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D Middleton

Publications and source records attributed to D Middleton.

At least 73 records · Page 4Linked to original sources
PubMed1999

History of DNA typing for the human MHC.

The last twenty years have seen an exponential growth in the application of DNA technology to the field of Histocompatibility and Immunogenetics (H&I). Initially, this was confined to a few research laboratories. However, the development and application of several different DNA methods by many laboratories has led to the situation whereby nearly every H&I laboratory performs some DNA typing for the detection of HLA alleles. It would not be unfair to say that H&I has shown diagnostic laboratories in other disciplines how useful the DNA techniques can be. This review attempts to summarise the history and application of DNA methods in the field of Histocompatibility (Table 1).

DNA↗
PubMed1998

Mutation screening in exons 3 and 4 of alpha-synuclein in sporadic Parkinson's and sporadic and familial dementia with Lewy bodies cases.

Recently it has been reported that a missense G(88)C mutation within exon 3 and a missense G(209)A mutation within exon 4 of the alpha-synuclein gene were linked to familial Parkinson's Disease (PD). We decided to investigate if these and any other mutations in exons 3 and 4 of the alpha-synuclein gene could be detected in sixty two sporadic PD and dementia with Lewy bodies (DLB) patients. Four cases of familial DLB were also studied, two of which were from the same family. Single stranded conformational polymorphism, DNA sequencing analyses and PCR-RFLP of exons 3 and 4 failed to reveal any nucleotide changes. However, three nucleotide differences occurred in the intron 4 sequence compared to the published sequence. This study adds further support to the idea that these particular mutation in the alpha-synuclein gene are a rare case of PD and now, as we have shown here, also of DLB.

Dementia↗
PubMed1998

Aggregates from mutant and wild-type alpha-synuclein proteins and NAC peptide induce apoptotic cell death in human neuroblastoma cells by formation of beta-sheet and amyloid-like filaments.

Alpha-synuclein (alpha-syn) protein and a fragment of it, called NAC, have been found in association with the pathological lesions of a number of neurodegenerative diseases. Recently, mutations in the alpha-syn gene have been reported in families susceptible to an inherited form of Parkinson's disease. We have shown that human wild-type alpha-syn, mutant alpha-syn(Ala30Pro) and mutant alpha-syn(Ala53Thr) proteins can self-aggregate and form amyloid-like filaments. Here we report that aggregates of NAC and alpha-syn proteins induced apoptotic cell death in human neuroblastoma SH-SY5Y cells. These findings indicate that accumulation of alpha-syn and its degradation products may play a major role in the development of the pathogenesis of these neurodegenerative diseases.

Amyloid↗
PubMed1998

An interluekin 1B allele, which correlates with a high secretor phenotype, is associated with diabetic nephropathy.

Induction of interleukin 1 activates vascular endothelial and kidney mesangial cells, and increases production of type IV (basement membrane) collagen. Hence, genes within the interleukin 1 gene cluster are potential candidates in the pathogenesis of diabetic nephropathy. In a previously validated case-control study from Northern Ireland, consisting of 95 patients with insulin-dependent (type 1) diabetes and nephropathy (cases) and 96 patients with insulin-dependent (type 1) diabetes without nephropathy (controls), the authors performed PCR-based genotyping of specific DNA polymorphisms within the interleukin 1A, interleukin 1B, interleukin 1 (type 1) receptor and interleukin 1 receptor antagonist genes. The groups were matched for age at onset and duration of diabetes. A statistically significant increase was found in the allele frequency of the interleukin 1B*2 allele in cases compared to controls (chi2=7. 19, df.=1; P=0.007, Pcorr=0.028). The results of this study suggest that the interleukin 1B*2 allele, or a susceptibility factor in linkage disequilibrium with this allele, is associated with diabetic nephropathy in the Northern Ireland population.

Alleles↗
PubMed1998

HLA-A towards a high-resolution DNA typing.

Sequencing-based typing (SBT) and sequence-specific oligonucleotide probing (PCR-SSOP) are DNA-based typing approaches to identify HLA-A alleles. In this study PCR-SSOP SBT have been evaluated and considered to reach a high-resolution typing. Based upon serological typing, 32 genomic samples were typed by SBT and PCR-SSOP Three main clusters of resolution could be defined. The advantage of the PCR-SSOP approach is the possibility to type numerous samples in a short time. SBT minimizes the number of ambiguous heterozygous combinations and often allows direct detection and identification of new alleles.

