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Biomedical subjects

K D Friedman

Publications and source records attributed to K D Friedman.

At least 19 recordsLinked to original sources
PubMed2006

Urgent reversal of warfarin with prothrombin complex concentrate.

BACKGROUND: When life-threatening bleeding occurs in patients on warfarin, timely reversal becomes imperative. In the USA, warfarin effect is commonly reversed with fresh frozen plasma (FFP). The use of FFP is complicated by delays in correction, volume overload and often, inadequate correction. OBJECTIVE: Evaluate the feasibility and efficacy of a protocol for rapid administration of prothrombin complex concentrate (PCC) in the setting of the urgent need for reversal of warfarin. METHODS/PATIENTS: We instituted a policy for rapid delivery and administration of PCC. Appropriate patients received 25-50 U kg(-1) of PCC. The prothrombin time (PT)/International Normalized Ratios (INR) was recorded before and immediately after dosing, and 24 h postdosing. Patients requiring surgical interventions were cleared for the operating room (OR) immediately. Fifty-eight patients were treated, with a median age of 75.5 years (range 26-92). RESULTS: The median INR on presentation was 3.8 (1.4-52.8). Immediately following PCC administration the median INR was 1.3 (0.9-5.7), only two patients with INRs exceeding 2.0. The benefit was maintained at 24 h with a median INR of 1.5 (1.1-3.4). Four patients experienced thrombotic events during their hospitalization, (two deep vein thrombosis, two non-q-wave myocardial infarction) although none was attributed to PPC therapy. CONCLUSIONS: PCC administration is an effective treatment modality for the correction of warfarin anticoagulation in the urgent setting. Advantages over FFP include more timely correction, absence of volume overload and potentially more complete correction. Broader use of PCC in this setting appears to be appropriate.

Adult↗
PubMed2004

Measurement of von Willebrand factor cleaving protease (ADAMTS-13): results of an international collaborative study involving 11 methods testing the same set of coded plasmas.

BACKGROUND: ADAMTS-13 is a von Willebrand factor (VFW)-cleaving protease. Its congenital or acquired deficiency is associated with thrombotic thrombocytopenic purpura (TTP) and more rarely with the hemolytic uremic syndrome. We report on a survey evaluating 11 methods for ADAMTS-13 measurement performed in different labs. DESIGN: Two plasmas, one normal and one from a patient with familial TTP, were mixed at the co-ordinating center to prepare 6 plasmas with 0%, 10%, 20%, 40%, 80% and 100% ADAMTS-13 levels. Each plasma was aliquoted and assembled into sets of 60 (coded from 1 to 60), each containing 10 copies of the original 6 plasmas. Plasmas were frozen and shipped in dry ice to 10 labs with a common frozen reference plasma. Laboratories were asked to measure ADAMTS-13 with their methods. Results were sent to the coordinating center for statistical analysis. RESULTS: Of the 10 methods performed under static conditions 9 were quantitative and one was semiquantitative. One method performed under flow conditions evaluated the extent of cleavage of endothelial cell-derived ultralarge VWF string-like structures and expressed results as deficient, normal, or borderline. Linearity (expected-vs-observed levels), assessed as the squared correlation coefficient, ranged from 0.98 to 0.39. Reproducibility, expressed as the coefficient of variation for repeated measurements, ranged from < 10% to 83%. The majority of methods were able to discriminate between different ADAMTS-13 levels. The majority were able to detect the plasma with 0% level and some of them to discriminate between 0% and 10%. Overall the best performance was observed for three methods measuring cleaved VWF by ristocetin cofactor, collagen binding, and immunoblotting of degraded multimers of VWF substrate, respectively. The poor interlaboratory agreement of results was hardly affected by the use of the common standard. The method performed under flow conditions identified the plasmas with 0%, 10%, 20% and 40% activity as deficient in 7, 5, 1 and 3 of the 10 replicate measurements. The plasmas with 80% and 100% were identified as normal in all of the 10 replicate measurements. CONCLUSIONS: The survey shows varied performance, but supports an optimistic view about the reliability of current methods for ADAMTS-13.

ADAM Proteins↗
PubMed2000

A multi-site study for detection of the factor V (Leiden) mutation from genomic DNA using a homogeneous invader microtiter plate fluorescence resonance energy transfer (FRET) assay.

