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Biomedical subjects

G B Howe

Publications and source records attributed to G B Howe.

7 recordsLinked to original sources

Scleroderma and silicone breast implants.

A 43-yr-old caucasian female presented in July 1992 with an explosive onset of diffuse scleroderma following general anaesthesia for orthopaedic surgery. Her environmental exposures included silicone breast prosthetic surgery and silica exposure, both preceding development of scleroderma. She was DR5-negative, DRw52 positive. All currently available literature relating to breast implants and scleroderma is reviewed and the conclusion drawn that, for currently documented US data, there is no evidence to suggest that patients having had breast augmentation have rates of scleroderma higher than expected to chance alone. However the cause-effect relationship between silicone and scleroderma/other connective tissue disease requires, not just anecdotal reports, but a rigorously designed study.

Adult

Postexposure prophylaxis against experimental inhalation anthrax.

Inhalation anthrax is a rare disease that is almost invariably fatal. This study determined whether a prolonged course of postexposure antibiotics with or without vaccination would protect monkeys exposed to a lethal aerosol dose of Bacillus anthracis when the antibiotic was discontinued. Beginning 1 day after exposure, groups of 10 animals were given penicillin, ciprofloxacin, doxycycline, doxycycline plus vaccination, vaccination alone, or saline. Antibiotics were administered for 30 days and then discontinued. Vaccine was given on days 1 and 15. Two animals died of causes other than anthrax and were not included in the statistical analysis. Nine of 10 controls and 8 of 10 animals given only vaccine died. Each antibiotic regimen completely protected animals while on therapy and provided significant long-term protection upon discontinuance of the drug (penicillin, 7 of 10 survived, P < .02; ciprofloxacin, 8 of 9 survived, P < .002; doxycycline, 9 of 10 survived, P < .002; doxycycline plus vaccination, 9 of 9 survived, P < .0002). Protection against rechallenge was provided by combining postexposure antibiotic treatment with vaccination.

Aerosols

Polymorphonuclear cell function in rheumatoid arthritis and in Felty's syndrome.

Tests for polymorphonuclear cell (PMN) chemotaxis, adherence, and electrophoretic mobility (EPM) were carried out on blood PMN isolated from 27 normal subjects, 16 patients with uncomplicated rheumatoid arthritis (RA), and 9 patients with Felty's syndrome. Chemotaxis was measured by a modification of the Boyden chamber technique, adherence by retention of cells on nylon fibre columns, and EPM in a cylindrical electrophoretic assembly. There was no significant difference between the chemotactic migration of normal and rheumatoid PMN as assessed by the leading front measurement. However, PMN from patients with Felty's syndrome showed significantly reduced chemotaxis (P less than 0.001). Computerised image analysis showed this impaired migration to be due to an overall reduction in cell motility rather than loss of a subset cells. Activated serum from patients with RA and Felty's syndrome were as good chemoattractants as activated pooled AB serum. There was no significant difference in the adhesiveness of PMN from normal persons and rheumatoid patients, though PMN from patients with Felty's syndrome did show a trend to lower adhesiveness. Both RA and Felty's syndrome patients had an increase in the proportion of PMN of lower surface charge than controls. Direct correlations were observed between cells of high surface charge and nonadhesiveness.

Adult

Polymorphonuclear motility: measurement by computer-linked image analysis.

Most methods of measuring neutrophil motility provide information mainly about the performance of a small proportion of the fastest moving cells. Application of a computer-linked image analysis technique, using the "Quantimet," provides a convenient, automated method of measuring the motility of the whole cell population. This makes it possible to test whether changes in motility represent a homogeneous alteration affecting all cells or a change in the numbers or performance of a subset of cells. In this study the neutrophils from patients with uncomplicated rheumatoid arthritis were found to perform similarly to normals, while cells from patients with Felty's syndrome were markedly slower. This was an overall, homogeneous slowing of the whole cell population, not due to a loss of fast moving cells.

Cell Movement

The effects of enteric coating of aspirin tablets on occult gastrointestinal blood loss.

The effect of enteric coating of aspirin tablets on the gastrointestinal blood loss associated with high dose aspirin therapy was investigated in 12 patients with rheumatoid arthritis. Occult blood loss was measured after labelling the patients' red blood cells with Cr51. Three salicylate preparations were used: enteric coated tablets of aspirin ("Rhusal", G.P. Laboratories, 7 x 650 mg per day), uncoated tablet cores of aspirin from the same batch (7 x 650 mg per day) and enteric coated tablets of sodium salicylate (7 x 600 mg and 1 x 300 mg per day). Daily blood loss during a salicylate-free period was (0.7 +/- 0.15 ml, mean +/- SE). Blood loss was significantly increased during dosage with all three salicylate preparations. Daily blood loss during dosage with the uncoated tablets of aspirin (5.3 +/- 0.3 ml) was significantly greater than during dosage with the enteric coated tablets of aspirin (2.3 +/- 0.3 ml) and enteric coated tablets of sodium salicylate (2.1 +/- 0.4 ml). The bioavailability of the salicylate preparations was studied in seven of the 12 patients. Mean plasma salicylate concentration two hours after the second daily dose during dosage with the enteric coated tablets of aspirin was 118 +/- 15 microgram/ml compared to 131 +/- 16 microgram/ml during dosage with the uncoated tablets. Urinary recoveries of the daily dosage of aspirin in the two formulations were also similar.

Aged

Lysozyme-promoted association of protein I molecules in the outer membrane of Escherichia coli.

Incubation of whole envelopes prepared from sonically oscillated Escherichia coli K-12 cultures with lysozyme in vitro resulted in the appearance of a protein species with an apparent molecular weight double that of outer membrane protein I. Similar dimers were also detected in purified outer membranes and whole envelopes from lysozyme-induced spheroplasts of E. coli K-12. This was confirmed by two-dimensional electrophoresis in which the dimers were resolved in the second dimension to run as single polypeptides of protein I. Formation of dimers was correlated with peptidoglycan degradation, but the ability of protein I molecules to associate may vary between strains of E. coli, since dimers were found only in outer membranes from E. coli W7. We suggest that extensive degradation of peptidoglycan leads to nonspecific formation of protein I aggregates, but that these aggregates do not occur in vivo.

Bacterial Proteins