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Biomedical subjects

C E Voorter

Publications and source records attributed to C E Voorter.

At least 19 recordsLinked to original sources
PubMed2000

Presence of the DRB4*0103102N null allele in different DRB1*04-positive individuals.

The DRB4 gene encoding the DR53 antigen is present in DRB1*04-, DRB1*07- and DRB1*09-positive individuals. Eight allelic variants of DRB4 have been recognized, 5 resulting in an expressed DR53 antigen and 3 belonging to the null alleles. So far the DRB4*0103102N null allele had been found exclusively in individuals carrying the haplotype DR7,-DQ9. High-resolution typing of HLA class II by polymerase chain reaction using sequence-specific primers (PCR-SSP) and/or sequence-based typing of kidney patients and their families revealed the presence of the DRB4*0103102N null allele segregating with DRB1*04 and DQB1*03 in 4 different families. Three different haplotypes on which the null allele was located, were recognized by family studies: DRB1*0401, DQB1*0301; DRB1*0402, DQB1*0302 and DRB1*0404, DQB1*0302. Determination of the DR53 specificity of antisera reacting with DR53-positive individuals has always been difficult due to the simultaneous presence of DR4, 7 or 9. Identification of DR4-positive DR53-negative individuals as described here, provided the serological reactions with DR53-antisera and revealed the antibody specificities in the antisera used.

Alleles↗
PubMed2000

Strong association between HLA-Cw*0706 and HLA-B*44032 in the Bubi population from Equatorial Guinea.

Unrelated Bubi, native to the island of Bioko (Equatorial Guinea), were previously typed by low-resolution polymerase chain reaction using sequence-specific primers (PCR-SSP) and serology for HLA-A, -B and -C. HLA-B*44 was found frequently and associated with Cw*07. We have studied the HLA subtypes of 20 B*44pos/Cw*07pos Bubi individuals. HLA-B and -C were typed by sequencing exons 2 and 3. To distinguish the alleles Cw*1701/02/03, Cw*07011/012/06 and Cw*1801/02 additional sequencing of exon 1 or 5 was performed. All 20 B*44pos/Cw*07pos individuals of the Bubi population were typed Cw*0706 positive. Nineteen of them carried the B*44032 allele and one B*4407. In addition, 19 B*44neg/ Cw*07pos Bubi individuals were typed for HLA-C and none of them proved Cw*0706 positive. To determine whether the association between Cw*0706 and B*44032 was limited to the Bubi, 19 individuals from Dutch Caucasian families were typed in which B44 and Cw7 segregated on one haplotype. None of these individuals showed the presence of B*44032 or Cw*0706. The haplotypes found in the Dutch Caucasians were B*4402-Cw*0704, B*44031-Cw*07011 and B*44031-Cw*0702. The present observation indicates a strong association between B*44032 and Cw*0706 in the Bubi population.

Alleles↗
PubMed2000

DPB1*8501, a novel DPB1 variant in the US Black population.

We describe a new DPB1 allele, DPB1*8501, which was identified by sequencing-based typing (SBT) in the UCLA exchange. DPB1*8501 is similar to DPB1*2701 with a difference at position 272, (G to A). This difference leads to an amino-acid change of codon 91 from arginine (CGC) to histidine (CAC). Until now this position has been considered conserved. This substitution is located at the 3' site of exon 2, and may interfere with typing strategies using primers or probes located in this region.

Alleles↗
PubMed1999

There is more to HLA-C than exons 2 and 3: sequencing exons 1, 4 and 5.