DNA↗
PubMed1998

Detection of HLA-A*24 null alleles by DNA typing methods.

A number of cases have been identified (seven unrelated individuals from the Northern Ireland bone marrow donor registry and two family groups) where an HLA-A*24 allele fails to express the normal HLA-A24 antigen. Family information has revealed common haplotypes with respect to each non-expressed allele indicating that the occurrence of these mutations has been a recent event. Two methods for the clinical typing of these alleles have been evaluated--PCR-SSOP and PCR-SSCP analysis.

Base Sequence↗
PubMed1998

High incidence of the Cys 282 Tyr mutation in the HFE gene in the Irish population--implications for haemochromatosis.

A simple PCR-SSOP approach based on a single PCR product has been developed to screen the HFE gene for the haemochromatosis-associated mutations Cys 282 Tyr and His 63 Asp. Using this approach the prevalence of these mutations in a cohort (30) of haemochromatosis patients and normal controls (404) was determined. Ninety percent of the haemochromatosis patients were homozygous for the Cys 282 Tyr mutation. In the normal population we found an increased incidence of the Cys 282 Tyr mutation (17.3%; 95% confidence limits 0.136-0.209) which was also reflected in the higher frequency of Cys 282 Tyr homozygotes (1.24%; 95% confidence limits 0.0016-0.0232). Linkage disequilibrium analysis confirmed the association between A*03 and Cys 282 Tyr. However, strong linkage disequilibrium occurred with the HLA-A*03-associated allele HLA-B*14 but not the HLA-A*03-associated allele HLA-B*07. The His 63 Asp was found to be in linkage disequilibrium with HLA-A*29.

Cysteine↗
PubMed1997

The distribution of Anoplocephala perfoliata in the intestine of the horse and associated pathological changes.

The intestinal tracts of 130 horses were examined for infection with Anoplocephala perfoliata at necropsy. Fifty horses (38.5%) harboured the tapeworm, and the site of attachment of each worm was recorded using predetermined anatomical landmarks. The worms were attached in four regions of the gastrointestinal tract: 17% of the worms were found at the ileocaecal junction, 81% on the caecal wall, 1.7% in the terminal ileum and 0.2% in the ventral colon. The severity of lesions produced at the sites of attachment was related to the number of worms attached. Due to the small area of the ileocaecal junction, worms at this site were attached in close proximity, resulting in more severe lesions. The major features of the lesions included ulceration, diphtheritic membranes and thickening of the mucosa, submucosa and lamina propria. There was an increase in the number of eosinophils and a decrease in the number of lymphocytes present at the sites of lesions.

Animals↗
PubMed1997

Natural inactivation of a common HLA allele (A*2402) has occurred on at least three separate occasions.

HLA-A*2402 is common and widely distributed in human populations. Several individuals were identified who type genotypically for A*2402, but are serologically null for the HLA-A24 Ag. Sequencing and transfection of genomic DNA fragments containing null and wild-type A*2402 alleles, and the related A*2301 allele, revealed three different null alleles (A*2409N, A*2411N, and A*2402(low)), each of which differs from A*2402 by a single nucleotide change within the 6.7-kb sequence. The A*2301 and A*2402 sequences differ by no substitutions additional to those previously determined for the 1.1-kb cDNA. In exon 4, A*2409N has an in-frame stop codon, while A*2411N has a nucleotide insertion that alters the reading frame, causing premature termination. A*2402(low) has a nucleotide substitution near the splice acceptor site for intron 2 that impairs the production of correctly spliced mRNA. For A*2409N and A*2411N, mRNA is undetectable by Northern analysis, whereas A*2402(low) produces a low level of mRNA and a concomitant amount of normal A*2402 protein at the cell surface. The protein expressed from the A*2402(low) allele is sufficient to stimulate an alloreactive T cell response. On a background of unexpected sequence homogeneity, the single nucleotide changes in the A*2409N, A*2411, and A*2402(low) alleles have dramatic effects upon gene expression and are of likely importance for HLA matching in clinical transplantation. Segregation of at least three independently inactivated A*2402 alleles in human populations raises the possibility that loss of A*2402 may be the result of natural selection.

