Αρχειοθήκη ιστολογίου

Αλέξανδρος Γ. Σφακιανάκης
ΩτοΡινοΛαρυγγολόγος
Αναπαύσεως 5
Άγιος Νικόλαος Κρήτη 72100
2841026182
6032607174

Τρίτη 19 Ιουλίου 2022

Differential avidity determination of IgG directed towards the receptor‐binding domain (RBD) of SARS‐CoV‐2 wildtype and its variants in one assay: Rational tool for the assessment of protective immunity.

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Abstract

The avidity (binding strength) of IgG directed towards the receptor-binding domain (RBD) of spike protein has been recognized as a central marker in SARS-CoV-2 serology. It seems to be linked to increased infection-neutralization potential and therefore might indicate protective immunity. Using a prototype line assay based on the established recomLine SARS-CoV-2 assay, supplemented with RBD of the delta and the omicron variant, differential avidity determination of IgG directed towards RBD of wild-type (WT) SARS-CoV-2 and distinct variants was possible within one assay. Our data confirm that natural SARS-CoV-2 infection or one vaccination step lead to low avidity IgG, whereas further vaccination steps gradually increase avidity to high values. High avidity is not reached by infection alone. After infection with WT SARS-CoV-2 or vaccination based on mRNA WT, the avidity of cross-reacting IgG directed towards RBD of the delta variant only showed marginal diffe rences compared to IgG directed towards RBD WT. In contrast, the avidity of IgG cross-reacting with RBD of the omicron variant was always much lower than for IgG RBD WT, except after the third vaccination step. Therefore, parallel avidity testing of RBD WT and omicron seems to be mandatory for a significant assessment of protective immunity towards SARS-CoV-2.

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New insight on the role of Helicobacter pylori cagA in the expression of cell surface antigens with important biological functions in gastric carcinogenesis

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Abstract

Background

Expression of cluster of differentiation (CD) antigens changes according to disease status and inflammation. Profiles of CD antigens expression in gastric cancer patients are different based on the status of H. pylori infection.

Aims

We conducted this study to profile CD antigen markers in gastric adenocarcinoma cells (AGS cell line) infected with distinct cytotoxin-associated gene A (cagA) genotypes of H. pylori clinical isolates.

Methods

The AGS cells were infected with H. pylori isolates with different cagA genotypes, and CD antigens expression was determined using DotScan™ antibody microarray. Formation of "hummingbird" phenotype was determined, and the percentage was calculated.

Results

H. pylori strains harboring cagA upregulated the expression of CD antigen involved in cancer stem cell formation (CD55), but downregulated CD antigens involved in immune regulation (CD40 and CD186) and cell adhesion (CD44). CD54 (neutrophil adhesion) and CD71 (iron transfer) were highly downregulated in the gastric cells infected with Western cagA isolates compared with East Asian isolates. CD antigen expression was different in the cells infected with H. pylori harboring different CagA EPIYA (Glu-Pro-Ile-Tyr-Ala) numbers, in which higher repression of CD54 and CD15 (Lewis x antigen) were observed in the isolate with the highest number of EPIYA motif. Furthermore, higher downregulation of CD15 was observed in the infected gastric cells with high percentage of "hummingbird" phenotype than that of low percentage of "hummingbird" phenotype.

Conclusion

Our study demonstrated the critical roles of CD antigens in the CagA pathogenesis and should be investigated further.

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Comparative study of DFAT cell and ADSC sheets for periodontal tissue regeneration:in vivo and in vitro evidence

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Abstract

Aim

To compare the efficacy of adipocyte-derived dedifferentiated fat (DFAT) cell and adipose-derived stromal cell (ADSC) sheets for regenerative treatment of intrabony periodontal defects.

Material and Methods

DFAT cells were obtained using the ceiling culture method and were compared with ADSCs using Cell Counting Kit-8 (CCK8), colony formation assay, surface antigen identification, and multilineage differentiation assays. DFAT and ADSC sheets were prepared in cell sheet culture medium. The biological characteristics of DFAT cell and ADSC sheets were compared using haematoxylin and eosin staining, quantitative reverse transcription PCR, and immunofluorescence staining. Micro-computed tomography and histological staining were used to compare the effects of the two cell sheets on the repair of periodontal intrabony defects in rats.

