Objective
To review recent biomolecular advances in etiopathogenesis of acquired cholesteatoma.
Data Sources
MEDLINE via OVID (to March 2014) and PubMed (to March 2014).
Review Methods
All articles ...referring to etiopathogenesis of acquired cholesteatoma were identified in the above databases, from which 89 articles were included in this review.
Results
The mechanisms underlying the etiopathogenesis of acquired cholesteatoma remain a subject of competing hypotheses. Four theories dominate the debate, including theories of invagination, immigration, squamous metaplasia, and basal cell hyperplasia. However, no single theory has been able to explain the clinical characteristics of all cholesteatoma types: uncoordinated hyperproliferation, invasion, migration, altered differentiation, aggressiveness, and recidivism. Modern technologies have prompted a number of researchers to seek explanations at the molecular level. First, cholesteatomas could be considered an example of uncontrolled cell growth, capable of altering the balance toward cellular hyperproliferation and enhancing the capacity for invasion and osteolysis. Second, the dysregulation of cell growth control involves internal genomic or epigenetic alterations and external stimuli, which induce excessive host immune response to inflammatory and infectious processes. This comprises several complex and dynamic pathophysiologic changes that involve extracellular and intracellular signal transduction cascades.
Conclusions
This article summarizes the existing theories and provides conceptual insights into the etiopathogenesis of acquired cholesteatoma, with the aim of stimulating continued efforts to develop a nonsurgical means of treating the disorder. Laryngoscope, 125:234–240, 2015
The existence of acquired cholesteatoma has been recognized for more than three centuries; however, the nature of the disorder has yet to be determined. Without timely detection and intervention, ...cholesteatomas can become dangerously large and invade intratemporal structures, resulting in numerous intra- and extracranial complications. Due to its aggressive growth, invasive nature, and the potentially fatal consequences of intracranial complications, acquired cholesteatoma remains a cause of morbidity and death for those who lack access to advanced medical care. Currently, no viable nonsurgical therapies are available. Developing an effective management strategy for this disorder will require a comprehensive understanding of past progress and recent advances. This paper presents a brief review of background issues related to acquired middle ear cholesteatoma and deals with practical considerations regarding the history and etymology of the disorder. We also consider issues related to the classification, epidemiology, histopathology, clinical presentation, and complications of acquired cholesteatoma and examine current diagnosis and management strategies in detail.
This study compares endoscopic and microscopic tympanoplasty for the treatment of chronic otitis media (COM) without cholesteatoma.
This retrospective study included 153 ears (139 patients) treated ...surgically (endoscopic or microscopic tympanoplasty) for COM in the absence of cholesteatoma at our hospital between January 2008 and October 2015. The adoption of transcanal endoscopic ear surgery (TEES) or microscopic ear surgery (MES) was divided temporally (before and since 2014). Comparisons between these groups focused on the following: (I) surgical outcomes, including successful tympanic membrane healing and post-operative complications; (II) restoration of hearing; and (III) consumption of medical resources, including the duration of surgery and anesthesia. All patients had a follow-up period of at least 3 months after surgery.
No statistically significant differences were observed between the two groups regarding surgical outcome or hearing restoration. TEES resulted in the successful healing of 96.2% of ear drums, whereas MES led to successful healing in 92% (p = 0.2826) of cases. The average hearing gains following surgery were 10.27 ± 6.4 and 12.43 ± 7.46 dB in TEES and MES, respectively. The consumption of medical resources in the TEES group was lower than that of the MES group (TEES versus MES) regarding the average operating time (87.8 ± 19.01 min (mins) versus 110.2 ± 17.0 (mins) (p < 0.0001)) and the mean duration of anesthesia ((for general anesthesia patients) (122.1 ± 21.25 mins versus 145.8 ± 16.88 mins) (p ≤ 0.0001)).
The results indicate that TEES can achieve surgical outcomes and hearing restoration comparable to those of MES. In addition, TEES appears to be associated with shorter surgical and anesthesia time, which makes it an ideal alternative for the management of COM without cholesteatoma.
This study was approved by the Institutional Review Board of the Cathay General Hospital. (CGHIRB No: CGH-P105012 ).
•The electronic structure and property of the N-doped defective graphene structures.•Physical origin of the enhanced Li/Na capacity on the graphene surface by N-doping.•Effect of the pyridinic-N ...doping at the graphene edge on the Li/Na storage capacity.•Effect of H-termination on the edge pyridinic-N atoms on the Li/Na storage capacity.
We performed first-principles calculations to investigate the effect of N-doping on the electronic structure property and the Li/Na storage behaviors of graphene nanomaterials. Our calculations first revealed that the N-doping treatment can effectively increase the number of C vacancy defects in graphene and the adsorption energy of a Li/Na atom on C vacancy can be largely enhanced by increasing the pyridinic-/pyrrolic-N atoms at the vacancy site. However, the reversible Li/Na capacity of the C vacancy defect was found to be largely reduced by increasing the doping level of N, which was primarily determined by the electronic structure property of the N-doped graphene structures and their strong electrostatic interactions with Li/Na. Our results clearly revealed that the enhanced Li/Na capacity by the N-doping on the graphene surface can be primarily attributed to the induced formation of a great number of C vacancy defects rather than the presence of the pyridinic-/pyrrolic-N on the basal plane. Our calculations also showed that the pyridinic-N doped graphene edges can possess a Li/Na capacity comparable to that of the N-doped C vacancy defects. Nevertheless, this excess Li/Na capacity was found to be largely reduced by the termination of the H atoms on these edge pyridinic-N groups.
