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PubMedDate not supplied

Immunological monitoring of patients with melanoma after peptide vaccination using soluble peptide/HLA-A2 dimer complexes.

To facilitate the immunologic monitoring of a peptide vaccine trial, a novel, empty dimeric HLA-A2 molecule (A2 dimer) that could be loaded with peptides was produced. The dimer comprises the extracellular domain of HLA-A2 noncovalently linked to a fusion protein consisting of human beta2-microglobulin joined to the human IgG1 Fc domain. Peptide-loaded dimer complexes were used to assess the function of peptide-specific T cells. HLA-A2 gp100 peptide dimers stimulated interferon (IFN)-gamma production by the gp100-specific TIL-1520 cell line. Gp100/A2 dimer stimulation in combination with intracellular cytokine staining was used to analyze peptide-specific T-cell responses in patients with melanoma after vaccination with the modified gp100: 209-2M peptide in adjuvant. Titration analysis of the amount of peptide-loaded dimer required to stimulate gp100-specific T cells was used to estimate the functional avidity of effector/memory CD8+ T lymphocytes. The number of peptide-specific T cells detected in the peripheral blood of vaccinated patients using this assay was comparable to the number determined by staining with fluoresceinated gp100: 209-2M HLA-A2 tetramers. IFN-gamma production by T cells was comparable after stimulation with peptide-pulsed dimers, T2 cells, or autologous dendritic cells. Peptide-loaded A2 dimers could also be used directly to stimulate T cells in the ELISPOT assay.

Animals↗
PubMed2004

pH effects on the stability and dimerization of procaspase-3.

pH-dependent conformational changes are known to occur in dimeric procaspase-3, and they have been shown to affect the rate of automaturation. We studied the equilibrium unfolding of procaspase-3(C163S) as a function of pH (between pH 8.5 and pH 4) in order to examine these changes in the context of folding and stability. The data show that the procaspase dimer undergoes a pH-dependent dissociation below pH 5, so that the protein is mostly monomeric at pH 4. Consistent with this, the dimer unfolds via a four-state process between pH 8.5 and pH 4.75, in which the native dimer isomerizes to a dimeric intermediate, and the dimeric intermediate dissociates to a monomer, which then unfolds. In contrast, a small protein concentration dependence was observed by circular dichroism, but not by fluorescence emission, at pH 4.5 and pH 4.2. There was no protein-concentration dependence to the data collected at pH 4. Overall, the results are consistent with the redistribution of the population of native dimer (N(2)) to dimeric intermediate (I(2)) to monomeric intermediate (I), as the pH is lowered so that at pH 4, the "native" ensemble resembles the monomeric intermediate (I) observed during unfolding at higher pH. An emerging picture of the monomeric procaspase is discussed. Procaspase-3 is most stable at pH approximately 7 (24-26 kcal/mol), and while the stability decreased with pH, it was observed that dimerization contributes the majority (>70%) of the conformational free energy.

Caspase 3↗
PubMed2000

Dimer formation by a "monomeric" protein.

Dimeric proteins can arise by the swapping of structural domains between monomers. The prevalence of this occurrence is unknown. Ribonuclease A (RNase A) is assumed to be a monomer near physiological conditions. Here, this hypothesis is tested and found to be imprecise. The two histidine residues (His12 and His119) in the active site of RNase A arise from two domains (S-peptide and S-protein) of the protein. The H12A and H119A variants have 10(5)-fold less ribonucleolytic activity than does the wild-type enzyme. Incubating a 1:1 mixture of the H12A and H119A variants at pH 6.5 and 65 degrees C results in a 10(3)-fold increase in ribonucleolytic activity. A large quantity of active dimer can be produced by lyophilizing a 1:1 mixture of the H12A and H119A variants from acetic acid. At pH 6.5 and 65 degrees C, the ribonucleolytic activity of this dimer converges to that of the dimer formed by simply incubating the monomers, as expected for a monomer-dimer equilibrium. The equilibrium dissociation constant for the dimer is near 2 mM at both 65 and 37 degrees C. This value of Kd is only 20-fold greater than the concentration of RNase A in the cow pancreas, suggesting that RNase A dimers exist in vivo. The intrinsic ability of RNase A to form dimers under physiological conditions is consistent with a detailed model for the evolution of homodimeric proteins. Dimers of "monomeric" proteins could be more prevalent than is usually appreciated.

