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Biomedical subjects

W M Halbmayer

Publications and source records attributed to W M Halbmayer.

At least 19 recordsLinked to original sources
PubMed1999

Rational, high quality laboratory monitoring before, during, and after infusion of prothrombin complex concentrates.

Prothrombin complex concentrates (PCCs) have been used for over thirty years to treat or prevent bleeding due to hemophilia B, vitamin K deficiency, warfarin overdose, liver disease, or deficiency of one of the prothrombin complex factors. This article tries to answer the questions of which profile of laboratory assays is required for the establishment of the diagnosis; what are indications of replacement therapy with PCCs; how to monitor the therapeutic effect; and how to monitor a possible prethrombotic state after PCC infusion. After proposing basic, standard, and optimal profiles of hemostaseological assays, the basic principal characteristics of a quality management satisfying the requirements of good laboratory practice are discussed.

Blood Coagulation Factors↗
PubMed1999

Venous thromboembolism at a young age in a brother and sister with coinheritance of homozygous 20210A/A prothrombin mutation and heterozygous 1691G/A factor V Leiden mutation.

We report on members of a Turkish thrombophilic family with coinheritance of the prothrombin mutation PT20210A and the factor V Leiden mutation. The 23-year-old propositus and his elder sister both had episodes of venous theomboembolism at a young age (23 years and 26 years, respectively) and are homozygous for the PT20210A mutation and heterozygous for the factor V Leiden mutation. The 51-year-old father is suffering from coronary heart disease and is heterozygous for both thrombophilic mutations. The asymptomatic 43-year-old mother is heterozygous for the PT20210A mutation, but without activated protein C resistance. Two other children, a 20-year-old girl who is homozygous for the PT20210A mutation and a 13-year-old boy who is heterozygous for the PT20210A mutation, are both free from activated protein C resistance and thrombosis. This report provides further evidence for an early onset of thromboembolic disorders in individuals with an homozygous state of the prothrombin variant 20210A/A and coinheritance of another thrombophilic mutation. Consensus guidelines are required for the treatment and prophylaxis of patients and subjects who remain asymptomatic with homozygous or more than one heterozygous genetic defect associated with thrombophilia.

Adult↗
PubMed1997

Mutations in the human factor XII gene.

The factor XII gene from 31 unrelated factor XII-deficient patients from Germany, Switzerland, and Austria was screened for mutations at the genomic level. Several novel mutations were detected and their absence in a control group of 74 healthy unrelated individuals was checked. Most changes are in the serine protease domain affecting the catalytic triad His-393-Asp-442-Ser-544; two missense mutations, R398Q (arginine 398 to glutamine; gene bank accession no. U71276) and L395M (leucine 395 to methionine; gene bank accession no. U71277), are close to the active site histidine at position 393. Another mutation detected in a cross-reacting material (CRM)-positive female with a history of three abortions affects the active site aspartic acid by changing it to asparagine (D442N; gene bank accession no. U71275). The novel mutation G570R (glycine 570 to arginine; gene bank accession no. U71274) giving rise to a CRM-positive phenotype is located next to Cys571, which forms a vital disulfide bridge. Two mutations are causing reading frame shifts: one single basepair deletion in exon 12 [exon 12: 10590(DelC); gene bank accession no. U71278] and one acceptor splice site mutation [exon 14: 11397(G --> A); gene bank accession no. L43615]. The putative regulatory mutation exon 1:-8 (g --> c) in the upstream region of the gene is associated with an aberrant Taq I restriction site allele in intron B of the gene (gene bank accession no. X80393).

Alleles↗
PubMed1997

A hitherto unknown splice site defect in the protein S gene (PROS1): the mutation results in allelic exclusion and causes type I and type III protein S deficiency.

A hitherto unknown splice site mutation, in the splice acceptor of intron B (tctag to tctgg), was identified in a symptomatic patient with type III protein S deficiency. The mutation co-segregated with type I/III protein S deficiency in the patient's family. RNA analysis showed allelic exclusion of the mutant transcript in affected individuals. The apparent type III deficiency in the propositus was not associated with the protein S Heerlen variant.

