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Biomedical subjects

E Bakker

Publications and source records attributed to E Bakker.

At least 109 records · Page 6Linked to original sources
PubMed1995

Point mutation screening for 16 exons of the dystrophin gene by multiplex single-strand conformation polymorphism analysis.

We have developed a rapid and nonradioactive method to screen for point mutations using the Pharmacia PhastSystem. In an SSCP analysis, we applied the two multiplex exon PCR kits, commonly used for the detection of deletions in Duchenne and Becker muscular dystrophy patients. The different exon bands in the multiplex SSCP pattern could be identified by running well-characterised deletion patients in this system. Two common polymorphisms were easily identifiable and are helpful in the haplotype analysis in families. Screening of 70 patients in which no gross rearrangement was detectable with the multiplex PCR and Southern blot, resulted in the identification of 6 patients with a band shift after SSCP analysis. Of these 6 band shifts, 5 were the result of a frame shift or termination mutation. The other band shift was found to be a rare polymorphism unlikely to be the cause of the patient's phenotype. Application of this technique enabled us to improve diagnosis in the families involved and will allow us to extend the search for point mutations in the remaining exons of the dystrophin gene.

Blotting, Southern↗
PubMed1995

Inversions in the factor VIII gene: improvement of carrier detection and prenatal diagnosis in Dutch haemophilia A families.

Haemophilia A is an X linked bleeding disorder caused by a heterogeneous spectrum of mutations in the factor VIII gene. It has recently been reported that about 50% of severe haemophilia A cases are the result of an iversion in the factor VIII gene. The inversion results from homologous recombination between the A gene located in intron 22 of the FVIII gene and one of the two distal A genes, thus disrupting the coding sequence of the factor VIII gene. The inversion can be detected by conventional Southern blotting and hybridisation techniques. Here we present an analysis of 177 unrelated Dutch haemophilia A cases for the presence of an inversion. In 57% of the patients with severe disease an inversion was found and also in at least one of the 26 patients with moderately severe disease. The majority of inversions (85%) involved the most distal A gene, while in a minority (15%) the more proximal A gene was involved. We show that direct mutation detection greatly improves the assessment of carrier status and prenatal diagnosis for haemophilia A, especially in families with an isolated patient. The inversion is predominantly of grandpaternal origin.

Blotting, Southern↗
PubMed1995

Refinement of the localisation of the X linked keratosis follicularis spinulosa decalvans (KFSD) gene in Xp22.13-p22.2.

X-linked keratosis follicularis spinulosa decalvans (KFSD) is a rare disorder affecting the skin and eyes. The disease was previously mapped in an extended Dutch family to Xp21.2-p22.2 between DXS16 and DXS269. Using five DNA probes and 14 CA repeat polymorphisms spanning this region an extensive linkage study was performed in the same pedigree. The highest lod scores were 12.07 for DXS365 (pRX-314) at 0 = 0, 11.72 for DXS418 (P122) at 0 = 0.015, and 10.93 for DXS989 (AFM135xe7) at 0 = 0.045. Analysis of recombination events locates the gene for KFSD between AFM291wf5 and DXS1226 (AFM316yf5). This is region Xp22.13-p22.2, an area covering approximately 1 Mb. These data confirm and greatly refine the regional localisation of KFSD and greatly improve reliability of carrier detection.

Blotting, Southern↗
PubMed1995

The FSHD-linked locus D4F104S1 (p13E-11) on 4q35 has a homologue on 10qter.

Facioscapulohumeral muscular dystrophy (FSHD) has recently been shown to be associated with deletions that are detectable using probe p13E-11 (D4F104S1). Although these deletions reside within large, highly polymorphic restriction fragments (20-300 kb), the "mutant" fragment is usually shorter than 28 kb and can routinely be detected using conventional agarose gel electrophoresis. Yet, the complete visualization of the alleles requires pulsed-field gel electrophoresis (PFGE). Family studies showed that p13E-11 detects two nonallelic loci in this size range, only one of which originates from chromosome 4q35. We have assigned the other p13E-11 locus to chromosome 10qter by linkage analysis in CEPH pedigrees. Knowing the location of both loci improves the diagnostic reliability, as the exact origin of "small" EcoRI fragments can be determined by haplotyping. Since FSHD shows genetic heterogeneity, this 10qter locus became an interesting candidate to be the second FSHD locus. However, analysis of a large chromosome 4-unlinked FSHD family did not provide evidence for linkage on chromosome 10qter.

Chromosome Mapping↗
PubMed1995

Early onset facioscapulohumeral muscular dystrophy.

We report 10 patients (5 familial, 5 sporadic) with facioscapulohumeral muscular dystrophy (FSHD) with onset of facial and shoulder girdle weakness in early infancy. They showed the same broad range of clinical signs and symptoms as can be seen normally in FSHD. In 7 patients Southern blotting with p13E-11 was performed which showed an abnormal EcoRI fragment (13-22 kb) in 6 of them. We conclude that early onset FSHD does not differ from regular FSHD clinically or genetically. However, the precise mechanisms involved in the extensive clinical variability of the disease are still unknown.

