A new mathematical model for evaluating surface changes in the mid-abdominal sagittal plane after two-level pedicle reduction osteotomy in patients with ankylosing spondylitis.

BACKGROUND: The purpose of this study was to create a mathematical model to precalculate the acreage change in the abdominal median sagittal plane (ac-AMSP) of patients with ankylosing spondylitis (AS) for whom two-level pedicle subtraction osteotomy (PSO) was planned. METHODS: A single-centre retrospective review of prospectively collected data was conducted among 11 adults with AS. Acreage of the abdominal median sagittal plane (a-AMSP) was performed. The distances and angles between the osteotomy apexes, anterosuperior edge of T12, xiphoid process, superior edge of the pubis, and anterosuperior corner of the sacrum were measured on preoperative thoracolumbar computed tomography. A mathematical model was created using basic trigonometric functions in accordance with the abdominal parameters. Planned osteotomized vertebra angles (POVAs) were substituted into the mathematical model, and the predictive ac-AMSP (P-AC) was obtained. A paired sample t test was performed to determine the differences between the P-AC and actual ac-AMSP (A-AC) and between the predictive acreage change rate (P-CR) and actual acreage change rate (A-CR). RESULTS: The mean age and GK were 44.4 ± 8.99 years and 102.9° ± 19.17°, respectively. No significant difference exists between A-CR and P-CR via mathematical modeling (p > 0.05). No statistically significant difference existed between POVA and actual osteotomized vertebra angles (AOVA) (p > 0.05). A statistically significant difference was observed between preoperative and postoperative measurements of LL, SVA, and GK variables (p < 0.001). CONCLUSIONS: The novel mathematical model was reliable in predicting the ac-AMSP in AS patients undergoing two-level PSO.

Operative strategies for ankylosing spondylitis-related thoracolumbar kyphosis: focus on the cervical stiffness, coronal imbalance and hip involvement.

BACKGROUND: Cervical stiffness, coronal imbalance and limited hip movement all play crucial roles in designing the corrective surgery for ankylosing spondylitis-related thoracolumbar kyphosis (AS-TLK). However, a comprehensive classification and tailored strategies for directing clinical work are lacking. This study aims to investigate the types and surgical strategies for AS-TLK that consider cervical stiffness, coronal imbalance and hip involvement as the key factors. METHODS: 25 consecutive AS-TLK patients were divided into three types according to their accompanying features: Type I: with a flexible cervical spine; Type IIA: with a stiff cervical spine; Type IIB: with coronal imbalance; Type IIC: with limited hip movement. Type III is the mixed type with at least two conditions of Type II. Individual strategies were given correspondingly. Spinal-pelvic-femoral parameters were measured, Scoliosis Research Society outcome instrument-22 (SRS-22) was used and complications were recorded and analysed. RESULTS: All patients (Type I 10, Type II 8 and Type III 7) underwent surgery successfully. 13 cases with 16 complications were recorded and cured. The patients were followed up for 24-65 months with an average of 33.0 ± 9.6 months. Both the sagittal and coronal parameters were corrected and decreased significantly (all, p < 0.05). SRS-22 scores showed a satisfactory outcome. CONCLUSION: Thoracolumbar kyphosis secondary to ankylosing spondylitis are complex and variable. Considering the factors of cervical stiffness, coronal imbalance and hip involvement assists in making decisions individually and achieving a desired surgical result.

An innovative adjustable prone positioning frame for treatment of severe kyphosis secondary to ankylosing spondylitis with two-level osteotomy.

