Acid End Products Research Articles

A Modular Synthetic Approach to Isosteric Sulfonic Acid Analogues of the Anticoagulant Pentasaccharide Idraparinux.

Heparin-based anticoagulants are drugs of choice in the therapy and prophylaxis of thromboembolic diseases. Idraparinux is a synthetic anticoagulant pentasaccharide based on the heparin antithrombin-binding domain. In the frame of our ongoing research aimed at the synthesis of sulfonic acid-containing heparinoid anticoagulants, we elaborated a modular pathway to obtain a series of idraparinux-analogue pentasaccharides bearing one or two primary sulfonic acid moieties. Five protected pentasaccharides with different C-sulfonation patterns were prepared by two subsequent glycosylation reactions, respectively, using two monosaccharide and four disaccharide building blocks. Transformation of the protected derivatives into the fully O-sulfated, O-methylated sulfonic acid end-products was also studied.

Abstract B41: Post-transcriptional regulation of IDH1 by the RNA-binding protein HuR is important for pancreatic cancer cell survival under nutrient deprivation

Abstract Introduction: Isocitrate dehydrogenase 1(IDH1) has been prioritized in the recent cancer biology literature because of mutations occurring in some tumor types. Additionally the wild type isoenzyme is important for metabolic reprogramming under hypoxic stress. Importantly, the role of IDH1 under other forms of metabolic stress, such as nutrient deprivation (hallmark of the PDA microenvironment) has not been explored, and the regulatory mechanism of IDH1 expression remains unknown. We recently showed that the regulatory RNA binding protein, HuR, binds and directly regulates IDH1 expression in multiple PDA cell lines. The regulatory protein becomes biologically engaged under nutrient deprivation by translocating with the IDH1 transcript form the nucleus to the cytoplasm under glucose deprivation, and HuR silencing sensitized cells under these conditions. Here, we hone in on the regulatory HuR binding site to the IDH1 transcript, explore the importance of HuR in the context of additional metabolic stressors and utilize stable isotope metabolomic profiling to gain mechanistic insight into how HuR is protective under nutrient deprivation. Methods: IDH1 and HuR expression were knocked down by siRNA, and cell viability was determined by PicoGreen and Trypan blue exclusion assays. Immunofluorescence was used to image HuR subcellular localization under glutamine deprivation. Based on computational predictions of 5 HuR binding sites in the IDH1 mRNA 3'UTR, we subcloned this entire region into a luciferase reporter construct to further study this regulatory interaction. In order to determine the impact of HuR expression in cellular metabolism targeted tracer fate association studies were performed using GC-MS of pellets from cells cultured with 13C-labeled glucose and glutamine in BxPC3 pancreatic cancer cells that differed only in HuR expression. We calculated Pearson correlations of measured metabolites after HuR silencing. Results: Cell viability was impaired by depletion of both IDH1 and HuR (vs. controls) upon glutamine and glucose withdrawal. Moreover, HuR silencing resulted in potent suppression of IDH1 at the mRNA and protein levels. HuR silencing substantially decremented luciferase activity in the IDH1 3'UTR construct compared to the control (> 2-fold decrease). HuR translocated to the cytoplasm under glutamine deprivation, as previously published observed with glucose deprivation by our group. Metabolic tracer fate association studies revealed that HuR silencing impaired carbon flux from glutamine into fatty acid end products (myristate and palmitate, > 0.9-Pearson's Correlation) under low glucose conditions, implicating HuR's regulatory role in the IDH1-mediated reductive carboxylation step of this metabolic pathway. Additionally, HuR silencing impaired ribose and glycogen synthesis from glucose, and futile carbon exchange fluxes were prevalent. Conclusions: HuR is important for pancreatic cancer cell survival under glutamine deprivation, as previously observed for glucose deprivation. Carbon flux from glutamine to fatty acid end products suggests a role for HuR in reductive carboxylation of glutamine-derived α-ketoglutarate by IDH1, as a way to maintain adequate lipid synthesis under glucose deprivation. Our Studies provide a rationale to pursue pharmacologic strategies that target HuR or its regulation of IDH1 as a novel treatment of PDA. Citation Format: Mahsa Zarei, Fernando F. Blanco, Laszlo G. Boros, Charles J. Yeo, Jonathan R. Brody, Jordan M. Winter. Post-transcriptional regulation of IDH1 by the RNA-binding protein HuR is important for pancreatic cancer cell survival under nutrient deprivation. [abstract]. In: Proceedings of the AACR Special Conference: Metabolism and Cancer; Jun 7-10, 2015; Bellevue, WA. Philadelphia (PA): AACR; Mol Cancer Res 2016;14(1_Suppl):Abstract nr B41.

