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At least 109 records · Page 6Linked to original sources
PubMed1996

Ranitidine bismuth citrate: a novel anti-ulcer agent with different physico-chemical characteristics and improved biological activity to a bismuth citrate-ranitidine admixture.

BACKGROUND: Ranitidine bismuth citrate (RBC) is a new chemical entity for the treatment of peptic ulcer disease. RESULTS: RBC is freely soluble in water (more than 600 mg/mL at pH 4.6), whereas an equimolar admixture of its component molecules, bismuth citrate and ranitidine, formed an almost totally insoluble suspension. Even at very low pH values (around 2.0), the solubility of bismuth in ranitidine bismuth citrate was at least two-fold better than in the admixture. Comparison of several physico-chemical characteristics indicated that RBC possessed significantly different melting point properties, X-ray powder diffraction patterns, infra-red spectra and 13C-NMR solid-state spectra to the admixture. Ranitidine bismuth citrate inhibited human pepsin isoenzymes 1, 2, 3 and 5 but the admixture was inactive. RBC showed approximately two-fold greater anti-Helicobacter pylori activity in vitro than the admixture (geometric mean minimum inhibitory concentrations of 12.5 and 25.7 mg/L, respectively) and was more rapidly bactericidal. In a mouse model of gastric H. pylori colonization, 200 mg/kg of bismuth, given as RBC, eradicated the organism from all mice while only 10% of infections were eradicated by equivalent levels of bismuth in admixture form. CONCLUSION: It is believed that the significantly greater solubility of RBC, especially at lower pH values, is highly relevant to its better antipepsin and anti-H. pylori action compared to the insoluble admixture of bismuth citrate and ranitidine.

Animals↗
PubMed1982

Purification of L-glutamate-dependent citrate lyase from Clostridium sphenoides and electron microscopic analysis of citrate lyase isolated from Rhodopseudomonas gelatinosa, Streptococcus diacetilactis and C. sphenoides.

Citrate lyase from Clostridium sphenoides was purified 72-fold with a yield of 11%. In contrast to citrate lyase from other sources the activity of this enzyme was strictly dependent on the presence of L-glutamate. The purified enzyme was only stable in the presence of 150 mM L-glutamate or 7 mM L-glutamate plus glycerol, sucrose or bovine serum albumin. Changes of the L-glutamate pool and of enzyme activity in growing cells of C. sphenoides indicated that citrate lyase activity in this organism was regulated by the intracellular L-glutamate concentration. Citrate lyase isolated from C. sphenoides, Rhodopseudomonas gelatinosa and Streptococcus diacetilactis was investigated by electron microscopy using the negative staining technique. Three different projections of enzyme molecules were observed: 'star' form, 'ring' form and 'triangle' form. In samples from R. gelatinosa and S. diacetilactis, star and ring forms occurred in a ratio of about 1:9. Using the enzyme from S. diacetilactis it was demonstrated that this ratio could be altered in favour of the star form by the addition of citrate or tricarballylate. The triangle form was observed in less than 1% of all evaluated molecules and may represent a transition form. In lyase samples from C. sphenoides there existed a correlation between enzyme activity and the proportion of stars and rings at varying concentrations of L-glutamate.

Bacteria↗
PubMed1982

Copurification of citrate lyase and citrate lyase ligase from Rhodopseudomonas gelatinosa and subsequent separation of the two enzymes.

A procedure has been worked out which allowed the purification and crystallization of a citrate lyase/citrate lyase ligase complex from Rhodopseudomonas gelatinosa. The complex was subsequently separated to yield two homogeneous enzymes. Citrate lyase ligase was purified 365-fold with a yield of 3.23%. The molecular weight of the enzyme was estimated to be 39500, the enzyme consisted of one polypeptide chain. The reaction rates for ATP, acetate and citrate lyase (sulfhydryl form) followed Michaelis-Menten kinetics (Km values: 0.14 mM, 5 mM and 37 nM respectively). Citrate lyase ligase exhibited a high substrate specificity and could not react with citrate lyases from nonphototrophic microorganisms. In contrast to the ligase from Streptococcus diacetilactis, the enzyme from R. gelatinosa was extremely labile; however, it could be stabilized by nucleotides, the most potent stabilizing one being ADP.

Carbon-Sulfur Ligases↗
PubMed2000

[Plasma concentrations of toremifene citrate and N-desmethyltoremifene in postmenopausal patients with breast cancer--comparison of 120 mg of toremifene citrate administered once a day and divided into 3 separate doses (t.i.d.)].

