Dorsal root entry zone fenestration for intramedullary ependymal cyst: illustrative case.

BACKGROUND: Intramedullary ependymal cysts are rare and difficult to distinguish from syringomyelia and neuroenteric cysts. Almost all cases in the literature have been case reports and have been performed with the traditional posterior median sulcus incision, which is difficult to identify accurately during spinal rotation. Approximately 40% of cases have transient neurological deterioration. The dorsal root entry zone has been proven to be an effective incision area in the treatment of intramedullary lesions, but so far, its utilization in intramedullary ependymal cysts has been rarely reported. OBSERVATIONS: This study is the first to report on six cases of intramedullary ependymal cysts treated with an 8-mm incision in the dorsal root entry zone to fully establish the communication between the cyst and the subarachnoid space. Imaging changes and neurological improvement were analyzed in all cases before and after surgery and were followed up for 49.7 months. LESSONS: The utilization of dorsal root entry zone fenestration in intramedullary ependymal cyst has demonstrated feasibility and effectiveness, ensuring the functional integrity of the posterior column.

Study on Corrosion Resistance of Stainless-Steel Welded Joints with SnSb8Cu4 and SnZn9.

The use of soldering based on metallurgical bonding, as opposed to conventional rubber sealing, is capable of achieving the firm sealing of stainless-steel subway car bodies, though the corrosion resistance of such joints has rarely been investigated. In this study, two typical solders were selected and applied to the soldering of stainless steel, and their properties were investigated. As indicated by the experimental results, the two types of solder exhibited favorable wetting and spreading properties on stainless-steel plates, and successfully achieved sealing connections between the stainless-steel sheets. In comparison with the Sn-Zn9 solder, the Sn-Sb8-Cu4 solder exhibited lower solidus-liquidus, such that it can be more suitably applied to low-temperature sealing brazing. The sealing strength of the two solders reached over 35 MPa, notably higher than that of the sealant currently used (the sealing strength is lower than 10 MPa). In comparison with the Sn-Sb8-Cu4 solder, the Sn-Zn9 solder exhibited a higher corrosion tendency and a higher degree of corrosion during the corrosion process.

C1-2 Fusion in Atlantoaxial Dislocation and Basilar Invagination with and without Chiari Malformation: Clinical/Radiological and Craniometric Results.

OBJECTIVE: Patients with Chiari malformation (CM) associated with atlantoaxial dislocation (AAD) and basilar invagination (BI) may present with a small posterior cranial fossa, but data on the volumetric analysis are lacking. Additionally, whether additional foramen magnum decompression (FMD) is needed together with atlantoaxial fusion remains controversial. This study evaluated the volumetric alterations of the posterior cranial fossa in these patients and analyzed the radiological and clinical outcomes after posterior C1-C2 reduction and fixation plus C1 posterior arch resection. METHODS: Thirty-two adult CM patients with AAD and BI (CM-AAD/BI group) and 21 AAD and BI patients without CM (AAD/BI-only group) who received posterior atlantoaxial fusion plus C1 posterior arch resection were retrospectively studied. The clinical and radiological outcomes and volumetric measurements of the posterior cranial fossa were evaluated. RESULTS: The majority of CM-AAD/BI patients (94%) improved clinically and radiologically at 12 mo postoperatively, and none required additional FMD. Morphological analysis revealed a significant reduction in the bony posterior cranial fossa volumes of the CM-AAD/BI group (P < 0.01) and the AAD/BI-only group (P < 0.01) relative to those of the CM group. No significant differences were observed between the CM-AAD/BI and AAD/BI groups. CONCLUSIONS: Compared with patients with simple CM, patients with AAD/BI with or without CM demonstrated a considerably and equally reduced bony posterior cranial fossa volume. No additional FMD is needed in the treatment of CM-AAD/BI patients after posterior reduction and fusion plus C1 posterior arch resection.

Potential association among posterior fossa bony volume and crowdedness, tonsillar hernia, syringomyelia, and CSF dynamics at the craniocervical junction in Chiari malformation type I.

