Acid Release Research Articles

Alginate-Based Carriers Loaded with Mulberry (Morus alba L.) Leaf Extract: A Promising Strategy for Prolonging 1-Deoxynojirimicyn (DNJ) Systemic Activity for the Nutraceutical Management of Hyperglycemic Conditions.

The iminosugar 1-deoxynojirimicyn (DNJ) contained in mulberry leaves has displayed systemic beneficial effects against disorders of carbohydrate metabolism. Nevertheless, its effect is impaired by the short half-life. Alginate-based carriers were developed to encapsulate a DNJ-rich mulberry extract: Ca-alginate beads, obtained by external gelation, and spray-dried alginate microparticles (SDMs). Mean size and distribution, morphology, drug loading, encapsulation efficiency, experimental yield, and release characteristics were determined for the two formulations. Ca-alginate beads and SDMs exhibited an encapsulation efficiency of about 54% and 98%, respectively, and a DNJ loading in the range of 0.43-0.63 μg/mg. The in vitro release study demonstrated the carriers' capability in controlling the DNJ release in acid and basic conditions (<50% in 5 h), due to electrostatic interactions, which were demonstrated by 1H-NMR relaxometry studies. Thus, alginate-based particles proved to be promising strategies for producing food supplements containing mulberry leaf extracts for the management of hyperglycemic state.

A strategy for source control of acid mine drainage by intelligent management of mine wastes

For mine site management, the release of acid and heavy metal ions from sulfur-containing waste rock or tailings (principally chalcopyrite and pyrite) under natural deposit conditions is a major environmental problem. In this study, the interaction between chalcopyrite and pyrite at different mass ratios under a simulated acid mine drainage environment was investigated. The dissolution experiments showed that a low proportion of pyrite promotes chalcopyrite dissolution, while a high proportion inhibits dissolution. However, this phenomenon is weakened by the presence of microorganisms. In addition, the combined characterization by X-ray diffraction spectroscopy, Fourier transform infrared spectroscopy, and Raman spectroscopy indicated that a high ratio of pyrite incorporation facilitated the formation of passivation layers on the chalcopyrite surface. Scanning electron microscopy results show that many oxidation etching pits are found on the surface of the chalcopyrite residues surface in a low ratio of pyrite addition, whereas numerous islands are observed and tightly wrapped around the surface of the chalcopyrite residues surface in a high ratio of pyrite addition. The current work presents a viable, practical approach to tailings stacking that reduces the release of the heavy metal ions copper and acid through the appropriate proportioning of ores.

Revealing the phosphate-solubilizing characteristics and mechanisms of the plant growth-promoting bacterium Agrobacterium deltaense C1.

This study explores the phosphate (Pi)-solubilizing characteristics and mechanisms of a novel phosphate-solubilizing bacterium, Agrobacterium deltaense C1 (C1 hereafter). The growth-promoting effects of C1 were investigated by gnotobiotic experiments, and the Pi-solubilizing mechanism was revealed by extracellular metabolomics, liquid chromatography analysis, and reverse transcription quantitative polymerase chain reaction. Results showed that C1 significantly increased Arabidopsis biomass and total phosphorus (P) content under P deficiency. Under Ca3(PO4)2 condition, the presence of C1 resulted in a significant and negative correlation between available P content and medium pH changes, implying that Pi dissolution occurs through acid release. Metabolomics revealed C1's ability to release 99 organic acids, with gluconic acid (GA), citric acid, and α-ketoglutaric acid contributing 64.86%, 9.58%, and 0.94%, respectively, to Pi solubilization. These acids were significantly induced by P deficiency. Moreover, C1's Pi solubilization may remain significant even in the presence of available P, as evidenced by substantial pH reduction and high gcd gene expression. Additionally, C1 produced over 10 plant growth-promoting substances. C1 dissolves Pi primarily by releasing GA, which enhances plant growth under P deficiency. Notably, its Pi solubilization effect is not significantly limited by available Pi.