To determine whether plasma concentrations of toremifene citrate after administration of 120 mg/day of toremifene citrate given in three separate dose (t.i.d.) were similar to those when toremifene citrate was administered in a single daily doses (40 mg x 3 tablets), we examined changes in plasma concentrations of toremifene citrate (TOR) and its metabolite, N-desmethyltoremifene (TOR-1). In both the t.i.d. administration group and the single-dose administration group, plasma TOR and TOR-1 concentrations reached a constant state within 2 weeks after administration was started. Under the constant state, plasma TOR concentrations were 1,493.3 +/- 120.3 ng/ml in the t.i.d. administration group and 1,348 +/- 341.0 ng/ml in the single-dose administration group. Plasma TOR-1 concentrations were 2,378.3 +/- 186.5 ng/ml in the t.i.d. administration group and 2,144 +/- 475.3 ng/ml in the single-dose administration group. In both groups, plasma TOR-1 concentrations were 2 or more times higher than plasma TOR concentrations. These results show there were no differences in plasma concentrations between administration of 120 mg/day of toremifene citrate in divided daily doses (t.i.d.) and in a single daily dose. The two administration methods appear to produce clinically similar actions.

Aged↗
PubMed2005

New trends in the chemistry of iron(III) citrate complexes: correlations between X-ray structures and solution species probed by electrospray mass spectrometry and kinetics of iron uptake from citrate by iron chelators.

Despite the crucial role of "iron(III) citrate systems" in the iron metabolism of living organisms (bacteria as well as plants or mammals), the coordination chemistry of ferric citrate remains poorly defined. Variations in the experimental conditions used for the preparation of so-called ferric citrates (iron salt, Fe:cit molar ratio, base, pH, temperature, solvent) lead to several different species, which are in equilibrium in solution. To date, six different anionic complexes have been structurally characterized in the solid state, by ourselves or others. In the work described herein, we have established the experimental conditions leading to each of them. Five were obtained from aqueous solution. With the exception of a nonanuclear species (of which fragments have been detected), all were identified in aqueous solution on the basis of electrospray ionization mass spectrometry. In addition, the spectra revealed a new trinuclear species, which could not be crystallized. Kinetic studies of iron uptake from citrate species by iron chelators confirmed the results indicated by the ESI-MS studies. These studies also allowed the relative molar fraction of mononuclear versus polynuclear complexes to be determined, which depends on the Fe:cit molar ratio.

Chemical Phenomena↗
PubMed1992

Chimeric allosteric citrate synthases: construction and properties of citrate synthases containing domains from two different enzymes.

The citrate synthases of the gram-negative bacteria, Escherichia coli and Acinetobacter anitratum, are allosterically inhibited by NADH. The kinetic properties, however, suggest that the equilibrium between active (R) and inactive (T) conformational states is shifted toward the T state in the E. coli enzyme. We have now manipulated the cloned genes for the two bacterial enzymes to produce two chimeric proteins, in which one folding domain of each subunit is derived from each enzyme. One chimera (the large domain from A. anitratum and the small domain from the E. coli enzyme) is designated CS ACI::eco; the other is called CS ECO::aci. Both chimeras are roughly as active as the wild type parents, but their Km values for both substrates are lower than those for the E. coli enzyme, and NADH inhibition is markedly sigmoid, while that for E. coli citrate synthases is hyperbolic. Curve-fitting to the allosteric equation suggests that these differences are the result of the destabilization of the T state in the chimeras. The ACI::eco chimera exists almost entirely as a hexamer, like the A. anitratum enzyme, while the ECO::aci chimera, like the E. coli synthase, forms three major bands on nondenaturing polyacrylamide gels, two of them hexamers of different net charge, and one a dimer. These findings indicate that subunit interactions leading to hexamer formation in allosteric citrate synthases of gram-negative bacteria involve mainly the large domains. The chimeras are also used to show that the NADH binding site of E. coli citrate synthase is located entirely in the large domain. Sensitivity of the chimeras to denaturation by urea, to which the A. anitratum enzyme is much more resistant than the E. coli enzyme, is determined by the large domains. Sensitivity to inactivation by subtilisin is intermediate between those shown by the E. coli (very sensitive) and A. anitratum (quite resistant) synthases. This result suggests that digestibility by subtilisin is determined by conformational factors as well as the amino acid sequences of the target regions.

