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D A Triplett

Publications and source records attributed to D A Triplett.

At least 73 records · Page 4Linked to original sources
PubMed1992

Coagulation assays for the lupus anticoagulant: review and critique of current methodology.

Several coagulation assays identify lupus anticoagulants, but there is no uniform opinion regarding minimum criteria for the diagnosis or the most sensitive procedure to be used to screen for lupus anticoagulants. Based on test availability and the cumulative literature, a sensitive activated partial thromboplastin time appears to be the most appropriate screening test. The dilute Russell's viper venom time may be used as both a screening and a confirmatory procedure. The platelet neutralization procedure is the most sensitive and specific of the confirmatory procedures that use an increased amount of phospholipid to either "bypass" or "neutralize" the lupus anticoagulant.

Anticoagulants↗
PubMed1991

Superwarfarin ingestion and detection.

Because of the emergence of warfarin resistance, new potent long-acting anticoagulants are now readily available in several over-the-counter rodenticide products. The availability of these "superwarfarin" compounds has led to accidental and purposeful human ingestions, one of which has resulted in a death. We summarize the prior case reports and report a second death. In addition, we report the availability of an assay to detect the presence of brodifacoum (a superwarfarin compound) in human plasma and tissues.

4-Hydroxycoumarins↗
PubMed1991

Laboratory diagnosis of von Willebrand's disease.

The laboratory diagnosis of von Willebrand's disease (vWD) has become much more difficult because of the identification of numerous variant forms of vWD. The biologic and pathologic variability in individual patients necessitates a comprehensive assessment. Patients with classic type I vWD may be easily identified by using the bleeding time, activated partial thromboplastin time, platelet count, von Willebrand antigen, and ristocetin cofactor tests. In patients with variant forms of vWD, however, multimeric analysis of both platelet and plasma von Willebrand factor may be necessary. Furthermore, more than one assessment may be needed to detect an abnormal result in many of the aforementioned tests.

Bleeding Time↗
PubMed1991

Evaluation of different mixing study reagents and dilution effect in lupus anticoagulant testing.

Until recently, the laboratory identification of lupus anticoagulants (LA) was not considered important. Often LA were regarded as a nuisance, resulting in factor assays and other coagulation tests with inconclusive results. However, the recognition of important clinical complications associated with the presence of LA has resulted in an emphasis on the detection of this phospholipid-dependent inhibitor. Most studies have evaluated the sensitivity of various screening or confirmatory procedures used in establishing the diagnosis of LA. The authors have focused on the variables involved in the mixing studies used to identify the presence of a circulating inhibitor. To detect the latter, attention to the ratio of patient plasma to normal plasma is important, particularly in the case of a minimally prolonged APTT. Also the source of "normal" plasma must be platelet poor to maximize sensitivity in the case of a weak LA.

Blood Coagulation Factors↗
PubMed1991

Serologic characterization of Rocky Mountain spotted fever. Appearance of antibodies reactive with endothelial cells and phospholipids, and factors that alter protein C activation and prostacyclin secretion.

Rocky Mountain spotted fever (RMSF) takes its name from the characteristic rash that occurs as a consequence of vasculitis associated with rickettsial invasion of the endothelium. The authors examined sera from 14 patients with serologically confirmed RMSF for the presence of antibodies (IgG and IgM) reactive with human umbilical vein-derived endothelial cells and with the phospholipids cardiolipin (CL) and phosphatidyl serine (PS). Sera from 7 patients (50%) exhibited antiendothelial antibodies, and 10 (71%) patient sera reacted with CL and/or PS. Because such antibodies may interfere with or augment endothelial thrombosis-related activities, acute and convalescent sera were tested for their effects on endothelial PGI2 secretion and protein C activation. Acute sera from two patients and convalescent sera from four patients stimulated protein C activation. Additionally, sera from five acute and nine convalescent cases inhibited basal endothelial PGI2 secretion, but sera from two acute and three convalescent cases stimulated thrombin-dependent PGI2 secretion. These results demonstrated that, in a significant proportion of patients, RMSF was accompanied by the appearance of antibodies that bound to endothelial cells and to phospholipids; some of these antibodies may have altered anticoagulant endothelial functions.

