Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “CITRATES”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 865 records · Page 48Linked to original sources
PubMed2001

Vanadium(IV)-citrate complex interconversions in aqueous solutions. A pH-dependent synthetic, structural, spectroscopic, and magnetic study.

Citrate is abundantly encountered in biological fluids as a natural metal ion chelator. Vanadium participates in biological processes as a catalyst in the active sites of metalloenzymes, as a metabolic regulator, as a mitogenic activator, and as an insulin-mimicking agent. Thus, vanadium chemistry with natural chelators, such as citrate, may have immediate implications on its role in a cellular milieu, and its action as a biological agent. In an effort to comprehend the aqueous chemistry of one of vanadium's oxidation states, namely, V(IV), implicated in its biological activity, reactions of VCl(3) and citric acid were pursued in water and led to V(IV)-citrate complexes, the nature and properties of which depend strongly on the solution pH. Analytical, FT-IR, UV/vis, EPR, and magnetic susceptibility data supported the formulation of X(4)[[VO(H(-1)Cit)](2)] x nH(2)O (H(-1)Cit = C(6)H(4)O(7)(4-); X = K(+), n = 6 (1); X = Na(+), n = 12 (2); X = NH(4)(+), n = 2 (3)) (pH approximately 8) and X(3)[[V(2)O(2)(H(-1)Cit)(Cit)]] x nH(2)O (X = K(+), n = 7 (4)) (pH approximately 5). Complex 2 crystallizes in space group P2(1)/c, a = 11.3335(9) A, b = 15.788(1) A, c = 8.6960(6) A, beta = 104.874(3) degrees, V = 1503.8(2), Z = 2. Complex 3 crystallizes in space group P one macro, a = 9.405(1) A, b = 10.007(1) A, c = 13.983(2) A, alpha = 76.358(4) degrees, beta = 84.056(4) degrees, gamma = 66.102(4) degrees, V = 1169.2(3), Z = 2. Complex 4 crystallizes in space group P2(1)nb, a = 9.679(4) A, b = 19.618(8) A, c = 28.30(1) A, V = 5374.0(4), Z = 8. The X-ray structures of 1-4 are V(2)O(2) dimers, with the citrate displaying varying coordination numbers and modes. 1 exhibits a small ferromagnetic interaction, whereas 4 exhibits an antiferromagnetic interaction between the V(IV) ions. 1 and 4 interconvert with pH, thus rendering the pH a determining factor promoting variable structural, electronic, and magnetic properties in V(IV)-citrate species. The observed aqueous behavior of 1-4 is consistent with past solution speciation studies, and contributes to the understanding of significant aspects of the biologically relevant vanadium(IV)-citrate chemistry.

Journal Article↗
PubMed2001

Differential effects of citrate versus PPACK anticoagulation on measured platelet inhibition by abciximab, eptifibatide and tirofiban.

BACKGROUND: High levels of glycoprotein (GP) IIb/IIIa receptor inhibition are required to prevent arterial thrombosis following percutaneous coronary intervention. Ex-vivo turbidometric platelet aggregation in citrate anticoagulated blood samples has been the primary method previously utilized to derive dose regimens for administering platelet GP IIb/IIIa inhibitors. Enhanced GP IIb/IIIa binding and inhibition of platelet aggregation for eptifibatide secondary to citrate induced reduction of ionized plasma calcium concentrations has been reported. METHODS/RESULTS: We evaluated the differential effects of citrate versus PPACK anticoagulation on turbidometric platelet inhibition in normal volunteers by eptifibatide, tirofiban or abciximab. The decrease in ionized calcium afforded by citrate was associated with enhanced in vitro platelet inhibition for all three GP IIb/IIIa inhibitors, including abciximab. The magnitude of citrate effect was greatest for eptifibatide. Both tirofiban and abciximab have similar citrate calcium chelation associated enhancement of measured platelet inhibition. CONCLUSION: Accurate assessment and comparison of platelet inhibition by GP IIb/IIIa inhibitors may require avoidance of calcium chelating anticoagulants.

