Effect of citric acid on cell membrane structure and function of Issatchenkia terricola WJL-G4.

AIMS: This study aimed to investigate the changes of cell membrane structure and function of Issatchenkia terricola under citric acid by performing physiological analysis. METHODS AND RESULTS: The membrane integrity, surface hydrophobicity, structure, fluidity, apoptosis, and fatty acid methyl esters composition of I. terricola WJL-G4 cells were determined by propidium iodide staining, microbial adhesion to hydrocarbon test, transmission electron microscopy analysis, fluorescence anisotropy, flow cytometry, and gas chromatography-mass, respectively. The results showed that with the increasing of citric acid concentrations, the cell vitality, membrane integrity, and fluidity of I. terricola reduced; meanwhile, apoptosis rate, membrane permeable, hydrophobicity, and ergosterol contents augmented significantly. Compared to control, the activities of Na+, K+-ATPase, and Ca2+, Mg2+-ATPase increased by 3.73-fold and 6.70-fold, respectively, when citric acid concentration increased to 20 g l-1. The cells cracked and their cytoplasm effused when the citric acid concentration reached 80 g l-1. CONCLUSIONS: I. terricola could successfully adjust its membrane structure and function below 60 g l-1 of citric acid. However, for citric acid concentrations above 80 g l-1, its structure and function were dramatically changed, which might result in reduced functionality.

Monocytes as Targets for Immunomodulation by Regional Citrate Anticoagulation.

Immune alterations in end-stage renal patients receiving hemodialysis are complex and predispose patients to infections. Anticoagulation may also play an immunomodulatory role in addition to the accumulation of uremic toxins and the effects of the dialysis procedure. Accordingly, it has been recently shown that the infection rate increases in patients under regional citrate anticoagulation (RCA) compared with systemic heparin anticoagulation (SHA). We hypothesized that RCA affects the immune status of hemodialysis patients by targeting monocytes. In a cohort of 38 end-stage renal patients undergoing hemodialysis, we demonstrated that whole blood monocytes of patients receiving RCA-but not SHA-failed to upregulate surface activation markers, like human leukocyte antigen class II (HLA-DR), after stressful insults, indicating a state of deactivation during and immediately after dialysis. Additionally, RNA sequencing (RNA-seq) data and gene set enrichment analysis of pre-dialysis monocytes evidenced a great and complex difference between the groups given that, in the RCA group, monocytes displayed a dramatic transcriptional change with increased expression of genes related to the cell cycle regulation, cellular metabolism, and cytokine signaling, compatible with the reprogramming of the immune response. Transcriptomic changes in pre-dialysis monocytes signalize the lasting nature of the RCA-related effects, suggesting that monocytes are affected even beyond the dialysis session. Furthermore, these findings demonstrate that RCA-but not SHA-impairs the response of monocytes to activation stimuli and alters the immune status of these patients with potential clinical implications.

Five days serum glucose stability at room-temperature in centrifuged fast-clotting serum tubes and the comparability with glucose in heparin-plasma and plasma containing citrate-stabilizer.

Glucose measurement plays a central role in the diagnosis of gestational diabetes mellitus (GDM). Because of earlier reports of overestimation of glucose in the widely used tubes containing granulated glycolysis inhibitor, the study assessed the performance of fast-clotting serum tubes as an alternative sample for the measurement of glucose. Glucose concentration in fast-clotting serum was compared to lithium-heparin plasma placed in an ice-water slurry after sample collection and glucose stability at room-temperature was studied. Blood samples from 30 volunteers were drawn in four different types of tubes (serum separator tubes, fast-clotting serum tubes, lithium-heparin tubes and sodium fluoride, EDTA and a citrate buffer (NaF-EDTA-citrate) tubes, all from Greiner Bio-One). Lithium-heparin tubes were placed in an ice-water slurry until centrifugation in accordance with international recommendations and centrifuged within 10 min. After centrifugation, glucose was measured in all tubes (timepoint T0) and after 24, 48, 72, 96 and 120 h of storage at 20-22 °C. NaF-EDTA-citrate plasma showed significant overestimation of glucose concentration by 4.7% compared to lithium-heparin plasma; fast-clotting serum showed glucose concentrations clinically equivalent to lithium-heparin plasma. In fast-clotting serum tubes, mean bias between glucose concentration after 24, 48, 72, 96 and 120 h and T0 was less than 2.4%. All individual differences compared to T0 were less than 6.5%. The results fulfill the acceptance criteria for sample stability based on biological variation. Fast-clotting serum tubes can be an alternative for the measurement of glucose in diagnosis and management of GDM and diabetes mellitus, especially when prolonged transportation is necessary.

