PubMed Health⌕ Search

Biomedical subjects

C Summers

Publications and source records attributed to C Summers.

At least 19 recordsLinked to original sources
PubMed2006

In-situ demonstration of mitogen-activated protein kinase Erk 1/2 signalling pathway in contagious respiratory tumours of sheep and goats.

Ovine pulmonary adenocarcinoma (OPA) and enzootic nasal adenocarcinoma (ENA) are two contagious neoplastic diseases of secretory epithelial cells in the respiratory system of sheep and goats. Jaagsiekte sheep retrovirus (JSRV) is the aetiological agent of OPA, and enzootic nasal tumour virus (ENTV) is associated with ENA. The genomes of these retroviruses do not contain known oncogenes but products of the env gene are important in the generation of transforming stimuli. However, the cell signalling pathways activated in vivo are not completely understood. This study was based on the use of activation stage antibodies specifically detecting proteins of the extracellular signal regulated kinase Erk 1/2 cell signalling pathway and transcription factors. Tissue sections were collected from four natural cases of OPA, four experimentally induced OPA tumours, four ENA tumours in sheep, four ENA tumours in goats, two normal sheep lungs and two lungs with chronic inflammation. Routine immunohistochemical procedures with phosphorylation stage-specific antibodies were carried out. Representative proteins of the Erk1/2 pathway (Raf-1, Mek1/2 and p44/42MAPK) were activated in natural cases of OPA and ENA in sheep and goats and also in experimentally induced OPA. Transcription factors 90Rsk and Elk-1 were activated in OPA and ENA tumours. However, c-Myc was activated only in OPA tumours. In contagious respiratory neoplasms of sheep and goats the Erk1/2 pathway appears to be important for the in-vivo generation of the transforming stimuli.

Adenocarcinoma↗
PubMed2005

An influx of macrophages is the predominant local immune response in ovine pulmonary adenocarcinoma.

Infection with a retrovirus, Jaagsiekte sheep retrovirus (JSRV), causes ovine pulmonary adenocarcinoma (OPA). The excess production of surfactant proteins by alveolar tumour cells results in increased production of pulmonary fluid, which is characteristically expelled through the nostrils of affected sheep. The immune response to JSRV and the tumour is poorly understood: no JSRV-specific circulating antibodies or T cells have been detected to date. The aim of the present study was to obtain phenotypic evidence for a local immune response in OPA lungs. Specific-pathogen free lambs were infected intratracheally with JSRV. When clinical signs of OPA were apparent, the lungs were removed at necropsy and immunohistochemistry (IHC) was performed on lung sections using a panel of mouse anti-sheep mAbs. No influx of dendritic cells, B cells, CD4, CD8 or gammadelta T cells was seen in the neoplastic nodules or in their periphery. MHC Class II-positive cells were found intratumourally, peritumourally and in the surrounding alveolar lumina. In the tumours, many of these cells were shown to be fibroblasts and the remainder were likely to be mature macrophages. In the alveolar lumen, the MHC Class II-positive cells were CD14-positive and expressed high levels of IFN-gamma. They appeared to be immature monocytes or macrophages which then differentiated to become CD14-negative as they reached the periphery of the tumours. A high level of MHC Class I expression was detected on a range of cells in the OPA lungs but the tumour nodules themselves contained no MHC Class I-positive cells. On the basis of these findings, it is proposed that the lack of an effective immune response in OPA could result from a mechanism of peripheral tolerance in which the activity of the invading macrophages is suppressed by the local environment, possibly as a consequence of the inhibitory properties of the surfactant proteins.

Animals↗
PubMed2001

Detection of immune system cells in paraffin wax-embedded ovine tissues.

This report describes a method (fixation, paraffin wax-embedding and immunolabelling) for the demonstration of several immune system cell epitopes (CD1, CD2, CD4, CD8, CD14, CD21, CD45R, WC-1, 28 kDa surface antigen, immunoglobulins and MHC II antigens) in ovine lymph nodes collected at necropsy. Cell surface epitopes considered to be sensitive to processing methods were successfully demonstrated by a procedure that included the use of a non-aldehyde-containing, zinc salts-based fixative, coupled with a sensitive system of immunolabelling. This novel method had the advantage of avoiding antigen-retrieval steps and of providing consistently good morphological definition.

Animals↗
PubMed1998

Expression and distribution of transforming growth factor-beta isoforms and their signaling receptors in growing human bone.