Important physiological features of the lactic acid bacterium employed in lactic acid production

One of the key characteristics of industrial bioprocesses is near maximum specific product formation rate and it can be attained as result of focused metabolic activity of employed microorganism under operational conditions. Most of the current knowledge about the metabolic activity of traditional industrial microorganisms - lactic acid bacteria includes relatively simple metabolic network based on carbohydrate catabolism and lactate production. However, recent investigations of metabolic flexibility of the lactic acid bacteria showed need for further investigation of their metabolic potential which can significantly improve efficiency of the industrial bioprocesses. Physiology of the lactic acid bacterium Lactobacillus coryniformis was investigated in a chemically defined medium containing glucose as main carbon and energy source. Batch cultivations were carried out at relatively low temperature and effect of dissolved oxygen and carbon dioxide concentration on bacterial growth was investigated. Limitation with carbon and energy source and accumulation of biomass was connected with D-lactic acid and other end-products formation.

Calcium and fat balance and gastrointestinal tolerance in normal term infants fed infant formulas containing a monoglyceride‐based vs triglyceride‐based fat‐blend (LB403)

Objectives: We investigated effects of monoacylglyceride (MG) and free fatty acids (end products of fat hydrolysis in the gut) inclusion in infant formula’s fat‐blend on calcium and fat absorption.Methods: A randomized, blinded, 4 wk crossover study evaluated calcium and fat absorption and gastrointestinal tolerance in 2‐4 mo old healthy term infants fed an experimental milk‐based powdered formula containing MG palmitate and soy calcium fatty acids (EF) vs a similar commercial control formula containing triacylglyceride‐based fat‐blend (CF). Balance and tolerance data was based on 12 and 13 evaluable subjects, respectively.Results: Balance data indicated that percent (%) calcium absorption (primary study variable) was not different (p=0.85) between EF (38+5; mean±SEM) and CF (37+6). Absorbed calcium (mg/kg/day) was numerically higher (16%) with EF, but not statistically different. Percent fat absorption was 5.2% lower (p=0.01) with EF vs CF, but absorbed fat (g/kg/day) was numerically greater (9.4%) with EF. Tolerance data indicated that mean rank stool consistency was firmer (p=0.02) and stool frequency was higher (p=0.01) with EF vs CF. Percentage of yellow stools was higher (p=0.03) and percentage of green stools (p=0.03) was lower with EF vs CF. Mean rank fussiness was lower (p= 0.01) with EF vs CF.Conclusion: The EF demonstrated similar calcium absorption and good GI tolerance vs the CF, which was a standard formula containing a fat blend with proven efficacy and safe use in normal infants.Grant Funding Source: Supported by Abbott Nutrition

Degradation of high loads of crystalline cellulose and of unpretreated plant biomass by the thermophilic bacterium Caldicellulosiruptor bescii