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•Mg doping facilitates the incorporation of atomic hydrogen in the ZnO lattice via Ar-H2 APPJ treatment.•The H-doped Zn0.9Mg0.1O thin film prepared using Ar-H2 APPJ treatment is ...characterized by the dominance of interstitial defects, Zni and Oi, which simultaneously enhance photocurrent response and reduce photocorrosion.•The presence of Hi and MgH2 in the H-doped Zn0.9Mg0.1O thin film contributes to the mitigation of photocorrosion by leveraging the reducing effect of hydrogen.•Pure ZnO thin film is characterized by the dominance of VO after Ar-H2 APPJ treatment, resulting in erratic photocurrent response and severe photocorrosion.
The effects of Mg doping and Ar-H2 atmospheric pressure plasma jet (APPJ) treatment on zinc oxide (ZnO) thin films were investigated. Mg doping has been demonstrated to facilitate the incorporation of atomic hydrogen in the ZnO lattice via Ar-H2 APPJ. The co-doping of Mg and H changed ZnO’s primary oxygen defect type from vacancy (VO) to interstitial (Oi), which reduced photocorrosion significantly. The dominance of interstitial defects (i.e., Zni and Oi) in the H-doped Zn0.9Mg0.1O thin film was confirmed by photoluminescence spectroscopy. Zni shallow donors improved light absorption at wavelengths > 650 nm, increasing the film’s photocurrent density. Without Mg, doping H via Ar-H2 APPJ was ineffective for pure ZnO thin film. The dominance of VO in pure ZnO thin film after APPJ, though enhanced light absorbance, gave rise to an erratic photocurrent response due to the instability of VO. The lack of acceptor states also led to severe photocorrosion.
The aim of this study was to review recent advances in the management of acquired cholesteatoma. All papers referring to acquired cholesteatoma management were identified in Medline via OVID (1948 to ...December 2013), PubMed (to December 2013), and Cochrane Library (to December 2013). A total of 86 papers were included in the review. Cholesteatoma surgery can be approached using either a canal wall up (CWU) or canal wall down (CWD) mastoidectomy with or without reconstruction of the middle ear cleft. In recent decades, a variety of surgical modifications have been developed including various “synthesis” techniques that combine the merits of CWU and CWD. The application of transcanal endoscopy has also recently gained popularity; however, difficulties associated with this approach remain, such as the need for one-handed surgery, the inability to provide continuous irrigation/suction, and limitations regarding endoscopic accessibility to the mastoid cavity. Additionally, several recent studies have reported successes in the application of laser-assisted cholesteatoma surgery, which overcomes the conflicting goals of eradicating disease and the preservation of hearing. Nevertheless, the risk of residual disease remains a challenge. Each of the techniques examined in this study presents pros and cons regarding final outcomes, such that any pronouncements regarding the superiority of one technique over another cannot yet be made. Flexibility in the selection of surgical methods according to the context of individual cases is essential in optimizing the outcomes.
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•Phase transformation in the highly-compressed CoCrFeMnNi alloy was investigated.•A highly crystal orientation-dependent phase transformation behavior was observed.•Deformation twin ...boundary effectively facilitates the fcc-hcp phase transformation.•Phase transformation can be effectively promoted by a large deviatoric compression.
We performed the modified-embedded-atom-method (MEAM) based molecular dynamics (MD) simulations to investigate the plastic deformation and phase transformation behaviors in the CoCrFeMnNi HEA under high compression at room temperature. Our MD simulations revealed that the stress-induced phase transformations in the CoCrFeMnNi HEA are strongly crystal orientation-dependent. The 0 0 1 uniaxial compression can induce the significant face-centered-cubic (fcc) -to-hexagonal-close-packed (hcp) phase transformation via successive emissions of partial dislocations from the extended stacking faults, twin boundaries and hcp-lamellas created during the early stage of deformation. As for the 1 1 0 and 1 1 1 uniaxial compressions, however, the transformed hcp atoms can simply form the intrinsic/extrinsic stacking faults. Although the 0 0 1 uniaxial compression produced a much lower dislocation density than the other two systems, it induced much more constituents transformed into the hcp atoms at the end of phase transformation. Our results clearly indicated that the deformation twin boundaries and extended hcp-lamellas play a critical role in facilitating the stress-induced fcc-to-hcp phase transformation in the CoCrFeMnNi HEA. Furthermore, it was found that the phase transformation in the CoCrFeMnNi HEA can be effectively facilitated by a large deviatoric compressive stress while it may tend to be significantly retarded by a hydrostatic compression. Our results also showed that the plastic deformation behaviors in Ni under high compression are very similar to those occurred in the CoCrFeMnNi HEA though nearly all the hcp atoms can simply constitute the intrinsic/extrinsic stacking faults without the formation of any bulk hcp phase in the fcc lattice. The main discrepancy in the phase transformation behaviors between the Ni and CoCrFeMnNi HEA can be largely attributed to the much lower stacking fault energy of the CoCrFeMnNi HEA than other fcc metals.
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