Cadaver preservative properties of a solution composed of honey, ethyl alcohol, liquid paraffin, distilled water and citric acid: Experiments on rabbit cadavers.

The objective of this study is to assess the efficacy of a solution including honey, ethyl alcohol, liquid paraffin, distilled water and citric acid (HEFS) as a preservative for rabbit cadavers, serving as a potential substitute for formaldehyde. The cadavers underwent preservation using three distinct solutions: 10% formalin, 35% alcohol and HEFS. The cadavers were subjected to a total of four sampling events, occurring at 4-month intervals, in order to collect specimens for microanatomical, histological, microbiological, mycological, colourimetric, texture and odour analysis. In terms of hardness, suitability for dissection and joint mobility metrics, the cadavers fixed with HEFS had superior qualities to those fixed with formalin. The fixation quality of HEFS for histological analyses was deemed acceptable, except kidney and intestinal tissues. In texture analysis, differences only in the elasticity parameter (p < 0.05) in the same sampling period. A total of 10 (13.9) bacteria isolates were identified among which, Metasolibacillus meyeri 3 (30%) was predominantly followed by Staphylococcus aureus 2 (20%), Bacillus siamensis, Bacillus subtilis, Pseudarthrobacter oxydans, Bacillus licheniformis, Bacillus subtilis subsp. subtilis with a proportion of 1 (10%), respectively, by both microbiological and molecular analysis. However, no anaerobic bacteria and fungi were isolated. A considerable percentage of the students had the perception that HEFS was appropriate for utilization in laboratory settings due to its absence of unpleasant odours and detrimental impact on ocular and respiratory functions. In conclusion, we consider that HEFS may serve as a viable substitute for formalin solution in the preservation of rabbit cadavers.

Iron oxide nanoparticles improving multimetal phytoextraction in Helianthus annuus.

This study assessed the phytotoxicity of a mixture of five different trace elements (TEs) frequently found as pollutants in soils: arsenic, cadmium, copper, lead and zinc. On the other hand, the plant response to a magnetite (Fe3O4) nanoparticle amendment on this mixture as well as nanomagnetite remediation potential has been tested. Sunflower (Helianthus annuus) plants were grown for 90 days in soil contaminated with the five mentioned TEs at the limit levels of TEs in soils likely to receive sludge established by French legislation. Depending on the conditions, experimental set-ups were amended or not with 1% dry weight nanomagnetite (NPsMagn), citric acid-coated nanomagnetite (NPsMagn@CA) or micro-sized magnetite (µPs) in order to assess the behavior of nanomagnetites in a TEs-contaminated water-soil-plant system under repeated water-deficiency stress. The mixture of TEs did not induce phytotoxicity as estimated by plant growth, pigment content, maximum quantum yield of photosynthesis, oxidative impact and antioxidant response. Furthermore, both nanomagnetites treatments in a TEs-contaminated soil significantly increased biomass production by 64 % compared to control and antioxidant enzyme activities compared to control and TEs-treated plants. NPsMagn and NPsMagn@CA particularly enhance phytoextraction of Cd and Cu, increasing the amounts of TEs in aerial parts from 1.5 to 4.5 times compared to set-ups without nanomagnetites. Based on Cd, Cu, Pb and Zn contents in soil solutions, both nanomagnetites treatments improved TEs phytoextraction without increasing groundwater contamination. On the contrary, nanomagnetites significantly reduce arsenic uptake by plants and solubilization in dissolved phase. Our results show that modifying surface physicochemical properties of NPsMagn with citric acid coating does not improve their effects compared to bare NPsMagn. NPsMagn and NPsMagn@CA also appear to mitigate the effects of drought stress. This work highlights several positive environmental aspects related to the use of nanomagnetites in phytoremediation.