The thermophilic bacterium Caldicellulosiruptor bescii grows at 78 °C on high concentrations (200 g L(-1)) of both crystalline cellulose and unpretreated switchgrass, while low concentrations (<20 g L(-1)) of acid-pretreated switchgrass inhibit growth. Degradation of crystalline cellulose, but not that of unpretreated switchgrass, was limited by nitrogen and vitamin (folate) availability. Under optimal conditions, C. bescii solubilized approximately 60% of the crystalline cellulose and 30% of the unpretreated switchgrass using initial substrate concentrations of 50 g L(-1). Further fermentation of crystalline cellulose and of switchgrass was inhibited by organic acid end-products and by a specific inhibitor of C. bescii growth that did not affect other thermophilic bacteria, respectively. Soluble mono- and oligosaccharides, organic acids, carbon dioxide, and microbial biomass, quantitatively accounted for the crystalline cellulose and plant biomass carbon utilized. C. bescii therefore degrades industrially-relevant concentrations of lignocellulosic biomass that have not undergone pretreatment thereby demonstrating its potential utility in biomass conversion.

PP213-MON AN APPROPRIATE METHOD TO MEASURE FRUCTAN LEVELS IN ENTERAL NUTRITION

Conclusion: Asidophilus ForteTM with prebiotics restricted facultatives in the PMEU. Neither probiotics nor prebiotics alone had this effect. The effect remained during different growth phases. Further studies are warranted for evaluating the impacts of various components of the prebiotic mixture. The supplementations could in vivo prevent bacterial overgrowth and balance the numbers of acid and neutral end-products producing facultatives, which could support food uptake.

PP214-MON 1–2,(30) FORMULA FOR SODIUM, POTASSIUM AND WATER NEEDS CALCULATION

Conclusion: Asidophilus ForteTM with prebiotics restricted facultatives in the PMEU. Neither probiotics nor prebiotics alone had this effect. The effect remained during different growth phases. Further studies are warranted for evaluating the impacts of various components of the prebiotic mixture. The supplementations could in vivo prevent bacterial overgrowth and balance the numbers of acid and neutral end-products producing facultatives, which could support food uptake.

Platelet-type 12-lipoxygenase induces MMP9 expression and cellular invasionviaactivation of PI3K/Akt/NF-κB

Prostate cancer is the most frequently diagnosed cancer and the second leading cause of death in males in the United States. Using human prostate cancer specimens, the authors have previously shown that elevated expression levels of 12-lipoxygenase (12-LOX) occurred more frequently in advanced stage, high-grade prostate cancer, suggesting that 12-LOX expression is associated with carcinoma progression and invasion. Previous reports from their group and others have shown that 12-LOX is a positive modulator of invasion and metastasis; however, the mechanism remains unclear. In this work, a new link between 12-LOX and the matrix metalloproteinase 9 (MMP9) in prostate cancer angiogenesis is reported. This study demonstrated that overexpression of 12-LOX in prostate cancer PC-3 cells resulted in elevated expression of MMP9 mRNA, protein and secretion. Exogenous addition of 12(S)-hydroxy eicosatetraenoic acid, the sole and stable end product of arachidonic acid metabolism by 12-LOX, is able to increase MMP9 expression in wild-type PC-3 cells. Furthermore, using pharmacological and genetic inhibition approaches, it was found that 12-LOX activates phosphoinositol 3 kinase (PI3K)/Akt, which results in nuclear factor-kappa B (NF-κB)-driven MMP9 expression, ensuing in enhanced chemoattraction of endothelial cells. Specific inhibitors of 12-LOX, PI3K or NF-κB inhibited MMP9 expression in 12-LOX-expressing PC-3 cells and resulted in the blockade of the migratory ability of endothelial cells. In summary, the authors have identified a new pathway by which overexpression of 12-LOX in prostate cancer cells leads to augmented production of MMP9 via activation of PI3K/Akt/NF-κB signaling. The role of 12-LOX-mediated MMP9 secretion in endothelial cell migration may account for the proangiogenic function of 12-LOX in prostate cancer.

