Decreased body mass index is associated with impaired survival in lung cancer patients with brain metastases: A retrospective analysis of 624 patients.

Body mass index (BMI) is a prognostic factor in several cancer types. We investigated the prognostic role of BMI in a large patient cohort with newly diagnosed lung cancer brain metastases (BM) between 1990 and 2013. BMI at diagnosis of BM and graded prognostic assessment (GPA) were calculated. Definitions were underweight (BMI <18.50), weight within normal range (BMI 18.50-24.99) and overweight (BMI ≥ 25.00). A total of 624 patients (men 401/624 [64.3%]; women 223/624 [35.7%]; median age of 61 [range 33-88]) were analysed. Histology was non-small cell lung cancer in 417/622 (66.8%), small cell lung cancer (SCLC) in 205/624 (32.9%) and not otherwise specified in 2/624 (0.3%) patients. About 313/624 (50.2%) had normal BMI, 272/624 (43.5%) were overweight and 39/624 (6.3%) were underweight. Underweight patients had shorter median overall survival (3 months) compared to patients with normal BMI (7 months) and overweight (8 months; p < .001; log rank test). At multivariate analysis, higher GPA class (HR 1.430; 95% cumulative incidence, CI 1.279-1.598; p < .001; Cox regression model), SCLC histology (HR 1.310; 95% CI 1.101-1.558) and presence of underweight (HR 1.845; 95% CI 1.317-2.585; p = .014; Cox regression model) were independent prognostic factors. Underweight at diagnosis of BM in lung cancer is associated with an unfavourable prognosis.

The PERS(2) ON score for systemic assessment of symptomatology in palliative care: a pilot study.

The comprehensive assessment of symptoms is the basis for effective, individualised palliative treatment. Established scoring systems provide in-depth information but are often lengthy and hence unsuitable. We introduce the PERS(2) ON score as a short and practically feasible score to evaluate symptom burden. Fifty patients admitted to a Palliative Care Unit rated seven items, i.e. pain, eating (loss of appetite/weight loss), rehabilitation (physical impairment), social situation (possibility for home care), suffering (anxiety/burden of disease/depression), O2 (dyspnoea) and nausea/emesis, on a scale ranging from 0 (absence) to 10 (worst imaginable), resulting in a score ranging from 0 to 70. Assessments were performed at admission, 7 days after admission and at the day of discharge. Symptom intensity scores were calculated, and change over time was evaluated. A significant improvement was observed from the PERS²ON score between admission and 7 days (P < 0.001; paired t-test). Significant improvement from baseline evaluation to evaluation on the day of discharge was observed (P = 0.001; paired t-test). This study provides initial evidence that the PERS²ON score is both feasible and sensitive to changes of the most prominent symptoms in palliative care. It may be useful in clinical practice to direct palliative treatment strategies and provide targeted symptom management.

The quality of oral anticoagulation before, during and after a period of patient self-management.

The study analyzes the quality of anticoagulation during a 3-year follow-up on patients who were treated by an anticoagulation clinic (ACS) for 1 year (Phase I), performed weekly self-management of anticoagulation (PSM) after a specific training for another year (Phase II) and finally returned to be treated by the anticoagulation clinic (ACS) for a third year (Phase III). The mean fraction of INR values within therapeutic target range was higher in Phase II (0.69 +/- 0, 11) compared to Phases I (0.40 +/- 0.20) and III (0.56 +/- 0.18; p < 0.05). Time spent in therapeutic target range was higher in Phase II (0.70 +/- 0.10) compared to Phases I (0.43 +/- 0.25) and III (0.60 +/- 0.17; p < 0.05). Mean square deviation from target value was lower in Phase II (0.39 +/- 0.17) compared to Phases I (0.81 +/- 0.44) and III (0.64 +/- 0.39, p = 0.05). Thus, the quality of anticoagulation during Phase II (PSM) was significantly better compared to Phases I (ACS) and III (ACS) in all endpoints tested. This shows that the quality of oral anticoagulation deteriorates again if patient self-management is stopped and patients return to conventional treatment. Furthermore, the quality of anticoagulation was better in Phase III (post-PSM) compared with Phase I (pre-PSM) although the type of treatment was identical in both phases (ACS). This suggests that the increased patient empowerment and enhanced compliance acquired during PSM (Phase II) might have a positive impact on the quality of anticoagulation, even when patients return to the conventional treatment (ACS).

