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PubMed1993

Platelets contain releasable coagulation factor IX antigen.

Platelets take up plasma proteins into their alpha granules. Platelet activation releases the alpha granule contents. The goal of this study was to test the hypothesis that human platelets also contain some coagulation factor IX in their alpha granules. Platelets were examined by immunofluorescence microscopy. Activated and unactivated platelets were quick frozen on to slides and dehydrated in situ to preserve optimal morphology. The slides were stained by indirect immunofluorescence for factors V and IX. Unactivated platelets showed coarsely granular staining for factor V and finely granular staining for factor IX. Staining for factor V was diffuse after activation, while staining for factor IX disappeared. Thus, the results support the conclusion that platelets contain factor IX which can be released upon activation. Immunoelectron microscopic studies were conducted to more precisely localize the site of the platelet factor IX. As expected, factor V was primarily localized in the alpha granules of unactivated platelets. By contrast, factor IX was observed both in alpha granules and diffusely in the platelet cytoplasm and membrane-bounded vesicles. After activation, staining for both factors V and IX was primarily in the open canalicular system. The physiological importance of this small amount of factor IX is unknown. However, it may be significant since only a few percent of normal IX levels are required to support haemostasis in the absence of trauma, and platelet factor IX could be released at sites of active coagulation.

Antigens↗
PubMed1987

Discordance in a pair of identical twin carriers of factor IX deficiency.

Female twin daughters of a man with hemophilia B were determined to be identical but widely discordant with respect to their degree of factor IX deficiency. The proposita had a marked deficiency (3%) of factor IX with clinical bleeding. She became pregnant. Delivery was managed with infusion of factor IX concentrates. These twins represent the second reported case of identical twins with discordant factor IX levels.

Adult↗
PubMed1998

Clinical evaluation of recombinant factor IX.

The pharmacokinetics, safety, and efficacy of recombinant factor IX (rFIX) have been evaluated in previously treated and untreated patients with hemophilia B. In a study of 56 previously treated patients, there was a total of 1,070 hemorrhages, which required 1,514 infusions of rFIX. Of the 1,070 episodes, 80% resolved after a single rFIX infusion. The majority of the remaining episodes requiring more than 1 infusion were either major or complicated hemorrhages. Eighty-seven percent of the 1,514 infusions were rated by the physicians or patients as providing an excellent or good response. These results are consistent with the efficacy data from other hemophilia product clinical trials. rFIX has also been administered as bolus doses or by continuous infusion in conjunction with 13 surgical procedures. Estimated blood loss during and after surgery was as expected when compared with blood loss for similar procedures in patients without hemophilia, and 97% of the clinical responses during and after surgery were rated by physicians or patients as excellent or good. Pharmacokinetic comparison of rFIX with one plasma-derived product showed a statistically significant lower recovery (28% less) of rFIX. The half-lives between the two products were comparable. Common adverse events associated with rFIX treatment have been comparable to other factor IX products. As expected, there has been no evidence of viral transmission by rFIX.

Drug Evaluation↗
PubMed1988

The role of beta-hydroxyaspartate and adjacent carboxylate residues in the first EGF domain of human factor IX.

beta-Hydroxyaspartic acid is a post-translationally modified amino acid found in a number of plasma proteins in a domain homologous to epidermal growth factor. Its presence can be correlated with a high affinity Ca2+ binding site, with a dissociation constant of 10-100 microM. We describe a system for the expression of human coagulation factor IX in dog kidney cells in tissue culture, in which the post-translational modifications and the biochemical activity are indistinguishable from factor IX synthesized in vivo. This system has been used to express eight different point mutations of human factor IX in the first epidermal growth factor domain in order to study the role of beta-hydroxyaspartate at residue 64, and the adjacent carboxylate residues at positions 47, 49 and 78. We conclude that this domain is essential for factor IX function and suggest that Ca2+ binds to carboxylate ions in this domain and stabilizes a conformation necessary for the interaction of factor IXa with factor X, factor VIII and phospholipid in the next step of the clotting cascade.

Amino Acid Sequence↗
PubMed1988

In vivo recovery and half-life time of a steam-treated factor IX concentrate in hemophilia B patients. The influence of reagents and standards.

