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Biomedical subjects

C P Warren

Publications and source records attributed to C P Warren.

At least 19 recordsLinked to original sources
PubMed2002

Geography in a scale-free network model.

We offer an example of a network model with a power-law degree distribution, P(k) approximately k(-alpha), for nodes, but which nevertheless has a well-defined geography and a nonzero threshold percolation probability for alpha>2, the range of real-world contact networks. This is different from p(c)=0 for alpha<3 results for the original well-mixed scale-free networks. In our lattice-based scale-free network, individuals link to nearby neighbors on a lattice. Even considerable additional small-world links do not change our conclusion of nonzero thresholds. When applied to disease propagation, these results suggest that random immunization may be more successful in controlling human epidemics than previously suggested if there is geographical clustering.

Journal Article↗
PubMed2001

Fluctuation effects in an epidemic model.

We study a discrete epidemic model A+B-->2A in one and two dimensions (1D and 2D). In 1D for low concentration theta, we find that a depletion zone exists ahead of the front and the average velocity of the front approaches v=theta/2. In the 1D high concentration limit, we find that the velocity approaches v=1-e(-theta/2). In 2D, for low concentration we also find a depletion zone, and the velocity scales as v approximately theta(0.6), which is different from the scaling expected from the mean field approximation, v approximately theta(0.5). Analysis of the interface width scaling properties demonstrated that the front dynamics of this reaction are not governed by the Kardar-Parisi-Zhang equation.

Journal Article↗
PubMed1993

Occupational asthma induced by inhaled egg lysozyme.

A 26-year-old man employed in a company which manufactured hen egg white derived lysozyme for use in the pharmaceutical industry was evaluated for occupational asthma. The worker began to experience immediate-onset asthmatic symptoms two months after starting to work with egg lysozyme powder. The work process involved the production of approximately 1,000 kg of purified dried lysozyme powder per week. Prick skin testing was positive to egg lysozyme (50 mg/ml) and other egg protein components, but negative to whole egg white and egg yolk reagents. Serum specific IgE to egg lysozyme was documented. Decrements in serial peak expiratory flow rates were associated with lysozyme exposure at work. A specific bronchoprovocation challenge to lysozyme powder was positive demonstrating an isolated immediate asthmatic response (48 percent decrease from baseline FEV1). This is the first reported case of lysozyme-induced asthma specifically caused by inhalational exposure to egg lysozyme.

Adult↗
PubMed1993

A placebo-controlled dose-finding study with bambuterol in elderly patients with asthma.

A new long-acting bronchodilator prodrug, bambuterol hydrochloride, was tested in a randomized, crossover, and double-blind study in elderly asthmatic patients (aged 64 to 82 years). They received placebo and 5-mg, 10-mg, and 20-mg tablets once daily for a week at each dose. The plasma concentration of the active metabolite, terbutaline, increased linearly with the dose of drug (p < 0.001). Peak expiratory flow rate increased with dose in the morning (p < 0.001 for 10-mg and 20-mg doses) and afternoon (p < 0.05 for 10 mg; p < 0.001 for 20 mg) and was different from placebo for the 10-mg/d and 20-mg/d regimens. The use of supplemental inhaled beta 2-adrenergic agonist therapy was reduced during the night for the 10-mg (p < 0.05) and 20-mg (p < 0.01) doses in comparison to placebo. No significant effects of treatment on blood pressure and pulse were demonstrated. Tremor and palpitations were mild and related to the dose. These data suggest that treatment once daily with bambuterol hydrochloride in a dose of 10 or 20 mg improves pulmonary function and is well tolerated as bronchodilator therapy in elderly patients with asthma.

Aged↗
PubMed1992

Pharmacokinetics and pharmacodynamics of bambuterol, a long-acting bronchodilator pro-drug of terbutaline, in young and elderly patients with asthma.

Disposition and efficacy of bambuterol were studied in 10 younger (20 to 37 years) and 10 older (69 to 76 years) patients with asthma (nine men and 11 women) at steady state, after single daily doses of 20 mg (50 mumol) for 1 week. There was a greater area under the concentration versus time curve for terbutaline during a dose interval in older patients compared with younger patients (558 +/- 171 and 376 +/- 149 nmol.hr/L, respectively [mean +/- SD], p less than 0.021). This was reflected in a lower apparent plasma terbutaline clearance in older patients compared with younger patients (1.22 +/- 0.33 and 2.32 +/- 1.26 L/hr/kg, respectively, p less than 0.023). Peak drug concentration was not different by age. Plasma cholinesterase levels were depressed by about 70% in both groups compared with pretreatment activity. Peak expiratory flow rate increased in both groups. Improvement in forced expiratory volume in 1 second and forced vital capacity was detected only in the younger patients. A small decrease in heart rate and diastolic blood pressure occurred in both patient groups. Bambuterol appears to offer the possibility of once-daily therapy in both younger and older patients with asthma.