The goal of this multicenter study was to evaluate the second-generation Invader technology for detecting the factor V (Leiden) mutation directly from genomic DNA of different sample types. Invader assay results were compared with polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) or allele-specific PCR (AS-PCR) analysis. The Invader assay is a PCR-independent methodology that uses a microtiter plate format. In the assay, a specific upstream Invader oligonucleotide and a downstream probe hybridize in tandem to a complementary DNA template and form a partially overlapping structure. The Cleavase VIII enzyme recognizes and cuts this structure to release the 5' flap of the probe. This flap then serves as an Invader oligonucleotide to direct cleavage of a fluorescence resonance energy transfer (FRET) probe in a second invasive cleavage reaction. Cleavage of this FRET probe results in the generation of a fluorescent signal. The results of the Invader assay were 99.5% concordant with the PCR-based methods. Of the 372 samples tested once, only two gave discordant results (one from operator error and one from unknown causes), but were concordant on retesting. These results indicate that a simple microtiter plate-based Invader assay can reliably genotype clinical patient samples for the factor V (Leiden) point mutation directly from genomic DNA without prior target amplification.

Base Sequence↗
PubMed2000

Genotyping of factor V G1691A (Leiden) without the use of PCR by invasive cleavage of oligonucleotide probes.

BACKGROUND: The factor V G1691A Leiden (FVL) mutation is the most common known hereditary risk factor for venous thrombosis. METHODS: Third Wave Technologies, Inc. (Madison, WI) has developed a new microtiter plate-based assay that does not require PCR, restriction digestion, or gel electrophoresis. This technology system, termed the Invader(TM) assay, utilizes a 5' "invading" oligonucleotide and a partially overlapping 3' "signal" oligonucleotide, which together form a specific structure when bound to a complementary genomic DNA template. A thermostable flap endonuclease cleaves this structure, releasing the 5' flap from the signal oligonucleotide. Increased temperature and an excess of the signal probe enable multiple probes to be cleaved for each target sequence present without temperature cycling. The cleaved probes then direct cleavage of a secondary probe, which is 5' end-labeled with fluorescein but is quenched by an internal dye. Upon cleavage, the fluorescein-labeled product is detected using a standard fluorescence plate reader. Genotypes are determined by net wild-type/mutant signal ratio. RESULTS: Complete concordance was observed, after resolution of four discordances, when 1369 individuals (1264 wild type, 102 heterozygous, 3 homozygous) were FVL genotyped by both the Invader assay and by allele-specific PCR. CONCLUSION: We conclude that FVL genotyping using invasive cleavage of oligonucleotide probes is a rapid and reliable alternative to genotyping by more traditional PCR-based methods.

DNA↗
PubMed1999

Contribution of the glycoprotein Ia 807TT, methylene tetrahydrofolate reductase 677TT and prothrombin 20210GA genotypes to prothrombotic risk among factor V 1691GA (Leiden) carriers.

The cooperative effects of the GPIa 807TT, MTHFR 677TT and prothrombin 20210GA genotypes with the FV Leiden 1691GA (FVL) genotype were evaluated by comparing these genotype frequencies in 77 asymptomatic and 156 symptomatic heterozygous FVL carriers. The GPIa 807TT and MTHFR 677TT genotypes did not segregate within the symptomatic FVL carrier group and did not contribute to venous thrombotic risk in this patient cohort. There was no difference in the prothrombin 20210GA genotype frequency between asymptomatic FVL carriers and a random Caucasian control group; however, the prothrombin 20210GA genotype was nearly 5 times as prevalent (19/156 v 2/77; P < 0.02) in the symptomatic FVL carriers (odds ratio 5.21; 95% confidence interval 1.20-47.62), demonstrating that this important prothrombotic risk factor acts synergistically with FVL.

Factor V↗
PubMed1999

Allelic distribution of the glycoprotein Ia (alpha2-integrin) C807T/G873A dimorphisms among caucasian venous thrombosis patients and six racial groups.

Two linked silent dimorphisms, 807 C --> T (Phe224) and 873 G --> A (Thr246) within the glycoprotein Ia (GPIa) gene have been correlated with low and high platelet receptor density, respectively, and associated with vascular disease. A multiplexed allele-specific PCR assay was used to determine the GPIa 807T/873A allele frequency among 331 Caucasian venous thrombosis patients and 3571 unrelated individuals belonging to six different racial groups. The 807T/873A allele frequencies were 54%, 51%, 39%, 39%, 38%, 34% and 30% among Native Americans, Hispanics, Caucasians, Caucasian venous thrombosis patients, Asian Indians, African-Americans, and Koreans, respectively. Significant differences in the GPIa allele frequency among racial groups were revealed which emphasized the need for appropriate controls in studies evaluating the association of GPIa genotype to vascular disease.