Amino Acid Substitution↗
PubMed2004

Effect of dimer dissociation on activity and thermostability of the alpha-glucuronidase from Geobacillus stearothermophilus: dissecting the different oligomeric forms of family 67 glycoside hydrolases.

The oligomeric organization of enzymes plays an important role in many biological processes, such as allosteric regulation, conformational stability and thermal stability. alpha-Glucuronidases are family 67 glycosidases that cleave the alpha-1,2-glycosidic bond between 4-O-methyl-D-glucuronic acid and xylose units as part of an array of hemicellulose-hydrolyzing enzymes. Currently, two crystal structures of alpha-glucuronidases are available, those from Geobacillus stearothermophilus (AguA) and from Cellvibrio japonicus (GlcA67A). Both enzymes are homodimeric, but surprisingly their dimeric organization is different, raising questions regarding the significance of dimerization for the enzymes' activity and stability. Structural comparison of the two enzymes suggests several elements that are responsible for the different dimerization organization. Phylogenetic analysis shows that the alpha-glucuronidases AguA and GlcA67A can be classified into two distinct subfamilies of bacterial alpha-glucuronidases, where the dimer-forming residues of each enzyme are conserved only within its own subfamily. It seems that the different dimeric forms of AguA and GlcA67A represent the two alternative dimeric organizations of these subfamilies. To study the biological significance of the dimerization in alpha-glucuronidases, we have constructed a monomeric form of AguA by mutating three of its interface residues (W328E, R329T, and R665N). The activity of the monomer was significantly lower than the activity of the wild-type dimeric AguA, and the optimal temperature for activity of the monomer was around 35 degrees C, compared to 65 degrees C of the wild-type enzyme. Nevertheless, the melting temperature of the monomeric protein, 72.9 degrees C, was almost identical to that of the wild-type, 73.4 degrees C. It appears that the dimerization of AguA is essential for efficient catalysis and that the dissociation into monomers results in subtle conformational changes in the structure which indirectly influence the active site region and reduce the activity. Structural and mechanistic explanations for these effects are discussed.

Amino Acid Sequence↗
PubMed2005

Mutations that abrogate human immunodeficiency virus type 1 reverse transcriptase dimerization affect maturation of the reverse transcriptase heterodimer.

The specific impact of mutations that abrogate human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) dimerization on virus replication is not known, as mutations shown previously to inhibit RT dimerization also impact Gag-Pol stability, resulting in pleiotropic effects on HIV-1 replication. We have previously characterized mutations at codon 401 in the HIV-1 RT tryptophan repeat motif that abrogate RT dimerization in vitro, leading to a loss in polymerase activity. The introduction of the RT dimerization-inhibiting mutations W401L and W401A into HIV-1 resulted in the formation of noninfectious viruses with reduced levels of both virion-associated and intracellular RT activity compared to the wild-type virus and the W401F mutant, which does not inhibit RT dimerization in vitro. Steady-state levels of the p66 and p51 RT subunits in viral lysates of the W401L and W401A mutants were reduced, but no significant decrease in Gag-Pol was observed compared to the wild type. In contrast, there was a decrease in processing of p66 to p51 in cell lysates for the dimerization-defective mutants compared to the wild type. The treatment of transfected cells with indinavir suggested that the HIV-1 protease contributed to the degradation of virion-associated RT subunits. These data demonstrate that mutations near the RT dimer interface that abrogate RT dimerization in vitro result in the production of replication-impaired viruses without detectable effects on Gag-Pol stability or virion incorporation. The inhibition of RT activity is most likely due to a defect in RT maturation, suggesting that RT dimerization represents a valid drug target for chemotherapeutic intervention.