Abciximab↗
PubMed1997

In vitro fertilization with low-dose clomiphene citrate stimulation in women who respond poorly to superovulation.

PURPOSE: Our experience with IVF using low-dose clomiphene citrate for stimulation in "non-" and "poor" responders was reviewed and the treatment outcomes with the previous controlled ovarian stimulation cycles in which hMG and GnRH agonist were used were compared. METHODS: The treatment outcome in 11 non- and 20 poor responders having 30 and 53 clomiphene citrate IVF treatment cycles, respectively, were compared with the treatment outcome in the previous long-protocol buserelin/hMG cycles. RESULTS: The clinical pregnancy rates per oocyte collection achieved in the first clomiphene citrate cycle in non (9.1%)- and poor (10%) responders were comparable to those achieved by poor responders (11.9%) who had buserelin/hMG using the long protocol. Although the numbers were small, a similar pregnancy rate could still be achieved in poor responders up to the third attempt using clomiphene citrate. CONCLUSIONS: IVF using long-protocol buserelin/hMG is more successful than using clomiphene citrate stimulation. However, this advantage may not be significant in those women with a previous poor response to buserelin/hMG. It is suggested that for such poor responders, three attempts of IVF in a clomiphene citrate cycle may offer a viable therapeutic alternative before reverting to more stressful, expensive, and time-consuming treatment.

Adult↗
PubMed2003

Citrate uniport by the mitochondrial tricarboxylate carrier: a basis for a new hypothesis for the transport mechanism.

The tricarboxylate transport system located in the inner mitochondrial membrane was studied as an isolated protein reconstituted in proteoliposomes. The effects on the transport of citrate by various reagents, specific for different aminoacid residues, were analyzed. In the group of SH reagents, it was found that N-ethylmaleimide is an irreversible inhibitor of the citrate-citrate exchange, while HgCl2 and the mercurial mersalyl cause a rapid unidirectional efflux of citrate from liposomes. It was demonstrated that NEM and mercurials act on different SH groups. Dithioerythritol is not able to reverse the effect of mersalyl unless another reagent, pyridoxalphosphate, is present. Pyridoxalphosphate itself, a reagent specific for NH2 residues, is an effective inhibitor of citrate exchange transport, as measured in both influx and efflux, but it has no effect on the mercurial-induced efflux. The same behavior was observed with diethylpyrocarbonate, a reagent specific for histidine and tyrosine residues. Interestingly, a slow basic efflux of internal citrate, in the absence of countersubstrate, was observed in proteoliposomes. Because it is inhibited by the same reagents acting on the exchange process, it is deduced that it is catalyzed by the tricarboxylate carrier. The ability of the carrier to perform a uniport of the substrate suggests the presence of a single substrate binding site on the carrier protein. A preliminary kinetic approach indicates that such a transport model is compatible with this theory.

Animals↗
PubMed1996

The safety and efficacy of ranitidine bismuth citrate in combination with antibiotics for the eradication of Helicobacter pylori.

BACKGROUND: Ranitidine bismuth citrate is a novel salt of ranitidine and a bismuth citrate complex. It has intrinsic antisecretory and anti-Helicobacter pylori activity, but monotherapy rarely eradicates H. pylori infection in man. AIM: A pilot study to investigate rates of H. pylori eradication achieved by co-prescription of ranitidine bismuth citrate with antibiotics, and to identify several regimens which would merit further investigation. METHOD: One hundred dyspeptic patients infected with H. pylori were randomly allocated to treatment with ranitidine bismuth citrate 800 mg b.d. plus either amoxycillin, metronidazole, clarithromycin, cefuroxime axetil, tetracycline, tetracycline plus metronidazole or clarithromycin plus tetracycline for 14 days. Eradication of infection was assessed using the 13C-urea breath test 4 weeks after the end of treatment. RESULTS: In a per protocol analysis eradication of H. pylori ranged between 22 and 100%; the intention-to-treat eradication rates ranged between 15 and 92%. No adverse events were specifically attributed to ranitidine bismuth citrate. CONCLUSION: Co-prescription therapy, using ranitidine bismuth citrate and one or more antibiotics, is suitable for further investigation in large-scale clinical trials in patients infected with H. pylori.

