Evaluation and Modeling of Polylactide Photodegradation under Ultraviolet Irradiation: Bio-Based Polyester Photolysis Mechanism.

In our study, we investigated the accelerated aging process of PLA under 253.7 nm UV-C irradiation with the use of the GPC, NMR, FTIR, and DSC methods and formal kinetic analysis. The results of GPC and DSC indicated a significant degree of destructive changes in the PLA macromolecules, while spectroscopic methods NMR and FTIR showed maintenance of the PLA main structural elements even after a long time of UV exposure. In addition to that, the GPC method displayed the formation of a high molecular weight fraction starting from 24 h of irradiation, and an increase in its content after 144 h of irradiation. It has been shown for the first time that a distinctive feature of prolonged UV exposure is the occurrence of intra- and intermolecular radical recombination reactions, leading to the formation of a high molecular weight fraction of PLA decomposition products. This causes the observed slowdown of the photolysis process. It was concluded that photolysis of PLA is a complex physicochemical process, the mechanism of which depends on morphological changes in the solid phase of the polymer under UV radiation.

Prognostic and predictive role of immune microenvironment in colorectal cancer.

Colorectal cancer (CRC) represents a molecularly heterogeneous disease and one of the most frequent causes of cancer-related death worldwide. The traditional classification of CRC is based on pathomorphological and molecular characteristics of tumor cells (mucinous, ring-cell carcinomas, etc.), analysis of mechanisms of carcinogenesis involved (chromosomal instability, microsatellite instability, CpG island methylator phenotype) and mutational statuses of commonly altered genes (KRAS, NRAS, BRAF, APC, etc.), as well as expression signatures (CMS 1-4). It is also suggested that the tumor microenvironment is a key player in tumor progression and metastasis in CRC. According to the latest data, the immune microenvironment can also be predictive of the response to immune checkpoint inhibitors. In this review, we highlight how the immune environment influences CRC prognosis and sensitivity to systemic therapy.

Selecting a randomization method for a multi-center clinical trial with stochastic recruitment considerations.

BACKGROUND: The design of a multi-center randomized controlled trial (RCT) involves multiple considerations, such as the choice of the sample size, the number of centers and their geographic location, the strategy for recruitment of study participants, amongst others. There are plenty of methods to sequentially randomize patients in a multi-center RCT, with or without considering stratification factors. The goal of this paper is to perform a systematic assessment of such randomization methods for a multi-center 1:1 RCT assuming a competitive policy for the patient recruitment process. METHODS: We considered a Poisson-gamma model for the patient recruitment process with a uniform distribution of center activation times. We investigated 16 randomization methods (4 unstratified, 4 region-stratified, 4 center-stratified, 3 dynamic balancing randomization (DBR), and a complete randomization design) to sequentially randomize n = 500 patients. Statistical properties of the recruitment process and the randomization procedures were assessed using Monte Carlo simulations. The operating characteristics included time to complete recruitment, number of centers that recruited a given number of patients, several measures of treatment imbalance and estimation efficiency under a linear model for the response, the expected proportions of correct guesses under two different guessing strategies, and the expected proportion of deterministic assignments in the allocation sequence. RESULTS: Maximum tolerated imbalance (MTI) randomization methods such as big stick design, Ehrenfest urn design, and block urn design result in a better balance-randomness tradeoff than the conventional permuted block design (PBD) with or without stratification. Unstratified randomization, region-stratified randomization, and center-stratified randomization provide control of imbalance at a chosen level (trial, region, or center) but may fail to achieve balance at the other two levels. By contrast, DBR does a very good job controlling imbalance at all 3 levels while maintaining the randomized nature of treatment allocation. Adding more centers into the study helps accelerate the recruitment process but at the expense of increasing the number of centers that recruit very few (or no) patients-which may increase center-level imbalances for center-stratified and DBR procedures. Increasing the block size or the MTI threshold(s) may help obtain designs with improved randomness-balance tradeoff. CONCLUSIONS: The choice of a randomization method is an important component of planning a multi-center RCT. Dynamic balancing randomization with carefully chosen MTI thresholds could be a very good strategy for trials with the competitive policy for patient recruitment.