The decanucleotide polymorphism in the factor VII promoter predicts factor VII plasma levels but not the risk of acute coronary syndromes.

It is known from large epidemiological studies that the elevation of coagulation factor VII in plasma is an independent risk factor for acute coronary syndromes. The level of factor VII is influenced by polymorphic sites in the factor VII gene. However, data on the association of such polymorphisms with the risk of acute coronary syndromes are conflicting. A decanucleotide insertion/deletion polymorphic site has been described in the promoter of the factor VII gene that leads to a dramatic change in the plasma factor VII levels. We therefore analyzed the association of this polymorphism with the risk of acute coronary syndromes in a case-control study. Included in the study were 111 patients with angiographically documented acute coronary syndromes and 108 age- and sex-matched individuals from the same geographic area without signs or symptoms of coronary heart disease. The presence or absence of the decanucleotide stretch at position -323 in the promoter of factor VII was monitored using a polymerase chain reaction (PCR)-based restriction technique. The prevalence of the genotype with the homozygous deletion was similar in the patients with acute coronary syndromes (79.2%) and in the control patients (79.6%). There was a non-significant trend toward a higher prevalence of the homozygote deletion in patients with premature acute coronary syndromes (77.4%) compared with an age-matched subgroup of the control patients (67. 5%) (odds ratio [OR] 1.6, confidence interval [CI] 0.95, 0.61-3.93). Thus, we could not find a significant association of the occurrence of acute coronary events with the insertion/deletion polymorphism in factor VII.

A prospective controlled trial comparing weekly self-testing and self-dosing with the standard management of patients on stable oral anticoagulation.

Oral anticoagulant therapy requires frequent laboratory controls of its intensity to assure therapeutic efficacy and to prevent potentially life threatening adverse events. It is generally assumed, that increasing the frequency of testing would lead to a better control of anticoagulation. We tested this hypothesis in a prospective controlled trial comparing weekly self-testing and self-dosing (self management) with the standard-management of these patients in an anticoagulation clinic. Only patients with stable anticoagulation were included into the study. We recorded 2733 weekly determinations of the intensity of anticoagulation (INR) in 49 patients on self-testing and self-dosing and 539 determinations of the INR in 53 patients on standard-management. Two intensities of anticoagulation were used in each group: a target INR of 3.5 for patients with artificial heart valves (target range: 2.5-4.5) and a target INR 2.5 (target range: 2.0-3.0) for patients with atrial fibrillation or venous thromboembolism. The deviation from the target INR, the fraction of INR determinations within the preset therapeutic range and the difference between the target INR and the actually achieved mean INR were the three major endpoints of the study. The mean deviation from the target INR was smaller in the groups of patients on self-management compared to the patients on standard-management. Individual deviations were significantly (p <0.0001) dependent on the type of management in interaction with the treatment intensity in a general linear model. Patients on weekly self-testing and self-dosing had more INR values within the therapeutic range than patients on standard-management (86.2% vs. 80.1% at INR range 2.5-4.5; 82.2 vs. 68.9 at INR range 2.0-3.0). The achieved mean INR was almost identical with the target INR in the patients on self-management but was significantly (p <0.005) below the target INR in the high intensity anticoagulation group on standard-management (target INR:3.5; achieved mean INR: 3.19; CI 0.95: 3.05-3.34). Our data show, that weekly self-testing and self-dosing leads to a better control of anticoagulation than standard treatment in an anticoagulation clinic.