Codon↗
PubMed1998

Requirement of PKR dimerization mediated by specific hydrophobic residues for its activation by double-stranded RNA and its antigrowth effects in yeast.

The roles of protein dimerization and double-stranded RNA (dsRNA) binding in the biochemical and cellular activities of PKR, the dsRNA-dependent protein kinase, were investigated. We have previously shown that both properties of the protein are mediated by the same domain. Here we show that dimerization is mediated by hydrophobic residues present on one side of an amphipathic alpha-helical structure within this domain. Appropriate substitution mutations of residues on that side produced mutants with increased or decreased dimerization activities. Using these mutants, we demonstrated that dimerization is not essential for dsRNA binding. However, enhancing dimerization artificially, by providing an extraneous dimerization domain, increased dsRNA binding of both wild-type and mutant proteins. In vitro, the dimerization-defective mutants could not be activated by dsRNA but were activated normally by heparin. In Saccharomyces cerevisiae, unlike wild-type PKR, these mutants could not inhibit cell growth and the dsRNA-binding domain of the dimerization-defective mutants could not prevent the antigrowth effect of wild-type PKR. These results demonstrate the biological importance of the dimerization properties of PKR.

Animals↗
PubMed2002

Embolus location affects the sensitivity of a rapid quantitative D-dimer assay in the diagnosis of pulmonary embolism.

D-dimer blood tests have been suggested to rule out pulmonary embolism. Despite evidence of the safety of withholding anticoagulant treatment in patients with suspected pulmonary embolism and a normal D-dimer assay result, clinicians remain reluctant to use a D-dimer assay as a sole diagnostic test. This prospective study in 314 consecutive inpatients and outpatients investigates the relation between the diagnostic accuracy of D-dimer plasma concentration and pulmonary embolus location. Plasma D-dimer levels were measured using a quantitative immunoturbidimetric method. A strict protocol of ventilation-perfusion scintigraphy, pulmonary angiography, and spiral computed tomography was used to arrive at a final diagnosis and to assess the largest pulmonary artery in which embolus was visible. The influence of embolus location on the diagnostic accuracy was evaluated using the Kruskal-Wallis test and receiver operator characteristics (ROC) analysis. There was a strong correlation between plasma D-dimer concentration and embolus location (Kruskal-Wallis, p < 0.001). Thus, the assay showed greater accuracy in excluding segmental or larger emboli (sensitivity = 93%) than subsegmental emboli (sensitivity = 50%). D-dimer concentration and the accuracy of D-dimer assays are clearly dependent on embolus location and smaller, subsegmental emboli may be missed when D-dimer assays are used as a sole test to exclude pulmonary embolism.

Dimerization↗
PubMed2004

Molecular dynamics simulation of amyloid beta dimer formation.

Recent experiments with amyloid beta (Abeta) peptide indicate that formation of toxic oligomers may be an important contribution to the onset of Alzheimer's disease. The toxicity of Abeta oligomers depends on their structure, which is governed by assembly dynamics. Due to limitations of current experimental techniques, a detailed knowledge of oligomer structure at the atomic level is missing. We introduce a molecular dynamics approach to study Abeta dimer formation. 1), We use discrete molecular dynamics simulations of a coarse-grained model to identify a variety of dimer conformations; and 2), we employ all-atom molecular mechanics simulations to estimate thermodynamic stability of all dimer conformations. Our simulations of a coarse-grained Abeta peptide model predicts 10 different planar beta-strand dimer conformations. We then estimate the free energies of all dimer conformations in all-atom molecular mechanics simulations with explicit water. We compare the free energies of Abeta(1-42) and Abeta(1-40) dimers. We find that 1), dimer conformations have higher free energies compared to their corresponding monomeric states; and 2), the free-energy difference between the Abeta(1-42) and the corresponding Abeta(1-40) dimer conformation is not significant. Our results suggest that Abeta oligomerization is not accompanied by the formation of thermodynamically stable planar beta-strand dimers.