HLA-C was shown to be a highly polymorphic gene which can be accurately typed for by sequencing methodologies. Most HLA-C sequence-based typing protocols described so far are based on analysis of sequence data of exons 2 and 3. Nonetheless, exons 1, 4 and 5 also contain nucleotide substitutions which contribute to the polymorphisms of the HLA-C locus. Ten alleles contain polymorphic positions in exons 1, 4 and 5, Cw*0701/06, Cw*1202112, Cw*15051/2, Cw*1701/02, and Cw*1801/02. Here we describe a reliable solid-phase sequence-based typing strategy for sequencing exons 1, 4 and 5, which is an extended protocol of our previous HLA-C study. A panel of 16 individuals, carrying 27 different Cw-alleles, was typed for exons 1, 4 and 5 to check the newly designed primers. No allelic dropout or preferential amplification was noticed in these individuals. The panel was also sequenced in order to check the known polymorphisms present in exons 1, 4 and 5. For exon 5 the sequences of the alleles Cw*0302, *0501 and *07011 did not correspond with the published data. In addition, exons 1, 4 and 5 were sequence-based typing typed in 28, 17 and 59 individuals, respectively. Two new alleles were detected which contain polymorphic positions outside exons 2 and 3, Cw*07012 and Cw*1703. The unknown sequence data of exons 1, 4 and 5 of the alleles Cw*02024, *0308, *1506 and *16041 were elucidated. The described high-resolution sequence-based typing protocol for sequencing exons 1, 4 and 5 will be a valuable tool to study the HLA-C locus for polymorphisms outside exons 2 and 3 and for identification of the presently known HLA-C alleles with polymorphic positions in these exons.

Base Sequence↗
PubMed1998

Helper and cytotoxic T cell precursor frequencies are not predictive for development of acute graft-versus-host disease after partially T cell-depleted HLA-identical sibling BMT.

Despite the use of partially T cell-depleted grafts, 20% of the recipients of an HLA-identical sibling marrow graft develop aGVHD > or = II. This indicates that the current method for selecting a sibling donor, ie serological typing for HLA-A, B and DR, and a mixed lymphocyte culture (MLC) or molecular typing for HLA-DRB/DQB, is not predictive for aGVHD. In order to optimise our selection procedure, we retrospectively analysed patients who developed aGVHD > or = II by means of sequencing based typing for HLA-DPB and frequency analysis of alloreactive helper and cytotoxic T lymphocyte precursors (HTLp-f and CTLp-f). Patients who did not develop aGVHD or developed aGVHD grade I served as controls. Retrospective typing for HLA-DPB revealed only a single disparity in the group with aGVHD > or = II, indicating that mismatches for antigens other than HLA are the major cause of aGVHD in these patients. Furthermore, in our patient group, neither HTLp-f nor CTLp-f were predictive for development of aGVHD indicating that these assays in their current set-up are insufficiently sensitive to predict aGVHD in BMT with a partially T cell-depleted graft. We conclude, that HLA-identical siblings can be identified by means of serological typing for HLA-A and B and intermediate resolution molecular typing for DRB and DQB, but that for the prediction of aGVHD cellular tests with higher sensitivity and specificity as compared to the currently used HTLp-f and CTLp-f assays need to be developed.

Acute Disease↗
PubMed1998

High-resolution HLA typing for the DQB1 gene by sequence-based typing.

The ideal high-resolution typing strategy for polymorphic genes is sequence-based typing. SBT of genomic DNA has been developed for the HLA class II genes DRB1, DRB3/4/5 and DPB1. For the DQB1 gene the sequence-based typing method was shown to cause a number of problems. To resolve those problems, different primers to amplify and sequence exon 2 of DQB1 were designed and tested. With several primer combinations, preferential amplification was observed in individuals heterozygous for DQB1*02/*03 and DQB1*02/*04. The preference was for DQB1*02 in many instances but could also be demonstrated for DQB1*03 or *04 and resulted occasionally in allelic drop-out. The best primer combination was selected and successfully used to type individuals heterozygous for DQB1*02, *03 and *04. To distinguish DQB1*0201 and *0202, primers for amplification and sequencing of exon 3 were developed and correct subtyping was obtained. The ambiguous typing DQB1*0301/*0302 and DQB1*0303/*0304 was resolved by allele-specific amplification and sequencing. A total of 258 individuals were fully typed for their DQB1 subtypes. All samples had been previously typed by PCR-SSP and serology. Concordant typing results were obtained for all individuals tested. The DQB1 alleles detected included *0501, *0502, *0503, *0601, *0602, *0603, *0604, *0609, *0201, *0202, *0301, *0302, *0303, *0304, *0401 and *0402. Sequence-based typing of the DQB1 gene proved a reliable typing strategy for assignment of the different DQB1 alleles after intensive selection of primers and test conditions.