The impact of Glu102Lys on the factor X function in a patient with a doubly homozygous factor X deficiency (Gla14Lys and Glu102Lys).

Two homozygous point mutations were found in a patient with factor X (FX) deficiency; One results in substitution of Lys for Gla+ 14 and the second causes a Lys substitution for Glu102. The proposita has a severely reduced FX coagulant activity in the extrinsic (<1% of normal) and in the intrinsic (30% of normal) system of coagulation and after activation with Russel's viper venom (18% of normal). The FX antigen is reduced in this patient to 20% of normal. The substitution of Lys for Glu102 in FX deficiency has been reported previously in a heterozygous state in conjunction with a Lys for Gla+14 substitution and with a Pro for Ser334 substitution. The contribution of the Lys for Glu102 substitution in the observed combined FX defect in these patients was unclear. The mutation causing the Glu102Lys substitution was introduced by site directed mutagenesis into a wild-type FX cDNA, and recombinant protein was expressed in HEK 293 cells. Compared to the wild-type FX cDNA, the mutant construct had a 67% activity upon activation in the extrinsic system, 93% activity upon activation in the intrinsic system and 72% after activation with RVV. The data presented show that the substitution of Lys for Glu102 results in a minor functional defect of the FX molecule.

Coagulation factors II, V, VII, and X, prothrombin gene 20210G-->A transition, and factor V Leiden in coronary artery disease: high factor V clotting activity is an independent risk factor for myocardial infarction.

Increased levels of hemostatic factors and genetic mutations of proteins involved in coagulation may play a role in the pathogenesis of coronary artery disease. We investigated clotting activity of factors II (FII:C), V (FV:C), VII (FVII:C), and X (FX:C), the prothrombin gene 20210G-->A transition, and the factor V Leiden mutation in 200 survivors of myocardial infarction and in 100 healthy controls. FV:C (P<0.0001) and FVII:C (P<0.0001) were found to be independent risk factors for myocardial infarction. High FV:C or high FVII:C combined with smoking or arterial hypertension increased the relative risk for myocardial infarction up to 50-fold. One of 177 patients (0.6%) and 4 of 89 controls (4.5%) had the prothrombin 20210 AG genotype. Eleven of 177 patients (6.2%) and 6 of 89 controls (6.7%) were heterozygous for the factor V Leiden mutation. No homozygous carrier for these mutations was found. Neither the prothrombin gene 20210G-->A transition (odds ratio [OR], 0.1; 95% confidence interval [CI], 0.01 to 1.1) nor the factor V Leiden mutation (OR, 1.0; 95% CI, 0.4 to 2.8) were associated with an increased relative risk for myocardial infarction. In conclusion, our data indicate that neither the prothrombin gene 20210G-->A transition nor the factor V Leiden mutation are risk factors for myocardial infarction. High FVII:C was confirmed to be an independent risk factor for myocardial infarction. Moreover, we describe for the first time that high FV:C is an independent risk factor for myocardial infarction.

Oral anticoagulation after a first episode of venous thromboembolism: how long? How strong?

A number of studies have been published in the last years which shed light on the optimal intensity and the optimal duration of oral anticoagulation in patients with venous thrombosis. Based on these studies it is now generally recommended to treat patients with venous thromboembolism at an INR ranging from 2.0 to 3.0. The optimal duration of anticoagulation mainly depends on the nature of the thrombotic event. In patients with a temporary prothrombotic risk factor such as surgery, immobilization or trauma a relatively short duration of oral anticoagulation (3-6 months) is generally recommended. Patients with idiopathic venous thromboembolism require a considerably longer duration of anticoagulation (6 months at least).

Elevated activation markers of coagulation in patients undergoing orthognathic surgery.