Adolescent↗
PubMed1991

Effect of lupus anticoagulants on the activated partial thromboplastin time. Results of the College of American Pathologists survey program.

Lupus anticoagulants are antibodies that interfere with in vitro phospholipid-dependent coagulation reactions. In vivo, they have been associated with a variety of thromboembolic problems. Samples from patients with lupus anticoagulants were included in the 1986 and 1987 College of American Pathologists proficiency survey program. Participant performance on these samples demonstrated significant variation in the responsiveness of different activated partial thromboplastin reagents to lupus anticoagulants. The level of factor VIII in these samples reported by the participants also varied with the reagent used. Follow-up studies demonstrated striking reagent-dependent differences in the dilutional effect on apparent factor VIII, IX, XI, and XII activity. These results point out the importance of selecting sensitive and responsive reagents for appropriate identification of lupus inhibitors. In addition, the results indicate that the choice of reagent used for factor assays can affect the apparent factor activity as well as whether a dilutional effect is noted when a lupus anticoagulant is present in the test sample, an important consideration when trying to distinguish a lupus anticoagulant from a specific factor inhibitor.

Autoantibodies↗
PubMed1990

Comparison of test methods for the lupus anticoagulant: international survey on lupus anticoagulants-I (ISLA-1).

Six lyophilized plasma samples were sent to 20 "expert" laboratories for assessment of lupus anticoagulant (LA). Four samples contained pooled LA of graded potency mixed with aged normal plasma. One contained LA plus cephalin phospholipid and one contained a nonspecific venom anticoagulant. Sixteen methods were used overall with some participants using up to 8 methods. Results were scored in regard to the known potencies of LA in the samples and other known induced defects. Activated partial thromboplastin time (APTT) tests used by most participants for preliminary screening were relatively sensitive, but non-specific. Platelet or phospholipid neutralization procedures (PNP) appeared to be sensitive and specific but showed a non-linear response to increased LA content. Kaolin clotting time (KCT) tests showed the most sensitive response to increased LA content but the weaker LA were not scored as abnormal by most laboratories as the samples may have contained platelet fragments. Other commonly used tests such as the tissue thromboplastin inhibition (TTI) test and the dilute Russell's viper venom test (DRVVT) were carried out somewhat inconsistently. The variability in performance of tests in different laboratories indicates that standardization of methodology is urgently required. Generally it seemed that most clotting tests were "bypassed" by the addition of phospholipid to a known LA-positive sample in apparently direct proportion to their sensitivity. Sample preparation, especially prevention of contamination with activated platelets is a vital preliminary part in the assay of LA.

Autoantibodies↗
PubMed1990

Heat treatment of serum and plasma induces false positive results in the antiphospholipid antibody ELISA.

We found that levels of antiphospholipid antibodies (aPLA), measured with an ELISA increase if serum or plasma samples are heated. The phenomenon is dependent on duration and degree of heating, optimum levels being reached at 3 h at 56 degrees C. Negative samples become positive after heating. The heating effect is more pronounced for IgG-aPLA than for IgM-aPLA and is not observed for adsDNA, atetanus or lymphocytotoxic antibodies. The presence of serum/plasma components in addition to IgG is essential for the phenomenon to occur. Ultracentrifugation and mixing experiments with isolated IgG did not enable us to explain our observations. Nevertheless, knowledge of this phenomenon is of practical importance.

Abortion, Habitual↗
PubMed1990

Evaluation of APTT reagent sensitivity to factor IX and factor IX assay performance. Results from the College of American Pathologists Survey Program.

