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Biomedical subjects

J C Richardson

Publications and source records attributed to J C Richardson.

At least 19 recordsLinked to original sources
PubMed1999

Royal British Legion war grave pilgrimages: a medical escort's perspective.

The Royal British Legion organizes pilgrimages to nearly all parts of the world where British servicemen and service-women and their allies fought and died. The Pilgrimage Department has taken thousands of widows, other relatives, veterans and friends to visit the grave of a loved one or comrade buried overseas. The parties of pilgrims are escorted by Service medical officers and nurses of the Regular and Reserve Armed Forces. The role of the medical escort is described.

Bereavement↗
PubMed1998

The M31 gene has a complex developmentally regulated expression profile and may encode alternative protein products that possess diverse subcellular localisation patterns.

HP1-like chromobox genes comprise an evolutionarily conserved family of genes that encode components of centromeric heterochromatin. In order to investigate the role of the murine HP1-like gene, M31, in heterochromatin formation we have isolated its gene and characterised its transcripts and protein products. PCR products that represent M31 transcripts were detected at the one-cell stage and were maternal in origin. Maternal provision of M31 transcripts may reflect a need for M31 in the formation of a functional centromere in order that there is proper segregation of chromosomes during the early cleavage divisions; studies in fission yeast and Drosophila have suggested a crucial role for HP1-like genes in centromere function. There are three protein products encoded by the M31 gene. Surprisingly, the two smaller products are found almost exclusively in the cytoplasm.

Alternative Splicing↗
PubMed1996

Identification of a set of proteins (C' and C) encoded by the bicistronic P gene of the Indiana serotype of vesicular stomatitis virus and analysis of their effect on transcription by the viral RNA polymerase.

Previous work (C.F. Spiropoulou and S.T. Nichol, 1993, J. Virol. 67, 3103-3110) has demonstrated the existence in cells infected with the New Jersey serotype of vesicular stomatitis virus (VSV) of two small carboxy-coterminal proteins encoded by the P mRNA. These proteins have been named C' and C. We are interested in studying the function of these proteins in the virus life cycle. Toward this end, we have cloned the ORF encoding the potential C' protein of the Indiana serotype as a histidine-tagged fusion protein, purified the expressed protein from Escherichia coli, and used the fusion protein as an immunogen to raise antiserum in a rabbit. We have used this anti-C' protein serum to demonstrate that both of the predicted C' and C proteins are synthesized in cells infected with the Indiana serotype of VSV. In addition we have localized a portion of these proteins to nucleocapsids isolated from infected cells, suggesting that they may play a role in RNA synthesis. Reconstitution of the viral polymerase activity by expressing the L and P protein subunits with or without the C proteins failed to demonstrate any effect of the presence of these latter proteins on reconstituted transcription using purified nucleocapsids as templates. However, we have been able to show a dramatic stimulation of the polymerase activity in purified virions by the addition of purified C' protein to in vitro transcription reactions. Both the level and the fidelity of mRNA synthesis are stimulated by this protein. Evidence for the specificity of this effect comes from the fact that stimulation appears to be serotype specific; C' protein of the Indiana serotype stimulates transcription by purified Indiana serotype virions but has a minimal effect on transcription by purified virions of the New Jersey serotype. We are continuing our studies to determine the mechanism of this stimulation.

Animals↗
PubMed1996

Inhibition of VSV genome RNA replication but not transcription by monoclonal antibodies specific for the viral P protein.

The growth of vesicular stomatitis virus requires two distinct RNA synthetic events: transcription of messenger RNA molecules and replication of the viral genome RNA. We report the use of a panel of monoclonal antibodies directed against the viral phosphoprotein P in an attempt to assess the role of this protein in RNA synthesis. Using extracts derived from virus-infected cells, we show that several anti-P monoclonal antibodies can have an inhibitory effect on genome RNA replication by binding to a soluble form of the P protein. We also show that the P protein to which one of these antibodies (6D11) is directed is not complexed with the N protein and that the amount of soluble P protein that binds to the 6D11 antibody in immunoprecipitation reactions can be increased by treating extracts with alkaline phosphatase. In addition, phosphatase treatment of infected cell extracts results in an increased level of genome RNA replication. These results suggest that a soluble subspecies of the P protein that functions in genome RNA replication exists in infected cells and that this species of the P protein is not required for transcription.

