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PubMed2001

Utility of an initial D-dimer assay in screening for traumatic or spontaneous intracranial hemorrhage.

OBJECTIVE: To evaluate the sensitivity of a D-dimer assay as a screening tool for possible traumatic or spontaneous intracranial hemorrhage. If adequately sensitive, the D-dimer assay may potentially permit omission of a more expensive computed tomography (CT) scan of the head when such hemorrhage is clinically suspected. METHODS: Prospective, consecutive, blinded study of patients (age > 16 years) requiring a CT scan of the head for suspected intracranial hemorrhage over a five-month period at a university, Level I trauma center. All study patients had a serum D-dimer assay obtained prior to their CT scans. Sensitivity and specificity, with 95% confidence intervals (95% CIs), of the enzyme-linked immunosorbent assay (ELISA) D-dimer assay for the detection of intracranial hemorrhage were calculated. RESULTS: Of the 319 patients entered in the study, 25 (7.8%) had a CT scan positive for intracranial hemorrhage. Patients with intracranial hemorrhage were more likely to have a positive D-dimer assay (chi-square = 13.075, p < 0.001). The D-dimer assay had 21 true-positive and four false-negative tests, resulting in a sensitivity of 84.0% (95% CI = 63.7% to 95.5%) and a specificity of 55.8% (95% CI = 55.5% to 55.9%). The four false-negative cases included one small intraparenchymal hemorrhage, one small subarachnoid hemorrhage, one moderate-sized intraparenchymal hemorrhage with mid-line shift, and one large subdural hematoma requiring emergent surgery. CONCLUSIONS: Due to the catastrophic nature of missing an intracranial hemorrhage in the emergency department, the D-dimer assay is not adequately sensitive or predictive to use as a screening tool to allow routine omission of head CT scanning.

Adolescent↗
PubMed2001

Role of the peripheral intravenous catheter in false-positive D-dimer testing.

OBJECTIVE: To determine whether inserting a peripheral intravenous catheter (IV) can significantly increase the circulating D-dimer concentration. METHODS: Twenty healthy young adult volunteers underwent cannulation of an antecubital vein with a 20-gauge Teflon IV. Time 0 venous blood was drawn during IV insertion. The IV was salinelocked and left in place for 90 minutes, at which time a second venipuncture was performed in a contralateral antecubital vein (+90 min). A qualitative D-dimer assay [erythrocyte-agglutination assay, SimpliRED (SRDD)] and a quantitative spectrophotometric assay [enzyme-linked immunosorbent assay (EIA), Dimertest Gold] were performed on all samples. Time 0 means (+/-SD) were compared with +90 min means by paired t-test, and SRDD pairs were compared with McNemar's test. RESULTS: Time 0 initial venipuncture blood samples yielded a mean D-dimer concentration of 15 +/- 24 ng/mL, with 2/20 SRDD tests read as positive (95% CI = 1% to 32%). At +90 min, the D-dimer concentration was 33 +/- 21 ng/mL (p = 0.04 vs time 0), with 5/20 SRDD tests read as positive (95% CI = 9% to 49%, p = 0.248). CONCLUSIONS: Insertion of an IV increased the circulating D-dimer concentration (determined by EIA), but did not lead to a significant increase in false-positive conversion of the SRDD. An effort should be made to perform D-dimer testing on "first-stick" blood to optimize specificity. However, a strongly positive D-dimer reaction cannot be ascribed to the presence of an IV.

Adult↗
PubMed2000

Validation of an immunoturbidimetric D-dimer assay in canine citrated plasma.

