Ferristatin II Efficiently Inhibits SARS-CoV-2 Replication in Vero Cells

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continues to have a significant impact on global public health. Multiple mechanisms for SARS-CoV-2 cell entry have been described; however, the role of transferrin receptor 1 (TfR1) in SARS-CoV-2 infection has received little attention. We used ferristatin II to induce the degradation of TfR1 on the surface of Vero cells and to study the consequences of such treatment on the viability of the cells and the replication of SARS-CoV-2. We demonstrated that ferristatin II is non-toxic for Vero cells in concentrations up to 400 µM. According to confocal microscopy data, the distribution of the labeled transferrin and receptor-binding domain (RBD) of Spike protein is significantly affected by the 18h pretreatment with 100 µM ferristatin II in culture medium. The uptake of RBD protein is nearly fully inhibited by ferristatin II treatment, although this protein remains bound on the cell surface. The findings were well confirmed by the significant inhibition of the SARS-CoV-2 infection of Vero cells by ferristatin II with IC₅₀ values of 27 µM (for Wuhan D614G virus) and 40 µM (for Delta virus). A significant reduction in the infectious titer of the Omicron SARS-CoV-2 variant was noted at a ferristatin II concentration as low as 6.25 µM. We hypothesize that ferristatin II blocks the TfR1-mediated SARS-CoV-2 host cell entry; however, further studies are needed to elucidate the full mechanisms of this virus inhibition, including the effect of ferristatin II on other SARS-CoV-2 receptors, such as ACE2, Neuropilin-1 and CD147. The inhibition of viral entry by targeting the receptor on the host cells, rather than the viral mutation-prone protein, is a promising COVID-19 therapeutic strategy.     

Normal variation of mandibular asymmetry in children

Objective

To explore the normal variation of asymmetry in mandibles of children in the age group of 1 to 12 years.

Materials and Methods

The study group consisted of 92 cadaveric mandibles of children with a dental age of 1 to 12 years old in possession of ACTA (Academic Centre for Dentistry Amsterdam), Faculty of Dentistry, the Netherlands. 3D models of the mandibles were obtained from CT-scans and hemimandibular volumes of all mandibles were calculated. The condylar height, ramus height, mandibular body length and the gonial angle were bilaterally determined using a novel landmark-based method, and the degree of asymmetry was calculated.

Results

No relationship was found between dental age and asymmetry of the studied parameters (P < .05). The highest degree of asymmetry was found in the ramus height, whereas the gonial angle presented the lowest degree of asymmetry. A positive correlation was found between the asymmetry of the hemimandibular volume vs the height of the ramus (P < .05) and the length of the mandibular body (P < .05). An inverse correlation was found between the asymmetry of the ramus height vs the condylar height (P < .05), mandibular body length (P < .05) and gonial angle (P < .05).

Conclusions

Mandibular asymmetries in children did occur (9.8% of the included mandibles presented with a relevant overall asymmetry of ≥3%) and were unrelated to age. The different segments of the mandible seem to compensate for each other, in order to maintain a functional equilibrium.     

Frequency of daytime tooth clenching episodes in individuals affected by masticatory muscle pain and pain-free controls during standardized ability tasks

Objectives

Tooth clenching has been suggested to be related to temporomandibular pain. However, the electromyographic characteristics of daytime clenching episodes have been minimally investigated. This study aimed to analyze the frequency, amplitude, and duration of daytime clenching episodes in patients with masticatory muscle pain and pain-free individuals.

Methods

Fifteen women with masticatory muscles myalgia (MP group, mean ± SD age = 26.4 ± 7.6 years) matched for age to 18 pain-free women (CTR group, mean ± SD age = 25.3 ± 2.8 years) were submitted to three different ability tasks (filling out questionnaires for 40 min, reading for 20 min, and playing a videogame for 20 min). The electromyographic activity periods (AP) of the right masseter greater than 10 % (AP10), 20 % (AP20), and 30 % (AP30) of the maximum voluntary contraction were analyzed.

Results

The mean frequencies of AP10, AP20, and AP30 were greater in MP than in CTR individuals (all p < 0.05). The mean duration of AP10 was higher in MP group than CTR group only while filling out the questionnaires (p = 0.0033). CTR group had an increased frequency and duration of AP10 while playing the videogame than while reading a magazine. The ability tasks did not affect the muscle activity in the MP group.

Conclusions

Individuals with masticatory muscle pain have an increased frequency of both high and low-intense daytime clenching episodes. The type of ability task affects the frequency and the duration of clenching episodes only in pain-free individuals.

