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Biomedical subjects

Y M Lo

Publications and source records attributed to Y M Lo.

At least 73 records · Page 4Linked to original sources
PubMed1997

Presence of fetal DNA in maternal plasma and serum.

BACKGROUND: The potential use of plasma and serum for molecular diagnosis has generated interest. Tumour DNA has been found in 'the plasma and serum of cancer patients, and molecular analysis has been done on this material. We investigated the equivalent condition in pregnancy-that is, whether fetal DNA is present in maternal plasma and serum. METHODS: We used a rapid-boiling method to extract DNA from plasma and serum. DNA from plasma, serum, and nucleated blood cells from 43 pregnant women underwent a sensitive Y-PCR assay to detect circulating male fetal DNA from women bearing male fetuses. FINDINGS: Fetus-derived Y sequences were detected in 24 (80%) of the 30 maternal plasma samples, and in 21 (70%) of the 30 maternal serum samples, from women bearing male fetuses. These results were obtained with only 10 microL of the samples. When DNA from nucleated blood cells extracted from a similar volume of blood was used, only five (17%) of the 30 samples gave a positive Y signal. None of the 13 women bearing female fetuses, and none of the ten non-pregnant control women, had positive results for plasma, serum or nucleated blood cells. INTERPRETATION: Our finding of circulating fetal DNA in maternal plasma may have implications for non-invasive prenatal diagnosis, and for improving our understanding of the fetomaternal relationship.

Case-Control Studies↗
PubMed1996

Two-way cell traffic between mother and fetus: biologic and clinical implications.

The bilateral trafficking of nucleated cells between the fetus and the mother was studied using polymerase chain reaction (PCR)-based systems sensitive enough to detect 1 target cell in 100,000 background cells. Sixty-six mother-baby pairs were recruited; maternal and cord blood samples were collected at delivery for DNA extraction. Cell trafficking was studied in informative cases using PCR-genotyping of polymorphic regions in the beta-globin cluster, the glutathione S-transferase M1 locus and the angiotensin converting enzyme gene. In addition, Y-PCR was also used in conjunction with these systems for the detection of fetal cells in maternal circulation. Fetal cells were detected in maternal peripheral blood in 26 of 51 cases whereas maternal cells were detected in 16 of 38 fetal umbilical cord blood samples. The proportion of umbilical samples with detectable maternal sequences was much higher than previously reported. In the 28 cases informative for both mother and baby, there was no obvious correlation between the cell traffic from mother to baby as compared to that from baby to mother. These findings may have implications for the use of cord blood for bone marrow transplantation, the vertical transmission of infectious agents, and the physiology of the feto-maternal relationship.

Blood Cells↗
PubMed1996

High prevalence of a missense mutation of the glucokinase gene in gestational diabetic patients due to a founder-effect in a local population.

A high proportion of the female patients who are members of maturity onset diabetes of the young (MODY) pedigrees, and whose diabetes mellitus is due to a glucokinase mutation, originally presented with gestational diabetes. To establish whether glucokinase mutations could be a common cause of gestational diabetes, we studied 50 subjects who presented with gestational diabetes and on follow-up had hyperglycaemia (5.5-10.0 mmol/l). Screening for glucokinase mutations using single-stranded conformational polymorphism (SSCP) analysis detected a missense mutation at position 299 (Gly299-->Arg) in three subjects. As two pedigrees in the Oxford area had the same glucokinase mutation, we suspected the role of a founder-effect, and carried out pedigree extension, haplotype construction (using microsatellite markers GCK1 and GCK2) and mutation screening of at-risk subjects from the same geographical area. One of the gestational diabetic subjects was found to be related to one of the previous pedigrees via her paternal grandmother. Subjects with the mutation were found to have the Z + 4/2 (GCK1/ GCK2) haplotype, suggesting that the observed high prevalence of the Gly299-->Arg glucokinase mutation in the Oxford region was due to a founder-effect. Since glucokinase mutations predominantly induce subclinical hyperglycaemia, it is likely that in the locality of other pedigrees there will be undiagnosed subjects with the same glucokinase mutation, which remains undetected unless pregnancy occurs.

Adult↗
PubMed1995

Application of a polymorphic Y microsatellite to the detection of post bone marrow transplantation chimaerism.

A highly sensitive Y-microsatellite amplification system was developed for the detection of post bone marrow transplantation (BMT) chimaerism. The system is able to detect the DNA equivalent of a single male cell in a background of 10(5) female cells. For clinical applications it has the distinct advantage that the polymorphic nature of the PCR product allows the checking of the genuineness of a positive PCR signal by reference to its allelic type. This extra degree of precision enhances the accuracy of Y-PCR for clinical diagnosis.

