As one type of primary brain injury, diffuse axonal injury (DAI) has specific traumatic mechanisms. The occurence of DAI is close to the loading property, loading manner, structural characteristics of skull, brain tissue and neck. This article demonstrated how the stress and strain varied in brain tissue effected by the load magnitude, load waveform, load frequency, load duration, linear acceleration, rotational acceleration, compounded linear/rotational acceleration, brain tissue, cerebral falx, cerebellar tentorium, skull and neck, and what are the relationships between these factors and the event of DAI.
Animals ; Biomechanical Phenomena ; Brain ; physiology ; Diffuse Axonal Injury ; physiopathology ; Humans ; Neck ; physiology ; Skull ; physiology ; Stress, Mechanical

The human skull impedance was quantitatively measured by means of Frequency Response Analyzer and its software. The impedance-frequency response curves of human skull were obtained. By analyzing the curves, we found that the characteristic frequency of human skull should be around 10 KHz.
Adult ; Electric Impedance ; Humans ; Middle Aged ; Skull ; physiology ; Time Factors

OBJECTIVETo look for the way of three-dimensional simulation of the craniofacial system.

METHODSA three-dimensional laser scanner was used for gypsum models digitization and computed tomography scans was employed for skull reconstruction, then the data of teeth and temporomandibular joint were picked up and integrated. The ARCUS sigma system was used to record spatial mandibular movements. The data of both digital reconstruction and spatial movements were transferred into one coordinate system. The software for three-dimensional simulation was programmed.

RESULTSThe preliminary program could be used to analyze static and dynamic occlusion and gnathic relations, to check the contact points and to show from various visual angles and slices. The occlusal plane, curves, and helical axis were initially defined and displayed.

CONCLUSIONSUsing available instruments and methods, we developed the primary edition for three-dimensional simulation of the craniofacial system. However, it is far from a mature system and there is still plenty of work to be done.

Dental Occlusion ; Humans ; Imaging, Three-Dimensional ; Mandible ; physiology ; Models, Anatomic ; Skull ; Temporomandibular Joint ; physiology ; Tooth

Biomechanical Phenomena ; Bone Substitutes ; therapeutic use ; Child ; Facial Bones ; physiology ; Fracture Fixation, Internal ; Fracture Healing ; Humans ; Skull ; physiology ; Skull Fractures ; therapy ; Stress, Mechanical

We have researched the viscoelastic properties of the cancellous bones of the os calcaneus, os lunatum and os capitalum. The compressing stress relaxation experiment and the creep experiment in the vertical, horizontal and 45 degree directions on the os calcaneus were performed. The data and curve of the compressing stress relaxation and creep were obtained. By masing regression analysis we worked out the compressing reduced stress relaxation and creep functions and curves. The results show that the quantities of compressing stress relaxation and creep of the calcaneus in the vertical direction are larger than those in the other two directions. The initial quantities of creep of the os capitalum are larger than those of the os lunatum, and there are no significant different between the quantities of stress relaxation of the cancellous bones of the os lunatum and os capitalum.
Adult ; Calcaneus ; physiology ; Elasticity ; Humans ; Linear Models ; Lunate Bone ; physiology ; Male ; Models, Biological ; Regression Analysis ; Skull ; physiology ; Stress, Mechanical ; Weight-Bearing ; physiology

BACKGROUND: Prenatal tongue development may affect oral-craniofacial structures, but this muscular organ has rarely been investigated. METHODS: In order to document the physiology of prenatal tongue growth, we histologically examined the facial and cranial base structures of 56 embryos and 106 fetuses. RESULTS: In Streeter's stages 13-14 (fertilization age [FA], 28 to 32 days), the tongue protruded into the stomodeal cavity from the retrohyoid space to the cartilaginous mesenchyme of the primitive cranial base, and in Streeter's stage 15 (FA, 33 to 36 days), the tongue rapidly swelled and compressed the cranial base to initiate spheno-occipital synchondrosis and continued to swell laterally to occupy most of the stomodeal cavity in Streeter's stage 16-17 (FA, 37 to 43 days). In Streeter's stage 18-20 (FA, 44 to 51 days), the tongue was vertically positioned and filled the posterior nasopharyngeal space. As the growth of the mandible and maxilla advanced, the tongue was pulled down and protruded anteriorly to form the linguomandibular complex. Angulation between the anterior cranial base (ACB) and the posterior cranial base (PCB) was formed by the emerging tongue at FA 4 weeks and became constant at approximately 124degrees-126degrees from FA 6 weeks until birth, which was consistent with angulations measured on adult cephalograms. CONCLUSIONS: The early clockwise growth of the ACB to the maxillary plane became harmonious with the counter-clockwise growth of the PCB to the tongue axis during the early prenatal period. These observations suggest that human embryonic tongue growth affects ACB and PCB angulation, stimulates maxillary growth, and induces mandibular movement to achieve the essential functions of oral and maxillofacial structures.
Adult ; Axis, Cervical Vertebra ; Embryonic Structures* ; Fetus* ; Humans ; Mandible ; Maxilla ; Mesoderm ; Parturition ; Physiology ; Skull Base ; Tongue*

OBJECTIVETo investigate the biomechanical characters of human dura and its substitutes and to establish guidelines for selection of optimal repair materials for reconstruction of skull base defects.

METHODSA measurement of creep properties of human dura and its substitutes were conducted using biomechanical tests. The dynamic changes of biomechanical properties of canine dura obtained from skull base defects were observed as well.

RESULTSThe creep properties of human dura presented a linear-relationship between initial strain and stress, and the creep strain increased slowly with time. The creep compliance formula for human dura and its substitutes was as follows: J (t) = J(0) + Kf (t). The initial compliance of canine dura in skull base defects was reduced by 35%, 46% and 50%, respectively 1, 3 and 6 months after surgery.