Humans↗
PubMed1996

Anti-GM1 antibodies in polyneuropathies of unknown origin.

This study was undertaken to determine whether anti-GM1 titres are raised in polyneuropathies of unknown origin and whether determination of these titres is useful for diagnosing these conditions. The study population comprised 20 controls (aged 36-88 years), 12 patients with polyneuropathies of known origin (aged 31-81 years) and 15 patients with polyneuropathies of unknown origin (aged 40-77 years). Antibody levels were measured using a commercial GM1 enzyme linked immunosorbent assay kit (Buehlmann Laboratories). Mean anti-GM1 IgG and IgM antibody titres were not raised in patients with polyneuropathies of unknown origin. Anti-GM1 IgG antibody titres were raised in one and GM1 IgM antibody titres in none of the patients with polyneuropathies of unknown origin. In conclusion, GM1 antibody levels are rarely raised in polyneuropathies of unknown origin and probably play a minor role in the pathogenesis of these conditions.

Adult↗
PubMed1995

Platelet size, fibrinogen and lipoprotein(a) in coronary heart disease.

BACKGROUND: An increase in mean platelet volume has been reported to be associated with arterial thrombosis and myocardial infarction. A larger mean platelet volume has been regarded as an independent risk factor for recurrent myocardial infarction. We therefore investigated whether it is also increased in patients with coronary heart disease examined a few days before cardiac surgery. METHODS: Four hundred and twenty-six patients with coronary heart disease who were waiting for cardiac surgery and 125 healthy individuals were included in the study. Mean platelet volume and other platelet parameters were obtained from a routine blood count procedure using a flow cytometric haematology analyser. RESULTS: Mean platelet volume did not differ significantly between patients and controls; however, as expected from the literature, patients had significantly elevated levels of fibrinogen, cholesterol, triglyceride, apolipoprotein B and apolipoprotein(a). Furthermore, we observed no significant difference in mean platelet volume between patients without myocardial infarction and those who had survived at least one myocardial infarction. CONCLUSION: Our findings suggest that, using a routine laboratory procedure, mean platelet volume cannot be used as a predictive marker for coronary heart disease or myocardial infarction.

Adult↗
PubMed1995

Quality assurance of high-dose i.v. heparin treatment exemplified by patients implanted with coronary Palmaz-Schatz stents.

The need to standardize treatment with high-dose IV standard heparin by using activated partial thromboplastin time (APTT) reagents tested for their heparin sensitivity and by establishing a standard treatment schedule led to the development of the "Lainz concept" of heparin management. The determination of heparin sensitivity of the 2 APTT reagents used (APTT Micronized Silica and APTT Actin FSL), their good agreement (r = .9977; P = .000), and their therapeutic APTT ratio of 1.5-2.5 fold of baseline APTT (therapeutic range, forty-five to seventy-five seconds) equivalent to 0.3-0.7 antifactor Xa units are presented. The "Lainz concept" was tested in 29 patients receiving high-dose heparin after coronary artery stenting. A mean dose of 1,273 U of standard heparin/hour (15.7 U/kg body weight/hour) was shown to produce APTTs in the therapeutic range. From the introduction of the "Lainz concept" 81% of the APTTs were kept within the therapeutic range by using a defined heparin-monitoring schedule based on a guideline protocol for controlling heparin treatment. Only 19% of the APTTs were below the therapeutic range. Factors underlying subtherapeutic APTTs are discussed. The reduction in the rate of subtherapeutic APTTs to less than 3% seen after the introduction of the "Lainz concept" constitutes an important contribution toward quality assurance in high-dose heparin treatment.

Aged↗
PubMed1995

[External quality assurance: a significant--and 25-year-old--element of quality management in the medical diagnostic laboratory].