Results

DFAT cells and ADSCs demonstrated mesenchymal stem cell characteristics. Both cell type were CD29-, CD90-, and CD146-positive and CD31-, CD34-, and CD45-negative. DFAT cells and ADSCs exhibited similar osteogenic and adipogenic differentiation capabilities, and colony-formation ability. DFAT cells displayed stronger proliferation capabilities compared to ADSCs. Compared with the ADSC sheets, DFAT cell sheets exhibited a higher expression of periodontal-related genes and proteins and greater ability to regenerate periodontal tissue.

Conclusion

Our findings suggest that DFAT cell sheets are an ideal seed cell source and form of cell delivery for periodontal intrabony defects.

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The accuracies of three intraoral scanners with regards to shade determination: An in vitro study

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Abstract

Purpose

: To compare the accuracy of three intraoral scanners for shade determination function in vitro, and to preliminarily investigate the shade-matching characteristics of the three intraoral scanners.

Materials & Methods

The shade of the middle third region of each shade tab on the Vita Classical A1-D4 shade guide (VC) was measured by a spectrophotometer (Vita Easyshade V, VE) and three intraoral scanners, including CEREC Omnicam (OM), 3Shape TRIOS 3 (T3), and TRIOS 4 (T4). A conversion table between VC values and CIELAB values was established from the database of VE to analyze the trueness. The reproducibility of the instruments was then compared by repeating the measurements five times.

Results

: The mean color difference for each instrument was highest in the OM, followed by the T4, and lowest in the T3 and VE, repectively. The L* and a* value for OM, and the b* value for T4, were significantly different from those for VE (p <0.05). The reproducibility of the instrument was highest in the VE (Fleiss' kappa: 0.95), followed by the T3 (Fleiss' kappa: 0.89), T4 (Fleiss' kappa: 0.87), and OM (Fleiss' kappa: 0.78).

Conclusions

: Of the three intraoral scanners, the trueness was best on the T3. The reproducibility of all the instruments was excellent.

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TREM2‐induced activation of microglia contributes to synaptic integrity in cognitively intact aged individuals with Alzheimer's neuropathology

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TREM2-induced activation of microglia contributes to synaptic integrity in cognitively intact aged individuals with Alzheimer's neuropathology

Efficient TREM2-phagocytic microglia underlie synaptic resilience in NDAN, removing damaged synpases, contributing to synaptic integrity and protecting from memory deficits.


Abstract

The existence of individuals who remain cognitively intact despite presenting histopathological signs of Alzheimer's disease (AD), here referred to as "Nondemented with AD neuropathology" (NDAN), suggests that some mechanisms are triggered to resist cognitive impairment. Exposed phosphatidylserine (ePS) represents a neuronal "eat-me" signal involved in microglial-mediated phagocytosis of damaged synapses. A possible mediator of this process is TREM2, a microglial surface receptor activated by ligands including PS. Based on TREM2 role in the scavenging function of microglia, we hypothesize that an efficient microglial phagocytosis of damaged synapses underlies synaptic resilience in NDAN, thus protecting from memory deficits. Using immunofluorescence microscopy, we performed a comparative study of human post-mortem frontal cortices of aged-matched, AD and NDAN individuals. We studied the distribution of activated microglia (IBA1, IBA1+/CD68+ cells) and phagocytic microglia-related proteins (TREM2, DAP12), demonstrating higher microglial activation and TREM2 expression in NDAN versus AD. A study of the preservation of synapses around plaques, assessed using MAP2 and βIII tubulin as dendritic and axonal markers, respectively, and PSD95 as a postsynaptic marker, revealed preserved axonal/dendritic structure around plaques in NDAN versus AD. Moreover, high levels of PSD95 around NDAN plaques and the colocalization of PSD95 with CD68 indicated a prompt removal of damaged synapses by phagocytic microglia. Furthermore, Annexin V assay on aged-matched, AD and NDAN individuals synaptosomes revealed increased levels of ePS in NDAN, confirming damaged synapses engulfment. Our results suggest a higher efficiency of TREM2-induced phagocytic microglia in removing damaged synapses, underlying synaptic resilience in NDAN individuals.