Interconversion of Lactose to Lactulose in Alkaline Environment: Comparison of Different Catalysis Concepts

Interconversion of lactulose to lactulose with the aim to determine and optimize the yield of ketose was carried out. Various homogenous and heterogeneous alkaline catalysts were applied (NaOH, MgO, hydrotalcite etc.). The selectivity and activity of the catalysts were compared. The results gave insight to the performance differences among the screened catalysts under the various reaction conditions. From the activity performance point of view, the conversion was limited by the formation of acidic end-products. In general, the selectivity decreased with conversion and the conversion-selectivity pattern was independent of the catalyst.

Anaerobic Respiration Using a Complete Oxidative TCA Cycle Drives Multicellular Swarming in Proteus mirabilis

ABSTRACTProteus mirabilis rapidly migrates across surfaces using a periodic developmental process of differentiation alternating between short swimmer cells and elongated hyperflagellated swarmer cells. To undergo this vigorous flagellum-mediated motility, bacteria must generate a substantial proton gradient across their cytoplasmic membranes by using available energy pathways. We sought to identify the link between energy pathways and swarming differentiation by examining the behavior of defined central metabolism mutants. Mutations in the tricarboxylic acid (TCA) cycle (fumC and sdhB mutants) caused altered patterns of swarming periodicity, suggesting an aerobic pathway. Surprisingly, the wild-type strain swarmed on agar containing sodium azide, which poisons aerobic respiration; the fumC TCA cycle mutant, however, was unable to swarm on azide. To identify other contributing energy pathways, we screened transposon mutants for loss of swarming on sodium azide and found insertions in the following genes that involved fumarate metabolism or respiration: hybB, encoding hydrogenase; fumC, encoding fumarase; argH, encoding argininosuccinate lyase (generates fumarate); and a quinone hydroxylase gene. These findings validated the screen and suggested involvement of anaerobic electron transport chain components. Abnormal swarming periodicity of fumC and sdhB mutants was associated with the excretion of reduced acidic fermentation end products. Bacteria lacking SdhB were rescued to wild-type pH and periodicity by providing fumarate, independent of carbon source but dependent on oxygen, while fumC mutants were rescued by glycerol, independent of fumarate only under anaerobic conditions. These findings link multicellular swarming patterns with fumarate metabolism and membrane electron transport using a previously unappreciated configuration of both aerobic and anaerobic respiratory chain components.

Functional amyloid formation by Streptococcus mutans

Dental caries is a common infectious disease associated with acidogenic and aciduric bacteria, including Streptococcus mutans. Organisms that cause cavities form recalcitrant biofilms, generate acids from dietary sugars and tolerate acid end products. It has recently been recognized that micro-organisms can produce functional amyloids that are integral to biofilm development. We now show that the S. mutans cell-surface-localized adhesin P1 (antigen I/II, PAc) is an amyloid-forming protein. This conclusion is based on the defining properties of amyloids, including binding by the amyloidophilic dyes Congo red (CR) and Thioflavin T (ThT), visualization of amyloid fibres by transmission electron microscopy and the green birefringent properties of CR-stained protein aggregates when viewed under cross-polarized light. We provide evidence that amyloid is present in human dental plaque and is produced by both laboratory strains and clinical isolates of S. mutans. We provide further evidence that amyloid formation is not limited to P1, since bacterial colonies without this adhesin demonstrate residual green birefringence. However, S. mutans lacking sortase, the transpeptidase enzyme that mediates the covalent linkage of its substrates to the cell-wall peptidoglycan, including P1 and five other proteins, is not birefringent when stained with CR and does not form biofilms. Biofilm formation is inhibited when S. mutans is cultured in the presence of known inhibitors of amyloid fibrillization, including CR, Thioflavin S and epigallocatechin-3-gallate, which also inhibited ThT uptake by S. mutans extracellular proteins. Taken together, these results indicate that S. mutans is an amyloid-forming organism and suggest that amyloidogenesis contributes to biofilm formation by this oral microbe.