Surgery is associated with a variable but increased incidence of postoperative venous thromboembolism (VTE). The risk of VTE after orthognathic surgery is unknown. Recently developed assays for activation markers of blood coagulation allow the detection of a prethrombotic state and may thus help to identify surgical procedures with a risk of postoperative VTE. The pre- and postoperative levels of thrombin-antithrombin complex (TAT) and prothrombin fragment 1+2 (F1+2) were studied in ten patients undergoing orthognathic surgery. Mean levels of TAT and F1+2 were within the normal range preoperatively (TAT:2.6+1.0 microg/L, F1+2:0.8+0.2 nmol/L). A significant increase in both parameters occurred postoperatively (TAT:21.8+21.4 microg/L, P<0.005; F1+2:1.3+0.4, P<0.02). No increase was observed in a control group (n=13) consisting of patients undergoing minor surgical procedures in general anesthesia. Our study shows that a marked activation of the coagulation cascade occurs during orthognathic surgery which warrants further studies on the true incidence of postoperative VTE in patients undergoing orthognathic surgery.

Factor X Frankfurt I: molecular and functional characterization of a hereditary factor X deficiency (Gla+25 to Lys).

A family with hereditary factor X deficiency is presented. One member, a 25-year-old man, showed a mild bleeding tendency. His factor X activity (extrinsic: 56%; intrinsic: 55%; Russell's viper venom: 57%) and his level of circulating factor X antigen (55% of normal) were markedly reduced. Analysis of his factor X gene revealed a single point mutation within exon II resulting in the substitution of +25 Gla (GAA) by Lys (AAA). The mutation was determined by gene analysis to be heterozygous in this patient, his mother and one of his brothers. Clotting assays of factor X purified from the plasma of the index patient revealed an activity of 89% of normal upon activation with Russell's viper venom, 77% of normal in the intrinsic and 81% of normal in the extrinsic coagulation pathway. The mutation responsible for the substitution of Lys for Gla+25 was introduced into an expression plasmid containing a wild type factor X cDNA and expressed in a mammalian cell line. Factor X antigen levels in the cell lysates and in the supernatant were identical in the mutant and wild type constructs. The specific activity of the factor X expressed from the mutant construct was 3% compared with the wild type construct. These data demonstrate that the substitution of Lys for Gla+25 results not only in a reduced level of factor X in the affected family members, but also in a substantial loss of specific factor X activity.

Geographic distribution of the 20210 G to A prothrombin variant.

A variant in prothrombin (clotting factor II), a G to A transition at nucleotide position 20210, has recently been shown to be associated with the prothrombin plasma levels and the risk of both venous and arterial thrombosis. The purpose of this study was to investigate the prevalence of carriership of this mutation in various populations. We combined data from 11 centres in nine countries, where tests for this mutation had been performed in groups representing the general population. We calculated an overall prevalence estimate, by a precision-weighted method, and, since the distribution of the prevalences did not appear homogeneous, by an unweighted average of the prevalences. We examined differences in the prevalences by geographical location and ethnic background as a possible explanation for the heterogeneity. Among a total of 5527 individuals who had been tested, 111 heterozygous carriers of the 20210A mutation were found. The prevalence estimates varied from 0.7 to 4.0 between the centres. The overall prevalence estimate was 2.0 percent (CI95 1.4-2.6%). The variation around the summary estimate appeared more than was expected by chance alone, and this heterogeneity could be explained by geographic differences. In southern Europe, the prevalence was 3.0 percent (CI95 2.3 to 3.7%), nearly twice as high as the prevalence in northern Europe (1.7%, CI95 1.3 to 2.2%). The prothrombin variant appeared very rare in individuals from Asian and African descent. The 20210A prothrombin variant is a common abnormality, with a prevalence of carriership between one and four percent. It is more common in southern than in northern Europe. Since this distribution within Europe is very different to that of another prothrombotic mutation (factor V Leiden or factor V R506Q), founder effects are the most likely explanation for the geographical distribution of both mutations.

