Biotransformation of the saponins in Panax notoginseng leaves mediated by gut microbiota from insomniac patients.

Saponins extracted from Panax notoginseng leaves by methanol or water could be orally administrated for insomnia with very low bioavailability, which might be bio-converted by gut microbiota to generate potential bioactive products. Moreover, gut microbiota profiles from insomniac patients are very different from healthy subjects. We aimed to compare the metabolic characteristics and profiles of the two saponins extract by incubation with gut microbiota from insomniac patients. The ginsenosides, notoginsenosides, and metabolites were identified and relatively quantified by high-performance liquid chromatography-tandem mass spectrometry. Gut microbiota was profiled by 16S ribosomal RNA gene sequencing. The results showed that saponins were very different between methanol or water extract groups, which were metabolized by gut microbiota to generate similar yields. The main metabolites included ginsenoside Rd, ginsenoside F2 , ginsenoside C-Mc or ginsenoside C-Y, ginsenoside C-Mx, ginsenoside compound K, and protopanaxadiol in both groups, while gypenoside XVII, notoginsenoside Fe, ginsenoside Rd2 , and notoginsenoside Fd were the intermediates in the methanol group. Moreover, the microbial, Faecalibacterium prausnitzi, could bio-convert the saponins to obtain the corresponding metabolites. Our study implied that saponins extracted from P. notoginseng leaves by methanol or water could be used for insomniac patients due to gut microbiota biotransformation.

Interactive three-dimensional teaching models of the female and male pelvic floor.

Controversies regarding structure and function of the pelvic floor persist because of its poor accessibility and complex anatomical architecture. Most data are based on dissection. This "surgical" approach requires profound prior knowledge, because applying the scalpel precludes a "second look." The "sectional" approach does not entail these limitations, but requires segmentation of structures and three-dimensional reconstruction. This approach has produced several "Visible Human Projects." We dealt with limited spatial resolution and difficult-to-segment structures by proceeding from clear-cut to more fuzzy boundaries and comparing segmentation between investigators. We observed that the bicipital levator ani muscle consisted of pubovisceral and puborectal portions; that the pubovisceral muscle formed, together with rectococcygeal and rectoperineal muscles, a rectal diaphragm; that the external anal sphincter consisted of its subcutaneous portion and the puborectal muscle only; that the striated urethral sphincter had three parts, of which the middle (urethral compressor) was best developed in females and the circular lower ("membranous") best in males; that the rectourethral muscle, an anterior extension of the rectal longitudinal smooth muscle, developed a fibrous node in its center (perineal body); that the perineal body was much better developed in females than males, so that the rectourethral subdivision into posterior rectoperineal and anterior deep perineal muscles was more obvious in females; that the superficial transverse perineal muscle attached to the fibrous septa of the ischioanal fat; and that the uterosacral ligaments and mesorectal fascia colocalized. To facilitate comprehension of the modified topography we provide interactive 3D-PDFs that are freely available for teaching purposes. Clin. Anat. 33:275-285, 2020. © 2019 Wiley Periodicals, Inc.

Architecture of structures in the urogenital triangle of young adult males; comparison with females.

The fibro-muscular architecture of the urogenital triangle remains contentious. Reasons are small size of the constituting structures and poor visibility with most imaging methods. We reinvestigated the area in serial sections of three males (21-38 years old) of the American and Chinese Visible Human Projects and two 26-week-old male fetuses, and compared the findings with earlier observations in females. The mass of the levator ani muscle was approximately twofold smaller and its funnel shape steeper in males than females. In the levator hiatus, a strand of the smooth longitudinal muscle layer of the rectum, the 'rectourethral (RU) muscle', extended anteriorly from the anorectal bend to the penile bulb. Fibrous tissue that formed in the inferior reach of the fetal RU muscle identified the location of the developing perineal body (PB) and divided the muscle into posterior 'rectoperineal' and anterior 'deep perineal' portions. In males, the PB remained small and bipartite, so that the RU muscle presented as an undivided midline structure. The well-developed female PB, instead, intertwined with the deep perineal muscle and both structures passed the vagina bilaterally to form the perineal membrane in the posterior portion of the urogenital triangle. The urethral rhabdosphincter extended in the anterior portion of the urogenital triangle between the penile bulb inferiorly and the bladder neck superiorly, and consisted of a well-developed circular 'membranous' portion with bilateral posteroinferior 'wings' and a thinner 'prostatic' portion on the prostate anterior side. In men, muscles occupy the urogenital triangle, but additional tightening of the locally fibrous adipose tissue by the superficial transverse perineal muscle appears necessary to generate functional support in women. An interactive 3D pdf file with these anatomical details (available online) should allow more accurate interpretation of ultrasound, computed tomography and magnetic resonance images.