Effect of 38% Silver Diamine Fluoride on Salivary Matrix Metalloproteinase-9 Levels in Children with Early Childhood Caries: A Clinical Study.

Early childhood caries is a major oral health problem in most industrialized countries, affecting the overall quality of life of children. It is caused by the action of bacterial acids on the enamel surface thereby demineralizing it and progressively destroying the tooth. It presents initially as smooth-surface carious lesions affecting the primary maxillary incisors. With the advancement of the lesion, decay progresses further to involve other primary teeth as well and if not treated early, the caries may involve the pulp leading to irreversible pulpitis. Matrix metalloproteinases (MMPs) are a group of endopeptidases that degrade almost all the proteins of the extracellular matrix (ECM). Among the different types of MMP, MMP-9 (gelatinase B) is one of the chief MMPs responsible for the breakdown of the organic matrix. Traces of MMP-9 can be found in the human carious lesions, saliva, and gingival crevicular fluid. They are activated by the release of acids by cariogenic bacteria and once activated they are able to digest demineralized dentin matrix. Thus, host-derived MMPs, which are activated by bacterial acids have a crucial role in the destruction of dentine by caries. Thus, this study was undertaken to investigate the effect of 38% silver diamine fluoride (SDF) solution on MMP-9 levels. This clinical trial investigated the MMP-9 levels before and after the application of 38% SDF in children with early childhood caries. About 15 children were selected and were subjected to clinical and radiographic assessment before the commencement of the procedure. After the collection of saliva, the teeth with carious lesions were isolated and SDF was applied. Saliva samples were again collected after 1, 3, and 6 months postapplication of SDF. The collected saliva samples were then analyzed for their MMP-9 levels using a human salivary enzyme-linked immunosorbent assay (ELISA) kit. Finally, the data obtained were subjected to statistical analysis by repeated measures of analysis of variance (ANOVA). The MMP-9 levels were found to be gradually increasing postapplication of 38% SDF and were significantly higher after 6 months and the highest mean difference in the MMP-9 levels was observed between baseline and 6th-month follow-up. Also, no new carious lesion appeared in the teeth during the experimental time period of 6 months and the decayed, extraction needed, filled teeth (deft) scores remained the same. Bora P, Saxena A, Goswami M. Effect of 38% Silver Diamine Fluoride on Salivary Matrix Metalloproteinase-9 Levels in Children with Early Childhood Caries: A Clinical Study. Int J Clin Pediatr Dent 2023;16(S-1):S51-S56.

Key Design Features of Lipid Nanoparticles and Electrostatic Charge-Based Lipid Nanoparticle Targeting.

Lipid nanoparticles (LNP) have gained much attention after the approval of mRNA COVID-19 vaccines. The considerable number of currently ongoing clinical studies are testament to this fact. These efforts towards the development of LNPs warrant an insight into the fundamental developmental aspects of such systems. In this review, we discuss the key design aspects that confer efficacy to a LNP delivery system, i.e., potency, biodegradability, and immunogenicity. We also cover the underlying considerations regarding the route of administration and targeting of LNPs to hepatic and non-hepatic targets. Furthermore, since LNP efficacy is also a function of drug/nucleic acid release within endosomes, we take a holistic view of charged-based targeting approaches of LNPs not only in the context of endosomal escape but also in relation to other comparable target cell internalization strategies. Electrostatic charge-based interactions have been used in the past as a potential strategy to enhance the drug release from pH-sensitive liposomes. In this review, we cover such strategies around endosomal escape and cell internalization in low pH tumor micro-environments.