Amyloid beta-Peptides↗
PubMed2005

Free energy landscapes for amyloidogenic tetrapeptides dimerization.

The oligomerization of four peptide sequences, KFFE, KVVE, KLLE, and KAAE is studied using replica-exchange molecular dynamics simulations with an atomically detailed peptide model. Previous experimental studies reported that of these four peptides, only those containing phenylalanine and valine residues form fibrils. We show that the fibrillogenic propensities of these peptides can be rationalized in terms of the equilibrium thermodynamics of their early oligomers. Thermodynamic stability of dimers, as measured by the temperature of monomer association, is seen to be higher for those peptides that are able to form fibrils. Although the relative high and low stabilities of the KFFE and KAAE dimers arise from their respective high and low interpeptide interaction energies, the higher stability of the KVVE dimer over the KLLE system results from the smaller loss of configurational entropy accompanying the dimerization of KVVE. Free energy landscapes for dimerization are found to be strongly sequence-dependent, with a high free energy barrier separating the monomeric and dimeric states for KVVE, KLLE, and KAAE sequences. In contrast, the most fibrillogenic peptide, KFFE, displayed downhill assembly, indicating enhanced kinetic accessibility of its dimeric states. The dimeric phase for all peptide sequences is found to be heterogeneous, containing both antiparallel beta-sheet structures that can grow into full fibrils as well as disordered dimers acting as on- or off-pathway intermediates for fibrillation.

Algorithms↗
PubMed2006

Dynamics and stability of E-cadherin dimers.

The extracellular domains of cadherins are known to play a major role in cell adhesion, although the structures involved in this process remain unclear. We have used molecular dynamics to characterize the conformational and thermodynamic properties of two of the dimer interfaces identified in E-cadherin crystals and involving the two outermost exodomains (EC1 and EC2): a dimer involving exchange of the N-terminal strand (referred to as the "swapped" dimer) and a "staggered" dimer involving an EC1-EC2 interface. The results show that the staggered dimer involves a much smaller interface area and is notably less stable than the swapped dimer. It is also found that, despite its stability, the swapped dimer undergoes a conformational transition leading to a structure closer to that experimentally observed for the homologous C-cadherin. Finally, comparing the simulated dimer structures with the sequences of E-, C-, and N-cadherins shows that the swapped dimer interface involves surprisingly few residues that vary from family to family and notably no changes between the E- and C-cadherin exodomains.

Animals↗
PubMed1998

Cross-linked growth hormone dimers have enhanced biological activity.

In this study we have investigated the effect on the bioactivity of pituitary-derived human growth hormone (hGH) and recombinant bovine (b) GH after the addition of various concentrations of the water soluble cross-linking agent 1-ethyl-3(3-dimethylaminopropyl) carbodiimide (EDC; 6.25-100 mg/ml). The biological activity of resulting cross-linked reactions were determined by its ability to promote incorporation of 35SO4(2-) into costal cartilage of hypopituitary Snell dwarf mice in vivo. Administration of EDC-treated hGH solutions resulted in a significant enhancement of hormone activity in vivo compared with non-cross-linked samples. A similar significant enhancement of bGH activity in vivo was also observed when solutions containing recombinant bGH were cross-linked using EDC. For both hGH and bGH the degree of enhancement appears to be dose-dependent for the concentration of EDC (6.25-100 mg/ml for hGH; 6.25-50 mg/ml for bGH) present in the cross-linking reactions. SDS-PAGE analysis of EDC cross-linked solutions containing hGH and bGH spiked with 125I-hGH and 125I-bGH respectively revealed that dimeric GH was the primary cross-linked component. Increasing the concentration of EDC in cross-linking reactions resulted in increased formation of dimeric hGH and bGH. There was a significant correlation between the amount of GH dimer present and the increase in biological activity, suggesting that GH dimers were responsible for the enhanced biological activity. This was confirmed by the enhanced biological activity of a purified preparation of EDC cross-linked dimeric hGH. In conclusion, covalently cross-linked GH dimers reported here have enhanced bioactivity in vivo. However, since naturally occurring GH dimers are known to have reduced biological activity, this work suggests that the structure of EDC cross-linked GH dimers differs fundamentally from that of native dimeric hGH.