D-dimer is a neoantigen formed when thrombin initiates the transformation of fibrinogen to fibrin; it is derived from plasmin digestion of cross-linked fibrin. In human medicine, the usefulness of this analyte in diagnosing disseminated intravascular coagulation (DIC) has been assessed in patients fulfilling the clinical and laboratory requirements for this disorder. In canine medicine, the use of D-dimer is relatively new. Detailed studies are needed to understand the relationship between D-dimer concentration in plasma and DIC status in dogs. We validated a D-dimer immunoturbidimetric assay (Tina-quant [a] D-Dimer, Boehringer Mannheim) in canine citrated plasma samples. Intra-assay and interassay variability (coefficient of variation) was 5.63% and 8.82%, respectively. The assay was linear, using 2 samples with low and high D-dimer concentrations (r=.996 and.998). Accuracy was 102.2% and 95.7% based on a recovery study in which 2 samples were assessed. Reference values for D-dimer were established using 70 healthy dogs that were assessed clinically and evaluated on the basis of a complete laboratory workup. The reference range was set between 0.02 and 0.28 microgram/mL (chi-square test for normal distribution, P>.05).

Journal Article↗
PubMed2005

Evaluation of latex agglutination kits for detection of fibrin(ogen) degradation products and D-dimer in healthy horses and horses with severe colic.

BACKGROUND: Fibrin(ogen) degradation products (FDPs) and D-dimer are sensitive indicators of excessive fibrinolysis due to disseminated intravascular coagulation (DIC) in dogs. To the authors' knowledge, latex-agglutination-based plasma FDP and D-dimer assays have not been validated for use in horses. OBJECTIVES: To determine: 1) sensitivity and specificity of latex agglutination serum and plasma FDP and D-dimer assays for diagnosis of DIC; and 2) their prognostic value in horses with severe colic. METHODS: At hospital admission and 24 hours later, blood was collected from 30 healthy horses and 20 horses with severe colic. Horses fulfilling predefined laboratory criteria of DIC were enrolled, and their data were subcategorized by survival for analysis. Platelet counts were determined and coagulation panel testing was performed. Serum and plasma FDP concentrations were measured using separate latex agglutination kits. Plasma D-dimer concentration was measured using 3 latex agglutination kits and a card immunofiltration test. Test sensitivity and specificity results were determined for healthy horses and those with colic. Median test values were compared between colic survivors and nonsurvivors to evaluate the prognostic usefulness of all tests. RESULTS: Performance characteristics varied among assays and kit suppliers. The FDP assays had low sensitivity (<40%), whereas the most accurate D-dimer kit had 50% sensitivity and 97% specificity. High D-dimer concentration was the third most common hemostatic abnormality in horses with colic. Median antithrombin (AT) activity was significantly lower and activated partial thromboplastin time (aPTT) was significantly longer in nonsurvivors than survivors. CONCLUSIONS: Commercial latex-agglutination D-dimer assays might prove useful as adjunctive tests for the diagnosis of DIC in horses with severe colic; however FDP assays are invalid for this purpose. Low AT activity and prolonged aPTT at admission are associated with a poor prognosis in this patient population.

Animals↗
PubMed1997

Mutations in the kissing-loop hairpin of human immunodeficiency virus type 1 reduce viral infectivity as well as genomic RNA packaging and dimerization.

A stem-loop termed the kissing-loop hairpin is one of the most highly conserved structures within the leader of human immunodeficiency virus type 1 (HIV-1) and chimpanzee immunodeficiency virus genomic RNA. Because it plays a key role in the in vitro dimerization of short HIV-1 RNA transcripts (M. Laughrea and L. Jette, Biochemistry 35:1589-1598, 1996, and references therein; M. Laughrea and L. Jette, Biochemistry 35:9366-9374, 1996, and references therein) and because dimeric RNAs may be preferably encapsidated into the HIV-1 virus, alterations of the kissing-loop hairpin might affect the in vivo dimerization and encapsidation processes. Accordingly, substitution and deletion mutations were introduced into the kissing-loop hairpin of an infectious HIV-1 molecular clone in order to produce viruses by transfection methods. The infectivity of the resulting viruses was decreased by at least 99%, the amount of genomic RNA packaged per virus was decreased by 50 to 75%, and the proportion of dimeric genomic RNA was reduced from >80 to 40 to 50%, but the dissociation temperature of the genomic RNA was unchanged. There is evidence suggesting that the deletion mutations moderately inhibited CAp24 production but had no significant effect on RNA splicing. These results are consistent with the kissing-loop model of HIV-1 RNA dimerization. In fact, because intracellular viral RNAs are probably more concentrated in transfected cells than in cells infected by one virus and because the dimerization and encapsidation processes are concentration dependent, it is likely that much larger dimerization and encapsidation defects would have been manifested within cells infected by no more than one virus.