Phytopathogenic Bacteria Associated with Bacterioses of Common Oak (Quercus robur L.) in Ukraine

Studying the biological characteristics of the causative agents of bacteriosis of the common oak (Quercus robur L.) (to highlight the links between the key factors of pathogenesis and bacterial groups) is a new and relevant area of research. This work aims to identify the species composition of phytopathogenic bacteria associated with common oak bacteriosis and to study the morphological, cultural, and biochemical properties of pathogens. To establish the general phytosanitary state of the surveyed stands, classical forest inventory and phytopathological (visual on based on typical symptoms of the disease and macroscopic) methods were used. The properties of isolated bacteria were studied using microbiological methods. The weakening and dieback of common oak in the forests of Ukraine is directly related to four types of bacterioses and their pathogens: the soft bacterial rot of acorns (Pectobacterium carotovorum subsp. carotovorum, bacterial wetwood (Lelliottia nimipressuralis), dry rot of branches and trunks (Erwinia rhapontici), and canker disease (Pseudomonas fluorescens and Pseudomonas sp.). Research on the correspondence between the biological properties of common oak bacteriosis pathogens has established that the synthesis of pectin-degrading enzymes and the ability to ferment with the release of acid and gas in many carbohydrate media by phytopathogenic bacteria is the main characteristic. This ensures the intensity and typical symptoms of the pathogenesis of a particular bacteriosis.

Long-Term Sustainability of Marble Waste Sludge in Reducing Soil Acidity and Heavy Metal Release in a Contaminated Mine Technosol

A field-based experiment was set up to evaluate the effectiveness of a single application of marble waste sludge (MWS) on chemical immobilization of potentially hazardous trace elements (PHE) within the soil profile of a mine Technosol under natural assisted remediation for 12 years. Results showed that MWS amendment significantly reduced soil acidity and PHE mobility compared to unamended soil, thus improving soil health and plant growth. The amendment application had a sustained acid-neutralizing action, as soil pH remains relatively constant at between 5.8 and 6.4 throughout the entire profile (70 cm depth). In addition to diluting pollutants, the treatment triggered a redistribution of trace elements among the various operationally defined geochemical pools, shifting the PHE speciation from water-soluble forms to fractions associated with carbonates (29% Cd), metal oxides (40–48% Zn, Cd, Cu, and Ni), organic matter (22% Cu and Ni), and insoluble secondary oxidation minerals and residual phases (80–99% As, Cr, Sb, Tl, and Pb), thereby effectively limiting its potential environmental significance. MWS treatment to immobilize PHE in the contaminated mine Technosol was effective and persistent while in the untreated soil metal release is continuing over time.

Abstract 1089: Targeting amino acid uptake in lung squamous cell carcinomas to improve response to targeted therapies

Abstract Lung squamous cell carcinomas (LUSC) are a subtype of non-small cell lung cancer characterized by poor overall survival. LUSC are highly aggressive in part due to their high metabolic activity, with uptake of high levels of glucose supporting their growth and proliferation. The main driver of high rate of glycolysis in LUSC is elevated expression of glucose transporter GLUT1, whose levels and membrane localization are regulated by activated PI3K-AKT-mTOR pathway. The Cancer Genome Atlas revealed that LUSC have high tumor mutational burden with varied genetic profile that includes amplification of receptor tyrosine kinases (RTKs), PI3KCA, and a loss of PTEN. These alterations lead to increased activity of mTOR pathway, one of the major pathways in cancer cells that drives cell proliferation and metabolism. We have recently demonstrated that catalytic mTOR kinase inhibitor TAK228 (MLN128) inhibits glycolysis in LUSC cell lines in vitro, in xenografts of human LUSC lines, in patient derived xenografts (PDXs) and genetically engineered mouse models. However, despite lowered glucose uptake measured by 18F-FDG signal LUSC tumors were able to maintain high levels of proliferation. Tumors were able to adapt to prolonged treatment with TAK228 by relying on glutaminolysis. Increased glutaminolysis was due to increased uptake of glutamine as well as increased levels of glutaminase (GLS), a key enzyme that converts glutamine to glutamate. Inhibiting both mTOR (with TAK228) and GLS (with CB-839) resulted in reduced proliferation index and lower tumor volume. However, while combination therapy halted tumor growth, there was a lack of tumor regression in xenografts and PDXs of LUSC. Therefore, tumors are poised to further adapt to combination therapy through metabolism of additional amino acids beyond glutamine. Here we show that macropinocytosis, a form of endocytosis that allows cancer cells to uptake extracellular fluids and further process solutes and macromolecules in lysosomes leading to the release of amino acids inside the cytoplasm, is upregulated in LUSC tumors that are resistant to TAK228. Macropinocytosis is induced by active RTKs, PI3KCA, Ras, loss of PTEN, and active NRF2 pathway - oncogenic alterations commonly found in LUSC tumors. This suggests that macropinocytosis might be a mechanism that supports amino acid metabolism utilized by LUSC in order to escape mTOR therapy. Basal levels of macropinocytosis in LUSC appear low, however, upon treatment with mTOR inhibitors, lysosomal catabolism of macropinocytosed proteins increases, allowing tumor cells to increase their proliferation. Resistance to targeted therapies is a major hurdle to achieving effective therapies in multiple cancer types. Identifying ways to overcome resistance to targeted therapies would allow for longer therapeutic response for larger number of patients, ultimately leading to longer survival and better quality of life. Citation Format: Milica Momcilovic, David Shackelford. Targeting amino acid uptake in lung squamous cell carcinomas to improve response to targeted therapies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1089.

