Thromboinflammation is the major cause of morbidity and mortality in COVID‐19 patients, and post‐mortem examination demonstrates the presence of platelet‐rich thrombi and microangiopathy in visceral ...organs. Moreover, persistent microclots were detected in both acute COVID‐19 and long COVID plasma samples. However, the molecular mechanism of SARS‐CoV‐2‐induced thromboinflammation is still unclear. We found that the spleen tyrosine kinase (Syk)‐coupled C‐type lectin member 2 (CLEC2), which was highly expressed in platelets and alveolar macrophages, interacted with the receptor‐binding domain (RBD) of SARS‐CoV‐2 spike protein (SARS‐CoV‐2 RBD) directly. Unlike the thread‐like NETs, SARS‐CoV‐2‐induced aggregated NET formation in the presence of wild‐type (WT), but not CLEC2‐deficient platelets. Furthermore, SARS‐CoV‐2 spike pseudotyped lentivirus was able to induce NET formation via CLEC2, indicating SARS‐CoV‐2 RBD engaged CLEC2 to activate platelets to enhance NET formation. Administration of CLEC2.Fc inhibited SARS‐CoV‐2‐induced NET formation and thromboinflammation in AAV‐ACE2‐infected mice. Thus, CLEC2 is a novel pattern recognition receptor for SARS‐CoV‐2, and CLEC2.Fc and may become a promising therapeutic agent to inhibit SARS‐CoV‐2‐induced thromboinflammation and reduced the risk of post‐acute sequelae of COVID‐19 (PASC) in the future.
Synopsis
CLEC2 interacts with SARS‐CoV‐2 spike RBD and is critical for SARS‐CoV‐2‐induced lung injury. In the presence of platelets, SARS‐CoV‐2 induces robust NET formation and cytokine release, while administration of CLEC2.Fc prevents platelet‐mediated enhancement of NET formation and cytokine storm via blocking interactions between CLEC2 and SARS‐CoV‐2 spike protein.
CLEC2 interacts with SARS‐CoV‐2 Spike RBD of wild type, alpha, beta, gamma, delta, and omicron, but not with SARS‐CoV Spike RBD.
SARS‐CoV‐2 Spike RBD activates platelet via CLEC2 inducing aggregated NET formation.
SARS‐CoV‐2 upregulates the expression of podoplanin in the lungs after infection.
Recombinant CLEC2.Fc inhibits SARS‐CoV‐2‐induced thromboinflammation in the lungs and heart.
Recombinant CLEC2.Fc attenuates SARS‐CoV‐2‐induced NET formation and collagen deposition in the lungs.
CLEC2 interacts with SARS‐CoV‐2 spike RBD and is critical for SARS‐CoV‐2‐induced lung injury. In the presence of platelets, SARS‐CoV‐2 induces robust NET formation and cytokine release, while administration of CLEC2.Fc prevents platelet‐mediated enhancement of NET formation and cytokine storm via blocking interactions between CLEC2 and SARS‐CoV‐2 spike protein.
The novel coronavirus disease (COVID-19) pandemic remains a global public health crisis, presenting a broad range of challenges. To help address some of the main problems, the scientific community ...has designed vaccines, diagnostic tools and therapeutics for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. The rapid pace of technology development, especially with regard to vaccines, represents a stunning and historic scientific achievement. Nevertheless, many challenges remain to be overcome, such as improving vaccine and drug treatment efficacies for emergent mutant strains of SARS-CoV-2. Outbreaks of more infectious variants continue to diminish the utility of available vaccines and drugs. Thus, the effectiveness of vaccines and drugs against the most current variants is a primary consideration in the continual analyses of clinical data that supports updated regulatory decisions. The first two vaccines granted Emergency Use Authorizations (EUAs), BNT162b2 and mRNA-1273, still show more than 60% protection efficacy against the most widespread current SARS-CoV-2 variant, Omicron. This variant carries more than 30 mutations in the spike protein, which has largely abrogated the neutralizing effects of therapeutic antibodies. Fortunately, some neutralizing antibodies and antiviral COVID-19 drugs treatments have shown continued clinical benefits. In this review, we provide a framework for understanding the ongoing development efforts for different types of vaccines and therapeutics, including small molecule and antibody drugs. The ripple effects of newly emergent variants, including updates to vaccines and drug repurposing efforts, are summarized. In addition, we summarize the clinical trials supporting the development and distribution of vaccines, small molecule drugs, and therapeutic antibodies with broad-spectrum activity against SARS-CoV-2 strains.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Abstract
Background
Coronavirus-induced disease 19 (COVID-19) infects more than three hundred and sixty million patients worldwide, and people with severe symptoms frequently die of acute respiratory ...distress syndrome (ARDS). Recent studies indicated that excessive neutrophil extracellular traps (NETs) contributed to immunothrombosis, thereby leading to extensive intravascular coagulopathy and multiple organ dysfunction. Thus, understanding the mechanism of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-induced NET formation would be helpful to reduce thrombosis and prevent ARDS in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection.
