PubMed Health⌕ Search

Biomedical subjects

R Morgan

Publications and source records attributed to R Morgan.

At least 145 records · Page 8Linked to original sources
PubMed1994

DNA variants at the LPL gene locus associate with angiographically defined severity of atherosclerosis and serum lipoprotein levels in a Welsh population.

Coronary artery disease (CAD) patients (n = 235), comprising minimal (CAD-, n = 124) and severe (CAD+, n = 111) CAD, were recruited on the basis of their angiographic scores. Male control subjects (n = 123) were selected randomly from the Caerphilly Heart Study cohort. Subjects were genotyped for the Ser447-Ter mutation and HindIII/Pvu II restriction fragment length polymorphisms of the lipoprotein lipase gene and investigated for associations with severity and development of CAD and lipid and lipoprotein levels. The Ser447-Ter mutation showed no significant associations with CAD or dyslipidemia but was related to favorable lipid and lipoprotein profiles. The H2H2 genotype (P < .05) and H2 allele (P = .05) were significantly more frequent in CAD+ versus CAD- and control subjects versus CAD-. H2H2 subjects, among the entire male cohort, had significantly higher levels of apolipoprotein B (P = .0002), total cholesterol (P < .004), and triglycerides (P < .04) than alternative genotypes. P2P2 associated with significantly lower high-density lipoprotein cholesterol levels (P < .01). The H2 allele had most significant associations with raised apolipoprotein B levels compared with other biochemical parameters. Our data suggest that the H2 allele may be a linkage marker for an etiologic mutation for dyslipidemia and the severity and development of atherosclerosis; this is not the Ser447-Ter mutation.

Alleles↗
PubMed1994

Chromosome 4q locus associated with insulin resistance in Pima Indians. Studies in three European NIDDM populations.

Markers on chromosome 4q have recently been shown to be associated with insulin resistance in Pima Indians, a population in which insulin resistance precedes and predicts the development of non-insulin-dependent diabetes mellitus (NIDDM). To examine whether genes in this region could play a major role in susceptibility to NIDDM in other populations, we have examined the allele frequencies of a trinucleotide repeat near the fatty acid-binding protein 2 (FABP2) gene on 4q28-31 in three European populations: Finnish, U.K. Caucasian, and Welsh. The U.K. NIDDM population was selected for insulin resistance by studying patients whose obesity-corrected fasting plasma insulin before treatment was above the 98th percentile. Seven alleles were detected. On cross-tabulation analysis, there were no significant associations between allele frequencies and glucose intolerance in any of the populations. Log-linear analysis of the results from all three populations suggested a moderately significant interaction of glucose tolerance status (normal versus diabetic) and the FABP2 allele (partial chi 2 = 24, df 6, P = 0.027). The parameter describing the interaction of allele A3 and glucose tolerance status was the only such parameter differing significantly from zero (z-score +2.003, P = 0.046). In both the Finnish and U.K. population, the A3 allele was found approximately twice as frequently in NIDDM than in control subjects (Finnish control subjects, impaired glucose tolerance, and NIDDM: 12.2, 22.4, and 26.6%, respectively; U.K. control subjects and NIDDM: 7.8 and 14.6%, respectively). In the Finnish populations, no associations were found between FABP2 alleles and plasma insulin levels or with homeostatic model assessment (HOMA) estimates of beta-cell function and insulin sensitivity.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1994

Distribution of agrin mRNAs in the chick embryo nervous system.

Agrin is a synapse-organizing protein likely to mediate nerve-induced aggregation of acetylcholine receptors and other postsynaptic components at the neuromuscular junction. We used in situ hybridization and polymerase chain reaction (PCR) to define the localization of agrin mRNA and its alternatively spliced forms in the chick embryo nervous system. Agrin cRNA probes intensely labeled motor neurons, dorsal root ganglia, cerebellar Purkinje neurons, and retinal ganglion cells. Neuronal layers in optic tectum and ventricular regions were also labeled. Analysis by PCR showed that all parts of the nervous system at embryonic day 10 contained three major forms of agrin mRNA. Our results raise the possibility that agrin isoforms play a role in synapse formation or other aspects of neuronal development in the central nervous system.

Agrin↗
PubMed1993

Identification of masked and variant Ph (complex type) translocations in CML and classic Ph in AML and ALL by fluorescence in situ hybridization with the use of bcr/abl cosmid probes.

In the present study, three chronic myelogenous leukemia (CML) patients with variant Philadelphia (Ph) chromosomes (complex types), two CML patients with a masked Ph, one case with Ph positive acute lymphocytic leukemia (ALL), and one with Ph positive acute myelocytic leukemia (AML) were analyzed by standard cytogenetic techniques (G-banding), Southern blot studies, and fluorescence in situ hybridization (FISH) procedures using probes from portions of the bcr and abl genes. It has been previously shown that this FISH approach could detect the bcr/abl fusion event in CML patients with classic or variant (simple type) Ph. Our results demonstrate that this FISH assay can also detect the bcr/abl fusion status in CML patients with masked or variant (complex type) Ph chromosomes and in some patients with Ph positive ALL or AML.

