Sunday, September 4, 2022

Deformation of implant retaining screws—Study with stereoscopic microscopy and microCT

alexandrossfakianakis shared this article with you from Inoreader

Abstract

Background

The prosthetic screw fixes the prostheses to the implants. Upon osteointegration, the untightening of the prosthetic screw is the most common problem in oral rehabilitation with implants.

Objective

To study the deformation of the implant retaining hexagonal screw head.

Methods

This investigation used two methods for evaluating the screw head's area of deformation (mm2): a stereoscopic microscopy and micro computed tomography (microCT). For stereoscopic microscopy, 16 titanium alloy (T) and 16 titanium gold-plated alloy (G) screws of the Zimmer Biomet™ brand were used, divided into eight groups: group 0 (control group), groups T1 and G1 (screws tightened 10 times to 20 Ncm), the groups T2 and G2 (screws tightened 20 times to 20 Ncm) and the groups T3 and G3 (screws tightened 10 times to 30 Ncm). In the study with microCT, one screw was randomly chosen from each of the groups described above to perform the scanning by microCT.

Results

When comparing the type of screw material using stereoscopic microscopy, no statistically significant differences were found (p > 0.05). Contrarily, different number of successive grips and different torque value showed statistically significant differences in the head section of the retaining screws (p < 0.05). The observation by microCT showed the torque applied is crucial to the head deformation in titanium screws. In gold-plated screws the successive tightening appears to be pivotal.

Conclusion

Titanium and gold screws tend to behave similarly. By increasing the tightening cycles and the torque values of protocols greater levels of deformations can be expected. In general, microCT data showed better results for gold-plated titanium alloy.

Clinical Significance

To control severe screw head deformation and the impossibility of untightening the implant's restoration, clinicians should avoid extreme torque values and prevent surpassing 10 tightening cycles.
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Computer Simulation of the Electrical Stimulation of the Human Vestibular System: Effects of the Reactive Component of Impedance on Voltage Waveform and Nerve Selectivity

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AbstractThe vestibular system is responsible for our sense of balance and spatial orientation. Recent studies have shown the possibility of partially restoring the function of this system using vestibular implants. Electrical modeling is a valuable tool in assisting the development of these implants by analyzing stimulation effects. However, previous modeling approaches of the vestibular system assumed quasi-static conditions. In this work, an extended modeling approach is presented that considers the reactive component of impedance and the electrode-tissue interface and their effects are investigated in a 3D human vestibular computer model. The Fourier finite element method was employed considering the frequency-dependent electrical properties of the different tissues. The electrode-tissu...
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Key mutations on spike protein altering ACE2 receptor utilization and potentially expanding host range of emerging SARS‐CoV‐2 variants

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Abstract

Increasing evidence supports inter-species transmission of SARS-CoV-2 variants from human to domestic or wild animals during the ongoing COVID-19 pandemic, which is posing great challenges to epidemic control. Clarifying the host range of emerging SARS-CoV-2 variants will provide instructive information for the containment of viral spillover. The spike protein (S) of SARS-CoV-2 is the key determinant of receptor utilization, and therefore amino acid mutations on S will probably alter viral host range. Here, in order to evaluate the impact of S mutations, we constructed 20 Hela cell lines stably expressing ACE2 orthologs from different animals, and prepared 27 pseudotyped SARS-CoV-2 carrying different spike mutants, among which 20 bear single mutation and the other 7 were cloned from emerging SARS-CoV-2 variants, including D614G, Alpha (B.1.1.7), Beta (B.1.351), Gamma (P.1), Delta (B.1.617.2), Lambda (B.1.429) and Mu (B.1.621). Using pseudoviral reporter assa y, we identified that the substitutions of T478I and N501Y enabled the pseudovirus to utilize chicken ACE2, indicating potential infectivity to avian species. Furthermore, the S mutants of real SARS-CoV-2 variants comprising N501Y showed significantly acquired abilities to infect cells expressing mouse ACE2, indicating a critical role of N501Y in expanding SARS-CoV-2 host range. In addition, A262S and T478I significantly enhanced the utilization of various mammals ACE2. In summary, our results indicated that T478I and N501Y substitutions were two S mutations important for receptor adaption of SARS-CoV-2, potentially contributing to the spillover of the virus to many other animal hosts. Therefore, more attention should be paid to SARS-CoV-2 variants with these two mutations.

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Robotic lateral oropharyngectomy following diagnostic tonsillectomy is oncologically safe in patients with human papillomavirus‐related squamous cell cancer: Long‐term results

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Abstract

Introduction

To report the long-term oncological and functional outcomes of en bloc TORS lateral oropharyngectomy to address the close/involved margin following diagnostic tonsillectomy in HPV-related SCC of unknown primary.