Acinetobacter↗
PubMed1990

Aspiration pneumonitis prophylaxis in obstetric anaesthesia: comparison of effervescent cimetidine-sodium citrate mixture and sodium citrate.

One hundred and forty-seven patients undergoing elective or emergency Caesarean section under general anaesthesia were allocated randomly to three groups: group 1 (n = 28) received no premedication; group 2 (n = 58) received 0.3-molar sodium citrate 15 ml (sodium citrate 1.16 g); group 3 (n = 61) received effervescent cimetidine-sodium citrate combination (cimetidine 400 mg with sodium citrate 0.9 g) after entering the operating room. Gastric pH was measured at tracheal intubation (pH1) and extubation (pH2). Mean pH1 and mean pH2 values in group 1 were, respectively, 2.25 (SD 1.35) and 2.83 (1.64). Mean pH1 and pH2 values in group 2 were, respectively, 4.38 (1.44) and 4.57 (1.51). In group 3 mean pH1 and pH2 values were, respectively, 5.07 (1.13) and 5.37 (1.30). Percentages of patients with pH1 less than or equal to 2.5 in groups 1, 2 and 3 were, respectively, 75, 13.8 and 1.6. Percentages of patients with pH2 less than or equal to 2.5 in groups 1, 2 and 3 were 50, 10.3 and 1.6, respectively.

Adult↗
PubMed1994

Transport of citrate catalyzed by the sodium-dependent citrate carrier of Klebsiella pneumoniae is obligatorily coupled to the transport of two sodium ions.

Aerobically grown Escherichia coli GM48 harboring plasmid pKScitS that codes for the sodium-dependent citrate carrier from Klebsiella pneumoniae (CitS) allows initial-rate measurements of citrate uptake in whole cells. The cation stoichiometry and selectivity of CitS was studied using this experimental system. The relationship between the initial rate of uptake of citrate and the Na+ concentration was sigmoidal at pH values between 5 and 7 suggesting a Na+ stoichiometry higher than 1. Rates of uptake increased quadratically in a range of non-saturating Na+ concentrations showing that two Na+ are translocated/catalytic cycle. Symport of Na+ is absolutely required in the range pH 5-7 because no uptake could be detected in the absence of Na+. Protons cannot replace Na+ in the translocation step but the decrease in apparent affinity for Na+ towards lower pH suggests that protons can compete with Na+ for the cation-binding sites. Li+ can replace Na+ in the symport reaction but it takes about a 200-fold higher concentration of Li+ over Na+ to achieve the same rate of uptake, showing that the affinity of CitS for Li+ is much lower than for Na+. Though high Li+ concentrations have an inhibitory effect on citrate uptake, the data suggest that the Li+ stoichiometry is also 2.

Bacterial Proteins↗
PubMed1965

CITRATE AND THE CONVERSION OF CARBOHYDATE INTO FAT. ACTIVITIES OF CITRATE-CLEAVAGE ENZYME AND ACETATE THIOKINASE IN LIVERS OF NORMAL AND DIABETIC RATS.

1. The activity of citrate-cleavage enzyme declines in alloxan-diabetes. 2. The administration of insulin elevates the activity of the enzyme in livers of normal and diabetic animals. Diets high in glucose or fructose elevate the activity of citrate-cleavage enzyme in normal animals, whereas only the diet high in fructose does so in diabetic animals. These observations parallel the effects of insulin, glucose and fructose on fatty acid synthesis in normal and diabetic animals. The effect of fructose is brought into play more rapidly and is larger than the effect of glucose. 3. With one exception acetate thiokinase shows similar changes at a lower level of activity. 4. The results indicate that insulin acts by increasing glucose utilization, and not by exerting a direct effect on citrate-cleavage enzyme or acetate thiokinase.

ATP Citrate (pro-S)-Lyase↗
PubMed2001

Citrate, a possible precursor of astaxanthin in Phaffia rhodozyma: influence of varying levels of ammonium, phosphate and citrate in a chemically defined medium.

