Biomedical subjects
Publications and source records attributed to R Allan.
Pseudomonas maltophilia cell-wall deficient forms were induced using a medium containing carbenicillin and polyvinyl pyrrolidone. Scanning electron microscopy proved to be a very effective method of demonstrating the various phases. It is suggested that the rapid rate of reversion to bacterial forms could have been due to plasmids.
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We have reviewed our experience with, and management of, entero-enteric fistula in Crohn's disease between 1970 and 1980 (inclusive). Thirty-three patients (20 of them female) came to our unit with entero-enteric fistulas, representing one-third of all Crohn's fistulas seen during those years. Entero-enteric fistulas gave few symptoms and their precise identification was not important in clinical management. The presence of the fistula itself is not an indication for operation and treatment should be directed towards the active or stenotic disease and not to the entero-enteric fistula. Therefore, radiological examination is important only to identify the extent of underlying disease.
The consumption of sugar and sugar-containing foods in 32 patients with recently diagnosed Crohn's disease was significantly greater than in matched controls; the assessment was made by a questionnaire and depended upon patients recalling their eating habits. In a further study of 16 patients with Crohn's disease, all food eaten over 5 days was weighed and recorded, and no significant difference was found in the consumption of carbohydrate, protein, fats, or sugars, although the consumption of "added sugars" in patients was greater than controls. Patients who participated in both studies significantly reduced their intake of added sugar, and this was not found to correlate with either total intake of monosaccharides and disaccharides or the total carbohydrate consumption. The increased consumption of added sugar in patients with Crohn's disease does not appear to be related to other dietary abnormalities and may simply reflect a deficiency in perception of sweet taste in patients with this condition.
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Several groups of compounds were examined for their ability to inhibit in vitro the binding of Clq to insoluble immune complexes. As expected from previous studies, polyinosinic acid, liquoid, sodium pentosan polysulfate, aliphatic diamines and heparin are good inhibitors. This study shows that compounds with much lower toxicity, such as certain amino acids and substances with vitamin B6 activity (pyridoxal-5-phosphate:P5P) were also capable of decreasing the binding of Clq. Using methods of equilibrium dialysis and difference spectra, it was shown that this compound binds to both, Clq und IgG antibody by forming Schiff bases. Clq binds approximately 10 times more P5P when compared to IgG. Immune complexes prepared with IgG antibody modified by P5P and stabilized with sodium borohydride had the same complement-fixing and Clq-binding capacity as normal immune complexes. This suggests that the inhibition of Clq-binding to immune complexes by P5P is due to a modification of lysyl resides in Clq. Collagen and IgG fragments derived from Fc were also found to inhibit Clq binding to immune complexes, but at higher concentrations than the above small-molecular compounds and with a different mode of action.
Koshland's reagent (2-hydroxy-5-nitrobenzyl bromide (NBB)) has been shown to modify tryptophanyl residues in anti-ovalbumin IgG. As little as 2 moles NBB/mole IgG antibody are sufficient to block the classical pathway of complement activation when the antibody is complexed to antigen (ovalbumin). In contrast, immune complexes containing antibody with the same degree of tryptophanyl substitution will activate the alternative pathway of complement fixation. Immune complexes containing F(ab')2 fragments derived from anti-ovalbumin IgG do not activate the classical pathway. When measuring the percentage activation of C3 using the method of Laurell, NBB does not affect the alternative pathway of the complement system up to a molar ratio of 2 NBB/F(ab')2. The above findings, provide a means to evaluate the relative contribution of complement activation by the different pathways.
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This paper describes the clinical management of 204 patients with Crohn's disease involving the colon who have been reviewed regularly for many years. The results have been analyzed to define the morbidity, mortality, and long term prognosis of the disorder. Despite a high morbidity, the long term prognosis is good. Although the mean interval since the onset of symptoms is more than 13 years, 77% of the patients are symptom-free and 60% have normal laboratory indices. This analysis suggests that until the etiology of Crohn's disease is established and a specific therapy is developed, good results can be obtained with regular medical review and appropriate surgical treatment with the limited use of immunosuppressive agents or total parenteral nutrition.
A prospective study is reported of 300 consecutive patients admitted to the General Hospital, Birmingham, because of acute gastrointestinal haemorrhage. The characteristics of the group have been outlined and the causes of death examined. It is shown that in patients diagnosed as having peptic ulcer or erosions, the major causes of death were thrombotic vascular disease and surgical complications. Current policies in the management of gastrointestinal bleeding are examined in this light, and it is concluded that gastric resection should be avoided wherever possible, and that procedures should be considered which might reduce intravascular clotting. The advisability of immediate surgery is also questioned and a case made for consideration of a policy of more prolonged resuscitation. A detailed analysis of mortality rates is included from reported European series, with particular reference to the increasing proportion of older patients. Taking this into consideration, it is argued that mortality rates are continuing to improve, and that early diagnosis must be an important contributory factor. It is also pointed out that not only are nearly half the patients in present studies over the age of sixty, but also the risk of developing such a haemorrhage is much greater in the older sections of the community. Gastrointestinal bleeding is more of a geriatric than an adolescent problem.
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Bidirectional sodium flux across the intestinal mucosa was measured in a group of 10 patients with Crohn's disease treated in the past by panproctocolectomy with ileostomy and compared with a similarly treated group of 11 patients with ulcerative colitis. All of them were in good health at the time of the study and a recent radiological examination of the small intestine was normal. A significant reduction in bidirectional sodium flux was found in those patients with Crohn's disease and suggests that the intestinal mucosa is involved to a greater extent than can be judged by radiological appearances alone. This adds weight to the concept that Crohn's diseases is a diffuse rather than a focal lesion of the gastrointestinal tract.
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