Antimicrobial and Cytotoxic Effect of Positively Charged Nanosilver-Coated Silk Sutures.

Sutures are a crucial component of surgical procedures, serving to close and stabilize wound margins to promote healing. However, microbial contamination of sutures can increase the risk of surgical site infections (SSI) due to colonization by pathogens. This study aimed to tackle SSI by synthesizing positively charged silver nanoparticles (P-AgNPs) and using them to produce antimicrobial sutures. The P-AgNPs were reduced and stabilized using polyethylenimine (PEI), a cationic branched polymer. The physiochemical characteristics of P-AgNPs were confirmed from the surface plasmon resonance (SPR) peak at 419 nm, spherical morphology with a particle size range of 8-10 nm, PEI functional groups on NPs, a hydrodynamic diameter of 12.3 ± 2.4 nm, and a zeta potential of 31.3 ± 6 mV. Subsequently, the surfaces of silk sutures were impregnated with P-AgNPs at different time intervals (24, 48, and 96 h) using an ex situ method. Scanning electron microscopy (SEM) and tensile strength studies were conducted to determine the coating and durability of the NP-coated sutures. The NPs were quantified on sutures using inductively coupled plasma optical emission spectrophotometry (ICP-OES), which was in the range of 1-5 µg. Primarily, antimicrobial activity was studied using three microorganisms (Candida albicans, Streptococcus mutans, and Staphylococcus aureus) for both P-AgNPs and suture-coated P-AgNPs using the agar diffusion method. The results showed that only the NPs and NP-coated sutures exhibited enhanced antimicrobial effects against bacteria and fungi. Finally, the cytotoxicity of the sutures was investigated using stem cells from the apical papilla (SCAPs) for 24 h, which exhibited more than 75% cell viability. Overall, the results indicate that NP-coated sutures can potentially be used as antimicrobial sutures to diminish or inhibit SSI in postoperative or general surgery patients.

Emotion regulation strategies and psychological health across cultures.

Emotion regulation is important for psychological health and can be achieved by implementing various strategies. How one regulates emotions is critical for maximizing psychological health. Few studies, however, tested the psychological correlates of different emotion regulation strategies across multiple cultures. In a preregistered cross-cultural study (N = 3,960, 19 countries), conducted during the COVID-19 pandemic, we assessed associations between the use of seven emotion regulation strategies (situation selection, distraction, rumination, cognitive reappraisal, acceptance, expressive suppression, and emotional support seeking) and four indices of psychological health (life satisfaction, depressive symptoms, perceived stress, and loneliness). Model comparisons based on Bayesian information criteria provided support for cultural differences in 36% of associations, with very strong support for differences in 18% of associations. Strategies that were linked to worse psychological health in individualist countries (e.g., rumination, expressive suppression) were unrelated or linked to better psychological health in collectivist countries. Cultural differences in associations with psychological health were most prominent for expressive suppression and rumination and also found for distraction and acceptance. In addition, we found evidence for cultural similarities in 46% of associations between strategies and psychological health, but none of this evidence was very strong. Cultural similarities were most prominent in associations of psychological health with emotional support seeking. These findings highlight the importance of considering the cultural context to understand how individuals from diverse backgrounds manage unpleasant emotions. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Antibiofilm properties of silver nanoparticles incorporated into polymethyl methacrylate used for dental applications.

BACKGROUND: Acrylic resins used in dental and biomedical applications do not have antimicrobial properties, their surface is susceptible to colonization of microorganisms. OBJECTIVE: The aim of this study was to evaluate the antibiofilm properties of silver nanoparticles (AgNPs) deposited in a polymethyl methacrylate (PMMA) surface against a Staphylococcus aureus biofilm. METHODS: The PMMA was impregnated with AgNPs by using the in-situ polymerization method. To determine the solubility of the incorporated silver (Ag+) atomic absorption spectrophotometry was used (AAS) at 24 h, 48 h, 7 days, and 30 days. Thirty specimens of PMMA with AgNPs and without NP (control group) were assembled in the CDC Biofilm Bioreactor system with a cell suspension of S. aureus. The specimens were removed at 6, 12, 24, 48, and 72 h to determine the viability profile and quantify the Arbitrary Fluorescence Units (AFU). RESULTS: The AgNPs showed an irregular and quasispherical shape with an average size of 25 nm. AAS analysis demonstrated a low solubility of Ag+. The formation of the S. aureus biofilm increased as the evaluation periods continued up to 72 h. The experimental group showed poor growth, and a decrease in the intensity of the fluorescence demonstrated a statistically significant inhibition of the formation of the biofilm (P < 0.05) in relation to the control group at 6, 12, 24, 48, and 72 h. CONCLUSION: AgNPs incorporated into PMMA decreased the growth and maturation of S. aureus biofilm.