Effect of experimental dentin etchants on dentin bond strength, metalloproteinase inhibition, and antibiofilm activity.

OBJECTIVE: this study evaluated dentin microtensile bond strength (µTBS) and failure modes (at 24 h and one year), bonding interface regarding hybridization, surface morphology regarding demineralization, in situ metalloproteinase (MMP) activity, and antibacterial effect of three dentin etchants compared to 35% phosphoric acid (PA). MATERIALS AND METHODS: The Adper Single Bond 2 adhesive (3 M Oral Care) was applied on moist dentin etched with PA (control) or on air-dried dentin etched with 3% aluminum nitrate + 2% oxalic acid (AN), 6.8% ferric oxalate + 10% citric acid (FO), or 10% citric acid (CA). The µTBS test used 40 human teeth (n = 10). Failure modes and surface morphology were analyzed by scanning electron microscopy (n = 3), while bonding interface morphology and MMP activity were evaluated by laser scanning confocal microscopy (n = 3). Antibacterial activity was evaluated against S. Mutans biofilm by means of viable cells count (CFU/mL). RESULTS: PA presented the highest bond strengths regardless of aging time. PA, AN, and CA showed stable bond strengths after one year of storage. Adhesive and mixed failures were predominant in all groups. Thin hybrid layers with short resin tags were observed for the experimental etchants. The AN-based etchant was able to inhibit MMP activity. All tested etchants presented antibacterial activity against S. Mutans biofilm. SIGNIFICANCE: This study suggests different dentin etchants capable of inhibiting MMP activity while also acting as cavity disinfectants.

Citrate synthase lysine K215 hypoacetylation contributes to microglial citrate accumulation and pro-inflammatory functions after traumatic brain injury.

AIMS: This study aimed to investigate the relationship between microglial metabolism and neuroinflammation by examining the impact of citrate accumulation in microglia and its potential regulation through Cs K215 hypoacetylation. METHODS: Experimental approaches included assessing Cs enzyme activity through Cs K215Q mutation and investigating the inhibitory effects of hesperidin, a natural flavanone glycoside, on citrate synthase. Microglial phagocytosis and expression of pro-inflammatory cytokines were also examined in relation to Cs K215Q mutation and hesperidin treatment. RESULTS: Cs K215Q mutation and hesperidin exhibited significant inhibitory effects on Cs enzyme activity, microglial citrate accumulation, phagocytosis, and pro-inflammatory cytokine expression. Interestingly, Sirt3 knockdown aggravated microglial pro-inflammatory functions during neuroinflammation, despite its proven role in Cs deacetylation. CONCLUSION: Cs K215Q mutation and hesperidin effectively inhibited microglial pro-inflammatory functions without reversing the metabolic reprogramming. These findings suggest that targeting Cs K215 hypoacetylation and utilizing hesperidin may hold promise for modulating neuroinflammation in microglia.

Dissolution behavior of stone wool fibers in synthetic lung fluids: Impact of iron oxidation state changes induced by heat treatment for binder removal.