Alkaline Phosphatase↗
PubMed1995

Developmental effects of over-expression of normal and mutated forms of a Xenopus NF-kappa B homologue.

High level over-expression of XrelA1, a homologue of the p65 sub-unit of NF-kappa B and of Drosophila dorsal, arrests Xenopus development at the gastrula stage, producing a reduction in the levels of expression of various genes of developmental interest without general reduction in transcription or cessation of cell division. There is little Goosecoid expression, even though a dorsal lip forms. At lower levels XrelA1 mRNA primarily produces disruption of the mid-dorsal axis. A dominant interference gene product, delta 222, produces mainly posterior, but also anterior abnormalities. On the basis of these results we postulate that the role of XrelA1 in the vertebrate embryo is unlikely to be in dorsoventral development, but more likely in the formation of the termini.

Animals↗
PubMed1994

XrelA, a Xenopus maternal and zygotic homologue of the p65 subunit of NF-kappa B. Characterisation of transcriptional properties in the developing embryo and identification of a negative interference mutant.

We have isolated two clones (XrelA.1 and XrelA.2) from Xenopus ovary representing differentially processed mRNAs homologous throughout their translated regions to the mammalian p65 subunit of NF-kappa B. The transcripts are ubiquitously present throughout development, but are most abundant in late blastulae and gastrulae. Overproduced protein shows nuclear localisation in both oocytes and early embryos. The XrelA.2 product bound to DNA as an oligomer which was not detected in the normal embryo. Two endogenous kappa B-binding complexes were present, showing no stage-specific variation, although one was relatively deficient in posterior regions of the early neurula. They were not disrupted by dimerization with over-expressed XrelA, suggesting that they were not produced by NF-kappa B/Rel/dorsal family members. The transcriptional properties of the cloned XrelA were assayed in intact embryos by co-injecting XrelA mRNA and a linear HIV LTR-driven CAT reporter gene. CAT levels were stimulated 20-30-fold by XrelA mRNA levels in the 100 pg range, and this was wholly dependent on NF-kappa B binding sites, and largely dependent on those for SP-1. These results were remarkably reproducible and show that quantitative analysis of transcription factor function is possible in intact developing Xenopus embryos A mutant lacking the transcriptional activation domain antagonised co-injected wild-type XrelA, providing a potential dominant negative p65 mutant for interfering with NF-kappa B function in analysing NF-kappa B function in normal development.

Amino Acid Sequence↗
PubMed1993

MHC class I gene expression is negatively regulated by the proto-oncogene, c-jun.

The trans-acting factor AP-1 is a heterodimeric complex composed of c-Jun and c-Fos family proteins which bind and regulate genes containing a TPA responsive enhancer element. Although AP-1 binding sites have been identified within the regulatory region of major histocompatibility complex (MHC) class I genes in vitro, the role of AP-1 in regulating MHC class I transcription in vivo has not been investigated previously. The present study demonstrates that expression of c-Jun results in decreased MHC class I promoter activity as determined in cotransfection assays of an MHC class I reporter construct with a c-Jun expression construct. The c-Jun responsive element is located between bp -440 and -431 upstream of initiation of transcription as determined both functionally and by direct binding of purified c-Jun. Furthermore, over-expression of c-Jun reduced the steady state levels of endogenous MHC class I RNA in murine L cells by approximately 10-fold. These data indicate that c-Jun/AP-1 acts as a negative trans-acting factor that down-regulates MHC class I gene expression.

