Frequency of inhibitors in haemophiliacs.
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Antibodies↗
Biomedical subjects
N Ciavarella
Publications and source records attributed to N Ciavarella.
Immune status of asymptomatic HIV-infected hemophiliacs: randomized, prospective, two-year comparison of treatment with a high-purity or an intermediate-purity factor VIII concentrate.
It has been postulated that high-purity factor VIII (FVIII) concentrates, since they contain less alloantigenic proteins than intermediate-purity concentrates, might cause lesser deterioration of the immune systems of hemophilic patients infected with the human immunodeficiency virus (HIV). To evaluate this hypothesis, we have prospectively compared T-lymphocytes subsets and delayed hypersensitivity reactions to skin tests in 17 asymptomatic HIV-positive hemophiliacs randomly assigned to continue treatment with an intermediate-purity concentrate with those of 16 hemophiliacs changed to a high-purity concentrate. For both groups, during the 24-month follow-up period CD4 cell counts showed similar rates of fall from baseline values. There was also no difference in the number of patients anergic to skin tests. Three patients treated with the intermediate purity concentrate and one treated with the high-purity concentrate developed symptoms of HIV infection. On the whole, no striking benefit is conferred to the immune status of asymptomatic HIV-positive hemophiliacs by using this high-purity concentrate for 2 years.
Adolescent↗
Characterization of the pseudogenic and genic homologous regions of von Willebrand factor.
The homologous pseudogenic and genic regions of von Willebrand factor (vWF) were studied in DNA from a patient with homozygous deletion of vWF genes and compared with a normal control. This analysis indicates informative restriction patterns for the investigation of restriction fragment length polymorphisms (RFLPs) and gene lesions, and for molecular cloning. A useful new genic XbaI RFLP was found and characterized. A large BgIII fragment of the pseudogenic region was cloned and mapped, and single sequences (9 kb) were used as probes. Corresponding genic and pseudogenic fragments, which contain exons 23-28, and specific restriction patterns were identified, including a new polymorphic TaqI site that was mapped in the gene. A cloned fragment contains the 5' boundary of the pseudogene and recognizes an additional and unknown homologous sequence in the genome. The chromosomal localization of the vWF pseudogene and of the breakpoint cluster region (BCR) gene were compared by 'in situ' hybridization: overlapping patterns were detected. The cloning, characterization and mapping of the pseudogenic region improves the analysis of this portion of chromosome 22 affected by several somatic and constitutional alterations, and also of the corresponding genic region on chromosome 12.
Base Sequence↗
Low risk for hepatitis C in hemophiliacs given a high-purity, pasteurized factor VIII concentrate. International Study Group.
STUDY OBJECTIVE: To assess whether the hepatitis B virus (HBV), the hepatitis C virus (HCV), and the human immunodeficiency virus (HIV) are transmitted to hemophiliacs by a high-purity factor VIII concentrate in which the method of virus inactivation is pasteurization. DESIGN: Hepatitis B virus markers, the antibody to HCV (anti-HCV), the antibody to HIV (anti-HIV), and aminotransferases were measured on serum samples collected before the first concentrate infusion and at regular time intervals thereafter. SETTING: Seventeen hemophilia centers in Italy, the Federal Republic of Germany, Belgium, Austria, and the Democratic Republic of Germany. PATIENTS: Twenty-nine patients with hemophilia A who had not received a previous transfusion with blood products and who had normal alanine and aspartate aminotransferases (ALT and AST) were included in the final analysis. MEASUREMENTS AND MAIN RESULTS: No patient became positive for anti-HCV or anti-HIV or developed sustained increases in aminotransferase levels. Similarly, none of the 15 unvaccinated patients developed markers of HBV infection. CONCLUSION: This prospective study conducted in previously untransfused hemophiliacs highly susceptible to developing post-transfusion hepatitis shows that a large-pool clotting factor concentrate treated with pasteurization carries a low risk for transmitting HCV, the major causative agent of post-transfusion hepatitis.
