Potential risk of mitomycin C at high concentrations on peripheral nerve structure

Postoperative Epidural Fibrosis: Challenges and Opportunities - A Review

Postoperative epidural fibrosis (EF) is still a major limitation to the success of spine surgery. Fibrotic adhesions in the epidural space, initiated via local trauma and inflammation, can induce difficult-to-treat pain and constitute the main cause of failed back surgery syndrome, which not uncommonly requires operative revision. Manifold agents and methods have been tested for EF relief in order to mitigate this longstanding health burden and its socioeconomic consequences. Although several promising strategies could be identified, few have thus far overcome the high translational hurdle, and there has been little change in standard clinical practice. Nonetheless, notable research progress in the field has put new exciting avenues on the horizon. In this review, we outline the etiology and pathogenesis of EF, portray its clinical and surgical presentation, and critically appraise current efforts and novel approaches toward enhanced prevention and treatment.

Neuroimmune crosstalk in the cornea: The role of immune cells in corneal nerve maintenance during homeostasis and inflammation

In the cornea, resident immune cells are in close proximity to sensory nerves, consistent with their important roles in the maintenance of nerves in both homeostasis and inflammation. Using in vivo confocal microscopy in humans, and ex vivo immunostaining and fluorescent reporter mice to visualize corneal sensory nerves and immune cells, remarkable progress has been made to advance our understanding of the physical and functional interactions between corneal nerves and immune cells. In this review, we summarize and discuss recent studies relating to corneal immune cells and sensory nerves, and their interactions in health and disease. In particular, we consider how disrupted corneal nerve axons can induce immune cell activity, including in dendritic cells, macrophages and other infiltrating cells, directly and/or indirectly by releasing neuropeptides such as substance P and calcitonin gene-related peptide. We summarize growing evidence that the role of corneal intraepithelial immune cells is likely different in corneal wound healing versus other inflammatory-dominated conditions. The role of different types of macrophages is also discussed, including how stromal macrophages with anti-inflammatory phenotypes communicate with corneal nerves to provide neuroprotection, while macrophages with pro-inflammatory phenotypes, along with other infiltrating cells including neutrophils and CD4⁺ T cells, can be inhibitory to corneal re-innervation. Finally, this review considers the bidirectional interactions between corneal immune cells and corneal nerves, and how leveraging this interaction could represent a potential therapeutic approach for corneal neuropathy.

Role of Imaging Studies in Evaluating Patients Post Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy

A 77-year-old male presented to the ED with a new onset of acute abdominal pain, nausea, and vomiting. He had a previous surgical history of cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) for an appendiceal tumor. Despite the repeated reassuring abdominal examinations, CT abdomen showed high-grade bowel obstruction and perforation. He was urgently taken to the operating room and underwent resection of 70 cm segment of small ischemic bowel with primary anastomosis. His postoperative course was complicated with atrial fibrillation (AF) requiring cardioversion and medical therapy. Later, he was discharged home under stable conditions. Relying on abdominal signs, an abdominal exam in a patient with a previous history of extensive peritonectomy and post-HIPEC surgery is challenging due to the altered peritoneal anatomy. As a result, the abdominal examination findings can be benign and misleading. This can lead to delayed surgical intervention, thereby increasing morbidity and mortality significantly. Therefore, a detailed evaluation with a low threshold for abdominal imaging studies like abdominal X-rays and CT abdomen series is warranted in this subset of patients.

Diversity of Actinobacteria Isolated from Date Palms Rhizosphere and Saline Environments: Isolation, Identification and Biological Activity Evaluation

The diversity of cultural Actinobacteria in two types of Algerian Sahara environments, including saline environments and date palms rhizosphere, was investigated. In this study, a total of 40 strains of actinomycetes was isolated from different soil samples, using a rehydration and centrifugation method. Molecular identification, based on 16S rRNA gene sequence analysis, revealed that these isolates were affiliated to six clusters corresponding to eight genera, including Streptomyces, Nocardiopsis, Saccharopolyspora, Actinomadura, Actinocorallia, Micromonospora, Couchioplanes, and Planomonospora. A taxonomic analysis, based on the morphological, physiological, biochemical, and molecular investigation, of selected strains, which belong to the rare Actinobacteria, was undertaken. Four strains (CG3, A111, A93, and A79) were found to form distinct phyletic lines and represent new actinobacterial taxa. An assessment of antimicrobial proprieties of the 40 obtained actinomycetes strains, showed moderate to strong antimicrobial activities against fungi and bacteria. This study demonstrated the richness of Algerian Sahara with rare Actinobacteria, which can provide novel bioactive metabolites, to solving some of the most challenging problems of the day, such as multi-drug resistance.