An external quality assurance system in the medical diagnostic laboratory, which is an essential part of the modern total quality management (TQM) concept in the public health system, was established in Austria already 25 years ago. The development and the scope of this quality assessment system by the "Austrian Society for Quality Assurance and Standardization of Analyses in the Clinical Laboratory" (OQUASTA) are presented. The decreasing coefficients of variation of several parameters of the external quality assessment exercises demonstrate an increasing analytical precision and might be interpreted as an effect of this quality assurance system.

Austria↗
PubMed1995

[Changes in antithrombin III, prothrombin fragment 1 + 2 and thrombin-antithrombin III complex following implantation of a coronary Palmaz-Schatz stent].

To detect changes in the clotting parameters antithrombin III (AT III), prothrombin-fragment 1 + 2 (F 1 + 2) and thrombin-antithrombin-III-complex (TAT) after implantation of Palmaz Schatz stents, coagulation was monitored at standardized time points in 35 patients for 10 days. All patients were anticoagulated using a combination of heparin, phenprocoumon, and acetyl salicylic acid. Heparin therapy was guided by APTT levels (normal range 25-35 s), which were still within the therapeutic range (median 49.6 s (25%/75% percentiles 41.6/54.4) on day 10. Simultaneous oral anticoagulation was found to be effective on day 8 on average (INR median 2.24 (1.93/2.50)). The AT III activity dropped significantly (p < 0.0001) after a heparin loading dose of 15,000 IU during stenting. As the heparin dose was reduced on the following days, AT III levels increased significantly (p < 0.0001) during the observation time. There was a highly significant (p < 0.001) negative correlation between AT III and heparin levels. On days 4 and 5 F 1 + 2 values were significantly (p < 0.001 and p < 0.05) higher than on the day of stenting (median 1.07 (0.90/1.31) 1.13 nmol/l and 1.06 (0.85/1.23) nmol/l vs. 0.97 (0.69/1.15) nmol/l) and dropped during anticoagulation. F 1 + 2 levels showed a significant negative correlation (p < 0.0005) with APTT values. TAT values showed no significant changes during the observation period.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1994

High-dose intravenous melphalan in a patient with multiple myeloma and oliguric renal failure.

A kappa light-chain myeloma was diagnosed as the underlying disease in a 52-year-old woman with acute oliguric renal failure. The patient was erroneously treated with high-dose intravenous melphalan (60 mg/m2). Because of this overdose treatment with granulocyte colony-stimulating factor was initiated, but pronounced absolute leukopenia (white blood cell count < 0.5 x 10(9)/l) developed and lasted for 13 days. Following melphalan treatment a continuous increase in urine volume was accompanied by a decrease of serum creatinine and blood urea nitrogen. Within 10 days after the administration of melphalan the patient no longer required hemodialysis. We conclude that high-dose chemotherapy in combination with hematopoietic growth factors should be considered in individual cases with newly diagnosed light-chain nephropathy.

Acute Kidney Injury↗
PubMed1994

The prevalence of poor anticoagulant response to activated protein C (APC resistance) among patients suffering from stroke or venous thrombosis and among healthy subjects.

A poor anticoagulant response to activated protein C (APC) in an activated partial thromboplastin time (aPTT) assay (APC resistance) was recently reported to be a cause of familial thrombophilia. The response to APC was measured in 30 patients suffering from juvenile or recurrent stroke, in 40 patients suffering from venous thromboembolism and in 50 healthy subjects. The prevalence of APC resistance was found to be significantly higher among patients with stroke (20%, P < 0.003) and venous thrombosis (17.5%, P < 0.02) compared with the prevalence of APC resistance among normal controls (2%). In one case of venous thrombosis, the proposita's family (A) could be investigated and in five out of nine investigated members (56%) a poor or borderline response to APC was detected. The family (B) of another APC-resistant patient revealed six subjects with poor coagulation response to APC out of eight family members studied (75%). Measuring protein S activity with an automated calcium-thromboplastin-based protein S activity assay, a significant correlation (P < 0.0001) between the results of this functional protein S assay and APC resistance (represented by the ratio (Rs value) of clotting time with and without addition of activated protein C) was observed. Nine out of 14 patients (64%) with poor APC response showed protein S activities below the normal range. Assessment of protein S activity with a second protein S clotting assay using factor Va as substrate confirmed only 47% of the decreased levels of the thromboplastin-based protein S clotting assay.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Course of thrombin activation markers in patients implanted with Palmaz-Schatz stents: first experiences with a post-interventional anticoagulation regimen.