Adolescent↗
Heterogeneous phenotypes of platelet and plasma von Willebrand factor in obligatory heterozygotes for severe von Willebrand disease.
To characterize the heterogeneity of severe (type III) von Willebrand disease (vWD), plasma and platelet von Willebrand factor antigen (vWF:Ag) and ristocetin cofactor activity (Ricof) were measured in 28 obligatory heterozygotes (ie, parents or children of probands from 15 different kindreds with severe vWD). On the average, heterozygotes had low levels of vWF in both platelets and plasma. There was, however, considerable heterogeneity, with four distinct patterns. Eleven heterozygotes had concordant reduction of vWF:Ag and Ricof in both plasma and platelets; five had low levels of vWF:Ag and Ricof in plasma contrasting with normal levels in platelets; eight had a peculiar pattern, the reverse of the above (ie, low levels in platelets and normal levels in plasma); and in one, both vWF measurements were normal in plasma and platelets. These patterns were genetically determined: they were consistent in four couples of consanguineous heterozygotes and in two couples carrying the same gene deletion. Only the remaining three heterozygotes had no clearly identifiable pattern. Other findings of this study were that although most of the heterozygotes had normal bleeding times, the 7 of 28 who had prolonged bleeding times had concordantly low levels of vWF measurements in both plasma and platelets. In conclusion, this large series of obligatory heterozygotes provides evidence for phenotypic and genotypic heterogeneity of severe vWD.
Bleeding Time↗
Evaluation of factor VIII pharmacokinetics in hemophilia-A subjects undergoing surgery and description of a nomogram for dosing calculations.
The pharmacokinetics of factor VIII were studied in a series of 20 hemophilia-A patients undergoing surgery. Regardless of the type of operation, elimination of factor VIII was shown to be increased only in ten cases (50%) during the post-operative period. In this subgroup of patients, factor VIII half-life, measured immediately after surgery, was considerably shorter (mean = 9.6 hr, n = 10) than that determined in the same individual during the late operative period (mean = 17.8 hr, n = 10). These findings indicate that identification of patients with increased postoperative consumption of factor VIII can be of value in reducing the risk of hemorrhage in these subjects and in exposing other subjects with no postoperative increase in factor VIII clearance to less of the deficient factor. Data from 20 subjects were analyzed to construct a nomogram allowing individualized prediction of factor VIII dosing requirements. The nomogram, which is based on the "single point after a single dose" method, uses a value of factor VIII concentration measured at 10 hr after preoperative loading dose to predict the regimen producing the desired average steady-state concentration of factor VIII (30, 60, or 90 units/dl).
Adolescent↗
Long-term immunogenicity of a plasma-derived hepatitis B vaccine in HIV seropositive and HIV seronegative hemophiliacs.
Short-term studies indicate that hepatitis B vaccines are safe and satisfactorily immunogenic in hemophiliacs. The duration of immunity in these immunocompromised patients, however, is not known. To determine this, we studied 78 hemophiliacs prospectively 2, 3, and 4 years after the initial vaccination with a plasma-derived vaccine given as three monthly injections followed by a fourth booster injection at month 14. The duration of immunity clearly depended on whether the patients were infected with the human immunodeficiency virus (HIV). In HIV seronegative hemophiliacs (n = 67), there was a progressive decline in titers of antibody to the hepatitis B surface antigen (anti-HBs), but antibody was still detectable 4 years later in all of them. From the curves of decline of antibody titers, it appears that there is no need to revaccinate patients for at least 5 to 6 years. The HIV seropositive hemophiliacs (n = 11) not only started from much lower anti-HBs titers, but 5 of 11 lost anti-HBs. None of the 45 patients treated with concentrates during the postvaccination period developed serologic signs of hepatitis B, even though 6 of them had come into contact with live or inactivated hepatitis B virus as shown by the occurrence of spontaneous anamnestic antibody responses. This vaccine and schedule of vaccination afford a prolonged duration of immunity in HIV seronegative hemophiliacs, but HIV seropositive hemophiliacs have a risk of losing immunity early.
