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Biomedical subjects

P S Clarke

Publications and source records attributed to P S Clarke.

At least 19 recordsLinked to original sources
PubMed1992

Titration of immunotherapy by periodical nasal allergic challenges in the treatment of allergic rhinitis.

OBJECTIVE: To determine the benefits of nasal allergen challenge (NAC) in monitoring immunotherapy for allergic rhinitis in a clinical setting. DESIGN: Two hundred consecutive courses of immunotherapy, with pyridine-extracted alum-precipitated allergen extracts (Allpyral), were personally carried out by the writer and analysed. Diagnosis before treatment was confirmed by NAC and the duration of treatment determined by periodical NAC. SETTING: Consultant allergist's clinical practice. PARTICIPANTS: Patients with allergic rhinitis who were referred for treatment; 79 patients were allergic to grass, 70 to the house dust mite, 30 to plantain and 21 to miscellaneous allergens. RESULTS: The mean protein nitrogen units (pnu) required to reverse an NAC was 145 467 pnu for grass, 93 771 pnu for mite, 103 137 pnu for plantain, and 121 030 pnu for miscellaneous allergen patients. The range of injections to obtain conversion to a negative NAC was wide. For grass it was 9-58 injections, for mite 6-47 injections, for plantain 4-39 injections, and for miscellaneous allergens 10-79 injections. Ten grass-sensitive patients who received an average of 477 807 pnu failed to convert to a negative NAC result. Similarly, two mite-sensitive patients who received 467 370 PNU, and one plantain-sensitive patient, one cat-sensitive patient and one horse-sensitive patient, who had 389 240 pnu, 148 520 pnu and 719 540 pnu respectively, failed to convert. One patient who was very sensitive to grass pollen developed urticaria which required an injection of adrenaline. CONCLUSION: Immunotherapy for allergic rhinitis with Allpyral is effective--as determined by the conversion of NAC results from positive to negative--providing a sufficient dose is given. The manufacturer's recommended dose is inadequate. The procedure is safe for mite, plantain and miscellaneous allergens, and only one reaction occurred with grass given in a high dosage protocol, which has subsequently been altered. Considering that the British Committee of Safety of Medicines reported no deaths from Allpyral injections, its recommendations appear over cautious for this make of extract.

Allergens↗
PubMed1990

Effect of fenoterol hydrobromide and sodium cromoglycate individually and in combination on postexercise asthma.

A double-blind trial involving 20 asthmatic patients was carried out to test the effect of fenoterol and sodium cromoglycate alone and in combination on ventilatory function one hour after medication. The results show that fenoterol, whether alone or in combination with sodium cromoglycate, can increase the forced expiratory volume in one second (FEV1) by up to 25% both after rest and after exercise. No patient suffered a decrease in FEV1 using fenoterol, and at least 80% of them recorded an increase in ventilatory ability. Sodium cromoglycate was of no benefit in eliminating early reaction to exercise-induced asthma.

Asthma↗
PubMed1988

Improved diagnosis and treatment of allergic rhinitis by the use of nasal provocation tests.

A simple and safe method of nasal provocation for out-patients that requires no special equipment is described. A total of 2,645 cases were tested by nasal provocation tests. Of the total, 1,175 were tested with Dermatophagoides pteronyssinus, 825 with mixed grass pollens, 352 with plantain (Plantago lanceolata), and 125 for cats and correlating nasal tests with skin tests yielded 80%, 90%, and 85%, respectively. Immunotherapy for allergic rhinitis was only considered justifiable when the nasal provocation test was positive. The nasal provocation test was repeated at the end of the normal course of injections recommended by the manufacturer. If the nasal provocation test was still positive, further injections were given until the test became negative. This method of improving diagnostic accuracy and monitoring results of immunotherapy was used with both aqueous extracts which were used for skin testing (Australian Government Commonwealth Serum Laboratories) and with Allpyral pyridine-extracted alum-precipitated extracts (Dome Laboratories, England). The number of injections of allergen required to convert a positive nasal provocation test to negative varied from 26 to 69 for mite aqueous injections with only 12 to 19 for mite suspension and 47 to 98 for grass aqueous injections compared with 12 to 36 for grass suspension. Direct provocation tests of the nose should give a more accurate diagnosis than RAST or skin tests and are required for monitoring therapy because considerable individual variations in sensitivity and response to treatment were demonstrated. Standard dosage schedules are not suitable for individual patients, who should have their immunotherapy personalized.

