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Energy expenditure and caloric targets during continuous renal replacement therapy under regional citrate anticoagulation. A viewpoint.
Jonckheer, J, Spapen, H, Malbrain, MLNG, Oschima, T, De Waele, E
Clinical nutrition (Edinburgh, Scotland). 2020;(2):353-357
Abstract
BACKGROUND Indirect calorimetry (IC) is the gold standard for measuring energy expenditure in critically ill patients However, continuous renal replacement therapy (CRRT) is a formal contraindication for IC use. AIMS To discuss specific issues that hamper or preclude an IC-based assessment of energy expenditure and correct caloric prescription in CRRT-treated patients. METHODS Narrative review of current literature. RESULTS Several relevant pitfalls for validation of IC during CRRT were identified. First, IC measures CO2 production (VCO2) and O2 consumption to calculate resting energy expenditure (REE) with the Weir equation. VCO2 measurements are influenced by CRRT because CO2 is exchanged during the blood purification process. CO2 exchange also depends on type of pre- and/or postdilution fluid(s). CO2 dissolves in different forms with dynamic but unpredictable impact on VCO2. Second, the effect of immunologic activation and heat loss on REE caused by extracorporeal circulation during CRRT is poorly documented. Third, caloric prescription should be adapted to CRRT-induced in- and efflux of different nutrients. Finally, citrate, which is the preferred anticoagulant for CRRT, is a caloric source that may influence IC measurements and REE. CONCLUSION Better understanding of CRRT-related processes is needed to assess REE and provide individualized nutritional therapy in this condition.
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Citrate valve integrates mitochondria into photosynthetic metabolism.
Igamberdiev, AU
Mitochondrion. 2020;:218-230
Abstract
While in heterotrophic cells and in darkness mitochondria serve as main producers of energy, during photosynthesis this function is transferred to chloroplasts and the main role of mitochondria in bioenergetics turns to be the balance of the level of phosphorylation of adenylates and of reduction of pyridine nucleotides to avoid over-energization of the cell and optimize major metabolic fluxes. This is achieved via the establishment and regulation of local equilibria of the tricarboxylic acid (TCA) cycle enzymes malate dehydrogenase and fumarase in one branch and aconitase and isocitrate dehydrogenase in another branch. In the conditions of elevation of redox level, the TCA cycle is transformed into a non-cyclic open structure (hemicycle) leading to the export of the tricarboxylic acid (citrate) to the cytosol and to the accumulation of the dicarboxylic acids (malate and fumarate). While the buildup of NADPH in chloroplasts provides operation of the malate valve leading to establishment of NADH/NAD+ ratios in different cell compartments, the production of NADH by mitochondria drives citrate export by establishing conditions for the operation of the citrate valve. The latter regulates the intercompartmental NADPH/NADP+ ratio and contributes to the biosynthesis of amino acids and other metabolic products during photosynthesis.
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Role of Citrate in Pathophysiology and Medical Management of Bone Diseases.
Granchi, D, Baldini, N, Ulivieri, FM, Caudarella, R
Nutrients. 2019;(11)
Abstract
Citrate is an intermediate in the "Tricarboxylic Acid Cycle" and is used by all aerobic organisms to produce usable chemical energy. It is a derivative of citric acid, a weak organic acid which can be introduced with diet since it naturally exists in a variety of fruits and vegetables, and can be consumed as a dietary supplement. The close association between this compound and bone was pointed out for the first time by Dickens in 1941, who showed that approximately 90% of the citrate bulk of the human body resides in mineralised tissues. Since then, the number of published articles has increased exponentially, and considerable progress in understanding how citrate is involved in bone metabolism has been made. This review summarises current knowledge regarding the role of citrate in the pathophysiology and medical management of bone disorders.
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Citric Acid Production from Acorn Starch by Tannin Tolerance Mutant Aspergillus niger AA120.
Zhang, N, Jiang, JC, Yang, J, Wei, M, Zhao, J, Xu, H, Xie, JC, Tong, YJ, Yu, L
Applied biochemistry and biotechnology. 2019;(1):1-11
Abstract
In this study, acorn starch was investigated as a new material for fermenting production of citric acid by using a tannin tolerance mutant strain Aspergillus niger AA120. The mutant A. niger AA120 was obtained by initially atmospheric pressure plasma at room temperature (ARTP) mutagenesis and then tannin gradient domestication. ARTP experiments showed that a "double-saddle" shape of survival rate curve was achieved, and a positive mutation rate of 63.6% was reached by setting the implantation time of mutagenesis to 100 s. In contrast to the original stain at the presence of 20.0 g/L tannin in the medium, the selected mutant A. niger AA120 exhibits an increase of biomass by 43.76% to 32.9 g/L, and citric acid production capacity by 20.34% to 130.8 g/L, with 8% (w/w) of inoculation quantity, an initial pH of 6.2 and shaking speed of 250 r/min. In this work, we present a referable method for the mutagenesis screening of the A. niger, and the application of acorn starch as a new raw material for the development of the citric acid industry.
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Regional citrate anticoagulation for continuous renal replacement therapy.
Kindgen-Milles, D, Brandenburger, T, Dimski, T
Current opinion in critical care. 2018;(6):450-454
Abstract
PURPOSE OF REVIEW The delivery of an effective dialysis dose in continuous renal replacement therapy (CRRT) depends on adequate anticoagulation of the extracorporeal circuit. In most patients, either systemic heparin anticoagulation (SHA) or regional citrate anticoagulation (RCA) is used. This review will outline the basics and rationale of RCA and summarize data on safety and efficacy of both techniques. RECENT FINDINGS The basic principle of RCA is to reduce the level of ionized calcium in the extracorporeal circuit via infusion of citrate. This way, effective anticoagulation restricted to the extracorporeal circuit is achieved. SHA and RCA were compared in a variety of studies. RCA significantly prolonged filter lifetime, reduced bleeding complications and provided excellent control of uremia and acid-base status. RCA was also safe in the majority of patients with impaired liver function, whereas caution must be exerted in those with severe multiorgan failure and persistent hyperlactatemia. SUMMARY RCA per se is safe and effective for anticoagulation of CRRT. Compared to SHA, efficacy of anticoagulation is improved and adverse effects are reduced. RCA can be recommended as the anticoagulation mode of choice for CRRT in most ICU patients.
