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Biomedical subjects

A J Robinson

Publications and source records attributed to A J Robinson.

At least 55 records · Page 3Linked to original sources
PubMed1999

[Analysis of hemopoietic progenitor cells in bone marrow and peripheral blood samples which have undergone different periods of cryopreservation].

Bone marrow (BM) and peripheral blood stem cell (PBSC) samples from patients undergoing autologous transplant were tested to evaluate the effects of cryopreservation. Cell viability was assessed as well as the proliferative capability of CFU-GM and BFU-E (myeloid and erythroid progenitors respectively). Moreover, long term culture (LTC) of stromal cells was used to test their functionality. A total of 23 samples were studied: 5 from AML patients, 7 MM, 6 NHL, 3 ALL and 2 HL. Nine patients received autologous bone marrow transplant (ABMT) and the remaining 14 PBSC. The cells were frozen during 24 to 33 days before infusion and 16 to 40 months before culture. Forty percent of AML and MM samples gave rise to colonies in vitro while the other hematology diseases tested showed colony growth in almost 100% of the cases. Samples from patients with lymphoid diseases exhibited a good correlation between the percentage of CD34+ cells and the number of colonies developed in culture. Nevertheless, there was no correlation when ALL and MM were tested suggesting that the underlying disease may have affected the growth in culture. The stromal layer was fully developed on BM samples, but on PBSC samples it only generated macrophages and fibroblasts. Our results suggest that the efficacy of cryopreservation of hematopoietic cells can be measured by means of CFU-GM and BFU-E culture and that the period the samples remained frozen did not affect the growth capability of the cells.

Adult↗
PubMed1998

Isolation and characterization of iridoviruses from the giant toad Bufo marinus in Venezuela.

In this communication we describe for the first time the isolation of 7 iridoviruses from the toad Bufo marinus and an unknown species of frog Leptodactylus in Venezuela, South America. The viruses are icosahedral with electron-dense cores, each of which is surrounded by an inner membrane, capsid and a cell-derived envelope. The virus(es) have an average vertex to vertex diameter of 160 nm and replicate in the cytoplasm of a range of cell lines. Within the cytoplasm of infected cells, rarefied areas could be observed; structures lacked cellular organelles and contained complete, empty and developing viruses. Results from antigen-capture enzyme-linked immunosorbent assays (ELISA) with polyclonal antibody raised against epizootic haematopoietic necrosis virus (EHNV) indicated cross-reactivity between these isolates, Bohle iridovirus (BIV) and frog virus 3 (FV3). Comparison of polypeptide and genomic profiles indicated that the Venezuelan viruses shared many polypeptides of equivalent molecular weight with type species FV3. There were, however, differences between the group of Venezuelan viruses and FV3 and BIV. The viruses belongs to the family Iridoviridae and the genus Ranavirus.

Animals↗
PubMed1998

Use of intravenous immune globulin in addition to antiviral therapy in the treatment of CMV gastrointestinal disease in allogeneic bone marrow transplant patients: a report from the European Group for Blood and Marrow Transplantation (EBMT). Infectious Diseases Working Party of the EBMT.

The best treatment of CMV gastrointestinal disease has been controversial, with some centers adding intravenous (i.v.) Ig to antiviral chemotherapy. The aim of this retrospective survey was to compare the outcome of antiviral chemotherapy with or without i.v. Ig. A questionnaire was sent to centers belonging to the EBMT. Thirty-three patients with CMV gastrointestinal disease were reported, 22 patients were given antiviral chemotherapy alone and 11 patients a combination of antiviral chemotherapy and i.v. Ig. Eighteen of 33 (55%) patients responded to therapy, 13 of those treated with antiviral chemotherapy alone and five (45%) of those treated with the combination (P = NS). Patients with acute GVHD of grades II-IV had significantly worse outcomes than patients with acute GVHD grades 0-I. In a Cox proportional hazards model corrected for acute GVHD there was no difference in outcome of CMV gastrointestinal disease with or without addition of Ig. Survival at 100 days after diagnosis of CMV gastrointestinal disease was 64%. There was no difference in survival in patients treated with or without i.v. Ig. The results of this retrospective survey indicate that addition of i.v. Ig to antiviral chemotherapy might not improve outcome in patients with biopsy-proven CMV gastrointestinal disease.