Animals↗
PubMedDate not supplied

Two glycoprotein populations of band 3 dimers are present in human erythrocytes.

The human erythrocyte Band 3 anion exchanger contains a single site of N-glycosylation that contains either a short complex oligosaccharide or an extended polylactosaminyl oligosaccharide. Approximately equal amounts of the different glycosylated forms of Band 3 are found in human red cells. As Band 3 exists predominantly as dimers, they may be uniform and consist of a subunit containing an extended oligosaccharide paired with a subunit containing a short oligosaccharide chain. Alternatively, Band 3 dimers may be comprised of subunits that either contain polylactosaminyl or short oligosaccharide chains. To distinguish between these two extremes, the ability of Band 3 membrane domain dimers to bind to immobilized tomato lectin, which specifically binds polylactosaminyl oligosaccharide, was tested. The dimeric membrane domain of Band 3 could be resolved into two fractions by tomato lectin chromatography. This shows that Band 3 dimers are not homogeneous and that two pools exist in red cells, some with a long polylactosaminyl oligosaccharide and the other with a short complex type. The amount of short chain form recovered in the unbound fraction was higher than expected for a random distribution of oligosaccharide chains on Band 3 dimers. Detergent extraction experiments showed that Band 3 glycoforms did not display a differential interaction with the cytoskeleton. The ability to separate Band 3 dimers into two glycoform populations suggests that subunit exchange between dimers does not occur in the membrane or in detergent solution. Furthermore, the results show that while one population of Band 3 dimers is processed to contain polylactosaminyl oligosaccharide, the other largely escapes this processing step.

Anion Exchange Protein 1, Erythrocyte↗
PubMed2005

Preferential recognition of undisruptable dimers of inducible nitric oxide synthase by a monoclonal antibody directed against an N-terminal epitope.

Overproduction of NO by inducible NO synthase (iNOS) has been implicated in the pathogenesis of many diseases. iNOS is active only as a homodimer in which the subunits align in a head-to-head manner, with the N-terminal oxygenase domains forming the dimer interface and a zinc metal center stabilizing the dimer. Thus, dimerization represents a critical locus for therapeutic interventions for regulation of NO synthesis. We have recently shown that intracellular iNOS forms dimers that are "undisruptable (UD)" by heat, SDS, strong denaturants, and/or reducing agents. Our data further suggest that the zinc metal center plays a role in forming and/or stabilizing iNOS undisruptable dimers (UD-dimers). In this study, we show that a mAb directed against a unique epitope at the oxygenase domain of human iNOS preferentially recognizes UD-dimers. This observation has implications for the mechanism of formation and regulation of dimer formation of iNOS. Our data suggest that UD-dimers of iNOS, in spite of SDS-PAGE denaturation, still maintain features of the quaternary structure of iNOS particularly at its N-terminal end and including head-to-head contact of the oxygenase domains.

Animals↗
PubMedDate not supplied

[Characteristic of the two-step RNA dimerization in avian sarcoma and leukosis viruses].