Following implantation of coronary Palmaz-Schatz stents, 29 patients were anticoagulated with a combination of heparin, phenprocoumon and aspirin following a standard protocol. After removing the arterial and venous lines, post-interventional intravenous (i.v.) heparin treatment started with 1500 IU/h for patients > 80 kg and 1250 IU/h for patients < 80 kg. Heparin was monitored by the activated partial thromboplastin time (aPTT) and adjusted by increasing or reducing i.v. heparin by 250 IU/h to maintain the aPTT within the therapeutic range. Phenprocoumon therapy began the day after stent implantation (day 2) and lasted for 3 months. aPTT, Heptest, prothrombin fragment F1 and 2 (F1.2) and thrombin-antithrombin III complexes (TAT) were monitored at standard intervals for 10 days (mean monitoring time: 9.7 +/- 2.3 days). Anticoagulation was efficient with aPTT levels remaining within the therapeutic range on day 9 and the simultaneous, moderate-onset oral anticoagulation within the therapeutic range of the International Normalized Ratio (INR; 2.15-4.80) on day 8 on average, the mean INR being 2.43 +/- 0.76. On day 4, F1.2 levels were significantly higher than on the day of stenting (1.16 +/- 0.30 nmol/l vs 1.04 +/- 0.53 nmol/l; P < 0.005). F1.2 levels fell after day 5, the difference becoming significant from day 8 on (P < 0.05). F1.2 was negatively correlated with the Heptest (P < 0.05) and fell significantly as a function of the INR during phenprocoumon administration (P < 0.001). After phenprocoumon therapy was discontinued over 3 weeks, 25 patients were followed up by angiography. Despite adequate anticoagulation, mean F1.2 levels in patients showing restenosis at follow-up angiography were significantly higher (P < 0.005) than in those without restenosis. In one patient who developed subacute stent thrombosis, clotting factors were determined 20 min before stent occlusion. The levels of F1.2 and TAT were less than all other patients on this day (F1.2: 0.98 nmol/l vs 1.11 +/- 0.40 nmol/l; TAT: 2.7 micrograms/l vs 3.21 +/- 3.38 micrograms/l). Thus, neither F1.2 nor TAT predicted the occurrence of thrombotic stent failure in individuals. Efficient anticoagulation by a combination of anticoagulants is imperative for stent implantation. Using only current routine methods, this way of monitoring anticoagulation is effective for managing combined anticoagulation therapy.

Adult↗
PubMed1994

Prevalence of factor XII (Hageman factor) deficiency among 426 patients with coronary heart disease awaiting cardiac surgery.

BACKGROUND: Several case reports of myocardial infarction in patients with factor XII deficiency have been published. In the present study we investigated the prevalence of this condition. METHODS: Factor XII activity (one-stage clotting assay), fibrinogen (derived method), and lipoprotein (a) (enzyme-linked immunosorbent assay) were measured in the plasma of 426 consecutive patients with coronary heart disease awaiting cardiac surgery. RESULTS: Among the 426 patients, 44 (10.3%) were found to be moderately deficient in factor XII (factor XII activity 17-50%, antigen 15-57%). The prevalence of factor XII deficiency was significantly higher (P < 0.0001) among patients with coronary heart disease than among 300 healthy blood donors (2.3%). Among coronary heart disease patients with this deficiency, elevated levels of fibrinogen, lipoprotein (a), and blood pressure were no more prevalent than in those without the deficiency; nor were cigarette smoking or a positive family history of thromboembolism more prevalent. CONCLUSIONS: Coronary heart disease patients showed a 10% prevalence of factor XII deficiency. However, the pattern of atherosclerotic risk factors did not differ between patients with or without the deficiency.

Blood Coagulation Tests↗