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Biomedical subjects

H H Brackmann

Publications and source records attributed to H H Brackmann.

At least 73 records · Page 4Linked to original sources
PubMed1996

Characterization of the factor VIII defect in 147 patients with sporadic hemophilia A: family studies indicate a mutation type-dependent sex ratio of mutation frequencies.

The clinical manifestation of hemophilia A is caused by a wide range of different mutations. In this study the factor VIII genes of 147 severe hemophilia A patients--all exclusively from sporadic families--were screened for mutations by use of the complete panel of modern DNA techniques. The pathogenous defect could be characterized in 126 patients (85.7 percent). Fifty-five patients (37.4 percent) showed a F8A-gene inversion, 47 (32.0 percent) a point mutation, 14 (9.5 percent) a small deletion, 8 (5.4 percent) a large deletion, and 2 (1.4 percent) a small insertion. Further, four (2.7 percent) mutations were localized but could not be sequenced yet. No mutation could be identified in 17 patients (11.6 percent). Sixteen (10.9 percent) of the identified mutations occurred in the B domain. Four of these were located in an adenosine nucleotide stretch at codon 1192, indicating a mutation hotspot. Somatic mosaicisms were detected in 3 (3.9 percent) of 76 patients, mothers, comprising 3 of 16 de novo mutations in the patients mothers. Investigation of family relatives allowed detection of a de novo mutation in 16 of 76 two-generation and 28 of 34 three-generation families. On the basis of these data, the male:female ratio of mutation frequencies (k) was estimated as k = 3.6. By use of the quotients of mutation origin in maternal grandfather to patients mother or to maternal grandmother, k was directly estimated as k = 15 and k = 7.5, respectively. Considering each mutation type separately, we revealed a mutation type-specific sex ratio of mutation frequencies. Point mutations showed a 5-to-10-fold-higher and inversions a >10-fold-higher mutation rate in male germ cells, whereas deletions showed a >5-fold-higher mutation rate in female germ cells. Consequently, and in accordance with the data of other diseases like Duchenne muscular dystrophy, our results indicate that at least for X-chromosomal disorders the male:female mutation rate of a disease is determined by its proportion of the different mutation types.

Base Sequence↗
PubMed1996

Stabilization of transgene expression by incorporation of E3 region genes into an adenoviral factor IX vector and by transient anti-CD4 treatment of the host.

Complex interactions between replication deficient adenoviral vectors (Ad5) and the immune system of the host influence the stability of transgenes in vivo. Vector-infected cells are attacked by diverse cellular immune mechanisms which limit transgene persistence. On the other hand, the products of several E3 region genes of wild-type adenovirus can suppress host immune reactions by interference with the expression of MHC class I molecules and by other mechanisms. We have developed an adenoviral vector for human factor IX (Ad5E3+FIX) which carries the E3 region of wild-type adenovirus, and an E3-deleted vector of otherwise similar structure (ad5 delta E3FIX). Intravenous injection of Ad5E3+FIX in C57BI/6 mice resulted in expression levels up to 6000 ng/ml of recombinant human factor IX in the mouse plasma and in enhanced transgene stability as compared with the vector Ad5 delta E3FIX. Whereas expression from E3-deleted vectors was essentially turned off 8 weeks after the gene transfer, the vector Ad5E3+FIX3+FIX supported transgene expression with therapeutic levels of human factor IX in the mouse plasma for > 4 months. The enhanced stability of the vector Ad5E3+FIX appears to be a consequence of efficient E3 region-mediated suppression of the host's antivector immune response. As an additional approach to improving transgene stability the influence of transient CD4+ T cell depletion of the host was investigated. CD4+ cytotoxic T lymphocytes contribute to the clearance of adenovirus-infected cells and play a pivotal role in the activation of CD8+ cytotoxic T cells and as helper T cells in the formation of human adenovirus neutralizing antibodies (HANA). Transient anti-CD4 treatment of the host limited to the time of vector injection resulted in a significant prolongation of transgene expression from the factor IX vector Ad5E3+FIX and a luciferase vector Ad5Luc. The combination of transient anti-CD4 treatment of the host and integration of a complete E3 region in an adenoviral vector resulted in markedly improved transgene stability after gene transfer to the liver (therapeutic factor IX levels for > 6 months).

