Stress relaxation in tunable gels.

Hydrogels are a staple of biomaterials development. Optimizing their use in e.g. drug delivery or tissue engineering requires a solid understanding of how to adjust their mechanical properties. Here, we present a numerical study of a class of hydrogels made of 4-arm star polymers with a combination of covalent and reversible crosslinks. This design principle combines the flexibility and responsivity associated with reversible linkers with stability provided by chemical crosslinks. In molecular dynamics simulations of such hybrid gel networks, we observe that the strength of the reversible bonds can tune the material from solid to fluid. We identify at what fraction of reversible bonds this tunability is most pronounced, and find that the stress relaxation time of the gels in this tunable regime is set directly by the average lifetime of the reversible bonds. As our design is easy to realize in the already widely-used tetraPEG gel setting, our work will provide guidelines to improve the mechanical performance of biomedical gels.

Hepatitis C Virus Core Antigen (HCVAg): an affordable assay to monitor the efficacy of treatment in DAAs era.

Hepatitis C virus (HCV) Core Antigen (HCVAg) and HCV-RNA were tested in 962 plasma/serum samples from 180 patients during Direct Antiviral Agents (DAAs) treatment and at follow-up. One hundred and eighty individuals were included: 71% carried advanced fibrosis and 43% were treatment-experienced. A Sustained Virological Response (SVR) was achieved in 166/180 (92%) individuals: 96/102 (94.1%) na ve and 70/78 (89.7%) treatment-experienced (p=0.20). The baseline median levels of HCV-RNA and HCVAg were not significantly different between individuals achieving SVR (5.92 x 105 IU/mL, IQR 5.4-6.4, and 3,417 fmol/L, 2,900-3,795) and those without SVR (6.06 x 105 IU/mL, 5.63-6.57, and 3,391 fmol/L, 2,828-4,077). The HCV-RNA vs. HCVAg assays results showed a fair correlation with an overall moderate qualitative agreement (kappa=0.52). Among treatment-failed individuals, at failure 100% of the assays results were positive for both techniques, with HCV-RNA median value 3.09 x 105 IU/mL (2.10-29.09) and HCVAg median value 1570.28 fmol/L (360.15-9317.67). Undetectable HCV-RNA at EOT showed sensitivity 54%, specificity 100%, negative predictive value (NPV) 93% and positive predictive value (PPV) 100%. Undetectable HCVAg at EOT showed sensitivity 74%, specificity 100%, NPV 97% and PPV 100%. The operative and economic advantages of the HCVAg support the alternative use of HCVAg to monitor DAAs treatment outcome.

Staphylococcus aureus vaccine preclinical and clinical development: current state of the art.

Staphylococcus aureus is a major pathogen in both community and hospital settings. It is a significant etiological agent to treat in healthcare-related infections due to both its ability to cause invasive infection as well as to form biofilm on biomaterials and the high prevalence of resistance to first line antibiotics. The most challenging preventive strategy is vaccine development to guarantee a full and durable protection from staphylococcal diseases in all different high-risk populations, even if the lack of a known correlate of protection from S. aureus is a major hindrance to this effort. We aimed to review the most recent advances in the field of vaccinology against S. aureus, highlighting the potential for future application of the different experimental vaccine types. Several vaccines have completed their preclinical phase of development and others have been tested in humans, however no successful phase III clinical trial has yet been completed.

Evaluation of Monkeypox- and Vaccinia virus-neutralizing antibodies in human serum samples after vaccination and natural infection.

Introduction: In early to mid-2022, an unexpected outbreak of Monkeypox virus infections occurred outside the African endemic regions. Vaccines originally developed in the past to protect against smallpox are one of the available countermeasures to prevent and protect against Orthopoxvirus infections. To date, there are few studies on the cross-reactivity of neutralizing antibodies elicited by previous vaccinia virus-based vaccination and/or Monkeypox virus infection. The aim of this study was to evaluate a possible approach to performing Monkeypox and vaccinia live-virus microneutralization assays in which the read-out is based on the production of cytopathic effect in the cell monolayer. Methods: Given the complexity of Orthopoxviruses, the microneutralization assay was performed in such a way as to uncover a potential role of complement, with and without the addition of an external source of Baby Rabbit Complement. A set of human serum samples from individuals who had been naturally infected with Monkeypox virus and individuals who may have and not have undergone vaccinia virus vaccinations, was used to evaluate the performance, sensitivity, and specificity of the assay. Results and conclusions: The results of the present study confirm the presence and cross-reactivity of antibodies elicited by vaccinia-based vaccines, which proved able to neutralize the Monkeypox virus in the presence of an external source of complement.

Dynamics of Total and Intact HIV-1 DNA in Virologically Suppressed Patients Switching to DTG-Based or ATV-Based Dual Therapy.