Objective: The characteristic morphological parameters (bony posterior fossa volume (bony-PFV), posterior fossa crowdness, cerebellar tonsillar hernia, and syringomyelia) and CSF dynamics parameters at the craniocervical junction (CVJ) in Chiari malformation type I (CMI) were measured. The potential association between these characteristic morphologies and CSF dynamics at CVJ was analyzed. Methods: A total of 46 cases of control subjects and 48 patients with CMI underwent computed tomography and phase-contrast magnetic resonance imaging. Seven morphovolumetric measures and four CSF dynamics at CVJ measures were performed. The CMI cohort was further divided into "syringomyelia" and "non-syringomyelia" subgroups. All the measured parameters were analyzed by the Pearson correlation. Results: Compared with the control, the posterior cranial fossa (PCF) area, bony-PFV, and CSF net flow were significantly smaller (P < 0.001) in the CMI group. Otherwise, the PCF crowdedness index (PCF CI, P < 0.001) and the peak velocity of CSF (P < 0.05) were significantly larger in the CMI cohort. The mean velocity (MV) was faster in patients with CMI with syringomyelia (P < 0.05). In the correlation analysis, the degree of cerebellar tonsillar hernia was correlated with PCF CI (R = 0.319, P < 0.05), MV (R = -0.303, P < 0.05), and the net flow of CSF (R = -0.300, P < 0.05). The Vaquero index was well correlated with the bony-PFV (R= -0.384, P < 0.05), MV (R = 0.326, P < 0.05), and the net flow of CSF (R = 0.505, P < 0.05). Conclusion: The bony-PFV in patients with CMI was smaller, and the MV was faster in CMI with syringomyelia. Cerebellar subtonsillar hernia and syringomyelia are independent indicators for evaluating CMI. Subcerebellar tonsillar hernia was associated with PCF crowdedness, MV, and the net flow of CSF at CVJ, while syringomyelia was associated with bony-PFV, MV, and the net flow of CSF at the CVJ. Thus, the bony-PFV, PCF crowdedness, and the degree of CSF patency should also be one of the indicators of CMI evaluation.

Does H3K27M Mutation Impact Survival Outcome of High-Grade Spinal Cord Astrocytoma?

OBJECTIVE: To evaluate the impact of H3K27M mutation in the prognosis of histological high-grade intramedullary astrocytoma. METHODS: A total of 78 patients who were diagnosed with high-grade spinal cord astrocytoma were included. Clinical data consisting demographic, radiological, molecular features and treatment data were recorded. Univariate and multivariate Cox analysis were performed to investigate variables associated with survival outcome of histological high-grade spinal cord astrocytoma. RESULTS: Median survival time was 21 months. Overall survival (OS) at 1 and 3 years was 65.7% and 40.7%, respectively. Sex, location, and tumor span did not present significant association with OS. Patients with H3K27M mutation showed significant shorter duration of symptom than patients with H3K27 wild-type. As respect to adjuvant treatment, adjuvant radiotherapy and chemotherapy were associated with favorable OS (both p = 0.01). Younger patients (age ≤ 18 years) had shorter OS (p = 0.008) than adult patients (age > 18 years). Of note, H3K27M mutation did not show significant impact on the survival outcome, regardless of histology grade 3 or grade 4 (p = 0.3). CONCLUSION: Histological high-grade spinal cord astrocytoma has dismal prognosis. Our study demonstrated that H3K27M mutation did not show significant impact on survival outcome of histological high-grade spinal cord astrocytoma.

Post-esophagectomy chylothorax refractory to mass ligation of thoracic duct above diaphragm: a case report.

BACKGROUND: Post-esophagectomy chylothorax is a relatively rare but potentially lethal complication. The treatment strategy of post-esophagectomy chylothorax remains a subject of debate which mainly focuses on the indication and timing of surgical intervention. For cases in which the leakage site is not localized, a mass ligation of the thoracic duct above diaphragm is advocated as the surgical procedure is believed to ensure sealing all the accessory ducts that could be the source of the chylothorax. But in this paper, we report a case of post-esophagectomy chylothorax which was refractory to mass ligation of thoracic duct above diaphragm. CASE PRESENTATION: A 59-year old man suffered from high output chylothorax (> 1000 ml/24 h for more than 30 days) after esophagectomy through left thoracotomy. Considering the failure of lymphangiography, we performed mass ligation of thoracic duct above diaphragm. However, we failed to close the chylous leakage. Finally, we found that a rare variated tributary of thoracic duct was the resource of the chylous output. Both the variation of lymphatic system and the coincidence of injured site lead to the invalidness of reoperation. After definitely ligating the variated tributary, chylothorax was cured. CONCLUSION: This case supplies a direct evidence that mass ligation of thoracic duct is of no avail in some refractory chylothorax, which indicates the importance of chylous leakage localization.