Tibolone Pre-Treatment Ameliorates the Dysregulation of Protein Translation and Transport Generated by Palmitic Acid-Induced Lipotoxicity in Human Astrocytes: A Label-Free MS-Based Proteomics and Network Analysis.

Excessive accumulation and release of fatty acids (FAs) in adipose and non-adipose tissue are characteristic of obesity and are associated with the leading causes of death worldwide. Chronic exposure to high concentrations of FAs such as palmitic acid (pal) is a risk factor for developing different neurodegenerative diseases (NDs) through several mechanisms. In the brain, astrocytic dysregulation plays an essential role in detrimental processes like metabolic inflammatory state, oxidative stress, endoplasmic reticulum stress, and autophagy impairment. Evidence shows that tibolone, a synthetic steroid, induces neuroprotective effects, but its molecular mechanisms upon exposure to pal remain largely unknown. Due to the capacity of identifying changes in the whole data-set of proteins and their interaction allowing a deeper understanding, we used a proteomic approach on normal human astrocytes under supraphysiological levels of pal as a model to induce cytotoxicity, finding changes of expression in proteins related to translation, transport, autophagy, and apoptosis. Additionally, tibolone pre-treatment showed protective effects by restoring those same pal-altered processes and increasing the expression of proteins from cell survival processes. Interestingly, ARF3 and IPO7 were identified as relevant proteins, presenting a high weight in the protein-protein interaction network and significant differences in expression levels. These proteins are related to transport and translation processes, and their expression was restored by tibolone. This work suggests that the damage caused by pal in astrocytes simultaneously involves different mechanisms that the tibolone can partially revert, making tibolone interesting for further research to understand how to modulate these damages.

Influence of the Human Lipidome on Epicardial Fat Volume in Mexican American Individuals.

IntroductionCardiovascular disease (CVD) is the leading cause of mortality worldwide and is the leading cause of death in the US. Lipid dysregulation is a well-known precursor to metabolic diseases, including CVD. There is a growing body of literature that suggests MRI-derived epicardial fat volume, or epicardial adipose tissue (EAT) volume, is linked to the development of coronary artery disease. Interestingly, epicardial fat is also actively involved in lipid and energy homeostasis, with epicardial adipose tissue having a greater capacity for release and uptake of free fatty acids. However, there is a scarcity of knowledge on the influence of plasma lipids on EAT volume.AimThe focus of this study is on the identification of novel lipidomic species associated with CMRI-derived measures of epicardial fat in Mexican American individuals.MethodsWe performed lipidomic profiling on 200 Mexican American individuals. High-throughput mass spectrometry enabled rapid capture of precise lipidomic profiles, providing measures of 799 unique species from circulating plasma samples. Because of our extended pedigree design, we utilized a standard quantitative genetic linear mixed model analysis to determine whether lipids were correlated with EAT by formally testing for association between each lipid species and the CMRI epicardial fat phenotype.ResultsAfter correction for multiple testing using the FDR approach, we identified 135 lipid species showing significant association with epicardial fat. Of those, 131 lipid species were positively correlated with EAT, where increased circulating lipid levels were correlated with increased epicardial fat. Interestingly, the top 10 lipid species associated with an increased epicardial fat volume were from the deoxyceramide (Cer(m)) and triacylglycerol (TG) families. Deoxyceramides are atypical and neurotoxic sphingolipids. Triacylglycerols are an abundant lipid class and comprise the bulk of storage fat in tissues. Pathologically elevated TG and Cer(m) levels are related to CVD risk and, in our study, to EAT volume.ConclusionOur results indicate that specific lipid abnormalities such as enriched saturated triacylglycerols and the presence of toxic ceramides Cer(m) in plasma of our individuals could precede CVD with increased EAT volume.