Adult↗
PubMed1997

Ranitidine bismuth citrate with clarithromycin versus omeprazole with amoxycillin in the cure of Helicobacter pylori infection.

AIM: To compare the efficacy of ranitidine bismuth citrate plus clarithromycin (RBC-C) vs. omeprazole plus amoxycillin (OME-AMO) in the cure of Helicobacter pylori infection. METHODS: In this double-blind, multicentre, parallel-group study 122 H. pylori-positive patients with active duodenal ulcer or gastritis, with confirmed history of duodenal ulcer, were randomized to treatment with ranitidine bismuth citrate 400 mg b.d. plus clarithromycin 500 mg b.d. or omeprazole 20 mg b.d. plus amoxycillin 1000 mg b.d. for 14 days, followed by 14 days of ranitidine bismuth citrate 400 mg b.d. or omeprazole 20 mg once daily, respectively, to facilitate ulcer healing. Endoscopy was carried out at the start of the study and 28 days after the end of treatment. At each endoscopy four biopsies were obtained from the antrum and four biopsies from the corpus, for rapid urease test, histology and culture. H. pylori infection was defined as a positive urease test, confirmed by histology or culture. Cure of H. pylori infection was defined as negative urease test, histology or culture from both sites. RESULTS: Per-protocol, all-patients-treated and intention-to-treat cure rates (95% confidence interval) were, respectively, 90% (81-89%), 90% (82-89%) and 84% (74-93%) for ranitidine bismuth citrate plus clarithromycin, and 39% (27-54%), 44% (31-57%) and 41% (29-53%) for omeprazole plus amoxycillin, P < 0.00001. Both regimens were well tolerated. Eight patients were lost to follow-up, for lack of efficacy (one patient), adverse events (three patients) or refusal of second endoscopy (four patients). CONCLUSION: Ranitidine bismuth citrate 400 mg b.d. with clarithromycin 500 mg b.d. is superior to omeprazole 20 mg b.d. with amoxycillin 1000 mg b.d. Ranitidine bismuth citrate with clarithromycin is the first dual therapy with high cure rates and good tolerance, and is easy to take. It may therefore prove a suitable first-line treatment in H. pylori infection.

Adolescent↗
PubMed2002

One-week ranitidine bismuth citrate, amoxicillin and metronidazole triple therapy for the treatment of Helicobacter pylori infection in Chinese.

BACKGROUND: We have previously shown that ranitidine bismuth citrate-based, clarithromycin-containing triple therapy achieves a higher eradication rate than proton pump inhibitor-based regimens in areas with a high prevalence of metronidazole resistance. AIM: To evaluate whether this higher efficacy of ranitidine bismuth citrate over proton pump inhibitor can be extended to non-clarithromycin-containing regimens. METHODS: Helicobacter pylori-positive dyspeptic patients were randomized to receive either ranitidine bismuth citrate, 400 mg, amoxicillin, 1000 mg, and metronidazole, 400 mg, or omeprazole, 20 mg, amoxicillin, 1000 mg, and metronidazole, 400 mg, each given twice daily for 1 week. H. pylori eradication was confirmed by 13C-urea breath test 5 weeks later. The side-effects of the treatments were documented. RESULTS: Two hundred and twenty-nine patients were eligible for analysis. By intention-to-treat and per protocol analysis, the eradication rates were 77% and 79%, respectively, in the ranitidine bismuth citrate-amoxicillin-metronidazole group and 77% and 82%, respectively, in the omeprazole-amoxicillin-metronidazole group (P = 0.58 and P = 0.65). However, patients in the omeprazole-amoxicillin-metronidazole group reported a significantly higher incidence of minor side-effects when compared to those in the ranitidine bismuth citrate-amoxicillin-metronidazole group (P = 0.001). CONCLUSIONS: Ranitidine bismuth citrate-amoxicillin-metronidazole was equally as effective as omeprazole-amoxicillin-metronidazole triple therapy, and may be considered as an alternative non-clarithromycin-based regimen in the Chinese population.