BACKGROUND: Clinical trials have demonstrated noninferior viral suppression rates of selected 2-drug regimens (2DRs) over standard 3-drug regimens (3DRs). However, the effect of simplification to 2DRs on HIV-1 reservoir remains to be fully assessed. SETTING: Retrospective analyses of samples of virologically suppressed people living with HIV remaining on the same 3DRs or switching to DTG + 3TC or ATV/r + 3TC 2DRs. METHODS: Whole blood samples were collected at enrollment and after 48 weeks. Total HIV-1 DNA (tDNA) and intact HIV-1 DNA (iDNA) were quantified by droplet digital polymerase chain reaction and intact proviral DNA assay, respectively. Statistical analysis was performed to identify associations among variables, and multiple linear regression was used to analyze potential predictors of tDNA and iDNA changes over time. RESULTS: Forty-seven individuals were switched to DTG + 3TC 2DR (N = 23) and ATV/r + 3TC 2DR (N = 24), while 18 remained on 3DRs. tDNA did not change either in the overall population or in the 3DR and 2DR groups. iDNA decreased significantly in the whole data set and in the overall 3DR and 2DR groups ( P = 0.001, P = 0.039 and P = 0.009, respectively). iDNA, but not tDNA, was inversely correlated with the time of viral suppression ( P = 0.002) and time under antiretroviral therapy ( P = 0.006). Higher nadir CD4 + T-cell counts ( P = 0.001) and lower zenith viral load ( P = 0.02) showed an association with the decrease of iDNA, but not with tDNA. CONCLUSIONS: Both tDNA and iDNA dynamics supported noninferior efficacy of 2DRs over 3DRs. iDNA could be more informative than tDNA in analyzing the dynamics of the HIV-1 reservoir under different treatment strategies.

Carriers of ADAMTS13 Rare Variants Are at High Risk of Life-Threatening COVID-19.

Thrombosis of small and large vessels is reported as a key player in COVID-19 severity. However, host genetic determinants of this susceptibility are still unclear. Congenital Thrombotic Thrombocytopenic Purpura is a severe autosomal recessive disorder characterized by uncleaved ultra-large vWF and thrombotic microangiopathy, frequently triggered by infections. Carriers are reported to be asymptomatic. Exome analysis of about 3000 SARS-CoV-2 infected subjects of different severities, belonging to the GEN-COVID cohort, revealed the specific role of vWF cleaving enzyme ADAMTS13 (A disintegrin-like and metalloprotease with thrombospondin type 1 motif, 13). We report here that ultra-rare variants in a heterozygous state lead to a rare form of COVID-19 characterized by hyper-inflammation signs, which segregates in families as an autosomal dominant disorder conditioned by SARS-CoV-2 infection, sex, and age. This has clinical relevance due to the availability of drugs such as Caplacizumab, which inhibits vWF-platelet interaction, and Crizanlizumab, which, by inhibiting P-selectin binding to its ligands, prevents leukocyte recruitment and platelet aggregation at the site of vascular damage.

Multiple chronic parasitic infections in an immunocompetent immigrant: a challenge for healthcare management.

The case reports multiple helmintiasis and chronic hepatitis caused by hepatitis B virus (HBV)/hepatitis D virus (HDV) in an immunocompetent immigrant male. It highlights the importance of early diagnosis and treatment of neglected infectious diseases in low endemic areas, besides difficulties that Western countries encounter in responding to immigrants' health needs.

Sculpting Silica Colloids by Etching Particles with Nonuniform Compositions.

We present the synthesis of new shapes of colloidal silica particles by manipulating their chemical composition and subsequent etching. Segments of silica rods, prepared by the ammonia catalyzed hydrolysis and condensation of tetraethylorthosilicate (TEOS) from polyvinylpyrrolidone loaded water droplets, were grown under different conditions. Upon decreasing temperature, delaying ethanol addition, or increasing monomer concentration, the rate of dissolution of the silica segment subsequently formed decreased. A watery solution of NaOH (∼mM) selectively etched these segments. Further tuning the conditions resulted in rod-cone or cone-cone shapes. Deliberately modulating the composition along the particle's length by delayed addition of (3-aminopropyl)-triethoxysilane (APTES) also allowed us to change the composition stepwise. The faster etching of this coupling agent in neutral conditions or HF afforded an even larger variety of particle morphologies while in addition changing the chemical functionality. A comparable step in composition was applied to silica spheres. Biamine functional groups used in a similar way as APTES caused a charge inversion during the growth, causing dumbbells and higher order aggregates to form. These particles etched more slowly at the neck, resulting in a biconcave silica ring sandwiched between two silica spheres, which could be separated by specifically etching the functionalized layer using HF.

Impairment of PI3K/AKT and WNT/ß-catenin pathways in bone marrow mesenchymal stem cells isolated from patients with myelodysplastic syndromes.

Bone marrow mesenchymal stem cells (BM-MSCs) exhibit multiple abnormalities in myelodysplastic syndromes (MDS), including impaired proliferative and clonogenic capacity, altered morphology, increased senescence, impaired immunoregulatory properties, and reduced hematopoietic support capacity. Common signaling pathways, such as PI3K/AKT and WNT/ß-catenin, regulate multiple MSC properties, including proliferation, differentiation, and cell-cell interaction. Here, with polymerase chain reaction arrays, we investigated the expression of 84 genes belonging to the PI3K/AKT signaling pathways in BM-MSCs isolated from patients with MDS, acute myeloid leukemia, and therapy-related myeloid neoplasms, using as a control BM-MSCs isolated from patients with untreated early-stage lymphomas without BM involvement. Statistically significant downregulation of GSK3ß, SOS1, RASA1, and MTCP1 gene expression was observed in BM-MSCs isolated from patients with de novo MDS, as compared with controls. Moreover, expression of the GSK3ß protein was reduced in MDS-derived MSCs, and was associated with concomitant reduction of phosphorylation at Ser-9. The role of GSK3ß in the downstream WNT/ß-catenin signaling pathway was assessed. We investigated ß-catenin protein levels and expression of 84 genes belonging to the WNT target gene pathway using PCR arrays in MDS BM-MSCs, as compared with control BM-MSCs. GSK3ß impairment translated into decreased ß-catenin protein levels and downregulation of several WNT/ß-catenin target genes (SOX9, EGR1, WISP1). These findings suggest that deregulation of genes involved in the PI3K/AKT and WNT signaling pathways may contribute to the phenotypical abnormalities of MDS BM-MSCs.