Adolescent↗
PubMed1998

Sexually transmitted organisms in sexually abused children.

OBJECTIVE: To establish the prevalence of sexually transmitted organisms and other genital organisms in potentially sexually abused children. DESIGN: Prospective study of children attending an inner London department of community paediatrics for evaluation of possible sexual abuse. SUBJECTS: Children under 16 referred for evaluation of possible sexual abuse. OUTCOME MEASURES: Prevalence of sexually transmitted organisms in relation to age, symptoms, and type of abuse. RESULTS: Swabs were taken from 159 of 242 girls evaluated. The overall prevalence of sexually transmitted organisms was 3.7%: three girls were infected with gonorrhoea, four with Trichomonas vaginalis, and two with Chlamydia trachomatis. One girl had all three infections plus mycoplasmas. Mycoplasmas were identified in 22% of girls swabbed. Of 30 boys swabbed, none yielded a sexually transmitted organism. CONCLUSIONS: There is a low prevalence of definitely sexually transmitted organisms in children who might have been abused. Other organisms possibly associated with sexual activity can be identified in this population. Screening for infection should be mandatory in presumed sexually abused girls with vaginal discharge and ideally should be undertaken in all children attending for evaluation of sexual abuse.

Adolescent↗
PubMed1997

Warfarin analog inhibition of human CYP2C9-catalyzed S-warfarin 7-hydroxylation.

Human metabolism of the S-warfarin enantiomer is catalyzed primarily by cytochrome P4502C9 (CYP2C9), which, because of the enzyme's broad drug substrate specificity, leads to drug-S-warfarin interactions. Several warfarin analogs have been synthesized and used to determine whether they exhibit diminished interactions with CYP2C9. The kinetics of the warfarin analogs' inhibition of human liver microsomal CYP2C9 catalyzed metabolism of S-warfarin to S-7-hydroxywarfarin have been investigated. R- and S-7-fluorowarfarin were both predominantly competitive inhibitors, whereas racemic 6-fluorowarfarin and racemic 6,7,8-trifluorowarfarin were predominantly mixed inhibitors with some competitive inhibition. For the alcohols produced by reductive methylation of the side chain of R- and S-warfarin, the R-enantiomer did not inhibit S-warfarin metabolism, whereas the S-enantiomer was primarily a competitive inhibitor. The fluorine substituted warfarins and the S-warfarin alcohol apparently bind with high affinity to CYP2C9. Thus their use clinically (if efficacious) would not prevent CYP2C9 associated warfarin-drug interactions. The R-warfarin alcohol did not inhibit CYP2C9 catalyzed metabolism of S-warfarin and is less likely than warfarin to participate in CYP2C9 associated warfarin-drug interactions.

Aryl Hydrocarbon Hydroxylases↗
PubMed1997

The characterization of potent novel warfarin analogs.

Racemic sodium warfarin, Coumadin, is widely used in the prevention of thromboembolic disease. The present study was undertaken to characterize three novel classes of warfarin analogs, and to compare them with the warfarin enantiomers. All three classes of compounds inhibit vitamin K epoxide reductase, the enzyme inhibited by racemic warfarin. The alcohol and the ester analogs have reduced protein binding compared with R-(+)-warfarin. The ester and the fluoro-derivatives have similar in vivo anticoagulant activity in the rat to that of S-(-)-warfarin. Thus, it is possible to synthesize novel warfarin analogs that differ from racemic warfarin or its enantiomers in certain selected properties.

Animals↗
PubMed1997

A novel strategy for determining protective antigens of the parapoxvirus, orf virus.

