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Biomedical subjects

F R Rickles

Publications and source records attributed to F R Rickles.

At least 55 records · Page 3Linked to original sources
PubMed1992

Influence of age, performance status, body weight, and tumor type in individuals with cancer on the disposition of warfarin and its enantiomers: Department of Veterans Affairs cooperative study number 75.

Plasma warfarin and its R,S enantiomer concentrations, one-stage prothrombin times, and mean daily warfarin doses were analyzed in 196 patients given warfarin. These individuals were part of a controlled clinical trial that examined the effect of warfarin as an adjuvant to "standard" treatment in a variety of malignancies. Neither the plasma warfarin concentration nor the daily warfarin dose required to produce a given degree of prothrombin-time prolongation was influenced by age or body weight in these subjects. When the data were analyzed by performance status, we noted several variations of interest. Individuals with different tumor types demonstrated disparities in warfarin disposition. Patients with colorectal cancer, for example, required lower mean daily warfarin doses to achieve a given degree of one-stage prothrombin time prolongation. Analysis of warfarin enantiomers (R,S) in a selected group of patients demonstrated a lower-than-normal ratio (2:1) for the colorectal cancer group (1.42:1) because of an apparent decrease in the plasma R component. In contrast, patients with head and neck cancer demonstrated a ratio of 2.85:1, and the R component was elevated. Warfarin disposition and the effect of warfarin on vitamin K-dependent clotting factor production were altered in the patients with cancer reported in this study. The mechanisms for these alterations are complex and not completely understood.

Aging↗
PubMed1991

Continuous infusion of monoclonal antibody-purified factor VIII.

Continuous intravenous infusion of wet and dry heat treated factor VIII products has been shown to be an effective, safe, and convenient alternative to pulse-dose therapy for the treatment of patients with hemophilia. We have used 12-hr, single-bottle continuous infusion of a factor VIII product purified from plasma sources by the use of monoclonal antibodies (Monoclate; Rorer Pharmaceutical Company) for the treatment of four bleeding episodes in three patients with severe hemophilia A. Patients required 2.1 U/kg/hr to attain an in vivo factor VIII level of 50 U/dl. Clinical hemostasis was achieved for all treatment episodes and no untoward effects of therapy were noted. Stability of the factor VIII:C levels in the product in vitro was also demonstrated. We conclude from this preliminary data that continuous infusion of factor VIII products purified by monoclonal antibody technology is a safe, effective, and practical approach to the treatment of patients with hemophilia A.

Antibodies, Monoclonal↗
PubMed1990

Purification and preliminary characterization of rabbit vitamin K-dependent coagulation proteins.

We describe herein a procedure for the purification of protein C, protein S, prothrombin, factor VII, and factor X to apparent homogeneity from rabbit plasma. The initial steps, which are common to the purification of vitamin K-dependent proteins from other mammalian species, include adsorption onto and elution from barium followed by anion exchange chromatography. Proteins were further purified using a variety of techniques, including affinity chromatography, gel filtration, and anion exchange chromatography in a Fast Protein Liquid Chromatography system. Significant structural homologies exist between rabbit, human, and bovine vitamin K-dependent proteins. As is true for protein C and factor X in human and bovine plasma, rabbit protein C and factor X are two-chain proteins which can be converted to active proteases by specific venom activators. Rabbit factor VII is also a two-chain protein and can restore coagulant activity to human or bovine plasma deficient in factor VII. In contrast, rabbit protein S and prothrombin are single chain proteins. In view of the well-described species specificity of many of the vitamin K-dependent proteins, purified rabbit coagulant and anticoagulant proteins should be useful in the development of animal models of coagulation and/or thrombosis.

Animals↗
PubMed1990

Heparin abolishes the chemotherapy-induced increase in plasma fibrinopeptide A levels.