Current trends and challenges in the analysis of marine environmental contaminants by isotope ratio mass spectrometry.

An increasing number of organic and inorganic pollutants are being detected in the marine environment, posing a severe threat to the ecosystem and human health, even in trace concentrations. Isotope ratio mass spectrometry (IRMS) is one of the critical methods for determining the origin and fate of environmental pollutants and characterising their transformation processes. It has been used for a relatively long time for ecological monitoring of some well-studied industrial hydrocarbons at contaminated sites. However, the method still faces many analytical challenges. This review provides a comprehensive overview of recent technical advances concerning IRMS analysis of various contaminants and discusses typical pitfalls encountered in marine environment analysis. Particular attention is given to the study of sampling techniques and sample preparation for examination, often the keys to successful research given the complexity of marine matrices and the diverse and numerous nature of contaminants. Prospects for developing IRMS to monitor pollution sources and pollutant transformation in the marine environment are outlined.

A rabbit model of ear otitis established using the Malassezia pachydermatis strain C23 from dogs.

Background and Aim: Fungal infections are a growing problem for both humans and animals due to the emergence of pathogenic strains resistant to modern antifungal treatments. To evaluate the efficacy of new antifungal drugs, it is essential to develop animal models that demonstrate typical responses to both the infection (pathogenesis and clinical course) and to the treatment, including adverse effects. In this study, we established a rabbit otitis model by infection of an aggressive multidrug-resistant strain from dogs, Malassezia pachydermatis C23, with no need for concomitant immunosuppression. Materials and Methods: Twenty healthy adult male gray giant rabbits (1 year old, 5.5 kg) were inoculated once with M. pachydermatis C23 at 108 colony-forming units/mL. We observed the clinical signs of the disease and collected ear smears and blood samples every 5 days. Results: The infection progressed rapidly and exhibited characteristic clinical signs without spontaneous recovery for at least 1 month. In fact, substantial deterioration was observed as evidenced by blood parameters. Conclusion: This rabbit otitis model established using an aggressive drug-resistant fungus strain without immunosuppression could prove valuable for testing novel antifungal agents.

Sphingolipid Metabolism in Tumor Cells.

Sphingolipids are a diverse family of complex lipids typically composed of a sphingoid base bound to a fatty acid via amide bond. The metabolism of sphingolipids has long remained out of focus of biochemical studies. Recently, it has been attracting an increasing interest of researchers because of different and often multidirectional effects demonstrated by sphingolipids with a similar chemical structure. Sphingosine, ceramides (N-acylsphingosines), and their phosphorylated derivatives (sphingosine-1-phosphate and ceramide-1-phosphates) act as signaling molecules. Ceramides induce apoptosis and regulate stability of cell membranes and cell response to stress. Ceramides and sphingoid bases slow down anabolic and accelerate catabolic reactions, thus suppressing cell proliferation. On the contrary, their phosphorylated derivatives (ceramide-1-phosphate and sphingosine-1-phosphate) stimulate cell proliferation. Involvement of sphingolipids in the regulation of apoptosis and cell proliferation makes them critically important in tumor progression. Sphingolipid metabolism enzymes and sphingolipid receptors can be potential targets for antitumor therapy. This review describes the main pathways of sphingolipid metabolism in human cells, with special emphasis on the properties of this metabolism in tumor cells.

A new digital case-based educational program Orthogeriatrics TeleECHO, a strategy to improve the care of fragility fracture patients.