Architectural differences in the anterior and middle compartments of the pelvic floor of young-adult and postmenopausal females.

The pelvic floor guards the passage of the pelvic organs to the exterior. The near-epidemic prevalence of incontinence in women continues to generate interest in the functional anatomy of the pelvic floor. However, due to its complex architecture and poor accessibility, the classical 'dissectional' approach has been unable to come up with a satisfactory description, so that many aspects of its anatomy continue to raise debate. For this reason, we opted for a 'sectional' approach, using the Chinese Visible Human project (four females, 21-35 years) and the Visible Human Project (USA; one female, 59 years) datasets to investigate age-related changes in the architecture of the anterior and middle compartments of the pelvic floor. The puborectal component of the levator ani muscle defined the levator hiatus boundary. The urethral sphincter complex consisted of a circular proximal portion (urethral sphincter proper), a sling that passed on the vaginal wall laterally to attach to the puborectal muscle (urethral compressor), and a circular portion that surrounded the distal urethra and vagina (urethrovaginal sphincter). The exclusive attachment of the urethral sphincter to soft tissues implies dependence on pelvic-floor integrity for optimal function. The vagina was circular at the introitus and gradually flattened between bladder and rectum. Well-developed fibrous tissue connected the inferior vaginal wall with urethra, rectum and pelvic floor. With eight-muscle insertions, the perineal body was a strong, irregular fibrous node that guarded the levator hiatus. Only loose areolar tissue comprising a remarkably well developed venous plexus connecting the middle and superior parts of the vagina with the lateral pelvic wall. The posterolateral boundary of the putative cardinal and sacrouterine ligaments coincided with the adventitia surrounding the mesorectum. The major difference between the young-adult and postmenopausal pelvic floor was the expansion of fat in between the components of the pelvic floor. We hypothesize that accumulation of pelvic fat compromises pelvic-floor cohesion, because the pre-pubertal pelvis contains very little fibrous and adipose tissue, and fat is an excellent lubricant.

Effects of polyol and surfactant plasticisers on lyophilised rice starch wafers for buccal drug delivery.

Rice starch is a promising biopolymer for buccal formulations but typical oven drying may promote starch retrogradation that affects mechanical properties. Hence, lyophilisation was proposed here to improve starch product's stability. This study aims to investigate the effects of plasticisers (sorbitol and Tween® 80, T80) on the characteristics and drug release profiles of lyophilised rice starch wafers incorporated with propranolol hydrochloride. The wafers were prepared by lyophilising starch mixture (5%w/v) with plasticiser (0.2 and 0.3 g/g) and drug (10, 20, 30%w/w). Control wafers exhibited loose layers with rough wrinkled surface. Sorbitol resulted in a dense structure with higher puncture strength (PS) but lower water absorption capacity (WAC) while T80 loosened the flakes that reduced PS and increased WAC. Drug inclusion decreased PS and increased WAC of unplasticised wafers. T80-plasticised wafers with drug had a lower PS and higher WAC than sorbitol-plasticised wafers. Particularly, T80-plasticised wafers achieved outstandingly high PS and the lowest WAC at 30%w/w drug. Drug dissolution of wafers relied mainly on the drug crystallinity and WAC at 10 and 30%w/w drug. Plasticisers reduced and increased drug dissolution at 10 and 20%w/w drug, respectively. This study highlights the potential of lyophilisation in preparing rice starch wafers for buccal delivery.

Rotational Load Fatigue Performance of an Implant System with an Internal Conical Connection and Microthreads.

