining HUC-MSCs with bone collagen particles provides a simple, rapid and suitable method to fill a bone defect site and treat of alveolar cleft bone defects.

A Composite Tissue Engineered Bone Material Consisting of Bone Mesenchymal Stem Cells, Bone Morphogenetic Protein 9 (BMP9) Gene Lentiviral Vector, and P3HB4HB Thermogel (BMSCs-LV-BMP9-P3HB4HB) Repairs Calvarial Skull Defects in Rats by Expression of Osteogenic Factors.

BackgroundBone tissue engineering has been proven to be an appropriate approach for treating bone defects. This study aimed to investigate the effects and mechanism of a composite tissue engineered bone material consisting of bone mesenchymal stem cells (BMSCs), bone morphogenetic protein (BMP9) gene lentiviral vector, and P3HB4HB thermogel (BMSCs-LV-BMP9-P3HB4HB) on calvarial skull defects in rats.Material/MethodsLV-BMP9 viral vector was structured and infected to BMSCs-P3HB4HB composite scaffold, which was named as BMSCs-P3HB4HB composite bone repair material. Adipogenic differentiation was determined by oil-red O (ORO) and alkaline phosphatase (ALP) staining. Osteogenic differentiation was measured using Alizarin red staining. Cell viability was examined using Cell-Counting Kit-8 (CCK-8) assay. Protein expression of osteogenic factors, including BMP9, runt-related transcription factor 2 (RUNX2), osteocalcin (OCN), osteopontin (OPN), and osterix (OSX), was detected with Western blot assay and immunohistochemistry. mRNA of these osteogenic factors was examined by RT-PCR. Histological changes were examined with hematoxylin and eosin (H&E) and Masson’s trichrome staining. Bone repair was measured using micro-computed tomography (micro-CT).ResultsBMSCs and LV-BMP9-infected BMSCs demonstrated adipogenic and osteogenic differentiation potential. BMSCs-P3HB4HB scaffold demonstrated good cell-tissue compatibility. BMSCs-LV-BMP9-P3HB4HB exhibited significantly higher osteogenic ability and cell viability of BMSCs compared to BMSCs-LV-P3HB4HB (p<0.05). BMSCs-LV-BMP9-P3HB4HB significantly promoted osteogenic factors (RUNX2, OCN, OPN, and OSX) expression compared to the BMSCs-LV-P3HB4HB group (p<0.05) in both BMSCs and in calvarial defect rats. BMSCs-LV-BMP9-P3HB4HB demonstrated stronger repair ability. BMSCs-LV-BMP9-P3HB4HB significantly alleviated pathological injury and increased collagen fiber production compared to the BMSCs-LV-P3HB4HB group (p<0.05).ConclusionsBMSCs-LV-BMP9-P3HB4HB composite bone repair material can effectively repair injured skull tissues of calvarial defect rats through triggering osteogenic factors expression. The present generated bone repair material may have applications in tissue engineering in regeneration of bone defects.

Isolation and Characterization of Human Suture Mesenchymal Stem Cells In Vitro.

Background and ObjectivesCranial sutures play a critical role in adjustment of skull development and brain growth. Premature fusion of cranial sutures leads to craniosynostosis. The aim of the current study was to culture and characterize human cranial suture mesenchymal cells in vitro.MethodsThe residual skull tissues, containing synostosed or contralateral suture from three boys with right coronal suture synostosis, were used to isolate the suture mesenchymal cells. Then, flow cytometry and multilineage differentiation were performed to identify the typical mesenchymal stem cell (MSC) properties. Finally, we used quantitative real-time polymerase chain reaction (RT-PCR) to detect the mRNA expression of osteogenesis and stemness related genes.ResultsAfter 3 to 5 days in culture, the cells migrated from the tissue explants and proliferated parallelly or spirally. These cells expressed typical MSC markers, CD73, CD90, CD105, and could give rises to osteocytes, adipocytes and chondrocytes. RT-PCR showed relatively higher levels of Runx2, osteocalcin and FGF2 in the fused suture MSCs than in the normal cells. However, BMP3, the only protein of BMP family that inhibits osteogenesis, reduced in synostosed suture derived cells. The expression of effector genes remaining cell stemness, including Bmi1, Gli1 and Axin2, decreased in the cells migrated from the affected cranial sutures.ConclusionsThe MSCs from prematurely occlusive sutures overexpressed osteogenic related genes and down-regulated stemness-related genes, which may further accelerate the osteogenic differentiation and suppress the self-renewal of stem cells leading to craniosynostosis.