Methods
We incubated SARS-CoV-2 with neutrophils in the presence or absence of platelets to observe NET formation. We further isolated extracellular vesicles from COVID-19 patients' sera (COVID-19-EVs) to examine their ability to induce NET formation.
Results
We demonstrated that antagonistic mAbs against anti-CLEC5A mAb and anti-TLR2 mAb can inhibit COVID-19-EVs-induced NET formation, and generated
clec5a
−/−
/tlr2
−/−
mice to confirm the critical roles of CLEC5A and TLR2 in SARS-CoV-2-induced lung inflammation in vivo. We found that virus-free extracellular COVID-19 EVs induced robust NET formation via Syk-coupled C-type lectin member 5A (CLEC5A) and TLR2. Blockade of CLEC5A inhibited COVID-19 EVs-induced NETosis, and simultaneous blockade of CLEC5A and TLR2 further suppressed SARS-CoV-2-induced NETosis in vitro. Moreover, thromboinflammation was attenuated dramatically in
clec5a
−/−
/tlr2
−/−
mice.
Conclusions
This study demonstrates that SARS-CoV-2-activated platelets produce EVs to enhance thromboinflammation via CLEC5A and TLR2, and highlight the importance of CLEC5A and TLR2 as therapeutic targets to reduce the risk of ARDS in COVID-19 patients.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Joints and fissures with similar orientation or characteristics are common in natural rocks; the inclination and density of the fissures affect the mechanical properties and failure mechanism of the ...rock mass. However, the strength, crack coalescence pattern, and failure mode of rock specimens containing multi-fissures have not been studied comprehensively. In this paper, combining similar material testing and discrete element numerical method (PFC2D), the peak strength and failure characteristics of rock-like materials with multi-fissures are explored. Rock-like specimens were made of cement and sand and pre-existing fissures created by inserting steel shims into cement mortar paste and removing them during curing. The peak strength of multi-fissure specimens depends on the fissure angle
α
(which is measured counterclockwise from horizontal) and fissure number (
N
f
). Under uniaxial compressional loading, the peak strength increased with increasing
α
. The material strength was lowest for
α
= 25°, and highest for
α
= 90°. The influence of
N
f
on the peak strength depended on
α
. For
α
= 25° and 45°,
N
f
had a strong effect on the peak strength, while for higher
α
values, especially for the 90° sample, there were no obvious changes in peak strength with different
N
f
. Under uniaxial compression, the coalescence modes between the fissures can be classified into three categories: S-mode, T-mode, and M-mode. Moreover, the failure mode can be classified into four categories: mixed failure, shear failure, stepped path failure, and intact failure. The failure mode of the specimen depends on
α
and
N
f
. The peak strength and failure modes in the numerically simulated and experimental results are in good agreement.
