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Citric acid 99%; CAS Number: 77-92-9; EC Number: 201-069-1; Linear Formula: HOC(COOH)(CH2COOH)2; find Sigma-Aldrich-C0759 MSDS, related peer-reviewed papers, technical documents, similar products & more at Sigma-Aldrich

Citric acid 99 77-92-9

Citric acid

Capsule endoscopy is an attractive alternative to colorectal cancer screening by conventional colonoscopy, but is currently limited by compromised mucosal visibility because of the lack of safe, controlled colonic insufflation. We have therefore developed a novel system of untethered, wireless-controlled carbon dioxide (CO2) insufflation for use in colonic capsule endoscopy, which this study aims to assess in vivo. This observational, nonsurvival, in vivo study used five Yorkshire-Landrace cross swine. A novel insufflation capsule was placed in the porcine colons, and we recorded volume of insufflation, time, force, visualization, and a pathologic assessment of the colon. The mean (standard deviation [SD]) diameter of insufflation was 32.1 (3.9) mm. The volume of CO2 produced successfully allowed complete endoscopic visualization of the mucosa and safe proximal passage of the endoscope. Pathologic examination demonstrated no evidence of trauma caused by the capsule. These results demonstrate the feasibility of a novel method of controlled colonic insufflation via an untethered capsule in vivo. This technological innovation addresses a critical need in colon capsule endoscopy.

Controlled colonic insufflation by a remotely triggered capsule for improved mucosal visualization.

Assay of Ornithine Decarboxylase and Spermidine/Spermine <I>N</I>1-acetyltransferase Activities.

A method for decalcification with citric acid.

Wheat straw hemicellulose films as affected by citric acid.

Determination of citric acid in fats.

Factors affecting the successful cryopreservation of honey bee (<I>Apis mellifera</I>) spermatozoa.

Antigen-retrieval procedure for bromodeoxyuridine immunolabeling with concurrent labeling of nuclear DNA and antigens damaged by HCl pretreatment.

New perspectives for citric acid production and application.

Prevention and management of wound infections receive a lot of attention, since the presence of micro-organisms interferes with the wound-healing process. The aim of this work was to use cyclodextrins (CDs) to endow hydrogels and gauzes with the ability to take up antiseptics and sustain their delivery for several hours. Benzalkonium chloride (BzCl) can form inclusion complexes with cross-linked CDs that regulate the release through an affinity-driven mechanism. Grafting of CDs to cotton gauzes using citric acid as the linker, at 190 °C and for 15 min, led to grafting yields of about 148%, much larger than those obtained at 180 °C or with shorter reaction times. Microbiological tests revealed that the BzCl-loaded networks can inhibit the growth of Staphylococcus epidermidis and Escherichia coli both on agar plates and in liquid medium. Furthermore, the antiseptic-loaded gauzes were able to inhibit biofilm formation by Staphylococcus aureus RN1HG pMV158GFP when applied in early stages of biofilm formation and could reduce the number of living cells in preformed biofilms grown in a chronic wound biofilm model. These findings highlight the role of CDs as main components of hydrogels and gauzes for the efficient delivery of antiseptics.

Antiseptic cyclodextrin-functionalized hydrogels and gauzes for loading and delivery of benzalkonium chloride.

The relative anti-aggregatory effects of currently prescribed platelet glycoprotein IIb/IIIa receptor antagonists during and after percutaneous coronary intervention for acute coronary syndromes have not been established. We randomized 70 acute coronary syndrome patients undergoing percutaneous coronary intervention to receive abciximab, eptifibatide, or tirofiban at doses used in the Evaluation of Platelet IIb/IIIa Inhibitor for STENTing (EPISTENT), Platelet glycoprotein IIb/IIIa in Unstable angina Receptor Suppression Using Integrilin Therapy (PURSUIT), and Platelet Receptor Inhibition in ischemic Syndrome Management in Patients Limited by Unstable Signs and symptoms (PRISM-PLUS)/Randomized Efficacy Study of Tirofiban for Outcomes and Restenosis (RESTORE) trials, respectively. Platelet aggregation (PA) in response to 20 micro mol/L of adenosine diphosphate was measured with turbidimetric aggregometry in both D-phenylalanyl-L-prolyl-L-arginine chloromethylketone and citrate-anticoagulated blood early (15 and 30 minutes) and late (4, 12, and 18 to 24 hours) after drug initiation. At 15 and 30 minutes, PA was significantly less inhibited by the tirofiban-RESTORE regimen compared with abciximab (P=0.028) and eptifibatide regimens (P=0.0001). The abciximab regimen, however, showed increasingly varied anti-aggregatory effects during continued infusion for > or =4 hours. Citrate exaggerated ex vivo platelet inhibition after eptifibatide and tirofiban, but had the opposite effect on abciximab. Of all regimens evaluated, the eptifibatide regimen inhibited PA most consistently throughout both the early and late periods. Currently recommended drug regimens to inhibit the platelet glycoprotein IIb/IIIa receptor have distinct pharmacodynamic profiles that might affect their relative efficacy in acute coronary syndromes and percutaneous coronary intervention.