Transforming growth factors type beta (TGF-beta1, -beta2, and -beta3) are potent stimulators of bone formation and have been shown to regulate chondrocyte, osteoblast, and osteoclast formation and function. However, the distribution of the different isoforms and their signaling receptors in human bone in vivo has not previously been reported. Using samples of normal (neonatal rib) and pathological (osteophytic) developing human bone, we have investigated the expression of the different TGF-beta isoforms and their signaling receptors (TGF-betaRI and RII) at the messenger ribonucleic acid (mRNA) and protein levels by in situ hybridization and immunolocalization to establish the sites of TGF-beta production and their possible sites of action during human bone development in vivo. All three TGF-beta isoforms and the receptors were detected at sites of endochondral and intramembranous ossification. At sites of endochondral ossification, TGF-beta2 was detected in all zones of the cartilage, with the highest expression seen in the hypertrophic and mineralizing zones. TGF-beta3 was detected in proliferative and hypertrophic zone chondrocytes, while TGF-beta1 expression was restricted to the proliferative and upper hypertrophic zones. TGF-betaRI and RII exhibited similar distributions with maximum expression in the hypertrophic and mineralizing zones in the neonatal rib but in the resting/proliferative zone in the developing osteophyte. At sites of intramembranous ossification TGF-beta3 was the most widely distributed isoform and showed both matrix- and cell-associated staining. TGF-beta2 and -beta1 were expressed almost exclusively at sites of mineralization. These observations demonstrate that the different TGF-beta isoforms and their receptors exhibit distinct but overlapping patterns of expression, and support the hypothesis that they are involved in the regulation of endochondral and intramembranous ossification during human bone development in vivo.

Activin Receptors, Type I↗
PubMed1996

Cognitive salience of haptic object properties: role of modality-encoding bias.

The influence of modality-encoding bias on the relative importance ('cognitive salience') of object shape, size, and material, with the last determined by weight and thermal variations, was examined. Experiment 1 confirmed that for these stimulus objects all five properties were very accessible haptically, as measured by the time to identify the property level of each designated property; however, observers were still generally faster for geometric than material properties. In experiment 2, the influence of modality-encoding bias on cognitive salience was assessed by using a task involving free sorting by similarity. As predicted, modality-encoding bias strongly influenced cognitive salience. Observers favoured sorting by material under haptic- bias instructions, and three-dimensional geometric properties (especially shape) under visual-bias instructions. Videotaped hand movements indicated that modality-encoding biases reflect long-term knowledge of the relative speed and precision of manual exploration patterns, rather than exploration of the current set of objects.

Analysis of Variance↗
PubMed1993

Cloning, expression and characterisation of the cDNA encoding human hepatic squalene synthase, and its relationship to phytoene synthase.

The reaction catalysed by squalene synthase (SQS) shows many similarities to that performed by another polyisoprene synthase, phytoene synthase (PhS). By identifying sequences conserved between yeast SQS (ySQS) and PhS, we have cloned a 2-kb cDNA (hSQS) encoding human SQS, a protein of 417 amino acids with a predicted M(r) of 48,041, which has only limited homology to ySQS. When expressed in E. coli, the hSQS cDNA directed the production of active enzyme. Two hSQS mRNA species of 2.0 and 1.55 kb have been identified which differ in their 3' untranslated sequences. The two mRNAs are present in roughly equal amounts in heart, placenta, lung, liver, kidney and pancreas, but the 2-kb mRNA predominates in brain and skeletal muscle. In HepG2 cells, both mRNAs are induced 2-4-fold by the 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitor, lovastatin. In contrast, Northern blot analysis of rat tissues reveals only a 2.0-kb mRNA, which is considerably up-regulated in vivo by lovastatin.

Alkyl and Aryl Transferases↗
PubMed1991

A deletion mutation of the cystic fibrosis transmembrane conductance regulator (CFTR) locus: Delta I507.

During the development of an amplification refractory mutation system (ARMS) assay for the detection of the Delta F508 mutation and corresponding normal locus in cystic fibrosis we discovered a family in which a further variant of the sequence exists. PCR amplification and direct sequencing of a region of exon 10 of the CFTR locus indicated the deletion of the three base pairs encoding isoleucine or isoleucine, or possibly the presence of a single base substitution in conjunction with the Delta F508 mutation. The resulting protein has a deletion of an isoleucine residue at position 507 as opposed to the previously described deletion of phenylalanine at position 508. We conclude that the loss of an isoleucine residue at position 507 (Delta I507) is another defective variant of the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) gene product.

Amino Acid Sequence↗
PubMed1991

Genetic analysis in cystic fibrosis using the amplification refractory mutation system (ARMS): the J3.11 MspI polymorphism.