Animals↗
PubMed1997

Mutant human immunodeficiency virus type 1 genomes with defects in RNA dimerization or encapsidation.

Retrovirus particles each contain two copies of the viral genome in the form of a noncovalently linked RNA dimer. Earlier studies have mapped a cis-acting region near the 5' end of the human immunodeficiency virus type 1 (HIV-1) genome, termed the psi locus, which appears essential for initiation of genomic dimerization, as well as for interactions with the HIV-1 Gag protein that are thought to target the RNA into nascent virions. This HIV-1 psi locus is proposed to be organized in four independent RNA stem-loops; at least three (SL1, SL3, and SL4) contain binding sites for Gag, and one of these (SL1) is implicated in dimer initiation through a kissing-loop mechanism. In this study, we have created HIV-1 proviruses containing psi mutations that affect in vitro Gag binding, RNA dimerization, or both, and we have characterized the effects of these mutations on viral assembly and infectivity by using a single-step infectious assay. We find that various mutations which eliminate the Gag binding sites in SL1 or SL3 produce marked defects in genomic RNA packaging and viral infectivity. In each case, the reduced genomic content of the mutant virions is associated with an increased content of spliced viral transcripts, suggesting that both SL1 and SL3 contribute to the discrimination between spliced and unspliced RNAs. The structures, but not the specific sequences, of the SL1 and SL3 stems appear critical for RNA packaging. Disruption of the stem or deletion of SL1 also results in abnormal genomic dimerization, as assessed by nondenaturing gel electrophoresis of virion-derived RNA. Virions carrying less extensive mutations in the SL1 loop that are known to prevent in vitro dimerization have impaired infectivity despite normal virion RNA content. This suggests that RNA dimerization is not a prerequisite for genomic packaging but instead serves an independent function in the retroviral infectious cycle.

Base Sequence↗
PubMed1992

Identification of a novel dimer stabilization region in a plant bZIP transcription activator.

We have carried out deletion analyses of a tobacco transcription activator, TGA1a, in order to define its functional domains. TGA1a belongs to the basic-region-leucine zipper (bZIP) class of DNA-binding proteins. Like other proteins of this class, it binds to its target DNA as a dimer, and its bZIP domain is necessary and sufficient for specific DNA binding. A mutant polypeptide containing the bZIP domain alone, however, shows a lower DNA-binding affinity than the full-length TGA1a. The C-terminal portion of TGA1a, which is essential for the higher DNA-binding affinity, contains a polypeptide region that can stabilize dimeric forms of the protein. This polypeptide region is designated the dimer stabilization (DS) region. Under our in vitro conditions, TGA1a derivatives with the DS region and those without the region do not form a detectable mixed dimer. This result indicates that in addition to the leucine zipper, the DS region can serve as another determinant of the dimerization specificity of TGA1a. In fact, the DS region, when fused to another bZIP protein, C/EBP, can inhibit dimer formation between the fusion protein and native C/EBP, whereas each of these can form homodimers. Such a portable determinant of dimerization specificity has potential application in studies of DNA-binding proteins as well as in biotechnology.

Base Sequence↗
PubMed1995

A dominant negative inhibitor indicates that monocyte chemoattractant protein 1 functions as a dimer.