PURPOSE: This in vitro study investigated the effect of implant geometry and diameter on the rotational load fatigue performance of an implant system with an internal conical connection with microthreads. MATERIALS AND METHODS: Regular (4.2 mm) and wide-diameter (4.8 mm) Astra Tech EV implants with straight (S) and conical (C) geometries were tested with their corresponding titanium abutments, comprising four test groups: 4.2-mm S (Group 1), 4.2-mm C (Group 2), 4.8-mm S (Group 3), and 4.8-mm C (Group 4). Five samples were included in each group. Customized brass implant holders and abutment holders were machined. A rotational load fatigue machine was used to apply a sinusoidally varying load to the implant-abutment interface at an angle of 45 degrees to produce an effective bending moment of 35 Ncm at a frequency of 14 Hz (air temperature: 20°C). The number of cycles to failure was recorded, with the upper limit set at 5 × 106 cycles. Results were analyzed using ANOVA. Failed samples were examined with a scanning electron microscope to evaluate the mode of failure. RESULTS: Of the 20 total samples, 2 failed, with Groups 1 and 2 each reporting one failure. Abutment and abutment screw fracture were observed in the failed sample in Group 1, while implant and abutment screw fracture occurred in the failed sample in Group 2. All wide-diameter implants ran beyond the cut-off without failure, but abutment screw loosening was noted in one sample in Group 3. No significant difference was found between implant groups of different geometries and diameters. Damage to the abutments and the implant internal surface were noted in all failed samples. CONCLUSIONS: While no significant differences were found between the test groups, failures were observed only in the regular-diameter group. The abutment and abutment screw fractured deep within the implant, and the implant fractured below the simulated bone level. These modes of failure may pose a significant clinical challenge during retrieval of these components.

Rotational Load Fatigue Performance of a One-Size Implant- Abutment Connection System.

PURPOSE: One-size implant-abutment (OSIA) connection systems have been developed for simplicity of clinical use and for a range of implant diameters. The aim of this in vitro study was to investigate the rotational load fatigue performance of different implant diameters and abutment platforms of an OSIA connection system. METHODOLOGY: Narrow, regular and wide diameter implants were tested with Regular Base (RB/WB) abutments of an OSIA system (Straumann. BLX). Wide diameter implants were also tested with Wide Base (WB) abutments. This resulted in 4 test groups (n=5): N-RB/WB (Narrow, 3.5mm, RB/WB abutment), R-RB/WB (Regular, 4.0mm, RB/WB abutment), W-RB/WB (Wide, 5.0mm, RB/WB abutment) and W-WB (Wide, 5.0mm, WB abutment). A rotational load fatigue machine applied a sinusoidally varying stress at an angle of 45o, producing an effective bending moment of 35Ncm at a frequency of 10 Hz in air at 20 oC. The number of cycles to failure was recorded. Results were evaluated using ANOVA. Failed specimens were examined with SEM to evaluate the failure mode. Pristine specimens were sectioned to examine the implant-abutment connection. RESULTS: All specimens in the 3 test groups with RB/WB abutments failed within the range of 558,750 cycles to 4,497,619 cycles, while the W-WB test group reached the upper limit of 5 million cycles without failure. Significant difference was found between abutment platforms (P < .001). There were no significant differences found for implant diameters (P =.857). However, with increasing implant diameter, implant fracture was less common and the location of failure was more coronal and consistently at the level of the implant platform for the abutment, and at the screw neck. CONCLUSIONS: For wide diameter implants, WB abutments exhibited a superior fatigue performance than RB/WB abutments, and would be preferred in situations of high mechanical risk. Increasing implant diameter, when used with RB/WB abutments, did not improve fatigue performance due to the one-size prosthetic connection, but failures were less catastrophic, and coronally located, which may be advantageous in managing failures.

Common and rare variants of EGF increase the genetic risk of Alzheimer's disease as revealed by targeted sequencing of growth factors in Han Chinese.