Adolescent↗
Immunogenicity of a recombinant hepatitis B vaccine in hemophiliacs.
Yeast-recombinant vaccines against hepatitis B virus (HBV) are now available, but there is no information about whether or not they are immunogenic in patients with hemophilia and other congenital bleeding disorders. Twenty micrograms of a recombinant vaccine expressing the adw serotype of the hepatitis B surface antigen (HBsAg) were given to 41 patients negative for HBV markers and again after 1 and 6 months. Ten percent of the vaccinees had anti-hepatitis B surface antibody (anti-HBs) responses, with titers of 10 mIU/ml or more, 1 month after the first dose of vaccine. The percentage of anti-HBs-positive patients increased to 54% after the second dose and to 98% after the third dose, with only one non-responder. Hence, the recombinant vaccine was immunogenic, with percentages of seroconversion and anti-HBs titers similar to those achieved with plasma-derived vaccines.
Adolescent↗
Aggregation of human peripheral blood mononuclear cells by calcium ionophore A23187. Comparison with the aggregation of platelets and defective response in Glanzmann's thrombasthenia.
Following exposure to calcium ionophore A23187, washed peripheral blood mononuclear cells (MNC) aggregated and formed thromboxane, like platelets. However, while aspirin strongly inhibited platelet aggregation and thromboxane formation, it had a little effect on the aggregation of MNC. In about 50% of the samples studied, aggregation of MNC was associated with the secretion of ATP. However studies in which exogenous ATP or ADP were used, suggested that the aggregation of MNC is independent of the secretion of nucleotides. MNC from 2 thrombasthenic patients failed to aggregate and bound 9-10 fold less radiolabelled fibrinogen than those from normals when challenged with A23187. However, fibrinogen, which plays a major role in the aggregation of platelets, did not appear to be involved in the aggregation of MNC. A differing behavior of these two types of cells was also found when the effect of plasma was studied on the aggregation response to A23187. Indeed, citrated plasma greatly enhanced the aggregation of platelets while it suppressed the response to MNC. This inhibitory effect of plasma was not detected when heparinized plasma was substituted for citrated plasma. We conclude that the aggregation of MNC in response to A23187 does not involve basic events known to play a major role in the aggregation of platelets. The response to A23187 may be an important probe for understanding basic mechanisms and pathophysiological significance of the aggregation of MNC.
Adult↗
Homozygous and heterozygous deletions of the von Willebrand factor gene in patients and carriers of severe von Willebrand disease.
Severe von Willebrand disease is characterized by undetectable or trace quantities of von Willebrand factor in plasma and tissue stores. We have studied the genomic DNA of 10 affected individuals from six families with this disorder using probes from the 5' and 3' ends of the vWF cDNA and with a probe extending from the 5' end into the central region. Southern blots of restriction endonuclease digests and gene dosage analysis measurements carried out with quantitative slot blots of undigested genomic DNA separated these patients into three groups. The first group consisted of a family with complete homozygous deletions of the vWF gene in the four probands. Gene dosage analysis was consistent with heterozygous deletions in both of the asymptomatic parents and four asymptomatic siblings of this kindred (P less than 0.01). The second group was comprised of a family in which there was a complete heterozygous deletion of the vWF gene in the proband and one asymptomatic parent, suggesting that a different type of genetic abnormality was inherited from the other parent. Thus, the patient appeared to be doubly heterozygous for interacting genetic abnormalities affecting vWF expression. In the third group, no gene deletions could be detected. Alloantibodies developed only in the kindred with homozygous deletions. These techniques should prove useful in identifying carriers of severe von Willebrand disease and also in defining patients predictably at risk of developing alloantibodies to vWF.
Chromosome Deletion↗
Absence of hepatitis after treatment with a pasteurized factor VIII concentrate in patients with hemophilia and no previous transfusions.