Participation in Orthogeriatrics TeleECHO was associated with improvement in physicians' knowledge and self-confidence in managing elderly patients with fractures. PURPOSE: To develop and conduct an interactive case-based virtual TeleECHO program to expand the knowledge of healthcare professionals in the field of orthogeriatrics. METHODS: The project included twelve 90-min sessions for physicians and healthcare managers. Each session was based on real clinical cases discussed by the multidisciplinary group of faculty. The efficacy of the project was assessed using questionnaires. RESULTS: The attendance of individual sessions ranged from 129 to 224 with the total number of participants 829; 25% of participants were from remote rural regions. A survey conducted at the beginning of the project showed insufficient knowledge and ability to apply the concepts of orthogeriatrics. A final questionnaire showed that 74% of respondents participated in most sessions, with 94% wishing to continue participating in further sessions. There was a statistically significant overall improvement in confidence of caring for fragility fracture patients with an effect size of 0.75 (p<0.001). The proportion of responders who were able to apply their new knowledge in clinical practice shortly after TeleECHO showed a substantial increase (p<0.0001). CONCLUSION: The Orthogeriatrics TeleECHO program was effective in changing perceptions and self-confidence of the participants, and applying knowledge acquired to patient care. This model of learning could be applied in other countries in other languages to improve post-fracture care worldwide.

In Vitro Activity of Farnesol against Malassezia pachydermatis Isolates from Otitis Externa Cases in Dogs.

Chronic otitis externa of dogs is a significant problem due to the prevalence and complexity of the treatment of such animals. There is evidence that in 60-80% of cases of infectious diseases microorganisms located in the biofilm phenotype play the main role. Microorganisms in the biofilm phenotype have a number of advantages, the most significant of which is considered to be increased resistance to various external factors. Among them, a special place is occupied by resistance to antibiotics. In recent decades, research has been conducted at an increasing scale on the role of biofilm infections in various pathologies in veterinary medicine. The etiology and therapy of dog otitis externa caused by Malassezia pachydermatis biofilm has not been fully studied. This is why we consider relevant the scientific and practical aspects of research on the etiology and therapy of dog otitis externa from the position of biofilm infection. In this work, it has been statistically proven that there is a relationship between the optical density of Malassezia pachydermatis biofilms and their sensitivity to drugs, and this relationship is statistically significant. In addition, we have demonstrated that Farnesol has a good antibiofilm effect at a concentration of more 1.6 µM/mL (24% OD decrease of biofilm), and its highest antibiofilm effect (71-55%-more than a half) was observed at a concentration of 200-12.5 µM/mL.

Mass Spectrometry Insight for Assessing the Destiny of Plastics in Seawater.

Plastic pollution has become an increasingly serious environmental issue that requires using reliable analytical tools to unravel the transformations of primary plastics exposed to the marine environment. Here, we evaluated the performance of the isotope ratio mass spectrometry (IRMS) technique for identifying the origin of polymer material contaminating seawater and monitoring the compositional alterations due to its chemical degradation. Of twenty-six plastic specimens available as consumer products or collected from the Mediterranean Sea, five plastics were shown to originate from biobased polymeric materials. Natural abundance carbon and hydrogen isotope measurements revealed that biopolymers incline to substantial chemical transformation upon a prolonged exposure to seawater and sunlight irradiation. To assess the seawater-mediated aging that leads to the release of micro/nano fragments from plastic products, we propose to use microfiltration. Using this non-destructive separation technique as a front end to IRMS, the fragmentation of plastics (at the level of up to 0.5% of the total mass for plant-derived polymers) was recorded after a 3-month exposure and the rate and extent of disintegration were found to be substantially different for the different classes of polymers. Another potential impact of plastics on the environment is that toxic metals are adsorbed on their surface from the seashore water. We addressed this issue by using inductively coupled mass spectrometry after nitric acid leaching and found that several metals occur in the range of 0.1-90 µg per g on naturally aged plastics and accumulate at even higher levels (up to 10 mg g-1) on pristine plastics laboratory-aged in contaminated seawater. This study measured the degradation degree of different polymer types in seawater, filling in the gaps in our knowledge about plastic pollution and providing a useful methodology and important reference data for future research.