We investigated the feasibility of using vaccinia virus (VAC) recombinants containing large multigene fragments of orf virus DNA to identify protective antigens of orf virus (OV). Sixteen OV strain NZ2 DNA fragments with an average size of 11.4 kb were recombined into VAC strain Lister. Each fragment was mapped relative to OV restriction endonuclease maps but was otherwise uncharacterized. Together the recombinants represent 95% of the OV genome in an overlapping manner. Immunofluorescence showed all 16 constructs expressed products recognized by OV antiserum and radioimmune precipitation with the same antiserum allowed the localization of the major antigens of OV to specific recombinants. These data indicated the approximate genomic locations of the genes encoding the OV major antigens and showed that their expression was authentic rather than resulting from read through from VAC sequences adjacent to the site of recombination. Vaccination of OV-naive sheep with the recombinant library provided protection against a subsequent challenge with virulent OV. These data confirm the feasibility of the proposed strategy.

Animals↗
PubMed1997

Progress towards using recombinant myxoma virus as a vector for fertility control in rabbits.

The history of myxoma virus, its use in Australia as a mortality agent and the development of the virus as a vector for controlling fertility in wild rabbit populations in Australia is reviewed. Myxoma virus recombinants have been constructed to express model antigens. Four potential insertion sites in the genome have been identified and two have been used to construct single and double recombinant viruses expressing Escherichia coli enzymes beta-galactosidase and beta-glucuronidase. Another recombinant expressing an influenza virus haemagglutinin gene (A/PR8/34) induced high and sustained antibody responses following intradermal inoculation in rabbits. To demonstrate the potential of introducing a recombinant virus into wild rabbit populations, a virus containing a natural deletion was released at four field locations. Preliminary analysis of the data has shown that the introduced virus spread well on 3 of the 4 locations. The steps being taken to address the ethical and safety implications of the introduction of a recombinant virus into the field are discussed.

Animals↗
PubMed1997

Novel techniques for visualising biological information.

The major challenge facing the bioinformatics community is the continuing increase in the number, size and complexity of biological databases with which it must contend. The goal of the research discussed herein is the development and utilisation of techniques that allow researchers to extract new and useful information from these burgeoning information resources using advanced visualisation methods and paradigms, coupled with distributed object technologies that allow communications between applications and remote databases. Visualisation has roles not only in analysis, but also in building more user-friendly interfaces, implementing methods to navigate large information spaces intuitively and powerful techniques to browse and query data. By using platform-independent object-oriented programming languages, these resources may be developed as reusable pieces of software componentry with their methods and interfaces defined fully, and then distributed through organisations such as the bioWidget Consortium. The widget and object-oriented approach is a powerful paradigm in developing new applications from existing components. Development time is reduced and greater time is spent on analysing these data, rather than in the writing of monolithic applications. More powerful applications can be constructed from components interacting in concert and offers the opportunity of a new generation of bioinformatics tools.

Base Composition↗
PubMed1996

Prediction of the three-dimensional structure of human interleukin-7 by homology modeling.

The three-dimensional structure of human interleukin (IL)-7 has been predicted based on homology to human IL-2, IL-4, granulocyte-macrophage colony stimulating factor and growth hormone. The model has a topology common to other cytokines and displays a unique disulfide pattern. Knowledge of the tertiary structure of IL-7 has implications for analysis of key binding regions, suggestions for mutagenesis experiments and design of (ant)agonists. In this context, the model is discussed and compared with other cytokine structures.

Amino Acid Sequence↗
PubMed1996

Location, DNA sequence and transcriptional analysis of the DNA polymerase gene of orf virus.

Degenerate oligonucleotides representing conserved regions of various DNA polymerases hybridized to a region located 26 kb from the left end of the orf virus (OV) strain NZ-2 genome. DNA sequence analysis of this region revealed a 3024 bp open reading frame able to encode a protein with 56 percent amino acid identity to the DNA polymerase of vaccinia virus (VAC) and with significant homology to other DNA polymerases. Early transcripts derived from the open reading frame were detected in RNA purified from OV-infected cells, and 5' ends were mapped to a region 8-19 nt downstream from an A/T-rich sequence that resembles VAC early promoters. Unlike the VAC gene, the OV DNA polymerase makes almost exclusive use of G/C coding options. Attempts to substitute the activity of the OV DNA polymerase for its VAC counterpart were unsuccessful. This may indicate that the OV DNA polymerase is incompatible with VAC accessory proteins.

Amino Acid Sequence↗