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M Pedersen

Publications and source records attributed to M Pedersen.

152 records · Page 9Linked to original sources
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Starch-encapsulated chlorpyrifos: release rate, insecticidal activity and degradation in soil.

Incorporation of chlorpyrifos into starch matrices was achieved by thermal gelatinization. The level of amylose content in the starch matrices (10 and 52%) and the addition of auxiliary agents, i.e. solvent, emulsifiers or both, were varied and eight different formulations were prepared. According to differential scanning calorimetry (DSC) and X-ray diffraction measurements, chlorpyrifos was partly present in a crystalline form in all the starch formulations. The formulations had controlled release properties, and the release rate into water could be described by a linear model. In a bioassay, the formulations killed all larvae of the cabbage root fly at a dosing of 1.4 kg a.i. per ha. The degradation of chlorpyrifos in soil from the starch formulations could be described in a non-linear logistic model and the half-life was predicted to be 88 days. Differences in the amount of amylose in the starch as well as the addition of solvent and emulsifiers in the preparation procedure had no systematic influence on the release rate, the insecticidal effect and the degradation rate. No correlation between release rate into water and degradation in soil could be established. Two commercial chlorpyrifos formulations Lorsban 15 G (granular) and Cyfos 500 gl(-1) (emulsifiable concentrate), were included in the study for comparison.

Algorithms↗
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Retrospective clinical study of hypersensitivity reactions to aztreonam and six other beta-lactam antibiotics in cystic fibrosis patients receiving multiple treatment courses.

A total of 2,793 courses of treatment with seven beta-lactam antibiotics were administered to 121 cystic fibrosis patients chronically infected with Pseudomonas aeruginosa, and the patients were evaluated with respect to clinical hypersensitivity reactions. Seventy-five patients (62%) experienced 125 reactions, for an overall frequency (based on the number of courses) of 4.5%. Immediate reactions occurred in 34 patients (28.1%) during 53 courses (1.9%). The highest rate of reactions involved piperacillin (50.9% of patients), and the lowest rate involved imipenem and aztreonam (4.0% and 6.5% of patients, respectively); intermediate reaction rates were noted for carbenicillin (23.6% of patients), azlocillin (20.8%), cefsulodin (17.1%), and ceftazidime (13.0%). Cross-reactivity did not appear to be a major problem. Reactions to aztreonam seemed to be restricted to a small group of patients with a high propensity for beta-lactam hypersensitivity.

Anti-Bacterial Agents↗
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Primary and secondary ciliary dyskinesia.

It has recently been shown that patients with Kartagener's triad and also some subjects with similar symptoms, but without situs inversus, have a congenital abnormality of cilia as an explanation for their chronic airway symptoms; this disease has been named "the immotile-cilia syndrome" or more correctly "primary ciliary dyskinesia". Studying 27 such patients, we have found daily nose blowings since birth, chronic-recurrent sinusitis, and chronic secretory otitis media highly characteristic features. The frequency of common colds was not increased, and most patients did not suffer from repeated episodes of acute purulent otitis media. The number of ciliated cells with immotile cilia was increased, but only a single patient had completely immotile cilia; also the degree of asynchrony within the single ciliated cell was increased. Electron microscopy showed a decreased number of dynein arms in some patients, and abnormal arrangement of microtubules in others. Some patients, however, had normal ultrastructure, and this appeared to be associated with a hyperfrequent beating pattern. At least three subgroups of patients with primary ciliary dyskinesia can be delineated based on the motility-ultrastructure studies. Bacterial infection tends to reduce the number of ciliated cells with motile cilia, and viral infection (common cold) gives a very marked and long-lasting reduction in the number of ciliated cells. This may account for some otherwise unexplainable subchronic symptoms from nose and throat.

Adolescent↗
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Study of bacteria in the nasal cavity and nasopharynx during naturally acquired common colds.

It was the purpose of this study to examine whether the number of bacteria in the nose and nasopharynx changes during a common cold. Samples for bacteriological culture were taken from the nasal cavity of 29 and from the nasopharynx of 26 adult patients with naturally acquired colds. The bacteriological samples were taken on days 2, 4, 8 16, 32 and 64 after the first nasal symptoms. The results showed that there were few pathogenic bacteria in the nasal cavity and nasopharynx. There was no tendency to an increase in the number of positive cultures during the cold, although most patients had macroscopically purulent discharge on days 3-5. In conclusion, the study indicates that during an uncomplicated common cold, a bacterial infection is not responsible for the occurrence of purulent nasal discharge which may be a direct consequence of the viral infection.

Adult↗