Biomedical subjects
Publications and source records attributed to C Dixon.
We report a case of pyoderma gangrenosum presenting as Fournier's gangrene. Although both processes have a similar presentation effective management is markedly different. Whereas broad-spectrum antibiotics and aggressive surgical débridement are necessary to control Fournier's gangrene, immediate institution of corticosteroids and local wound care are indicated for pyoderma gangrenosum.
Stimulation of quiescent Swiss mouse 3T3 fibroblasts either by serum or by the low molecular weight hormones, prostaglandin F2 alpha and insulin, induces DNA synthesis after a lag period of about 15 h. Following restimulation by serum or these pure hormones there is an overall increase of two- to fourfold in the rate of biosynthesis of nuclear proteins. In addition, there is a relative decrease in some proteins (Mr = 200 X 10(3), pI 6.0-6.5), while others increase (e.g. actin). Two polypeptides show specific correlations with the exit from G0. The synthesis of p30 (Mr = 30 X 10(3), pI 5.2) is at a maximum within 5 h of restimulation, while the synthesis of p36 (Mr = 36 X 10(3), pI = 4.25) is first seen at 10-20 h after restimulation. Synthesis of p36 correlates well with the initiation of DNA synthesis. The synthesis of both proteins is stimulated by serum and by the hormones. Thus there are common biosynthetic responses to different stimuli indicating convergent pathways leading to DNA biosynthesis. Addition of hydrocortisone with the growth-stimulatory hormones inhibits both entry into the S phase and biosynthesis of p36. In contrast, hydrocortisone does not alter the biosynthesis of p30. This 'early' protein, p30, is different from the products of both c-fos and c-myc. Therefore, we have identified two specific components that might participate in the regulation of cell proliferation.
We studied 7 asthmatics who had a history of symptoms exacerbated by ice-cold drinks. Bronchial responsiveness to inhaled histamine was measured before and after ingestion of 40 ml of ice or water at room temperature. Although there was no change in baseline peak flow, a significant increase in bronchial responsiveness to histamine developed by 90 min after the ingestion of ice. No satisfactory explanation could be found.
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Ten asthmatic children who gave a history of cough or wheeze after orange drinks, were tested for tartrazine sensitivity. On separate days, either oral tartrazine (1 mg) or a placebo capsule were administered double blind. Bronchial reactivity was measured before, 30 and 60 min after ingestion by means of a histamine-inhalation challenge test. There was no change in baseline lung function after tartrazine, but histamine sensitivity (PC20) increased significantly in four of the children. No response was obtained to a larger dose of tartrazine (10 mg) in four of the non-responders. Alteration in the bronchial reactivity after an oral challenge, appears to be a sensitive means of detecting tartrazine sensitivity.
Isocapnic hyperventilation dose response curves were constructed for 11 asthmatic children before and after pretreatment with placebo or ipratropium bromide, 40-1500 micrograms given by inhalation, on three separate days. The response before and after placebo was highly reproducible (within subject coefficient of variation 7.5%, 18%, and 22% for intervals of two hours, within two weeks, and over two weeks). It was independent of baseline lung function. Complete protection against hyperventilation induced asthma was achieved by ipratropium bromide 40 micrograms in six children and by 200 micrograms or more in a further four. The remaining child was unaffected by any dose of ipratropium up to 1500 micrograms. The dose of ipratropium required for protection was better related to the subjects' requirement for regular medication than to their sensitivity to hyperventilation or baseline lung function.
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The measurement of bronchial reactivity by histamine challenge testing is of increasing clinical importance in paediatrics. By means of a simple tidal breathing technique for the measurement of histamine sensitivity (expressed as PC20--the concentration of histamine which produces a 20% fall in peak flow rate) in childhood asthma, the reproducibility of pairs of tests was estimated over one hour and 24-hour intervals in 22 children. Under carefully controlled conditions the 95% confidence limits of PC20 were 0.8-1.25 X baseline PC20 after one hour and 0.36-2.8 X baseline PC20 after 24 hours.
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BRONCHIAL ASTHMA CAN BE DIAGNOSED WHEN A PATIENT DEVELOPS THE CLINICAL MANIFESTATIONS OF BRONCHIAL REACTIVITY: wheezing, cough, tachypnea, and dyspnea. Occasionally, despite immunotherapy, bronchodilator therapy, and avoidance of the provocative factors, some asthmatic patients do not respond to treatment. Bronchial inhalation challenge, a method to test airway reactivity after inhalation of a nonspecific drug, can be used to plan and assess different modes of treatment, as well as screen for bronchial hyperreactivity in an occupational setting.
In three patients, bronchopleural fistula developed after right pneumonectomy for bronchogenic carcinoma. In each instance, radiologic and clinical evidence was inconclusive. Xenon 133 regional ventilation-perfusion studies confirmed the diagnosis of a bronchopleural fistula in both the immediate and late postoperative periods.
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Mycoplasma pneumoniae pneumonia is usually a mild, self-limited disease. Complications are rare. A patient is presented with adult respiratory distress syndrome. Recognition of this unusual complication, presenting as a common disease syndrome, is emphasized.
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1. Using an in vitro everted gut sac method based on that of Wilson & Wiseman (1954), a number of amino penicillins were tested in order to identify the involvement of any specialized transport mechanisms in their absorption across rat intestine. 2. Only one of the amino penicillins, cyclacillin (1-amino-cyclohexyl penicillin) was shown to be actively transported. The other penicillins appeared to diffuse passively across the intestine. 3. Cyclacillin was found to concentrate against a gradient at 37 degrees C but not at 19 degrees C. 4. Transport of cyclacillin across the mucosal membrane was saturated at mucosal concentrations greater than 1000 microgram/ml. 5. The rate of the forward flux of cyclacillin was many times that of its back flux. 6. No relationship between the active transport of cyclacillin and that of amino acids could be demonstrated.