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Biomedical subjects

D A Triplett

Publications and source records attributed to D A Triplett.

At least 109 records · Page 6Linked to original sources
PubMed1983

Inherited factor X deficiency: presentation of a case with etiologic and treatment considerations.

The first documented case of inherited factor X deficiency in the dental literature is presented. Its ascertainment as a result of postoperative surgical complications illustrates the clinician's need to be familiar with the hereditary bleeding diatheses, as treatment is dependent on the underlying etiology of the specific disorder. In the present case treatment included administration of the antifibrinolytic agent epsilon-aminocaproic acid (EACA) and fresh frozen plasma. On the basis of our findings, a minimal therapeutic level of circulating factor X is estimated to be 15 percent of the normal level. Genetic heterogeneity within the factor X deficiency phenotype is discussed and, on the basis of laboratory findings, a CRM-positive autosomal recessive structural or regulator gene defect is proposed as the etiologic factor in the current case. Forty-nine cases in the literature are reviewed to delineate the pattern of bleeding in hereditary factor X deficiency.

Child↗
PubMed1983

Laboratory diagnosis of lupus inhibitors: a comparison of the tissue thromboplastin inhibition procedure with a new platelet neutralization procedure.

The introduction of the activated partial thromboplastin time (APTT) as a screening test has resulted in increased recognition of circulating anticoagulants. The most frequently encountered inhibitor is the lupus-type anticoagulant. However, criteria for differentiation of this inhibitor are not well-established. We evaluated the ability of two procedures, tissue thromboplastin inhibition (TTI) and a new platelet neutralization procedure (PNP), to differentiate between various types of coagulation inhibitors. The TTI, widely used for the diagnosis of lupus anticoagulants, proved to be nonspecific. The PNP specifically separated lupus-type inhibitors from Factor VIII, X, and V inhibitors. The PNP may be a useful test for the diagnosis of lupus anticoagulants.

Blood Coagulation↗
PubMed1983

Selecting instrumentation and reagents for the coagulation laboratory.

The selection of appropriate instrumentation and reagents for the coagulation laboratory is a difficult task for pathologists who do not devote a significant portion of their time to hemostatic problems. In this article, the authors outline a systematic approach to evaluating instruments and reagents. Using this approach, an informed individualized decision can be made.

Decision Making↗
PubMed1983

Factor assay (VIII and IX) results in the College of American Pathologists Survey Program (1980-1982).

It has become apparent that mild factor deficiency states (i.e., Factor VIII, IX, and von Willebrand's syndrome) are frequent causes of postoperative bleeding and hemorrhagic complications following trauma. Despite their incidence, they frequently are not diagnosed or in some instances are misdiagnosed. In an attempt to improve the level of performance of factor assays, the College of American Pathologists recently has introduced factor-deficient plasmas into their proficiency testing program. Initially, plasmas deficient in Factor VIII were evaluated and more recently, plasmas deficient in Factors IX and XI were included. The results of the initial survey programs indicated a lack of precision and accuracy of Factor VIII and IX assays. Similar difficulties also were encountered with plasmas deficient in Factor XI. Extensive information also was gathered on the fundamentals of laboratory performance of factor assays. This information included data regarding preparation of the standard activity curves, source of deficient substrate plasmas, number of patient sample dilutions, etc. Also, it was evident that various thromboplastins have different degrees of sensitivity to the various deficiency states. A portion of this variability may be attributable to the choice of activator, however, it would appear that the phospholipid content of the partial thromboplastins is of equal importance.

Adult↗
PubMed1982

Factor XI assay results in the CAP survey (1981).

Data from the 1981 CAP Survey for factor XI assay is reviewed. Different instrument reagent combinations are ranked according to precision and sensitivity. Results of the survey questionnaire are analyzed. There is poor correlation between precision and sensitivity of most systems (i.e., instrument and reagent combinations). For any given system, precision appears to decrease with increasing severity of the factor XI deficiency of the specimen. Some comparisons are made to recent CAP surveys of factor VIII and IX activity. Considerable interlaboratory variation is noted with respect to technical aspects of factor assays (i.e., dilution of normal plasma used to construct the standard curve, etc.). Procedures used by some laboratories in handling patient specimens for factor assays, such as freezing the patient specimen, may decrease the chance of identifying a mild factor XI deficiency. The need for standardization of factor assays is evident from the survey data.

Factor XI↗
PubMed1981

New methods in coagulation.

Recent advances in the elucidation of the molecular biochemistry of the coagulation proteins have provided the foundation for the development of synthetic substrates. These substrates are oligopeptide with either a chromophore or fluorophore group attached to the C-terminal end. They may be used in the laboratory to assay for a number of the serine proteases involved in either coagulation or fibrinolysis. Also, by suitably modifying the assay system, the various inhibitors can be quantitated. These substrates promise to revolutionize the coagulation laboratory allowing for more precise quantitation of trace enzymes and also improved standardization and precision of coagulation assays. In addition to these substrates, the introduction of a number of immunologic procedures into the diagnostic laboratory have been of major importance in elucidating the heterogeneity of hereditary coagulation defects. By correlating the immunologic assays, coagulation assays and clinical picture, a number of subgroups of hereditary deficiencies have been identified. Also, the immunologic assays have provided a means for identifying the carrier state of hemophilia A and have significantly contributed to the improved diagnosis of von Willebrand's disease. The use of ristocetin cofactor assays, when used in conjunction with the Factor VIII antigens, have enable the laboratory to more accurately diagnose the majority of patients with von Willebrand's disease. Ristocetin cofactor may be assayed utilizing either formalin fixed or washed platelets and recently a snake venom has been introduced to assay for this particular aspect of the Factor VIII complex. Platelet specific proteins (i.e., platelet factor 4 and beta-thromboglobulin) may be assayed utilizing either radioimmunoassays or in the case of platelet factor 4 modified coagulation assays. These proteins provide evidence of in vivo platelet activation and hopefully may, in the future, be correlated with platelet kinetics.