Increased prevalence of a polymorphism in the gene coding for human prothrombin in patients with coronary heart disease.

A number of genetic risk factors for the development of coronary heart disease has been identified in the past. Some of these represent polymorphisms in genes of proteins which are associated with the process of blood clotting. We investigated the distribution of a recently described G/A polymorphism in the 3'untranslated region of the human prothrombin gene (nt 20210) in 98 patients (19 female age: 53 + 12 SD years and 79 male, age: 49 + 8.5 SD years) with coronary heart disease and in 102 healthy newborns by enzymatic amplification of the genomic DNA carrying the polymorphic site and by subsequent restriction digest. The diagnosis of coronary heart disease was established by coronary angiography in all patients. The frequency of the A allele in the healthy newborns was 0.98% (0.2%-3.5%; CI 0.95) with the G/A genotype occurring in 1.96% (0.24%-6.9%; CI 0.95). In the group of patients with coronary heart disease the G/A genotype was found in 5.1% (1.7%-11.4%; CI 0.95). 94.9% of the patients studied showed a G/G genotype. The A/A genotype was neither detected in the newborns nor in the patients with coronary heart disease. This preliminary study strongly suggest that the presence of the G/A polymorphism in the 3'untranslated region of the gene coding for human prothrombin is associated with the occurrence of coronary heart disease.

FLAG (fludarabine, cytosine arabinoside, G-CSF) for refractory and relapsed acute myeloid leukemia.

Twenty-two patients with refractory or relapsed AML were treated with FLAG [25 mg/m2 fludarabine daily (days 1-5), 2 g/m2 daily Ara-C (days 1-5) and 400 micrograms/m2 daily G-CSF (day -1 till the absolute neutrophil count was > 500/microliter)]. Median age was 46 years (range 24-63). Eight patients had leukemia which was primarily refractory to conventional regimens, six were in first, seven were in second, and one was in third relapse. Overall, 11 of 22 (50%) patients achieved complete remission (CR), three had a partial response (PR), and seven did not respond (NR). One patient died of an early cerebral hemorrhage. The median remission duration from achievement of CR after FLAG was 9.9 months and median survival was 13.0 months. One patient is alive in CR at 31.9 months. Hematological toxicity of the regimen was severe. The median time to neutrophil recovery (ANC > 500/microliter) was 21 days (range 18-33). A median of seven red cell units (range 0-22) and of six platelet concentrate units (range 3-28) had to be given. Median duration of febrile neutropenia was 2 days (range 0-20 days) and patients were on i.v. antibiotics for a median of 16 days (range 0-51). There was no death from infection. Nonhematological toxicity was remarkably low, with almost no neurotoxicity and no major hepatotoxicity. In conclusion, FLAG seems to be an efficient and well tolerated regimen. It may be particularly useful for patients who have a sibling or unrelated donor for subsequent allogeneic bone marrow transplantation.

Six novel and three recurrent mutations in nine Austrian patients with hemophilia B.

In this report we describe the molecular basis of the factor IX (FIX) deficiency in nine patients with severe (n = 6), moderate (n = 1) or mild (n = 2) hemophilia B. The following genetic defects were identified by enzymatic amplification with the polymerase chain reaction (PCR) and subsequent direct sequencing of all exons and exon-intron-junctions: patient B.B. (FIX "Vienna I"): deletion of nucleotides 6343 to 6362; patient M.H. and W.J. (FIX "Vienna II"): nucleotide 17704 (C to G), Gln 97 to Glu; patient L.K. (FIX "Vienna III"): nucleotide 17761 (C to T), Arg 116 to stop; patient U.A. (FIX "Vienna IV"): nucleotide 10415 (C to G), Pro 55 to Ala; patient H.G. (FIX "Vienna V"): nucleotide 6488 (C to T), Thr 38 to Ile; patient H.M. (FIX "Vienna VI"): nucleotide 31276 (G to C), Trp 385 to Cys; patient L.C. (FIX "Vienna VII"): deletion of nucleotide 6700; patient S.F. (FIX "Vienna VIII"): nucleotide 10392 (A to T), Asp 47 to Val. The causative mutation was detected in the FIX gene in each of the nine patients with hemophilia B. There was one small deletion, one point deletion and seven point mutations. The latter include six missense mutations and one nonsense mutation. The mutations in Vienna III, IV and V have already been described in previous studies. The two deletions, Vienna I and Vienna VII have not been reported previously. The genetic defects observed in Vienna II, VI and VIII are novel missense mutations which result in amino acid changes at residues 97, 47 and 385, respectively.