Monocyte chemoattractant protein 1 (MCP-1) is a member of the chemokine family of proinflammatory cytokines, all of which share a high degree of amino acid sequence similarity. Aberrant expression of chemokines occurs in a variety of diseases that have an inflammatory component, such as atherosclerosis. Although structural analyses indicate that chemokines form homodimers, there is controversy about whether dimerization is necessary for activity. To address this question for MCP-1, we obtained evidence in four steps. First, coprecipitation experiments demonstrated that MCP-1 forms dimers at physiological concentrations. Second, chemically cross-linked MCP-1 dimers attract monocytes in vitro with a 50% effective concentration of 400 pM, identical to the activity of non-cross-linked MCP-1. Third, an N-terminal deletion variant of MCP-1 (called 7ND) that inhibits MCP-1-mediated monocyte chemotaxis specifically forms heterodimers with wild-type MCP-1. Finally, although 7ND inhibits wild-type MCP-1 activity, it has no effect on cross-linked MCP-1. These results indicate that 7ND is a dominant negative inhibitor, implying that MCP-1 activates its receptor as a dimer. In addition, chemical cross-linking restores activity to an inactive N-terminal insertional variant of MCP-1, further supporting the need for dimerization. Since the reported Kd for MCP-1 monomer dissociation is much higher than its 50% effective concentration or Kd for receptor binding, active dimer formation may require high local concentrations of MCP-1. Our data further suggest that the dimer interface can be a target for MCP-1 inhibitory drugs.

Base Sequence↗
PubMed1997

Prognostic significance of plasma D-dimer levels in patients with lung cancer.

BACKGROUND: The peripheral blood concentrations of several proteases of the clotting system have been shown to predict survival in patients with malignancy. A study was undertaken to investigate the independent value of the plasma levels of the D-dimer degradation product of fibrin before treatment for predicting prognosis in patients with lung cancer. METHODS: The study comprised 70 patients with lung cancer (49 non-small cell lung cancer and 21 small cell lung cancer). Plasma levels of D-dimer were measured using an enzyme immunoassay kit. Multivariate statistical analysis was carried out using the Cox's proportional hazards model. RESULTS: The median value of the plasma level of D-dimer differentiated two groups of patients with different outcomes: a group with a D-dimer level of < 150 ng/ml (low DD group) and those with D-dimer levels of > or = 150 ng/ml (high DD group). Survival time was significantly better in patients in the low DD group than in those in the high DD group in all patients (hazard ratio for high DD group = 4.7; 95% confidence interval (CI) 1.8 to 11.7). The plasma levels of D-dimer predicted survival independently from the clinical stage of disease, histological type, performance status, and tumour size (hazard ratio = 3.9; 95% CI 1.6 to 9.2). CONCLUSIONS: These results suggest that plasma levels of D-dimer might be useful for predicting the clinical outcome in patients with lung cancer. However, further prospective studies are needed in a larger population to confirm these findings.

Adult↗
PubMed2004

Evolution of plasma D-dimer and fibrinogen in witnessed onset of paroxysmal atrial fibrillation.

BACKGROUND: Although increased D-dimer and fibrinogen have been proved to be related with atrial fibrillation (AF), their evolution in the course of time remains unclear. METHODS: To elucidate the evolution of plasma D-dimer and fibrinogen in AF of different duration. 56 patients (group A) of 3,524 patients in whom the onset of AF had been witnessed in a chest pain clinic were enrolled for study. Plasma D-dimer and fibrinogen concentrations were checked within 30 min after the onset of AF and followed up as scheduled. Another 50 patients (group B) with chronic AF underwent the same protocol and served as controls. RESULTS: In group A, the D-dimer levels reached a plateau at the 18th hour (382 +/- 52 vs. 840 +/- 280 ng/ml, p < 0.001 by ANOVA) and the fibrinogen level increased gradually from 4.1 +/- 0.6 g/ml at baseline to 6.1 +/- 0.9 g/ml at the 48th hour (p < 0.001). No subjects had evidence of intra-cardiac thrombi by transesophageal echocardiography. There were significant differences in plasma D-dimer and fibrinogen levels between the two groups at each measurement. At the cut- off value of 500 ng/ml, plasma D-dimer had a sensitivity of 100%, a specificity of 93% in defining AF lasting for less than 12 h. The positive and negative predictive values were 52% and 100%, respectively. Plasma D-dimer increased above the normal range prior to the 12th hour after the onset of AF. CONCLUSION: The observations support its use as a screening tool for identifying patients with short duration AF capable of being safely converted.

Acute Disease↗
PubMed1991

Comparison of the appropriateness of the latex and Elisa plasma D-dimer determination for the diagnosis of deep venous thrombosis.

