Worker exposure to paraquat and diquat.
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Biomedical subjects
Publications and source records attributed to J F Price.
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In children with perennial asthma, dual (immediate and late) reactions in the skin to D. pteronyssinus and Timothy grass pollen were more frequent with high doses of antigen and were associated with large immediate reactions. The frequency of dual bronchial or nasal reactions was not related to the size of the immediate reaction and dual reactions were commonly elicited to the lowest antigen dose which would elicit an immediate reaction. Serum IgG, IgA, IgM or IgE concentrations, IgE or IgG antibodies to the antigens and defective yeast opsonization did not differ in children with dual or immediate only reactions in skin, nose or lung. In five patients undergoing bronchial provocation tests with D. pteronyssinus there was no fever, no fine crepitations in the lungs and no significant change in the levels of C3.
Twenty six infants with a congenital immunodeficiency, characterised by failure of their sera to opsonise heat killed bakers' yeast for phagocytosis by normal polymorphonuclear leucocytes, were studied during infancy to determine the frequency of infection and development of atopy. They were compared with controls, matched prospectively for birth date, sex, parental smoking, and atopy and in whom feeding patterns were similar. In 18 of 26 infants the serum defect persisted at age one year. The incidence of infection and atopy, was appreciably greater in the study group than in controls. The 8 children in whom the defect was transient had a similar incidence of infection but a higher incidence of atopy than controls. Eight of 26 mothers and four of 9 fathers tested also had the serum defect, suggesting a strong genetic component. We support the hypothesis that immunodeficiency predisposes to infection and atopy, and that transient immunodeficiency predisposes to atopy.
Forty six of 142 infants weighing less than 1500 g at birth, who had chest radiographs in the first 5 days of life, developed pulmonary interstitial emphysema (PIE) and in 19 this occurred in the first 24 hours. PIE was seen more frequently in infants weighing less than 1000 g at birth (24 of 57) than in those weighing 1000-1500 g (22 of 85). Ventilation for hyaline membrane disease was strongly associated with PIE, and only babies who were resuscitated, or ventilated, or had hyaline membrane disease developed the disorder. Most pneumothoraces were preceded by x-ray appearances of PIE (17 of 21). Mortality was increased in ventilated infants who developed PIE and was high in those with severe x-ray changes.
1. Transnasal pressure (delta p) in Pa and gas flow in cm3 s-1 were measured in men breathing gases of different density, assuming flow through each nostril (f) to be half the measured total flow. Measurements were also made in children with allergic rhinitis before and after nasal antigen challenge. 2. Flow always showed evidence of turbulence when transnasal pressure exceeded 40-80 Pa breathing air and Reynolds number exceeded 2400 (1800 in the presence of nasal obstruction). 3. Changes in effective mean nasal airway diameter (D) after nasal challenge can be determined at points of similar pressure from the relation log (D2/D1) = 0.368 log (f2/f1) when flow is turbulent. 4. Absolute estimates of airway diameter in cm can be obtained from the relation 4.75 log D = 1.75 log f--log delta p+log L--4.756 breathing air when flow is turbulent (since the relation between pressure and flow approximates to that found in a long cylinder) and these estimates are only marginally affected by differing assumptions about nasal airway length (L). 5. Because pressure and flow are non-linearly related, and changing nasal dimensions have a profound effect on the flow at which turbulence occurs, it is suggested that measures of nasal conductance at delta p greater than or equal to 0.1 kPa are preferable to the more conventional measures of nasal resistance at a specified flow rate.
Sera from 30 of 303 (9.9%) unselected term newborn infants were deficient in their ability to opsonize heat-killed baker's yeasts, an incidence which is almost double that seen in adults. Genetic influence is important in some since the mothers of 10 infants with defective opsonization showed the same defect, but it was not related to the sex or race of the infant or to the atopic state of the parents. In others the defect could be due to a functional maturation delay of the complement system, but not to inhibitory factors in neonatal serum since correction of opsonization was achieved with subopsonizing amounts of normal sera. Significantly more infants had sera with high opsonizing capacity (greater than 80% yeasts phagocytosed) when compared with adults; perhaps antibody independent immune mechanisms like this are important in the newborn. This study shows that a common specific immunodeficiency which may predispose to severe infection or atopy can be identified at birth.