PURPOSE: This study aims to introduce an innovative adjustable prone positioning frame (APPF) and explore its feasibility and safety for treatment of severe kyphosis secondary to ankylosing spondylitis (AS) with two-level osteotomy. METHODS: A retrospective, non-controlled study was conducted to illustrate the process where 13 patients diagnosed with severe kyphosis secondary to AS received operations on the APPF. Parameters of chin brow vertical angle (CBVA), global kyphosis (GK), thoracolumbar kyphosis (TLK), lumbar lordosis (LL) and sagittal vertical axis (SVA) were measured. Positioning time, operation time, intraoperative blood loss ahd complications were also determined. The Scoliosis Research Society outcomes instrument (SRS-22) was applied for clinical assessment. RESULTS: All patients were placed on the APPF successfully with the positioning time of 2.92 ± 0.76 min, received operation with 457.00 ± 88.04 min and had blood loss of 2330.77 ± 1423.25 ml. Four cases experienced pain due to tensional skin of the abdomen and one case suffered cerebrospinal fluid leakage postoperatively, but these patients were all cured conservatively. No neurological complications were observed, although sagittal translation occurred in four patients. Significant improvements were detected in CBVA, GK, TLK, LL and SVA postoperatively (P < 0.05), but no significant difference was observed between postoperation and the final follow-up (P > 0.05). The SRS-22 scores at 2 years after operation were significantly higher than those before operation (P < 0.05). CONCLUSION: The innovative APPF provided great convenience to place patients with severe kyphosis secondary to AS in a prone position. Performing two-level osteotomy with the aid of APPF is safe, feasible and effective.

Social support, health behavior self-efficacy, and anxiety on physical activity levels among lung cancer survivors: a structural equation modeling.

PURPOSE: The study aims to investigate the relationship among social support, health behavior self-efficacy, anxiety, and the physical activity (PA) levels of lung cancer survivors, and to analyze whether health behavior self-efficacy and anxiety mediate the relationship between social support and PA levels. METHODS: In a cross-sectional study of 1128 lung cancer survivors from 16 Chinese hospitals, we collected demographic data and administered the Social Support Rating Scale (SSRS), Self-Rated Abilities for Health Practices Scale (SRAHP), Anxiety Scale (AS), and International Physical Activity Questionnaire (IPAQ). SPSS 25.0 was used for descriptive analyses, while the structural equation model in SPSS AMOS 24.0 was used to identify the direct, indirect, and total effects among variables. RESULTS: There were significant correlations among SSRS, SRAHP, AS, and PA (P < 0.01). Model outcomes revealed a positive association between social support and health behavior self-efficacy (ß = 0.732, P < 0.001). Health behavior self-efficacy positively correlated with PA levels (ß = 0.228, P < 0.001) and negatively with anxiety (ß=-0.252, P = 0.001). Moreover, health behavior self-efficacy was found to partially mediate the relationship between social support and PA (ß = 0.174, P < 0.001). CONCLUSIONS AND IMPLICATIONS FOR CANCER SURVIVORS: This study revealed a positive correlation between social support and health behavior self-efficacy, and between health behavior self-efficacy and PA levels among lung cancer survivors. Additionally, health behavior self-efficacy mediated the relationship between social support and PA levels. In future clinical practice, medical and nursing staff should assess social support and health behavior self-efficacy in lung cancer survivors to inform personalized PA interventions.

Internucleosomal interactions mediated by histone tails allow distant communication in chromatin.

Action across long distances on chromatin is a hallmark of eukaryotic transcriptional regulation. Although chromatin structure per se can support long-range interactions, the mechanisms of efficient communication between widely spaced DNA modules in chromatin remain a mystery. The molecular simulations described herein suggest that transient binary internucleosomal interactions can mediate distant communication in chromatin. Electrostatic interactions between the N-terminal tails of the core histones and DNA enhance the computed probability of juxtaposition of sites that lie far apart along the DNA sequence. Experimental analysis of the rates of communication in chromatin constructs confirms that long-distance communication occurs efficiently and independently of distance on tail-containing, but not on tailless, chromatin. Taken together, our data suggest that internucleosomal interactions involving the histone tails are essential for highly efficient, long-range communication between regulatory elements and their targets in eukaryotic genomes.

[Application of back-forward Bending CT localization image in the prediction of proximal junctional kyphosis after spinal deformity surgery in adults].