Stone wool fiber materials are commonly used for thermal and acoustic insulation, horticulture and filler purposes. Biosolubility of the stone wool fiber (SWF) materials accessed through acellular in vitro dissolution tests can potentially be used in future as an indicator of fiber biopersistence in vivo. To correlate acellular in vitro studies with in vivo and epidemiological investigations, not only a robust dissolution procedure is needed, but fundamental understanding of fiber behavior during sample preparation and dissolution is required. We investigated the influence of heat treatment procedure for binder removal on the SWF iron oxidation state as well as on the SWF dissolution behavior in simulant lung fluids (with and without complexing agents). We used heat treatments at 450 °C for 5 min and 590 °C for 1 h. Both procedures resulted in complete binder removal from the SWF. Changes of iron oxidation state were moderate if binder was removed at 450 °C for 5 min, and there were no substantial changes of SWF's dissolution behavior in all investigated fluids after this heat treatment. In contrast, if binder was removed at 590 °C for 1 h, complete Fe(II) oxidation to Fe(III) was observed and significant increase of dissolution was shown in fluids without complexing agent (citrate). PHREEQC solution speciation modeling showed that in this case, released Fe(III) may form ferrihydrite precipitate in the solution. Precipitation of ferrihydrite solid phase leads to removal of iron cations from the solution, thus shifting reaction towards the dissolution products and increasing total mass loss of fiber samples. This effect is not observed for heat treated fibers if citrate is present in the fluid, because Fe(III) binds with citrate and remains mobile in the solution. Therefore, for developing the most accurate SWF in vitro acellular biosolubility test, SWF heat treatment for binder removal is not recommended in combination with dissolution testing in fluids without citrate as a complexing agent.

Boron deficiency decreased the root activity of Ga-exposed rice seedlings by reducing iron accumulation and increasing Ga in iron plaque.

Gallium (Ga) is an emerging chemical pollutant chiefly associated with high-tech industries. Boron (B) alleviates the negative effects of toxic elements on plant growth. Thereby, the effects of B fertilization on Ga toxicity in rice seedlings was studied to clarify the role of iron plaque in the distribution of Ga, Fe, and B in Ga-treated rice seedlings in the presence or absence of B. Gallium exposure significantly reduced the biomass of rice seedlings. Boron deficiency induced a significant change in the distribution of B in Ga-treated rice seedlings compared with "Ga+B" treatments. Accumulation of Ga in roots, dithionite-citrate-bicarbonate (DCB) extracts, and shoots showed a dose-dependent manner from both +B and -B rice seedlings. Boron nutrition levels affect the distribution of Fe in roots, DCB extracts, and shoots, in which DCB-extractable Fe was significantly decreased from "Ga-B" treatments compared with "Ga+B" treatments. Root activity was significantly decreased in both Ga-exposed rice seedlings; however, B-deficient seedlings showed a severe reduction than +B rice seedlings. These results reveal that Fe plaque might be a temporary sink for B accumulation when plants are grown with proper B, wherein the re-utilization of DCB-extractable B stored in Fe plaque is mandatory for plant growth under B deficiency. Correlation analysis revealed that B deficiency decreased the root activity of Ga-exposed rice seedlings by reducing DCB-extractable Fe and increasing DCB-extractable Ga in Fe plaque. This study enhances our understanding of how B nutritional levels affect Ga toxicity in rice plants.

Can humans smell tastants?

Although studies have shown that olfaction may contribute to the perception of tastant, literature is scarce or circumstantial, especially in humans. This study aims to (i) explore whether humans can perceive solutions of basic prototypical tastants through orthonasal and retronasal olfaction and (ii) to examine what volatile odor compounds (VOCs) underlie this ability. Solutions of 5 basic tastants (sucrose, sodium chloride, citric acid, monosodium glutamate [MSG], quinine) dissolved in water, and 2 fatty acids (oleic and linoleic acid) dissolved in mineral oil were prepared. Triangle discrimination tests were performed (n = 41 in duplicate) to assess whether the tastant solutions can be distinguished from blanks (solvents) through ortho- and retronasal olfaction. Participants were able to distinguish all tastant solutions from blank through orthonasal olfaction. Only sucrose, sodium chloride, oleic acid, and linoleic acid were distinguished from blank by retronasal olfaction. Ethyl dichloroacetate, methylene chloride, and/or acetone were identified in the headspace of sucrose, MSG, and quinine solutions but not in the headspace of water, sodium chloride, and citric acid solutions. Fat oxidation compounds such as alcohols and aldehydes were detected in the headspace of the oleic and linoleic acid solutions but not the mineral oil. We conclude that prototypical tastant solutions can be discriminated from water and fatty acid solutions from mineral oil through orthonasal olfaction. Differences in the volatile headspace composition between blanks and tastant solutions may have facilitated the olfactory discrimination. These findings can have methodological implications for future studies assessing gustatory perception using these prototypical taste compounds.