Adult↗
PubMed1992

Christmas candy maker's asthma. IgG4-mediated pectin allergy.

We evaluated a 29-year-old candy maker with no history of asthma who developed asthma after exposure to pectin, a compound manufactured from fruits and fruit rinds. Following eight years of employment during which he added pectin to a recipe for Christmas candies, the candymaker developed acute respiratory symptoms. Challenge testing with the pectin mixture caused a 40 percent decrease in FEV1. Skin prick testing was positive to the pectin extract. Total IgE was normal and pectin-specific IgE antibodies were not detected. A strongly positive pectin-specific IgG4 antibody response was present that was not detected in a control serum and could be inhibited by the addition of pectin. Antigen-specific IgG4 should be sought in IgE negative cases of occupational asthma.

Adult↗
PubMed1989

Chronic respiratory disorders related to farming and exposure to grain dust in a rural adult community.

In a survey of chronic respiratory symptoms and airflow obstruction of a rural population aged 20-65 years, the effects of both farming and, in particular, the exposure to grain dust on the respiratory health of the people was examined. Of the 1,892 subjects (82% of the eligible population) studied, 924 were males and 968 females, with half living in the town. Three groups were identified: current, former, and never farmers. Almost all current farmers were exposed to grain for, on average, 2 months a year. There was no difference in atopic status between the groups. While there was a strong association between most symptoms and smoking, there was no association between symptoms and exposure to grain and farming category once age and smoking had been taken into account. Results of this study suggest that farmers do not have chronic respiratory symptoms or impairment of lung function because of their exposure to grain dust. Lung function of former farmers might have been affected by farming, and this may reflect more involvement with livestock in the past.

Adult↗
PubMed1988

Sarcoidosis as a cause of linitis plastica.

We report a patient with gastric sarcoidosis. After initial pulmonary sarcoidosis, which responded to corticosteroids, the patient developed linitis plastica of the stomach which was treated by partial gastrectomy and steroids.

Adenocarcinoma, Scirrhous↗
PubMed1987

Antibiotic therapy in exacerbations of chronic obstructive pulmonary disease.

The effects of broad-spectrum antibiotic and placebo therapy in patients with chronic obstructive pulmonary disease in exacerbation were compared in a randomized, double-blinded, crossover trial. Exacerbations were defined in terms of increased dyspnea, sputum production, and sputum purulence. Exacerbations were followed at 3-day intervals by home visits, and those that resolved in 21 days were designated treatment successes. Treatment failures included exacerbations in which symptoms did not resolve but no intervention was necessary, and those in which the patient's condition deteriorated so that intervention was necessary. Over 3.5 years in 173 patients, 362 exacerbations were treated, 180 with placebo and 182 with antibiotic. The success rate with placebo was 55% and with antibiotic 68%. The rate of failure with deterioration was 19% with placebo and 10% with antibiotic. There was a significant benefit associated with antibiotic. Peak flow recovered more rapidly with antibiotic treatment than with placebo. Side effects were uncommon and did not differ between antibiotic and placebo.

Aged↗
PubMed1986

Human asthma due to a dog's drugs.

A woman had a recurrence of asthma due to sensitization to her dog's pancreatic enzyme powder. The cause of her asthma was confirmed by bronchial inhalation challenge, and specific IgE antibodies against the enzymes were found in her serum but not in that of control subjects.

Animals↗
PubMed1986

Induction of histamine release in vitro from rat peritoneal mast cells by extracts of grain dust.

The ability of extracts of grain dust and wheat to induce histamine release from rat peritoneal cells was investigated. Some grain dusts, with a high endotoxin content, were found to produce cytotoxic histamine release. Extract of wheat dust, with a low endotoxin release, produced noncytotoxic histamine release from peritoneal cells but not from purified mast cells. This reaction was dependent on the presence of phosphatidyl serine. The agent did not appear to be a lectin because histamine release was not enhanced by passive sensitization of mast cells with IgE. The activity occurred only over a narrow range of concentrations of the extract of wheat. The cause was unclear.

Animals↗
PubMed1986

Acute symptoms following exposure to grain dust in farming.

History of acute symptoms (cough, wheezing, shortness of breath, fever, stuffy nose, and skin itching/rash) following exposure to grain dust was obtained from 661 male and 535 female current and former farmers. These symptoms were relatively common: 60% of male and 25% of female farmers reported at least one such symptom on exposure to grain dust. Association of cough, wheezing, shortness of breath, and stuffy nose with skin reactivity and capacity to form IgE is consistent with an allergic nature of these symptoms. Barley and oats dust were perceived as dust most often producing symptoms. On the other hand, grain fever showed a different pattern, i.e., it was not associated with either skin reactivity or total IgE. Smoking might modify the susceptibility to react to grain dust with symptoms. Only those who reported wheezing on exposure to grain dust may have an increased risk to develop chronic airflow obstruction.

Adult↗