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Biomedical subjects

L Neilson

Publications and source records attributed to L Neilson.

16 recordsLinked to original sources
PubMed2005

Cytokeratin 7 and 20 expression in intestinal metaplasia of the distal oesophagus: relationship to gastro-oesophageal reflux disease.

AIMS: Intestinal metaplasia and gastro-oesophageal reflux disease typify classical Barrett's oesophagus. Cytokeratin (CK) 7 and 20 phenotypes differentiate intestinal metaplasia in long segment Barrett's oesophagus from gastric intestinal metaplasia. This study examines the relationship between CK7/20 phenotypes and reflux disease in intestinal metaplasia of the distal oesophagus. METHODS AND RESULTS: Eighty patients with oesophageal pH studies included 30 with long segment Barrett's, 16 with short segment Barrett's and 34 with intestinal meatplasia of the gastro-oesophageal junction. Representative biopsy specimens were immunostained for CK7 and CK20. All 30 long segment patients demonstrated a Barrett's CK7/20 phenotype. All nine short segment patients with gastro-oesophageal reflux had a Barrett's CK7/20 phenotype, while four of seven short segment patients without reflux had a gastric CK7/20 phenotype (P = 0.019). Of 14 patients with intestinal metaplasia of the gastro-oesophageal junction and reflux, 10 (71%) had a Barrett's CK7/20 phenotype, compared with 11 (55%) of the 20 non-reflux patients. CONCLUSIONS: CK7/20 immunoreactivity for patients with intestinal metaplasia of the distal oesophagus without long segment Barrett's oesophagus suggests a heterogeneous group, with an association between Barrett's CK7/20 pattern and gastro-oesophageal reflux disease in both short segment Barrett's and intestinal metaplasia of the gastro-oesophageal junction.

Barrett Esophagus↗
PubMed2002

Aberrant expression of minichromosome maintenance proteins 2 and 5, and Ki-67 in dysplastic squamous oesophageal epithelium and Barrett's mucosa.

BACKGROUND: Minichromosome maintenance (Mcm) proteins are essential for eukaryotic DNA replication, and their expression implies potential for cell proliferation. Expression is dysregulated in dysplastic states but data for oesophageal squamous mucosa and Barrett's mucosa have not been published. AIM: To test the hypothesis that Mcm proteins are downregulated together with the proliferation marker Ki-67 in differentiating epithelial compartments of non-dysplastic squamous and Barrett's epithelium, and that this process does not occur in dysplastic mucosae. METHODS AND CASES: Forty five patients with Barrett's oesophagus included 20 with glandular dysplasia (10 low grade, eight high grade, two both, and four with invasive adenocarcinoma). Twenty five other patients included 12 with oesophageal squamous dysplasia (three low grade, six high grade, three both, and four with invasive squamous carcinoma). Formalin fixed paraffin embedded tissue sections from biopsy series and resections were immunostained using antibodies to Mcm2, Mcm5, and Ki-67. Percentage of nuclei positive for Mcm2, Mcm5, and Ki-67 was estimated and scored from 0 to 6 as: 0, none +; 1, <10%+; 2, 10-30%+; 3, 30-70%+; 4, 70-90%+; 5, >90%+; 6, all+. Four separate epithelial strata were scored: in squamous epithelium the basal layer and thirds to the surface, in Barrett's mucosa the luminal surface, upper and lower crypt, and deep glands. RESULTS: In non-dysplastic squamous epithelium and Barrett's mucosa, high level expression of Mcm2, Mcm5, and Ki-67 proteins was largely confined to the proliferative compartments and downregulated in differentiated compartments. Expression persisted up to the mucosal surface in dysplastic squamous epithelium and Barrett's mucosa. CONCLUSIONS: Persistent expression of Mcm2, Mcm5, and Ki-67 proteins in luminal compartments of dysplastic oesophageal squamous epithelium and dysplastic Barrett's mucosa may be diagnostic markers and imply disruption of cell cycle control and differentiation in these dysplastic epithelia.

Barrett Esophagus↗
PubMed2000

Molecular phenotype of the human oocyte by PCR-SAGE.