Citric Acid Promotes Immune Function by Modulating the Intestinal Barrier.

Amidst increasing concern about antibiotic resistance resulting from the overuse of antibiotics, there is a growing interest in exploring alternative agents. One such agent is citric acid, an organic compound commonly used for various applications. Our research findings indicate that the inclusion of citric acid can have several beneficial effects on the tight junctions found in the mouse intestine. Firstly, the study suggests that citric acid may contribute to weight gain by stimulating the growth of intestinal epithelial cells (IE-6). Citric acid enhances the small intestinal villus-crypt ratio in mice, thereby promoting intestinal structural morphology. Additionally, citric acid has been found to increase the population of beneficial intestinal microorganisms, including Bifidobacterium and Lactobacillus. It also promotes the expression of important protein genes such as occludin, ZO-1, and claudin-1, which play crucial roles in maintaining the integrity of the tight junction barrier in the intestines. Furthermore, in infected IEC-6 cells with H9N2 avian influenza virus, citric acid augmented the expression of genes closely associated with the influenza virus infection. Moreover, it reduces the inflammatory response caused by the viral infection and thwarted influenza virus replication. These findings suggest that citric acid fortifies the intestinal tight junction barrier, inhibits the replication of influenza viruses targeting the intestinal tract, and boosts intestinal immune function.

Citric Acid Conditioning as an Alternative to EDTA for Growth Factors Release and Stem Cell Response in Regenerative Endodontics: A Systematic Review of In Vitro Studies.

INTRODUCTION: Citric acid (CA) conditioning may be a promising alternative to ethylenediaminetetraacetic acid (EDTA) in regenerative endodontic procedures, as reported to improve growth factors' release from dentin. This review systematically investigated the effect of CA conditioning on the growth factors release from dentin and cell behavior compared to EDTA conditioning. METHODS: Searches were conducted (PubMed/MEDLINE, Scopus, Web of Science, Embase, SciELO, Cochrane Library, and grey literature) until May-2023. Only in vitro studies that evaluated the effects of CA on growth factors' release from dentin and cell behavior outcomes compared to EDTA were included. The studies were critically appraised using a modified Joanna Briggs Institute's checklist. Meta-analysis was unfeasible. RESULTS: Out of the 335 articles screened, nine were included. Among these, three studies used dentin discs/roots from permanent human teeth; the rest combined them with stem cells. 10% CA for 5 or 10 minute was the most used protocol. Meanwhile, EDTA concentrations ranged from 10% to 17%. In eight studies examining the release of growth factors, five reported a significant release of transforming growth factor-ß after dentin conditioning with 10% CA compared to 17% EDTA. Regarding cell behavior (6 studies), three studies assessed cell viability. The findings revealed that 10% CA conditioning showed cell viability similar to those of 17% EDTA. Additionally, in two out of three studies, it was observed that 10% CA conditioning did not affect cell morphology. The studies had a low risk of bias. CONCLUSIONS: The use of 10% CA to condition dentin for 5-10 minutes resulted in a notable transforming growth factor -ß1 release, but its cell responses were similar to those of EDTA.

Citrate-coated silver nanoparticles loaded with agomelatine provide neuronal therapy in acute cerebral ischemia/reperfusion of rats by inhibiting the oxidative stress, endoplasmic reticulum stress, and P2X7 receptor-mediated inflammasome.