Material and methods

A single tertiary center observational cohort over a 4-year period. Primary outcome measures were disease-specific survival (DSS), overall survival (OS), and PSS NOD (Performance Status Scale-Normalcy of Diet) scores.

Results

TORS specimens did not evidence residual carcinoma in 93% of patients. Of 14 patients, 50% received surgery alone (median follow-up 57 months; range 46–96), the remainder surgery and adjuvant therapy (median follow-up of 58 months; range 51–69) with 100% DSS, OS and no deterioration of PSS NOD scores.

Conclusions

Long-term oncological outcomes confirm TORS lateral oropharyngectomy alone is an oncologically safe treatment. Due consideration of this approach is warranted to mitigate against the morbidity of adjuvant radiotherapy treatment in this group of patients.
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Should Linezolid Replace Clindamycin as the Adjunctive Antimicrobial of Choice in Group A Streptococcal Necrotizing Soft Tissue Infection and Toxic Shock Syndrome? A Focused Debate

alexandrossfakianakis shared this article with you from Inoreader

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Abstract
Group A Streptococcus (GAS) necrotizing soft tissue infections and toxic shock syndrome remain high-mortality conditions. In vitro and animal model data, as well as multiple observational studies, suggest adjunctive clindamycin (i.e., given with a beta-lactam) reduces invasive GAS infection mortality by inhibiting exotoxin production. Unfortunately, clindamycin resistance in GAS has been rapidly increasing in the United States (US) since the mid-2010s, though the clinical significance of this remains unclear. Linezolid is a promising alternative adjunctive agent to which US GAS isolates remain near-universally susceptible, with a similar mechanism of action and similar in vitro evidence of GAS virulence factor attenuation. However, the clinical data supporting linezolid's value in severe GAS infections are far more limited. Here, the authors review the data and reasoning behind a general preference for clindamycin or linezolid in a focused, pro-con debate format.
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Estimating Waning of Vaccine Effectiveness: a Simulation Study

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Abstract
Background
Developing accurate and reliable methods to estimate vaccine protection is a key goal in immunology and public health. While several statistical methods have been proposed, their potential inaccuracy in capturing fast intra-seasonal waning of vaccine-induced protection needs to be rigorously investigated.
Methods
To compare statistical methods for vaccine effectiveness (VE) estimation, we generated simulated data using a multiscale agent-base d model of an epidemic with an acute viral infection and differing extents of VE waning. We apply a previously proposed framework for VE measures based on the observational data richness to assess changes of vaccine-induced protection over time.
Results
While VE measures based on hard-to-collect information (e.g. the exact timing of exposures) were accurate, usually VE studies rely on time-to-infection data and the Cox proportional hazard model. We found that its extension utilizing scaled Schoenfeld residuals, previously proposed for capturing VE waning, was unreliable in capturing both the degree of waning and its functional form and identified the mathematical factors contributing to this unreliability. We showed that partitioning time and including a time-vaccine interaction term in the Cox model significantly improved estimation of VE waning, even in the case of dramatic, rapid waning. We also proposed how to optimize the partitioning scheme.
Conclusions
While appropriate for rejecting the null hypothesis of no waning, scaled Schoenfeld residuals are unreliable for estimating the degree of waning. We propose a Cox-model-based method with a time-vaccine interaction term and further optimization of partitioning time. These findings may guide future analysis of VE waning data.
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Native and activated antithrombin inhibits TMPRSS2 activity and SARS‐CoV‐2 infection

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Abstract

Host cell proteases such as TMPRSS2 are critical determinants of SARS-CoV-2 tropism and pathogenesis. Here, we show that antithrombin (AT), an endogenous serine protease inhibitor regulating coagulation, is a broad-spectrum inhibitor of coronavirus infection. Molecular docking and enzyme activity assays demonstrate that AT binds and inhibits TMPRSS2, a serine protease that primes the Spike proteins of coronaviruses for subsequent fusion. Consequently, AT blocks entry driven by the Spikes of SARS-CoV, MERS-CoV, hCoV-229E, SARS-CoV-2 and its variants of concern including Omicron, and suppresses lung cell infection with genuine SARS-CoV-2. Thus, AT is an endogenous inhibitor of SARS-CoV-2 that may be involved in COVID-19 pathogenesis. We further demonstrate that activation of AT by anticoagulants, such as heparin or fondaparinux, increases the anti-TMPRSS2 and anti-SARS-CoV-2 activity of AT, suggesting that repurposing of native and activated AT for COVID-19 tr eatment should be explored.