Factor IX (FIX) recovery and half-life was measured in ten hemophilia B patients under standardized conditions. Each patient received a steam-treated high-purity factor IX concentrate at a dose of 19-39 U/kg body weight. FIX activity was determined using a one-stage assay, which was calibrated against the international concentrate standard (reagents from Immuno, Heidelberg). The in vivo recovery ranged from 24% to 53% (mean value 37.7%) and the half-disappearance time (HDT) from 8-30 h (mean 16.7 h). In four of the ten patients, the distribution and elimination half-lives were estimated and ranged from 0.3 h to 3.9 h (mean 1.4 h) and from 28.6 h to 39.7 h (mean 33.1 h), respectively. In six patients FIX was redetermined using a different FIX deficient plasma and a plasma standard (reagents from Merz & Dade, Munich, FRG). Recoveries and HDT based on the results obtained with this method were significantly higher (68.2% vs 39.7%; p less than 0.05), and longer (14.8 h vs 10.6 h; p less than 0.05), respectively. FIX activity was also measured by both assay systems in 100 healthy subjects (50 males, 50 females). The reagents from Immuno yielded a mean value of 0.77 U/ml, while the mean FIX activity utilizing standards and reagents from Merz & Dade was 1.11 U/ml (p less than 0.000001). The coefficient of correlation between the FIX activity measurements, as determined in 100 healthy subjects and 6 hemophilia B patients using the different test systems, was r = 0.9 (N = 159; y = 0.08 +/- 1.3* chi; p less than 0.001). Our data suggest that recovery and HDT of factor IX concentrate strongly depend on the assay and calibration conditions and that an international FIX activity plasma standard is urgently required.

Adolescent↗
PubMed1989

Blood clotting factor IX BM Nagoya. Substitution of arginine 180 by tryptophan and its activation by alpha-chymotrypsin and rat mast cell chymase.

Factor IX BM Nagoya (IX Nagoya) is a natural mutant of factor IX responsible for severe hemophilia B. A patient with this mutant is characterized by a markedly prolonged ox brain prothrombin time. IX Nagoya was purified from the patient's plasma by immunoaffinity chromatography with an anti-factor IX monoclonal antibody column. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed that treatment of IX Nagoya with factor XIa/Ca2+ resulted in cleavage only at the Arg145-Ala146 bond. Reversed-phase high performance liquid chromatography of a trypsin digest of IX Nagoya showed an aberrant peptide, which was further digested with proteinase Asp-N. Primary structure analysis of one of the Asp-N peptides revealed that Arg180 is replaced by Trp. An essentially complete (99%) amino acid sequence of IX Nagoya was obtained by sequencing fragments derived from a lysyl endopeptidase digest in which no other substitutions in the catalytic triad or substrate binding site were found. We also found that IX Nagoya is activated by alpha-chymotrypsin or rat mast cell chymase by monitoring the rate of factor X activation using a fluorogenic peptide substrate in the presence of factor VIII, phospholipids, and Ca2+. These results indicate that the substitution of Arg180 by Trp impairs the cleavage by factor XIa required for activation of this zymogen and that the substitution causes hemophilia BM.

Amino Acid Sequence↗
PubMed1983

Studies of factor IX concentrate therapy in hemophilia.

The effects of factor IX concentrate therapy on hemostasis in hemophilia patients were studied by means of the radiometric factor IXa assay, the coupled amidolytic assay for factor VIIa, and coagulant assays for factors II, IX, and X, and antithrombin III. Both activated and unactivated concentrates contained factors VIIa and IXa, with the highest levels in the activated concentrates. Factors VIIa and IXa were detected in patient plasma after infusion of unactivated concentrates. Increases of 3-5--fold in factors II and X were also found. Major decreases in antithrombin III activity, but not antigen, were found after unactivated concentrate therapy. This functional decrease may be due to the presence of inactive antithrombin III complexes, since a decreased mobility of antithrombin III antigen by crossed immunoelectrophoresis was found. These studies support the possible importance of factors IXa and VIIa as therapeutic agents and suggest that a transient functional deficiency in antithrombin III may be involved in the thrombotic potential of the concentrates.

Antithrombin III↗
PubMed1989

Production of human factor IX in animals by genetically modified skin fibroblasts: potential therapy for hemophilia B.

Inherited diseases might be treated by introducing normal genes into a patient's somatic tissues to correct the genetic defects. In the case of hemophilia resulting from a missing clotting factor, the required gene could be introduced into any cell as long as active factor reached the circulation. We previously showed that retroviral vectors can efficiently transfer genes into normal skin fibroblasts and that the infected cells can produce high levels of a therapeutic product in vitro. In the current study, we examined the ability of skin fibroblasts to secrete active clotting factor after infection with different retroviral vectors encoding human clotting factor IX. Normal human fibroblasts infected with one vector secreted greater than 3 micrograms factor IX/10(6) cells/24 h. Of this protein, greater than 70% was structurally and functionally indistinguishable from human factor IX derived from normal plasma. This suggests that infected autologous fibroblasts might provide therapeutic levels of factor IX if transplanted into patients suffering from hemophilia B. By transplanting normal diploid fibroblasts infected with the factor IX vectors, we showed that human factor IX can be produced and is circulated at readily detectable levels in rats and mice.