Analysis of Engineered Nanoparticles in Seawater Using ICP-MS-Based Technology: From Negative to Positive Samples.

A growing global emission of engineered nanoparticles (ENPs) into the aquatic environment has become an emerging safety concern that requires methods capable of identifying the occurrence and possibly determining the amounts of ENPs. In this study, we employed sector-field inductively coupled mass spectrometry to assess the presence of ENPs in coastal seawater samples collected from the Black Sea in regions suffering different anthropogenic impacts. Ultrafiltration through commercial 3 kDa membrane filters was shown to be feasible to separate the ENPs from the bulk seawater, and the subsequent ultrasound-mediated acidic dissolution makes the metals constituting the ENPs amenable to analysis. This procedure allowed the ENPs bearing Cu, Zn, V, Mo, and Sn to be for the first time quantitated in seashore surface water, their concentration ranging from 0.1 to 1.0 µg L-1 (as metal) and related to the presence of industry and/or urban stress. While these levels are decreased by natural dilution and possible sedimentation, the monitored ENPs remain measurable at a distance of 2 km from the coast. This can be attributed not only to local emission sources but also to some natural backgrounds.

Seawater analysis of engineered nanoparticles using ICP-MS-based technology: Addressing challenges with the development of reliable monitoring strategy.

With an increasing production and use of engineered nanoparticles (ENPs), inevitably grows their release into the environment. This makes it important to determine in what quantitates they occur in aquatic systems like seawater. However, even when using the most sensitive ICP-MS technique, quantification of very low seawater concentrations of ENPs is still concept rather than the fact. To approach this goal, a unified protocol for the preparation of seawater samples for ICP-MS analysis has been developed in this study using a selection of silver, titanium dioxide and zinc oxide nanoparticles. In order to minimize the risk of particle loss, the effect of sample pH was examined and it was found out that a moderate in-field acidification (to pH 7.5) ensures particle stability prior to analysis. Ultrafiltration through commercial 3 kDa membrane filters was shown feasible to separate the ENPs from the bulk seawater sample provided that the filter unit is pre-conditioned with 0.1 M copper nitrate to avoid ionic metal adsorption. The following ultrasound-mediated dissolution in 30% HNO3 directly in the filer unit and ultrafiltration makes the metals constituting the ENPs amenable to analysis. The latter was for the first time performed using high-resolution ICP-MS method validated according to the common EU standards. The limits of detection attained here were as low as 0.06, 0.09, and 17.5 µg L-1 for Ag, TiO2, and ZnO nanoparticles, respectively. Accuracy of the method was tested with uncontaminated open-sea water spiked with ENPs and recoveries were acceptable ranging from 85 to 110%.

Detection of A and B Influenza Viruses by Surface-Enhanced Raman Scattering Spectroscopy and Machine Learning.

We demonstrate the possibility of applying surface-enhanced Raman spectroscopy (SERS) combined with machine learning technology to detect and differentiate influenza type A and B viruses in a buffer environment. The SERS spectra of the influenza viruses do not possess specific peaks that allow for their straight classification and detection. Machine learning technologies (particularly, the support vector machine method) enabled the differentiation of samples containing influenza A and B viruses using SERS with an accuracy of 93% at a concentration of 200 µg/mL. The minimum detectable concentration of the virus in the sample using the proposed approach was ~0.05 µg/mL of protein (according to the Lowry protein assay), and the detection accuracy of a sample with this pathogen concentration was 84%.

Interaction of Cyprinus carpio Linnaeus with the biofilm-forming Aeromonas hydrophila.