Adenoviridae↗
PubMed1996

Immunosuppression may lead to progression of hepatitis C virus-associated liver disease in hemophiliacs coinfected with HIV.

OBJECTIVE: The aim of this study was to examine the interaction between HIV and hepatitis C virus (HCV) in hemophiliacs coinfected with the viruses and to investigate the possible relationship between immunosuppression and liver failure. METHODS: To identify risk factors for impending liver failure in hemophiliacs coinfected with HIV and HCV, we analyzed clinical and laboratory parameters, including CD4 count, aminotransferases (ALT, AST), cholinesterase, alkaline phosphatase, bilirubin, and gamma-glutamyltransferase, during 3 yr of follow-up (1990-1993) in four groups of patients: hemophiliacs with progressive immunodeficiency who were coinfected with HCV and HIV (group A, n = 49); hemophiliacs with stable immune function who were seropositive for HIV and HCV (group B, n = 95); hemophiliacs who were infected with HCV but not HIV (group C, n = 72); and homosexuals with progressive immunodeficiency who were infected with HIV but not HCV (group D, n = 24). RESULTS: Univariate analysis of data for group A showed a significant rise in gamma-glutamyltransferase and alkaline phosphatase (p < 0.01) that was not seen in groups B, C, and D. In a multivariate Cox regression analysis, age (odds ratio, 1.054 per yr; 95% confidence interval, 1.014-1.096 per yr), decline in CD4 count (odds ratio, 1.063 per cell/microl; 95% confidence interval, 1.037-1.091 per cell/microl), and alkaline phosphatase level (odds ratio, 1.012 per U/L; 95% confidence interval, 1.002-1.021 per U/L) emerged as independent determinants of death. CONCLUSIONS: Our data suggest that progressive immune dysfunction in hemophiliacs coinfected with HIV and HCV may influence progression of liver failure. In these patients cholestasis is an additional prognostic marker for survival that may reflect both exhausted immunity and impaired liver function.

Acquired Immunodeficiency Syndrome↗
PubMed1995

The genetic diversification of the HIV type 1 gag p17 gene in patients infected from a common source.

An evolutionary analysis was undertaken of HIV-1 gag p17 sequences taken from a small cohort of hemophilia B patients infected from a common batch of clotting factor concentrate. The sequence population found at seroconversion was highly homogeneous, suggesting that the infecting batch also contained little sequence variation. Genetic diversification was found in follow-up sequences taken approximately 3 years later and was generally found to be complex. Greater rates of synonymous to nonsynonymous substitution were observed, especially when comparing distantly related isolates, and the rate of synonymous substitution was used to estimate times of divergence for a number of isolates of HIV-1 including the origin of the subtypes A to H. The p17 region is therefore proposed as a useful marker for future epidemiological studies.

Amino Acid Sequence↗
PubMed1995

QEEG in hemophiliacs with HIV infection.

Conventional visual analysis of the EEG was performed on 320 hemophiliacs infected with HIV, who spanned the range of the Walter Reed (WR) system for classifying clinical stage of HIV infection, and on 50 HIV seronegative hemophiliac controls. Intermittent or paroxysmal slowing was the conventional EEG abnormality most commonly seen in early stages of HIV infection (stages WR1 and 2), with increased focal epileptiform activity and generalized slowing appearing in patients with the full clinical syndrome of AIDS (WR6). Slowing of the manually measured alpha rhythm was noted in stages WR2 and above. Quantitative EEG (qEEG) was obtained in a subset of 103 male HIV seropositive male hemophiliacs and 35 male HIV seronegative hemophiliac controls. The principal findings were a progressive relative increase in theta power with a tendency towards an anterior topographic distribution, and a progressive decline of spectral power in fast alpha relative to slow alpha with increasing severity of HIV disease. Significant qEEG differences from controls were apparent in WR2 subjects (seropositive with lymphadenopathy and without other constitutional symptoms), and were relatively greater in WR3-6 subjects. These results suggest sensitivity of qEEG to early CNS involvement with HIV infection.