PURPOSE, PATIENTS, AND METHODS: Blood coagulation abnormalities are common in patients with cancer, particularly after treatment with chemotherapeutic agents. Chemotherapy has been associated with an increased incidence of thromboembolic events, and patients treated with chemotherapy often develop evidence of local phlebitis, which may lead to loss of venous access. We have utilized the radioimmunoassay for plasma fibrinopeptide A (FPA) and in vitro FPA generation to assess the rate of in vivo blood coagulation and the level of plasma thrombin activity in 16 cancer patients treated with chemotherapy. Eight patients were treated twice, once with chemotherapy alone and once with chemotherapy after an intravenous infusion of heparin (5,000 U). RESULTS: Our results confirm that FPA levels are elevated in most cancer patients. Following chemotherapy, FPA levels were further increased within 45 minutes (mean FPA = 5.2 ng/mL before chemotherapy versus 8.3 ng/mL after chemotherapy, p less than 0.01) and were accompanied by an increase in the FPA generation rate. Infusion of heparin prior to chemotherapy significantly lowered plasma FPA levels and abolished post-chemotherapy FPA generation. CONCLUSION: These data suggest that patients receiving chemotherapy express thrombin-like activity in plasma and, therefore, may be at risk for clinically significant intravascular activation of coagulation. Heparin diminished the laboratory evidence of this chemotherapy-related coagulopathy and may have a role in the prevention of thromboembolic disorders in some cancer patients undergoing cytotoxic therapy.

Antineoplastic Agents↗
PubMed1989

The use of continuous infusion of factor concentrates in the treatment of hemophilia.

Bolus infusion of clotting factor concentrates remains the most common approach to the treatment or prevention of bleeding in patients with hemophilia. Although successful use of continuous infusion of such concentrates has been reported by several groups, this alternative treatment method has not achieved widespread popularity. We report here our experience in one hemophilia center with the use of continuous infusion of factor VIII and factor IX concentrates in 13 patients, 11 with hemophilia A, and 2 with hemophilia B. All patients were treated successfully for bleeding episodes (e.g., hemarthroses, intracranial, or gastrointestinal bleeding) or for surgical procedures (appendectomy, thoracotomy, etc.). Three patients with low titer factor VIII inhibitors were treated successfully with constant infusion therapy, requiring a mean dose of factor VIII concentrate 2.3 fold (8.20 u/kg/h) higher than that of the patients without inhibitors (3.63 u/kg/h) to maintain a circulating plasma level of factor VIII of 1 u/ml. The use of constant infusion of clotting factor concentrates is safe, efficacious, and more convenient than bolus therapy of factor concentrates and should be considered for hospitalized hemophilia patients requiring replacement therapy.

Adolescent↗
PubMed1989

Severe hyponatremia after repeated intravenous administration of desmopressin.

Desmopressin (DDAVP) has recently been found to improve hemostasis in patients with congenital or acquired disorders of coagulation and to reduce operative blood loss in patients with normal hemostasis undergoing certain surgical procedures. Despite its potent antidiuretic effect, severe hyponatremia after the intravenous administration of DDAVP is felt to be rare. We report four cases of severe hyponatremia with serious clinical sequelae occurring in patients with underlying coagulopathies who were treated prophylactically with DDAVP to improve hemostasis prior to surgical procedures. Each patient received multiple (3-22) doses of DDAVP and was given intravenous hydration with hypotonic solutions before developing clinical signs and laboratory evidence of hyponatremia. We believe that the risk of significant hyponatremia after treatment with intravenous DDAVP may be higher than is generally appreciated and that patients undergoing surgical procedures, who often receive multiple doses of DDAVP and intravenous hydration, are at particular risk for this complication. Hypotonic intravenous solutions should be avoided and serum sodium levels should be monitored frequently in those patients receiving multiple doses of DDAVP.

Adenoidectomy↗
PubMed1988

Effect of mopidamol on survival in carcinoma of the lung and colon: final report of Veterans Administration Cooperative Study No. 188.