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Early marginal bone loss around dental implants to define success in implant dentistry: A retrospective study

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Abstract

Purpose

The aim of this study was to establish an objective criterion in terms of marginal bone level (MBL) to know the prognosis of an implant.

Materials and Methods

A group of 176 patients in whom 590 implants were placed were included in this retrospective study. Patients older than 18 years, presenting either Kennedy class I or II edentulous section, or totally edentulous at least in one of the dental arches were included in this study. Those with any type of disturbance able to alter bone metabolism or with nontreated periodontal disease were excluded. Data on radiographic MBL at loading, 6 and 18 months later, age, gender, smoking habits, history of periodontitis, bone substratum, implant, and prosthetic features were recorded. Nonparametric receiver operating curves (ROC) were constructed for the MBL at 18 months in order to establish a distinction among high bone loser (HBL) and low bone loser (LBL) implants. Differences as a function of main variables were also determined, particularly abutment height and periodontal disease.

Results

HBL implants lost at least 0.48 mm of MBL 6 months after loading; they reached at least 2 mm of MBL 18 months after loading. MBL rate followed a nonlinear trend, except in implants restored over long prosthetic abutments and in patients with history of severe periodontitis; in whom the rate of MBL over the time was nearly zero.

Conclusion

Implants that lose more than 0.5 mm of marginal bone 6 months after loading are at great risk of not being radiographically successful anymore. Therefore, 0.5 mm of MBL is proposed as a distinctive and objective criterion of success in Implant Dentistry within a 6-month follow-up period. A prosthetic abutment height ≥2 mm resulted the most protective factor in the peri-implant bone maintenance.

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Comparative Evaluation of the Antibacterial Effect of Allium Sativum, Calcium hydroxide and Their Combination as Intracanal Medicaments in Infected Mature Anterior Teeth A Randomized Clinical Trial

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Abstract

Aim

The purpose of this study was to compare the antibacterial effects of Allium Sativum (garlic extract), calcium hydroxide (Ca (OH)2), and their combination as intracanal medicaments in infected mature anterior teeth using real-time PCR.

Material& Methods

This prospective double-blind, controlled, parallel, superiority, randomized clinical trial was carried out on sixty-six permanent, necrotic incisors associated with asymptomatic apical periodontitis in sixty-six male patients. Patients were randomly divided into three groups (n =22) according to the intra -canal medications used. After access preparation, four microbiological samples (S) were taken using sterile absorbent paper points as follows: S1: before canal instrumentation. S2: after cleaning and shaping. The third samples (S3) and fourth samples (S4) were taken after the placement of the tested intracanal medications into their corresponding canals for 7 and 14 days, respectively. Total DNA was extracted from microbiological samples and relative quantitative real time PCR reactions were done to quantify the relative gene expression fold change (FC) for Enterococcus faecalis and Streptococcus species. At significance level p ≤ 0.05, the data were statist ically analyzed in SPSS software using Kruskal-Wallis and Freidman's tests, followed by Dunn-Bonferroni post-hoc test for pairwise comparisons.

Results

Both bacterial mean FC decreased significantly after mechanical instrumentation (S1 to S2) in all groups. However, no statistically significant differences were found after intra-canal medicament placement (from S2 to S3 and from S3 to S4) except in the garlic group. Garlic significantly reduced Enterococcus faecalis FC in S3 and S4 when compared to Ca (OH) 2 and Ca (OH) 2+ garlic combination. However, garlic and Ca (OH)2 reduced Streptococcus bacteria in S3 similarly. While in S4, garlic showed significantly more reduction than Ca (OH) 2. The combination of Ca (OH) 2 with garlic extract showed the least significant bacterial reduction.

