Pedicle screw path planning for multi-level vertebral fixation

BACKGROUND

For the spinal internal fixation procedures, connecting rods to the pedicle screws are commonly used in all spinal segments from the cervical to sacral spine. So far, we have only seen single vertebral screw trajectory planning methods in literatures. Joint screw placements in multi-level vertebrae with the constraint of an ipsilateral connecting rod are not considered.

PURPOSE

In this paper, a screw trajectory planning method that considers screw-rod joint system with both multi-level vertebral constraints and individual vertebral safety tolerance are proposed.

METHODS

The proposed method addresses three challenging constraints jointly for multi-level vertebral fixation with pedicle screws. First, a cylindrical screw safe passage model is suggested instead of a unique mathematical optimal trajectory for a single pedicle. Second, the flexible screw cap accessibility model is also included. Third, the connecting rod is modeled to accommodate the spine contour and support the needed gripping capacity. The retrospective clinical data of relative normal shape spines from Beijing Jishuitan hospital were used in the testing. The screw trajectories from the existing methods based on single vertebra and the proposed method based on multi-level vertebrae optimization are calculated and compared.

RESULTS

The results showed that the calculated screw placements by the proposed method can achieve 88% success rate without breaking the pedicle cortex and 100% in clinical class A quality (allow less than 2 mm out of the pedicle cortex) compared to 86.1% and 99.1%, respectively, with the existing methods. Expert evaluation showed that the screw path trajectories and the connecting rod calculated by the new method satisfied the clinical implantation requirements.

CONCLUSIONS

The new screw planning approach that seeks an overall optimization for multi-level vertebral fixation is feasible and more advantageous for clinical use than the single vertebral approaches.

A novel memory-like Tfh cell subset is precursor to effector Tfh cells in recall immune responses

T follicular helper (Tfh) cells, essential for germinal center reactions, are not identical, with different phenotypes reported. Whether, when, and how they generate memory cells is still poorly understood. Here, through single-cell RNA-sequencing analysis of CXCR5+Bcl6+ Tfh cells generated under different conditions, we discovered, in addition to PD-1hi effector Tfh cells, a CD62L+PD1low subpopulation. CD62L-expressing Tfh cells developed independently from PD-1+ cells and not in direct contact with B cells. More importantly, CD62L+ Tfh cells expressed memory- and stemness-associated genes, and with better superior long-term survival, they readily generated PD-1hi cells in the recall response. Finally, KLF2 and IL7R, also highly expressed by CD62L+ Tfh cells, were required to regulate their development. Our work thus demonstrates a novel Tfh memory-like cell subpopulation, which may benefit our understanding of immune responses and diseases.

Inter-Shell Sliding in Individual Few-Walled Carbon Nanotubes for Flexible Electronics

Few-walled carbon nanotube (FWCNT) is composed of a few coaxial shells of CNTs with different diameters. The shells in one tube can slide relatively to each other under external forces, potentially leading to regulated electrical properties, which are never explored due to experimental difficulties. In this work, the electromechanical response induced by inter-shell sliding of individual CNTs is studied and revealed the linear electrical current variation for the first time. Based on centimeter-long FWCNTs grown through chemical vapor deposition, controllable and reversible inter-shell sliding is realized while simultaneously recording the electrical current. Reversible and linear current variation with inter-shell sliding is observed, which is consistent with the proposed inter-shell tunneling model. Further, a silk fibroin-assisted transfer technique is developed for long CNTs and realized the fabrication of FWCNT-based flexible devices. Tensile stress can be applied on the FWCNTs@silk film encapsulated in elastic silicone to induce inter-shell sliding and thus controls electrical current, which is demonstrated to serve as a new human-machine interface with high reliability. Besides, it is foreseen that the electromechanical behaviors induced by inter-layer sliding in 1D nanotubes may also be extended to 2D layered materials, shedding new light on the fabrication of novel electronics.

Detection of antigen Ag85B expression is useful for the diagnosis of tuberculosis, especially for those with an antituberculosis treatment history

OBJECTIVES

The present study used immunohistochemistry (IHC) to detect antigen Ag85B in tissue sections and aimed to evaluate its validity in histopathologic diagnosis of tuberculosis (TB).