Adult↗
PubMed2003

Association between vitamin D receptor gene polymorphisms and tubular citrate handling in calcium nephrolithiasis.

OBJECTIVES: Hypocitraturia is a risk factor for calcium nephrolithiasis. 1,25(OH)2D3 influences renal citrate handling and enhances citraturia. The aim of this study was to evaluate the relationship between vitamin D receptor (VDR) allelic variant and urinary citrate excretion in recurrent stone formers (SF) patients. DESIGN: Case-control study. SUBJECTS: A total of 220 recurrent calcium oxalate SF patients and 114 healthy control (C) subjects were enrolled for this study. Subjects with urinary tract infections, hyperparathyroidism, cystinuria >70 micromol/24 h, gouty diathesis, renal tubular acidosis, renal failure, chronic diarrhoeal states, intake of thiazide diuretics, angiotensin-converting enzyme (ACE)-inhibitors, glucocorticoids or oestrogens were excluded. A standard constant diet was given for 7 days. The 24-h urinary citrate excretion and the active tubular reabsorption of filtered citrate (Rcit) were evaluated. Hypocitraturia was defined as a urinary citrate excretion lower than 1.7 mmol day-1. Stone formers patients and C were genotyped for BsmI and TaqI VDR alleles. Contingency table chi-square tests were used to compare genotype frequencies in hypocitraturic SF patients, normocitraturic SF and C. RESULTS: The prevalence of hypocitraturia in SF patients was 32.7% (72 of 200). Hypocitraturia in these patients resulted from excessive Rcit of a normal load of citrate. We found a different distribution (P < 0.05) of BsmI and TaqI VDR genotypes in hypocitraturic SF patients compared with normocitraturic SF and C. In particular, the prevalence of bb and TT VDR genotypes in hypocitraturic SF was significantly higher than in normocitraturic SF and C. CONCLUSIONS: These results point to a genetic association between BsmI and TaqI VDR polymorphisms and idiopathic hypocitraturia in calcium-oxalate recurrent SF patients.

Adult↗
PubMed2002

Regional anticoagulation with acid citrate dextrose-A for extracorporeal photoimmunochemotherapy.

BACKGROUND AND OBJECTIVES: During photopheresis, intravenous heparin is used to prevent clotting in the extracorporeal circuit. Regional citrate anticoagulation could lower the risks associated with heparin treatment. MATERIALS AND METHODS: Four-hundred and six photophereses procedures that were anticoagulated by acid citrate dextrose-A (ACD-A) (of which 343 were performed in patients at risk for haemorrhage) were analysed together with 278 heparin-anticoagulated treatments. RESULTS: Four-hundred and four of 406 citrate treatments were completed. Seven transient paresthesias (1.73%), five of which occurred in the first 50 treatments, were observed. Bleeding complications were noted during heparin anticoagulation (1.07%), but not during citrate anticoagulation. During photopheresis, haemoglobin values and platelet counts decreased by 11.4% and 14.6%, respectively (P < 0.0001). Twenty-four hours after treatment, haemoglobin values, and platelet and leucocyte counts were still lower than at baseline (P < 0.0001). The changes of haemoglobin, platelet and leucocyte values did not differ for citrate and heparin. CONCLUSIONS: In patients with contraindications against heparin use, ACD-A citrate anticoagulation during photopheresis is a safe and efficient alternative. Photopheresis induces profound changes of the blood count, irrespective of the anticoagulation method.

