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J Robson

Publications and source records attributed to J Robson.

96 records · Page 6Linked to original sources
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Permeability measurement of macromolecules and assessment of mucosal antigen sampling using in vitro converted M cells.

INTRODUCTION: M cells are located in the epithelial layer covering the gut-associated lymphoid tissue and are responsible for delivery of macromolecules and microorganisms to the underlying lymphoid cells. It has been shown that the human colonic cell line Caco-2 can be converted to M cells in vitro following coculture with isolated lymphocytes from murine Peyer's patches. Studies were undertaken to evaluate and characterize the transepithelial transport of select macromolecules across these in vitro derived M cells. METHODS: Caco-2 cells were converted to M cells as reported previously. The morphology of Caco-2 cells and M cells was compared by transmission electron microscopy (TEM). The transport properties of macromolecules such as horseradish peroxidase, FITC-conjugated polystyrene beads, and radiolabeled dextrans were examined. The activation of murine antigen-specific T cells following transport of the antigen ovalbumin across the M-cell barrier was assessed by measuring cytokine production. RESULTS: M cells were shown to be irregular in shape and have fewer and shorter microvilli compared to the Caco-2 cell progenitors. These cells were still able to form tight junctions and monolayers on polycarbonate membranes. Time-course studies demonstrated that the transport of polystyrene beads and large-molecular-weight dextrans at physiological temperature across M-cell-containing monolayers was size dependent and more rapid than across Caco-2 cell monolayers. The transport of dextrans was also shown to be temperature and concentration dependent. Befitting the role of the M cell in mucosal defense, protein antigen could be delivered by these cells in order to be processed and presented to antigen-specific CD4+ T lymphocytes. DISCUSSION: The M-cell permeability model is a functional and practical system for evaluating the transport properties of macromolecules and assessing the potential for intestinal mucosal antigen sampling to elicit immunological responses.

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Enhancing communication in jargon aphasia: a small group study of writing therapy.

People with jargon aphasia have severely disordered and incomprehensible speech that may be resistant to therapeutic intervention. In this study, we treated written output and examined whether it assisted communication for these clients. In stage one of the study, anagram sorting, delayed copying and lexical decision tasks were used to investigate the residual knowledge of written words in a group of ten people with jargon aphasia. Evidence of the presence of orthographic knowledge was taken as an indication that writing might be a useful focus for therapy. This hypothesis was explored in stage two with six clients. A personally useful vocabulary was selected for each, and copying, word completion and written picture-naming tasks were used in therapy to improve written production of these words. The clients made progress in written naming. However, they showed little change on a 'message' assessment that tested their ability to use the written words to convey messages. Stage three targeted communicative writing. Here, three of the clients received 'message therapy', which encouraged them to relate treated words to functional messages and to communicate them to a partner. The clients improved on the message assessment and observation of their communication and reports from relatives suggested that they made functional use of writing in a range of communication settings.

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Written communication in undifferentiated jargon aphasia: a therapy study.

A subject, R.M.M., with a 2-year history of jargon aphasia is described. At the beginning of this study she had minimal meaningful spoken output and showed little awareness of her speech despite having relatively well-preserved auditory comprehension. Her spoken output had proved resistant to earlier periods of therapy. In contrast, R.M.M.'s written output showed some ability to access orthographic information and monitoring of this modality was shown by an acute awareness of her errors. A 3-stage therapy programme is described. This was designed to improve R.M.M.'s writing of single words and to encourage use of writing as an alternative means of communication. The initial stage of therapy aimed to increase R.M.M.'s access to written word forms by use of picture stimuli. She showed significant improvement in writing treated items in response to pictures both immediately after therapy and at re-assessment 6 weeks later. Despite the acquisition of these skills, R.M.M. failed to use them in communicative contexts. A second stage of therapy replicated the results of the first and sought to facilitate R.M.M.'s functional use of her written vocabulary by asking her to write words to spoken questions. She again showed improved written naming of the treated items and could now produce written names appropriately in a questionnaire-type assessment. Generalization of this ability extended to items that had not been trained in this way. Functional use of writing in everyday communication remained absent, however. The final stage of therapy made explicit the potential links between items which R.M.M. could now write and functional messages which they might convey. She again showed significant changes in the acquisition of new vocabulary and, encouragingly, progress was also seen in her use of the strategy in functional communication. R.M.M.'s speech is almost entirely incomprehensible. It has remained unchanged for 2 years and has not responded to therapy. Relatively well-preserved auditory comprehension and good monitoring of written output allowed therapy to effectively target a small written vocabulary. Despite significant progress in the acquisition of new items, transfer of this skill to functional communication was initially absent. Further therapy which specifically targeted the impairment causing this failure was needed before functional use was seen. The potential for treating written output in cases of jargon aphasia which have been resistant to therapy for spoken language is discussed.

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The effect of human serum in vitro on Trypanosoma (Trypanozoon) brucei species trypanosomes and its relationship to infectivity in the blood incubation infectivity test.

All attempts to identify Trypanosoma (Trypanozoon) brucei species trypanosome strains by their sensitivity or resistance to human serum in vitro have so far been unsuccessful. Wet-film examination of T.(T.) b. brucei, T. (T.)b. rhodesiense and T. (Nannomonas) congolense trypanosome strains, both before and after in vitro incubation in fresh human blood for 5 hours at 37 degrees C showed that serum-sensitivity or serum-resistance is not a constant and reproducible property of a trypanosome strain and is totally unrelated to infectivity.

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