Cerebral ischemia and reperfusion are related to various situations like injuries after various traumas, oxidative stress, increased calcium ion, capillary hypoperfusion, microvascular hyperpermeability, leukocyte infiltration, and blood-brain barrier disruption. An antidepressant Agomelatine which is a melatonin receptor (MT1/MT2) agonist and serotonin receptor (5-HT2C) antagonist has been reported by studies to have antioxidant and anti-inflammatory effects. In our study, we aimed to detect the effects of citrate-coated silver nanoparticle-loaded agomelatine application on neurodegeneration, endoplasmic reticulum stress, autophagic and apoptotic cell death, inflammation, and P2X7R expression in the cerebral ischemia-reperfusion model to facilitate the passage of blood-brain barrier. Forty two Sprague-Dawley rats in total were divided into six equal groups (n:7) and applications were performed. Acute cerebral injury in the ischemia-reperfusion model was created 2 h after internal carotid artery ligation in rats and then at the 2nd hour of reperfusion citrate-coated silver nanoparticles loaded with Agomelatine were applied. Twenty four hours later, neurologic analysis on animals in experimental groups was performed, animals were decapitated and GSH, GPx, SOD, CAT, MDA, IL-1ß, and TNF-α parameters were examined after taking blood and the cerebral tissue samples. As a result, it was determined that ischemia-reperfusion caused endoplasmic reticulum stress in the cerebral tissues and thus caused cellular injury.

Plant growth promoting bacteria and citric acid promote growth and cadmium phytoremediation in ryegrass.

Based on the growth-promoting effect of plant growth promoting bacteria on plants and the mobilization of Cd by citric acid, an experiment was designed in which the combined treatment of Bacillus megaterium and citric acid promoted ryegrass to repair Cd-contaminated soil. This study aimed to evaluate the effects of different treatments on the antioxidant enzyme activity, photosynthesis intensity, Cd accumulation, and rhizosphere cadmium migration under cadmium contamination conditions. And the soil morphology and structure changes were studied by infrared spectroscopy FourierTransformInfrared(FT-IR) and scanning electron microscope Energy Dispersive Spectrometer(SEM-EDS) before and after different treatments. The results show that the combined treatment of Bacillus megaterium and citric acid significantly improved the oxidative stress defense and plant photosynthesis and increased of rye biomass. rye biomass 1.28 times higher than CK treatment. Joint treatment significantly increased the amount of shoot accumulation of Cd, 2.31 times higher than CK treatment, increased the migration and accumulation of cadmium. FTIR and SEM-EDS also showed that the organic constituents such as O-H, C-O and C-N in soils as a major mechanism for mobilization of the heavy metal Cd. Thus, the combined treatment of Bacillus megaterium and citric acid can promote plant growth, improve the damage to ryegrass caused by single organic acid addition, and improve the plant extraction efficiency, which is a feasible way to repair Cd-contaminated soil through activated extraction system.

The novelty of this study is the combined application of bacteria and chelating agents to ryegrass to improve phytoremediation efficiency. Bacillus giganosus has a good role in promoting the growth of ryegrass. As citrate, a small molecule chelate, can activate heavy metal cadmium and detoxify heavy metals, so it was selected. This study revealed in detail the response of ryegrass to the heavy metal Cd after exogenous addition of Bacillus gigansus and citrate, which is important for the application of cadmium removal by phytoremediation.

Mercury-induced excitotoxicity in presynaptic brain nerve terminals: modulatory effects of carbonaceous airborne particulate simulants.

Multipollutant approach is a breakthrough in up-to-date environmental quality and health risk estimation. Both mercury and carbonaceous air particulate are hazardous neurotoxicants. Here, the ability of carbonaceous air particulate simulants, i.e. carbon dots obtained by heating of organics, and nanodiamonds, to influence Hg2+-induced neurotoxicity was monitored using biological system, i.e. presynaptic rat cortex nerve terminals. Using HgCl2 and classical reducing/chelating agents, an adequate synaptic parameter, i.e. the extracellular level of key excitatory neurotransmitter L-[14C]glutamate, was selected for further analysis. HgCl2 starting from 5 µM caused an acute and concentration-dependent increase in the extracellular L-[14C]glutamate level in nerve terminals. Combined application of Hg2+ and carbon dots from heating of citric acid/urea showed that this simulant was able to mitigate in an acute manner excitotoxic Hg2+-induced increase in the extracellular L-[14C]glutamate level in nerve terminals by 37%. These carbon dots and Hg2+ acted as a complex in nerve terminals that was confirmed with fluorimetric data on Hg2+-induced changes in their spectroscopic features. Nanodiamonds and carbon dots from ß-alanine were not able to mitigate a Hg2+-induced increase in the extracellular L-[14C]glutamate level in nerve terminals. Developed approach can be applicable for monitoring capability of different particles/compounds to have Hg2+-chelating signs in the biological systems. Therefore, among testing simulants, the only carbon dots from citric acid/urea were able to mitigate acute Hg2+-induced neurotoxicity in nerve terminals, thereby showing a variety of effects of carbonaceous airborne particulate in situ and its potential to interfere and modulate Hg2+-associated health hazard.

