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Biomedical subjects

R J Thompson

Publications and source records attributed to R J Thompson.

At least 145 records · Page 8Linked to original sources
PubMed1984

Endogenous cyclic AMP-stimulated phosphorylation of a Wolfgram protein component in rabbit central-nervous-system myelin.

Cyclic AMP-stimulated phosphorylation of membrane proteins in central-nervous-system myelin was investigated, with rabbit brain myelin. Subfractionation of a myelin membrane preparation by sucrose-density-gradient centrifugation produced a rapidly sedimenting population of membrane vesicles containing 5'-nucleotidase and acetylcholinesterase, a light membrane fraction containing myelin basic protein and 2',3'-cyclic nucleotide 3'-phosphodiesterase, and an intermediate membrane fraction containing the highest specific activity of 2',3'-cyclic nucleotide 3'-phosphodiesterase and a small proportion of myelin basic protein. Cyclic AMP stimulation of protein phosphorylation was confined to a protein of Mr 49 700, which co-electrophoresed with the upper component of the Wolfgram protein doublet. Cyclic AMP did not affect the phosphorylation of myelin basic protein. Cyclic AMP-stimulated phosphorylation of this protein followed 2',3'-cyclic nucleotide 3'-phosphodiesterase activity on subcellular fractionation and was correspondingly high in the intermediate or 'myelin-like' fraction on sucrose-density-gradient centrifugation.

Animals↗
PubMed1984

Photoaffinity labelling of central-nervous-system myelin. Evidence for an endogenous type I cyclic AMP-dependent kinase phosphorylating the larger subunit of 2',3'-cyclic nucleotide 3'-phosphodiesterase.

Endogenous cyclic AMP-stimulated phosphorylation of a 49700-Mr Wolfgram protein component in rabbit central nervous system was investigated by using photoaffinity labelling and 2',3'-cyclic nucleotide 3'-phosphodiesterase activity staining after electroblotting on to nitrocellulose paper. Photoaffinity labelling with 8'-azidoadenosine 3',5'-cyclic monophosphate showed a cyclic AMP-binding protein that appeared to be intrinsic to the myelin membrane and appeared to represent the R-subunit of a type I cyclic AMP-dependent protein kinase. This photoaffinity-labelled protein was of larger apparent Mr than the protein showing cyclic AMP-stimulated phosphorylation. Blotting of one-dimensional sodium dodecyl sulphate/polyacrylamide-gel electrophoretograms followed by staining for 2',3'-cyclic nucleotide 3'-phosphodiesterase activity showed two activity bands corresponding to the two components of the Wolfgram protein doublet. Cyclic AMP-stimulated protein phosphorylation corresponded to the upper component of this doublet. Electroblotting of two-dimensional non-equilibrium pH-gradient electrophoretograms also showed co-migration of cyclic AMP-stimulated protein phosphorylation with enzyme activity. It is proposed that central-nervous-system myelin contains an endogenous type I cyclic-AMP dependent protein kinase that phosphorylates the larger subunit of 2',3'-cyclic nucleotide 3'-phosphodiesterase.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗
PubMed1984

Levels of immunoreactive aldolase C, creatine kinase-BB, neuronal and non-neuronal enolase, and 14-3-3 protein in circulating human blood cells.

Five proteins found in the human nervous system have been measured by radioimmunoassay in human red cells, platelets, and lymphocytes. Two neuronal proteins (neurone-specific enolase and 14-3-3 protein) occur in platelets at levels equivalent to their concentration in brain, and in erythrocytes at levels approximately 10% of the level in brain. Two proteins characteristic of astrocytes in the cerebral cortex (creatine kinase BB and aldolase C) occur at low levels in platelets and are virtually undetectable in erythrocytes and lymphocytes. The more widely distributed non-neuronal enolase is present in erythrocytes, platelets and lymphocytes. The neurone-specific enolase and 14-3-3 protein immunoreactivities found in circulating blood cells have been characterised in terms of molecular mass, charge, and dilution characteristics in the respective radioimmunoassay and in each case appears to represent the intact protein. Controlled lysis of erythrocytes releases neurone-specific enolase and 14-3-3 protein in parallel with haemoglobin. The occurrence of brain proteins in circulating blood cells (which appears to be a species-dependent phenomenon) has the practical clinical consequence that minor degrees of especially red cell lysis can produce high serum levels of immunoreactivity. This represents a pitfall in the measurement of these proteins in serum as tumour markers or as indices of damage to the central nervous system.