METHODS

In total, 204 patients with confirmed TB and 40 other diseases were included in the present study. Ziehl-Neelsen (Z-N) stains, IHC (anti-Ag85B), and quantitative fluorescence polymerase chain reaction were used to detect acid-fast bacilli, Mycobacterium tuberculosis (MTB) antigen, and MTB DNA.

RESULTS

Immunohistochemistry was significantly more sensitive than Z-N stains (93.1% vs 67.2%; P < .001). The sensitivity of Z-N stains significantly correlated with anti-TB treatment history. The sensitivity of Z-N stains was lower in rifampicin (RIF)-resistant TB compared with RIF-sensitive TB (52.8% vs 69.0%; P = .091) and those without treatment history (52.8% vs 84.0%; P = .015). However, IHC was not significantly affected by treatment history (P = .410). Moreover, expression patterns of Ag85B were dependent on treatment history and commonly showed weak scattered spots in RIF-susceptible TB. Conversely, strong brown rods were often found in those with RIF-resistant TB.

CONCLUSIONS

Immunohistochemistry is a simple, sensitive technique for the diagnosis of TB, especially for those patients with treatment history. The expression pattern of Ag85B is a potential marker for evaluating anti-TB treatment response.

Disturbed Resting-State Whole-Brain Functional Connectivity of Striatal Subregions in Bulimia Nervosa

BACKGROUND

Disturbed self-regulation, taste reward, as well as somatosensory and visuospatial processes were thought to drive binge eating and purging behaviors that characterize bulimia nervosa. Although studies have implicated a central role of the striatum in these dysfunctions, there have been no direct investigations on striatal functional connectivity in bulimia nervosa from a network perspective.

METHODS

We calculated the functional connectivity of striatal subregions based on the resting-state functional Magnetic Resonance Imaging data of 51 bulimia nervosa patients and 53 healthy women.

RESULTS

Compared with the healthy women, bulimia nervosa patients showed increased positive functional connectivity in bilateral striatal nuclei and thalamus for nearly all of the striatal subregions, and increased negative functional connectivity in bilateral primary sensorimotor cortex and occipital areas for both ventral striatum and putamen subregions. Only for the putamen subregions, we observed reduced negative functional connectivity in the prefrontal (bilateral superior and middle frontal gyri) and parietal (right inferior parietal lobe and precuneus) areas. Several striatal connectivities with occipital and primary sensorimotor cortex significantly correlated with the severity of bulimia.

CONCLUSIONS

The findings indicate bulimia nervosa-related alterations in striatal functional connectivity with the dorsolateral prefrontal cortex supporting self-regulation, the subcortical striatum and thalamus involved in taste reward, as well as the visual occipital and sensorimotor regions mediating body image, which contribute to our understanding of neural circuitry of bulimia nervosa and encourage future therapeutic developments for bulimia nervosa by modulating striatal pathway.

Validation of glomerular filtration rate-estimating equations in Chinese children

Background

Glomerular filtration rate (GFR) is essential for renal function evaluation and classification of chronic kidney disease (CKD), while the reference method in children are cumbersome. In the Chinese children, there was no data about GFR measured through plasma or renal clearance of the exogenous markers, and therefore no validated GFR-estimating tools in this population.

Methods

We measured GFR with double-sample plasma clearance of ^99mTc-DTPA (mGFR) in 87 hospitalized children with renal injury. Using mGFR as the golden standard, we evaluate the efficiency of four different GFR estimation equations (the original and update Schwartz equation, the Filler equation, the CKiD equation) by statistical parameters of correlation, precision and accuracy.

Results

In our population, mGFR was 97.0± 31.9 mL/min/1.73m². The updated Schwartz equation, the Filler equation and the CKiD equation, produced eGFR with strong correlation with mGFR, strong explanation capacity of variance in mGFR, small bias, satisfactory performance in Bland-Altman analysis, high intra-class correlation coefficients, high ratio of eGFR within mGFR±10% and eGFR within mGFR±30%, good agreement in CKD staging between eGFR and mGFR. The original Schwartz equation produced eGFR with large bias, poor precision and accuracy.

Conclusion

The validated equations to estimate GFR in our patients are the updated Schwartz equation, which is simple for bedside use, the Filler equation and the CKiD equation, which provide more accurate eGFR. The original Schwartz equation should not be applied to estimate GFR in Chinese children with kidney injuries.