Dimerization of two copies of genomic RNA is a necessary step of retroviral replication. In the case of human immunodeficiency virus type 1 (HIV-1) the process is explored in many details. It is proved that conserved stem-loop structure is an essential element in RNA dimerization. Similar model of two-step dimerization mechanism can be considered for avian sarcoma and leukosis virus group (ASLV) in spite of the absence of homology between dimer initiation site (DIS) of ASLV and that of HIV-1. In this paper, short RNA fragments of two viruses: avian sarcoma virus CT-10 and avian leukosis virus HPRS-103 have been chosen in order to investigate the structural requirements of dimerization process and compare them to that of HIV-1. The rate of spontaneous transition from loose to tight dimer was studied as a function of stem length and temperature. Although both types of dimers were observed for both avian retroviruses chosen, fragments of CT-10 requires much higher RNA concentration to form loose dimer. In spite of identical sequence of the loops (5'-A-CUGCAG-3') avian sarcoma virus CT-10 RNA fragments dimerization was greatly impaired. The differences can be explained by deletion of adenine 271 in avian sarcoma virus CT-10 in the stem and by resulting shortening of the self-complementary loop.

Animals↗
PubMed1990

Effects of microinjected photoreactivating enzyme on thymine dimer removal and DNA repair synthesis in normal human and xeroderma pigmentosum fibroblasts.

UV-induced thymine dimers (10 J/m2 of UV-C) were assayed in normal human and xeroderma pigmentosum (XP) fibroblasts with a monoclonal antibody against these dimers and quantitative fluorescence microscopy. In repair-proficient cells dimer-specific immunofluorescence gradually decreased with time, reaching about 25% of the initial fluorescence after 27 h. Rapid disappearance of dimers was observed in cells which had been microinjected with yeast photoreactivating enzyme prior to UV irradiation. This photoreactivation (PHR) was light dependent and (virtually) complete within 15 min of PHR illumination. In general, PHR of dimers strongly reduces UV-induced unscheduled DNA synthesis (UDS). However, when PHR was applied immediately after UV irradiation, UDS remained unchanged initially; the decrease set in only after 30 min. When PHR was performed 2 h after UV exposure, UDS dropped without delay. An explanation for this difference is preferential removal of some type(s) of nondimer lesions, e.g., (6-4) photoproducts, which is responsible for the PHR-resistant UDS immediately following UV irradiation. After the rapid removal of these photoproducts, the bulk of UDS is due to dimer repair. From the rapid effect of dimer removal by PHR on UDS it can be deduced that the excision of dimers up to the repair synthesis step takes considerably less than 30 min. Also in XP fibroblasts of various complementation groups the effect of PHR was investigated. The immunochemical dimer assay showed rapid PHR-dependent removal comparable to that in normal cells. However, the decrease of (residual) UDS due to PHR was absent (in XP-D) or much delayed (in XP-A and -E) compared to normal cells. This supports the idea that in these XP cells preferential repair of nondimer lesions does occur, but at a much lower rate.

Cells, Cultured↗
PubMed2006

Value of D-dimer testing for the exclusion of pulmonary embolism in patients with previous venous thromboembolism.

BACKGROUND: D-dimer levels remain elevated in many patients after completion of a 6-month anticoagulant drug course for a first episode of venous thromboembolism (VTE), which may limit the clinical usefulness of D-dimer testing for ruling out a possible recurrence. METHODS: We assessed the safety and usefulness of D-dimer testing in patients with suspected pulmonary embolism (PE) who had experienced a previous VTE. We analyzed data from 2 outcome studies that enrolled 1721 consecutive emergency department patients with clinically suspected PE. Information on the existence of a previous episode of VTE was abstracted from the database. All the patients underwent a sequential diagnostic workup, including an enzyme-linked immunosorbent assay D-dimer test and a 3-month follow-up. RESULTS: The proportion of confirmed PE was 24.1% (415/1719); PE was ruled out by a negative D-dimer test result in 32.7% (462/1411) of the patients without previous VTE but in only 15.9% (49/308) of the patients with previous VTE (P<.001). The 3-month thromboembolic risk was 0% (95% confidence interval, 0.0%-7.9%) in patients with previous VTE and a negative D-dimer test result. The 2-fold lower chance of a negative D-dimer test result in patients with previous VTE was independent of older age, active malignancy, fever, and recent surgery. CONCLUSIONS: In patients with suspected PE and previous VTE, a negative D-dimer test result seems to allow safely ruling out a recurrent event. However, the proportion of negative results is lower in such patients, definitely reducing the clinical usefulness of the D-dimer test in that subgroup.