Synthesis of 2-Hydroxyl-3-Sulfonic Acid Sodium Salt-Propyl Lacrylate

2-hydroxyl-3-sulfonic acid sodium salt-propyl lacrylate was synthesized through the three-step process (sulfonation, ring-closing reaction, and esterification) by using epichlorohydrin as the starting material. The structure of oxiranemethane sulfonic acid sodium salt and end product 2-hydroxyl-3-sulfonic acid sodium salt-propyl lacrylate was identified by FTIR and Melting point. The influence factors of the synthesis process were studied. The optimal condition of the synthesis of ring-closing reaction and esterification was gained. Through the synthesis method, a corresponding synthesis of lauric acid, 14 acid, palmitic acid, 18 acid were gained. Then they were on the surface tension tests to determine the critical micelle concentration.

The Branched-Chain Amino Acid Aminotransferase Encoded by ilvE Is Involved in Acid Tolerance in Streptococcus mutans

The ability of Streptococcus mutans to produce and tolerate organic acids from carbohydrate metabolism represents a major virulence factor responsible for the formation of carious lesions. Pyruvate is a key metabolic intermediate that, when rerouted to other metabolic pathways such as amino acid biosynthesis, results in the alleviation of acid stress by reducing acid end products and aiding in maintenance of intracellular pH. Amino acid biosynthetic genes such as ilvC and ilvE were identified as being upregulated in a proteome analysis of Streptococcus mutans under acid stress conditions (A. C. Len, D. W. Harty, and N. A. Jacques, Microbiology 150:1353-1366, 2004). In Lactococcus lactis and Staphylococcus carnosus, the ilvE gene product is involved with biosynthesis and degradation of branched-chain amino acids, as well as in the production of branched-chain fatty acids (B. Ganesan and B. C. Weimer, Appl. Environ. Microbiol. 70:638-641, 2004; S. M. Madsen et al., Appl. Environ. Microbiol. 68:4007-4014, 2002; and M. Yvon, S. Thirouin, L. Rijnen, D. Fromentier, and J. C. Gripon, Appl. Environ. Microbiol. 63:414-419, 1997). Here we constructed and characterized an ilvE deletion mutant of S. mutans UA159. Growth experiments revealed that the ilvE mutant strain has a lag in growth when nutritionally limited for branched-chain amino acids. We further demonstrated that the loss of ilvE causes a decrease in acid tolerance. The ilvE strain exhibits a defect in F(1)-F(o) ATPase activity and has reduced catabolic activity for isoleucine and valine. Results from transcriptional studies showed that the ilvE promoter is upregulated during growth at low pH. Collectively, the results of this investigation show that amino acid metabolism is a component of the acid-adaptive repertoire of S. mutans.

Analysis of Acidic End Products and Molecular Characterization of Biohydrogenbacterium R3 sp.nov

Biohydrogenbacterium R3 sp.nov, as a typical strains of hydrogen production bacteria, was isolated from the activated sludge in the biohydrogen production reaction by using culture media of HPB-LR which was designed particularly for isolating anaerobic fermentation bacteria and an improved Hungate rolling tubes technique and a plate method of culture bottle (PMCB) which were used for counting and isolating the anaerobes by our lab. Two representative strains of hydrogen production bacteria, namely RL20, RL37, and a strain of no hydrogen production bacterium, namely RL16 were used as contrast analysis. Experiment results indicated that the distributed proportion of ethanol and acetic acid was 95%-99% in the total amount of VAFs (Volatile Fatty Acid) of R3 which were typical ethanol-type fermentation, and the total amount of ethanol and acetic acid was commensurate with that of propionic acid.

Characterization of a glutamate transporter operon, glnQHMP, in Streptococcus mutans and its role in acid tolerance.