Adolescent↗
PubMed1999

Magnesium citrate-bisacodyl regimen proves better than castor oil for colonoscopic preparation.

BACKGROUND: A clean colon preparation prior to endoscopy or X-ray examination is essential to obtain an accurate diagnosis. In order to determine which of two easily made preparations is better, this study compares colon cleansing efficacy, patient acceptance and side effects in patients given either a magnesium citrate-bisacodyl or a castor oil regimen prior to colonoscopy. METHODS: Seventy outpatients scheduled for colonoscopy were randomized to receive one of two bowel evacuation regimens on the day prior to the examination. Group 1 (n = 36) received a magnesium citrate solution (250 mL) and bisacodyl (10 mg, orally). Group 2 (n = 34) received castor oil (60 mL, orally). RESULTS: The cleansing effect of the magnesium citrate-bisacodyl regimen was significantly better than that of castor oil in the ascending colon and caecum (cleansing scores 5.2+/-1.2 vs 3.5+/-1.3, P< 0.0001), but similar to that of castor oil in the recto-sigmoid, descending and transverse colon. Abdominal pain (38 vs 11%, P< 0.01) and nausea (29 vs 8%, P<0.05) were significantly more common in patients receiving the castor oil preparation than in patients administered with the magnesium citrate-bisacodyl regimen. More patients complained of poor acceptance with the castor oil regimen than with the magnesium citrate-bisacodyl regimen (24 vs 8%, P=0.06). CONCLUSIONS: A combined oral magnesium citrate and bisacodyl regimen is effective and better than castor oil for colonoscopic preparation.

Administration, Oral↗
PubMed1999

Regional citrate anticoagulation in continuous venovenous hemofiltration in critically ill patients with a high risk of bleeding.

BACKGROUND: Systemic heparinization is associated with a high rate of bleeding when used to maintain patency of the extracorporeal circuit during continuous renal replacement therapy (CRRT) in critically ill patients. Regional anticoagulation can be achieved with citrate, but previously described techniques are cumbersome and associated with metabolic complications. METHODS: We designed a simplified system for delivering regional citrate anticoagulation during continuous venovenous hemofiltration (CVVH). We evaluated filter life and hemorrhagic complications in the first 17 consecutive patients who received this therapy at our institution. Blood flow rate was set at 180 ml/min. Ultrafiltration rate was maintained at 2.0 liters/hr and citrate-based replacement fluid (trisodium citrate 13.3 mM, sodium chloride 100 mM, magnesium chloride 0.75 mM, dextrose 0.2%) was infused proximal to the filter to maintain the desired fluid balance. Calcium gluconate was infused through a separate line to maintain a serum-ionized calcium level of 1.0 to 1.1 mM. RESULTS: All patients were critically ill and required mechanical ventilation and vasopressor therapy. Systemic heparin anticoagulation was judged to be contraindicated in all of the patients. A total of 85 filters were used, of which 64 were lost because of clotting, with a mean life span of 29.5 +/- 17.9 hours. The remaining 21 filters were discontinued for other reasons. Control of fluid and electrolyte balance and azotemia was excellent (mean serum creatinine after 48 to 72 hr of treatment was 2.4 +/- 1.2 mg/dl). No bleeding episodes occurred. Two patients, one with septic shock and the other with fulminant hepatic failure, developed evidence for citrate toxicity without a significant alteration in clinical status. Nine patients survived (52.9%). CONCLUSION: Our simplified technique of regional anticoagulation with citrate is an effective and safe form of anticoagulation for CVVH in critically ill patients with a high risk of bleeding.

Adult↗
PubMed2002

Controlled study of citrate effects and response to i.v. calcium administration during allogeneic peripheral blood progenitor cell donation.

