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At least 865 records · Page 48Linked to original sources
PubMed1988

An insertion within the factor IX gene: hemophilia BEl Salvador.

A patient with moderate to severe hemophilia B has been found to have a large insertion within his factor IX gene. The site of insertion is located in a DNA segment of approximately 0.8 kb between exon IV and an EcoRI site within intron D. The size of the DNA insertion is approximately 6 kb, and it contains at least two TaqI sites, two EcoRI sites, and one HindIII site. The insert probably originates from outside the FIX gene and does not represent an internal duplication. We propose that this abnormal FIX gene be called FIX El Salvador in recognition of the birthplace of the patient.

Adolescent↗
PubMed1986

Neurofibromatosis, factor IX deficiency, and rhabdomyosarcoma.

A paratesticular rhabdomyosarcoma occurred in a child with factor IX deficiency and neurofibromatosis, illustrating the need to consider carefully the various etiologic possibilities of a soft-tissue mass in a child with neurofibromatosis and/or a bleeding disorder.

Diseases in Twins↗
PubMed1986

Immunopurification of human coagulation factor IX using monoclonal antibodies.

This study examines the suitability of four recently characterised monoclonal antibodies (MAbs) for the immunoaffinity purification of human coagulation factor IX (FIX) from plasma concentrates. Initial studies using 125I-FIX indicated that appreciable amounts of bound FIX could be eluted from immobilised MAbs with 0.2 M glycine, 50% ethanediol pH 10 (buffer N). Further studies with FIX concentrates showed that buffer N eluted FIX without compromising the activity of the zymogen. Although FIX was eluted from all four MAbs with this buffer, the best yield (82%) was obtained with MAb ESN-3. ESN-3 bound 40 to 60 iu FIX per mg MAb when immobilised on Sepharose 4B. After washing, column elution with buffer N yielded FIX at 100-200 iu/mg. The purity of the product was confirmed by sodium-dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and by Western blotting. The product contained no detectable mouse IgG (less than 3%) and less than 1% FII, X, or protein C.

Antibodies, Monoclonal↗
PubMed2003

Neonatal gene transfer with a retroviral vector results in tolerance to human factor IX in mice and dogs.

The effect of neonatal gene transfer on antibody formation was determined using a retroviral vector (RV) expressing human factor IX (hFIX). Normal mice from different strains injected intravenously with RV as newborns achieved therapeutic levels of hFIX without antibody production and were tolerant as adults to challenge with hFIX. Neonatal hemophilia B mice that received different amounts of RV achieved stable and dose-related expression of hFIX without anti-hFIX antibody formation. After protein challenge, antibody formation was markedly reduced for animals that expressed hFIX at levels higher than 14 ng/mL (0.3% of normal). However, antibodies developed for animals that received the lowest dose of RV and expressed hFIX at approximately 2 ng/mL before protein challenge. In dogs, neonatal injection of a high dose of RV resulted in 500 ng/mL hFIX in plasma without antibody formation. We conclude that neonatal gene transfer with RV does not induce antibody responses to hFIX in mice or dogs and that mice achieving levels greater than 3 x 10-10 M hFIX are usually tolerant to protein injection as adults. Low-dose gene therapy or frequent protein injections in the neonatal period might induce tolerance to subsequent injections of protein with a low risk for adverse effects.

Animals↗
PubMed2002

Sustained phenotypic correction of hemophilia B dogs with a factor IX null mutation by liver-directed gene therapy.

Hemophilia B is an X-linked coagulopathy caused by absence of functional coagulation factor IX (FIX). Using adeno-associated virus (AAV)-mediated, liver-directed gene therapy, we achieved long-term (> 17 months) substantial correction of canine hemophilia B in 3 of 4 animals, including 2 dogs with an FIX null mutation. This was accomplished with a comparatively low dose of 1 x 10(12) vector genomes/kg. Canine FIX (cFIX) levels rose to 5% to 12% of normal, high enough to result in nearly complete phenotypic correction of the disease. Activated clotting times and whole blood clotting times were normalized, activated partial thromboplastin times were substantially reduced, and anti-cFIX was not detected. The fourth animal, also a null mutation dog, showed transient expression (4 weeks), but subsequently developed neutralizing anti-cFIX (inhibitor). Previous work in the canine null mutation model has invariably resulted in inhibitor formation following treatment by either gene or protein replacement therapies. This study demonstrates that hepatic AAV gene transfer can result in sustained therapeutic expression in a large animal model characterized by increased risk of a neutralizing anti-FIX response.

Animals↗
PubMed2004

The safety and efficacy of recombinant human blood coagulation factor IX in previously untreated patients with severe or moderately severe hemophilia B.