Blood Coagulation↗
PubMed1981

Laboratory monitoring of heparin. Effect of reagents and instruments on the activated partial thromboplastin time.

The CAP Hematology Survey of 1979-1980 included specimens with heparin levels between 0.0 and 0.8 U/ml. The results obtained with different reagent-instrument systems in common usage were analyzed. Sensitivity to heparin was dependent upon choice of reagent and did not appear to be influenced by choice of instrument. All systems displayed a loss of precision with increasing APTT which was independent of the choice of reagent. Compared to the photo-optical instruments, the BBL Fibrometer showed a greater loss of precision with longer APTT's. The results are discussed in terms of their effect on the laboratory's ability to adequately monitor heparin therapy.

Animals↗
PubMed1980

Factor assay (VIII and IX) results in the College of American Pathologists Survey Program (1976-1979).

Data from the 1976-1979 CAP Surveys for Factor VIII assays are reviewed. Beginning in 1979, Factor IX assays were also performed by survey participants. Data was obtained from approximately 2500 laboratories and the different instrument-reagents are ranked according to precision and sensitivity. Also, the results of questionnaires on specific assay techniques (1977 through 1979) are analyzed. A trend was noted indicating an increasing number of laboratories are now performing factor assays. There is poor correlation between precision and sensitivity of most systems (i.e., instrument and reagent combination). For any given system, there was considerable variation in precision from a normal Factor VIII levels specimen to a low Factor VIII specimen. This was also the case with respect to Factor IX assays. With respect to the technical aspects of factor assays there was marked interlaboratory variation (i.e., dilution of normal plasma used to construct standard curve, etc.). The need for standardization of factor assays is evident from the survey data.

Factor IX↗
PubMed1980

Laboratory monitoring of heparin therapy--the effect of different salts of heparin on the activated partial thromboplastin time.

Data from the 1978 CAP Hematology Survey were analyzed for the effect of sodium and calcium salts of heparin on the activated partial thromboplastin time (APTT). The results indicate that the sodium salt of heparin prolongs the APTT more than the calcium salt at a heparin concentration of 0.2 units/ml. Furthermore, there was a variable response of the different APTT reagents to the different heparin salts. Data from the 1979 CAP Hematology Survey showed a greater sensitivity of the Automated APTT reagent and the Platelin Plus Activator of General Diagnostics compared with Actin (Dade) and Thrombofax (Ortho) at therapeutic heparin levels of 0.2 units/ml to 0.4 units/ml. The 1979 CAP heparin questionnaire results are presented and analyzed.

Blood Coagulation Tests↗
PubMed1979

Cap survey results for factor VIII assays (1977-1978).

This paper combines the data from the 1976, 1977, and 1978 CAP Surveys concerning factor VIII methods. The different instrument-reagent combinations are ranked according to precision and sensitivity. The results of questionnaires on specific assay technic from 1977 and 1978 are analyzed. The number of laboratories performing factor VIII assays has increased from 1976 to 1978. There was a poor correlation between precision and sensitivity in most systems. For any given system, there was considerable variation in precision from a normal factor VIII level specimen to a low factor VIII specimen. Certain technics, such as the dilutions on normal plasma used to construct the standard activity curve, show considerable interlaboratory variation. The need for standardization of factor VIII assay methods is evident from this study.

Analysis of Variance↗
PubMed1979

Heparin: biochemistry, therapy, and laboratory monitoring.

Heparin has been used extensively in the treatment of venous thrombosis and pulmonary embolus and more recently as a prophylactic measure in high-risk patient populations. The chemistry and biologic, pharmacologic, and physiologic actions of heparin are discussed, with some emphasis on the role of antithrombin III. The various modes of heparin administration, dosage regimens, requirements, and indications for therapy are reviewed. Full-dose and minidose heparin therapy are discussed in detail. The advantages and disadvantages of the various laboratory tests used to monitor heparin therapy are covered, along with standardization of heparin preparations. Finally, complications associated with heparin therapy are pointed out.

Antithrombin III↗
PubMed1978

The effect of heparin on the activated partial thromboplastin time.

Data from the 1976 and 1977 CAP surveys were analyzed for response of the activated partial thromboplastin time (APTT) to heparin. Different sources and concentrations of heparin were used. The results indicate that the precision of the APTT is more dependent on instrumentation than on partial thromboplastin. This was true for all four of the heparinized specimens evaluated. A single exception was found with the "old" Dade reagent activated cephaloplastin. The mean difference in the activated partial thromboplastin times obtained with differing concentrations of heparin was entirely dependent on the partial thromboplastin reagent used. No significant difference in the results was found when equal concentrations of bovine lung and porcine intestinal mucosal heparin were compared.

Animals↗