Facile fabrication of pH-controlled drug release mat via engineering 3D reversible gel-like nanofibers

The drug release system is emerging as a novel dosage form for multipurpose prevention against the undesired cytotoxic side effect caused by large doses of oral administration via the site-specific and on-demand control of drugs. Herein, a drug release system with a large dose of encapsulation-free drugs loading and site-specific controlled release was facilely built via engineering 3D reversible gel-like nanofibers based on pH-responsive copolymer containing sensitive photo-crosslinker and stiffness tunable polymer. This strategy can be used to address the case-by-case issue of drugs loaded in the matrix via in-situ-trapping drugs in the crosslinked gel-like nanofibers. The cumulative release profiles and release kinetics upon different pH indicate that 3D reversible gel-like nanofibrous mat can stably control the drug release for more than 80 h. Moreover, the 3D nanofibrous release system behaves sustained and pH-controlled release of drugs, thereby contributing to satisfying targeted drug release therapy for weakly acidic pathological tissues. • Copolymers capable of UV initiating crosslinking and pH responses are synthesized. • A drug release system loading with megadose encapsulation-free drugs was prepared. • Engineered 3D reversible nanofibers achieve site-specific drug release in acid. • Nanofibrous mat can stably control the drug release for more than 80 h. • Two different kinetic equations fit the bimodal of the release curve in pH 6.4 PBS.

Laboratory Simulation of Groundwater Along Uranium-Mining-Affected Flow Paths Near the Grand Canyon, Arizona, USA

Mining of volumetrically small, but relatively enriched (average 0.6% U3O8) breccia pipe uranium (BPU) deposits near the Grand Canyon, Arizona, USA has the potential to affect groundwater and springs in the area. Such deposits also contain base metal sulfides that can oxidize to generate acid mine drainage and release trace metals. In this study, sequential batch experiments were conducted to simulate the geochemistry of local shallow groundwater that contacts BPU ore and then moves downgradient through sedimentary strata. The experiments simulated shallow groundwater in a carbonate aquifer followed by contact with BPU ore. The experiments subsequently simulated contact with sedimentary rocks and changing oxygen availability. Concentrations of several contaminants of potential concern became substantially elevated in the waters exposed to BPU ore, including As, Co, Ni, U, and Zn, and to a lesser extent, Mo. Of these, Co, Mo, Ni, and U were minimally attenuated by downgradient processes, whereas Zn was partially attenuated. Sb and Tl concentrations were more moderately elevated but also generally minimally attenuated. Although the mixture of elements is particular to these BPU ore deposits, sulfide oxidation in the ore and carbonate buffering of pH by sedimentary rocks generates patterns of water chemistry common in acid mine drainage settings. Ultimately, downgradient concentrations of elements sourced from BPU ore will also be strongly influenced by non-geochemical factors such as the quantities of water contacting BPU materials, heterogeneity of materials along flow paths, and mixing with waters that have not contacted BPU materials.