Post-transfusion hepatitis is frequent among patients with hemophilia who are treated with concentrated factor VIII prepared from pooled plasma, especially if it is obtained from paid donors. In 26 patients with hemophilia A or von Willebrand's disease who had not been treated with blood or any blood product and hence were highly susceptible to the development of post-transfusion hepatitis, we infused 32 batches of a factor VIII concentrate that had been produced from large pools of human plasma (collected from paid plasmapheresis donors) and then heated in solution at 60 degrees C for 10 hours before final lyophilization. Patients were examined clinically and serologically over a period of 12 months after the first infusion of the pasteurized concentrate. Neither hepatitis nor serologic signs of other viral infections were observed. The hemostatic effectiveness of the concentrate appeared to be satisfactory relative to untreated concentrates.
Adolescent↗
Hemophilia A: carrier detection and prenatal diagnosis by DNA analysis.
In this study, we used DNA polymorphisms for carrier detection and prenatal diagnosis of hemophilia A in a large group of Italian families. The restriction fragment length polymorphisms (RFLPs) investigated were the intragenic polymorphic Bc/I site within the factor VIII gene; the extragenic multiallelic Taq I system at the St14 locus; and the extragenic Bg/II site at the DX13 locus. The factor VIII probe was informative in 30%, St14 in 82%, and DX13 in 60% of obligate carriers. The combination of factor VIII-Bc/I and St14-Taq I showed that 91% of obligate carriers were heterozygotes for one or both; with all three probes, only 4% of obligate carriers were noninformative. In families clearly segregating for hemophilia A, RFLP analysis allowed us to define the carrier status for the hemophilia A gene in all 27 women tested. RFLP analysis allowed us to exclude the carrier status in 39 of 45 female relatives of sporadic patients. The combination of RFLP analysis and biological assay of factor VIII allowed us to identify a de novo mutation in the maternal grandfather in 7 of 12 of the families with sporadic cases, for which members of three generations were available for study. Nine of 10 couples requesting prenatal diagnosis provided informative RFLP DNA pattern. Carrier status was excluded in two women, two fetuses were shown to be female, and prenatal diagnosis was carried out in five pregnancies by DNA analysis. Prenatal testing was successful in three instances and failed in two because a sufficient amount of chorionic villous DNA was not obtained for the analysis.
DNA↗
Hepatitis B vaccination of 113 hemophiliacs: lower antibody response in anti-LAV/HTLV-III-positive patients.
One-hundred thirteen adults and children with hemophilia or other congenital bleeding disorders were vaccinated against the hepatitis B virus. Each patient was given three subcutaneous injections of the vaccine at monthly intervals and then a fourth booster dose 14 months after the first. The vaccine was highly immunogenic, since 111 of 113 patients (98%) produced anti-HBs (10 mIU/ml or more). After the first three vaccine doses and after the booster dose, ten anti-LAV/HTLV-III-positive hemophiliacs produced anti-HBs but had a lower average titer than anti-LAV/HTLV-III-negative hemophiliacs. Of the 23 patients treated with concentrates in the 15 month postvaccination period only, none acquired HBV infection. Of the 50 patients treated with concentrates also in the 6 month prevaccination period, one developed hepatitis B. In summary, the vaccine was highly immunogenic in both children and adults with hemophilia; anti-LAV/HTLV-III-positive patients responded to the vaccine, but the average anti-HBs response was lower; no case of hepatitis B occurred in patients treated with concentrates only in the postvaccination period.
Adolescent↗
Effectiveness of defibrotide for prophylaxis of deep venous thrombosis in gynecological surgery: a double-blind, placebo-controlled clinical trial.