Animals↗
PubMed1993

Creation of mice expressing human antibody light chains by introduction of a yeast artificial chromosome containing the core region of the human immunoglobulin kappa locus.

We have previously described a strategy for integrating selectable marker genes into yeast artificial chromosomes (YACs) to facilitate their transfer into embryonic stem (ES) cells. Here we apply this technology to create mice carrying the core region of the human immunoglobulin (Ig) kappa light chain locus. A YAC was isolated which contains a 300 kb insert spanning three V kappa segments, the J kappa cluster, the C kappa region and extending downstream of the Kde element. After modification of this YAC to integrate the selectable neo marker gene, the YAC was introduced into ES cells by protoplast fusion. Several ES cell clones were obtained which appeared to harbor one complete copy of the YAC while retaining little or no other yeast DNA. The ES cells were injected into blastocysts and the chimaeric mice were shown to rearrange the introduced human light chain genes with the resultant production of antibodies containing human kappa light chains in the serum.

Animals↗
PubMed1992

In vivo function of regulatory DNA sequence elements of a major histocompatibility complex class I gene.

Major histocompatibility complex class I genes are expressed in nearly all somatic tissues, although their level of expression varies. By analysis of a set of promoter deletion mutants introduced into transgenic mice, a complex regulatory element, consisting of overlapping enhancer and silencer activities, is demonstrated to function as a tissue-specific regulator of class I expression. The enhancer activity predominates in lymphoid tissues but not in nonlymphoid tissues. In contrast to the tissue-specific functions of the complex regulatory element, a second novel silencer element is shown to function in both lymphoid and nonlymphoid tissues. The complement of DNA-binding factors in different cell lines is shown to correlate with the levels of class I expression.

Animals↗
PubMed1991

NS2 protein of influenza virus is found in purified virus and phosphorylated in infected cells.

Purified viral preparations of influenza A virus were examined for the presence of NS2 protein hitherto considered as a viral nonstructural protein that is present only in infected cells. Analysis of purified virus by radioimmunoprecipitation with monospecific antisera to NS2 revealed its presence in the virus particle suggesting that it is a viral structural protein. NS2 protein was also shown to be phosphorylated in infected cells in this study. This brings the number of influenza virus phosphoproteins to three which include NP, NS1, and NS2. These observations raise important questions about the role of NS2 in the replication of influenza virus.

Capsid↗
PubMed1991

Heterogeneous forms of polymerase proteins exist in influenza A virus-infected cells.

In influenza virus-infected cells a virus coded polymerase that consists of three polypeptide subunits, namely PB1, PB2 and PA, mediates both transcription and replication. Radioimmunoprecipitation with monospecific antisera to each of the polymerase proteins revealed additional forms of PB1 and PA proteins in infected cells. PA antiserum detected two additional proteins of 62k and 60k and PB1 antiserum recognized two additional proteins of 85k and 70k. Further investigation was carried out on the 62k PA and 85k PB1 related proteins. Limited proteolysis peptide mapping showed that these proteins are subsets of their normal counter-parts. These new forms of polymerase proteins are designated as "b" forms (PAb and PB1b) to distinguish them from the previously recognized forms designated as "a" forms (PAa and PB1a). Both PAb and PB1b proteins were found in cells infected with all the influenza type A viruses tested indicating that they are evolutionarily conserved. Pulse chase experiments showed that the "b" forms are not derived from "a" forms. This suggested that "b" forms are translated independently. The "b" forms were not detected in purified virus but were found to be associated with intracellular RNP templates, suggesting a role for these proteins in intracellular virus replication events.

Animals↗
PubMed1990

The use of primed cytotoxic T lymphocytes as a highly sensitive and accurate method for the detection of MHC disparate allogeneic cells.