The COVID-19 pandemic presents an unprecedented challenge to global public health. Rapid development and deployment of safe and effective vaccines are imperative to control the pandemic. In the ...current study, we applied our adjuvanted stable prefusion SARS-CoV-2 spike (S-2P)-based vaccine, MVC-COV1901, to hamster models to demonstrate immunogenicity and protection from virus challenge. Golden Syrian hamsters immunized intramuscularly with two injections of 1 µg or 5 µg of S-2P adjuvanted with CpG 1018 and aluminum hydroxide (alum) were challenged intranasally with SARS-CoV-2. Prior to virus challenge, the vaccine induced high levels of neutralizing antibodies with 10,000-fold higher IgG level and an average of 50-fold higher pseudovirus neutralizing titers in either dose groups than vehicle or adjuvant control groups. Six days after infection, vaccinated hamsters did not display any weight loss associated with infection and had significantly reduced lung pathology and most importantly, lung viral load levels were reduced to lower than detection limit compared to unvaccinated animals. Vaccination with either 1 μg or 5 μg of adjuvanted S-2P produced comparable immunogenicity and protection from infection. This study builds upon our previous results to support the clinical development of MVC-COV1901 as a safe, highly immunogenic, and protective COVID-19 vaccine.
Abstract The surrounding rock stability is a main difficult problem in the hydropower station construction and operation. Taking one hydropower station as object, FLAC 3D numerical simulation ...software was used to calculate the changes in surrounding rock failure zone distribution, surrounding rock strain, and block safety factor before and after supporting. The stability of the surrounding rock after excavation was analyzed and effect of the supporting structure was also evaluated. Finding that: the supporting structure can effectively improve the stability of surrounding rock. After supporting, the failure zone range, the deformation of surrounding rock, and the internal force of the supporting structure all reduced, while the safety factor of the block improved. Due to the effect of bolt, the deformation of the surrounding rock transformed from plastic to elastic, and the rebound zone of the surrounding rock increased, while the plastic and failure zone reduced. The depth of the failure zone on the downstream side is greater than that on the upstream side, and a large number of cracking zones are distributed on the downstream side. At the same time, due to the influence of cracks and geological fracture, the failure of surrounding rock around the main powerhouse is higher than that around the tailgate chamber higher than that in the main transformer chamber. The safety factor of the key blocks distributed around the main transformer chamber and the main power house improved, the sliding form of some blocks transformed from collapse to single-surface sliding.
Background and Aims
PreS mutants of HBV have been reported to be associated with HCC. We conducted a longitudinal study of the role of HBV preS mutations in the development of HCC, particularly in ...patients with chronic hepatitis B (CHB) having low HBV DNA or alanine aminotransferase (ALT) levels, and investigated the effects of secretion‐defective preS2 deletion mutant (preS2ΔMT) on hepatocyte damage in vitro and liver fibrosis in vivo.
Approach and Results
Association of preS mutations with HCC in 343 patients with CHB was evaluated by a retrospective case–control follow‐up study. Effects of preS2ΔMT on HBsAg retention, endoplasmic reticulum (ER) stress, calcium accumulation, mitochondrial dysfunction, and liver fibrosis were examined. Multivariate analysis revealed a significant association of preS mutations with HCC (HR, 3.210; 95% CI, 1.072‐9.613; P = 0.037) including cases with low HBV DNA or ALT levels (HR, 2.790; 95% CI, 1.133‐6.873; P = 0.026). Antiviral therapy reduced HCC risk, including cases with preS mutations. PreS2ΔMT expression promoted HBsAg retention in the ER and unfolded protein response (UPR). Transmission electron microscopic examination, MitoTracker staining, real‐time ATP assay, and calcium staining of preS2ΔMT‐expressing cells revealed aberrant ER and mitochondrial ultrastructure, reduction of mitochondrial membrane potential and ATP production, and calcium overload. Serum HBV secretion levels were ~100‐fold lower in preS2ΔMT‐infected humanized Fah–/–/ Rag2–/–/Il2rg–/– triple knockout mice than in wild‐type HBV‐infected mice. PreS2ΔMT‐infected mice displayed up‐regulation of UPR and caspase‐3 and enhanced liver fibrosis.
Conclusions
PreS mutations were significantly associated with HCC development in patients with CHB, including those with low HBV DNA or ALT levels. Antiviral therapy reduced HCC occurrence in patients with CHB, including those with preS mutations. Intracellular accumulation of mutated HBsAg induced or promoted ER stress, calcium overload, mitochondrial dysfunction, impaired energy metabolism, liver fibrosis, and HCC.