Corneal nerves anatomy, function, injury and regeneration

The cornea is a highly innervated tissue, exhibiting a complex nerve architecture, distribution, and structural organization. Significant contributions over the years have allowed us to come to the current understanding about the corneal nerves. Mechanical or chemical trauma, infections, surgical wounds, ocular or systemic comorbidities, can induce corneal neuroplastic changes. Consequently, a cascade of events involving the corneal wound healing, trophic functions, neural circuits, and the lacrimal products may interfere in the corneal homeostasis. Nerve physiology drew the attention of investigators due to the popularization of modern laser refractive surgery and the perception of the destructive potential of the excimer laser to the corneal nerve population. Nerve fiber loss can lead to symptoms that may impact the patient's quality of life, and impair the best-corrected vision, leading to patient and physician dissatisfaction. Therefore, there is a need to better understand preoperative signs of corneal nerve dysfunction, the postoperative mechanisms of nerve degeneration and recovery, aiming to achieve the most efficient way of treating nerve disorders related to diseases and refractive surgery.

The Impact of Photorefractive Keratectomy and Mitomycin C on Corneal Nerves and Their Regeneration

PURPOSE

To determine how photorefractive keratectomy (PRK) and mitomycin C (MMC) affect corneal nerves and their regeneration over time after surgery.

METHODS

Twenty-eight New Zealand rabbits had corneal epithelial scraping with (n = 3) and without (n = 3) MMC 0.02% or -9.00 diopter PRK with (n = 6) and without (n = 16) MMC 0.02%. Corneas were removed after death and corneal nerve morphology was evaluated using acetylcholinesterase immunohistochemistry and beta-III tubulin staining after 1 day for all groups, after 1 month for PRK with and without MMC, and 2, 3, and 6 months after PRK without MMC. Image-Pro software (Media Cybernetics, Rockville, MD) was used to quantitate the area of nerve loss after the procedures and, consequently, regeneration of the nerves over time. Opposite eyes were used as controls.

RESULTS

Epithelial scraping with MMC treatment did not show a statistically significant difference in nerve loss compared to epithelial scraping without MMC (P = .40). PRK with MMC was significantly different from PRK without MMC at 1 day after surgery (P = .0009) but not different at 1 month after surgery (P = .90). In the PRK without MMC group, nerves regenerated at 2 months (P < .0001) but did not return to the normal preoperative level of innervation until 3 months after surgery (P = .05). However, the morphology of the regenerating nerves was abnormal-with more tortuosity and aberrant innervation compared to the preoperative controls-even at 6 months after surgery.

CONCLUSIONS

PRK negatively impacts the corneal nerves, but they are partially regenerated by 3 months after surgery in rabbits. Nerve loss after PRK extended peripherally to the excimer laser ablated zone, indicating that there was retrograde degeneration of nerves after PRK. MMC had a small additive toxic effect on the corneal nerves when combined with PRK that was only significant prior to 1 month after surgery. [J Refract Surg. 2018;34(12):790-798.].

Update on biomaterials for prevention of epidural adhesion after lumbar laminectomy

Lumbar laminectomy often results in failed back surgery syndrome. Most scholars support the three-dimensional theory of adhesion: Fibrosis surrounding the epidural tissues is based on the injured sacrospinalis behind, fibrous rings and posterior longitudinal ligaments. Approaches including using the minimally invasive technique, drugs, biomaterial and nonbiomaterial barriers to prevent the postoperative epidural adhesion were intensively investigated. Nevertheless, the results are far from satisfactory. Our review is based on various implant biomaterials that are used in clinical applications or are under study. We show the advantages and disadvantages of each method. The summary will help us to figure out ideas towards new techniques. The translational potential of this article: This review summarises recent biomaterials-related clinical and basic research that focuses on prevention of epidural adhesion after lumbar laminectomy. We also propose a novel possible translational method where a soft scaffold acts as a physical barrier in the early stage, engineered adipose tissue acts as a biobarrier in the later stage in the application of biomaterials and adipose-derived mesenchymal stem cells are used for prevention of epidural adhesion.

Upregulation of P27Kip1 by mitomycin C induces fibroblast apoptosis and reduces epidural fibrosis

Fibroblast excessive proliferation is considered as one of the major reasons of epidural fibrosis after laminectomy. Recent studies have shown that mitomycin C (MMC) could successfully reduce the formation of epidural fibrosis by inducing fibroblasts apoptosis. However, the detailed mechanism was still unclear. Increasing evidence indicated that P27^Kip1 (P27) could result in apoptotic cell death in various cells. In this study, we investigated whether MMC could induce fibroblasts apoptosis and reduce epidural fibrosis by regulating P27. Western blot analysis, Hoechst staining, Flow cytometry, and Cell Counting Kit-8 (CCK-8) assay were used to detect the effect of MMC on fibroblasts apoptosis by regulating P27 expression in vitro. Moreover, histological and immunohistochemical assays were used to evaluate the effect of MMC on reducing epidural fibrosis by regulating P27 expression in rats. The results showed that MMC could induce fibroblasts apoptosis and upregulate P27 expression in vitro. Knockdown of P27 partially attenuated MMC-induced expressions of P27 and cleaved PARP as well as increased the cell viability. MMC could reduce epidural fibrosis in a dose-dependent manner in rats by histological analysis. The expression of P27 was increased by MMC treatment as shown by immuohistochemical analysis. In conclusion, this study demonstrated that MMC could upregulate P27 expression, which subsequently induced fibroblasts apoptosis and reduced epidural fibrosis.