Objective: To investigate the feasibility of predicting proximal junctional kyphosis (PJK) in adults after spinal deformity surgery based on back-forward Bending CT localization images and related predictive indicators. Methods: A retrospective analysis was performed for 31 adult patients with spinal deformity who underwent posterior osteotomy and long-segment fusion fixation between March 2017 and March 2020. There were 5 males and 26 females with an average age of 62.5 years (range, 30-77 years). The upper instrumented vertebrae (UIV) located at T 5 in 1 case, T 6 in 1 case, T 9 in 13 cases, T 10 in 12 cases, and T 11 in 4 cases. The lowest instrumented vertebrae (LIV) located at L 1 in 3 cases, L 2 in 3 cases, L 3 in 10 cases, L 4 in 7 cases, L 5 in 5 cases, and S 1 in 3 cases. Based on the full-length lateral X-ray film of the spine in the standing position before and after operation and back-forward Bending CT localization images before operation, the sagittal sequence of the spine was obtained, and the relevant indexes were measured, including thoracic kyphosis (TK), lumbar lordosis (LL), local kyphosis Cobb angle (LKCA) [the difference between the different positions before operation (recovery value) was calculated], kyphosis flexibility, hyperextension sagittal vertical axis (hSVA), T 2-L 5 hyperextension C 7-vertebral sagittal offset (hC 7-VSO), and pre- and post-operative proximal junctional angle (PJA). At last follow-up, the patients were divided into PJK and non-PJK groups based on PJA to determine whether they had PJK. The gender, age, body mass index (BMI), number of fusion segments, number of cases with coronal plane deformity, bone mineral density (T value), UIV position, LIV position, operation time, intraoperative blood loss, osteotomy grading, and related imaging indicators were compared between the two groups. The hC 7-VSO of the vertebral body with significant differences between groups was taken, and the receiver operating characteristic curve (ROC) was used to evaluate its accuracy in predicting the occurrence of PJK. Results: All 31 patients were followed up 13-52 months, with an average of 30.0 months. The patient's PJA was 1.4°-29.0° at last follow-up, with an average of 10.4°; PJK occurred in 8 cases (25.8%). There was no significant difference in gender, age, BMI, number of fusion segments, number of cases with coronal plane deformity, bone mineral density (T value), UIV position, LIV position, operation time, intraoperative blood loss, and osteotomy grading between the two groups ( P>0.05). Imaging measurements showed that the LL recovery value and T 8-L 3 vertebral hC 7-VSO in the PJK group were significantly higher than those in the non-PJK group ( P>0.05). There was no significant difference in hyperextension TK, hyperextension LL, hyperextension LKCA, TK recovery value, LL recovery value, kyphosis flexibility, hSVA, and T 2-T 7, L 4, L 5 vertebral hC 7-VSO ( P>0.05). T 8-L 3 vertebral hC 7-VSO was analyzed for ROC curve, and combined with the area under curve and the comprehensive evaluation of sensitivity and specificity, the best predictive index was hC 7-L 2, the cut-off value was 2.54 cm, the sensitivity was 100%, and the specificity was 60.9%. Conclusion: Preoperative back-forward Bending CT localization image can be used to predict the occurrence of PJK after posterior osteotomy and long-segment fusion fixation in adult spinal deformity. If the patient's T 8-L 2 vertebral hC 7-VSO is too large, it indicates a higher risk of postoperative PJK. The best predictive index is hC 7-L 2, and the cut-off value is 2.54 cm.

3DNALandscapes: a database for exploring the conformational features of DNA.

3DNALandscapes, located at: http://3DNAscapes.rutgers.edu, is a new database for exploring the conformational features of DNA. In contrast to most structural databases, which archive the Cartesian coordinates and/or derived parameters and images for individual structures, 3DNALandscapes enables searches of conformational information across multiple structures. The database contains a wide variety of structural parameters and molecular images, computed with the 3DNA software package and known to be useful for characterizing and understanding the sequence-dependent spatial arrangements of the DNA sugar-phosphate backbone, sugar-base side groups, base pairs, base-pair steps, groove structure, etc. The data comprise all DNA-containing structures--both free and bound to proteins, drugs and other ligands--currently available in the Protein Data Bank. The web interface allows the user to link, report, plot and analyze this information from numerous perspectives and thereby gain insight into DNA conformation, deformability and interactions in different sequence and structural contexts. The data accumulated from known, well-resolved DNA structures can serve as useful benchmarks for the analysis and simulation of new structures. The collective data can also help to understand how DNA deforms in response to proteins and other molecules and undergoes conformational rearrangements.

Web 3DNA--a web server for the analysis, reconstruction, and visualization of three-dimensional nucleic-acid structures.