14-3-3 Proteins↗
PubMed1984

Fragments of myelin basic protein derived from human brain are not mitogenic in cultures of human amniotic fluid cells and other cells.

The possible mitogenic effects of a number of preparations of the myelin basic protein (MBP) of human brain have been investigated in various cell types in culture, including human amniotic fluid cells. Intact human MBP, as well as fragments derived by BNPS-skatole and cathepsin D treatment, and isoelectric focusing fractions of human MBP, showed no mitogenic activity. These results are consistent with recent findings that the fibroblast growth factor (FGF) activity of bovine brain does not originate from MBP.

Amniotic Fluid↗
PubMed1984

A study by high-resolution two-dimensional polyacrylamide gel electrophoresis of relationships between Neisseria gonorrhoeae and other bacteria.

High-resolution two-dimensional polyacrylamide gel electrophoresis was used to analyse the soluble proteins from seven strains of Neisseria gonorrhoeae, six strains of Neisseria meningitidis and one or two strains of twelve other species. Approximately 200 individual polypeptides could be visualized as Coomassie Blue stained spots on an electrophoretogram of N. gonorrhoeae and similar numbers were found for the other bacteria. Each species of bacterium had a distinctly different pattern of spots which could be recognized. Quantitative comparisons of 48 selected spots derived from one strain of N. gonorrhoeae with those of five other strains of gonococcus, three strains of N. meningitidis and one of Branhamella catarrhalis, showed relationships in agreement with their current taxonomic classification but with a higher level of discrimination than that of previously used methods. It was also possible to distinguish the individual gonococcal strains. It is suggested that the method could be useful for bacterial classification and identification.

Electrophoresis, Polyacrylamide Gel↗
PubMed1984

Light and Genetic Determinants in the Control of Specific Chloroplast Transcripts in Chlamydomonas reinhardtii.

We have looked for chloroplast genes whose expression is controlled by light by comparing the abundance of specific chloroplast transcripts in light-grown and dark-grown cells of Chlamydomonas reinhardtii. In addition, we have investigated whether genetic components influence expression of such genes.Northern blot analyses of specific separated transcripts showed that in certain strains (e.g. CC-278), several chloroplast transcripts from the Hpa II 5 region of the chloroplast chromosome were more abundant in dark-grown cells than in light-grown cells. The increased abundance of these Hpa II 5-specific transcripts was dependent on the genetic background: we have isolated mutants and we have found distantly related wild type strains which do not overaccumulate these transcripts in the dark.The strains which overaccumulated the Hpa II 5-specific transcripts, and only these strains, died after several cell divisions following transfer to the dark. Overaccumulation appears to be a necessary but not sufficient prerequisite for commitment to cell death in the dark.By analogy to bacterial systems, we speculate that a critical event associated with accumulation of one of these specific transcripts involves control at the level of transcription initiation or termination-antitermination.

Journal Article↗
PubMed1984

Investigation of microtrauma after sexual intercourse.

An investigation was carried out to determine whether colposcopic examination would be valuable in documenting vaginal intercourse. A prospective study was conducted on 18 volunteers, each of whom was examined after 72 hours of sexual abstinence and again within 6 hours after vaginal intercourse. Each of two examinations consisted of a colposcopic examination of the vaginal mucosa before and after staining with Lugol's solution to maximize the possibility of finding trauma. Positive colposcopic findings were found in 61.1% of patients after consensual vaginal intercourse as compared with 11.1% of patients after abstinence (p less than 0.01).

Adolescent↗
PubMed1984

Two-site monoclonal antibody assays for human heart- and brain-type creatine kinase.

Monoclonal antibodies have been raised against human heart- and brain-type creatine kinase (CK-MB and CK-BB). We used a low-affinity monoclonal antibody to develop a simple two-step immunoaffinity purification procedure for native CK-MB. Antibodies of higher affinity were used to construct specific two-site immunoradiometric assays for CK-MB and CK-BB. In the assay for CK-MB we used an 125I-labeled B subunit-specific antibody with an immobilized anti-M subunit antibody--adding either simultaneously, for a 1-h assay in which between 5 and 1000 ng of CK-MB per milliliter could be measured with an intra-assay CV of 4% to 20%, or sequentially, for a 2-h magnetic separation assay in which between 0.5 and 1000 ng/mL could be measured with an intra-assay CV of 14 to 19%. In both versions CK-BB up to 100 ng/mL and CK-MM up to 5000 ng/mL did not interfere. In the assay for CK-BB we used an 125I-labeled, reduced, and alkylated monoclonal antibody specific for the B subunit of CK-BB, and removed bound isoenzyme with a second immobilized monoclonal antibody specific for a different epitope on the B subunit. Total incubation time for this assay was 5 h. Intra-assay CV was 7.5 to 20% between 0.1 and 1000 ng/mL. CK-MB up to 1000 ng/mL and CK-MM up to 100 000 ng/mL did not interfere. Inter-assay CVs in all three assays varied from 9 to 21%.