Prenatal diagnosis of anencephaly and acrania in pregnant females - Report series of eight cases

Acrania and anencephaly are characterized by the partial or complete absence of skull and brain tissue. Due to this, the neural tissue is exposed and it leads to non-function of few parts of the hemispheres. A total of eight cases of acrania and anencephaly were included in the report. Five cases were acrania and three cases were anencephaly. Both cases were diagnosed between 15 and 24 weeks of gestation period. In the present report, all the pregnant women carry fetuses with neural tube defects. Out of five acrania cases, there is a partial or complete absence of cranium in all the cases, and in one case, there is a twin intrauterine gestational sac that was noted. However, out of twin sac, the first one is having a good heart rate (155 bpm) and the second fetus is having no cardiac activity, i.e., early fetal demise. On the other hand, out of three anencephaly cases, two anencephaly cases were diagnosed with partial absence of the fetal brain and the complete absence of the cranium, and in one case, there is a partial absence of cerebral parenchymal tissue above the orbit with the absence of cranial vault. By the use of ultrasonography, we can diagnose the anencephaly and acrania at a very early stage without any side effects. The cause of anencephaly and acrania is dependent on the number of factors one of which is a folic acid deficiency. Sentence is reviewed and corrected): It is always better to consume the folic acid supplements that are advised by the physician during the planning of pregnancy to avoid the congenital anomalies of the fetus like anencephaly and acrania. The ultimate focus of the study is to evaluate the morphology of the fetus in case of anencephaly and acrania which could lead to the early detection of abnormalities and also to create awareness among people to take folic acid supplements to eschew such abnormalities.

THE INFLUENCE OF BRAIN TISSUE MATERIAL PARAMETERS ON THE RESPONSE OF DYNAMIC CHARACTERISTICS BASED ON FINITE ELEMENT MODEL

Aiming at the uncertainty of material parameters of human brain tissue, the influence of tissue material performance sensitivity on frequency and mode shape under free vibration is studied. In this paper, the 50th percentile finite element (FE) model of human head and neck with detailed anatomical characteristics has been chosen as the research object, the parameters of skull, cerebrospinal fluid (CSF) and brain tissue materials with high sensitivity are analyzed by orthogonal test design and variance analysis. The results show that the natural frequencies of Group 7, Group 8 and Group 9 are all around 230[Formula: see text]Hz, which are basically consistent with the initial parameter of 229.18[Formula: see text]Hz, and the intracranial displacements of the three groups are also concentrated on the lateral nasal cartilage. The main reason is that the Young’s modulus of the skull used in three groups of experiments is 9780[Formula: see text]Mpa, which is close to the initial parameter of 8000[Formula: see text]Mpa. It indicates that the material parameter of the skull has the greatest influence on the dynamic characteristics of human head and neck, followed by the CSF and brain tissue. This study provides an effective method for vehicle safety and head and neck injury protection, and supplies a reference for FE analysis of head collision damage.

