Transdural Spinal Cord Herniation: An Exceptional Complication of Thoracoscopic Discectomy: 2-Dimensional Operative Video

Thoracic disc herniation is a rare and severe condition, whose treatment may have complications including dural tears. Although benign in most cases, dural tears may induce iatrogenic transdural herniation of the spinal cord. The video demonstrates the diagnosis and surgical treatment of iatrogenic transdural herniation of the spinal cord. Here, we report a case of spinal cord herniation after thorascopic treatment of a thoracic disc herniation (DH). A 28-yr-old male presented with several years of left lower extremity weakness and was found to have a T6-7 DH. He underwent DH resection through video assisted mini-thoracotomy at another institution. In the immediate postoperative period, he developed a Brown-Sequard syndrome with left leg weakness. The surgeon decided not to reoperate and the patient improved with rehabilitation, allowing him to walk again. At 6 mo postop, he experienced sudden neurologic worsening but did not present to our clinic until 6 mo later. At this time, he had near complete paraplegia with bilateral lower extremity spasticity and central neuropathic pain. MRI showed a pseudo-meningocele and features suggesting a lateral spinal cord herniation. After a multidisciplinary meeting, we elected to perform a posterolateral approach with costo-arthro-pediculectomy and durotomy to repair the SC herniation. Immediately postop, the patient had a slight improvement in right lower extremity function, with decreased pain and spasticity. This case shows a transdural SC herniation, a rare complication after resection of DH. It is possible that an unreported or unrecognized dural tear at the time of the initial surgery, combined with the negative pressure of the thoracic cavity, put the patient at risk for this particular complication. The authors state that the patient gave his informed consent.

New Insights into Expression of Hormonal Receptors by Meningiomas

OBJECTIVE

Meningiomas have a female predilection, which is even stronger for spinal than for intracranial meningiomas. The relationship between meningiomas and endogenous or exogenous sex hormones such as cyproterone acetate (CPA) is well documented, yet their underlying mechanism remains unknown. Clarification of the expression profile of hormonal receptors by meningiomas would help us to better understand their hormonal susceptibility.

METHODS

We used tissue microarray and immunohistochemistry to determine the receptor status of the 3 main sex hormones: androgen (AR), estrogen, and progesterone (PR) in 30 intracranial meningiomas, 30 spinal meningiomas, and 30 meningiomas developed on CPA.

RESULTS

AR status was positive in 73% of meningiomas in the intracranial group, 87% of meningiomas in the CPA group, and in all meningiomas in the spinal group. Estrogen status was positive in only 7% of meningiomas in the intracranial group and in only 3% of meningiomas in the CPA group but in 30% of meningiomas in the spinal group. PR status was positive in 90% of meningiomas in the intracranial group, in 97% of meningiomas in the CPA group, and in 87% of meningiomas in the spinal group. These specific hormonal receptor statuses based on immunoreactive score were reflected on staining intensities. Furthermore, AR and PR expression was correlated in each group.

CONCLUSIONS

Our study shows that intracranial meningiomas, spinal meningiomas, and meningiomas developed on CPA express specific hormonal receptor patterns. This result invites the scientific community to review the potential role of AR in the unbalanced sex ratio of meningiomas.

Patients with Coronavirus 2019 (COVID-19) and Surgery: Guidelines and Checklist Proposal

The management of patients with novel coronavirus 2019 (COVID-19) represents a new challenge for medical and surgical teams. Each operating room in the world should be prepared thoughtfully, and the development of a protocol and patient route seems mandatory. An adequate degree of protection must be used. We propose recommendations to help different professionals in the establishment of protocols for the management of patients with COVID-19. We also offer a checklist that could be used in the operating room.

Histomolecular characterization of intracranial meningiomas developed in patients exposed to high-dose cyproterone acetate: an antiandrogen treatment

Background

Meningiomas are the most common primary intracranial tumors in adults. The relationship between meningiomas and exogenous sex hormones such as cyproterone acetate (CPA) is well documented, yet the underlying mechanisms remain unknown. Defining the histomolecular status of meningiomas developed on CPA would help us to better understand the oncogenesis of these tumors.

Methods

We identified 30 patients operated for a meningioma after long-term high-dose CPA therapy and with a history of CPA discontinuation before establishing the indication for surgical intervention. We used array-comparative genomic hybridization (to characterize copy number changes in those 30 meningiomas and subsequently performed next-generation sequencing with the National Institute of Cancer (INCa) solid tumor panel, which is a targeted panel of clinically actionable genes. We also examined grade, type, and clinical features.

Results

We identified AKT1 mutations or PIK3CA mutations in 33.3% of CPA meningiomas. AKT1 and PIK3CA mutations were mutually exclusive. Enrichment in oncogenic PIK3CA mutations in the CPA cohort was detected. CPA meningiomas showed chromosomal stability and were located mainly in the skull base. Ninety percent of CPA meningiomas were low-grade meningiomas and 63.4% were meningotheliomas. Half of our CPA cohort had microcystic components.

Conclusion

Our study shows that low-grade meningothelial meningiomas of the skull base are predominant in CPA meningiomas. We identified PIK3CA/AKT1 pathway as a hypothetical actor in onco-pharmacological interaction between meningiomas and CPA. This signaling pathway could be an interesting target for precision medicine trials in meningioma patients who have been subjected to CPA. Our results could invite the scientific community to review the current classification of meningiomas and to evolve toward more specific histomolecular classification.