Morphometric and volumetric analysis of the posterior cranial fossa in adult Chiari malformation type I with and without group B basilar invagination.

BACKGROUND: The frequent association of basilar invagination (BI) makes the understanding of the pathogenesis of Chiari malformation type I (CMI) difficult. The influence of group B type of BI (the BI without obvious atlantoaxial instability) on the skeletal morphology has not been thoroughly studied. The objective of this study is to evaluate the skeletal alterations in the posterior cranial fossa (PCF) of adult CMI cases with and without group B BI. METHODS: Fifty-four adult CMI without BI cases (CMI-only group) and 30 adult CMI with group B BI cases (CMI-BI group) were retrospectively studied. Fifty-six adult patients with unruptured intracranial aneurysms were included as the controls. Several linear and angular variables, and the bony volume of the PCF were analyzed based on thin-slice computed tomography data. RESULTS: Morphological analysis revealed a significant difference in several variables from controls compared to CMI-only, and CMI-BI patients. The clivus and occipital bone, shortened and elevated in CMI-only patients, were further flattened in BI-associated CMI patients. Furthermore, although out of the scope for the diagnostic threshold of BI, the CMI-only cases also had a tendency to form BI. The association of BI modified several variables, without further reducing the bony PCF volume. CONCLUSIONS: These findings indicate that the variables associated with group B BI tend to be a continuum of the same pathological abnormalities that originate from the same pathological alterations in CMI patients.

Thermal stability and diffusion characteristics of ultrathin amorphous carbon films grown on crystalline and nitrogenated silicon substrates by filtered cathodic vacuum arc deposition.

Amorphous carbon (a-C) films are widely used as protective overcoats in many technology sectors, principally due to their excellent thermophysical properties and chemical inertness. The growth and thermal stability of sub-5-nm-thick a-C films synthesized by filtered cathodic vacuum arc on pure (crystalline) and nitrogenated (amorphous) silicon substrate surfaces were investigated in this study. Samples of a-C/Si and a-C/SiNx/Si stacks were thermally annealed for various durations and subsequently characterized by high-resolution transmission electron microscopy (TEM) and electron energy loss spectroscopy (EELS). The TEM images confirmed the continuity and uniformity of the a-C films and the 5-nm-thick SiNx underlayer formed by silicon nitrogenation using radio-frequency sputtering. The EELS analysis of cross-sectional samples revealed the thermal stability of the a-C films and the efficacy of the SiNx underlayer to prevent carbon migration into the silicon substrate, even after prolonged heating. The obtained results provide insight into the important attributes of an underlayer in heated multilayered media for preventing elemental intermixing with the substrate, while preserving the structural stability of the a-C film at the stack surface. An important contribution of this investigation is the establishment of an experimental framework for accurately assessing the thermal stability and elemental diffusion in layered microstructures exposed to elevated temperatures.

A molecular dynamics study of the oxidation mechanism, nanostructure evolution, and friction characteristics of ultrathin amorphous carbon films in vacuum and oxygen atmosphere.

Amorphous carbon (a-C) films are characterized by extraordinary chemical inertness and unique thermophysical properties that are critical to applications requiring oxidation-resistant, low-friction, and durable overcoats. However, the increasing demands for ultrathin (a few nanometers thick) a-C films in various emerging technologies, such as computer storage devices, microelectronics, microdynamic systems, and photonics, make experimental evaluation of the structural stability and tribomechanical properties at the atomic level cumbersome and expensive. Consequently, the central objective of this study was to develop comprehensive MD models that can provide insight into the oxidation behavior and friction characteristics of ultrathin a-C films exhibiting layered through-thickness structure. MD simulations were performed for a-C films characterized by relatively low and high sp3 contents subjected to energetic oxygen atom bombardment or undergoing normal and sliding contact against each other in vacuum and oxygen atmosphere. The effect of energetic oxygen atoms on the oxidation behavior of a-C films, the dependence of contact deformation and surface attractive forces (adhesion) on surface interference, and the evolution of friction and structural changes (rehybridization) in the former a-C films during sliding are interpreted in the context of simulations performed in vacuum and oxidizing environments. The present study provides insight into the oxidation mechanism and friction behavior of ultrathin a-C films and introduces a computational framework for performing oxidation/tribo-oxidation MD simulations that can guide experimental investigations.