Spatially Segregated Transmission of Co-Occluded Baculoviruses Limits Virus-Virus Interactions Mediated by Cellular Coinfection during Primary Infection.

The occlusion bodies (OBs) of certain alphabaculoviruses are polyhedrin-rich structures that mediate the collective transmission of tens of viral particles to the same insect host. In addition, in multiple nucleopolyhedroviruses, occlusion-derived virions (ODVs) form nucleocapsid aggregates that are delivered to the same host cell. It has been suggested that, by favoring coinfection, this transmission mode promotes evolutionarily stable interactions between different baculovirus variants. To quantify the joint transmission of different variants, we obtained OBs from cells coinfected with two viral constructs, each encoding a different fluorescent reporter, and used them for inoculating Spodoptera exigua larvae. The microscopy analysis of midguts revealed that the two reporter genes were typically segregated into different infection foci, suggesting that ODVs show limited ability to promote the co-transmission of different virus variants to the same host cell. However, a polyhedrin-deficient mutant underwent inter-host transmission by exploiting the OBs of a fully functional virus and re-acquired the lost gene through recombination, demonstrating cellular coinfection. Our results suggest that viral spatial segregation during transmission and primary infection limits interactions between different baculovirus variants, but that these interactions still occur within the cells of infected insects later in infection.

Belief in a COVID-19 Conspiracy Theory as a Predictor of Mental Health and Well-Being of Health Care Workers in Ecuador: Cross-Sectional Survey Study.

BACKGROUND: During the coronavirus disease (COVID-19) pandemic, social media platforms have become active sites for the dissemination of conspiracy theories that provide alternative explanations of the cause of the pandemic, such as secret plots by powerful and malicious groups. However, the association of individuals' beliefs in conspiracy theories about COVID-19 with mental health and well-being issues has not been investigated. This association creates an assessable channel to identify and provide assistance to people with mental health and well-being issues during the pandemic. OBJECTIVE: Our aim was to provide the first evidence that belief in conspiracy theories regarding the COVID-19 pandemic is a predictor of the mental health and well-being of health care workers. METHODS: We conducted a survey of 252 health care workers in Ecuador from April 10 to May 2, 2020. We analyzed the data regarding distress and anxiety caseness with logistic regression and the data regarding life and job satisfaction with linear regression. RESULTS: Among the 252 sampled health care workers in Ecuador, 61 (24.2%) believed that the virus was developed intentionally in a lab; 82 (32.5%) experienced psychological distress, and 71 (28.2%) had anxiety disorder. Compared to health care workers who were not sure where the virus originated, those who believed the virus was developed intentionally in a lab were more likely to report psychological distress and anxiety disorder and to have lower levels of job satisfaction and life satisfaction. CONCLUSIONS: This paper identifies belief in COVID-19 conspiracy theories as an important predictor of distress, anxiety, and job and life satisfaction among health care workers. This finding will enable mental health services to better target and provide help to mentally vulnerable health care workers during the ongoing COVID-19 pandemic.

Developing and testing a measure of COVID-19 organizational support of healthcare workers - results from Peru, Ecuador, and Bolivia.

During the COVID-19 pandemic, healthcare workers are facing high workloads with resource constraints and risk of virus exposure, and healthcare organizations need to support their healthcare workers to reduce their anxiety. Based on a recent 8-point framework of COVID-19 specific organization support, we devised a measure of COVID-19 Organizational Support (COVID-OS). We tested the new measure with 712 healthcare workers in Bolivia, Ecuador, and Peru and found the new measure formed three factors to predict healthcare workers' anxiety and life satisfaction during the COVID-19 pandemic. We call for further studies to test COVID-OS in other countries and settings.