Mopidamol (RA-233), a derivative of dipyridamole, is a phosphodiesterase inhibitor that has been shown previously to limit progression of malignancy in certain experimental animal models and in a pilot study in humans. RA-233 plus chemotherapy was compared with chemotherapy alone in a 5-year double-blind trial involving 719 patients with advanced carcinomas of the lung and of the colon. RA-233 treatment was associated with a statistically significant prolongation of survival in patients with non-small cell lung cancer (N-SCLC) limited to one hemithorax and with reduction in mean plasma fibrogen concentration. RA-233 was not toxic. The favorable effects on survival could not be explained by any factor other than the RA-233 treatment. In other tumor categories tested, no differences in survival were observed. These results suggest that RA-233 is useful in the treatment of N-SCLC of limited extent. They also suggest that therapeutic intervention aimed at modified intracellular pathways might constitute a novel investigative approach to the treatment of cancer.

Carcinoma↗
PubMed1988

Antimetastatic agents. II. Summary of the interactions of tumor cells with blood coagulation factors, platelets, fibrinolytic factors, and inflammatory cells and their soluble mediators: potential for therapeutic interventions.

Although not reviewed during this session of the Workshop, other reactions in the hemostatic pathways are relevant to tumor-host cell interactions, are potential targets for antimetastatic agents, and are therefore included in Figure 1 and Table 1. For example, elsewhere in this issue of Seminars Loskutoff reviews the recent evidence for the importance of naturally occurring plasminogen activator inhibitors in the regulation of fibrinolysis. Since tumor cells may contain both tissue plasminogen activator and a urokinase-like plasminogen activator, the balance between tumor-mediated fibrin formation and fibrinolysis becomes an important issue in assessing antimetastatic treatment protocols. The relationship of the fibrinolytic pathways to metastasis has been reviewed recently by Dano and colleagues. Clearly, no single therapeutic approach designed to inhibit only one of these complicated interactions between tumor cells and host defense mechanisms is likely to be successful. However, each of the pathways illustrated (Fig. 1) and each of the theoretical steps in the metastatic cascade (Table 1) must be considered in the design of new strategies for the use of antimetastatic agents.

Anticoagulants↗
PubMed1988

Fibrinopeptide A during normal pregnancy.

Fibrinopeptide A (FPA) is the first peptide released from fibrinogen upon thrombin action. Plasma FPA is cleared rapidly with a first order kinetics and therefore its level reflects the rate of thrombin cleavage of fibrinogen. A prospective study was undertaken to establish normal values of FPA during pregnancy. The mean FPA for the pregnant group (n = 136) was 2.8 ng/ml (SD = 3.3) while it was 1.24 ng/ml (SD = 0.4) for a nonpregnant control group of healthy women (n = 30). The median FPA for the pregnant group was 2.2 ng/ml and 1.4 ng/ml for the nonpregnant group (Wilcoxon test P less than 0.0001). Plasma FPA levels increased with gestational age. The median value was 1.5 ng/ml in the first trimester (n = 18), 1.8 ng/ml in the second trimester (n = 40), and 2.5 ng/ml in the third trimester (n = 78). Plasma FPA concentrations in the third trimester were significantly higher than in the first and second trimester. These findings suggest increased thrombin activity and fibrin generation during the course of normal pregnancy.

Cross-Sectional Studies↗
PubMed1988

Monocyte procoagulant activity as a peripheral marker of clotting activation in cancer patients.

Peripheral blood monocytes generate the procoagulant tissue factor in vitro and in vivo in response to stimulation by a variety of agents. Monocytes from cancer patients generate significantly increased tissue factor and a quantitative relationship exists between the levels of monocyte tissue factor (MTF) and levels of circulating fibrinopeptide A (FPA), a marker of in vivo clotting activation. Furthermore, monocytes from cancer patients have a greater procoagulant response to stimulation by endotoxin in vitro, which appears independent of lymphocyte regulation. These findings suggest a priming process in vivo, and may reflect exposure of monocytes to tumor antigen(s) or components of the immune response to tumors.