Glutamate contributes to the acid tolerance response (ATR) of many Gram-negative and Gram-positive bacteria, but its role in the ATR of the oral bacterium Streptococcus mutans is unknown. This study describes the discovery and characterization of a glutamate transporter operon designated glnQHMP (Smu.1519 to Smu.1522) and investigates its potential role in acid tolerance. Deletion of glnQHMP resulted in a 95% reduction in transport of radiolabeled glutamate compared to the wild-type UA159 strain. The addition of glutamate to metabolizing UA159 cells resulted in an increased production of acidic end products, whereas the glnQHMP mutant produced less lactic acid than UA159, suggesting a link between glutamate metabolism and acid production and possible acid tolerance. To investigate this possibility, we conducted a microarray analysis with glutamate and under pH 5.5 and pH 7.5 conditions which showed that expression of the glnQHMP operon was downregulated by both glutamate and mild acid. We also measured the growth kinetics of UA159 and its glnQHMP-negative derivative at pH 5.5 and found that the mutant doubled at a much slower rate than the parent strain but survived at pH 3.5 significantly better than the wild type. Taken together, these findings support the involvement of the glutamate transporter operon glnQHMP in the acid tolerance response in S. mutans.

Inactivation of VicK Affects Acid Production and Acid Survival of Streptococcus mutans

The regulation of acid production in and the tolerance to low pH of the cariogenic bacterium Streptococcus mutans have garnered considerable attention since both of these properties contribute substantially to the virulence of this organism. Frequent or prolonged exposure to acid end products, mainly lactic acid, that are present following the consumption of dietary sugars erodes the dental enamel, thereby initiating dental caries. Here we report the involvement of the S. mutans VicK sensor kinase in both the acidogenicity and the aciduricity of this bacterium. When cultures were supplemented with glucose, the glycolytic rate of a VicK null mutant was significantly decreased compared to the glycolytic rate of the wild type (P < 0.05), suggesting that there was impaired acid production. Not surprisingly, the VicK deletion mutant produced less lactic acid, while an acid tolerance response assay revealed that loss of VicK significantly enhanced the survival of S. mutans (P < 0.05). Compared to the survival rates of the wild type, the survival rates of the VicK-deficient mutant were drastically increased when cultures were grown at pH 3.5 with or without preexposure to a signal pH (pH 5.5). Global transcriptional analysis using DNA microarrays and S. mutans wild-type UA159 and VicK deletion mutant strains grown at neutral and low pH values revealed that loss of VicK significantly affected expression of 89 transcripts more than twofold at pH 5.5 (P < 0.001). The affected transcripts included genes with putative functions in transport and maintenance of cell membrane integrity. While our results provide insight into the acid-inducible regulon of S. mutans, here we imply a novel role for VicK in regulating intracellular pH homeostasis in S. mutans.

Fluoride released from glass-ionomer cement is responsible to inhibit the acid production of caries-related oral streptococci

Objectives Glass-ionomer cements (GICs) are known to have inhibitory effects on bacterial growth, but the biochemical mechanism of this property has not been fully understood. This study aimed to evaluate inhibitory effects of GIC on the acid production of caries-related oral streptococci, and to identify the components responsible for the inhibition. Methods An eluate was prepared by immersing set GIC in phosphate-buffered saline at 37 °C for 24 h. Fluoride and other elements in the eluate were quantified by fluoride ion electrode and atomic absorption photometry, respectively. Streptococcus mutans NCTC 10449 and Streptococcus sanguinis NCTC 10556 were used to evaluate the pH fall and the rate of acid production after the addition of glucose in the presence or absence of the eluate. Acidic end products from glucose were also assayed by carboxylic acid analyzer. Results The eluate contained silicon (1.24 ± 0.26 mM), fluoride (0.49 ± 0.02 mM) and aluminum (0.06 ± 0.00 mM), and inhibited the pH fall and the acid production rate of both streptococci at acidic pH, with a concomitant decrease in lactic acid production. These effects were comparable to those of a potassium fluoride solution containing the same concentration of fluoride as the eluate. Significance These results indicate that the GIC eluate inhibits the acid production of caries-related oral streptococci at acidic pH and that the effect is due to fluoride derived from the GIC. Thus, adjacent to GIC fillings, bacterial acid production and the subsequent bacterial growth may decrease, establishing a cariostatic environment.