Improvement of baculovirus as protein expression vector and as biopesticide by CRISPR/Cas9 editing.

The clustered regularly interspaced short palindromic repeats (CRISPR) system-associated Cas9 endonuclease is a molecular tool that enables specific sequence editing with high efficiency. In this study, we have explored the use of CRISPR/Cas9 system for the engineering of baculovirus. We have shown that the delivering of Cas9-single guide RNA ribonucleoprotein (RNP) complex with or without DNA repair template into Sf21 insect cells through lipofection might be efficient to produce knockouts as well as knock-ins into the baculovirus. To evaluate potential application of our CRISPR/Cas9 method to improve baculovirus as protein expression vector and as biopesticide, we attempted to knockout several genes from a recombinant AcMNPV form used in the baculovirus expression system as well as in a natural occurring viral isolate from the same virus. We have additionally confirmed the adaptation of this methodology for the generation of viral knock-ins in specific regions of the viral genome. Analysis of the generated mutants revealed that the editing efficiency and the type of changes was variable but relatively high. Depending on the targeted gene, the editing rate ranged from 10% to 40%. This study established the first report revealing the potential of CRISPR/Cas9 for genome editing in baculovirus, contributing to the engineering of baculovirus as a protein expression vector as well as a biological control agent.

Estimates of dietary exposure of Spanish population to packaging contaminants from cereal based foods contained in plastic materials.

Food packaging may be a potential source of contamination, through the migration of chemicals from the packaging into the food, thus food consumption is an important route of human exposure to packaging contaminants. In the present study an approach to estimate the exposure to different chemicals transferred from food packaging was designed. As a first step a GC-MS screening was conducted to identify potential contaminants in the materials. Secondly, different chemicals previously identified in the packaging materials were selected for exposure assessment. The proposed methodology was applied to cereal based foods packed with plastic packaging. A variety of chemicals including e.g. acetyl tributyl citrate (ATBC), bis (2-ethylhexyl) adipate (DEHA) and diethyl phthalate (DEP) among others were identified and analyzed in the foodstuffs. For this purpose a LC-MS/MS method was developed. The selected foodstuffs were pooled into three groups according to the population age (12-35 months, 3-9 years and 10-17 years) and based on the Spanish consumption data (Enalia). In general, ATBC mean exposure was higher than that of phthalates and DEHA for the three groups considered, with mean dietary exposure values ranging from 1.01 µg/kg bw/day (pool 12-35 months) to 2.01 µg/kg bw/day (pool 3-9 years).

Migration studies of butylated hydroxytoluene, tributyl acetylcitrate and dibutyl phthalate into food simulants.

BACKGROUND: Migration is a mass transfer process in which chemical substances with a low molecular weight are transferred from packaging into food. This phenomenon has received great attention from a food safety point of view because these chemicals could potentially represent a risk for consumers' health. The present study investigated the process of migration of two common plasticizers [tributyl acetylcitrate (ATBC) and dibutyl phthalate (DBP)] and one antioxidant [butylated hydroxytoluene (BHT)] from a common plastic material used in food packaging (low density polyethylene) into 50% ethanol (v/v), 95% ethanol (v/v) and isooctane. A mathematical model based on Fick's second law was used to determine the partition and diffusion coefficients. In addition, the effect of temperature on the diffusion was studied by applying the Arrhenius equation. RESULTS: High-performance liquid chromatography with diode-array detection and gas chromatography-mass spectrometry methods were applied to measure the amount of ATBC, DBP and BHT that migrated into the food simulants. A mathematical model based on Fick's second law of diffusion was used to estimate key migration parameters: diffusion and partition coefficients (DP and KP/F ), which were determined for each migrant and food simulant at three temperatures (10, 20 and 40 °C). The results showed that the diffusion process is significantly influenced by temperature, although the type of simulant also plays an important role in the migration process. CONCLUSION: The model investigated is shown to be appropriate for predicting the migration from food packaging into real foodstuffs at common storage temperatures. © 2018 Society of Chemical Industry.