Adolescent↗
PubMed1995

Facioscapulohumeral muscular dystrophy in the Dutch population.

Extrapolating the figures from a previous study on FSHD in a province of The Netherlands to the entire Dutch population suggests that at present a nearly complete overview is obtained of all symptomatic kindred. In 139 families, dominant inheritance was observed in 97, a pattern compatible with germline mosaicism in 6, while sporadic cases were found in 36 families. A mutation frequency of 9.6% was calculated. Mental retardation and severe retinal vasculopathy were reported in low frequencies (1%). Early onset was seen more frequently in sporadic cases. Chromosome 4 linkage appeared excluded in 3 of 22 autosomal-dominant families. The clinical pictures in the linked and nonlinked families were identical.

Age of Onset↗
PubMed1994

Selectivity of polymer membrane-based ion-selective electrodes: self-consistent model describing the potentiometric response in mixed ion solutions of different charge.

Despite its well-documented limitations, the semiempirical Nicolsky-Eisenman equation is used throughout the existing analytical literature to describe the selectivity of modern polymer membrane-based ion-selective electrodes (ISEs). In this paper, a new quantitative description for the response/selectivity function based on ion-extraction equilibria at the sample/membrane interface is presented. The proposed selectivity formalism clearly illustrates the range of validity for the conventional Nicolsky-Eisenman formalism. Extended equations are derived describing the electrode response in an exact manner, particularly with respect to analyte and interfering ions of different charge. The expression obtained corresponds to the matched potential method proposed previously by Christian and co-workers on the basis of solely empirical observations. Selectivity coefficients required for a given analytical problem with a predefined maximum error can now be predicted more accurately. Such predictions with respect to analyte and interfering ions of varying charges differ by 1-2 orders of magnitude in comparison to the selectivity values required on the basis of the extended Nicolsky-Eisenman formalism.

Electrochemistry↗
PubMed1994

Response mechanism of polymer membrane-based potentiometric polyion sensors.

The potentiometric response mechanism of a previously reported polymer membrane-based electrode sensitive to the polyanion heparin is established. Based on transport and extraction studies, the heparin response is attributed to a nonequilibrium change in the phase boundary potential at the sample/membrane interface. While true equilibrium polyion response, obtained for low heparin concentrations only after very long equilibration times (> 20 h), yields the expected Nernstian response slope of < 1 mV/decade, the observed large and reproducible EMF response to clinically relevant heparin concentrations (approximately 10(-7) M) during typical measurement periods (2-5 min) is ascribed to a steady-state kinetic process defined by the flux of the polyion both to the surface and into the bulk of the polymer membrane. A model describing this nonequilibrium response is presented. With this model, the uniqueness of the polymer membrane composition (e.g., very low plasticizer content, strictly controlled cationic site concentration, etc.) required to achieve analytically useful heparin response becomes clear. Practical working conditions and limitations of the sensor are discussed. To support the generality of the steady-state model proposed, corresponding EMF response data for a newly developed membrane electrode sensitive to a polycationic protein (protamine) are also presented. It is shown that the protamine-responsive membrane electrode appears to operate via the exact same kinetic mechanism as the heparin sensing system.

Biosensing Techniques↗
PubMed1994

The apolipoprotein E epsilon 4 allele does not influence the clinical expression of the amyloid precursor protein gene codon 693 or 692 mutations.

In 31 symptomatic and 5 asymptomatic carriers of the amyloid precursor protein (APP) gene codon 693 mutation, 10 family members without mutation, and 5 carriers of the APP gene codon 692 mutation (3 with early-onset Alzheimer dementia, 2 with cerebral hemorrhage), a high frequency of the apolipoprotein E epsilon 4 allele was found. Age at onset, age at death, occurrence of dementia, and number of strokes did not differ between APP gene mutation carriers with or without epsilon 4 allele, showing that the clinical expression of these APP mutations is not influenced by the apolipoprotein E gene.

Adult↗
PubMed1994

First-trimester prenatal diagnosis in twin pregnancies.

Two twin pregnancies at risk for a sex-linked disorder are described. Both pregnancies were dichorionic. Transabdominal sampling was chosen for prenatal diagnosis. Molecular genetic techniques raised suspicion with regard to the accuracy of the samples in one case. Second-trimester amniocentesis confirmed the error. Selective feticide of the affected fetus was performed. When first-trimester prenatal diagnosis is offered in dichorionic twin pregnancies, confirmation through molecular genetic testing can confirm that villi have been obtained from different fetuses. All parties must be aware that additional invasive diagnostic procedures in the second trimester may be required in cases of doubt.

Adult↗