BACKGROUND: Leukapheresis procedures are generally performed at citrate anticoagulation rates extrapolated from shorter plateletpheresis procedures. However, neither the metabolic effects nor the management of associated symptoms have been critically evaluated during leukapheresis in healthy donors. STUDY DESIGN AND METHODS: Symptom assessments (n = 315) and laboratory analyses (n = 49) were performed during 244 procedures performed with and 71 without prophylactic calcium (Ca) chloride or Ca gluconate given at a dose linked to the citrate infusion rate (1.0-2.2 mg/kg/min). RESULTS: During leukapheresis of 12 to 25 L processed, ionized Ca and ionized magnesium (Mg) decreased as much as 35 and 56 percent, respectively, each exhibiting a tight negative correlation with marked increases in serum citrate levels. Significant increases in urinary Ca and Mg excretion accompanied the renal excretion of a large citrate load. Serum divalent cation levels remained depressed 24 hours after leukapheresis. Symptoms were more frequent in donors who were women, had low initial total Mg levels, and underwent procedures in which larger volumes were processed at higher citrate infusion rates. Ca infusions reduced clinically significant paresthesias by 96 percent and also attenuated decreases in serum potassium. Ca chloride maintained higher Ca levels than Ca gluconate. CONCLUSIONS: Prophylactic Ca infusions safely attenuate the marked metabolic effects of citrate administration and promote faster, more comfortable, leukapheresis procedures.

Calcium↗
PubMed2003

Pediatric convective hemofiltration: Normocarb replacement fluid and citrate anticoagulation.

BACKGROUND: Continuous venovenous hemofiltration (CVVH) may be preferable over continuous venovenous hemodialysis (CVVHD) in sepsis; however, CVVH use is limited by the lack of commercially produced bicarbonate replacement solutions in the United States. Anticoagulation used for hemofiltration traditionally has been either heparin or citrate based, but to date, citrate protocols have been used predominately in CVVHD. When CVVH has been used with citrate anticoagulation, replacement solutions have had to be custom made in the pharmacy. METHODS: We describe a protocol used in a series of 9 children with sepsis who underwent CVVH with the use of a commercially available bicarbonate solution (Normocarb; Dialysis Solutions Inc, Richmond Hill, Ontario, Canada) and a commercially available citrate solution (Anticoagulant Citrate Dextrose Solution Formula A [ACD-A]; Baxter Health Care, Deerfield, IL). This simplified approach to citrate anticoagulation with CVVH used Normocarb as a prefilter replacement solution under provisions of the 1997 Food and Drug Administration Modernization Act. RESULTS: All patients had acceptable levels of solute and ultrafiltration clearance with this approach. CVVH circuit life averaged 71 hours (range, 37 to 131 hours), influenced in part by the industry recommendation to change the circuit at 72 hours, whereas no complications from this protocol were identified. CONCLUSION: Similar to CVVHD, this protocol is effective and simple in its components, using industry-produced solutions, avoiding the need for pharmacy-made solutions, and limiting cost and potential risk for compounding errors. Although not the purpose of this report, the patient survival rate was 55%.

Adolescent↗
PubMed2004

Bone resorption and "relative" immobilization hypercalcemia with prolonged continuous renal replacement therapy and citrate anticoagulation.

Regional citrate anticoagulation is an alternative to heparin in patients with bleeding diatheses who require continuous renal replacement therapy (CRRT). The short-term metabolic consequences that occur with citrate anticoagulation are well described and usually manageable if established protocols are followed vigilantly. Because of its customary short-term nature, the long-term consequences of CRRT with citrate are less often considered and have not been reported. The authors present the case of a woman with multisystem organ failure and prolonged acute renal failure who required CRRT for 120 days. Throughout her hospital course, adequate regional anticoagulation was achieved by blocking the coagulation cascade via the chelation of calcium by citrate. Despite an appropriate drop in the postfilter ionized calcium level, by 8 weeks after the initiation of CRRT, the patient was able to normalize serum calcium levels without the customary calcium infusion. Bone resorption owing to prolonged immobilization leading to hypercalcemia is a known complication of critically ill patients. This problem is more pronounced in patients with high bone turnover rates owing to conditions such as secondary hyperparathyroidism. In this particular case, the chelation of calcium by citrate masked the ensuing immobilization hypercalcemia, resulting in marked bone loss and bilateral spontaneous femoral fractures in the context of normal calcium levels. In critically ill patients sustained with prolonged CRRT with citrate anticoagulation, bone resorption and "relative" immobilization hypercalcemia may manifest as normal serum calcium levels in the face of falling calcium infusion rate requirements.