Antibodies, Monoclonal↗
PubMed1983

A monoclonal antibody to human brain-type creatine kinase. Increased avidity with mercaptans.

1. A monoclonal antibody (subclass immunoglobulin G1) has been raised against human brain-type creatine kinase (CK-BB). This antibody did not cross-react with either muscle-type creatine kinase (CK-MM) or heart-type creatine kinase (CK-MB). 2. The binding constant measured with native antibody was 6 X 10(8) M-1. In the presence of 2mM-dithiothreitol this constant was some 40-50-fold greater. 3. Partial reduction and alkylation showed that the increased binding was due to a direct effect on the antibody and was associated with concomitant cleavage of the heavy-heavy interchain disulphide bonds. The binding constant measured with Fab' fragments produced from reduced and alkylated antibody was similar to that shown by the native, unreduced antibody. 4. The molecular weight of the complex found in the absence of mercaptans was consistent with one antibody and one CK-BB molecule, whereas the molecular weight estimated with reduced and alkylated antibody was consistent with a complex of two antibodies and two CK-BB molecules. 5. It is proposed that mercaptans increase the flexibility of the hinge region of the antibody molecule, allowing the formation of a higher-order complex with increased avidity for the CK-BB dimer.

Alkylation↗
PubMed1983

PGP 9.5--a new marker for vertebrate neurons and neuroendocrine cells.

PGP 9.5 is a new cytoplasmic neuron-specific protein structurally and immunologically distinct from neuron-specific enolase. A specific antiserum has now shown that this protein is widely distributed in vertebrate brains and is also present in cells of the human diffuse neuroendocrine system. PGP 9.5 appears to be older than neuron-specific enolase in evolutionary terms, as an immunologically-related protein can be found in species as remote as the trout.

Animals↗
PubMed1983

A construct validity study of the Missouri Children's Behavior Checklist with developmentally disabled children.

Evaluated the construct validity of the MCBC scales and behavior profiles by determining the relationship between the MCBC and the clinical findings and recommendations that resulted from an interdisciplinary evaluation of children (N = 217) referred to a clinic for developmental disabilities. There were few differences in MCBC scale means and percentage occurrences of behavior profiles as a function of demographic factors and broad diagnostic categories. Substantial association was found between the MCBC and clinical findings of behavior problems. The association of the MCBC and clinical findings suggestive of affective problems was not as substantial, which suggests a need to augment the sensitivity of the MCBC in this area. The findings also suggested both the potential and the need for evolving additional MCBC behavior profiles that would reflect additional clinically meaningful subgroups among developmentally disabled children.

Adolescent↗
PubMed1983

Isolation of PGP 9.5, a new human neurone-specific protein detected by high-resolution two-dimensional electrophoresis.

Protein gene product (PGP) 9.5 is a new brain-specific protein originally detected by high-resolution two-dimensional electrophoresis of the soluble proteins of human brain and other organs. We have purified this protein from human brain and raised a rabbit antihuman PGP 9.5 antiserum. The protein has a monomer molecular weight of approximately 27,000 and is present in brain at concentrations at least 50 times greater than in other organs. Immunoperoxidase labelling has localised PGP 9.5 to neurones in the human cerebral cortex with no evidence of staining of glial elements. PGP 9.5 is estimated to be present in brain at concentrations of 200-500 micrograms/g wet weight and represents a major protein component of neuronal cytoplasm. This new neurone-specific cytoplasmic marker may prove useful in studies of neuronal development and in the detection of neuronal damage in disease of the nervous system.

Brain Chemistry↗
PubMed1982

Blood creatine kinase isoenzyme BB in boxers.

Creatine kinase isoenzyme BB (CK-BB) is found in high concentrations in the brain. Normally concentrations in blood are undetectable or low. Blood concentrations of CK-BB were measured in 16 boxers before and after a fight and in 16 track cyclists before and after a race. Blood CK-BB rose to significantly higher concentrations in the boxers than in the cyclists. The number of blows received to the head was estimated in half the boxers and correlated significantly with the rise in CK-BB. This increase in blood CK-BB may indicate disruption of the blood-brain barrier. This may be one of the mechanisms accounting for brain damage in boxers.

Adolescent↗