Alleles↗
PubMed1999

Prevalence of prothrombin G20210A, factor V G1691A (Leiden), and methylenetetrahydrofolate reductase (MTHFR) C677T in seven different populations determined by multiplex allele-specific PCR.

Individuals belonging to six racial groups (African American, Asian Indian, Caucasian, Hispanic, Korean, Native American), and a seventh group comprised of referred patients with thrombosis were genotyped for the prothrombin G20210A mutation, the factor V G1691A (Leiden) mutation, and the methylenetetrahydrofolate reductase (MTHFR) C677T mutation by multiplexed allele-specific PCR. The prothrombin 20210A and factor V 1691A allele frequencies in the thrombosis patients, 3.2% and 9.5%, were significantly higher than those in the random Caucasians, 1.3% and 1.8%, (p = 0.043 and p <0.001, respectively). The relative risk of venous thrombosis was determined to be 2.4-fold for carriers of the prothrombin 20210A allele (odds ratio = 2.54; 95% confidence interval = 0.94, 6.82) and 4.5-fold for carriers of the factor V 1691A allele (odds ratio = 5.06; 95% confidence interval = 2.25, 11.36). Among the seven populations, significant differences were observed in the MTHFR 677T allele distribution, however this mutation was not determined to be a risk factor for venous thrombosis in the patient group studied, either alone or in combination with the prothrombin 20210A and/or the factor V 1691A allele(s).

Alleles↗
PubMed1995

Phase I trial of simultaneous administration of interleukin 2 and interleukin 4 subcutaneously.

Interleukin (IL) 2 plays an important role in enhancing the immune response, whereas IL-4 has pluripotent activities which include affecting immune function. Preclinical data suggest that the combination might have enhanced immunomodulatory activity. In this Phase I trial in patients with advanced solid tumors, both IL-2 and IL-4 were given by separate s.c. injections simultaneously daily, 5 days in a row, Monday through Friday, for 3 consecutive weeks, followed by a 1-week break from treatment. Cycles could be repeated. The dose of IL-2 was kept constant at 9 x 10(6) IU/m2/injection while the dose of IL-4 was escalated beginning at 100 microgram/m2/injection and increasing by 100-microgram/m2 increments to a planned level of 400 microgram/m2/injection. Sixteen patients were entered in this study, with one patient being ineligible because of the presence of brain metastases. Of the 15 eligible patients, there were 14 males and 1 female, with a median age of 54 (range, 38-67) years and initial performance status of 0 in 5 patients and 1 in 10 patients. Patients were treated at levels of up to 300 microgram/m2/injection of IL-4 before the study was closed due to withdrawal of the drug by the manufacturer. The most commonly observed toxicities were fatigue, fever and chills, local reaction, nausea/vomiting and anorexia, headache and nasal stuffiness, and coughing, sometimes with the production of clear white sputum, more common in smokers. Duodenal ulcers occurred in one patient and one patient had grade 4 cardiac toxicity consisting of an asymptomatic minimal elevation of the creatinine phosphokinase MB isoenzyme (CPK-MB). Grade 3 hyponatremia occurred in two patients, and elevated liver function tests and creatinine occurred but were not dose limiting. Eosinophilia of unknown significance occurred in all patients. There were statistically significant elevations in absolute numbers of most T-cell subsets examined, without changes in circulating B cells. No antibodies to the IL-4 were found after one cycle. One patient with renal cell carcinoma showed a significant decrease in tumor burden after one cycle of treatment. Because of the IL-4 withdrawal, the maximum tolerated dose for this combination of drugs given by the route and schedule used here was not determined and will require additional testing. Subcutaneous IL-2 and IL-4 given simultaneously show important immunomodulatory and antitumor effects and should be tested further in cancer patients.

Adult↗
PubMed1994

A phase III trial of recombinant human erythropoietin therapy in nonanemic orthopedic patients subjected to aggressive removal of blood for autologous use: dose, response, toxicity, and efficacy.