Background and Aim: The resistance of susceptible fish populations and the adaptive potential of heterogeneous biofilms, which cause multiple antibacterial resistance and long-term persistence of microorganisms, mediate the development and outcome of the infectious process. The study of the fish immunological parameters in interaction with biofilm-forming bacteria is of practical importance for assessing the stability of the homeostasis of the fish. This study aimed to determine the immunobiological parameters of Cyprinus carpio Linnaeus when interacting with biofilm-forming bacteria Aeromonas hydrophila. Materials and Methods: Clinically healthy fish C. carpio L. (Linnaeus, 1758) of both sexes, aged 4 years, and weighing 1.0-1.5 kg (n = 10), were used in this study. The fish were taken from the pond of the VNIIR experimental base in the period of 2020-2022. The standard method was employed to determine the phagocytic activity of blood cells, the total redox activity of neutrophils, and the bactericidal activity of blood serum. Results: After 24-48 h of cultivation in nutrient broth, the implementation of the processes of intercellular communication of bacteria had common patterns of formation of the heterogeneous structure of biofilms. Moreover, analyzing the optical density indices (density, D), it was observed that A. hydrophila was a strong producer of biofilms, as the optical density of the sample (density of sample, Ds) exceeded the optical density of the control (density of control, Dc) by more than 4 times (D = 0.464 ± 0.07). The ratio of the average number of microorganisms attached to the surface of one erythrocyte (average adhesion index) and the percentage (%) of erythrocytes having bacteria on their surface (adhesion coefficient [AC]) was 14.05 ± 0.72, and the adhesion index, AI was ≥4.00, indicating A. hydrophila to be highly adhesive. In addition, the AC of erythrocytes having bacteria on the surface was 14.05% ± 0.72%. A direct correlation was established (R2 = 0.94) between the AC (14.05% ± 0.11%-13.29% ± 0.08%) and the phagocytic index (11.3% ± 0.29%-32.0% ± 0.8%). The indicators of spontaneous nitro blue tetrazolium were 103.20 ± 11.70 when estimating the total redox activity of neutrophils. The optical density increased to 182.10 ± 21.12 with the addition of 20.0 mL of A. hydrophila bacteria (1 billion/mL) and the activity of neutrophils also increased. Conclusion: Among the markers of homeostasis stability, immunological indicators most fully reflect the mechanisms of initiation, development, and outcome of the infectious process mediated by the interaction of adhesive molecules of multicellular eukaryotes and adhesives of infectious disease pathogens. The research will contribute to further understanding the potential mechanism of quorum-sensing molecules and the search for new anti-adhesive drugs that reduce the formation of biofilms.

Liquid-crystalline ordering in bacterial cellulose produced by Gluconacetobaсter hansenii on glucose-containing media.

This research is dedicated to the studies of the microscale morphology of bacterial cellulose (BC) obtained by means of static cultivation of Gluconacetobacter hansenii GH-1/2008. We found that the microscale morphology depended on the BC production rate that was varied by using different glucose concentrations in the cultivation medium. It was revealed that at higher production rates, BC fibrils were aligned in a liquid-crystalline-like (LC-like) order. The observed helical alignment was always left-handed. The half-periods of the helix varied from 50 µm to 150 µm depending on the cultivation conditions. The mechanical and water absorption properties of the obtained BC pellicles were measured. The former correlated mainly with the density of the samples; the latter were the best for films with layered structure, where the BC had segregated into fleece sheets separated by gaps with low density of fibrils.

Enhancement of the antifungal activity of some antimycotics by farnesol and reduction of Candida albicans pathogenicity in a quail model experiment.