CONCLUSIONThe optimal material for the repair of skull base defects can be estimated using creep compliance analysis. The less the compliance, the better the property of anti-protrusion. Fresh human dura is the least compliant and then in increasing order are lyophilized human dura, fresh human pericranium, Terylene and silicon membranes. The pattern of biomechanical characteristics of the dura mater at skull base defects shows that the strain ability of the dura mater decreases distinctly for 1 - 3 months and then remains almost unchanged for 3 - 6 months after surgery.

Animals ; Biomechanical Phenomena ; Dogs ; Dura Mater ; physiology ; Humans ; Skull Base ; surgery

OBJECTIVETo investigate the feasibility of using marrow stromal osteoblast-cancellous bone matrix compound artificial bone (MCCAB) as tissue-engineered bone, the osteogenesis of MCCAB in the cranial defect was observed in the experiment.

METHODSThe in vitro cultivated and induced marrow stromal cells of adult New Zealand rabbits were seeded into the alginate-cancellous bone matrix to form MCCAB. The MCCAB was then implanted into the cranial defect for 4 to 8 weeks. The cancellous bone matrix (CBM) alone or the marrow stromal osteoblasts (MSOs) alone was implanted as the control. The effectiveness of bone formation was assessed by histological and roentgenographic analysis.

RESULTSThe osteogenesis of MCCAB was better than CBM or MSOs and superior to the blank group.

CONCLUSIONMCCAB can effectively repair cranial defect. It could be used clinically to restore large bone defects.

Animals ; Bone Marrow Cells ; cytology ; physiology ; Bone Matrix ; cytology ; Cells, Cultured ; Feasibility Studies ; Male ; Osteoblasts ; cytology ; physiology ; Rabbits ; Skull ; abnormalities ; Stromal Cells ; cytology ; physiology

OBJECTIVETo explore the functions of phospholipase C (PLC)-independent protein kinase C signaling pathway (PTH/nonPLC/PKC) of parathyroid hormone (PTH) and its role in bone metabolism.

METHODSOsteoblasts isolated from the calvaria of 2- or 3-day-old C57BL mice, identified by alkaline phosphatase staining and Alizarin red staining, were treated for 4 h with 100 nmol/L [Gly(1), Arg(19)]hPTH(1-28) plus 10 nmol/L RP-cAMP, 10 nmol/L [Gly(1), Arg(19)]hPTH(1-34) plus 10 nmol/L RP-cAMP , 10 nmol/L PTH(1-34), or and 0.1% trifluoroacetic acid (TFA). The total RNA was then isolated for screening differentially expressed genes related to PTH/nonPLC/PKC pathway using Affymetrix mouse 12x135K gene expression profile microarray, and the identified genes were confirmed by real-time quantitative PCR. MC3T3-E1 cells treated with [Gly(1), Arg(19)]hPTH(1-28)+RP-cAMP, [Gly(1), Arg(19)]hPTH(1-34)+RP-cAMP, [Gly(1), Arg(19)]hPTH(1-34)+ RP-cAMP +100 nmol/L Go6983, or 0.1% TFA were also examined for GR(1-28)- or GR(1-34)-mediated gene expression changes using real-time quantitative PCR.

RESULTSAlizarin red staining visualized red mineralized nodules in the osteoblasts at 28 days of culture. According to the genechip results, we selected 56 target genes related to PTH/nonPLC/PKC pathway, among which CITED1 showed higher expressions in [Gly(1), Arg(19)]hPTH(1-34)+ RP-cAMP group than in both the control group and [Gly(1), Arg(19)]hPTH(1-28)+RP-cAMP group (P<0.05), and its expression was the highest in PTH(1-34) group (P<0.05). RT-PCR of MC3T3-E1 cells yielded consist results with those in the primary osteoblasts, and the cells treated with Go6983 (a PKC inhibitor) did not show GR(1-28)- or GR(1-34)-mediated differential expression of CITED1.

CONCLUSIONThe activation of PLC-independent protein kinase C signaling pathway of PTH enhances the expression of CITED1 in mouse osteoblasts to mediate the effect of PTH on bone metabolism, and this pathway is not dependent on the activation of PLC or PKA signaling.

Animals ; Cells, Cultured ; Indoles ; Maleimides ; Mice ; Mice, Inbred C57BL ; Nuclear Proteins ; physiology ; Osteoblasts ; physiology ; Parathyroid Hormone ; physiology ; Protein Kinase C ; physiology ; Signal Transduction ; Skull ; Trans-Activators ; physiology ; Type C Phospholipases

The degradable performance and bio-mineralization function of PLA-PEG-PLA/PLA tissue engineering scaffolds in vitro and in vivo were systematically studied. The X-ray diffraction and Fourier transform infrared spectra showed that there was the deposition of bone-like carbonate hydroxyapatite on the surface of scaffolds. We found that the weight of scaffolds did not always decrease with the prolongation of time in vitro. At the same time, we found that after the PLA-PEG-PLA/PLA tissue engineering scaffolds were embedded in skulls of rhesus monkeys, the new bone area reached 75% at the 12th week. Histological observation showed that the new bones were rebuilt and knitted bones were formed at the 12th week. These findings meant that the PLA-PEG-PLA/PLA tissue engineering scaffolds were potential in clinical use.
Animals ; Biocompatible Materials ; chemistry ; Bone Regeneration ; Bone Substitutes ; chemistry ; Implants, Experimental ; Macaca mulatta ; Polyethylene Glycols ; chemistry ; Polymers ; chemistry ; Skull ; drug effects ; physiology ; Tissue Engineering ; methods ; Tissue Scaffolds ; chemistry