Real‐Time IR Tracking of Single Reflective Micromotors through Scattering Tissues

AbstractMedical micromotors have the potential to lead to a paradigm shift in future biomedicine, as they may perform active drug delivery, microsurgery, tissue engineering, or assisted fertilization in a minimally invasive manner. However, the translation to clinical treatment is challenging, as many applications of single or few micromotors require real‐time tracking and control at high spatiotemporal resolution in deep tissue. Although optical techniques are a popular choice for this task, absorption and strong light scattering lead to a pronounced decrease of the signal‐to‐noise ratio with increasing penetration depth. Here, a highly reflective micromotor is introduced which reflects more than tenfold the light intensity of simple gold particles and can be precisely navigated by external magnetic fields. A customized optical IR imaging setup and an image correlation technique are implemented to track single micromotors in real‐time and label‐free underneath phantom and ex vivo mouse skull tissues. As a potential application, the micromotors speed is recorded when moving through different viscous fluids to determine the viscosity of diverse physiological fluids toward remote cardiovascular disease diagnosis. Moreover, the micromotors are loaded with a model drug to demonstrate their cargo‐transport capability. The proposed reflective micromotor is suitable as theranostic tool for sub‐skin or organ‐on‐a‐chip applications.

Tullio phenomenon and drop attacks – An unsuspected cause

Tullio phenomenon or loudness intolerance is most commonly associated with superior semicircular canal dehiscence. We describe a patient presenting solely with this phenomenon and found to have an unsuspected cause. A 43-years-old gentleman presented to us complaining of intolerance to loud noise, occasionally leading to falls, for six months. These complaints were insidious in onset and steadily progressing. Interestingly, the intolerance in heavy traffic used to subside on wearing a helmet. There was no history of hearing loss, tinnitus, earache, or ear discharge. Clinical tests of hearing including Rinne, Weber and absolute bone conduction test were within normal limits. The neurologic as well as systemic examination was normal. Pure tone audiometry (PTA) showed mild conductive hearing loss in left ear and brainstem auditory evoked response (BAER) was normal. Patient’s skull radiograph showed multiple large lytic lesions giving the appearance of “geographical skull”. Chest X-ray showed a lytic lesion with pathological fracture involving posterior part of in left sided rib. Computed Tomography of head with bone window also showed multiple lytic lesions in skull (Figure 1,2). Brain parenchyma was normal. Incisional biopsy of one of the skull lesions was performed, which was consistent with a diagnosis of Langerhans cell histiocytosis (LCH) (Figure 3). The patient showed considerable improvement after being initiated on Etoposide and Vinblastine. LCH is a rare cause of Tullio phenomenon. It appears that the loss of skull tissue due to lytic lesions leads to impairment of “modifier” function of intact skull, resulting in “volume conduction” and noise intolerance.

Multi-level customized 3D printing for autogenous implants in skull tissue engineering

Three-dimensional (3D) printing of decellularized extracellular matrix (ECM) has been achieved to ensure real physiological environments for tissue engineering. However, the limited source, biocompatibility, and biosafety of decellularized ECM are deficiencies in its large clinical use. Autogenous ECM is biocompatible, bioactive, and biosafe, making it an optimal choice for future clinical applications of 3D printing. Here, we developed a multi-level customized 3D printing (MLC-3DP) strategy applying autogenous bone matrix (Auto-BM). This MLC-3DP includes shape specificity (shape), material specificity (Auto-BM), and cell specificity (autogenous cells) for true patient-specific repairs. Auto-BM (skull flaps) is readily accessible for specific patients after craniectomy, providing sufficient autogenous materials for MLC-3DP. Under mild conditions of this strategy, human-scale 3D printed samples can be fabricated using bioactive micron-sized Auto-BM particles. Multi-level customized autogenous bones (MLC-Auto-Bones) are finally obtained by combining autogenous bone marrow-derived mesenchymal stem cells (Auto-BMSCs). With autogenous materials and cells, MLC-Auto-Bones are inherently biocompatible and biosafe, providing good bioactivity for osteogenesis. In this implant, Auto-BMSCs can spontaneously differentiate into osteoblasts in vitro without additional osteogenic factors. In critical-sized skull defect models in vivo (3 months), implants integrate tightly to the defects’ margin, facilitate mineralization, and generate vascularized mature bone. This work provides not only feasibility for patient-specific implants for skull defects, but also potential patient-specific solutions for other similar clinical requirements.