Consecutive application of PCR and serial analysis of gene expression (SAGE) was used to generate a catalog of approximately 50, 000 SAGEtags from nine human oocytes. Matches for known genes were identified using the National Institutes of Health SAGEtag database. This database links directly to the UniGene database, providing rapid discrimination between SAGEtags that match known genes and expressed sequence tags and those that currently have no match. Matches in the oocyte SAGE catalog were found for surface receptors, second-messenger systems, and cytoskeletal, apoptotic, and secreted proteins. Many of these proteins were not previously known to be expressed in mammalian oocytes. The relative abundances of transcripts for cytoskeletal proteins and proteins known to be in oocytes are consistent with their documented expression, suggesting an absence of representational distortion by the PCR step. The expression profile of the human oocyte may help identify factors that reprogram somatic cell nuclei to totipotency.

Databases, Factual↗
PubMed1999

Site-specific recombination at dif by Haemophilus influenzae XerC.

Xer site-specific recombination at the Escherichia coli chromosomal site dif converts chromosomal dimers to monomers, thereby allowing chromosome segregation during cell division. dif is located in the replication terminus region and binds the E. coli site-specific recombinases EcoXerC and EcoXerD. The Haemophilus influenzae Xer homologues, HinXerC and HinXerD, bind E. coli dif and exchange strands of dif Holliday junctions in vitro. Supercoiled dif sites are not recombined by EcoXerC and EcoXerD in vitro, possibly as a consequence of a regulatory process, which ensures that in vivo recombination at dif is confined to cells that can initiate cell division and contain dimeric chromosomes. In contrast, the combined action of HinXerC and EcoXerD supports in vitro recombination between supercoiled dif sites, thereby overcoming the barrier to dif recombination exhibited by EcoXerC and EcoXerD. The recombination products are catenated and knotted molecules, consistent with recombination occurring with synaptic complexes that have entrapped variable numbers of negative supercoils. Use of catalytically inactive recombinases provides support for a recombination pathway in which HinXerC-mediated strand exchange between directly repeated duplex dif sites generates a Holliday junction intermediate that is resolved by EcoXerD to catenated products. These can undergo a second recombination reaction to generate odd-noded knots.

Amino Acid Sequence↗
PubMed1996

Xer-mediated site-specific recombination in vitro.

The Xer site-specific recombination system acts at ColE1 cer and pSC101 psi sites to ensure that these plasmids are in a monomeric state prior to cell division. We show that four proteins, ArgR, PepA, XerC and XerD are necessary and sufficient for recombination between directly repeated cer sites on a supercoiled plasmid in vitro. Only PepA, XerC and XerD are required for recombination at psi in vitro. Recombination at cer and psi in vitro requires negative supercoiling and is exclusively intramolecular. Strand exchange at cer produces Holliday junction-containing products in which only the top strands have been exchanged. This reaction requires the catalytic tyrosine residue of Xer C but not that of XerD. Recombination at psi gives catenated circular resolution products. Strand exchange at psi is sequential. XerC catalyses the first (top) strand exchange to make a Holiday junction intermediate and XerD catalyses the second (bottom) strand exchange.

Base Sequence↗
PubMed1995

Kinetic characteristics of Escherichia coli RNase H1: cleavage of various antisense oligonucleotide-RNA duplexes.

1. The effects of variations in substrates on the kinetic properties of Escherichia coli RNase H were studied using antisense oligonucleotides of various types hybridized to complementary oligoribonucleotides. The enzyme displayed minimal sequence preference, initiated cleavage through an endonucleolytic mechanism near the 3' terminus of the RNA in a DNA-RNA chimera and then was processively exonucleolytic. Phosphorothioate oligodeoxynucleotides hybridized to RNA supported cleavage more effectively than phosphodiester oligodeoxynucleotides. Oligonucleotides comprised of 2'-methoxy-, 2'-fluoro- or 2'-propoxy-nucleosides did not support RNase H1 activity. 2. The Km and Vmax. of cleavage of RNA duplexes with full phosphorothioate oligodeoxynucleotides were compared with methoxy-deoxy 'gapmers', i.e.; oligonucleotides with 2'-methoxy wings surrounding a deoxynucleotide centre. Such structural modifications resulted in substantial increases in affinity, but significant reductions in cleavage efficiency. The initial rates of cleavage increased as the deoxynucleotide gap size was increased. Multiple deoxynucleotide gaps increased the Vmax. but had little effect on Km. 3. The effects of several base modifications on the site of initial cleavage, processivity and initial rate of cleavage were also studied.

Base Sequence↗
PubMed1995

Skin irritation testing in man for hazard assessment--evaluation of four patch systems.