Animals↗
PubMed1994

Analysis of potential functional regions using local degeneracy: mutational hotspots in human factor IX are localized in high-degeneracy regions.

To study the relationship between the potential functional regions with the primary amino acid sequence, we introduced a new factor termed local degeneracy to analyze the degree of the degeneracy in a given segment of the protein. Using the defined local degeneracy, we have analyzed the human coagulation Factor IX (Christmas factor) which is an essential component of the clotting cascade. The mutational hotspots in Factor IX are primarily distributed in the high-degeneracy regions, suggesting a direct correlation of the functional regions with high degree of the degeneracy. This method may be useful to predict and to evaluate potential functional domains of a protein.

Animals↗
PubMed1989

Inhibitors of 2-ketoglutarate-dependent dioxygenases block aspartyl beta-hydroxylation of recombinant human factor IX in several mammalian expression systems.

While a role has been ascribed to the gamma-carboxyglutamate (Gla) residues in vitamin K-dependent coagulation proteins and the enzyme catalyzing this posttranslational modification has been identified and partially characterized, both the functional significance of a second posttranslationally synthesized amino acid found in these proteins, beta-hydroxyaspartate (Hya), and the aspartyl beta-hydroxylating enzyme remain to be determined. We now report that inhibitors of 2-ketoglutarate-dependent dioxygenases, such as dipyridyl, o-phenanthroline, and pyridine 2,4-dicarboxylate, block hydroxylation of Asp64 in recombinant factor IX molecules produced in three different mammalian expression systems. This hydroxylation was not inhibited by the specific copper chelators 2,9-dimethylphenanthroline or D-penicillamine. The Gla levels in these proteins were unaffected by these compounds and demonstrate that carboxylation proceeds independently of hydroxylation. Using these Hya-deficient recombinant factor IX molecules we demonstrate that this residue does not play a significant role in factor IX binding to endothelial cells under equilibrium conditions. From additional binding studies we have concluded that the Gla domain of factor IX is a major cell binding domain of factor IX. Furthermore, in contrast to studies demonstrating a marked loss of one-stage clotting activity in recombinant factors IX following site-directed mutations of Asp64 to neutral or basic residues (Rees, D. J. G., Jones, I. M., Handford, P. A., Walter, S. J., Esnouf, M. P., Smith, K. J., and Brownlee, G. J. (1988) EMBO J. 7, 2053-2061), we have not found a decrease of one-stage clotting activity with Hya-deficient factor IX. Hya-deficient proteins produced in this manner may prove to be more appropriate to elucidate the function of Hya than those produced by site-directed mutagenesis.

2,2'-Dipyridyl↗
PubMed2004

A retrospective survey on the safety of Replenine, a high-purity factor IX concentrate.

PURPOSE: To assess the safety of a plasma-derived highly purified factor IX concentrate (Replenine) in routine clinical use. METHODS: Following guidelines entitled Safety Assessment of Marketed Medicines (SAMM), safety data were collected in the UK by retrospective review of the hospital notes of 114 patients who received an estimated 14.8 million IU of Replenine. Included were 40 patients undergoing 44 surgical procedures or dental extractions [corrected]. RESULTS: The study detected a total of nine adverse events (AEs), four of which were possibly product-related, four that were unrelated to the product and one whose causality was unknown. None of these cases had been notified to the manufacturer through conventional spontaneous reporting procedures. One patient was switched from Replenine because of infusion site irritation, but no unexpected adverse reactions were noted. There were no reports of virus transmission or new factor IX inhibitor development. The mean factor IX recovery value was 1.44 IU/dl per IU/kg (95%CI: 1.31-1.57 IU/dl per IU/kg). CONCLUSIONS: The study was a practical application of the SAMM guidelines to the collection of pharmacovigilance data on patients with Haemophilia B. Replenine is well tolerated in routine clinical practice.

Adult↗
PubMed2003

Continuous intravenous infusion of a plasma-derived factor IX concentrate (Mononine) in haemophilia B.