Adult↗
PubMed1993

Presence of telomeric sequences on deleted chromosomes and their absence on double minutes in cell line HL-60.

The issue of telomeric sequences on deleted chromosomes and double minutes (dmin) was investigated by examining the cell line HL-60 with fluorescence in situ hybridization using a human plasmid DNA sequence with 800 bp TTAGGG repeats. This cell line showed telomeric sequences on the deleted short arms of chromosomes 9 and 10, with the results suggesting that so-called terminal deletion may be, in fact, an interstitial deletion, or that telomeric sequences may be synthesized by telomerase after deletion. On the other hand, numerous dmin showed no evidence of hybridization with the telomeric probe. This suggests that the characteristics unequal distribution of dmin during mitosis may result from the lack of not only centromeres but also telomeres.

Chromosome Deletion↗
PubMed1993

A more efficient and specific strategy in the ablation of mRNA in Xenopus laevis using mixtures of antisense oligos.

Previously, antisense oligodeoxyribonucleotides (oligos) have been used to ablate specific mRNAs from the maternal RNA pool of Xenopus laevis oocytes. However, this strategy is limited by the dose of oligo which can be used and the fact that 100% cleavage of the target RNA is rare. Further, non-specific cleavage of other RNAs can also occur. We demonstrate that the use of several oligos against the histone H4 RNA results in a marked improvement in the efficiency of target degradation, due to synergistic action between oligos and the existence of RNA in at least two different secondary structures. We show, by using a set of overlapping oligos complementary to the entire H4 RNA, that the amount of oligo required for efficient target ablation is greatly lowered and non-specific effects are reduced.

Animals↗
PubMed1993

Rearrangement of the MLL gene in acute lymphoblastic and acute myeloid leukemias with 11q23 chromosomal translocations.

BACKGROUND: Translocations involving chromosome band 11q23 are very frequent in both acute lymphoblastic and acute myeloid leukemias and are the most common genetic alteration in infants with leukemia. In all age groups and all phenotypes of leukemia, an 11q23 translocation carries a poor prognosis. A major question has been whether one or several genes on band 11q23 are implicated in these leukemias. Previously, we identified the chromosomal breakpoint region in leukemias with the common 11q23 translocations and subsequently cloned a gene named MLL that spans the 11q23 breakpoint. METHODS: We isolated a 0.74-kb BamHI fragment from a complementary DAN (cDNA) clone of the MLL gene. To determine the incidence of MLL rearrangements in patients with 11q23 abnormalities, we analyzed DNA from 61 patients with acute leukemia, 3 cell lines derived from such patients, and 20 patients with non-Hodgkin's lymphoma and 11q23 aberrations. RESULTS: The 0.74-kb cDNA probe detected DNA rearrangements in the MLL gene in 58 of the patients with leukemia, in the 3 cell lines, and in 3 of the patients with lymphoma. All the breaks occurred in an 8.3-kb breakpoint cluster region within the MLL gene. The probe identified DNA rearrangements in all 48 patients with the five common 11q23 translocations involving chromosomes 4, 6, 9, and 19, as well as in 16 patients with uncommon 11q23 aberrations. Twenty-one different chromosomal breakpoints involving the MLL gene were detected. CONCLUSIONS: MLL gene rearrangements were detected with a single probe and a single restriction-enzyme digest in all DNA samples from patients with the common 11q23 translocations as well as in 16 patients or cell lines with other 11q23 anomalies. The ability to detect an MLL gene rearrangement rapidly and reliably, especially in patients with limited material for cytogenetic analysis, should make it possible to identify patients who have a poor prognosis and therefore require aggressive chemotherapy or marrow transplantation.

Acute Disease↗
PubMed1993

Telomeric structure in cells with chromosome end associations.

End-to-end associations of metaphase chromosomes have been observed in a variety of human tumors, ageing cells, and several chromosome instability syndromes. Since telomeres of tumor cells and ageing tissues are often reduced in length, it has been suggested that chromosome end associations may be due to loss of telomeric repeats. We report the molecular structure of telomeres of two human tumor cell lines with frequent end-to-end associations of metaphase chromosomes. These telomeres were shown to be severely reduced compared with most other human cells with functional telomeres. However, we also describe two cell lines with severely shortened telomeres that are not detectably compromised in their function. We suggest that telomeric length is not the only determinant of the fusigenic behavior of human telomeres in tumor cells.

Base Sequence↗
PubMed1993

Two microsatellite repeat polymorphisms flanking opposite ends of the human glucokinase gene: use in haplotype analysis of Welsh Caucasians with type 2 (non-insulin-dependent) diabetes mellitus.