Gravitational symmetry breaking leads to a polar liquid crystal phase of microtubules in vitro

Recent space-flight experiments performed by Tabony's team provided further evidence that a microgravity environment strongly affects the spatio-temporal organization of microtubule assemblies. Characteristic time and length scales were found that govern the organization of oriented bundles under Earth's gravitational field (GF). No such organization has been observed in a microgravity environment. This paper discusses physical mechanisms resulting in pattern formation under gravity and its disappearance in microgravity. The subtle interplay between chemical kinetics, diffusion, gravitational drift, thermal fluctuations, electrostatic interactions and liquid crystalline characteristics provides a plausible scenario.

Elastic vibrations in seamless microtubules

Parameters characterizing elastic properties of microtubules, measured in several recent experiments, reflect an anisotropic character. We describe the microscopic dynamical properties of microtubules using a discrete model based on an appropriate lattice of dimers. Adopting a harmonic approximation for the dimer-dimer interactions and estimating the lattice elastic constants, we make predictions regarding vibration dispersion relations and vibration propagation velocities. Vibration frequencies and velocities are expressed as functions of the elastic constants and of the geometrical characteristics of the microtubules. We show that vibrations which propagate along the protofilament do so significantly faster than those along the helix.

Anisotropic elastic properties of microtubules

We review and model the experimental parameters which characterize elastic properties of microtubules. Three macroscopic estimates are made of the anisotropic elastic moduli, accounting for the molecular forces between tubulin dimers: for a longitudinal compression of a microtubule, for a lateral force and for a shearing force. These estimates reflect the anisotropies in these parameters observed in several recent experiments.

Ionic wave propagation along actin filaments

We investigate the conditions enabling actin filaments to act as electrical transmission lines for ion flows along their lengths. We propose a model in which each actin monomer is an electric element with a capacitive, inductive, and resistive property due to the molecular structure of the actin filament and viscosity of the solution. Based on Kirchhoff's laws taken in the continuum limit, a nonlinear partial differential equation is derived for the propagation of ionic waves. We solve this equation in two different regimes. In the first, the maximum propagation velocity wave is found in terms of Jacobi elliptic functions. In the general case, we analyze the equation in terms of Fisher-Kolmogoroff modes with both localized and extended wave characteristics. We propose a new signaling mechanism in the cell, especially in neurons.

Models of spatial and orientational self-organization of microtubules under the influence of gravitational fields

Tabony and co-workers [C. Papaseit, N. Pochon, and J. Tabony, Proc. Natl. Acad. Sci. U.S.A. 97, 8364 (2000)] showed that the self-organization of microtubules from purified tubulin solutions is sensitive to gravitational conditions. In this paper, we propose two models of spatial and orientational self-organization of microtubules in a gravitational field. First, the spatial model is based on the dominant chemical kinetics. The pattern formation of microtubule concentration is obtained (1) in terms of a moving kink in the limit when the disassembly rate is negligible, and (2) for the case of no free tubulin and only assembled microtubules present. Second, the orientational pattern of striped microtubule domains is consistent with predictions from a phenomenological Landau-Ginzburg free energy expansion in terms of an orientational order parameter.

Weightlessness acts on human breast cancer cell line MCF-7

Because cells are sensitive to mechanical forces, weightlessness might act on stress-dependent cell changes. Human breast cancer cells MCF-7, flown in space in a Photon capsule, were fixed after 1.5, 22 and 48 h in orbit. Cells subjected to weightlessness were compared to 1 g in-flight and ground controls. Post-flight, fluorescent labeling was performed to visualize cell proliferation (Ki-67), three cytoskeleton components and chromatin structure. Confocal microscopy and image analysis were used to quantify cycling cells and mitosis, modifications of the cytokeratin network and chromatin structure. Several main phenomena were observed in weightlessness: The perinuclear cytokeratin network and chromatin structure were looser; More cells were cycling and mitosis was prolonged. Finally, cell proliferation was reduced as a consequence of a cell-cycle blockade; Microtubules were altered in many cells. The results reported in the first point are in agreement with basic predictions of cellular tensegrity. The prolongation of mitosis can be explained by an alteration of microtubules. We discuss here the different mechanisms involved in weightlessness alteration of microtubules: i) alteration of their self-organization by reaction-diffusion processes, and a mathematical model is proposed, ii) activation or deactivation of microtubules stabilizing proteins, acting on both microtubule and microfilament networks in cell cortex.

Quantitative analysis of cytokeratin network topology in the MCF7 cell line

BACKGROUND

In the MCF7 human breast cancer cell line, several patterns of cytokeratin networks are observed, depending on the intracellular localization. Our hypothesis is that architectural variations of cytokeratin networks depend on local tensions or forces appearing spontaneously in the cytoplasm. The aim of this work was to discriminate between the different patterns and to quantitate these variations.

MATERIALS AND METHODS

Image analysis procedures were developed to extract cytokeratin filament networks visualized by immunofluorescence and confocal microscopy. Two methods were used to segment sets of curvilinear objects. The first, the "mesh-approach," based on classical methods of mathematical morphology, takes into account global network topology. The second, the "filament-approach" (novel), is meant to account for individual element morphology. These methods and their combination allow the computation of several features at two levels of geometry: global (network topology) and local (filament morphology).

RESULTS

Variations in cytokeratin networks are characterized by their connectivity, density, mesh structure, and filament shape. The connectivity and the density of a network describe its location in a local "stress-force" zone or in a "relaxed" zone. The mesh structure characterizes the intracellular localization of the network. Moreover, the filament shape reflects the intracellular localization and the occurrence of a "stress-force" zone.

CONCLUSIONS

These features permitted the quantitation of differences within the network patterns and within the specific filament shapes according to the intracellular localization. Further experiments on cells submitted to external forces will test the hypothesis that the architectural variations of intermediate filaments reflect intracytoplasmic tensions.