Randomized COMparison of platelet inhibition with abciximab, tiRofiban and eptifibatide during percutaneous coronary intervention in acute coronary syndromes: the COMPARE trial. Comparison Of Measurements of Platelet aggregation with Aggrastat, Reopro, and Eptifibatide.

Supernatants of serum-free cultured mononuclear cells (MNC) contain a mix of immunomodulating factors (secretome), which have been shown to attenuate detrimental inflammatory responses following myocardial ischaemia. Inflammatory dilated cardiomyopathy (iDCM) is a common cause of heart failure in young patients. Experimental autoimmune myocarditis (EAM) is a CD4+ T cell-dependent model, which mirrors important pathogenic aspects of iDCM. The aim of this study was to determine the influence of MNC secretome on myocardial inflammation in the EAM model. BALB/c mice were immunized twice with an alpha myosin heavy chain peptide together with Complete Freund adjuvant. Supernatants from mouse mononuclear cells were collected, dialysed, and injected i.p. at Day 0, Day 7, or Day 14, respectively. Myocarditis severity, T cell responses, and autoantibody formation were assessed at Day 21. The impact of MNC secretome on CD4+ T cell function and viability was evaluated using in vitro proliferation and cell viability assays. A single high-dose application of MNC secretome, injected at Day 14 after the first immunization, effectively attenuated myocardial inflammation. Mechanistically, MNC secretome induced caspase-8-dependent apoptosis in autoreactive CD4+ T cells. MNC secretome abrogated myocardial inflammation in a CD4+ T cell-dependent animal model of autoimmune myocarditis. This anti-inflammatory effect of MNC secretome suggests a novel and simple potential treatment concept for inflammatory heart diseases.

Mononuclear cell secretome protects from experimental autoimmune myocarditis.

The G-Project committee was erected by the Japan Society for Gastroenterological Carcinogenesis with an aim of establishing a new classification scheme based on molecular biological characteristics that would supplement the conventional TNM classification to better predict outcome. In a literature search involving 822 articles on gastric cancer, eight molecules including p53, vascular endothelial growth factor (VEGF)-A, VEGF-C, matrix metalloproteinase-7 (MMP-7), human epidermal growth factor receptor 2, Regenerating islet-derived family, member 4, olfactomedin-4 and Claudin-18 were selected as candidates to be included in the new molecular classification scheme named G-factor. A total of 210 cases of gastric cancer who underwent curative R0 resection were registered from four independent facilities. Immunohistochemical staining for the aforementioned molecules was performed for the surgically resected specimens of the 210 cases to investigate the correlation between clinicopathological factors and expression of each molecule. No significant correlation was observed between the immunostaining expression of any of the eight factors and postoperative recurrence. However, the expressions of p53 and MMP-7 were significantly correlated with overall survival (OS). When 210 gastric cancer patients were divided into three groups based on the expression of p53 and MMP-7 (G0 group: negative for both p53 and MMP-7, n = 69, G1 group: positive for either p53 or MMP-7, n = 97, G2 group: positive for both of the molecules, n = 44), G2 group demonstrated significantly higher recurrence rate (59%) compared to 38% in G0 (p = 0.047). The multivariate regression analysis revealed that G2 group was independently associated with a shorter disease-free survival (DFS) (hazard ratio 1.904, 95% CI 1.098-3.303; p = 0.022), although the association with OS was not significant. Stage II patients among the G2 group had significantly inferior prognosis both in terms of OS and DFS when compared with those among the G0/G1 group, with survival curves similar to those of Stage III cases. G-factor based on the expression of p53 and MMP-7 was found to be a promising factor to predict outcome of Stage II/III gastric cancer, and possibly to help select the treatment for Stage II cancer, thus supplementing the conventional TNM system.

New molecular staging with G-factor supplements TNM classification in gastric cancer: a multicenter collaborative research by the Japan Society for Gastroenterological Carcinogenesis G-Project committee.

