Finite element modeling and analysis of effect of preexisting cervical degenerative disease on the spinal cord during flexion and extension.

Recent studies have emphasized the importance of dynamic activity in the development of myelopathy. However, current knowledge of how degenerative factors affect the spinal cord during motion is still limited. This study aimed to investigate the effect of various types of preexisting herniated cervical disc and the ligamentum flavum ossification on the spinal cord during cervical flexion and extension. A detailed dynamic fluid-structure interaction finite element model of the cervical spine with the spinal cord was developed and validated. The changes of von Mises stress and maximum principal strain within the spinal cord in the period of normal, hyperflexion, and hyperextension were investigated, considering various types and grades of disc herniation and ossification of the ligamentum flavum. The flexion and extension of the cervical spine with spinal canal encroachment induced high stress and strain inside the spinal cord, and this effect was also amplified by increased canal encroachments and cervical hypermobility. The spinal cord might evade lateral encroachment, leading to a reduction in the maximum stress and principal strain within the spinal cord in local-type herniation. Although the impact was limited in the case of diffuse type, the maximum stress tended to appear in the white matter near the encroachment site while compression from both ventral and dorsal was essential to make maximum stress appear in the grey matter. The existence of canal encroachment can reduce the safe range for spinal cord activities, and hypermobility activities may induce spinal cord injury. Besides, the ligamentum flavum plays an important role in the development of central canal syndrome.Significance. This model will enable researchers to have a better understanding of the influence of cervical degenerative diseases on the spinal cord during extension and flexion.

Scriptaid is a prospective agent for improving human asthenozoospermic sample quality and fertilization rate in vitro.

ABSTRACT: Male infertility is a global issue caused by poor sperm quality, particularly motility. Enhancement of the sperm quality may improve the fertilization rate in assisted reproductive technology (ART) treatment. Scriptaid, with a novel human sperm motility-stimulating activity, has been investigated as a prospective agent for improving sperm quality and fertilization rate in ART. We evaluated the effects of Scriptaid on asthenozoospermic (AZS) semen, including its impact on motility stimulation and protective effects on cryopreservation and duration of motility, by computer-aided sperm analysis (CASA). Sperm quality improvement by Scriptaid was characterized by increased hyaluronan-binding activity, tyrosine phosphorylation, adenosine triphosphate (ATP) concentration, mitochondrial membrane potential, and an ameliorated AZS fertilization rate in clinical intracytoplasmic sperm injection (ICSI) experiments. Furthermore, our identification of active Scriptaid analogs and different metabolites induced by Scriptaid in spermatozoa lays a solid foundation for the future biomechanical exploration of sperm function. In summary, Scriptaid is a potential candidate for the treatment of male infertility in vitro as it improves sperm quality, prolongs sperm viability, and increases the fertilization rate.

Effect of compressive and tensile forces on glucose concentration and cell viability within the intervertebral disc: A finite element study.

Understanding the role of mechanical force on tissue nutrient transport is essential, as sustained force may affect nutrient levels within the disc and initiate disc degeneration. This study aims to evaluate the time-dependent effects of different compressive force amplitudes as well as tensile force on glucose concentration and cell viability within the disc. Based on the mechano-electrochemical mixture theory, a multiphasic finite element model of the lumbar intervertebral disc was developed. The minimum glucose concentration and minimum cell density in both normal and degenerated discs were predicted for different compressive force amplitudes, tensile force, and corresponding creep time. Under high compressive force, the minimum glucose concentration exhibited an increasing and then decreasing trend with creep time in the normal disc, whereas that of the degenerated disc increased, then decreased, and finally increased again. At steady state, a higher compressive force was accompanied by a lower glucose concentration distribution. In the degenerated disc, the minimum cell density was negatively correlated with creep time, with a greater range of affected tissue under a higher compressive force. For tensile force, the minimum glucose concentration of the degenerated disc raised over time. This study highlighted the importance of creep time, force magnitude, and force type in affecting nutrient concentration and cell viability. Sustained weight-bearing activities could deteriorate the nutrient environment of the degenerated disc, while tensile force might have a nonnegligible role in effectively improving nutrient levels within the degenerated disc.

Prognostic factors and treatment responses among patients with gross residual disease in differentiated thyroid cancer.

BACKGROUND: Various postoperative staging systems were developed to assess the outcome of differentiated thyroid cancer from initial risk after surgery to dynamic changing prognosis during follow-up. The objective of our retrospective cohort study was to identify risk factors contributing to macroscopic positive surgical margin (R2 resection) and parameters in discriminating the treatment responses and prognosis among R2 patients. METHODS: In total, 242 differentiated thyroid cancer patients with extrathyroidal extension who underwent a thyroidectomy at Kaohsiung Chang Gung Memorial Hospital between January 2013 and July 2018, were included. The patients were grouped according to the presence or absence of gross residual disease (R2). The R2 patients were further classified into two categories according to their treatment response into excellent and nonexcellent groups. The parameters and treatment outcomes were compared between these groups. RESULTS: The mean follow-up time was 45.3 months. Two hundred seven (85.5%) patients had either surgery-free or microscopic margins (R0/R1), while 35 (14.5%) had R2 resection. In the R2 group (n = 35), 15 (42.9%) patients achieved an excellent response, while 20 (57.1%) achieved a nonexcellent response. Statistically significant differences were observed in the extent of neck dissection, TSH-Tg level, post-RAI Tg level, nodal status, and recurrence between the two groups. The Kaplan-Meier curves for 5-year local and distant recurrence-free survival of R0/R1 versus R2 patients were 90.0% versus 66.3%, and 98.4% versus 90.7%, respectively ( p < 0.001). Among the R2 patients, the excellent responders had a higher local recurrence-free survival than nonexcellent responders (93.3% vs. 45.1%, p = 0.008). CONCLUSION: There are significant disparities in recurrence-free survival among R2 patients with different treatment responses. The nodal status of papillary thyroid cancer and thyroglobulin level after thyroidectomy and RAI were factors contributing to difference in their treatment responses.