Hinokitiol is a tropolone-related compound isolated from the heartwood of cupressaceous plants. It is known to exhibit various biological functions including antibacterial, antifungal, and ...antioxidant activities. In the study, we investigated the antitumor activities of hinokitiol against human osteosarcoma cells. The results revealed that hinokitiol treatment inhibited cell viability of human osteosarcoma U-2 OS and MG-63 cells in the MTT assay. Further study revealed that hinokitiol exposure caused cell cycle arrest at the S phase and a DNA damage response with the induction of γ-H2AX foci in both osteosarcoma cell lines. In U-2 OS cells with wild-type tumor suppressor p53, we found that hinokitiol exposure induced p53 expression and cellular senescence, and knockdown of p53 suppressed the senescence. However, in MG-63 cells with mutated p53, a high percentage of cells underwent apoptosis with cleaved-PARP expression and Annexin V staining after hinokitiol treatment. In addition, up-regulated autophagy was observed both in hinokitiol-exposed U-2 OS and MG-63 cells. As the autophagy was suppressed through the autophagy inhibitor chloroquine, hinokitiol-induced senescence in U-2 OS cells was significantly enhanced accompanying more abundant p53 expression. In MG-63 cells, co-treatment of chloroquine increased hinokitiol-induced apoptosis and decreased cell viability of the treated cells. Our data revealed that hinokitiol treatment could result in different cell responses, senescence or apoptosis in osteosarcoma cell lines, and suppression of autophagy could promote these effects. We hypothesize that the analysis of p53 status and co-administration of autophagy inhibitors might provide more precise and efficacious therapies in hinokitiol-related trials for treating osteosarcoma.
Abstract
Background
This study aims to determine whether nail size or the difference between canal and nail diameter (CN difference) affects the union rate and time of femoral shaft fracture treated ...with an interlocking intramedullary nail (IMN).
Methods
This was a retrospective review of 257 patients with femoral shaft fractures treated with IMN at a tertiary trauma medical center. All the IMN inserted were the same (Stryker T2 Femoral Nail). The patients were divided into groups based on nail size (10-, 11-, 12-, or 13-mm) and CN difference (< 1, 1–2, or > 2 mm), and union rate and time to union were compared.
Results
The 10-, 11-, 12-, and 13-mm groups based on nail size had 113, 74, 54, and 16 patients, respectively. The overall union rate was 97% (257/265). No significant differences in union rate or time to union were observed among these 4 groups. The groups based on CN differences of < 1-, 1 to 2, and > 2 mm comprised 143, 79, and 35 patients, respectively. Again, no significant differences were noted in union rate or mean time to union among the groups.
Conclusions
Similar union rate and time to union were observed, regardless of nail size or CN difference. This finding indicates that most simple femoral shaft fractures can be treated with a standard, reamed 10-mm IMN. A larger nail insertion is unnecessary and presents more risks; comparatively, the use of a small nail with less reaming is simpler, requires shorter operative times, results in less blood loss, and is less expensive.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The present work involves the investigation of coupling effects of gamma irradiation and absorbed moisture on silicone foam. Compression stress-strain test, creep test, differential scanning ...calorimetry (DSC) and swelling test were performed to analyze the properties of pristine and dewatered samples irradiated by 60Co gamma ray. Changes in the compression stress, creep elongation, melting temperature, melting enthalpy and the average molecular weight between cross-links of the dewatered samples are much more obvious than that of the pristine ones. The possible mechanism was investigated by computational study with analog molecules. It suggests that the absorbed moisture and its radiolysis species (H·/HO·) would consume part of the macromolecular radicals generated by gamma irradiation, which hinders the crosslinking reactions. This should be the main mechanism for the coupling effects of moisture and irradiation at room temperature.
Display omitted
•Coupling effects of gamma irradiation and absorbed moisture on silicone foam were investigated by both experiment and computational study.•The corresponding mechanism for the coupling effects of moisture and gamma irradiation was also proposed.
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