BACKGROUND: Previous clinical trials have shown that the use of recombinant human erythropoietin (EPO) can facilitate autologous blood donation and reduce allogeneic blood transfusions in autologous blood donors who are anemic at first donation. However, the role of EPO therapy in nonanemic patients remains undefined. To identify this role, a randomized, controlled, multicenter dose-escalation trial was conducted in patients whose initial hematocrit was > 39 percent (0.39). STUDY DESIGN AND METHODS: EPO (150, 300, or 600 units/kg) or placebo was administered intravenously at each of six phlebotomy visits over a 3-week study period. Sixteen (14%) of 116 patients were unable to complete the treatment protocol because of adverse events (n = 11) or for personal reasons (n = 5); 2 patients (1 EPO and 1 placebo) experienced serious adverse events. RESULTS: In 91 evaluable patients, additional red cell production during the study period was 440 +/- 176, 621 +/- 215, 644 +/- 196, and 856 +/- 206 mL (mean +/- SD), respectively, for patients receiving placebo and EPO at 150, 300, and 600 units/kg (p < 0.05 for all EPO groups compared to placebo). However, the percentages of patients in each group who received allogeneic blood did not differ: 2 (9%) of 23 placebo patients and 6 (9%) of 68 EPO patients. CONCLUSION: It is concluded that, while EPO therapy increased preoperative red cell production, no clinical benefit could be demonstrated in autologous blood donors who were not anemic at first blood donation.

Adolescent↗
PubMed1994

Erythropoietin response to anaemia is not altered by surgery or recombinant human erythropoietin therapy.

Recombinant human erythropoietin (EPO) therapy has been shown to increase red blood cell (RBC) production and facilitate autologous blood donation before elective surgery. However, recent reports have suggested that surgery and/or EPO therapy may suppress endogenous erythropoietin secretion in response to anaemia. We therefore analysed the haemoglobin/erythropoietin relationship preoperatively and postoperatively in 71 autologous blood donors subjected to aggressive phlebotomy and six treatments with either EPO (150 U/kg, n = 16, 300 U/kg, n = 18, or 600 U/kg, n = 19) or placebo (n = 18). Using data from the three preoperative study visits, the linear relationship between log erythropoietin and haemoglobin was determined for each of the 18 placebo patients. We found no significant differences in the slopes of the relationships in this group during aggressive phlebotomy. Furthermore, there was no evidence of a significant difference in the erythropoietin level recorded postoperatively for each patient to that predicted from the patient's postoperative haemoglobin level, based on the haemoglobin/log erythropoietin relationship preoperatively. Similarly, for each of the EPO-treated groups, there was no evidence of a significant difference when comparing the recorded erythropoietin level to that predicted from each patient's postoperative haemoglobin level, based on the haemoglobin/log erythropoietin relationship preoperatively. We conclude that preoperative recombinant human erythropoietin therapy and/or surgery do not adversely affect the postoperative erythropoietin response to anaemia.

Adult↗
PubMed1991

Abnormal binding of factor VIII is linked with the substitution of glutamine for arginine 91 in von Willebrand factor in a variant form of von Willebrand disease.

von Willebrand factor (vWf) is a multimeric plasma glycoprotein that functions in hemostasis as the initiator of platelet adhesion to damaged blood vessels and as the carrier of Factor VIII (FVIII). Montgomery et al. (Montgomery, R.R., Hathaway, W.E., Johnson, J., Jacobsen, L., and Muntean, W. (1982) Blood 60, 201-207) reported a variant of von Willebrand disease characterized by the abnormal interaction between FVIII and a defective vWf. To identify the molecular basis of this abnormal interaction, we isolated platelet RNA from members of one of the affected families and determined the nucleotide sequence of the FVIII-binding domain encoded by the vWf mRNA. A single G to A transition at nucleotide 2561 was linked with disease expression and results in the substitution of Gln for Arg91 in mature vWf. A restriction fragment containing this mutation was introduced into a full-length vWf expression vector, and both wild type and mutant vWf were expressed in COS-7 cells. In a solid-phase binding assay, expressed vWf was captured with anti-vWf monoclonal antibody AVW1 and then incubated with 6.25-400 milliunits of recombinant FVIII. After washing, vWf-bound FVIII activity was determined with a chromogenic assay. Mutant vWf showed reduced binding of FVIII compared with wild type, suggesting that the substitution of Gln for Arg91 is the likely basis for the abnormal vWf/FVIII interaction in this von Willebrand disease variant.

Arginine↗
PubMed1988

Protein C deficiency. A cause of unusual or unexplained thrombosis.