DNA Primers↗
PubMed1998

A reliable and efficient high resolution typing method for HLA-C using sequence-based typing.

Serological typing of HLA-C has been poor and almost half of its alleles are serologically undetectable blanks in most populations. Therefore, DNA typing techniques have been used to identify and type for the HLA-C gene. Sequence-based typing (SBT) has proven a major typing strategy for highly polymorphic HLA genes. The technique enables direct identification of all sequence motifs without the need to continuously adjust primers. Here we describe a reliable solid-phase SBT strategy for HLA-C which can be used to distinguish all currently known HLA-C alleles without prior knowledge gained by low resolution typing. Exons 2 and 3 were amplified and sequenced and if necessary sequences of exons 1 and 5 were determined. A total of 257 individuals were typed for HLA-C using this protocol and 30 of the 42 known HLA-C alleles were detected. All heterozygous combinations found in this study were unambiguously discriminated. One hundred and forty-four individuals from the Dutch population were typed randomly. In this group Cw*0701 and *0702 were the most frequently detected alleles. Of the serological Cw blank alleles Cw*1203 was found to have the highest frequency (16%). From the total group 212 individuals were typed serologically and 106 were retyped with 97 selected antisera to further compare serological and molecular defined phenotypes. Discrepancies between serological typing and SBT are mainly attributable to the serologically Cw blank alleles Cw*12-18. The high resolution SBT protocol described will be a valuable tool for the identification of HLA-C alleles and the determination of the role of HLA-C in marrow and organ transplantation.

Alleles↗
PubMed1997

Comparison of DRB sequence-based typing using different strategies.

Sequence-based typing (SBT) has become an important tool in the identification of HLA alleles. In this study a comparison was made between SBT of DRB1/3/4/5 alleles performed in two laboratories each using a different strategy for SBT. The laboratories in Utrecht and in Maastricht performed direct sequencing of PCR amplified genomic DNA from 30 selected samples. Primers and conditions for PCR amplification were different. Sequencing was either performed with T7 polymerase, using internal sequencing primers, or with cycle sequencing using an M13 tailed system. Two different automated DNA sequencers were used; the ALFexpress from Pharmacia and Applied Biosystems 373A. We concluded that nor the method of sequencing nor the sequencing machine influences typing results. However the PCR reaction used for generating template DNA is the most critical step. Different primers and different conditions can lead to false negative reactions. The fact that these false negative reactions can occur with different alleles in different combinations but not in all, implicates that extensive quality control is needed to assure correct typing results.

HLA-DR Antigens↗
PubMed1997

High-resolution HLA typing for the DRB3/4/5 genes by sequence-based typing.