Thirty-two patients suspected of deep venous thrombosis (DVT) of the leg were evaluated after simple plasma tests (latex D-dimer and Elisa D-dimer) against echography and phlebography as the gold standard of DVT. Seven patients showed negative results in the latter test. The classification conformity between the D-dimer methods amounted 84.4%. With regard to the diagnostic classification a high specificity of 100% was found for the latex D-dimer test at the cut-off level of 450 ng/ml, whereas for sensitivity, 96% was reached. The Elisa D-dimer test was striking by its high sensitivity of 100%, but its low specificity of 28.5%. In summary, these results demonstrate that when there is a suspicion of DVT according to the clinical symptoms, a negative latex test may reject the diagnosis, whereas the latex test is less useful to establish the diagnosis. On the contrary, the Elisa D-dimer test has a too high false-positive rate. The latex D-dimer test seems to be a reliable tool to exclude the diagnosis after which an ascending contrast venography can be omitted.

Adult↗
PubMed2003

Predictive value of D-dimer test for recurrent venous thromboembolism after anticoagulation withdrawal in subjects with a previous idiopathic event and in carriers of congenital thrombophilia.

BACKGROUND: We have shown that normal D-dimer levels obtained after the discontinuation of oral anticoagulant treatment (OAT) has a high negative predictive value for recurrent venous thromboembolism (VTE). The aim of the present study was to assess the predictive value of D-dimer for recurrent VTE in subjects with a previous unprovoked event who are either carriers of inherited thrombophilia or not. METHODS AND RESULTS: We prospectively evaluated 599 patients (301 males) with a previous VTE episode. They were repeatedly examined for D-dimer levels after OAT withdrawal and were screened for inherited thrombophilic alterations. Alterations were detected in 130 patients (21.7%), factor V Leiden (70 patients; 2 of whom were homozygotes) and prothrombin mutation (38 patients) were the most prevalent ones. Recurrent events were recorded in 58 subjects (9.7%) during a follow-up of 870.7 patient-years. Altered D-dimer levels at 1 month after OAT withdrawal were associated with a higher rate of subsequent recurrence in all subjects investigated, especially in those with an unprovoked qualifying VTE event (hazard ratio, 2.43; 95% confidence interval, 1.18 to 4.61) and in those with thrombophilia (hazard ratio, 8.34; 95% confidence interval, 2.72 to 17.43). The higher relative risk for recurrence of altered D-dimer was confirmed by multivariate analysis after adjustment for other risk factors. The negative predictive value of D-dimer was 92.9% and 95.8% in subjects with an unprovoked qualifying event or with thrombophilia, respectively. CONCLUSIONS: D-dimer levels measured 1 month after OAT withdrawal have a high negative predictive value for recurrence in subjects with unprovoked VTE who are either carriers or not carriers of congenital thrombophilia.

Administration, Oral↗
PubMed1994

Plasma concentration of cross-linked fibrin degradation product (D-dimer) and the risk of future myocardial infarction among apparently healthy men.

BACKGROUND: Plasma levels of D-dimer, the primary degradation product of cross-linked fibrin, are elevated in several acute thrombotic disorders. However, whether elevated D-dimer levels among healthy individuals are associated with future coronary thrombosis is unknown. METHODS AND RESULTS: To evaluate whether levels of D-dimer are associated with the occurrence of future myocardial infarction (MI) among apparently healthy men, levels were measured in plasma samples collected at baseline from 296 participants in the Physicians' Health Study who later developed a first MI and from an equal number of age- and smoking status-matched control subjects who remained free of vascular disease during a mean follow-up period of 60.2 months. In univariate analyses, baseline plasma concentrations of D-dimer in the upper ranges of normal were associated with elevated risks of MI. Specifically, the relative risk of future MI for individuals with baseline D-dimer concentration exceeding the 95th percentile of the control distribution was two times higher than that of individuals with lower levels (relative risk [RR], 2.02; 95% confidence interval [CI], 1.04 to 4.02; P = .04). This association persisted in multivariate analyses controlling for nonlipid cardiovascular risk factors (RR, 2.12; 95% CI, 1.05 to 4.28; P = .04) and for lipoprotein(a) (RR, 2.02; 95% CI, 1.04 to 3.94; P = .03). In contrast, this association was attenuated and no longer statistically significant in analyses that controlled for total and high-density lipoprotein cholesterol (RR, 1.74; 95% CI, 0.78 to 3.91; P = .2) or for endogenous tissue-type plasminogen activator and its primary inhibitor, plasminogen activator inhibitor type 1 (RR, 1.58; 95% CI, 0.67 to 3.77; P = .3). CONCLUSIONS: Elevated levels of D-dimer are associated with increased risks of future MI, although they do not appear to be an independent predictor when other risk factors are considered. As the presence of D-dimer in plasma reflects ongoing fibrin degradation, these data support the hypothesis that activation of the endogenous fibrinolytic system occurs many years in advance of coronary arterial occlusion.