Substance P Increases the Excitability of Dorsal Motor Nucleus of the Vagus Nerve via Inhibition of Potassium Channels

Increases in the substance P (SP) concentration in the medial portion of the dorsal motor nucleus of the vagus nerve (mDMV) in the brainstem are closely associated with chemotherapy induced nausea and vomiting (CINV). However, the underlying cellular and molecular mechanisms of action are not well understood. In this study, we investigated the effects of SP on mDMV neurons using whole-cell patch-clamp recordings from rat brainstem slices. Application of different concentrations of SP induced tonic and phasic responses. Submicromolar concentrations of induced an inward shift of the holding current by increasing membrane input resistance. The response was mimicked by acidification of the extracellular solution and inhibited by a neurokinin type 1 receptor antagonist. These responses have equilibrium potentials close to the K+ equilibrium potential. In addition, a TWIK-related acid-sensitive K+ channel 3 (TASK-3) inhibitor, PK-THPP, induced responses similar to those produced by submicromolar SP concentrations. Micromolar concentrations of SP facilitated γ-aminobutyric acid (GABA) release but diminished glutamate release; these changes were blocked by a GABAB receptor antagonist and a neurokinin type 3 receptor antagonist, respectively. In current-clamp recordings, submicromolar SP concentrations increased neuronal excitability by depolarizing membrane potentials. However, neither the increase in SP concentration to the micromolar range nor the addition of GABAA and ionotropic glutamate receptor antagonists affected neuronal excitability. Thus, SP increases the excitability of mDMV neurons by inhibiting K+ conductance.

Hypothesis: Enhanced glucose availability and insulin resistance enhances an activated immune system and accounts for the obesity paradox.

Many studies have demonstrated an 'obesity paradox' where people with obesity have reduced mortality in the context of acute critical illnesses compared to people of normal weight. In contrast, obesity is associated with reduced life expectancy in the population in general and is associated with an increased risk for type 2 diabetes, cardiovascular disease and other health problems. However, the absence of the metabolic syndrome is associated a lower mortality than when the metabolic syndrome is present regardless of body mass index status and the obesity paradox appears to only occur in association with the metabolic syndrome, but cardiorespiratory fitness modifies these outcomes. Enhanced glucose availability is important when the immune system is activated not only because it has an acute onset, a high consumption of glucose and is substantially an obligate glucose utilizer but also because it has priority over most other tissues and cells for the available glucose. Thus, for vulnerable populations, such as children with severe infections, this increases the risk of hypoglycaemia and death. The obesity paradox may be substantially a consequence of two features associated with obesity. One is endogenous glucose production (EGP). Obesity is associated with an increased capacity for EGP and thus is associated with enhanced glucose availability. Second is insulin resistance that reduces the amount of glucose metabolized by cells that are not obligate glucose utilizers and increases the release of fatty acids and glycerol from adipose stores that are alternative fuels for tissues and cells.

Effect of the Application of Cold Plasma Energy on the Inactivation of Microorganisms, Proteins, and Lipids Deterioration in Adobera Cheese

Cheeses are perishable foods that must fulfill sanitary and quality requirements according to the parameters established globally. Plasma as a nonthermal inactivation technique has been a current research topic for food preservation, so the objective of this work was to study the effect of plasma energy against microorganisms in Adobera cheese (traditional Mexican cheese) as well as evaluate the possible degradation of lipids and protein. 108 CFU/mL of Escherichia coli ATCC 25922, Salmonella ATCC13076, and Staphylococcus aureus ATCC 6538 were inoculated at 0.5 g of Adobera cheese and were subjected to an energy of 30 volts, in a dielectric barrier discharge reactor (DBDR) at intervals of times 1, 3, 5, 7, 10, and 15 min. A flow of a mixture of air and helium at 96% purity was used. The decimal reduction time (D) was determined, and the oxidation of proteins and lipids was analyzed after each treatment. The results showed an annihilating effect of plasma on the indicator bacteria under study, and a reduction of 5 logarithmic cycles was obtained. The maximum degree of lipid oxidation was 23 acid degree values (ADV) after 7 min of exposure to plasma. The oxidation of proteins showed a direct and proportional relationship between the formation of carbonyl groups with the percentage significant loss to the concentration of carbonyl groups with the concentration of protein oxidation, after 3 min of exposure to cold plasma levels of 82% and 99% oxidation of Adobera cheese protein and free casein, respectively. We conclude that the plasma energy applied to Adobera cheese is an effective treatment to inactivate bacteria. However, there is the possibility of causing changes in taste and odor, due to the release of fatty acids and the oxidation of proteins.