The w3DNA (web 3DNA) server is a user-friendly web-based interface to the 3DNA suite of programs for the analysis, reconstruction, and visualization of three-dimensional (3D) nucleic-acid-containing structures, including their complexes with proteins and other ligands. The server allows the user to determine a wide variety of conformational parameters in a given structure--such as the identities and rigid-body parameters of interacting nucleic-acid bases and base-pair steps, the nucleotides comprising helical fragments, etc. It is also possible to build 3D models of arbitrary nucleotide sequences and helical types, customized single-stranded and double-helical structures with user-defined base-pair parameters and sequences, and models of DNA 'decorated' at user-defined sites with proteins and other molecules. The visualization component offers unique, publication-quality representations of nucleic-acid structures, such as 'block' images of bases and base pairs and stacking diagrams of interacting nucleotides. The w3DNA web server, located at http://w3dna.rutgers.edu, is free and open to all users with no login requirement.

How stiff is DNA?

The natural stiffness of DNA, which contributes to the interactions of the many proteins involved in its biological processing and packaging, also plays an important role in modern nanotechnology. Here we report new Monte-Carlo simulations of deformable DNA molecules of potential utility in understanding the behavior of the long, double-helical polymer in the tight confines of a cell and in the design of novel nanomaterials and molecular devices. We directly determine the fluctuations in end-to-end extension associated with the conventional elastic-rod representation of DNA and with more realistic models that take account of the precise deformability of the constituent base-pair steps. Notably, the variance of end-to-end distance shows a quadratic increase with chain length in short chains of both types. We also consider the contributions to chain extension from the chemical linkages used to attach small molecular probes to DNA. The distribution of computed distances is sensitive to the intrinsic structure and allowed deformations of the tether. Surprisingly, the enhancement in end-to-end variance associated with the presence of the probe depends upon chain length, even when the probe is rigidly connected to DNA. We find that the elastic rod model of DNA in combination with a slightly fluctuating tether accounts satisfactorily for the distributions of end-to-end distances extracted from the small-angle X-ray scattering of gold nanocrystals covalently linked to the ends of short DNAs. There is no need to introduce additional structural fluctuations to reproduce the measured uptake in end-to-end fluctuations with chain length.

[Application of self-designed adjustable operation frame in treatment of severe kyphosis secondary to ankylosing spondylitis with posterior osteotomy].

OBJECTIVE: To introduce a self-designed adjustable operation frame and explore the feasibility and safety in the treatment of severe kyphosis secondary to ankylosing spondylitis with posterior osteotomy. METHODS: Between March 2016 and May 2018, 7 cases of severe kyphosis secondary to ankylosing spondylitis were treated with posterior osteotomy using self-designed adjustable operation frame with prone position. There were 5 males and 2 females with an average age of 49.4 years (range, 40-55 years). The disease duration was 10-21 years (mean, 16.7 years). The apical vertebrae of kyphosis were located at T 11 in 2 cases, T 12 in 1 case, L 1 in 1 case, and L 2 in 3 cases. Among the 7 cases, 2 were classified as typeⅠ, 4 as type ⅡB, and 1 as type ⅢA according to 301 classification system. There was no neurological deficit of all cases; but 1 case suffered bilateral hip joints ankylosed in non-functional position. The parameters of chin-brow vertical angle (CBVA), global kyphosis (GK), thoracolumbar kyphosis (TLK), lumbar lordosis (LL), sagittal vertical axis (SVA) were measured; and the operation time, the intraoperative blood loss, and the complications were also collected and analyzed. RESULTS: All operations completed successfully. The operation time was 310-545 minutes (mean, 409.7 minutes) and the intraoperative blood loss was 1 500-2 500 mL (mean, 1 642.9 mL). There were 2 cases treated with one-level osteotomy of sagittal translation, 1 case of radiculopathy symptom of L 3, and 3 cases of tension of abdominal skin. All patients were followed up 20-35 months (mean, 27.9 months). There were significant differences in CBVA, GK, TLK, LL, and SVA between pre- and post-operation ( P<0.05); but no significant difference between 1 week after operation and last follow-up ( P>0.05). All the osteotomies and bone grafts fused well and no complications of loosening and breakage of internal fixator occurred during the follow-up. CONCLUSION: In the posterior osteotomy for correction of severe kyphosis secondary to ankylosing spondylitis, the self-designed adjustable operation frame is convenient for the patient to be placed in prone position. It is safe, feasible, and effective to perform osteotomy correction with the aid of the self-designed adjustable operation frame.

Structure, dynamics, and branch migration of a DNA Holliday junction: a single-molecule fluorescence and modeling study.