The present studies have investigated the use of primed cytotoxic T cells (CTL) for the purpose of detecting the presence of an MHC disparate allogeneic cell population. The findings indicate that restimulation of primed CTL in the presence of activated T cell supernatants is an extremely sensitive method capable of detecting one allogeneic cell within a population containing 10,000 total cells (0.01%). In addition, this primed lymphocyte cytotoxicity assay (PLCA) was shown to be at least as accurate as flow cytometric analysis in determination of low numbers and percentages of allogeneic cells within the cell population being examined. Furthermore, the nature of the allogeneic mononuclear population did not influence the sensitivity or accuracy of this method. To examine this method's applicability for the detection of chimeric populations in vivo, spleen and thymic tissue from neonatally tolerized animals were examined by PLCA analysis. Allogeneic cells were readily detected in 100% of individual host spleen and thymuses tested. In total, the results showed that the PLCA is a highly reproducible and accurate method for the detection of extremely low numbers of allogeneic cells. This approach should be useful to monitor the presence of foreign cells in experimental and clinical situations in which individuals are exposed to allogeneic cell populations.

Animals↗
PubMed1989

Group purchasing.

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Conflict, Psychological↗
PubMed1989

Exploring the persistent black risk of low birthweight: findings from the GLOWBS Study.

Results are presented from the Galveston Low Birthweight Survey (GLOWBS) Study, a tri-ethnic survey (N = 1,179) of live, single births, conducted in Galveston, Texas, from 1986 to 1987. Four principal findings emerged pointing to a persistent black risk for low birthweight (less than 2,500g). First, black infants (2,997g) have significantly lower mean birthweight than either Anglos (3,281g) or Hispanics (3,270g). Second, blacks are at significantly higher risk of low birthweight than nonblacks (risk ratio = 1.71). Third, despite controlling for a variety of pregnancy- and health-related, psychosocial, socioeconomic, and health services factors (including even gestational length), being black still exerts a significant, inverse effect on birthweight (beta = -0.137). Fourth, of the above factors only gestational length (R2 = 0.39) accounts for more than a negligible amount of the total variance in birthweight among blacks. These findings are discussed, and several lines of follow-up research are proposed.

Black or African American↗
PubMed1987

Utilization of antigen specific cytotoxic T-cells as a sensitive approach to investigate the fate of placentally injected allogeneic lymphocytes.

In this report we present a model for the introduction of immunocompetent populations during murine gestation and the subsequent detection of allogeneic cells in the offspring. A highly sensitive in vitro assay, the primed lymphocyte cytotoxicity assay, which can detect extremely low numbers of allogeneic cells residing within host tissue is described. Primed cytotoxic T cells specific for class I antigens were found to be restimulated by as few as 10-50 allogeneic spleen cells from within 10,000 syngeneic neonatal spleen or liver cells. Various tissues derived from neonatal mice which had been placentally injected 1 or 10 days previously were found to contain markedly different percentages of "chimeric" cells in the neonatal organs examined. Notably, while spleen and lung contained more allogeneic cells early following injection, 10 days later the liver contained the highest percentage and the thymus and spleen a significantly lower percentage of allogeneic cells. These findings are discussed with respect to the possible enhancement or depression of the offspring's immune responsiveness following interaction with alloantigen bearing lymphoid cells.

Animals↗
PubMed1987

Absence of mutagenic activity of benorylate, paracetamol and aspirin in the Salmonella/mammalian microsome test.

Benorylate and its two major hydrolysis products, paracetamol and aspirin were examined for mutagenicity in the Salmonella/mammalian microsome screening test. The compounds were tested in 6 strains of Salmonella typhimurium (TA1535, TA1537, TA1538, TA100, TA97 and TA98) in the presence and absence of a rat-liver microsome activation system. Benorylate did not show evidence of mutagenic activity in the 6 strains tested with or without metabolic activation at concentrations ranging from 0.006 to 3 mg per plate. Paracetamol and aspirin likewise did not show any evidence of mutagenic activity at concentrations ranging from 0.1 to 50 mg per plate for the former and 0.01 to 50 mg per plate for the latter.

Acetaminophen↗