Animals↗
PubMed1987

Identification of IL 2R+ T cells and macrophages within rejecting rat cardiac allografts, and comparison of the effects of treatment with anti-IL 2R monoclonal antibody or cyclosporin.

Monoclonal antibodies to lymphokine-induced activation antigens of lymphocytes and macrophages were used to analyze the intragraft events occurring during acute rejection of rat heterotopic cardiac allografts. The cells present during untreated rejection were then compared with those present in situ after immunosuppression with the mouse anti-rat IL 2 receptor (anti-IL 2R) monoclonal antibody ART-18 or cyclosporin (CsA). Untreated rats rejected their grafts within 7 days, whereas rats receiving 10 days of i.v. ART-18 antibody therapy showed graft prolongation to more than 21 days, and rats receiving CsA for 7 days maintained their grafts indefinitely. Untreated rejection was associated with an influx of T (W3/13+) cells and macrophages (ED-1+, ED-2+). Activated mononuclear cells (IL 2R+) were identified within rejecting grafts from day 2, and their numbers peaked on days 4 to 6 when 15 to 20% of infiltrating leukocytes were IL 2R+. Double labeling studies of IL 2R+ cells present at day 6 showed surprisingly that both T cells and macrophages expressed IL 2R. In particular, although 55.8 +/- 6.9% (mean +/- SD) of IL 2R+ cells expressed the pan-T cell antigen 3/13, a similar proportion of IL 2R+ cells (49.8 +/- 8.2%) expressed the macrophage antigen ED-2. Conversely, both T cells and macrophage populations showed heterogeneity in their expression of IL 2R, because 39.2 +/- 12.2% of T cells and 31.0 +/- 13.4% of macrophages were IL 2R+. In addition, inflammatory macrophages at day 6 expressed the A1-3 antigen. Expression of this antigen by macrophages has previously been linked with development of macrophage procoagulant activity, and in this model intragraft inflammatory macrophages were closely associated with widespread deposits of fibrin. By comparison with untreated animals, rats treated with either ART-18 or CsA both lacked detectable IL 2R+ cells during the first 14 days post-transplantation (post-Tx), and showed significantly less cellular infiltration. However, although grafts of CsA-treated animals continued to remain IL 2R- and failed to stain with the macrophage activation marker A1-3, ART-18-treated rats showed increasing infiltration by both IL 2R+ mononuclear cells and A1-3+ macrophages, as well as increasing perivascular and interstitial fibrin deposition, prior to rejection by day 22. These studies document the presence of small number of activated intragraft T cells and macrophages during rat cardiac rejection, and show how CsA, and to a lesser extent anti-IL 2R therapy, inhibit this in situ activation and prolong graft survival. (ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1987

Markers of thrombotic activity in arterial disease.

Levels of the platelet degranulation product beta-thromboglobulin (BTG) and the fibrinogen degradation product fibrinopeptide A (FPA) were measured in 26 asymptomatic subjects (group 1), 17 patients with peripheral vascular disease (PVD) (group 2), and 12 patients with PVD and bypass grafts (group 3). Mean BTG and FPA levels were elevated in both groups 2 and 3, indicating increased thrombotic activity in patients with PVD. Results of serial BTG and FPA assays in group 3 patients suggested a trend downward. These markers may be useful for estimating disease severity and prognosis, extent of graft healing and patency, and efficacy of therapeutic intervention.

Arterial Occlusive Diseases↗
PubMed1987

Pregnancy management and successful outcome of Ehlers-Danlos syndrome type IV.

Ehlers-Danlos syndrome type IV (EDS IV) is a rare but serious disorder of connective tissue that is characterized by the abnormal production or secretion of type III collagen. Experience with pregnant patients exhibiting this syndrome is limited. This report describes the successful management of a pregnancy in a woman with EDS IV that included activity restriction and complete bed rest after 32 weeks, use of 1-desamino-8-D-arginine vasopressin (DDAVP) before delivery to improve coagulation, and cesarean section before the onset of labor. The possibility of prenatal diagnosis based on genetic linkage studies also is discussed.

Adult↗