Familial hypercoagulable states are a collection of syndromes characterized by an inherited deficiency of various proteins involved in the control of coagulation and include antithrombin III, plasminogen, protein C, and protein S. Affected patients usually develop venous thrombosis as adults. During a 15-month interval, we identified five patients with venous thrombosis accompanied by protein C deficiency. Four patients presented with deep venous thrombosis, which was recurrent in two, and one patient developed mesenteric venous thrombosis. The kindred of this last patient suggested an autosomal dominant genetic transmission of protein C deficiency. Patients' ages at the time of diagnosis of disease ranged from 28 to 41 years. All patients had low levels of protein C (range, 34 to 67 U/dL; normal, 70 to 130 U/dL). All patients were treated with heparin sodium immediately and then given long-term oral anticoagulation therapy with warfarin sodium. Protein C deficiency is a predisposing factor to the development of venous thrombosis that has only recently been recognized. Treatment of symptomatic protein C deficiency requires short-term heparin therapy followed by long-term oral anticoagulation therapy with warfarin. Oral anticoagulation treatment must be initiated slowly with no loading dose to avoid warfarin-associated skin necrosis. Patients with unexplained or unusual thrombosis, especially if it occurs at an early age, and patients with recurrent episodes of lower limb venous thrombosis should have their protein C levels measured. If a deficiency is documented, long-term warfarin anticoagulation therapy is recommended.

Adult↗
PubMed1988

Thrombolytic therapy with tissue plasminogen activator or streptokinase induces transient thrombin activity.

We have determined the plasma level of fibrinopeptide A as a specific index of thrombin activity during the infusion of a thrombolytic agent in patients with acute myocardial infarction. Peripheral venous plasma levels of fibrinopeptide A increased following the initiation of thrombolytic therapy from 2.7 nmol/L to a peak of 13.0 nmol/L at 30 minutes with streptokinase and from 1.1 nmol/L to a peak of 10.7 nmol/L at 90 minutes with tissue plasminogen activator. The amount of fibrinogen converted to fibrin I was determined by integration of the plasma level of fibrinopeptide A over time. The amount of fibrin I formed over the five-hour period from the start of drug infusion was approximately 10 mg/dL in response to either streptokinase or recombinant tissue plasminogen activator. We conclude that activation of coagulation occurs in response to thrombolytic therapy despite heparin administration. This thrombin action, though transient, would be sufficient to cause rethrombosis if localized and incompletely opposed by fibrinolytic activity.

Fibrin↗
PubMed1987

Quantitation of fragment X formation during thrombolytic therapy with streptokinase and tissue plasminogen activator.

We have determined the extent of fragment X formation during thrombolytic therapy by integration over time of the plasma fibrinopeptide B beta 1-42 concentration. This peptide is quantitatively released when fragment X is formed by plasmin action on fibrinogen or fibrin I. In response to streptokinase (SK) and rt-PA, 264 +/- 54 and 95 +/- 12 mg/dl respectively of fibrinogen was converted to fragment X. By immunoblotting, fragment X was demonstrated as early as 5 min after SK and 30 min after rt-PA, and was still evident 24 h after treatment. Patients treated with SK showed extensive further plasmin degradation of fragment X to fragments Y and D. Thus fragment X concentrations tend to be more similar in the two groups than would be expected from the extent of fibrinogen breakdown. Fragment X forms clots, but these have lower tensile strength and are more susceptible to further plasmin lysis than clots of fibrin. Thus the similar bleeding observed in the two treatment groups might be a reflection of their similar plasma fragment X concentrations.

Fibrin Fibrinogen Degradation Products↗
PubMed1986

Heparin cofactor activity and antithrombin III antigen levels in preeclampsia.

It has been reported that patients with preeclampsia have decreased levels of antithrombin III heparin cofactor and that the degree of depression parallels the severity of disease. To determine the time course of development and resolution of this deficiency, and to gain insight into the cause of this deficiency, plasma antithrombin III antigen and heparin cofactor activity levels were measured serially in 11 women with mild preeclampsia. Although the ATIII antigen level remained stable during the antepartum period, the level of heparin cofactor was noted to fall progressively during the antepartum period. Both ATIII antigen and heparin cofactor increased promptly postpartum. The discrepancy between the levels of ATIII antigen and heparin cofactor activity suggests that in both mild and severe preeclampsia there is utilization of antithrombin III to form inactive protease inhibitor complexes.

Antigens↗