Identification of intentionally and non-intentionally added substances in plastic packaging materials and their migration into food products.

Plastic materials are widely used in food packaging applications; however, there is increased concern because of the possible release of undesirable components into foodstuffs. Migration of plastic constituents not only has the potential to affect product quality but also constitutes a risk to consumer health. In order to check the safety of food contact materials, analytical methodologies to identify potential migrants are required. In the first part of this work, a GC/MS screening method was developed for the identification of components from plastic packaging materials including intentionally and "non-intentionally added substances" (NIAS) as potential migrants. In the second part of this study, the presence of seven compounds (bis (2-ethylhexyl) phthalate (DEHP), diethyl phthalate (DEP), diisobutyl phthalate (DIBP), dibutyl phthalate (DBP), butylated hydroxytoluene (BHT), acetyl tributyl citrate (ATBC), benzophenone (BP)) previously identified in packaging materials were investigated in food products (corn and potatoes snacks, cookies, and cakes). For this purpose, a suitable extraction method was developed and quantification was performed using GC-MS. The developed method was validated in terms of linearity, recovery, repeatability, and limits of detection and quantification. The spiked recoveries varied between 82.7 and 116.1%, and relative standard deviation (RSD) was in the range of 2.22-15.9%. The plasticizer ATBC was the most detected compound (94% samples), followed by DEP (65%), DEHP (47%), BP (44%), DBP (35%), DIBP (21%), and BHT (12%). Regarding phthalates, DEP and DEHP were the most frequently detected compounds in concentrations up to 1.44 µg g-1. In some samples, only DBP exceeded the European SML of 0.3 mg kg-1 established in Regulation 10/2011. Graphical abstract Chemical migration from plastic packaging into food.

Synthesis and evaluation of dual crosslinked alginate microbeads.

Alginate hydrogels have been investigated for a broad variety of medical applications. The ability to assemble hydrogels at neutral pH and mild temperatures makes alginate a popular choice for the encapsulation and delivery of cells and proteins. Alginate has been studied extensively for the delivery of islets as a treatment for type 1 diabetes. However, poor stability of the encapsulation systems after implantation remains a challenge. In this paper, alginate was modified with 2-aminoethyl methacrylate hydrochloride (AEMA) to introduce groups that can be photoactivated to generate covalent bonds. This enabled formation of dual crosslinked structure upon exposure to ultraviolet light following initial ionic crosslinking into bead structures. The degree of methacrylation was varied and in vitro stability, long term swelling, and cell viability examined. At low levels of the methacrylation, the beads could be formed by first ionic crosslinks followed by exposure to ultraviolet light to generate covalent bonds. The methacrylated alginate resulted in more stable beads and cells were viable following encapsulation. Alginate microbeads, ionic (unmodified) and dual crosslinked, were implanted into a rat omentum pouch model. Implantation was performed with a local injection of 100 µl of 50 µg/ml of Lipopolysaccharide (LPS) to stimulate a robust inflammatory challenge in vivo. Implants were retrieved at 1 and 3 weeks for analysis. The unmodified alginate microbeads had all failed by week 1, whereas the dual-crosslinked alginate microbeads remained stable up through 3 weeks. The modified alginate microbeads may provide a more stable alternative to current alginate-based systems for cell encapsulation. STATEMENT OF SIGNIFICANCE: Alginate, a naturally occurring polysaccharide, has been used for cell encapsulation to prevent graft rejection of cell transplants for people with type I diabetes. Although some success has been observed in clinical trials, the lack of reproducibility and failure to reach insulin dependence for longer periods of time indicates the need for improvements in the procedure. A major requirement for the long-term function of alginate encapsulated cells is the mechanical stability of microcapsules. Insufficient mechanical integrity of the capsules can lead to immunological reactions in the recipients. In this work, alginate was modified to allow photoactivatable groups in order to allow formation of covalent crosslinks in addition to ionic crosslinking. The dual crosslinking design prevents capsule breakdown following implantation in vivo.