Alleles↗
PubMed1995

Detection of NPM-ALK DNA rearrangement in CD30 positive anaplastic large cell lymphoma.

CD30 positive anaplastic large cell lymphoma (ALCL) is a type of non-Hodgkin's lymphoma associated with a specific chromosome translocation between chromosomes 2 and 5. Recent molecular characterization of the translocation breakpoint has identified a gene fusion between NPM (nucleophosmin) and ALK (anaplastic lymphoma kinase). Using a DNA hybridization technique, the NPM rearrangement was found among 5/5 ALCL samples. We have developed a PCT methodology which has enabled the detection of the NPM-ALK rearrangements amongst seven t(2;5)(p23;q35) ALCL cases based on a long-range PCR of genomic DNA. The rapidity and robustness of this method may have diagnostic applications for ALCL.

Anaplastic Lymphoma Kinase↗
PubMed1995

HLA typing for DR3 and DR4 using artificial restriction fragment length polymorphism PCR from archival DNA.

AIM: To develop polymerase chain reaction based artificial restriction fragment length polymorphism (artificial RFLP PCR) assays for DR3 and DR4 alleles of the multiallelic DRB1 locus and to apply them to paraffin wax embedded archival material. METHODS: Sixty five samples from DRB1 typed cell lines were analysed using the artificial RFLP PCR method to determine the specificity and sensitivity of the system. RESULTS: The artificial RFLP PCR method for typing the DRB1 locus showed 100% accuracy in the 65 samples previously typed using allele specific PCR and serology. The samples included 18 combinations of alleles that included DR3, 18 that included DR4, four that were DR3/DR4 heterozygotes, and 10 samples that were neither DR3 nor DR4. Typing of 10 paraffin wax embedded samples using artificial RFLP PCR was in complete agreement with previous typing at the DRB1 locus. CONCLUSION: The application of artificial RFLP PCR for the analysis of multiallelic loci, such as those of the HLA system, in archival DNA samples has been achieved. Artificial RFLP PCR is a robust, easily implemented, non-isotopic system and may be useful for large retrospective studies.

Alleles↗
PubMed1994

Prenatal determination of fetal rhesus D status by DNA amplification of peripheral blood of rhesus-negative mothers.

We have developed a sensitive PCR-based assay for the RhD gene and used it to detect circulating fetal cells from RhD-positive fetuses from peripheral blood of RhD-negative mothers. With further improvement in diagnostic accuracy, this assay may have implications in the management of RhD-sensitized pregnancies in women whose partners are heterozygous for the RhD gene. Further studies are required to determine the relationship between maternal anti-D levels and circulating fetal cell numbers.

Amniotic Fluid↗
PubMed1994

HLA DR4 is a marker for rapid disease progression in primary sclerosing cholangitis.

BACKGROUND/AIMS: Primary sclerosing cholangitis (PSC) is an inflammatory disease of the biliary tree associated with an increase in the HLA alleles DR3, DR52a, DR2, Dw2, and a decrease in DR4. However, it is not certain which of these alleles provides the primary associations. Our aim was to establish the primary HLA associations with PSC and to assess the ability of HLA alleles to mark for disease progression. METHODS: By applying molecular techniques to archival tissue, we have genotyped 83 PSC patients from two populations and 131 controls for the alleles HLA DR2, DR3, DR4, DRw12, DR52a, and Dw2. RESULTS: HLA DR3, DR52a, DR2, and Dw2 were all significantly increased in PSC, with the relative risk for DR52a and Dw2 being greater than for DR3 and DR2, respectively. HLA DR4 was significantly decreased, but this may be artifactual to the DR3, DR2 increase. HLA DR4 and not DR52a marks for rapid disease progression in both our PSC populations. CONCLUSIONS: HLA DR52a and Dw2 are the best candidate alleles for providing the known HLA association with PSC. HLA DR4 and not DR52a marks for rapid disease progression in our two PSC populations.

Amino Acid Sequence↗
PubMed1994

Detection of fetal RhD sequence from peripheral blood of sensitized RhD-negative pregnant women.

A sensitive PCR-based assay was developed to amplify fetal-derived rhesus D (RhD) sequence from peripheral blood of RhD-negative pregnant women with circulating anti-D. RhD-PCR positivity was detected in 7/22 samples from women bearing RhD-positive fetuses, despite the presence of varying levels of anti-D. Evidence is presented which suggests that rising maternal anti-D levels might reduce circulating fetal cell numbers. Further development of this assay may have implications in the clinical management of RhD-sensitized pregnancies and aid the understanding of the physiology of feto-maternal cell trafficking.

Base Sequence↗