A new method of genetic analysis has been devised. The method, amplification refractory mutation system (ARMS), has been used to genotype the J3.11 MspI restriction fragment length polymorphism (RFLP) closely linked to cystic fibrosis (CF). The DNA sequence for both alleles of this dimorphism has been used to design ARMS primers. These allow genotyping of DNA isolated from blood, Guthrie cards, and buccal cells.

Alleles↗
PubMed1991

A plasmid cassette system that allows optimization of primers for use in the amplification refractory mutation system.

A plasmid "cassette" system is presented that allows the development of amplification refractory mutation system (ARMS) primers. Primer development may be accomplished even in the absence of appropriate clinical material from patients demonstrating mutated alleles. The use of such cassettes is demonstrated here in the assessment of primers prepared for ARMS analysis of the gene coding for the normal and Z variant alleles of the human serine protease inhibitor alpha-1-antitrypsin.

Adult↗
PubMed1990

Delta F508 testing of the DNA bank of the Royal Manchester Children's Hospital.

Details of haplotype and delta F508 status from various populations represented in the cystic fibrosis (CF) DNA bank of the Royal Manchester Children's Hospital are provided, together with information on the association of genotype and clinical status. Clinical details and DNA analyses from native English in the North-West and South-West of England (Bath), from Lancashire Pakistani families and from Afrikaans Namibian families are compared. A 78.5% incidence of delta F508 has been found in English families. Compound heterozygotes with CF and only one delta F508 gene have an increased likelihood of having milder disease, with less Pseudomonas isolated from sputum and relatively more showing either no regular respiratory pathogens or colonisation with Staphylococcus. There is also a relative increase in meconium ileus in these compound heterozygotes. The diagnosis of CF may be in doubt in some subjects negative for delta F508. Some of the Bath families have unusual haplotypes for an English population and a compound heterozygote delta F508/delta I507 has been found. There is evidence from metD analysis of the founder effect in the Afrikaans Namibian families, who have a high delta F508 incidence.

Cystic Fibrosis↗
PubMed1989

Analysis of any point mutation in DNA. The amplification refractory mutation system (ARMS).

We have improved the "polymerase chain reaction" (PCR) to permit rapid analysis of any known mutation in genomic DNA. We demonstrate a system, ARMS (Amplification Refractory Mutation System), that allows genotyping solely by inspection of reaction mixtures after agarose gel electrophoresis. The system is simple, reliable and non-isotopic. It will clearly distinguish heterozygotes at a locus from homozygotes for either allele. The system requires neither restriction enzyme digestion, allele-specific oligonucleotides as conventionally applied, nor the sequence analysis of PCR products. The basis of the invention is that unexpectedly, oligonucleotides with a mismatched 3'-residue will not function as primers in the PCR under appropriate conditions. We have analysed DNA from patients with alpha 1-antitrypsin (AAT) deficiency, from carriers of the disease and from normal individuals. Our findings are in complete agreement with allele assignments derived by direct sequencing of PCR products.

Base Sequence↗
PubMed1988

Absence of immunoglobulin and T-cell receptor gene rearrangements in myelodysplastic syndromes and acute nonlymphocytic leukemias.

The arrangement of the immunoglobulin and T-cell receptor genes has been analysed in 72 cases of primary myelodysplastic syndrome and 17 cases of acute nonlymphocytic leukemia. DNA was extracted from bone marrow aspirates, digested with at least two restriction enzymes, and hybridised with probes for the joining region of the immunoglobulin heavy chain gene, the constant region of the T-cell receptor beta chain gene, and the joining region of the T-cell receptor gamma chain gene. All cases showed germline arrangements of the immunoglobulin and the T cell receptor genes. Thus, true interlineage infidelity, myeloid to lymphoid, is a rare occurrence in myelodysplasia and in myeloid leukemias.

Acute Disease↗
PubMed1988

Detection of chromosomal 7 loss in myelodysplasia using an extremely polymorphic DNA probe.

Chromosomal loss is a characteristic feature of the myelodysplastic syndromes (MDS). A method is described which detects chromosomal 7 loss in MDS by DNA analysis using a specific hypervariable region gene probe which has been cloned from a human DNA fingerprint. Loss of one of the chromosomal 7 homologues was demonstrated in 10/118 MDS patients; the ten patients include all the five patients which had previously been shown to have monosomy 7 by cytogenetic analysis. This technique makes it feasible to study serial samples from large numbers of patients for loss of chromosomal material and could be readily applied to the study of other human malignancies.

Alleles↗