The Holliday junction (HJ) is a central intermediate of various genetic processes, including homologous and site-specific DNA recombination and DNA replication. Elucidating the structure and dynamics of HJs provides the basis for understanding the molecular mechanisms of these genetic processes. Our previous single-molecule fluorescence studies led to a model according to which branch migration is a stepwise process consisting of consecutive migration and folding steps. These data led us to the conclusion that one hop can be more than 1 basepair (bp); moreover, we hypothesized that continuous runs over the entire sequence homology (5 bp) can occur. Direct measurements of the dependence of the fluorescence resonance energy transfer (FRET) value on the donor-acceptor (D-A) distance are required to justify this model and are the major goal of this article. To accomplish this goal, we performed single-molecule FRET experiments with a set of six immobile HJ molecules with varying numbers of bps between fluorescent dyes placed on opposite arms. The designs were made in such a way that the distances between the donor and acceptor were equal to the distances between the dyes formed upon 1-bp migration hops of a HJ having 10-bp homology. Using these designs, we confirmed our previous hypothesis that the migration of the junction can be measured with bp accuracy. Moreover, the FRET values determined for each acceptor-donor separation corresponded very well to the values for the steps on the FRET time trajectories, suggesting that each step corresponds to the migration of the branch at a defined depth. We used the dependence of the FRET value on the D-A distance to measure directly the size for each step on the FRET time trajectories. These data showed that one hop is not necessarily 1 bp. The junction is able to migrate over several bps, detected as one hop and confirming our model. The D-A distances extracted from the FRET properties of the immobile junctions formed the basis for modeling the HJ structures. The composite data fit a partially opened, side-by-side model with adjacent double-helical arms slightly kinked at the four-way junction and the junction as a whole adopting a global X-shaped form that mimics the coaxially stacked-X structure implicated in previous solution studies.

Electric field control of magnetization direction across the antiferromagnetic to ferromagnetic transition.

Electric-field-induced magnetic switching can lead to a new paradigm of ultra-low power nonvolatile magnetoelectric random access memory (MeRAM). To date the realization of MeRAM relies primarily on ferromagnetic (FM) based heterostructures which exhibit low voltage-controlled magnetic anisotropy (VCMA) efficiency. On the other hand, manipulation of magnetism in antiferromagnetic (AFM) based nanojunctions by purely electric field means (rather than E-field induced strain) remains unexplored thus far. Ab initio electronic structure calculations reveal that the VCMA of ultrathin FeRh/MgO bilayers exhibits distinct linear or nonlinear behavior across the AFM to FM metamagnetic transition depending on the Fe- or Rh-interface termination. We predict that the AFM Fe-terminated phase undergoes an E-field magnetization switching with large VCMA efficiency and a spin reorientation across the metamagnetic transition. In sharp contrast, while the Rh-terminated interface exhibits large out-of-plane (in-plane) MA in the FM (AFM) phase, its magnetization is more rigid to external E-field. These findings demonstrate that manipulation of the AFM Néel-order magnetization direction via purely E-field means can pave the way toward ultra-low energy AFM-based MeRAM devices.

Insights into Gene Expression and Packaging from Computer Simulations.

Within the nucleus of each cell lies DNA - an unfathomably long, twisted, and intricately coiled molecule - segments of which make up the genes that provide the instructions that a cell needs to operate. As we near the 60(th) anniversary of the discovery of the DNA double helix, crucial questions remain about how the physical arrangement of the DNA in cells affects how genes work. For example, how a cell stores the genetic information inside the nucleus is complicated by the necessity of maintaining accessibility to DNA for genetic processing. In order to gain insight into the roles played by various proteins in reading and compacting the genome, we have developed new methodologies to simulate the dynamic, three-dimensional structures of long, fluctuating, protein-decorated strands of DNA. Our a priori approach to the problem allows us to determine the effects of individual proteins and their chemical modifications on overall DNA structure and function. Here we present our recent treatment of the communication between regulatory proteins attached to precisely constructed stretches of chromatin. Our simulations account for the enhancement in communication detected experimentally on chromatin compared to protein-free DNA of the same chain length as well as the critical roles played by the cationic 'tails' of the histone proteins in this signaling. The states of chromatin captured in the simulations offer new insights into the ways that the DNA, histones, and regulatory proteins contribute to long-range communication along the genome.