Alzheimer's disease (AD) is the most common neurodegenerative disease with high heritability. Growth factors (GFs) might contribute to the development of AD due to their broad effects on neuronal system. We herein aimed to investigate the role of rare and common variants of GFs in genetic susceptibility of AD. We screened 23 GFs in 6324 individuals using targeted sequencing. A rare-variant-based burden test and common-variant-based single-site association analyses were performed to identify AD-associated GF genes and variants. The burden test showed an enrichment of rare missense variants (p = 6.08 × 10-4) in GF gene-set in AD patients. Among the GFs, EGF showed the strongest signal of enrichment, especially for loss-of-function variants (p = 0.0019). A common variant rs4698800 of EGF showed significant associations with AD risk (p = 3.24 × 10-5, OR = 1.26). The risk allele of rs4698800 was associated with an increased EGF expression, whereas EGF was indeed upregulated in AD brain. These findings suggested EGF as a novel risk gene for AD.

Convergent transcriptomic and genomic evidence supporting a dysregulation of CXCL16 and CCL5 in Alzheimer's disease.

BACKGROUND: Neuroinflammatory factors, especially chemokines, have been widely reported to be involved in the pathogenesis of Alzheimer's disease (AD). It is unclear how chemokines are altered in AD, and whether dysregulation of chemokines is the cause, or the consequence, of the disease. METHODS: We initially screened the transcriptomic profiles of chemokines from publicly available datasets of brain tissues of AD patients and mouse models. Expression alteration of chemokines in the blood from AD patients was also measured to explore whether any chemokine might be used as a potential biomarker for AD. We further analyzed the association between the coding variants of chemokine genes and genetic susceptibility of AD by targeted sequencing of a Han Chinese case-control cohort. Mendelian randomization (MR) was performed to infer the causal association of chemokine dysregulation with AD development. RESULTS: Three chemokine genes (CCL5, CXCL1, and CXCL16) were consistently upregulated in brain tissues from AD patients and the mouse models and were positively correlated with Aß and tau pathology in AD mice. Peripheral blood mRNA expression of CXCL16 was upregulated in mild cognitive impairment (MCI) and AD patients, indicating the potential of CXCL16 as a biomarker for AD development. None of the coding variants within any chemokine gene conferred a genetic risk to AD. MR analysis confirmed a causal role of CCL5 dysregulation in AD mediated by trans-regulatory variants. CONCLUSIONS: In summary, we have provided transcriptomic and genomic evidence supporting an active role of dysregulated CXCL16 and CCL5 during AD development.

Risk factors for renal outcomes in children with antineutrophil cytoplasmic antibody-associated vasculitis: a nationwide retrospective study in China.

BACKGROUND: Pediatric antineutrophil cytoplasmic antibody-associated vasculitis (AAV) is a life-threatening systemic vasculitis featured by liability to renal involvement. However, there are few studies on the risk factors and predictive models for renal outcomes of AAV in children. METHODS: Data from 179 AAV children in multiple centers between January 2012 and March 2020 were collected retrospectively. The risk factors and predictive model of end-stage renal disease (ESRD) in AAV were explored. RESULTS: Renal involvement was the most typical manifestation (95.5%), and the crescent was the predominant pathological lesion (84.9%). The estimated glomerular filtration rate (eGFR) was evaluated in 114 patients, of whom 59.6% developed ESRD, and the median time to ESRD was 3.20 months. The eGFR [P = 0.006, odds ratio (OR) = 0.955, 95% confidence interval (CI) = 0.924-0.987] and the percentages of global glomerulosclerosis (pGGS; P = 0.018, OR = 1.060, 95% CI = 1.010-1.112) were independent risk factors for ESRD of renal biopsy. Based on the pGGS and eGFR at renal biopsy, we developed three risk grades of ESRD and one predictive model. The Kaplan‒Meier curve indicated that renal outcomes were significantly different in different risk grades (P < 0.001). Compared with serum creatinine at baseline, the predictive model had higher accuracy (0.86 versus 0.58, P < 0.001) and a lower coefficient of variation (0.07 versus 0.92) in external validation. CONCLUSIONS: Renal involvement is the most common manifestation of pediatric AAV in China, of which more than half deteriorates into ESRD. The predictive model based on eGFR at renal biopsy and the pGGS may be stable and accurate in speculating the risk of ESRD in AAV children. Supplementary file 2 (MP4 18937 KB).

Comparative study of thin sectional anatomical images from Chinese visible human data set and computed tomography images of superior mediastinum.