Alleles↗
PubMed1997

HLA-DR antigens associated with major genetic risk for late-onset Alzheimer's disease.

Hla-dr antigen types were determined from DNA isolated from post-mortem brain tissue of age-matched groups of 78 patients with pathologically confirmed late-onset Alzheimer's disease (AD) and 50 controls. The results suggest that for individuals with no apolipoprotein E epsilon 4 alleles the presence of either DR1, 2 or 3 antigens is associated with a significantly increased risk for development of late-onset AD. Conversely the DR4 or 6 antigens are associated with a decreased risk of similar magnitude. This DR effect, rather than prolonged use of non-steroidal anti-inflammatory drugs, could be responsible for the reported lower prevalence of AD in rheumatoid arthritis (a condition associated with an increased frequency of DR-4).

Age of Onset↗
PubMed1997

Application of an HLA-B PCR-SSOP typing method to a bone marrow donor registry.

A previously reported HLA-B PCR-SSOP typing method has been applied to those individuals, from the local bone marrow registry, with only one detectable HLA-B antigen by serology. The PCR-SSOP method detected the serologically defined HLA-B antigen in all cases. In addition, PCR-SSOP detected the presence of a second HLA-B allele in 19.9% of these individuals. The method was also applied to all individuals where serology could only determine the HLA-B antigen as a broad specificity. All antigens were split by the PCR-SSOP method, indicating that the method is more specific than serology. Using a combination of PCR-SSOP and serologically determined types for 5000 individuals on the local bone marrow registry, HLA-B frequencies for the Northern Ireland population have been calculated.

Alleles↗
PubMed1997

Development of PCR-SSOP for HLA-A typing of bone marrow registry donors.

A medium resolution PCR-SSOP typing method, using 26 digoxigenin labelled probes, has been established for the identification of HLA-A alleles. The system is capable of discriminating all of the serologically defined specificities except for eight heterozygous combinations which are however rare in Caucasians. The method has been applied to 1,838 individuals on the local bone marrow registry who either had only one detectable HLA-A antigen, or a HLA-A antigen whose presence had been queried using the serological technique or a broad HLA-A specificity assigned by the serological technique. In all but one case the serologically assigned antigens were detected with the PCR-SSOP method. In addition, PCR-SSOP detected the presence of a second HLA-A allele in over 10% of individuals who had been previously homozygous. Frequency information, based on a population of 5,000 individuals, has been established using a combination of molecular and serological typing data.

Bone Marrow↗
PubMed1997

Development of PCR-SSOP for the identification of HLA-A*02 subtypes and determination of HLA-A*02 frequencies within different ethnic populations.

A PCR-SSOP typing method, involving a single PCR amplification in conjunction with 19 digoxigenin labelled oligonucleotide probes, has been developed for the identification of 17 known HLA-A*02 alleles. The method has been applied to four populations (Northern Ireland, Singapore Chinese, Shetland Island and Mexican) and percentages of HLA-A*02 alleles determined within each population.

Alleles↗
PubMed1997

HLA class I DNA typing of 215 "HLA-A, -B, -DR zero mismatched" kidney transplants.

DNA typing for HLA class II improves the typing quality and this was shown previously to be relevant for kidney graft survival. In this project we addressed the question whether molecular typing for HLA class I also increases the efficacy of HLA matching in kidney transplantation. 215 HLA-A,-B,-DR zero-mismatched donor/recipient pairs as defined by serological typing were selected. Retrospective HLA-A and HLA-B typing was performed both by the PCR-SSP and the PCR-SSOP method. DNA typing for HLA-A revealed discrepant results to serology in 5.7% of the donors and 2.8% of the recipients. HLA-B typing discrepancies were found in 6.6% of the donors and 5.6% of the recipients. 10.4% of the donors and 6.5% of the recipients showed either an HLA-A or an HLA-B discrepancy Nearly one-third of the HLA-A discrepancies affected A19 splits. The most common reason for HLA-A discrepancies was the erroneous assignment of serological blanks, whereas HLA-B errors were caused mainly by the assignment of incorrect specificities. DNA typing allowed the definition of HLA-A and -B split specificities in all 118 "splitable" cases for which only broad specificities were reported based on serological typing. A total of 183 DNA class I compatible transplants had a 15% higher one-year graft survival rate than 32 transplants for which DNA typing revealed a class I incompatibility

DNA Probes, HLA↗