Porous films of p-type CuInS2, prepared by sulfurization of electrodeposited metals, are surface-modified with thin layers of CdS and TiO2. This specific porous electrode evolved H2 from photoelectrochemical water reduction under simulated sunlight. Modification with thin n-type CdS and TiO2 layers significantly increased the cathodic photocurrent and onset potential through the formation of a p-n junction on the surface. The modified photocathodes showed a relatively high efficiency and stable H2 production under the present reaction conditions.

Enhancement of solar hydrogen evolution from water by surface modification with CdS and TiO2 on porous CuInS2 photocathodes prepared by an electrodeposition-sulfurization method.

1H NMR was used to analyze human cerebrospinal fluid (CSF) from a group of neurological disease controls and from a vitamin B12 deficient patient. The spectra were acquired at either 7.06 or 9.40 T at ambient temperature with CSF freeze dried and reconstituted in 2H2O. 3-Trimethylsilyl propionate was used as an internal chemical shift and concentration reference. All of the CSF samples showed peaks for lactate, L-alanine, acetate, glutamine, citrate, creatine/creatinine and sugar resonances. There was good agreement between the metabolite concentrations as determined by NMR with those obtained using conventional chemical methods. 1D and 2D 1H NMR techniques along with J-coupling and T1 analysis were used to confirm the peak assignments. Methylmalonic acid could be detected and quantitated (ca 150 microM) in the CSF from the vitamin B12 deficient patient.

1H NMR characterization of normal human cerebrospinal fluid and the detection of methylmalonic acid in a vitamin B12 deficient patient.

In mice the transcription factor Elf5 is necessary for correct trophoblast development. Upon knockdown of Elf5, TS cells display neither a decrease in proliferation nor an increase in cell death but rather an increased propensity to differentiate. Such cells rapidly lose Sox2 and 3 expression, while transiently upregulating the giant cell differentiation determinant gene Hand1. Other genes affected within 24h of Elf5 knock-down, many of which have not previously been implicated in trophoblast development, exhibited in vivo expression domains and in vitro expression responses consistent with Elf5 having a role in counteracting trophoblast differentiation. In an ES to TS differentiation assay using Cdx2 overexpression with Elf5 loss of function cell lines, it was shown that Elf5 is necessary to prevent terminal trophoblast differentiation. This data thus suggest that Elf5 is a gatekeeper for the TS to differentiated trophoblast transition thereby preventing the precocious differentiation of the undifferentiated extraembryonic ectoderm.

Elf5 counteracts precocious trophoblast differentiation by maintaining Sox2 and 3 and inhibiting Hand1 expression.

The causal role of aneuploidy in cancer initiation remains under debate since mutations of euploidy-controlling genes reduce cell fitness but aneuploidy strongly associates with human cancers. Telomerase activation allows immortal growth by stabilizing telomere length, but its role in aneuploidy survival has not been characterized. Here, we analyze the response of primary human cells and murine hematopoietic stem cells (HSCs) to aneuploidy induction and the role of telomeres and the telomerase in this process. The study shows that aneuploidy induces replication stress at telomeres leading to telomeric DNA damage and p53 activation. This results in p53/Rb-dependent, premature senescence of human fibroblast, and in the depletion of hematopoietic cells in telomerase-deficient mice. Endogenous telomerase expression in HSCs and enforced expression of telomerase in human fibroblasts are sufficient to abrogate aneuploidy-induced replication stress at telomeres and the consequent induction of premature senescence and hematopoietic cell depletion. Together, these results identify telomerase as an aneuploidy survival factor in mammalian cells based on its capacity to alleviate telomere replication stress in response to aneuploidy induction.

Telomerase abrogates aneuploidy-induced telomere replication stress, senescence and cell depletion.

Controlling viral contamination is an important issue in the process development of monoclonal antibodies (MAbs) produced from mammalian cell lines. Virus filtration (VF) has been demonstrated to be a robust and effective clearance step which can provide ≥4 logs of reduction via size exclusion. The minimization of VF area by increasing flux and filter loading is critical to achieving cost targets as VFs are single use and often represent up to 10% of total purification costs. The research presented in this publication describes a development strategy focused on biophysical attributes of product streams that are directly applicable to VF process performance. This article summarizes a case study where biophysical tools (high-pressure size exclusion chromatography, dynamic light scattering, and absolute size exclusion chromatography) were applied to a specific MAb program to illustrate how changes in feed composition (pH, sodium chloride concentration, and buffer salt type) can change biophysical properties which correlate with VF performance. The approach was subsequently refined and expanded over the course of development of three MAbs where performance metrics (i.e., loading and flux) were evaluated for two specific virus filters (Viresolve Pro and Planova 20N) during both unspiked control runs and virus clearance experiments. The analyses of feed attributes can be applied to a decision tree to guide the recommendation of a VF filter and operating conditions for use in future MAb program development. The understanding of the biophysical properties of the feed can be correlated to virus filter performance to significantly reduce the mass of product, time, and costs associated with virus filter step development.