The structures of superior mediastinum and their spatial relationships are complex and difficult to master. This study aimed to compare visualization of the superior mediastinum based on computed tomography (CT) images and on the thin sections of the Chinese visible human (CVH) data set to provide a sectional anatomical basis for diagnostic imaging of superior mediastinal pathology. CVH sections of the mediastinum of a 35-year old male were compared with plain and enhanced CT images of a 45-year old male without apparent abnormalities in the upper chest. In addition, a three-dimensional model based on the CVH sections was compared with a model based on CT images. Although CT imaging is noninvasive and can be carried out in many individuals, its weakness is clearly the visualization of small soft tissue structures. In this respect, the sectional anatomical approach of the CVH images is complementary, as it visualizes these small soft tissue structures due to the higher resolution in the plain of sectioning and the color of the different structures in the section. Three-dimensional surface and volume rendering of reconstructions of the CVH data set can help medical students and less experienced thoracic surgeons to familiarize themselves with the topographic anatomy of the superior mediastinal structures and their spatial relationships, and thus with interpreting CT images of patients.

A novel technique for three-dimensional reconstruction for surgical simulation around the craniocervical junction region.

Performing surgeries on the craniocervical junction presents a technical challenge for operating surgeons. Three-dimensional (3D) reconstruction and surgical simulation have improved the efficacy and success rate of surgeries. The aim of this study was to create a 3D, digitized visible model of the craniocervical junction region to help realize accurate simulation of craniocervical surgery on a graphic workstation. Transverse sectional anatomy data for the study were chosen from the first Chinese visible human. Manual axial segmentation of the skull base, cervical spine, cerebellum, vertebral artery, internal carotid artery, sigmoid sinus, internal jugular vein, brain stem, and spinal cord were carried out by using Photoshop software. The segmented structures were reconstructed in 3 dimensions with surface and volume rendering to accurately display 3D models spatially. In contrast to conventional 3D reconstruction techniques that are based on computed tomography and magnetic resonance imaging Digital Imaging and Communications in Medicine (DICOM) inputs and provide mostly osseous details, this technique can help to illustrate the surrounding soft tissue structure and provide a realistic surgical simulation. The reconstructed 3D model was successfully used in simulating complex procedures in the virtual environment, including the transoral approach, bone drillings, and clivus resection.

Exploring the Genetic Association of the ABAT Gene with Alzheimer's Disease.

Accumulating evidence demonstrated that GABAergic dysfunction contributes to the pathogenesis of Alzheimer's disease (AD). The GABA aminotransferase (ABAT) gene encodes a mitochondrial GABA transaminase and plays key roles in the biogenesis and metabolism of gamma-aminobutyric acid (GABA), which is a major inhibitory neurotransmitter. In this study, we performed an integrative study at the genetic and expression levels to investigate the potential genetic association between the ABAT gene and AD. Through re-analyzing data from the currently largest meta-analysis of AD genome-wide association study (GWAS), we identified genetic variants in the 3'-UTR of ABAT as the top AD-associated SNPs (P < 1 × 10-4) in this gene. Functional annotation of these AD-associated SNPs indicated that these SNPs are located in the regulatory regions of transcription factors or/and microRNAs. Expression quantitative trait loci (eQTL) analysis and luciferase reporter assay showed that the AD risk alleles of these SNPs were associated with a reduced expression level of ABAT. Further analysis of mRNA expression data and single-cell transcriptome data of AD patients showed that ABAT reduction in the neuron is an early event during AD development. Overall, our results indicated that ABAT genetic variants may be associated with AD through affecting its mRNA expression. An abnormal level of ABAT will lead to a disturbance of the GABAergic signal pathway in AD brains.

Creation of the digital three-dimensional model of the prostate and its adjacent structures based on Chinese visible human.

We managed to provide three-dimensional digitized visible model of the prostate and its adjacent structures and to provide morphological data for imaging diagnosis and male urological surgery. With 3D-DOCTOR software, the contour line of prostate and its adjacent structures including rectum, bladder, male urethra, ureter, seminal vesicle, ductus deferens, ejaculatory ducts, obturator internus, levator ani, coccygeus, male pelvis, femur, prostatic nervous and venous plexus, internal and external iliac arteries were segmented from the Chinese visible human (CVH)-1 data set and the three-dimensional surfaces of intrapelvic visceras were successfully and accurately reconstructed via surface rendering, which can also be manipulated individually and interactively. Combined with AMIRA software, surface rendering reconstructed model of male urological organs and its adjacent structures via volume rendering reconstruction can be displayed together clearly and actually. It provides a learning tool of practicing virtual anatomy and virtual urological surgery for medical students and younger surgeons.