Conclusion

within the study limitations, garlic intra-canal medicament has a comparable anti-Streptococcus efficiency to Ca (OH) 2, while it is more effective against Enterococcus faecalis species. When Ca (OH)2 and garlic are combined, their antibacterial effectiveness is reduced. Increasing the time of application for tested intracanal medicaments by more than one week has no additional antibacterial effectiveness.

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Increased sensitivity of Aggregatibacter actinomycetemcomitans to human serum is mediated by induction of a bacteriophage

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Summary

Aggregatibacter actinomycetemcomitans, a Gram-negative oral pathobiont causing aggressive periodontitis and systemic infections demonstrates serum resistance. We have identified a dsDNA tailed bacteriophage S1249, which was found from this microorganism inducible by human serum to convert into lytic state to kill the bacterium. This phage demonstrated active transcripts when exposed to human serum: 20% of genes were up regulated greater than 10 folds and 45% of them were up regulated 5–10 folds, when the bacterium was grown in the presence of human serum compared to without. Transcriptional activation when grown in equine serum was less pronounced. This phage demonstrated a tail with the inner rigid tubes and outer contractile sheath, features of Myoviridae spp. Further characterization revealed that the lysogenized integration of the phage in the chromosome of A. actinomycetemcomitans occurred between the genes encoding for cold-shock DNA-binding domain-con taining protein (csp) and glutamyl-tRNA synthetase (gltX). Both phage DNA integrated lysogeny and non-integrated pseudolysogeny were identified in the infected bacterium. A newly generated, lysogenized strain using this phage displayed similar attributes, including 63% growth inhibition compared to its isogenic phage-free strain when in the presence of human serum. Our data suggest that bacteriophage S1249 can be induced in the presence of human serum and enters the lytic cycle, which reduces the viability of infected bacteria in vivo.

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The malignant property of circHIPK2 for angiogenesis and chemoresistance in non-small cell lung cancer

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Publication date: Available online 19 July 2022

Source: Experimental Cell Research

Author(s): Mingming Ren, Xiang Song, Jieting Niu, Guojie Tang, Zhen Sun, Yanguang Li, Fanyi Kong

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Orthopedic Surgery Causes Gut Microbiome Dysbiosis and Intestinal Barrier Dysfunction in Prodromal Alzheimer Disease Patients: A Prospective Observational Cohort Study

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imageObjective: To investigate gut microbiota and intestinal barrier function changes after orthopedic surgery in elderly patients with either normal cognition (NC) or a prodromal Alzheimer disease phenotype (pAD) comprising either subjective cognitive decline (SCD) or amnestic mild cognitive impairment (aMCI). Background: Homeostatic disturbances induced by surgical trauma and/or stress can potentially alter the gut microbiota and intestinal barrier function in elderly patients before and after orthopedic surgery. Methods: In this prospective cohort study, 135 patients were subject to preoperative neuropsychological assessment and then classified into: NC (n=40), SCD (n=58), or aMCI (n=37). Their gut microbiota, bacterial endotoxin (lipopolysaccharide), tight junction (TJ) protein, and inflammatory cytokines in blood were measured before surgery and on postsurgical day 1, 3, and 7 (or before discharge). Results: The short-chain fatty acid (SCFA)-producing bacteria were lower while the gram-negative bacteria, lipopolysaccharide and TJ were higher preoperatively in both the SCD and aMCI (pAD) groups compared with the NC group. After surgery, a decrease in SCFA-producing bacteria, and an increase in both gram-negative bacteria and plasma claudin were significant in the pAD groups relative to the NC group. SCFA-producing bacteria were negatively correlated with TJ and cytokines in pAD patients on postsurgical day 7. Furthermore, surgery-induced perioperative metabolic stress and inflammatory responses were associated with gut microbiota alterations. Conclusions: Surgery exacerbates both preexisting microbiota dysbiosis and intestinal barrier dysfunction in pAD patients, all of which may be associated with systemic inflammation and, in turn, may lead to further cognitive deterioration.
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