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Biomedical subjects

T H Barker

Publications and source records attributed to T H Barker.

16 recordsLinked to original sources
PubMed2003

A near fatal case of the dapsone hypersensitivity syndrome in a patient with urticarial vasculitis.

Dapsone (4,4'-diaminodiphenyl sulphone) is used for a variety of dermatological conditions including immunobullous diseases and urticarial vasculitis. Side-effects are common and include lethargy, headaches, methaemoglobinaemia and haemolysis. Severe adverse effects are rare but the dapsone hypersensitivity syndrome is well recognized. Symptoms include fever, haemolytic anaemia, lymphocytosis and hepatitis. We report a near fatal case of the dapsone hypersensitivity syndrome in a patient with urticarial vasculitis. This diagnosis should be remembered in any patient who becomes unwell whilst taking dapsone.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2003

Removal of organic debris from bovine dentin shavings.

A common problem with root canal failures is chronic inflammation at the apex caused by overfilling of root canal materials. Dentin filings have been suggested as an apical plug to create a biocompatible barrier between the filling material and the periapical tissue. Unfortunately residual organic material, such as pulp remnants or bacteria, still may be part of the filings. Dentin filings removed from the tooth, cleaned, and then used to form a barrier might serve as an effective barrier. The purpose of this study was to evaluate methods of cleaning dentin of organic debris. NaOCl, sodium dodecyl sulfate, and 1% Triton X-100 were used to treat dentin shavings and were evaluated by a micro bicinchoninic acid protein analysis assay. Two series of experiments were performed. One compared the effect of temperature while using phosphate-buffered saline as a control and the second compared exposure times. The percentage of protein extracted from dentin samples increased with temperature. Sodium hypochlorite at room temperature extracted 24.6%, NaOCl at 37 degrees C extracted 26.9%, and NaOCl at 70 degrees C extracted 33.9%. Only NaOCl at 37 degrees C and 70 degrees C showed statistically significant differences from phosphate-buffered saline at room temperature with p-values of 0.028 and 0.019, respectively. The exposure time series showed a difference between a phosphate-buffered saline solution and 6.25% NaOCl. NaOCl removed approximately 90% of protein compared with 60% for the phosphate-buffered saline. A 10-min exposure to 70 degrees C 6.25% NaOCl may be an efficient means of removing organic material from dentin shavings.

Animals↗
PubMed2001

Modification of fibrinogen with poly(ethylene glycol) and its effects on fibrin clot characteristics.

The suitability of existing topical fibrin glue preparations for tissue sealing or local drug delivery applications is greatly limited by their poor mechanical properties and the limited capacity of fibrinogen (Fgn) to actively bind growth factors or other therapeutic agents. Poly(ethylene glycol) (PEG) offers potential solutions to these problems by providing a mechanism for increasing the number of crosslinks between adjacent fibrin monomer molecules or for covalently crosslinking Fgn to therapeutic agents. The feasibility of this approach requires the full biological activity, or clottability, of PE glycolated Fgn. This study characterizes the clot characteristics of Fgn modified to varying degrees with monofunctional succinimidyl propionate PEG (5000 Da). The data indicate that, although thrombin clotting times are significantly altered, Fgn maintains 90% of its capacity to clot upon the addition of up to 5 PEG/Fgn. Further derivatization significantly decreases the Fgn clottability. The addition of up to 5 PEG/Fgn has little, if any, effect on the kinetics of degradation by plasmin. The results suggest that limited modification of Fgn with lysine-reactive PEG allows therapeutic enhancement of fibrin glues.

Biocompatible Materials↗
PubMed1999

Alcohol at moderate levels decreases fibrinogen expression in vivo and in vitro.

BACKGROUND: Consumption of moderate amounts of alcohol has been reported to exert a cardioprotective effect in individuals. The exact mechanism by which this occurs has not been fully explored. Circulating levels of the clotting protein fibrinogen have been unequivocally established as an independent risk factor for vascular diseases. This study examined the effects of moderate levels of ethanol on the expression of fibrinogen in an animal model and in hepatoma cells. METHODS: Out-bred Sprague-Dawley rats were fed 5% ethanol (v/v) in their water for 4 weeks, and circulating levels of fibrinogen were measured weekly via quantitative immunoassay. H4IIE rat hepatoma cells, which constitutively produce fibrinogen, were exposed to 10 and 20 mM ethanol, and fibrinogen production was determined. The effects of ethanol on fibrinogen messenger ribonucleic acids were determined by northern gel analyses. RESULTS: Our findings demonstrate that daily consumption of moderate amounts of ethanol decreases circulating levels of fibrinogen 18% to 20%. The decrease is reversible and is not gender specific. The exposure of hepatoma cells to ethanol also diminishes fibrinogen production by 20% by decreasing the transcription of fibrinogen genes. Alcohol concentration of 10 to 20 mM did not affect hepatoma cell viability or doubling time. CONCLUSIONS: The findings indicate that one likely positive benefit of moderate ethanol consumption is to diminish the production of fibrinogen, which reduces the potential risk exerted by this protein. The site of action of ethanol is, at least in part, exerted at the level of gene transcription.

Animals↗
PubMed1998

Idiopathic midline destructive disease--does it exist?

There is controversy whether idiopathic mid-line destructive disease remains a valid entity, some authors considering that such cases are unrecognized malignant lymphoma or Wegener's disease. A case is presented in which numerous nasal biopsies over several years failed to show evidence of either lymphoma or Wegener's disease. Molecular genetic analysis of archival tissue did not demonstrate a monoclonal lymphoid population. It is proposed that idiopathic mid-line destructive disease remains a valid description in a small number of cases.

Adult↗
PubMed1985

Early rheumatoid-like synovial lesions in rabbits drinking cow's milk. I. Joint pathology.

Rheumatoid-like lesions developed in 9 of 25 (36%) Old English rabbits drinking cow's milk for 12 weeks. The incidence of lesions in male and female animals was similar. The majority of rabbits drinking cow's milk developed increased numbers of nucleated cells and raised percentages of T lymphocytes in their synovial fluids, compared to control rabbits. The cell counts and T cell percentages correlated with the severity of the histological lesions. No evidence of glomerulonephritis was observed in any of the experimental animals.

Animals↗
PubMed1984

Nasal polyps. Scanning electron microscopy and artifact.

Nasal polyps are grossly oedematous tissue which has undergone considerable shrinkage when processed for scanning electron microscopy (SEM), converting the normally smooth surface into one with undulations. This shrinkage resulted in variable degrees of loss of the surface epithelium and thus gave rise to artifact. In its severest form, the entire surface epithelium was removed and the basement membrane exposed; lesser damage resulted in exposure of the basal cells, giving the previously described 'cobblestone' appearance. When the epithelium was intact, it was typical respiratory in type.

Adult↗