Zinc oxide nanoparticles dissolution and toxicity enhancement by polystyrene microplastics under sunlight irradiation

Zinc oxide nanoparticles (ZnO NPs) dissolution is a critical process for the transformation and toxicity of ZnO NPs in aquatic environments. However, the effect of microplastics (MPs) on dissolution and toxicity of ZnO NPs under sunlight irradiation is still lacking. Herein, the dramatic increase in sunlight-induced ZnO NPs dissolution by polystyrene (PS) MPs was proven, which was attributed to the increase in h+-dependent and proton-dependent ZnO NPs dissolution by PS MPs, yielding 1O2 generation inhibition and acid release, respectively. The sizes, functional groups and aging status of PS MPs and pH were characteristic ZnO NPs dissolution through modifying 1O2, •OH and O2•− generation and acid release. Furthermore, the ZnO NPs dissolution affected by PS MPs also occurred in three realistic water samples, which were mainly governed by dissolved organic matter (DOM) and CO32−, rather than Cl− or SO42−. The PS MPs (1 μg/mL) dramatically altered the Zn2+:ZnO ratio in ZnO NPs suspension after 96 h of sunlight irradiation and presented vehicle effects on Zn2+, which in turn significantly increased the ion-related toxicity of ZnO NPs to Daphnia magna. Based on the PS MPs enhanced dissolution and toxicity of ZnO NPs, the effects of PS MPs on the environmental risk assessment of ZnO NPs should be seriously considered in freshwater environments under sunlight irradiation.

Can acids produced from probiotics demineralize the tooth and cause progression of caries: a critical review

Background: Probiotics are live microorganisms which that provide various health benefits to the host upon administration in adequate amounts. Lactobacilli, Propionibacterium, and Bifidobacterium are common “Lactic Acid-producing bacteria (LAB)” present in various probiotic formulations. These probiotic bacteria release many organic acids, mainly lactic acid, acetic acid, and propionic acid into their surrounding environment. Increased concentration of these inorganic and organic acids reduces the saliva’s critical pH to below 5.5, and initiates demineralization. Thus, the present review aims to critically appraise the existing evidence on this emerging clinical perspective and double edged nature of the probiotic bacteria, and explain as to how probiotic supplements increase the risk of tooth decay. Results: Lactobacilli and Bifidobacterium were associated with rampant caries in preschool children and progression of caries. All probiotics were acidogenic as they decreased the pH of the saliva, demineralized and eroded the enamel. Probiotics also release extracellular polysaccharides that help to release essential elements like calcium and phosphorous from the enamel surface. The lactic acid-producing efficiency of probiotics is increased when combined with supragingival plaque. Low pH was attributed to the interaction of Lactobacilli with other microorganisms. Conclusion: Acids release from probiotics bacteria can lower the critical pH of the oral cavity to below five, and play a role in demineralization of the tooth and progression of caries.

Occurrence, Genesis, and Significance of Analcime in Fine-Grained Sedimentary Rocks

Natural analcime, an aluminosilicate mineral with multiple genetic mechanisms, widely occurs in fine-grained sedimentary reservoirs rich in oil and gas. Researchers have discussed the source and formation mechanism of reservoirs and the influence of morphology formation, occurrence characteristics associated with minerals, geochemical data, and Si/Al ratio on reservoir properties. The occurrence location, particle size, automorphism, purity, and fracture development can indicate the source of analcime macroscopically. The correlation between the enrichment of associated minerals and the content of analcime indicates that the associated mineral assemblage or correlation provides a material source for the formation of analcime or effectively improves the formation environment. Geochemical data are often used to identify analcime related to primary magmatic crystallization and hydrothermal processes. The genetic source grouping scheme based on the Si/Al ratio, which is a traditional means to identify the source of analcime, has been widely used in the research on analcime. After more than 200 years of study, research has shown that analcime distributed in fine-grained sedimentary rocks was mainly formed by burial alteration of volcanic materials (V-type analcime), conversion of nontuffaceous materials (N-type analcime), hydrothermal deposition mineralization (H-type analcime), and precipitation directly from an alkaline lake or pore water (P-type analcime). Based on reservoir properties, analcime that formed before the organic acid release stage of source rocks can effectively improve the porosity through precipitation–dissolution mechanisms after the release of massive organic acid, whereas the cementation formed by the transition of the fluid from acid to alkaline during the intermediate diagenetic stage would reduce porosity to some extent.