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COVID‐19 immunopathology: From acute diseases to chronic sequelae

alexandrossfakianakis shared this article with you from Inoreader

ABSTRACT

The clinical manifestation of COVID-19 mainly targets the lung as a primary affected organ, which is also a critical site of immune cells activation by SARS-CoV-2. However, recent reports also suggest the involvement of extrapulmonary tissues in COVID-19 pathology. The interplay of both innate and adaptive immune responses is key to COVID-19 management. As a result, a robust innate immune response provides the first line of defense, concomitantly, adaptive immunity neutralizes the infection and builds memory for long-term protection. However, dysregulated immunity, both innate and adaptive, can skew towards immunopathology both in acute and chronic cases. Here we have summarized some of the recent findings that provide critical insight into the immunopathology caused by SARS-CoV-2, in acute and post-acute cases. Finally, we further discuss some of the immunomodulatory drugs in preclinical and clinical trials for dampening the immunopathology caused by COVID- 19.

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WHOLE GENOME SEQUENCING OF SARS‐CoV‐2: COMPARISON OF TARGET CAPTURE AND AMPLICON SINGLE MOLECULAR REAL TIME SEQUENCING PROTOCOLS

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ABSTRACT

Fast, accurate sequencing methods are needed to identify new variants and genetic mutations of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) genome. Single Molecular Real Time (SMRT) Pacific Biosciences (PacBio) provides long, highly accurate sequences by circular consensus reads. This study compares the performance of a target capture SMRT Pacbio protocol for whole genome sequencing (WGS) of SARS-CoV-2 to that of an amplicon Pacbio SMRT sequencing protocol. The median genome coverage was higher (p<0.05) with the target capture protocol (99.3% [IQR: 96.3-99.5]) than with the amplicon protocol (99.3% [IQR :69.9-99.3]). The clades of 65 samples determined with both protocols were 100% concordant. After adjusting for Ct values, S gene coverage was higher with the target capture protocol than with the amplicon protocol. After stratification on Ct values, higher S gene coverage with the target capture protocol was observed only for samples w ith Ct>17 (p<0.01). Pacbio SMRT sequencing protocols appears to be suitable for WGS, genotyping and detecting mutations of SARS-CoV-2.

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Translucency, color stability, and biaxial flexural strength of advanced lithium disilicate ceramic after coffee thermocycling

alexandrossfakianakis shared this article with you from Inoreader

Abstract

Objective

To compare the color stability, translucency, and biaxial flexural strength (BFS) of differently glazed advanced lithium disilicate (ALDS) with those of lithium disilicate (LDS) and zirconia-reinforced lithium silicate (ZLS) after coffee thermocycling.

Materials and methods

Forty disk-shaped specimens were prepared from three lithium silicate based materials (CEREC Tessera, ALDS; IPS e.max CAD, LDS; Vita Suprinity, ZLS). ALDS specimens were divided into two subgroups according to glazing procedures (reduced glaze duration, ALDS-S and normal glaze duration, ALDS-N), while LDS and ZLS specimens were crystallized and glazed. Color coordinate measurements were performed before and after coffee thermocycling. Color differences (ΔE 00) and relative translucency parameters (RTP) were calculated. Specimens were then subjected to BFS test. Statistical analysis was performed by using 1- (ΔE 00 and BFS) and 2-way (RTP) ANOVA tests (α = 0.05).

Results

ΔE 00 values of tested materials were similar (df = 3, F = 0.150, p = 0.929). Two-way ANOVA showed the significant effect of material type, coffee thermocycling, and the interaction between these parameters on RTP values (p < 0.001). Both before and after thermocycling, LDS had the highest (p ≤ 0.001) and ZLS had the lowest (p < 0.001) RTP values, while ALDS-N had higher RTP than ALDS-S (p ≤ 0.001). Among tested materials, only LDS had similar RTP values before and after thermocycling (p = 0.865) as the other materials had lower RTP values after thermocycling (p < 0.001). ALDS-N had higher BFS values than ALDS-S (p = 0.005), while LDS had similar values to ALDS specimens (p ≥ 0.201). ZLS had the highest BFS (p ≤ 0.007).

Conclusions

ALDS had comparable values to those of other materials. However, reduced glazing duration resulted in decreased translucency and BFS of ALDS.

Clinical significance

ALDS may be an appropriate restorative material for those patients with increased coffee consumption considering its color stability and ability to maintain translucency, particularly when glazed by using a conventional porcelain furnace.
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