Adult↗
PubMed2006

Uterine effects of clomiphene citrate in women with polycystic ovary syndrome: a prospective controlled study.

BACKGROUND: Previous data on the efficacy of clomiphene citrate, the most commonly used drug for treating anovulatory infertility in patients with polycystic ovary syndrome (PCOS), have shown a discrepancy between ovulation and pregnancy rates. In the present subanalysis (of a larger previously published randomized controlled trial), the effect of clomiphene citrate on several ultrasonographic markers of uterine receptivity in PCOS patients who ovulated under treatment was studied. METHODS: Thirty-three PCOS women who ovulated under 150 mg daily clomiphene citrate and 33 healthy controls were studied. Uterine, subendometrial and endometrial blood flows, endometrial thickness and pattern were assessed using serial ultrasonographic assessments. The data were analysed before and after grouping the clomiphene citrate-stimulated ovulatory cycles for reproductive outcome [unfavourable (ovulation alone or early pregnancy loss) or favourable outcome (clinical pregnancy and/or live birth)]. RESULTS: Both before and during treatment, uterine vascularity assessed at all sites was significantly lower in the PCOS group than in controls. Endometrial thickness and pattern were impaired in the PCOS group under clomiphene citrate treatment. A significant difference in all ultrasonographic parameters was observed between cycles ending in unfavourable versus those ended in favourable outcome. CONCLUSIONS: Clomiphene citrate administration alters several surrogate ultrasonographic parameters of uterine receptivity, and this effect could be crucial for its efficacy.

Adult↗
PubMed2002

Iron deficiency decreases mitochondrial aconitase abundance and citrate concentration without affecting tricarboxylic acid cycle capacity in rat liver.

Mitochondrial aconitase (m-acon) is the tricarboxylic acid (TCA) cycle enzyme that converts citrate to isocitrate. m-Acon mRNA is a potential target for regulation by iron regulatory proteins (IRPs), suggesting a link between dietary iron intake, m-acon synthesis, and energy metabolism. Our previous studies indicate that m-acon is one of a limited number of proteins that is down-regulated in iron-deficient liver. Here we use isolated hepatocytes to study the relationships among decreased m-acon abundance, TCA cycle function and cellular citrate concentration in iron deficiency. Rats were fed an iron-deficient (ID) (2 mg Fe/kg diet) diet, or they were pair-fed (PF) or freely fed (C) a control diet (50 mg Fe/kg diet) for up to 21 d. Hepatocyte total IRP activity was greater by d 2 in the ID group than in the C and PF groups and by d 10, the difference was maximal. Liver IRP activity was inversely correlated with m-acon abundance (r = -0.93, P < 0.0001). However, the decrease in m-acon abundance did not affect the ability of hepatocytes to oxidize 2-[(14)C]pyruvate or 1-[(14)C]acetate, indicating that TCA cycle capacity was not affected. Interestingly, by d 21, total liver citrate concentration was 40% lower in ID than in PF rats, suggesting enhanced utilization of citrate. However, the decrease in citrate concentration was not reflected in a change in liver total lipid concentration. Taken together, our results indicate that the iron-dependent regulation of m-acon in liver does not alter TCA cycle capacity but suggest that IRP-mediated changes in m-acon expression may modulate citrate use in other aspects of intermediary or iron metabolism.