Hereditary factor IX deficiency (hemophilia B) is among the more common hereditary bleeding disorders and factor IX assays are among the more common specific factor assays performed by coagulation laboratories. To assess the sensitivity of various reagents used for performance of activated partial thromboplastin times and factor IX assays, a series of samples with varying levels of factor IX were included in the 1988 College of American Pathologists Survey Program. We found significant differences in the sensitivity of reagents to factor IX deficiency. Surprisingly, the least sensitive reagents were among the most commonly used reagents. Significant differences in the classification of activated partial thromboplastin times as abnormal were noted between H1 and H2 survey participants. As with factor VIII assays, significant differences in the dose-response curves for factor IX deficiency were noted between reagents, with more responsive reagents giving more precise results for factor IX assays. Comparison of factor IX assay performance in 1988 with 1980 performance indicates a substantial improvement in assay precision. However, a further improvement in assay performance could be expected if current recommendations were followed.

Blood Coagulation Tests↗
PubMed1989

Antiphospholipid antibodies and recurrent pregnancy loss.

Antiphospholipid antibodies (APA) have recently been linked to a variety of clinical findings including arterial and venous thrombosis, recurrent spontaneous abortions and fetal loss, as well as thrombocytopenia. These observations have stimulated multidisciplinary interest in the laboratory identification of APA and the clinical management of patients with positive tests for APA.

Abortion, Habitual↗
PubMed1989

The effect of phospholipid on the detection of lupus anticoagulants by the dilute Russell viper venom time.

The dilute Russell viper venom time (dRVVT) has been recently introduced as a sensitive test for the detection of lupus anticoagulants. We evaluated the effect of method and source of phospholipid on performance of the dRVVT. Our results indicate that the source of phospholipid has a significant effect on the sensitivity of this assay to lupus anticoagulants. The dRVVT will need to undergo further evaluation and characterization before it is adopted as a standard assay for detection of lupus anticoagulants.

Animals↗
PubMed1988

Evaluation of lupus anticoagulants: antiphospholipid antibodies, endothelium associated immunoglobulin, endothelial prostacyclin secretion, and antigenic protein S levels.

Plasma samples from nineteen patients with well characterized lupus anticoagulants (LA) were evaluated using a series of test systems. An ELISA was used to determine if the plasmas contained antiphospholipid antibodies (APA); fifteen of nineteen LA plasmas contained APA, with five exhibiting IgG only, two exhibiting IgM, and eight plasmas containing both IgG and IgM. Anti-phosphatidyl serine (PS) was the predominant IgG specificity and all IgM APA-containing plasmas reacted with phosphatidyl inositol (PI). An ELISA was developed to determine if LA plasmas contained immunoglobulin which would associate with cultured human umbilical cord vein-derived endothelial cells (HUV); ten of nineteen plasmas contained endothelium associated immunoglobulin (EAI). There was significant concordance between the occurrence of EAI and IgM anti-PI. The occurrence of EAI or APA, either singly or in combination, did not correlate with a past history of thrombosis. Patient plasmas were incubated with HUV and examined for effects on HUV prostacyclin (PGI2) secretion; six plasmas significantly stimulated PGI2 secretion and one plasma was inhibitory. Finally, plasma levels of free and total antigenic protein S were determined by EID. Five plasmas contained significantly reduced levels of free antigenic protein S, and total antigenic protein S was reduced in ten plasmas. Patient histories were examined for evidence of thrombotic episodes; six patients had a history of either arterial or venous thrombosis, with five of these six patients having drug-induced LA. Thus, unlike previous studies, drug-induced LA were associated with thrombosis.

Adolescent↗
PubMed1988

Factor VIII assays. Assessment of variables.

Factor VIII assays are the most common specific coagulation factor assay performed in the United States. Interlaboratory proficiency studies have documented persistent problems with variation in results between laboratories. The Coagulation Resource Committee of the College of American Pathologists conducted a workshop to analyze variables that may affect performance of the one-stage factor assay. The results indicate that accuracy of the assay can be improved by uniform standardization of reference plasma samples and that reproducibility can be enhanced through appropriate choice of reagents and instruments. Optimizing performance of this assay should lead to more reproducible interlaboratory results.

Evaluation Studies as Topic↗