Effects of Liquid Medium and Ablation Wavelength on the Properties of Cadmium Sulfide Nanoparticles Formed by Pulsed-Laser Ablation.

Pulsed-laser ablation in liquid (PLAL) is a green synthesis technique to obtain semiconductor nanomaterials in colloidal form. Herein, cadmium sulfide (CdS) nanoparticles were synthesized by the pulsed-laser ablation of a CdS target in different liquid media by using λ=532 and 1064 nm outputs from a pulsed (10 ns, 10 Hz) Nd:YAG laser at different ablation fluence values. The morphology, structure, crystalline phase, elemental composition, optical, and luminescent properties of CdS nanomaterials were analyzed by using transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV/Vis absorption spectroscopy, and fluorescence spectroscopy. By changing the liquid medium and ablation wavelength, CdS nanoparticles with different morphology and size were formed, as demonstrated by using TEM analysis. The crystallinity and chemical states of the ablation products were confirmed by using XRD and XPS analyses. The optical bandgap of the CdS nanoparticles was dependent on the ablation wavelength and the fluence. These nanocolloids presented different green emissions, which implied the presence of several emission centers. CdS nanocolloids in distilled water catalyzed the photocatalytic decay of methylene blue dye under light irradiation from a solar simulator.

Imaging of Hydrogel Microsphere Structure and Foreign Body Response Based on Endogenous X-Ray Phase Contrast.

Transplantation of functional islets encapsulated in stable biomaterials has the potential to cure Type I diabetes. However, the success of these materials requires the ability to quantitatively evaluate their stability. Imaging techniques that enable monitoring of biomaterial performance are critical to further development in the field. X-ray phase-contrast (XPC) imaging is an emerging class of X-ray techniques that have shown significant promise for imaging biomaterial and soft tissue structures. In this study, XPC imaging techniques are shown to enable three dimensional (3D) imaging and evaluation of islet volume, alginate hydrogel structure, and local soft tissue features ex vivo. Rat islets were encapsulated in sterile ultrapurified alginate systems produced using a high-throughput microfluidic system. The encapsulated islets were implanted in omentum pouches created in a rodent model of type 1 diabetes. Microbeads were imaged with XPC imaging before implantation and as whole tissue samples after explantation from the animals. XPC microcomputed tomography (µCT) was performed with systems using tube-based and synchrotron X-ray sources. Islets could be identified within alginate beads and the islet volume was quantified in the synchrotron-based µCT volumes. Omental adipose tissue could be distinguished from inflammatory regions resulting from implanted beads in harvested samples with both XPC imaging techniques. Individual beads and the local encapsulation response were observed and quantified using quantitative measurements, which showed good agreement with histology. The 3D structure of the microbeads could be characterized with XPC imaging and failed beads could also be identified. These results point to the substantial potential of XPC imaging as a tool for imaging biomaterials in small animal models and deliver a critical step toward in vivo imaging.

This paper is a winner in the Undergraduate category for the SFB awards: Evaluation of the tissue response to alginate encapsulated islets in an omentum pouch model.

Islet transplantation is currently in clinical use as a treatment for type I diabetes, but donor shortages and long-term immunosuppression limit broad application. Alginate microcapsules coated with poly-l-ornithine can be used to encapsulate islets in an environment that allows diffusion of glucose, insulin, nutrients, and waste products while inhibiting cells and antibodies. While clinical trials are ongoing using islets encapsulated in alginate microbeads, there are concerns in regards to long-term stability. Evaluation of the local tissue response following implantation provides insight into the underlying mechanisms contributing to biomaterial failure, which can be used to the design of new material strategies. Macrophages play an important role in driving the response. In this study, the stability of alginate microbeads coated with PLO containing islets transplanted in the omentum pouch model was investigated. Biomaterial structure and the inflammatory response were characterized by X-ray phase contrast (XPC) µCT imaging, histology, and immunostaining. XPC allowed evaluation of microbead 3D structure and identification of failed and stable microbeads. A robust inflammatory response characterized by high cell density and the presence of pro-inflammatory macrophages was found around the failed grafts. The results obtained provide insight into the local tissue response and possible failure mechanisms for alginate microbeads. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 1581-1590, 2016.