Adult↗
PubMed1995

Pharmacokinetics and tolerability of factor XIII concentrates prepared from human placenta or plasma: a crossover randomised study.

The pharmacokinetics and tolerability of factor XIII (FXIII) from plasma were compared with those of FXIII from placenta in a randomised, double-blind, crossover study involving 13 patients with congenital FXIII deficiency. Both FXIII activity and FXIII antigen were monitored. No difference was seen in the mean half-lives of the two preparations (9.3 days and 9.1 days for plasma and placenta FXIII activity, respectively). Response was similar for both preparations, but was slightly greater for FXIII from plasma (1.6 ormula: see text] vs 1.5 [formula: see text]). Similar results were found for recovery (65% vs 60%). The area under the data completed by extrapolation was significantly higher for FXIII from plasma. No differences between preparations in terms of efficacy or tolerability were observed. It can be concluded that treatment with FXIII concentrate from plasma is as efficient as with FXIII concentrate from placenta in terms of recovery and half-life. Both preparations were equivalent in terms of safety during the observation period. With the administration of monthly injections of approximately 30 U/kg serious bleeding events were prevented and no other serious adverse events occurred.

Adolescent↗
PubMed1995

Haemophilia A: mutation type determines risk of inhibitor formation.

The formation of factor VIII antibodies is a major problem for replacement therapy of haemophilia A patients. Antibodies occur in 5-30% of patients with severe haemophilia A. The reason for antibody formation is still unknown. In this study we correlate for the first time different factor VIII gene mutations, stop- and missense mutations, large and small deletions and intrachromosomal intron 22 recombinations to antibody formation. A total of 364 patients with known inhibitor status of our institute, of the database, and of 3 studies representing intron-22-inversion data are included. The results show that the risk for developing factor VIII antibodies is strongly related to stop mutations. large deletions and intrachromosomal recombinations. A probable explanation could be the complete lack of endogenous circulating factor VIII protein in these cases. Other factors that might be important for the pathogenesis of inhibitor formation, e. g. the antenatal period, as well as possible therapeutic effects, are discussed.

Antibodies↗
PubMed1994

Parallel evolution in the V3 region of HIV type 1 after infection of hemophiliacs from a homogeneous source.

To determine the genetic diversification in the highly functional V3 loop, we followed up five hemophiliacs who were infected by a homogeneous HIV-1 population from a contaminated clotting factor lot. Initially, all patients displayed identical DNA sequences in this part of the proviral env gene. Therefore, this unique outbreak allows us to investigate the biological and genetic development of a common ancestor virus in different patients. A high degree of homology is maintained in the predominant sequences from 5 until 35 months after seroconversion. Only one patient showed a remarkable diversification 3 years postinfection. However, these genetic changes in the V3 region were not associated with disease progression. Discontinuous sequence changes were observed mainly in a region downstream of the V3 loop. Two positions in particular are involved in a sequence evolution within the V3 loop leading to the same amino acids in different patients. These directed changes occurred at sites that are reported to be critical for the specificity of antibodies (position 308) and viral cytopathicity (position 324). However, the parallel evolution was associated neither with differentiation of the viral phenotype nor with progression of the disease.

Amino Acid Sequence↗
PubMed1994

How will immune tolerance protocols affect self-sufficiency goals?

Inhibitor development is a serious complication in haemophilia, and its treatment, immune tolerance therapy, is an expensive part of haemophilia treatment. However, the therapy can lead to an increased lifespan and improved quality of life. If commenced sufficiently early in the disease, it can help to reduce the overall amount of factor VIII concentrate, or other plasma derived therapeutic agents required during life.

Adult↗
PubMed1994

Haemophilia A diagnosis by automated fluorescent DNA detection of ten factor VIII intron 13 dinucleotide repeat alleles.