Symptomatic hereditary type-II protein C deficiency caused by a missense mutation in exon IX of the protein C gene (Gly381 to Ser).

We report the characterization of the genetic defect in a family with hereditary type-II protein C (PC) deficiency. The propositus is a 28-year-old woman with a history of thrombosis. Her PC activity level (58%) and PC antigen level (115%) are compatible with the diagnosis of type-II PC deficiency. Her asymptomatic sister is also PC deficient. Analysis of the PC gene of the propositus revealed a point mutation (G to A) at nucleotide 8856, which results in the replacement of Gly381 by Ser in the heavy chain of PC. The amino acid change occurs close to the active-site serine at a residue which is highly conserved among the serine proteases. The mutation is also present in the PC gene of the propositus' sister. Her brother, who is asymptomatic, has a normal genotype with respect to the mutation at nucleotide 8856.

Human coagulation factor X deficiency caused by a mutant signal peptide that blocks cleavage by signal peptidase but not targeting and translocation to the endoplasmic reticulum.

Human factor XSanto Domingo is a form of coagulation factor X in which a mutation within the signal peptide region of the precursor protein has been correlated genetically with a severe deficiency of factor X in the affected individual. A point mutation results in substitution of Arg for Gly at the critical -3 position of the factor X signal peptide. To determine the biochemical effect of this mutation on the biosynthesis of factor X, the wild-type and mutant factor X cDNAs were subcloned into a vector for transcription and translation in vitro. Translation products of mRNAs encoding portions of both mutant and wild-type proteins were used in a systematic biochemical approach to evaluate directly the effect of the mutation on targeting, transport, and proteolytic processing in vitro. The results show that targeting and transport of factor XSanto Domingo to the endoplasmic reticulum are functionally dissociated from the removal of the signal peptide by signal peptidase. Factor XSanto Domingo is translocated into the endoplasmic reticulum but not processed by signal peptidase. Transient expression of the wild-type and mutant factor X in human embryonic kidney 293 cells revealed apparently normal secretion of the glycosylated two-chain form of factor X but no secretion of factor XSanto Domingo. Thus, the inability of signal peptidase to cleave factor XSanto Domingo is directly responsible for the absence of circulating factor X and leads to the bleeding diathesis in the affected individual.

Factor XSanto Domingo. Evidence that the severe clinical phenotype arises from a mutation blocking secretion.