1. The limitations of the Draize rabbit skin irritation test for hazard evaluation for man are widely documented. Nevertheless it remains the prescribed method for determining acute skin irritations hazard. 2. While the use of human testing for risk assessment of irritants is well established, the use of predictive testing in man for hazard identification has not been explored widely, and this is the object of the research programme. 3. The experiment described in this report evaluates the sensitivity of four patch testing systems (Finn chamber, Hill Top patch, Van der Bend chamber, and Webril patch) using a total of six irritant substances. 4. Following preliminary range-finding experiments, test materials were applied to the upper outer arm for up to 4 h. Assessments were performed immediately after patch removal and at 1, 24, 48, and 72 h. 5. Webril and Hill Top patches generated the greatest levels of response, although responses with Finn and Van der Bend were observed. Hill Top patches are recommended for future development work. 6. The use of very small preliminary panels to predict the effects in larger panels using different volunteers was only of limited value as each volunteer was found to have different irritant thresholds.

Acetates↗
PubMed1994

Denial: coping or cop-out?

Health caregivers working with palliative patients in the home are able to establish closer relationships with these patients than in the palliative hospital setting. Since a familiar and comfortable setting helps set the stage for effective communication, it is not surprising that home care patients and their families often share intimate thoughts and feelings with visiting caregivers. Yet that same closeness can make it more difficult for a home caregiver to accept a patient's denial of impending death. While agreeing that, in theory, denial is a normal defence mechanism, the home caregiver may have become too emotionally involved to appreciate denial as a particular patient's choice.

Adaptation, Psychological↗
PubMed1993

Oestrogen receptor message in premalignant and normal cervical cells: a methodological study.

Normal and abnormal biopsies of the uterine cervix, to a total of 124 samples, have been analysed for the detection of oestrogen receptor (ER) mRNA. The tough fibrous nature of the cervix proved very resistant to disaggregation in the first instance and subsequently, it was difficult to extract good high molecular weight message. This necessitated a systematic study of methodological technique, including two methods of tissue disaggregation and five techniques of extraction of ER mRNA, which in total involved the use of 124 cervical biopsies. The most successful method involved chopping the tissue, then digesting the cells with proteinase K and extracting the nucleic acids in salt and sodium dodecyl sulphate. Using the perfected technique, 16 cervical biopsies obtained at serial intervals from four women did not show any differences in ER mRNA in cervical biopsies either in the presence of oral contraception or histological abnormality. The successful method described will prove valuable for the detection of ER message in human tumours and other tissues of similar nature.

Cervix Uteri↗
PubMed1991

Prospective serial study of viral change in the cervix and correlation with human papillomavirus genome status.

OBJECTIVE: To observe in serial fashion the histological changes of human papilloma virus (HPV) infection of the cervix and to correlate these with the detection of HPV genomes. DESIGN: A prospective longitudinal study to perform colposcopy and at 0, 9 and 18 months to obtain a smear, a biopsy for histology and HPV-16 genome detection by DNA/DNA hybridization. SETTING: Glasgow Family Planning Centre. SUBJECTS: Eighty-two women recruited on the basis of a routine smear showing viral change without dyskaryosis. INTERVENTIONS: Women found to have CIN 3 were treated with laser. MAIN OUTCOME MEASURES: Cytology and cervical biopsy results and HPV-16 DNA detection by Southern blotting obtained serially from individual subjects. RESULTS: Of 82 women recruited, 10% were positive for HPV-16 detection by Southern blotting. Detection of HPV-16 genomes did not correlate with either CIN or viral infection assessed histologically and serial hybridizations in a given individual showed fluctuation in HPV-16 detection. Polymerase chain reaction in a subset of samples revealed 46% positive for HPV DNA. CONCLUSION: No clear correlation exists between HPV genome detection and the histological appearance. HPV-16 genome detection alone may not be a useful predictor of precancerous progression.

Adolescent↗
PubMed1988

Effect of heat shock on ribosome synthesis in Drosophila melanogaster.

In Drosophila tissue culture cells, the synthesis of ribosomal proteins was inhibited by a 1-h 37 degrees C heat shock. Ribosomal protein synthesis was repressed to a greater extent than that of most other proteins synthesized by these cells at 25 degrees C. After a 1-h heat shock, when the cells were returned to 25 degrees C, the ribosomal proteins were much slower than most other 25 degrees C proteins to return to pre-heat shock levels of synthesis. Relative to one another, all the ribosomal proteins were inhibited and later recovered to normal levels of synthesis at the same rate and to the same extent. Unlike the ribosomal proteins, the precursor to the large rRNAs was continually synthesized during heat shock, although at a slightly reduced level, but was not processed. It was rapidly degraded, with a half-life of approximately 16 min. Pre-heat shock levels of synthesis, stability, and correct processing were restored only when ribosomal protein synthesis returned to at least 50% of that seen in non-heat-shocked cells.