Chiari Malformations Type I without Basilar Invagination in Adults: Morphometric and Volumetric Analysis.

BACKGROUND: Chiari malformation type I (CMI) cases are frequently associated with basilar invagination (BI), which complicates the understanding of the pathology of CMI. We specifically evaluated the morphometric and volumetric alterations in the bony structures of CMI patients without BI. METHODS: Fifty adult CMI patients without BI treated at our institution from January 2015 to December 2019 were retrospectively studied. The morphometric and volumetric characteristics of the posterior cranial fossa (PCF) were analyzed using thin-slice computed tomography images. RESULTS: Compared with the controls, the clivus length (P < 0.001), supraoccipital length (P < 0.001), Klaus height index (P < 0.001), axial length (P < 0.001), clivo-axial angle (P < 0.001), tentorial angle (P < 0.05), and bony PCF volume (P < 0.001) of the CMI-only group were significantly smaller, and the distance between the Chamberlain line and the dens axis (P < 0.001), clivus angle (P < 0.001), and basal angle (P < 0.001) of the CMI-only group were significantly larger, while the distance between the McRae line and the dens axis, McRae line, anteroposterior diameter of the PCF, occipital angle, occipital canal angle, and tentorial Twining line angle showed no significant difference between the 2 groups. CONCLUSIONS: Hypoplasia of the clivus and occipital bone were confirmed in CMI patients without BI, thus providing further evidence for the notion that CMI is secondary to the underdevelopment of the PCF.

Structure evolution during deposition and thermal annealing of amorphous carbon ultrathin films investigated by molecular dynamics simulations.

The evolution of the structure of amorphous carbon (a-C) films during deposition and thermal annealing is of significant interest from both the materials science and application perspectives. However, despite the voluminous literature of studies dealing with the deposition and physical properties of a-C films, basic understanding of the structure evolution due to phase change during film growth and heating is fairly sparse and empirical, presumably due to the lack of high-resolution instruments that can probe structural changes at the atomic and molecular levels in real time. Molecular dynamics (MD) is a powerful computational method for studying atomic/molecular-scale movement and interactions. Thus, the objective of this study was to perform MD simulations that provide insight into changes in the structure of ultrathin a-C films during deposition and annealing. Simulation results reveal a multi-layer film structure, even for a-C films as thin as ~20 Å, the existence of a deposition energy that yields a-C films with the highest sp3 content, the transient and steady-state stages of the structure evolution during annealing at different temperatures, and the changes in the hybridization state (mainly in the bulk layer) encountered during annealing at elevated temperatures. The MD results of this study are of particular importance to applications where the deposition conditions and operation temperature affect the structure and, in turn, the physical properties of ultrathin a-C films used as protective overcoats.

ASK1 phosphorylation regulates astrocytic reactive gliosis in vitro and in vivo.

Apoptosis signal-regulating kinase 1 (ASK1) may play a pivotal role in reactive gliosis. To assess the role of ASK1 in trauma-induced reactive gliosis, we examined the phosphorylation of ASK1 and the expression of glial fibrillary acidic protein (GFAP) and vimentin after scratch injury in cultured astrocytes and spinal cord injury (SCI) in rats. Enhanced phosphorylation of ASK1 was detected during reactive gliosis both in vitro and in vivo, and P38 MAPK relayed the signal from phosphorylated ASK1 to the activation of astrocytes. Immunoprecipitation analyses suggested that 14-3-3 was dissociated from ASK1 during astrocyte activation. Finally, treatment with thioredoxin reduced ASK1 phosphorylation and reactive gliosis and promoted hindlimb locomotion recovery in SCI rats. These results indicated that ASK1 may play an important role in mechanical-injury-induced reactive gliosis.