Most (18/21) children with perennial asthma gave dual (immediate and late) responses to bronchial provocation with two of Dermatophagoides pteronyssinus, and either timothy grass pollen or cat fur. Most (19/21) also showed dual responses to skin prick tests, only half (11/21) gave dual responses in the nose, mainly with timothy grass pollen, and these were associated with allergic rhinitis. Only two children gave dual responses in lung, skin and nose to both antigens, and only two gave immediate reactions without late reactions in all positive tests; most showed different patterns of response according to the organ tested or the antigen used for provocation. Our results suggest that local factors may be important in determining the pattern of allergic response in a 'target' organ, and that dual responses are strongly associated with the patient's symptoms.
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Ten of fifteen cystic fibrosis children with positive skin prick tests to common antigens gave an immediate bronchial reaction to the antigen inhaled, five of them also gave a late reaction; however only one gave a history of asthma. The antigen most commonly eliciting a positive skin reaction in cystic fibrosis patients is Aspergillus fumigatus. In six children tested to this antigen the bronchial response varied, two were negative, one gave an immediate reaction and three gave a dual (immediate and late) reaction. None of the children showed the characteristic pattern of response to exercise seen in asthmatic patients, an initial rise in Peak Expiratory Flow Rate followed by a fall of greater than 14% below the resting level. Two patients showed an abnormal rise in Peak Expiratory Flow Rate during exercise, a pattern described previously in cystic fibrosis. The results suggest that bronchial allergy, immediate or late does completely explain susceptibility to asthma, and that other factors including perhaps the type of bronchial reactivity shown by bronchoconstriction after exercise may be required. However the majority of the children tested had bronchial allergy and anti-allergy therapy such as inhaled sodium cromoglycate may have a place in the management of selected patients with cystic fibrosis.
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Hyposensitisation with Dermatophagoides pteronyssinus tyrosine absorbate in asthmatic children with bronchial sensitivity to D. pteronyssinus was effective in a 12-month double-blind controlled clinical trial. Compared with controls, treated children used a smaller quantity of drugs while maintaining clinical and lung function improvements. In most children who improved there was no change in immediate response to D. pteronyssinus on bronchial provocation test, but the late reaction was lost in half the patients and these showed the greatest improvement in symptoms.
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The clinical features of perennial asthmatic children with a skin or bronchial reaction to the house dust mite (Dermatophagoides pteronyssinus) were compared with those of asthmatic children without mite sensitivity. Mite sensitive asthma was characterised by an early age of onset of symptoms, these being predominantly nocturnal. A history of wheezing precipitated by dust exposure, during vacuuming, bedmaking, or dusting was present in 52% of cases. Asthmatic children with mite sensitivity were more likely to have been born at the time of the year when mite counts were highest. This was consistent with the idea that allergy may be associated with a period of susceptibility to sensitisation in early infancy.
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Forty-two children with eczema were studied for exercise-induced asthma (EIA), skin sensitivity to prick testing, blood eosinophil count, and immunoglobulins. 29 had a fall in peak expiratory flow rate after exercise greater than 20% and of these, 23 had symptoms of wheezing. 13 of the eczematous children showed a fall of less than 20%. The children with EIA showed greater cutaneous sensitivity (p less than 0.001) and a higher total serum IgE (p less than 0.025). 3 of the group with a fall of less than 20% had allergic rhinitis with skin sensitivity to grass pollen. The remaining 10 had no clinical evidence of allergic disease, other than eczema and skin sensitivity, and total IgE fell within the normal range. It is suggested that in a proportion of chilren with eczema there is little evidence of reaginic allergy.
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Considerable salt-soluble protein degradation was observed in pork muscle inoculated with Pseudomonas fragi. During a 20-day incubation period at 10 C, the samples proceeded to rank spoilage or putrefaction. There was a large decrease in the salt-soluble protein fraction and a corresponding increase in nonprotein nitrogen. Disc gel electrophoretic patterns showed that breakdown of the salt-soluble proteins had occurred after incubation for 20 days. During incubation for 10 days at 10 C, P. fragi produced large amounts of extracellular proteolytic activity in ground pork. Most of the proteolytic activity appeared immediately after spoilage occurred. However, a significant increase in the ability to hydrolyze casein and a slight increase in the ability to hydrolyze denatured hemoglobin occurred prior to spoilage.