Sucrose, NaCl, and citric acid suppress the metallic sensation of FeSO4.

Metallic sensation is often described as unpleasant and can reduce acceptance of foods and beverages and compliance with medication. Masking and suppressing aversive sensations can help to improve acceptance of these products, with many successful strategies identified for bitterness. However, there are few studies investigating effective strategies for suppressing metallic sensation. This study aims to assess the effectiveness of mixture suppression to reduce the metallic sensation elicited from ferrous sulfate and examine whether individual differences in metallic sensation are associated with the effectiveness of suppression strategies. To achieve this, participants (n = 121) reported the intensity of suprathreshold concentrations of ferrous sulfate alone and in binary mixtures with three tastants, specifically, sucrose, citric acid, and sodium chloride. The results revealed that metallic sensation ratings were significantly lower for every binary mixture tested compared to ferrous sulfate presented in isolation. For 0.3 mM ferrous sulfate, sucrose was identified to be the most effective compound in suppressing metallic sensation, followed by citric acid and sodium chloride. For the 1.0 mM ferrous sulfate solutions, all tastants were equally effective at suppressing metallic sensation. In addition, there is a significant interaction between the perceived metallic intensity and the effectiveness of each strategy. These findings suggest that sucrose, citric acid, and sodium chloride have the potential to be effective in suppressing metallic sensation.

[Remediation of Soil Cadmium Contamination by Solanum nigrum L. Enhanced by the Combination of Exogenous Bacteria and Citric Acid].

To determine how to strengthen the Cd-enriched plant Solanum nigrum L. to remediate cadmium(Cd)-contaminated soil, a pot experiment was conducted with five treatments:control treatment(CK), Glomus mosseae(GM), G. mosseae+citric acid(GM+CA), G. mosseae+Bacillus megaterium(GM+BM), and G. mosseae+B. megaterium+citric acid(GM+BM+CA). We measured soil total Cd, available Cd, plant Cd uptake, and microbial community changes and analyzed the effects of exogenous microbial agents and citric acid addition on the remediation effect of Cd contamination by S. nigrum L. The results showed that relative to that of the CK treatment, the root, stem, and leaf biomass of the GM treatment significantly increased by 35.67%, 41.35%, and 65.38%, and the root and stem biomass of the GM+BM+CA treatment significantly increased by 73.38% and 75.38%. The GM+BM+CA treatment significantly increased Cd accumulation in leaves by 226.84%. The GM+BM+CA treatment significantly increased the Cd transport factor from stem to leaves by 52.47%. The GM+BM+CA treatment significantly increased the leaf bioconcentration factor by 120.53%. In addition, the combined restoration also had an impact on the rhizosphere microbial community structure, especially in inducing the relative abundance of some key microbial groups such as Proteobacteria, Actinobacteria, Glomeromycota, and Olpidiomycota to increase by 2.00%-5.77%, 0.76%-9.96%, 2.11%-3.63%, and 0.54%-2.98%, respectively. According to the RDA analysis, Proteobacteria and Actinobacteria were negatively correlated with soil total Cd, whereas Glomeromycota and Olpidiomycota were negatively correlated with soil total Cd. The changes in key microorganisms enhanced the ability of S. nigrum L. to absorb rhizosphere nutrients and resist Cd stress, increased the Cd accumulation ability of S. nigrum L., and effectively reduced the total Cd content in soil. In conclusion, G. mosseae, citric acid, and B. megaterium activated insoluble Cd in the soil by co-inoculation, which contributed to more Cd accumulation by S. nigrum L. and also produced co-remediation with G. mosseae. The enrichment plant-microorganism combined remediation Cd-contaminated soil has good application potential.