The study of three-dimensional reconstruction of Chinese adult liver.

PURPOSE: To build a three-dimensional (3D) visible model of human liver and provide visualization of precise anatomical structures for making plans for hepatic operations and obtain accurate simulation of liver on computer. METHODS: Based on the Chinese Visible Human data set, the hepatic structures were precisely segmented by Photoshop software. Then the segmented structures were reconstructed in surface rendering method and the hepatic parenchyma and the other parts of upper abdomen were reconstructed with volume rendering method by using our software on personal computer. RESULTS: A 3D model of human liver and its surrounding structures was built. The reconstructed structures can be displayed singly, in small groups or as a whole and can be continuously rotated in 3D space at different velocities. This model can help doctors to understand the spatial structure of the liver and its surrounding organs and also help surgeons to devise a reasonable surgical plan and reduce the risk of surgical malpractice. CONCLUSION: Combining volume-rendering reconstruction with surface rendering reconstruction can overcome some of the defects of both rendering reconstructions. The reconstructed liver and the main internal structures are realistic, which demonstrate the natural shape and exact position of the structures. They provide an accurate anatomical model for Chinese adult and also provide a basis for performing virtual hepatic operation.

[Development and clinical application of 3D operative planning system of live in virtual reality environments].

OBJECTIVE: To explore and develop three-dimension (3D) virtual reality (VR) liver model and convert computed tomography data into a fully 3D VR environment for display, measure and manipulation. METHODS: 3D-reconstruction of liver was restored from spiral computed tomography (CT) data by using LiVirtue software. Dextrobeam was used to view the 3D model in the VR environment. The liver and its anatomic structure were reconstructed to illuminate the location of the tumor and its related vessels. RESULTS: 3D models of liver, tumor and their relative vessels were reconstructed successfully. These models could be viewed and manipulated in the VR environment on personal computer.38 patients underwent liver resection, including 21 right hemihepatectomy, 14 left hemihepatectomy and 3 extended right hemihepatectomy. The intraoperative contrast with preoperative simulation confirmed the reliability of our 3D operative planning system. CONCLUSIONS: The preoperative simulation in 3D VR facilitated liver resection by the ability to view tumor and its relative vessels. This preoperative estimation from 3D model of liver benefits a lot to complicated liver resection.

Lower levels of whole blood serotonin in obsessive-compulsive disorder and in schizophrenia with obsessive-compulsive symptoms.

It has been reported that some schizophrenic patients suffer from obsessive-compulsive symptoms (OCS), and clozapine treatment is quite often associated with an occurrence/increase of OCS in schizophrenic patients. The aim of the study was to explore whether differences would exist in the clinical symptomatology and the whole blood serotonin (5-HT) concentrations in patients with obsessive-compulsive disorder (OCD), schizophrenic patients with and without OCS (S+OCS, S-OCS), and clozapine-treated schizophrenic patients with and without clozapine-induced OCS (CLZ+OCS, CLZ-OCS). We found that S+OCS patients (n=15) showed significantly lower scores on the Hamilton Anxiety Scale (HAMA), but similar levels of compulsions and obsessions using Yale-Brown Obsessive-Compulsive Scale (YBOCS) as compared to the patients (n=35) with OCD. S+OCS patients scored significantly lower on the Positive and Negative Syndrome Scale (PANSS) but higher on the Hamilton Depression Scale (HAMD) compared with S-OCS patients (n=19). However, CLZ+OCS patients (n=15) suffered from dominant compulsions but fewer obsessions compared with the OCD and S+OCS patients. OCD, S+OCS and CLZ+OCS groups had significantly lower levels of whole blood 5-HT than did the healthy volunteers (n=15), S-OCS and CLZ-OCS groups. It suggests that alterations in serotonin metabolism may be a common biological characteristic of OCS in OCD as well as in schizophrenia.

Biomechanics of anterior plating failure in treating distractive flexion injury in the caudal subaxial cervical spine.