Skull's Photoacoustic Attenuation and Dispersion Modeling with Deterministic Ray-Tracing: Towards Real-Time Aberration Correction.

Although transcranial photoacoustic imaging has been previously investigated by several groups, there are many unknowns about the distorting effects of the skull due to the impedance mismatch between the skull and underlying layers. The current computational methods based on finite-element modeling are slow, especially in the cases where fine grids are defined for a large 3-D volume. We develop a very fast modeling/simulation framework based on deterministic ray-tracing. The framework considers a multilayer model of the medium, taking into account the frequency-dependent attenuation and dispersion effects that occur in wave reflection, refraction, and mode conversion at the skull surface. The speed of the proposed framework is evaluated. We validate the accuracy of the framework using numerical phantoms and compare its results to k-Wave simulation results. Analytical validation is also performed based on the longitudinal and shear wave transmission coefficients. We then simulated, using our method, the major skull-distorting effects including amplitude attenuation, time-domain signal broadening, and time shift, and confirmed the findings by comparing them to several ex vivo experimental results. It is expected that the proposed method speeds up modeling and quantification of skull tissue and allows the development of transcranial photoacoustic brain imaging.

Bone-targeting carbon dots: effect of nitrogen-doping on binding affinity.

Novel fluorescent carbon dots (CDs) for bone imaging were fabricated via a facile hydrothermal method using alendronate in the absence of a nitrogen-doping precursor to enhance bone affinity. One-step synthesized alendronate-based CDs (Alen-CDs) had strong binding activity for calcium-deficient hydroxyapatite (CDHA, the mineral component of bones) scaffold, rat femur, and bone structures of live zebrafish. This was attributed to the bisphosphonate group present on the CD surface, even after carbonization. For comparison, the surface effects of nitrogen-doped CDs obtained using ethylenediamine (EDA), i.e., Alen-EDA-CDs, were also investigated, focusing on the targeting ability of distinct surface functional groups when compared with Alen-CDs. An in vivo study to assess the impact on bone affinity revealed that Alen-CDs effectively accumulated in the bone structures of live zebrafish larvae after microinjections, as well as in the bone tissues of femur extracted from rats. Moreover, Alen-CD-treated zebrafish larvae had superior toleration, retaining skeletal fluorescence for 7 days post-injection (dpi). The sustainable capability, surpassing that of Alizarin Red S, suggests that Alen-CDs have the potential for targeted drug delivery to damaged bone tissues and provides motivation for additional in vivo investigations. To our knowledge, this is the first in vitro, ex vivo, and in vivo demonstration of direct bone-targeted deliveries, supporting the use of fluorescent CDs in the treatment of various bone diseases such as osteoporosis, Paget's disease, and metastatic bone cancer.

A mosaic structure multi-level vascular network design for skull tissue engineering

In human skull tissue engineering scaffolds, cell growth and osteogenesis are limited due to the lack of vascular structure. Therefore, a mosaic structure vascular parameterized design method is proposed according to the scanning characteristics of the diploic vein. Using micro-CT scans of skull samples, the features of the diploic vein were extracted, and a multi-level vascular network model was established based on a power diagram. Considering the characteristics of blood flow in the veins, finite element analysis (FEA) of the fluid-solid coupling was established to analyze the effect of blood on vessels with four-level mosaic structures. The results showed that the deformation and stress distribution of vessels were reasonable, and the blood pressure, velocity and shear stress in the designed vascular structure could meet the cell growth requirements. The mosaic structure was prepared by PDMS and cultured in vitro using HUVECs. It was found that most of the cells survived after 48 h, and some cells were attached to the surface mosaic structure. In this method, different levels of vessels nest together, with a curvature that matches the shape of the skull, forming a similar morphology to the native diploic vein, and the local structures can be adjusted flexibly. This mosaic structure vascular design method can be used for network vascular design and experimental studies in hard tissues.