The influence of ammonium, phosphate and citrate on astaxanthin production by the yeast Phaffia rhodozyma was investigated. The astaxanthin content in cells and the final astaxanthin concentration increased upon reduction of ammonium from 61 mM to 12.9 mM (from 140 microg/g to 230 microg/g and 1.2 microg/ml to 2.3 microg/ml, respectively). Similarly, both the astaxanthin content and astaxanthin concentration increased by reducing phosphate from 4.8 mM to 0.65 mM (160 microg/g to 215 microg/g and 1.7 microg/ml to 2.4 microg/ml, respectively). Low concentrations of ammonium or phosphate also increased the fatty acid content in cells. By analogy with lipid synthesis in other oleaginous yeasts, an examination of the data for varying nitrogen and phosphate levels suggested that citrate could be the source of carbon for fatty acids and carotenoid synthesis. Supporting this possibility was the fact that supplementation of citrate in the medium at levels of 28 mM or higher notably increased the final pigment concentration and pigment content in cells. Increased carotenoid synthesis at low ammonium or phosphate levels, and stimulation by citrate were both paralleled by decreased protein synthesis. This suggested that restriction of protein synthesis could play an important role in carotenoid synthesis by P. rhodozyma.

Citric Acid↗
PubMed2003

Structural evidence for iron-free citrate and ferric citrate binding to the TonB-dependent outer membrane transporter FecA.

Escherichia coli possesses a TonB-dependent transport system, which exploits the iron-binding capacity of citrate and its natural abundance. Here, we describe three structures of the outer membrane ferric citrate transporter FecA: unliganded and complexed with iron-free or diferric dicitrate. We show the structural mechanism for discrimination between the iron-free and ferric siderophore: the binding of diferric dicitrate, but not iron-free dicitrate alone, causes major conformational rearrangements in the transporter. The structure of FecA bound with iron-free dicitrate represents the first structure of a TonB-dependent transporter bound with an iron-free siderophore. Binding of diferric dicitrate to FecA results in changes in the orientation of the two citrate ions relative to each other and in their interactions with FecA, compared to the binding of iron-free dicitrate. The changes in ligand binding are accompanied by conformational changes in three areas of FecA: two extracellular loops, one plug domain loop and the periplasmic TonB-box motif. The positional and conformational changes in the siderophore and transporter initiate two independent events: ferric citrate transport into the periplasm and transcription induction of the fecABCDE transport genes. From these data, we propose a two-step ligand recognition event: FecA binds iron-free dicitrate in the non-productive state or first step, followed by siderophore displacement to form the transport-competent, diferric dicitrate-bound state in the second step.

Amino Acid Sequence↗
PubMed2003

Correlations of synthetic, spectroscopic, structural, and speciation studies in the biologically relevant cobalt(II)-citrate system: the tale of the first aqueous dinuclear cobalt(II)-citrate complex.

Synthetic efforts targeting soluble species of Co(II) with the low molecular mass physiological ligand citric acid led to the isolation of the first dinuclear complex [Co(2)(C(6)H(5)O(7))(2)(H(2)O)(4)](2-), at pH approximately 5, in the form of its K+ (1) and Na+ (2) salts. Both 1 and 2 were characterized analytically, spectroscopically (FT-IR, UV/visible, EPR), and magnetically. Complex 1 crystallizes in the monoclinic space group P2(1)/n, with a = 10.348(5) A, b = 11.578(6) A, c = 12.138(6) A, beta = 112.62(2) degrees, V = 1342(1) A(3), and Z = 2. Complex 2 crystallizes in the monoclinic space group P2(1)/c, with a = 9.234(4) A, b = 11.913(4) A, c = 11.728(6) A, beta = 99.93(2) degrees, V = 1271(1) A(3), and Z = 2. X-ray crystallography on 1 and 2 reveals the presence of two Co(II) ions, in a dinuclear assembly, octahedrally coordinated by two citrate ligands in a tridentate fashion. The octahedral environment around each Co(II) is complemented by another singly bonded citrate belonging to the adjacent Co(II) unit and two water molecules. Magnetic susceptibility and EPR studies on 1, in the solid state, corroborate the X-ray results, indicating a weak interaction between the two Co(II) ions. Moreover, EPR and UV/visible studies in solution suggest that 1 does not retain its dimeric structure, yielding a mononuclear octahedral Co(II)-citrate species. Detailed speciation studies suggest the presence of a number of species including the mononuclear complex [Co(C(6)H(5)O(7))](-), optimally present around pH approximately 5. In consonance with EPR and UV/visible spectroscopy, [Co(C(6)H(5)O(7))](-) is likely the scaffolding unit on the basis of which the dimer [Co(2)(C(6)H(5)O(7))(2)(H(2)O)(4)](2-) is isolated from aqueous solutions. Collectively, this comprehensive study offers significant structural insight into the Co(II)-citrate speciation and the elucidation of the role of Co(II) in biological fluids.