This prospective, multicentre, open-label study evaluated the efficacy and safety of a plasma-derived factor IX concentrate [Mononine, Coagulation Factor IX (Human) Monoclonal Antibody Purified] administered by continuous intravenous (CIV) infusion to patients with haemophilia B. Admission criteria included documented diagnosis of haemophilia B (mild, moderate, or severe). Twenty-eight patients (25 surgery, two trauma, one severe spontaneous haemorrhage) were enrolled to receive a therapeutic bolus dose followed by CIV infusion of factor IX (FIX) to maintain FIX:C plasma levels of 0.4-1.0 IU mL(-1) (i.e. 40-100%). A median intravenous bolus dose of 54.2 IU kg(-1) FIX was administered to a subset of 13 non-emergency patients 7-21 days prior to CIV infusion to determine pharmacokinetic parameters in order to guide the dosing for CIV. For treatment, a bolus injection (median FIX dose; 89.6 IU kg(-1)) (range, 12.4-108.3), followed by a median total CIV infusion dose of 396.4 IU kg(-1) (range, 44.9-785.5) was administered at a median rate of 3.84 IU kg(-1) h(-1) (range, 1.74-7.33) for 107.17 h (range, 31.75-144). Twenty-four patients completed 72-120 h of FIX CIV infusion. Overall, 'excellent' (i.e. achievement of normal haemostasis) efficacy was reported in 23 of 24 (96%) evaluable patients, and 'good' (i.e. slight oozing) efficacy was reported in one (4%) patient. Median FIX:C was 72-86% for all patients receiving FIX by CIV on all days. Nine patients reported 13 adverse events that were possibly related to study medication but were not deemed serious by the investigator and were mainly because of local irritation at the infusion site. FIX CIV infusion therapy is safe and effective in the treatment of haemophilia B patients undergoing surgery, exposed to trauma, or experiencing severe spontaneous haemorrhage.

Adolescent↗
PubMed1991

Perspectives on the use of factor IX complex concentrates in the treatment of bleeding in persons with acquired factor VIII inhibition.

In contrast to the type of bleeding encountered in congenital hemophilia with inhibitors, the diathesis toward bleeding exhibited by patients with spontaneously acquired factor VIII (FVIII) inhibitors often is severe and life threatening. Large hematomas and retropharyngeal or central nervous system hemorrhage may appear suddenly. Thus, a high premium is placed on rapid therapeutic intervention. Several treatment options are at the physician's disposal. The role of factor IX (FIX) complex concentrates, both standard and purposely activated, is discussed. The FIX products are also known as prothrombin complex concentrates (PCCs). Prudent choice of any treatment modality requires weighing its benefits and shortcomings. Advantages of PCCs--particularly the activated products--include availability, ease of reconstitution and administration, and at least partial efficacy; control of bleeding episodes can be achieved with PCCs in many (but not all) instances. One salient disadvantage of therapy with FIX complex concentrates is that they are not subjected to such rigorous viral-attenuation processes as are most of the currently marketed FVIII products. Therefore, a small but definite risk of infection with hepatitis B or C (HBV, HCV) remains. An assay that detects antibodies against HCV has been licensed and is being used to screen blood donors. Nevertheless, up to the present time the U.S. Food and Drug Administration (FDA) has ruled that HCV screening of plasmapheresis donors should not be performed for plasma collections destined to be pooled for fractionation and that units of HCV-positive source plasma (e.g., that provided by American Red Cross donors) found to be HCV positive be sent for fractionation. The starting plasma from which FIX complex concentrates and human FVIII concentrates are made thus contains some HCV and may also contain some HBV. Because nonhemophiliacs with acquired antibodies against FVIII are unlikely to have had prior exposure to blood products and are unlikely to have been vaccinated against HBV, they are at risk of viral hepatitis and its sequelae when treated with FIX complex concentrates. Furthermore, therapy with FIX complex concentrates is not always effective in controlling bleeding in persons with FVIII inhibitors, its mechanism of action in bypassing the need for FVIII remains unclear, very large doses are required, and it has an attendant risk of several adverse effects when used in large, repeated doses. These include disseminated intravascular coagulation, thromboembolism, and acute myocardial infarction. Thus, FIX complex concentrates may play a useful role in the treatment of bleeding in nonhemophiliacs with acquired inhibitors against FVIII, but one must carefully consider their disadvantages profile.(ABSTRACT TRUNCATED AT 400 WORDS)

Autoantibodies↗
PubMedDate not supplied

[Comparison of factor VIII:C and factor IX sensitivity of different commercial APTT reagents for canine plasma].