Characterization of Lactic Acid Bacteria from Dry Sausages

ABSTRACTEight genera (Lactobacillus, Leuconostoc, Staphylococcus, Enterococcus, Lactococcus, Micrococcus, Streptococcus) are most commonly used meat starter cultures. The Lactobacilli associated with meat fermentation and the efforts to accurate classification and identification of them are becoming more important as various isolates of LAB become more commonly used as starter cultures.The present work deals with characterization of the microflora associated with naturally fermented Bulgarian sausages (Lukanka) and sausages (Lukanka) with defined starter culture produced by “Tandem”. More then 200 strains of genera Lactobacillus were isolated during the different stages of the fermentation process of the naturally fermented sausages. The morphological, cultural and physiological and biochemical analysis were performed. In such a system such as meat with a wide variety of complex substrates serving as sources of peptoses, organic acid and other fermentable compounds different end products are formed. Research on the production of lactic acid, determination of pH, screening for producers of antimicrobials was performed.

Response of Porphyromonas gingivalis to Heme Limitation in Continuous Culture

Porphyromonas gingivalis is an anaerobic, asaccharolytic, gram-negative bacterium that has essential requirements for both iron and protoporphyrin IX, which it preferentially obtains as heme. A combination of large-scale quantitative proteomic analysis using stable isotope labeling strategies and mass spectrometry, together with transcriptomic analysis using custom-made DNA microarrays, was used to identify changes in P. gingivalis W50 protein and transcript abundances on changing from heme-excess to heme-limited continuous culture. This approach identified 160 genes and 70 proteins that were differentially regulated by heme availability, with broad agreement between the transcriptomic and proteomic data. A change in abundance of the enzymes of the aspartate and glutamate catabolic pathways was observed with heme limitation, which was reflected in organic acid end product levels of the culture fluid. These results demonstrate a shift from an energy-efficient anaerobic respiration to a less efficient process upon heme limitation. Heme limitation also resulted in an increase in abundance of a protein, PG1374, which we have demonstrated, by insertional inactivation, to have a role in epithelial cell invasion. The greater abundance of a number of transcripts/proteins linked to invasion of host cells, the oxidative stress response, iron/heme transport, and virulence of the bacterium indicates that there is a broad response of P. gingivalis to heme availability.

The effect of packed red blood cell storage on arachidonic acid and advanced glycation end-product formation

The transfusion of packed red blood cells (PRBCs) is a significant risk to blood recipients. Blood banking procedures permit the storage of PRBCs for up to 42 days. Storage of PRBCs can cause polymorphonuclear granulocytes (PMNs) activation and the development of neutrophil-mediated transfusion-related acute lung injury. The aim of our study was to determine if PRBC storage has an influence on the formation of arachidonic acid (AA) and advanced glycation end products (AGEs). Twenty units of PRBCs were used to measure AA and AGE levels. The samples were taken on the 0th, 14th, 28th, and 42nd days of PRBC storage. The AA level was analyzed by gas-liquid chromatography-mass spectrometry and AGE level by an immunoenzymatic test. During the first 14 days of PRBC storage, the AA level significantly increased and then slowly decreased. The AGE level increased continuously during the whole time of the study. In a model experiment, the AA glycoxidation product trans-2-nonenal (T2N) formed adducts in reaction with hemoglobin which were detectable with the test for AGE. It is highly probable that the observed increase in AGE level is related to the decrease in AA in PRBCs, which can be associated with the formation of toxic aldehydes, especially T2N and 4-hydroxynonenal (HNE), from AA. Glucose in the PRBCs (preservative solution) can contribute to AGE formation as well. The formation of AGEs, HNE, and T2N in PRBCs, their influence on PMNs in vitro, and confirmation of our assumption need further studies.