Journal Article↗
PubMed2002

Reactivity investigation of dinuclear vanadium(IV,V)-citrate complexes in aqueous solutions. A closer look into aqueous vanadium-citrate interconversions.

Well-known vanadium(IV)- and vanadium(V)-citrate complexes have been employed in transformations involving vanadium redox as well as nonredox processes. The employed complexes include K(2)[V(2)O(4)(C(6)H(6)O(7))(2)] x 4H(2)O, K(4)[V(2)O(4)(C(6)H(5)O(7))(2)] x 5.6H(2)O, K(2)[V(2)O(2)(O(2))(2)(C(6)H(6)O(7))(2)] x 2H(2)O, K(4)[V(2)O(2)(C(6)H(4)O(7))(2)] x 6H(2)O, K(3)[V(2)O(2)(C(6)H(4)O(7))(C(6)H(5)O(7))] x 7H(2)O, (NH(4))(4)[V(2)O(2)(C(6)H(4)O(7))(2)] x 2H(2)O, and (NH(4))(6)[V(2)O(4)(C(6)H(4)O(7))(2)] x 6H(2)O. Reactions toward hydrogen peroxide at different vanadium(IV,V):H(2)O(2) ratios were crucial in delineating the routes leading to the interconversion of the various species. Equally important thermal transformations were critical in showing the linkage between pairs of dinuclear vanadium-citrate peroxo as well as nonperoxo complexes, for which the important vanadium(V)-assisted oxidative decarboxylation, leading to reduction of vanadium(V) to vanadium(IV), seemed to be a plausible pathway in place for all the cases examined. FT-IR spectroscopy and X-ray crystallography were instrumental in the identification of the arising products of all investigated reactions. Collectively, the data support the existence of chemical links between different and various structural forms of dinuclear vanadium(IV,V)-citrate complexes in aqueous media. Furthermore, in corroboration of past studies, the examined interconversions lend credence to the notion that the involved species are active participants in the respective aqueous distributions of the metal ion in the presence of the physiological ligand citrate. The concomitant significance of structure-specific species relating to soluble and potentially bioavailable forms of vanadium is mentioned.

Journal Article↗
PubMed2003

Synthesis and spectroscopic and structural studies of a new cadmium(II)-citrate aqueous complex. Potential relevance to cadmium(II)-citrate speciation and links to cadmium toxicity.

The presence of cadmium in the environment undoubtedly contributes to an increased risk of exposure and ultimate toxic influence on humans. In an effort to comprehend the chemical and biological interactions of Cd(II) with physiological ligands, like citric acid, we explored the requisite aqueous chemistry, which afforded the first aqueous Cd(II)-citrate complex [Cd(C(6)H(6)O(7))(H(2)O)](n)() (1). Compound 1 was characterized by elemental analysis, and spectroscopically by FT-IR and (113)Cd MAS NMR. Compound 1 crystallizes in the orthorhombic space group P2(1)2(1)2(1), with a = 6.166(2) A, b = 10.508(3) A, c = 13.599(5) A, V = 881.2(5) A(3), and Z = 4. The X-ray structure of 1 reveals the presence of octahedral Cd(II) ions bound to citrate ligands in a molecular crystal lattice. Citrate acts as a tridentate binder promoting coordination to one Cd(II) through the central alcoholic moiety, one terminal carboxylate group, and the central carboxylate group. In addition, the central carboxylate binds to three Cd(II) ions. Specifically, one of the oxygens of the central carboxylate serves as a bridge to two neighboring Cd(II) ions, while the other oxygen binds to a third Cd(II). A bound water molecule completes the coordination requirements of Cd(II). (113)Cd MAS NMR studies project the spectroscopic signature of the nature of the coordination environment around Cd(II) in 1, thus corroborating the X-ray findings. Collectively, the data at hand are in line with past solution studies. The latter predict that other similar low molecular mass Cd(II)-citrate complexes may exist in the acidic pH region, thus influencing the uptake of cadmium by living (micro)organisms, their ability to metabolize organic substrates, and possibly Cd(II) toxicity.

Cadmium↗
PubMed1975

Citrate cleavage enzymes from developing soybean cotyledons: incorporation of citrate carbon into Fatty acids.