This international clinical trial evaluated the safety and efficacy of recombinant factor IX (rFIX) in previously untreated patients (PUPs) with severe or moderately severe hemophilia B (FIX activity, < or = 3 IU/dL). Sixty-three PUPs aged younger than 1 month to 14 years received rFIX (median treatment duration, 37 months; range, 4-64 months). Mean rFIX recovery (0.68 +/- 0.27 IU/dL per IU/kg) remained constant over 5 years and was similar in infants (1 month to < 2 years) and children (2 to < 12 years). Fifty-four PUPs used rFIX (median dose, 62.7 IU/kg per infusion; range, 8.2-292 IU/kg) to treat 997 hemorrhages. Bleeding was well controlled, with 75% of hemorrhages requiring only one rFIX infusion. Response to rFIX was "excellent" or "good" in 94% of cases. Effective hemostasis was achieved in 32 PUPs receiving rFIX for routine prophylaxis, with 91% of prophylaxis responses rated "excellent." rFIX administered for 30 surgical procedures in 23 PUPs achieved hemostasis for all rated procedures. Five patients experienced allergic-type manifestations, including 2 (3%) patients who developed FIX inhibitors (both > 5 BU/dL). rFIX was well tolerated, with no associated thrombotic events or evidence of viral transmission. These data indicate that rFIX is a safe and effective treatment for PUPs with hemophilia B.

Adolescent↗
PubMed1995

Liposome-encapsulated DNA-mediated gene transfer and synthesis of human factor IX in mice.

Hemophilia B is an X-chromosome-linked recessive disorder that is caused by a deficiency of biologically active clotting factor IX (FIX). In this work, liposomes (Lip) were used for non-viral, in vivo gene transfer of the human FIX gene into mouse organs. Plasmid DNA, containing the human FIX cDNA under the control of the Moloney murine leukemia virus (MoMLV) long terminal repeat (LTR), was encapsulated in 1-2-microns multilamellar Lip composed of egg phosphatidylcholine (EPC). The percentage of Lip-associated DNA was 47%, and 72% of the Lip DNA was protected from DNase I digestion. The Lip-encapsulated (Len) DNA was injected intravenously into Balb/c mice, and at various times post-injection, various tissues were examined for the presence of the exogenous DNA. Plasmid DNA was detected by Southern blot analysis mainly in the liver and spleen, but small amounts were also detected in the lungs, heart and kidneys. The plasmid DNA was retained in mouse liver cells for at least 7 days post-injection, and remained in an episomal state. The levels of human FIX protein in the mouse plasma were 190-650 pg per ml for 2 to 7 days post-injection. Treatment of mice with chloroquine (Cq) and colchicine (Cc) prior to Lip injection significantly increased the amount of plasmid DNA found in the liver cells, as well as the level of human FIX in the plasma. These results demonstrate the potential use of Len DNA for gene transfer into liver and spleen, and for gene therapy of inherited and acquired disorders.

Animals↗
PubMed2006

Fatal hemorrhagic diathesis associated with mild factor IX deficiency in pl/J mice.

Surgical implantation of devices into the abdomen of PL/J mice was associated with fatal hemorrhage at 9 to 11 d after surgery. Coagulation profiles were evaluated to determine the underlying cause of this effect. The mean activated partial thromboplastin time (aPTT) of untreated PL/J mice was significantly higher than that of BALB/cByJ and C57BL/6J strains. The addition of human plasmas deficient in factors VIII, XI, or XII, prekallikrein, or high molecular-weight kininogen corrected the elevated aPTT of PL/J mice, but correction did not occur when factor IX-deficient human plasma was added. When compared to an assigned factor IX activity of 100% for pooled plasma from BALB/cByJ mice, C57BL/6J and PL/J mice revealed percent activities of 67% and 16%, respectively. PL/J mice could represent a new model for the study of pathogenesis and therapy of mild factor IX deficiency that is expressed and becomes clinically apparent secondary to major surgery.

Animals↗
PubMed1981

The use of factor IX concentrates in man: a 9-year experience of Scottish concentrates in the South-East of Scotland.

During the last 9 years, two factor IX concentrates produced in Scotland, PPSB and DEFIX, have been used for the treatment of haemophilia B and acquired coagulation disorders, including those due to liver disease, coumarin therapy, neonatal immaturity and post-operative bleeding. During the period of study 112 batches of DEFIX and 40 batches of PPSB were used in the Edinburgh and South-East Scotland Region. Data were analysed from 575 non-haemophilic patients, receiving 968 treatment episodes, as well as 24 haemophiliacs. Serial coagulation studies and analysis of retrospective data showed that both concentrates corrected the coagulation deficiencies in all the above patient groups; in no case was there any evidence of intravascular coagulation resulting from concentrate infusion.

Blood Coagulation Disorders↗
PubMed2003

Complete and sustained phenotypic correction of hemophilia B in mice following hepatic gene transfer of a high-expressing human factor IX plasmid.

Therapeutic correction of hemophilia B was achieved by rapid infusion of a large-volume solution containing a high-expressing human factor IX (hFIX) plasmid into the tail vein of hemophilia B mice. hFIX circulated at therapeutic levels (1-5 micro g mL-1) in all animals for more than 1 year as determined by both species-specific antigen assay and an activated partial thromboplastin time (APTT)-based clotting assay. There was acute, transient hepatic tissue damage by the infusion procedure and no significant inhibitory anti-hFIX antibodies developed. No bleeding episode was observed during or after treatment. Immunohistochemical studies indicated that the hFIX gene was exclusively expressed in hepatocytes, and that transduced cells had readily detectable hFIX protein at 4 h postinfusion, and stainable protein persisted for up to 1 year. Repeated infusions of hFIX plasmids boosted the hFIX expression to higher levels. These results demonstrate that hemophilia B can be treated by gene transfer of naked hFIX plasmids.