Allergens↗
PubMed1987

The diagnosis of perennial rhinitis due to house dust mite (Dermatophagoides pteronyssinus) demonstrated by nasal provocation tests.

The paper describes a simple clinical method of performing allergic nasal challenges. It was found to give no complications in over 1,000 challenges with D. pteronyssinus solution. It requires no special apparatus. Reasons for not measuring nasal airways resistance are given. In 1,167 challenges, positive nasal challenges agreed with positive skin prick tests 943 times (81%). Twenty-five positive nasal tests had negative skin tests (2%). One hundred and ninety-nine negative nasal tests had positive skin tests (17%). In 60 patients who had positive RAST (Fadel-Nalebuff modification), 14 (23%) nasal challenges were negative. Five positive nasal challenges had negative RASTS (8%). This is the largest series of mite nasal challenges correlated to skin and RAST tests that has been published.

Airway Resistance↗
PubMed1982

The effect of beclomethasone diproprionate on bronchial hyperreactivity.

BDP is a useful treatment for asthma, but the mechanism of its action is unknown. Routine estimations of bronchial sensitivity to histamine aerosols showed that there was a decrease in bronchial hyperreactivity in 11 out of 14 cases given BDP as a routine treatment. The results are significant by Student's t-test (P less than .001) and reveal one mechanism by which BDP can act in the lungs.

Adolescent↗
PubMed1982

The protective effect of ipratropium bromide aerosol against bronchospasm induced by hyperventilation and the inhalation of allergen, methacholine and histamine.

The ability of the anticholinergic agent, ipratropium bromide, Atrovent, (40 mcg from a metered dose inhaler) to prevent bronchoconstriction produced by four different provocation tests was compared with placebo in 12 asthmatic patients. The provocation tests used were hyperventilation and inhalations of histamine, methacholine and an allergen to which the subject was known to be sensitive. The order in which each patient received the tests was determined according to a Latin-square design and remained the same on both test days. Pretreatment with ipratropium bromide and placebo was allocated randomly and administered in double-blind fashion. Ipratropium bromide provided significant protection at the 5% level against all four types of challenge. The average number of breaths required to produce a fall of at least 20% in FEV1 (forced expiratory volume in one second) was doubled for both histamine and allergen and increased by a factor of six for methacholine. The fall in FEV1 induced by hyperventilation was approximately halved. No side effects were noted with ipratropium bromide.

Adolescent↗
PubMed1980

Asthma hyperventilation and emotion.

Hyperventilation in asthmatic subjects causes airways obstruction as demonstrated by a fall in the Forced Expiratory Volume in one second. Clinically, measurements of blood gases during asthmatic attacks have shown that asthmatic subjects, who hyperventilate have a blood carbon dioxide level below normal unless ventilatory failure occurs. Two methods of demonstrating that asthmatic subjects hyperventilate on the thought of asthma were employed. 1. Chronic asthmatic subjects had their respiratory minute volume measured during relaxation and at the recall of an asthmatic attack. The mean minute volume rose from 10.1 litres when relaxed to 13.5 litres when recalling an asthmatic attack (p < .025). 2. Asthmatic volunteers had their respiratory minute volume measured during relaxation and on the hypnotic suggestion of anger, fright and asthma and pleasurable excitement, both in the conscious state and under hypnosis. The data were statistically treated by an analysis of variance. All emotion resulted in a significant increase in minute volume at the 0.1 level of significance.

Aged↗