Keratinolytic bacteria from the feathers of wild Dark-eyed Juncos (Junco hyemalis)

We collected &gt;300 bacterial isolates from overwintering Dark-eyed Juncos ( Junco hyemalis) to find that ∼40% appear to degrade the structural protein of feathers using extracellular keratinase enzymes. A guild of bacteria (∼18% of total counts) grew significantly better on basal salt medium (BSM) plates containing feather meal than on BSM agar-only plates (∼8% total counts). The genus-level profile of the 107 most active keratinolytic bacterial isolates shows that nearly half are Bacillus species. Keratinolytic Frigoribacterium, Microbacterium, Okibacterium, Pantoea, Sphingomonas, Staphylococcus, and Stenotrophomonas were found, among others. Active isolates were shown to degrade whole feathers, used feather meal as a sole carbon and energy source, and produced zones of clearing indicative of extracellular proteases on milk agar plates. Our novel in vitro keratinase assay uses ninhydrin to quantitate the release of amino acids from exogenously added keratin, with Bacillus licheniformis str. ATCC 14580 serving as a positive control. Keratinolytic isolates were grown in the presence of feather meal to induce keratinase release and this conditioned medium, called the enzyme extract, was clarified by centrifugation and filtration. The enzyme reaction was completed in 30 min and was positively correlated with the amount of extract added, until reaching color saturation. Bacillus pumilus str. F166 was the most active isolate and Bacillus cereus str. F65 was about half as active as the positive control. Bacillus cereus str. F27 performed well too. We also have demonstrated strong keratinolytic activity against raw wool α-keratin. Juncos are long-distance migrant birds that carry bacteria on their feathers, both beneficial and harmful to plants. The abundant keratinolytic bacteria on feathers are capable of structurally damaging the feathers, potentially reducing bird fitness and reproductive success. Keratinases have uses in tanning, silage, and remediation. Keratinases may be useful in the treatment of onychomycoses and actinic keratoses in medical and veterinary settings.

Polystyrene microplastics sunlight-induce oxidative dissolution, chemical transformation and toxicity enhancement of silver nanoparticles

The coexistence of microplastics (MPs) and nanomaterials has been increasingly studied, but the influence of MPs on the chemical transformation of nanomaterials remains unclear. Herein, it was demonstrated that polystyrene (PS) MPs induce the oxidative dissolution, transformation and toxicity of silver nanoparticles (Ag NPs) under simulated sunlight irradiation. The PS MPs induced the oxidation dissolution of pristine Ag NPs by 1O2, OH and/or acid release and simultaneously reduced the released Ag+ to secondary Ag NPs by O2−. The sizes, functional groups and ageing status of the PS MPs and pH characterized secondary Ag NPs formation. Secondary formation of Ag NPs induced by PS MPs also occurred in realistic water and was governed by dissolved organic matter (DOM) and Cl−, rather than SO42− or CO32−. Moreover, PS MPs remarkably promoted Ag+ release, altered the Ag+:Ag0 ratio, and presented vehicle effects on Ag+ toxicity to Daphnia magna. The concentration addition model demonstrated that the ion-related toxicity of Ag NPs was significantly increased by PS MPs. Therefore, PS MPs induced the oxidative dissolution, transformation and toxicity enhancement of Ag NPs under sunlight irradiation, and accordingly, the coexistence of PS MPs and Ag NPs in freshwater environments should be seriously considered.