The purpose of this study was to evaluate the role of potential glucokinase defects contributing to susceptibility to Type 2 (non-insulin-dependent) diabetes mellitus in Welsh Caucasians. For this analysis, two microsatellite repeat polymorphisms flanking opposite ends of the gene were employed. For a recently described microsatellite (GCK2), located 6 kilobases upstream of islet exon 1, six different sized alleles were observed, with heterozygosity of 0.50 and polymorphism information content 0.44. Combined heterozygosity with another microsatellite repeat (GCK1) was 0.72. Significant linkage disequilibrium was noted between GCK2 and GCK1, suggesting that haplotypes may be a better predictor of Type 2 diabetes than analysis with either microsatellite alone. Using these two markers, the association with Type 2 diabetes was examined. The frequencies of alleles and genotypes at GCK1 did not differ between the patients with Type 2 diabetes (n = 157) and control subjects (n = 73). Similarly no differences were observed in GCK2 alleles or genotypes. The frequencies of haplotypes, derived from the two markers, also did not differ between the two groups. To investigate the possibility of minor metabolic effects of glucokinase defects, we also studied the association between the GCK alleles or haplotypes and the response profiles to meal tolerance tests. No association was observed between plasma glucose or insulin responses to meal tolerance tests with GCK haplotypes or alleles. These results suggest that glucokinase mutations in Welsh Caucasians are not major determinants of susceptibility to the common type of Type 2 diabetes.

Aged↗
PubMed1993

Multicenter phase II study of brequinar sodium in patients with advanced lung cancer.

A total of 53 patients with advanced lung cancer [non-small-cell (NSC), 21; small-cell (SC), 32] were treated with brequinar sodium. All of the NSC patients were chemotherapy-naive, but 31/32 (97%) SC patients had failed a multiagent chemotherapy program prior to study entry. Brequinar was given intravenously at a median weekly dose of 1200 mg/m2. The toxicity was moderate, with 19 patients (36%) experiencing grade 3 or 4 toxicity. Objective responses were observed in one NSC and two SC patients. We conclude that at this dose and on this schedule, brequinar does not have sufficient activity in patients with NSC or in patients with previously treated SC to warrant further evaluation. However, since responses were observed in previously treated SC lung-cancer patients, further evaluation in chemotherapy-naive patients may be warranted.

Aged↗
PubMed1993

FISH: a useful technique in the verification of clonality of random chromosome abnormalities.

Random chromosome abnormality is an important issue in clinical cytogenetics, especially in cancer cytogenetics. The significance of random abnormalities needs to be well defined. In the present study, ten patients with malignant hematologic disorders were analyzed by classical cytogenetic techniques and fluorescence in situ hybridization (FISH) procedures. Cytogenetic studies showed all ten patients to have a single cell with trisomy, i.e., +8, +8 (5 cases), +12, +15, +18, +20, and +21, respectively. FISH necessitated revision of the cytogenetic diagnosis and confirmed the clonality of these "random" abnormalities.

Adult↗
PubMed1993

Radiological aspects of solvent dissolution of gall-stones.

Twenty-five patients were referred for solvent dissolution of gall-stones using methyl tertiary butyl ether (MTBE). All patients were assessed beforehand by ultrasound and oral cholecystography. Computed tomography was performed in 23 patients to assess stone calcification and gall-bladder anatomy. Successful stone dissolution was achieved in 15 patients and partial dissolution in six patients. Failure to catheterize the gall-bladder occurred in four patients. There were four biliary leaks, two requiring cholecystectomy. The CT appearances of the gall-bladder may have predicted problems with catheterization in three of the four cases, and the results suggest that cover of the gall-bladder by the liver of greater than 50% is a favourable predictor of successful catheterization. A thick-walled gall-bladder and excess fat between the liver and the lateral abdominal wall are adverse predictors of successful gall-bladder catheterization. Both tubography and ultrasound should be used to assess progress of dissolution. Newer, more effective solvents together with increased expertise in interventional techniques may encourage the more widespread use of solvent dissolution of gall-stones as an alternative to surgery in a selected population.

Adult↗
PubMed1993

Overexpression of Her-2/neu may be an indicator of poor prognosis in prostate cancer.

Previous reports have shown that Her-2/neu oncogene expression in human breast cancer and ovarian cancer may be associated with poorer prognosis. We report the expression of Her-2/neu on fresh samples of known prostatic adenocarcinoma but not on those of benign prostatic hypertrophy. Using a monoclonal antibody (TA1) directed against human Her-2/neu oncogene product and an immunohistochemical staining method, no Her-2/neu expression was noted with benign prostatic hypertrophy (15 samples). With prostatic adenocarcinoma samples, a subset (9 of 25) showed overexpression of Her-2/neu. Such overexpression is correlated with higher histological grade, higher stage of disease, and high S phase and aneuploidy on flow cytometric analysis. These findings suggest that Her-2/neu may be a prognostic marker in prostate cancer as well.

Adenocarcinoma↗