Human Pancreatic Islets React to Glucolipotoxicity by Secreting Pyruvate and Citrate.

Progressive decline in pancreatic beta-cell function is central to the pathogenesis of type 2 diabetes (T2D). Here, we explore the relationship between the beta cell and its nutritional environment, asking how an excess of energy substrate leads to altered energy production and subsequent insulin secretion. Alterations in intracellular metabolic homeostasis are key markers of islets with T2D, but changes in cellular metabolite exchanges with their environment remain unknown. We answered this question using nuclear magnetic resonance-based quantitative metabolomics and evaluated the consumption or secretion of 31 extracellular metabolites from healthy and T2D human islets. Islets were also cultured under high levels of glucose and/or palmitate to induce gluco-, lipo-, and glucolipotoxicity. Biochemical analyses revealed drastic alterations in the pyruvate and citrate pathways, which appear to be associated with mitochondrial oxoglutarate dehydrogenase (OGDH) downregulation. We repeated these manipulations on the rat insulinoma-derived beta-pancreatic cell line (INS-1E). Our results highlight an OGDH downregulation with a clear effect on the pyruvate and citrate pathways. However, citrate is directed to lipogenesis in the INS-1E cells instead of being secreted as in human islets. Our results demonstrate the ability of metabolomic approaches performed on culture media to easily discriminate T2D from healthy and functional islets.

Antihypertensive and Vasorelaxant Effects of Citric Acid and Lemon Juice in Spontaneously Hypertensive Rats: In Vivo and Ex Vivo Studies.

Hypertension is a key risk factor for heart, brain, and kidney disease development. Fruit consumption has been associated with a decrease in blood pressure. Lemon juice, which contains antihypertensive compounds, may exert antihypertensive effects. However, no research has verified the antihypertensive effects of citric acid, the most abundant ingredient in lemon juice. In the present study, we demonstrated the antihypertensive effects of citric acid and lemon juice by performing single oral administration tests and the aortic ring assay using spontaneously hypertensive rats (SHRs). Single oral doses of both agents markedly reduced the systolic and diastolic blood pressures in the SHRs. In addition, both these agents relaxed the thoracic aorta from the SHRs; however, these effects were notably attenuated by the removal of the aortic endothelium. Orally administered citric acid was rapidly absorbed and metabolized in vivo. Among the functional compounds in lemon juice, citric acid was identified as the primary antihypertensive component. Although more detailed studies are required to validate our findings, the novel functional attributes of citric acid can achieve the normalization of blood pressure when it is consumed via diet.

Suppression of sweetness: evidence for central mechanism for suppression of sweetness from sucrose by citric acid.

The underlying mechanisms of taste interactions in humans are not well understood, and three mechanisms have been proposed, namely a chemical interaction, a peripheral physiological, and a central mechanism. In the present study, it was investigated which of these mechanisms causes the suppression of sweetness by citric acid. This was investigated using a split-tongue gustometer that can stimulate the two sides of the tongue with different stimuli simultaneously, enabling a comparison of sucrose and citric acid presented either separately on each side of the tongue simultaneously or in a mixture on one side. Two studies were conducted using low (Study 1; n = 50) and high (Study 2: n = 59) concentrations of sucrose (2.5% (w/w) and 10% (w/w), respectively), and citric acid (0.14% (w/w) and 0.18% (w/w), respectively). In neither of the studies was there a significant difference in sweetness intensity ratings between the two conditions where sucrose and citric acid were presented either separately or in a mixture form. However, both showed significantly lower sweetness ratings than without citric acid indicating suppression of the sweetness of sucrose from citric acid. This provides strong evidence for a central mechanism for the suppression of the sweetness of sucrose by citric acid. This mechanism seems to be equal in high and low concentrations of both sucrose and citric acid.