Aconitate Hydratase↗
PubMed2003

Ferric citrate is half as effective as ferrous sulfate in meeting the iron requirement of juvenile tilapia, Oreochromis niloticus x O. aureus.

Two growth experiments were conducted to estimate the minimum dietary iron requirement for juvenile hybrid tilapia, Oreochromis niloticus x O. aureus. Purified diets containing 0, 10, 30, 50, 100, 150, 200 and 400 mg Fe/kg from ferric citrate (Experiment 1) and 0, 10, 30, 50, 100, 150 and 200 mg Fe/kg from ferrous sulfate (Experiment 2) were fed to tilapia (mean initial weight: 0.63 +/- 0.01 g, Experiment 1; 0.64 +/- 0.01 g, Experiment 2) for 8 wk. In Experiment 2, 150 mg Fe/kg from ferric citrate was also included for comparison. The rearing water contained 1.07 micro mol/L iron, and supplemental levels were confirmed by analysis. Each diet was fed to three replicate groups of fish. In Experiment 1, weight gain and feed efficiency (FE) were highest (P < 0.05) in fish fed the diet supplemented with 150 mg Fe/kg, followed by fish fed diets with 50, 100 and 200 mg Fe/kg and lowest in fish fed the unsupplemented control diet. Hepatic iron concentration was highest in fish fed diets supplemented with >150 mg Fe/kg, followed by fish fed the diet with 100 mg Fe/kg and lowest in fish fed diets with </=10 mg Fe/kg. Hemoglobin (Hb) and hematocrit (Hct) were higher in fish fed diets with >/=100 mg Fe/kg and mean corpuscular volume (MCV) and mean corpuscular hemoglobin (MCH) were higher in fish fed diets with >/=150 mg Fe/kg than in fish fed the diet without iron supplementation. In Experiment 2, weight gain was higher in fish fed the diet with 50 mg Fe/kg than in fish fed diets with 150, 200 and </=30 mg Fe/kg. FE was higher in fish fed diets with 50 and 100 mg Fe/kg and the ferric citrate comparison diet than in fish fed diets with </=10 mg Fe/kg. Hepatic iron concentration was higher in fish fed diets with >/=50 mg Fe/kg and the ferric citrate comparison diet than fish fed diets with </=30 mg Fe/kg. Hb, Hct, MCV and MCH were higher in fish fed diets with >/=50 mg Fe/kg than in fish fed the unsupplemented control diet. Analyses by polynomial regression of weight gain and by broken-line regression of hepatic iron and blood Hb concentrations indicated that the dietary iron requirement for tilapia is approximately 150-160 mg Fe/kg and 85 mg Fe/kg with ferric citrate and ferrous sulfate as the iron source, respectively; it also appears that ferric citrate was approximately 50% as effective as ferrous sulfate in meeting the iron requirement.

Animals↗
PubMed2003

Influence of urine pH and citrate concentration on the upper limit of metastability for calcium phosphate.

PURPOSE: We determined the effects on the urine upper limit of metastability for calcium phosphate of citrate concentration and pH, and achievement of the upper limit of metastability by adding calcium or phosphate. MATERIALS AND METHODS: The citrate concentration in aliquots of 24-hour urine samples from normal males without a history of kidney stones was increased. The upper limit of metastability was determined by the point of visible crystal formation, as confirmed by increased optical density at 620 nm. when calcium or pH was increased. In additional experiments the upper limit of metastability was determined by adding calcium or phosphate at pH 5.9 and 6.4. RESULTS: Regardless of how the upper limit of metastability was achieved increasing the citrate concentration increased the former value by about 0.4 units per mM. citrate per l. The upper limit of metastability achieved in a given urine sample by adding phosphate or calcium did not differ. Increasing urine pH increased the upper limit of metastability. CONCLUSIONS: Treatment with alkaline citrate salts may decrease stone formation via an increase in calcium phosphate upper limit of metastability by increasing urine citrate and by directly affecting increased pH.

Calcium↗