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Symptomatic Hyponatremia after Bowel Preparation: Report of Two Cases and Literature Review.
Costa, JM, Soares, JB
Acta medica portuguesa. 2017;(11):824-826
Abstract
INTRODUCTION Bowel preparation for colonoscopy and/or colorectal surgery can cause electrolyte imbalances. The risk of electrolyte imbalances seems to be related to the type of bowel cleansing solution, age of patients and comorbidities. CASE REPORT We report two cases of symptomatic hyponatremia (focal neurological signs and coma) after bowel preparation with sodium picosulfate/magnesium citrate for colonoscopy. In both cases, symptoms related to hyponatremia rapidly disappeared after sodium level correction with intravenous administration of hypertonic saline (3% NaCl). DISCUSSION Electrolyte imbalances are more common with sodium phosphate-based solutions (NaP) and sodium picosulfate/magnesium citrate, in patients older than 65, in patients treated with thiazide diuretics, angiotensin-converting-enzyme inhibitor, betablockers or antidepressants and in gastrectomized patients. These patients should use macrogol-based solutions (polyethylene glycol). CONCLUSION In patients at risk (patient > 65 years old, patients taking thiazide diuretics, angiotensin-converting-enzyme inhibitors, beta-blockers and antidepressants and with previous gastrectomy) we recommend macrogol-based solutions.
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Citrate pathophysiology and metabolism.
Monchi, M
Transfusion and apheresis science : official journal of the World Apheresis Association : official journal of the European Society for Haemapheresis. 2017;(1):28-30
Abstract
By chelating ionized calcium, citrate allows extracorporeal circuit anticoagulation without a bleeding risk for the patient. Citrate anticoagulation is also associated with a reduced activation of leucocytes and platelets. Citrate clearance by citric acid cycle (Krebs cycle) is not modified by renal failure, but is reduced by about 50% in patients with cirrhosis. Toxic effects of citrate result from a decrease in plasma ionized calcium of the patient. The first side effect is a prolongation of the QT interval. Clinical signs of hypocalcemia and hypotension in humans appear below 0.9mmol/L of plasma ionized calcium.
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Metabolic evaluation of first-time and recurrent stone formers.
Goldfarb, DS, Arowojolu, O
The Urologic clinics of North America. 2013;(1):13-20
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Abstract
Evaluation of stone formers should include careful attention to medications, past medical history, social history, family history, dietary evaluation, occupation, and laboratory evaluation. Laboratory evaluation requires at least serum chemistries and urinalysis. Twenty-four-hour urine collections are most appropriate for patients with recurrent stones or complex medical histories. However, these collections may be appropriate for some first-time stone formers, including those with comorbidities or large stones. Although twin studies demonstrate that heritability accounts for at least 50% of the kidney stone phenotype, the responsible genes are not clearly identified, and so genetic testing is rarely indicated.
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What controls fleshy fruit acidity? A review of malate and citrate accumulation in fruit cells.
Etienne, A, Génard, M, Lobit, P, Mbeguié-A-Mbéguié, D, Bugaud, C
Journal of experimental botany. 2013;(6):1451-69
Abstract
Fleshy fruit acidity is an important component of fruit organoleptic quality and is mainly due to the presence of malic and citric acids, the main organic acids found in most ripe fruits. The accumulation of these two acids in fruit cells is the result of several interlinked processes that take place in different compartments of the cell and appear to be under the control of many factors. This review combines analyses of transcriptomic, metabolomic, and proteomic data, and fruit process-based simulation models of the accumulation of citric and malic acids, to further our understanding of the physiological mechanisms likely to control the accumulation of these two acids during fruit development. The effects of agro-environmental factors, such as the source:sink ratio, water supply, mineral nutrition, and temperature, on citric and malic acid accumulation in fruit cells have been reported in several agronomic studies. This review sheds light on the interactions between these factors and the metabolism and storage of organic acids in the cell.
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Roles of organic acid anion secretion in aluminium tolerance of higher plants.
Yang, LT, Qi, YP, Jiang, HX, Chen, LS
BioMed research international. 2013;:173682
Abstract
Approximately 30% of the world's total land area and over 50% of the world's potential arable lands are acidic. Furthermore, the acidity of the soils is gradually increasing as a result of the environmental problems including some farming practices and acid rain. At mildly acidic or neutral soils, aluminium (Al) occurs primarily as insoluble deposits and is essentially biologically inactive. However, in many acidic soils throughout the tropics and subtropics, Al toxicity is a major factor limiting crop productivity. The Al-induced secretion of organic acid (OA) anions, mainly citrate, oxalate, and malate, from roots is the best documented mechanism of Al tolerance in higher plants. Increasing evidence shows that the Al-induced secretion of OA anions may be related to the following several factors, including (a) anion channels or transporters, (b) internal concentrations of OA anions in plant tissues, (d) temperature, (e) root plasma membrane (PM) H(+)-ATPase, (f) magnesium (Mg), and (e) phosphorus (P). Genetically modified plants and cells with higher Al tolerance by overexpressing genes for the secretion and the biosynthesis of OA anions have been obtained. In addition, some aspects needed to be further studied are also discussed.