Factor X (FX) is a vitamin K-dependent plasma protein required for the intrinsic and extrinsic pathways of blood coagulation. FXSanto Domingo is a hereditary FX deficiency which is characterized clinically by a severe bleeding diathesis. The proposita has a FX activity of less than 1% and a FX antigen of less than 5%. We have determined the molecular basis of the defect in the FXSanto Domingo gene by amplification of all eight exons with polymerase chain reaction and subsequent sequence analysis. The patient is homozygous for a G----A transition in exon I at codon -20 (numbering the alanine at the NH2 terminus of the mature protein as +1), resulting in the substitution of arginine for glycine in the carboxy-terminal part of the signal peptide. This amino acid change occurs near the presumed cleavage site of the signal peptidase. We hypothesized that the mutation might prevent cleavage by the signal peptidase which in turn would impair proper secretion of the FX protein. To test this hypothesis, we compared the expression of wild type and mutant FX cDNA in a human kidney cell line. Wild type and mutant constructs in the expression vector pCMV4 were introduced into the human embryonic kidney cell line 293 by calcium phosphate transfection. FX antigen levels in the supernatant of the cells harboring the wild type construct were 2.4 micrograms/10(7) cells per 24 h, whereas antigen levels in media from cells containing the FXSanto Domingo construct were undetectable. No FX antigen was detected in the cell lysates of cells transfected with the mutant construct. To insure that the difference in protein levels was not due to a difference in steady state levels of mRNA, Northern analysis was performed on RNA from the cell lysates of both constructs. The results showed a transcript of the same size, present in roughly equal amounts, in both cases. Thus, the defect in the signal sequence of FXSanto Domingo exerts its effect posttranscriptionally. FXSanto Domingo is the first described example of a bleeding diathesis due to a mutation in the signal sequence.

Molecular defect (Gla+14----Lys) and its functional consequences in a hereditary factor X deficiency (factor X "Vorarlberg").

Factor X (FX) "Vorarlberg" is a congenital FX deficiency characterized clinically by a mild bleeding tendency. Homozygous individuals have a FX activity of less than 10% in the extrinsic system and 25% in the intrinsic system. FX antigen is 20%. Using molecular techniques, two point mutations were detected in the coding sequence of the FX Vorarlberg gene: a G----A at base pair 160 in exon II resulting in a change of Gla14 (GAA) to Lys (AAA); a G----A at base pair 424 in exon V resulting in a change from Glu102 (GAG) to Lys (AAG). The mutations abolished a TaqI restriction site in exon II and an MnlI site in exon V. To determine whether these mutations are present on one or on both alleles, restriction analyses of amplified exon II and exon V fragments were performed. Analysis of the pedigree showed that the genotype for the mutation on exon II (homozygous versus heterozygous) correlates with the severity of the phenotypic coagulation defect. We therefore conclude that the mutation in exon II is responsible for the functional defect in FX Vorarlberg. We have also purified the mutant FX protein from patient plasma. Purified FX Vorarlberg is indistinguishable from normal FX on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Its activity is 15% of normal FX upon activation with factor VIIa/tissue factor, 75% upon activation with factor IXa/factor VIIIa, and 100% upon activation with RVV. Activation at varying Ca2+ concentrations shows that the affinity of FX Vorarlberg for Ca2+ is decreased. Factor Xa Vorarlberg is able to convert prothrombin at a normal rate but also shows decreased affinity for Ca2+ in this interaction. Upon addition of Ca2+, FX Vorarlberg does not undergo the same conformational change as normal FX. Our data show that FX Vorarlberg has a decreased affinity for Ca2+ which impedes a normal conformational change. This leads to a decreased rate of activation by factor VIIa/tissue factor and by factor IXa. The decrease is much more marked for the extrinsic than for the intrinsic pathway.

Molecular cloning of a cDNA encoding canine factor IX.

Factor IX (F.IX) is a vitamin K-dependent plasma protein, a deficiency of which results in hemophilia B. A canine model of hemophilia B exists; attempts to use this model for gene transfer experiments or characterization of the hemophilic defect require elucidation of normal canine F.IX structure. We report the isolation and characterization of the coding region for canine F.IX cDNA. Canine F.IX possesses 86% identity at the amino-acid level with human F.IX. The leader peptide, Gla domain, EGF domains, and the carboxy-terminal portion of the heavy chains show extensive sequence conservation between the canine and human. All Glu residues undergoing gamma-carboxylation in humans are conserved in canines. The complete coding sequence for canine F.IX has been determined, and the derived translation product has been analyzed. A similar approach should allow identification of the causative mutation in canine hemophilia B. Furthermore, this clone may prove a valuable resource in gene transfer experiments for this disease.