Clinical relevance

Clinicians should recognize that the frequency and intensity of daytime clenching are noticeably increased in individuals with masticatory muscle pain in order to better tailor treatment.

     

Can the metabolic syndrome identify children with insulin resistance?

OBJECTIVE: The metabolic syndrome is associated with insulin resistance in adults. We defined pediatric metabolic syndrome using criteria analogous to Adult Treatment Panel III. The purpose of this study was to determine whether these criteria are reliable for insulin resistance in children. RESEARCH DESIGN AND METHODS: Out of 167 children (6.7 +/- 3 yr), 73 overweight [body mass index (BMI) > 95 percentile], 41 at risk of overweight (BMI > 85 < 95 percentile), and 53 normal-weight (BMI < 85 percentile) children matched for sex and age were examined. The results for waist circumference, blood pressure, oral glucose tolerance test, C-reactive protein, adiponectin, insulin, and lipids were obtained. RESULTS: There was a comparable prevalence of the metabolic syndrome in both sexes. The prevalence of the metabolic syndrome was 11.3% [95% confidence interval (CI) 6.56-16.19%] among the whole group and 21.9% (95% CI 12.24-31.0%) among overweight children. Waist circumference >75 percentile 53.2% (95% CI 45.73-60.86%) and low high-density lipoprotein 27.5% (95% CI 20.77-34.32%) were common in this sample. Compared with patients without any component of the metabolic syndrome, homeostasis model assessment insulin resistance (HOMA-IR) for patients with one through four components was higher (beta = 0.6, 95% CI 0.4-0.7, p < 0.0001, R(2) = 0.185). A logistic regression analysis using the metabolic syndrome as the dependent variable showed that HOMA-IR (odds ratio 1.52, 95% CI 1.2-2.0, p = 0.007) was the only independent risk factor for the metabolic syndrome, adjusted for age and sex. CONCLUSIONS: The importance of insulin resistance in the metabolic syndrome is supported by the results of logistic regression analysis. Early identification of children may be useful to predict future cardiovascular disease and type 2 diabetes.     

Identification and characterization of novel rare mutations in the planar cell polarity gene PRICKLE1 in human neural tube defects

The planar cell polarity (PCP) pathway controls the process of convergent extension (CE) during gastrulation and neural tube closure, and has been implicated in the pathogenesis of neural tube defects (NTDs) in animal models and human cohorts. In this study, we analyzed the role of one core PCP gene PRICKLE1 in these malformations. We screened this gene in 810 unrelated NTD patients and identified seven rare missense heterozygous mutations that were absent in all controls analyzed and predicted to be functionally deleterious using bioinformatics. Functional validation of five PRICKLE1 variants in a zebrafish model demonstrated that one variant, p.Arg682Cys, antagonized the CE phenotype induced by the wild-type zebrafish prickle1a (zpk1a) in a dominant fashion. Our study demonstrates that PRICKLE1 could act as a predisposing factor to human NTDs and further expands our knowledge of the role of PCP genes in the pathogenesis of these malformations.     

The role of DMQ(9) in the long-lived mutant clk-1

IntroductionUbiquinone (UQ) is a redox active lipid that transfers electrons from complex I or II to complex III in the electron transport chain (ETC). The long-lived Caenorhabditis elegans mutant clk-1 is unable to synthesize its native ubiquinone, and accumulates high amounts of its precursor, 5-demethoxyubiquinone-9 (DMQ₉). In clk-1, complexes I–III activity is inhibited while complexes II–III activity is normal. We asked whether the complexes I–III defect in clk-1 was caused by: (1) a defect in the ETC; (2) an inhibitory effect of DMQ₉; or (3) a decreased amount of ubiquinone.MethodsWe extracted the endogenous quinones from wildtype (N2) and clk-1 mitochondria, replenished them with exogenous ubiquinones, and measured ETC activities.ResultsReplenishment of extracted mutant and wildtype mitochondria resulted in equal enzymatic activities for complexes I–III and II–III ETC assays. Blue native gels showed that supercomplex formation was indistinguishable between clk-1 and N2. The addition of a pentane extract from clk-1 mitochondria containing DMQ₉ to wildtype mitochondria specifically inhibited complexes I–III activity. UQ in clk-1 mitochondria was oxidized compared to N2.DiscussionOur results show that no measurable intrinsic ETC defect exists in clk-1 mitochondria. The data indicate that DMQ₉ specifically inhibits electron transfer from complex I to ubiquinone.