Adult↗
PubMed1995

A novel and rapid whole-blood assay for D-dimer in patients with clinically suspected deep vein thrombosis.

BACKGROUND: The clinical utility of using a novel whole blood assay for D-dimer (SimpliRED), alone or in combination with impedance plethysmography (IPG), was investigated in a two-center, prospective cohort study of 214 consecutive patients with clinically suspected deep vein thrombosis (DVT). METHODS AND RESULTS: All patients underwent the SimpliRED D-dimer assay, contrast venography, and IPG. According to the results of venography, 43 patients had proximal DVT (popliteal and/or more proximal veins), 10 had isolated calf DVT, and 161 had DVT ruled out. The D-dimer had a sensitivity of 93% for proximal DVT and of 70% for calf DVT, an overall specificity of 77%, and a negative predictive value of 98% for proximal DVT. The sensitivity and specificity of IPG for proximal DVT were 67% and 96%, respectively. When analyzed in combination with the IPG results, it was determined that (1) the combination of a negative D-dimer and a normal IPG had a negative predictive value of 97% for all DVT and of 99% for proximal DVT and occurred in 58% of patients (likelihood ratio, 0.1) and (2) the combination of a positive D-dimer and an abnormal IPG had a positive predictive value of 93% for any DVT and of 90% for proximal DVT and occurred in 14% of patients (likelihood ratio, 42.6). When the D-dimer and IPG results were discordant, it was not possible to exclude or diagnose DVT reliably; discordant results occurred in 28% of patients. CONCLUSIONS: The SimpliRED D-dimer assay, which can be performed and interpreted at the bedside within 5 minutes, has great potential in patients with clinically suspected DVT, especially for ruling out DVT, and is complementary to IPG. The assay should be evaluated in large clinical management studies.

Agglutination Tests↗
PubMed2001

Plasma fibrin D-dimer levels and risk of stable coronary artery disease: results of a large case-control study.

Increased levels of fibrin D-dimer are indicative of a hypercoagulable state, as found in acute coronary syndromes. Few well-controlled studies have assessed D-dimers in patients with stable coronary artery disease (CAD). We measured levels of D-dimers (in ng/mL by enzyme-linked immunosorbent assay) in 312 patients with angiographically proved CAD and stable angina pectoris and in 477 age- and sex-matched healthy blood donors. Demographic characteristics were assessed by a standardized questionnaire, and a complete lipid profile was performed for all subjects. In addition, a variety of other markers of hemostasis and inflammation were measured. The distribution of D-dimer levels was skewed to the right, and plasma median levels were higher in cases than in controls (median: 11.2 vs 2.8 ng/mL; P<0.001). In controls, correlations of D-dimer were found with fibrinogen, plasma viscosity, and interleukin-6. In logistic regression analysis, the age- and sex-adjusted odds ratio (OR) for the presence of CAD was 2.6 (95% confidence interval [CI], 1.9 to 3.5) when the highest quartile of the D-dimer distribution was compared with the combined lower 3 quartiles. The OR did not change appreciably after controlling for nonlipid risk factors (OR, 2.7; 95% CI, 1.9 to 3.9) and remained significant after further adjustment for other hemostatic parameters (OR, 2.4; 95% CI, 1.7 to 3.3) and markers of inflammation (OR, 2.1; 95% CI, 1.5 to 2.9). Plasma D-dimer levels are strongly and independently associated with the presence of CAD in patients with stable angina pectoris. These results support the concept of a contribution of intravascular fibrin to atherothrombogenesis.