The high degree of polymorphism of the HLA genes at the nucleotide sequence level has proven sequence-based typing a major typing strategy. For DRB1 the allelic variability is predominantly present in the second exon and by DNA sequencing of exon 2 all hitherto known DRB1 alleles can be detected. For the associated genes DRB3, DRB4 and DRB5 the situation is slightly different. Allelic differences are not limited to exon 2 and the sequence of exon 3 and sometimes exon 4 is needed for complete subtyping. Oligonucleotides to amplify the exons needed for subtyping of DRB3, DRB4 and DRB5 were designed. Gene-specific products were generated to make simultaneous detection of alleles in heterozygous combinations possible. In this way 238 individuals were fully typed for their DRB3, 4 and 5 subtypes. Additional samples were typed for only one of the genes. All samples had been previously typed by PCR-SSP. Concordant typing results were obtained for all individuals tested. The DRB3 alleles typed for included *0101, *0201, *0202 and *0301, for DRB4 they were *01011, *0102 and *0103 and for DRB5 *0101, *0102, *0103, *0105, *0201, *0202 and *0203. All alleles were easily detected by the protocol described except for DRB5*0201. Sequencing of exon 3 and 4 of the DRB5*0201 allele showed this allele to be a sequencing error and the sequences obtained were identical to the exon 2, 3 and 4 sequences of DRB5*0202. Two new alleles were identified in the samples studied, DRB4*0105 and DRB3*0207. Sequence based typing has been recognized as a valuable tool for HLA typing of DRB1, DQB1 and DPB1 since several years. It is shown to be a superior typing method as well in the detection of the different DRB3, 4 and 5 subtypes.

Alleles↗
PubMed1997

The absence of DR51 in a DRB5-positive individual DR2ES is caused by a null allele (DRB5*0108N)

DR51, a protein encoded by the DRB5 gene, was shown to be present in almost all DR2-positive haplotypes. Exceptions were reported, some DR2-negative samples were shown to be DR51 positive and in a number of DR2-positive samples no DR51 antigen could be demonstrated. In some of them lack of the DRB5 gene was the cause of the absence of DR51 but in others the DRB5 gene was present without resulting in a detectable gene product. Many of these variants were studied in detail in previous international workshops. One of them was DR2ES from our laboratory. She is a DR15-positive DR51-negative individual of oriental origin with a clearly demonstrable DRB5*01 allele when typed by molecular techniques. To unravel the molecular mechanism responsible for the defect in expression, cDNA and DNA encoding the defective DRB5 allele were analyzed. Nucleotide sequence analysis of exon 2 showed no differences from the sequence of DRB5*0102. However, when exon 3 was examined a difference in length was noticed due to a deletion of 19 nucleotides between codon 161 and 168. The deletion caused a frameshift and a premature stopcodon resulting in a null allele. The same allele could be demonstrated in 6 other unrelated individuals of oriental origin as well as in 5 individuals from South Africa. The absence of the DR51 protein was explained by the presence of an alteration in the DRB5 allele resulting in a null allele. The allele has been officially named DRB5*0108N. This is the first description of a null allele of the DRB5 gene.

Alleles↗
PubMed1997

Identification of a new DRB3*02 allele (DRB3*0207) by sequence-based typing.

A new DRB3*02 allele (DRB3*0207) was detected in a female Luxembourg Caucasian blood donor by sequence-based typing. The new allele differs from DRB3*0202 by two substitutions in codon 57 resulting in an amino acid change from a charged aspartic acid to a neutral valine. This is the first example of a DRB3 allele pair differing only at codon 57.

Alleles↗
PubMed1996

Loss of chromosome 11 and 11 p/q imbalances in bladder cancer detected by fluorescence in situ hybridization.

To identify chromosomal imbalances in non-diploid transitional-cell carcinoma (TCC) of the bladder we performed double-target in situ hybridization (FISH), using the centromeric probe for chromosome 11 together with 2 cosmid probes located on the 11p and 11q arm in the proximity of the telomere. The FISH protocol was optimized to ensure a highly efficient and reproducible detectability of all 3 targets. As a consequence, it was possible to calculate ratios between the number of spots obtained with cosmid and centromere probes. Furthermore, the number of chromosomes 11 present was compared with the DNA index and the chromosome ploidy as obtained with other chromosome centromere probes. In this study we found that: (i) in 54 diploid TCCs a monosomy for chromosome 11 was detected in only one case; (ii) chromosome 11 was completely lost in 9 of 16 non-diploid TCCs; (iii) in 8 of these 16 non-diploid tumors an imbalance was observed between the 11p and 11q arm, in 4 of these cases a complete loss of chromosome 11 being observed in addition; (iv) the copy number counted for 11q was always identical to the 11 centromere number, except in one case, indicating a loss of 11p in the cases with imbalances. In total, 13 of 16 non-diploid TCCs (81%) showed either a loss of a complete chromosome 11, of (part of) the 11p arm, or both. Therefore we concluded that during tetra- or aneuploidization in TCCs, (part of) chromosome 11 is lost. In addition, our results indicate that under-representation of chromosome 11p occurs in the majority of the tumor cells, supporting the idea that loss of these sequences is an important step in the development of TCC.