Defibrotide, a new antithrombotic compound without anticoagulant activity, has been tested for prevention of deep venous thrombosis (DVT) in patients undergoing gynecological surgery (mainly hysterectomy). Eighty-nine women (mean age 48.5) were randomly allocated to defibrotide (44 patients) or placebo (45 patients). 800 mg defibrotide was given daily (200 mg intravenously 4 times a day), starting on the day before operation and then for the next 7 days. DVT were detected by the conventional 125I-fibrinogen test. The two groups were homogeneous for known risk factors (age, varicosities, obesity, neoplasia and previous thromboembolic episodes). The results showed a statistically significant reduction of DVT incidence in patients on defibrotide, as compared with those on placebo: 4/44 = 9% vs. 13/45 = 28.8% (p less than 0.05). There were no side effects, including hemorrhagic complications. The numbers of units transfused were comparable for the 2 groups. In conclusion, the trial shows that defibrotide is an effective and safe drug for the prevention of DVT in gynecological surgery.
Double-Blind Method↗
Carrier detection in factor VII congenital deficiency.
Thirty obligate and 28 possible carriers of factor VII congenital deficiency, belonging to 16 families, were studied in relation to the immunological variants to which the kindreds belonged, namely, VII+, VIIR and VII-. Factor VII activity and antigen determinations in these subjects formed two phenotypical patterns: a discrepant pattern characterized by a low ratio activity/antigen present in VII+ heterozygotes, and a non-discrepant pattern (normal ratio activity/antigen) which is present in the VII- and VIIR variants. In the first genetic variant the detection of carriers can be performed using the ratio VII:C/VII:Ag. In the other variant, which accounts for the vast majority of heterozygotes, the distribution of the carriers' factor VII is so widespread that a large overlap results between these subjects and the normals. The application of a probabilistic calculation performed by combining the actual values of factor VII:C and the genetic probability of carriership using Fisher's linear discriminant analysis, makes discrimination between carriers and normals easier.
Adolescent↗
Hemophilia B with inhibitor: molecular analysis of the subtotal deletion of the factor IX gene.
The structure of factor IX gene was analyzed in a hemophilia B patient with inhibitor. Genomic DNA, digested with a variety of restriction endonucleases, was hybridized with the cDNA and various genomic factor IX probes. A large subtotal deletion of the gene was observed. The borders of the deletion span from a approximately 125 nucleotide region within the last exon to an unknown domain at least 7.5 kb upstream from the first exon: it thus involves approximately 33 kb of the factor IX locus. The abnormal gene was inherited by the daughter of the propositus, who showed both the normal and the deleted allele.
Chromosome Deletion↗
High-resolution analysis of von Willebrand factor multimeric composition defines a new variant of type I von Willebrand disease with aberrant structure but presence of all size multimers (type IC).
In Type I von Willebrand disease, the whole series of von Willebrand factor (vWF) multimers is present in plasma, but all are decreased in quantity. No structural abnormality of individual multimers has been demonstrated so far in these patients. We now describe five individuals, from two unrelated families, who had this form of the disease and in whom the complex banding pattern of each vWF multimer was markedly abnormal. Inheritance was autosomal dominant and the clinical expression was mild. A bleeding history was elicited in three of the patients and included recurrent epistaxis, menometrorrhagia, and bleeding following tooth extraction. Replacement therapy had never been required. Although vWF levels in plasma were within the normal range in all of them, the ristocetin cofactor activity was decreased in four, and the bleeding time was prolonged in three. Analysis of vWF multimeric structure by agarose gel electrophoresis, including a newly developed high-resolution technique, demonstrated that the main band of each multimer was present, but a second, well-defined band always seen in normal individuals was missing in the patients. Two additional bands had altered mobility and were less well defined than in normal subjects, and a fifth, less intense band was also undetectable in the patients. Treatment with 1-deamino-8-D-arginine vasopressin (DDAVP) was assessed in two patients. It caused the circulating levels of vWF to increase and correct the bleeding time, but did not alter the structural abnormality. This study describes, therefore, a new variant form of Type I von Willebrand disease with aberrant structure of individual repeating multimers and an associated functional abnormality of vWF. In keeping with previously accepted terminology, the designation of Type IC von Willebrand disease has been adopted for this new variant.
Adult↗
[Dipyridamole and warfarin in patients with artificial heart valve prosthesis: double-blind tests].
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Adolescent↗