Animals↗
PubMed1994

Removal and inactivation of enveloped and non-enveloped viruses during the purification of a high-purity factor IX by metal chelate affinity chromatography.

Virus reduction during the copper chelate affinity chromatography stage used during the purification of a new high-purity factor IX (BPLs 9MC) has been investigated. Virus reduction for the enveloped virus Sindbis was 6.5 log, a value which included approximately 2 log of inactivation due to the use of an acidic wash buffer (pH 4.4) during chromatography. In the case of the non-enveloped hepatitis-A-like poliovirus, which is acid-resistant, the virus reduction value was 4.0 log and was exclusively due to physical virus removal during the chromatographic process.

Chelating Agents↗
PubMed2002

Concentrates containing factor IX could improve haemostasis under conditions of thrombocytopenia: studies in an in vitro model.

BACKGROUND AND OBJECTIVES: We explored the effect on haemostasis of different factor IX (FIX) concentrates under thrombocytopenic conditions using an in vitro perfusion technique. MATERIALS AND METHODS: A moderate experimental thrombocytopenia (25 000-30 000 platelets/microl) was induced by means of a filtration procedure in blood anticoagulated with low-molecular-weight heparin. The effects of three different FIX concentrates - a prothrombin complex concentrate (PCC), an intermediate-purity concentrate (FIX/X), and a high-purity concentrate (HPFIX) - on platelet deposition and fibrin formation on subendothelium were assessed at two different shear rates (600/second and 1200/second). Activation of the coagulation system was monitored through assessment of prothrombin activation fragment 1 + 2 (F1 + 2). RESULTS: Fibrin deposition increased after addition of FIX concentrates, but only showed a significant increase in experiments performed after incubation of PCC at the lower shear rate (600/second) (64.25 +/- 9.61% vs. control 31.22 +/- 8.02%; P < 0.05). Addition of FIX concentrates caused a small increase in the percentage of platelet deposition and area of those aggregates. These differences reached levels of statistical significance in the presence of FIX/X and HPFIX in experiments performed at a shear rate of 600/second. F1 + 2 baseline values in anticoagulated thrombocytopenic blood were 1.15 +/- 0.13 nm and reached levels of 2.49 +/- 0.24 and 3.60 +/- 0.33 nm at shear rates of 600 and 1200/second, respectively. Increments in F1 + 2 observed after addition of different FIX concentrates always remained in the previous ranges. CONCLUSIONS: Data from the present study provide experimental support favouring the concept that FIX concentrates containing other activated factors could improve haemostasis under conditions of moderate thrombocytopenia.

Animals↗
PubMed1994

Location and rapid analysis of the intragenic BamHI polymorphic site of the factor IX gene.

We report the precise location and a polymerase chain reaction (PCR)-based method for the analysis of the intragenic BamHI polymorphism of the factor IX (FIX) gene. After screening DNA samples from the Brazilian Black population by a selective amplification of a segment of the FIX gene containing entire exon 2, intron 2, and exon 3 followed by digestion of PCR products with BamHI, we were able to identify individuals presenting the polymorphic BamHI site. By DNA sequencing of selected samples, the dimorphic base was located at nucleotide number 6575 (intron 2). The PCR method outlined here allows rapid and easy analysis of this polymorphism. Its application may be particularly useful for carrier detection and prenatal diagnosis of hemophilia B in the Black population, thus far the only one that has been shown to be polymorphic for this site. Because of its apparent restrictive pattern it may also be used in combination with other markers for estimates of racial admixture in mixed populations in which the Black population is present (as is the case for most countries in the American continent).

Base Sequence↗
PubMed1997

Construction of mammary gland-specific expression vectors for human clotting factor IX and its secretory expression in goat milk.

Two expression vectors comprised of mouse matrix attachment regions (MARs), bovine beta-casein gene sequence, human factor IX (hFIX) minigene, and cDNA, pMCIXm and pMCIX, were constructed for the purpose of a mammary gland bioreactor. A secretory expression system of hFIX protein in milk was made using stearylamine (SA) liposome to transfect plasmid DNA directly into the mammary gland lobule of a lactating goat. The highest production of hFIX in goat milk was 13.7 ng/ml 3 days after transfection, and the hFIX production in the goat mammary gland transfected with pMCIXm containing hFIX minigene was obviously higher than that transfected with pMCIX containing hFIX cDNA. Activity immuno-analysis and the barium citrate absorption method showed that > 90% hFIX protein in milk appeared to be a gamma-glycosylated and biological activity. This result confirmed the validity of the constructed vectors for further transgenic study, and this assay could also find its success in the evaluation of a foreign gene expression and secretion in the milk as a rapid detection system using liposome to transfect DNA directly into the goat mammary gland.

Animals↗