In the present study, six commercial reagents for the determination of the activated partial thromboplastin time (APTT) were compared with respect to their factor VIII:C and factor IX sensitivity for measurements of canine plasma. For this purpose, plasma with different levels of factor VIII:C or factor XI activity (100, 80, 70, 60, 50, 40, 30, 20, 15, and 10% [factor VIII:C: additionally 5%]) was prepared by mixing pool plasma with plasma of dogs with haemophilia A or B. Double measurements of three different sample mixtures were carried out for each activity level. The sensitivity of the reagents was measured first based on the ratios of the coagulation time to the 100% values. In addition, the single factor activity (F VIII:C/IX(X0.975)), whose accompanying APTT corresponded to the upper limit of the reference range (97.5%-quantile, n = 50) of the respective reagent, was determined graphically. The APTT reflected a decrease of factor IX activity generally more sensitive than a reduction of factor IX activity of an identical degree. Based on ratios distant differences respecting factor VIII:C and factor IX sensitivity were found between different reagents using two way analysis of variance (p < 0.05). Significant differences between various reagents were also found with respect to the F VIII:C(X0.975) and the F IX(X0.975). These corresponded to values between 27 and 50% or 32 and 64%, respectively, dependent on the reagent. As a result, the more sensitive reagents fulfilled the demands on the sensitivity of APTT in humans. Based on the latter criterion the highest sensitivity for both factors was found for the same reagent (Pathromtin) consisting of kaolin as a contact activator and human placental phospholipid. Respecting all proofed reagents, however, no relation was found between contact activator and single factor sensitivity.

Animals↗
PubMed1990

Functional characterization of the 5'-regulatory region of human factor IX gene.

Functional characterization of the 5'-regulatory region of the human factor IX gene was carried out by a series of gene dissection analyses. The region extending from -175 to -274 of the 5' end flanking sequence is required for the expression of this gene. Within this region, sequence elements AGCCACT at -238 and TCAAAT at -187 were assigned as the functional CAAT box and TATA box, respectively. The transcription initiation site was found to be at -150 for the factor IX chloramphenicol acetyltransferase chimeric gene. A negative regulatory (silencer) activity was located in the region spanning from 1.4 to 1.7 kilobases upstream of the promoter region. This region contains a short sequence element (ATCCTCTCC) known to have such activity. A strong promoter on the opposite strand was also located about 500 base pairs upstream of the promoter. The expression of factor IX gene was highly liver specific, as assessed by Northern blot analysis. Short sequence elements (TGGACC and CTTTGGACT) homologous to the known liver-specific elements were located in the vicinity of the defined promoter region.

Base Sequence↗
PubMed1989

Extragenic factor IX gene RFLP is useful for detecting carriers of Japanese hemophilia B.

Seventy-eight X chromosomes from 25 normal Japanese subjects and 22 family members with hemophilia B (coagulation factor IX deficiency) were examined with an extragenic factor IX DNA probe, pX58dIIIc at DXS99 locus. In contrast to the previously described nonpolymorphic RFLPs in the factor IX gene, DXS99 locus RFLP produced by SacI digestion was detected among those Japanese subjects with allelic frequencies of 0.48 and 0.52. The estimated heterozygosity rate of this extragenic RFLP among Japanese females was about 50%. The study of hemophilia B family members showed that DXS99 locus RFLP was informative in 9 out of 13 families tested (69.2%). No recombination events between the factor IX gene locus (F9) and DXS99 locus have been noted among nine families analyzed. DXS99 SacI RFLP is a useful gene indicator of carrier-ship of hemophilia B.

Factor IX↗
PubMed1995

Concomitant treatment with factor IX concentrates and antifibrinolytics in hemophilia B.

Concomitant use of the monoclonal antibody-purified factor IX concentrate (Mononine, Armour Pharmaceutical Company, Collegeville, Pa.) and two antifibrinolytic agents, epsilon-aminocaproic acid (EACA; Amicar, Immunex, Seattle, Wash.) or tranexamic acid (AMCA; Cyklokapron, Kabi Pharmacia, Piscataway, N.J.) was examined for safety and efficacy in patients with hemophilia B. In a retrospective review of 19 patients treated with monoclonal antibody-purified factor IX and EACA on 35 occasions, bleeding was successfully controlled and no instances of clinical thrombotic complications were reported; one instance of urticaria resolved without additional treatment. The use of EACA or AMCA in combination with monoclonal antibody-purified factor IX was also examined prospectively in a study of 9 patients. Bleeding was effectively controlled and no thrombotic events were detected clinically with either antifibrinolytic agent. No significant changes in hematocrit or hemoglobin were detected, and there was no evidence of thrombosis as evaluated clinically and by sensitive molecular markers. It was concluded from both the retrospective and prospective data that monoclonal antibody-purified factor IX concentrate in combination with an antifibrinolytic agent does not activate the coagulation cascade and is a safe and effective treatment for prevention and control of oral bleeding in hemophilia B patients.

Aminocaproates↗