Adult↗
PubMed2005

Metallophilicity versus pi-pi interactions: ligand-unsupported argentophilicity/cuprophilicity in oligomers-of-dimers [M2L2]n (M=CuI or AgI, L=tridentate ligand).

To verify whether attractive metallophilic interactions exist in the dimer-of-dimers [Cu(2)(ophen)(2)](2) (Hophen=1H-[1,10]phenanthrolin-2-one) (1), we designed and synthesized a series of such [M(2)L(2)](2) structures by varying the d(10) metal and/or the ligand (M=Cu(I) or Ag(I), L=ophen or obpy; Hobpy=1H-[2,2']bipyridinyl-6-one), and have successfully obtained three dimers-of-dimers: [Ag(2)(ophen)(2)](2).6 H(2)O (2), [Cu(2)(obpy)(2)](2) (3), and [Ag(2)(obpy)(2)](2).4.5 H(2)O.0.5 DMF (4). X-ray analyses of these structures show that interdimer M-M separations in [Ag(2)-(ophen)(2)](2) (3.199 A) are remarkably shorter than those in [Cu(2)(ophen)(2)](2) (3.595 A). Shorter interdimer M-M separations are found in the structures of [M(2)(obpy)(2)](2) (2.986 and 2.993 A in [Cu(2)(obpy)(2)](2), 3.037 to 3.093 A in [Ag(2)(obpy)(2)](2)), in which the pi systems are smaller than in the complexes with the ophen ligand. Detailed structural comparison of these dimers-of-dimers indicates that the interdimer, face-to-face pi-pi interactions repulse rather than support the interdimer metal-metal attractive interactions. This study also yields qualitative comparison of the strengths between argentophilic, cuprophilic, and face-to-face pi-pi interactions. DFT calculations on the four dimers-of-dimers further support the above deduction. The structure of a trimer-of-dimers [Ag(2)(obpy)(2)](3) (Ag-Ag 3.171 to 3.274 A) is further evidence that the oligomerization of the [M(2)L(2)] molecules is favored by stronger metallophilic and weaker face-to-face pi-pi interactions.

Journal Article↗
PubMed2003

D-dimer and its relationship to fibrinogen/fibrin degradation products (FDPs) in disorders associated with activation of coagulation or fibrinolytic systems.

Levels of D-dimer and fibrinogen/fibrin degradation products (FDPs) are significantly elevated in patients with deep venous thrombosis, pulmonary embolism, disseminated intravascular coagulation, or other complications. The diagnosis of these disorders can be difficult, time-consuming, and expensive. Assays for the detection of FDPs and D-dimer are used in many laboratories to investigate these disorders. The aim of this study was to compare plasma D-dimer levels obtained by the immuno-turdimetric method (Liatest D-Dimer Diagnostica Stago, Asnières, France) with plasma FDPs were measured by latex agglutination to investigate the relationship between these parameters. These immunoassays were tested in 144 blood samples from patients with suspected disorders associated with activation of coagulation or fibrinolytic systems. D-dimer and FDPs assays were performed in plasma samples by the use of Liatest D-dimer and plasma FDPs (Diagnostica Stago), respectively. Patients were divided into four groups according to plasma D-dimer levels. In group 1, 47.4% had negative FDPs and 52.6% had positive FDPs. In group 2, 15.4% had negative FDPs and 84.6% had positive FDPs. In group 3, 10.3% had negative FDPs and 89.7% had positive FDPs. All of the patients in group 4 had positive FDPs. It was shown that plasma D-dimer levels measured by Liatest D-dimer have a relation to FDP levels measured by latex agglutination.

Biomarkers↗