Prediction of viral filtration performance of monoclonal antibodies based on biophysical properties of feed.

The tumor suppressor, PTEN, is one of the most commonly mutated genes in cancer. Recently, PTEN has been shown to localize in the nucleus and is required to maintain genomic stability. Here, we show that nuclear PTEN, independent of its phosphatase activity, is essential for maintaining heterochromatin structure. Depletion of PTEN leads to loss of heterochromatic foci, decreased chromatin compaction, overexpression of heterochromatic genes, and reduced protein stability of heterochromatin protein 1 α. We found that the C-terminus of PTEN is required to maintain heterochromatin structure. Additionally, cancer-associated PTEN mutants lost their tumor-suppressor function when their heterochromatin structure was compromised. We propose that this novel role of PTEN accounts for its function in guarding genomic stability and suppressing tumor development.

Nuclear PTEN tumor-suppressor functions through maintaining heterochromatin structure.

Exposure to improvised explosive devices can result in a unique form of traumatic brain injury--blast-induced traumatic brain injury (bTBI). At the mild end of the spectrum (mild bTBI [mbTBI]), there are cognitive and mood disturbances. Similar symptoms have been observed in post-traumatic stress disorder caused by exposure to extreme psychological stress without physical injury. A role of the monoaminergic system in mood regulation and stress is well established but its involvement in mbTBI is not well understood. To address this gap, we used a rodent model of mbTBI and detected a decrease in immobility behavior in the forced swim test at 1 d post-exposure, coupled with an increase in climbing behavior, but not after 14 d or later, possibly indicating a transient increase in anxiety-like behavior. Using in situ hybridization, we found elevated messenger ribonucleic acid levels of both tyrosine hydroxylase and tryptophan hydroxylase 2 in the locus coeruleus and the dorsal raphe nucleus, respectively, as early as 2 h post-exposure. High-performance liquid chromatography analysis 1 d post-exposure primarily showed elevated noradrenaline levels in several forebrain regions. Taken together, we report that exposure to mild blast results in transient changes in both anxiety-like behavior and brain region-specific molecular changes, implicating the monoaminergic system in the pathobiology of mbTBI.

Neurotransmitter Systems in a Mild Blast Traumatic Brain Injury Model: Catecholamines and Serotonin.

The Human Metabolome Database (HMDB, http://www.hmdb.ca) is a richly annotated resource that is designed to address the broad needs of biochemists, clinical chemists, physicians, medical geneticists, nutritionists and members of the metabolomics community. Since its first release in 2007, the HMDB has been used to facilitate the research for nearly 100 published studies in metabolomics, clinical biochemistry and systems biology. The most recent release of HMDB (version 2.0) has been significantly expanded and enhanced over the previous release (version 1.0). In particular, the number of fully annotated metabolite entries has grown from 2180 to more than 6800 (a 300% increase), while the number of metabolites with biofluid or tissue concentration data has grown by a factor of five (from 883 to 4413). Similarly, the number of purified compounds with reference to NMR, LC-MS and GC-MS spectra has more than doubled (from 380 to more than 790 compounds). In addition to this significant expansion in database size, many new database searching tools and new data content has been added or enhanced. These include better algorithms for spectral searching and matching, more powerful chemical substructure searches, faster text searching software, as well as dedicated pathway searching tools and customized, clickable metabolic maps. Changes to the user-interface have also been implemented to accommodate future expansion and to make database navigation much easier. These improvements should make the HMDB much more useful to a much wider community of users.

HMDB: a knowledgebase for the human metabolome.

Citrate is one of many cell culture components that affects the performance of serum-free, protein-free and animal protein-free cell culture systems used for biomanufacturing heterologous proteins such as monoclonal antibodies.

Citrate Serum-Free Medium Supplement

To standardize a procedure for the determination of the enzymatic assay of choloylglycine hydrolase.

Citric acid

99%

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