Adult↗
PubMed1993

High affinity and specificity of dimeric binding of thyroid hormone receptors to DNA and their ligand-dependent dissociation.

The thyroid hormone receptors are ligand-dependent, DNA binding, trans-acting transcriptional factors belonging to the erbA-related steroid/thyroid hormone receptor superfamily. We report here the high affinity and specificity of dimeric DNA binding of human thyroid hormone receptor-alpha 1 (hTR alpha 1) and hTR beta 1 and the effect of T3 on its DNA binding. Gel mobility shift assay showed that hTR alpha 1 and -beta 1 bind to the rat GH-thyroid hormone response element (TRE) and rat malic enzyme (rME)-TRE as a monomer, dimer, and oligomer in the absence of T3 and bind to an irrelevant DNA sequence from the adenovirus 5 promoter only as a monomer. In competition studies using unlabeled TRE, dimer binding was displaced by lower concentrations of TRE than was the monomer, indicating that the dimeric binding has higher affinity than the monomer binding. These results suggest that the formation of dimers of TR increases the specificity and affinity for the response element. Surprisingly, T3 disrupted dimer binding and increased the intensity of monomer binding to rME-TRE in a dose-dependent manner. This does not occur with the rat GH-TRE. We also demonstrate that this disruption of dimeric binding by T3 occurred on a TRE formed by a direct repeat and not on a palindromic TRE. Furthermore, a mutant hTR beta (Mf), which has no detectable ligand-binding activity because of a glycine to arginine substitution at amino acid 340 in the hormone-binding domain, does not show dissociation from rME-TRE after the addition of T3.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenoviruses, Human↗
PubMed2004

Analytic validation and clinical evaluation of the STA LIATEST immunoturbidimetric D-dimer assay for the diagnosis of disseminated intravascular coagulation.

To evaluate the diagnostic performance of a quantitative, immunoturbidimetric D-dimer assay and compare it with other components of the proposed International Society on Thrombosis and Haemostasis disseminated intravascular coagulation (DIC) diagnostic algorithm, we retrospectively analyzed the D-dimer, platelet count, prothrombin time, and fibrinogen results for all eligible hospitalized patients (n = 241) who had a D-dimer assay ordered during a 12-month period. A receiver operating characteristic (ROC) curve constructed from the maximum D-dimer measurement for all patients was significant (P < .001) with an area under the curve (AUC) of 0.94. The ROC curves of the other tests were each significant (P < .001), but the AUCs of the prothrombin time (0.74), fibrinogen level (0.70), and platelet count (0.67) did not approach that of the D-dimer. A D-dimer cutoff of 8.2 microg/mL (8,200 microg/L) optimized sensitivity and negative predictive value for the total population and patients with a predisposing condition. Validation against 286 additional patients in a separate analysis verified the diagnostic performance of the aforementioned cutoff. A sensitive, immunoturbidimetric D-dimer assay, by itself provides excellent sensitivity and negative predictive value for the diagnosis of DIC.

Adult↗
PubMed1993

Elevated D dimer in the lungs and blood of patients with sarcoidosis.

The hypothesis of this study was that D dimer, a specific degradation product of cross-linked fibrin, would be increased in the bronchoalveolar lavage (BAL) fluids of patients with sarcoidosis and that it would be related to other BAL parameters of disease activity. Eight of 10 sarcoidosis patients but none of 18 healthy volunteers had detectable BAL D dimer by enzyme immunoassay. Autoradiography revealed the presence of fibrinogen and D dimer in the BAL fluids from sarcoidosis patients. Bronchoalveolar lavage D dimer levels in sarcoidosis patients correlated with total BAL cells per milliliter, lymphocytes per milliliter, and total protein level, but not macrophages per milliliter. The D dimer in the BAL fluids from sarcoidosis patients did not correlate with D dimer in the blood. Our findings indicate that BAL D dimer parallels directly the lymphocytic alveolitis that characterizes pulmonary sarcoidosis.

Adult↗