Solution Synthesis of Co-Ni-W-Based ODS Alloy Powder.

Low-temperature combustion synthesis was utilized to prepare Co-Ni-W-based oxide dispersion strengthened (ODS) alloy powder. The influence of the U/Co and C/Co ratios on the morphology and specific surface area of the combusted powder was investigated. Particle size, phase constituents, and element distribution of the resulting Co-Ni-W-based ODS alloy powder were characterized. The results indicate that insufficient urea induced no autocombustion reaction, while excess urea and glucose inhibited the combustion reaction. The optimized contents of urea and glucose were around U/Co = 1.2 and C/Co = 1.5, and the specific surface area of the powder reached 43.5 m²/g. The lamellar Co-Ni-W-based ODS alloy powder with particle sizes of 1-21 µm was the soft agglomeration of a high population of nanosized (65 nm) particles. These nanoparticles grew from 65 to 260 nm in the reduction temperature range of 700-900 °C. Homogeneous distribution of Co, Ni, W, and Y in the Co-Ni-W-based ODS alloy powder was achieved.

Synthesis and structure-activity relationship of teixobactin analogues via convergent Ser ligation.

Convergent Ser/Thr ligation has been used to prepare a series of teixobactin analogues (28 in total) to establish a structure-activity relationship of teixobactin. anti-bacterial evaluations of these synthetic analogues have revealed the critical amino acid residues and the sites tolerable of modifications. These studies will shed lights on the further development of teixobactin analogues with improved antibacterial activities.

Resistin-Like Molecule-ß Promotes Invasion and Migration of Gastric Carcinoma Cells.

BACKGROUND: Resistin-like molecule-ß (RELMß) is a novel secretory protein from intestinal goblet cells and participates in epithelial differentiation, tumor occurrence, and immune response. RELMß is absent in normal gastric mucosa but is abundantly expressed in gastric carcinoma tissues, and is correlated with tumor invasion and metastasis. Epithelial-mesenchymal transition (EMT) is an important mechanism governing tumor cell invasion. This study thus investigated the modulation of RELMß in gastric cancer metastasis and its correlation with EMT. MATERIAL/METHODS: We used RELMß-low expression AGS cell line of gastric cancer and normal mucosa cell line GES1 as in vitro models, on which RELMß0-expressing vector was transfected. The invasion and migration of cells were quantified by Transwell assay. EMT-related protein including E-cadherin, N-cadherin, Snail, and Vimentin were detected by Western blotting in transfected AGS cells. RESULTS: RELMß transfection significantly potentiated invasion and migration abilities of AGS cells, whose RELMß protein level was significantly elevated compared to those in untransfected AGS or GES1 cells. After RELMb transfection, EMT-related proteins, including N-cadherin, Snail, and Vimentin levels, were elevated, but E-cadherin expression was depressed. CONCLUSIONS: RELMß-overexpression can facilitate invasion and migration of gastric carcinoma cells and it increases the expression of EMT-related proteins, such as N-cadherin, Snail, Vimentin, but decreases E-cadherin level, thus promoting the progression of EMT.

Relation of Serum and Vitreous Concentrations of Fetuin-A with Diabetic Retinopathy.

BACKGROUND: Fetuin-A, a liver-derived glycoprotein, is correlated with diabetes. The aim of the present investigation was to evaluate serum and vitreous concentrations of fetuin-A in patients with diabetic retinopathy (DR). MATERIAL AND METHODS: We randomly selected 224 diabetic patients and 68 control subjects for this study. RESULTS :There were markedly higher serum and vitreous fetuin-A concentrations in proliferative diabetic retinopathy (PDR) patients than in the other three groups. NPDR patients exhibited elevated vitreous fetuin-A concentrations compared with patients without DR. However, no significant differences in serum fetuin-A concentrations were observed between NPDR patients and patients without DR. In addition, there were significantly lower concentrations of serum and vitreous fetuin-A in control subjects compared with the other three groups. CONCLUSIONS: The occurrence and severity of DR is correlated with serum and vitreous fetuin-A concentrations.