Chromosomes, Human, Pair 11↗
PubMed1994

Elastase inhibition by the C-terminal domains of alpha-crystallin and small heat-shock protein.

alpha-Crystallin, an abundant eye-lens protein and a stress protein in other tissues, shows structural and functional similarities with the small heat-shock proteins. One of the properties in common is the inhibition of elastase. We now report that the separated subunits of alpha-crystallin, alpha A and alpha B, also exhibit elastase inhibition, whereas phosphorylation of these subunits apparently has no influence on the inhibitory capacity. Furthermore, for both alpha A-crystallin and mouse HSP25 the putative C-terminal structural domain, comprising the major region of homology between these proteins, is sufficient to give elastase inhibition. With database search no homology could be found between the three proteins under investigation and any of the known consensus sequences of proteinase inhibitor families.

Amino Acid Sequence↗
PubMed1994

The developmental expression of taxon-specific crystallins in the duck lens.

The three crystallins, alpha B-crystallin, tau-crystallin/alpha-enolase and epsilon-crystallin/lactate dehydrogenase B are all stress induced proteins and may thus share common regulatory elements. However, no evidence was found for coordinate expression of these three genes during duck lens development. The alpha B- and alpha-enolase/tau-crystallin mRNAs accumulate with similar kinetics between day 12 and day 24 of embryonic development but differ in their epithelial versus fibre cell location; the LDH-B/epsilon-crystallin transcript shares its preferential location in the fibre cell with alpha B-crystallin but differs in its developmental pattern of expression. The accumulation of LDH-B/epsilon-crystallin mRNA in heart and lens followed a similar developmental pattern. In contrast, the alpha-enolase/tau-crystallin mRNA level in heart decreases while the level in lens rises. The LDH-B gene is used as a crystallin gene in duck but not in chicken. This species-specific difference may correlate with the difference in LDH-B activity between various chicken and duck tissues: the retina and pancreas in duck have significantly higher LDH-B activity than in chick, while heart, muscle, stomach, liver, intestine and kidney all have much higher LDH-B activity in chicken than in duck.

Animals↗
PubMed1994

Expression of alpha B-crystallin in Alzheimer's disease.

alpha B-crystallin is a member of the small heat-shock protein family. Under pathological conditions, the expression of alpha B-crystallin increases in proliferating astrocytes, which suggests that this protein, in addition to glial fibrillary acidic protein (GFAP), can be a marker for gliosis in neurodegenerative diseases. Immunoblotting and immunohistochemical methods were used for the detection of alpha B-crystallin in the brains of Alzheimer's disease (AD) patients and nondemented controls. An increase in alpha B-crystallin expression was found in the brains of AD patients. Immunoreaction was present in reactive astrocytes, microglia, and oligodendrocytes, indicating that all types of glia respond to the stress associated with AD pathology. Colocalization of GFAP and alpha B-crystallin was found in fibrous astrocytes. However, the intensity and range of alpha B-crystallin expression appeared to be limited as compared with the large increase in the number of GFAP-positive astrocytes. This indicates that expression of alpha B-crystallin is not a marker for gliosis in AD. Immunoreactivity to alpha B-crystallin in both astrocytes and microglia was found mainly restricted to areas with senile plaques and neurofibrillary tangles, suggesting the association of alpha B-crystallin with amyloid deposition in AD.

Aged↗