Background and Aim: Clinical strains of microorganisms, including pathogenic yeast-like fungi (YLF), are resistant to currently used antifungal agents. Thus, it is relevant to study the combinations of existing antimicrobial drugs and a medicinal extract of plant origin (farnesol). In previous studies, farnesol showed a relatively strong anti-biofilm effect against Candida albicans. This study aimed to determine how much the resistance profile of non-biofilm microorganisms can change. Materials and Methods: Six clinical isolates of C. albicans and one reference strain were used to study the interaction of farnesol with the most used antimycotics. To determine the sensitivity of YLF to antimycotic drugs, such as nystatin (50 µg), amphotericin B (10 µg), ketoconazole (10 µg), clotrimazole (10 µg), voriconazole (10 µg), fluconazole (25 µg), miconazole (10 µg), and intraconazole (10 µg), the classic disk diffusion method was used. In the second stage, one of the six strains was used to simulate candidiasis of the gastrointestinal tract in an in vivo quail model. As an unusual experimental design, this study investigated the effects of pretreated C. albicans in quails, not the in vivo pathogenicity of C. albicans, after treatment with farnesol. Results: The resistance profiles of Candida strains did not improve with farnesol in all strains. All concentrations of farnesol (100, 50, and 25 µM) demonstrated a fungistatic effect (i.e., an increase in drug sensitivity) in 23 of 56 (7×8) cases (41%). The remaining 54% demonstrated no changes in the resistance to antifungal drugs or deterioration of the indicators in rare cases (5%). At 100 µM farnesol, sensitivity improved in 33 of 56 cases (59%). Candidiasis or the severity of clinical disease of the quail digestive tract developed to a lesser extent if fungi were treated with farnesol. Conclusion: Farnesol does not always show a positive result on single cells without biofilm in the laboratory. However, in a biofilm or an in vivo model with biofilms, farnesol can be considered a new antimycotic drug or an additive to existing antimycotics.

Marine sediment analysis - A review of advanced approaches and practices focused on contaminants.

This review is aimed at critical analysis of current and emerging capabilities of analytical methods as employed for marine sediment analysis. An emphasis is given to the most reliable experimental strategies used to quantifying the various classes of contaminants and thus to acquiring analytical information that is relevant to assess the quality of sediments with regard to possible pollution of marine ecosystems. Advanced analytical methodology in use basically relies on the application of mass spectrometry to enable identification and quantification of hazardous chemical species, directly or after separation using the principles of gas and liquid chromatography. Also addressed are sample preparation techniques which - given the complexity of sediment matrices and the diverse and multiple nature of contaminants - are often a key for successful analysis. Among the trends in marine sediment analysis is an inclination to chemicals that are only recently recognized as emerging pollutants of very high concern, such as microplastics, pharmaceuticals and their metabolites.

Reduction in Pathogenicity in Yeast-like Fungi by Farnesol in Quail Model.

Candida albicans was the first eukaryotic microorganism to exhibit quorum-sensing through the secretion of the sesquiterpene E, farnesol. This molecule is generated by dephosphorylation of farnesyl pyrophosphate in the mevalonate biosynthetic pathway in mammalian and yeast cells. Exogenous farnesol inhibits yeast-to-hyphal formation in a concentration- and time-dependent manner at the earliest stage of hyphal development. Much research has been devoted to studying the role of farnesol as an inhibitor of hyphal morphogenesis; however, little research has been published regarding the in vivo impacts of farnesol on fungal virulence and the development of Candida infection. While other studies have examined the impact of multiple doses of farnesol in addition to antimycotics, we hypothesize that C. albicans treated with a single dose of this quorum-sensing molecule could reduce fungal virulence in a quail model.

Magnetic nanoparticles for highly robust, facile and efficient loading of metal-based drugs.

Direct interaction between iron oxide nanoparticles (IONs), modified with polyethylene glycol and an ionic liquid, and activated cisplatin drug resulted in a fast and high drug loading (up to 0.17 mol of platinum per gram of iron), and the payload does not strongly affect the magnetic properties of IONs and resists protein adsorption in human serum environment. For another, developmental metal-based drug, tris(8-quinolinolato)gallium(III), binding to the IONs allowed for overcoming the disadvantages of low solubility and incompatibility with intravenous administration. The potential of IONs as a magnetic nanoformulation for smart drug delivery has been confirmed by the release of both metallodrugs under conditions relevant to cancer cytosol.