BACKGROUND: Operative level is a potential biomechanical risk factor for construct failure during anterior fixation for distractive flexion injury. No biomechanical study of this concept has been reported, although it is important in clinical management. METHODS: To explore the mechanism of this concept, a previously validated three-dimensional C2-T1 finite element model was modified to simulate surgical procedure via the anterior approach for treating single-level distractive flexion injury, from C2-C3 to C7-T1. Four loading conditions were used including no-compression, follower load, axial load, and combined load. Construct stability at the operative level was assessed. FINDINGS: Under these loading conditions with the head's weight simulated, segmental stability decreases when the operative level shifts cephalocaudally, especially at C6-C7 and C7-T1, the stress of screw-bone interface increases cephalocaudally, and in the same operative level, the caudal screws always carries more load than the cephalad ones. All these predicted results are consistent with failure patterns observed in clinical reports. In the contrast, under other loading conditions without the weight of head, no obvious segmental divergence was predicted. INTERPRETATION: This study supports that the biomechanical mechanism of this phenomenon includes eccentric load from head weight during sagittal movements and difference of moment arms. Our study suggests that anterior fixation is not recommended for treating distractive flexion injury at the caudal segments of the subaxial cervical spine, especially at C6-C7 and C7-T1, because of the intrinsic instability in these segments. Combined posterior rigid fixation with anterior fixation should be considered for these segments.

Segmentation and three-dimension reconstruction of Chinese digitized human cerebrum.

OBJECTIVE: A 3D digitized visible model of human cerebrum was built to provide anatomical structure for making plans of cerebral surgical operation and realizing accurate simulation of cerebrum on computer. METHODS: Transverse sectional anatomy data of the cerebrum were chosen from the first Chinese visible human (one male and one female). Semi-automated segmentation and Photoshop software were selected to segment cerebral cortex, white matter, basal nuclei, lateral ventricle, hippocampus, etc. On personal computer, the segmented structures were reconstructed in 3D with volume rendering reconstruction and surface rendering reconstruction. RESULTS: Two accurately segmented images of the main structures of cerebrum were completed. The reconstructed structures can be displayed singly, in small groups or as a whole and can be continuously rotated in 3D space at different velocities. CONCLUSION: Combining volume-rendering reconstruction with surface rendering reconstruction overcomes the defects of surface rendering reconstruction that lack of internal anatomical information, which provides a new method for 3D reconstruction. The reconstructed cerebrum and the main internal structures are realistic, which demonstrates the natural shape and exact position of the structures. It provides an accurate model for the automated segmentation algorithmic study and provides a digitized anatomical mode of cerebrum.

Resection or degeneration of uncovertebral joints altered the segmental kinematics and load-sharing pattern of subaxial cervical spine: A biomechanical investigation using a C2-T1 finite element model.

The uncovertebral joint (UJ) is an important load-bearing structure in the subaxial cervical spine (SCS) and the medial wall of the intervertebral foramen (IVF). To investigate the UJ׳s role in load distribution and transmission under physiological loading, we developed and validated a detailed finite element model (C2-T1). Based on the initial model, two additional models were modified to simulate surgical resection and degeneration of UJs, to evaluate their influence on SCS kinematics and load distribution. The three models were subjected to 2Nm pure moment (flexion, extension, lateral bending, and axial rotation). Foraminal narrowing and potential nerve compression were evaluated. In the initial model, contact forces provided by the UJ were apparent in lateral bending and axial rotation. In axial rotation, the UJs and contralateral facet joints participated in joint activity, implying a possible restraint/counterbalance mechanism of these two joints. Peak vertebral stress was observed in the pedicle of vertebrae and was higher in the uncovertebral region than in the facet region. Resection of uncinate processes led to an apparent range of motion increase in lateral bending and axial rotation, while sagittal kinematics is influenced slightly. The load on other structures was slightly increased, but in axial rotation, resection of UJs changed the load distribution pattern. Degeneration of UJs significantly increased SCS stiffness and shielded other load-bearing structures. Peak IVF narrowing, but no nerve compression, was observed in axial rotation of the resection model. Thus, resection did not induce apparent secondary foraminal stenosis when other structures were still functional.