Animals↗
PubMed1988

Analysis of the spectrotypes of autoantibodies against thyroglobulin in two rat models of autoimmune thyroiditis.

We have studied the isoelectric focusing (IEF) spectrotypes of autoantibodies against thyroglobulin in two rat models of Hashimoto's thyroiditis: (1) AUG strain rats immunized with autologous thyroglobulin in Freund's complete adjuvant; (2) PVG/c strain rats which have been thymectomized and sublethally irradiated. The IEF spectrotypes revealed differences between the two models. The anti-thyroglobulin response in immunized AUG rats is mainly oligoclonal or polyclonal, often with dominant clones in the spectrotype, similar to about 90% of Hashimoto's patients, whereas the response in the PVG/c rat is highly restricted. There were pronounced changes in spectrotype with time in the PVG/c, but not AUG, rats with considerable variation in the lifespan of individual clones. The maximum lifespan of an anti-self secreting B-cell clone in the PVG/c rat, determined by persistence of its clonotype, was at least 16 weeks.

Animals↗
PubMed1986

Analysis of the clonal origins of autoantibodies against thyroglobulin and DNA in autoimmune thyroiditis and systemic lupus erythematosus.

We have analysed the isoelectric focusing (IEF) spectra of antithyroglobulin autoantibodies in the sera of patients with autoimmune thyroiditis, and of anti-dsDNA autoantibodies in the sera of patients with systemic lupus erythematosus (SLE), NZB/NZW F1 hybrid, MRL-lpr/lpr and MRL/++ male and female mice. Ninety-two per cent of patients with anti-thyroglobulin autoantibodies had a polyclonal spectrotype compared with only 25% of SLE patients analysed for anti-dsDNA. Fifty-five per cent of the latter had monoclonal spectrotypes, the remainder being either biclonal or having a dominant clone on a polyclonal background. By contrast, only two out of 61 autoimmune thyroiditis patients expressed monoclonal anti-thyroglobulin autoantibodies. All of the lupus mice had highly restricted spectrotypes (monoclonal or biclonal) of anti-dsDNA autoantibodies. The implications of these results for the aetiology of autoimmunity are discussed.

Animals↗
PubMed1985

Insulin suppresses rat growth hormone messenger ribonucleic acid levels in rat pituitary tumor cells.

Insulin has been shown to suppress growth hormone (GH) secretion by rat pituitary tumor cells (GH3) independently of glucose utilization. The effects of physiologic doses of insulin were therefore tested on cytoplasmic levels of GH messenger ribonucleic acid (mRNA) sequences. Insulin (3.5 nM) treatment of cells for 5 days suppressed the hybridization of cytoplasmic GH mRNA with 32P-cDNA for rGH by 50%. The three- to fourfold induction of cytoplasmic GH mRNA by hydrocortisone (1 microM) was also suppressed by insulin (3.5 nM) by 40%. The results show a direct suppression of cytoplasmic rGH mRNA concentration by physiologic doses of insulin. These findings may be due to either decreased rate of GH gene transcription, increased intracellular breakdown, or decreased nuclear-cytoplasmic transport of GH mRNA caused by insulin.

Animals↗
PubMedDate not supplied

Serum, insulin and phorbol esters stimulate rRNA and tRNA gene expression in both dividing and nondividing Drosophila cells.

The expression of genes that code for the large ribosomal RNAs (rRNAs) and tRNAs can be regulated by calcium, serum, insulin and a tumor-promoting phorbol ester, TPA. These effectors can rapidly alter rRNA and tRNA synthesis in dividing and nondividing Drosophila cells. In an in vitro assay system of the nondividing cells of the male accessory glands, calcium, insulin and TPA were shown to increase both rRNA and tRNA synthesis. Exposure of actively dividing Drosophila culture cells to differing serum concentrations or TPA also altered rRNA and tRNA synthesis. Nuclear run-on assays demonstrate that the exposure of these cells to increased serum concentrations coordinately alters RNA polymerase I loading on both 18S and 28S rDNA. These data indicate that calcium, growth factors and a tumor-promoter each can signal changes in ribosomal and tRNA gene expression.

Animals↗