Data are presented which demonstrate a citrate cleavage enzyme in the supernatant of a developing soybean (Glycine max L. Merr., var. Harosoy 63) cotyledon homogenate following a 126,000g spin for 2 hours. Activity of the enzyme was observed directly in the supernatant enzyme preparation and in a desalted supernatant preparation by measuring the formation of acetylhydroxamate. Acetylhydroxamate production was dependent on citrate and coenzyme A. The reaction increased with time, citrate, and coenzyme A concentrations.Involvement of the enzyme in lipid synthesis was investigated by the incorporation of carbon from citrate-1,5-(14)C into fatty acids. Incorporation shows a pH optimum at 8.5, a temperature optimum at 30 C, and a dependence on ATP and coenzyme A. The reaction is linear throughout the range of extract concentrations tested and is linear as a function of time for 1 hour. Isotope was distributed primarily in unsaturated fatty acids.

Journal Article↗
PubMed2000

Transcriptional control of the citrate-inducible citMCDEFGRP operon, encoding genes involved in citrate fermentation in Leuconostoc paramesenteroides.

In this study we describe the expression pattern of the Leuconostoc paramesenteroides citMCDEFGRP operon in response to the addition of citrate to the growth medium. An 8.8-kb polycistronic transcript, which includes the citMCDEFGRP genes, was identified; its synthesis was dramatically induced upon addition of citrate to the growth medium. We also found that expression of the cit operon is subjected to posttranscriptional regulation, since processing sites included in four complex secondary structures (I, II, III, and IV) were identified by Northern blot analysis and mapped by primer extension. Upstream of the citMCDEFGRP operon a divergent open reading frame, whose expression was also increased by citrate, was identified by DNA sequencing and designated citI. The start and end sites of transcription of the cit operon and citI gene were mapped. The start sites are separated by a stretch of 188 bp with a very high A+T content of 77% and are preceded by transcriptional promoters. The end sites of the transcripts are located next to the 3' end of two secondary structures characteristic of rho-independent transcriptional terminators. The effect of the citI gene on expression of the cit operon was studied in Escherichia coli. The presence of the citI gene in cis and in trans resulted in increased activity of the cit promoter. These data provide the first evidence that citrate fermentation in Leuconostoc is regulated at the transcriptional level by a transcriptional activator rather than by a repressor.

Bacterial Proteins↗
PubMed1978

[Whole-body retention studies of 167Tm-citrate.--Estimation of radiation dose to human from 167Tm-citrate--(author's transl)].

For the purpose of calculating absorbed dose to humans from 167Tm-citrate, the whole-body retention studies using 5 rats were carried out. Up to 40 days following intravenous injection of 167Tm-citrate, the whole-body counts were monitored with a animal counter. The whole-body retention curve was obtained with three exponentaial components. Namely, the 26% of the injected 167 Tm-citrate had a biological half-time of 3.4 hours, 12.5% had a biological half-time of 99 hours and 61.5% had a biological half-time of 106 days. These results indicate, that three components consist of the rapid clearance from the kidneys, the retention in the liver and other soft tissues with relatively long half-time and the retention in the bones with long half-time. Based on these biological data and the MIRD Committee method, the average dose estimates to the bone and whole-body from intravenous administration of 1 mCi 167Tm-citrate were 7.08 rads and 1.28 rads, respectively.

Animals↗
PubMed2004

Comparison of samples obtained from 3.2% sodium citrate glass and two 3.2% sodium citrate plastic blood collection tubes used in coagulation testing.

We sought to compare coagulation test results obtained from patients using 2 plastic blood collection tubes and the traditional glass blood collection tube. Blood specimens were obtained from 241 patients in 3.2% buffered sodium citrate using standard glass tubes, in 3.2% buffered sodium citrate in plastic tubes, and in 3.2% sodium citrate "sandwich" tubes (plastic within plastic). All samples were obtained and processed contemporaneously and tested for prothrombin time (PT) and activated partial thromboplastin time (aPTT). Residual plasma was frozen at -70 degrees C for future testing, including fibrinogen, antithrombin, plasminogen, protein C and protein S (functional and antigenic), dilute Russell viper venom time (DRVVT), ristocetin cofactor, factor XIII, D dimer, anti-Xa activity, and prothrombin fragment. Although paired t test analysis revealed statistically significant differences (P < .05) between glass and plastic for PT, aPTT, fibrinogen, protein C (functional and antigenic), functional protein S, DRVVT and confirmation method, antithrombin, and factor XIII, these differences were not considered clinically significant.

Blood Coagulation Tests↗