Haemophilia A is a recessive X linked bleeding disorder caused by deficiency or functional abnormality of coagulation factor VIII. This disease usually has no visible phenotype in female carriers; hence, great efforts are made to offer all haemophilia A families accurate carrier diagnosis. Significant progress in this direction was made with the identification of the intron 13 variable number tandem repeat (VNTR), which is hitherto the most informative single marker within the factor VIII gene. The authors have established intron 13 VNTR detection in their laboratory by adapting its analysis to an automated sequencer using different primers of which one is fluorescent dye labelled. With this method, which is more rapid and convenient than that originally described, 67 haemophilia A families of German origin were screened and two new alleles (alleles 17 and 25) were identified. The informativeness of the VNTR in these families based on the patients maternal X chromosomes (134) is about 67%.

Alleles↗
PubMed1994

Serological and virological markers of human parvovirus B19 infection in sera of hemophiliacs.

It is known that parvovirus B19 (B19) is transmitted to hemophiliacs by clotting factors prepared from human plasma. However, it is not clear whether B19 is also transmitted by the more recently used inactivated clotting factor preparations. Therefore, we investigated 69 hemophiliacs, mostly children, receiving only virus-inactivated clotting factors. 49 of them (71%) were B19 IgG-positive and 18 of the IgG-positive hemophiliacs (37%) were also B19 IgM-positive. In contrast, out of 73 age-matched controls only 10 (14%) were IgG-positive, two of them being also IgM-positive. In hemophiliacs treated before 1984 with non-inactivated clotting factors, seroprevalence was very similar: 94/136 (69%) presented B19 IgG antibodies as compared to their age-matched controls with 16/50 (32%). Out of the 94 IgG-positive patients 24 (26%) were IgM-positive, whereas IgM antibodies were never found in 16 sera of 16 IgG-positive controls. In 4 out of 24 IgM positive hemophiliacs, B19 DNA was detected in the sera by using the polymerase chain reaction. However, B19 DNA was also found in 3/69 anti-B19 IgM-negative, HIV-infected hemophiliacs (all three patients in CDC stage IV). Since it seems unlikely that the results only represent passive acquisition of B19 DNA from blood products and induction of antibodies by immunization with inactivated antigen, the observations rather suggest that infection with B19 is transmitted by clotting factors, including those treated for virus inactivation.

Acute Disease↗
PubMed1994

[Hemophilia A: molecular biology and carrier diagnosis].

OBJECTIVE: Within this review we give an overview of haemophilia A research concentrating on molecular biology and carrier diagnosis. Haemophilia A, located on X-chromosome and transmitted recessively, is caused by deficiency or functional abnormality of coagulation factor VIII. DATA SOURCES: For this review we used original papers as main sources, but also review articles as well as study results of our group. SELECTION CRITERIA: This review describes factor VIII synthesis and its posttranslational modification, and it discusses the known functional domains of factor VIII protein on the basis of mutations identified and protein studies. Additionally, the significance of mutations concerning carrier diagnosis of haemophilia A affected families is described. RESULTS: Only a few functional domains within factor VIII protein are found, so far. Using newly available prescreening methods, mutations are now identified within factor VIII gene in about 60% of all patients studied. This is an excellent completion of the already available carrier diagnosis by polymorphisms and factor VIII coagulation data. CONCLUSION: The new mutations identified using prescreening methods will improve the results of factor VIII protein studies. In spite of this progress, mutation screening should be intensified, thus allowing to diagnose each female who could be a carrier of haemophilia A.

Factor VIII↗
PubMed1994

Hepatitis A virus infection among the hemophilia population at the Bonn Hemophilia Center.

Following a publication on the sudden outbreak of hepatitis A (HAV) infections in Italian hemophiliacs after treatment with a solvent detergent (S/D) virus-inactivated factor VIII concentrate, we retrospectively examined our patients for HAV seroconversions and clinical symptoms of an acute HAV infection at our center. We found that between 1988 and 1992, 17 hemophilia A patients displayed HAV IgG seroconversions. Of these patients, 13 also had an HAV IgM seroconversion and 10 exhibited clinical symptoms of an acute HAV infection. A feature common to all was the fact that in the months prior to seroconversion they had been treated exclusively with the S/D-virus-inactivated product Octavi manufactured by Octapharma in Düsseldorf (FRG). None of the hemophilia A patients who had been treated with other products and who were susceptible to hepatitis A displayed seroconversion in the above-mentioned time span.

Adolescent↗